WO2020095796A1

WO2020095796A1 - Coated particle, electrically conductive material comprising same, and method of manufacturing coated particle

Info

Publication number: WO2020095796A1
Application number: PCT/JP2019/042620
Authority: WO
Inventors: 裕之稲葉; 智真成橋
Original assignee: 日本化学工業株式会社
Priority date: 2018-11-07
Filing date: 2019-10-30
Publication date: 2020-05-14
Also published as: TW202031936A; CN112740338A; KR20210083246A; CN112740338B; TWI820245B; JP6825170B2; JPWO2020095796A1

Abstract

The purpose of the present invention is to provide a coated particle in which an insulating layer coats the surface of an electrically conductive particle, wherein the surface of the electrically conductive particle and the insulating layer has excellent adhesion.　This coated particle comprises: an electrically conductive particle which has a metal film formed on the surface of a core and has a titanium compound having a hydrophobic group arranged on the surface of the metal film opposite the core; and an insulating layer that coats the electrically conductive particle, wherein the insulating layer comprises a compound containing a charged functional group. It is preferable that the insulating layer has a plurality of fine particles arranged in layers or is a continuous film. It is also preferable that the hydrophobic group is an aliphatic hydrocarbon group having 2 to 30 carbon atoms.

Description

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

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

Conductive particles in which a metal film such as nickel or gold is formed on the surface of resin particles are used as a conductive material such as a conductive adhesive, an anisotropic conductive film, or an anisotropic conductive adhesive.
In recent years, with further miniaturization of electronic devices, the circuit width and pitch of electronic circuits have become smaller and smaller. Accordingly, as the conductive particles used for the above-mentioned conductive adhesive, anisotropic conductive film, anisotropic conductive adhesive, etc., those having a small particle size are required. When the 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 compounding 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 between the counter electrodes, and it is difficult to obtain insulation in that direction. ing.

In order to solve the above problems, the surface of the conductive particles is coated with an insulating substance having a functional group having an affinity for the metal film to prevent contact between the metal films of the conductive particles. Insulating layer coated conductive particles have been used. In such conductive particles, a technique is known in which the metal surface is preliminarily surface-treated with an organic treatment agent before being coated with an insulating substance.

For example, Patent Document 1 describes that a 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 insulating particles having an ammonium group are attached to the treated conductive particles.

JP, 2014-29857, A International Publication 2016/063941 Pamphlet

With conductive particles coated with insulating particles, improving the adhesion between the insulating particles and the conductive particles was a problem. The adhesiveness between the insulating particles and the conductive particles is important in achieving electrical conduction between the counter electrodes while obtaining insulation in a direction different from that of the counter electrodes (hereinafter, also simply referred to as connection reliability). In this regard, Patent Documents 1 and 2 are for treating the metal surface of the conductive particles with an organic treatment agent for the purpose of rust prevention and oxidation prevention, and consider the adhesion between the insulating particles and the conductive particles. Not a thing. Therefore, an object of the present invention is to provide an insulating layer-covered conductive particle that can solve the problems of the above-mentioned conventional techniques.

As a result of intensive studies to solve the above problems, the present inventors have found that when an insulating layer containing a functional group having a charge is used, a titanium-based compound having a hydrophobic group on the surface of conductive particles is used. The present invention completes the present invention by discovering that the insulating layer has excellent affinity with the conductive particles having a titanium-based compound, and that the coverage of the insulating material on the conductive particles is further increased as compared with the conventional technique. did.

That is, the present invention is a conductive particle having a metal coating formed on the surface of the core material, a titanium-based compound having a hydrophobic group, which is disposed on the outer surface of the metal coating, and the conductive particles having the titanium-based compound. The present invention provides coated particles having an insulating layer coating the surface of the above, wherein the insulating layer has a compound containing a functional group having a 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 preferred embodiments.
The coated particles of the present embodiment, a metal coating is formed on the surface of the core material, and the outer surface of the metal coating is coated with conductive particles in which a titanium compound having a hydrophobic group is arranged, and the conductive particles are coated. And an insulating layer to
The insulating layer has a compound containing a charged functional group. The outer surface of the metal coating means the surface of the metal coating opposite to the core material.

As the conductive particles, known particles that have been conventionally used for conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives can be used.
The core material of the conductive particles is in the form of particles, and may be an inorganic material or an organic material without particular limitation. 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 water-containing substances), and aluminosilicates. Examples thereof include metal silicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal salts, metal halides and carbon. On the other hand, examples of the organic material core particles include thermoplastics such as natural fiber, natural resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic ester, polyacrylonitrile, polyacetal, ionomer, and polyester. Examples thereof include resins, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins and diallyl phthalate resins. These may be used alone or in combination of two or more. Among these, the core particles made of a resin material are preferable in that the specific gravity is smaller than that of the core particles made of a metal, it is difficult to settle, the dispersion stability is excellent, and the electrical connection is easily maintained by the elasticity of the resin. ..

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

When an organic material is used as the core material particles and the organic material is a highly crosslinked resin, the glass transition temperature is hardly observed even when an attempt is made to measure up 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 particle material having no such glass transition temperature, it may be obtained by copolymerizing a monomer constituting the organic material exemplified above with a crosslinkable monomer. 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, tetraethylene oxide. (Meth) acrylate, 1,6-hexanedi (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane di ( (Meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, tetramethylolpropane tetra (meth) acrylate, dipentaene Polyfunctional (meth) acrylates such as thritol penta (meth) acrylate, glycerol di (meth) acrylate and glycerol tridi (meth) acrylate, polyfunctional vinyl monomers such as divinylbenzene and divinyltoluene, vinyltrimethoxysilane, Examples thereof include silane-containing monomers such as trimethoxysilylstyrene and γ- (meth) acryloxypropyltrimethoxysilane, and monomers such as triallyl isocyanurate, diallyl phthalate, diallyl acrylamide and diallyl ether. Particularly in the COG (Chip on Glass) field, many core particles made of such a hard organic material are used.

The shape of the core material particles is not particularly limited. Generally, the core particles are spherical. However, the core material particles may have a shape other than spherical, 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 amorphous shape. In the present invention, spherical core particles are preferable because they are excellent in filling property and can be easily coated with a metal.
The shape of the conductive particles depends on the shape of the core particles, but is not particularly limited. For example, it may have a fibrous shape, a hollow shape, a plate shape, or a needle shape, and may have a protrusion on its surface or an amorphous shape. In the present invention, a spherical shape or a shape having protrusions on the surface is preferable in terms of excellent filling properties and connectivity. When the conductive particles have a shape having protrusions on the surface, it preferably has a plurality of protrusions on the surface, and more preferably has a plurality of protrusions on a spherical surface. When the conductive particles have a shape having a plurality of projections, the core material particles may have a plurality of projections, or the core material particles do not have a projection and the metal coating has a plurality of projections. May be Preferably, the core material particles do not have protrusions, and the metal coating has a plurality of protrusions.

The coated particles of the present invention have a titanium-based compound disposed on the surface of the metal film, and the insulating layer has a compound containing a functional group having a charge, whereby the insulating layer has excellent adhesion to the conductive particles. In order to ensure electric conduction, the conductive particle surface may have a protrusion. Since the conductive particles have the protrusions on their surfaces, when the conductive particles are compressed by the electrodes during mounting, the protrusions can effectively repel the insulating layer. The height H of the protrusions of the conductive particles is H / L of 0.1 or more, where L is the thickness of the insulating layer, and the insulating layer is eliminated during mounting to ensure electrical conduction. It is preferable from the standpoint of controlling Further, H / L is preferably 10 or less from the viewpoint of filling property and insulating property in a direction different from that of the counter electrode. From these points, H / L is more preferably 0.2 or more and 5 or less. In these preferable ranges, the thickness L refers to the average particle diameter 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 on average, and particularly 50 nm or more. The number of protrusions depends on the particle diameter of the conductive particles, but it is preferably 1 to 20,000, and particularly 5 to 5000, per particle from the viewpoint of further improving the conductivity of the conductive particles. .. The aspect ratio of the protrusion is preferably 0.3 or more, more preferably 0.5 or more. A large aspect ratio of the protrusions is advantageous because the oxide film formed on the electrode surface can be easily pierced. The aspect ratio is a ratio defined by the height H of the protrusion and the length D of the base of the protrusion, that is, a value defined by 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 particles observed by the electron microscope. The aspect ratio of the particles was calculated and the average value was calculated. The length D of the base means the length of the base of the protrusion along the surface of the conductive particles in an 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 portion of the protrusions is preferably 5 to 500 nm, particularly preferably 10 to 400 nm, and the height H of the protrusions is H. Is preferably 20 to 500 nm, particularly preferably 50 to 400 nm.

The conductive particles having protrusions on the surface may have insufficient coverage on the protrusions when the insulating layer is insulating fine particles. The coated particles of the present invention, since the titanium-based compound itself used in the present invention described below exhibits insulating properties, by arranging the titanium-based compound on the outer surface of the metal film, conductive particles having protrusions on the surface The insulating property can be further enhanced.

The metal film in the conductive particles has conductivity, and as the constituent metals thereof, for example, gold, platinum, silver, copper, iron, zinc, nickel, tin, lead, antimony, bismuth, cobalt, indium, In addition to metals such as titanium, antimony, bismuth, germanium, aluminum, chromium, palladium, tungsten, molybdenum, and alloys thereof, metal compounds such as ITO and solder are listed. Among them, gold, silver, copper, nickel, palladium or solder is preferable because of its low resistance, and particularly gold, silver, copper, nickel, palladium, gold alloys, silver alloys, copper alloys, nickel alloys or palladium alloys have insulating properties. It is preferably used because it has high bondability with a functional group having an electric charge in the fine particles, and it is preferable that at least one selected from these metals is contained. The metal in the metal coating 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, the outermost layer is preferably gold, silver, copper, nickel, palladium, gold alloy, silver alloy, copper alloy, nickel alloy or palladium alloy.

Further, the metal film may not cover the entire surface of the core material particles, and may cover only a part thereof. When only a part of the surface of the core particle is coated, the coating site may be continuous, for example, may be discontinuously coated in an island shape. The thickness of the metal coating is preferably 0.001 μm or more and 2 μm or less. When the metal coating has protrusions, the thickness of the metal coating here does not include the height of the protrusions.

As a method for forming a metal film on the surface of the core material particles, there are a vapor deposition method, a sputtering method, a dry method utilizing a mechanochemical method, a hybridization method, etc., a wet method utilizing an electrolytic plating method, an electroless plating method and the like. Can be mentioned. Moreover, you may form a metal film on the surface of a core material particle combining these methods.

The conductive particles have a titanium compound on the outer surface of the metal coating. When the conductive particles have a titanium-based compound on the surface, it is easy to adhere to the insulating layer having a charge, thereby making it possible to obtain a sufficient coverage with the insulating layer on the surface of the conductive particles and to prevent the insulating layer from the conductive particles. Peeling is effectively prevented. Therefore, the effect of preventing the short circuit by the insulating layer in the direction different from the direction between the opposed electrodes is likely to be exhibited, and the improvement of the insulating property in the direction can be expected.
Therefore, the coated particles of the present invention can improve connection reliability.

As the titanium 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 compound include organic groups, and the number of carbon atoms thereof is preferably 2 or more and 30 or less from the viewpoint of availability and affinity with the insulating layer. From the same viewpoint, as the hydrophobic group in the titanium-based compound, an aliphatic hydrocarbon group having 2 to 30 carbon atoms, an aryl group having 6 to 22 carbon atoms, and an arylalkyl group having 7 to 23 carbon atoms Are preferred. 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 to 30 carbon atoms include a linear or branched saturated aliphatic hydrocarbon group and an unsaturated 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 group. Group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group and the like. Examples of unsaturated aliphatic hydrocarbon groups include alkenyl groups such as dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, nonadecenyl group, icosenyl group, eicosenyl group, henicosenyl group, and docosenyl group. Be done.
Examples of the aryl group having 6 to 22 carbon atoms include phenyl group, tolyl group, naphthyl group and anthryl group.
Examples of the arylalkyl group having 7 to 23 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 increasing the affinity between the insulating layer and the conductive particles, the aliphatic hydrocarbon group as the hydrophobic group is particularly preferably one having 4 to 28 carbon atoms, and most preferably 6 to 24. preferable.

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

(R ¹² is a divalent or trivalent group, R ¹³ is an aliphatic hydrocarbon group having 4 to 28 carbon atoms, an aryl group having 6 to 22 carbon atoms, or an aryl group having 7 to 23 carbon atoms. It is an arylalkyl group, p and r are each an integer of 1 or more and 3 or less, satisfy p + r = 4, q is an integer of 1 or 2, and when 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 ¹³ may be the same or different, and * represents a bond. )

Examples of the aliphatic hydrocarbon group having 4 to 28 carbon atoms represented by R ¹³ include those listed as examples 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—, —OSO ₂ — and the like. Examples of the trivalent group represented by R ¹² include -P (OH) (O-) ₂ and -OPO (OH) -OPO (O-) ₂ .

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 or group. In that case, other atoms, groups and the like include those described in the general formula (I ′) described later.

As the titanium-based compound having the structure represented by the general formula (I), a compound having a structure in which R ¹² in the general formula (I) is a divalent group is easily available or has a conductive property of conductive particles. It is preferable in that it can be processed without damage. A 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 have the same meanings as in 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 compound may or may not be chemically bonded to the metal on the surface of the conductive particles. For example, the titanium compound may be chemically bonded to the metal film by the bond in the general formulas (I) and (II) as described above. The chemical bond includes covalent bond and electrostatic bond.

The titanium-based compound may be present on the surface of the conductive particles, in which 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 for the insulating layer having a charged functional group on the surface becomes high.

In order to allow the titanium-based compound to be present on the outer surface of the metal coating of the conductive particles, the conductive particles may be surface-treated with the titanium-based compound in the preferred method for producing coated particles described below.

The average particle diameter of the conductive particles is preferably 0.1 μm or more and 50 μm or less, 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 short-circuit in the obtained coated particles in a direction different from that between the counter electrodes. In addition, in this invention, the average particle diameter of a conductive particle is an average value of the particle diameter measured using the scanning electron microscope (Scanning Electron Microscope: SEM). When the conductive particles have a spherical shape in the scanning electron microscope image, the particle size measured by SEM is the diameter of a circular conductive particle image. When the insulating fine particles are not spherical, the particle size measured by SEM means the largest length (maximum length) of the line segment that crosses 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 the average particle diameter. This also applies to the average particle diameter of the insulating fine particles described later.
Specifically, the average particle diameter of the conductive particles is measured by the method described in the examples.

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

First, the case where the insulating layer is made of insulating fine particles and the fine particles contain a compound having a functional group having a charge will be described. In this case, the insulating fine particles are melted, deformed, peeled or moved by moving the conductive particle surface by thermocompression-bonding the coated particles between the electrodes to expose the metal surface of the conductive particles in the thermocompression-bonded portion, Thereby, electrical connection between the electrodes is possible and connectivity is obtained. On the other hand, in the surface portion of the coated particles that faces a direction other than the thermocompression bonding direction, the conductive particles are substantially covered with the insulating fine particles on the surface, so that conduction in directions other than the thermocompression bonding direction is prevented.
Since the insulating fine particles include a functional group having a charge on the surface thereof (hereinafter, also simply referred to as “charged functional group”), the insulating fine particles easily adhere to the conductive particles having the titanium-based compound on the surface, whereby the conductive particles are formed. The surface can be covered with the insulating fine particles at a sufficient rate, and peeling of the insulating fine particles from the conductive particles can be effectively prevented. For this reason, the effect of preventing short circuits by the insulating fine particles in the direction different from the direction between the opposing electrodes is likely to be exhibited, and improvement in the insulating property in the direction can be expected.
Further, in the coated particle 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 the insulating fine particles is easily formed on the surface of the conductive particle. Therefore, when the coated particles of the present invention are used for an anisotropically conductive material or the like, conduction defects due to thermocompression bonding due to the presence of insulating fine particles in a multi-layered structure are effectively prevented, and improved connectivity is expected. it can.
Therefore, the connection reliability can be improved by the coated particles of the present invention in which the insulating layer is composed of insulating fine particles having charged functional groups on the surface thereof.

The 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 insulating fine particles have a functional “Having a group on the surface”.

The shape of the insulating fine particles is not particularly limited, and may be spherical, or may be a shape other than spherical. Examples of shapes other than spherical shapes include fibrous shapes, hollow shapes, plate shapes, and needle shapes. Further, the insulating fine particles may have a large number of protrusions on the surface thereof or may have an irregular shape. The spherical insulating fine particles are preferable in terms of adhesion to the 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 forming 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 functional “Having a group on the surface”.

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

As the charged functional group, an onium-based functional group such as a phosphonium group, an ammonium group, or a sulfonium group is particularly preferable because the insulating layer is more likely to adhere to the conductive particles having a titanium-based compound or an amide-based compound on the surface. And a phosphonium group is most preferred.

As the onium-based functional group, those represented by the following general formula (1) are preferred.

(In the formula, X is a phosphorus atom, a nitrogen atom, or a sulfur atom, R may be the same or different, and is a hydrogen atom, a linear, branched or cyclic alkyl group, or an aryl group. N is 1 when X is a nitrogen atom or a phosphorus atom, and is 0 when X is a sulfur atom. * Is a bond.)

For example, as a counter ion for a functional group having a positive charge, a halide ion is preferable. Examples of halide ions include Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ .

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, 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 n-nonadecyl group and n-icosyl group.

Examples of the branched chain alkyl group represented by R include isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, s-pentyl group, t-pentyl group, isohexyl group, 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, and an o-xylyl group.

R is a point that enhances the adhesion between the conductive particles and the insulating fine particles, and when the thermocompression bonding is performed inside the anisotropic conductive film, the insulating fine particles are easily separated from the conductive particles to ensure conduction. From the viewpoint of the following, an alkyl group having 1 to 12 carbon atoms is preferable, an alkyl group having 1 to 10 carbon atoms is more preferable, and an alkyl group having 1 to 8 carbon atoms is preferable. Is most preferred. It is also preferable that R is a linear alkyl group because the insulating fine particles are easily brought close to and adhere to the conductive particles.

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 having a polymerizable compound having an ethylenically unsaturated bond, the polymerizable composition It is preferable to include a polymerizable compound having a charged functional group and an ethylenically unsaturated bond.

Examples of the polymerizable compound having an ethylenically unsaturated bond that constitutes the polymerizable composition include styrenes, olefins, esters, α, β unsaturated carboxylic acids, amides, and nitriles. Examples of styrenes include styrene, o-m, p-methylstyrene, dimethylstyrene, ethylstyrene, chlorostyrene, and other nuclear-substituted styrenes, and α-methylstyrene, α-chlorostyrene, β-chlorostyrene, and other styrene derivatives. Can be mentioned. Examples of olefins include ethylene and propylene. Examples of the esters include vinyl acetate, vinyl propionate, vinyl benzoate and other vinyl esters, and methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, phenyl (meth) acrylate and the like. Examples thereof include esters of (meth) acrylic acid. Examples of the α, β unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like. Salts of these α, β unsaturated carboxylic acids are also included in the α, β unsaturated carboxylic acids. Examples of amides include acrylamide and methacrylamide. Examples of the nitriles include acrylonitrile and the like. These may be further substituted, and as the substituent, 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, 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, a polymer of at least one polymerizable monomer selected from styrenes, esters and nitriles is particularly preferable because it has a high polymerization rate and is easily spherical. It is preferable because it is possible. When the polymer forming 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, alternating or block. The polymer constituting the insulating fine particles may be crosslinked or non-crosslinked. When a polymer constituting the insulating fine particles is cross-linked, as a cross-linking agent, for example, an aromatic divinyl compound such as divinylbenzene or divinylnaphthalene; allyl methacrylate, triacrylic formal, 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, trimethylolpropane trimethacrylate, glycerin Methacrylate, dimethylol-tricyclodecane diacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, neopentyl glycol acrylic acid benzoate, trimethylolpropane acrylic acid benzoate, 2-hydroxy Examples of di (meth) acrylate compounds such as -3-acryloyloxypropyl methacrylate, hydroxypivalic acid neopentyl glycol diacrylate, ditrimethylolpropane tetraacrylate, and 2-butyl-2-ethyl-1,3-propanediol diacrylate. be able to.

Examples of the polymerizable compound having a charged functional group and having an ethylenically unsaturated bond include, for example, N, N-dimethylaminoethyl methacrylate, N, N as the polymerizable compound having an ethylenically unsaturated bond having an onium-based functional group. -Ammonium group-containing monomers such as dimethylaminopropyl acrylamide and N, N, N-trimethyl-N-2-methacryloyloxyethylammonium chloride; Monomers having sulfonium groups such as phenyldimethylsulfonium methylsulfate methacrylate; 4- (vinyl Benzyl) triethylphosphonium chloride, 4- (vinylbenzyl) trimethylphosphonium chloride, 4- (vinylbenzyl) tributylphosphonium chloride, 4- (vinylbenzyl) trioctylphosphonium chloride, -(Vinylbenzyl) triphenylphosphonium chloride, 2- (methacryloyloxyethyl) trimethylphosphonium chloride, 2- (methacryloyloxyethyl) triethylphosphonium chloride, 2- (methacryloyloxyethyl) tributylphosphonium chloride, 2- (methacryloyloxyethyl) Examples thereof include monomers having a phosphonium group such as yloxyethyl) trioctylphosphonium chloride and 2- (methacryloyloxyethyl) triphenylphosphonium chloride.

When the insulating fine particles are a copolymer of a polymerizable compound having a charged functional group and an ethylenically unsaturated bond and a polymerizable compound having no charged functional group and having an ethylenically unsaturated bond, The polymerizable compound having a functional group and the polymerizable compound having no charged functional group may be the same kind or different kinds. Examples of the types mentioned 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, the polymer that constitutes the insulating fine particles preferably has a structural unit represented by the following general formula (2) or general formula (3) from the viewpoint of easy availability of monomers and easiness 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, ortho-position, and meta-position with respect to the CH group of the benzene ring of formula (2), and is preferably bonded to the para-position. In formulas (2) and (3), halide ions are preferable as the monovalent An ⁻ . Examples of halide ions include Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ .

(In the formula, X, R and n have the same meanings as in the general formula (1). M is an integer of 0 to 5. An ⁻ represents a monovalent anion.)

(In the formula, X, R and n have the same meanings as in 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. It is.)

In the polymer constituting the insulating fine particles, the proportion of the constituent units 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, in all the constituent units. It is more preferably 2.0 mol% or less. Here, the number of constitutional units in the polymer is counted as one constitutional unit having a structure derived from one ethylenically unsaturated bond.

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

The polymer constituting the insulating fine particles is a copolymer having two or more types, more preferably three or more types of structural units, and at least one type of these structural units preferably has an ester bond in the structure. Thereby, the glass transition temperature of the polymer can be easily made to be suitably low, and the adhesiveness between the insulating fine particles and the conductive particles can be increased by increasing the ratio of the area in contact with the conductive particles in the insulating fine particles. 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 constituent 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 a polymerizable compound include the above-mentioned esters, specifically, vinyl propionate, vinyl esters such as 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. Particularly, the polymerizable compound having both an ethylenically unsaturated bond and an ester bond in the structure has a group represented by -COOR ₁ or -OCOR ₂ (R ₁ and R ₂ are alkyl groups) in the structure. In particular, these groups are preferably H ₂ C = CH *, or H ₂ C = C (CH ₃ ) * (* is a bond of a bond in the group represented by -COOR ₁ or -OCOR ₂ above. The compound bound to the above) is preferred. 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 proportion of the structural units having an ester bond in the structure in all the structural units is such that the glass transition temperature of the insulating fine particles is within a suitable range and the ratio of the insulating particles generated during the progress of the polymerization reaction. From the viewpoint that the functional 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. .. Preferred examples of the structural unit having an ester bond in the structure herein are 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 this configuration, it is possible to easily increase the ratio of the area of the insulating fine particles in contact with the conductive particles and the adhesion between the insulating fine particles.

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.
In addition, the glass transition temperature of the insulating fine particles is preferably 40 ° C. or higher from the viewpoint of shape stability of the coated particles during storage and the ease of synthesis of the insulating fine particles, and more preferably 45 ° C. or higher. It is preferably 50 ° C. or higher, and particularly preferably 50 ° C. or higher. The glass transition temperature can be measured by the method described in Examples below.

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, and 120 ° C. The temperature is more preferably below, and particularly preferably 100 ° C. or below. 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 cooling rate of 5 ° C./min. .. Then, the sample was heated at a heating rate of 5 ° C./min to measure the amount of heat. When a peak is observed, the temperature of the peak is measured, and when a step is observed without the peak being observed, a tangent line indicating the maximum slope of the curve of the step and an extension line of the baseline on the high temperature side of the step The temperature at the intersection point of was defined as the glass transition temperature.

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

The particle size distribution of the insulating fine particles measured by the above method has a range. In general, the width of the particle size distribution of powder is represented by a coefficient of variation (Coefficient of Variation, hereinafter also referred to as “CV”) represented by the following calculation formula (1).
C. V. (%) = (Standard deviation / average particle size) × 100 (1)
This C. V. A large value indicates that the particle size distribution has a wide range, while C.I. V. A small value indicates that the particle size distribution is sharp. The coated particles of this embodiment are C.I. V. Is preferably 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. Within this range, there is an advantage that the thickness of the coating layer of the insulating fine particles can be made uniform.

The insulating layer may be a continuous film made of a polymer and having a charged functional group, instead of the insulating fine particles. When the insulating layer is a continuous film containing a compound having a charged functional group, thermo-compression bonding of the coated particles between the electrodes melts, deforms or peels the continuous film to expose the metal surface of the conductive particles. However, this makes it possible to conduct electricity between the electrodes and obtain connectivity. In particular, the metal surface is often exposed by breaking the continuous film by thermocompression-bonding the coated particles between the electrodes. On the other hand, at the surface portion of the coated particles that faces a direction different from the thermocompression bonding direction, the continuous coating of the conductive particles is generally maintained, so conduction in directions other than the thermocompression bonding direction is prevented. The insulating film also preferably has a charged functional group on its surface.

Even if the insulating layer is composed of a continuous film, by having a charged functional group, the insulating continuous film easily adheres to the conductive particles having the titanium compound on the surface. In addition, as will be described later, when the continuous film is formed by heating the insulating fine particles or when the insulating fine particles coated with the conductive particles are dissolved in an organic solvent, the insulating fine particles serving as a precursor of the insulating layer Since they can be uniformly arranged, there is an effect that the film thickness of the coating film obtained by melting or melting the insulating fine particles can be made uniform. For these reasons, even when the insulating layer is formed of a continuous film, by having the titanium-based compound and the charged functional group, the effect of preventing a short circuit in a direction different from that between the counter electrodes is easily exhibited, and the insulating property in the direction is improved. It is improved and the connection reliability is 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 a part of the surface. Further, the surface of the continuous film may be flat, and may have irregularities due to melting or melting of the insulating fine particles on the surface.

The thickness of the continuous film is preferably 10 nm or more from the viewpoint of improving the insulating property in the direction different from that between the counter electrodes, and 3,000 nm or less is the point of ease of conduction between the counter electrodes. Is preferred. From this point, 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 the structure of at least one structural unit of the polymer that constitutes the continuous film. The charged functional group is preferably chemically bonded to the polymer forming 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, examples of the constitutional unit of the polymer constituting the continuous film and the composition thereof include the same constitutional units of the polymer constituting the insulating fine particles described above and the same as those mentioned above as examples of the composition thereof. All the preferred ratio ranges for the constituent units also apply for continuous coatings. The glass transition temperature of the continuous film may be the same as 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 above-described relationship between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core material particles, and the same relationship.

When the insulating layer is a continuous film, the conductive film is preferably a continuous film obtained by coating the conductive particles with insulating fine particles having a charged functional group and then heating the insulating fine particles. In this case, as described above, the insulating fine particles are easily adhered to the conductive particles with respect to the conductive particles, and thereby the ratio of the insulating fine particles coated on the surface of the conductive particles becomes sufficient and It is easy to prevent the insulating fine particles from peeling from the particles. In addition, 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 coverage on the surface of the conductive particles.

Originally, it is desirable that the structure and characteristics of the continuous film obtained by subjecting the specific insulating fine particles to the heat treatment are measured by some means and then directly specified in the present specification. ..
However, at least at the time of filing, it was not possible at the applicant's technical level to confirm the structure or characteristics of other continuous films related to the effect of the present invention.
Even if all the factors are found, it is necessary to establish a new measurement method to identify the structure and properties of the continuous film related to these factors, and in order to do so, remarkably excessive economic expenditure and time are required. It costs.
From the above circumstances, in view of the fact that the nature of the patent application requires swiftness, the applicant is to manufacture the continuous film by the above-mentioned manufacturing method as one of the preferable characteristics. Was described.

Next, a suitable method for producing the coated particles of this embodiment will be described.
The present production method comprises a 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,
A second step of containing a titanium compound on the surface of the conductive particles,
A third step of mixing the dispersion liquid containing the insulating fine particles and the conductive particles having the titanium-based compound on the surface to adhere 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 simultaneously.

(First step)
The polymerizable composition is composed of two or more kinds of polymerizable compounds, and at least one kind includes a charged functional group. Examples of the polymerizable compound include a polymerizable compound having an ethylenically unsaturated bond which serves as a constitutional unit of a polymer forming the insulating fine particles described above. In addition, examples of the preferable polymerizable compound and the constitutional ratio thereof include those which give the preferable constitutional unit of the polymer constituting the insulating fine particles and the 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 method may be used.When soap-free emulsion polymerization is used, monodisperse fine particles and a surfactant are used. It is preferable because 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 under 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)
The conductive particles having the titanium-based compound on the surface can be obtained by mixing the titanium-based compound 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 those having the structure represented by the above general formula (I) are preferable. As the compound having the structure represented by the general formula (I), the compound represented by the general formula (I ′) is preferably exemplified. Prior to the treatment with the titanium compound, the conductive particles may be treated with another organic agent or may be untreated.

(If ^{^{R 12, R 13, p,}} q and r are .R ¹¹ as defined in the above general formula (I) is a hydrocarbon group .p is 2 or more, plural R ¹¹ may be the same May be different from each other, two R ^{11 s} may be bonded to each other, and the methylene group in the group represented by R ¹¹ may be substituted with —O—, —COO— or —OCO—. .)

In the general formula (I ′), examples of the hydrocarbon group represented by R ¹¹ include alkyl groups having 1 to 12 carbon atoms. When p is 2 or more, examples of the linking group in which two R ¹¹ are bonded to each other include 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 with —O—, —COO—, or —OCO— under the condition that oxygen atoms are not continuous with each other. Examples of the alkyl group having 1 to 12 carbon atoms represented by R ¹¹ include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group and tert-butyl group. Is mentioned.

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

When the surface treatment is performed with a titanium compound, the treatment can be performed by mixing the conductive particles, the titanium compound and a solvent at room temperature. Alternatively, the conductive particles and the titanium 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 containing the insulating fine particles and the conductive particles having a titanium compound on the surface are mixed to adhere 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 of easily obtaining coated particles having a certain coverage. As the inorganic salt, the organic salt or the organic acid, those that dissociate anions are preferably used, and as the anions, Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ , SO ₄ ²⁻ , CO ₃ ^{2− are used.} , NO ₃ ⁻ , COO ⁻ , RCOO ⁻ (R is an organic group) and the like are preferable. 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 , MgSO ₄ , Na ₂ CO ₃ , NaHCO ₃ , K ₂ CO ₃ , KHCO ₃ , Li ₂ CO ₃ , LiHCO ₃ , MgCO ₃ , NaNO. ₃ , KNO ₃ , LiNO ₃ , MgNO ₃ , BaNO ₃ or the like can be used. As the organic salt, Na oxalate, Na acetate, Na citrate, Na tartrate or 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 preferred concentrations of the inorganic salt, the organic salt and the organic acid differ depending on the coverage area of the insulating fine particles on the surface area of the conductive particles, but may be, for example, 0. A concentration of 1 mmol / L or more and 100 mmol / L or less is preferable because it has a suitable coverage and it is easy to obtain coated particles in which the insulating fine particles are a single layer. From this viewpoint, it is particularly preferable that the concentrations of the inorganic salt, the organic salt and the organic acid in the dispersion liquid are 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 may be mixed. Alternatively, insulating fine particles and conductive particles may be added to the liquid medium, and a dispersion medium containing insulating fine particles and a dispersion medium containing conductive particles may be mixed. In the dispersion liquid containing the conductive particles and the insulating fine particles, the conductive particles are preferably contained in an amount of 100 ppm or more and 100,000 ppm or less, and more preferably 500 ppm or more and 80,000 ppm or less on a mass basis. ..
The insulating fine particles are preferably contained in the dispersion liquid containing the conductive particles and the insulating fine particles in an amount of 10 ppm or more and 50,000 ppm or less, and more preferably 250 ppm or more and 30,000 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 of easily obtaining coated particles of constant quality, and particularly preferably 40 ° C. or higher. Particularly, when the glass transition temperature of the insulating fine particles is Tg ° C., the temperature of the dispersion liquid 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 a 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 the conductive particles are mixed, 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. Next, 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 adhere to the surface of the conductive particles, the insulating fine particles can be melted to coat the surface of the conductive particles in a film shape. By forming the insulating fine particles into a film, the insulating property becomes stronger. As a method of heating, a method of heating the dispersion after attaching the insulating fine particles to the surface of the conductive particles, a method of heating the coated particles in a solvent such as water, an inert gas such as coated particles Examples include a method of heating in a gas phase. The heating temperature is Tg + 1 ° C or more and Tg + 60 ° C when the glass transition temperature of the polymer forming the insulating fine particles is Tg, since it is easy to form a uniform film without the insulating fine particles falling off. The following is preferable, Tg + 5 ° C. or more and Tg + 50 ° C. or less are more preferable, and Tg + 15 ° C. or more is most preferable. The heating time is preferably 0.1 hours or more and 24 hours or less from the viewpoint of easily forming a uniform film shape. When the coated particles are heated in the gas phase, the pressure condition can be atmospheric pressure, reduced pressure or increased pressure.

In addition, the coated particles in which the insulating fine particles are adhered to the surface of the conductive particles can bring the insulating fine particles into a fluid state by adding an organic solvent to the dispersion liquid. Can be coated on. When the insulating fine particles are dissolved, tetrahydrofuran, toluene, methyl ethyl ketone, N-methyl-2-pyrrolidone, N, N-dimethylformamide, or 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 coated particles in the dispersion liquid, in order to easily form a uniform film without the insulating fine particles falling off. Is preferred, 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 of easily forming a uniform film shape without the insulating fine particles falling off. Further, the time for forming a film after addition is preferably 0.1 hour or more and 24 hours or less from the viewpoint of forming a uniform film.

The coated particles obtained by coating the surface of the conductive particles 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, where Tg is the glass transition temperature of the polymer forming the insulating fine particles. The heating atmosphere is not particularly limited, and the heating atmosphere may be performed under an atmosphere of an inert gas such as nitrogen or argon or an oxidizing atmosphere such as air under atmospheric pressure, reduced pressure, or increased pressure.

The preferred production method has been described above, but the coated particles of the present invention can be produced by other production methods. For example, insulating fine particles having no charged functional group are previously produced by a polymerization reaction, and the obtained insulating fine particles are reacted with a compound having a charged functional group to introduce a charged functional group onto the surface of the insulating fine particles. May be.

The coated particles obtained as described above have an insulating property and a facing property between coated particles due to the advantages of combining conductive particles having a titanium compound on the surface and insulating fine particles having a charged functional group or a continuous film. It is suitably used as a conductive material such as a conductive adhesive, an anisotropic conductive film, an anisotropic conductive adhesive, etc., by utilizing the connectivity between the electrodes.

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

(1) Average particle size 200 particles were arbitrarily extracted from a scanning electron microscope (SEM) photograph (magnification of 100,000 times for insulating fine particles and 10,000 times for conductive particles) of a measurement target. The above-mentioned particle diameters were measured for them, and the average value was defined as the average particle diameter.

(2) C.I. V. (Coefficient of variation)
The average particle diameter was measured, and the average particle diameter was calculated by the following formula.
C. V. (%) = (Standard deviation / average particle size) × 100

(3) Glass transition temperature A differential scanning calorimeter (manufactured by METTLER TOLEDO, STAR SYSTEM) was used to increase or decrease the temperature at a rate of 5 ° C./min under a nitrogen atmosphere and measure the change in the amount of heat from 25 ° C. to 200 ° C. according to the above procedure. It was measured.

(Example 1)
[Production 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. Then, 30.00 mmol of styrene monomer (manufactured by Kanto Kagaku), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Kagaku), 0.30 mmol of 4- (vinylbenzyl) triethylphosphonium chloride (manufactured by Nippon Kagaku Kogyo), and as a polymerization initiator 0.50 mmol of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.) was added. Nitrogen was bubbled for 15 minutes to drive off the dissolved oxygen, then the temperature was raised to 60 ° C. and the temperature was maintained for 6 hours to allow the polymerization reaction to proceed. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having openings of 150 μm to remove aggregates. The dispersion liquid from which the agglomerates were removed was subjected to a centrifugal separator (CR-21N, manufactured by Hitachi Koki Co., Ltd.) under the conditions of 20,000 rpm for 20 minutes to precipitate fine particles, and the supernatant was removed. Pure water was added to the obtained solid material to wash it, and spherical fine particles of poly (styrene / n-butyl acrylate / 4- (vinylbenzyl) triethylphosphonium chloride) were obtained. The obtained fine particles had an average particle diameter of 86 nm, and C.I. V. Was 7.4%. The glass transition temperature was about 62 ° C.
[Production of conductive particles coated with insulating fine particles]
Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having an average particle diameter of 3 μm and having a nickel coating with a thickness of 0.125 μm on the surface of spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 25 mL of toluene was added to 5.0 g of the above Ni-plated particles and stirred to obtain a dispersion liquid of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Planeact KR-TTS, p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is —OCO—, q = 1, R in the above general formula (I ′). 0.1 g of a compound in which ¹³ is a heptadecyl group) was added to this dispersion, and the mixture was stirred at room temperature for 20 minutes for surface treatment. Then, filtration was performed with a membrane filter having an opening of 2.0 μm, and Ni plated particles having a Ti-based coupling agent layer on the surface were collected. 100 mL of a mixed solution of ethanol: pure water = 75: 25 was added to the recovered Ni plated particles on a mass basis to obtain a dispersion liquid of the surface treated Ni plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and this was stirred at 40 ° C. for 30 minutes. After adding the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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. The SEM photograph of the obtained coated particles is shown in FIG.

(Example 2)
[Production of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Production of conductive particles coated with insulating fine particles]
The spherical resin particles had 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 on the surface, and had a thickness of 0. Ni-plated particles (manufactured by Nippon Kagaku Kogyo) having an average particle diameter of 3 μm and having a nickel coating of 125 μm were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 25 mL of toluene was added to 5.0 g of the above Ni-plated particles and stirred to obtain a dispersion liquid of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Planeact KR-TTS, p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is —OCO—, q = 1, R in the above general formula (I ′). 0.1 g of a compound in which ¹³ is a heptadecyl group) was added to this dispersion, and the mixture was stirred at room temperature for 20 minutes for surface treatment. Then, filtration was performed with a membrane filter having an opening of 2.0 μm, and Ni plated particles having a Ti-based coupling agent layer on the surface were collected. 100 mL of a mixed solution of ethanol: pure water = 75: 25 was added to the recovered Ni plated particles on a mass basis to obtain a dispersion liquid of the surface treated Ni plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and this was stirred at 40 ° C. for 30 minutes. After adding the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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)
[Production of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Production of conductive particles coated with insulating fine particles]
Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Planeact KR-41B, p in the above general formula (I ′) is 3, r is 1, R ¹¹ is an isopropyl group, and R ¹² is —P (OH) (O—). ₂ , q = 1, and a compound in which R ¹³ is an octyl group) (0.1 g) is added to the dispersion liquid of the Ni-plated particles to perform the surface treatment, and the insulating fine particle-coated conductive material is prepared in the same manner as in Example 1. The particles were obtained. 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)
[Production of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Production of conductive particles coated with insulating fine particles]
Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Planeact KR-41B, p in the above general formula (I ′) is 3, r is 1, R ¹¹ is an isopropyl group, and R ¹² is —P (OH) (O—). ₂ , q = 1, and a compound in which R ¹³ is an octyl group) (0.1 g) is added to the dispersion liquid of the Ni-plated particles to carry out the surface treatment, and the insulating fine particle-coated conductive material is prepared in the same manner as in Example 2. The particles were obtained. 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 electrically conductive particles coated with insulating fine particles obtained in Example 1 was added to 20 mL of pure water to prepare a dispersion liquid, and the dispersion liquid was stirred at 95 ° C. for 6 hours. After the stirring is completed, the solid content is separated using a membrane filter having an opening of 2 μm and dried to obtain coated particles coated with an insulating layer composed 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 the insulating layer formed of a continuous film was determined by the following method. The results are shown in Table 1.

(Example 6)
[Production 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. Then, 15.0 mmol of divinylbenzene monomer (manufactured by Nippon Steel & Sumikin) as a crosslinkable monomer, 30.00 mmol of styrene monomer (manufactured by Kanto Kagaku) as a non-crosslinkable monomer, and 5.3 mmol of n-butyl acrylate (manufactured by Kanto Kagaku), 4- (Vinylbenzyl) triethylphosphonium chloride (manufactured by Nippon Kagaku Kogyo) 0.03 mmol, and 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries) as a polymerization initiator. 50 mmol was added. Nitrogen was bubbled for 15 minutes to drive off the dissolved oxygen, then the temperature was raised to 60 ° C. and the temperature was maintained for 6 hours to allow the polymerization reaction to proceed. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having openings of 150 μm to remove aggregates. The dispersion liquid from which the agglomerates were removed was centrifuged by a centrifuge (CR-21N manufactured by Hitachi Koki Co., Ltd.) at 20,000 rpm for 20 minutes to precipitate fine particles, and the supernatant was removed. Pure water was added to the obtained solid material to wash it, and spherical fine particles of poly (styrene / divinylbenzene / n-butyl acrylate / 4- (vinylbenzyl) triethylphosphonium chloride) were obtained. The average particle size of the obtained fine particles was 220 nm, and C.I. V. Was 9.7%.
[Production 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)
[Production 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. Then, 30.00 mmol of styrene monomer (manufactured by Kanto Chemical Co., Inc.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), 0.30 mmol of 4- (vinylbenzyl) triethylammonium chloride (manufactured by Nippon Kagaku Kogyo Co., Ltd.), and polymerization. As the initiator, 0.50 mmol of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.) was added. Nitrogen was bubbled for 15 minutes to drive off the dissolved oxygen, then the temperature was raised to 60 ° C. and the temperature was maintained for 6 hours to allow the polymerization reaction to proceed. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having openings of 150 μm to remove aggregates. The dispersion liquid from which the agglomerates were removed was centrifuged with a centrifuge (CR-21N manufactured by Hitachi Koki Co., Ltd.) at 20,000 rpm for 20 minutes to precipitate fine particles, and the supernatant liquid was removed. Pure water was added to the obtained solid matter to wash it, to obtain spherical fine particles of poly (styrene / n-butyl acrylate / 4- (vinylbenzyl) triethylammonium chloride). The obtained fine particles had an average particle diameter of 90 nm, and C.I. V. Was 8.6%. The glass transition temperature was about 59 ° C.
[Production of conductive particles coated with insulating fine particles]
Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having an average particle diameter of 3 μm and having a nickel coating with a thickness of 0.125 μm on the surface of spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 25 mL of toluene was added to 5.0 g of the above Ni-plated particles and stirred to obtain a dispersion liquid of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Planeact KR-TTS, p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is —OCO—, q = 1, R in the above general formula (I ′). 0.1 g of a compound in which ¹³ is a heptadecyl group) was added to this dispersion, and the mixture was stirred at room temperature for 20 minutes for surface treatment. Then, filtration was performed with a membrane filter having an opening of 2.0 μm, and Ni plated particles having a Ti-based coupling agent layer on the surface were collected. 100 mL of a mixed solution of ethanol: pure water = 75: 25 was added to the recovered Ni plated particles on a mass basis to obtain a dispersion liquid of the surface treated Ni plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and this was stirred at 40 ° C. for 30 minutes. After adding the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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)
[Production of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Production of conductive particles coated with insulating fine particles]
In Example 1, the surface treatment with the Ti-based coupling agent was not performed. Specifically, Ni plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel coating of 0.125 μm thick on the surface of spherical resin particles and 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 liquid of the 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 adding the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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)
[Production of phosphonium-based insulating fine particles]
The same insulating fine particles as in Example 1 were obtained.
[Production of conductive particles coated with insulating fine particles]
In Example 2, the surface treatment with the Ti coupling agent was not performed. More specifically, the surface of 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 Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having an average particle diameter of 3 μm and having a nickel coating of 0.125 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 liquid of the 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 adding the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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)
[Production of ammonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 7.
[Production of conductive particles coated with insulating fine particles]
In Example 7, the surface treatment with the Ti-based coupling agent was not performed. Specifically, Ni plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel coating of 0.125 μm thick on the surface of spherical resin particles and 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 liquid of the 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 introduction of the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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 conductivity and insulating properties of the coated particles with the same coverage as Comparative Example 2.
[Production of phosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Example 1.
[Production of conductive particles coated with insulating fine particles]
The spherical resin particles had 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 on the surface, and had a thickness of 0. Ni-plated particles (manufactured by Nippon Kagaku Kogyo) having an average particle diameter of 3 μm and having a nickel coating of 125 μm were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 25 mL of toluene was added to 5.0 g of the above Ni-plated particles and stirred to obtain a dispersion liquid of Ni-plated particles. Ti-based coupling agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Planeact KR-TTS, p is 3, r is 1, R ¹¹ is an isopropyl group, R ¹² is —OCO—, q = 1, R in the above general formula (I ′). 0.1 g of a compound in which ¹³ is a heptadecyl group) was added to this dispersion, and the mixture was stirred at room temperature for 20 minutes for surface treatment. Then, filtration was performed with a membrane filter having an opening of 2.0 μm, and Ni plated particles having a Ti-based coupling agent layer on the surface were collected. 100 mL of a mixed solution of ethanol: pure water = 75: 25 was added to the recovered Ni plated particles on a mass basis to obtain a dispersion liquid of the surface treated Ni plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and this was stirred at 40 ° C. for 30 minutes. After adding the insulating fine particles and Na ₂ SO ₄ , the solid 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 liquid, washing with pure water was repeated 3 times, and then vacuum drying was performed 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 said average particle diameter was used for the following radius.
<Measurement method of coverage>
In Examples other than Example 5, Comparative Examples and Reference Example 1, the number N of the insulating fine particles when the insulating fine particles were arranged in the closest packing on the surface of the Ni plated particles was calculated by the following calculation 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 attached to the Ni-plated particles was counted by SEM, and the coverage was calculated from the following formula.
Coverage (%) = (n / N) × 100
The coverage used for evaluation was an average value of 20 Ni-plated particles.
In Example 5, the backscattered electron composition (COMPO) image of the SEM photographic image of the coated particles was loaded into an automatic image analyzer (Luzex (registered trademark) AP manufactured by Nireco Co., Ltd.), and 20 coated particles in the COMPO image were taken. Was calculated as a target.

As shown in Table 1, the coated particles obtained by treating the conductive particles with the Ti-based coupling agent as the titanium-based compound and then coated with the insulating fine particles were the same as the coated particles obtained without treatment with the Ti-based coupling agent. A good coverage was shown in comparison.
Further, the coated 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 allowing the conductive particle surface to have a titanium-based compound and having a functional group having a charge in the insulating layer. It can be seen that the adhesiveness of is improved synergistically.

(Evaluation of conductivity and insulation)
The coated particles of Example 2, Comparative Example 2 and Reference Example 1 were used to evaluate conductivity and insulation by the following methods.

<Evaluation of conductivity>
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 was 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 placed 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 performed. The conductivity of the coated particles was evaluated at room temperature (25 ° C. and 50% RH) by measuring the conduction resistance between the substrates. It can be evaluated that the lower the resistance value, the higher the conductivity of the coated particles. In the conductivity evaluation of the coated particles, those having a resistance value of less than 2Ω are “very good” (indicated by a symbol “◯” in Table 2), and those having a resistance value of 2Ω or more and less than 5Ω are “good”. (Indicated by the symbol “Δ” in Table 2), and those having a resistance value of 5Ω or more were determined as “poor” (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), the coating of Example 2, Comparative Example 2 and Reference Example 1 was performed on 20 coated particles 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. The larger the compressive displacement until the resistance value is detected, the higher the insulating property of the coated particles can be evaluated. In the insulation evaluation of the coated particles, the one in which the arithmetic mean value of the compression displacement until the resistance value was detected was 10% or more was “very good” (indicated by the symbol “◯” in Table 2), If the arithmetic mean value of the compression displacement is more than 3% and less than 10%, it is defined as “good” (indicated by the symbol “Δ” in Table 2), and if the arithmetic mean value of the compression displacement is 3% or less. "Poor" (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 which were surface-treated with the Ti-based coupling agent were superior in insulating property while maintaining conductivity as compared with the coated particles of Comparative Example 2 which were not surface-treated. You can see that In addition, since the reference example 1 having the same coverage as that of the comparative example 2 has the same coverage as that of the comparative example 2 but is excellent in the insulating property, the insulating effect by the Ti-based coupling agent is obtained. It is understood that it is being done.

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

Claims

Conductive particles in which a metal coating is formed on the surface of the core material, and a titanium compound having a hydrophobic group is arranged on the outer surface of the metal coating,
An insulating layer coating the conductive particles, and coated particles having:
Coated particles, wherein the insulating layer has a compound containing a charged functional group.
The coated particles 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 a charge is a phosphonium group or an ammonium group.
5. The metal film according to claim 1, wherein the metal film is a metal film containing at least one selected from nickel, gold, silver, copper, palladium, nickel alloy, gold alloy, silver alloy, copper alloy and palladium alloy. The coated particle according to item 1.
The coated particle according to any one of claims 1 to 5, wherein the insulating layer is made of a polymer of at least one type of polymerizable monomer selected from styrenes, esters and nitriles.
The coated particles according to any one of claims 1 to 6, wherein the conductive particles have a plurality of protrusions on the surface.
A conductive material containing the coated 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 titanium compound on the surface of the conductive particles. The second step (any of the first step and the second step may be performed first or at the same time), the dispersion liquid containing the insulating fine particles, and the conductive material having the titanium-based compound on the surface. A third step of mixing coated particles with the conductive particles to attach insulating fine particles having a charged functional group to the surface of the conductive particles.
The coated particle according to claim 9, further comprising a fourth step of heating the coated particle obtained in the third step to coat the surface of the conductive particle in a film state with the insulating fine particles in a molten state. Production method.
Furthermore, the coated particles obtained in the third step have a fourth step of coating the surface of the conductive particles in a film form by adding an organic solvent to the dispersion liquid to bring the insulating fine particles into a dissolved state. 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 functional group having a charge is a phosphonium group or an ammonium group.