JP7430610B2 - Coated particles and their manufacturing method - Google Patents

Description

The present invention relates to coated particles comprising conductive particles and an insulating layer covering the conductive particles.

Conductive particles in which a metal film of nickel, gold, or the like is formed on the surface of core particles are used as conductive materials such as conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives.
In recent years, with the further miniaturization of electronic devices, the circuit width and pitch of electronic circuits have become smaller and smaller. Accordingly, conductive particles used in the above-mentioned conductive materials are required to have small particle diameters. When using such small-sized conductive particles, the amount of conductive particles in the conductive material must be increased in order to improve connectivity. However, when the amount of conductive particles is increased, a short circuit occurs due to conduction in an unintended direction, that is, conduction in a direction different from that between opposing electrodes, making it difficult to obtain insulation in an unintended direction. It has become.

In order to solve the above problem, insulating layer-coated conductive particles have been proposed in which the surfaces of conductive particles are coated with an insulating substance to prevent the metal coatings of the conductive particles from coming into contact with each other. For coated particles with such a structure, the insulating fine particles of the insulating layer are usually melted, deformed, or peeled off by thermocompression bonding the coated particles between electrodes, and the metal surface of the conductive particles is exposed. However, there is a known technique for improving characteristics such as reliability of conduction by examining the constituent components of the insulating fine particles.

Resin particles such as styrene resin and acrylic resin, or inorganic particles such as silica and alumina are used as insulating particles, but in order to improve properties such as insulation and solvent resistance, organic particles made by combining organic and inorganic substances are used. Inorganic composite fine particles are also being studied (see, for example, Patent Documents 1 to 5).

Among the above-mentioned patent documents, for example, Patent Document 4 describes conductive fine particles coated with insulating fine particles, in which organic-inorganic composite fine particles are present on the surface of conductive fine particles. According to this document, insulating fine particles are organic-inorganic composite fine particles, and their forms include particles in which an inorganic component is dispersed in an organic component, core-shell particles in which an inorganic component core particle is coated with an organic component, and a core-shell particle in which an inorganic component core particle is coated with an organic component. Disclosed are core-shell particles in which a core particle is coated with an inorganic component, and particles in which an inorganic component and an organic component are composited at the molecular level. Further, the shape thereof is not particularly limited, and may be spherical, needle-like, plate-like, confection sugar-like, or the like. It has been reported that excellent solvent resistance and high insulation properties can be imparted by using such insulating fine particles.

Moreover, in Patent Document 5, conductive particles are coated with polymer particles obtained by polymerizing a polymerizable monomer having a double bond and a hydrolyzable silyl group and a polymerizable monomer having a hydrophilic functional group as insulating fine particles. is listed. It has been reported that these insulating fine particles can be used as organic-inorganic composite insulating fine particles by hydrolyzing the silyl group to form a silanol group and treating this silanol group with a silicone oligomer. It is said to improve.

Special Publication No. 2007-537570 International Publication No. 2012/002508 pamphlet Japanese Patent Application Publication No. 2015-187984 Japanese Patent Application Publication No. 2011-65750 Japanese Patent Application Publication No. 2013-108026

When the anisotropic conductive material is thermocompressed between the electrodes, electrical conduction between the electrodes is achieved by the conductive particles in the anisotropic conductive material. The conductive particles described in the above patent document can prevent contact between metal films and short circuits by blocking adjacent conductive particles with an insulating layer coated with conductive particles during thermocompression bonding. However, because the conductive particles were displaced from the electrodes due to mechanical force during thermocompression bonding, there was a problem with continuity reliability.

Therefore, an object of the present invention is to provide coated particles that solve the above problems and can improve conduction reliability and insulation properties.

The present inventors conducted extensive research to solve the above problem, and found that if an inorganic compound is supported on a part of the insulating layer, the supported inorganic compound will successfully pierce the electrode, and the conductive particles will be The present invention was completed based on the discovery that the conduction reliability is excellent because it is easily fixed to the electrode.

That is, the present invention provides a block comprising conductive particles having a metal film formed on the surface of a core material and an insulating layer covering the conductive particles, wherein the insulating layer has a hydrophobic site and a hydrophilic site. The present invention provides coated particles containing a copolymer, in which an inorganic compound is supported on the hydrophilic site of the block copolymer.

According to the present invention, coated particles with excellent conduction reliability and insulation properties can be provided.

FIG. 1 is a schematic cross-sectional view showing one embodiment of coated particles. FIGS. 2(a) and 2(b) are schematic cross-sectional views showing one embodiment of coated particles. FIG. 3(a) is a schematic diagram showing one embodiment of the patchy particles, and FIG. 3(b) is a schematic diagram showing one embodiment of the insulating fine particles. FIG. 4 is a 1H-NMR chart of the patchy particles obtained in Example 1. FIG. 5 is an FT/IR chart of the patchy particles obtained in Example 1. FIG. 6 is a TEM photograph of the mottled particles obtained in Example 1. FIG. 7 is an FT/IR chart of the insulating fine particles obtained in Example 1.

Hereinafter, the coated particles of the present invention will be explained based on preferred embodiments thereof with reference to the drawings. As shown in FIG. 1, the coated particles 1 include conductive particles 5 having conductive surfaces and an insulating layer 6 covering the conductive particles 5. The conductive particles 5 only need to have conductivity at least on the surface of the particles, and the conductive particles 5 may be integrally formed of a conductive material, or the outer surface of a non-conductive material or a conductive material. Both embodiments include an embodiment in which a conductive material is further disposed on the surface of the conductive material to make the surface conductive.

The conductive particles 5 shown in FIG. 1 have conductive particles on their surfaces by forming a conductive film 3 made of a conductive material on the surface of a core material 2 made of a non-conductive material or a conductive material. It has become a thing. With the configuration shown in the figure, conductivity with electrodes can be improved while allowing the coated particles to exhibit appropriate elasticity during electrical connection during the formation of an electronic circuit. In the following description, a conductive particle 5 in which a conductive film 3 made of a conductive material is formed on the surface of a core material 2 will be taken as an example.

The conductive film 3 shown in the figure may cover the entire particle surface of the core material 2 evenly and continuously, or it may cover only a part of the particle surface of the core material 2 as long as conductivity can be ensured. may be covered. In the former case, the conductive particles 5 are such that the entire surface of the core material 2 is completely covered with metal, and the surface of the core material 2 particles is not exposed. In the latter case, the conductive particles 5 are composed of a portion whose surface is made of a component of the core material serving as the base material, and a portion made of metal. When the conductive film 3 covers only a part of the particle surface of the core material 2, the coated area may be a continuous film, a discontinuous film like a sea island, or a combination of these. It may be a combination. Further, the conductive film 3 may have a single layer structure, a laminated structure consisting of multiple layers, or a combination of these structures. In any case, it is preferable that the conductive film 3 is formed in direct contact with the surface of the core material 2.

As the constituent components of the core material 2, inorganic substances and organic substances can be used without particular limitation. Although the shape of the core material is not particularly limited, it is preferably particulate. Examples of the shape of the particulate core material include spherical, fibrous, hollow, plate-like, needle-like, and irregular shapes. Among these, spherical shapes are preferred from the viewpoint of efficient particle filling and formation of a conductive film on the core material. The core material may have a plurality of protrusions on its surface. In the following description, unless otherwise specified, an embodiment will be described in which a particulate core material (core material particles) is used as the core material.

Examples of inorganic substances used in the core material 2 include metals such as gold, silver, copper, nickel, and palladium, or alloys thereof, metal compounds such as solder, glass, ceramics, silica, and anhydrous oxides of metals or nonmetals. or hydrates, metal silicates including aluminosilicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal acid salts, metal halides, and carbon. . These may be used alone or in combination of two or more.

Examples of organic substances used in the core material 2 include natural fibers, natural resins, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic esters, polyacrylonitrile, polyacetals, ionomers, polyesters, acrylic resins, Examples include thermoplastic resins such as methacrylic resins, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, and thermosetting resins such as diallyl phthalate resins. These may be used alone or in combination of two or more.

The core material 2 may be made of either the above-mentioned inorganic or organic material, or alternatively, it may be made of both an inorganic material and an organic material. When the core material 2 is made of a material consisting of both an inorganic substance and an organic substance, the presence of the inorganic substance and the organic substance in the core material 2 includes, for example, a core made of an inorganic substance and an organic substance covering the surface of the core. Examples include a core-shell type structure, such as an embodiment including a shell, or an embodiment including a core made of an organic substance and a shell made of an inorganic substance covering the surface of the core. In addition to these, examples include a blend type structure in which an inorganic substance and an organic substance are mixed or randomly fused in one core material 2 particle.

In particular, the core material 2 is preferably composed mainly of a material made of an organic substance, more preferably a resin, and even more preferably a thermoplastic resin. By using a core material made of such a material, it is possible to improve the dispersion stability of particles, and also to develop appropriate elasticity and improve conductivity when electrically connecting electronic circuits. can. Furthermore, the heat resistance can be improved by using inorganic substances such as metal particles, ceramics, and silica as subcomponents.

Examples of the conductive material used to develop conductivity on the surface of the conductive particles 5 include gold, platinum, silver, copper, iron, zinc, nickel, tin, lead, antimony, bismuth, cobalt, indium, and titanium. , metals such as germanium, aluminum, chromium, palladium, tungsten, and molybdenum, or alloys thereof, and metal compounds such as ITO and solder. These materials can be used alone or in combination of two or more. In the embodiment shown in FIG. 1, these conductive materials can be used for the conductive film 3.

From the viewpoint of lowering the electrical resistance during conduction and increasing adhesion with the insulating layer 6 described later, the surface of the conductive particles 5 is coated with at least one kind of conductive material selected from gold, silver, copper, nickel, palladium, and solder. The conductive particles preferably include at least one conductive material selected from nickel, gold, silver, copper, palladium, nickel alloy, gold alloy, silver alloy, copper alloy, and palladium alloy. More preferably, the surface includes a surface of 5. In other words, the conductive film 3 shown in FIG. 1 preferably includes at least one selected from gold, silver, copper, nickel, palladium, and solder, and includes an alloy of nickel, gold, silver, copper, palladium, and nickel. , gold alloy, silver alloy, copper alloy, and palladium alloy. From the same point of view, when the conductive film 3 has a laminated structure consisting of multiple layers, the outermost layer of the conductive film is nickel, gold, silver, copper, palladium, nickel alloy, gold alloy, silver alloy. It is more preferable that the material be made of at least one selected from , copper alloys, and palladium alloys.

The shape of the conductive particles 5 is not particularly limited, although it depends on the shape of the core particles. Examples of the shape of the conductive particles 5 include spherical, fibrous, hollow, plate-like, needle-like, and irregular shapes. Among these, from the viewpoint of achieving excellent filling properties and connectivity, it is preferable that the conductive particles 5 have a spherical shape or a shape having protrusions on the surface. When the conductive particles have a shape having protrusions on the surface, it is preferable to have a plurality of protrusions on the surface, and it is more preferable to have a plurality of protrusions on the surface of a sphere. When the conductive particles 5 have a shape having a plurality of protrusions, the protrusions of the conductive particles 5 may be formed by core particles having a plurality of protrusions, or the core particles do not have protrusions and are conductive. This may be due to the fact that the sexual coating 3 has a plurality of protrusions.

When the conductive particles 5 have protrusions on their surfaces, the height of the protrusions is preferably 20 nm or more and 500 nm or less, more preferably 50 nm or more and 400 nm or less. Although the number of protrusions depends on the particle size of the conductive particles 5, the number of protrusions per conductive particle 5 is preferably 1 to 20,000, more preferably 5 to 5,000. This is advantageous in that the conductivity of the particles is further improved. Further, the length of the base of the protrusion is preferably 5 nm or more and 500 nm or less, more preferably 10 nm or more and 400 nm or less. The length of the base of the protrusion is the length along the surface of the conductive particle at the site where the protrusion is formed, when measured using an electron microscope image in a cross-sectional view of the particle, and the height of the protrusion is: The shortest distance from the base of the protrusion to the apex of the protrusion. Note that if one protrusion has multiple vertices, the highest apex is the height of the protrusion. The length of the protrusion base and the protrusion height are the arithmetic mean values measured for 20 different particles observed using an electron microscope.

When forming the conductive film 3 on the core material 2, the thickness of the conductive film 3 is preferably 0.001 μm or more and 2 μm or less, more preferably 0.01 μm or more and 1.5 μm or less. When the conductive film 3 has a laminated structure consisting of a plurality of layers, the thickness of the entire laminated structure of the conductive film 3 may be within the above-mentioned range. Furthermore, when the conductive particles have protrusions described below, the height of the protrusions is not included in the thickness of the conductive film referred to herein. The thickness of the conductive film can be measured, for example, by cutting the coated particle to be measured into two and observing the cross section of the cut using an SEM.

The insulating layer 6 covers the surface of the conductive particles 5. The coated particles 1 shown in FIG. 1 have a form in which an insulating layer 6 is disposed on the surface of a conductive film 3 to cover the surface of the conductive particle 5.

The insulating layer 6 includes a block copolymer having a hydrophobic site and a hydrophilic site, and has a structure in which an inorganic compound is supported on the hydrophilic site of the block copolymer. Since the insulating layer has an inorganic compound region, it physically bites into the electrode during pressurized connection, making it possible to fix the conductive particles to the electrode, thereby improving insulation and continuity reliability. .

The insulating layer 6 may cover the entire surface of the conductive particles 5 evenly and continuously, or may cover only a part of the surface of the conductive particles 5. In the former case, the entire surface of the conductive film of the conductive particles 5 is completely covered with the insulating layer 6, so that the surface of the conductive particles 5 is not exposed. In the latter case, the conductive particles 5 are composed of a portion whose surface is made of at least one of the core material 2 and the conductive film 3 as a base, and a portion made of the insulating layer 6. When the insulating layer 6 covers only a part of the surface of the conductive particles 5, the covered area may be continuous, discontinuously covered in a sea-island shape, or a combination thereof. You can.

In detail, the formation mode of the insulating layer 6 in the coated particle 1 includes, for example, the forms (i) and (ii) shown below.
(i) As shown in Figure 2(a), the inorganic compound is added to the hydrophilic region of the patchy particle, which is made of a block copolymer having a hydrophobic region and a hydrophilic region, and has a hydrophobic region and a hydrophilic region on the surface. Insulating fine particles 6a carrying particles 7c are arranged in a layered manner on the surface of conductive particles 5.
(ii) As shown in FIG. 2(b), the inorganic compound 8c is formed in the hydrophilic region of a patchy film made of a block copolymer having a hydrophobic region and a hydrophilic region, and has a hydrophobic region and a hydrophilic region. A form in which the supported insulating film 6b is arranged on the surface of the conductive particles 5.

As shown in FIG. 2(a), when the insulating layer 6 is made of insulating fine particles 6a, the shape of the insulating fine particles 6a may be, for example, spherical, fibrous, hollow, plate-like, acicular, or irregularly shaped. obtain. Furthermore, the insulating fine particles 6a may have many protrusions on their surfaces. From the viewpoint of adhesion to the conductive particles and ease of manufacturing the insulating fine particles, the insulating fine particles are preferably spherical.

In the present invention, the patchy particles made of a block copolymer having hydrophobic sites and hydrophilic sites constituting the insulating fine particles 6a refer to polymer particles in which hydrophobic regions and hydrophilic regions are distributed in a mottled manner. . The insulating fine particles 6a in the present invention are particles in which an inorganic compound is supported on the hydrophilic region of the surface of the mottled particles.

As shown in FIG. 2(b), when the insulating layer 6 is an insulating film 6b, the thickness of the film may be uniform or non-uniform. Further, the insulating film 6b in the insulating layer 6 may be continuous, discontinuous like a sea island, or a combination thereof.

In the present invention, the patchy film made of a block copolymer having hydrophobic regions and hydrophilic regions constituting the insulating film 6b means a polymer film in which hydrophobic regions and hydrophilic regions are distributed in a mottled manner. . The insulating film 6b in the present invention is formed by supporting an inorganic compound on the hydrophilic polymer of the patchy film.

According to the coated particles having the above structure, since the insulating layer supports an inorganic compound, when a conductive material containing the coated particles is thermocompressed between electrodes in forming an electronic circuit, the insulating layer Since the inorganic compound region physically bites into the electrode, the coated particles can be fixed to the electrode, so conduction in the desired conduction direction can be sufficiently ensured, and conduction reliability can be improved. In addition, the surface portion of the coated particle facing in a direction other than the thermocompression bonding direction generally maintains the coating state of the conductive particle surface with the insulating layer, preventing conduction in unintended directions and improving the insulation properties. will be maintained.

The monomer component constituting the hydrophobic site of the block copolymer is preferably a compound that does not have a hydrophilic structure such as a carboxy group, an amino group, an ester bond, or an amide bond. Such monomer components include styrene, nuclear substituted styrenes such as o-, m- or p-methylstyrene, dimethylstyrene, ethylstyrene and chlorostyrene; α-methylstyrene, α-chlorostyrene and β-chlorostyrene, etc. Styrene derivatives; olefin monomers such as ethylene and propylene; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, phenyl (meth)acrylate, etc. esters of acrylic acid or methacrylic acid; examples include vinyl acetate. A "monomer component" refers to a structure derived from a monomer in a polymer, and is a component derived from a monomer. By subjecting the monomer to polymerization, a polymer containing the monomer component as a constituent unit is formed.

Examples of the monomer component constituting the hydrophilic site of the block copolymer include compounds having hydrophilic groups such as hydroxyl groups, carboxy groups, and amino groups. Such monomer components include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl acrylate, N,N- Esters of acrylic acid or methacrylic acid such as diethylaminoethyl methacrylate; α,β unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and their salts; acrylamide, methacrylamide, N,N-dimethylaminopropyl Acrylamides or methacrylamides such as acrylamide, N,N-dimethylaminopropylmethacrylamide, and N-methylolacrylamide; ammonium such as 3-(methacrylamido)propyltrimethylammonium hydrochloride and (3-acrylamidopropyl)trimethylammonium hydrochloride; Hydrochloride; Examples include 4-vinylpyridine and 4-vinylphenol. In the hydrophilic site, all of the monomer components may have a hydrophilic group, or some of the structural units may have a hydrophilic group. When some of the structural units have a hydrophilic group, the proportion of the monomer component having a hydrophilic group is preferably 50 mol% or more and 90 mol% or less, and 70 mol% or more and 95 mol% or less. It is more preferable that there be.

As monomer components, styrene is used as the monomer component that forms the hydrophobic part, and styrene is used as the monomer component that forms the hydrophilic part, because it easily forms patchy particles and has excellent adhesion to the surface of the conductive particles. Preferably, it is an ester of acrylic acid or methacrylic acid having an amino group, or an acrylamide or a methacrylamide. In particular, it is preferred that the monomer component constituting the hydrophobic site is styrene and the monomer component constituting the hydrophilic site is N,N-dimethylaminoethyl methacrylate.

In addition, from the viewpoint of achieving the above-mentioned effects more effectively, on the premise that an inorganic compound is supported on the hydrophilic region of the above-mentioned patchy particles or film, it is preferable that the hydrophobic region has a charged functional group. It is preferable that

The charged functional group is preferably present at the interface between the hydrophobic region of the insulating layer and the conductive particles. Further, it is preferable that the charged functional group is chemically bonded to a monomer component constituting the hydrophobic site of the block copolymer. That is, it is preferable that the hydrophobic site of the block copolymer is formed using a compound having a charged functional group as one of the monomer components. Whether or not a charged functional group exists at the interface between the hydrophobic region of the insulating layer and the conductive particles is determined by the fact that an insulating layer containing a hydrophobic region having a charged functional group is formed on the surface of the conductive particle. At this time, it can be determined by scanning electron microscopy observation whether or not the insulating layer is attached to the surface of the conductive particles.

Examples of the charged functional group include onium-based functional groups such as a phosphonium group, an ammonium group, and a sulfonium group. Among these, ammonium groups or phosphonium groups are preferable from the viewpoint of improving the adhesion between the conductive particles 5 and the insulating layer 6 and forming coated particles that have both insulation properties and continuity reliability at a high level. More preferred is a phosphonium group, and even more preferred is a phosphonium group.

Preferred examples of the onium-based functional group include those represented by the following general formula (1).

(wherein, n is 1 when X is a nitrogen atom or a phosphorus atom, and 0 when X is a sulfur atom. * is a bond.)

Examples of the counter anion in the onium-based functional group include halide ions. Examples of halide ions include Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ .

In formula (1), the linear alkyl group represented by R includes, for example, a linear alkyl group having 1 to 20 carbon atoms, and specifically, a methyl group, an ethyl group, an n- Propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n- Examples include tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group.

In formula (1), the branched alkyl group represented by R includes, for example, a branched alkyl group having 3 to 8 carbon atoms, and specifically, isopropyl group, isobutyl group, s- Examples include butyl group, t-butyl group, isopentyl group, s-pentyl group, t-pentyl group, isohexyl group, s-hexyl group, t-hexyl group, and ethylhexyl group.

In formula (1), the cyclic alkyl group represented by R includes cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, and cyclooctadecyl group. .

In formula (1), the aryl group represented by R includes a phenyl group, a benzyl group, a tolyl group, an o-xylyl group, and the like.

In general formula (1), R is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and R is an alkyl group having 1 to 8 carbon atoms. It is more preferable that Further, in general formula (1), it is also more preferable that R is a linear alkyl group. By having such a structure of the onium-based functional group, it is possible to improve the adhesion between the insulating layer 6 and the conductive particles 5 to ensure insulation, and to further improve the continuity reliability during thermocompression bonding. can.

From the viewpoint of facilitating monomer acquisition and polymer synthesis and increasing the production efficiency of the insulating layer, the hydrophobic moiety of the block copolymer constituting the insulating layer is expressed by the following general formula (2) or general formula (3). It is preferable to have the structural unit.

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

₍ ^{wherein ,} It is a methyl group.)

As examples of R in formulas (2) and (3), the above description of the functional group of R in general formula (1) is applied as appropriate. The ionic group may be bonded to the CH group of the benzene ring of formula (2) at any of the para, ortho, and meta positions, and is preferably bonded to the para position. In formulas (2) and (3), monovalent An 2 ^- is preferably a halide ion. Examples of halide ions include Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ .

In general formula (2), m is preferably an integer of 0 or more and 2 or less, more preferably 0 or 1, and particularly preferably 1. In general formula (3), m ¹ is preferably 1 or more and 3 or less, more preferably 1 or 2, and most preferably 2.

The hydrophobic portion of the block copolymer having a charged functional group is preferably configured to include a component derived from a monomer having an onium-based functional group and an ethylenically unsaturated bond, for example.

Examples of monomers having onium-based functional groups and ethylenically unsaturated bonds include ammonium group-containing monomers such as N,N,N-trimethyl-N-2-methacryloyloxyethylammonium chloride; phenyldimethylsulfonium methacrylate; Monomers with sulfonium groups such as methyl sulfate; 4-(vinylbenzyl)triethylphosphonium chloride, 4-(vinylbenzyl)trimethylphosphonium chloride, 4-(vinylbenzyl)tributylphosphonium chloride, 4-(vinylbenzyl)trioctylphosphonium Chloride, 4-(vinylbenzyl)triphenylphosphonium chloride, 2-(methacroyloxyethyl)trimethylphosphonium chloride, 2-(methacroyloxyethyl)triethylphosphonium chloride, 2-(methacroyloxyethyl)tributylphosphonium chloride, 2 -(Methacroyloxyethyl)trioctylphosphonium chloride, 2-(methacroyloxyethyl)triphenylphosphonium chloride, and other monomers having a phosphonium group. These non-crosslinkable monomers may be contained alone or in combination of two or more.

In the hydrophobic portion of the block copolymer constituting the insulating layer, the proportion of the monomer component containing a charged functional group is preferably 0.01 mol% or more and 20 mol% or less, and 0.02 mol% or more and 10 mol%. % or less is more preferable. If the proportion of monomer components containing electrically charged functional groups is high, it becomes difficult to form patchy particles, which is not preferable. Here, the number of monomer components in the hydrophobic site of the block copolymer is counted by counting a structure derived from one ethylenically unsaturated bond as one monomer constitutional unit.

The molar ratio of hydrophobic sites and hydrophilic sites in the block copolymer constituting the insulating layer is preferably hydrophobic sites:hydrophilic sites = 50:50 to 99:1, and preferably 60:40 to 98:2. It is even more preferable. Due to the presence of hydrophobic sites and hydrophilic sites in the insulating layer in such a molar ratio, when an inorganic compound is supported on the hydrophilic sites, it becomes easy to immobilize it on the electrode, and the insulation between the coated particles increases. It is possible to achieve both excellent conductivity and conduction reliability when the coated particles are used as a conductive material. The molar ratio of the hydrophobic site and the hydrophilic site can be measured, for example, by the method described in the Examples below.

Examples of inorganic compounds constituting the insulating layer 6 include silicon dioxide (silica), silicon carbide, silicon nitride, calcium phosphate, magnesium phosphate, magnesium oxide, zirconium oxide, aluminum oxide, aluminum nitride, nickel oxide, cobalt oxide, manganese oxide, Titanium oxide or the like can be used. Among these, silicon dioxide, aluminum oxide, titanium oxide, and zirconium oxide are preferred from the viewpoint of firming fixation to the electrode.

Next, the manner in which the insulating layer is formed on the coated particles will be described in detail. As described above, the insulating layer 6 in the coated particle 1 may have a form in which (i) insulating fine particles 6a are arranged in a layer on the surface of the conductive particle 5. That is, the coated particles 1 in this embodiment are made of a block copolymer having a hydrophobic region and a hydrophilic region, and the inorganic compound 7c is supported on the hydrophilic region of the patchy particle having a hydrophobic region and a hydrophilic region. The insulating layer 6 is formed by the presence of a plurality of insulating fine particles 6a on the surface of the conductive particles 5. Even if the insulating layer has such a configuration, the effects of the present invention can be sufficiently achieved.

From the viewpoint of achieving both excellent insulation properties and continuity reliability in a desired direction, the average particle diameter of the insulating fine particles 6a is preferably 80 nm or more and 3000 nm or less, more preferably 100 nm or more and 2000 nm or less. . From the same viewpoint, the average particle diameter of the conductive particles 5 is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 30 μm or less.

The average particle diameter mentioned above is the average value of particle diameters when 200 particles to be measured are measured using a scanning electron microscope. When the particle to be measured in a scanning electron microscope image is spherical, the particle diameter refers to the largest length (maximum length) of the line segments that intersect the two-dimensional projected image of the particle. Regarding the thickness of the insulating layer in this embodiment, the average particle diameter of the insulating particles having the largest average particle diameter among the insulating particles can be regarded as the thickness of the insulating layer.

Instead of the above-mentioned embodiment (i), the insulating layer 6 in the coated particle 1 may have a form in which (ii) the insulating film 6b is disposed on the surface of the conductive particle 5. That is, the coated particles 1 in this embodiment are made of a block copolymer having a hydrophobic region and a hydrophilic region, and the inorganic compound 8c is supported on the hydrophilic region of a patchy film having a hydrophobic region and a hydrophilic region. The insulating layer 6 is formed by disposing the insulating film 6b on the surface of the conductive particles 5. Even if the insulating layer has such a configuration, the effects of the present invention can be sufficiently achieved. The insulating film 6b corresponds to a film obtained by melting the insulating fine particles 6a. Here, "melting" means imparting fluidity to the block copolymer constituting the insulating fine particles 6a, and includes both a method using a solvent and a method using heating.

The thickness of the insulating film 6b is preferably smaller than the average particle diameter of the insulating fine particles 6a, more preferably 10 nm or more and 120 nm or less, and even more preferably 15 nm or more and 80 nm or less. When the thickness of the insulating film 6b is non-uniform, the thickness of the insulating film 6b may be such that both the maximum thickness and the minimum thickness thereof are within the above-mentioned range. The thickness of the insulating layer 6 in this embodiment can be measured, for example, by cutting the coated particle on which the insulating film 6b is formed into two pieces and observing the cross section of the cut part using an SEM.

When the insulating layer contains insulating fine particles, the particle size distribution of the insulating fine particles has a wide range. Generally, the width of the particle size distribution of powder is expressed by the coefficient of variation (hereinafter also referred to as "C.V.") shown by the following calculation formula (I).
C. V. (%) = (standard deviation/average particle diameter) x 100...(I)
This C. V. A large C. indicates that there is a wide range in particle size distribution; V. A small value indicates that the particle size distribution is sharp. The coated particles of this embodiment are C. V. It is desirable to use insulating fine particles whose content is preferably 0.1% or more and 20% or less, more preferably 0.5% or more and 19% or less. C. V. is within this range, which has the advantage that the thickness of the insulating layer containing the insulating fine particles can be made uniform.

When using conductive particles 5 in which a conductive film 3 is formed on the surface of a core material 2 as the coated particles 1, the glass transition temperature of the insulating layer 6 is preferably lower than the glass transition temperature of the core material 2. With such a configuration, the adhesion and adhesion between the insulating layer 6 and the conductive particles 5 can be improved.

When using particulate organic matter as the core material, it is important that the core material particles have no glass transition temperature or that the glass transition temperature is over 100°C so that the shape of the core material particles is easily maintained in the anisotropic conductive connection process. This is preferable because the shape of the core material particles can be easily maintained in the process of forming a conductive film. In addition, if the core material particles have a glass transition temperature, the glass transition temperature should be 200°C or less, since the conductive particles are likely to soften in anisotropic conductive connections, and the contact area will increase, making it easier to establish continuity. preferred. From this viewpoint, when the core material particles have a glass transition temperature, the glass transition temperature is more preferably higher than 100°C and lower than or equal to 180°C, particularly preferably higher than 100°C and lower than or equal to 160°C. The glass transition temperature can be measured by the method described in Examples below.

When an organic material is used as the core particle, and the organic material is a highly crosslinked resin, the glass transition temperature is hardly observed even if the measurement is attempted up to 200 ° C. by the method described in the following example. In this specification, such particles are also referred to as particles without a glass transition point. As a specific example of the core particle material that does not have such a glass transition temperature, it can be obtained by copolymerizing the monomers constituting the organic substance exemplified above with a crosslinkable monomer. can.

From the same viewpoint, when the core material has a glass transition temperature, the difference between the glass transition temperature of the insulating layer and the glass transition temperature of the core material is preferably 160°C or less, more preferably 120°C or less. Preferably, the temperature is particularly preferably 100°C or lower. Further, the difference between the glass transition temperature of the insulating layer and the glass transition temperature of the core material is preferably 5°C or more, more preferably 10°C or more.

Examples of methods for measuring 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 then cooled from that temperature to 25°C at a cooling rate of 5°C/min. . Next, the sample was heated at a heating rate of 5° C./min, and the amount of heat was measured. When a peak is observed, the temperature at the peak is measured, and when a step is observed without a peak, the tangent indicating the maximum slope of the curve at the step and the extension line of the baseline on the high temperature side of the step. The temperature at the intersection was defined as the glass transition temperature.

A preferred method for producing coated particles will be described below. This manufacturing method includes a step of mixing insulating fine particles 6a and conductive particles 5 to form an insulating layer 6 made of insulating fine particles 6a on the surface of the conductive particles 5.

First, conductive particles are prepared. When forming the conductive film 3 on the surface of the core material 2 to form the conductive particles 5, methods for forming the conductive film on the surface of the core material include, for example, vapor deposition, sputtering, etc. on the core material particles. Examples include a dry method using a method, a mechanochemical method, a hybridization method, etc., a wet method using an electrolytic plating method, an electroless plating method, etc., and these methods can be performed alone or in combination. Alternatively, commercially available conductive particles may be used.

Furthermore, a plurality of insulating fine particles 6a forming the insulating layer 6 are formed before or after the above-described process, or simultaneously with the above-described process. Specifically, after obtaining a block copolymer having a hydrophobic site and a hydrophilic site, an inorganic compound is supported on the hydrophilic site to obtain insulating fine particles.

Methods for obtaining a block copolymer having a hydrophobic site and a hydrophilic site include a method in which a hydrophilic monomer component is living-polymerized to form a hydrophilic site, and then a hydrophobic monomer component is polymerized; A method of polymerizing to form a hydrophobic site and then polymerizing a hydrophilic monomer component, a method in which a hydrophobic monomer component and a hydrophilic monomer component are separately polymerized to obtain a hydrophobic polymer and a hydrophilic polymer, and then the hydrophobic Examples include a method of coupling a polymer with the hydrophilic polymer. A known method may be used to obtain a block copolymer by living polymerization, such as controlled living radical polymerization, and specifically, atom transfer radical polymerization (ATRP), nitroxide-mediated polymerization (NMP), and reversible polymerization. Examples include addition-fragmentation chain transfer (RAFT) polymerization.

The block copolymer preferably has a molecular weight of 100,000 or more. If the molecular weight is less than 100,000, it becomes difficult to form patchy particles, and the particle size of the obtained particles becomes small.

In the production method of the present invention, in order to support an inorganic compound on the hydrophilic sites of the obtained block copolymer, patchy particles 7 in which hydrophobic regions and hydrophilic regions are distributed in a patchy manner are prepared. The method for producing the patchy particles is not particularly limited as long as the hydrophobic regions and hydrophilic regions are distributed in a patchy manner, but for example, a method using self-assembly of a block copolymer may be mentioned. By emulsifying the dispersed phase in which the polymer is dissolved in the continuous phase containing a surfactant and evaporating the solvent in the dispersed phase, the difference in solubility of each block in the solvent in the dispersed phase and the difference in the solubility of each block to the solvent in the dispersed phase can be determined. Due to the difference in affinity, each block undergoes phase separation and self-organization, producing patchy particles.

Specifically, a method may be mentioned in which the block copolymer is dispersed in an organic solvent and then added dropwise to an aqueous phase to form droplets. Specifically, the obtained block copolymer is poured into an organic solvent with higher volatility than water to obtain a solution in which the block copolymer is dissolved. By pouring this solution into water and stirring, an aqueous solution in which block copolymer droplets are dispersed is obtained. By stirring this aqueous solution at room temperature, the organic solvent in the droplets evaporates, so that block copolymer particles are obtained. As a result, patchy particles 7, which are particles in which hydrophobic regions 7a and hydrophilic regions 7b are distributed in a patchy manner, as shown in FIG. 3(a) are obtained.

Examples of the organic solvent include pentane, n-hexane, cyclohexane, dicyclomethane, 1,2-dicyclomethane, chloroform, carbon tetrachloride, diethyl ether, ethyl acetate, benzene, and the like.

Next, an inorganic compound 7c is supported on the hydrophilic regions 7b of the obtained patchy particles 7 to obtain insulating fine particles 6a. An example of a method for supporting an inorganic compound in a hydrophilic region is a method of reacting an inorganic compound precursor with a hydrophilic group in a hydrophilic portion of a block copolymer.

Examples of the inorganic compound precursor include triethylsilane, trimethoxysilane, triethoxysilane, chlorodimethylsilane, triethylchlorosilane, tetramethyldisiloxane, tetramethoxysilane, tetraethoxysilane, 1,1,3,3-tetra Methyldisilazane, 1,2-diethoxy-1,1,2,2-tetramethyldisilazane, tetramethoxytitanium, tetraethoxytitanium, trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, tris(1-methylpropoxy ) Aluminum, aluminum diisopropyl monosec-butyrate, zirconium (IV) tetrabutoxide, zirconium (IV) tetrapropoxide, zirconium (IV) acetylacetonate, and the like.

The inorganic compound is supported on the hydrophilic site of the block copolymer by a reaction between a hydrophilic group and an inorganic compound precursor, and includes, for example, silicon dioxide, titanium oxide, aluminum oxide, zirconium oxide, and the like.

Next, the insulating fine particles obtained in the above step and conductive particles are mixed to obtain coated particles having an insulating layer made of the insulating fine particles on the surface of the conductive particles. When using the above-mentioned insulating fine particles, for example, the insulating fine particles and conductive particles are mixed to form coated particles having an insulating layer 6 containing insulating fine particles 6a on the surface of the conductive particles 5. .

When mixing insulating fine particles and conductive particles, it is preferable to add these particles to a dispersion medium to form a dispersion liquid. Examples of the dispersion medium include water, organic solvents, and mixtures thereof, and water, ethanol, or a mixture of ethanol and water is preferably used.

It is preferable that the dispersion liquid contains an inorganic salt, an organic salt, or an organic acid because coated particles having an insulating layer coverage of a certain level or more can be easily obtained. As the inorganic salt, organic salt, or organic acid, those that dissociate anions are preferably used. Suitable anions include Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ , SO ₄ ²⁻ , CO ₃ ²⁻ , NO ₃ ⁻ , COO ⁻ , RCOO ⁻ (R is an organic group), and the like. Examples of inorganic salts include NaCl, KCl, LiCl, MgCl ₂ , BaCl ₂ , NaF, KF, LiF, MgF ₂ , BaF ₂ , NaBr, KBr, LiBr, MgBr ₂ , BaBr ₂ , NaI, KI, LiI, MgI ₂ , _BaI2 , _Na2SO4 , _K2SO4 , _{Li2SO4 , MgSO4 , Na2CO3} , _{NaHCO3 , K2CO3} , _{KHCO3 , Li2CO3} , _{LiHCO3 , MgCO3 ,} NaNO ₃ , _KNO3 , _LiNO3 , _MgNO3 , _BaNO3, etc. can be used. Further, as the organic salt, Na oxalate, Na acetate, Na citrate, Na tartrate, etc. 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, etc. can be used.

Preferred concentrations of inorganic salts, organic salts, and organic acids vary depending on how much of the surface area of the conductive particles is covered by the insulating fine particles, but in the dispersion after mixing the conductive particles, 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 rate and it is easy to obtain coated particles in which the insulating fine particles have a single layer. From this viewpoint, it is particularly preferable that the concentration of the inorganic salt, organic salt, and organic acid in the dispersion is 1.0 mmol/L or more and 80 mmol/L or less.

In a dispersion containing insulating fine particles and conductive particles, the conductive particles are preferably contained in an amount of 100 ppm or more and 100,000 ppm or less, more preferably 500 ppm or more and 80,000 ppm or less, based on mass. Furthermore, the content of the insulating fine particles is preferably 10 ppm or more and 50,000 ppm or less, and more preferably 250 ppm or more and 30,000 ppm or less, based on mass.

From the viewpoint of obtaining coated particles of constant quality, the temperature of the dispersion liquid is preferably 20°C or more and 100°C or less, and 40°C or more and 100°C or less when mixing the insulating fine particles and the conductive particles. It is even more preferable. In particular, when the glass transition temperature of the polymer having the lowest glass transition temperature is Tg (°C), the temperature of the dispersion liquid is preferably Tg - 30°C or more and Tg + 30°C or less. Within this range, the insulating fine particles easily adhere to the surface of the conductive particles while maintaining their shape. In particular, since the affinity between insulating fine particles and conductive particles can be further improved, coated particles with sufficiently high coverage can be produced.

The dispersion time in the dispersion liquid is preferably 0.1 hour or more and 24 hours or less, so that the insulating fine particles and the conductive particles can be sufficiently attached. During this time, it is preferable to stir the dispersion. Thereafter, if necessary, the solid content of the dispersion is washed and dried to obtain coated particles in which insulating fine particles adhere to the surfaces of conductive particles. The coated particles 1 thus obtained have an insulating layer 6 formed on the surface of the conductive particle 5 to which a plurality of insulating fine particles 6a are attached.

When forming a continuous film on the insulating layer 6, the coated particles 1 in which a plurality of insulating fine particles 6a are attached to the surface of the conductive particles 5 are treated with an organic solvent or heated. By making the insulating fine particles 6a highly fluid, the insulating layer 6 can be formed by an insulating film 6b covering the surface of the conductive particles 5 in the form of a film. By forming the insulating layer in the form of a film, the adhesion between the insulating layer and the conductive particles can be increased, resulting in higher insulation.

Coated particles in which insulating fine particles are attached to the conductive particle surface can be made to flow by adding an organic solvent to the dispersion, so the conductive particle surface can be coated in a film form. can do. When melting the insulating fine particles, tetrahydrofuran, toluene, methyl ethyl ketone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, and the like can be used as the organic solvent. The amount of organic solvent added should be 1 part by mass or more and 100 parts by mass or less per 1 part by mass of the coated particles in the dispersion liquid, from the viewpoint of easily forming a uniform film without causing the insulating fine particles to fall off. is preferable, and more preferably 5 parts by mass or more and 50 parts by mass or less. The addition temperature is preferably 10° C. or more and 100° C. or less, more preferably 20° C. or more and 80° C. or less, from the viewpoint of easily forming a uniform film without causing the insulating fine particles to fall off. Further, the time required to form a film after addition is preferably 0.1 hour or more and 24 hours or less in order to form a uniform film. In this way, as shown in FIG. 2(b), the insulating layer 6 having the insulating film 6b can be suitably formed.

The coated particles can be heated by heating a dispersion liquid after attaching insulating fine particles to the surface of the conductive particles, or by re-dispersing the obtained coated particles in a solvent such as water. Examples include a method of heating in a solvent, and a method of heating the obtained coated particles in a gas phase such as an inert gas. The heating temperature is Tg + 1°C or more and Tg + 60°C or less, where the glass transition temperature of the polymer that makes up the insulating particles is Tg (°C), since it is easy to form a uniform film without the insulating particles falling off. is preferable, Tg+5°C or higher and Tg+50°C or lower is more preferable, and most preferably Tg+15°C or higher. The heating time is preferably 0.1 hour or more and 24 hours or less in order to easily form a uniform film. Furthermore, when the coated particles are heated in a gas phase, the pressure conditions can be atmospheric pressure, reduced pressure, or increased pressure. In this way, as shown in FIG. 2(b), the insulating layer 6 having the insulating film 6b can be suitably formed.

The coated particles in which the surface of the conductive particles is coated in a film form may be subjected to an annealing treatment in order to further stabilize the continuous film. Examples of the annealing treatment 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 (°C) is the glass transition temperature of the polymer constituting the insulating fine particles. The heating atmosphere is not particularly limited, and heating can be carried out in an inert gas atmosphere such as nitrogen or argon, or an oxidizing atmosphere such as air, under atmospheric pressure, reduced pressure, or increased pressure.

The coated particles obtained as described above have an insulating layer formed from insulating fine particles supporting an inorganic compound or an insulating film supporting an inorganic compound, so that when bonded by thermocompression between electrodes, the inorganic The compound makes it easier for the coated particles to be immobilized on the electrode, resulting in improved conduction reliability. The coated particles of the present invention are suitably used as conductive materials such as conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives. These conductive materials contain the coated particles of the present invention and an insulating resin such as an epoxy resin or an acrylic resin, and are preferably a mixture of these. The conductive material may further contain a resin curing agent or an organic solvent, if necessary.

The present invention will be explained below using examples. However, the scope of the present invention is not limited to these examples. The properties in the examples were measured by the following methods.

(1) Molecular weight of block copolymer The sample to be measured was measured using a gel permeation chromatography device (manufactured by Tosoh Corporation, HLC-8220GPC).

(2) Average particle diameter of insulating fine particles The sample to be measured was measured using a dynamic light scattering device (manufactured by Otsuka Electronics Co., Ltd., ELS-8000).

(3) Average particle diameter of coated particles Select 200 particles from a scanning electron microscope (SEM) photograph of the measurement target (100,000x magnification for insulating particles, 10,000x magnification for conductive particles, 10,000x magnification for coated particles). The particles were extracted and the above particle diameters were measured, and the arithmetic mean value was taken as the average particle diameter.

(4)C. V. (coefficient of variation)
It was determined from the above average particle diameter measurement using the following formula.
C. V. (%) = (standard deviation/average particle diameter) x 100

(5) Maximum thickness of insulating layer The maximum thickness of the insulating layer was measured by the method described above.

[Example 1]
[Step 1. Production of patchy particles]
In a 20 mL eggplant flask, add 7.86 g of 2-(N,N-dimethylamino)ethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 6.3 mg of cumyl dithiobenzoate (manufactured by Sigma-Aldrich), and 2,2'- 2.1 mg of azobis(isobutyronitrile) (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 1.5 mL of tetrahydrofuran (manufactured by Kanto Kagaku Co., Ltd.) were added, and after degassing, the mixture was filled with nitrogen. A polymerization reaction was carried out for 24 hours while stirring this reaction solution in an oil bath at 60°C. After cooling in an ice bath, tetrahydrofuran was added to the reaction solution to dilute it, and the solid was purified by reprecipitation in n-hexane (manufactured by Kanto Kagaku Co., Ltd.). The precipitate obtained by decantation was dried under reduced pressure at 40°C to obtain a polymer having 2-(N,N-dimethylamino)ethyl methacrylate as its main chain.
Next, 0.3 g of the above polymer, 0.733 mg of styrene (manufactured by Kanto Kagaku Co., Ltd.), and 0.73 mg of 2,2'-azobis(isobutyronitrile) (manufactured by Tokyo Kasei Kogyo Co., Ltd.) were placed in a 10 mL eggplant flask. .0578 mg and 1.0 mL of tetrahydrofuran (manufactured by Kanto Kagaku Co., Ltd.) were added, and after degassing, nitrogen was filled. A polymerization reaction was carried out for 78 hours while stirring this reaction solution in an oil bath at 60°C. After cooling in an ice bath, tetrahydrofuran was added to the reaction solution to dilute it, and the solid was purified by reprecipitation in n-hexane (manufactured by Kanto Kagaku Co., Ltd.). The precipitate obtained by decantation was dried under reduced pressure at 40° C. to obtain a block copolymer of 2-(N,N-dimethylamino)ethyl methacrylate and styrene.
The obtained block copolymer had a molecular weight (Mn) of 120,000 and a polydispersity (Mw/Mn) of 1.43.
Next, 30 mL of pure water was poured into a 100 mL sample tube. Thereafter, 150 mg of hexadecyltrimethylammonium bromide (manufactured by Wako Pure Chemical Industries, Ltd.) as a surfactant was added and dissolved to obtain Solution A. Separately, 2.25 mL of chloroform (manufactured by Kanto Kagaku Co., Ltd.) and 33.75 mg of the block copolymer were placed in a 100 mL sample tube to obtain Solution B. This B solution was added to a sample tube containing A solution and stirred at 12,000 rpm to obtain droplets. The resulting droplets were allowed to stand at room temperature while being slowly stirred, and the oil phase of the droplets was evaporated to obtain patchy particles of poly(2-(N,N-dimethylamino)ethyl methacrylate/styrene).
¹ H-NMR of the obtained patchy particles was measured using a Fourier transform nuclear magnetic resonance spectrometer (manufactured by JEOL, JNM-ECS400). The results are shown in FIG. From this result, a peak derived from polystyrene with δ = 7.4 to 6.1 ppm and a peak derived from poly(2-(N,N-dimethylamino)ethyl methacrylate) with δ = 4.01 ppm were observed. Further, the results of measuring the obtained patchy particles using a Fourier transform infrared spectrophotometer (manufactured by JASCO, FT/IR-420) are shown in FIG. 5, and a TEM photograph is shown in FIG.

[Step 2. Production of insulating fine particles]
Next, 20 mg of the above-mentioned patchy particles, 0.4 mL of tetraethyl orthosilicate (manufactured by Wako Pure Chemical Industries, Ltd.), 0.8 mL of methanol (manufactured by Kanto Chemical Co., Ltd.), and 1.2 mL of pure water were added to a 5 mL sample bottle. The mixture was left at room temperature for 24 hours with stirring. Thereafter, the particles were separated by centrifugation and purified by repeating the procedure of redispersing them in methanol several times to obtain insulating fine particles. The average particle diameter of the insulating fine particles was 361 nm.
The obtained insulating fine particles were measured using a Fourier transform infrared spectrophotometer (manufactured by JASCO, FT/IR-420). The results are shown in FIG. From this result, a peak derived from Si-O was observed at 1080 cm ^-1 , and the peak derived from poly(2-(N,N-dimethylamino)ethyl methacrylate) was relatively weakened. It was confirmed that SiO ₂ was supported on the 2-(N,N-dimethylamino)ethyl methacrylate) portion.

[Step 3. Production of coated particles]
As the core material, spherical particles made of crosslinkable acrylic resin (glass transition temperature: 120 ° C.) are used, and the core material particles have a conductive film made of nickel with a thickness of 0.125 μm on the surface, and have an average particle size. Conductive particles (Ni-plated particles; manufactured by Nihon Kagaku Kogyo Co., Ltd.) having a diameter of 3 μm and a smooth surface were prepared. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. 10 mL of a 1% by mass aqueous solution of benzotriazole was added to this dispersion and stirred for 5 minutes to perform surface treatment. Thereafter, the mixture was filtered through a membrane filter with an opening of 2.0 μm to collect Ni-plated particles having a benzotriazole layer on the surface. The insulating fine particles obtained above and Na ₂ SO ₄ were added to a dispersion of the Ni-plated particles in 100 mL of pure water, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol/L. After removing the supernatant liquid, performing solid-liquid separation, adding fresh pure water and washing, the procedure was repeated three times, followed by vacuum drying at 50° C. to obtain coated particles. The average particle diameter of the obtained coated particles was 3.4 μm.

[Example 2]
1.0 g of the coated particles obtained in Example 1 were poured into 20 mL of pure water to obtain a dispersion. 10 mL of tetrahydrofuran was added to this dispersion, and the mixture was stirred at room temperature for 6 hours. After stirring, the solids are separated using a membrane filter with an opening of 2 μm and dried to form a part in which SiO ₂ is supported on the surface of the conductive particles and a film-like part in which the insulating fine particles are melted. Coated particles having an insulating layer were obtained. The average particle diameter of the coated particles was 3.4 μm.

[Example 3]
1.0 g of the coated particles obtained in Example 1 were added to 20 mL of pure water to form a dispersion, and the dispersion was stirred at 95° C. for 6 hours. After stirring, the solids are separated using a membrane filter with an opening of 2 μm and dried to form a part in which SiO ₂ is supported on the surface of the conductive particles and a film-like part in which the insulating fine particles are melted. Coated particles having an insulating layer were obtained. The average particle diameter of the coated particles was 3.4 μm.

[Example 4]
In Example 1, coated particles were produced in the same manner as in Example 1, except that the conditions for the production process of coated particles in Step 3 were changed to Ni-plated particles having a large number of protrusions with an average height of 0.1 μm. The average particle diameter of the coated particles was 3.4 μm.

[Example 5]
[Step 1. Production of phosphonium-based patchy particles]
In a 20 mL eggplant flask, add 7.86 g of 2-(N,N-dimethylamino)ethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 6.3 mg of cumyl dithiobenzoate (manufactured by Sigma-Aldrich), and 2,2'- 2.1 mg of azobis(isobutyronitrile) (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 1.5 mL of tetrahydrofuran (manufactured by Kanto Kagaku Co., Ltd.) were added, and after degassing, the mixture was filled with nitrogen. A polymerization reaction was carried out for 24 hours while stirring this reaction solution in an oil bath at 60°C. After cooling in an ice bath, tetrahydrofuran was added to the reaction solution to dilute it, and the solid was purified by reprecipitation in n-hexane (manufactured by Kanto Kagaku Co., Ltd.). The precipitate obtained by decantation was dried under reduced pressure at 40°C to obtain a polymer having 2-(N,N-dimethylamino)ethyl methacrylate as its main chain.
Next, in a 10 mL eggplant flask, 0.3 g of the polymer, 0.733 mg of styrene (manufactured by Kanto Kagaku Co., Ltd.), 0.02 mg of 4-(vinylbenzyl)triethylphosphonium chloride (manufactured by Nihon Kagaku Kogyo Co., Ltd.), 0.0578 mg of 2,2'-azobis(isobutyronitrile) (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 1.0 mL of tetrahydrofuran (manufactured by Kanto Kagaku Co., Ltd.) were added, and after degassing, the mixture was filled with nitrogen. A polymerization reaction was carried out for 78 hours while stirring this reaction solution in an oil bath at 60°C. After cooling in an ice bath, tetrahydrofuran was added to the reaction solution to dilute it, and the solid was purified by reprecipitation in n-hexane (manufactured by Kanto Kagaku Co., Ltd.). The precipitate obtained by decantation was dried under reduced pressure at 40° C. to obtain a block copolymer of 2-(N,N-dimethylamino)ethyl methacrylate and styrene having a phosphonium group.
The obtained block copolymer had a molecular weight (Mn) of 110,000 and a polydispersity (Mw/Mn) of 1.40.
Next, 30 mL of pure water was poured into a 100 mL sample tube. Thereafter, 150 mg of hexadecyltrimethylammonium bromide (manufactured by Wako Pure Chemical Industries, Ltd.) as a surfactant was added and dissolved to obtain Solution A. Separately, 2.25 mL of chloroform (manufactured by Kanto Kagaku Co., Ltd.) and 33.75 mg of the block copolymer were placed in a 100 mL sample tube to obtain Solution B. This B solution was added to a sample tube containing A solution and stirred at 12,000 rpm to obtain droplets. The resulting droplets were left at room temperature with slow stirring, and the oil phase of the droplets was evaporated to form poly(2-(N,N-dimethylamino)ethyl methacrylate/styrene/4-(vinylbenzyl)triethylphosphonium). mottled particles of chloride) were obtained.
When ¹ H-NMR of the obtained patchy particles was measured using a Fourier transform nuclear magnetic resonance spectrometer (manufactured by JEOL, JNM-ECS400), a peak derived from polystyrene at δ = 7.4 to 6.1 ppm and a peak derived from δ = 7.4 to 6.1 ppm were found. A peak of 4.01 ppm derived from poly(2-(N,N-dimethylamino)ethyl methacrylate) was observed.

[Step 2. Production of phosphonium-based insulating fine particles]
Next, 20 mg of the above-mentioned patchy particles, 0.4 mL of tetraethyl orthosilicate (manufactured by Wako Pure Chemical Industries, Ltd.), 0.8 mL of methanol (manufactured by Kanto Chemical Co., Ltd.), and 1.2 mL of pure water were added to a 5 mL sample bottle. The mixture was left at room temperature for 24 hours with stirring. Thereafter, the particles were separated by centrifugation and redispersed in methanol for purification, which was repeated three times to obtain insulating fine particles. The average particle diameter of the insulating fine particles was 361 nm.
When the obtained insulating fine particles were measured using a Fourier transform infrared spectrophotometer (manufactured by JASCO, FT/IR-420), a peak derived from Si-O was observed at 1080 cm ^-1 , and a relatively poly(2 -(N,N-dimethylamino)ethyl methacrylate) was weakened, indicating that SiO ₂ was supported on the poly(2-(N,N-dimethylamino)ethyl methacrylate) portion of the patchy particles. It was confirmed.

[Step 3. Production of coated particles]
As the core material, spherical particles made of crosslinkable acrylic resin (glass transition temperature: 120 ° C.) are used, and the core material particles have a conductive film made of nickel with a thickness of 0.125 μm on the surface, and have an average particle size. Conductive particles (Ni-plated particles; manufactured by Nihon Kagaku Kogyo Co., Ltd.) having a diameter of 3 μm and a smooth surface were prepared. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. 10 mL of a 1% by mass aqueous solution of benzotriazole was added to this dispersion and stirred for 5 minutes to perform surface treatment. Thereafter, the mixture was filtered through a membrane filter with an opening of 2.0 μm to collect Ni-plated particles having a benzotriazole layer on the surface. The insulating fine particles obtained above and Na ₂ SO ₄ were added to a dispersion of the Ni-plated particles in 100 mL of pure water, and the mixture was stirred at 40° C. for 30 minutes. After the insulating fine particles and Na ₂ SO ₄ were added, the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol/L. After removing the supernatant liquid, performing solid-liquid separation, adding fresh pure water and washing, the procedure was repeated three times, followed by vacuum drying at 50° C. to obtain coated particles. The average particle diameter of the obtained coated particles was 3.4 μm.

[Example 6]
1.0 g of the coated particles obtained in Example 5 were poured into 20 mL of pure water to obtain a dispersion. 10 mL of tetrahydrofuran was added to this dispersion, and the mixture was stirred at room temperature for 6 hours. After stirring, the solids are separated using a membrane filter with an opening of 2 μm and dried to form a part in which SiO ₂ is supported on the surface of the conductive particles and a film-like part in which the insulating fine particles are melted. Coated particles having an insulating layer were obtained. The average particle diameter of the coated particles was 3.4 μm.

[Example 7]
1.0 g of the coated particles obtained in Example 5 were added to 20 mL of pure water to form a dispersion, and the dispersion was stirred at 95° C. for 6 hours. After stirring, the solids are separated using a membrane filter with an opening of 2 μm and dried to form a part in which SiO ₂ is supported on the surface of the conductive particles and a film-like part in which the insulating fine particles are melted. Coated particles having an insulating layer were obtained. The average particle diameter of the coated particles was 3.4 μm.
[Example 8]
In Example 5, coated particles were manufactured in the same manner as in Example 5, except that the conditions for the manufacturing process of coated particles in Step 3 were changed to Ni-plated particles having a large number of protrusions with an average height of 0.1 μm. The average particle diameter of the coated particles was 3.4 μm.

[Comparative example 1]
Coated particles were produced in the same manner as in Example 1, except that the patchy particles obtained in Step 1 were used as insulating fine particles and coated with Ni-plated particles to produce coated particles. The average particle diameter of the coated particles was 3.4 μm.

[Comparative example 2]
In Example 1, the patchy particles obtained in Step 1 were used as insulating fine particles and coated with Ni-plated particles to produce coated particles. 1.0 g of the coated particles were put into 20 mL of pure water to obtain a dispersion. 10 mL of tetrahydrofuran was added to this dispersion, and the mixture was stirred at room temperature for 6 hours. After stirring, the solid matter was separated using a membrane filter with an opening of 2 μm and dried to obtain coated particles having an insulating layer in which a film-like portion of melted insulating fine particles was formed. The average particle diameter of the coated particles was 3.4 μm.

[Comparative example 3]
In Example 5, coated particles were produced in the same manner as in Example 5, except that the patchy particles obtained in Step 1 were used as insulating fine particles to produce coated particles. The average particle diameter of the coated particles was 3.4 μm.

[Evaluation of coverage]
The coverage of the coated particles obtained in Examples and Comparative Examples was calculated by the following method. That is, a backscattered electron composition (COMPO) image of a SEM photographic image of the coated particles is taken into an automatic image analyzer (Luzex (registered trademark) AP, manufactured by Nireco Co., Ltd.), and 20 coated particles in the COMPO image are coated. The coverage of particles was calculated. The higher the coverage, the more densely formed the insulating layer is. The results are shown in Table 1.

[Evaluation of conductivity and insulation]
Using the coated particles of Examples and Comparative Examples, conductivity and insulation were evaluated by the following method.

[Evaluation of conductivity]
An insulating adhesive prepared 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 coated particles obtained in Examples and Comparative Examples to obtain an insulating paste. Ta. This paste was applied onto a siliconized 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 whose entire surface was vapor-deposited with aluminum and a polyimide film substrate on which copper patterns were formed at a pitch of 50 μm, and electrical connection was made. By measuring the conduction resistance between the substrates, the conductivity of the coated particles was evaluated at room temperature (25° C., 50% RH). It can be evaluated that the lower the resistance value, the higher the conductivity of the coated particles. In evaluating the conductivity of coated particles, those with a resistance value of less than 2Ω are rated “very good” (indicated by the symbol “○” in Table 1), and those with a resistance value of 2Ω or more and less than 5Ω are rated “good”. ” (indicated by the symbol “△” in Table 1), and those with a resistance value of 5Ω or more were determined to be “defective” (indicated by the symbol “×” in Table 1). The results are shown in Table 1.

[Evaluation of insulation]
Using a micro compression tester MCTM-500 (manufactured by Shimadzu Corporation), the coated particles of Examples and Comparative Examples were compressed at a load rate of 0.5 mN/sec for 20 coated particles, and the resistance was measured. The insulation properties of the coated particles were evaluated by measuring the compressive displacement until a value was detected. The larger the compressive displacement until the resistance value is detected, the higher the insulation properties of the coated particles can be evaluated. The insulation properties of the coated particles are evaluated as "very good" (indicated by the symbol "○" in Table 1) if the arithmetic mean value of the compressive displacement until the resistance value is detected is 10% or more. Those whose arithmetic mean value of compressive displacement is more than 3% and less than 10% are considered "good" (indicated by the symbol "△" in Table 1), and those whose arithmetic mean value of compressive displacement is 3% or less are "good". "Poor" (indicated by the symbol "x" in Table 1). The results are shown in Table 1.

As shown in Table 1, it can be seen that the coated particles of the present invention are formed with high coverage and adhesion of the insulating layer, and thus have excellent insulation properties as well as excellent conduction reliability.

1 Coated particles 2 Core material 3 Metal coating 5 Conductive particles 6 Insulating layer 6a Insulating fine particles 6b Insulating coating 7 Mottled particles 7a, 8a Hydrophobic region 7b Hydrophilic region 7c, 8c Inorganic compound

Claims (12)

Comprising conductive particles with a metal film formed on the surface of a core material, and an insulating layer covering the conductive particles,
The insulating layer includes a block copolymer having a hydrophobic site and a hydrophilic site,
An inorganic compound is supported on the hydrophilic site of the block copolymer.
coated particles. The insulating layer is made of insulating fine particles made of a block copolymer having a hydrophobic part and a hydrophilic part, and having an inorganic compound supported on the hydrophilic region of mottled particles having a hydrophobic region and a hydrophilic region on the surface. The coated particle according to claim 1, comprising: The coated particle according to claim 2, wherein the insulating layer is an insulating film formed by melting the insulating fine particles into a film form. The coated particle according to any one of claims 1 to 3, wherein the hydrophobic site contains a monomer component having a charged functional group. The coated particle according to claim 4, wherein the charged functional group is an ammonium group or a phosphonium group. The monomer component of the hydrophobic site is styrene, o-, m- or p-methylstyrene, dimethylstyrene, ethylstyrene, chlorostyrene, vinyl acetate, methyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylate, etc. ) The coated particles according to any one of claims 1 to 5, which are at least one selected from propyl acrylate, n-butyl (meth)acrylate, and phenyl (meth)acrylate. The monomer component of the hydrophilic site is N,N-dimethylaminoethyl methacrylate, acrylamide, N-methylolacrylamide, 2-hydroxyethyl methacrylate, 3-(methacrylamido)propyltrimethylammonium hydrochloride, (3-acrylamidopropyl) The coated particles according to any one of claims 1 to 6, which are at least one selected from trimethylammonium hydrochloride and 4-vinylpyridine. The coated particles according to any one of claims 1 to 7, wherein the inorganic compound is at least one selected from silicon dioxide, aluminum oxide, titanium oxide, and zirconium oxide. The coated particle according to any one of claims 1 to 8, wherein the metal constituting the metal film is at least one selected from nickel, gold, nickel alloy, and gold alloy. A method for producing coated particles comprising conductive particles having a metal coating formed on the surface of a core material and an insulating layer covering the conductive particles, the method comprising:
obtaining patchy particles consisting of a block copolymer having a hydrophobic site and a hydrophilic site and having a hydrophobic area and a hydrophilic area on the surface;
a step of reacting an inorganic compound precursor with the hydrophilic region of the patchy particles to obtain insulating fine particles carrying an inorganic compound;
mixing the insulating fine particles and the conductive particles to obtain coated particles having an insulating layer;
A method for producing coated particles comprising: 11. The method for producing coated particles according to claim 10, further comprising the step of melting the insulating fine particles with an organic solvent to obtain coated particles having an insulating layer including an insulating film, after the step of obtaining the coated particles. 11. The method for producing coated particles according to claim 10, further comprising the step of melting the insulating fine particles by heating to obtain coated particles having an insulating layer including an insulating film, after the step of obtaining the coated particles.

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