JP2020035544A - Coated particle - Google Patents

Abstract

To provide a coated particle in which a conductive particle surface having a metal coated film on a surface of a core material is coated by an insulation layer, oxidation of the metal coated film on the conductive particle surface is effectively prevented, and the conductive particle surface can be coated tightly by the insulation layer when the insulation layer is an insulation fine particle or a continuous coated film by melting or dissolving the same.SOLUTION: The coated particle has a conductive metal coated particle having a metal coated film on a surface of a core material, and an insulation layer consisting of a polymer coating the metal coated particle, and the insulation layer has a phosphonium group represented by the following formula (1). In the formula, R is each independently an alkyl group having 4 to 10 carbon atoms.SELECTED DRAWING: Figure 1

Description

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

BACKGROUND ART Conductive particles in which a metal such as nickel or gold is formed on the surface of a resin particle are used as a conductive material such as a conductive adhesive, an anisotropic conductive film, and an anisotropic conductive adhesive.
In recent years, with further miniaturization of electronic devices, circuit widths and pitches of electronic circuits have become increasingly smaller. Accordingly, conductive particles having a small particle size have been demanded for use in the above-described conductive adhesives, anisotropic conductive films, anisotropic conductive adhesives, and the like. When conductive particles having such a small particle size are used, the blending amount of the conductive particles must be increased in order to enhance the connectivity. However, when the blending amount of the conductive particles is increased, conduction in an unintended direction, that is, conduction in a direction different from that between the opposed electrodes causes a short circuit, and it is difficult to obtain insulation in the direction. ing. In order to solve this problem, conductive particles coated with an insulating layer in which the surfaces of the conductive particles are coated with an insulating substance to prevent the metal layers of the conductive particles from contacting each other are used. Generally, the coated particles having such a configuration are exposed to the metal surface of the metal-coated particles by melting, deforming, or peeling the insulating fine particles by pressing the coated particles between the electrodes, whereby the conduction between the electrodes is performed. Becomes possible and connectivity is obtained.

  For example, Non-Patent Document 1 describes a coated particle in which the surface of a conductive particle is coated with insulating fine particles having a triethylphosphonium group.

Proceedings of the 66th Symposium on Polymers Vol.66, No.2, P 60

The insulating fine particles having a phosphonium group as described in Non-Patent Document 1 have better adhesion to the conductive particles than the insulating fine particles having a positive charge such as an ammonium group used in the related art. high.
On the other hand, conductive particles having a metal film such as nickel are required to sufficiently prevent oxidation of the metal film. If the metal film is oxidized, the conductivity may decrease with time.
In addition, in the case of coated particles made of conductive particles coated with insulating fine particles, it is also required that the surface of the metal-coated particles be easily covered with the insulating fine particles. When the surface of the metal-coated particles is not sufficiently densely covered with the insulating fine particles, a part of the surface of the conductive particles is not coated, and when the conductive particles are close to each other inside the anisotropic conductive film, the film is There is a possibility of electrical contact in the plane direction of. In addition, there is a possibility that the insulating property cannot be ensured because the insulating fine particles are slightly peeled off from the surface of the metal-coated particles during the production of the conductive material or the thermocompression bonding of the device production.
However, the coated particles coated with the conventional insulating fine particles described in Non-Patent Document 1 are sufficient in terms of both the prevention of oxidation of the metal film and the close coverage of the insulating fine particles on the surface of the metal coated particles. Was not.

  Therefore, an object of the present invention is to provide an insulating layer-coated conductive particle that can solve the problems of conventional coated particles.

  The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, when using insulating fine particles containing a phosphonium group having an alkyl chain having a specific number of carbon atoms as an insulating material, the conductive particles On the other hand, they have found that oxidation of a metal film can be effectively prevented while obtaining the same adhesiveness as conventional insulating fine particles containing a triethylphosphonium group, and completed the present invention.

That is, the present invention includes conductive metal-coated particles having a metal film formed on the surface of a core material, and an insulating layer made of a polymer covering the metal-coated particles, wherein the insulating layer has the following formula (1) And a coated particle having a phosphonium group represented by the formula:
(Wherein, R is each independently an alkyl group having 4 to 10 carbon atoms).

The coated particles of the present invention are those in which oxidation of the metal film is prevented, and a decrease in conductivity over time is suppressed. Further, when the insulating layer is insulating fine particles or a continuous film obtained by melting or dissolving the same, the surface of the conductive metal-coated particles is easily covered with the insulating layer densely, and has stable insulating properties.
Such coated particles of the present invention have high connection reliability.

FIG. 1 is a photograph of the coated particles obtained in Example 4 observed by SEM. FIG. 2 is a photograph of the coated particles obtained in Example 7 observed by SEM. FIG. 3 is a photograph of the coated particles obtained in Example 8 observed by SEM.

Hereinafter, the present invention will be described based on preferred embodiments.
The coated particles of the present embodiment include conductive metal-coated particles having a metal film formed on the surface of a core material, and an insulating layer made of a polymer that coats the metal-coated particles. It has a phosphonium group represented by 1).

As the conductive metal-coated particles (hereinafter also referred to as “conductive particles”), known particles 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 used without any limitation, whether inorganic or organic. Examples of the inorganic core material particles include metal particles such as gold, silver, copper, nickel, palladium, and solder, alloys, glass, ceramics, silica, metal or nonmetal oxides (including hydrates), and aluminosilicates. Metal silicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal salts, metal halides, and carbon. On the other hand, organic core material particles include, for example, thermoplastics such as natural fibers, natural resins, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylate, polyacrylonitrile, polyacetal, ionomer, and polyester. Resins, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, diallyl phthalate resins, and the like. These may be used alone or in combination of two or more. Among these, core particles made of a resin material are preferred in that they have a lower specific gravity than the metal core particles and are less likely to settle down, have excellent dispersion stability, and easily maintain electrical connection due to the elasticity of the resin. .

  When an organic material is used as the core particles, the organic particles do not have a glass transition temperature, or the glass transition temperature is higher than 100 ° C., so that the shape of the core particles can be easily maintained in the anisotropic conductive connection step, or the metal can be used. This is preferable because the shape of the core material particles can be easily maintained in the step of forming the film. When the core material particles have a glass transition temperature, the glass transition temperature is 200 ° C. or lower, which makes it easy for the conductive particles to soften in the anisotropic conductive connection and to increase the contact area to facilitate conduction. Is preferred. In this respect, when the core material particles have a glass transition temperature, the glass transition temperature is more preferably higher than 100 ° C and 180 ° C or lower, and particularly preferably higher than 100 ° C and 160 ° C or lower. The glass transition temperature can be measured by the method described in Examples described later.

  When an organic substance is used as the core material particles and the organic substance is a highly crosslinked resin, the glass transition temperature is hardly observed even when the glass transition temperature is measured 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, and in the present invention, such core material particles may be used. The above-mentioned core particle material having no glass transition temperature can be obtained by copolymerizing a monomer constituting the organic substance exemplified above with a crosslinkable monomer. Examples of the crosslinking monomer include tetramethylene di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide di (meth) acrylate, and tetraethylene oxide. (Meth) acrylate, 1,6-hexanedi (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanedi ( (Meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, tetramethylolpropanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycero Polyfunctional (meth) acrylates such as rudi (meth) acrylate and glycerol tridi (meth) acrylate, polyfunctional vinyl monomers such as divinylbenzene and divinyltoluene, vinyltrimethoxysilane, trimethoxysilylstyrene, γ- (meth) ) Silane-containing monomers such as acryloxypropyltrimethoxysilane, and monomers such as triallyl isocyanurate, diallyl phthalate, diallyl acrylamide, and diallyl ether. Particularly in the field of COG (Chip on Glass), it is crosslinked with the above polyfunctional (meth) acrylate, the above polyfunctional vinyl monomer, the above silane containing monomer, triallyl isocyanurate, diallyl phthalate, diallyl acrylamide or diallyl ether. Core particles made of hard organic materials are often used.

There is no particular limitation on the shape of the core material particles. Generally, the core material particles are spherical. However, the core material particles may have a shape other than a spherical shape, for example, a fibrous shape, a hollow shape, a plate shape, or a needle shape, and may have a large number of projections on the surface thereof or an irregular shape. In the present invention, spherical core material particles are preferable in that they have excellent filling properties and are easily coated with metal.
The shape of the conductive particles depends on the shape of the core material particles, but is not particularly limited. For example, it may be fibrous, hollow, plate-like or needle-like, and may have protrusions on its surface or irregular shape. In the present invention, a spherical shape or a shape having projections 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, the conductive particles preferably have a plurality of protrusions on the surface, and more preferably have a plurality of protrusions on the spherical surface. When the conductive particles have a shape having a plurality of protrusions, the core material particles may have a plurality of protrusions, or the core material particles have no protrusions, and the metal film has a plurality of protrusions. It may be. Preferably, the core material particles do not have protrusions, and the metal film has a plurality of protrusions. By having the projections on the surface of the conductive particles, when the conductive particles are compressed by the electrodes during mounting, the insulating layer can be effectively pushed away by the projections. As for the height H of the projections of the conductive particles, when the thickness of the insulating layer is L, it is necessary that H / L is 0.1 or more. It is preferable from the viewpoint of achieving Further, it is preferable that H / L is 10 or less from the viewpoint of obtaining the filling property and the insulating property in a direction different from that of the counter electrode. From these points, it is still more preferable that H / L is 0.2 or more and 5 or less. In these preferred ranges, the thickness L indicates the average particle diameter of the insulating fine particles when the insulating layer is the insulating fine particles.

  The height H of the projection is preferably 20 nm or more on average, particularly preferably 50 nm or more. Although the number of projections depends on the particle size of the conductive particles, it is preferably from 1 to 20,000, particularly from 5 to 5,000 per particle, from the viewpoint of further improving the conductivity of the conductive particles. . The aspect ratio of the projection is preferably 0.3 or more, more preferably 0.5 or more. The large aspect ratio of the projection is advantageous because the oxide film formed on the electrode surface can be easily pierced. The aspect ratio is a value defined by the ratio of the height H of the projection to the length D of the base of the projection, that is, H / D. The height H of the protrusion and the length D of the base of the protrusion are average values measured for 20 different particles observed by an electron microscope, and the aspect ratio of the protrusion is 20 different particles observed by an electron microscope. The aspect ratio of the particles was calculated, and the average value was calculated. The base length D refers to the length of the base of the protrusion along the surface of the conductive particles in the electron microscope image.

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

  The metal film in the conductive particles has conductivity, and as the constituent metal, 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, and molybdenum or alloys thereof, metal compounds such as ITO and solder are exemplified. Among them, gold, silver, copper, nickel, palladium or solder is preferable because of low resistance, and particularly, nickel, gold, nickel alloy or gold alloy is suitably used because of high binding property with phosphonium group in insulating fine particles. . Nickel, nickel alloys, iron, zinc, tin, lead, cobalt, titanium, and aluminum are preferable in that the antioxidant effect of the present invention is easily obtained. From these points, nickel or a nickel alloy is most preferable. The metal in the conductive particles can be used alone or in combination of two or more.

  The metal film may have a single-layer structure or a multilayer structure including a plurality of layers. In the case of a multilayer structure composed of a plurality of layers, the outermost layer is preferably made of nickel, gold, a nickel alloy or a gold alloy because of its high bonding property with a phosphonium group in the insulating fine particles. , Iron, zinc, tin, lead, cobalt, titanium, and aluminum are preferred in that the antioxidant effect of the present invention is easily obtained. From these points, nickel or a nickel alloy is most preferable.

  The outer surface of the metal film may be surface-treated to prevent corrosion and oxidation of the metal film. This surface treatment can be performed by using a known surface treatment agent. Examples of the surface treatment agent include a phosphoric acid compound, a chromic acid compound, a triazole compound, an imidazole compound, and a thiazole compound.

  Further, the metal coating may cover the entire surface of the core material particles, or may cover only a part thereof. When only a part of the surface of the core material particles is covered, the covering portion may be continuous, for example, may be discontinuously covered in an island shape. The thickness of the metal film is preferably from 0.001 μm to 2 μm.

  As a method of forming a metal film on the surface of the core material particles, a wet method using a vapor deposition method, a sputtering method, a mechanochemical method, a dry method using a hybridization method, an electrolytic plating method, an electroless plating method, or the like is used. No. Further, these methods may be combined to form a metal film on the surface of the core material particles.

The average particle size 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, the obtained coated particles can easily secure conduction between the opposed electrodes without causing a short circuit in a direction different from that between the opposed electrodes. In the present invention, the average particle size of the conductive particles is an average value of the particle sizes measured using a scanning electron microscope (SEM). In the case where the conductive particles are spherical in the scanning electron microscope image, the particle diameter measured by using the SEM is the diameter of a circular conductive particle image. When the conductive particles are not spherical, the particle diameter measured using the SEM refers to the largest length (maximum length) among the line segments that traverse the image of the conductive particles. This is the same for the average particle diameter of the insulating fine particles described later. However, when the conductive particles have projections, the above-described maximum length of a portion other than the projections is defined as an average particle diameter.
Specifically, the average particle size of the conductive particles is measured by the method described in Examples.

  The insulating layer covering the conductive particles has a trialkylphosphonium group composed of an alkyl group having 4 to 10 carbon atoms as represented by the formula (1). A trialkylphosphonium group composed of an alkyl group having 4 to 10 carbon atoms has a higher hydrophobicity than a triethylphosphonium group. The present inventors speculate that this may be one of the reasons why the metal film of the conductive particles is less likely to be oxidized in the present invention than in the case of the conventional coated particles in which the insulating layer has a triethylphosphonium group.

The insulating layer in the present invention includes a plurality of insulating fine particles containing a compound having a phosphonium group arranged in layers, or an insulating continuous film containing a compound having a phosphonium group.
First, a case where the insulating layer is made of insulating fine particles and the fine particles include a compound having a phosphonium group will be described. In this case, the insulating particles are melted, deformed, peeled or moved on the conductive particle surface by thermocompression bonding the coated particles between the electrodes, thereby exposing the metal surface of the conductive particles in the thermocompression-bonded portion. Thereby, electrical connection between the electrodes is made possible and connectivity is obtained. On the other hand, the surface of the coated particles facing in a direction other than the thermocompression bonding direction is substantially maintained in a state where the conductive particles are covered with the insulating fine particles, so that conduction in directions other than the thermocompression bonding direction is prevented.

  The insulating fine particles preferably have a phosphonium group represented by the formula (1) on the surface thereof. In the present specification, if the insulating fine particles have a phosphonium group represented by the formula (1) and can be confirmed by scanning electron microscope observation that the insulating fine particles have adhered to the surface of the conductive particles, it means that “insulating fine particles” The conductive fine particles have a phosphonium group represented by the formula (1) on the surface. "

  The shape of the insulating fine particles is not particularly limited, and may be spherical or a shape other than spherical. Examples of the shape other than the spherical shape include a fiber shape, a hollow shape, a plate shape, and a needle shape. Further, the insulating fine particles may have a large number of protrusions on the surface thereof or may have an irregular shape. Spherical insulating fine particles are preferred from the viewpoint of adhesion to the conductive particles and ease of synthesis.

  The phosphonium group represented by the formula (1) in the insulating fine particles 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 phosphonium group is preferably contained in at least one kind of structure of the constituent unit of the polymer constituting the insulating fine particles. The phosphonium group represented by the formula (1) is preferably chemically bonded to a polymer constituting the insulating fine particles, and is more preferably bonded to a side chain of the polymer.

  Examples of the alkyl group represented by R include linear, branched, and cyclic groups. Examples of the linear one include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

  Examples of the branched alkyl group represented by R include an isobutyl group, an s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 3-pentyl group, an s-pentyl group, a t-pentyl group, and an isohexyl group. , S-hexyl group, t-hexyl group, ethylhexyl group and the like.

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

R is preferably a straight-chain alkyl group from the viewpoint that the insulating fine particles come close to and easily adhere to the conductive particles.
Further, from the viewpoint of densely filling the insulating fine particles of the conductive particles and the hydrophobicity of the insulating fine particles, the alkyl group represented by R has 4 to 10 carbon atoms, More preferably, it has 4 to 8 carbon atoms.

  The polymer constituting the insulating fine particles is preferably a polymer of a plurality of polymerizable compounds having an ethylenically unsaturated bond, and at least one of the polymerizable compounds having an ethylenically unsaturated bond for constituting the polymer. One kind preferably has a phosphonium group represented by the formula (1).

  Examples of the polymerizable compound having an ethylenically unsaturated bond having a phosphonium group represented by the formula (1) include styrenes, olefins, esters, α, β unsaturated carboxylic acids, amides, and nitriles. Can be Examples of the styrenes include styrene, o, m, p-methylstyrene, dimethylstyrene, ethylstyrene, chlorostyrene and other nuclear-substituted styrenes, and styrene derivatives such as α-methylstyrene, α-chlorostyrene and β-chlorostyrene. No. Examples of the olefin include ethylene and propylene. Examples of the esters include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate, and methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and phenyl (meth) acrylate. (Meth) acrylic acid esters and the like. Examples of the α, β unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, and maleic acid. Salts of these α, β unsaturated carboxylic acids are also included in the α, β unsaturated carboxylic acids. Examples of the amide include acrylamide and methacrylamide. Examples of the nitriles include acrylonitrile. These may be further substituted, and examples of the substituent include a phosphonium group, an amino group, a quaternary ammonium group, an amide group, a sulfonium group, a sulfonic acid group, a thiol group, a carboxyl group, a phosphate group, a cyano group, Examples 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 polymerizable compound having an ethylenically unsaturated bond having a phosphonium group represented by the formula (1), styrenes or esters are particularly preferable.
The polymer constituting the insulating fine particles has a structural unit represented by the following formula (2) or (3) as a phosphonium group represented by the above formula (1). It is preferable from the viewpoint of ease. Examples of R in the formulas (2) and (3) are as described above as examples of R in the formula (1). The phosphonium group may be bonded to any of the para, ortho and meta positions with respect to the CH group of the benzene ring of the formula (2), and is preferably bonded to the para position. In the formulas (2) and (3), the monovalent An ⁻ is preferably a halide ion. Examples of halide ions include Cl ⁻ , F ⁻ , Br ⁻ , and I ⁻ .

(In the formula, R independently represents an alkyl group having 4 to 10 carbon atoms. An ⁻ represents a monovalent anion. M represents an integer of 0 to 5.)

(Wherein, R independently represents an alkyl group having 4 to 10 carbon atoms; An ⁻ represents a monovalent anion; n is a number of 1 to _5; R ₅ is a hydrogen atom or methyl). )

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

Examples of the polymerizable compound having an ethylenically unsaturated bond that provides the compound represented by the above formula (2) include:
4- (vinylbenzyl) tributylphosphonium chloride,
4- (vinylbenzyl) tripentylphosphonium chloride,
4- (vinylbenzyl) trihexylphosphonium chloride,
4- (vinylbenzyl) triheptylphosphonium chloride,
4- (vinylbenzyl) trioctylphosphonium chloride,
4- (vinylbenzyl) trinonylphosphonium chloride,
4- (vinylbenzyl) tridecylphosphonium chloride.

Examples of the polymerizable compound having an ethylenically unsaturated bond that gives the compound represented by the above formula (3) include:
2- (methacryloyloxyethyl) tributylphosphonium chloride,
2- (methacryloyloxyethyl) tripentylphosphonium chloride,
2- (methacryloyloxyethyl) trihexylphosphonium chloride,
2- (methacryloyloxyethyl) triheptylphosphonium chloride,
2- (methacryloyloxyethyl) trioctylphosphonium chloride,
2- (methacryloyloxyethyl) trinonylphosphonium chloride,
2- (methacryloyloxyethyl) tridecylphosphonium chloride,
And the like.

  In the polymer constituting the insulating fine particles, the proportion of the constituent unit to which the phosphonium group represented by the formula (1) is bonded in all the constituent units is preferably 0.01 mol% or more and 5.0 mol% or less. , 0.02 mol% or more and 2.0 mol% or less. Here, the number of structural units in the polymer is such that a structure derived from one monomer is counted as one structural unit.

  As described above, the polymer constituting the insulating fine particles is preferably a polymer obtained by combining a plurality of polymerizable compounds having an ethylenically unsaturated bond. Among the polymerizable compounds having an ethylenically unsaturated bond for constituting the insulating fine particles, the polymerizable compounds having no phosphonium group represented by the formula (1) include the above-mentioned styrenes, olefins, and the like. Examples include esters, α, β unsaturated carboxylic acids, amides, and nitriles. Examples of styrenes, olefins, esters, α, β unsaturated carboxylic acids, amides, and nitriles include those described above. The polymer constituting the insulating fine particles is preferably at least one polymer selected from styrenes, esters, and nitriles, in particular, in that the polymerization rate is high and the insulating fine particles can be easily made spherical. Is preferred. When the polymer constituting the insulating fine particles has a plurality of types of structural units, the mode of existence of those structural units in the polymer may be random, alternate, or block.

The polymer constituting the insulating fine particles may be cross-linked or non-cross-linked.However, the cross-linking expands the particle distribution of the insulating fine particles to improve the close filling property to the conductive particles. It is preferable because it is easy to obtain.
When the polymer constituting the insulating fine particles is crosslinked, two or more ethylenically unsaturated bonding groups may be added to the composition of the polymerizable compound having an ethylenically unsaturated bond for obtaining the polymer forming the insulating fine particles. May be added. Examples of the crosslinking agent include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol divinyl. (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, neo Pentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane trimethacrylate, glycerin dimethacrylate, dimethylol-tricyclodeca Diacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, neopentyl glycol acrylate benzoate, trimethylolpropane acrylate benzoate, 2-hydroxy-3-acryloyloxypropyl Examples thereof include di (meth) acrylate compounds such as methacrylate, neopentyl glycol diacrylate hydroxypivalate, ditrimethylolpropane tetraacrylate, and 2-butyl-2-ethyl-1,3-propanediol diacrylate.

  In the polymer constituting the insulating fine particles, the proportion of the structural unit derived from the crosslinking agent in all the structural units is preferably from 1 mol% to 15 mol%, more preferably from 2 mol% to 13 mol%. Is more preferred. Here, the number of structural units in the polymer is such that a structure derived from one monomer is counted as one structural unit.

  The polymer constituting the insulating fine particles is a copolymer having two or more kinds of constituent units, and it is preferable that at least one of the constituent units has an ester bond in the structure. Thereby, the glass transition temperature of the polymer can be appropriately reduced, and the ratio of the area of the insulating fine particles in contact with the conductive particles can be increased to increase the adhesion between the insulating fine particles and the conductive particles. The degree of bonding between the insulating fine particles can be increased, and the insulating property between the coated particles can be further improved.

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

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

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

The glass transition temperature of the insulating fine particles is preferably lower than the glass transition temperature of the core material of the conductive particles. With this configuration, the ratio of the area of the insulating fine particles in contact with the conductive particles and the adhesion between the insulating fine particles can be easily increased.
In particular, in the present embodiment, by using the insulating fine particles having a phosphonium group on the surface, as described above, the insulating fine particles can be adhered to the conductive particles in a single layer. By using a material having a low transition temperature, the adhesion of the insulating fine particles to the conductive particles and the adhesion between the insulating fine particles can be more easily increased. Therefore, in the present embodiment, the insulation between the coated particles can be effectively improved.

More specifically, the glass transition temperature of the insulating fine particles is preferably 100 ° C. or lower, more preferably 95 ° C. or lower, and particularly preferably 90 ° C. or lower.
Further, the glass transition temperature of the insulating fine particles is preferably 40 ° C. or more from the viewpoint of shape stability at the time of storage of the coated particles and the easiness of synthesizing the insulating fine particles, and more preferably 45 ° C. or more. It is particularly preferred that the temperature be 50 ° C. or higher. The glass transition temperature can be measured by the method described in Examples described later.

  When the core material has a glass transition temperature from the same point as described above, 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 is 120 ° C. The temperature is more preferably at most 100 ° C. The difference between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core material of the conductive particles is preferably 5 ° C. or more, more preferably 10 ° C. or more.

The method for measuring the glass transition temperature includes, for example, the following method.
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 rate of 5 ° C./min. . Next, the sample was heated at a heating rate of 5 ° C./min, and the calorific value was measured. When a peak is observed, the temperature of the peak, when a step is observed without observing the peak, a tangent indicating the maximum slope of the curve of the step portion and an extension of the baseline on the high temperature side of the step. The temperature at the intersection of was taken as the glass transition temperature.

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

The particle size distribution of the insulating fine particles measured by the above method has a range. Generally, the width of the particle size distribution of the powder is represented by a coefficient of variation (hereinafter, also referred to as “CV”) represented by the following equation (1).
C. V. (%) = (Standard deviation / average particle diameter) × 100 (1)
This C. V. Is large, indicating that the particle size distribution has a certain range, while C.I. V. Is small indicates that the particle size distribution is sharp. The coated particles of the present embodiment are C.I. V. Is preferably 5% or more, more preferably 7% or more, and most preferably more than 10%. C. V. Is not less than the lower limit, it is easy to make the covering of the surface of the conductive particles with the insulating fine particles more dense. Also, C.I. V. The value is preferably 20% or less, and more preferably 15% or less, from the viewpoint of making the thickness of the coating layer made of insulating fine particles uniform.

  The insulating layer may be a continuous film containing a compound having a phosphonium group and made of a polymer, instead of the above-mentioned one made of insulating fine particles. The term “continuous” of a continuous film means that the conductive particles are coated more continuously than the insulating fine particles, and a form in which one conductive particle is necessarily covered with only one continuous film is used. Instead, one conductive particle may be intermittently covered with a plurality of films. When the insulating layer is a continuous film containing a compound having a phosphonium group, the metal film of the conductive particles is exposed by melting, deforming or peeling the continuous film by thermocompression bonding the coated particles between electrodes. Thus, conduction between the electrodes is enabled, and connectivity is obtained. In particular, a metal surface is often exposed by breaking a continuous film by thermocompression bonding of coated particles between electrodes. On the other hand, in the surface portion of the coated particles facing in a direction different from the thermocompression bonding direction, the conductive film is substantially covered with the continuous film, so that conduction in directions other than the thermocompression bonding direction is prevented. The insulating film also preferably has a phosphonium group on the surface.

Even if the insulating layer is formed of a continuous film, the presence of the phosphonium group represented by the formula (1) makes it easy to prevent oxidation of the metal film. When the continuous film is formed by heating insulating fine particles coated with conductive particles, or when insulating fine particles coated with conductive particles are dissolved in an organic solvent, a precursor of the insulating layer is used. Since the insulating fine particles can be densely coated, a continuous film obtained by melting or dissolving the insulating fine particles can densely cover the surface of the conductive particles and obtain stable insulating properties.
When the insulating layer is a continuous film containing a compound having a phosphonium group, the film may cover the entire surface of the conductive particles or may cover a part of the surface. In addition, the surface of the continuous film may be flat, or a part or all of the surface may have irregularities derived from melting or dissolving the insulating fine particles. The insulating layer may be in a state where the continuous film and the insulating fine particles are mixed.

  The thickness of the continuous film is preferably 10 nm or more from the viewpoint of improving the insulating property in a direction different from that between the counter electrodes, and 3,000 nm or less is preferable for the continuity between the counter electrodes. It is preferred in that respect. From this point, the thickness of the continuous film is preferably from 10 nm to 3,000 nm, and more preferably from 15 nm to 2,000 nm.

Like the insulating fine particles, the phosphonium group represented by the formula (1) 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 phosphonium group represented by the formula (1) is preferably contained in at least one kind of structure of a structural unit of a polymer constituting the continuous film. The phosphonium group represented by the formula (1) is preferably chemically bonded to a polymer constituting the continuous film, and more preferably is bonded to a side chain of the polymer.
Examples of the phosphonium group represented by the formula (1) included in the continuous film include those similar to the phosphonium group represented by the formula (1) included in the insulating fine particles.
Examples of the constituent units of the polymer constituting the continuous film and the composition thereof include the same units as those described above as examples of the constituent units of the polymer constituting the insulating fine particles described above and the composition thereof. The preferred ratio ranges of the constituent units all apply to the continuous film. As the glass transition temperature of the continuous film, the same as the glass transition temperature of the insulating fine particles described above can be used. The relationship between the glass transition temperature of the continuous film and the glass transition temperature of the core particles includes the same relationship as the above-described relationship between the glass transition temperature of the insulating fine particles and the glass transition temperature of the core particles.

Next, a preferred method for producing the coated particles of the present embodiment will be described.
This production method comprises a first step of polymerizing a polymerizable composition containing a polymerizable compound having a phosphonium group represented by the formula (1) to obtain insulating fine particles having a phosphonium group on the surface,
A second step of mixing the insulating fine particles and the conductive particles to adhere the insulating fine particles to the surface of the conductive particles.

(First step)
The polymerizable composition is composed of two or more types of polymerizable compounds, and includes at least one type having a phosphonium group. Examples of the polymerizable compound include a polymerizable compound having an ethylenically unsaturated bond, which is a constituent unit of the polymer constituting the insulating fine particles described above. Examples of the preferable polymerizable compound and the composition ratio thereof include those which give the above-mentioned preferable constituent units of the polymer constituting the insulating fine particles and the preferable quantitative 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. In the case of soap-free emulsion polymerization, monodisperse fine particles are used with a surfactant. It is preferable because there is an advantage that it can be manufactured without using. In the case of soap-free emulsion polymerization, a water-soluble initiator is used as a polymerization initiator. The polymerization is preferably performed under an inert atmosphere such as nitrogen or argon.
Thus, insulating fine particles having a phosphonium group represented by the formula (1) on the surface are obtained.

(2nd process)
Next, the insulating fine particles are mixed with the conductive particles to adhere the insulating fine particles to the surface of the conductive particles. The mixing of the insulating fine particles and the conductive particles is preferably performed in a liquid medium. Examples of the liquid medium include water, an organic solvent, and a mixture thereof, with water being preferred. As the organic solvent, as described below, alcohols such as methanol, ethanol, 1-propanol and 2-propanol can be used as those which do not dissolve the insulating fine particles.
When using a conductive particle having a surface treatment agent on the outer surface thereof, for example, before mixing with insulating fine particles, if surface treatment such as dispersing the conductive particles in a solution of the surface treatment agent is performed. Good.

When mixing the insulating fine particles and the conductive particles in a liquid medium, the dispersion liquid composed of these particles and the liquid medium may contain an inorganic salt, an organic salt or an organic acid, and the coated particles having a coating ratio of a certain level or more. It is preferable because it is easy to obtain. As the inorganic salt, the organic salt or the organic acid, those which dissociate anions are suitably used. As the anions, Cl ⁻ , F ⁻ , Br ⁻ , I ⁻ , SO ₄ ²⁻ , and CO ₃ ^2−. , NO ₃ ⁻ , COO ⁻ , RCOO ⁻ (R is an organic group) and the like. As the inorganic salt, for example _{NaCl, KCl, LiCl, MgCl 2} , BaCl 2, NaF, KF, LiF, MgF 2, BaF 2, NaBr, KBr, LiBr, MgBr 2, BaBr 2, NaI, KI, LiI, MgI 2 _{, BaI 2, Na 2 SO 4} , K 2 SO 4, Li 2 SO 4, 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 and the} like can be used. Further, as the organic salt, Na succinate, Na oxalate, Na acetate, Na citrate, Na malonate, Na tartrate, Na fumarate, Na maleate and the like can be used. As the organic acid, amino acids such as glycine, succinic acid, oxalic acid, acetic acid, citric acid, tartaric acid, malonic acid, fumaric acid, maleic acid and the like can be used.

  The preferred concentration of the inorganic salt, the organic salt and the organic acid is different depending on how much the covering area occupied by the insulating fine particles in the surface area of the conductive particles, but in the dispersion containing the insulating fine particles and the conductive particles, for example, A concentration of 1 mmol / L or more and 100 mmol / L or less is preferable because it has a suitable coverage and easily obtains coated particles in which the insulating fine particles are a single layer. From this viewpoint, the concentration of the inorganic salt, organic salt, and organic acid in the dispersion is more preferably 2 mmol / L or more and 90 mmol / L or less, particularly preferably 3 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 containing the insulating fine particles and the conductive particles may be mixed, and the dispersion containing the conductive particles and the insulating fine particles may be mixed. Alternatively, insulating fine particles and conductive particles may be respectively added to the liquid medium, and a dispersion medium containing insulating fine particles and a dispersion medium containing conductive particles may be mixed. The dispersion containing the conductive particles and the insulating fine particles preferably contains the conductive particles in an amount of 100 ppm to 100,000 ppm, more preferably 500 ppm to 80,000 ppm by mass. .
In the dispersion containing the conductive particles and the insulating fine particles, the insulating fine particles are preferably contained in an amount of 10 ppm or more and 50,000 ppm or less, more preferably 250 ppm or more and 30,000 ppm or less based on mass. .

  In general, the temperature of the dispersion liquid containing the conductive particles and the insulating fine particles is preferably from 15 ° C to 100 ° C, from the viewpoint of easily obtaining coated particles having a constant quality, and is preferably from 20 ° C to 90 ° C. Is particularly preferred. In particular, when the glass transition temperature of the insulating fine particles is Tg ° C., the temperature of the dispersion is preferably Tg−60 ° C. or more and Tg + 30 ° C. or less, and more preferably Tg−50 ° C. or more and Tg + 15 ° C. or less. . This range is preferred because the insulating fine particles adhere to the conductive particles while maintaining their shape, and a suitable contact area between the insulating fine particles and the conductive particles can be easily obtained. However, the insulating fine particles having a phosphonium group represented by the formula (1) of the present invention have a high affinity for the conductive particles, and thus can be sufficiently coated within the above-mentioned temperature range. .

  In the dispersion liquid after mixing the conductive particles, the time for the insulating fine particles to adhere to the conductive particles is preferably 0.1 hours or more and 24 hours or less. During this time, it is preferable to stir the dispersion. Next, the solid content of the dispersion is washed and dried, if necessary, to obtain coated particles having insulating fine particles having a phosphonium group adhered to the surface of the conductive particles.

  As described above, by heating the coated particles having the insulating fine particles adhered to the surface of the conductive particles, the insulating fine particles can be melted and the surface of the conductive particles can be coated in a film-like manner. 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 liquid 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, and a method of heating the coated particles with an inert gas. For example, a method of heating in a gas phase may be used. The heating temperature is Tg + 1 ° C. or higher and Tg + 60 ° C. when the glass transition temperature of the polymer constituting the insulating fine particles is Tg, since a uniform film shape is easily formed without the insulating fine particles falling off. Or less, more preferably Tg + 5 ° C. or more and Tg + 50 ° C. or less, and most preferably Tg + 10 ° C. or more. When the coated particles are heated in the gas phase, the heating can be performed under atmospheric pressure, reduced pressure, or increased pressure.

  In addition, the coated particles having the insulating fine particles adhered to the surface of the conductive particles can be made to be in a fluid state by adding an organic solvent to the dispersion, so that the surface of the conductive particles can be formed into a film. Can be coated. When dissolving 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 the organic solvent to be added is 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, since the insulating fine particles are easily formed into a uniform film without falling off. Is preferably 5 parts by mass or more and 50 parts by mass or less. The addition temperature is preferably from 10 ° C. to 100 ° C., more preferably from 20 ° C. to 80 ° C., from the viewpoint that a uniform film is easily formed without the insulating fine particles falling off.

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

  The preferred production method has been described above, but the coated particles of the present invention can be produced by other production methods. For example, the insulating fine particles having no phosphonium group may be prepared in advance by a polymerization reaction, and the resulting insulating fine particles may be reacted with a compound having a phosphonium group to introduce a phosphonium group on the surface of the insulating fine particles. .

  The coated particles obtained as described above take advantage of the insulating property between the coated particles and the connectivity between the counter electrodes due to the advantage of combining the conductive particles with the insulating fine particles having a phosphonium group or the continuous film. And a conductive material such as a conductive adhesive, an anisotropic conductive film, and an anisotropic conductive adhesive.

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

(1) Average particle diameter 200 particles are arbitrarily extracted from a scanning electron microscope (SEM) photograph (magnification: 100,000 times) of a measurement object, their particle diameters are measured, and the average value is averaged. The particle size was used. The definition of the average particle size is as described above.

(2) C.I. V. (Coefficient of variation)
The average particle diameter was determined by the following equation.
C. V. (%) = (Standard deviation / average particle diameter) × 100

(3) Glass transition temperature Using a differential scanning calorimeter (available from METTLER TOLEDO, STAR SYSTEM), the rate of temperature rise and fall is 5 ° C./min. It was measured.

(Example 1)
[Production of tributylphosphonium-based insulating fine particles]
100 mL of pure water was charged 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., Ltd.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), 4- (vinylbenzyl) tributylphosphonium chloride (Nippon Chemical Industry Co., Ltd.) 0.30 mmol, 1.50 mmol of divinylbenzene (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) as a crosslinking agent and 2,2′-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator , V-50) 0.50 mmol. After venting nitrogen for 15 minutes to drive out dissolved oxygen, the temperature was raised to 60 ° C. and maintained for 6 hours to advance the polymerization reaction. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having an aperture of 150 μm to remove aggregates. The dispersion from which the aggregates were removed was centrifuged at 20,000 rpm for 20 minutes in a centrifuge (CR-21N, manufactured by Hitachi Koki Co., Ltd.) to precipitate fine particles. Removed. Pure water was added to the obtained solid to wash it, and spherical fine particles of tributylphosphonium-based insulating fine particles made of a crosslinked resin were obtained. The average particle diameter of the obtained fine particles was 139 nm, and C.I. V. Was 8.6%. The glass transition temperature was about 81 ° C.

[Production of conductive particles coated with insulating fine particles]
Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Example 2)
[Production of tributylphosphonium-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]
Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and NaCl were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and NaCl, the solid content of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of NaCl was 10 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Example 3)
[Production of tributylphosphonium-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]
Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and succinic acid were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and the succinic acid, the solid content of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of the succinic acid was 10 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Example 4)
[Production of tributylphosphonium-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]
Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. 10 mL of a 1% by mass aqueous solution of benzotriazole was charged into this dispersion and stirred for 5 minutes to perform surface treatment. Thereafter, the mixture was filtered through a membrane filter having a mesh size of 2.0 μm to collect Ni-plated particles having a benzotriazole layer on the surface. After washing the collected Ni-plated particles with pure water, 100 mL of pure water was added to obtain a dispersion of Ni-plated particles having a benzotriazole layer on the surface. The insulating fine particles obtained above and Na ₂ SO ₄ were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results. FIG. 1 shows an SEM photograph of the obtained coated particles.

(Example 5)
[Production of tributylphosphonium-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 surface of the spherical resin particles has 1,030 protrusions having an average height of 0.1 μm, an average base length of 0.197 μm, an aspect ratio of 0.5, and a thickness of 0.10 μm. Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having a nickel film of 125 μm 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. Further, 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 charged into this dispersion and stirred for 5 minutes to perform surface treatment. Thereafter, the mixture was filtered through a membrane filter having a mesh size of 2.0 μm to collect Ni-plated particles having a benzotriazole layer on the surface. After washing the collected Ni-plated particles with pure water, 100 mL of pure water was added to obtain a dispersion of Ni-plated particles having a benzotriazole layer on the surface. The insulating fine particles obtained above and Na ₂ SO ₄ were added to this dispersion, and the mixture was stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Example 6)
[Production of trioctylphosphonium-based insulating fine particles]
100 mL of pure water was charged 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., Ltd.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), and 4- (vinylbenzyl) trioctylphosphonium chloride (Nippon Chemical Industry Co., Ltd.) 0.30 mmol), 1.5 mmol of divinylbenzene (manufactured by Nippon Steel & Sumikin Chemical) as a crosslinking agent, and 2,2′-azobis (2-methylpropionamidine) dihydrochloride (Wako Pure Chemical Industries, Ltd.) as a polymerization initiator 0.50 mmol). After venting nitrogen for 15 minutes to drive out dissolved oxygen, the temperature was raised to 60 ° C. and maintained for 6 hours to advance the polymerization reaction. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having an aperture of 150 μm to remove aggregates. The dispersion from which the aggregates were removed was centrifuged at 20,000 rpm for 20 minutes in a centrifuge (CR-21N, manufactured by Hitachi Koki Co., Ltd.) to precipitate fine particles. Removed. Pure water was added to the obtained solid to wash it, and spherical fine particles of trioctylphosphonium-based insulating fine particles made of a crosslinked resin were obtained. The average particle diameter of the obtained fine particles was 152 nm, and C.I. V. Was 10.6%. The glass transition temperature was about 82 ° C.
[Production of conductive particles coated with insulating fine particles]
Conductive particles coated with insulating fine particles were obtained in the same manner as in Example 1 except that the insulating fine particles obtained above were used. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Example 7)
1.0 g of the conductive particles coated with the insulating fine particles obtained in Example 1 was charged into 20 mL of pure water, and stirred at 95 ° C. for 6 hours. After completion of the stirring, the solid matter was separated by a membrane filter having an opening of 2 μm, and then dried to obtain conductive particles coated with an insulating continuous film in which the entire surface of the conductive particles was coated with a film having a thickness of 125 nm. FIG. 2 shows an SEM photograph of the obtained coated particles.

(Example 8)
1.0 g of the conductive particles coated with the insulating fine particles obtained in Example 1 was charged into 20 mL of pure water to obtain a dispersion. To this dispersion was added 10 mL of tetrahydrofuran, and the mixture was stirred at room temperature for 6 hours. After completion of the stirring, the solid substance was separated by a membrane filter having an opening of 2 μm, washed with water, and dried to obtain a continuous film-coated conductive particle in which the entire surface of the conductive particle was coated with a continuous film having a thickness of 100 nm. Was. FIG. 3 shows an SEM photograph of the obtained coated particles.

(Comparative Example 1)
[Production of triethylphosphonium-based insulating fine particles]
100 mL of pure water was charged 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., Ltd.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), 4- (vinylbenzyl) triethylphosphonium chloride (Nippon Chemical Industry Co., Ltd.) 0.30 mmol, divinylbenzene (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) as a crosslinking agent, 1.5 mmol, and 2,2′-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator. , V-50) 0.50 mmol. After venting nitrogen for 15 minutes to drive out dissolved oxygen, the temperature was raised to 60 ° C. and maintained for 6 hours to advance the polymerization reaction. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having an aperture of 150 μm to remove aggregates. The dispersion from which the aggregates were removed was centrifuged at 20,000 rpm for 20 minutes in a centrifuge (CR-21N, manufactured by Hitachi Koki Co., Ltd.) to precipitate fine particles. Removed. Pure water was added to the obtained solid, which was washed to obtain spherical triethylphosphonium-based insulating fine particles made of a crosslinked resin. The average particle diameter of the obtained fine particles was 143 nm, and C.I. V. Was 10.7%. The glass transition temperature was about 80 ° C.
[Production of conductive particles coated with insulating fine particles]
Conductive particles coated with insulating fine particles were obtained in the same manner as in Example 1 except that the insulating fine particles obtained above were used. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Comparative Example 2)
[Production of triethylphosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Comparative Example 1.
[Production of conductive particles coated with insulating fine particles]
Except for using the insulating fine particles obtained above, conductive particles coated with insulating fine particles were obtained in the same manner as in Example 2. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and NaCl were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and NaCl, the solid content of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of NaCl was 10 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Comparative Example 3)
[Production of triethylphosphonium-based insulating fine particles]
Insulating fine particles were obtained in the same manner as in Comparative Example 1.
[Production of conductive particles coated with insulating fine particles]
Conductive particles coated with insulating fine particles were obtained in the same manner as in Example 3, except that the insulating fine particles obtained above were used. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and succinic acid were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and the succinic acid, the solid content of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of the succinic acid was 10 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Comparative Example 4)
[Production of tridodecyl phosphonium-based insulating fine particles]
100 mL of pure water was charged 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., Ltd.), 5.3 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), and 4- (vinylbenzyl) tridodecylphosphonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.) 0.30 mmol), 1.5 mmol of divinylbenzene (manufactured by Nippon Steel & Sumikin Chemical) as a crosslinking agent, and 2,2′-azobis (2-methylpropionamidine) dihydrochloride (Wako Pure Chemical Industries, Ltd.) as a polymerization initiator 0.50 mmol). After venting nitrogen for 15 minutes to drive out dissolved oxygen, the temperature was raised to 60 ° C. and maintained for 6 hours to advance the polymerization reaction. The dispersion liquid of the fine particles after polymerization was passed through a SUS sieve having an aperture of 150 μm to remove aggregates. The dispersion from which the aggregates were removed was centrifuged at 20,000 rpm for 20 minutes in a centrifuge (CR-21N, manufactured by Hitachi Koki Co., Ltd.) to precipitate fine particles. Removed. Pure water was added to the obtained solid to wash it, and spherical tridodecylphosphonium-based insulating fine particles made of a crosslinked resin were obtained. The average particle diameter of the obtained fine particles was 149 nm, and C.I. V. Was 11.7%. The glass transition temperature was about 78 ° C.
[Production of conductive particles coated with insulating fine particles]
Conductive particles coated with insulating fine particles were obtained in the same manner as in Example 1 except that the insulating fine particles obtained above were used. Specifically, Ni-plated particles (manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of the spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120 ° C. 100 mL of pure water was added to 5.0 g of the Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. The insulating fine particles obtained above and Na ₂ SO ₄ were added to the dispersion and stirred at 40 ° C. for 30 minutes. After the addition of the insulating fine particles and Na ₂ SO ₄ , the solid content concentration of the insulating fine particles in the dispersion was 10,000 ppm by mass, and the concentration of Na ₂ SO ₄ was 5 mmol / L. After removing the supernatant liquid, the resultant was washed with pure water, and dried in vacuum at 50 ° C. to obtain conductive particles coated with insulating fine particles. The coverage of the insulating particles in the obtained coated particles was determined by the following method. Table 1 shows the results.

(Evaluation of coverage)
The coverage of the coated particles obtained in Examples 1 to 6 and Comparative Examples 1 to 4 was determined by the following method.
The number N of the insulating fine particles when the insulating fine particles were arranged on the surface of the Ni-plated particles in the closest packing was calculated by the following formula.
N = 4π (R + r) ² / 2√3r ²
(R: radius (nm) of Ni plating particles, r: radius (nm) of insulating fine particles)
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 equation.
Coverage (%) = (n / N) × 100
The coverage used for the evaluation was an average value of 20 Ni-plated particles.

(Evaluation of nickel coating)
After holding the coated particles at 85 ° C. and 85% RH for 24 hours, about 1.0 g was weighed into a glass petri dish and measured at 120 ° C. for 30 minutes using an infrared moisture meter FD-610 (manufactured by Kett Chemical Laboratories). The water content was measured under the following conditions. The lower the water content, the more easily the oxidation of the nickel film is prevented.

Claims (7)

It has conductive metal-coated particles having a metal film formed on the surface of a core material, and an insulating layer made of a polymer covering the metal-coated particles, wherein the insulating layer is a phosphonium represented by the following formula (1): A coated particle having a group.
(Wherein, R is each independently an alkyl group having 4 to 10 carbon atoms).   The coated particles according to claim 1, wherein the insulating layer is composed of a plurality of insulating fine particles or is a continuous film.   The coated particles according to claim 2, wherein the insulating layer is composed of a plurality of insulating fine particles, or is a continuous film obtained by melting or dissolving the insulating fine particles.   The coated particles according to any one of claims 1 to 3, wherein the polymer is crosslinked.   C. of the insulating fine particles; V. Is 5% or more.   The coated particles according to any one of claims 1 to 5, wherein the insulating layer is made of at least one polymer selected from styrenes, esters, and nitriles. The coated particles according to any one of claims 1 to 6, wherein the metal coating is a coating of nickel or a nickel alloy.