JP2006269296A - Manufacturing method of particle with protrusions, particle with protrusions, conductive particle with protrusions, and anisotropic conductive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of particles with protrusions capable of forming protrusions by binding child particles on a surface of base particles, and particles with protrusions manufactured by using the manufacturing method of particles with protrusions, conductive particle with protrusions, and anisotropic conductive material. <P>SOLUTION: The manufacturing method of particles with protrusions formed by binding child particles on the surface of the base particles comprises a process of strongly binding the child particles on the surface of seed particles, a process of preparing polymerizing liquid drop by swelling the seed particles by polymerizing monomer, and a process of polymerizing the polymerizing liquid drop. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a method for producing a projecting particle capable of firmly binding a child particle to the surface of a base particle, a projecting particle using the method for producing the projecting particle, a conductive projecting particle, and an anisotropic conductive material. .

Protrusion particles having protrusions on at least a part of the surface of the base particle have a function not found in the base particles, and therefore are expected to be developed for various uses. For example, when used as a gap material or conductive particles, an effect of preventing the movement of particles between the substrate and the electrode is expected. In addition, the matte effect due to irregular reflection of the surface protrusions can be made opaque (whitening) without adding pigments and dyes, and thus is expected as display particles and paints for electronic paper.

In addition, aluminum electrodes that have recently been used in electronic circuits have a problem in that an oxide film is easily formed on the surface, and when an attempt is made to connect circuits with conductive particles, conduction is hindered due to the oxide film. . Even in such a case, if conductive protrusion particles having conductive protrusions on the surface are used, the protrusions can break through the oxide film of the circuit and ensure conduction, so that it is considered that connection reliability is improved.

As a method for producing such protruding particles, conventionally, for example, a method in which organic or inorganic child particles are adhered to the surface of the substrate particles by a mechanochemical method (high-speed air flow method) or the like has been performed. However, in this method, it is extremely difficult to control the amount of the child particles attached to the surface of the base material particles, and since the bond between the base particles and the child particles is only a physical binding force, it is extremely difficult. There is a problem that the child particles may be peeled off from the base particles in a single particle forming process or a dispersing process in a medium.

In addition, as a method for producing conductive protrusion particles, for example, in Patent Document 1, when a nickel conductive film is formed on the surface of a substrate particle by electroless plating, the nickel coating and the nickel microparticles that serve as the core of the protrusion are formed. A method is disclosed in which conductive protrusions are formed on the surface of substrate particles by simultaneously depositing particles and forming a nickel coating while taking in nickel fine particles. However, this method has a problem that it is difficult to control the number and size of the protrusions to be obtained because it is very difficult to control the amount and size of the nickel fine particles to be deposited.

JP 2000-243132 A

In view of the above-mentioned present situation, the present invention is capable of firmly binding child particles to the surface of a base particle, and can control the number and size of protrusions. It is an object to provide a conductive protrusion particle and an anisotropic conductive material.

The present invention relates to a method for producing a protruding particle in which a child particle is bonded to the surface of a base particle, the step of attaching the child particle to the surface of the seed particle, the seed particle is swollen with a polymerizable monomer, and polymerization is performed. It is a manufacturing method of the projection particle | grains which has the process of preparing a property droplet, and the process of superposing | polymerizing the said polymerizable droplet.
The present invention is described in detail below.

As a result of intensive studies, the inventors have made a polymerizable droplet in which a child particle is attached to the surface of the seed particle by causing the seed particle to swell with a polymerizable monomer after the child particle is attached to the surface of the seed particle. And then polymerizing the polymerizable droplets, the child particles were found to be firmly fixed on the surface of the base material particles obtained by polymerizing the polymerizable droplets, and the present invention was completed. .
In the present specification, the seed particles mean particles that form polymerizable droplets by absorbing a polymerizable monomer described later.

As a method for producing the protruding particles of the present invention, for example, a step of mixing seed particles and a medium to prepare a dispersion in which the seed particles are dispersed in the medium, adding child particles to the dispersion, The step of adhering the child particles to the surface of the seed particles, mixing the polymerizable monomer into the dispersion liquid in which the seed particles having the child particles attached are dispersed, and absorbing the polymerizable monomer into the seed particles And a method of polymerizing the seed particles that have absorbed the polymerizable monomer are preferred (such a method is hereinafter also referred to as this embodiment).
The production method of the protruding particles of the present invention will be described by describing this embodiment below.

In the method for producing protruding particles according to this embodiment, first, a step of mixing a seed particle and a medium to prepare a dispersion in which the seed particle is dispersed in the medium is performed.
The material constituting the seed particles is not particularly limited as long as it absorbs a polymerizable monomer described later and forms a polymerizable droplet. For example, polyolefin such as polyethylene and polybutadiene; polyethylene glycol, polypropylene Polyethers such as glycol; polystyrene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, polyvinyl alcohol, polyacetal, polyvinyl ester, polyvinyl ether, polyamide, polyethylene terephthalate, polyether ether ketone, phenol resin, allyl resin, Furan resin, polyester, epoxy resin, silicone resin, polyimide resin, melamine resin, benzoguanamine resin, polyurethane, fluororesin, acrylonitrile / styrene resin, styrene / butadiene Fat, ABS resins, vinyl resins, polyamide resins, polycarbonate, polyacetal, polysulfone, polyether sulfone, polyphenylene oxide, sugars, starches, cellulose, condensate mainly containing polypeptide such as, polymers and the like. These may be used alone or in combination of two or more.
The material constituting the seed particles is preferably a non-crosslinked material because it absorbs a polymerizable monomer described later and easily forms a polymerizable droplet.

The seed particle production method is not particularly limited. For example, suspension polymerization method, micro suspension polymerization method, emulsion polymerization method, miniemulsion polymerization method, phase inversion emulsification method, dispersion polymerization method, precipitation polymerization method, soap-free emulsification (Precipitation) Conventionally known polymerization methods such as polymerization methods can be mentioned. Of these, dispersion polymerization and soap-free emulsion (precipitation) polymerization methods excellent in particle size controllability are preferably used.

The particle size of the seed particles is not particularly limited because it varies depending on the particle size of the obtained projection particles, but the preferred lower limit is 1/10 of the particle size of the obtained projection particles, and the preferred upper limit is the particle size of the obtained projection particles. More specifically, the lower limit of the particle diameter of the seed particles is preferably 100 nm.

The medium in which the seed particles are dispersed is not particularly limited as long as it is incompatible with the seed particles, and examples thereof include water, methanol, ethanol, dimethyl sulfoxide, dimethylformamide, and a mixed solution thereof. Of these, water is preferable because it is easy to handle.

In order to stably disperse the seed particles in the medium, for example, dispersion stabilizers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyoxyethylene, cellulose, polyalkylene glycol alkyl ether, polyalkylene glycol alkyl phenyl ether, fatty acid It is preferable to add an ionic or nonionic surfactant such as diethanolamide, sodium lauryl sulfate, sodium alkylbenzenesulfonate, long chain fatty acid, long chain alkyltrimethylamine hydrochloride, dimethylalkylbetaine.
Further, additives such as auxiliary stabilizers, pH adjusters, anti-aging agents, antioxidants, preservatives and the like that are usually used in suspension polymerization methods and emulsion polymerization methods may be added to the medium.

The method for preparing the dispersion liquid in which the seed particles are dispersed in the medium is not particularly limited, and examples thereof include a method in which the seed particles are added to the medium and stirred.
In the above stirring, a homomixer, a homogenizer, or the like may be used in addition to a normal stirring blade, and an ultrasonic wave may be used in this case.

In the method for producing the protruding particles of this embodiment, the step of adding the child particles to the dispersion and then attaching the child particles to the surface of the seed particles is performed.
The said child particle comprises the protrusion part of the protrusion particle | grains obtained.
The child particles are not particularly limited, and examples thereof include those made of a resin, those made of an insulating inorganic material such as silica, and those made of a metal. Especially, what consists of resin is preferable. It does not specifically limit as said resin, For example, the material similar to the material which comprises the above-mentioned seed particle etc. are mentioned. These resins may be used alone or in combination of two or more.
The material constituting the child particles is such that the child particles attached to the surface of the seed particles are not dissolved by the polymerizable monomer when the seed particles are absorbed by the seed particles in the next step. It preferably has a crosslinked structure.

It does not specifically limit as a method of manufacturing the said child particle, For example, the method similar to the method of manufacturing the seed particle mentioned above is mentioned. Among these, a suspension polymerization method, a micro suspension method, an emulsion polymerization method, a mini-emulsion polymerization method, and the like that can form a highly crosslinked product are preferably used.

The child particles preferably have a polymerizable unsaturated group on the surface. As a result, when the above described child particles polymerize seed particles in which the polymerizable monomer has been absorbed, the above child particles are copolymerized with the seed particles. Bonding with the material particles becomes extremely strong.
The method for introducing a polymerizable unsaturated group into the surface of the child particle is not particularly limited. For example, (1) the functional group on the surface of the child particle is converted into a polymerizable unsaturated group by a one-stage or multi-stage reaction. Examples of the method include (2) a method of adding a monomer having two polymerizable unsaturated groups having different polymerization properties when preparing the child particles.

As the above method (1), for example, a method in which vinyl silane is reacted with the surface of a child particle made of silica to introduce a vinyl group; a methacrylic group is introduced by reacting methacrylic acid with the surface of a child particle made of glycidyl methacrylate. Method: A method of introducing a methacryl group by reacting 2-methacryloyloxyethyl isocyanate with the surface of a child particle made of hydroxyethyl methacrylate.

Examples of the monomer having two polymerizable unsaturated groups having different polymerizable properties in the method (2) include 2-hydroxy-3-acryloyloxypropyl methacrylate, allyloxy polyethylene glycol-polyethylene glycol monomethacrylate, and the like. Can be mentioned.

Although it does not specifically limit as a particle diameter of the said child particle, A preferable minimum is 50 nm. 50
When it is less than nm, when the protruding particle produced by the method for producing a protruding particle of the present invention is used as a gap material or conductive particle, the height of the protrusion becomes insufficient, and the movement preventing effect, the aluminum electrode surface The effect of breaking through the oxide film may not be obtained. Moreover, a preferable upper limit is 20% of the particle diameter of the base particle of the projection particle to be manufactured. If it exceeds 20%, the protrusions are larger than necessary with respect to the particle diameter of the base particles, and the characteristics of the base particles of the manufactured protrusion particles may not be expressed.

When the child particles are added to the dispersion, the child particles adhere to the surface of the seed particles by van der Waals force or electrostatic interaction. This adhesion method is a method called heteroaggregation. According to the hetero-aggregation method, as in the dry method using a conventional high-speed stirrer or a hybridizer, the base particles and the child particles are not deformed, and the child particles are laminated and adhered, The child particles do not melt and cannot be made into a single particle due to the coalescence of the particles, and the child particles can be adhered to the surface of the seed particles uniformly and in a single layer.

The number of child particles to be attached to the seed particles is not particularly limited, and varies depending on the particle diameter, the number of protrusions, and the use of the protrusion particles to be manufactured, but the lower limit of the exclusive area of the seed particle surface by the child particles is 40%. It is preferable to become. By attaching the child particles to the surface of the seed particles in this way, the seed particle surface is uniformly coated with the child particles, the seed particles are swollen by the polymerizable monomer described later, and the protrusions of the protrusion particles obtained by polymerization are further formed. They are formed at approximately equal intervals.
A preferred lower limit of the area occupied by the seed particles on the surface of the seed particles is 0.5%. If it is less than 0.5%, the number of protrusions of the protrusion particles to be produced is too small, and even if the resulting protrusion particles are used as a gap material, the movement preventing effect may not be obtained. Even if used, there may be no protrusion in the conduction direction, and the effect of breaking through the oxide film may not be obtained.
In the present specification, the exclusive area means the projected area of the child particles on the surface of the base material particles. The exclusive area can be controlled by the amount, concentration, surface potential, surface charge, medium polarity, pH, ionic strength, etc. of the child particles.

In the method for producing protruding particles of the present invention, it is preferable that the child particles attached to the seed particles are attached to the surface of the seed particles so as to be closely packed. As will be described later, in the method for producing protruding particles of the present invention, the polymerizable monomer is absorbed into the seed particles and swollen to form polymerizable droplets. At this time, if the child particles are attached to the surface of the seed particles so as to be densely packed, the exclusive area of the child particles attached to the surface of the polymerizable droplet after the swelling can be in the above range. In addition, the interval between the attached child particles can be made substantially uniform.

In the method for producing protruding particles of this embodiment, a step of absorbing the polymerizable monomer in the dispersion liquid in which the seed particles to which the child particles are attached is dispersed is then performed.

The polymerizable monomer is not particularly limited as long as it is polymerized or condensed by heat or light in the presence or absence of a polymerization initiator. Moreover, when using the protruding particle manufactured by the manufacturing method of the protruding particle of the present invention as a liquid crystal spacer or an anisotropic conductive material, it is preferable to have a crosslinked structure since the strength of the particle is required. In addition, a crosslinked structure can be given by using a crosslinkable polymerizable monomer for a part or all of the polymerizable monomers.

Examples of the polymerizable monomer include olefins such as ethylene, propylene, butylene, methylpentene, butadiene, and isoprene and derivatives thereof; styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and divinylbenzene. Styrene derivatives such as chloromethylstyrene; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate, vinyl fluoride, vinyl chloride, vinyl acetate, vinyl propionate, etc. Vinyl esters; unsaturated nitriles such as (meth) acrylonitrile; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, maleic anhydride; methyl (meth) acrylate, ethyl (meth) acrylic acid , Propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, ethylene glycol (meth) ) Acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, cyclohexyl (meth) acrylate, tetramethylol methane tetra (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane di (meth) Acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) a (Meth) acrylic acid ester derivatives such as acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate; 2-hydroxyethyl (meth) acrylate, Oxygen atom-containing (meth) acrylates such as glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, and glycidyl (meth) acrylate; acrylamides such as acrylamide, isopropylacrylamide, and propylene diacrylamide; γ- (meth) acryloxy Silane-containing monomers such as propyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane; dicarboxylic acids such as phthalic acid; diamines; S; diallyl phthalate, benzoguanamine, triallyl (iso) cyanurate, triallyl trimellitate, divinyl benzene, diallyl acrylamide, diallyl ether, triallyl isocyanate. These polymerizable monomers may be used alone or in combination of two or more.

Since the particle diameter of the base particle of the protruding particle manufactured according to the present invention depends on the particle diameter of the polymerizable droplet formed by absorbing the polymerizable monomer in the seed particle in this step, the particle of the protruding particle to be manufactured The diameter can be easily controlled by adjusting the amount of polymerizable monomer absorbed by the seed particles.
The amount of the polymerizable monomer to be absorbed by the seed particles is not particularly limited, but the preferable lower limit is twice and the preferable upper limit is 300 times the amount of the seed particles. If it is less than 2 times, the spacing between the projections of the obtained projection particles becomes too narrow and the effect of forming projections may not be expected, and if it exceeds 300 times, the polymerizable monomer cannot be completely absorbed, The dispersibility of the resulting polymerizable droplets may be impaired. A more preferable lower limit is 8 times, and a more preferable upper limit is 200 times.

The method for absorbing the polymerizable monomer in the seed particles to which the child particles are attached is not particularly limited. For example, the polymerizable monomer is dispersed in a medium to obtain a dispersion of the polymerizable monomer. A method of preparing and adding the dispersion of the polymerizable monomer to the dispersion in which the seed particles to which the child particles are attached is dispersed while stirring is exemplified.
The medium in which the polymerizable monomer is dispersed is not particularly limited, and examples thereof include the same medium as that in which the seed particles are dispersed. Moreover, you may add various additives, such as a dispersing agent and a dispersion stabilizer, as needed.

In the method for producing protruding particles of this embodiment, a step of polymerizing polymerizable droplets to which the child particles are attached is then performed. Specifically, for example, polymerization is started by heating or irradiating light using a polymerization initiator. When polymerization is initiated by heating, the heating temperature is appropriately determined depending on the composition and molecular weight of the polymerizable monomer to be used, the type and amount of the polymerization initiator, etc., but is usually in the range of 30 to 100 ° C.

The polymerization initiator may be contained in the polymerizable droplet, or may be dissolved in a medium in which the polymerizable droplet is dispersed. When contained in the polymerizable droplet, in the step of absorbing the polymerizable monomer in the seed particles to which the above child particles have adhered, after dissolving the polymerizable monomer in the polymerizable monomer, the polymerization initiator is dissolved. And a method of preparing the polymerizable droplets by absorbing the polymerizable monomer in the seed particles. When dissolving in the medium, the polymerization initiator is dissolved in the medium in advance, or after preparing the polymerizable droplets, dissolved in the same liquid as the medium, The method of adding to is mentioned.

The polymerization initiator is not particularly limited, and examples thereof include peroxides such as hydrogen peroxide and benzoyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl). Azonitrile compounds such as valeronitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2- (carbamoylazo) isobutyronitrile; 2 , 2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1 -Hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] and the like; 2,2′-a Bis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane], their hydrochlorides, sulfuric acid Cyclic azoamide compounds such as salts; azoamidine compounds such as 2,2′-azobis (2-amidinopropane) and 2,2′-azobis [N- (2-carboxyethyl) -2-methyl-propionamidine]; Examples include azocarboxylic acid compounds such as 2′-azobis (4-cyanovaleric acid); azooxime compounds such as 2,2′-azobis (2-methylpropionamidooxime), and the like.

The number of protrusions formed on the protruding particles manufactured through this step is appropriately selected depending on the particle diameter of the base particle, the particle diameter of the child particles, and the use of the protruding particles to be manufactured. The preferable lower limit of the exclusive area on the surface of the substrate particles is 0.5%, and the preferable upper limit is 50%. If it is less than 0.5%, the number of projections is too small, and even if the resulting projection particles are used as a gap material, the movement preventing effect may not be obtained. There may be no protrusion in the direction, and the effect of breaking through the oxide film may not be obtained. If it exceeds 50%, the physical properties of the protruding particles are greatly affected by the physical properties of the child particles, and the characteristics of the base particles may not be exhibited. The exclusive area of the substrate particle surface by the child particles can be controlled by the amount of the child particles combined with the seed particles.

Through the above operation, base particles are formed from the polymerizable droplets, and projecting particles in which the child particles are bonded to the surface of the base particles are obtained.

According to the method for producing a projecting particle of the present invention, it is possible to easily produce a projecting particle in which a child particle is bonded to the surface of a base material particle, and easily by applying a conventional seed polymerization technique. The size of the base particles can be adjusted, and the number and density of the protrusions can be controlled by adjusting the amount of the child particles added, and the protrusions are formed at substantially equal intervals. Protruding particles can also be produced. In addition, the protruding particles obtained by the manufacturing method of the protruding particles of the present invention have strong bonding between the base particles and the child particles, and do not easily peel off even after plating described later, and are stably conductive. Sexual protrusion particles can be produced.

Protrusion particles in which child particles are bonded to the surface of the substrate particles, wherein the child particles are bonded to the surface of the substrate particles at equal intervals, are also one aspect of the present invention.
The above-mentioned "child particles are bonded to the surface of the base material particles at equal intervals" does not mean that the distance between the child particles bonded to the surface of the base material particles is completely equal, but a slight error. Means substantially the same. Specifically, it means a state in which the variation in the interval between the protrusions is 20% or less, or the number of protrusions formed by two or more child particles is 20% or less.
Such protruding particles of the present invention can be preferably manufactured by using the method for manufacturing protruding particles of the present invention described above.

Conductive protruding particles comprising the protruding particles of the present invention and a metal layer formed on the surface of the protruding particles are also one aspect of the present invention.
The metal is not particularly limited as long as it has conductivity. For example, gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, Examples thereof include metals such as antimony, bismuth, germanium, cadmium and silicon, and metal compounds such as ITO and solder.
The metal layer may have a single layer structure or a laminated structure including a plurality of layers. In the case of a laminated structure, the outermost layer is preferably made of gold. By making the outermost layer of gold, conductive projection particles having high corrosion resistance and low contact resistance can be obtained.

The method for forming the metal layer on the surface of the protruding particles is not particularly limited, and examples thereof include known methods such as physical metal vapor deposition and chemical electroless plating. An electroless plating method is preferred. Examples of the metal layer that can be formed by the electroless plating method include gold, silver, copper, platinum, palladium, nickel, rhodium, ruthenium, cobalt, tin, and alloys thereof.

Although it does not specifically limit as thickness of the said metal layer, A preferable minimum is 0.005 micrometer and a preferable upper limit is 1 micrometer. If the thickness is less than 0.005 μm, a sufficient effect as a conductive layer may not be obtained. If the thickness exceeds 1 μm, the specific gravity of the obtained conductive projection particles becomes too high, or the hardness may not be sufficiently deformed. There are things to do. A more preferable lower limit is 0.01 μm, and a more preferable upper limit is 0.3 μm.

If the conductive projection particle of the present invention is used for conductive connection between the substrate and the electronic component, even if the oxide film is formed on the surface of the aluminum electrode or the like, the oxide film can be broken through, Extremely high connection reliability can be obtained.

The coated conductive particles comprising the conductive protruding particles of the present invention and the insulating particles covering the surfaces of the conductive protruding particles are also one aspect of the present invention. The coated conductive particles of the present invention can also be suitably used for conductive connection between a substrate and an electronic component. In addition, by insulatingly coating the surface of the conductive projection particles of the present invention, it is possible to prevent conduction between adjacent conductive projection particles, and thus to prevent leakage between circuit electrodes.

The insulating particles are not particularly limited as long as they are insulative, and examples thereof include those made of an insulating resin such as silica and the like. Among these, an insulating resin is preferable. It does not specifically limit as said insulating resin, For example, resin etc. which are used for the above-mentioned child particle are mentioned. These resins may be used alone or in combination of two or more.

The particle diameter of the insulating particles depends on the size of the protrusion and the number of protrusions, but the preferable lower limit is 5 nm and the preferable upper limit is 1000 nm. If the thickness is less than 5 nm, the distance between adjacent coated conductive particles is smaller than the electron hopping distance, and leakage between adjacent conductive projection particles is likely to occur. If the thickness exceeds 1000 nm, thermocompression bonding is performed between circuit electrodes. When doing so, the pressure and heat required may become too large. A more preferred lower limit is 10 nm, and a more preferred upper limit is 500 nm.

The insulating particles preferably have a positive charge. By having a positive charge, it is possible to bond to the conductive projection particles using the hetero-aggregation method, and since the insulating particles repel each other, the aggregation of the insulating particles is suppressed. Thus, a single coating layer can be formed. That is, when the insulating particles are positively charged, the insulating particles adhere to the metal surface particles as a single layer.

The conductive protruding particles or coated conductive particles of the present invention can be suitably used as an anisotropic conductive material by dispersing in an insulating binder resin. Such an anisotropic conductive material is also one aspect of the present invention.
In this specification, the anisotropic conductive material includes an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive, an anisotropic conductive ink, and the like.

The insulating binder resin is not particularly limited as long as it is insulative. For example, acrylic ester, ethylene-vinyl acetate resin, styrene-butadiene block copolymer and hydrogenated product thereof, and styrene-isoprene block copolymer. And thermoplastic resins such as hydrogenated products thereof; thermosetting resins such as epoxy resins, acrylate resins, melamine resins, urea resins, phenol resins; acrylic acid esters of polyhydric alcohols, polyester acrylates, polycarboxylic acids Examples thereof include resins that are cured by ultraviolet rays such as unsaturated esters, electron beams, and the like. Especially, the adhesive agent hardened | cured with a heat | fever and / or light is suitable.

In the anisotropic conductive material of the present invention, in addition to the binder resin which is an essential component and the conductive projection particles of the present invention, for example, a filler, a filler, etc. 1 or 2 of various additives such as softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, UV absorbers, lubricants, antistatic agents, flame retardants, etc. More than one kind may be added.

According to the present invention, there is provided a method for producing a projecting particle capable of firmly binding a child particle to the surface of a substrate particle, a projecting particle using the method for producing the projecting particle, a conductive projecting particle, and an anisotropic conductive material. Can provide material.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(1) Preparation of child particles 8 parts by weight of ethylene glycol dimethacrylate, 2 parts by weight of methyl methacrylate, 0.1 part by weight of hexadecane, 1 part by weight of polyoxyethylene (9) lauryl ether, 2,2′-azobisiso After uniformly emulsifying 0.1 part by weight of butyronitrile, 0.1 part by weight of 2,2′-azobis (2-amidinopropane) dihydrochloride and 100 parts by weight of distilled water with an ultrasonic homogenizer, A 1000 mL separable flask equipped with a mouth separable cover, a stirring blade, a three-way cock, a condenser, and a temperature probe was placed, and polymerization was performed at 70 ° C. for 12 hours in a nitrogen atmosphere.
After completion of the reaction, removal of unreacted monomers, polymerization initiators, and the like by centrifugation and washing were performed twice, and further dispersed with distilled water to obtain an average particle size of 250 nm, a CV value of 9.8%, and a solid content of 10 % Child particle dispersion. The particle size and distribution of the child particles were measured using a dynamic light scattering particle size distribution size (DLS8000, manufactured by Otsuka Electronics Co., Ltd.).

(2) Preparation of seed particles 10 equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube, and temperature probe
In a 00 mL separable flask, 500 mmol of styrene, 85 mmol of n-octyl mercaptan, 2 mmol of potassium persulfate, 2.5 mmol of sodium chloride, and 585 mL of distilled water were weighed, stirred at 200 rpm, and then at 70 ° C. for 24 hours in a nitrogen atmosphere. Polymerization was performed. After completion of the reaction, removal of unreacted monomer, polymerization initiator, etc. by centrifugation and washing were carried out twice, and further dispersed with distilled water to obtain an average particle size of 900 nm, CV value of 3.2%, solid content of 10 % Seed particle dispersion. In addition, the particle diameter and distribution of the seed particles were measured using a dynamic light scattering particle size distribution diameter (manufactured by Otsuka Electronics Co., Ltd., DLS8000).

(3) Preparation of insulating particles A 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a condenser tube, and a temperature probe was charged with 70 mmol methyl methacrylate, 10 mmol glycidyl methacrylate, ethylene glycol dimethacrylate. After weighing 20 mmol, phenyldimethylsulfonium methacrylate methylsulfate 3 mmol, 2,2′-azobis [N- (2-carboxyethyl) -2-methyl-propionamidine] tetrahydrate 3 mmol, and 470 mL of distilled water The insulating particle dispersion having an epoxy group on the surface having an average particle diameter of 305 nm, a CV value of 8.8% and a solid content of 10% is obtained by stirring at 200 rpm and polymerizing at 70 ° C. for 5 hours in a nitrogen atmosphere. Obtained. The particle diameter and distribution of the insulating particles were measured using a dynamic light scattering particle size distribution diameter (DLS8000, manufactured by Otsuka Electronics Co., Ltd.).

(4) Production of protruding particles (1) Into a 500 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a cooling tube, and a temperature probe, 10 g of the obtained seed particle dispersion and distilled water After weighing 90 mL, while stirring, 1 g of the obtained child particle dispersion was dropped to attach the child particles to the seed particle surface. Next, 0.05 g of sodium lauryl sulfate and 20 g of a 3% aqueous solution of polyvinyl alcohol were added to obtain a child particle-attached seed particle dispersion.
Separately, 120 g of divinylbenzene, 3 g of benzoyl peroxide, 0.7 g of sodium lauryl sulfate, and 800 mL of distilled water were mixed and emulsified with a homogenizer to obtain a polymerizable monomer emulsion.
The resulting polymerizable monomer emulsion is added to the child particle-attached seed particle dispersion, stirred at 100 rpm, and absorbed into the child particle-attached seed particles for 24 hours at room temperature under a nitrogen stream. Polymerizable droplets were obtained. Next, after setting the stirring speed to 200 rpm, the polymerizable droplets were polymerized by heating to 90 ° C. to obtain protruding particles (1).
When observed using a scanning electron microscope, the obtained protruding particles (1) had an average particle diameter of 4.01 μm and a CV value of 3% in the portion without protrusions, and each protruding particle (1) The average number of protrusions was 24 (13.5% as the projected area). Further, the formed protrusions were substantially equally spaced.

(5) Production of conductive projecting particles (1) The resulting projecting particles (1) are degreased, sensitized and activated to generate palladium nuclei on the resin surface, thereby forming catalyst nuclei for electroless plating. . Next, it was immersed in an electroless nickel plating bath to form a nickel plating layer. Furthermore, electroless displacement gold plating was performed on the surface of the nickel layer to obtain conductive protruding particles (1).
When the obtained conductive projection particles (1) were observed using a scanning electron microscope, the surface of the particles including the projections was plated with metal, and the average number of projections was 24. The number of protrusions did not decrease.

(6) Production of anisotropic conductive film (1) 100 parts by weight of epoxy resin (Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.), 2 parts by weight of trisdimethylaminoethylphenol and 100 parts by weight of toluene as binder resin After thoroughly mixing with the use of the film, it was coated on the release film so that the thickness after drying was 10 μm, and toluene was evaporated to obtain an adhesive film.
Then, the conductive protruding particles (1) obtained by adding 100 parts by weight of epoxy resin (manufactured by Yuka Shell Epoxy Co., Epicoat 828), 2 parts by weight of trisdimethylaminoethylphenol and 100 parts by weight of toluene as a binder resin, After thoroughly mixing using a planetary stirrer, the adhesive film containing conductive projection particles (1) is applied on the release film so that the thickness after drying is 7 μm, and toluene is evaporated. Obtained. In addition, the compounding quantity of electroconductive protrusion particle | grains (1) was made so that content in a film might be 50,000 pieces / cm < ² >.
By laminating the obtained adhesive film and the adhesive film containing the conductive protruding particles (1) at room temperature, an anisotropic conductive film (1) having a two-layer structure and having a thickness of 17 μm was produced.

(Reference example)
The anisotropic conductive film was manufactured in the same manner as the anisotropic conductive film (1) produced in Example 1 except that the compounding amount of the conductive projection particles (1) in the film was 100,000 particles / cm ² . A film (2) was produced.

(Example 2)
(1) Production of coated conductive particles (1) Reaction solution by dissolving 10 mmol of p-aminothiophenol in 500 mL of methanol in a 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade and a three-way cock. Got.
10 g of the conductive protruding particles (1) obtained in Example 1 were dispersed in the reaction solution under a nitrogen atmosphere, stirred at room temperature for 12 hours, filtered to remove unreacted p-aminothiophenol, and washed with methanol. Then, it dried and obtained the conductive projection particle | grains which aminated the surface.
The obtained aminated conductive protrusion particles were dispersed in 500 mL of acetone, 4 mL of an insulating particle dispersion having an epoxy group was added, and the mixture was stirred at room temperature for 6 hours. After filtration through a 3 μm mesh filter, the particles were further washed with acetone and dried to obtain coated conductive particles (1).
The coated conductive particle (1) has only one layer of coating on the surface, and the coated area of the insulating particle with respect to the area of 2 μm from the center of the coated conductive particle by image analysis (that is, the projected area of the particle diameter of the insulating particle) ) Was calculated, and the coverage was 40%.

(2) Production of anisotropic conductive film (3) Anisotropic conductive film (2) produced in Reference Example, except that coated conductive particles (1) were used instead of conductive projection particles (1) An anisotropic conductive film (3) was produced in the same manner.

(Comparative Example 1)
(1) Resin particles were obtained in the same manner as in (4) of Example 1 except that the manufacturing particle dispersion of the protruding particles (2) was not added. The obtained resin particles had a particle size of 3.9 μm.
After 10 g of the obtained resin particles and 1 g of the child particles (dried) obtained in Example 1 were combined using a hybridization system (manufactured by Nara Machinery Co., Ltd.) at 120 ° C. for 5 minutes, The mixture was cooled and uncomposited child particles were removed by an air stream to obtain protruding particles (2).
Observation with a scanning electron microscope revealed that the obtained protruding particles (2) had an average of 30 protrusions per one, but there were many variations and many protrusions did not have protrusions. Observed. Further, the protrusions were formed unevenly.

(2) Production of conductive projection particles (2) Conductive projection particles (2) in the same manner as the conductive projection particles (1) produced in Example 1, except that the obtained projection particles (2) were used. Got.
When the obtained conductive projection particles (2) were observed using a scanning electron microscope, the surface of the particles including the projections was metal-plated, but the average number of projections was 15; The number of was decreasing.

(3) Preparation of anisotropic conductive film (2) Anisotropy was performed in the same manner as the anisotropic conductive film (1) prepared in Example 1, except that the obtained conductive projection particles (2) were used. A conductive film (2) was produced.

(Comparative Example 2)
(1) Production of conductive protruding particles (3) The resin particles having an average particle size of 3.9 μm produced in Comparative Example 1 were degreased, sensitized and activated to produce palladium nuclei on the resin surface. The catalyst core for electrolytic plating was used. Next, it was immersed in an electroless nickel plating bath to form a nickel plating layer. At this time, an appropriate amount of L-cysteine was dropped at the initial stage of the nickel plating reaction to induce self-decomposition of nickel in the vicinity of the plating film, and the plating proceeded while taking in the fine particles of the nickel, thereby having protrusions. A nickel layer was formed. Next, electroless displacement gold plating was performed on the surface of the nickel layer to obtain conductive protruding particles (3).
When observed with a scanning electron microscope, the average number of protrusions per unit was 35, but the number and size of the protrusions varied greatly, and many protrusions with a size close to 1 μm were observed in the circumferential direction. It was. In addition, fine particles made of only nickel / gold, which are extremely difficult to remove, were observed. Further, the protrusions were formed unevenly.

(2) Production of anisotropic conductive film (5) Anisotropic conductive film (1) was produced in the same manner as the anisotropic conductive film (1) produced in Example 1 except that the obtained conductive projection particles (3) were used. A conductive film (3) was produced.

(Evaluation)
The anisotropic conductive films (1) to (5) produced in each example, comparative example, and reference example were cut to a size of 5 × 5 mm. This is attached to the center of an aluminum electrode having a width of 200 μm, a length of 1 mm, a height of 0.2 μm, and an L / S of 20 μm having a resistance measurement lead wire on one side, and then a glass substrate having the same aluminum electrode. After the alignment, the electrodes were pasted together.
The bonded portion of the glass substrate was subjected to thermocompression bonding under a pressure bonding condition of 10 N and 100 ° C., and then the resistance value between the electrodes and the presence or absence of leakage between the electrodes were evaluated.
The results are shown in Table 1.

As shown in Table 1, the anisotropic conductive film (1) produced in Example 1 had a low resistance value between the electrodes and no leakage between electrodes, whereas the anisotropic conductive film (1) produced in Example 1 produced Although the resistance value between the electrodes of the anisotropic conductive film (2) is low, the blending amount of the conductive protruding particles (1) in the film is larger than that of the anisotropic conductive film (1) of Example 1, and therefore, between the electrodes. A leak occurred. On the other hand, the anisotropic conductive film (3) produced in Example 2 has the coated conductive particles (1) in the film with the same blending amount as the conductive projection particles (1) blended in the film in the reference example. Although blended, no leakage occurred between the electrodes due to the excellent insulating properties of the coated conductive particles (1), and the resistance value between the electrodes was low.
On the other hand, the anisotropic conductive film (4) produced in Comparative Example 1 had no leakage between the electrodes, but the resistance value between the electrodes was high, and the anisotropic conductive film (5) produced in Comparative Example 2 was Although the resistance value between the electrodes was low, leakage occurred between the electrodes.

According to the present invention, there is provided a method for producing a projecting particle capable of firmly binding a child particle to the surface of a substrate particle, a projecting particle using the method for producing the projecting particle, a conductive projecting particle, and an anisotropic conductive material. Can provide material.

Claims (7)

A method for producing a protruding particle in which a child particle is bonded to the surface of a substrate particle,
Attaching child particles to the surface of the seed particles;
Swelling the seed particles with a polymerizable monomer to prepare polymerizable droplets; and
A process for producing protruding particles, comprising a step of polymerizing the polymerizable droplets. A method for producing a protruding particle in which a child particle is bonded to the surface of a substrate particle,
Mixing seed particles and a medium to prepare a dispersion in which the seed particles are dispersed in the medium;
Adding child particles to the dispersion to attach the child particles to the surface of the seed particles;
A step of mixing a polymerizable monomer in a dispersion liquid in which the seed particles to which the child particles are attached are dispersed, and allowing the seed particles to absorb the polymerizable monomer; and
A method for producing protruding particles, comprising a step of polymerizing the seed particles that have absorbed the polymerizable monomer. A projecting particle having child particles bonded to the surface of a substrate particle, wherein the child particles are bonded to the surface of the substrate particle at equal intervals. The protruding particle according to claim 3, wherein the protruding particle is produced by the method for producing a protruding particle according to claim 1. 5. A conductive projecting particle comprising the projecting particle according to claim 3 and a metal layer formed on a surface of the projecting particle. A coated conductive particle comprising the conductive protruding particle according to claim 5 and an insulating particle covering a surface of the conductive protruding particle. An anisotropic conductive material, wherein the conductive protruding particles according to claim 5 or the coated conductive particles according to claim 6 are dispersed in an insulating binder resin.