JP5902456B2 - Polymer particles, conductive particles and anisotropic conductive materials - Google Patents

Description

  The present invention relates to polymer particles, conductive particles having a conductive metal layer formed on the surface of the polymer particles, and an anisotropic conductive material containing the conductive particles.

  Electronic devices are becoming smaller and thinner and more functional each year. Therefore, for example, electronic devices such as a connection between an ITO (indium tin oxide) electrode of a liquid crystal display panel and a driving LSI (Large Scale Integration), a connection between an LSI chip and a circuit board, and a connection between fine pattern electrode terminals For the electrical connection between the minute parts, an electrical connection using an anisotropic conductive material containing conductive particles is employed.

  As the conductive particles used for the anisotropic conductive material, those having a resin particle as a core material and a conductive metal layer formed on the surface of the core material are generally used because of excellent compression deformability. Further, in order to obtain an anisotropic conductive material excellent in connection stability, particles having high flexibility and a high recovery rate are used.

As such particles having a high recovery rate, for example, resin particles composed of a specific acrylic monomer and having a compression deformation recovery rate of 80% or more and a compression modulus (20% K value) of 1000 to 4000 mN / mm ² ( Patent Document 1 (see claim 4)); polymer fine particles having a compression modulus (10% K value) of 10 to 50 kgf / mm ² (98 to 490 N / mm ² ) and a compression deformation recovery rate of 30% or more (patent Reference 2 (refer to claim 1)); Polymer fine particles having a compression modulus (10% K value) of 10 to 250 kgf / mm ² (98 to 2450 N / mm ² ) and a compression deformation recovery rate of 30% or more (Patent Document) 3 (see claim 1)).

JP 2010-159328 A JP 2000-309715 A JP 2000-319309 A

  When the conductive particles are hard as the core material, the conductive particles are pushed into the adherend when the electrodes and the like are pressed and connected, thereby forming indentations and increasing the connection area. . Moreover, it becomes easy to exclude the binder resin that exists between the conductive particles and the adherend during pressure connection. Therefore, it is preferable that the core material is hard in order to achieve low resistance in electrical connection using an anisotropic conductive material. However, although the polymer particles described in Patent Documents 1 to 3 are excellent in the recovery rate, the hardness is insufficient.

  This invention is made | formed in view of the said situation, and it aims at providing the electroconductive particle which can form an indentation with respect to a to-be-adhered body, and was excellent in connection reliability. Another object of the present invention is to provide an anisotropic conductive material containing the above conductive particles. Furthermore, an object of this invention is to provide the polymer particle which can be used conveniently as a core material of the above electroconductive particles.

The polymer particles of the present invention that can solve the above-mentioned problems are obtained by heat-treating particles containing a vinyltrialkoxysilane siloxane bond at a temperature of 200 ° C. or higher. The particles containing a vinyltrialkoxysilane siloxane bond preferably further contain a vinyl polymer. The polymer particles of the present invention preferably have a number average particle size of 0.5 μm to 4.0 μm, preferably a 10% K value of 3000 N / mm ² or more, and a recovery rate of 80% or more. It is preferable.
The present invention also includes conductive particles having a conductive metal layer on the surface of the polymer particles, and an anisotropic conductive material containing the conductive particles and a binder.

  The polymer particles of the present invention have an excellent recovery rate and a high hardness. Therefore, when the polymer particles of the present invention are used as a gap holding spacer of a liquid crystal cell or a touch panel cell in a liquid crystal display panel, the holding stability is excellent. Further, since the conductive particles of the present invention use the polymer particles as a core material, an indentation can be formed on the adherend during pressure connection, and the connection area can be increased, so that low resistance can be realized. Further, since the compression deformation recovery rate is excellent, it is possible to maintain good connection stability over a long period of time. Further, by using an anisotropic conductive material containing the conductive particles, a connection structure having low resistance and excellent connection stability can be obtained.

1. Polymer Particles The polymer particles of the present invention are obtained by heat-treating particles containing a vinyltrialkoxysilane siloxane bond. When vinyltrialkoxysilane is hydrolyzed / condensed in a solution in the presence of a catalyst, an unreacted hydroxy group (bonded to silicon) or an alkoxy group remains in the siloxane bond. By heat-treating the particles containing the siloxane bond, hydrolysis / condensation reaction of these residual hydroxy groups and residual alkoxy groups can be promoted. Therefore, a polysiloxane structure having a higher crosslinking density is formed, and particles with a significantly improved recovery rate can be obtained.

The heat treatment is preferably performed in air or in an inert gas, and more preferably in nitrogen gas. The temperature of the heat treatment is preferably 200 ° C. or higher, more preferably 250 ° C. or higher, further preferably 270 ° C. or higher, preferably lower than the thermal decomposition temperature, more preferably 400 ° C. or lower, and still more preferably 370 ° C. or lower.
The heat treatment time is preferably 0.3 hours or more, more preferably 0.5 hours or more, further preferably 0.7 hours or more, preferably 10 hours or less, more preferably 5.0 hours or less, Preferably it is 3.0 hours or less.

Examples of the particles containing a vinyltrialkoxysilane siloxane bond include particles containing a skeleton (polysiloxane skeleton) made of a (co) hydrolysis / condensation product of a silane monomer containing vinyltrialkoxysilane. ); A skeleton composed of (co) hydrolysis / condensation product of a silane monomer containing vinyltrialkoxysilane (polysiloxane skeleton) and a polymer skeleton of vinyl monomer containing vinyltrialkoxysilane (vinyl heavy) Particle (ii); containing a combined skeleton) and the like.
Among these, (ii) is preferable. Particles having a polysiloxane skeleton and a vinyl polymer are excellent in elastic deformability and contact pressure, and the connection reliability of the resulting conductive particles is more excellent. Further, when used as a gap holding spacer of a liquid crystal cell or a touch panel cell in a liquid crystal display panel, the gap holding stability is excellent.

In the vinyl trialkoxysilane, a vinyl group and three alkoxy groups are bonded to a silicon atom.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, and a heptyloxy group. Among these, as an alkoxy group, a C1-C5 thing is preferable, More preferably, it is C1-C4, More preferably, it is C1-C3. The three alkoxy groups may be the same or different, but the three alkoxy groups are preferably the same.
Examples of the vinyltrialkoxysilane include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltritert-butoxysilane, and the like.

  The polysiloxane skeleton can be formed by using vinyltrialkoxysilane and, if necessary, a silane monomer other than vinyltrialkoxysilane (hereinafter sometimes referred to as “other silane monomer”). These other silane monomers are classified into silane crosslinkable monomers and silane noncrosslinkable monomers. Moreover, when a silane crosslinkable monomer is used as the silane monomer, a crosslinked structure can be formed. The cross-linked structure formed by the silane cross-linkable monomer includes a cross-link between a vinyl polymer and a vinyl polymer (first form); a cross-link between a polysiloxane skeleton and a polysiloxane skeleton (second In which the vinyl polymer and the polysiloxane skeleton are cross-linked (third form).

Examples of the silane-based crosslinkable monomer that can form the first form (crosslinking between vinyl polymers) include silanes having two or more radical polymerizable groups such as dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane. Compounds.
Examples of the silane crosslinkable monomer that can form the second form (crosslink between polysiloxanes) include tetrafunctional silane single monomers such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Examples of the polymer include trifunctional silane monomers such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane.
Examples of the silane-based crosslinkable monomer that can form the third form (crosslinking between vinyl polymer and polysiloxane) include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3- (Meth) acryloyl such as acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxyethoxypropyltrimethoxysilane Di- or trialkoxysilane having a group; di- or trialkoxysilane having a vinyl group such as p-styryltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- ( 3 4-epoxycyclohexyl) di- or trialkoxysilanes having an epoxy group such as ethyltrimethoxysilane; di- or trialkoxysilanes having an amino group such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane; It is done. These silane crosslinking monomers may be used alone or in combination of two or more.

  Examples of the silane-based non-crosslinkable monomer include bifunctional silane-based monomers such as dimethyldimethoxysilane and dialkylsilane such as dimethyldiethoxysilane; and trialkylsilanes such as trimethylmethoxysilane and trimethylethoxysilane. And monofunctional silane-based monomers. These silane non-crosslinkable monomers may be used alone or in combination of two or more.

  When using a silane monomer other than vinyltrialkoxysilane, the content of vinyltrialkoxysilane in all silane monomers is preferably 60% by mass or more, more preferably 70% by mass or more. More preferably, 80 mass% or more is preferable. It is also preferable to use only vinyltrialkoxysilane as the silane monomer. When the content of the vinyltrialkoxysilane is 60% by mass or more, the elastic deformability and the contact pressure are excellent, and the connection reliability of the obtained conductive particles is more excellent.

The vinyl polymer can be formed by polymerizing a vinyl monomer (radical polymerization), and the vinyl monomer can be divided into a vinyl crosslinkable monomer and a vinyl noncrosslinkable monomer. .
The vinyl-based crosslinkable monomer is a monomer having a radically polymerizable group and capable of forming a crosslinked structure, specifically, a monomer having two or more radically polymerizable groups in one molecule. (Monomer (1)), or one radical polymerizable group in one molecule and other binding functional groups (protic hydrogen-containing groups such as carboxyl groups and hydroxy groups, terminal functions such as alkoxy groups) And the like (monomer (2)). However, in order to form a crosslinked structure with the monomer (2), it is necessary to have a counterpart monomer capable of reacting (binding) with the binding functional group of the monomer (2).

  The “radical polymerizable group” includes not only a carbon-carbon double bond but also a functional group such as a (meth) acryloxy group, an allyl group, an isopropenyl group, a vinylphenyl group, and an isopropenylphenyl group. Substituents composed of carbon-carbon double bonds are also included. In the present specification, “(meth) acryloxy group”, “(meth) acrylate” and “(meth) acryl” are respectively “acryloxy group and / or methacryloxy group”, “acrylate and / or methacrylate” and “acryl”. And / or methacryl ".

  Examples of the monomer (1) (monomer having two or more radical polymerizable groups in one molecule) among the vinyl-based crosslinkable monomers include, for example, allyl such as allyl (meth) acrylate. (Meth) acrylates; alkanediol di (meth) acrylate (for example, ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, etc.), polyalkylene glycol di (meth) acrylate (for example, diethylene glycol di ( (Meth) acrylate, triethylene glycol di (meth) acrylate, decaethylene Recall di (meth) acrylate, pentadecaethylene glycol di (meth) acrylate, pentacontactor ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) Di (meth) acrylates such as acrylate)) Tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate; Tetra (meth) acrylates such as pentaerythritol tetra (meth) acrylate; Dipentaerythritol hexa Hexa (meth) acrylates such as (meth) acrylate; aromatic hydrocarbon crosslinking agents such as divinylbenzene, divinylnaphthalene, and derivatives thereof (preferably divinyl Styrene polyfunctional monomers such as benzene); N, N-divinyl aniline, divinyl ether, divinyl sulfide, hetero atom-containing crosslinking agents such as divinyl sulfonic acid; and the like. A monomer (1) may be used independently and may use 2 or more types together.

  Among the vinyl-based crosslinkable monomers, the monomer (2) (a monomer having one radical polymerizable group and other binding functional group in one molecule) is, for example, (meta ) Monomers having a carboxyl group such as acrylic acid; hydroxy group-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, Monomers having hydroxy groups such as hydroxy group-containing styrenes such as p-hydroxystyrene; alkoxy such as 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate and 2-butoxyethyl (meth) acrylate Alkoxy groups such as group-containing (meth) acrylates and alkoxystyrenes such as p-methoxystyrene And the like; monomers having. A monomer (2) may be used independently and may use 2 or more types together.

  Examples of the vinyl non-crosslinkable monomer include a monomer having one radical polymerizable group in one molecule (monomer (3)), or the monomer in the case where no counterpart monomer is present. Monomer (2) (monomer having one radical polymerizable group and other binding functional group in one molecule).

  Among the vinyl non-crosslinkable monomers, the monomer (3) (monomer having one radical polymerizable group in one molecule) includes a (meth) acrylate monofunctional monomer and a styrene type. Monofunctional monomers are included. Examples of the (meth) acrylate monofunctional monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and pentyl (meth) acrylate. , Hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate Alkyl (meth) acrylates such as: cyclopropyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclo Cycloalkyl (meth) acrylates such as ndecyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate; phenyl (meth) acrylate, benzyl (meth) acrylate And aromatic ring-containing (meth) acrylates such as tolyl (meth) acrylate and phenethyl (meth) acrylate, and alkyl (meth) acrylates such as methyl (meth) acrylate are preferred. Styrene monofunctional monomers include styrene; alkyl styrenes such as o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, ethyl styrene (ethyl vinyl benzene), pt-butyl styrene, Examples include halogen group-containing styrenes such as o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene, and styrene is preferable. A monomer (3) may be used independently and may use 2 or more types together.

  The vinyl monomer is preferably a vinyl crosslinkable monomer, more preferably the monomer (1). In particular, (meth) acrylates (polyfunctional (meth) acrylate) having two or more (meth) acryloyl groups in one molecule and aromatic hydrocarbon crosslinking agents (especially styrene polyfunctional monomers) are preferable. Among the styrenic polyfunctional monomers, monomers having two vinyl groups in one molecule such as divinylbenzene are preferable. If divinylbenzene is used, polymer particles having high hardness and excellent heat resistance can be obtained.

  When the vinyl monomer is used, the amount used is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more with respect to 100 parts by mass of the silane monomer. Yes, it is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 100 parts by mass or less. If the amount of the vinyl monomer used is 10 parts by mass or more, the flexibility of the vinyl polymer can be expressed, and if it is 200 parts by mass or less, the rigidity of the silane condensate is expressed. Can do.

  In this case, the mass ratio between the total amount of the other silane monomers and the vinyl monomers used and the amount of vinyltrialkoxysilane used (other silane monomers + vinyl monomers / Vinyltrialkoxysilane) is preferably 0.1 or more, more preferably 0.2 or more, further preferably 0.3 or more, and preferably 2 or less, more preferably 1.5 or less, More preferably, it is 1 or less.

The particles containing vinyltrialkoxysilane are, for example, particles (i) containing a skeleton composed of a (co) hydrolysis / condensation product of a silane monomer containing vinyltrialkoxysilane, and silane containing vinyltrialkoxysilane. It can be obtained by hydrolysis and condensation polymerization of a monomer. Further, a particle (ii) including a skeleton composed of a (co) hydrolysis / condensation product of a silane monomer containing vinyltrialkoxysilane and a polymer skeleton of a vinyl monomer containing vinyltrialkoxysilane, Hydrolyzing and condensing a silane monomer containing vinyltrialkoxysilane to prepare polymerizable polysiloxane particles, and then radically polymerizing the polymerizable polysiloxane particles by absorbing the vinyl monomer. It is obtained by.
And as above-mentioned, the polymer particle of this invention is obtained by heat-processing to the particle | grains containing the siloxane coupling body of vinyl trialkoxysilane.

  The number average particle diameter of the polymer particles of the present invention is preferably 0.5 μm or more, preferably 12 μm or less, more preferably 4.0 μm or less, still more preferably 3.5 μm or less, and particularly preferably 3.2 μm or less. . When the particle diameter is smaller than 0.5 μm, when the surface is coated with a conductive metal layer to form conductive particles, the particles tend to aggregate and it may be difficult to form a uniform conductive metal layer. On the other hand, if the particle diameter exceeds 12 μm, the application application when conductive particles are used is limited, and there is a tendency for industrial fields of use to decrease.

  When conductive particles based on the polymer particles of the present invention are used as an anisotropic conductive material, the number average particle size of the polymer particles is preferably 0.5 μm or more, more preferably 1.0 μm or more, more preferably 1.6 μm or more, particularly preferably 2.0 μm or more, preferably 4.0 μm or less, more preferably 3.5 μm or less, still more preferably 3.2 μm or less, and even more preferably 3 It is 0.0 μm or less, more preferably 2.8 μm or less, still more preferably 2.7 μm or less, particularly preferably 2.6 μm or less, and most preferably 2.5 μm or less. With the fine pitch and low gap in the connected medium, the conductive particles are also required to have a small particle size. Further, as the adherend or adherend substrate is made thinner, a low connection resistance at low pressure connection is required. In particular, when the number average particle diameter is 3.2 μm or less, the compression elastic modulus (10% K value) at the time of minute deformation is increased, the indentation forming ability to the adherend is further improved, and a stable connection state. Is easily obtained. The variation coefficient of the particle diameter is preferably 20% or less, more preferably 10% or less, and further preferably 7% or less.

  The 10% compression load of the polymer particles of the present invention is preferably 0.588 mN (0.06 gf) or more, more preferably 0.686 mN (0.07 gf) or more, and still more preferably 0.784 mN (0.08 gf) or more. It is preferably 1.960 mN (0.2 gf) or less, more preferably 1.764 mN (0.18 gf) or less, and still more preferably 1.568 mN (0.16 gf) or less. If the 10% compressive load is within the above range, when polymer particles are used as a core material for conductive particles, an indentation can be formed in a connected medium such as an electrode, and there is no practical problem. Can be secured.

Polymer particles of the present invention is preferably a compression modulus of elasticity 3000N / mm ² or more when allowed to 10% compressive deformation, more preferably 5000N / mm ² or more, more preferably 10000 N / mm ² or more, more preferably 12000N / mm ² or more, more preferably 15000 N / mm ² or more, even more preferably 19600N / mm ² greater, particularly preferably at 20000N / mm ² or more, preferably 50,000 N / mm ² or less, more preferably 40000N / mm ² or less, more preferably 30000 N / mm ² or less.

  That is, it is preferable that the compression elastic modulus at the initial stage of deformation when compressing and deforming is high. When the core particles are soft, since they are compressed and deformed with a small pressure when they are pressure-connected, a large connection area can be obtained relatively easily. However, since it is soft, an indentation cannot be formed on the adherend, and it is difficult to eliminate the binder resin existing between the conductive particles and the adherend, so the connection resistance value is low. Difficult to do. However, if the polymer particles have a high compressive elastic modulus at the initial stage of deformation, the conductive particles having the polymer particles as a core material are bonded to the adherend when the electrodes are pressure-connected. Can be pushed into and form indentations. Moreover, it becomes easy to exclude the binder resin that exists between the conductive particles and the adherend during pressure connection. Therefore, the connection resistance value can be further reduced.

  The compression modulus of the polymer particles can be obtained from the following formula based on the compression load, compression displacement, and particle diameter when the polymer particles are compressed and deformed. Hereinafter, the compression elastic modulus (K value) at a displacement of 10% is referred to as a 10% K value.

[Wherein, K: compression elastic modulus (N / mm ² ), F: compression load (N), S: compression displacement (mm), R: particle radius (mm). ]

  The recovery rate of the polymer particles of the present invention is preferably at least 70%, more preferably at least 80%, even more preferably at least 85%, preferably at most 99%, more preferably at most 97%, further preferably at 95. % Or less. If the recovery rate is 70% or more, it is possible to follow changes in the electrode gap over time when used as an anisotropic conductive material, so that good connection reliability can be obtained. Sometimes the contact area can be increased while forming indentations on the adherend. A method for measuring the recovery rate will be described later.

  Since the polymer particles of the present invention have an appropriate hardness and a high recovery rate, spacers for cell gaps (or panel gaps) for display displays such as liquid crystal display devices and touch panels; It is useful for the core material of the conductive particles used for the anisotropic conductive material.

2. Electroconductive particle The electroconductive particle of this invention has a conductive metal layer which coat | covers the surface of the said polymer particle. Therefore, the electroconductive particle of this invention is equipped with the characteristic of the above-mentioned polymer particle. The metal constituting the conductive metal layer is not particularly limited. For example, gold, silver, copper, platinum, iron, lead, aluminum, chromium, palladium, nickel, rhodium, ruthenium, antimony, bismuth, germanium, tin, Examples thereof include metals such as cobalt, indium, nickel-phosphorus, and nickel-boron, metal compounds, and alloys thereof. Among these, gold, nickel, palladium, silver, copper, and tin are preferable because of excellent conductivity. In addition, nickel, nickel alloy, copper, copper alloy, silver, silver alloy, tin, and tin alloy are preferable from the viewpoint of inexpensiveness. Among them, nickel, nickel alloy (Ni-P, Ni-B, Ni-Zn, Ni-Sn) are preferable. Ni-W, Ni-Co, Ni-Ti) and the like are preferable. Further, the conductive metal layer may be a single layer or multiple layers. In the case of multiple layers, for example, a combination of nickel / gold, nickel / palladium, nickel / palladium / gold, nickel / silver, etc. Is preferred.

  The thickness of the conductive metal layer is preferably 0.01 μm or more, more preferably 0.03 μm or more, preferably 0.20 μm or less, more preferably 0.15 μm or less. When the thickness of the conductive metal layer is within the above range, when the conductive particles are used as an anisotropic conductive material, stable electrical connection can be maintained, and the mechanical properties of the polymer particles can be sufficiently obtained. You can save it.

  The conductive particles of the present invention may further have an insulating resin layer on the surface of the conductive metal layer. The insulating resin layer is not particularly limited as long as the insulating property between the conductive particles can be ensured, and the insulating resin layer can be easily collapsed or peeled off by a certain pressure and / or heating. For example, polyolefins such as polyethylene; (meth) acrylate polymers and copolymers such as polymethyl (meth) acrylate; thermoplastic resins such as polystyrene; and particularly cross-linked products thereof; heat such as epoxy resins, phenol resins, and melamine resins Curable resins; water-soluble resins such as polyvinyl alcohol and mixtures thereof.

  The insulating resin layer may be a single layer or a plurality of layers. For example, a single or multiple film-like layer; a layer in which particles of insulating, granular, spherical, lump, scale or other shapes are attached to the surface of the conductive particle; and the surface of the conductive particle is chemically modified Or a layer formed by doing so. The thickness of the resin insulating layer is preferably 0.01 μm to 1 μm, more preferably 0.1 μm to 0.5 μm. If the thickness of the resin insulating layer is within the above range, the electrical insulation between the particles becomes good while maintaining the conduction property by the conductive particles well.

  The number average particle diameter of the conductive particles of the present invention is preferably 1.1 μm or more, more preferably 1.2 μm or more, further preferably 1.3 μm or more, particularly preferably 1.4 μm or more, and 3.5 μm or less. More preferably, it is 3.3 μm or less, more preferably 3.0 μm or less, still more preferably 2.9 μm or less, still more preferably 2.8 μm or less, and particularly preferably 2.7 μm or less. When the number average particle diameter is within this range, the conductive particles have excellent indentation forming ability.

2-1. Manufacturing method of electroconductive particle The electroconductive particle of this invention is obtained by forming an electroconductive metal layer on the surface of the said polymer particle. The method for coating the surface of the polymer particles with the conductive metal layer is not particularly limited. For example, a method using electroless plating, displacement plating or the like; a paste obtained by mixing metal fine powder alone or in a binder with a polymer. Methods for coating particles: physical vapor deposition methods such as vacuum vapor deposition, ion plating, ion sputtering and the like. Among these, the electroless plating method is preferable because a conductive metal layer can be easily formed without requiring a large-scale apparatus.

  When the conductive particles of the present invention have an insulating resin layer, the surface of the conductive metal layer is insulated with a resin or the like after the electroless plating step. The method for forming the insulating resin layer is not particularly limited, for example, in the presence of conductive particles after the electroless plating treatment, interfacial polymerization, suspension polymerization, emulsion polymerization of the raw material of the insulating resin layer, A method of microencapsulating conductive particles with an insulating resin; a dipping method in which conductive particles are dispersed in an insulating resin solution in which the insulating resin is dissolved in an organic solvent and then dried; a spray drying method, by hybridization Any conventionally known method such as a method can be used.

3. Anisotropic conductive material The conductive particles of the present invention are also suitable as a constituent material of the anisotropic conductive material, and the anisotropic conductive material containing the conductive particles of the present invention and a binder is also preferable of the present invention. This is one of the embodiments. The form of the anisotropic conductive material is not particularly limited as long as the conductive particles of the present invention are used. For example, an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive is used. And various forms such as anisotropic conductive ink. That is, electrical connection can be achieved by providing these anisotropic conductive materials between opposing substrates or between electrode terminals. The anisotropic conductive material using the conductive particles of the present invention includes a conductive material for a liquid crystal display element (conductive spacer and composition thereof).

  The anisotropic conductive material is manufactured by dispersing the conductive particles of the present invention in an insulating binder resin to obtain a desired form. Of course, the insulating binder resin and the conductive particles May be used separately to connect between substrates or between electrode terminals. The binder resin is not particularly limited, and is, for example, a thermoplastic resin such as an acrylic resin, an ethylene-vinyl acetate resin, a styrene-butadiene block copolymer; a monomer or oligomer having a glycidyl group, and a curing agent such as isocyanate. Examples thereof include a curable resin composition that is cured by reaction and a curable resin composition that is cured by light and heat.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention. In the following, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.

1. Evaluation method 1-1. Average particle diameter <seed particles, polymer particles>
Measure the particle size of 30000 particles with a particle size distribution measuring device (“Coulter Multisizer III type”, manufactured by Beckman Coulter, Inc.) to obtain the average particle size based on the number and the standard deviation of the particle size. The CV value (coefficient of variation) based on the number of diameters was calculated.
Variation coefficient of particles (%) = 100 × (standard deviation of particle diameter / number average particle diameter)
<Conductive particles>
Using a flow type particle image analyzer (manufactured by Sysmex Corporation, “FPIA (registered trademark) -3000”), the particle diameter (μm) of 3000 conductive particles was measured to determine the number average particle diameter.

1-2.10% K value Particles 1 dispersed on a sample table (material: SKS flat plate) at room temperature (25 ° C.) using a micro compression tester (manufactured by Shimadzu Corporation, “MCT-W500”) A load was applied at a constant load speed (2.23 mN / sec) toward the center of the particle using a circular flat plate indenter (material: diamond) having a diameter of 50 μm. And the load when the compression displacement became 10% of the particle diameter was measured. In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value. The K value was calculated from the measured compression load, compression displacement of particles, and particle diameter.

1-3. Recovery rate Using a micro-compression tester (manufactured by Shimadzu Corporation, “MCT-W500”), at room temperature (25 ° C.), one particle dispersed on a sample stage (material: SKS material flat plate) has a diameter of 50 μm. Using a circular flat plate indenter (material: diamond) and compressing to the maximum load (2.452 mN) at a constant load speed (0.4462 mN / sec) toward the center of the particle in the “soft surface detection” mode. The amount of displacement (μm) was measured, and this was taken as the maximum amount of displacement L1.
Next, the displacement (μm) between the maximum load and the minimum load when the load is reduced to the minimum load (0.049 mN) at a constant unloading speed (0.4462 mN / sec) is measured. Was the recovery displacement L2. In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value.
Compression deformation recovery rate (%) = (L2 / L1) × 100

1-4. Connection reliability An anisotropic conductive film is sandwiched between an entire aluminum vapor-deposited glass substrate having resistance measurement lines and a polyimide film substrate having a copper pattern formed on a 20 μm pitch, and pressure bonding conditions of 1 MPa and 190 ° C. A test piece was prepared by thermocompression bonding.
And the initial resistance value A between the electrodes of a test piece was measured. Further, after the obtained test piece was left in an atmosphere of 85 ° C. and 85% RH for 500 hours, the resistance value B was measured in the same manner as the initial resistance value A. The case where the resistance value increase rate (%) calculated based on the following formula was 2% or less was evaluated as “◯”, and the case where it exceeded 2% was evaluated as “X”.
Resistance value increase rate (%) = [(B−A) / A] × 100

1-5. Indentation formation 0.1 mg of conductive adhesive paste is sandwiched between two glass substrates on which aluminum electrodes are formed, thermocompression bonded at 1 MPa and 190 ° C., and a test piece (an anisotropic conductive sheet made of a cured conductive adhesive) To obtain a connecting structure having a structure in which is sandwiched between electrodes.
In the test piece, the electrode surface on the side in contact with the anisotropic conductive sheet was observed with a metal microscope (magnification: 1000 times) to evaluate the presence or absence of indentation. The case where the indentation was confirmed was evaluated as “◯”, and the case where the indentation was not confirmed was evaluated as “x”.

2. Production Example 1 of Polymer Particles 1
A four-necked flask equipped with a cooling tube, a thermometer, and a dripping port was charged with 720 parts of ion-exchanged water, 1.2 parts of 25% aqueous ammonia and 480 parts of methanol and maintained at 25 ° C. Into this, 60 parts of vinyltrimethoxysilane (“KBM1003” manufactured by Shin-Etsu Chemical Co., Ltd.), which is a crosslinkable silane monomer, is dropped, and the internal temperature is maintained at 25 ° C. for 15 minutes, and then polyoxyethylene styrenation is performed. 32 parts of a 20% aqueous solution of phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., “Hytenol (registered trademark) NF-08”) was added, and the mixture was further stirred for 15 minutes. An emulsion of polysiloxane particles having a vinyl group (polymerizable polysiloxane particles) was prepared by performing decomposition and condensation reactions. When the obtained polysiloxane particle emulsion was sampled and the particle size was measured, the number average particle size was 2.25 μm.
Subsequently, a solution obtained by dissolving 1.0 part of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., “Hytenol NF-08”) as an emulsifier in 42 parts of ion-exchanged water. In addition, 42 parts of DVB960 (manufactured by Nippon Steel Chemical Co., Ltd., divinylbenzene content 96 mass%) and 2,2′-azobis (2,4-dimethylvaleronitrile) (made by Wako Pure Chemical Industries, Ltd., “V” as a polymerization initiator) -65 ") 1.0 part of the solution was added, and a monomer emulsion was prepared by emulsifying and dispersing at 8000 rpm for 5 minutes using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). This monomer emulsion was added to an emulsion of polysiloxane particles and further stirred. One hour after the addition of the monomer emulsion, the reaction solution was sampled and observed with a microscope. As a result, it was confirmed that the specific polysiloxane particles were enlarged by absorbing the monomer composition.
Next, the reaction solution was heated to 65 ° C. under a nitrogen atmosphere and kept at 65 ° C. for 2 hours to perform radical polymerization. After cooling the reaction solution, the obtained emulsion was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and then methanol, then dried at 120 ° C. for 2 hours, and further at 280 ° C. under a nitrogen atmosphere. By performing the heat treatment for 1 hour, the polymer particles No. 1 was obtained.

Production Example 2
Polymeric polysiloxane particles were produced in the same manner as in Production Example 1 except that the charging composition in the four-necked flask was changed to 680 parts of ion exchange water, 1.2 parts of 25% aqueous ammonia, and 520 parts of methanol. Subsequently, with respect to the monomer component to be absorbed, absorption of the monomer component was performed in the same manner as in Production Example 1 except that the content was changed to 24 parts DVB960 (manufactured by Nippon Steel Chemical Co., Ltd., divinylbenzene content 96 mass%). Radical polymerization was performed.
After cooling the reaction solution, the obtained emulsion was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and then methanol, then dried at 120 ° C. for 2 hours, and further at 350 ° C. under a nitrogen atmosphere. By performing the heat treatment for 3 hours, the polymer particles No. 2 was obtained.

Production Example 3
Preparation of polymerizable polysiloxane particles in the same manner as in Production Example 2, except that the charge composition in the four-necked flask was changed to 600 parts of ion exchange water, 1.2 parts of 25% ammonia water, and 600 parts of methanol. Except for the above, absorption of monomer components and radical polymerization were carried out in the same manner as in Production Example 2.
After cooling the reaction solution, the obtained emulsion is solid-liquid separated, and the resulting cake is washed with ion-exchanged water and then with methanol, and then subjected to heat treatment at 200 ° C. for 2 hours without passing through a drying step. By applying the polymer particles No. 3 was obtained.

Production Example 4
Except that the heat treatment conditions were changed to 240 ° C. for 2 hours under a nitrogen atmosphere, the same procedure as in Production Example 3 was carried out. 4 was obtained.

Production Example 5
In the same manner as in Production Example 3, polymerizable polysiloxane particles were prepared, and monomer components were absorbed and radical polymerization was performed.
After cooling the reaction solution, the obtained emulsion was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and then methanol, dried at 120 ° C. for 2 hours, and further at 320 ° C. under a nitrogen atmosphere. By performing the heat treatment for 1 hour, the polymer particles No. 5 was obtained.

Production Example 6
Except that the heat treatment conditions were changed to 350 ° C. for 3 hours under a nitrogen atmosphere, the polymer particle No. 6 was obtained.

Production Example 7
A four-necked flask equipped with a cooling tube, a thermometer, and a dripping port was charged with 720 parts of ion-exchanged water, 1.2 parts of 25% aqueous ammonia and 480 parts of methanol and maintained at 25 ° C. 120 parts of vinyltrimethoxysilane (“KBM1003”, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a crosslinkable silane monomer, is dropped into it, and the internal temperature is maintained at 25 ° C. for 15 minutes, and then polyoxyethylene styrenation is performed. Addition of 64 parts of 20% aqueous solution of phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., “Hytenol NF-08”), and further stirring for 15 minutes, hydrolysis and condensation reaction of vinyltrimethoxysilane Then, an emulsion of polysiloxane particles having a vinyl group (polymerizable polysiloxane particles) was prepared. The obtained polysiloxane particle emulsion was sampled and the particle size was measured. The number average particle size was 2.9 μm.
Subsequently, a solution in which 1.0 part of 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., “V-65”) as a polymerization initiator was dissolved in 30 parts of methanol was added. Then, the reaction solution was heated to 65 ° C. under a nitrogen atmosphere and kept at 65 ° C. for 2 hours to carry out radical polymerization. After cooling the reaction solution, the obtained emulsion was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and then methanol, then dried at 120 ° C. for 2 hours, and further at 350 ° C. under a nitrogen atmosphere. By performing the heat treatment for 3 hours, the polymer particles No. 7 was obtained.

Production Example 8
The polymer particles No. 1 were prepared in the same manner as in Production Example 1 except that no heat treatment was performed in a nitrogen atmosphere. 8 was obtained.

Production Example 9
Except that no heat treatment was performed in a nitrogen atmosphere, the polymer particles No. 1 were prepared in the same manner as in Production Example 6. 9 was obtained.

Production Example 10
Except that no heat treatment was performed in a nitrogen atmosphere, the polymer particles No. 1 were prepared in the same manner as in Production Example 7. 10 was obtained.

3. Production of conductive particles Polymer particle No. 1 to 10 were etched with sodium hydroxide, and then sensitized with a tin dichloride solution. Further, activation with a palladium dichloride solution was performed to form palladium nuclei. Next, 2 parts of polymer particles having palladium nuclei formed were added to 400 parts of ion-exchanged water and subjected to ultrasonic dispersion treatment, and then the obtained resin particle suspension was heated in a 70 ° C. warm bath. The electroless nickel plating reaction is caused by adding 600 parts of electroless plating solution (“Schumer (registered trademark) S680” manufactured by Nippon Kanisen Co., Ltd.) separately heated to 70 ° C. while the suspension is heated. I let you. After confirming that the generation of hydrogen gas was completed, solid-liquid separation was performed, followed by washing with ion exchange water and methanol in that order, and vacuum drying at 100 ° C. for 2 hours to obtain nickel-plated particles.
Next, the obtained nickel plating particles were added to a displacement gold plating solution containing potassium gold cyanide, and the nickel layer surface was further plated with gold to obtain conductive particles. The film thickness of the conductive metal layer in the obtained conductive particles was as shown in Table 1.

4). Production of anisotropic conductive material 1 part of conductive particles, 100 parts of epoxy resin (manufactured by Mitsubishi Chemical Corporation, “JER828”) as a binder resin, curing agent (manufactured by Sanshin Chemical Co., Ltd., “Sun-Aid (registered trademark) SI-” 150 ") and 2 parts toluene. Furthermore, 50 parts of φ1 mm zirconia beads were added and dispersed by stirring for 10 minutes at 300 rpm using two stainless steel stirring blades to prepare a conductive adhesive paste.
An anisotropic conductive film was obtained by applying the obtained paste onto a PET film subjected to a peeling treatment and drying it by a bar coater.

  Polymer particle No. obtained above. Table 1 shows the evaluation results of the average particle diameter and compression deformation characteristics of 1 to 10. Moreover, the evaluation result about the anisotropic conductive material containing the electroconductive particle obtained above was combined with Table 1, and was shown.

Polymer particles No. 1 obtained by subjecting particles containing a vinyltrialkoxysilane siloxane binder to a heat treatment of 200 ° C. or higher. Nos. 1 to 7 all have an excellent recovery rate and a high hardness. These polymer particles No. Conductive particles Nos. 1 to 7 having a core as a core material. When 1-7 were used, the obtained connection structure was excellent in connection reliability.
On the other hand, polymer particles having no heat treatment at 200 ° C. or higher were applied to particles containing a vinyltrialkoxysilane siloxane binder. As for 8-10, all are inferior to a recovery rate, and hardness is low. These polymer particles No. Conductive particles Nos. 8 to 10 having a core material. When 8-10 was used, the connection structure obtained was inferior in connection reliability.

  The polymer particles of the present invention have an excellent recovery rate and a high hardness. Therefore, if conductive particles having the polymer particles of the present invention as a core material are used, a connection structure having low resistance and excellent connection stability can be obtained. The conductive particles of the present invention are suitably used for anisotropic conductive materials such as anisotropic conductive films and anisotropic conductive pastes. Moreover, when the polymer particles of the present invention are used as a gap retaining spacer for a liquid crystal cell in a liquid crystal display panel or a cell in a touch panel, the retention stability is excellent.

Claims (3)

Look-containing siloxane bonds of the vinyl trialkoxy silanes are particles that are further crosslinked with an aromatic hydrocarbon-based crosslinking agents, polymer particles, wherein the recovery rate is 70% or more.   A conductive particle comprising a conductive metal layer on the surface of the polymer particle according to claim 1.   An anisotropic conductive material comprising the conductive particles according to claim 2 and a binder.