Composite particles and method for producing the same

Abstract

The present invention addresses the problem of providing polymer particles having both monodispersibility and high hardness and a method for producing the same.　The polymer particles of the present invention are characterized by comprising a (meth)acrylic resin that is prepared by polymerizing (meth)acrylic ester (A) having a cyclic ether structure and that has a structure wherein cyclic ether moieties in the cyclic ether structure are ring-opening polymerized with each other.

Description

Technical Field

[0001] The present invention relates to polymer particles and a method for producing the same.

Background Art

[0002] In the connection of semiconductor elements, wiring boards, etc., in order to make electrical connections between a large number of opposing electrodes and wirings, a connection method using an anisotropic conductive material is widely used. The anisotropic conductive material is a material in which conductive particles are dispersed in a binder resin (adhesive), and examples thereof include anisotropic conductive paste (ACP) and anisotropic conductive film (ACF).

[0003] The conductive particles used for anisotropic conductive connection are formed by covering polymer particles serving as a core with a metal layer. In recent years, in order to improve the performance of anisotropic conductive materials, the development of conductive particles contained in anisotropic conductive materials has been promoted. Since the compression deformation characteristics of the conductive particles are strongly affected by the characteristics of the polymer particles serving as the core, hardening of the polymer particles is required to improve the connection reliability during pressure connection. In addition, the polymer particles used for anisotropic conductive materials are required to have monodispersity from the viewpoint of connection reliability.

[0004] Patent Document 1 discloses a step (a) of radical polymerizing a polymerizable monomer having a double bond and a functional group capable of reacting with an amino group to obtain mother particles, and after step (a), contacting the mother particles with an amino compound having an amino group, and further crosslinking the crosslinked polymer by the reaction between the functional group and the amino group. The crosslinked polymer particles described in Patent Document 1 are characterized by having good compression characteristics.

[0005] In addition, Patent Document 2 discloses a method for producing crosslinked fine particles, which comprises a step of absorbing a compound having two or more amino groups into organic fine particles having a glycidyl group, and a crosslinking step of reacting the glycidyl group with the amino group, and crosslinked particles produced by the production method. The crosslinked fine particles described in Patent Document 2 are characterized by being monodisperse and excellent in solvent resistance and heat resistance.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The polymer particles proposed in the above Patent Document 1 and Patent Document 2 were insufficient in achieving both monodispersity and high hardness. An object of the present invention is to provide polymer particles that achieve both monodispersity and high hardness, and a method for producing the same.

Means for Solving the Problems

[0008] The present inventors intensively studied to solve the above problems. As a result, it has been found that the above problems can be solved by adding an imidazole-based compound or / and an amino compound having a tertiary amino group to polymer particles containing a (meth)acrylic resin having a cyclic ether structure and subjecting the cyclic ether moieties in the cyclic ether structure to ring-opening polymerization, and the present invention has been completed. The present invention relates to, for example, the following [1] to [8].

[0009] [1] Polymer particles comprising a (meth)acrylic resin obtained by polymerizing a (meth)acrylic acid ester (A) having a cyclic ether structure and having a structure in which the cyclic ether moieties in the cyclic ether structure are subjected to ring-opening polymerization.

[0010] [2] The polymer particles according to [1], wherein the (meth)acrylic resin further contains a structure derived from a polymerizable monomer (B) other than the (meth)acrylate (A) having the cyclic ether structure.

[0011] [3] The polymer particles according to [2], wherein the polymerizable monomer (B) is at least one compound selected from the group consisting of monomers having 1 to 4 (meth)acryloyl groups in one molecule.

[0012] [4] The polymer particles according to any one of [1] to [3], wherein the (meth)acrylate (A) having the cyclic ether structure is a compound represented by the following formula (1).

[0013] [Chemical formula] [In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, x represents an integer of 1 to 6, Y represents a single bond or -O-CH2-, and z represents an integer of 0 to 2.] [5] The polymer particles according to any one of [1] to [4], comprising a (meth)acrylic resin having a structure formed by polymerizing the (meth)acrylate (A) having the cyclic ether structure and adding an imidazole-based compound to a site where a part of the cyclic ether structure is ring-opened.

[0014] [6] In the polymer particles, the 10% K value is 3,000 to 7,000 N / mm 2 The polymer particles according to any one of [1] to [5]. [7] A method for producing the polymer particles according to any one of [1] to [6], Step (1) of radically polymerizing a polymerizable monomer component containing a (meth)acrylate (A) having a cyclic ether structure to obtain mother particles containing a (meth)acrylic resin, Contacting the mother particles with an imidazole-based compound and / or an amino compound having a tertiary amino group to subject the cyclic ether moieties in the cyclic ether structure to ring-opening polymerization, thereby obtaining polymer particles containing a (meth)acrylic resin having a structure formed by ring-opening polymerization of the cyclic ether moieties with each other (Step 2); and a step (3) of pulverizing the polymer particles. A method for producing polymer particles.

[0015] [8] The polymer particles according to any one of [1] to [6] above, which are used for the conductive particles of the anisotropic conductive adhesive. [Advantages of the Invention]

[0016] According to the present invention, it is possible to provide polymer particles having both monodispersity and high hardness, and a method for producing the same. [Embodiments for Carrying Out the Invention]

[0017] Hereinafter, the polymer particles of the present invention and a method for producing the same will be specifically described. [Polymer particles] The polymer particles of the present invention contain a (meth)acrylic resin. The (meth)acrylic resin is obtained by polymerizing a (meth)acrylate (A) having a cyclic ether structure, and has a structure in which the cyclic ether moieties in the cyclic ether structure are subjected to ring-opening polymerization with each other.

[0018] In the present specification, (meth)acrylic is used as a general term for acrylic and methacrylic, and may be either acrylic or methacrylic. (Meth)acrylate is used as a general term for acrylate and methacrylate, and may be either acrylate or methacrylate. (Meth)acryloyl is used as a general term for acryloyl and methacryloyl, and may be either acryloyl or methacryloyl.

[0019] In the present invention, the “(meth)acrylic resin” refers to a resin in which the total of the structural units derived from (meth)acrylic acid, the structural units derived from acrylate, the structural units derived from acrylic ester, the structural units derived from methacrylic acid, the structural units derived from methacrylate, and the structural units derived from methacrylic ester is 50% by mass or more based on 100% by mass of all the structural units of the (meth)acrylic resin.

[0020] By containing the above (meth)acrylic resin, the polymer particles of the present invention can achieve both monodispersity and high hardness. [Method for producing polymer particles] The method for producing the polymer particles of the present invention is a step (1) of subjecting a monomer component containing a (meth)acrylic ester (A) having a cyclic ether structure to radical polymerization to obtain mother particles containing a (meth)acrylic resin; a step (2) of bringing the mother particles into contact with an imidazole-based compound or / and an amino compound having a tertiary amino group to carry out ring-opening polymerization between the cyclic ether moieties in the cyclic ether structure, thereby obtaining polymer particles containing a (meth)acrylic resin having a structure formed by ring-opening polymerization between the cyclic ether moieties; and a step (3) of pulverizing the polymer particles.

[0021] Since the method for producing the polymer particles of the present invention can complete the synthesis in one pot from the step of producing particles before crosslinking to obtaining polymer particles through a crosslinking reaction, the manufacturing operation can be simplified.

[0022] <Step (1)>[ The mother particles containing a (meth)acrylic resin are obtained by subjecting a polymerizable monomer component containing a (meth)acrylic ester (A) having a cyclic ether structure to radical polymerization by a known method.

[0023] «(Meth)acrylate (A) having a cyclic ether structure» (Meta)acrylic acid ester (A) having a cyclic ether structure (hereinafter also referred to as “(meta)acrylic acid ester (A)”) is not particularly limited as long as it is a (meta)acrylic acid ester having a cyclic ether structure in the molecule, and known (meta)acrylic acid esters having a cyclic ether structure can be widely used.

[0024] Examples of the cyclic ether structure include oxacyclopropane (oxirane), oxacyclobutane (oxetane), oxacyclopentane (tetrahydrofuran), oxacyclohexane (tetrahydropyran), 1,4-dioxacyclohexane (1,4-dioxane), 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 1,4-epoxycyclohexane, 1-methyl-1,2-epoxycyclohexane, exo-2,3-epoxynorbornane, and the like. Among these, oxirane is preferable from the viewpoint of high reactivity and easy ring-opening polymerization of cyclic ether moieties with each other by a catalyst.

[0025] (Meta)acrylic acid ester (A) has a structure in which a cyclic ether structure is directly or indirectly bonded to the oxygen atom of the (meta)acrylic acid ester. For example, a group represented by the following formula (I) is interposed between the oxygen atom of the ester and the cyclic ether structure.

[0026] -(CH2) m - ···(I) (In formula (I), m represents an integer of 1 to 7.) (Meta)acrylic acid ester (A) is preferably a compound represented by the following formula (1), and more preferably a compound represented by the following formula (2).

[0027]

Chemical formula

[0028]

Chemical formula

[0029] Examples of the compound represented by formula (2) include glycidyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, glycidyloxy (poly) alkylene glycol (meth) acrylate, methyl glycidyl (meth) acrylate, and 4-hydroxybutyl acrylate glycidyl ether.

[0030] Among these, from the viewpoint of ensuring the polymerization stability of the polymer particles while increasing the crosslinking density of the polymer particles, glycidyl (meth) acrylate and 4-hydroxybutyl acrylate glycidyl ether are preferred.

[0031] These compounds may be used alone or in combination of two or more. The content of the structural unit derived from (meth) acrylic acid ester (A) in the (meth) acrylic resin is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, still more preferably 10 to 50% by mass, and particularly preferably 10 to 30% by mass based on 100% by mass of all the structural units of the (meth) acrylic resin.

[0032] When the content of the structural unit derived from (meth) acrylic acid ester (A) is within the above range, it is possible to achieve both the polymerization stability of the polymer particles and the ring-opening polymerization of the cyclic ether moiety by the catalyst. The content of the structural unit derived from the (meth)acrylic acid ester (A) can be calculated from the amount of the (meth)acrylic acid ester (A) in the polymerizable monomer component used in the production of the (meth)acrylic resin.

[0033] «Polymerizable monomer (B)» Preferably, the polymer particles of the present invention further contain a structure derived from a polymerizable monomer (B) other than the (meth)acrylic acid ester (A) in the (meth)acrylic resin. By including the polymerizable monomer (B), the resulting polymer particles are excellent in monodispersity and high hardness.

[0034] In step (1), by radically polymerizing the polymerizable monomer (B) together with the (meth)acrylic acid ester (A), polymer particles further containing a structure derived from the polymerizable monomer (B) can be obtained.

[0035] The polymerizable monomer (B) is not particularly limited as long as it can copolymerize with the (meth)acrylic acid ester (A). Examples thereof include monofunctional monomers such as (meth)acrylic acid-based monomers, styrene-based monomers, functional group-containing monomers, conjugated diene-based monomers, monomers forming polyurethane resins, and polyols. Preferably, at least one compound selected from the group consisting of monomers having 1 to 4 functional groups in one molecule is preferred, and more preferably, at least one compound selected from the group consisting of monomers having 1 to 4 (meth)acryloyl groups in one molecule.

[0036] Examples of the (meth)acrylic acid-based monomer include (meth)acrylic acid alkyl esters; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, etc. (meth)acrylic acid aryl esters; phenyl (meth)acrylate, benzyl (meth)acrylate, etc. (Meth)acrylic acid alkoxyalkyl; methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, etc. Salts such as (meth)acrylic acid and alkali metal salts of (meth)acrylic acid; Alicyclic alcohol (meth)acrylate esters; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc.

[0037] Examples of styrene monomers include alkylstyrenes such as styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene, fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, chloromethylstyrene, styrene iodide, nitrostyrene, acetylstyrene, methoxystyrene, α-methylstyrene, vinyltoluene, etc.

[0038] Examples of functional group-containing monomers include Oxazoline group-containing polymerizable compounds; 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, etc. Aziridine group-containing polymerizable compounds; (meth)acryloyl aziridine, 2-aziridinyl ethyl (meth)acrylate, etc. Epoxy group-containing vinyl monomers; allyl glycidyl ether, glycidyl ether (meth)acrylate, 2-ethyl glycidyl ether (meth)acrylate, etc. Hydroxyl group-containing vinyl compounds; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, monoesters of (meth)acrylic acid with polypropylene glycol or polyethylene glycol, and adducts of lactones with 2-hydroxyethyl (meth)acrylate, etc. Fluorine-containing vinyl monomer; fluorine-substituted (meth)acrylic acid alkyl ester, etc., Carboxyl group-containing vinyl monomer; unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid and fumaric acid, salts thereof, and (partial) ester compounds and acid anhydrides thereof, etc., Reactive halogen-containing vinyl monomer; 2-chloroethyl (meth)acrylate, 2-chloroethyl vinyl ether, vinyl monochloroacetate, vinylidene chloride, etc., Amide group-containing vinyl monomer; (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, etc., Organosilicon group-containing vinyl compound monomer; vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, 2-methoxyethoxytrimethoxysilane, etc., Others, macromonomers; substances having a radically polymerizable vinyl group at the end of the copolymer of the above monomers (for example, fluorine-based macromonomers, silicon-containing macromonomers, urethane-based macromonomers), Acrylonitrile; vinyl acetate; can be mentioned.

[0039] Examples of the conjugated diene monomer include butadiene, isoprene, chloroprene, etc. As the monomer for forming the polyurethane resin, a polyol mainly composed of glycol and a diisocyanate raw material, etc. can be used. For example, aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and p-phenylene diisocyanate, aliphatic diisocyanates, bifunctional terminal isocyanate urethane prepolymers, etc. can be mentioned.

[0040] Examples of the polyol include diol compounds such as ethylene glycol and diethylene glycol, polyether glycols, etc. The above-mentioned polymerizable monomer may be used alone or in combination of two or more.

[0041] When the (meth)acrylic resin contains a structural unit derived from the polymerizable monomer (B), from the viewpoint of adjusting the polymerization stability and hardness of the resulting polymer particles, the content of the structural unit derived from the polymerizable monomer (B) is preferably 15 to 90% by mass based on 100% by mass of all the structural units of the (meth)acrylic resin.

[0042] The content of the structural unit derived from the polymerizable monomer (B) can be calculated from the amount of the polymerizable monomer (B) in the monomer component used in producing the (meth)acrylic resin. From the viewpoint of adjusting the hardness of the resulting polymer particles, a polyfunctional monomer may be used as the polymerizable monomer (B) within a range that does not impair the effects of the present invention.

[0043] Examples of the polyfunctional monomer include bifunctional monomers; ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyoxyethylene di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, divinylbenzene, etc., trifunctional monomers; trimethylolpropane triacrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris(2-(meth)acryloxyethyl isocyanurate), etc., Monomers having four or more functional groups; tetra(meth)acrylate compounds such as pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, ethoxylated dipentaerythritol tetra(meth)acrylate, propoxylated dipentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated ditrimethylolpropane tetra(meth)acrylate and ethoxylated ditrimethylolpropane tetra(meth)acrylate, An adduct obtained by an addition reaction of a diisocyanate compound having an aliphatic group between diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diisocyanate methylcyclohexane, isophorone diisocyanate and methylene bis(4-cyclohexyl isocyanate), or a diisocyanate compound having an aromatic group such as diisocyanate methylbenzene or 4,4'-diphenylmethane diisocyanate, and glycidol di(meth)acrylate, Examples include dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate and the like.

[0044] «Radical polymerization» The mother particles containing the (meth)acrylic resin are obtained by radically polymerizing the (meth)acrylic acid ester (A) and, if necessary, the polymerizable monomer (B) by a known method.

[0045] Examples of this method include a method of emulsion or suspension polymerization in the presence of a radical polymerization initiator, or a method of swelling and polymerizing a monomer together with a radical polymerization initiator using non-crosslinked seed particles (so-called seed polymerization method), and polymerization methods in an aqueous medium such as a soap-free emulsion polymerization method. Among these polymerization methods, it is preferable to use the seed polymerization method because mother particles having a particle diameter of several μm and a uniform particle diameter can be obtained.

[0046] (Radical polymerization initiator) Examples of the radical polymerization initiator that can be used in the above polymerization include persulfates such as potassium persulfate and ammonium persulfate; peroxides such as benzoyl peroxide and lauryl peroxide; and azo compounds such as azobisisobutyronitrile. The polymerization initiator may be used alone or in combination of two or more. The amount of the polymerization initiator used is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the monomer component.

[0047] (Emulsifier) Examples of the emulsifier that can be used in the above polymerization include alkyl sulfonates such as sodium dodecyl sulfonate; alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate; alpha-sulfonated fatty acid ester salts such as sodium 2-sulfo-tetradecanoate 1-methyl ester; polyethylene glycol alkyl aryl ethers such as polyethylene glycol nonyl phenyl ether; polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether; polyoxyethylene polycyclic phenyl ethers, allyl ethers, and salts of their sulfuric acid esters. Among these, alkyl benzene sulfonates are preferred. The emulsifier may be used alone or in combination of two or more. The amount of the emulsifier used is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the monomer component.

[0048] (Dispersion stabilizer) Examples of the dispersion stabilizer that can be used in the above polymerization include partially saponified polyvinyl alcohol; completely saponified polyvinyl alcohol; polyacrylic acid, its copolymers, and neutralized products thereof; polymethacrylic acid, its copolymers, and neutralized products thereof; celluloses such as carboxymethyl cellulose and hydroxypropyl methyl cellulose; and polyvinyl pyrrolidone. The dispersion stabilizer may be used alone or in combination of two or more. The amount of the dispersion stabilizer used is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the monomer component.

[0049] Examples of the aqueous medium that can be used for the above polymerization include water and a mixture of water and a hydrophilic organic solvent. Examples of water include purified water (e.g., ion-exchanged water, distilled water), groundwater, and tap water.

[0050] Examples of the hydrophilic organic solvent include lower alcohols such as methanol, ethanol, and isopropanol; polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, and triethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; ketones such as acetone; ethers such as tetrahydrofuran; and esters such as methyl formate.

[0051] The hydrophilic organic solvent may be used alone or in combination of two or more. The addition amount of the hydrophilic organic solvent is usually 10 parts by mass or less with respect to 100 parts by mass of water. In this specification, unless otherwise specified, "aqueous medium" refers to the above medium.

[0052] In the above polymerization method, the polymerization temperature is usually 40 to 100 °C, preferably 55 to 85 °C, and the polymerization time is usually 1 to 24 hours, preferably 1 to 10 hours. In the case of seed polymerization, the above polymerization conditions can be adopted at each stage.

[0053] Seed polymerization is a polymerization method using a seed when performing polymerization. As seed polymerization, it is preferably carried out as seed emulsion polymerization, which is a kind of emulsion polymerization. In seed emulsion polymerization, the nucleation stage in the system in normal emulsion polymerization can be replaced by a seed. By using a seed with a uniform particle size and swelling the seed sufficiently with a monomer before polymerization, resin particles with a large and uniform particle size can be obtained.

[0054] When obtaining a (meth)acrylic resin by seed polymerization, the (meth)acrylate (A) and, if necessary, the polymerizable monomer (B) and other monomer components are copolymerized in the presence of a seed.

[0055] As seeds, it is preferable to use monodisperse particles from the viewpoint of making the particle size of the (meth)acrylic resin uniform. As seeds, it is preferable to use polymers of the alkyl (meth)acrylate esters exemplified as the monomer components, for example, particles of polymethyl methacrylate (PMMA) or polymethyl acrylate.

[0056] The seed polymerization may be repeated a plurality of times. Usually, the seed polymerization is carried out 1 to 15 times, preferably 1 to 10 times, to obtain (meth)acrylic resin particles. When the seed polymerization is repeated, the resin particles obtained by the first seed polymerization are used as the seeds for the second seed polymerization, and similarly, the resin particles obtained by the (n - 1)-th seed polymerization are used as the seeds for the n-th seed polymerization. The examples of the seeds described above are examples of the seeds used for the first seed polymerization when the seed polymerization is carried out a plurality of times.

[0057] The average particle size of the seeds used for the first seed polymerization, that is, the first seed polymerization, varies depending on the desired size of the average particle size of the (meth)acrylic resin and the number of times the seed polymerization is repeated. Usually, seeds with an average particle size of 0.1 to 3.0 μm, preferably 0.1 to 2.0 μm are used.

[0058] As seeds, usually 1 to 50 parts by mass, preferably 1 to 30 parts by mass are used per 100 parts by mass of the monomer component. When the seed polymerization is carried out a plurality of times, in each seed polymerization, usually 1 to 50 parts by mass, preferably 1 to 30 parts by mass of the seeds are used per 100 parts by mass of the monomer component.

[0059] Also, the CV value of the seeds is preferably 10% or less, more preferably 2 to 8% with high monodispersity. The CV value (Coefficient of Variation) is an index of the particle size distribution of the particles and is also a value called the coefficient of variation, which can be obtained by the following formula (II).

[0060] CV value [%] = (σ / D) × 100 ··· (II) [In formula (II), σ is the standard deviation and D is the average particle diameter.] When the total amount of each monomer in the monomer component is 100 parts by mass of (meth)acrylate (A) and polymerizable monomer (B), the amount of (meth)acrylate (A) is preferably 5 to 90 parts by mass, and the polymerizable monomer (B) is 10 to 95 parts by mass. More preferably, the (meth)acrylate (A) is 10 to 80 parts by mass, and the polymerizable monomer (B) is 20 to 90 parts by mass. Even more preferably, the (meth)acrylate (A) is 10 to 50 parts by mass, and the polymerizable monomer (B) is 50 to 90 parts by mass. Particularly preferably, the (meth)acrylate (A) is 10 to 30 parts by mass, and the polymerizable monomer (B) is 70 to 90 parts by mass. When a (meth)acrylic resin is obtained by a multi-step reaction such as seed polymerization, the amount of each monomer used when the total amount of all monomer components used in each step is 100 parts by mass may be within the above range.

[0061] In step (1), finally, if necessary, the (meth)acrylic resin can be washed and dehydrated with ion-exchanged water using a Buchner funnel or the like. <Step (2)>[ In step (2), after step (1), the mother particles are brought into contact with an imidazole-based compound and / or an amino compound having a tertiary amino group, and the cyclic ether moieties in the cyclic ether structure are subjected to ring-opening polymerization to obtain polymer particles containing a (meth)acrylic resin having a structure formed by ring-opening polymerization of the cyclic ether moieties.

[0062] In the (meth)acrylic resin, the structure formed by ring-opening polymerization of the cyclic ether moieties in the cyclic ether structure may be such that the cyclic ether moieties of one type in the cyclic ether structure are subjected to ring-opening polymerization, or the cyclic ether moieties of two or more different types are subjected to ring-opening polymerization.

[0063] Examples of the structure formed by ring-opening polymerization of the cyclic ether moieties include, for example, the repeating unit represented by the following formula (3).

[0064] [Chemical formula] [In formula (3), P 1 represents a polymer chain containing a structural unit derived from (meth)acrylate (A).] For example, when glycidyl methacrylate is used as the polymerizable monomer, the structure formed by the ring-opening polymerization of cyclic ether moieties is represented by the following formula (4). In this case, the cyclic ether moieties of the glycidyl methacrylate polymer, that is, the epoxy groups, undergo ring-opening polymerization. Therefore, the resulting polymer particles have a repeating structure of glycidyl methacrylate polymer chains in step (1), and further have a repeating structure formed by the ring-opening polymerization of the epoxy groups of glycidyl methacrylate in step (2).

[0065] [Chemical formula] The content of the structural unit formed by the ring-opening polymerization of cyclic ether moieties in the cyclic ether structure of the (meth)acrylic resin is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, still more preferably 10 to 50% by mass, and particularly preferably 10 to 30% by mass, based on 100% by mass of all the structural units of the (meth)acrylic resin.

[0066] When the content of the structure formed by the ring-opening polymerization of cyclic ether moieties is within the above range, polymer particles excellent in high hardness and monodispersity can be obtained. «Imidazole-based compound» The polymer particles of the present invention are preferably obtained by polymerizing a (meth)acrylate (A) having a cyclic ether structure, and contain a (meth)acrylic resin having a structure in which an imidazole-based compound is added to a part of the cyclic ether structure to open the cyclic ether moiety.

[0067] Examples of the imidazole-based compound include an imidazole-based compound having an active hydrogen at the 1-position represented by the following formula (5), or an imidazole-based compound having no active hydrogen at the 1-position represented by the following formula (6).

[0068] [Chemical formula]

[0069] [Chemical formula] [In formula (5) and formula (6), R 3 and R 6 represent an organic group, and R 4 and R 5 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.] Examples of the imidazole-based compound having an active hydrogen at the 1-position represented by formula (5) include, for example, 2-ethyl-4-methylimidazole, 2-phenyl-1H-imidazole, 2-methylimidazole, ethyl 4-methyl-1H-imidazole-5-carboxylate, 2-isopropylimidazole, 1H-imidazole-4,5-dicarboxylic acid, benzimidazole, 2-phenyl-5-benzimidazolesulfonic acid, 2-hydroxybenzimidazole, 4-methylimidazole, 5,6-dimethylbenzimidazole.

[0070] Examples of the imidazole-based compound having no active hydrogen at the 1-position represented by formula (6) include, for example, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, 1-isobutyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-1-benzyl-1H-imidazole.

[0071] Among the above imidazole-based compounds, 2-ethyl-4-methylimidazole is preferred from the viewpoints of reactivity and water solubility. The imidazole compound may be used alone or in combination of two or more.

[0072] The addition amount of the imidazole compound in step (2) is 0.01 to 5.0 parts by mass, preferably 0.05 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass, based on 100 parts by mass of the solid content of the mother particles.

[0073] The molecular weight of the imidazole compound is preferably 50 to 1,000, more preferably 50 to 500, and even more preferably 50 to 300. In step (2), when an imidazole compound having an active hydrogen at the 1-position is used, the active hydrogen of the imidazole compound reacts with the cyclic ether of a part of the side chain of the (meth)acrylic resin, and the imidazole compound can be added to the site where a part of the cyclic ether structure is ring-opened.

[0074] Examples of the structure in which a part of the cyclic ether structure is added with an imidazole compound to open the cyclic ether site include a structure represented by the following formula (7) in which an imidazole compound having an active hydrogen at the 1-position reacts with the cyclic ether of a part of the side chain of the (meth)acrylic resin, the ether ring is opened, and the imidazole compound is added.

[0075] [Chemical formula] [In formula (7), R 3 represents an organic group, R 4 and R 5 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, P 2 represents the main chain of the (meth)acrylic resin, and w represents an integer of 1 to 6.] A structure in which an imidazole-based compound is added to a part of the cyclic ether structure and the cyclic ether moiety is ring-opened may be in the same molecule as a (meth)acrylic polymer that constitutes a (meth)acrylic resin having a structure formed by ring-opening polymerization of the cyclic ether moieties, or may be in the molecule of a (meth)acrylic polymer different from the (meth)acrylic polymer.

[0076] When the polymer particles of the present invention have a structure in which an imidazole-based compound is added to a part of the cyclic ether structure and the cyclic ether moiety is ring-opened, from the viewpoint of the balance with the amount of the cyclic ether moieties that react in the ring-opening polymerization of the cyclic ether moieties, the content of the structural unit in which the cyclic ether moiety is ring-opened by adding the imidazole-based compound is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, still more preferably 10 to 50% by mass, and particularly preferably 10 to 30% by mass with respect to 100% by mass of all the constitutional units of the polymer particles.

[0077] «Amino compound having a tertiary amino group» Examples of the amino compound having a tertiary amino group include trimethylamine, triethylamine, tributylamine, trioctylamine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N-methyldiethanolamine, N-n-butyldiethanolamine, N-t-butyldiethanolamine, N,N-diethylisopropanolamine, 1-methylimidazole, 1,8-diazabicyclo[5.4.0]undec-7-ene, and polyethyleneimine.

[0078] Among these, from the viewpoint of obtaining polymer particles in which the cyclic ether moieties are ring-opened and polymerized and both monodispersity and high hardness are achieved, an amino compound having only a tertiary amino group and not having a primary and / or secondary amino group in the molecule of the compound is preferred.

[0079] Compounds having a tertiary amino group, unlike compounds having a primary or secondary amino group, promote the reaction as a polymerization catalyst. Tertiary amines formed after the reaction between an amino compound having a primary or secondary amino group and a cyclic ether group are less likely to have a catalytic function due to their steric hindrance, but compounds having a tertiary amino group have a catalytic function because they are strongly basic and can cause ring-opening polymerization between cyclic ether moieties.

[0080] The addition amount of the amino compound having a tertiary amino group in step (2) is 0.01 to 5.0 parts by mass, preferably 0.05 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the solid content of the mother particles.

[0081] The average molecular weight of the amino compound having a tertiary amino group is preferably 50 to 2,000, more preferably 50 to 500, still more preferably 50 to 200. In step (2), one or more imidazole compounds or amino compounds having a tertiary amino group can be used respectively, and the imidazole compound and the amino compound having a tertiary amino group may be used in combination within a range not impairing the effects of the present invention. Among them, it is more preferable to use an imidazole compound because the polymer particles can be made harder.

[0082] «Other components» In step (2), other components may be used as necessary together with the imidazole compound or the amino compound having a tertiary amino group. Examples of the other components include amino compounds having a primary amino group and / or amino compounds having a secondary amino group.

[0083] Examples of the amino compound having a primary amino group include alkyl diamine; Aliphatic amines such as menthylamine, isophoronediamine, xylylenediamine, diethylenetriamine (including secondary amines), trimethylenetetramine (including secondary amines), tetraethylenepentamine (including secondary amines), 1,3-bis(aminomethyl)cyclohexane, diethylaminopropylamine, 4,4'-methylenebis(2-methylcyclohexylamine); Aromatic amines such as m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, 4,4'-diaminodiphenylether, 1,3-bis(3-aminophenoxy)benzene can be mentioned.

[0084] Examples of the amino compound having a secondary amino group include, for example, methylcyclohexylamine, diethylenetriamine (including primary amines), trimethyltetramine (including primary amines), tetraethylenepentamine (including primary amines); aromatic amines such as 4,4'-methyleneaniline.

[0085] When using a compound having a primary amino group and / or a secondary amino group, the addition amount of the compound having a primary amino group and / or a secondary amino group is preferably 0.7 parts by mass or less with respect to 100 parts by mass of the solid content of the mother particles.

[0086] When the usage amount is below the above numerical value, the cyclic ether sites of (meth)acrylate (A) can be ring-opening polymerized without impairing the catalytic action of the imidazole-based compound or the amino compound having a tertiary amino group.

[0087] When the usage amount exceeds the above range, an addition reaction occurs between the cyclic ether sites present on the surface of the polymer particles and the primary amino group and / or secondary amino group, and problems such as the curing being completed without some of the cyclic ethers reacting occur.

[0088] In step (2), when an imidazole-based compound having an active hydrogen at the 1-position is used, it is considered that after the imidazole-based compound is added to the site where a part of the cyclic ether structure is ring-opened, the imidazole-based compound acts as a catalyst to promote the ring-opening polymerization of the cyclic ether sites of the mother particles.

[0089] On the other hand, in step (2), when an imidazole-based compound having no active hydrogen at the 1-position or an amino compound having a tertiary amino group is used, it is considered that the imidazole-based compound or the amino compound having a tertiary amino group promotes the ring-opening polymerization of the cyclic ether sites of the mother particles as a catalyst without adding to a part of the cyclic ether structure.

[0090] In these ring-opening polymerizations, the molar ratio (imidazole or amino compound having a tertiary amino group / (meth)acrylate ester (A) having a cyclic ether structure) of the imidazole-based compound or the amino compound having a tertiary amino group to the (meth)acrylate ester (A) having a cyclic ether structure is preferably 0.001 to 0.4, more preferably 0.002 to 0.2. Since the imidazole-based compound and the amino compound having a tertiary amino group act as catalysts for ring-opening polymerization of the cyclic ether sites, if the molar ratio is within the above range, the anionic polymerization reaction proceeds sufficiently. The ring-opening polymerization can be carried out, for example, at 100 to 200 °C for 0.5 to 2 hours.

[0091] <Step (3)>[ In step (3), the polymer particles obtained in step (2) are pulverized. The method for separating the polymer particles from the dispersion medium is not particularly limited, and known methods such as filtration and centrifugation can be used. Then, the polymer particles separated by using a commonly employed method such as freeze-drying method or spray-drying method can be dried and pulverized.

[0092] In consideration of the hardness of the polymer particles, it is preferable to dry under conditions where the particles are not deformed. The dried polymer particles are preferably pulverized using a mortar, a jet mill, or the like. [Physical properties of polymer particles] Although the polymer particles of the present invention are not particularly limited, the average particle diameter is preferably 2 to 20 μm, more preferably 2 to 5 μm. If the average particle diameter is less than the above range, the polymer particles may tend to aggregate. In this specification, all "average particle diameters" including the average particle diameter used for calculating the CV value and 10% K value of the polymer particles can be determined by the measurement method described in the examples.

[0093] The CV value of the polymer particles is preferably 15% or less, more preferably 7% or less. If the CV value exceeds the above range, the properties of the polymer particles in various applications tend to deteriorate. For example, when the polymer particles are used as conductive particles constituting an anisotropic conductive adhesive, the connection reliability tends to decrease. The CV value of the particle diameter can be determined by the same method as described for the CV value of the seeds above.

[0094] The polymer particles of the present invention preferably have a 10% K value determined by the following formula of 3,000 to 7,000 N / mm 2 and more preferably 3,300 to 6,000 N / mm 2 .

[0095] 10% K value (N / mm 2 ) = (3 / √2)·F·S -3 / 2 ·R -1 / 2 [F and S are the load value (N) and compression displacement (mm) in the 10% compression deformation of the polymer particles, respectively, and R is the radius (mm) of the polymer particles, which is half of the average particle diameter of the polymer particles measured by the method described in the examples.] When the 10% K value of the polymer particles is too small, when used as an anisotropic conductive material, the binder (adhesive) around the conductive particles cannot be sufficiently excluded (spread out), or the penetration into the electrode is weak and contact point dropout may occur, resulting in the inability to obtain a low connection resistance value. On the other hand, when the 10% K value of the polymer particles is too large, although the true contact area involved in electron conduction increases and the resistance value decreases, the connection site may be damaged, and it may not be possible to ensure a good electrical contact state.

[0096] The 10% K value is a value calculated from the compression load when the particle diameter is deformed by 10%, and it represents the hardness of the sphere universally and quantitatively. The specific measurement method of the 10% K value is described in the examples below.

[0097] The polymer particles of the present invention preferably have a so-called breaking point where the particles break before reaching the maximum load when the particles are compressed. As a method for obtaining polymer particles having a breaking point, a method of forming a three-dimensional network structure in the obtained polymer by including a polyfunctional monomer as the polymer constituting the polymer particles can be mentioned. Also, even when the polymer is composed only of monofunctional monomers, a method of promoting the ring-opening polymerization of epoxy groups of uncrosslinked polymers by contacting a compound having a tertiary amino group or an imidazole-based compound as a post-added catalyst can be mentioned.

[0098] [Uses of polymer particles] The use of the polymer particles of the present invention is not particularly limited. For example, in the field of electrical and electronic materials such as conductive particles for anisotropic conductive adhesives, various spacers, modifiers for the sliding properties of resin films, rheology control additives, shot blasting agents, abrasives, carriers for chromatography, etc. The polymer particles of the present invention are preferably applied to the polymer particles that are the core of the conductive particles used in anisotropic conductive adhesives from the viewpoint of exhibiting the effects of the present invention.

[0099] <Anisotropic conductive adhesive>[ When the polymer particles of the present invention are used in an anisotropic conductive adhesive, conductive particles can be obtained by providing a conductive metal layer on the surface of the polymer particles. The method for forming a metal layer on the surface of the polymer particles is not particularly limited. For example, methods such as electroless plating, coating with a paste obtained by mixing metal fine powder alone or with a binder, physical vapor deposition methods such as vacuum evaporation, ion plating, and ion sputtering can be mentioned. More specifically, for example, the method described in JP-A-2000-319309 can be mentioned.

[0100] The anisotropic conductive adhesive only needs to contain the conductive particles and a binder resin, and other components are not particularly limited, and components conventionally contained in anisotropic conductive adhesives can be used without particular limitation.

[0101] The binder resin is not particularly limited as long as it is an insulating resin. For example, thermoplastic resins such as acrylic resins, ethylene-vinyl acetate resins, and styrene-butadiene block copolymers, curable resin compositions that are cured by reaction with monomers or oligomers having glycidyl groups and curing agents such as isocyanates, curable resin compositions that are cured by light or heat, and the like can be mentioned.

[0102] Also, depending on the adhesive manufacturing method, the anisotropic conductive adhesive can be made into a film form or a paste form, and the dispersion method can be appropriately changed according to the form. In the case of a film-shaped anisotropic conductive adhesive (anisotropic conductive film), it is obtained by molding a mixture in which conductive particles are dispersed in a resin component into a film shape. In the case of an anisotropic conductive paste, the viscosity and the like are adjusted using a solvent for the mixture obtained in the same manner as the anisotropic conductive film.

[0103] When the polymer particles of the present invention are used in an anisotropic conductive adhesive, the polymer particles are preferably contained in an amount of 5 to 60 parts by mass, more preferably 10 to 50 parts by mass, per 100 parts by mass of the anisotropic conductive adhesive. If the content of the conductive particles is too small, sufficient electrical conduction may be difficult to obtain. On the other hand, if the content of the conductive particles is too large, the conductive particles may come into contact with each other, and it may be difficult to exhibit the function as an anisotropic conductive material.

[0104] The anisotropic conductive adhesive can be obtained, for example, by mixing or kneading at least conductive particles and an adhesive, but usually it can be obtained by mixing or kneading conductive particles, an adhesive, a curing agent, and an organic solvent.

Examples

[0105] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the description of the following examples and the like, unless otherwise specified, "parts" means "parts by mass".

[0106] [Average particle diameter] The average particle diameter of the polymer particles obtained in the examples and comparative examples was measured using a laser diffraction particle size distribution analyzer FPIA-3000S (manufactured by Spectris Co., Ltd.), and the average value of the particle diameters (cumulative 50% particle diameter based on volume) in the case of an effective analysis number of 30,000 was measured and taken as the average particle diameter.

[0107] [CV value] The CV value of the polymer particles obtained in the examples and comparative examples was determined from the following formula. CV value (%) = standard deviation of particle size distribution / average particle diameter × 100 [10% K value] The 10% K value of the polymer particles obtained in the examples and comparative examples was determined as follows using an ultra-micro indentation hardness tester ENT-NEXUS (manufactured by Elionix, Inc.). At 25°C, a 50-μmφ flat indenter was attached to the tip of the tester. Using the microscope attached to the apparatus, one polymer particle with a diameter of 3.0 μm was selected. The polymer particle was compressed under the conditions of a maximum load of 50 mN and a load rate of 1.33 mN / second, and the compression load F (N) when the particle diameter was deformed by 10% was measured and determined from the following formula.

[0108] 10% K value (N / mm 2 ) = (3 / √2)·F·S -3 / 2 ·R -1 / 2 [F and S are the load value (N) and compression displacement (mm) at 10% compression deformation of the polymer particle, respectively, and R is the radius (mm) of the polymer particle, which is half of the average particle diameter of the polymer particle measured by the method described in the example.] [Breaking point] Using the same tester as that for measuring the 10% K value, when the particle cracked before reaching the maximum load during compression of the particle, the breaking point was regarded as "present". The breaking point was used as an index indicating that the uncrosslinked polymer constituting the polymer particle had undergone ring-opening polymerization between epoxy groups and crosslinking between polymers by a tertiary amine or imidazole-based post-added catalyst. In Tables 1 and 2, the notation "absent" in the column of the breaking point means that there is no corresponding data.

[0109] [IR (910 cm -1 )] By infrared absorption spectroscopy (IR), peaks around 910 cm -1 were observed, and it was confirmed that all epoxy groups of the polymer particle had reacted by an addition reaction of an amino compound or a ring-opening polymerization between epoxy groups due to the disappearance of the peaks. In Tables 1 and 2, the symbol "-" in the column of IR (910 cm -1 ) means that there is no corresponding data, and "remaining" means that the peak remains, that is, a part of the epoxy groups of the polymer constituting the polymer particle exist as epoxy groups without the addition reaction by an amine compound proceeding or without ring-opening polymerization.

[0110] The respective evaluation results are shown in Table 1 and Table 2. [Example 1] <Step (1)> (First-stage polymerization: Production of monodisperse particles) Into a 1-liter four-necked flask equipped with a thermometer and a nitrogen inlet tube, 100 parts of methyl methacrylate (hereinafter also referred to as "MMA") and 300 parts of ion-exchanged water were charged, mixed and stirred, and further heated to 80 °C while stirring under a nitrogen stream to obtain a mixed solution. 0.5 part of potassium persulfate was added to the heated mixed solution, and the reaction was carried out for 6 hours while maintaining the temperature at 80 °C to obtain a dispersion (A1) of polymethyl methacrylate (PMMA) resin particles.

[0111] The PMMA resin particles obtained by separation and drying from the dispersion (A1) were spherical monodisperse particles with an average particle diameter of 0.4 μm and a CV value of 3.5%. The solid content concentration in the dispersion (A1) was 24% by mass.

[0112] (Second-stage polymerization: Seed polymerization) Into a 1-liter flask, 100 parts of methyl methacrylate and 1.0 part of benzoyl peroxide as an initiator were charged and dissolved to obtain a solution. 0.5 part of sodium dodecylbenzenesulfonate and 300 parts of ion-exchanged water were added to the solution, and emulsified with a homomixer to obtain an emulsion.

[0113] Next, the dispersion (A1) of the PMMA resin particles was added to the emulsion so that the amount of PMMA resin particles was 6.4 parts. After swelling this mixture at 50 °C for 1 hour, water in which partially saponified polyvinyl alcohol was dissolved (a total of 40 parts of dispersion stabilizer and water) was added, and the reaction was carried out at 73 °C for 1.5 hours and then at 90 °C for 1.5 hours, and then cooled to obtain a dispersion (A2) of monodisperse seed particles with an average particle diameter of 1.0 μm and a CV value of 3.5%.

[0114] (Third-stage polymerization: Production of (meth)acrylic resin particles) Into a flask with a capacity of 1 liter, 66.3 parts of methyl methacrylate, 30 parts of glycidyl methacrylate (GMA), and 1.0 part of benzoyl peroxide as an initiator were added and dissolved to obtain a solution. 0.5 part of sodium dodecylbenzenesulfonate and 200 parts of ion-exchanged water were added to the solution, and the mixture was emulsified with a homomixer to obtain an emulsion.

[0115] Next, to the emulsion, the dispersion (A2) of the monodisperse seed particles was added so that the amount of the seed particles was 3.7 parts. After swelling this mixture at 50 °C for 1 hour, water in which partially saponified polyvinyl alcohol was dissolved (a total of 40 parts of the dispersion stabilizer and water) was added, and the mixture was reacted at 73 °C for 1.5 hours and at 90 °C for 1.5 hours, and then cooled to obtain a dispersion (A3) of (meth)acrylic resin particles having an average particle diameter of 2.8 μm and a CV value of 5.2%.

[0116] <Step (2)> (Contact of imidazole-based compound and ring-opening polymerization of cyclic ether moieties) To the dispersion (A3) obtained above, 1 part of 2-ethyl-4-methylimidazole (hereinafter also referred to as "2E4MZ") which serves as an epoxy polymerization catalyst was added with respect to 100 parts by mass of the particle solid content to bring the imidazole-based compound into contact with the mother particles. Then, by heating at 180 °C for 1 hour, a dispersion (A4) containing a (meth)acrylic resin having a structure in which the cyclic ether moieties of the (meth)acrylic resin particles are ring-opening polymerized was obtained.

[0117] <Step (3)> (Powderization) The dispersion (A4) was powdered by freeze-drying, and then the powder was further pulverized with a mortar and a jet mill to obtain polymer particles containing (meth)acrylic resin particles having a structure in which the cyclic ether moieties of the monodisperse seed particles are ring-opening polymerized.

[0118] [Examples 2 to 16, Comparative Examples 1 to 13] Polymer particles were obtained in the same manner as in Example 1 except that the types and amounts of each component used were changed as described in Tables 1 and 2.

[0119] [Comparative Example 14] Since the boiling point of n-butylamine used as an amine curing agent is about 75°C, in the above <Step (2)>, n-butylamine was used instead of 2-ethyl-4-methylimidazole, and the heating temperature was set to 60°C. Otherwise, polymer particles were obtained in the same manner as in Example 1.

[0120]

Table 1

[0121]

Table 2

[0122] (Seed) ·PMMA: Polymethyl methacrylate (Radical polymerizable monomer) 〔(Meth)acrylate ester (A)〕 ·GMA: Glycidyl methacrylate (Light Acrylate G, manufactured by Kyoeisha Chemical Co., Ltd.) ·4HBAGE: 4-Hydroxybutyl acrylate glycidyl ether (manufactured by Mitsubishi Chemical Corporation) 〔Mono-functional monomer〕 ·MMA: Methyl methacrylate ·MAA: Methacrylic acid 〔Bifunctional monomer〕 ·EGDMA: Ethylene glycol dimethacrylate 〔Trifunctional monomer〕 ·TMPTA: Trimethylolpropane triacrylate (Biscote #295, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 〔Tetrafunctional monomer〕 ·PETA: Pentaerythritol tetraacrylate (M-305, manufactured by Toagosei Co., Ltd.) (Post-added catalyst for ring-opening polymerization of cyclic ether) ·DBU: 1,8-Diazabicyclo[5.4.0]undec-7-ene (manufactured by San-Apro Ltd., molecular weight = 152.24) ·SP-003: Polyethyleneimine (mixed primary, secondary, and tertiary amines (amine ratio: primary 45% secondary 35%, tertiary 20%), Epomin SP-003, manufactured by Nippon Shokubai Co., Ltd., number average molecular weight = 300) ·2PZ-PW: 2-Phenyl-1H-imidazole (Curezol 2PZ-PW, manufactured by Shikoku Kasei Kogyo Co., Ltd., molecular weight = 144.17) ·2MZA-PW: 2,4-Diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine (Curezol 2MZA-PW, manufactured by Shikoku Kasei Kogyo Co., Ltd., molecular weight = 219.25) ·jER Cure IBM12: 1-Isobutyl-2-methylimidazole (jER Cure IBM12, manufactured by Mitsubishi Chemical Corporation, molecular weight = 138.21) ·2E4MZ: 2-Ethyl-4-methylimidazole (molecular weight = 110.16) (amine-based curing agent) ·jER Cure 113: 4,4'-Methylenebis(2-methylcyclohexylamine) (jER Cure 113, manufactured by Mitsubishi Chemical Corporation) ·Nissan Amine M-14: 1-Amino-3-undecanoxy-propane (Nissan Amine M-14, manufactured by NOF Corporation) ·Butylamine: n-Butylamine In the columns of "Crosslinking Types of Polymer Particles" in Table 1 and Table 2, "non-crosslinked" means polymer particles composed only of monofunctional monomers containing (meth)acrylate (A), and "crosslinked" means polymer particles composed of monofunctional monomers containing (meth)acrylate (A) and polymerizable monomers (B) including polyfunctional monomers as the polymerizable monomers.

[0123] In the column of "post-added catalyst for ring-opening polymerization of cyclic ether" in Table 1, "H" means active hydrogen in the imidazole-based compound. In the case of "H×0", it means that there is no active hydrogen in the imidazole-based compound, and in the case of "H×1", it means that there is one active hydrogen in the imidazole-based compound.

[0124] In the columns of "post-added catalyst for ring-opening polymerization of cyclic ether" and "amine-based curing agent" in Table 1 and Table 2, "NH2" means the primary amino group in the imidazole-based compound or amine-based curing agent used in the examples and comparative examples. For example, in the case of "NH2×1", it means that there is one primary amino group in the imidazole-based compound or amine-based curing agent.

[0125] As shown in Table 1, the polymer particles in each example had high hardness and excellent monodispersity. In Example 11, the reason why the breaking point is "none" is considered to be that by using a post-added catalyst which is an amino compound containing a mixture of primary to tertiary amino groups, the addition reaction of the epoxy group by the highly reactive primary and secondary amino groups to the epoxy group proceeded only near the surface of the polymer particles, so that the uncrosslinked polymer inside the particles remained as an uncrosslinked polymer without the ring-opening polymerization of the epoxy groups proceeding.

[0126] In Comparative Examples 9 to 11, the reason why the breaking point is "present" is considered to be that a three-dimensional network polymer having a network structure is formed by using a large amount of bifunctional or higher monomers.

[0127] In Comparative Example 12, IR (910 cm -1) is considered to be "remaining" because although the addition reaction of a primary amine to the epoxy group proceeds preferentially, the tertiary amine generated by the addition of an amino compound having a primary amino group has difficulty having a catalytic reaction due to steric hindrance, and thus some epoxy groups remain without reacting. Also, the addition amount of the amino compound having a primary amino group in Comparative Example 12 is 0.04 equivalent relative to the epoxy group of GMA, which is less than the addition amount in the case of an addition reaction with an epoxy group using a normal amine-based curing agent (for example, the molar ratio of the cyclic ether structure in the mother particle to the amine-based curing agent is usually about 0.5 to 5), so it is considered that some unreacted epoxy groups remain. Furthermore, for the reasons described above, since the polymer particles of Comparative Example 12 do not have a structure formed by ring-opening polymerization of ether sites in GMA, the 10% K value is considered to be low.

[0128] Nissan Amine M-14, an amine-based curing agent used in Comparative Example 13, is a compound having a primary amino group. n-Butylamine, an amine-based curing agent used in Comparative Example 14, is a compound having a low molecular weight primary amino group. Also in Comparative Examples 13 and 14, similar to Comparative Example 12, the tertiary amine generated by the addition of a compound having a primary amino group does not have a catalytic function for promoting the ring-opening polymerization of epoxy groups, so it is considered that it did not contribute to the hardening of the polymer particles.

Claims

1. It is obtained by polymerizing a (meth)acrylic acid ester (A) having a cyclic ether structure, and contains a (meth)acrylic resin having a structure formed by ring-opening polymerization of cyclic ether moieties in the cyclic ether structure. Polymer particles used for conductive particles of an anisotropic conductive adhesive.

2. The polymer particles according to claim 1, wherein the (meth)acrylic resin further contains a structure derived from a polymerizable monomer (B) other than the (meth)acrylic acid ester (A) having the cyclic ether structure.

3. The polymer particles according to claim 2, wherein the polymerizable monomer (B) is at least one compound selected from the group consisting of monomers having 1 to 4 (meth)acryloyl groups in one molecule.

4. The polymer particles according to claim 1, wherein the (meth)acrylic acid ester (A) having the cyclic ether structure is a compound represented by the following formula (1). 【Chemical 1】 [In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, x represents an integer of 1 to 6, Y represents a single bond or -O-CH 2 -, and z represents an integer of 0 to 2.]

5. The polymer particles according to claim 1, which contain a (meth)acrylic resin obtained by polymerizing the (meth)acrylic acid ester (A) having the cyclic ether structure and having a structure in which an imidazole-based compound is added to a site where a part of the cyclic ether structure is ring-opened.

6. In the polymer particles, the 10% K value is 3,000 to 7,000 N / mm 2 The polymer particles according to claim 1, wherein the 10% K value is 3,000 to 7,000 N / mm

7. A method for producing the polymer particles according to any one of claims 1 to 6, comprising: Step (1) of radical polymerizing a polymerizable monomer component containing a (meth)acrylic acid ester (A) having a cyclic ether structure to obtain mother particles containing a (meth)acrylic resin; Step (2) of bringing the mother particles into contact with an imidazole-based compound and / or an amino compound having a tertiary amino group to cause ring-opening polymerization of the cyclic ether moieties in the cyclic ether structure to obtain polymer particles containing a (meth)acrylic resin having a structure formed by ring-opening polymerization of the cyclic ether moieties; and Step (3) of pulverizing the polymer particles, the method for producing polymer particles.

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