(METH)acrylic copolymer, epoxy resin composition, adhesive, cured product, molding material and fiber reinforced plastics

Abstract

To provide a (meth)acrylic copolymer which is a block copolymer or a graft copolymer and is capable of obtaining a cured product with high adhesive strength, an epoxy resin composition comprising the (meth)acrylic copolymer, its cured product, its adhesive, its molding material and its fiber reinforced plastics.SOLUTION: There is provided a (meth)acrylic copolymer (A) which is a block copolymer or a graft copolymer and has a structural unit derived from a radical-polymerizable monomer (a1) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms and a structural unit derived from a (meth)acrylate (a2) having a cyclic ether group. In addition, there is provided an epoxy resin composition comprising the (meth)acrylic graft copolymer (A), an epoxy resin (B) and a curing agent (C).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a (meth)acrylic copolymer, an epoxy resin composition, an adhesive, a cured product, a molding material, and a fiber-reinforced plastic. [Background technology]

[0002] Epoxy resins have excellent rigidity, heat resistance, electrical properties, durability, etc., and are therefore used in adhesives and molding materials for vehicle structures, civil engineering and construction, electronic material adhesives, industrial adhesives, fiber-reinforced plastics, etc. However, epoxy resins are generally known to be brittle, and studies are being conducted to improve adhesive strength and impact strength by improving their toughness.

[0003] For example, Patent Document 1 discloses that a cured product having excellent adhesive strength and impact strength can be obtained from an epoxy resin composition containing an epoxy resin and a (meth)acrylic polymer having structural units derived from a macromonomer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 049951 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a (meth)acrylic copolymer that is a block copolymer or a graft copolymer that can give a cured product having high adhesive strength, an epoxy resin composition containing the (meth)acrylic copolymer, an adhesive, a cured product, a molding material, and a fiber-reinforced plastic obtained therefrom. Another object of the present invention is to provide a (meth)acrylic copolymer that is a block copolymer or a graft copolymer that can give a cured product having high impact strength, an epoxy resin composition containing the (meth)acrylic copolymer, an adhesive, a cured product, a molding material, and a fiber-reinforced plastic obtained therefrom. [Means for solving the problem]

[0006] The present invention includes the following configurations. [1] A (meth)acrylic copolymer which is a block copolymer or a graft copolymer, comprising a structural unit derived from a radically polymerizable monomer (a1) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and a structural unit derived from a (meth)acrylate (a2) having a cyclic ether group. [2] The (meth)acrylic copolymer according to [1], wherein the radical polymerizable monomer (a1) is a (meth)acrylate represented by the following formula (1): [ka] (In formula (1), R 1 is a hydrogen atom or a methyl group, R 2 ~R 4 each independently represents a hydrogen atom or a hydroxyl group, and x represents an integer of 0 to 3. [3] The (meth)acrylic copolymer according to [1] or [2], which has a main chain polymer structure and a side chain polymer structure, and the side chain polymer structure contains a structural unit derived from the (meth)acrylate (a2) having a cyclic ether group. [4] The (meth)acrylic copolymer according to any one of [1] to [3], which contains a structural unit derived from a macromonomer (M) and a structural unit derived from a vinyl radically polymerizable monomer (m1). [5] The (meth)acrylic copolymer according to [4], wherein the macromonomer (M) contains a structural unit derived from a vinyl radically polymerizable monomer (m2). [6] The (meth)acrylic copolymer according to [5], wherein the macromonomer (M) contains a structure represented by the following formula (2): [ka] (In formula (2), X 1 ~X n-1 are each independently H, CH3, or CH2OH, and Y 1 ~Y n are each independently a substituent bonded to a vinyl group of the vinyl radical polymerizable monomer (m2), Z is a terminal group, and n is an integer of 2 to 10,000. [7] An epoxy resin composition comprising the (meth)acrylic copolymer according to any one of [1] to [6], an epoxy resin (B), and a curing agent (C). [8] The epoxy resin composition according to [7], further comprising a polymer (D) having a core-shell structure. [9] An adhesive containing the epoxy resin composition according to [7] or [8].

[10] A cured product of the epoxy resin composition according to [7] or [8].

[11] A molding material comprising the cured product according to

[10] .

[12] A fiber-reinforced plastic comprising the cured product according to

[10] . [Effects of the Invention]

[0007] The present invention provides a (meth)acrylic copolymer that is a block copolymer or a graft copolymer that can give a cured product having high adhesive strength, an epoxy resin composition containing the (meth)acrylic copolymer, an adhesive, a cured product, a molding material, and a fiber-reinforced plastic thereof.The present invention also provides a (meth)acrylic copolymer that is a block copolymer or a graft copolymer that can give a cured product having high impact strength, an epoxy resin composition containing the (meth)acrylic copolymer, an adhesive, a cured product, a molding material, and a fiber-reinforced plastic thereof. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to these embodiments. The present invention can be implemented in various forms without departing from the spirit of the present invention.

[0009] In the present invention, "(meth)acrylic" is a general term for "acrylic" and "methacrylic." "(Meth)acrylate" is a general term for "acrylate" and "methacrylate." "(Meth)acryloyl group" is a general term for "acryloyl group" and "methacryloyl group," and is a group represented by CH2=C(R)-C(=O)- (R is a hydrogen atom or a methyl group). "Macromonomer" means a high molecular weight compound having a radically polymerizable group or an addition-reactive functional group. The number average molecular weight (Mn) is usually 1,000 to 1,000,000. "Radically polymerizable monomer" means a monomer having an ethylenically unsaturated bond that is not a macromonomer.

[0010] [Epoxy resin composition] The epoxy resin composition of the present invention contains a (meth)acrylic copolymer (A) (hereinafter also referred to as "component (A)"), an epoxy resin (B) (hereinafter also referred to as "component (B)"), and a curing agent (C) (hereinafter also referred to as "component (C)"). The epoxy resin composition of the present invention may further contain a polymer (D) having a core-shell structure (hereinafter also referred to as "component (D)"). Furthermore, the epoxy resin composition of the present invention may contain components other than components (A) to (D) (hereinafter also referred to as "optional components"), as necessary, within the scope of not impairing the effects of the present invention.

[0011] <Component (A)> The (meth)acrylic copolymer (A) contains a structural unit (hereinafter also referred to as "structural unit (a1)") derived from a radically polymerizable monomer (a1) (hereinafter also referred to as "component (a1)") having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and a structural unit (hereinafter also referred to as "structural unit (a2)") derived from a (meth)acrylate (a2) (hereinafter also referred to as "component (a2)") having a cyclic ether group. The (meth)acrylic copolymer (A) has a main chain polymer structure and a side chain polymer structure, and it is preferable that the side chain polymer structure contains the structural unit (a2).

[0012] From the viewpoint of improving the solubility of component (A) in component (B) and of improving the adhesive strength and impact resistance of the cured product, it is preferable that component (A) contain 0.1% by mass or more of the structural unit (a1) relative to 100% by mass of the total amount of component (A). The content of the structural units derived from the component (a1) in the component (A) is more preferably 0.2 to 20 mass%, even more preferably 0.5 to 10 mass%, and particularly preferably 1 to 5 mass%, relative to 100 mass% of the total mass of the component (A). The component (A) may be used alone or in combination of two or more.

[0013] The component (a1) is a radical polymerizable monomer having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms. The component (a1) is preferably a (meth)acrylate represented by the following formula (1):

[0014] [ka] (In the formula, R 1 is a hydrogen atom or a methyl group, R 2 ~R 4 each independently represents a hydrogen atom or a hydroxyl group, and x represents an integer of 0 to 3.

[0015] Examples of the component (a1) include glycerin monoacrylate (in formula (1), R 1 is a hydrogen atom, R 2 ~R 4 is a hydrogen atom and x is 1), glycerin monomethacrylate (a compound in which R 1 is a methyl group, R 2 ~R 4 is a hydrogen atom and x is 1). The component (a1) may be used alone or in combination of two or more.

[0016] The component (a2) is a (meth)acrylate having a cyclic ether group. The cyclic ether group is preferably a 3- to 6-membered ring, more preferably a 3- to 5-membered ring. Examples of the (meth)acrylate (a2) having a cyclic ether group include tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, (meth)acrylateoylmorpholine, (3,4-epoxycyclohexyl)methyl (meth)acrylate, β-methylglycidyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)(meth)acrylate, (5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, and (2-oxo-1,3-dioxolan-4-yl)methyl (meth)acrylate. The component (a2) may be used alone or in combination of two or more.

[0017] As component (a2), glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, (3,4-epoxycyclohexyl)methyl (meth)acrylate, β-methylglycidyl (meth)acrylate, and (2-oxo-1,3-dioxolan-4-yl)methyl (meth)acrylate are more preferred, and glycidyl (meth)acrylate is even more preferred, because they can react with curing agent (C) to improve adhesive strength and impact resistance in particular.

[0018] In order to obtain good adhesive strength and impact resistance of the cured product, the content of the structural unit (a2) in the component (A) is preferably 1 to 50 mass%, more preferably 2 to 40 mass%, and even more preferably 3 to 30 mass%, relative to 100 mass% of the total mass of the component (A).

[0019] Component (A) is a block copolymer or a graft copolymer. A graft copolymer is preferable from the viewpoint of ease of blending with component (B). A "graft copolymer" is a polymer having one or more types of blocks chemically bonded as side chain polymer structures (branch polymer structures) to a main chain polymer structure (trunk polymer structure). The structures of the main chain polymer and the side chain polymer may be different or the same. The method for producing the graft copolymer is not particularly limited, and examples thereof include a method in which a macromonomer having a radically polymerizable double bond at its terminal is produced as a side chain polymer structure, and then radically polymerized with a monomer that will become a structural unit of the main chain polymer; a method in which a main chain polymer having a reactive site and a macromonomer having a reactive site are produced in advance, and then the main chain polymer is reacted with each other; and a method in which, after the main chain polymer is produced, an initiator having hydrogen abstraction ability is used to generate radicals on the main chain polymer, and then a monomer that will become a structural unit of the side chain polymer is reacted to produce a side chain polymer structure.

[0020] When the component (A) is a graft copolymer, there are no particular limitations on the copolymer, so long as it has a branched structure in which a side chain polymer is bonded to a main chain polymer. Preferably, the copolymer contains a structural unit derived from a vinyl radically polymerizable monomer (m1) (hereinafter also referred to as "component (m1)") and a structural unit derived from a macromonomer (M) (hereinafter also referred to as "component (M)") (hereinafter also referred to as "structural unit (M)"). Examples of the (m1) component include the (a1) to (a2) components, as well as monofunctional (meth)acrylates, polyfunctional (meth)acrylates, and other vinyl compounds (hereinafter also referred to as "other vinyl compounds").

[0021] Specific examples of monofunctional (meth)acrylates include (meth)acrylic acid, (meth)acrylates containing a carboxyl group such as 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate; cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentene. (Meth)acrylates having a cycloalkyl group, such as dicyclopentenoxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, and 1,4-cyclohexanedimethanol monoacrylate; phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and phenoxypolyethylene glycol (meth)acrylate. (meth)acrylates having an aryl group such as acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, and (1-naphthyl)methyl (meth)acrylate; (meth)acrylates having an isocyanate group such as 2-isocyanatoethyl (meth)acrylate, 2-isocyanatopropyl (meth)acrylate, 3-isocyanatopropyl (meth)acrylate, 2-(2-(meth)acryloyloxyethyloxy)ethyl isocyanate, and 1,1-(bis(meth)acryloyloxymethyl)ethyl isocyanate; (meth)acrylamides such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)acrylamide;Examples of the silane include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate. These monofunctional (meth)acrylates may be used alone or in combination of two or more.

[0022] Specific examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, polycarbonate diol di(meth)acrylate, polyester diol di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A dimeth ... Examples of the functional groups include difunctional (meth)acrylates such as propylene oxide adduct di(meth)acrylate, polyurethane di(meth)acrylate, and 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene; trifunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, and ε-caprolactone-modified tris((meth)acryloxyethyl)isocyanurate; tetrafunctional (meth)acrylates such as ditrimethylolpropane tetra(meth)acrylate; pentafunctional (meth)acrylates such as dipentaerythritol penta(meth)acrylate; and hexafunctional (meth)acrylates such as dipentaerythritol hexa(meth)acrylate. These polyfunctional (meth)acrylates may be used alone or in combination of two or more.

[0023] The other vinyl compounds are not particularly limited as long as they are copolymerizable with the monofunctional (meth)acrylate and the polyfunctional (meth)acrylate, and examples thereof include styrene or styrene derivatives such as styrene, α-methylstyrene, pt-butylstyrene, and vinyltoluene; unsaturated carboxylic acids such as itaconic acid, maleic acid, and fumaric acid; unsaturated nitriles such as (meth)acrylonitrile; unsaturated carboxylic acid esters such as diethyl maleate, dibutyl maleate, dibutyl fumarate, diethyl itaconate, and dibutyl itaconate; and vinyl esters such as vinyl acetate and vinyl propionate. The other vinyl compounds may be used alone or in combination of two or more.

[0024] As the (m1) component, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate are preferred, as the (m1) component, since they improve the solubility of the (A) component in the (B) component and can improve the adhesive strength and impact resistance of the cured product. Ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, methoxyethyl (meth)acrylate, and ethoxyethyl (meth)acrylate are more preferred.

[0025] The macromonomer (M) is a high molecular weight compound having a radical polymerizable group or an addition-reactive functional group, and its number average molecular weight (Mn) is usually 1,000 to 100,000.

[0026] The component (M) is not particularly limited as long as it is a high molecular weight compound having a radically polymerizable group or an addition-reactive functional group, but from the viewpoint of a high degree of designability with respect to the solubility of the component (A) in the component (B), a compound containing a structural unit derived from a vinyl radically polymerizable monomer (m2) (hereinafter also referred to as "component (m2)") is preferred, and a compound containing two or more structural units derived from the component (m2) and having a radically polymerizable group at its terminal is more preferred. The component (M) may be used alone or in combination of two or more.

[0027] As the component (m2), the compounds listed above as the component (m1) can be used.

[0028] From the viewpoint of the solubility of the component (A) in the component (B), the component (m2) preferably contains the component (a1), and glycerin mono(meth)acrylate is more preferred.

[0029] From the viewpoint of the solubility of the component (A) in the component (B), it is preferable that the component (m2) contains the component (a2), and glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, (3,4-epoxycyclohexyl)methyl (meth)acrylate, β-methylglycidyl (meth)acrylate, and (2-oxo-1,3-dioxolan-4-yl)methyl (meth)acrylate are more preferable, and glycidyl (meth)acrylate is even more preferable.

[0030] The component (M) preferably has a structure represented by the following formula (2) because it has excellent radical polymerizability with the component (m1).

[0031] [ka]

[0032] In formula (2), X 1 ~X n-1 are each independently H, CH3, or CH2OH, and Y 1 ~Yn are each independently a substituent bonded to a vinyl group of the vinyl radical polymerizable monomer (m2), Z is a terminal group, and n is an integer of 2 to 10,000. In addition, "-···-" in formula (2) represents a state in which structural units derived from a monomer are polymerized.

[0033] X 1 ~X n-1 is preferably a methyl group, and from the viewpoint of ease of synthesis, it is preferable that at least half of the groups are methyl groups. Y 1 ~Y n are each independently an X bonded to a vinyl group of the vinyl radical polymerizable monomer (m2). 1 ~X n-1 Examples of such substituents include OR 6 , halogen atoms, COR 7 , COOR 8 ,CN,CONR 9 R 10 , NHCOR 11 , or R 12 etc. In addition, R 6 ~R 12 are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, a cyclic ether group, an aryl group, a heteroaryl group, or the like. Z is a terminal group. The terminal group may be a hydrogen atom or a group derived from a radical polymerization initiator, similar to the terminal groups of polymers obtained by known radical polymerization. n represents the number of monomer units in one molecule of the macromonomer (M), and is an integer of 2 to 10,000, preferably an integer of 5 to 1,000, and more preferably an integer of 10 to 500.

[0034] The number average molecular weight (Mn) of the component (M) is preferably from 1,000 to 30,000, more preferably from 1,000 to 20,000, and even more preferably from 1,000 to 10,000. When the number average molecular weight of the component (M) is within the above range, the solubility of the component (A) in the component (B) is improved. The mass average molecular weight (Mw) of the component (M) is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and even more preferably 1,000 to 30,000. When the mass average molecular weight of the component (M) is within the above range, the solubility of the component (A) in the component (B) is improved. The Mw / Mn of the component (M) is preferably from 1 to 5, and more preferably from 1.5 to 3. When the Mw / Mn of the component (M) is within the above range, the solubility of the component (A) in the component (B) becomes better. The number average molecular weight (Mn) and weight average molecular weight (Mw) of the component (M) are values ​​measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0035] The component (M) may be one produced by a known method or a commercially available product. Examples of methods for producing the component (M) include a method using a cobalt chain transfer agent (U.S. Pat. No. 4,680,352, etc.), a method using an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent (WO 1988 / 04304), a method of chemically bonding a polymerizable group (JP-A No. 60-133007 and U.S. Pat. No. 5,147,952, etc.), and a method using thermal decomposition (JP-A No. 11-240854, etc.). The preferred method for producing component (M) is to use a cobalt chain transfer agent, which requires fewer production steps and uses a catalyst with a high chain transfer constant. Because the cobalt chain transfer agent has a high chain transfer constant, adding a small amount of the agent allows the production of component (M) with a controlled molecular weight.

[0036] As the cobalt chain transfer agent, known cobalt complexes can be used. The amount of the cobalt chain transfer agent used is preferably 0.00001 to 0.1 parts by mass, more preferably 0.00005 to 0.05 parts by mass, and even more preferably 0.0001 to 0.02 parts by mass, per 100 parts by mass of the component (m2).

[0037] The component (A) and the macromonomer (M) can be produced by known methods such as solution polymerization, suspension polymerization, emulsion polymerization, and redox polymerization.

[0038] From the viewpoint of improving the solubility of component (A) in component (B) and improving the adhesive strength and impact resistance of the cured product, the content of structural unit (M) in component (A) is preferably 0 to 60 mass%, more preferably 1 to 50 mass%, and even more preferably 5 to 40 mass%, relative to 100 mass% of the total amount of component (A).

[0039] The mass average molecular weight (Mw) of component (A) is preferably 10,000 to 1,000,000, more preferably 20,000 to 800,000, and even more preferably 30,000 to 600,000. When the mass average molecular weight of component (A) is within the above range, the solubility of component (A) in component (B) becomes better. The number average molecular weight (Mn) of component (A) is preferably 3,000 to 300,000, more preferably 50,000 to 200,000, and even more preferably 10,000 to 100,000. When the number average molecular weight of component (A) is within the above range, the solubility of component (A) in component (B) is improved. The Mw / Mn of component (A) is preferably from 1 to 20, and more preferably from 1.5 to 15. When the Mw / Mn of component (A) is within the above range, the solubility of component (A) in component (B) becomes better. The number average molecular weight (Mn) and weight average molecular weight (Mw) of component (A) are values ​​measured by gel permeation chromatography (GPC) and converted into polystyrene equivalents.

[0040] <(B) component> Component (B) is an epoxy resin. Examples of component (B) include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol E type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, dicyclopentadiene type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins, and glycidylamine type epoxy resins. Examples of component (B) include prepolymers of the above-mentioned epoxy resins, copolymers of the above-mentioned epoxy resins with other polymers, such as polyether-modified epoxy resins and silicone-modified epoxy resins, and epoxy resins in which a portion of the above-mentioned epoxy resins has been substituted with a reactive diluent having an epoxy group.

[0041] Examples of reactive diluents include monoglycidyl compounds such as resorcinol glycidyl ether, t-butylphenyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 1-(3-glycidoxypropyl)-1,1,3,3,3-pentamethylsiloxane, and N-glycidyl-N,N-bis[3-(trimethoxysilyl)propyl]amine; and monoalicyclic epoxy compounds such as 2-(3,4)-epoxycyclohexyl)ethyltrimethoxysilane. These reactive diluents may be used alone or in combination of two or more.

[0042] Bisphenol A epoxy resins and bisphenol F epoxy resins are preferred as component (B) because they are liquid and easy to handle, and because they have high glass transition points and thus increase the adhesive strength of the cured product. These components (B) may be used alone or in combination of two or more.

[0043] <(C) component> Component (C) is a component that cures component (B) and is used to adjust the curability of the epoxy resin composition and the properties of the cured product. As the component (C), known compounds can be used, such as acid anhydrides, amine compounds, phenolic compounds, and latent curing agents.

[0044] Specific examples of component (C) include acid anhydrides such as phthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methylhimic anhydride, methylcyclohexene dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, dodecenyl succinic anhydride, polyazelaic anhydride, and poly(ethyloctadecanedioic) anhydride;2,5(2,6)-bis(aminomethyl)bicyclo[2,2,1]heptane, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, bis(4-amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, bis(4-aminocyclohexyl)methane, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane, diethyltoluenediamine, diaminodiphenylsulfones such as 3,3'-diaminodiphenylsulfone (3,3'-DDS) and 4,4'-diaminodiphenylsulfone (4,4'-DDS), diaminodiphenylether (DADPE), bisaniline, dimethylaniline, triethylenediamine, dimethylbenzylamine, 2,4,6-tris(dimethylaminomethyl)phenyl amine compounds such as phenol, benzyldimethylaniline, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4,4'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, 2,3-tolylenediamine, 2,4-tolylenediamine, 2,5-tolylenediamine, 2,6-tolylenediamine, 3,4-tolylenediamine, methylthiotoluenediamine, diethyltoluenediamine, and dicyandiamide; phenolic compounds such as phenol novolac resin, cresol novolac resin, bisphenol A, bisphenol F, bisphenol AD, and diallylated derivatives of these bisphenols;Carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, iminodiacetic acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecane dihydrazide, hexadecanedihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diglycol Examples of hydrazide compounds include citric acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4'-bisbenzenedihydrazide, 1,4-naphthoic acid dihydrazide, Amicure VDH, Amicure UDH (all trade names, manufactured by Ajinomoto Co., Inc.), and citric acid trihydrazide; Among these, amine compounds and hydrazide compounds are preferred as component (C) from the viewpoint of improving the storage stability of the epoxy resin composition, and dicyandiamide and hydrazide compounds are more preferred. These components (C) may be used alone or in combination of two or more.

[0045] <(D) component> Component (D) is a polymer with a core-shell structure. Addition of component (D) can further increase the adhesive strength and impact strength of the cured product. The structure of component (D) preferably has a core layer made of at least one material selected from the group consisting of diene-based rubber polymers, acrylic-based rubber polymers, and organosiloxane-based rubber polymers, and a shell layer made of a vinyl-based polymer.

[0046] An example of the diene rubber polymer is a copolymer made of 1,3-butadiene, a vinyl monomer copolymerizable therewith, and a crosslinkable monomer used as needed. For ease of blending with component (B), component (D) is preferably handled as an "epoxy dispersion of component (D)" obtained by removing water and emulsifier from latex and replacing with epoxy resin.

[0047] A commercially available product may be used as the epoxy dispersion liquid of component (D). Examples of commercially available products include the "Kane Ace MX Series" manufactured by Kaneka Corporation. "Kane Ace MX154," an example of the "Kane Ace MX Series," is a dispersion liquid in which a polymer component (approximately 40% by mass) with a core layer of polybutadiene and a shell layer of a vinyl polymer is dispersed as single particles in a bisphenol A-type epoxy resin (approximately 60% by mass).

[0048] <Optional ingredients> Optional components include, for example, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2-methylimidazole, 2-ethyl-4-methylimidazole, adducts of imidazole compounds and epoxy resins, curing accelerators such as triphenylphosphine, tetraphenylphosphine tetraphenylborate, and diazabicycloundecene (DBU); 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol, n-octadecyl-3-(3',5'- Di-t-butyl-4'-hydroxyphenyl)propionate, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethyl phosphite, tri(2-ethylhexyl)phosphite , tridecyl phosphite, triphenyl phosphite, trisisodecyl phosphite, tristridecyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, dihexyl sulfide, dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearic-3,3'-thiodipropionate, pentaerythritol tetrakis(β-laurylthiopropionate) release agents such as silicone oil, natural wax, synthetic wax; fillers such as glass beads, crystalline silica, fused silica, calcium silicate, alumina, calcium carbonate; fibers such as glass fiber, carbon fiber, alumina fiber, cellulose nanofiber; flame retardants such as antimony trioxide; halogen trapping agents such as hydrotalcite and rare earth oxides; colorants such as carbon black and red iron oxide; silane coupling agents; antifoaming agents; rheology modifiers: pigments; dyes, etc. These optional components may be used alone or in combination of two or more.

[0049] <Content> When the total mass of the components (A) to (D) is taken as 100 mass %, the preferred content of each component in the epoxy resin composition is as follows: The content of component (A) is preferably 1 to 60 mass%, more preferably 5 to 55 mass%, and even more preferably 10 to 50 mass%, because this allows the epoxy resin composition to have a low viscosity that provides good workability, while also increasing the toughness and adhesive strength of the cured product. The content of component (B) is preferably 20 to 90 mass %, more preferably 30 to 80 mass %, and even more preferably 40 to 70 mass %, because this allows the epoxy resin composition to have a low viscosity and good workability. The content of component (C) is preferably 0.1 to 10 mass%, more preferably 0.5 to 9 mass%, and even more preferably 1 to 8 mass%, because this provides sufficient curability to obtain a cured product while improving the storage stability of the epoxy resin composition. The content of component (D) is preferably 0 to 40% by mass, more preferably 1 to 35% by mass, and even more preferably 3 to 30% by mass, because this allows the epoxy resin composition to have a low viscosity that provides good workability, while further increasing the toughness and adhesive strength of the cured product.

[0050] <Manufacturing method> The method for producing the epoxy resin composition is not particularly limited, and known methods can be used. For example, the components (A), (B), and (C), and optionally the component (D), and any optional components, may be mixed simultaneously, or some of the components (e.g., the components (A) and (B)) may be mixed in advance, and the mixture may then be mixed with the remaining components. The mixing method is not particularly limited, and known mixers such as a planetary centrifugal mixer, a three-roll mill, a kneader, etc. can be used.

[0051] <Action and effect> The epoxy resin composition of the present invention described above contains the above-mentioned components (A), (B), and (C), and optionally the component (D), and optional components, and therefore can provide a cured product with high adhesive strength. Furthermore, the epoxy resin composition of the present invention contains the above-mentioned components (A), (B), and (C), and optionally the component (D), and optional components, and therefore can provide a cured product with high impact strength.

[0052] <Application> The epoxy resin composition of the present invention is useful as an adhesive since it can give a cured product having high adhesive strength. In addition, the epoxy resin composition of the present invention is useful as a molding material and a fiber-reinforced plastic since it can give a cured product having high adhesive strength and high impact strength. The applications of the epoxy resin composition of the present invention are not limited to those described above. The epoxy resin composition of the present invention can also be used for other applications, such as various applications in which thermosetting resins such as epoxy resins are used. Examples of such applications include paints, coating agents, insulating materials, and sealants. The adhesive, molding material, and fiber-reinforced plastic containing the epoxy resin composition of the present invention will be described below.

[0053] [glue] The adhesive of the present invention contains the above-mentioned epoxy resin composition of the present invention. Examples of adhesives include adhesives for vehicles including structural adhesives for automobiles, etc., adhesives for civil engineering and construction, adhesives for electronic materials, adhesives for general office use, adhesives for medical instruments, and industrial adhesives. Examples of adhesives for vehicles include hemming adhesives, weld bond adhesives, mastic adhesives, direct glazing adhesives, spot sealers, body sealers, and undercoats. Examples of adhesives for electronic materials include interlayer adhesives for multilayer substrates such as build-up substrates, die bonding agents, adhesives for semiconductors such as underfills, underfills for reinforcing BGAs, and mounting adhesives such as anisotropic conductive films (ACFs) and anisotropic conductive pastes (ACPs). These adhesive applications require high adhesive strength and impact strength.

[0054] [Cured product] The cured product of the present invention is obtained by curing the above-described epoxy resin composition of the present invention. The method for curing the epoxy resin composition is not particularly limited, and any known method can be used, such as a thermal curing method. When the epoxy resin composition is cured by a heat curing method, the optimal conditions vary depending on the type and amount of component (C) contained in the epoxy resin composition, but it is preferable to cure the epoxy resin composition under heating conditions of, for example, 50 to 250°C for about 0.1 to 10 hours.

[0055] [Molding material] The molding material of the present invention contains the cured product of the above-mentioned epoxy resin composition of the present invention. Examples of molding materials include sheets and films obtained by curing the epoxy resin composition of the present invention. Examples of molding methods include transfer molding and cast molding. Examples of applications of the molding materials include aircraft parts, automobile parts, sporting goods, building materials, electronic circuit boards, semiconductor encapsulants, and reflectors for optical semiconductors. These molding materials are required to have high impact strength.

[0056] [Fiber reinforced plastic] The fiber reinforced plastics (FRP) of the present invention are produced by curing a prepreg in which fibers such as glass fibers or carbon fibers are impregnated with the epoxy resin composition of the present invention. Examples of applications of fiber reinforced plastics include aircraft parts, automobile parts, ship parts, sporting goods, building materials, wind power generation blades, gas tanks, robots, and electronic circuit boards. These fiber reinforced plastics are required to have high impact strength, and the epoxy resin composition used for impregnation is required to have high adhesive strength to the fibers. [Example]

[0057] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In each example below, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0058] [Measurement and evaluation methods] <Measurement of molecular weight of macromonomer (M)> The molecular weight of the component (M) was measured using a gel permeation chromatograph (GPC apparatus) (manufactured by Tosoh Corporation, product name "HLC-8320") as follows. The component (M) was dissolved in tetrahydrofuran (THF) to a concentration of 0.2% by mass to prepare a THF solution (1). 10 μL of the THF solution (1) was injected into a GPC system equipped with Tosoh columns (TSKgel SuperHZM-M (inner diameter 4.6 mm, length 15 cm) x 1, HZM-M (inner diameter 4.6 mm, length 15 cm) x 1, HZ-2000 (inner diameter 4.6 mm, length 15 cm) x 1, and TSKguardcolumn SuperHZ-L (inner diameter 4.6 mm, length 3.5 cm) x 1). Measurement was performed under the following conditions: flow rate: 0.35 mL / min, eluent: THF containing dibutylhydroxytoluene (BHT) as a stabilizer, column temperature: 40 °C, and the mass average molecular weight (Mw) and number average molecular weight (Mn) were calculated in terms of standard polystyrene.

[0059] <Measurement of Molecular Weight of (Meth)acrylic Copolymer (A)> The molecular weight of the (meth)acrylic copolymer (A) was measured using a gel permeation chromatograph (GPC apparatus) (manufactured by Tosoh Corporation, product name "HLC-8320") as follows. The (meth)acrylic copolymer (A) was dissolved in tetrahydrofuran (THF) to a concentration of 0.2% by mass to prepare a THF solution (2). 10 μL of the above THF solution (2) was injected into a GPC apparatus equipped with Tosoh columns (two TSKgel SuperHZM-H (internal diameter 6.0 mm, length 15 cm) and one TSKguardcolumn SuperHZ-H (internal diameter 4.6 mm, length 3.5 cm)), and measurement was performed under the conditions of a flow rate of 0.5 mL / min, an eluent: THF containing BHT as a stabilizer, and a column temperature: 40°C, and the mass average molecular weight (Mw) and number average molecular weight (Mn) were calculated in terms of standard polystyrene.

[0060] <Evaluation of adhesive strength> A 25mm wide x 150mm long x 0.5mm thick steel plate (manufactured by Engineering Test Services, product name "JIS G3141, SPCC-SD") was used. The area from one end of one side to 50mm along the length was designated as a gripping area, and the remaining area was coated with an epoxy resin composition. Another steel plate of the same size was attached to the epoxy resin composition-coated surface, fixed so that the thickness of the epoxy resin composition layer was constant, and heated at 180°C for 30 minutes to cure the epoxy resin composition, yielding a laminate. Any cured epoxy resin composition that protruded from the sides of the resulting laminate was scraped off, and the gripping areas of each of the two steel plates were bent 90° outward to obtain a T-shaped test specimen. Using a precision universal testing machine (Shimadzu Corporation, product name "Autograph AGX-10kNVD", load cell 1kN), the obtained test specimen was held at the top and bottom of the gripping portion and the peel strength was measured at 200 mm / min. The measurement was carried out at 23°C. The average value of the load excluding the first 25 mm and the last 25 mm was taken as the T-peel strength. The T-peel strength was measured for three test specimens and the average value was calculated to evaluate the adhesive strength. A higher T-peel strength indicates better adhesive strength. A higher T-peel strength indicates better toughness.

[0061] <Impact strength evaluation> Symmetric wedge test specimens were prepared in accordance with ISO 11343 and JIS K6865, and impact strength measurements were performed. Specifically, an epoxy resin composition was applied to 0.8 mm thick bent steel plates (JIS G3141, SPCC-SD, manufactured by Engineering Test Services Co., Ltd.), bonded together, and then heated at 180°C for 30 minutes to cure the epoxy resin. Using a Hydroshot HITS-T10 high-speed tensile tester (Shimadzu Corporation, 10 kN load cell), the symmetric wedge test specimens were driven into the test piece at a speed of 2 m / s, and the dynamic cleavage resistance was measured during the cleavage of a 20 mm wide, 30 mm long cured epoxy resin specimen. Measurements were performed at 23°C. The average dynamic cleavage resistance between the first 25% and last 10% of the travel distance was used to determine the impact strength. Higher impact strength indicates better toughness.

[0062] [Dispersant] <Synthesis Example 1: Synthesis of Dispersant (1)> A polymerization reactor equipped with a stirrer, condenser, thermometer, and nitrogen gas inlet tube was charged with 900 parts of deionized water, 60 parts of 2-sulfoethyl sodium methacrylate, 10 parts of potassium methacrylate, and 12 parts of methyl methacrylate (MMA). The contents were stirred and purged with nitrogen while the temperature was raised to 50°C. 0.08 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride was added as a polymerization initiator, and the temperature was further raised to 60°C. After the temperature was raised, MMA was continuously added dropwise at a rate of 0.24 parts / min for 75 minutes using a dropping pump. The reaction solution was maintained at 60°C for 6 hours and then cooled to room temperature to obtain a clear aqueous solution of dispersant (1) with a solids content of 10%.

[0063] [Chain transfer agent] <Synthesis Example 2: Synthesis of chain transfer agent (1)> In a synthesis apparatus equipped with a stirrer, 1.00 g of cobalt(II) acetate tetrahydrate, 1.93 g of diphenylglyoxime, and 80 mL of diethyl ether (previously deoxygenated by nitrogen bubbling) were placed under a nitrogen atmosphere and stirred at room temperature for 30 minutes. Next, 10 mL of boron trifluoride diethyl etherate was added and stirred for an additional 6 hours. The mixture was filtered, and the solid was washed with diethyl ether and dried in vacuo for 15 hours to obtain 2.12 g of chain transfer agent (1) as a reddish-brown solid.

[0064] <Production Example 1: Production of Macromonomer (M1)> A polymerization apparatus equipped with a stirrer, a condenser, a thermometer, and a nitrogen gas inlet tube was charged with 145 parts of deionized water, 0.1 parts of sodium sulfate, and 0.25 parts of dispersant (1) (solids content 10%) and stirred to form a uniform aqueous solution. 50 parts of methyl methacrylate as component (m2), 50 parts of glycidyl methacrylate as component (a2), 0.0040 parts of chain transfer agent (1), and 2 parts of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (NOF Corporation, trade name "Perocta O") as a polymerization initiator were added to form an aqueous suspension. Next, the inside of the polymerization reactor was purged with nitrogen, the temperature was raised to 80°C, and the reaction was carried out for 3.5 hours. To further increase the polymerization rate, the temperature was raised to 90°C and maintained at this temperature for 1 hour. The reaction solution was then cooled to 40°C to obtain an aqueous suspension containing the macromonomer. This aqueous suspension was filtered, and the residue remaining on the filter was washed with deionized water, dehydrated, and dried at 40°C for 16 hours to obtain macromonomer (M1). The molecular weight of the resulting macromonomer (M1) was measured, and the results are shown in Table 1.

[0065] <Production Example 2: Production of Macromonomer (M2)> A macromonomer (M2) was obtained in the same manner as in Production Example 1, except that the component (m2), component (a2), chain transfer agent (1), and polymerization initiator used were changed to those shown in Table 1. The molecular weight of the obtained macromonomer (M2) is shown in Table 1.

[0066] <Production Example 3: Production of Macromonomer (M3)> A four-neck flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 40 parts of ethyl acetate as the initial solvent. The external temperature was raised to 85°C while stirring under a nitrogen gas stream. After the external temperature reached 85°C and the internal temperature stabilized, a mixture consisting of 20 parts of ethyl acetate, 65 parts of methyl methacrylate as component (m2), 5 parts of glycerin monomethacrylate (NOF Corporation, trade name "Blemmer GLM-EX") as component (a1), 30 parts of glycidyl methacrylate as component (a2), 0.0020 parts of chain transfer agent (1), and 0.4 parts of AMBN (Otsuka Chemical Co., Ltd., trade name: "AMBN") as a polymerization initiator was added dropwise over 4 hours. After the dropwise addition was completed and the mixture was held for 1 hour, a mixture consisting of 0.3 parts of AMBN as a polymerization initiator and 20 parts of ethyl acetate was added over 30 minutes. After that, after holding for 2 hours, ethyl acetate was added so that the solid content (proportion of the amount of monomer charged in (amount of monomer + solvent charged)) became 50%, and then the mixture was cooled to room temperature to obtain an ethyl acetate solution of macromonomer (M3). The molecular weight of the resulting macromonomer (M3) was measured, and the results are shown in Table 1.

[0067] <Production Example 4: Production of Macromonomer (M4)> An ethyl acetate solution of macromonomer (M4) was obtained in the same manner as in Production Example 3, except that the components (m2), (a1), and (a2), chain transfer agent (1), and polymerization initiator used were changed to those shown in Table 1. The molecular weight of the obtained macromonomer is shown in Table 1.

[0068] [Table 1]

[0069] The abbreviations in Table 1 are as follows: MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester M"). GMA: Glycidyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester G"). GLM: Glycerin monomethacrylate (manufactured by NOF Corporation, product name "Blenmar GLM-EX"). Chain transfer agent (1): The chain transfer agent synthesized in Synthesis Example 2. Perocta O: 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name "Perocta O"). AMBN: 2,2'-azobis(2-methylbutyronitrile) (manufactured by Otsuka Chemical Co., Ltd., trade name "AMBN")

[0070] <Production Example 5: Production of (meth)acrylic copolymer (A-1)> A four-neck flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 55 parts of methyl ethyl ketone (MEK), 15 parts of isopropyl alcohol (IPA), and 20 parts of macromonomer (M1) as the initial solvent. The external temperature was raised to 85°C under nitrogen gas flow while stirring. After the external temperature reached 85°C and the internal temperature stabilized, a mixture consisting of 25 parts of MEK, 79 parts of ethyl acrylate as component (m1), 1 part of glycerin monomethacrylate as component (a1), and 0.13 parts of benzoyl peroxide (NOF Corporation, trade name: "Niper BMT-K40") as a polymerization initiator was added dropwise over 3 hours. After the addition was completed and the mixture was held for 1 hour, a mixture consisting of 0.5 parts of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (NOF Corporation, trade name: "Perocta O") as a polymerization initiator and 10 parts of MEK was added over 1 hour. After that, after holding for 2 hours, MEK was added so that the solid content (proportion of the amount of monomer charged in (amount of monomer + solvent charged)) became 50%, and then the mixture was cooled to room temperature to obtain a MEK solution of (meth)acrylic copolymer (A-1). The molecular weight of the resulting (meth)acrylic copolymer (A-1) was measured, and the results are shown in Table 2.

[0071] <Production Examples 6 to 9, 13 to 14, and 17: Production of (meth)acrylic copolymers (A-2) to (A-5), (A-9) to (A-10), and (A-13)> Solutions of (meth)acrylic copolymers (A-2) to (A-5), (A-9) to (A-10), and (A-13) were obtained in the same manner as in Production Example 5, except that the types and amounts of components (M), (m1), and (a1), and the initial solvent were changed to those shown in Table 2. The molecular weights of the resulting acrylic copolymers (A-2) to (A-5), (A-9) to (A-10), and (A-13) were measured. The results are shown in Table 2.

[0072] <Production Example 10: Production of (meth)acrylic copolymer (A-6)> A four-neck flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 35 parts of methyl ethyl ketone (MEK) as the initial solvent and 40 parts of an ethyl acetate solution of macromonomer (M3) (20 parts macromonomer (M3) and 20 parts ethyl acetate). The external temperature was raised to 85°C while stirring under a nitrogen gas stream. After the external temperature reached 85°C and the internal temperature stabilized, a mixture consisting of 25 parts of MEK, 80 parts of ethyl acrylate as component (m1), and 0.13 parts of benzoyl peroxide (NOF Corporation, trade name: "Niper BMT-K40") as a polymerization initiator was added dropwise over 3 hours. After the addition was completed and the mixture was held for 1 hour, a mixture consisting of 0.5 parts of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (NOF Corporation, trade name: "Perocta O") as a polymerization initiator and 10 parts of MEK was added over 1 hour. After that, after holding for 2 hours, MEK was added so that the solid content (proportion of the amount of monomer charged in (amount of monomer + solvent charged)) became 50%, and then the mixture was cooled to room temperature to obtain a MEK solution of (meth)acrylic copolymer (A-6). The molecular weight of the resulting (meth)acrylic copolymer (A-6) was measured, and the results are shown in Table 2.

[0073] <Production Examples 11 to 12, 15: Production of (meth)acrylic copolymers (A-7) to (A-8), and (A-11)> Solutions of (meth)acrylic copolymers (A-7) to (A-8) and (A-11) were obtained in the same manner as in Production Example 5, except that the types and amounts of component (M), component (m1), component (a1), and the initial solvent were changed to those shown in Table 2. The molecular weights of the obtained acrylic copolymers (A-7) to (A-8) and (A-11) were measured. The results are shown in Table 2.

[0074] <Production Example 16: Production of (meth)acrylic copolymer (A-12)> A four-neck flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 50 parts of methyl ethyl ketone (MEK) and 10 parts of isopropyl alcohol (IPA) as initial solvents, and the external temperature was raised to 85°C while stirring and under nitrogen gas flow. After the external temperature reached 85°C and the internal temperature stabilized, 25 parts of MEK and a mixture consisting of 79 parts of butyl acrylate, 10 parts of methyl methacrylate, and 10 parts of glycidyl methacrylate as component (m1), 1 part of glycerin monomethacrylate as component (a1), and 0.13 parts of benzoyl peroxide (manufactured by NOF Corporation, trade name: "Niper BMT-K40") as a polymerization initiator were added dropwise over 3 hours. After the dropwise addition was completed, the mixture was maintained for 1 hour, and then a mixture of 0.5 parts of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name "Perocta O") as a polymerization initiator and 10 parts of MEK was added over 1 hour. After maintaining the mixture for 2 hours, MEK was added so that the solid content (proportion of the amount of monomer charged in (amount of monomer + solvent charged)) became 50%, and the mixture was then cooled to room temperature to obtain an MEK solution of (meth)acrylic copolymer (A-12). The molecular weight of the resulting (meth)acrylic copolymer (A-12) was measured, and the results are shown in Table 2.

[0075] [Table 2]

[0076] The abbreviations in Table 2 are as follows: M1 to M4: Macromonomers produced in Production Examples 1 to 4. GLM: Glycerin monomethacrylate (manufactured by NOF Corporation, product name "Blenmar GLM-EX"). EA: Ethyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Ethyl acrylate"). n-BA: n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name "butyl acrylate"). 2-MTA: 2-Methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd., trade name "Methoxyethyl Acrylate"). MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester M"). GMA: Glycidyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name "Acryester G"). · MEK: Methyl ethyl ketone. ·IPA: Isopropyl alcohol.

[0077] [Example 1] 100 parts of the (meth)acrylic copolymer (A-1) solution obtained in Production Example 5 was mixed with 50 parts of bisphenol A-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER828"), and MEK was distilled off under reduced pressure using a vacuum dryer, thereby obtaining a (meth)acrylic copolymer-containing epoxy resin containing 50 parts of the (meth)acrylic copolymer (A-1). A mixing vessel was charged with 32 parts of a (meth)acrylic copolymer-containing epoxy resin as components (A) and (B) (breakdown: 16 parts of (meth)acrylic copolymer (A-1), 16 parts of jER828), 18 parts of jER828 as component (B), 4 parts of dicyandiamide as component (C), and 30 parts of Kane Ace MX154 (trade name, manufactured by Kaneka Corporation) as components (D) and (B) (breakdown: 12 parts of a polymer having a core-shell structure, bisphenol A). An epoxy resin composition was prepared by adding 18 parts of a phenol A-type epoxy resin, 0.8 parts of 3-(3,4-dichlorophenyl)-1,1-dimethylurea as a curing accelerator, 15.2 parts of calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., product name "Whiten B") as a filler, and 0.8 parts of glass beads (manufactured by Potters Ballotini Co., Ltd., product name "J-100"), and mixing them using a stirring degassing device (manufactured by Thinky Corporation, product name "Awatori Rentaro"). The resulting epoxy resin composition was used to evaluate the adhesive strength, and the results are shown in Table 3.

[0078] [Examples 2 to 8, Comparative Examples 1 to 5] Epoxy resin compositions were prepared in the same manner as in Example 1, except that the type of component (A) and the amount of each component were changed to those shown in Tables 3 and 5. The results of the adhesive strength evaluation of the epoxy resin compositions of Examples 2 to 8 and Comparative Examples 1 to 5 are shown in Tables 3 and 5.

[0079] [Example 9] 100 parts of the MEK solution of the (meth)acrylic copolymer (A-1) obtained in Production Example 2 was mixed with 50 parts of a bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER828"), and the MEK was distilled off under reduced pressure using a vacuum dryer, thereby obtaining a (meth)acrylic copolymer-containing epoxy resin containing 50 parts of the (meth)acrylic copolymer (A-1). An epoxy resin composition was prepared by adding 60 parts of a (meth)acrylic copolymer-containing epoxy resin as components (A) and (B) (breakdown: 30 parts of (meth)acrylic copolymer (A-1) and 30 parts of jER828), 20 parts of jER828 as component (B), 4 parts of dicyandiamide (manufactured by Mitsubishi Chemical Corporation, trade name "DICY7") as component (C), 0.8 parts of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (manufactured by Hodogaya Chemical Co., Ltd., trade name "DCMU") as a curing accelerator, 15.2 parts of calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., trade name "Whiten B") as a filler, and 0.8 parts of glass beads (manufactured by Potters Ballotini Co., Ltd., trade name "J-100") to a mixing vessel and mixing using a stirring degassing apparatus (manufactured by Thinky Corporation, product name "Awatori Rentaro"). The resulting epoxy resin composition was used to evaluate the adhesive strength, and the results are shown in Table 4.

[0080] [Examples 10 to 12, Comparative Examples 6 to 10] Epoxy resin compositions were prepared in the same manner as in Example 9, except that the type of component (A) and the amount of each component were changed to those shown in Tables 4 and 5. The results of the adhesive strength evaluation of the epoxy resin compositions of Examples 10 to 12 and Comparative Examples 6 to 10 are shown in Tables 4 and 5.

[0081] [Table 3]

[0082] [Table 4]

[0083] [Table 5]

[0084] The results of the impact strength evaluation carried out on the epoxy resin compositions of Examples 1 to 2, 4 to 8 and Comparative Example 1 are shown in Tables 3 and 5.

[0085] The abbreviations in Tables 3 to 5 are as follows: A-1 to A-13: (meth)acrylic copolymers (A) produced in Production Examples 5 to 17. jER828: Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER828"). Bisphenol A epoxy: Bisphenol A type epoxy resin contained in Kaneka Corporation's product name "Kane Ace MX154." DICY: Dicyandiamide (manufactured by Mitsubishi Chemical Corporation, product name "DICY7"). DCMU: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (manufactured by Hodogaya Chemical Co., Ltd., trade name "DCMU"). Whiten B: Calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., product name "Whiten B"). J-100: Glass beads (manufactured by Potters Barotini, product name "J-100"). Polymer with core-shell structure: Polymer with core-shell structure included in the product name "Kane Ace MX154" manufactured by Kaneka Corporation.

[0086] As is clear from Tables 3 to 5, the cured products of the epoxy resin compositions obtained in each Example were excellent in adhesive strength and impact strength. On the other hand, the cured products of the epoxy resin compositions obtained in each of the comparative examples were poor in adhesive strength and impact strength. [Industrial Applicability]

[0087] The epoxy resin composition containing the (meth)acrylic copolymer of the present invention can give a cured product having high adhesive strength and impact strength, and therefore the epoxy resin composition of the present invention is useful as, for example, adhesives for vehicles such as automobiles, civil engineering and construction adhesives, adhesives for electronic materials, general office adhesives, medical adhesives, industrial adhesives, molding materials, fiber-reinforced plastics, etc.

Claims

1. A (meth)acrylic copolymer which is a block copolymer or a graft copolymer, comprising a structural unit derived from a radically polymerizable monomer (a1) having a structure in which a hydroxyl group is bonded to each of at least two adjacent carbon atoms, and a structural unit derived from a (meth)acrylate (a2) having a cyclic ether group.

2. The (meth)acrylic copolymer according to claim 1 , wherein the radical polymerizable monomer (a1) is a (meth)acrylate represented by the following formula (1): 【Chemical 1】 (In formula (1), R １ is a hydrogen atom or a methyl group, R ２ ~R ４ each independently represents a hydrogen atom or a hydroxyl group, and x represents an integer of 0 to 3.

3. The (meth)acrylic copolymer according to claim 1, which has a main chain polymer structure and a side chain polymer structure, and the side chain polymer structure contains a structural unit derived from the (meth)acrylate (a2) having a cyclic ether group.

4. The (meth)acrylic copolymer according to claim 1 , which contains a structural unit derived from a macromonomer (M) and a structural unit derived from a vinyl radically polymerizable monomer (m1).

5. The (meth)acrylic copolymer according to claim 4 , wherein the macromonomer (M) contains a structural unit derived from a vinyl radically polymerizable monomer (m2).

6. The (meth)acrylic copolymer according to claim 5 , wherein the macromonomer (M) contains a structure represented by the following formula (2): 【Chemistry 2】 (In formula (2), X １ ~X ｎ－１ are each independently H, CH ３ or CH ２ OH and Y １ ~Y ｎ are each independently a substituent bonded to the vinyl group of the vinyl radical polymerizable monomer (m2), Z is a terminal group, and n is an integer of 2 to 10,000.

7. An epoxy resin composition comprising the (meth)acrylic copolymer according to claim 1, an epoxy resin (B), and a curing agent (C).

8. The epoxy resin composition according to claim 7, further comprising a polymer (D) having a core-shell structure.

9. An adhesive comprising the epoxy resin composition according to claim 7 or 8.

10. A cured product of the epoxy resin composition according to claim 7 or 8.

11. A molding material comprising the cured product according to claim 10.

12. A fiber-reinforced plastic comprising the cured product according to claim 10.

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