One-component curable resin composition and adhesive

Abstract

A one-pack type curable resin composition which contains 100 parts by weight of (A) an epoxy resin, from 1 to 100 parts by weight of (B) polymer particles having a core-shell structure and / or a blocked urethane, (C) a compound which has from 1 to 3 phenolic hydroxyl groups in each molecule (provided that a compound having an amino group is not considered as a compound (C)), and (D) dicyandiamide. The (number of moles of phenolic hydroxyl groups in compound (C)) / (number of moles of CN groups generated from dicyandiamide (D)) ratio is from 0.01 to 0.39 in cases where the compound (C) has one phenolic hydroxyl group, while the ratio is from 0.01 to 1.5 in cases where the compound (C) has two or three phenolic hydroxyl groups.

Description

[Technical Field]

[0001] The present invention relates to a one-component curable resin composition containing an epoxy resin, and an adhesive containing the same. [Background technology]

[0002] Epoxy resins are widely used in civil engineering and construction materials, electrical and electronic materials, adhesives, etc., because their cured products have excellent dimensional stability, mechanical strength, electrical insulation properties, heat resistance, water resistance, chemical resistance, etc. However, cured epoxy resins have the problem of low fracture toughness and very brittle properties.

[0003] On the other hand, dicyandiamide generates cyanamide when heated, and can function as a latent curing agent that exhibits curing activity. Therefore, it is known that blending dicyandiamide with an epoxy resin can form a one-component curable composition.

[0004] Patent Document 1 describes an adhesive composition that exhibits high peel adhesive strength by containing an epoxy resin, dicyandiamide as a curing agent, and fine particles of a specific particle size made of a specific thermoplastic resin. In this document, core-shell particles are used in the comparative examples.

[0005] Patent Document 2 describes a one-component epoxy adhesive in which an epoxy compound containing a tri- or higher functional liquid epoxy is blended with a filler, a core-shell toughening agent, and a latent curing agent such as dicyandiamide.

[0006] Patent Document 3 describes an epoxy resin composition containing an epoxy resin, an amino-based curing agent such as dicyandiamide, and a phenol-based curing agent having a specific structure, with the ratio of the amino-based curing agent to the phenol-based curing agent being within a specific range, and a prepreg formed using the same. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-36095 [Patent Document 2] JP 2019-11445 A [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-40069 Summary of the Invention [Problem to be solved by the invention]

[0008] The one-component curable compositions in which dicyandiamide is blended with an epoxy resin as described in Patent Documents 1 to 3 do not have sufficient impact peel adhesion and there is room for improvement.

[0009] In view of the above-mentioned current situation, an object of the present invention is to provide a one-component curable resin composition which contains an epoxy resin and dicyandiamide and which gives a cured product which exhibits excellent impact peel adhesion. [Means for solving the problem]

[0010] As a result of extensive research to solve the above problems, the present inventors have found that a one-component curable resin composition can be obtained that gives a cured product that exhibits excellent impact peel adhesion by blending an epoxy resin (A) with polymer particles and / or blocked urethane (B) having a core-shell structure, a specific phenolic compound (C), and dicyandiamide (D) in a specific ratio.

[0011] That is, the present invention comprises 100 parts by weight of an epoxy resin (A), 1 to 100 parts by weight of polymer particles and / or blocked urethane (B) having a core-shell structure, Compound (C) having 1 to 3 phenolic hydroxyl groups in one molecule [however, when the compound having 1 to 3 phenolic hydroxyl groups in one molecule further has an amino group, it does not fall under the category of compound (C)], and Dicyandiamide (D), The one-component curable resin composition relates to a one-component curable resin composition, wherein the ratio of the number of moles of phenolic hydroxyl groups in the compound (C) to the number of moles of CN groups generated from dicyandiamide (D) is 0.01 or more and 0.39 or less when the compound (C) has one phenolic hydroxyl group in one molecule, and is 0.01 or more and 1.5 or less when the compound (C) has two or three phenolic hydroxyl groups in one molecule. Preferably, the compound (C) has one or two phenolic hydroxyl groups in one molecule. Preferably, the compound (C) has, on the aromatic ring, 1 to 4 substituents selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, and a halogen. Preferably, the compound (C) has one or two substituents selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, and a halogen at the ortho position of at least one phenolic hydroxyl group. Preferably, the component (B) contains polymer particles having the core-shell structure. Preferably, the molecular weight of the compound (C) is 90 or more and 500 or less. Preferably, the composition further contains a compound (E) having four or more phenolic hydroxyl groups in one molecule, and the ratio of the total weight of the compound (E) to the total weight of the compound (C) is less than 1. Preferably, the ratio of the molar amount of the dicyandiamide (D) to the molar amount of the epoxy groups in the epoxy resin (A) is 0.10 or more and 0.30 or less. Preferably, the one-component curable resin composition further contains 0.1 to 10 parts by weight of a curing accelerator (F) based on 100 parts by weight of the epoxy resin (A). Preferably, the polymer particles having a core-shell structure have a core layer made of one or more types of rubber selected from the group consisting of diene-based rubber, (meth)acrylate-based rubber, and organosiloxane-based rubber. Preferably, the diene rubber is a butadiene rubber and / or a butadiene-styrene rubber. Preferably, the polymer particles having a core-shell structure have a shell layer formed by graft polymerizing one or more monomer components selected from the group consisting of aromatic vinyl monomers, vinyl cyan monomers, and (meth)acrylate monomers onto a core layer. Preferably, the polymer particles having a core-shell structure have epoxy groups in the shell layer. Preferably, the polymer particles having a core-shell structure have a shell layer formed by graft polymerizing a monomer component having an epoxy group onto a core layer. Preferably, the polymer particles having a core-shell structure have epoxy groups in the shell layer, and the content of the epoxy groups in the shell layer relative to the total amount of the shell layer is 0.1 to 2.0 mmol / g. The present invention also relates to a cured product obtained by curing the one-component curable resin composition. The present invention also relates to an adhesive containing the one-component curable resin composition. Preferably, the adhesive is a structural adhesive. Furthermore, the present invention also relates to a laminate comprising two substrates and an adhesive layer formed by curing the adhesive, which bonds the two substrates together. The present invention also relates to a method for producing the cured product, the method including the steps of mixing the epoxy resin (A), the polymer particles having a core-shell structure and / or the blocked urethane (B), the compound (C), and the dicyandiamide (D) to obtain a mixture, and heating the mixture to obtain the cured product. [Effects of the Invention]

[0012] An object of the present invention is to provide a one-component curable resin composition which contains an epoxy resin and dicyandiamide and which gives a cured product which exhibits excellent impact peel adhesion. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0014] The present embodiment is a one-component curable resin composition containing at least an epoxy resin (A), polymer particles and / or blocked urethane having a core-shell structure (B), a compound (C) having 1 to 3 phenolic hydroxyl groups in one molecule, and dicyandiamide (D).

[0015] <Epoxy resin (A)> The one-component curable resin composition of this embodiment contains an epoxy resin (A) as the curable resin. Various epoxy resins can be used as the epoxy resin. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD ​​epoxy resin, bisphenol S epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, novolac epoxy resin, glycidyl ether epoxy resin of bisphenol A propylene oxide adduct, hydrogenated bisphenol A (or F) epoxy resin, fluorinated epoxy resin, flame-retardant epoxy resin such as glycidyl ether of tetrabromobisphenol A, p-oxybenzoic acid glycidyl ether ester epoxy resin, m-aminophenol epoxy resin, diaminodiphenylmethane epoxy resin, various alicyclic epoxy resins, N,N-diglycidylaniline, N,N-diglycidyl-o-toluidin Examples of epoxy resins include, but are not limited to, epoxy compounds obtained by addition reaction of the above-mentioned epoxy resins with bisphenol A (or F) or polybasic acids, triglycidyl isocyanurate, divinylbenzene dioxide, resorcinol diglycidyl ether, polyalkylene glycol diglycidyl ether, glycol diglycidyl ether, diglycidyl esters of aliphatic polybasic acids, glycidyl ethers of dihydric or higher polyhydric aliphatic alcohols such as glycerin, epoxidized products of unsaturated polymers such as chelate-modified epoxy resins, rubber-modified epoxy resins, urethane-modified epoxy resins, hydantoin-type epoxy resins, and petroleum resins, amino-containing glycidyl ether resins, and epoxy compounds obtained by addition reaction of the above-mentioned epoxy resins with bisphenol A (or F) or polybasic acids, etc., but commonly used epoxy resins can also be used. These epoxy resins may be used alone or in combination of two or more.

[0016] More specific examples of the polyalkylene glycol diglycidyl ether include polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether. More specific examples of the glycol diglycidyl ether include neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether. More specific examples of the diglycidyl esters of aliphatic polybasic acids include dimer acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, and maleic acid diglycidyl ester. More specific examples of the glycidyl ethers of dihydric or higher polyhydric aliphatic alcohols include trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, castor oil-modified polyglycidyl ether, propoxylated glycerin triglycidyl ether, and sorbitol polyglycidyl ether. Examples of epoxy compounds obtained by subjecting an epoxy resin to an addition reaction with a polybasic acid or the like include an addition reaction product of a dimer of tall oil fatty acid (dimer acid) with a bisphenol A-type epoxy resin, as described in WO 2010-098950.

[0017] The polyalkylene glycol diglycidyl ethers, glycol diglycidyl ethers, diglycidyl esters of aliphatic polybasic acids, and glycidyl ethers of dihydric or higher polyhydric aliphatic alcohols are epoxy resins with relatively low viscosity, and when used in combination with other epoxy resins such as bisphenol A epoxy resins and bisphenol F epoxy resins, they function as reactive diluents, improving the balance between the viscosity of the composition and the physical properties of the cured product. The content of these epoxy resins functioning as reactive diluents in component (A) is preferably 0.5 to 20 wt %, more preferably 1 to 10 wt %, and even more preferably 2 to 5 wt %.

[0018] The chelate-modified epoxy resin is a reaction product of an epoxy resin and a compound containing a chelating functional group (chelating ligand). When a one-component curable resin composition containing this resin is used as a vehicle adhesive, it can improve adhesion to metal substrate surfaces contaminated with oily substances. The chelating functional group is a functional group of a compound that has multiple coordination sites within the molecule capable of coordinating to metal ions. Examples include phosphorus-containing acid groups (e.g., -PO(OH)), carboxylic acid groups (-COH), sulfur-containing acid groups (e.g., -SOH), amino groups, and hydroxyl groups (especially hydroxyl groups adjacent to each other in an aromatic ring). Examples of chelating ligands include ethylenediamine, bipyridine, ethylenediaminetetraacetic acid, phenanthroline, porphyrin, and crown ether. Commercially available chelate-modified epoxy resins include ADEKA ADEKA RESIN EP-49-10N. The amount of chelate-modified epoxy resin used in component (A) is preferably 0.1 to 10% by weight, and more preferably 0.5 to 3% by weight.

[0019] The rubber-modified epoxy resin is a reaction product obtained by reacting rubber with an epoxy group-containing compound, and has an average of 1.1 or more epoxy groups per molecule, preferably 2 or more. Examples of rubber include rubber-based polymers such as acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber, and polyoxyalkylenes such as polypropylene oxide, polyethylene oxide, and polytetramethylene oxide. The rubber-based polymer preferably has a terminal reactive group such as an amino group, a hydroxy group, or a carboxyl group. The rubber-modified epoxy resin is a product obtained by reacting these rubber-based polymers with an epoxy resin at an appropriate blending ratio using a known method. Among these, acrylonitrile-butadiene rubber-modified epoxy resins and polyoxyalkylene-modified epoxy resins are preferred from the viewpoint of the adhesiveness and impact peel adhesion resistance of the resulting one-component curable resin composition, and acrylonitrile-butadiene rubber-modified epoxy resins are more preferred. Note that acrylonitrile-butadiene rubber-modified epoxy resins can be obtained, for example, by reacting carboxyl-terminated NBR (CTBN) with bisphenol A-type epoxy resin.

[0020] The content of the acrylonitrile monomer component in the acrylonitrile-butadiene rubber is preferably 5 to 40% by weight, more preferably 10 to 35% by weight, and even more preferably 15 to 30% by weight, from the viewpoint of adhesiveness and impact peel adhesion of the resulting one-component curable resin composition, and particularly preferably 20 to 30% by weight from the viewpoint of workability of the resulting one-component curable resin composition.

[0021] Further, rubber-modified epoxy resins also include, for example, addition reaction products (hereinafter also referred to as "adducts") between amino-terminated polyoxyalkylenes and epoxy resins. The adducts can be easily produced by known methods, as described in, for example, U.S. Pat. Nos. 5,084,532 and 6,015,865. Examples of the epoxy resins used in producing the adducts include the specific examples of component (A) described above, but bisphenol A epoxy resins and bisphenol F epoxy resins are preferred, and bisphenol A epoxy resins are more preferred. Examples of commercially available amino-terminated polyoxyalkylenes used in producing the adducts include Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, Jeffamine D-4000, and Jeffamine T-5000, manufactured by Huntsman.

[0022] The average number of epoxide reactive terminal groups per molecule in the rubber is preferably 1.5 to 2.5, more preferably 1.8 to 2.2. The number average molecular weight of the rubber, measured by GPC in terms of polystyrene, is preferably 1,000 to 10,000, more preferably 2,000 to 8,000, particularly preferably 3,000 to 6,000.

[0023] There are no particular limitations on the method for producing rubber-modified epoxy resins. For example, they can be produced by reacting rubber with an epoxy group-containing compound in a large amount of epoxy group-containing compound. Specifically, production is preferably carried out by reacting two or more equivalents of epoxy group-containing compound per equivalent of epoxy reactive terminal groups in the rubber. It is more preferable to react a sufficient amount of epoxy group-containing compound so that the resulting product is a mixture of an adduct of rubber and epoxy group-containing compound and free epoxy group-containing compound. For example, rubber-modified epoxy resins can be produced by heating to a temperature of 100 to 250°C in the presence of a catalyst such as phenyldimethylurea or triphenylphosphine. There are no particular limitations on the epoxy group-containing compound used in producing rubber-modified epoxy resins; however, bisphenol A epoxy resins and bisphenol F epoxy resins are preferred, and bisphenol A epoxy resins are more preferred. Note that if an excessive amount of epoxy group-containing compound is used in producing the rubber-modified epoxy resin, the unreacted epoxy group-containing compound remaining after the reaction is not included in the rubber-modified epoxy resin as used herein.

[0024] In the case of rubber-modified epoxy resins, the epoxy resin can be modified by pre-reacting it with a bisphenol component. The amount of the bisphenol component used for modification is preferably 3 to 35 parts by weight, more preferably 5 to 25 parts by weight, per 100 parts by weight of the rubber component in the rubber-modified epoxy resin. A cured product obtained by curing a one-component curable resin composition containing the modified rubber-modified epoxy resin has excellent adhesion durability after exposure to high temperatures and also excellent impact resistance at low temperatures.

[0025] The glass transition temperature (Tg) of the rubber-modified epoxy resin is not particularly limited, but is preferably −25° C. or lower, more preferably −35° C. or lower, even more preferably −40° C. or lower, and particularly preferably −50° C. or lower.

[0026] The number average molecular weight of the rubber-modified epoxy resin, measured by GPC in terms of polystyrene, is preferably 1500 to 40000, more preferably 3000 to 30000, and particularly preferably 4000 to 20000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

[0027] The rubber-modified epoxy resins can be used alone or in combination of two or more kinds. The amount of rubber-modified epoxy resin used in component (A) is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, even more preferably 5 to 30% by weight, and particularly preferably 10 to 20% by weight.

[0028] The urethane-modified epoxy resin is a reaction product obtained by reacting a compound containing an epoxy group and a group reactive with an isocyanate group with a urethane prepolymer containing an isocyanate group, and has an average of 1.1 or more epoxy groups per molecule, preferably 2 or more. For example, a urethane-modified epoxy resin can be obtained by reacting a hydroxyl-containing epoxy compound with a urethane prepolymer.

[0029] The number average molecular weight of the urethane-modified epoxy resin, measured by GPC in terms of polystyrene, is preferably 1500 to 40000, more preferably 3000 to 30000, and particularly preferably 4000 to 20000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

[0030] The urethane-modified epoxy resins can be used alone or in combination of two or more kinds. The amount of urethane-modified epoxy resin used in component (A) is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, even more preferably 5 to 30% by weight, and particularly preferably 10 to 20% by weight.

[0031] Among these epoxy resins, those having at least two epoxy groups in one molecule are preferred because they have high curability, excellent flexibility after curing, and excellent effect of improving impact peel resistance by blending the core-shell polymer particles (B). In particular, compounds having two epoxy groups in one molecule are preferred.

[0032] Among the above-mentioned epoxy resins, bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferred because the resulting cured products have a high elastic modulus, excellent heat resistance and adhesiveness, and are relatively inexpensive, with bisphenol A type epoxy resins being particularly preferred.

[0033] Among various epoxy resins, epoxy resins having an epoxy equivalent of less than 220 are preferred because the resulting cured product has a high elastic modulus and heat resistance. An epoxy equivalent of 90 or more but less than 210 is more preferred, and 150 or more but less than 200 is even more preferred.

[0034] In particular, bisphenol A type epoxy resins and bisphenol F type epoxy resins having an epoxy equivalent of less than 220 are preferred because they are liquid at room temperature and the resulting one-component curable resin compositions are easy to handle.

[0035] It is preferred to add a bisphenol A type epoxy resin or a bisphenol F type epoxy resin having an epoxy equivalent of 220 or more but less than 5000 to component (A) in an amount of preferably 40% by weight or less, more preferably 20% by weight or less, since the resulting cured product will have excellent impact resistance.

[0036] <Core-shell polymer particles and / or blocked urethane (B)> The one-component curable resin composition of this embodiment contains, as component (B), polymer particles having a core-shell structure and / or a blocked urethane. Due to the toughness-improving effect of component (B), the resulting cured product has excellent impact peel adhesion. By using component (B) in combination with component (C), which will be described below, in addition to components (A) and (D), a synergistic effect can be achieved, greatly improving the impact peel adhesion of the cured product obtained from the one-component curable resin composition. Component (B) may contain only polymer particles having a core-shell structure, or only blocked urethane. Alternatively, it may contain both. It is preferable that component (B) contains at least polymer particles having a core-shell structure. Hereinafter, polymer particles having a core-shell structure will also be referred to as core-shell polymer particles.

[0037] <Core-shell polymer particles> The core-shell polymer particles (B) may not have epoxy groups in the shell layer, but preferably have epoxy groups in the shell layer. In this case, the content of epoxy groups in the shell layer relative to the total amount of the shell layers of the core-shell polymer particles (B) is preferably 0.1 mmol / g or more and 2.0 mmol / g or less, more preferably 0.3 mmol / g or more and 1.5 mmol / g or less, from the viewpoint of the impact peel adhesion of the resulting cured product. This is thought to suppress aggregation of the core-shell polymer particles (B) and allow the core-shell polymer particles (B) to be dispersed in the cured product in the state of primary particles, thereby improving the impact peel adhesion of the cured product.

[0038] The particle size of the core-shell polymer particles (B) is not particularly limited, but in consideration of industrial productivity, the volume average particle size (Mv) is preferably 10 to 2000 nm, more preferably 30 to 600 nm, still more preferably 50 to 400 nm, and particularly preferably 100 to 300 nm. The volume average particle size (Mv) of the polymer particles can be measured for the latex of the polymer particles using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.).

[0039] In the one-component curable resin composition, the core-shell polymer particles (B) preferably have a half-value width in the number distribution of particle diameters that is 0.5 to 1 times the volume average particle diameter, because the resulting one-component curable resin composition has a low viscosity and is easy to handle.

[0040] From the viewpoint of easily realizing the above-mentioned specific particle size distribution, it is preferable that the particle size number distribution of the core-shell polymer particles (B) has two or more maximum values, and from the viewpoint of the labor and cost during production, it is more preferable that the particle size number distribution has two or three maximum values, and even more preferable that the particle size number distribution has two maximum values. In particular, it is preferable that the particle size distribution contains 10 to 90% by weight of core-shell polymer particles having a volume average particle size of 10 nm or more and less than 150 nm, and 90 to 10% by weight of core-shell polymer particles having a volume average particle size of 150 nm or more and 2000 nm or less.

[0041] The core-shell polymer particles (B) are preferably dispersed in the one-component curable resin composition in the state of primary particles. In this specification, "the core-shell polymer particles are dispersed in the state of primary particles" (hereinafter also referred to as "primary dispersion") means that the core-shell polymer particles are dispersed substantially independently (without contact) with each other, and this dispersion state can be confirmed, for example, by dissolving a part of the one-component curable resin composition in a solvent such as methyl ethyl ketone and measuring the particle size using a particle size measuring device that uses laser light scattering.

[0042] The value of the volume average particle diameter (Mv) / number average particle diameter (Mn) measured by the particle diameter measurement is not particularly limited, but is preferably not more than 3, more preferably not more than 2.5, even more preferably not more than 2, and particularly preferably not more than 1.5. If the volume average particle diameter (Mv) / number average particle diameter (Mn) is not more than 3, it is considered that the core-shell polymer particles (B) are well dispersed, and the physical properties of the obtained cured product, such as impact resistance and adhesiveness, will be good.

[0043] The volume average particle size (Mv) / number average particle size (Mn) can be determined by measuring using a Microtrac UPA (manufactured by Nikkiso Co., Ltd.) and dividing Mv by Mn.

[0044] Furthermore, the "stable dispersion" of the core-shell polymer particles means a state in which the core-shell polymer particles are dispersed steadily under normal conditions for a long period of time without aggregation, separation, or precipitation in the continuous layer. It is also preferable that the distribution of the core-shell polymer particles in the continuous layer does not change substantially, and that the "stable dispersion" can be maintained even when the composition is heated within a safe range to reduce the viscosity and stirred. The core-shell polymer particles (B) may be used alone or in combination of two or more kinds.

[0045] The structure of the core-shell polymer particles (B) is not particularly limited, but preferably has two or more layers, and may also have a three or more layer structure consisting of an intermediate layer covering a core layer and a shell layer further covering the intermediate layer.

[0046] Each layer of the core-shell polymer particles (B) will be specifically described below. <Core layer> The core layer is preferably an elastic core layer having rubber-like properties in order to enhance the toughness of the cured product of the one-component curable resin composition. To have rubber-like properties, the elastic core layer preferably has a gel content of 60% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more. In this specification, the gel content refers to the ratio of insoluble matter to the total amount of insoluble matter and soluble matter when 0.5 g of crumb obtained by coagulation and drying is immersed in 100 g of toluene, left to stand at 23°C for 24 hours, and then the insoluble matter and soluble matter are separated.

[0047] The core layer preferably contains one or more rubbers selected from the group consisting of diene rubbers, (meth)acrylate rubbers, and organosiloxane rubbers. The core layer preferably contains a diene rubber because it has a high effect of improving the impact peel adhesion of the resulting cured product and has low affinity with the epoxy resin (A), making it less likely to experience an increase in viscosity over time due to swelling of the core layer caused by component (A).

[0048] (Diene rubber) Examples of the conjugated diene monomer constituting the diene rubber include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, 2-methyl-1,3-butadiene, etc. These conjugated diene monomers may be used alone or in combination of two or more.

[0049] The content of the conjugated diene monomer in the core layer is preferably in the range of 50 to 100% by weight, more preferably in the range of 70 to 100% by weight, and even more preferably in the range of 90 to 100% by weight. When the content of the conjugated diene monomer is 50% by weight or more, the impact peel adhesion of the resulting cured product can be improved.

[0050] Examples of vinyl monomers copolymerizable with conjugated diene monomers include vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; vinyl carboxylic acids such as acrylic acid and methacrylic acid; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; vinyl acetate; alkenes such as ethylene, propylene, butylene, and isobutylene; and polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. These vinyl monomers may be used alone or in combination of two or more. Styrene is particularly preferred.

[0051] The content of the vinyl monomer copolymerizable with the conjugated diene monomer in the core layer is preferably 0 to 50% by weight, more preferably 0 to 30% by weight, and even more preferably 0 to 10% by weight. When the content of the vinyl monomer copolymerizable with the conjugated diene monomer is 50% by weight or less, the impact peel adhesion of the resulting cured product can be improved.

[0052] The diene rubber is preferably butadiene rubber using 1,3-butadiene and / or butadiene-styrene rubber, which is a copolymer of 1,3-butadiene and styrene, from the viewpoints of a high effect of improving impact peel adhesion and a low affinity with the epoxy resin (A) that makes it difficult for the viscosity to increase over time due to swelling of the core layer, and butadiene rubber is more preferred. Butadiene-styrene rubber is also preferred because it can enhance the transparency of the cured product obtained by adjusting the refractive index.

[0053] ((Meth)acrylate rubber) The (meth)acrylate rubber is preferably a rubber elastomer obtained by polymerizing a monomer mixture containing 50 to 100% by weight of at least one monomer selected from the group consisting of (meth)acrylate monomers and 0 to 50% by weight of another vinyl monomer copolymerizable with the (meth)acrylate monomer.

[0054] Examples of the (meth)acrylate monomer include: (i) alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (ii) aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; (iii) 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; Examples of suitable (meth)acrylate monomers include hydroxyalkyl (meth)acrylates such as acrylate; (iv) glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; (v) alkoxyalkyl (meth)acrylates; (vi) allyl alkyl (meth)acrylates such as allyl (meth)acrylate and allyl alkyl (meth)acrylate; and (vii) polyfunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. These (meth)acrylate monomers may be used alone or in combination of two or more. Preferred (meth)acrylate monomers are ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0055] Examples of other vinyl monomers copolymerizable with (meth)acrylate monomers include: (i) vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; (ii) vinyl carboxylic acids such as acrylic acid and methacrylic acid; (iii) vinyl cyanides such as acrylonitrile and methacrylonitrile; (iv) vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; (v) vinyl acetate; (vi) alkenes such as ethylene, propylene, butylene, and isobutylene; and (vii) polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. These vinyl monomers may be used alone or in combination of two or more. Styrene is particularly preferred because it can easily increase the refractive index.

[0056] (organosiloxane rubber) Examples of the organosiloxane rubber include (i) polysiloxane polymers composed of alkyl or aryl di-substituted silyloxy units, such as dimethylsilyloxy, diethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy; and (ii) polysiloxane polymers composed of alkyl or aryl mono-substituted silyloxy units, such as organohydrogensilyloxy in which some of the alkyl groups in the side chains are substituted with hydrogen atoms. These polysiloxane polymers may be used alone or in combination of two or more. Among them, dimethylsilyloxy, methylphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy are preferred because they can impart heat resistance to the cured product, and dimethylsilyloxy is most preferred because it is easily available. In an embodiment in which the core layer is formed from an organosiloxane rubber, the polysiloxane polymer moiety preferably accounts for 80% by weight or more (more preferably 90% by weight or more) of the total organosiloxane rubber as 100% by weight, in order not to impair the heat resistance of the cured product.

[0057] The glass transition temperature (hereinafter sometimes simply referred to as "Tg") of the core layer is preferably 0°C or lower, more preferably -20°C or lower, even more preferably -40°C or lower, and particularly preferably -60°C or lower, in order to enhance the toughness of the resulting cured product.

[0058] The volume average particle diameter of the core layer is preferably 0.03 to 2 μm, more preferably 0.05 to 1 μm. Within this range, stable production is possible, and the cured product can have good heat resistance and impact resistance. The volume average particle diameter can be measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.).

[0059] The proportion of the core layer is preferably 40 to 97 wt%, more preferably 60 to 95 wt%, even more preferably 70 to 93 wt%, and particularly preferably 80 to 90 wt%, based on 100 wt% of the entire core-shell polymer particles. When the proportion of the core layer is 40 wt% or more, the impact peel adhesion of the resulting cured product can be improved. When the proportion of the core layer is 97 wt% or less, the core-shell polymer particles are less likely to aggregate, the one-component curable resin composition has a lower viscosity, and workability can be improved.

[0060] The core layer is often a single layer structure, but may also be a multilayer structure consisting of layers having rubber elasticity. When the core layer has a multilayer structure, the polymer compositions of the layers may be different from each other within the ranges disclosed above.

[0061] <Middle class> If necessary, an intermediate layer may be formed between the core layer and the shell layer. In particular, the following rubber surface cross-linked layer may be formed as the intermediate layer. From the viewpoint of the effect of improving the toughness and impact peel adhesion of the resulting cured product, it is preferable not to include an intermediate layer, and in particular not to include the following rubber surface cross-linked layer.

[0062] When an intermediate layer is present, the ratio of the intermediate layer to 100 parts by weight of the core layer is preferably 0.1 to 30 parts by weight, more preferably 0.2 to 20 parts by weight, further preferably 0.5 to 10 parts by weight, and particularly preferably 1 to 5 parts by weight.

[0063] The cross-linked rubber surface layer is composed of an intermediate layer polymer obtained by polymerizing a cross-linked rubber surface layer component consisting of 30 to 100% by weight of a polyfunctional monomer having two or more radically polymerizable double bonds in one molecule and 0 to 70% by weight of other vinyl monomers, and has the effects of reducing the viscosity of the one-component curable resin composition and improving the dispersibility of the core-shell polymer particles (B) in component (A). It also has the effects of increasing the cross-link density of the core layer and the grafting efficiency of the shell layer.

[0064] Specific examples of the polyfunctional monomer do not include conjugated diene monomers such as butadiene, and include allyl alkyl (meth)acrylates such as allyl (meth)acrylate and allyl alkyl (meth)acrylate; allyloxyalkyl (meth)acrylates; polyfunctional (meth)acrylates having two or more (meth)acrylic groups such as (poly)ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene, with allyl methacrylate and triallyl isocyanurate being preferred. In this specification, (meth)acrylate refers to acrylate and / or methacrylate.

[0065] <Shell layer> The shell layer present on the outermost side of the core-shell polymer particles is formed by polymerizing a monomer for forming the shell layer, and is made of a shell polymer that plays a role in improving the compatibility between the core-shell polymer particles (B) and the component (A) and enabling the core-shell polymer particles (B) to be dispersed in the form of primary particles in the one-component curable resin composition or its cured product.

[0066] Such a shell polymer is preferably grafted to the core layer and / or intermediate layer. Hereinafter, the phrase "grafted to the core layer" includes the case where an intermediate layer is formed on the core layer, in which case the shell polymer is grafted to the intermediate layer. More precisely, it is preferable that the monomer component used to form the shell layer is graft polymerized to the core polymer forming the core layer (when an intermediate layer is formed, the core polymer also includes the intermediate layer polymer forming the intermediate layer; the same applies below), so that the shell polymer and the core polymer are substantially chemically bonded to each other (when an intermediate layer is formed, it is also preferable that the shell polymer and the intermediate layer polymer are chemically bonded to each other). That is, the shell polymer is preferably formed by graft polymerizing the shell layer-forming monomer in the presence of the core polymer, so that the shell polymer is graft polymerized to the core polymer and covers a part or all of the core polymer. This polymerization operation can be carried out by adding the shell polymer layer-forming monomer to a core polymer latex prepared in an aqueous polymer latex state and polymerizing it.

[0067] As the shell layer-forming monomer, from the viewpoint of compatibility and dispersibility of the core-shell polymer particles (B) in the one-component curable resin composition, for example, an aromatic vinyl monomer, a vinyl cyan monomer, or a (meth)acrylate monomer is preferred, and a (meth)acrylate monomer is more preferred. In particular, the shell layer-forming monomer preferably contains methyl methacrylate. These shell layer-forming monomers may be used alone or in appropriate combination.

[0068] The total amount of the aromatic vinyl monomer, vinyl cyan monomer, and (meth)acrylate monomer is preferably 10 to 99.5% by weight, more preferably 50 to 99% by weight, even more preferably 65 to 98% by weight, particularly preferably 67 to 90% by weight, and most preferably 67 to 85% by weight, based on 100% by weight of the monomers for forming the shell layer.

[0069] The content of methyl methacrylate is preferably 5 to 100% by weight, more preferably 20 to 99% by weight, further preferably 30 to 97% by weight, and particularly preferably 70 to 95% by weight, based on 100% by weight of the monomer for forming the shell layer.

[0070] In order to chemically bond the core-shell polymer particles (B) with component (A) so that they do not aggregate and remain well dispersed in the cured product or one-component curable resin composition, it is preferable that the shell layer-forming monomer contains a reactive group-containing monomer containing one or more groups selected from the group consisting of an epoxy group, an oxetane group, a hydroxyl group, an amino group, an imide group, a carboxylic acid group, a carboxylic anhydride group, a cyclic ester, a cyclic amide, a benzoxazine group, and a cyanate ester group, and in particular, a monomer having an epoxy group is preferred.

[0071] From the viewpoint of impact peel adhesion and storage stability, the monomer having an epoxy group is preferably contained in an amount of 0 to 90% by weight, more preferably 1 to 50% by weight, even more preferably 2 to 35% by weight, and particularly preferably 3 to 20% by weight, based on 100% by weight of the monomer for forming the shell layer.

[0072] The monomer having an epoxy group is preferably used to form the shell layer, and more preferably used only in the shell layer.

[0073] In addition, the use of a polyfunctional monomer having two or more radically polymerizable double bonds as the shell layer-forming monomer is preferred because it prevents swelling of the core-shell polymer particles in the one-component curable resin composition and tends to result in a one-component curable resin composition with a low viscosity and easy handling. On the other hand, from the viewpoint of improving the toughness and impact peel adhesion of the resulting cured product, it is preferred not to use a polyfunctional monomer having two or more radically polymerizable double bonds as the shell layer-forming monomer.

[0074] The polyfunctional monomer may be contained in an amount of, for example, 0 to 20% by weight, preferably 1 to 20% by weight, and more preferably 5 to 15% by weight, based on 100% by weight of the monomers for forming the shell layer.

[0075] Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, and vinylbenzenes such as divinylbenzene.

[0076] Specific examples of the vinyl cyan monomer include acrylonitrile and methacrylonitrile.

[0077] Specific examples of the (meth)acrylate monomer include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; and (meth)acrylic acid hydroxyalkyl esters.

[0078] Specific examples of the (meth)acrylic acid hydroxyalkyl ester include hydroxy linear alkyl (meth)acrylates (particularly, hydroxy linear C1-6 alkyl (meth)acrylates) such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; caprolactone-modified hydroxy (meth)acrylates; hydroxy branched alkyl (meth)acrylates such as α-(hydroxymethyl)methyl acrylate and α-(hydroxymethyl)ethyl acrylate; and hydroxyl group-containing (meth)acrylates such as mono(meth)acrylates of polyester diols (particularly saturated polyester diols) obtained from divalent carboxylic acids (such as phthalic acid) and dihydric alcohols (such as propylene glycol).

[0079] Specific examples of the monomer having an epoxy group include glycidyl group-containing vinyl monomers such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether.

[0080] Specific examples of the polyfunctional monomer having two or more radically polymerizable double bonds include the same monomers as the polyfunctional monomers described above, with allyl methacrylate and triallyl isocyanurate being preferred.

[0081] In this embodiment, the shell layer is preferably a polymer of shell layer-forming monomers (total 100 wt%) that combine, for example, 0 to 50 wt% (preferably 1 to 50 wt%, more preferably 2 to 48 wt%) of an aromatic vinyl monomer (particularly styrene), 0 to 50 wt% (preferably 0 to 30 wt%, more preferably 10 to 25 wt%) of a vinyl cyan monomer (particularly acrylonitrile), 0 to 100 wt% (preferably 5 to 100 wt%, more preferably 70 to 95 wt%) of a (meth)acrylate monomer (particularly methyl methacrylate), and 1 to 50 wt% (preferably 2 to 35 wt%, more preferably 3 to 20 wt%) of a monomer having an epoxy group (particularly glycidyl methacrylate). This allows for a good balance between the desired toughness improvement effect and mechanical properties.

[0082] These monomer components may be used alone or in combination of two or more. The shell layer may be formed by containing other monomer components in addition to the above-mentioned monomer components.

[0083] The graft ratio of the shell layer is preferably 70% or more (more preferably 80% or more, and even more preferably 90% or more). When the graft ratio is 70% or more, the one-component curable resin composition can have a lower viscosity.

[0084] The graft ratio is calculated as follows. First, an aqueous latex containing core-shell polymer particles is coagulated and dehydrated, and finally dried to obtain a powder of core-shell polymer particles. Next, 2 g of the powder of core-shell polymer particles is immersed in 100 g of methyl ethyl ketone (MEK) at 23°C for 24 hours, after which the MEK-soluble fraction is separated from the MEK-insoluble fraction, and the methanol-insoluble fraction is further separated from the MEK-soluble fraction. The graft ratio is then calculated by determining the ratio of the MEK-insoluble fraction to the total amount of the MEK-insoluble fraction and the methanol-insoluble fraction.

[0085] <Method for producing core-shell polymer particles> (Method of manufacturing the core layer) The core layer constituting the core-shell polymer particles (B) can be produced by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, or the like, and the method described in, for example, WO 2005 / 028546 can be used.

[0086] (Method of forming shell layer and intermediate layer) The intermediate layer can be formed by polymerizing a monomer for forming the intermediate layer by known radical polymerization. When the rubber elastic material constituting the core layer is obtained as an emulsion, the polymerization of the monomer for forming the intermediate layer is preferably carried out by emulsion polymerization.

[0087] The shell layer can be formed by polymerizing a monomer for forming the shell layer by known radical polymerization. When the core layer or the polymer particle precursor formed by coating the core layer with the intermediate layer is obtained as an emulsion, the polymerization of the monomer for forming the shell layer is preferably carried out by emulsion polymerization, and can be produced, for example, according to the method described in WO 2005 / 028546.

[0088] Examples of emulsifiers (dispersants) that can be used in emulsion polymerization include alkyl or aryl sulfonic acids (e.g., dioctyl sulfosuccinic acid and dodecylbenzenesulfonic acid), alkyl or aryl ether sulfonic acids, alkyl or aryl sulfuric acids (e.g., dodecyl sulfate), alkyl or aryl ether sulfuric acids, alkyl or aryl-substituted phosphoric acids, alkyl or aryl ether-substituted phosphoric acids, N-alkyl or aryl sarcosinic acids (e.g., dodecyl sarcosinic acid), alkyl or aryl carboxylic acids (e.g., oleic acid and stearic acid), alkyl or aryl ether carboxylic acids, and various acids, as well as anionic emulsifiers (dispersants) such as alkali metal salts or ammonium salts of these acids; nonionic emulsifiers (dispersants) such as alkyl or aryl-substituted polyethylene glycol; and dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives. These emulsifiers (dispersants) may be used alone or in combination of two or more.

[0089] It is preferable to use a small amount of emulsifier (dispersant) as long as it does not impair the dispersion stability of the aqueous latex of polymer particles. Furthermore, the more water-soluble the emulsifier (dispersant), the more preferable it is. High water solubility makes it easier to wash off the emulsifier (dispersant) with water, and can easily prevent adverse effects on the final cured product.

[0090] When emulsion polymerization is employed, known initiators, such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate, can be used as thermal decomposition initiators.

[0091] Alternatively, a redox initiator can be used which is a combination of a peroxide such as an organic peroxide such as t-butyl peroxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, or t-hexyl peroxide; or an inorganic peroxide such as hydrogen peroxide, potassium persulfate, or ammonium persulfate, optionally with a reducing agent such as sodium formaldehyde sulfoxylate or glucose, optionally with a transition metal salt such as iron (II) sulfate, optionally with a chelating agent such as disodium ethylenediaminetetraacetate, and optionally with a phosphorus-containing compound such as sodium pyrophosphate.

[0092] When a redox initiator system is used, polymerization can be carried out at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set over a wide range, which is preferable. Among these, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide are preferably used as redox initiators. The amount of the initiator used, and when a redox initiator is used, the amount of the reducing agent, transition metal salt, chelating agent, etc. used can be within known ranges. Furthermore, when polymerizing a monomer having two or more radically polymerizable double bonds, known chain transfer agents can be used within known ranges. Surfactants can also be used, but this is also within known ranges.

[0093] The polymerization conditions, such as polymerization temperature, pressure, and deoxidation, can be those within known ranges. The polymerization of the intermediate layer-forming monomer can be carried out in one stage or two or more stages. For example, the intermediate layer-forming monomer can be added all at once or continuously to the emulsion of the rubber elastomer that constitutes the elastic core layer. Alternatively, the intermediate layer-forming monomer can be added to a reactor that has already been charged with the intermediate layer-forming monomer, followed by polymerization.

[0094] When core-shell polymer particles are used as component (B), in order to balance the ease of handling of the resulting one-component curable resin composition and the toughness-improving effect of the resulting cured product, the content of the core-shell polymer particles is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, even more preferably 3 to 60 parts by weight, even more preferably 4 to 50 parts by weight, and particularly preferably 5 to 40 parts by weight, per 100 parts by weight of the epoxy resin (A).

[0095] <Blocked urethane> Blocked urethane, one embodiment of component (B), is an elastomer-type compound containing urethane and / or urea groups, in which all or some of the terminal isocyanate groups of a compound having terminal isocyanate groups have been capped with various blocking agents having active hydrogen groups. Compounds in which all of the terminal isocyanate groups have been capped with blocking agents are particularly preferred. Such compounds can be obtained, for example, by reacting an organic polymer having terminal active hydrogen-containing groups with an excess of a polyisocyanate compound to form a polymer (urethane prepolymer) having urethane and / or urea groups in the main chain and terminal isocyanate groups, and then, either simultaneously or afterward, capping all or some of the isocyanate groups with blocking agents having active hydrogen groups.

[0096] The blocked urethane may be, for example, a compound represented by the following general formula (1): A-(NR 2 -C(=O)-X) a (1) (Wherein, a number of R 2 are each independently a hydrocarbon group having 1 to 20 carbon atoms. a represents the average number of capped isocyanate groups per molecule, and is preferably 1.1 or more, more preferably 1.5 to 8, even more preferably 1.7 to 6, and particularly preferably 2 to 4. X is a residue obtained by removing an active hydrogen atom from the blocking agent. A is a residue obtained by removing a terminal isocyanate group from the urethane prepolymer.

[0097] The number average molecular weight of the blocked urethane, measured by GPC in terms of polystyrene, is preferably 2000 to 40000, more preferably 3000 to 30000, and particularly preferably 4000 to 20000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

[0098] (Organic polymer having terminal active hydrogen-containing groups) Examples of the main chain skeleton constituting the organic polymer having an active hydrogen-containing group at its terminal include polyether polymers, polyacrylic polymers, polyester polymers, polydiene polymers, saturated hydrocarbon polymers (polyolefins), and polythioether polymers.

[0099] (Active hydrogen-containing group) Examples of the active hydrogen-containing group constituting the organic polymer having an active hydrogen-containing group at its terminal include a hydroxyl group, an amino group, an imino group, and a thiol group. Among these, from the viewpoint of availability, a hydroxyl group, an amino group, and an imino group are preferred, and from the viewpoint of ease of handling (viscosity) of the resulting blocked urethane, a hydroxyl group is more preferred.

[0100] Examples of organic polymers having terminal active hydrogen-containing groups include polyether polymers (polyether polyols) having terminal hydroxyl groups, polyether polymers (polyether amines) having terminal amino and / or imino groups, polyacrylic polyols, polyester polyols, diene polymers (polydiene polyols) having terminal hydroxyl groups, saturated hydrocarbon polymers (polyolefin polyols) having terminal hydroxyl groups, polythiol compounds, and polyamine compounds. Among these, polyether polyols, polyether amines, and polyacrylic polyols are preferred because they have excellent compatibility with component (A), the glass transition temperatures of the organic polymers are relatively low, and the resulting cured products have excellent impact resistance at low temperatures. In particular, polyether polyols and polyether amines are more preferred because the resulting organic polymers have low viscosity and good workability, and polyether polyols are particularly preferred.

[0101] The organic polymer having an active hydrogen-containing group at its terminal, which is used when preparing the urethane prepolymer, which is a precursor of the blocked urethane, may be used alone or in combination of two or more kinds.

[0102] The number average molecular weight of the organic polymer having an active hydrogen-containing group at its terminal is preferably 800 to 7,000, more preferably 1,500 to 5,000, and particularly preferably 2,000 to 4,000, in terms of polystyrene-equivalent molecular weight measured by GPC.

[0103] (Polyether polymer) The polyether polymer essentially has the general formula (2): -R 1 -O- (2) (In the formula, R 1 is a linear or branched alkylene group having 1 to 14 carbon atoms.) 1 is preferably a linear or branched alkylene group having 1 to 14 carbon atoms, more preferably 2 to 4 carbon atoms. Specific examples of the repeating unit represented by general formula (2) include: -CH2O-, -CH2CH2O-, -CH2CH(CH3)O-, -CH2CH(C2H5)O-, -CH2C(CH3)2O-, -CH2CH2CH2CH2O- The main chain skeleton of the polyether polymer may consist of only one type of repeating unit, or two or more types of repeating units. In particular, those consisting of a polymer mainly composed of polypropylene glycol containing 50% by weight or more of propylene oxide repeating units are preferred from the viewpoint of T-peel adhesive strength. Furthermore, polytetramethylene glycol (PTMG) obtained by ring-opening polymerization of tetrahydrofuran is preferred from the viewpoint of dynamic splitting resistance.

[0104] (Polyether polyol, polyether amine) The polyether polyol is a polyether polymer having a hydroxyl group at its terminal, and the polyether amine is a polyether polymer having an amino group or an imino group at its terminal.

[0105] (Polyacrylic polyol) The polyacrylic polyol may be a polyol having a (meth)acrylic acid alkyl ester (co)polymer skeleton and a hydroxyl group in the molecule. In particular, a polyacrylic polyol obtained by copolymerizing a hydroxyl group-containing (meth)acrylic acid alkyl ester monomer such as 2-hydroxyethyl methacrylate is preferred.

[0106] (polyester polyol) Examples of the polyester polyol include polymers obtained by polycondensing a polybasic acid or anhydride thereof, such as maleic acid, fumaric acid, adipic acid, or phthalic acid, with a polyhydric alcohol, such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, or neopentyl glycol, in the presence of an esterification catalyst at a temperature of 150 to 270° C. Other examples include ring-opening polymers of ε-caprolactone or valerolactone, and active hydrogen compounds having two or more active hydrogen atoms, such as polycarbonate diol or castor oil.

[0107] (Polydiene polyol) Examples of the polydiene polyol include polybutadiene polyol, polyisoprene polyol, and polychloroprene polyol, with polybutadiene polyol being particularly preferred.

[0108] (Polyolefin polyol) Examples of the polyolefin polyol include polyisobutylene polyol and hydrogenated polybutadiene polyol.

[0109] (Polyisocyanate compounds) Specific examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene (tolylene) diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; and aliphatic polyisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated diphenylmethane diisocyanate. Among these, aliphatic polyisocyanates are preferred from the viewpoint of heat resistance, and isophorone diisocyanate and hexamethylene diisocyanate are more preferred from the viewpoint of availability.

[0110] (blocking agent) Examples of the blocking agent include primary amine-based blocking agents, secondary amine-based blocking agents, oxime-based blocking agents, lactam-based blocking agents, active methylene-based blocking agents, alcohol-based blocking agents, mercaptan-based blocking agents, amide-based blocking agents, imide-based blocking agents, heterocyclic aromatic compound-based blocking agents, hydroxy-functional (meth)acrylate-based blocking agents, and phenol-based blocking agents. Among these, oxime-based blocking agents, lactam-based blocking agents, hydroxy-functional (meth)acrylate-based blocking agents, and phenol-based blocking agents are preferred, hydroxy-functional (meth)acrylate-based blocking agents and phenol-based blocking agents are more preferred, and phenol-based blocking agents are even more preferred.

[0111] (Primary amine blocking agent) Examples of the primary amine blocking agents include butylamine, isopropylamine, dodecylamine, cyclohexylamine, aniline, and benzylamine. Examples of the secondary amine blocking agents include dibutylamine, diisopropylamine, dicyclohexylamine, diphenylamine, dibenzylamine, morpholine, and piperidine. Examples of the oxime blocking agents include formaldoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, and cyclohexane oxime. Examples of the lactam blocking agents include ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-butyrolactam. Examples of the active methylene blocking agents include ethyl acetoacetate and acetylacetone. Examples of the alcohol-based blocking agents include methanol, ethanol, propanol, isopropanol, butanol, amyl alcohol, cyclohexanol, 1-methoxy-2-propanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol, methyl glycolate, butyl glycolate, diacetone alcohol, methyl lactate, and ethyl lactate. Examples of the mercaptan-based blocking agents include butyl mercaptan, hexyl mercaptan, decyl mercaptan, t-butyl mercaptan, thiophenol, methylthiophenol, and ethylthiophenol. Examples of the amide-based blocking agents include acetic acid amide and benzamide. Examples of the imide-based blocking agents include succinimide and maleic acid imide. Examples of the heterocyclic aromatic compound-based blocking agent include imidazoles such as imidazole and 2-ethylimidazole; pyrroles such as pyrrole, 2-methylpyrrole, and 3-methylpyrrole; pyridines such as pyridine, 2-methylpyridine, and 4-methylpyridine; and diazabicycloalkenes such as diazabicycloundecene and diazabicyclononene.

[0112] (Hydroxy-functional (meth)acrylate-based blocking agent) The hydroxy-functional (meth)acrylate-based blocking agent is a (meth)acrylate having one or more hydroxyl groups. Specific examples of the hydroxy-functional (meth)acrylate-based blocking agent include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate.

[0113] (Phenol-based blocking agent) The phenolic blocking agent contains at least one phenolic hydroxyl group, i.e., a hydroxyl group directly bonded to a carbon atom of an aromatic ring. The phenolic compound may have two or more phenolic hydroxyl groups, but preferably contains only one phenolic hydroxyl group. The phenolic compound may contain other substituents, but these substituents preferably do not react with the isocyanate group under the conditions of the capping reaction, and alkenyl groups and allyl groups are preferred. Other substituents include alkyl groups such as linear, branched, or cycloalkyl; aromatic groups (e.g., phenyl, alkyl-substituted phenyl, alkenyl-substituted phenyl, etc.); aryl-substituted alkyl groups; and phenol-substituted alkyl groups. Specific examples of phenolic blocking agents include phenol, cresol, xylenol, chlorophenol, ethylphenol, allylphenol (particularly o-allylphenol), resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane), bisphenol F, bisphenol K, bisphenol M, tetramethylbiphenol, and 2,2'-diallyl-bisphenol A.

[0114] The blocking agent is preferably bonded to the end of the polymer chain of the urethane prepolymer in such a manner that the end to which it is bonded no longer has a reactive group. The blocking agents may be used alone or in combination of two or more.

[0115] The blocked urethane may contain residues of a crosslinking agent, residues of a chain extender, or both.

[0116] (Crosslinking agent) The crosslinking agent preferably has a molecular weight of 750 or less, more preferably 50 to 500, and is a polyol or polyamine compound having at least three hydroxyl groups, amino groups, and / or imino groups per molecule. The crosslinking agent is useful for imparting branching to the blocked urethane and increasing the functionality of the blocked urethane (i.e., the number of capped isocyanate groups per molecule).

[0117] (Chain extender) The molecular weight of the chain extender is preferably 750 or less, more preferably 50 to 500, and is a polyol or polyamine compound having two hydroxyl groups, amino groups, and / or imino groups per molecule. Chain extenders are useful for increasing the molecular weight of the blocked urethane without increasing the functionality.

[0118] Specific examples of the crosslinking agent or chain extender include trimethylolpropane, glycerin, trimethylolethane, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, sucrose, sorbitol, pentaerythritol, ethylenediamine, triethanolamine, monoethanolamine, diethanolamine, piperazine, and aminoethylpiperazine. Other examples include compounds having two or more phenolic hydroxyl groups, such as resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane), bisphenol F, bisphenol K, bisphenol M, tetramethylbiphenol, and 2,2'-diallyl-bisphenol A.

[0119] When a blocked urethane is used as component (B), in view of the balance between the heat resistance of the resulting cured product and the toughness-improving effect of the resulting cured product, the content of the blocked urethane is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, even more preferably 3 to 60 parts by weight, even more preferably 4 to 50 parts by weight, and particularly preferably 5 to 40 parts by weight, per 100 parts by weight of the epoxy resin (A).

[0120] As component (B), core-shell polymer particles and blocked urethane may be used in combination. In this case, in order to balance the ease of handling of the resulting one-component curable resin composition, the heat resistance of the resulting cured product, and the toughness-improving effect of the resulting cured product, the total content of the core-shell polymer particles and blocked urethane is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, even more preferably 3 to 60 parts by weight, even more preferably 4 to 55 parts by weight, and particularly preferably 5 to 50 parts by weight, per 100 parts by weight of epoxy resin (A). Furthermore, when used in combination, the ratio (by weight) of core-shell polymer particles to blocked urethane is preferably 0.1 to 10, more preferably 0.2 to 5, and particularly preferably 0.3 to 3.

[0121] <Compound (C) Having 1 to 3 Phenolic Hydroxyl Groups in One Molecule> The compound (C) having 1 to 3 phenolic hydroxyl groups per molecule is a component that controls the crosslink density of the epoxy resin (A) and thereby improves the impact peel adhesion of the cured product. This compound is hereinafter also referred to as the phenol compound (C).

[0122] The curing process of epoxy resins using dicyandiamide as a curing agent is believed to be as follows (see Takashi Kamon et al., Polymer Studies, Vol. 34, No. 7, pp. 537-543). When a composition containing epoxy resin (A) and dicyandiamide (D) is heated, first, the cyanamide produced from dicyandiamide (D) reacts with epoxy resin (A) to form linear polymers having hydroxyl and cyano groups. Next, the hydroxyl and cyano groups react within the linear polymers to form a three-dimensional crosslinked structure, which causes the composition to cure.

[0123] In this case, if a phenolic compound (C) is present, the phenolic hydroxyl groups of the phenolic compound (C) react with some of the cyano groups, inhibiting some of the reactions between the hydroxyl groups of the linear polymer and the cyano groups, thereby reducing the crosslink density of the three-dimensional crosslinked structure. This increases the molecular weight between crosslink points in the cured product, making the cured product more susceptible to plastic deformation and improving impact peel adhesion. On the other hand, if a compound (C) with four or more phenolic hydroxyl groups per molecule is used instead of one to three phenolic hydroxyl groups per molecule, the crosslink density increases, making the cured product brittle and reducing impact peel adhesion.

[0124] The phenol compound (C) may be any compound having 1 to 3 phenolic hydroxyl groups per molecule, and may or may not have a substituent other than the phenolic hydroxyl group on the aromatic ring. Substituents other than the phenolic hydroxyl group include, but are not limited to, hydrocarbon groups such as alkyl groups, alkenyl groups, aryl groups, and aralkyl groups, and halogens such as chlorine, bromine, and iodine. The number of carbon atoms in the hydrocarbon group is not particularly limited, and may be, for example, 1 to 20, preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. Among these, alkyl groups are preferred, t-butyl groups or methyl groups are more preferred, and methyl groups are particularly preferred, as they provide cured products with good properties.

[0125] Among the phenolic compounds (C), examples of compounds having one phenolic hydroxyl group include phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 4-ethylphenol, 2-propylphenol, 4-propylphenol, 4-isopropylphenol, 2,3,4-trimethylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,4,6-trimethylphenol, 2-tert-butylphenol, 3-tert -butylphenol, 4-tert-butylphenol, 2-methyl-6-tert-butylphenol, 3-methyl-6-tert-butylphenol, 6-tert-butyl-2,4-xylenol, 4-methyl-2-tert-butylphenol, 4-cyclohexylphenol, 2-cyclohexyl-5-methylphenol, 4-iodophenol, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-methoxyphenol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)octadecyl propionate, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)octadecyl propionate. Examples of compounds having two phenolic hydroxyl groups include resorcinol, catechol, 4-tert-butylcatechol, bisphenol A, tetrabromobisphenol A, bisphenol AP, bisphenol B, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol Z, hydroquinone, 2,5-dichlorohydroquinone, methylhydroquinone, tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,2'-diallylbisphenol A, 2,2'-methylenebisphenol, 2,2'-methylenebis(4-methylphenol), 4,4'-methylenebis(2-methylphenol), 4,4'-methylenebis(2,5-dimethyl phenol), 4,4'-methylenebis(2,6-dimethylphenol), 4,4'-isopropylidenebis(2-methylphenol), 4,4'-isopropylidenebis(2,6-dimethylphenol), 4,4'-biphenol, 2,2'-biphenol, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid)][ethylenebis(oxyethylene)], 2,2',6,6'-tetra-tert-butyl-4,4'-dihydroxybiphenyl, bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]thiobisethylene, bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]1,6-hexanediyl, and the like. Examples of compounds having three phenolic hydroxyl groups include pyrogallol, hydroxyquinol, phloroglucinol, 4,4',4''-ethylidynetrisphenol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, and 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene. The phenol compound (C) may be used alone or in combination of two or more kinds.

[0126] From the viewpoint of achieving both an improvement in impact peel adhesion and storage stability of the one-component curable resin composition, the phenol compound (C) is preferably a compound having one or two phenolic hydroxyl groups in one molecule.

[0127] From the viewpoint of improving both the impact peel adhesion and the heat resistance of the cured product, the phenol compound (C) is preferably a compound having two phenolic hydroxyl groups in one molecule. When a compound having two phenolic hydroxyl groups is used, the decrease in the glass transition temperature of the cured product is suppressed compared to when a compound having one phenolic hydroxyl group is used, and the impact peel adhesion can be improved.

[0128] From the viewpoint of the storage stability of the one-component curable resin composition and the moist heat resistance of the cured product, the phenol compound (C) is preferably a compound having one phenolic hydroxyl group in one molecule.

[0129] The phenolic compound (C) may be an unsubstituted phenolic compound, but is preferably a substituted phenolic compound. This is because the steric hindrance of the substituent can improve the storage stability of the one-component curable resin composition and the moist heat resistance of the cured product. The presence of a substituent on the aromatic ring of the phenolic compound (C) suppresses the reactivity of the phenolic hydroxyl group due to the steric hindrance, thereby improving the storage stability of the one-component curable resin composition. Furthermore, the presence of a substituent on the aromatic ring of the phenolic compound (C) suppresses hydrolysis by water molecules due to the steric hindrance, thereby improving the moist heat resistance of the cured product. Specifically, the phenolic compound (C) preferably has a substituent on the aromatic ring selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, and a halogen. From the viewpoint of improving storage stability due to the steric hindrance of the substituent, the substituent is more preferably a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, or a halogen, and particularly preferably a tertiary alkyl group. The number of the substituents is preferably 1 to 4, and more preferably 1 or 2, per molecule of the phenol compound (C).

[0130] Furthermore, it is more preferable that the substituent is bonded to the ortho-position of at least one phenolic hydroxyl group. The presence of a substituent at the ortho-position of the phenolic hydroxyl group more effectively suppresses the reactivity of the phenolic hydroxyl group due to steric hindrance, thereby improving the storage stability of the one-component curable resin composition. Furthermore, the presence of a substituent at the ortho-position of the phenolic hydroxyl group more effectively suppresses hydrolysis by water molecules due to steric hindrance, thereby improving the moist heat resistance of the cured product. From the viewpoints of the storage stability of the one-component curable resin composition and the moist heat resistance of the cured product, the phenolic compound (C) preferably has one or two substituents at the ortho-position of each phenolic hydroxyl group, and even more preferably has two substituents at the ortho-position of each phenolic hydroxyl group. When two substituents are present at the ortho-position of each phenolic hydroxyl group, it is preferable that the phenolic compound (C) has a tertiary alkyl group and a group selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, and a halogen, and particularly preferably has a methyl group and a tert-butyl group. Specific examples of such phenolic compounds (C) include 2-methyl-6-tert-butylphenol, 6-tert-butyl-2,4-xylenol, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid] [ethylenebis(oxyethylene)], and the like.

[0131] Furthermore, when two substituents are present at the ortho-positions of each phenolic hydroxyl group, the phenolic compound (C) may be a compound having tertiary alkyl groups at all ortho-positions of each phenolic hydroxyl group, i.e., a so-called hindered phenol. Such a phenolic compound has bulky tertiary alkyl groups on both sides of the phenolic hydroxyl group, and the steric hindrance thereof can further improve the storage stability of the one-component curable resin composition.

[0132] Examples of the compound having tertiary alkyl groups at all ortho positions of each phenolic hydroxyl group include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-methoxyphenol, 2,2',6,6'-tetra-tert-butyl-4,4'-dihydroxybiphenyl, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,6-di-tert-butyl-4-hydroxyphenylpropionate. Examples of suitable phenol compounds include octadecyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiobisethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexanediyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, and 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene. However, the phenol compound (C) may not be a phenol compound having tertiary alkyl groups at all ortho positions of each phenolic hydroxyl group.

[0133] However, even if a compound has 1 to 3 phenolic hydroxyl groups per molecule, a compound having an amino group in addition to the phenolic hydroxyl group does not fall under the phenolic compound (C) of the present application because it inhibits the storage stability required for a one-component curable resin composition. Examples of compounds having an amino group in addition to a phenolic hydroxyl group include 2,4,6-tris(dimethylaminomethyl)phenol and 2-(dimethylaminomethyl)phenol.

[0134] However, the one-component curable resin composition according to this embodiment may further contain, in addition to the phenolic compound (C), a compound having a phenolic hydroxyl group and an amino group in an amount that does not impair the storage stability of the composition. The amount that does not impair the storage stability of the composition is, for example, 0.1 parts by weight or less, preferably 0.05 parts by weight or less, and more preferably 0.01 parts by weight or less, per 100 parts by weight of the epoxy resin (A). However, it is preferable that the one-component curable resin composition according to this embodiment does not contain a compound having a phenolic hydroxyl group and an amino group.

[0135] The phenol compound (C) is preferably a low molecular weight phenol compound rather than a phenol resin, and the molecular weight of the low molecular weight phenol compound is preferably 90 or more and 500 or less.

[0136] The amount of phenolic compound (C) to be added satisfies the following conditions in order to obtain the effect of improving impact peel adhesion by adding the compound. When the phenolic compound (C) is a compound having one phenolic hydroxyl group per molecule, the ratio of the number of moles of phenolic hydroxyl groups in the phenolic compound (C) to the number of moles of CN groups generated from dicyandiamide (D) is 0.01 or more and 0.39 or less. If the ratio is less than 0.01, the effect of improving impact peel adhesion due to a decrease in crosslink density may be insufficient. If the ratio is greater than 0.39, the crosslink density may be too low, resulting in a decrease in the strength of the resulting cured product, and the effect of improving impact peel adhesion may be insufficient. In this case, the ratio is preferably 0.05 or more and 0.35 or less, more preferably 0.08 or more and 0.30 or less, and even more preferably 0.10 or more and 0.25 or less.

[0137] Furthermore, when the phenolic compound (C) is a compound having two or three phenolic hydroxyl groups per molecule, the ratio of the number of moles of phenolic hydroxyl groups in the phenolic compound (C) to the number of moles of CN groups generated from dicyandiamide (D) is 0.01 or more and 1.5 or less. If the ratio is less than 0.01, the crosslink density may be reduced, resulting in an insufficient improvement in impact peel adhesion. If the ratio is greater than 1.5, the crosslink density may be too low, resulting in a reduced strength of the resulting cured product, resulting in an insufficient improvement in impact peel adhesion. In this case, the ratio is preferably 0.20 or more and 1.4 or less, more preferably 0.30 or more and 1.3 or less, and even more preferably 0.60 or more and 1.0 or less. Dicyandiamide decomposes upon heating, generating two molecules of cyanamide (a compound having CN groups) from one molecule of dicyandiamide. The "number of moles of CN groups generated from dicyandiamide (D)" is the theoretical number of moles of CN groups contained in the cyanamide, calculated on the assumption that the entire amount of dicyandiamide is converted into cyanamide.

[0138] <Dicyandiamide (D)> Dicyandiamide (D) generates cyanamide upon heating, which enables crosslinking of the epoxy resin (A), and therefore can function as a latent curing agent that becomes active upon heating. By blending dicyandiamide (D), it is possible to form a one-component curable resin composition.

[0139] The amount of dicyandiamide (D) to be added can be appropriately set depending on the desired physical properties, but from the viewpoint of improving impact peel adhesion, it is preferably 2 to 20 parts by weight, more preferably 3 to 18 parts by weight, even more preferably 4 to 16 parts by weight, even more preferably 5 to 14 parts by weight, and particularly preferably 6 to 12 parts by weight, per 100 parts by weight of the epoxy resin (A).

[0140] Furthermore, from the viewpoint of improving the impact peel adhesion and suppressing the water absorption of the cured product, the ratio of the molar amount of dicyandiamide (D) to the molar amount of epoxy groups in the epoxy resin (A) is preferably 0.10 or more and 0.30 or less, more preferably 0.12 or more and 0.28 or less, and even more preferably 0.15 or more and 0.26 or less.

[0141] <Compound (E) having four or more phenolic hydroxyl groups in one molecule> In addition to components (A) to (D), the one-component curable resin composition of this embodiment may further contain a compound (E) having four or more phenolic hydroxyl groups per molecule. Examples of such compounds include novolac phenolic resins and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0142] The amount of compound (E) to be added can be determined appropriately by those skilled in the art, but from the viewpoint of impact peel adhesion, the ratio of the total weight of compound (E) to the total weight of phenol compound (C) is preferably less than 1, more preferably less than 0.5, and even more preferably less than 0.1. Compound (E) may not be added.

[0143] <Curing accelerator (F)> The one-component curable resin composition of this embodiment may contain a curing accelerator (F). The component (F) can accelerate the curing reaction between the epoxy resin (A) and dicyandiamide (D).

[0144] Examples of the (F) component include ureas such as p-chlorophenyl-N,N-dimethylurea (trade name: Monuron), 3-phenyl-1,1-dimethylurea (trade name: Phenuron), 3,4-dichlorophenyl-N,N-dimethylurea (trade name: Diuron), N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea (trade name: Chlortoluron), and 1,1-dimethylphenylurea (trade name: Dyhard); 6-caprolactam, etc. The (F) component may be used alone or in combination of two or more. The (F) component may be encapsulated or may be a latent component that becomes active only upon heating.

[0145] When the (F) component is blended, the blending amount of the (F) component is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, even more preferably 0.5 to 3 parts by weight, and particularly preferably 0.8 to 2 parts by weight, per 100 parts by weight of the epoxy resin (A), from the viewpoints of the effect of improving curability and storage stability.

[0146] <Reinforcer> The one-component curable resin composition of this embodiment may optionally contain an epoxy unmodified rubber polymer as a toughening agent for the purpose of further improving performance such as toughness, impact resistance, shear adhesion, peel adhesion, etc. The toughening agents may be used alone or in combination of two or more.

[0147] <Epoxy unmodified rubber polymer> If necessary, the rubber-based polymer may be contained in the one-component curable resin composition of this embodiment in an unmodified state without being reacted with the epoxy resin. Examples of the rubber-based polymer include acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber, and polyoxyalkylenes such as polypropylene oxide, polyethylene oxide, and polytetramethylene oxide. The rubber-based polymer preferably has a reactive group such as an amino group, a hydroxy group, or a carboxyl group at its terminal. Among these, NBR and polyoxyalkylenes are preferred from the viewpoint of the adhesiveness and impact peel adhesion resistance of the resulting one-component curable resin composition, with NBR being more preferred and carboxyl-terminated NBR (CTBN) being particularly preferred.

[0148] The glass transition temperature (Tg) of the rubber polymer is not particularly limited, but is preferably −25° C. or lower, more preferably −35° C. or lower, even more preferably −40° C. or lower, and particularly preferably −50° C. or lower.

[0149] The number average molecular weight of the rubber polymer, measured by GPC in terms of polystyrene, is preferably 1500 to 40000, more preferably 3000 to 30000, and particularly preferably 4000 to 20000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

[0150] The rubber polymers can be used alone or in combination of two or more kinds. The amount of the rubber polymer is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and particularly preferably 5 to 10 parts by weight, per 100 parts by weight of the epoxy resin (A). When the amount is 1 part by weight or more, the effects of improving toughness, impact resistance, adhesiveness, etc. are good, and when the amount is 50 parts by weight or less, the elastic modulus of the resulting cured product is high.

[0151] <Inorganic filler> The one-component curable resin composition of this embodiment may contain an inorganic filler, such as silicic acid and / or silicates, and specific examples thereof include dry silica, wet silica, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, and talc.

[0152] The dry silica is also called fumed silica, and examples thereof include hydrophilic fumed silica with no surface treatment, and hydrophobic fumed silica produced by chemically treating the silanol group portions of hydrophilic fumed silica with silane or siloxane. From the viewpoint of dispersibility in component (A), hydrophobic fumed silica is preferred.

[0153] Other inorganic fillers include reinforcing fillers such as dolomite and carbon black; heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, titanium oxide, ferric oxide, fine aluminum powder, zinc oxide, activated zinc white, and the like.

[0154] The inorganic filler is preferably surface-treated with a surface treatment agent, which improves the dispersibility of the inorganic filler in the composition, thereby improving various physical properties of the resulting cured product.

[0155] The inorganic fillers may be used alone or in combination of two or more. The amount of inorganic filler used is preferably 1 to 100 parts by weight, more preferably 2 to 70 parts by weight, even more preferably 5 to 40 parts by weight, and particularly preferably 7 to 20 parts by weight, per 100 parts by weight of component (A).

[0156] <Calcium oxide> The one-component curable resin composition of this embodiment may contain calcium oxide.

[0157] Calcium oxide reacts with the moisture in the one-component curable resin composition to remove it, thereby solving various problems with physical properties caused by the presence of moisture. For example, calcium oxide acts as an anti-bubble agent to prevent a decrease in adhesive strength due to moisture removal.

[0158] Calcium oxide can be surface-treated with a surface treatment agent. The surface treatment improves the dispersibility of calcium oxide in the composition. As a result, the physical properties of the resulting cured product, such as adhesive strength, are improved compared to when non-surface-treated calcium oxide is used. In particular, T-peel adhesion and impact peel adhesion are significantly improved. The surface treatment agent is not particularly limited, but a fatty acid is preferred.

[0159] The amount of calcium oxide used is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, even more preferably 0.5 to 3 parts by weight, and particularly preferably 1 to 2 parts by weight, per 100 parts by weight of component (A). When the amount is 0.1 part by weight or more, the moisture removal effect is good, and when it is 10 parts by weight or less, the strength of the resulting cured product is high. The calcium oxide may be used alone or in combination of two or more kinds.

[0160] <Radical curing resin> The one-component curable resin composition of this embodiment may contain a radical curable resin having two or more double bonds in the molecule, as needed. Furthermore, if necessary, a low-molecular-weight compound having at least one double bond in the molecule and a molecular weight of less than 300 may be added. When used in combination with the radical curable resin, the low-molecular-weight compound has the function of adjusting the viscosity, physical properties of the cured product, and curing speed, and functions as a so-called reactive diluent for the radical curable resin. Furthermore, a radical polymerization initiator may be added to the one-component curable resin composition of this embodiment. Here, the radical polymerization initiator is preferably a latent type that is activated by increasing the temperature (preferably, about 50°C to about 150°C).

[0161] Examples of the radical curable resin include unsaturated polyester resin, polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, polyether (meth)acrylate, and acrylated (meth)acrylate. These may be used alone or in combination. Specific examples of the radical curable resin include the compounds described in International Publication No. 2014-115778. Specific examples of the low molecular weight compound and the radical polymerization initiator include the compounds described in International Publication No. 2014-115778.

[0162] As described in International Publication No. 2010-019539, if a radical polymerization initiator is activated at a temperature different from the curing temperature of the epoxy resin, the selective polymerization of the radical curable resin enables partial curing of the one-component curable resin composition. This partial curing increases the viscosity of the composition after application, improving its wash-off resistance. Note that during the water shower process in vehicle production lines, the uncured adhesive composition may be partially dissolved, scattered, or deformed by the water pressure of the shower during the water shower process, adversely affecting the corrosion resistance of the applied steel sheet or reducing the rigidity of the steel sheet. The "wash-off resistance" refers to the ability to resist this problem. Furthermore, this partial curing can provide the ability to temporarily bond substrates together until the composition is fully cured. In this case, the free radical initiator is preferably activated by heating to 80°C to 130°C, more preferably 100°C to 120°C.

[0163] <Monoepoxide> The one-component curable resin composition of this embodiment may contain a monoepoxide as needed. The monoepoxide can function as a reactive diluent. Specific examples of monoepoxides include aliphatic glycidyl ethers such as butyl glycidyl ether, or aromatic glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether, ethers consisting of a glycidyl group and an alkyl group having 8 to 10 carbon atoms, such as 2-ethylhexyl glycidyl ether, ethers consisting of a glycidyl group and a phenyl group having 6 to 12 carbon atoms, which may be substituted with an alkyl group having 2 to 8 carbon atoms, such as p-tert-butylphenyl glycidyl ether, and ethers consisting of a glycidyl group and an alkyl group having 12 to 14 carbon atoms, such as dodecyl glycidyl ether, aliphatic glycidyl esters such as glycidyl (meth)acrylate and glycidyl maleate, glycidyl esters of aliphatic carboxylic acids having 8 to 12 carbon atoms, such as versatic acid glycidyl ester, neodecanoic acid glycidyl ester, and lauric acid glycidyl ester, and pt-butylbenzoic acid glycidyl ester.

[0164] When a monoepoxide is used, the amount used is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, and particularly preferably 1 to 5 parts by weight, per 100 parts by weight of component (A). When the amount is 0.1 part by weight or more, the viscosity-lowering effect is good, and when the amount is 20 parts by weight or less, physical properties such as adhesiveness are good.

[0165] <Photopolymerization initiator> Furthermore, when the one-component curable resin composition of this embodiment is photocured, a photopolymerization initiator may be added. Examples of such photopolymerization initiators include onium salts such as aromatic sulfonium salts and aromatic iodonium salts with anions such as hexafluoroantimonate, hexafluorophosphate, and tetraphenylborate, and photocationic polymerization initiators (photoacid generators) such as aromatic diazonium salts and metallocene salts. These photopolymerization initiators may be used alone or in combination of two or more.

[0166] <Other ingredients> In this embodiment, other ingredients may be used as needed, such as expanding agents such as azo-type chemical foaming agents and thermally expandable microballoons, fiber pulp such as aramid pulp, colorants such as pigments and dyes, extender pigments, UV absorbers, antioxidants, stabilizers (antigelling agents), plasticizers, leveling agents, defoamers, silane coupling agents, antistatic agents, flame retardants, lubricants, viscosity reducers, shrinkage reducing agents, organic fillers, thermoplastic resins, desiccants, dispersants, etc.

[0167] <Method for producing one-component curable resin composition> In an embodiment in which the one-component curable resin composition of the present embodiment contains an epoxy resin (A) that is a curable resin and a core-shell polymer as component (B), the composition is preferably a composition in which the core-shell polymer particles (B) are dispersed in the state of primary particles.

[0168] Various methods can be used to obtain a composition in which such core-shell polymer particles (B) are dispersed in the form of primary particles, including, for example, a method in which core-shell polymer particles obtained in an aqueous latex state are contacted with component (A) and then unnecessary components such as water are removed, or a method in which the core-shell polymer particles are extracted with an organic solvent, mixed with component (A), and then the organic solvent is removed. The method described in International Publication No. 2005 / 028546 is preferably used. Specifically, the production method preferably includes the following steps, in order: a first step: mixing an aqueous latex containing core-shell polymer particles (B) (specifically, a reaction mixture obtained after producing core-shell polymer particles by emulsion polymerization) with an organic solvent having a solubility in water of 5% by weight to 40% by weight at 20°C, followed by further mixing with excess water to aggregate the polymer particles; a second step: separating and recovering the aggregated core-shell polymer particles (B) from the liquid phase, then mixing them again with an organic solvent to obtain an organic solvent solution of the core-shell polymer particles (B); and a third step: mixing the organic solvent solution with component (A), followed by distilling off the organic solvent.

[0169] Component (A) is preferably liquid at 23°C, as this facilitates the third step. "Liquid at 23°C" means that the softening point is 23°C or lower, and the component exhibits flowability at 23°C.

[0170] The composition obtained through the above steps, in which the core-shell polymer particles (B) are dispersed in the state of primary particles in the component (A), is mixed with additional components (A), (C), and (D), and, if necessary, other components, to obtain a one-component curable resin composition according to this embodiment, in which the core-shell polymer particles (B) are dispersed in the state of primary particles.

[0171] On the other hand, powdery core-shell polymer particles (B) obtained by coagulation by a method such as salting out and then drying can be redispersed in component (A) using a disperser with high mechanical shear force, such as a triple paint roll, a roll mill, or a kneader. In this case, component (A) and component (B) can be efficiently dispersed by applying mechanical shear force at high temperature. The temperature during dispersion is preferably 50 to 200°C, more preferably 70 to 170°C, even more preferably 80 to 150°C, and particularly preferably 90 to 120°C.

[0172] The one-component curable resin composition of this embodiment has good storage stability, and therefore can be used as a one-liquid composition in which all of the components are blended in advance and then sealed and stored, and which is then applied and cured by heating or light irradiation.

[0173] <Cured product> A cured product can be obtained by curing the one-component curable resin composition of this embodiment. When the one-component curable resin composition contains core-shell polymer particles as component (B), the core-shell polymer particles (B) are uniformly dispersed in the cured product. In a preferred embodiment, the one-component curable resin composition has low viscosity, allowing the cured product to be obtained with good workability.

[0174] The cured product can be produced by mixing components (A) to (D) and, if necessary, other components, and heating the resulting mixture at a curing temperature described below. Mixing components (A) to (D) and, if necessary, other components also includes a mode in which a composition in which core-shell polymer particles (B) are dispersed in component (A) as primary particles is prepared in advance, as described above, and then additional components (A), (C), and (D) and, if necessary, other components are mixed with the composition. When producing the cured product by mixing the components, there is no need to perform a step of preliminarily reacting the epoxy resin (A) with the phenol compound (C) to polymerize the epoxy resin (A).

[0175] <Application method> The one-component curable resin composition of this embodiment can be applied to a substrate by any method. According to a preferred embodiment, it can be applied at a low temperature, such as room temperature, and can also be heated and applied as needed. The one-component curable resin composition of this embodiment has excellent storage stability and is therefore particularly useful for construction methods in which it is applied after heating.

[0176] The one-component curable resin composition of this embodiment can be extruded onto a substrate in the form of a bead, monofilament, or swirl using a coating robot, or can be applied mechanically using a caulking gun or other manual application means. The composition can also be applied to a substrate using a jet spray or streaming method. The one-component curable resin composition of this embodiment is applied to one or both substrates, and the substrates are brought into contact with each other so that the composition is positioned between them. The composition is then cured in this state to bond the two substrates. The viscosity of the one-component curable resin composition is not particularly limited. For the extrusion bead method, a viscosity of approximately 150 to 600 Pa·s at 45°C is preferred. For the swirl coating method, a viscosity of approximately 100 Pa·s at 45°C is preferred. For the high-volume coating method using a high-speed flow device, a viscosity of approximately 20 to 400 Pa·s at 45°C is preferred.

[0177] When the one-component curable resin composition of this embodiment is used as a vehicle adhesive, increasing the thixotropy of the composition is effective in improving the "resistance to washing off." Generally, thixotropy is improved by a thixotropy-imparting agent such as fumed silica or amide wax, and the lower the viscosity of the thermosetting resin component, which is the main component, the greater the effect of this improvement, resulting in a composition with good workability. The one-component curable resin composition of this embodiment is preferred because it is prone to low viscosity and therefore easy to increase the thixotropy. A highly thixotropic composition can be adjusted to a viscosity that allows application by heating.

[0178] Furthermore, in order to improve the "resistance to washing off," it is preferable to incorporate a polymeric compound having a crystalline melting point near the application temperature of the composition into the one-component curable resin composition, as described in International Publication No. 2005-118734. The composition has a low viscosity at the application temperature (making it easy to apply), but becomes highly viscous at the temperature required for the water shower rinse, improving the "resistance to washing off." Examples of the polymeric compound having a crystalline melting point near the application temperature include various polyester resins such as crystalline or semi-crystalline polyester polyols.

[0179] <Adhesive> When the one-component curable resin composition of the present embodiment is used as an adhesive to bond various substrates, it can bond substrates such as wood, metal, plastic, and glass. Bonding automobile parts is preferred, and bonding automobile frames to each other or bonding an automobile frame to another automobile part is more preferred. Examples of substrates include steel materials such as cold-rolled steel and hot-dip galvanized steel, aluminum materials such as aluminum and coated aluminum, general-purpose plastics, engineering plastics, and composite materials such as CFRP and GFRP, as well as various plastic substrates.

[0180] The one-component curable resin composition of this embodiment has excellent adhesiveness, and therefore a laminate obtained by sandwiching the one-component curable resin composition of this embodiment between a plurality of members including an aluminum substrate, laminating the members together, and then curing the one-component curable resin composition to bond the members is preferable because it exhibits high adhesive strength.

[0181] The one-component curable resin composition of this embodiment has excellent toughness and is therefore suitable for bonding different types of substrates having different linear expansion coefficients.

[0182] The one-component curable resin composition of this embodiment can also be used to bond aerospace components, particularly exterior metal components.

[0183] <Curing temperature> The curing temperature of the one-component curable resin composition of this embodiment is not particularly limited, but is preferably 50°C to 250°C, more preferably 80°C to 220°C, even more preferably 100°C to 200°C, and particularly preferably 130°C to 180°C.

[0184] When the one-component curable resin composition of the present embodiment is used as an automotive adhesive, it is preferable, from the viewpoint of shortening and simplifying the process, to apply the adhesive to an automotive part, then apply a coating, and bake and cure the coating while curing the adhesive at the same time.

[0185] <Application> The one-component curable resin composition of this embodiment is preferably used for adhesives such as structural adhesives for vehicles and aircraft, structural adhesives for wind power generation, paints, lamination materials with glass fibers, materials for printed wiring boards, solder resists, interlayer insulating films, build-up materials, adhesives for FPCs, electrical insulating materials such as encapsulants for electronic components such as semiconductors and LEDs, die bond materials, underfills, semiconductor packaging materials such as ACF, ACP, NCF, and NCP, and encapsulants for display and lighting devices such as liquid crystal panels, OLED lighting, and OLED displays. It is particularly useful as a structural adhesive for vehicles. [Example]

[0186] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0187] (Measurement of volume average particle size) The average particle size of the polybutadiene rubber particles in the polybutadiene rubber latex and the core-shell polymer particles in the core-shell polymer latex described in the Production Examples was measured by the following method. The volume average particle size (Mv) of the particles dispersed in the aqueous latex was measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). Samples diluted with deionized water were used as measurement samples. The measurements were performed by inputting the refractive index of water and the refractive index of each polymer particle, adjusting the sample concentration so that the measurement time was 600 seconds, and the signal level was within the range of 0.6 to 0.8.

[0188] 1. Formation of the core layer Production Example 1: Preparation of polybutadiene rubber latex (R-2) A pressure-resistant polymerization reactor was charged with 200 parts by weight of water, 0.03 parts by weight of tripotassium phosphate, 0.002 parts by weight of disodium ethylenediaminetetraacetate (EDTA), 0.001 parts by weight of ferrous sulfate heptahydrate (FE), and 1.55 parts by weight of sodium dodecylbenzenesulfonate (SDBS). The mixture was thoroughly purged with nitrogen while stirring to remove oxygen. Then, 100 parts by weight of butadiene (Bd) was added to the system, and the temperature was raised to 45°C. 0.03 parts by weight of paramenthane hydroperoxide (PHP) was added, followed by 0.10 parts by weight of sodium formaldehyde sulfoxylate (SFS). 0.025 parts by weight of PHP was added at 3, 5, and 7 hours after the start of polymerization. 0.0006 parts by weight of EDTA and 0.003 parts by weight of FE were added at 4, 6, and 8 hours after the start of polymerization. After 15 hours of polymerization, the remaining monomer was removed by volatilization under reduced pressure to terminate the polymerization, yielding a polybutadiene rubber latex (R-1) composed mainly of polybutadiene rubber. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 0.08 μm.

[0189] A pressure-resistant polymerization reactor was charged with 21 parts by weight of polybutadiene rubber latex (R-1) (containing 7 parts by weight of polybutadiene rubber), 185 parts by weight of deionized water, 0.03 parts by weight of tripotassium phosphate, 0.002 parts by weight of EDTA, and 0.001 parts by weight of FE. The mixture was thoroughly purged with nitrogen while stirring to remove oxygen. Then, 93 parts by weight of Bd was added to the system, and the temperature was raised to 45°C. 0.02 parts by weight of PHP, followed by 0.10 parts by weight of SFS, were added to initiate polymerization. Every 3 hours from the start of polymerization until 24 hours later, 0.025 parts by weight of PHP, 0.0006 parts by weight of EDTA, and 0.003 parts by weight of FE were added. After 30 hours of polymerization, the remaining monomer was removed under reduced pressure to volatilize and terminate the polymerization, yielding a polybutadiene rubber latex (R-2) composed primarily of polybutadiene rubber. The volume average particle size of the polybutadiene rubber particles contained in the obtained latex was 0.20 μm.

[0190] 2. Preparation of core-shell polymer latex (shell layer formation) Production Example 2-1: Preparation of core-shell polymer latex (L-1) A glass reactor equipped with a thermometer, stirrer, reflux condenser, nitrogen inlet, and monomer addition device was charged with 262 parts by weight of the polybutadiene rubber latex (R-2) prepared in Preparation Example 1 (containing 87 parts by weight of polybutadiene rubber particles) and 57 parts by weight of deionized water, and stirred at 60°C while purging with nitrogen. After adding 0.004 parts by weight of EDTA, 0.001 parts by weight of FE, and 0.2 parts by weight of SFS, a mixture of shell monomers (12 parts by weight of methyl methacrylate (MMA) and 1 part by weight of glycidyl methacrylate (GMA)) and 0.04 parts by weight of cumene hydroperoxide (CHP) was continuously added over 120 minutes. After the addition was completed, 0.04 parts by weight of CHP was added, and stirring was continued for an additional 2 hours to complete the polymerization, yielding an aqueous latex (L-1) containing core-shell polymer particles. The polymerization conversion of the monomer components was over 99%. The core-shell polymer particles contained in the aqueous latex (L-1) had a volume average particle diameter of 0.21 μm, and the content of epoxy groups in the total amount of the shell layer of the core-shell polymer particles was 0.5 mmol / g.

[0191] Production Example 2-2: Preparation of core-shell polymer latex (L-2) An aqueous latex (L-2) containing core-shell polymer particles was obtained in the same manner as in Production Example 2-1, except that the shell monomers were changed to 1 part by weight of MMA, 6 parts by weight of styrene (ST), 2 parts by weight of acrylonitrile (AN), and 4 parts by weight of GMA. The conversion rate of the monomer components was 99% or more. The volume average particle diameter of the core-shell polymer particles contained in the aqueous latex (L-2) was 0.21 μm. The epoxy group content relative to the total weight of the shell layer of the core-shell polymer particles was 2.2 mmol / g.

[0192] Production Example 2-3: Preparation of core-shell polymer latex (L-3) An aqueous latex (L-3) containing core-shell polymer particles was obtained in the same manner as in Production Example 2-1, except that the shell monomers were changed to 3 parts by weight of MMA, 6 parts by weight of ST, 2 parts by weight of AN, and 2 parts by weight of GMA. The conversion rate of the monomer components was 99% or more. The volume average particle diameter of the core-shell polymer particles contained in the aqueous latex (L-3) was 0.21 μm. The epoxy group content relative to the total amount of the shell layer of the core-shell polymer particles was 1.1 mmol / g.

[0193] Production Example 2-4: Preparation of core-shell polymer latex (L-4) An aqueous latex (L-4) containing core-shell polymer particles was obtained in the same manner as in Production Example 2-1, except that the shell monomers were changed to 4 parts by weight of MMA, 6 parts by weight of ST, 2 parts by weight of AN, and 1 part by weight of GMA. The conversion rate of the monomer components was 99% or more. The volume average particle diameter of the core-shell polymer particles contained in the aqueous latex (L-4) was 0.21 μm. The epoxy group content relative to the total amount of the shell layer of the core-shell polymer particles was 0.5 mmol / g.

[0194] Production Example 2-5: Preparation of core-shell polymer latex (L-5) An aqueous latex (L-5) containing core-shell polymer particles was obtained in the same manner as in Production Example 2-1, except that the shell monomers were changed to 5 parts by weight of MMA, 6 parts by weight of ST, and 2 parts by weight of AN. The conversion rate of the monomer components was 99% or more. The volume average particle diameter of the core-shell polymer particles contained in the aqueous latex (L-5) was 0.21 μm. The epoxy group content relative to the total amount of the shell layer of the core-shell polymer particles was 0 mmol / g.

[0195] 3. Preparation of dispersion (M) in which core-shell polymer particles (B) are dispersed in a curable resin Production Example 3-1: Preparation of Dispersion (M-1) 132 g of methyl ethyl ketone (MEK) was introduced into a 1 L mixing tank at 25 °C. While stirring, 132 g of the core-shell polymer latex (L-1) obtained in Production Example 2-1 (equivalent to 40 g of core-shell polymer particles) was added. After uniform mixing, 200 g of water was added at a feed rate of 80 g / min. After the feed was completed, stirring was promptly stopped, yielding a slurry liquid consisting of floating aggregates and an aqueous phase containing a portion of the organic solvent. Next, 360 g of the aqueous phase was discharged from the outlet at the bottom of the tank, leaving behind the aggregates containing a portion of the aqueous phase. 90 g of MEK was added to the resulting aggregates and mixed uniformly to obtain a dispersion in which the core-shell polymer particles (B) were uniformly dispersed. 60 g of epoxy resin (JER828: liquid bisphenol A-type epoxy resin, manufactured by Mitsubishi Chemical Corporation), component (A), was mixed with this dispersion. MEK was removed from this mixture using a rotary evaporator. In this way, a dispersion (M-1) in which the core-shell polymer particles (B) were dispersed in the epoxy resin (A) was obtained.

[0196] Production Example 3-2: Preparation of Dispersion (M-2) A dispersion (M-2) in which core-shell polymer particles (B) were dispersed in epoxy resin (A) was obtained in the same manner as in Production Example 3-1, except that (L-2) obtained in Production Example 2-2 was used instead of (L-1) as the core-shell polymer latex in Production Example 3-1.

[0197] Production Example 3-3: Preparation of Dispersion (M-3) A dispersion (M-3) in which core-shell polymer particles (B) were dispersed in epoxy resin (A) was obtained in the same manner as in Production Example 3-1, except that (L-3) obtained in Production Example 2-3 was used instead of (L-1) as the core-shell polymer latex in Production Example 3-1.

[0198] Production Example 3-4: Preparation of Dispersion (M-4) A dispersion (M-4) in which core-shell polymer particles (B) were dispersed in epoxy resin (A) was obtained in the same manner as in Production Example 3-1, except that (L-4) obtained in Production Example 2-4 was used instead of (L-1) as the core-shell polymer latex in Production Example 3-1.

[0199] Production Example 3-5: Preparation of Dispersion (M-5) A dispersion (M-5) in which core-shell polymer particles (B) were dispersed in epoxy resin (A) was obtained in the same manner as in Production Example 3-1, except that (L-5) obtained in Production Example 2-5 was used instead of (L-1) as the core-shell polymer latex in Production Example 3-1.

[0200] (Examples 1 to 60, Comparative Examples 1 to 24) Each component was weighed according to the formulation shown in Tables 1 to 9 and mixed thoroughly to obtain a one-component curable resin composition. For each composition in Tables 1 to 9, dynamic splitting resistance (impact peel adhesion) and its retention rate after a moist heat test, water absorption rate, T-peel adhesion strength and its retention rate after a moist heat test, and viscosity increase rate (storage stability) were evaluated using the following methods.

[0201] <Dynamic splitting resistance (impact-resistant peel adhesion) and its retention rate after moist heat test> Each composition was applied to two SPCC steel plates, which were then stacked so that the adhesive layer was 0.25 mm thick. The compositions shown in Tables 1 to 5 were cured at 170°C for 30 minutes, while the compositions shown in Tables 6 to 9 were cured at 150°C for 30 minutes to obtain a laminate. Using these laminates, dynamic splitting resistance (impact peel adhesion) was measured at 23°C in accordance with ISO 11343. The results are shown in Tables 1 to 9. For each of the compositions in Table 8, the dynamic fracture resistance was also measured after a damp heat test in which the laminate was left in an environment of 70°C / 95% RH for 21 days, and the retention rate (= strength after the damp heat test / strength before the damp heat test) was calculated. The results are shown in Table 8.

[0202] <Water absorption rate> Each of the compositions in Table 1 was defoamed and poured between two glass plates with a 3-mm-thick spacer, and cured at 170°C for 1 hour in a hot air oven to obtain a cured plate with a thickness of 3 mm. This cured plate was cut into a size of 3 mm × 5 mm × 50 mm to obtain a rectangular parallelepiped cured product. The weight of this rectangular parallelepiped cured product was measured before and after a damp heat test in which the cured product was left in an environment of 70°C / 95% RH for 7 days, and the water absorption rate (%) was calculated by the following formula. The results are shown in Table 1. Water absorption rate (%) = (weight after the damp heat test / weight before the damp heat test - 1) × 100

[0203] <T-peel adhesion strength and its retention rate after the damp heat test> Each of the compositions in Table 2, Tables 4 to 6, Table 8, and Table 9 was applied to two SPCC steel plates with a width of 25 mm × a length of 200 mm × a thickness of 0.5 mm, and the two plates were overlapped so that the adhesive layer thickness was 0.25 mm. For the compositions in Table 2 and Tables 4 to 5, they were cured under the condition of 170°C × 30 minutes, and for the compositions in Table 6 and Tables 8 to 9, they were cured under the condition of 150°C × 30 minutes to obtain a laminate. Under the measurement conditions where the measurement temperature was 23°C and the test speed was 254 mm / min, the T-peel adhesion strength with the unit of N / 25 mm was measured. The results are shown in Table 2, Tables 4 to 6, Table 8, and Table 9. For each of the compositions in Table 6 and Table 9, the T-peel adhesion strength was also measured after a damp heat test in which the laminate was left in an environment of 70°C / 95% RH for 21 days, and the retention rate (= strength after the damp heat test / strength before the damp heat test) was calculated. The results are shown in Table 6 and Table 9.

[0204] <Viscosity increase rate (storage stability)> The viscosity at 50°C of each of the compositions of Examples 17 to 21 and Comparative Example 8 in Table 2, each of the compositions of Examples 50 to 53 and Comparative Example 20 in Table 7, and each of the compositions of Examples 57 to 60 and Comparative Example 24 in Table 9 was measured using a rheometer at a shear rate of 5 s -1 Each composition was stored at 40°C for 14 days, and the viscosity after storage was measured at 50°C and a shear rate of 5 s in the same manner as before storage. -1 The viscosity increase rate (= viscosity after storage / viscosity before storage) was calculated and the results are shown in Tables 2, 7 and 9.

[0205] The various compounding ingredients used in Tables 1 to 9 are shown below. Table 10 shows the structural formula, molecular weight, and melting point of each compound (C) and comparative compound. <Epoxy resin (A)> A-1: JER828 (Mitsubishi Chemical, bisphenol A epoxy resin that is liquid at room temperature, epoxy equivalent: 184-194) A-2: HyPox RA 1340 (manufactured by CVC Thermoset Specialties, rubber-modified epoxy resin, epoxy equivalent: 350) A-3: EPU-73B (ADEKA, urethane-modified epoxy resin, epoxy equivalent: 245) <Dispersion (M) in which polymer particles (B) are dispersed in epoxy resin (A)> M-1 to M-5: Dispersions obtained in Production Examples 3-1 to 3-5 <Blocked Urethane (B)> B-1: ADEKA Resin QR-9466 (manufactured by ADEKA, blocked urethane, block NCO equivalent 1400g / eq) <Rubber polymer> Carboxyl-terminated acrylonitrile butadiene copolymer: CTBN 1300x8 (manufactured by CVC Thermoset Specialties) Carboxyl-terminated acrylonitrile butadiene copolymer: CTBN 1300x13 (manufactured by CVC Thermoset Specialties) <Compound (C) Having 1 to 3 Phenolic Hydroxyl Groups in One Molecule> 4-tert-butylphenol (Tokyo Chemical Industry Co., Ltd.) Bisphenol A (Tokyo Chemical Industry Co., Ltd.) Bisphenol M (Tokyo Chemical Industry Co., Ltd.) Phenol (Fujifilm Wako Pure Chemical Industries) 4-Methoxyphenol (Fujifilm Wako Pure Chemical Industries, Ltd.) 2,6-Xylenol (Fujifilm Wako Pure Chemical Industries, Ltd.) Resorcinol (Fujifilm Wako Pure Chemical Industries, Ltd.) Catechol (Fujifilm Wako Pure Chemical Industries, Ltd.) 4-tert-butylcatechol (Fujifilm Wako Pure Chemical Industries, Ltd.) Hydroquinone (Tokyo Chemical Industry Co., Ltd.) Methylhydroquinone (Fujifilm Wako Pure Chemical Industries) tert-Butylhydroquinone (Tokyo Chemical Industry Co., Ltd.) 2,5-Di-tert-butylhydroquinone (Tokyo Chemical Industry Co., Ltd.) 2,2'-Diallylbisphenol A (Konishi Chemical Industry Co., Ltd.) Pyrogallol (Kanto Chemical) 3-Methyl-6-tert-butylphenol (Tokyo Chemical Industry Co., Ltd.) 2-Methyl-6-tert-butylphenol (Tokyo Chemical Industry Co., Ltd.) Bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid)][ethylenebis(oxyethylene)] (BASF Japan, product name: Irganox 245) 6-tert-butyl-2,4-xylenol (Tokyo Chemical Industry Co., Ltd.) 2,3,6-trimethylphenol (Tokyo Chemical Industry Co., Ltd.) 2,6-di-tert-butylphenol (Tokyo Chemical Industry Co., Ltd.) <Phenol compounds not included in component (C)> 2,4,6-tris(dimethylaminomethyl)phenol (Tokyo Chemical Industry Co., Ltd.) PHENOLITE TD-2090 (DIC, novolac phenolic resin) <Non-phenolic compounds> Anisole (Kanto Chemical) <Dicyandiamide (D)> Dyhard 100S (manufactured by AlzChem) <Curing accelerator (F)> Dyhard UR200 (AlzChem, 1,1-dimethyl-3-(3,4-dichlorophenyl)urea) Dyhard UR300 (AlzChem, 1,1-dimethyl-3-phenylurea) <Fumed silica> CAB-O-SIL TS-720 (CABOT, fumed silica surface-treated with polydimethylsiloxane) <Calcium carbonate> Untreated heavy calcium carbonate: Whiten SB (Shiraishi Calcium, average particle size: 1.8 μm) Colloidal calcium carbonate: Vigot-10 (Shiraishi Kogyo Co., Ltd., average particle size: 0.17 μm) <Carbon black> MONARCH 280 (Cabot) <Calcium oxide> CML#31 (Omi Chemical Industry Co., Ltd.)

[0206] [Table 1]

[0207] From Table 1, it can be seen that the one-component curable resin compositions of Examples 1 to 9 containing components (A) to (D) gave cured products with good impact peel adhesion. On the other hand, the compositions of Comparative Examples 1, 6 to 7 do not contain the phenol compound (C) and have lower impact peel adhesion than Examples 1, 8, or 9, which have the same composition except for the component (C). The compositions of Comparative Examples 2 to 4 have a large ratio of the number of moles of phenolic hydroxyl groups in compound (C) to the number of moles of CN groups generated from dicyandiamide (D), i.e., the amount of compound (C) blended is relatively large, and the impact peel adhesion is extremely low. The composition of Comparative Example 5 contains anisole, an aromatic compound without a phenolic hydroxyl group, instead of the phenol compound (C), and has lower impact peel adhesion than Examples 1 to 9.

[0208] [Table 2(1)]

[0209] [Table 2(2)]

[0210] Table 2 shows that the one-component curable resin compositions of Examples 10 to 22 containing the phenol compound (C) have good impact peel adhesion and high T-peel adhesion strength compared to Comparative Example 8 which does not contain the (C) component. On the other hand, among Comparative Examples 9 and 10, which contain a phenolic compound that does not meet the definition of component (C), Comparative Example 10 had an impact peel adhesion value equal to or lower than Comparative Example 8, and a T-peel adhesion strength value equivalent to Comparative Example 8. Furthermore, in Comparative Example 9, the one-component curable resin composition gelled within just one hour after preparation, making it impossible to prepare an evaluation sample. This shows that phenolic compounds having an amino group reduce the stability of the composition and impair the storage stability that should be exhibited by a one-component curable resin composition. Furthermore, among Examples 17 to 21, Examples 19 to 21, especially Example 21, showed a low viscosity increase rate after storage at 40°C for 14 days, indicating that the storage stability of the one-component curable resin composition was relatively good. This is presumably due to the fact that the phenol compound (C) has a substituent on the aromatic ring, and further due to the number of the substituents.

[0211] [Table 3]

[0212] Table 3 shows that the one-component curable resin compositions of Examples 23 to 28, which contain a phenol compound (C), have better impact peel adhesion than Comparative Example 12, which does not contain the (C) component. On the other hand, Comparative Example 11, which does not contain the (B) component, has extremely poor impact peel adhesion. From the above, it can be seen that the improvement in impact peel adhesion is a synergistic effect achieved by the combined use of the (B) component and the (C) component.

[0213] [Table 4]

[0214] Table 4 shows that Example 29, which contains the phenolic compound (C), has better impact peel adhesion and higher T-peel bond strength than Comparative Example 13, which does not contain the phenolic compound (C) and has the same composition except for the (C) component. Similarly, Example 30 has better impact peel adhesion and higher T-peel bond strength than Comparative Example 14, Example 31 has higher impact peel adhesion than Comparative Example 15, Example 33 has higher impact peel adhesion than Comparative Example 16, and Example 34 has higher T-peel bond strength than Comparative Example 17. Furthermore, it is clear that the T-peel adhesive strength of Example 32 is improved by blending a rubber-based polymer, compared with Example 29, which has the same composition except for the rubber-based polymer.

[0215] [Table 5]

[0216] Table 5 shows that the one-component curable resin compositions of Examples 35 to 39 containing the phenol compound (C) have good impact peel adhesion and high T-peel adhesion strength compared to Comparative Example 18 which does not contain the (C) component.

[0217] [Table 6]

[0218] Table 6 shows that the one-component curable resin compositions of Examples 40 to 49 containing the phenol compound (C) have good impact peel adhesion and high T-peel adhesion strength compared to Comparative Example 19 which does not contain the (C) component. Furthermore, among Examples 40 to 49, Examples 41, 46, 47, and 49 exhibited a high retention rate of T-peel adhesive strength after the wet heat test, indicating that the resulting cured products had excellent wet heat resistance. This indicates that it is preferable for the phenol compound (C) to have a substituent at the ortho position of the phenolic hydroxyl group in order to improve wet heat resistance.

[0219] [Table 7]

[0220] Table 7 shows that the one-component curable resin compositions of Examples 50 to 53, which contain the phenol compound (C), have higher impact peel adhesion than Comparative Example 20, which does not contain the (C) component. Furthermore, the one-component curable resin compositions of Examples 50 to 53 exhibited a low viscosity increase rate after storage at 40°C for 14 days, indicating relatively good storage stability. This is presumably due to the fact that the phenolic compound (C) used has one tertiary alkyl group at the ortho position of each phenolic hydroxyl group. Among Examples 50 to 53, the one-component curable resin compositions of Examples 51 and 53 had particularly low viscosity increase rates and excellent storage stability, which is presumably due to the presence of a methyl group and a tertiary alkyl group at the ortho-position of each phenolic hydroxyl group in the phenolic compound (C) used.

[0221] [Table 8]

[0222] Table 8 shows that the one-component curable resin compositions of Examples 54 to 56 containing the phenol compound (C) have good impact peel adhesion and high T-peel adhesion strength compared to Comparative Examples 21 to 23 which do not contain the (C) component. Furthermore, Examples 54 to 56 exhibited a higher retention of impact peel adhesion after a wet heat test than Comparative Examples 21 to 23, indicating that the resulting cured products had excellent wet heat resistance. This is presumably due to the presence of a methyl group and a tertiary alkyl group at the ortho-position of each phenolic hydroxyl group in the phenolic compound (C) used.

[0223] [Table 9]

[0224] Table 9 shows that the one-component curable resin compositions of Examples 57 to 60, which contain the phenol compound (C), have good impact peel adhesion and high T-peel adhesion strength compared to Comparative Example 24, which does not contain the (C) component. Furthermore, Examples 57 to 60 showed a higher retention rate of T-peel adhesive strength after a wet heat test compared to Comparative Example 24, and Example 59 was particularly good, demonstrating that the resulting cured product had excellent wet heat resistance. This shows that, from the viewpoint of improving wet heat resistance, it is preferable for the phenolic compound (C) to have a substituent at the ortho-position of the phenolic hydroxyl group, and it is particularly preferable for the phenolic compound (C) to have a methyl group and a tertiary alkyl group at the ortho-position of the phenolic hydroxyl group. On the other hand, the one-component curable resin compositions of Examples 57 to 60 had a low viscosity increase rate after storage at 40°C for 14 days, and were found to have relatively good storage stability, with Examples 59 to 60 being even better and Example 60 being particularly excellent. This is presumably due to the number of substituents at the ortho-position of each phenolic hydroxyl group and the bulkiness of these substituents.

[0225] [Table 10(1)]

[0226]

Table 10(2)

Claims

1. 100 parts by weight of epoxy resin (A), 1 to 100 parts by weight of polymer particles and / or blocked urethane (B) having a core-shell structure, Compound (C) having 1 to 3 phenolic hydroxyl groups in one molecule [however, if the compound having 1 to 3 phenolic hydroxyl groups in one molecule further has an amino group, it does not fall under the category of compound (C)], and Contains dicyandiamide (D), the compound (C) has one or two substituents selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, and a halogen atom at the ortho-position of at least one phenolic hydroxyl group, a ratio of the number of moles of phenolic hydroxyl groups in the compound (C) to the number of moles of CN groups generated from dicyandiamide (D) is 0.01 or more and 0.39 or less when the compound (C) has one phenolic hydroxyl group in one molecule, and is 0.01 or more and 1.5 or less when the compound (C) has two or three phenolic hydroxyl groups in one molecule.

2. 100 parts by weight of epoxy resin (A), 1 to 100 parts by weight of polymer particles and / or blocked urethane (B) having a core-shell structure, a compound (C) having 1 to 3 phenolic hydroxyl groups in one molecule (provided that when the compound having 1 to 3 phenolic hydroxyl groups in one molecule further has an amino group, it does not fall under the category of compound (C)); Dicyandiamide (D), and containing a compound (E) having four or more phenolic hydroxyl groups in one molecule, the ratio of the number of moles of phenolic hydroxyl groups in the compound (C) to the number of moles of CN groups generated from dicyandiamide (D) is 0.01 or more and 0.39 or less when the compound (C) has one phenolic hydroxyl group in one molecule, and is 0.01 or more and 1.5 or less when the compound (C) has two or three phenolic hydroxyl groups in one molecule, A one-component curable resin composition, wherein the ratio of the total weight of the compound (E) to the total weight of the compound (C) is less than 1.

3. The one-component curable resin composition according to claim 2, wherein the compound (C) has one or two substituents selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, and a halogen at the ortho position of at least one phenolic hydroxyl group.

4. The one-component curable resin composition according to any one of claims 1 to 3, wherein the compound (C) has one or two phenolic hydroxyl groups in one molecule.

5. The one-component curable resin composition according to claim 4 , wherein the compound (C) has two phenolic hydroxyl groups in one molecule.

6. The one-component curable resin composition according to claim 4 , wherein the compound (C) has one phenolic hydroxyl group in one molecule.

7. The one-component curable resin composition according to any one of claims 1 to 6, wherein the compound (C) has 1 to 4 substituents on an aromatic ring selected from the group consisting of a methyl group, a primary alkyl group, a secondary alkyl group, a tertiary alkyl group, and a halogen.

8. The one-component curable resin composition according to any one of claims 1 to 7, wherein the molecular weight of the compound (C) is 90 or more and 500 or less.

9. The one-component curable resin composition according to any one of claims 1 to 8, wherein the ratio of the molar amount of the dicyandiamide (D) to the molar amount of the epoxy groups in the epoxy resin (A) is 0.10 or more and 0.30 or less.

10. The one-component curable resin composition according to any one of claims 1 to 9, further comprising 0.1 to 10 parts by weight of a curing accelerator (F) relative to 100 parts by weight of the epoxy resin (A).

11. The one-component curable resin composition according to any one of claims 1 to 10, wherein the component (B) contains polymer particles having the core-shell structure.

12. The one-component curable resin composition according to claim 11, wherein the polymer particles having a core-shell structure have a core layer made of one or more materials selected from the group consisting of diene-based rubbers, (meth)acrylate-based rubbers, and organosiloxane-based rubbers.

13. The one-component curable resin composition according to claim 12, wherein the diene rubber is a butadiene rubber and / or a butadiene-styrene rubber.

14. The one-component curable resin composition according to any one of claims 11 to 13, wherein the polymer particles having a core-shell structure have a shell layer formed by graft polymerizing one or more monomer components selected from the group consisting of an aromatic vinyl monomer, a vinyl cyan monomer, and a (meth)acrylate monomer onto a core layer.

15. The one-component curable resin composition according to any one of claims 11 to 14, wherein the polymer particles having a core-shell structure have an epoxy group in the shell layer.

16. The one-component curable resin composition according to claim 15, wherein the polymer particles having a core-shell structure have a shell layer formed by graft polymerizing a monomer component having an epoxy group onto a core layer.

17. The one-component curable resin composition according to claim 15 or 16, wherein the polymer particles having a core-shell structure have epoxy groups in a shell layer, and the content of the epoxy groups in the shell layer relative to the total amount of the shell layer is 0.1 to 2.0 mmol / g.

18. A cured product obtained by curing the one-component curable resin composition according to any one of claims 1 to 17.

19. An adhesive comprising the one-component curable resin composition according to any one of claims 1 to 17.

20. 20. The adhesive of claim 19, wherein the adhesive is a structural adhesive.

21. A laminate comprising two substrates and an adhesive layer formed by curing the adhesive according to claim 19 or 20, which bonds the two substrates together.

22. A method for producing the cured product according to claim 18, a step of mixing the epoxy resin (A), the polymer particles having a core-shell structure and / or the blocked urethane (B), the compound (C), and the dicyandiamide (D) to obtain a mixture; and a step of heating the mixture to obtain the cured product.

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