One-component curable resin composition and adhesive

Abstract

The present invention relates to a one-component curable resin composition containing: 100 parts by weight of an epoxy resin (A), 1 to 100 parts by weight of a polymer particle having a core-shell structure and / or a blocked urethane (B), a compound (C) having 1 to 3 phenolic hydroxyl groups in one molecule [wherein a compound having an amino group is not included in the compound (C)], and a dicyandiamide (D). The ratio of the number of moles of the phenolic hydroxyl groups of the compound (C) to the number of moles of CN groups generated from the dicyandiamide (D) is 0.01 or more and 0.39 or less when the compound (C) has one phenolic hydroxyl group, and 0.01 or more and 1.5 or less when it has two or three phenolic hydroxyl groups.

Description

Technical Field

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

[0002] Cured epoxy resins exhibit excellent properties in many aspects, including dimensional stability, mechanical strength, electrical insulation, heat resistance, water resistance, and chemical resistance. Therefore, they are widely used in civil engineering materials, electrical and electronic materials, and adhesives. However, cured epoxy resins suffer from low fracture toughness and exhibit extreme brittleness.

[0003] On the other hand, dicyandiamide can be heated to produce cyanamide, thereby functioning as a potential curing agent exhibiting activity as a curing agent. Therefore, it is known that by incorporating dicyandiamide into epoxy resins, one-component curable compositions can be formed.

[0004] Patent Document 1 describes an adhesive composition that exhibits high peel adhesion by containing epoxy resin, dicyandiamide as a curing agent, and microparticles of a specific particle size formed from a specific thermoplastic resin. In this document, core-shell particles were used in a comparative example.

[0005] Patent document 2 describes a one-component epoxy adhesive made by combining an epoxy compound containing liquid epoxy with three or more functions with fillers, core and shell toughening agents, and potential curing agents 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 phenolic curing agent with a specific structure, wherein the ratio of the amino-based curing agent to the phenolic curing agent is set to a specific range, and a prepreg formed using the epoxy resin composition.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2005-36095

[0010] Patent Document 2: Japanese Patent Application Publication No. 2019-11445

[0011] Patent Document 3: Japanese Patent Application Publication No. 2001-40069 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] As described in Patent Documents 1-3, the single-component curable compositions containing dicyandiamide in epoxy resin have insufficient impact-peel adhesion and there is room for improvement.

[0014] In view of the above, the object of the present invention is to provide a one-component curable resin composition incorporating epoxy resin and dicyandiamide, which yields a cured product exhibiting excellent impact-resistant peel adhesion.

[0015] Problem Solving Methods

[0016] In order to solve the above-mentioned problems, the inventors have repeatedly conducted in-depth research and found that by combining polymer particles with a core-shell structure and / or end-capped urethane (B), a specific phenolic compound (C), and dicyandiamide (D) in epoxy resin (A) in a specific ratio, a one-component curable resin composition that can form a cured product exhibiting excellent impact-resistant peel adhesion can be obtained.

[0017] That is, the present invention relates to a one-component curable resin composition comprising:

[0018] 100 parts by weight of epoxy resin (A)

[0019] 1-100 parts by weight of polymer particles with a core-shell structure and / or end-capped urethane (B)

[0020] Compounds having 1 to 3 phenolic hydroxyl groups per molecule (C) [wherein, if a compound having 1 to 3 phenolic hydroxyl groups per molecule is further having an amino group, it does not belong to the above-mentioned compound (C)], and

[0021] Dicyandiamide (D),

[0022] When the above compound (C) has one phenolic hydroxyl group in one molecule, the ratio of the number of moles of phenolic hydroxyl groups in the above 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 above compound (C) has two or three phenolic hydroxyl groups in one molecule, the ratio of the number of moles of phenolic hydroxyl groups in the above compound (C) to the number of moles of CN groups generated from dicyandiamide (D) is 0.01 or more and 1.5 or less.

[0023] Preferably, the above compound (C) has one or two phenolic hydroxyl groups in one molecule.

[0024] Preferably, the above compound (C) has 1 to 4 substituents selected from methyl, primary alkyl, secondary alkyl, tertiary alkyl and halogen on the aromatic ring.

[0025] Preferably, the above compound (C) has one or two substituents selected from methyl, primary alkyl, secondary alkyl, tertiary alkyl and halogen at the ortho position of at least one phenolic hydroxyl group.

[0026] Preferably, polymer particles with the core-shell structure described above are used as component (B).

[0027] Preferably, the molecular weight of the above compound (C) is 90 or more and 500 or less.

[0028] Preferably, it further contains a compound (E) having four or more phenolic hydroxyl groups in one molecule, and the ratio of the total weight of the above compound (E) to the total weight of the above compound (C) is less than 1.

[0029] 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.

[0030] Preferably, relative to 100 parts by weight of the epoxy resin (A), the single-component curable resin composition further contains 0.1 to 10 parts by weight of curing accelerator (F).

[0031] Preferably, the polymer particles with the core-shell structure have one or more core layers selected from diene rubber, (meth)acrylate rubber, and organosiloxane rubber.

[0032] The preferred diene rubbers are butadiene rubber and / or butadiene-styrene rubber.

[0033] Preferably, the polymer particles with the core-shell structure have a shell layer, which is formed by grafting and polymerizing one or more monomer components selected from aromatic vinyl monomers, vinyl cyanide monomers, and (meth)acrylate monomers with the core layer.

[0034] Preferably, the polymer particles with the core-shell structure have epoxy groups in the shell layer.

[0035] Preferably, the polymer particles with the core-shell structure have a shell layer, which is formed by grafting an epoxy-containing monomer component to the core layer.

[0036] Preferably, the polymer particles with the core-shell structure have epoxy groups in the shell layer, and the content of the epoxy groups in the shell layer is 0.1 to 2.0 mmol / g relative to the total amount of the shell layer.

[0037] In addition, the present invention also relates to a cured product, which is formed by curing the above-mentioned single-component curable resin composition.

[0038] Furthermore, the present invention also relates to an adhesive comprising the above-described single-component curable resin composition. Preferably, the adhesive is a structural adhesive.

[0039] In addition, the present invention also includes a laminate comprising two substrates and an adhesive layer for joining the two substrates, wherein the adhesive layer is formed by curing the adhesive.

[0040] Furthermore, the present invention also relates to a method for manufacturing the above-mentioned cured product, the method comprising:

[0041] The process of mixing the above-mentioned epoxy resin (A), the above-mentioned polymer particles having a core-shell structure and / or terminal urethane (B), the above-mentioned compound (C), and the above-mentioned dicyandiamide (D) to obtain a mixture; and

[0042] The process of heating the above mixture to obtain the above-mentioned cured product.

[0043] The effects of the invention

[0044] According to the present invention, the object is to provide a one-component curable resin composition incorporating epoxy resin and dicyandiamide, which yields a cured product exhibiting excellent impact-resistant peel adhesion. Detailed Implementation

[0045] The embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

[0046] This embodiment relates to a one-component curable resin composition, which contains at least an epoxy resin (A), polymer particles having a core-shell structure and / or a capped urethane (B), a compound having 1 to 3 phenolic hydroxyl groups per molecule (C), and dicyandiamide (D).

[0047] <Epoxy Resin (A)>

[0048] The single-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. Examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol S type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenolic varnish type epoxy resin, glycidyl ether type epoxy resin of bisphenol A propylene oxide adduct, hydrogenated bisphenol A (or F) type epoxy resin, fluorinated epoxy resin, flame-retardant epoxy resins such as glycidyl ether of tetrabromobisphenol A, glycidyl ether ester type epoxy resin of p-oxybenzoic acid, m-aminophenol type epoxy resin, diaminodiphenylmethane epoxy resin, various alicyclic epoxy resins, N,N-diglycidyl aniline, N,N-diglycidyl o-toluidine, triglycidyl aniline, etc. Epoxy resins include, but are not limited to, oil-based isocyanurates, divinylbenzene dioxide, resorcinol diglycidyl ether, polyalkylene glycol diglycidyl ether, glycol diglycidyl ether, diglycidyl esters of aliphatic polyacids, glycidyl ethers of di- or higher polyaliphatic alcohols such as glycerol, chelate-modified epoxy resins, rubber-modified epoxy resins, urethane-modified epoxy resins, hydantoin-type epoxy resins, epoxides of unsaturated polymers such as petroleum resins, amino-containing glycidyl ether resins, and epoxy compounds obtained by adding bisphenol A (or F) or polyacids to the above-mentioned epoxy resins via an addition reaction. Commonly used epoxy resins can also be used. These epoxy resins can be used alone or in combination of two or more.

[0049] More specifically, examples of the aforementioned polyalkylene glycol diglycidyl ethers include polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether. More specifically, examples of the aforementioned glycol diglycidyl ethers include neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and cyclohexanediol diglycidyl ether. More specifically, examples of the aforementioned diglycidyl esters of aliphatic polyacids include dimer acid diglycidyl esters, adipic acid diglycidyl esters, sebacic acid diglycidyl esters, and maleic acid diglycidyl esters. More specifically, examples of the aforementioned diglycidyl ethers of di- or higher polyaliphatic alcohols include trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, castor oil-modified polyglycidyl ether, propoxylated glycerol triglycidyl ether, and sorbitol polyglycidyl ether. Examples of epoxy compounds obtained by adding polybasic acids to epoxy resins include the addition reaction product of tall oil fatty acid dimer (dimer acid) and bisphenol A type epoxy resin as described in International Publication No. 2010-098950.

[0050] The aforementioned polyalkylene glycol diglycidyl ether, the aforementioned glycol diglycidyl ether, the aforementioned diglycidyl ester of aliphatic polyacid, and the aforementioned diglycidyl ether of di- or higher polyaliphatic alcohols, when used in combination with epoxy resins having relatively low viscosity, such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, function as reactive diluents, thereby improving the balance between the viscosity of the composition and the physical properties of the cured product. The content of the epoxy resin functioning as these reactive diluents is preferably 0.5 to 20% by weight in component (A), more preferably 1 to 10% by weight, and even more preferably 2 to 5% by weight.

[0051] The aforementioned chelate-modified epoxy resin is a reaction product of epoxy resin and a compound containing chelating functional groups (chelate ligands). When a one-component curable resin composition containing this chelate-modified epoxy resin is used as an adhesive for vehicles, adhesion to metal substrate surfaces contaminated with oily substances can be improved. A chelate functional group is a functional group in a compound that has multiple coordination teeth (coordination sites) within the molecule capable of coordinating with metal ions. Examples include phosphorus-containing acid groups (e.g., -PO(OH)2), carboxylic acid groups (-CO2H), sulfur-containing acid groups (e.g., -SO3H), amino groups, and hydroxyl groups (especially hydroxyl groups adjacent to each other in an aromatic ring). Examples of chelate ligands include ethylenediamine, bipyridine, ethylenediaminetetraacetic acid, phenanthroline, porphyrin, and crown ethers. Examples of commercially available chelate-modified epoxy resins include ADEKA resin EP-49-10N manufactured by ADEKA. (A) The amount of chelate-modified epoxy resin in component (A) is preferably 0.1 to 10% by weight, more preferably 0.5 to 3% by weight.

[0052] The aforementioned rubber-modified epoxy resin is a reaction product obtained by reacting rubber with an epoxy-containing compound, having an average of 1.1 or more, preferably 2 or more, epoxy groups per molecule. Examples of rubbers include acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber, polypropylene oxide, polyethylene oxide, polycyclobutane oxide, and other polyoxyethylene rubber-based polymers. These rubber-based polymers preferably have reactive groups such as amino, hydroxyl, or carboxyl groups at their terminals. The product obtained by reacting these rubber-based polymers with an epoxy resin in a suitable proportion using a known method is a rubber-modified epoxy resin. Among these, from the viewpoint of the adhesive properties and impact-peel adhesion of the resulting one-component cured resin composition, acrylonitrile-butadiene rubber-modified epoxy resin and polyoxyethylene-modified epoxy resin are preferred, with acrylonitrile-butadiene rubber-modified epoxy resin being more preferred. It should be noted that acrylonitrile-butadiene rubber modified epoxy resin is obtained, for example, by reacting carboxyl-terminated NBR (CTBN) with bisphenol A type epoxy resin.

[0053] From the viewpoint of the adhesive properties and impact-peel adhesion of the obtained one-component curable resin composition, the content of acrylonitrile monomer in the above-mentioned 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 the operability of the obtained one-component curable resin composition, it is particularly preferred to be 20 to 30% by weight.

[0054] Additionally, for example, the addition reaction product of amino-terminated polyoxyethylene and epoxy resin (hereinafter also referred to as "addition") is also included in the rubber-modified epoxy resin. The aforementioned addition can be easily manufactured, for example, by known methods as described in U.S. Patent No. 5,084,532, U.S. Patent No. 6,015,865, etc. Specific examples of the epoxy resin used in manufacturing the addition include the component (A) described above, preferably bisphenol A type epoxy resin, bisphenol F type epoxy resin, and more preferably bisphenol A type epoxy resin. Commercially available amino-terminated polyoxyethylenes used in manufacturing the addition include, for example, Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, Jeffamine D-4000, Jeffamine T-5000, etc., manufactured by Huntsman Corporation.

[0055] The number of reactive terminal groups of the epoxide per molecule of the above-mentioned rubber is preferably 1.5 to 2.5, more preferably 1.8 to 2.2. The number average molecular weight of the rubber, calculated as the equivalent molecular weight of polystyrene determined by GPC, is preferably 1,000 to 10,000, more preferably 2,000 to 8,000, and particularly preferably 3,000 to 6,000.

[0056] There are no particular limitations on the method for producing rubber-modified epoxy resin. For example, it can be produced by reacting rubber with an epoxy-containing compound in a large amount of epoxy-containing compound. Specifically, it is preferable to react with an amount of epoxy-containing compound of 2 equivalents or more relative to the average amount of epoxy reactive terminal groups in the rubber. More preferably, the reaction is carried out with a sufficient amount of epoxy-containing compound so that the resulting product is a mixture of rubber and an adduct of epoxy-containing compound, and free epoxy-containing compound. For example, rubber-modified epoxy resin can be produced by heating to a temperature of 100-250°C in the presence of a catalyst such as phenyl dimethylurea or triphenylphosphine. There are no particular limitations on the epoxy-containing compound used in the production of rubber-modified epoxy resin, but bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferred, and bisphenol A type epoxy resin is more preferred. It should be noted that if an excess of epoxy-containing compound is used in the production of rubber-modified epoxy resin, the unreacted epoxy-containing compound remaining after the reaction is not included in the rubber-modified epoxy resin described in this application.

[0057] For rubber-modified epoxy resins, the epoxy resin can be modified by pre-reacting with bisphenol components. The bisphenol component used for modification is preferably 3 to 35 parts by weight, more preferably 5 to 25 parts by weight, relative to 100 parts by weight of the rubber component in the rubber-modified epoxy resin. The cured product obtained by curing a one-component curable resin composition containing the modified rubber-modified epoxy resin exhibits excellent adhesive durability after high-temperature exposure and excellent impact resistance at low temperatures.

[0058] There is no particular limitation on the glass transition temperature (Tg) of the rubber-modified epoxy resin, but it is preferably below -25°C, more preferably below -35°C, further preferably below -40°C, and especially preferably below -50°C.

[0059] The number-average molecular weight of the rubber-modified epoxy resin, calculated based on the polystyrene-converted molecular weight as determined by GPC, is preferably 1,500 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. 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.

[0060] Rubber-modified epoxy resins can be used alone or in combination of two or more types.

[0061] (A) The amount of rubber-modified epoxy resin in the component is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, further preferably 5 to 30% by weight, and particularly preferably 10 to 20% by weight.

[0062] The aforementioned urethane-modified epoxy resin is a reaction product obtained by reacting a compound containing a group and an epoxy group that are reactive with an isocyanate group with a urethane prepolymer containing an isocyanate group. Each molecule has an average of 1.1 or more epoxy groups, 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.

[0063] The number-average molecular weight of the urethane-modified epoxy resin, calculated based on the polystyrene-converted molecular weight as determined by GPC, is preferably 1,500 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. 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.

[0064] Carbamate-modified epoxy resins can be used alone or in combination of two or more types.

[0065] (A) The amount of urethane-modified epoxy resin in the component is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, further preferably 5 to 30% by weight, and particularly preferably 10 to 20% by weight.

[0066] Among these epoxy resins, those having at least two epoxy groups per molecule are preferred due to their high curability, excellent flexibility after curing, and superior impact and peel resistance resulting from the combination of core and shell polymer particles (B). Compounds having two epoxy groups per molecule are particularly preferred.

[0067] Among the epoxy resins mentioned above, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferred because the cured products have high elastic modulus, excellent heat resistance and adhesion, and relatively low price. Bisphenol A type epoxy resin is particularly preferred.

[0068] In addition, among various epoxy resins, epoxy resins with an epoxy equivalent of less than 220 are preferred because the resulting cured product has high elastic modulus and heat resistance, and epoxy equivalents of 90 or more and less than 210 are even more preferred to be 150 or more and less than 200.

[0069] In particular, bisphenol A type epoxy resin and bisphenol F type epoxy resin with an epoxy equivalent of less than 220 are preferred because they are liquid at room temperature and the resulting single-component curable resin compositions have good processability.

[0070] If bisphenol A type epoxy resin or bisphenol F type epoxy resin with an epoxy equivalent of 220 or more and less than 5000 is added to component (A) in a range of preferably 40% by weight or less, more preferably 20% by weight or less, the resulting cured product has excellent impact resistance and is therefore preferred.

[0071] <Core-shell polymer particles and / or end-capped urethane (B)>

[0072] The one-component curable resin composition of this embodiment contains polymer particles with a core-shell structure and / or terminal urethane as component (B). Due to the toughness-improving effect of component (B), the resulting cured product exhibits excellent impact-peel adhesion. By combining component (B) with component (C), which will be described below, relative to components (A) and (D), the impact-peel adhesion of the cured product obtained from the one-component curable resin composition can be significantly improved through a synergistic effect. Component (B) may contain only polymer particles with a core-shell structure or only terminal urethane. Alternatively, both may be contained. Component (B) preferably contains at least polymer particles with a core-shell structure. Hereinafter, polymer particles with a core-shell structure will also be referred to as core-shell polymer particles.

[0073] <Core-shell polymer particles>

[0074] The core-shell polymer particles (B) may not have epoxy groups in the shell layer, but it is preferable that they do. From the viewpoint of the impact peel adhesion of the resulting cured product, the content of epoxy groups in the shell layer relative to the total amount of the core-shell polymer particles (B) shell layer 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. This suppresses the aggregation of the core-shell polymer particles (B) and prevents them from dispersing in the cured product as primary particles, presumably resulting in improved impact peel adhesion of the cured product.

[0075] The particle size of the core-shell polymer particles (B) is not particularly limited, but considering industrial production feasibility, the volume average particle size (Mv) is preferably 10–2000 nm, more preferably 30–600 nm, further preferably 50–400 nm, and particularly preferably 100–300 nm. It should be noted that the volume average particle size (Mv) of the polymer particles can be measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) to determine the latex content of the polymer particles.

[0076] In a one-component curable resin composition, a half-value width of 0.5 times to 1 times the volume average particle size in the number distribution of core-shell polymer particles (B) is preferred because the resulting one-component curable resin composition has low viscosity and is easy to handle.

[0077] From the viewpoint of easily achieving the aforementioned specific particle size distribution, it is preferable that the number distribution of the core-shell polymer particles (B) has two or more maxima. From the viewpoint of labor and cost during manufacturing, it is more preferable that it has two to three maxima, and even more preferable that it has two maxima. Particularly preferable is the presence of 10 to 90% by weight of core-shell polymer particles with 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 with a volume average particle size of 150 nm or more and less than 2000 nm.

[0078] The core-shell polymer particles (B) are preferably dispersed in the one-component curable resin composition in a primary particle state. In this application specification, "the core-shell polymer particles are dispersed in a primary particle state" (hereinafter also referred to as primary dispersion) means that the core-shell polymer particles are dispersed substantially independently (without contact) from each other, and their dispersion state can be confirmed, for example, by dissolving a portion of the one-component curable resin composition in a solvent such as methyl ethyl ketone and measuring its particle size using a particle size analyzer employing laser scattering.

[0079] The value of the volume average particle size (Mv) / number average particle size (Mn) based on the above particle size measurement is not particularly limited, but is preferably 3 or less, more preferably 2.5 or less, even more preferably 2 or less, and particularly preferably 1.5 or less. When the volume average particle size (Mv) / number average particle size (Mn) is 3 or less, it can be 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 adhesion, become good.

[0080] It should be noted that the volume average particle size (Mv) / number average particle size (Mn) can be determined by using a MicrotracUPA (manufactured by Nikkiso Corporation) and then dividing Mv by Mn.

[0081] Furthermore, "stable dispersion" of the core-shell polymer particles refers to a state in which the core-shell polymer particles do not aggregate, separate, or precipitate in the continuous layer, but remain stably dispersed over a long period under normal conditions. Additionally, it is preferable that the distribution of the core-shell polymer particles in the continuous layer remains substantially unchanged, and that "stable dispersion" can be maintained even when the composition is heated to reduce viscosity and stirred within a safe range.

[0082] The core-shell polymer particles (B) can be used alone or in combination of two or more.

[0083] The structure of the core-shell polymer particles (B) is not particularly limited, but it is preferable to have two or more layers. Alternatively, it may have a structure consisting of an intermediate layer covering the core layer and a shell layer further covering the intermediate layer, comprising three or more layers.

[0084] The following is a detailed description of each layer of the core-shell polymer particles (B).

[0085] Core Layer

[0086] To improve the toughness of the cured product of the single-component curable resin composition, the core layer is preferably an elastic core layer with rubber-like properties. To possess rubber-like properties, the gel content of the elastic core layer is preferably 60% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, and particularly preferably 95% by weight or more. It should be noted that the gel content mentioned in this specification refers to the ratio of the insoluble portion to the total amount of the insoluble and soluble portions when 0.5g of a product obtained through coagulation and drying is impregnated in 100g of toluene, allowed to stand at 23°C for 24 hours, and then separated from the soluble portion.

[0087] The core layer preferably comprises one or more selected from diene rubber, (meth)acrylate rubber, and organosiloxane rubber. Considering the improved impact peel adhesion of the resulting cured product and the reduced viscosity increase over time due to swelling of the core layer caused by component (A) because of its low affinity for epoxy resin (A), the core layer preferably comprises diene rubber.

[0088] (Diene-based rubber)

[0089] Examples of conjugated diene monomers constituting the aforementioned diene-based rubbers include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, and 2-methyl-1,3-butadiene. These conjugated diene monomers can be used alone or in combination of two or more.

[0090] The content of the aforementioned conjugated diene monomer is preferably in the range of 50-100% by weight in the core layer, more preferably in the range of 70-100% by weight, and even more preferably in the range of 90-100% 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.

[0091] Examples of vinyl monomers capable of copolymerizing with conjugated diene monomers include: vinyl aromatics 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; halogenated vinyls such as vinyl chloride, vinyl bromide, and chloroprene; vinyl acetate; olefins such as ethylene, propylene, butene, and isobutene; and multifunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. These vinyl monomers can be used alone or in combination of two or more. Styrene is particularly preferred.

[0092] The content of the vinyl monomers capable of copolymerizing with the conjugated diene monomers is preferably in the range of 0 to 50% by weight in the core layer, more preferably in the range of 0 to 30% by weight, and even more preferably in the range of 0 to 10% by weight. When the content of the vinyl monomers capable of copolymerizing with the conjugated diene monomers is 50% by weight or less, the impact peel adhesion of the resulting cured product can be improved.

[0093] Considering the improved impact resistance and peel adhesion, and the low affinity with epoxy resin (A) which reduces the likelihood of viscosity increase over time due to core swelling, diene-based rubbers are preferably butadiene rubbers using 1,3-butadiene and / or copolymers of 1,3-butadiene and styrene, i.e., butadiene-styrene rubber, and more preferably butadiene rubber. Furthermore, butadiene-styrene rubber is preferred because it allows for improved transparency of the cured product through refractive index adjustment.

[0094] ((meth)acrylate rubber)

[0095] The aforementioned (meth)acrylate-based rubber is preferably a rubber elastomer obtained by polymerizing a monomer mixture containing 50-100% by weight of at least one monomer selected from (meth)acrylate monomers and 0-50% by weight of other vinyl monomers capable of copolymerizing with (meth)acrylate monomers.

[0096] Examples of the above-mentioned (meth)acrylate monomers include: (i) methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, dodecyl methacrylate, and other alkyl methacrylates; (ii) phenoxyethyl methacrylate, benzyl methacrylate, and other (meth)acrylates containing aromatic rings; (iii) 2-hydroxyethyl methacrylate, methyl methacrylate, etc. (iv) Hydroxyalkyl methacrylates such as 4-hydroxybutyl acrylate; (v) Glycidyl methacrylate, glycidyl methacrylate, and other glycidyl methacrylates; (vi) Alkoxyalkyl methacrylates; (vii) Allyl methacrylate, allyl alkyl methacrylate, and other allyl methacrylates; (vii) Polyfunctional methacrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. These methacrylate monomers can be used alone or in combination of two or more. Ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate are preferred as methacrylate monomers.

[0097] Other vinyl monomers capable of copolymerizing with (meth)acrylate monomers include, for example: (i) vinyl aromatics 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) halogenated vinyls such as vinyl chloride, vinyl bromide, and chloroprene; (v) vinyl acetate; (vi) olefins such as ethylene, propylene, butene, and isobutene; and (vii) polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. These vinyl monomers can be used individually or in combination of two or more. Styrene is particularly preferred from the perspective of easily increasing the refractive index.

[0098] (Organosiloxane-based rubber)

[0099] Examples of the aforementioned organosiloxane-based rubbers include: (i) polysiloxane polymers composed of alkyl or aryl 2-substituted siloxane units such as dimethylsiloxy, diethylsiloxy, methylphenylsiloxy, diphenylsiloxy, and dimethylsiloxy-diphenylsiloxy; and (ii) polysiloxane polymers composed of alkyl or aryl 1-substituted siloxane units such as organohydrosiloxy with a portion of the side chain alkyl group replaced by a hydrogen atom. These polysiloxane polymers can be used individually or in combination of two or more. Dimethylsiloxy, methylphenylsiloxy, and dimethylsiloxy-diphenylsiloxy are preferred because they impart heat resistance to the cured product, and dimethylsiloxy is most preferred because it is readily available. In the case where the core layer is formed of organosiloxane-based rubber, in order not to impair the heat resistance of the cured product, the organosiloxane-based rubber is set to 100% by weight, and preferably contains 80% or more (more preferably 90% or more) of polysiloxane-based polymer.

[0100] To improve the toughness of the obtained cured product, the glass transition temperature (hereinafter sometimes simply referred to as "Tg") of the core layer is preferably below 0°C, more preferably below -20°C, further preferably below -40°C, and particularly preferably below -60°C.

[0101] Furthermore, the volume average particle size of the core layer is preferably 0.03 to 2 μm, more preferably 0.05 to 1 μm. Within this range, stable manufacturing is possible, and the heat resistance and impact resistance of the cured product are improved. It should be noted that the volume average particle size can be measured using a Microtrac UPA150 (manufactured by Nikkiso Corporation).

[0102] With the core and shell polymer particles comprising 100% by weight, the core layer preferably comprises 40–97% by weight, more preferably 60–95% by weight, further preferably 70–93% by weight, and particularly preferably 80–90% by weight. If the core layer comprises 40% by weight or more, the resulting cured product exhibits better impact-peel adhesion. If the core layer comprises 97% by weight or less, the core and shell polymer particles are less prone to aggregation, resulting in a lower viscosity in the single-component curable resin composition and improved workability.

[0103] The core layer is often a single-layer structure, but it can also be a multi-layer structure containing layers with rubber elasticity. Furthermore, in the case of a multi-layer core layer, the polymer composition of each layer can differ within the scope disclosed above.

[0104] The Intermediate Layer

[0105] An intermediate layer may be formed between the core layer and the shell layer as needed. In particular, a rubber surface cross-linking layer may be formed as the intermediate layer. Considering the improvement in toughness and impact peel adhesion of the resulting cured product, it is preferable to have no intermediate layer, and particularly preferable to have no rubber surface cross-linking layer.

[0106] When an intermediate layer is present, the ratio of the intermediate layer to the core layer in 100 parts by weight 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.

[0107] The aforementioned rubber surface crosslinking layer includes an intermediate layer polymer, which is formed by polymerizing a rubber surface crosslinking layer component comprising 30-100% by weight of a polyfunctional monomer having two or more free radical polymerizable double bonds within a molecule and 0-70% by weight of other vinyl monomers. This intermediate layer polymer has the effect of reducing the viscosity of the single-component curable resin composition and improving the dispersibility of the core-shell polymer particles (B) in component (A). Furthermore, it also has the effect of increasing the crosslinking density of the core layer or improving the grafting efficiency of the shell layer.

[0108] Specific examples of the aforementioned multifunctional monomers, excluding conjugated diene monomers such as butadiene, include allyl methacrylate, allyl alkyl methacrylate, and other allyl alkyl methacrylates; allyl methacrylate; multifunctional (meth)acrylates having two or more (meth)acryloyl groups, such as polyethylene 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, preferably allyl methacrylate and triallyl isocyanurate. In this application specification, (meth)acrylate refers to acrylates and / or methacrylates.

[0109] Shell

[0110] The outermost shell layer present in the core-shell polymer particles is formed by polymerizing the shell layer with monomers. The shell layer contains a shell polymer that performs the following functions: improving the compatibility of the core-shell polymer particles (B) with component (A) and enabling the core-shell polymer particles (B) to be dispersed in a primary particle state in a single-component curable resin composition or its cured product.

[0111] Such a shell polymer is preferably grafted with the aforementioned core layer and / or intermediate layer. It should be noted that, hereinafter, the phrase "grafted with the core layer" also includes grafting with the intermediate layer when an intermediate layer is formed within the core layer. More precisely, it is preferable that the monomeric components used to form the shell layer are grafted with the core polymer forming the core layer (in the case of an intermediate layer, the core polymer also includes the intermediate layer polymer forming the intermediate layer; the same applies hereinafter), substantially forming a chemical bond between the shell polymer and the core polymer (in the case of an intermediate layer, it is also preferable that the shell polymer is chemically bonded with the intermediate layer polymer). That is, it is preferable that the shell polymer is formed by grafting the aforementioned shell-forming monomers in the presence of the core polymer, thereby grafting with the core polymer to cover a portion or the entirety of the core polymer. This polymerization operation can be carried out by adding the shell polymer layer-forming monomers to the latex of the core polymer prepared in an aqueous polymer latex state and polymerizing it.

[0112] As the shell-forming monomer, from the perspective of the compatibility and dispersibility of the core-shell polymer particles (B) in the one-component curable resin composition, aromatic vinyl monomers, vinyl cyanide monomers, or (meth)acrylate monomers are preferred, and (meth)acrylate monomers are more preferred. Particularly preferred are shell-forming monomers comprising methyl methacrylate. These shell-forming monomers can be used alone or in appropriate combinations.

[0113] The total amount of aromatic vinyl monomers, vinyl cyanide monomers, and (meth)acrylate monomers is preferably 10 to 99.5% by weight, more preferably 50 to 99% by weight, further preferably 65 to 98% by weight, particularly preferably 67 to 90% by weight, and most preferably 67 to 85% by weight in 100% of the monomers for shell formation.

[0114] The content of methyl methacrylate in 100% by weight of the shell-forming monomer 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.

[0115] In order to ensure that the core-shell polymer particles (B) remain well dispersed in the cured product or single-component curable resin composition without agglomeration, from the viewpoint of chemically bonding with component (A), the monomer used for shell formation preferably contains a group selected from epoxy, oxetyl, hydroxyl, amino, imino, carboxylic acid, carboxylic anhydride, cyclic ester, cyclic amide, benzo[a] The monomer contains one or more reactive groups, including azino and cyanate groups, and is particularly preferred to be a monomer having an epoxy group.

[0116] From the viewpoint of impact resistance, peel adhesion, and storage stability, the monomer for shell formation preferably contains 0 to 90% by weight of an epoxy group-containing monomer, more preferably 1 to 50% by weight, further preferably 2 to 35% by weight, and particularly preferably 3 to 20% by weight.

[0117] Monomers with epoxy groups are preferably used for the formation of the shell, and more preferably for the shell only.

[0118] Furthermore, if a polyfunctional monomer having two or more free radical polymerizable double bonds is used as the shell-forming monomer, there is a tendency to prevent swelling of the core-shell polymer particles in the one-component curable resin composition, and the viscosity of the one-component curable resin composition is low, and its processability is improved, which is therefore preferred. On the other hand, considering the improvement in toughness and impact peel resistance of the obtained cured product, it is preferable not to use a polyfunctional monomer having two or more free radical polymerizable double bonds as the shell-forming monomer.

[0119] Of the 100% by weight of the monomer for shell formation, for example, 0 to 20% by weight of a multifunctional monomer may be included, preferably 1 to 20% by weight, and more preferably 5 to 15% by weight.

[0120] Specific examples of the aforementioned aromatic vinyl monomers include vinylbenzenes such as styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

[0121] Specific examples of the aforementioned vinyl cyanide monomers include acrylonitrile or methacrylonitrile.

[0122] Specific examples of the aforementioned (meth)acrylate monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; and hydroxyalkyl (meth)acrylates.

[0123] Specific examples of the aforementioned hydroxyalkyl methacrylates include: hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, and other hydroxyl linear alkyl methacrylates (especially hydroxyl linear C1-6 alkyl methacrylates); caprolactone-modified hydroxy(meth)acrylates; hydroxyl branched alkyl methacrylates such as methyl α-(hydroxymethyl)acrylate and ethyl α-(hydroxymethyl)acrylate; and mono(meth)acrylates containing hydroxyl groups, such as mono(meth)acrylates of polyester diols (especially saturated polyester diols) obtained from dicarboxylic acids (phthalic acid, etc.) and diols (propylene glycol, etc.).

[0124] Specific examples of the monomers containing epoxy groups mentioned above include glycidyl acrylate, 4-hydroxybutyl methacrylate glycidyl ether, allyl glycidyl ether, and other vinyl monomers containing glycidyl groups.

[0125] As a specific example of a polyfunctional monomer having two or more of the above-mentioned free radical polymerizable double bonds, monomers identical to the above-mentioned polyfunctional monomers can be exemplified, preferably allyl methacrylate or triallyl isocyanurate.

[0126] In this embodiment, for example, it is preferable to prepare a shell layer as a polymer of a polymer comprising 0-50 wt% (preferably 1-50 wt%, more preferably 2-48 wt%) of aromatic vinyl monomers (especially styrene), 0-50 wt% (preferably 0-30 wt%, more preferably 10-25 wt%) of vinyl cyanide monomers (especially acrylonitrile), 0-100 wt% (preferably 5-100 wt%, more preferably 70-95 wt%) of (meth)acrylate monomers (especially methyl methacrylate), and 1-50 wt% (preferably 2-35 wt%, more preferably 3-20 wt%) of epoxy-containing monomers (especially glycidyl methacrylate). This allows for a good balance between the desired improved toughness and mechanical properties.

[0127] These monomeric components can be used individually or in combination of two or more. In addition to the aforementioned monomeric components, the shell can also contain other monomeric components to form the shell.

[0128] The grafting rate of the shell layer is preferably 70% or more (more preferably 80% or more, and even more preferably 90% or more). When the grafting rate is 70% or more, the single-component curable resin composition can be made with a lower viscosity.

[0129] The grafting rate was calculated as described below. First, the aqueous latex containing the core-shell polymer particles was coagulated / dehydrated and then dried to obtain a powder of the core-shell polymer particles. Next, 2g of the core-shell polymer particle powder was impregnated in 100g of methyl ethyl ketone (MEK) at 23°C for 24 hours. The MEK-soluble and MEK-insoluble portions were then separated, and the methanol-insoluble portion was further separated from the MEK-soluble portion. The grafting rate was then calculated by determining the ratio of the MEK-insoluble portion to the total amount of the MEK-insoluble and methanol-insoluble portions.

[0130] Manufacturing Methods for Core-Shell Polymer Particles

[0131] (Core layer manufacturing method)

[0132] The core layer constituting the core-shell polymer particle (B) can be formed, for example, by emulsion polymerization, suspension polymerization, micro-suspension polymerization, etc., and can be manufactured by, for example, the method described in International Publication No. 2005 / 028546.

[0133] (Methods for forming the shell and intermediate layer)

[0134] The intermediate layer can be formed by polymerizing monomers for forming the intermediate layer using known free radical polymerization. When the rubber elastomer constituting the core layer is obtained in the form of an emulsion, the polymerization of the monomers for forming the intermediate layer is preferably carried out by emulsion polymerization.

[0135] The shell can be formed by polymerizing the shell-forming monomers using known free radical polymerization. When the core layer is obtained in the form of an emulsion, or when the core layer is formed by an intermediate layer covering the polymer particle precursor, the polymerization of the shell-forming monomers is preferably carried out by emulsion polymerization, for example, by the method described in International Publication No. 2005 / 028546.

[0136] In emulsion polymerization, suitable emulsifiers (dispersants) include dioctyl sulfosuccinic acid, alkyl or aryl sulfonic acids (such as dodecylbenzene sulfonic acid), alkyl or aryl ether sulfonic acids, alkyl or aryl sulfuric acid (such as dodecyl sulfuric acid), alkyl or aryl ether sulfuric acid, alkyl or aryl substituted phosphoric acid, alkyl or aryl ether substituted phosphoric acid, N-alkyl or aryl sarcosine (such as dodecyl sarcosine), oleic acid, alkyl or aryl carboxylic acids (such as stearic acid), alkyl or aryl ether carboxylic acids, and various acids 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) can be used alone or in combination of two or more.

[0137] To minimize the amount of emulsifier (dispersant), it is preferable to reduce the amount used, provided it does not affect the dispersion stability of the aqueous latex of polymer particles. Furthermore, higher water solubility of the emulsifier (dispersant) is preferred. Higher water solubility facilitates the removal of the emulsifier (dispersant) through water washing, easily preventing adverse effects on the final cured product.

[0138] When using emulsion polymerization, known initiators such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate can be used as thermally decomposable initiators.

[0139] Alternatively, a redox initiator combination can be used, which incorporates organic peroxides such as isopropyl tert-butyl peroxide, p-menthol peroxide, cumene peroxide, dicumene peroxide, tert-butyl peroxide, di-tert-butyl peroxide, and tert-hexyl peroxide; inorganic peroxides such as hydrogen peroxide, potassium persulfate, and ammonium persulfate; reducing agents such as sodium formaldehyde sulfoxylate and glucose as needed; transition metal salts such as ferric sulfate (II) as needed; chelating agents such as disodium ethylenediaminetetraacetate as needed; and phosphorus-containing compounds such as sodium pyrophosphate as needed.

[0140] When using a redox initiator system, polymerization can be carried out at low temperatures where the peroxides do not substantially undergo thermal decomposition, allowing the polymerization temperature to be set over a wide range, which is therefore preferable. Specifically, organic peroxides such as cumene hydroperoxide, dicumene hydroperoxide, and tert-butyl hydroperoxide are preferred as redox initiators. The amounts of the initiator, and the amounts of the reducing agent / transition metal salt / chelating agent, etc., when using a redox initiator, can be used within known ranges. Furthermore, when polymerizing monomers having two or more free radical polymerizable double bonds, known chain transfer agents can be used within known ranges. Surfactants can also be added, which are also within known ranges.

[0141] The polymerization temperature, pressure, deoxidation, and other conditions during polymerization can be within a known range. Furthermore, the polymerization of the intermediate layer forming monomer can be carried out in one stage or in two or more stages. For example, in addition to methods such as adding the intermediate layer forming monomer to the emulsion of the rubber elastomer constituting the elastic core layer in a single step or a continuous addition method, methods such as adding the emulsion of the rubber elastomer constituting the elastic core layer to a reactor pre-added with the intermediate layer forming monomer, and then carrying out polymerization, are also possible.

[0142] When using core-shell polymer particles as component (B), in order to balance the ease of processing the obtained single-component curable resin composition with the toughness improvement effect of the obtained cured product, the content of core-shell polymer particles relative to 100 parts by weight of epoxy resin (A) is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, further 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.

[0143] <Terminated carbamates>

[0144] As a component (B), the terminal urethane is an elastomeric compound containing urethane and / or urea groups and having isocyanate groups at the ends, all or part of which isocyanate groups are capped by various capping agents having active hydrogen groups. Particularly preferred are compounds in which all of the terminal isocyanate groups are capped by a capping agent. Such compounds are obtained, for example, by reacting an excess of a polyisocyanate compound with an organic polymer having active hydrogen groups at the ends to produce a polymer (urethane prepolymer) having urethane and / or urea groups in the main chain and isocyanate groups at the ends, or by simultaneously capping all or part of the isocyanate groups with a capping agent having active hydrogen groups.

[0145] The above-mentioned capped carbamates are represented, for example, by the following general formula (1):

[0146] A-(NR 2 -C(=O)-X) a (1)

[0147] (where a is a R) 2 Each is independently a hydrocarbon group having 1 to 20 carbon atoms. 'a' represents the average number of terminal isocyanate groups per molecule, preferably 1.1 or more, more preferably 1.5 to 8, further preferably 1.7 to 6, and particularly preferably 2 to 4. 'X' is the residue remaining after removing active hydrogen atoms from the above-mentioned capping agent. 'A' is the residue remaining after removing terminal isocyanate groups from the above-mentioned urethane prepolymer.

[0148] The number-average molecular weight of the capped urethane, converted from the molecular weight of polystyrene as determined by GPC, is preferably 2,000 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. 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.

[0149] (Organic polymers with active hydrogen groups at the ends)

[0150] Examples of polymers that form the backbone of organic polymers with active hydrogen groups at the ends include polyether polymers, polyacrylic acid polymers, polyester polymers, polydiene polymers, saturated hydrocarbon polymers (polyolefins), and polysulfide polymers.

[0151] (Contains active hydrogen groups)

[0152] Examples of active hydrogen groups constituting organic polymers having active hydrogen groups at their ends include hydroxyl, amino, imino, and thiol groups. Among these, hydroxyl, amino, and imino groups are preferred from the perspective of availability, and hydroxyl groups are more preferred from the perspective of the processability (viscosity) of the resulting capped urethane.

[0153] Examples of organic polymers having active hydrogen groups at the ends include polyether polymers (polyether polyols) with hydroxyl groups at the ends, polyether polymers (polyether amines) with amino and / or imino groups at the ends, polyacrylic acid polyols, polyester polyols, diene polymers (polydiene polyols) with hydroxyl groups at the ends, saturated hydrocarbon polymers (polyolefin polyols) with hydroxyl groups at the ends, polythiol compounds, and polyamine compounds. Among these, polyether polyols, polyether amines, and polyacrylic acid polyols are preferred because they have excellent compatibility with component (A), relatively low glass transition temperatures, and excellent impact resistance at low temperatures in the resulting cured products. 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 especially preferred.

[0154] The organic polymers with active hydrogen groups at the ends used in preparing the above-mentioned urethane prepolymers as precursors of end-capped urethanes can be used alone or in combination of two or more.

[0155] The number-average molecular weight of the organic polymer having active hydrogen groups at the ends is preferably 800 to 7000, more preferably 1500 to 5000, and particularly preferably 2000 to 4000, based on the polystyrene equivalent molecular weight determined by GPC.

[0156] (Polyether polymers)

[0157] The above-mentioned polyether polymers are essentially polymers having repeating units as shown in general formula (2):

[0158] -R 1 -O-(2)

[0159] (where R is in the formula) 1 It is a straight-chain or branched alkylene group having 1 to 14 carbon atoms. ), R in general formula (2) 1 Preferably, it is a straight-chain or branched alkylene group having 1 to 14 carbon atoms, more preferably 2 to 4. Specific examples of the repeating unit shown in general formula (2) can be given as follows:

[0160] -CH2O-, -CH2CH2O-, -CH2CH(CH3)O-, -CH2CH(C2H5)O-, -CH2C(CH3)2O-, -CH2CH2CH2CH2O-.

[0161] The backbone of polyether polymers may contain only one repeating unit or two or more repeating units. Particularly from the viewpoint of T-peel bond strength, polymers containing polypropylene glycol as the main component at 50% by weight or more of repeating units having propylene oxide are preferred. Furthermore, polytetramethylene glycol (PTMG), obtained by ring-opening polymerization of tetrahydrofuran, is preferred from the viewpoint of dynamic fracture resistance.

[0162] (Polyether polyols, polyether amines)

[0163] The aforementioned polyether polyols are polyether polymers with hydroxyl groups at the ends, and the aforementioned polyether amines are polyether polymers with amino or imino groups at the ends.

[0164] (Polyacrylate polyol)

[0165] Examples of the aforementioned polyacrylate polyols include those with an alkyl (meth)acrylate (co)polymer as the backbone and containing hydroxyl groups within the molecule. Polyacrylate polyols obtained by copolymerizing alkyl (meth)acrylate monomers containing hydroxyl groups, such as 2-hydroxyethyl methacrylate, are particularly preferred.

[0166] (Polyester Polyol)

[0167] Examples of the aforementioned polyester polyols include polymers obtained by polycondensation of polyacids such as maleic acid, fumaric acid, adipic acid, and phthalic acid, and their anhydrides, with polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and neopentyl glycol in the presence of an esterification catalyst at a temperature range of 150–270°C. Other examples include ring-opening polymers such as ε-caprolactone and valerate, polycarbonate diol, and active hydrogen compounds such as castor oil, which possess two or more active hydrogen atoms.

[0168] (Polydiene polyols)

[0169] Examples of polydiene polyols include polybutadiene polyol, polyisoprene polyol, and polychloroprene polyol, with polybutadiene polyol being particularly preferred.

[0170] (Polyolefin polyols)

[0171] Examples of polyolefin polyols mentioned above include polyisobutylene polyol and hydrogenated polybutadiene polyol.

[0172] (Polyisocyanate compounds)

[0173] Specific examples of the aforementioned polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and phenyl dimethyl 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 perspective of heat resistance, and isophorone diisocyanate and hexamethylene diisocyanate are more preferred from the perspective of availability.

[0174] (End-capping agent)

[0175] Examples of such end-capping agents include primary amine end-capping agents, secondary amine end-capping agents, oxime end-capping agents, lactam end-capping agents, active methylene end-capping agents, alcohol end-capping agents, thiol end-capping agents, amide end-capping agents, imide end-capping agents, heterocyclic aromatic compound end-capping agents, hydroxyl-functional (meth)acrylate end-capping agents, and phenolic end-capping agents. Among these, oxime end-capping agents, lactam end-capping agents, hydroxyl-functional (meth)acrylate end-capping agents, and phenolic end-capping agents are preferred, more preferably hydroxyl-functional (meth)acrylate end-capping agents and phenolic end-capping agents, and even more preferably phenolic end-capping agents.

[0176] (Primary amine capping agent)

[0177] Examples of primary amine end-capping agents include butylamine, isopropylamine, dodecylamine, cyclohexylamine, aniline, and benzylamine. Examples of secondary amine end-capping agents include dibutylamine, diisopropylamine, dicyclohexylamine, diphenylamine, dibenzylamine, morpholine, and piperidine. Examples of oxime end-capping agents include formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, diacetyl monooxime, and cyclohexane oxime. Examples of lactam end-capping agents include ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-butyrolactam. Examples of active methylene end-capping agents include ethyl acetoacetate and acetylacetone. Examples of alcohol-based end-capping agents include methanol, ethanol, propanol, isopropanol, butanol, pentanol, 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 thiol-based end-capping agents include butyl mercaptan, hexyl mercaptan, decyl mercaptan, tert-butyl mercaptan, thiophenol, methyl thiophenol, and ethyl thiophenol. Examples of amide-based end-capping agents include acetamide and benzamide. Examples of imide-based end-capping agents include succinic imide and maleic imide. Examples of end-capping agents for the aforementioned heterocyclic aromatic compounds include imidazoles such as imidazole and 2-ethylimidazole, pyrroles such as 2-methylpyrrole and 3-methylpyrrole, pyridines such as pyridine, 2-methylpyridine and 4-methylpyridine, and diazabicycloundecene and diazabicyclononene, among others.

[0178] (Hydroxy-functional (meth)acrylate end-capping agent)

[0179] The aforementioned hydroxyl-functional (meth)acrylate end-capping agents are (meth)acrylates having one or more hydroxyl groups. Specific examples of hydroxyl-functional (meth)acrylate end-capping agents include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate.

[0180] (Phenolic capping agent)

[0181] The aforementioned phenolic end-capping agents contain at least one phenolic hydroxyl group, i.e., a hydroxyl group directly bonded to a carbon atom of the aromatic ring. The phenolic compound may have two or more phenolic hydroxyl groups, but preferably only one. The phenolic compound may contain other substituents, which preferably do not react with the isocyanate group under the end-capping reaction conditions, and are preferably alkenyl or allyl. Examples of other substituents include linear, branched, or cycloalkyl groups; 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 end-capping agents include phenol, cresol, xylenol, chlorophenol, ethylphenol, allylphenol (especially 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.

[0182] The aforementioned end-capping agent is preferably bonded to the end of the polymer chain of the urethane prepolymer in such a way that the bonded end no longer has reactive groups.

[0183] The above-mentioned end-capping agents can be used alone or in combination of two or more.

[0184] The aforementioned capped urethane may contain residues of a crosslinking agent, residues of a chain extender, or both.

[0185] (Cross-linking agent)

[0186] The crosslinking agent is preferably 750 or less, more preferably 50 to 500, and is a polyol or polyamine compound having at least three hydroxyl, amino, and / or imino groups per molecule on average. The crosslinking agent imparts branching to the capped urethane, which is useful for increasing the functionality of the capped urethane (i.e., the number of isocyanate groups capped per molecule on average).

[0187] (Chain extender)

[0188] The chain extender described above preferably has a molecular weight of 750 or less, more preferably 50 to 500, and is a polyol or polyamine compound having an average of two hydroxyl, amino, and / or imino groups per molecule. The chain extender is useful for increasing the molecular weight of terminal carbamates without increasing their functionality.

[0189] Specific examples of the aforementioned crosslinking agents and chain extenders include trimethylolpropane, glycerol, trimethylolethane, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, sucrose, sorbitol, pentaerythritol, ethylenediamine, triethanolamine, monoethanolamine, diethanolamine, piperazine, and aminoethylpiperazine. Additionally, compounds with 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, can also be cited.

[0190] When using end-capped urethane as component (B), in order to balance the heat resistance of the obtained cured product with the effect of improving the toughness of the obtained cured product, the content of end-capped urethane relative to 100 parts by weight of epoxy resin (A) is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, further 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.

[0191] As component (B), the core-shell polymer particles and the end-capped urethane can be used in combination. In this case, considering the balance between the ease of processing the resulting one-component curable resin composition, the heat resistance of the resulting cured product, and the improvement in the toughness of the resulting cured product, the total content of the core-shell polymer particles and the end-capped urethane relative to 100 parts by weight of epoxy resin (A) is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, further 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. Furthermore, when used in combination, the ratio (by weight) of the core-shell polymer particles to the end-capped urethane is preferably 0.1 to 10, more preferably 0.2 to 5, and particularly preferably 0.3 to 3.

[0192] <Compounds with 1 to 3 phenolic hydroxyl groups per molecule (C)>

[0193] Compound (C) having 1 to 3 phenolic hydroxyl groups per molecule is a component that improves the impact peel adhesion of the cured product by controlling the crosslinking density of epoxy resin (A). Hereinafter, this compound will also be referred to as phenolic compound (C).

[0194] The curing process of epoxy resin using dicyandiamide as a curing agent is presumed to be as follows (refer to Gammon et al., Polymer Papers, Vol. 34, No. 7, 537-543). When the composition containing epoxy resin (A) and dicyandiamide (D) is heated, firstly, the cyanamide generated from dicyandiamide (D) reacts with epoxy resin (A) to form a linear polymer having hydroxyl and cyano groups. Next, the hydroxyl and cyano groups react between these linear polymers, thereby forming a three-dimensional cross-linked structure, and thus the composition cures.

[0195] In the presence of phenolic compound (C), the phenolic hydroxyl groups of phenolic compound (C) react with some of the cyano groups, thereby hindering part of the reaction between the hydroxyl groups and cyano groups of the linear polymer, thus reducing the crosslinking density of the three-dimensional crosslinked structure. As a result, the molecular weight between the crosslinking points in the cured product increases, making the cured product more susceptible to plastic deformation, and presumably improving its impact-peel adhesion. On the other hand, when a compound with four or more phenolic hydroxyl groups per molecule is used instead of a compound (C) with one to three phenolic hydroxyl groups per molecule, the crosslinking density increases, the cured product becomes brittle, and its impact-peel adhesion decreases.

[0196] The phenolic compound (C) can be any compound having 1 to 3 phenolic hydroxyl groups per molecule. It may or may not have substituents other than the phenolic hydroxyl groups on the aromatic ring. Substituents other than the phenolic hydroxyl groups are not particularly limited, and examples include alkyl, alkenyl, aryl, aralkyl, and other hydrocarbon groups, as well as halogens such as chlorine, bromine, and iodine. The number of carbon atoms in the hydrocarbon group is not particularly limited, 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 for obtaining a cured product with good properties, more preferably tert-butyl or methyl, and particularly preferably methyl.

[0197] Examples of phenolic compounds (C) 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, and 2,4,6-trimethylphenol. Phenols, 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, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, etc., as having... Compounds with two phenolic hydroxyl groups include, for example: 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-dimethylphenol), 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][triethylene glycol] ester, 2,2',6,6'-tetratert-butyl-4,4'-dihydroxybiphenyl, thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] ester, bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]1,6-hexanediol, etc.

[0198] Examples of compounds having three phenolic hydroxyl groups include: pyrophenol, phloroglucinol, resorcinol, 4,4',4"-ethide triphenol, 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)trimethylbenzene.

[0199] Phenolic compounds (C) can be used alone or in combination of two or more.

[0200] From the viewpoint of balancing improved impact-resistant peel adhesion with the storage stability of single-component curable resin compositions, the phenolic compound (C) is preferably a compound having one or two phenolic hydroxyl groups in one molecule.

[0201] From the perspectives of improving both impact-peel adhesion and the heat resistance of the cured product, phenolic compounds (C) are compounds with two phenolic hydroxyl groups per molecule. Using a compound with two phenolic hydroxyl groups suppresses the decrease in the glass transition temperature of the cured product compared to using a compound with one phenolic hydroxyl group, resulting in better impact-peel adhesion.

[0202] From the viewpoint of the storage stability of single-component curable resin compositions and the resistance of cured products to damp heat, the phenolic compound (C) is preferably a compound having one phenolic hydroxyl group in one molecule.

[0203] The phenolic compound (C) can be an unsubstituted phenolic compound, but is preferably a phenolic compound with substituents. This is because the steric hindrance of the substituents can be used to improve the storage stability of the one-component curable resin composition and the resistance of the cured product to damp heat. By having substituents on the aromatic ring of the phenolic compound (C), the reactivity of the phenolic hydroxyl groups can be suppressed by utilizing their steric hindrance, resulting in good storage stability of the one-component curable resin composition. In addition, by having substituents on the aromatic ring of the phenolic compound (C), hydrolysis caused by water molecules can be suppressed by utilizing their steric hindrance, thereby improving the resistance of the cured product to damp heat. Specifically, the phenolic compound (C) preferably has substituents selected from methyl, primary alkyl, secondary alkyl, tertiary alkyl, and halogens on its aromatic ring. From the viewpoint of improving storage stability by utilizing the steric hindrance of the substituents, the substituents are more preferably primary alkyl, secondary alkyl, tertiary alkyl, or halogens, and particularly preferably tertiary alkyl. The number of such substituents is preferably 1 to 4 per molecule of phenolic compound (C), more preferably 1 or 2.

[0204] Furthermore, 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 allows for more effective suppression of the reactivity of the phenolic hydroxyl group by utilizing its steric hindrance, resulting in better storage stability of the single-component curable resin composition. Additionally, the presence of a substituent at the ortho position of the phenolic hydroxyl group allows for more effective suppression of hydrolysis caused by water molecules by utilizing its steric hindrance, further improving the moisture and heat resistance of the cured product.

[0205] From the viewpoint of the storage stability of the aforementioned single-component curable resin composition and the resistance of the cured product to damp heat, the phenolic compound (C) is more preferably provided with one or two substituents at the ortho position of each phenolic hydroxyl group, and more preferably with two substituents at the ortho position of each phenolic hydroxyl group. When two substituents are provided at the ortho position of each phenolic hydroxyl group, it is preferable to have groups selected from methyl, primary alkyl, secondary alkyl, and halogen groups, and tertiary alkyl groups, and particularly preferably methyl and tert-butyl groups. Specific examples of such phenolic compounds (C) include 2-methyl-6-tert-butylphenol, 6-tert-butyl-2,4-xylenol, and bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][triethylene glycol] ester.

[0206] Furthermore, when there are two substituents at the ortho position of each phenolic hydroxyl group, the phenolic compound (C) can be a compound with tertiary alkyl groups at all the ortho positions of each phenolic hydroxyl group, a so-called hindered phenol. Such phenolic compounds have large tertiary alkyl groups on both sides of the phenolic hydroxyl groups, and therefore, their steric hindrance can be used to further improve the storage stability of single-component curable resin compositions.

[0207] Examples of compounds having tertiary alkyl groups at all ortho positions of the phenolic hydroxyl groups 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, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Examples of phenolic compounds include octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] 1,6-hexanediol 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)trimethylbenzene. However, phenolic compound (C) can also be a phenolic compound that does not belong to the category of compounds having tert-alkyl groups at all ortho-positions of the phenolic hydroxyl groups.

[0208] However, even compounds having 1 to 3 phenolic hydroxyl groups per molecule, compounds having an amino group in addition to the phenolic hydroxyl group would hinder the storage stability necessary for a one-component curable resin composition, and therefore are not phenolic compounds (C) in this application. Examples of compounds having an amino group in addition to the phenolic hydroxyl group include 2,4,6-tris(dimethylaminomethyl)phenol and 2-(dimethylaminomethyl)phenol.

[0209] However, in addition to the phenolic compound (C), the one-component curable resin composition of this embodiment may contain compounds having phenolic hydroxyl and amino groups in an amount that does not impede the storage stability of the composition. The amount that does not impede the storage stability of the composition refers to, 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, relative to 100 parts by weight of epoxy resin (A). However, the one-component curable resin composition of this embodiment preferably does not contain compounds having phenolic hydroxyl and amino groups.

[0210] The preferred phenolic compound (C) is not a phenolic resin, but a low-molecular-weight phenolic compound. The molecular weight of the low-molecular-weight phenolic compound is preferably 90 or higher and 500 or lower.

[0211] To improve the impact peel adhesion improvement effect brought about by the compound, the amount of phenolic compound (C) must meet the following conditions. When phenolic compound (C) is a compound having one phenolic hydroxyl group per molecule, the ratio of the molar number of phenolic hydroxyl groups in phenolic compound (C) to the molar number 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 improvement effect on impact peel adhesion due to the reduced crosslinking density is insufficient; if the ratio is greater than 0.39, the crosslinking density is excessively reduced, the strength of the resulting cured product decreases, and the improvement effect on impact peel adhesion is insufficient. In this case, a ratio of 0.05 or more and 0.35 or less is preferred, 0.08 or more and 0.30 or less is more preferably 0.10 or more and 0.25 or less is preferred.

[0212] Furthermore, when the phenolic compound (C) is a compound having two or three phenolic hydroxyl groups per molecule, the ratio of the molar number of phenolic hydroxyl groups in the phenolic compound (C) to the molar number 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 improvement in impact-resistant peel adhesion due to the reduced crosslinking density is insufficient; if the ratio is greater than 1.5, the crosslinking density is excessively reduced, the strength of the resulting cured product decreases, and the improvement in impact-resistant peel adhesion is insufficient. In this case, a ratio of 0.20 or more and 1.4 or less is preferred, more preferably 0.30 or more and 1.3 or less, and even more preferably 0.60 or more and 1.0 or less is preferred. Dicyandiamide decomposes upon heating, generating two molecules of cyanamide (a compound having CN groups) from one molecule of dicyandiamide. The aforementioned "molar number of CN groups generated from dicyandiamide (D)" refers to the theoretical molar number of CN groups in the cyanamide, calculated assuming the total amount of dicyandiamide is changed to cyanamide.

[0213] <Dicyandiamide (D)>

[0214] Dicyandiamide (D) generates cyanamide upon heating, which enables crosslinking of epoxy resin (A). Therefore, it can function as a curing agent that exhibits activity upon heating. By combining dicyandiamide (D), a one-component curable resin composition can be formed.

[0215] The amount of dicyandiamide (D) can be appropriately set according to the desired physical properties. From the viewpoint of improving impact-resistant peel adhesion, it is preferably 2 to 20 parts by weight, more preferably 3 to 18 parts by weight, further 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 relative to 100 parts by weight of epoxy resin (A).

[0216] In addition to improving the impact-resistant peel adhesion, from the viewpoint of 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.

[0217] <Compounds having four or more phenolic hydroxyl groups in one molecule (E)>

[0218] In addition to components (A) to (D), the single-component curable resin composition of this embodiment may also include a compound (E) having four or more phenolic hydroxyl groups in one molecule. Examples of such compounds include phenolic varnish-type phenolic resins and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0219] The amount of compound (E) can be appropriately set by those skilled in the art. From the viewpoint of impact-resistant peel adhesion, it is preferable that the ratio of the total weight of compound (E) to the total weight of phenolic compound (C) is less than 1, more preferably less than 0.5, and even more preferably less than 0.1. Alternatively, compound (E) may not be included.

[0220] <Curing Accelerator (F)>

[0221] The single-component curable resin composition of this embodiment may contain a curing accelerator (F). Component (F) can accelerate the curing reaction based on epoxy resin (A) and dicyandiamide (D).

[0222] Examples of components (F) 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); and 6-caprolactam, etc. Components (F) can be used alone or in combination of two or more. Components (F) can be encapsulated or are potential components that only become active upon heating.

[0223] When component (F) is incorporated, from the viewpoint of improving curability and storage stability, the amount of component (F) is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, further preferably 0.5 to 3 parts by weight, and particularly preferably 0.8 to 2 parts by weight, relative to 100 parts by weight of epoxy resin (A).

[0224] <Reinforcer>

[0225] To further improve properties such as toughness, impact resistance, shear adhesion, and peel adhesion, the single-component curable resin composition of this embodiment may contain an unmodified epoxy rubber polymer as a reinforcing agent, as needed. The reinforcing agent may be used alone or in combination of two or more.

[0226] <Unmodified epoxy rubber polymers>

[0227] As needed, the single-component curable resin composition of this embodiment may directly contain unmodified rubber polymers that have not reacted with epoxy resin.

[0228] Examples of rubber-based polymers include acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber, polypropylene oxide, polyethylene oxide, polycyclobutane oxide, and other polyoxyethylene rubber-based polymers. These rubber-based polymers preferably have reactive groups such as amino, hydroxyl, or carboxyl groups at their ends. Among these, from the viewpoint of the adhesive properties and impact-peel adhesion of the resulting one-component curable resin composition, NBR and polyoxyethylene are preferred, more preferably NBR, and particularly preferably carboxyl-terminated NBR (CTBN).

[0229] The glass transition temperature (Tg) of the above-mentioned rubber-based polymer is not particularly limited, but is preferably below -25°C, more preferably below -35°C, further preferably below -40°C, and especially preferably below -50°C.

[0230] The number-average molecular weight of the aforementioned rubber-based polymer, calculated based on the polystyrene-converted molecular weight as determined by GPC, is preferably 1,500 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. 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.

[0231] Rubber-based polymers can be used alone or in combination of two or more.

[0232] The amount of rubber-based polymer relative to 100 parts by weight of epoxy resin (A) 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. When the amount is 1 part by weight or more, the improvement in toughness, impact resistance, and adhesion is good, and when the amount is 50 parts by weight or less, the elastic modulus of the cured product is higher.

[0233] <Inorganic filler materials>

[0234] The single-component curable resin composition of this embodiment may contain inorganic filler materials. Examples of inorganic filler materials include silicic acid and / or silicates, such as dry silica, wet silica, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, and talc.

[0235] The aforementioned dry silica is also called fumed silica. Examples include untreated hydrophilic fumed silica and hydrophobic fumed silica produced by chemically treating the silanol group of hydrophilic fumed silica with silane or siloxane. From the perspective of dispersibility in component (A), hydrophobic fumed silica is preferred.

[0236] Other inorganic fillers include reinforcing fillers such as dolomite and carbon black; heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, titanium dioxide, iron oxide, aluminum micro powder, zinc oxide, and active zinc oxide.

[0237] The inorganic filler material is preferably surface-treated with a surface treatment agent. Surface treatment improves the dispersibility of the inorganic filler material in the composition, resulting in improved physical properties of the cured product.

[0238] Inorganic filler materials can be used alone or in combination of two or more.

[0239] The amount of inorganic filler material used is preferably 1 to 100 parts by weight relative to 100 parts by weight of component (A), more preferably 2 to 70 parts by weight, further preferably 5 to 40 parts by weight, and particularly preferably 7 to 20 parts by weight.

[0240] <Calcium oxide>

[0241] The single-component curable resin composition of this embodiment may contain calcium oxide.

[0242] Calcium oxide removes moisture by reacting with it in a one-component curable resin composition, thus solving various physical property problems caused by the presence of moisture. For example, it functions as an anti-bubble agent based on moisture removal, suppressing the reduction of adhesive strength.

[0243] Calcium oxide can be surface-treated with a surface treatment agent. Surface treatment improves the dispersibility of calcium oxide in the composition. As a result, the cured product exhibits improved physical properties such as adhesive strength compared to the case where untreated calcium oxide is used. In particular, T-peel adhesion and impact-resistant peel adhesion are significantly improved. There are no particular limitations on the surface treatment agent used, but fatty acids are preferred.

[0244] The amount of calcium oxide relative to 100 parts by weight of component (A) is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, further preferably 0.5 to 3 parts by weight, and particularly preferably 1 to 2 parts by weight. When the amount is 0.1 parts by weight or more, the moisture removal effect is good, and when the amount is 10 parts by weight or less, the strength of the obtained cured product is high.

[0245] Calcium oxide can be used alone or in combination with two or more other substances.

[0246] <Free radical curing resin>

[0247] The one-component curable resin composition of this embodiment may contain a free radical curable resin having two or more double bonds within its molecule, as needed. Additionally, a low molecular weight compound with a molecular weight of less than 300 and having at least one double bond within its molecule may be added, as needed. This low molecular weight compound, when used in combination with the aforementioned free radical curable resin, functions as a reactive diluent, adjusting viscosity, cured product properties, and curing speed. Furthermore, a free radical polymerization initiator may be added to the one-component curable resin composition of this embodiment. Here, the free radical polymerization initiator is preferably a latent type that is activated when the temperature is increased (preferably from about 50°C to about 150°C).

[0248] Examples of free radical curable resins include unsaturated polyester resins, polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, polyether (meth)acrylates, and acrylated (meth)acrylates. These can be used alone or in combination. Specific examples of the free radical curable resins include the compound described in International Publication No. 2014-115778. Furthermore, specific examples of the low-molecular-weight compounds and free radical polymerization initiators include the compound described in International Publication No. 2014-115778.

[0249] As described in International Publication No. 2010-019539, if a free radical polymerization initiator is activated at a temperature different from the curing temperature of the epoxy resin, partial curing of the single-component curable resin composition can be achieved through selective polymerization of the aforementioned free radical curable resin. This partial curing increases the viscosity of the composition after coating, improving wash-off resistance. It should be noted that in the water washing spray process of manufacturing lines for vehicles, etc., the uncured adhesive composition may partially dissolve, scatter, or deform due to the spray water pressure, sometimes adversely affecting the corrosion resistance of the coated steel plate or reducing its rigidity. The aforementioned "wash-off resistance" refers to resistance to this problem. Furthermore, this partial curing provides the function of temporarily bonding (temporarily adhering) the substrates together until the curing of the composition is complete. 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.

[0250] <Monocyclic oxide>

[0251] Depending on the requirements, the one-component curable resin composition of this embodiment may contain a monoepoxide. The monoepoxide can function as a reactive diluent. Specific examples of monoepoxides include aliphatic glycidyl ethers such as butyl glycidyl ether; aromatic glycidyl ethers such as phenyl glycidyl ether and tolyl glycidyl ether; ethers containing alkyl groups with 8 to 10 carbon atoms such as 2-ethylhexyl glycidyl ether; ethers containing phenyl groups with 6 to 12 carbon atoms such as p-tert-butylphenyl glycidyl ether, which can be substituted with alkyl groups with 2 to 8 carbon atoms; ethers containing alkyl groups with 12 to 14 carbon atoms such as dodecyl glycidyl ether; aliphatic glycidyl esters such as (meth)acrylate glycidyl ester and maleic acid glycidyl ester; glycidyl esters of aliphatic carboxylic acids with 8 to 12 carbon atoms such as tert-butyl carbonate glycidyl ester, neodecanoic acid glycidyl ester, and lauric acid glycidyl ester; and glycidyl p-tert-butylbenzoate, etc.

[0252] When using a monoepoxide, the amount of component (A) 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, relative to 100 parts by weight. When the amount is 0.1 parts by weight or more, the viscosity reduction effect is good, and when the amount is 20 parts by weight or less, the physical properties such as adhesion become good.

[0253] <Photopolymerization Initiator>

[0254] Furthermore, when photocuring the single-component curable resin composition of this embodiment, a photopolymerization initiator can be added. Examples of such photopolymerization initiators include hexafluoroantimonate, hexafluorophosphate, tetraphenyl borate, and aromatic sulfonates and aromatic iodides with anionic structures. Salt, etc. Photocationic polymerization initiators (photoacid generators) include salts, aromatic diazonium salts, and metallocene salts. These photopolymerization initiators can be used alone or in combination of two or more.

[0255] <Other Compounding Ingredients>

[0256] In this embodiment, other compounding components may be used as needed. Examples of other compounding components include azo chemical foaming agents, thermally expandable microspheres and other expanding agents, fibrous slurries such as aramid-based slurries, pigments, dyes and other colorants, extender pigments, ultraviolet absorbers, antioxidants, stabilizers (anti-gelling agents), plasticizers, leveling agents, defoamers, silane coupling agents, antistatic agents, flame retardants, lubricants, viscosity reducers, low-shrinkage agents, organic fillers, thermoplastic resins, desiccants, dispersants, etc.

[0257] <Preparation Method of Single-Component Curable Resin Composition>

[0258] In the case where the single-component curable resin composition of this embodiment contains an epoxy resin (A) as 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 a primary particle state.

[0259] Various methods can be used to obtain a composition in which the core-shell polymer particles (B) are dispersed in a primary particle state. Examples include: removing unwanted components such as water after contacting the core-shell polymer particles obtained in an aqueous latex state with component (A); temporarily extracting the core-shell polymer particles into an organic solvent, mixing them with component (A), and then removing the organic solvent. The method described in International Publication No. 2005 / 028546 is preferred. The specific manufacturing method preferably includes the following steps in sequence: a first step of mixing an aqueous latex containing core-shell polymer particles (B) (more specifically, the reaction mixture after manufacturing core-shell polymer particles by emulsion polymerization) with an organic solvent having a solubility of 5% by weight or more and 40% by weight or less in water at 20°C, and then further mixing it with excess water to cause the polymer particles to aggregate; a second step of separating / recovering the aggregated core-shell polymer particles (B) from the liquid phase and mixing it again with the organic solvent to obtain an organic solvent solution of core-shell polymer particles (B); and a third step of further mixing the organic solvent solution with component (A) and then removing the organic solvent by distillation.

[0260] If component (A) is liquid at 23°C, then the third step described above becomes easier and is therefore preferred. "Liquid at 23°C" means that the softening point is below 23°C and it exhibits fluidity at 23°C.

[0261] For a composition in which the core-shell polymer particles (B) obtained through the above process are dispersed in component (A) in a primary particle state, by mixing additional components (A), (C), (D), and other components as needed, a single-component curable resin composition of this method in which the core-shell polymer particles (B) are dispersed in a primary particle state can be obtained.

[0262] On the other hand, the powdered core-shell polymer particles (B) obtained by solidification and drying through methods such as salting out can be redispersed in component (A) using a disperser with high mechanical shear force, such as a three-roll mill, roller mill, or kneader. In this case, by applying mechanical shear force to components (A) and (B) at high temperature, the dispersion of component (B) can be achieved with good efficiency. The dispersion temperature is preferably 50–200°C, more preferably 70–170°C, further preferably 80–150°C, and particularly preferably 90–120°C.

[0263] The single-component curable resin composition of this embodiment has good storage stability. Therefore, after all the compounding components are pre-mixed, sealed and stored, coated, and cured by heating and light irradiation, it can be used in the form of the single-component composition obtained therefrom.

[0264] <Cured product>

[0265] By curing the one-component curable resin composition of this embodiment, a cured product can be obtained. 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. Preferably, the one-component curable resin composition has a low viscosity, allowing for good workability in obtaining the cured product.

[0266] The cured product described above can be manufactured by mixing components (A) to (D) and other components as needed, and then heating the resulting mixture at the curing temperature described later. Mixing components (A) to (D) and other components as needed also includes the following method: pre-preparing a composition in which core-shell polymer particles (B) are dispersed in component (A) in a primary particle state, as described above, and then mixing additional components (A), (C), (D), and other components as needed into that composition. When manufacturing the cured product by mixing the components, it is not necessary to perform a process of pre-reacting the epoxy resin (A) with the phenolic compound (C) to increase the molecular weight of the epoxy resin (A).

[0267] <Coating Method>

[0268] The one-component curable resin composition of this embodiment can be applied to a substrate by any method. According to a preferred embodiment, the application can be performed at a low temperature of around room temperature; however, heating and application can also be performed as needed. The heating and application method is particularly useful in order to ensure excellent storage stability of the one-component curable resin composition of this embodiment.

[0269] The one-component curable resin composition of this embodiment can be extruded onto the substrate in a bead, monofilament, or swirl pattern using a coating robot, or it can be applied using mechanical coating methods such as a caulking gun or other manual coating methods. Alternatively, the composition can be applied to the substrate using a spraying method or a flow coating method. The one-component curable resin composition of this embodiment can be applied to one or two substrates, bringing the substrates into contact by placing the composition between the two substrates to be bonded, and then curing the composition in this state to bond the two substrates. It should be noted that the viscosity of the one-component curable resin composition is not particularly limited; in the bead coating method, it is preferably around 150–600 Pa·s at 45°C; in the swirl coating method, it is preferably around 100 Pa·s at 45°C; and in the high-volume coating method using a high-speed flow device, it is preferably around 20–400 Pa·s at 45°C.

[0270] When using the one-component curable resin composition of this embodiment as an adhesive for vehicles, improving the thixotropy of the composition is effective in enhancing the aforementioned "washability". Generally, thixotropy is improved by thixotropic agents such as fumed silica and amide waxes. There is a tendency that the lower the viscosity of the thermosetting resin component as the main component, the greater the improvement effect and the better the workability of the composition. The one-component curable resin composition of this embodiment is easily made to have a low viscosity, thus easily improving its thixotropy, and is therefore preferred. The high thixotropic composition can be adjusted to a coatable viscosity by heating.

[0271] Furthermore, to improve the aforementioned "difficulty in rinsing," it is preferable to incorporate a polymeric compound having a crystalline melting point near the coating temperature of the composition into a single-component curable resin composition, as described in International Publication No. 2005-118734. This composition has low viscosity at the coating temperature (easy to coat) and high viscosity at the temperature during the water washing spray process, thus improving "difficulty in rinsing." Examples of such polymeric compounds having a crystalline melting point near the coating temperature include various polyester resins such as crystalline or semi-crystalline polyester polyols.

[0272] <Adhesive>

[0273] When using the single-component curable resin composition of this embodiment as an adhesive to bond various substrates together, substrates such as wood, metal, plastic, and glass can be joined. Joining automotive parts is preferred, and joining automotive frames together or joining automotive frames with other automotive parts is more preferable. Examples of substrates include cold-rolled steel, hot-dip galvanized steel, aluminum, aluminum-clad aluminum, general-purpose plastics, engineering plastics, composite materials such as CFRP and GFRP, and various plastic substrates.

[0274] The one-component curable resin composition of this embodiment exhibits excellent adhesive properties. Therefore, after sandwiching and bonding the one-component curable resin composition of this embodiment between multiple components comprising an aluminum substrate, and then curing the one-component curable resin composition, the resulting laminate formed by bonding the components exhibits high adhesive strength, which is therefore preferred.

[0275] The single-component curable resin composition of this embodiment has excellent toughness, and therefore is suitable for bonding different substrates with different coefficients of linear expansion.

[0276] In addition, the single-component curable resin composition of this embodiment can also be used for bonding of aerospace structural materials, especially external metal structural materials.

[0277] <Curing Temperature>

[0278] The curing temperature of the single-component curable resin composition in 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.

[0279] When using the single-component curable resin composition of this embodiment as an adhesive for automobiles, from the viewpoint of shortening / simplifying the process, it is preferable to apply the adhesive to the automobile component, then apply a coating agent, sinter / cur the coating agent, and simultaneously cure the adhesive.

[0280] <Uses>

[0281] The single-component curable resin composition of this embodiment is preferably used for applications such as adhesives for structural use in vehicles and aircraft, structural adhesives for wind power generation, coatings, materials for lamination with glass fiber, materials for printed wiring boards, solder resists, interlayer insulating films, assembly materials, adhesives for FPCs, electrical insulating materials such as sealants for electronic components such as semiconductors / LEDs, chip bonding materials, underfills, semiconductor mounting materials such as ACF, ACP, NCF, and NCP, and sealants for display / lighting machines such as LCD panels, OLED lighting, and OLED displays. In particular, it is useful as a structural adhesive for vehicles.

[0282] Example

[0283] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0284] (Determination of volume average particle size)

[0285] 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 manufacturing example was determined by the following method. The volume average particle size (Mv) of the particles dispersed in the aqueous latex was determined using a Microtrac UPA150 (manufactured by Nikkiso Corporation). The sample obtained by diluting with deionized water was used as the test sample. The measurement was performed as follows: the refractive index of water and the refractive index of each polymer particle were input, the measurement time was 600 seconds, and the sample concentration was adjusted to achieve a signal level in the range of 0.6 to 0.8.

[0286] 1. Core formation

[0287] Manufacturing Example 1: Preparation of Polybutadiene Rubber Latex (R-2)

[0288] In a pressure polymerizer, 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 hexahydrate (FE), and 1.55 parts by weight of sodium dodecylbenzenesulfonate (SDBS) were added. While stirring, nitrogen was thoroughly purged 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 p-menthane hydrogen peroxide (PHP) were added, followed by 0.10 parts by weight of sodium formaldehyde sulfoxylate (SFS), and polymerization began. 0.025 parts by weight of PHP were added at the 3rd, 5th, and 7th hours after polymerization began. Additionally, 0.0006 parts by weight of EDTA and 0.003 parts by weight of FE were added at the 4th, 6th, and 8th hours after polymerization began. The residual monomers were volatilized and removed under reduced pressure at the 15th hour of polymerization, thus ending the polymerization and yielding a polybutadiene rubber latex (R-1) with polybutadiene rubber as the main component. The volume average particle size of the polybutadiene rubber particles contained in the obtained latex was 0.08 μm.

[0289] In a pressure polymerizer, 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 were added. While stirring, nitrogen was used to fully purge oxygen. Then, 93 parts by weight of Bd were added to the system, and the temperature was raised to 45°C. 0.02 parts by weight of PHP were added, followed by 0.10 parts by weight of SFS, and polymerization began. From the start of polymerization until the 24th hour, 0.025 parts by weight of PHP, 0.0006 parts by weight of EDTA, and 0.003 parts by weight of FE were added every 3 hours. At the 30th hour of polymerization, residual monomers were evaporated under reduced pressure, ending the polymerization and yielding polybutadiene rubber latex (R-2) with polybutadiene rubber as the main component. The volume average particle size of the polybutadiene rubber particles contained in the obtained latex is 0.20 μm.

[0290] 2. Preparation of core-shell polymer latex (shell formation)

[0291] Manufacturing Example 2-1; Preparation of Core-Shell Polymer Latex (L-1)

[0292] In a glass reactor equipped with a thermometer, stirrer, reflux cooler, nitrogen inlet, and monomer addition device, 262 parts by weight of polybutadiene rubber latex (R-2) prepared in Manufacturing Example 1 (containing 87 parts by weight of polybutadiene rubber particles) and 57 parts by weight of deionized water were added, and stirring was carried out 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), 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 another 2 hours to complete the polymerization, yielding an aqueous latex (L-1) containing core-shell polymer particles. The polymerization conversion rate of the monomer components was over 99%. The water-based latex (L-1) contains core-shell polymer particles with a volume average particle size of 0.21 μm. The epoxy group content of these core-shell polymer particles relative to the total amount in the shell is 0.5 mmol / g.

[0293] Manufacturing Example 2-2; Preparation of Core-Shell Polymer Latex (L-2)

[0294] By changing the shell monomer 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, an aqueous latex (L-2) containing core-shell polymer particles was obtained in the same manner as in Manufacturing Example 2-1. The monomer conversion rate was over 99%. The volume average particle size of the core-shell polymer particles contained in the aqueous latex (L-2) was 0.21 μm. The epoxy group content of the core-shell polymer particles relative to the total amount of the shell was 2.2 mmol / g.

[0295] Manufacturing Examples 2-3; Preparation of Core-Shell Polymer Latex (L-3)

[0296] By changing the shell monomers 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, an aqueous latex containing core-shell polymer particles (L-3) was obtained in the same manner as in Manufacturing Example 2-1. The monomer conversion rate was over 99%. The volume average particle size of the core-shell polymer particles contained in the aqueous latex (L-3) was 0.21 μm. The epoxy group content of the core-shell polymer particles relative to the total amount of the shell was 1.1 mmol / g.

[0297] Manufacturing Examples 2-4; Preparation of Core-Shell Polymer Latex (L-4)

[0298] By changing the shell monomers 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, an aqueous latex containing core-shell polymer particles (L-4) was obtained in the same manner as in Manufacturing Example 2-1. The monomer conversion rate was over 99%. The volume average particle size of the core-shell polymer particles contained in the aqueous latex (L-4) was 0.21 μm. The epoxy group content of the core-shell polymer particles relative to the total amount of the shell was 0.5 mmol / g.

[0299] Manufacturing Examples 2-5; Preparation of Core-Shell Polymer Latex (L-5)

[0300] By changing the shell monomers to 5 parts by weight of MMA, 6 parts by weight of ST, and 2 parts by weight of AN, an aqueous latex containing core-shell polymer particles (L-5) was obtained in the same manner as in Manufacturing Example 2-1. The monomer conversion rate was over 99%. The volume average particle size of the core-shell polymer particles contained in the aqueous latex (L-5) was 0.21 μm. The epoxy group content of the core-shell polymer particles relative to the total amount of the shell was 0 mmol / g.

[0301] 3. Preparation of a dispersion (M) containing core-shell polymer particles (B) in a curable resin

[0302] Manufacturing Example 3-1; Preparation of Dispersion (M-1)

[0303] 132g of methyl ethyl ketone (MEK) was introduced into a 1L mixing tank at 25°C, and 132g of core-shell polymer latex (L-1) obtained in Manufacturing Example 2-1 (equivalent to 40g of core-shell polymer particles) was added while stirring. After uniform mixing, 200g of water was added at a feed rate of 80g / min. After the feed was completed, stirring was stopped immediately, resulting in a slurry consisting of suspended agglomerates and an aqueous phase containing a portion of organic solvent. Next, the agglomerates containing a portion of the aqueous phase were left as residue, and 360g of the aqueous phase was discharged from the outlet at the bottom of the tank. 90g of MEK was added to the obtained agglomerates and mixed uniformly to obtain a dispersion in which core-shell polymer particles (B) were uniformly dispersed. 60g of epoxy resin (manufactured by Mitsubishi Chemical Corporation, JER828: liquid bisphenol A type epoxy resin) as component (A) was mixed into this dispersion. MEK was removed from the mixture by a rotary evaporator. Thus, a dispersion (M-1) in which core-shell polymer particles (B) are dispersed in epoxy resin (A) is obtained.

[0304] Manufacturing Example 3-2; Preparation of Dispersion (M-2)

[0305] In Manufacturing Example 3-1, (L-2) obtained in Manufacturing Example 2-2 was used instead of (L-1) as the core-shell polymer latex. Otherwise, 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 Manufacturing Example 3-1.

[0306] Manufacturing Example 3-3; Preparation of Dispersion (M-3)

[0307] In Manufacturing Example 3-1, (L-3) obtained in Manufacturing Example 2-3 was used instead of (L-1) as the core-shell polymer latex. Otherwise, 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 Manufacturing Example 3-1.

[0308] Manufacturing Examples 3-4; Preparation of Dispersion (M-4)

[0309] In Manufacturing Example 3-1, (L-4) obtained in Manufacturing Example 2-4 was used instead of (L-1) as the core-shell polymer latex. Otherwise, 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 Manufacturing Example 3-1.

[0310] Manufacturing Examples 3-5; Preparation of Dispersion (M-5)

[0311] In Manufacturing Example 3-1, (L-5) obtained in Manufacturing Example 2-5 was used instead of (L-1) as the core-shell polymer latex. Otherwise, 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 Manufacturing Example 3-1.

[0312] (Examples 1-60, Comparative Examples 1-24)

[0313] Each component was measured according to the prescriptions shown in Tables 1 to 9, and thoroughly mixed to obtain a single-component curable resin composition.

[0314] For each composition in Tables 1 to 9, the dynamic breaking resistance (impact peel adhesion) and its retention rate after damp heat test, water absorption, T-peel adhesion strength and its retention rate after damp heat test, and viscosity rise rate (storage stability) were evaluated by the following methods.

[0315] <Dynamic fracture resistance (impact peel adhesion) and its retention rate after damp heat test>

[0316] Each composition was applied to two SPCC steel plates, overlapped to achieve an adhesive layer thickness of 0.25 mm. Compositions in Tables 1-5 were cured at 170°C for 30 minutes, and compositions in Tables 6-9 were cured at 150°C for 30 minutes, yielding laminates. Using these laminates, dynamic breaking resistance (impact peel adhesion) was measured at 23°C according to ISO 11343. The results are shown in Tables 1-9.

[0317] For each composition in Table 8, the dynamic breaking resistance was also measured after the above laminates were placed in a damp heat test at 70°C / 95% RH for 21 days, and the retention rate (= strength after damp heat test / strength before damp heat test) was calculated. The results are shown in Table 8.

[0318] <Water Absorption Rate>

[0319] The compositions in Table 1 were degassed and injected between two glass plates holding a 3mm thick spacer. The mixtures were then cured in a hot air oven at 170°C for 1 hour to obtain a 3mm thick cured plate. This cured plate was cut into 3mm × 5mm × 50mm dimensions to obtain a rectangular cured product. Before and after a 7-day damp heat test at 70°C / 95% RH, the weight of the rectangular cured product was measured, and the water absorption rate (%) was calculated using the following formula. The results are shown in Table 1.

[0320] Water absorption rate (%) = (Weight after damp heat test / Weight before damp heat test - 1) × 100

[0321] <T-Pipe Bond Strength and its Retention Rate after Damp Heat Test>

[0322] The compositions in Tables 2, 4-6, 8, and 9 were coated onto two SPCC steel plates with a width of 25 mm, a length of 200 mm, and a thickness of 0.5 mm. The plates were overlapped to achieve an adhesive layer thickness of 0.25 mm. The compositions in Tables 2 and 4-5 were cured at 170°C for 30 minutes, and the compositions in Tables 6 and 8-9 were cured at 150°C for 30 minutes to obtain the laminate.

[0323] The T-shaped peel bond strength was measured under the conditions of a test temperature of 23℃ and a test speed of 254 mm / min, with the unit set to N / 25 mm. The results are shown in Tables 2, 4-6, 8, and 9.

[0324] For each composition in Tables 6 and 9, the T-peel bond strength was also measured after a 21-day damp heat test in an environment of 70°C / 95% RH, and the retention rate (= strength after damp heat test / strength before damp heat test) was calculated. The results are shown in Tables 6 and 9.

[0325] <Viscosity rise rate (storage stability)>

[0326] Using a rheometer, at a shear rate of 5s -1 The viscosity of each composition of Examples 17-21 and Comparative Example 8 in Table 2, each composition of Examples 50-53 and Comparative Example 20 in Table 7, and each composition of Examples 57-60 and Comparative Example 24 in Table 9 was measured at 50°C. Each composition was stored at 40°C for 14 days and then subjected to a shear rate of 5 seconds at 50°C. -1 The viscosity after storage was measured in the same manner as before storage. The calculated viscosity increase rate (= viscosity after storage / viscosity before storage) is shown in Tables 2, 7 and 9.

[0327] It should be noted that the various complexing agents listed in Tables 1 through 9 use the complexing agents shown below. Additionally, Table 10 shows the structural formula, molecular weight, and melting point of each compound (C) and the comparative compound.

[0328] <Epoxy Resin (A)>

[0329] A-1: JER828 (Made by Mitsubishi Chemical, bisphenol A type epoxy resin, liquid at room temperature, epoxy equivalent: 184-194)

[0330] A-2: HyPox RA 1340 (made by CVC Thermoset Specialties, rubber-modified epoxy resin, epoxy equivalent: 350)

[0331] A-3: EPU-73B (made by ADEKA, urethane-modified epoxy resin, epoxy equivalent: 245)

[0332] <A dispersion (M) in which polymer particles (B) are dispersed in epoxy resin (A)>

[0333] M-1~5: Dispersions obtained in manufacturing examples 3-1~5 above

[0334] <Terminated carbamate (B)>

[0335] B-1: ADEKA resin QR-9466 (made by ADEKA, end-capped urethane, end-capped NCO equivalent 1400g / eq)

[0336] <Rubber-based polymers>

[0337] Carboxyl-terminated acrylonitrile-butadiene copolymer: CTBN 1300×8 (made by CVC Thermoset Specialties)

[0338] Carboxyl-terminated acrylonitrile-butadiene copolymer: CTBN 1300×13 (made by CVC Thermoset Specialties)

[0339] <Compounds with 1 to 3 phenolic hydroxyl groups per molecule (C)>

[0340] 4-tert-Butylphenol (Tokyo Chemical Manufacturing Co., Ltd.)

[0341] Bisphenol A (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0342] Bisphenol M (manufactured by Tokyo Chemical Industry)

[0343] Phenol (manufactured by Fujifilm and Koichi Chemical Industries)

[0344] 4-Methoxyphenol (manufactured by Fujifilm and Hikari Pure Chemical Industries)

[0345] 2,6-Xylenol (manufactured by Fujifilm and Hikari Pure Chemical Industries)

[0346] Resorcinol (manufactured by Fujifilm and Koh Genuine Chemicals Co., Ltd.)

[0347] Catechol (manufactured by Fujifilm and Hikari Pure Chemical Industries)

[0348] 4-Tert-butylcatechol (manufactured by Fujifilm and Hikari Pure Chemical Industries)

[0349] Hydroquinone (manufactured by Tokyo Chemical Industry)

[0350] Methylhydroquinone (manufactured by Fujifilm and Koichi Chemical Industries).

[0351] tert-Butylhydroquinone (Tokyo Chemical Manufacturing Co., Ltd.)

[0352] 2,5-Di-tert-butylhydroquinone (Tokyo Kasei Corporation)

[0353] 2,2'-Dialylbisphenol A (manufactured by Konishi Chemical Industry)

[0354] Pyrophenol (Kanto Chemical)

[0355] 3-Methyl-6-tert-butylphenol (Tokyo Chemical Manufacturing Co., Ltd.)

[0356] 2-Methyl-6-tert-butylphenol (Tokyo Chemical Manufacturing Co., Ltd.)

[0357] Bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][triethylene glycol] ester (manufactured by BASF Japan, product name: Irganox 245)

[0358] 6-tert-butyl-2,4-xylenol (Tokyo Kasei Corporation)

[0359] 2,3,6-Trimethylphenol (Tokyo Chemical Manufacturing Co., Ltd.)

[0360] 2,6-Di-tert-butylphenol (Tokyo Chemical Manufacturing Co., Ltd.)

[0361] <Phenolic compounds that do not belong to component (C)>

[0362] 2,4,6-Tris(dimethylaminomethyl)phenol (Tokyo Kasei Corporation)

[0363] PHENOLITE TD-2090 (DIC-based phenolic varnish-type phenolic resin)

[0364] <Non-phenolic compounds>

[0365] Anisole (manufactured by Kanto Chemical)

[0366] <Dicyandiamide (D)>

[0367] Dyhard 100S (Made by AlzChem)

[0368] <Curing Accelerator (F)>

[0369] Dyhard UR200 (AlzChem manufactured, 1,1-dimethyl-3-(3,4-dichlorophenyl)urea)

[0370] Dyhard UR300 (AlzChem manufactured, 1,1-dimethyl-3-phenylurea)

[0371] <Fused silica>

[0372] CAB-O-SIL TS-720 (CABOT manufactured fumed silica with a surface treated with polydimethylsiloxane)

[0373] <Calcium carbonate>

[0374] Untreated heavy calcium carbonate: Whiten SB (made of white stone calcium, average particle size: 1.8μm)

[0375] Colloidal calcium carbonate: Vigot-10 (manufactured by Shiraishi Industrial, average particle size: 0.17μm)

[0376] <Carbon Black>

[0377] MONARCH 280 (made by Cabot)

[0378] <Calcium oxide>

[0379] CML#31 (manufactured by Omi Chemical Industry)

[0380]

[0381] As shown in Table 1, the single-component curable resin compositions of Examples 1 to 9 containing components (A) to (D) exhibit good impact-resistant peel adhesion.

[0382] On the other hand, the compositions of Comparative Examples 1, 6-7 do not contain phenolic compound (C) and have low impact peel adhesion compared to Examples 1, 8, or 9, which have the same composition except for component (C).

[0383] For the compositions of Comparative Examples 2 to 4, the 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) is large, that is, the amount of compound (C) is relatively large, and the impact peel adhesion is very low.

[0384] The composition of Comparative Example 5 contains anisole, an aromatic compound without phenolic hydroxyl groups, in place of phenolic compound (C), and exhibits lower impact peel adhesion compared to Examples 1-9.

[0385]

[0386]

[0387] As shown in Table 2, the single-component curable resin compositions of Examples 10-22 containing phenolic compound (C) have better impact peel adhesion and higher T-peel adhesion strength compared to Comparative Example 8 which does not contain (C).

[0388] On the other hand, among Comparative Examples 9 and 10, which contain phenolic compounds that do not meet the definition of component (C), the impact peel adhesion of Comparative Example 10 is lower than that of Comparative Example 8, while its T-peel adhesion strength is the same as that of Comparative Example 8. Furthermore, Comparative Example 9 could not be prepared as an evaluation sample because it gelled within one hour after the preparation of the one-component curable resin composition. This indicates that phenolic compounds containing amino groups reduce the stability of the composition and hinder the storage stability that a one-component curable resin composition should exhibit.

[0389] Furthermore, it is known that in Examples 17-21, and especially in Example 21, the viscosity increase rate caused by storage at 40°C for 14 days was low, indicating good storage stability of the single-component curable resin composition. This is presumably due to the presence and number of substituents on the aromatic ring of the phenolic compound (C).

[0390]

[0391] As shown in Table 3, the single-component curable resin compositions of Examples 23-28 containing phenolic compound (C) exhibited good impact peel adhesion compared to Comparative Example 12, which did not contain component (C). On the other hand, Comparative Example 11, which did not contain component (B), showed very low impact peel adhesion. From the above, it can be seen that the improved impact peel adhesion is achieved through a synergistic effect of the combined use of components (B) and (C).

[0392]

[0393] As shown in Table 4, Example 29, containing phenolic compound (C), exhibited better impact-resistant peel adhesion and higher T-peel adhesion strength compared to Comparative Example 13, which contained no phenolic compound (C) but had the same composition except for component (C). Similarly, Example 30, compared to Comparative Example 14, Example 31, Example 33, Example 16, and Example 34, compared to Comparative Example 17, showed better impact-resistant peel adhesion and higher T-peel adhesion strength.

[0394] Furthermore, it is known that Example 32, by incorporating a rubber-based polymer, improves the T-peel bond strength compared to Example 29, which has the same composition except for the rubber-based polymer.

[0395]

[0396] As shown in Table 5, the single-component curable resin compositions of Examples 35-39 containing phenolic compound (C) exhibited better impact peel adhesion and higher T-peel adhesion strength compared to Comparative Example 18 which did not contain (C).

[0397]

[0398] As shown in Table 6, the single-component curable resin compositions of Examples 40-49 containing phenolic compound (C) have better impact peel adhesion and higher T-peel adhesion strength compared to Comparative Example 19 which does not contain (C).

[0399] Furthermore, it is evident that in Examples 40-49, the T-peel bond strength of Examples 41, 46, 47, and 49 exhibits high retention rates after damp heat testing, indicating excellent damp heat resistance of the cured products. Therefore, it is preferable from the viewpoint of improving damp heat resistance, that the phenolic compound (C) has a substituent at the ortho position of the phenolic hydroxyl group.

[0400]

[0401] As shown in Table 7, the single-component curable resin compositions of Examples 50-53 containing phenolic compound (C) exhibit higher impact peel adhesion compared to Comparative Example 20 which does not contain (C).

[0402] Furthermore, it is known that the single-component curable resin compositions of Examples 50-53 exhibit low viscosity increase rates after storage at 40°C for 14 days, indicating good storage stability. This is presumably because the phenolic compound (C) used has a tertiary alkyl group ortho-position in each phenolic hydroxyl group.

[0403] It can be seen that in Examples 50-53, the viscosity rise rate of the single-component curable resin compositions of Examples 51 and 53 is particularly low, and their storage stability is excellent. This is presumably because each phenolic hydroxyl group in the phenolic compound (C) has a methyl and a tertiary alkyl group at the ortho position.

[0404]

[0405] As shown in Table 8, the single-component curable resin compositions of Examples 54-56 containing phenolic compound (C) exhibit better impact peel adhesion and higher T-peel adhesion strength compared to Comparative Examples 21-23 which do not contain (C).

[0406] Furthermore, it is evident that Examples 54-56 exhibit a higher retention rate of impact-peel adhesion after the damp heat test compared to Comparative Examples 21-23, and the cured products show excellent damp heat resistance. This is presumably because the phenolic compound (C) used has methyl and tertiary alkyl groups at their ortho-positions.

[0407]

[0408] As shown in Table 9, the single-component curable resin compositions of Examples 57-60 containing phenolic compound (C) exhibited better impact peel adhesion and higher T-peel adhesion strength compared to Comparative Example 24 which did not contain (C).

[0409] Furthermore, it is evident that Examples 57-60 exhibit a greater retention rate of T-peel bond strength after damp heat testing compared to Comparative Example 24, with Example 59 showing particularly good performance, and the resulting cured product exhibits excellent damp heat resistance. Therefore, it is preferable from the viewpoint of improving damp heat resistance that the phenolic compound (C) has substituents at the ortho position of the phenolic hydroxyl group, and particularly preferable that it has methyl and tertiary alkyl groups at the ortho position of the phenolic hydroxyl group.

[0410] On the other hand, the single-component curable resin compositions of Examples 57-60 showed low viscosity increase rates after 14 days of storage at 40°C, indicating good storage stability. Examples 59-60 showed even better stability, with Example 60 being particularly outstanding. This is presumably because of the large number and volume of substituents at the ortho positions of the phenolic hydroxyl groups.

[0411] [Table 10(1)]

[0412]

[0413] [Table 10(2)]

[0414]

Claims

1. A one-component curable resin composition comprising: 100 parts by weight of epoxy resin (A); 1 to 100 parts by weight of polymer particles (B) having a core-shell structure, or 1 to 100 parts by weight of polymer particles having a core-shell structure and end-capped urethane (B); Compounds having 1 to 3 phenolic hydroxyl groups per molecule (C); as well as Dicyandiamide (D), Among them, compounds having 1 to 3 phenolic hydroxyl groups in one molecule, and further having an amino group, are not considered compounds (C). The compound (C) has substituents selected from methyl, secondary alkyl, tertiary alkyl and halogens on its aromatic ring, or has substituents selected from primary alkyl, secondary alkyl, tertiary alkyl and halogens, wherein the number of substituents is 1 to 4 per molecule of the compound (C). 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 0.3 or less when the compound (C) has one phenolic hydroxyl group in one molecule, and 0.01 or more and 1.5 or less when the compound (C) has two or three phenolic hydroxyl groups in one molecule.

2. The single-component curable resin composition according to claim 1, wherein, The substituent is bonded to the ortho position of at least one phenolic hydroxyl group.

3. A one-component curable resin composition comprising: 100 parts by weight of epoxy resin (A); 1 to 100 parts by weight of polymer particles (B) having a core-shell structure, or 1 to 100 parts by weight of polymer particles having a core-shell structure and end-capped urethane (B); Compounds having 1 to 3 phenolic hydroxyl groups per molecule (C); as well as Dicyandiamide (D), Among them, compounds having 1 to 3 phenolic hydroxyl groups in one molecule, and further having an amino group, are not considered compounds (C). The compound (C) has two substituents at the ortho position of each phenolic hydroxyl group. 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 0.3 or less when the compound (C) has one phenolic hydroxyl group in one molecule, and 0.01 or more and 1.5 or less when the compound (C) has two or three phenolic hydroxyl groups in one molecule.

4. The single-component curable resin composition according to any one of claims 1 to 3, wherein, The compound (C) has two substituents at the ortho position of each phenolic hydroxyl group, the two substituents being groups selected from methyl, secondary alkyl and halogen, or groups selected from primary alkyl, secondary alkyl and halogen; and tertiary alkyl.

5. The single-component curable resin composition according to claim 4, wherein, The two substituents are methyl and tert-butyl.

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

7. A one-component curable resin composition comprising: 100 parts by weight of epoxy resin (A); 1 to 100 parts by weight of polymer particles (B) having a core-shell structure, or 1 to 100 parts by weight of polymer particles having a core-shell structure and end-capped urethane (B); Compounds having 1 to 3 phenolic hydroxyl groups per molecule (C); as well as Dicyandiamide (D), Among them, compounds having 1 to 3 phenolic hydroxyl groups in one molecule, and further having an amino group, are not considered compounds (C). The compound (C) has one phenolic hydroxyl group 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 0.3 or less.

8. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, The molecular weight of the compound (C) is 90 or more and 500 or less.

9. The single-component curable resin composition according to any one of claims 1 to 3 and 7, further comprising a compound (E) having four or more phenolic hydroxyl groups in one molecule. The ratio of the total weight of compound (E) to the total weight of compound (C) is less than 1.

10. The single-component curable resin composition according to any one of claims 1 to 3 and 7, 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.

11. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, Relative to 100 parts by weight of the epoxy resin (A), it further contains 0.1 to 10 parts by weight of curing accelerator (F).

12. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, The polymer particles with a core-shell structure have one or more core layers selected from diene rubber, (meth)acrylate rubber, and organosiloxane rubber.

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

14. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, The polymer particles with the core-shell structure have a shell layer, which is formed by grafting and polymerizing one or more monomer components selected from aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers with the core layer.

15. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, The polymer particles with a core-shell structure have epoxy groups in the shell layer.

16. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, The polymer particles with a core-shell structure have a shell layer, which is formed by grafting an epoxy-containing monomer component to the core layer.

17. The single-component curable resin composition according to any one of claims 1 to 3 and 7, wherein, The polymer particles with a core-shell structure have epoxy groups in the shell layer, and the content of the epoxy groups in the shell layer is 0.1~2.0 mmol / g relative to the total amount of the shell layer.

18. A cured product, which is formed by curing a single-component curable resin composition according to any one of claims 1 to 17.

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

20. The adhesive according to claim 19, wherein, The adhesive is a structural adhesive.

21. A laminate comprising two substrates and an adhesive layer for joining the two substrates, said adhesive layer being formed by curing the adhesive of claim 19 or 20.

22. The method for manufacturing the cured product according to claim 18, the method comprising: The process of mixing the epoxy resin (A), the polymer particles with a core-shell structure (B), or the polymer particles with a core-shell structure, a capped urethane ester (B), the compound (C), and the dicyandiamide (D) to obtain a mixture; as well as The process of heating the mixture to obtain the cured product.

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