JP2018090651A - Curable epoxy resin composition excellent in storage stability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable epoxy resin composition which contains a core shell polymer, is excellent in adhesion after curing, and is excellent in storage stability.SOLUTION: A curable epoxy resin composition contains (B) 1-50 pts.wt. of a core shell polymer and (C) 1-50 pts.wt. of blocked isocyanate with respect to (A) 100 pts.wt. of an epoxy resin, where a core layer of (B) is formed of a diene-based rubber, an acrylic rubber and a polysiloxane-based rubber, a shell layer of (B) the core shell polymer is formed of 30-98 mass% of an alkyl methacrylate monomer, 0-25 mass% of a monomer having an epoxy group and 2-70 mass% of a monomer copolymerizable with them with the total amount of the monomer constituting the shell layer 100 mass%, and the core layer is formed of a butadiene rubber and/or a butadiene-styrene rubber.SELECTED DRAWING: None

Description

  The present invention relates to a curable epoxy resin composition containing a core-shell polymer, an adhesive thereof, and particularly a structural adhesive for vehicles.

  Epoxy resins are used in a wide range of applications, one of which is an adhesive. Epoxy resin cured products exhibit excellent mechanical properties, electrical properties, and durability, while curable epoxy resin compositions are used in structural adhesives such as vehicles to improve brittle properties and impact resistance. In some cases, the product contains a core-shell polymer and a blocked isocyanate (Patent Document 1).

  In structural adhesives, quality cannot be maintained when stored for a long period of time, and the product viscosity may change before and after storage.

Special table 2010-530472

In order to maintain quality before and after long-term storage, it is considered effective to provide a curable epoxy resin composition having excellent storage stability.
An object of this invention is to provide the curable epoxy resin composition which is excellent in storage stability according to the above-mentioned situation, and is further excellent in the adhesiveness of the hardened | cured material obtained.

1) The present invention is a curable epoxy resin composition containing (B) 1 to 50 parts by weight of a core-shell polymer and (C) 1 to 50 parts by weight of a blocked isocyanate with respect to 100 parts by weight of (A) an epoxy resin. (B) The core layer of the core-shell polymer is made of any of diene rubber, acrylic rubber, or polysiloxane rubber. (B) The shell layer of the core-shell polymer is 100 masses of the total amount of monomers constituting the shell layer. It is related with the curable epoxy resin composition characterized by comprising 30-98 mass% of alkyl methacrylate monomers, 0-25 mass% of monomers having an epoxy group, and 2-70 mass% of monomers copolymerizable therewith.
2) Further, in the present invention, (B) the shell layer of the core-shell polymer has the total amount of monomers constituting the shell layer as 100% by mass, the alkyl methacrylate monomer 50 to 97% by mass, and the monomer having an epoxy group 2 to 20% by mass. And a curable epoxy resin composition comprising 1 to 48% by mass of a monomer copolymerizable therewith.
3) Further, the present invention relates to a curable epoxy resin composition, wherein the alkyl methacrylate monomer is at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, and propyl methacrylate.
4) Further, the present invention relates to a curable epoxy resin composition, wherein the monomer having an epoxy group is glycidyl methacrylate.
5) Further, the present invention relates to a curable epoxy resin composition, wherein the core layer of the (B) core-shell polymer is composed of butadiene rubber and / or butadiene-styrene rubber.
6) Furthermore, this invention relates to the curable epoxy resin composition characterized by the volume average particle diameter of (B) core shell polymer being 0.05-0.30 nm.
7) Further, the present invention relates to a curable epoxy resin composition, wherein (C) the blocked isocyanate is a compound obtained by capping a urethane prepolymer containing a polypropylene glycol structure with a blocking agent.
8) Further, the present invention relates to a curable epoxy resin composition, wherein (C) blocked isocyanate is a compound obtained by capping a urethane prepolymer containing a polytetramethylene glycol structure with a blocking agent.
9) Furthermore, this invention relates to the curable epoxy resin composition characterized by containing 1-80 weight part epoxy hardener (D).
10) Furthermore, this invention relates to the curable epoxy resin composition characterized by containing 0.1-10 weight part weight part of hardening accelerator (E).
11) It relates to a cured product obtained by curing a curable epoxy resin composition.
12) It is related with the structural adhesive agent which uses a curable epoxy resin composition.
13) The present invention relates to a structural adhesive for vehicles using a curable epoxy resin composition.

  The curable epoxy resin composition of the present invention is excellent in storage stability.

  The curable epoxy resin composition of the present invention contains (A) an epoxy resin, (B) a core-shell polymer, and (C) a blocked isocyanate.

<Epoxy resin (A)>
(A-1) Examples of polyglycidyl ether, polyvalent glycidylamine compound, alicyclic epoxy resin, etc. The epoxy resin (A) of the present invention is not particularly limited as long as it is a compound having an epoxy group, but is used in the present invention. The epoxy resin that can be obtained is preferably an epoxy resin also called polyepoxide. Examples of the epoxy resin include polyglycidyl ether (bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenol type) such as addition reaction products of polyphenols such as bisphenol A, bisphenol F, biphenol, and phenol novolak and epichlorohydrin. Epoxy resins, phenol novolac type epoxy resins, etc.), polyamines derived from monoamines and polyamines such as aniline, diaminobenzene, aminophenol, phenylenediamine, diaminophenyl ether, and alicyclic epoxies such as cyclohexyl epoxy Cycloaliphatic epoxy resin having a structure, addition reaction product of polyhydric alcohols and epichlorohydrin, halogenation in which some of these hydrogens are substituted with halogen elements such as bromine Examples thereof include homopolymers or copolymers obtained by polymerizing monomers containing unsaturated monoepoxides such as epoxy resins and allyl glycidyl ether. Many polyepoxides synthesized from polyhydric phenols are disclosed, for example, in US Pat. No. 4,431,782. Examples of polyepoxides further include those disclosed in US Pat. Nos. 3,804,735, 3,892,819, 3,948,698, 4,147,771, and an epoxy resin handbook (Nikkan Kogyo Shimbun, 1987). Can be mentioned.

(A-2) Illustrative examples of polyalkylene glycol diglycidyl ether, glycol diglycidyl ether and the like As the epoxy resin (A) of the present invention, polyalkylene glycol diglycidyl ether, glycol diglycidyl ether, aliphatic polybasic acid Diglycidyl esters, glycidyl ethers of divalent or higher polyhydric aliphatic alcohols, and divinylbenzene dioxide can also be used. These are epoxy resins having a relatively low viscosity, and when used in combination with other epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, they function as reactive diluents, and the viscosity and cured physical properties of the composition. The balance can be improved. The content of these epoxy resins is preferably 0.5 to 20% by mass in the component (A), more preferably 1 to 10% by mass, and still more preferably 2 to 5% by mass. More specific examples of the polyalkylene glycol diglycidyl ether include polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether. More specifically, the glycol diglycidyl ether includes neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, cyclohexane dimethanol diglycidyl ether, and the like. Can be mentioned. Specific examples of the diglycidyl ester of the aliphatic polybasic acid include dimer acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, maleic acid diglycidyl ester, and the like. More specifically, the glycidyl ether of the dihydric or higher polyhydric aliphatic alcohol includes trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, castor oil-modified polyglycidyl ether, propoxylated glycerin triglycidyl ether, sorbitol. And polyglycidyl ether.

(A-3) Example of epoxy compound obtained by addition reaction of polybasic acids and the like to epoxy resin Furthermore, as the epoxy resin (A) of the present invention, an epoxy resin as described in WO2010-098950 Epoxy compounds obtained by addition reaction of polybasic acids and the like can also be used. For example, an addition reaction product of a dimer of tall oil fatty acid (dimer acid) and a bisphenol A type epoxy resin can be mentioned. Chelate-modified epoxy resins, rubber-modified epoxy resins, and urethane-modified epoxy resins can also be used as the component (A). Epoxy resins that can be used in the present invention are as described above, and generally include those having an epoxy equivalent of 80 to 2000. These polyepoxides can be obtained by a well-known method. As a commonly used method, for example, an excess amount of epihalohydrin is reacted with a polyhydric alcohol or polyhydric phenol in the presence of a base.

(A-3-1) Chelate-modified epoxy resin As the epoxy resin (A) of the present invention, a chelate-modified epoxy resin can be used. The chelate-modified epoxy resin is a reaction product of an epoxy resin and a compound containing a chelate functional group (chelate ligand). When added to the resin composition of the present invention and used as an adhesive for vehicles, an oily substance The adhesion to the metal substrate surface contaminated with can be improved. The chelate functional group is a functional group of a compound having a plurality of coordination sites capable of coordinating with metal ions in the molecule. For example, a phosphorus-containing acid group (for example, —PO (OH) ₂ ), a carboxylic acid group (— CO ₂ H), sulfur-containing acid groups (for example, —SO ₃ H), amino groups and hydroxyl groups (particularly, hydroxyl groups adjacent to each other in the aromatic ring). Examples of chelate ligands include ethylenediamine, bipyridine, ethylenediaminetetraacetic acid, phenanthroline, porphyrin, and crown ether. Examples of commercially available chelate-modified epoxy resins include Adeka Resin EP-49-10N manufactured by ADEKA. The amount of chelate-modified epoxy resin used in component (A) is preferably 0.1 to 10% by mass, more preferably 0.5 to 3% by mass.

(A-3-2) Rubber-modified epoxy resin The rubber-modified epoxy resin is a reaction product obtained by reacting rubber and an epoxy group-containing compound with an average of 1.1 or more epoxy groups per molecule. As rubber, acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber And rubber-based polymers such as polyoxyalkylenes such as polypropylene oxide, polyethylene oxide, and polytetramethylene oxide. The rubber polymer is preferably one having a reactive group such as an amino group, a hydroxy group, or a carboxyl group at the terminal. The rubber-modified epoxy resin used in the present invention is a product obtained by reacting these rubber-based polymer and epoxy resin at an appropriate blending ratio by a known method. Among these, acrylonitrile-butadiene rubber-modified epoxy resin and polyoxyalkylene-modified epoxy resin are preferable from the viewpoint of adhesion of the resulting resin composition and impact-resistant peel adhesion, and acrylonitrile-butadiene rubber-modified epoxy resin is more preferable. . The acrylonitrile-butadiene rubber-modified epoxy resin can be obtained, for example, by a reaction between a carboxyl group-terminated NBR (CTBN) and a bisphenol A type epoxy resin. The polyoxyalkylene-modified epoxy resin is obtained, for example, by a reaction between an amino group-terminated polyoxyalkylene and a bisphenol A type epoxy resin.

  The content of the acrylonitrile monomer component in the acrylonitrile-butadiene rubber is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, from the viewpoint of the adhesiveness of the resin composition to be obtained and the impact-resistant peel adhesion. Preferably, 15 to 30% by mass is more preferable. 20-30 mass% is especially preferable from a thixotropic viewpoint of the resin composition obtained.

  The average number of epoxide-reactive end groups per molecule in the rubber is preferably 1.5 to 2.5, and more preferably 1.8 to 2.2. The number average molecular weight of the rubber is preferably 2,000 to 10,000, more preferably 3,000 to 8,000, and particularly preferably 4,000 to 6,000 in terms of polystyrene-converted molecular weight measured by GPC.

  There is no restriction | limiting in particular about the manufacturing method of rubber-modified epoxy resin, For example, it can manufacture by making rubber and an epoxy resin group containing compound react in a lot of epoxy resin group containing compounds. Specifically, it is preferable to produce by reacting 2 equivalents or more of an epoxy group-containing compound with respect to 1 equivalent of an epoxy-reactive terminal group in the rubber. It is more preferable to react an amount of the epoxy group-containing compound sufficient for the resulting product to be a mixture of an adduct of rubber and an epoxy group-containing compound and a free epoxy group-containing compound. The rubber-modified epoxy resin is produced by heating to a temperature of 100 to 250 ° C. in the presence of a catalyst such as phenyldimethylurea or triphenylphosphine. The epoxy group-containing compound used in producing the rubber-modified epoxy resin is not particularly limited, but bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable, and bisphenol A type epoxy resin is more preferable. In the present invention, when an excessive amount of the epoxy group-containing compound is used during the production of the rubber-modified epoxy resin, the unreacted epoxy group-containing compound remaining after the reaction is included in the rubber-modified epoxy resin of the present application, It shall not be included.

  The rubber-modified epoxy resin can be modified by pre-reaction with a bisphenol component. The bisphenol component used for modification is preferably 3 to 35 parts by weight and more preferably 5 to 25 parts by weight with respect to 100 parts by weight of the rubber component in the rubber-modified epoxy resin. A cured product obtained by curing a resin composition containing a modified rubber-modified epoxy resin is excellent in adhesion durability after high-temperature exposure and excellent in impact resistance at low temperatures.

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

The content of the rubber-modified epoxy resin in the component (A) is preferably 1 to 40% by mass, more preferably 3 to 30% by mass, still more preferably 5 to 25% by mass, and particularly preferably 10 to 20% by mass. If it is less than 1% by mass, the resulting cured product may be brittle and impact-resistant peel adhesion may be low, and if it exceeds 40% by mass, the resulting cured product may have low heat resistance and / or elastic modulus (rigidity).
The rubber-modified epoxy resins can be used alone or in combination of two or more.

(A-3-3) Urethane-modified epoxy resin The urethane-modified epoxy resin is obtained by reacting a compound containing an epoxy group with a group having reactivity with an isocyanate group and a urethane prepolymer containing an isocyanate group. Further, it is a reaction product having an average of 1.1 or more epoxy groups per molecule. For example, a urethane-modified epoxy resin can be obtained by reacting a hydroxy group-containing epoxy compound with a urethane prepolymer.

  (A) As for content of the urethane-modified epoxy resin in a component, 1-40 mass% is preferable, 3-30 mass% is more preferable, 5-25 mass% is still more preferable, 10-20 mass% is especially preferable. If it is less than 5% by mass, the resulting cured product may be brittle and may have low impact peel adhesion, while if it exceeds 40% by mass, the resulting cured product may have low heat resistance and / or elastic modulus (rigidity).

  Urethane-modified epoxy resins can be used alone or in combination of two or more.

  Among the above-mentioned epoxy resins (A), bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferable because the obtained cured products have high elastic modulus, excellent heat resistance and adhesiveness, and are relatively inexpensive. A type epoxy resin is particularly preferred.

  The epoxy equivalent of the epoxy resin (A) of the present invention is preferably less than 220, more preferably 90 or more and less than 210, and still more preferably 150 or more and less than 200, from the viewpoint that the obtained cured product has high elastic modulus and high heat resistance. In particular, a bisphenol A type epoxy resin or a bisphenol F type epoxy resin having an epoxy equivalent of less than 220 is preferable because it is liquid at room temperature and the handleability of the resulting resin composition is good.

  It is obtained by adding a bisphenol A type epoxy resin or a bisphenol F type epoxy resin having an epoxy equivalent of 220 or more and less than 2000 to the component (A) in a range of preferably 40% by mass or less, more preferably 20% by mass or less. A cured product is preferred because of its excellent impact resistance.

<Core shell polymer (B)>
The core-shell polymer (B) of the present invention comprises at least two layers of a core layer and a shell layer. Moreover, the core-shell polymer (B) of the present invention may be composed of three layers of a core layer, an intermediate layer, and a shell layer. The volume average particle diameter of the core-shell polymer (B) of the present invention is preferably 0.03 to 2.10 μm, more preferably 0.05 to 1.10 μm, and particularly preferably 0.08 to 0.30 μm. In many cases, it is difficult to stably obtain a volume average particle size of less than 0.03 μm, and when it exceeds 2 μm, the heat resistance and impact resistance of the final molded product may be deteriorated.

Hereinafter, each layer will be described.
(Core layer)
(Core layer (use either diene, acrylic or polysiloxane rubber))
The core layer of the core-shell polymer (B) of the present invention comprises 50 to 100 at least one monomer (first monomer) selected from natural rubber, diene monomers (conjugated diene monomers) and (meth) acrylate monomers. A rubber elastic body comprising 0% by mass to 50% by mass of another copolymerizable vinyl monomer (second monomer), a polysiloxane rubber elastic body, or a combination thereof. . Due to the high toughness improvement effect and impact peel adhesion improvement effect of the resulting cured product, and the low viscosity with time due to swelling of the core layer due to low affinity with the matrix resin. A diene rubber using a monomer is preferred. Since a wide variety of polymer designs are possible by combining various monomers, (meth) acrylate rubber is preferred. Moreover, when it is going to improve the impact resistance in low temperature, without reducing the heat resistance of hardened | cured material, it is preferable that an elastic core layer is a polysiloxane rubber elastic body. In the present invention, (meth) acrylate means acrylate and / or methacrylate.

(Core layer (diene))
Examples of the diene monomer (conjugated diene monomer) of the first monomer include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, 2-methyl-1,3-butadiene, and the like. . These diene monomers may be used alone or in combination of two or more.

  1,3-butadiene is used because it has a high toughness-improving effect and an impact-removing adhesiveness-improving effect, and because the affinity with the matrix resin is low, it is difficult for the core layer to swell to increase the viscosity over time. Butadiene rubber or butadiene-styrene rubber which is a copolymer of 1,3-butadiene and styrene is preferable, and butadiene rubber is more preferable. Also, butadiene-styrene rubber is more preferred because it can increase the transparency of the cured product obtained by adjusting the refractive index.

(Core layer (acrylic)
Examples of the (meth) acrylate rubber monomer of the first monomer include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and octyl (meth) acrylate. , Alkyl (meth) acrylates such as dodecyl (meth) acrylate, stearyl (meth) acrylate, and behenyl (meth) acrylate; aromatic ring-containing (meth) acrylates such as phenoxyethyl (meth) acrylate and benzyl (meth) acrylate; 2 -Hydroxyethyl (meth) acrylates such as hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; glycidyl (meth) acrylate, glycidylalkyl (meth) acrylate, etc. Glycidyl (meth) acrylates; alkoxyalkyl (meth) acrylates; allylalkyl (meth) acrylates such as allyl (meth) acrylate and allylalkyl (meth) acrylate; monoethylene glycol di (meth) acrylate, triethylene glycol di Polyfunctional (meth) acrylates such as (meth) acrylate and tetraethylene glycol di (meth) acrylate are exemplified. These (meth) acrylate monomers may be used alone or in combination of two or more. Particularly preferred are ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

(Second monomer)
Examples of the other copolymerizable vinyl monomer (second monomer) include, for example, vinyl arenes such as styrene, α-methyl styrene, monochlorostyrene and dichlorostyrene; vinyl carboxylic acids such as acrylic acid and methacrylic acid; acrylonitrile Vinyl cyanides such as methacrylonitrile; vinyl halides such as vinyl chloride, vinyl bromide, chloroprene; vinyl acetate; alkenes such as ethylene, propylene, butylene, isobutylene; diallyl phthalate, triallyl cyanurate, triallyl And polyfunctional monomers such as isocyanurate and divinylbenzene. These vinyl monomers may be used alone or in combination of two or more. Particularly preferred is styrene.

(Polysiloxane rubber)
The polysiloxane rubber elastic body is composed of alkyl or aryl disubstituted silyloxy units such as dimethylsilyloxy, diethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, dimethylsilyloxy-diphenylsilyloxy, and the like. And polysiloxane polymers composed of alkyl or aryl 1-substituted silyloxy units, such as organohydrogensilyloxy in which a part of the alkyl in the side chain is substituted with hydrogen atoms. These polysiloxane polymers may be used alone or in combination of two or more. Among them, dimethylsilyloxy, methylphenylsilyloxy, dimethylsilyloxy-diphenylsilyloxy are preferable for imparting heat resistance to the cured product, and dimethylsilyloxy is most preferable because it is easily available and economical. In an embodiment in which the core layer is formed of a polysiloxane rubber-based elastic body, the polysiloxane-based polymer portion is 80% by mass or more (more preferably) in order not to impair the heat resistance of the cured product. 90% by mass or more) is preferable.

(Cross-linking of core layer)
The core layer of the core-shell polymer (B) preferably has a cross-linked structure introduced from the viewpoint of maintaining dispersion stability in the curable epoxy resin composition. Examples of a method for introducing a crosslinked structure include a method in which a crosslinkable monomer such as a polyfunctional monomer or a mercapto group-containing compound is added to a polymer component and then polymerized. In addition, as a method for introducing a crosslinked structure into the polysiloxane polymer, a method in which a polyfunctional alkoxysilane compound is partially used at the time of polymerization, or a reactive group such as a vinyl reactive group or a mercapto group is added to the polysiloxane polymer. And then adding a vinyl polymerizable monomer or an organic peroxide to cause a radical reaction, or adding a crosslinkable monomer such as a polyfunctional monomer or a mercapto group-containing compound to the polysiloxane polymer, Next, a polymerization method and the like can be mentioned.

(Multifunctional monomer)
Examples of the polyfunctional monomer include allyl alkyl (meth) acrylates such as allyl (meth) acrylate and allylalkyl (meth) acrylate; allyloxyalkyl (meth) acrylates; (poly) ethylene glycol di (meth) acrylate, Polyfunctional (meth) having two or more (meth) acrylic groups such as butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate Acrylates such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene and the like. Particularly preferred are allyl methacrylate, triallyl isocyanurate, butanediol di (meth) acrylate, and divinylbenzene.

(Gel content of core layer)
The core layer of the core-shell polymer (B) of the present invention preferably has rubber properties in order to increase the toughness of the cured product of the curable epoxy resin composition. From the viewpoint of toughness of the cured product, the gel content of the core layer of the core-shell polymer (B) of the present invention is preferably 60% by mass or more, more preferably 80% by mass or more, and 90% by mass or more. More preferably, it is particularly preferably 95% by mass or more. The gel content is the insoluble and soluble content when 0.5 g of crumb obtained by coagulation and drying is immersed in 100 g of toluene and allowed to stand at 23 ° C. for 24 hours, and then the insoluble and soluble components are separated. The ratio of insoluble matter to the total amount of

(Tg of core layer)
In the present invention, the glass transition temperature of the core layer of the core-shell polymer (B) (hereinafter sometimes simply referred to as “Tg”) is preferably 0 ° C. or lower in order to increase the toughness of the resulting cured product. -20 ° C or lower is more preferable, -40 ° C or lower is further preferable, and -60 ° C or lower is particularly preferable.

  On the other hand, when it is desired to suppress the decrease in rigidity of the resulting cured product, the Tg of the core layer is preferably greater than 0 ° C, more preferably 20 ° C or more, and even more preferably 50 ° C or more. 80 ° C. or higher is particularly preferable, and 120 ° C. or higher is most preferable.

  As a polymer capable of forming a core layer having a Tg greater than 0 ° C. and capable of suppressing a decrease in rigidity of the resulting cured product, at least one monomer having a Tg of a homopolymer greater than 0 ° C. is 50 to 100 masses. % (More preferably 65 to 99% by mass), and 0 to 50% by mass (more preferably 1 to 35% by mass) of at least one monomer having a Tg of less than 0 ° C. Polymers.

  Monomers having a Tg of higher than 0 ° C. are, for example, unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; vinyl-substituted aromatic compounds such as α-methylstyrene; 3-methylstyrene Cyclic alkylated vinyl aromatic compounds such as 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene; Cyclic alkoxylated vinyl aromatic compounds such as 4-ethoxystyrene; ring halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; ring ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene Ring aromatic vinyl compounds such as 4-hydroxyoxystyrene; vinyl benzoate, vinyl Vinyl esters such as lohexanoate; vinyl halides such as vinyl chloride; aromatic monomers such as acenaphthalene and indene; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and isopropyl methacrylate; aromatic methacrylates such as phenyl methacrylate; Methacrylate monomers such as bornyl methacrylate and trimethylsilyl methacrylate; methacrylic monomers including methacrylic acid derivatives such as methacrylonitrile; certain acrylic acid esters such as isobornyl acrylate and tert-butyl acrylate; including acrylic acid derivatives such as acrylonitrile Mention may be made of acrylic monomers. Furthermore, Tg of acrylamide, isopropylacrylamide, N-vinylpyrrolidone, isobornyl methacrylate, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, 1-adamantyl methacrylate, etc. is 120 ° C. or higher. The monomer which becomes.

(Average particle diameter of core layer)
The volume average particle diameter of the core layer of the core-shell polymer (B) of the present invention is preferably 0.03 to 2 μm, more preferably 0.05 to 1 μm. In many cases, it is difficult to stably obtain a volume average particle size of less than 0.03 μm, and when it exceeds 2 μm, the heat resistance and impact resistance of the final molded product may be deteriorated.

(Ratio of core layer)
The core layer of the core-shell polymer (B) of the present invention is preferably 40 to 97% by mass, more preferably 60 to 95% by mass, still more preferably 70 to 93% by mass, based on 100% by mass of the entire core-shell polymer, and 80 to 90%. Mass% is particularly preferred. If the core layer is less than 40% by mass, the effect of improving the toughness of the cured product may be reduced. When the core layer is larger than 97% by mass, the polymer fine particles tend to aggregate, and the curable epoxy resin composition has a high viscosity and may be difficult to handle.

(Multi-layer structure of core layer)
In the present invention, the core layer may have a multilayer structure. When the core layer has a multilayer structure, the polymer composition of each layer may be different.

(Middle layer)
The core-shell polymer (B) of the present invention may have an intermediate layer between the core layer and the shell layer. . In particular, the following rubber surface cross-linked layer may be formed as the intermediate layer. From the viewpoint of the effect of improving the toughness and the impact resistance improvement effect of the resulting cured product, it is preferable not to contain the following rubber surface cross-linked layer as an intermediate layer.

  The rubber surface cross-linked layer is obtained by polymerizing a rubber surface cross-linked layer component composed of 30 to 100% by mass of a polyfunctional monomer having two or more radical double bonds in the same molecule and 0 to 70% by mass of other vinyl monomers. And an effect of reducing the viscosity of the curable epoxy resin composition of the present invention and an effect of improving the dispersibility of the core-shell polymer (B) in the component (A). It also has the effect of increasing the crosslinking density of the core layer and increasing the grafting efficiency of the shell layer.

  Specific examples of the polyfunctional monomer include the same monomers as the above-mentioned polyfunctional monomer, but preferably allyl methacrylate and triallyl isocyanurate.

(Shell layer)
The shell layer of the core-shell polymer (B) is obtained by polymerizing a monomer for shell formation, and improves the compatibility between the core-shell polymer and the component (A) according to the present invention, and the curable epoxy resin composition of the present invention. Or a shell polymer that plays a role of allowing the core-shell polymer to be dispersed in the form of primary particles in the cured product.

  From the viewpoint that the shell layer of the core-shell polymer (B) of the present invention is low in viscosity while maintaining storage stability, the total amount of monomers constituting the shell layer is 100% by mass, and monomers 0 to 25 having an epoxy group It is preferably composed of 30% by mass of alkyl methacrylate monomers, 30-98% by mass of monomers, and 2-70% by mass of monomers copolymerizable therewith.

  More preferably, the shell layer of the core-shell polymer (B) of the present invention has a total viscosity of 100% from the viewpoint of low viscosity and high dynamic splitting resistance while maintaining storage stability. It consists of 2 to 20% by mass of an epoxy group-containing monomer, 50 to 97% by mass of an alkyl methacrylate monomer, and 1 to 48% by mass of a monomer copolymerizable therewith.

  More preferably, in the shell layer of the core-shell polymer (B) of the present invention, the total amount of monomers constituting the shell layer is 100 from the viewpoint of low viscosity and high dynamic splitting resistance while maintaining storage stability. It consists of 3 to 15% by mass of an epoxy group-containing monomer, 70 to 95% by mass of an alkyl methacrylate monomer, and 1 to 27% by mass of a monomer copolymerizable therewith.

  Examples of the monomer having an epoxy group include allyl glycidyl ether, glycidyl (meth) acrylate, and glycidyl alkyl (meth) acrylate. Glycidyl methacrylate is particularly preferred from the viewpoint of shear bond strength, T-shaped peel bond strength or dynamic splitting resistance.

  Examples of the alkyl methacrylate monomer include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, and behenyl methacrylate. From the viewpoint of low viscosity, methyl methacrylate, ethyl methacrylate, and propyl methacrylate are preferable, and methyl methacrylate is particularly preferable.

  Monomers copolymerizable therewith include styrene, α-methylstyrene, 1- or 2-vinylnaphthalene, monochlorostyrene, dichlorostyrene, bromostyrene, etc .; aromatic vinyl monomers, (meth) acrylonitrile, etc .; vinylcyan monomers, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (2-ethoxyethoxy), etc .; alkoxyalkyl (meth) acrylate monomer, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, Examples include alkyl acrylate monomers such as octyl acrylate, dodecyl acrylate, stearyl acrylate, and behenyl acrylate. Styrene is more preferable from the viewpoint of shear bond strength, T-peel bond strength or dynamic splitting resistance.

(Graft rate of shell layer)
The graft ratio of the shell layer is preferably 70% or more (more preferably 80% or more, and further 90% or more). When the graft ratio is less than 70%, the viscosity of the liquid resin composition may increase. The graft ratio was calculated by first coagulating and dewatering an aqueous latex containing a core-shell polymer, and finally drying to obtain a core-shell polymer powder. Subsequently, 2 g of the core-shell polymer powder was immersed in 100 g of methyl ethyl ketone (MEK) at 23 ° C. for 24 hours, and then the MEK soluble component was separated from the MEK insoluble component, and the methanol insoluble component was further separated from the MEK soluble component. And it calculated by calculating | requiring the ratio of MEK insoluble content with respect to the total amount of MEK insoluble content and methanol insoluble content.

(Method for producing core-shell polymer)
The polymer that forms the core layer constituting the core-shell polymer used in the present invention includes at least one monomer (first monomer) selected from diene monomers (conjugated diene monomers) and (meth) acrylate monomers. In this case, the core layer can be formed, for example, by emulsion polymerization, suspension polymerization, microsuspension polymerization, or the like, and for example, the method described in WO2005 / 028546 can be used.

  In addition, when the polymer forming the core layer is configured to include a polysiloxane polymer, the formation of the core layer can be produced by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, etc. The method described in WO2006 / 070664 can be used.

  The intermediate layer can be formed by polymerizing the monomer for forming the intermediate layer by a known radical polymerization. When the rubber elastic body constituting the core layer is obtained as an emulsion, the polymerization of the monomer having two or more double bonds is preferably carried out by an emulsion polymerization method.

  The shell layer can be formed by polymerizing a shell layer forming monomer by known radical polymerization. In the case where the core layer or a core-shell polymer precursor constituted by coating the core layer with an intermediate layer is obtained as an emulsion, the polymerization of the monomer for forming the shell layer is preferably carried out by an emulsion polymerization method, for example, WO2005 Can be produced according to the method described in Japanese Patent No.

  As an emulsifier (dispersant) that can be used in emulsion polymerization, alkyl or aryl sulfonic acid represented by dioctylsulfosuccinic acid and dodecylbenzenesulfonic acid, alkyl or arylether sulfonic acid, alkyl or aryl represented by dodecylsulfuric acid, and the like. 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 acid represented by dodecyl sarcosine acid, alkyl represented by oleic acid or stearic acid, or Various acids such as aryl carboxylic acids, alkyl or aryl ether carboxylic acids, anionic emulsifiers (dispersants) such as alkali metal salts or ammonium salts of these acids; Nonionic emulsifiers such as-substituted polyethylene glycol (dispersing agent); polyvinyl alcohol, alkyl substituted cellulose, polyvinyl pyrrolidone, dispersants such as polyacrylic acid derivatives. These emulsifiers (dispersants) may be used alone or in combination of two or more.

  As long as the dispersion stability of the aqueous latex of the core-shell polymer is not hindered, it is preferable to reduce the amount of emulsifier (dispersant) used. Moreover, an emulsifier (dispersant) is so preferable that the water solubility is high. If the water solubility is high, the emulsifier (dispersant) can be easily removed by washing with water, and adverse effects on the finally obtained cured product can be easily prevented.

  When the emulsion polymerization method is employed, a known initiator, that is, 2,2′-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, ammonium persulfate, or the like can be used as the thermal decomposition type initiator. .

  In addition, organic peroxides such as t-butylperoxyisopropyl carbonate, paramentane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-hexyl peroxide, etc. Oxides; peroxides such as inorganic peroxides such as hydrogen peroxide, potassium persulfate, and ammonium persulfate; reducing agents such as sodium formaldehyde sulfoxylate and glucose as necessary; and iron sulfate (II as necessary) ), A chelating agent such as disodium ethylenediaminetetraacetate if necessary, and a redox type initiator using a phosphorus-containing compound such as sodium pyrophosphate if necessary.

  When a redox type initiator system is used, the polymerization can be performed at a low temperature at which the peroxide is not substantially thermally decomposed, and the polymerization temperature can be set in a wide range, which is preferable. Of these, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide are preferably used as the redox initiator. When the amount of the initiator used, or the redox type initiator is used, the amount of the reducing agent / transition metal salt / chelating agent used may be within a known range. In the polymerization of a monomer having two or more double bonds, a known chain transfer agent can be used within a known range. In addition, a surfactant can be used, but this is also within a known range.

  When a redox type initiator system is used, the polymerization can be performed at a low temperature at which the peroxide is not substantially thermally decomposed, and the polymerization temperature can be set in a wide range, which is preferable. Of these, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide are preferably used as the redox initiator. When the amount of the initiator used, or the redox type initiator is used, the amount of the reducing agent / transition metal salt / chelating agent used may be within a known range. In the polymerization of a monomer having two or more double bonds, a known chain transfer agent can be used within a known range. In addition, a surfactant can be used, but this is also within a known range.

  The polymerization temperature, pressure, deoxygenation, and other conditions during the polymerization can be within the known ranges. The polymerization of the intermediate layer forming monomer may be performed in one stage or in two or more stages. For example, in addition to a method of adding an intermediate layer forming monomer to a rubber elastic emulsion constituting the elastic core layer at once, a method of continuously adding it, an elastic core layer is added to a reactor in which an intermediate layer forming monomer is charged in advance. For example, a method of carrying out polymerization after adding an emulsion of a rubber elastic body to be constituted can be employed.

(Amount of core-shell polymer (B))
From the balance between easy handling of the resulting curable resin composition and toughness improvement effect of the obtained cured product, the amount of the core-shell polymer is 1 to 50 parts by weight with respect to 100 parts by weight of the (A) epoxy resin. Preferably, 10 to 40 parts by weight is more preferable, and 10 to 35 parts by weight is particularly preferable.

<Blocked isocyanate (C)>
In the present invention, the blocked isocyanate (C) is added for the purpose of further improving performances such as toughness, impact resistance, shearing adhesiveness, and T-peeling adhesiveness. It is effective to use the component (B) and the component (C) in combination.

  The blocked isocyanate (C) of the present invention is an elastomer type, and contains all or part of the terminal isocyanate group of the compound containing a urethane group and / or a urea group and having an isocyanate group at the terminal. Compounds capped with various blocking agents having groups. In particular, a compound in which all of the terminal isocyanate groups are capped with a blocking agent is preferable. Such a compound can be prepared, for example, by reacting an organic polymer having an active hydrogen-containing group at the terminal with an excess of a polyisocyanate compound to have a urethane group and / or a urea group in the main chain and an isocyanate group at the terminal. It is obtained by capping all or part of the isocyanate group with a blocking agent having an active hydrogen group after or simultaneously with the polymer (urethane prepolymer).

The blocked isocyanate is, for example, the following general formula (1):
^{A- (NR 2 -C (= O} ) -X) a (1)
(In the formula, each a ² R ² is independently a hydrocarbon group having 1 to 20 carbon atoms. A represents the average number of capped isocyanate groups per molecule, 1.1 or more. 1.5 to 8 is more preferable, 1.7 to 6 is still more preferable, and 2 to 4 is particularly preferable, and X is a residue obtained by removing an active hydrogen atom from the blocking agent. Is a residue obtained by removing a terminal isocyanate group from an isocyanate-terminated prepolymer.
The number average molecular weight of the blocked isocyanate is preferably a molecular weight in terms of polystyrene measured by GPC, preferably 2000 to 40000, more preferably 3000 to 30000, and particularly preferably 4000 to 20000. 1-4 is preferable, as for molecular weight distribution (ratio of a weight average molecular weight and a number average molecular weight), 1.2-3 are more preferable, and 1.5-2.5 are especially preferable.

(C-1 Organic polymer having an active hydrogen-containing group at the terminal)
As the main chain skeleton constituting the organic polymer having an active hydrogen-containing group at the terminal, a polyether polymer, a polyacrylic polymer, a polyester polymer, a polydiene polymer, a saturated hydrocarbon polymer (polyolefin) ) And polythioether polymers.

(Active hydrogen group)
Examples of the active hydrogen-containing group constituting the organic polymer having an active hydrogen-containing group at the terminal include a hydroxyl group, an amino group, an imino group, and a thiol group. Among these, a hydroxyl group, an amino group, and an imino group are preferable from the viewpoint of availability, and a hydroxyl group is more preferable from the viewpoint of easy handling (viscosity) of the obtained blocked isocyanate.

  Examples of the organic polymer having an active hydrogen-containing group at the terminal include a polyether polymer having a hydroxyl group at the terminal (polyether polyol), and a polyether polymer having an amino group and / or an imino group at the terminal (polyether amine). ), Polyacryl polyol, polyester polyol, diene polymer having a hydroxyl group at the terminal (polydiene polyol), saturated hydrocarbon polymer having a hydroxyl group at the terminal (polyolefin polyol), polythiol compound, polyamine compound, and the like. Among these, polyether polyol, polyether amine, and polyacryl polyol are excellent in compatibility with the component (A), the glass transition temperature of the organic polymer is relatively low, and the resulting cured product is low in temperature. It is preferable because of its excellent impact resistance. In particular, polyether polyols and polyether amines are more preferred because the resulting organic polymer has a low viscosity and good workability, and polyether polyols are particularly preferred.

  The organic polymer having an active hydrogen-containing group at the terminal used when adjusting the urethane prepolymer that is a precursor of blocked isocyanate may be used alone or in combination of two or more.

  The number average molecular weight of the organic polymer having an active hydrogen-containing group at the terminal is preferably from 800 to 7000, more preferably from 1500 to 5000, particularly preferably from 2000 to 4000, in terms of polystyrene equivalent molecular weight measured by GPC.

(Polyether polymer)
The polyether polymer essentially has the general formula (2):
—R ¹ —O— (2)
(Wherein R ¹ is a linear or branched alkylene group having 1 to 14 carbon atoms), and R ¹ in the general formula (2) is a carbon atom. A linear or branched alkylene group having 1 to 14 or 2 to 4 is preferable. Specific examples of the repeating unit represented by the general formula (2) include
_{-CH 2 O -, - CH 2} CH 2 O -, - CH 2 CH (CH 3) O -, - CH 2 CH (C 2 H 5) O -, - CH 2 C (CH 3) 2 O-, _{-CH 2 CH 2 CH 2 CH 2} O-
Etc. The main chain skeleton of the polyether polymer may be composed of only one type of repeating unit, or may be composed of two or more types of repeating units. In particular, a polymer composed mainly of a polypropylene glycol having a propylene oxide repeating unit of 50% by mass or more is preferable from the viewpoint of T-shaped peel adhesion strength. Polytetramethylene glycol (PTMG) obtained by ring-opening polymerization of tetrahydrofuran is preferred from the viewpoint of dynamic splitting resistance.

  Moreover, when using together with (B) component, it is preferable that the ratio of (B) component and (C) component is 0.1-10, It is more preferable that it is 0.2-5, It is especially preferable that it is 3-1.

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

(Polyacryl polyol)
Examples of the polyacrylic polyol include a polyol having a (meth) acrylic acid alkyl ester (co) polymer as a skeleton and a hydroxyl group in the molecule. In particular, a polyacryl polyol obtained by copolymerizing a hydroxyl group-containing (meth) acrylic acid alkyl ester monomer such as 2-hydroxyethyl methacrylate is preferred.
Examples of the polyester polyol include polybasic acids such as maleic acid, fumaric acid, adipic acid, and phthalic acid, and acid anhydrides thereof, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, Examples thereof include polymers obtained by polycondensation with polyhydric alcohols such as diethylene glycol, dipropylene glycol and neopentyl glycol in the presence of an esterification catalyst in a temperature range of 150 to 270 ° C. Further, ring-opening polymers such as ε-caprolactone and valerolactone, and active hydrogen compounds having two or more active hydrogens such as polycarbonate diol and castor oil are also included.

(Polydiene polyol)
Examples of the polydiene polyol include polybutadiene polyol, polyisoprene polyol, polychloroprene polyol, and the like, and polybutadiene polyol is particularly preferable.

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

(C-2 polyisocyanate)
Specific examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene (tolylene) diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; fats such as isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated diphenylmethane diisocyanate. Group polyisocyanates can be mentioned. Among these, aliphatic polyisocyanates are preferable from the viewpoint of heat resistance, and isophorone diisocyanate and hexamethylene diisocyanate are more preferable from the viewpoint of availability.

(C-3 blocking agent)
Examples of the blocking agent include a primary amine blocking agent, a secondary amine blocking agent, an oxime blocking agent, a lactam blocking agent, an active methylene blocking agent, an alcohol blocking agent, a mercaptan blocking agent, and an amide. Blocking agents, imide-based blocking agents, heterocyclic aromatic compound-based blocking agents, hydroxy-functional (meth) acrylate-based blocking agents, and phenol-based blocking agents. Among these, an oxime block agent, a lactam block agent, a hydroxy functional (meth) acrylate block agent, and a phenol block agent are preferable, and a hydroxy functional (meth) acrylate block agent and a phenol block agent are more preferable. A phenolic blocking agent is more preferable.

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

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

(Phenolic block agent)
The phenolic blocking agent contains at least one phenolic hydroxyl group, that is, a hydroxyl group directly bonded to a carbon atom of an aromatic ring. The phenolic compound may have two or more phenolic hydroxyl groups, but preferably contains only one phenolic hydroxyl group. The phenolic compound may contain other substituents, but these substituents are preferably those that do not react with isocyanate groups under the conditions of the capping reaction, and are preferably alkenyl groups and allyl groups. Other substituents include linear, branched, or cycloalkyl alkyl groups; aromatic groups (eg, phenyl, alkyl-substituted phenyl, alkenyl-substituted phenyl, etc.); aryl-substituted alkyl groups; phenol-substituted alkyl groups Can be mentioned. Specific examples of the phenolic blocking agent include phenol, cresol, xylenol, chlorophenol, ethylphenol, allylphenol (especially o-allylphenol), resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1- Bis (4-hydroxylphenyl) -1-phenylethane), bisphenol F, bisphenol K, bisphenol M, tetramethylbiphenol and 2,2′-diallyl-bisphenol A, and the like.

  The blocking agent is preferably bonded to the end of the polymer chain of the urethane prepolymer in such a manner that the terminal to which it is bonded no longer has a reactive group.

The blocking agent may be used alone or in combination of two or more.
The blocked isocyanate may contain a residue of a crosslinking agent, a residue of a chain extender, or both.

(Crosslinking agent)
The molecular weight of the crosslinking agent is preferably 750 or less, more preferably 50 to 500, and a polyol or polyamine compound having at least 3 hydroxyl groups, amino groups and / or imino groups per molecule. Crosslinkers are useful for imparting branching to the blocked isocyanate and increasing the functionality of the blocked isocyanate (ie, the number of capped isocyanate groups per molecule).

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

  Specific examples of the crosslinking agent and chain extender include trimethylolpropane, glycerin, trimethylolethane, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, sucrose, sorbitol, pentaerythritol, ethylenediamine, triethanolamine, monoethanol. Examples include amine, diethanolamine, piperazine, and aminoethylpiperazine. Resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1-bis (4-hydroxylphenyl) -1-phenylethane), bisphenol F, bisphenol K, bisphenol M, tetramethylbiphenol, 2,2 Also included are compounds having two or more phenolic hydroxyl groups, such as' -diallyl-bisphenol A.

(Amount of blocked isocyanate (C))
The amount of blocked isocyanate is preferably 1 to 50 parts by weight, more preferably 10 to 40 parts by weight, and particularly preferably 10 to 35 parts by weight with respect to 100 parts by weight of (A) epoxy resin. If it is less than 1 part by weight, there are cases where the modifying effects such as toughness, impact resistance and adhesiveness are not sufficient, and if it is more than 50 parts by weight, the elastic modulus of the resulting cured product may be low.
A reinforcing agent may be used independently and may be used together 2 or more types.

<Epoxy resin curing agent (D)>
An epoxy resin curing agent (D) can be used in the curable epoxy resin composition of the present invention as necessary.

  When the curable epoxy resin composition of the present invention is used as a one-component adhesive, the component (D) is selected so that the adhesive rapidly cures when heated to a temperature of 80 ° C or higher, preferably 140 ° C or higher. It is preferable to do this. On the contrary, it is preferable to select the component (D) and the component (E) described later so that the curing is very slow even at room temperature (about 22 ° C.) or at least up to 50 ° C.

  Examples of the component (D) include boron trichloride / amine complex, boron trifluoride / amine complex, dicyandiamide, melamine, diallyl melamine, guanamine (for example, acetoguanamine and benzoguanamine), aminotriazole (for example, 3-amino- 1,2,4-triazole), hydrazides (for example, adipic acid dihydrazide, stearic acid dihydrazide, isophthalic acid dihydrazide, semicarbazide), cyanoacetamide, and aromatic polyamines (for example, diaminodiphenylsulfone). It is more preferable to use dicyandiamide, isophthalic acid dihydrazide, adipic acid dihydrazide, or 4,4'-diaminodiphenylsulfone, and dicyandiamide is particularly preferable.

Among the above curing agents, the latent epoxy curing agent is preferable because the curable epoxy resin composition of the present invention can be made into one component.
(D) A component may be used independently and may be used together 2 or more types.
Component (D) is used in an amount sufficient to cure the composition. Typically, sufficient curing agent is provided to consume at least 80% of the epoxide groups present in the composition. A large excess over that required for consumption of epoxide groups is usually not necessary. Component (D) is preferably used in an amount of 1 to 40 parts by weight, more preferably 2 to 30 parts by weight, still more preferably 3 to 25 parts by weight, and 5 to 20 parts by weight per 100 parts by weight of component (A). Part is particularly preferred. If it is less than 1 weight part, the sclerosis | hardenability of the curable epoxy resin composition of this application may worsen. If the amount is more than 40 parts by weight, the storage stability of the curable epoxy resin composition of the present application may be poor and handling may be difficult.

<Curing accelerator (E)>
A hardening accelerator (E) can be used for this invention curable epoxy resin composition as needed.

  The component (E) is a catalyst for promoting the reaction between the epoxy group and the epoxide reactive group on the other component of the curing agent or adhesive.

As the component (E), ureas such as p-chlorophenyl-N, N-dimethylurea (Monuron), 3-phenyl-1,1-dimethylurea (Phenuron), 3,4-dichlorophenyl-N, N- Dimethylurea (Diuron), N- (3-chloro-4-methylphenyl) -N ', N'-dimethylurea (Chlortoluron), tert-acryl- or alkyleneamines such as benzyldimethylamine, 2,4,6 -Tris (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol incorporated in a poly (p-vinylphenol) matrix, piperidine or derivatives thereof, imidazole derivatives, generally C1-C12 alkylene imidazoles Or N-aryl imidazole , For example, 2-ethyl-2-methylimidazole or N- butyl imidazole, 6-caprolactam, and the like. The catalyst may be encapsulated or may be a potential one that becomes active only when the temperature is raised.
(E) A component may be used independently and may be used together 2 or more types.

  The amount of component (E) used is preferably from 0.1 to 10 parts by weight, more preferably from 0.2 to 5 parts by weight, even more preferably from 0.5 to 3 parts by weight, based on 100 parts by weight of component (A). Preferably, 0.8 to 2 parts by weight is particularly preferable. If it is less than 0.1 weight part, the sclerosis | hardenability of the curable epoxy resin composition of this application may worsen. If the amount is more than 10 parts by weight, the storage stability of the curable epoxy resin composition of the present application may be poor and difficult to handle.

<Filler>
A filler can be used in the curable epoxy resin composition of the present invention as necessary. Specific examples of the filler include reinforcing silica fillers such as dry silica such as hydrophobic fumed silica surface-treated with polydimethylsiloxane, wet silica, aluminum silicate, magnesium silicate, calcium silicate, dolomite and carbon black. Plate-like fillers such as talc and wollastonite; colloidal calcium carbonate, heavy calcium carbonate, magnesium carbonate, titanium oxide, ferric oxide, aluminum fine powder, zinc oxide, activated zinc white and the like. A microballoon having an average particle size of up to 200 μm and a density of up to 0.2 g / cc can also be used. The particle size is preferably about 25 to 150 μm and the density is preferably about 0.05 to about 0.15 g / cc. Examples of commercially available microballoons include Dualite manufactured by Dualite Corporation, Expandel manufactured by Akzo Nobel, and Microsphere manufactured by Matsumoto Yushi Seiyaku.

<Reactive diluent>
In addition, the curable epoxy resin composition of the present invention includes, as necessary, a monoepoxide such as aliphatic glycidyl ether such as butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, or 2 as a reactive diluent. -Ethylhexyl glycidyl ether, alkyl C8-C10 glycidyl ether, alkyl C12-C14 glycidyl ether, p-tertbutylphenyl glycidyl ether, neodecanoic acid monoglycidyl ether may be included.

(Other ingredients)
In this invention, another compounding component can be used as needed. Other ingredients include dehydrating agents such as calcium oxide, colorants such as pigments and dyes, extender pigments, UV absorbers, antioxidants, stabilizers (anti-gelling agents), plasticizers, leveling agents, anti-oxidants. Examples include foaming agents, silane coupling agents, antistatic agents, flame retardants, lubricants, viscosity reducers, low shrinkage agents, organic fillers, thermoplastic resins, drying agents, and dispersing agents.

(Cured product)
The present invention includes a cured product obtained by curing the curable epoxy resin composition.

(Use)
The curable epoxy resin composition of the present invention is excellent in storage stability and can be used as a one-component adhesive.

  The curable epoxy resin composition of the present invention includes adhesives such as structural adhesives for vehicles and aircraft, paints, materials for laminating with glass fibers, materials for laminating with carbon fibers, printed wiring boards, and electrical insulating materials. It is preferably used for such applications. In particular, it is useful as a structural adhesive for vehicles.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples, and comparative examples. However, the present invention is not limited to these examples, and may be appropriately modified and implemented within a range that can meet the gist of the preceding and following descriptions. All of which are within the scope of the present invention.

<Evaluation method>
The measuring method of each average particle diameter is described below about the polybutadiene rubber particle in the polybutadiene rubber latex described in the manufacture example, and the core-shell polymer particle in the core-shell polymer latex.

(Measurement of volume average particle size of butadiene rubber particles and core-shell polymer particles in latex)
The volume average particle diameter of the polybutadiene rubber particles in the polybutadiene rubber latex and the core-shell polymer particles in the core-shell polymer latex was measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.).
A sample diluted with deionized water was used as a measurement sample. The measurement is performed by inputting the refractive index of water or methyl ethyl ketone and the refractive index of each core-shell polymer (B), and measuring the sample concentration so that the measurement level is 600 seconds and the Signal Level is in the range of 0.6 to 0.8. Adjusted.

(Storage stability)
The viscosity before storage of the curable epoxy resin composition measured using an E-type viscometer at a shear rate of 2 (s ⁻¹ ) is η0, and the viscosity after storage at 40 ° C. for 7 days is η1. , Evaluation was performed at a magnification of η1 with η0 as 1. The lower the magnification of η1 with η0 as 1, the better the storage stability.
The E type viscometer was measured using a digital viscometer DV-II + Pro type manufactured by BROOKFIELD. Measurement was performed at 23 ° C. using a spindle CPE-52.

(Measurement of viscosity of epoxy resin in which core-shell polymer is dispersed)
Using an E-type viscometer, the shear rate was measured under the condition of 10 (s ⁻¹ ). The E type viscometer was measured using a digital viscometer DV-II + Pro type manufactured by BROOKFIELD. Measurement was performed at 50 ° C. using a spindle CPE-52.

(Shear bond strength)
Apply a curable epoxy resin composition to two SPCC steel sheets of width 25 mm x length 100 mm x thickness 1.6 mm, and paste them so that the adhesive layer is 25 mm wide x 12.5 mm long x 0.13 mm thick In addition, the specimen was cured for 1 hour under the conditions of 170 ° C.

  The shear bond strength with the unit of MPa was measured under the measurement conditions of a measurement temperature of 23 ° C. and a test speed of 1.3 mm / min.

(T-shaped peel adhesion strength)
Applying a curable epoxy resin composition to two SPCC steel sheets of width 25 mm × length 200 mm × thickness 0.5 mm, and bonding them so that the adhesive layer becomes width 25 mm × length 150 mm × thickness 0.26 mm, The specimen was cured at 170 ° C. for 1 hour to prepare a test specimen.
Under the measurement conditions where the measurement temperature was 23 ° C. and the test speed was 254 mm / min, the T-shaped peel adhesion strength with the unit N / 25 mm was measured.

(Dynamic splitting resistance)
Applying a curable epoxy resin composition to two SPCC steel sheets 20 mm wide x 90 mm long x 0.8 mm thick, and bonding them so that the adhesive layer is 20 mm wide x 30 mm long x 0.26 mm thick, The specimen was cured for 1 hour under the condition of 170 ° C.

  The dynamic splitting resistance with the unit of kN / m was measured under the measurement conditions of a measurement temperature of 23 ° C., an impact energy of 50 J, and an impact speed of 2 m / s.

<Production example of core-shell polymer (B), production example of epoxy resin (N) in which core-shell polymer is dispersed>
In Production Example 1-1 and Production Example 1-2, preparation methods of polybutadiene rubber latex (R-1) and (R-2) containing polybutadiene rubber which is a core layer of a core-shell polymer are described.
The preparation methods of core-shell polymer latex (L-1) to (L-8) were described in Production Example 2-1 to Production Example 2-8.

  In Production Example 3-1 to Production Example 3-8, the preparation method of the epoxy resin (N) in which the core-shell polymer is dispersed is described.

Production Example 1-1: Preparation of polybutadiene rubber latex (R-1) In a pressure-resistant polymerizer, 200 parts by weight of deionized water, 0.03 part by weight of tripotassium phosphate, disodium ethylenediaminetetraacetate (EDTA) 0.002 Add parts by weight, ferrous sulfate and heptahydrate 0.001 part by weight, and sodium dodecylbenzenesulfonate (SDBS) 1.55 part by weight, and thoroughly purge with nitrogen to remove oxygen. Thereafter, 100 parts by weight of butadiene (Bd) was charged into the system, and the temperature was raised to 45 ° C. Polymerization was initiated by adding 0.03 parts by weight of paramentane hydroperoxide (PHP), followed by 0.10 parts by weight of sodium formaldehyde sulfoxylate (SFS). 0.03 part by weight of paramentane hydroperoxide (PHP) was added at 3, 5, and 7 hours from the start of polymerization. In addition, 0.0006 parts by weight of EDTA and 0.003 parts by weight of ferrous sulfate heptahydrate were added at 4, 6, and 8 hours after the start of polymerization. At 15 hours after polymerization, the residual monomer was removed by devolatilization under reduced pressure to complete the polymerization, and a polybutadiene rubber latex (R-1) containing polybutadiene rubber as a main component was obtained. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 0.08 μm.

Production Example 1-2: Preparation of polybutadiene rubber latex (R-2)
21 parts by weight (including 7 parts by weight of polybutadiene rubber) of polybutadiene rubber latex (R-1) obtained in Production Example 1-1, 185 parts by weight of deionized water, and 0.03 of tripotassium phosphate in a pressure-resistant polymerization machine. Parts by weight, 0.002 parts by weight of EDTA, and 0.001 part by weight of ferrous sulfate and heptahydrate, and after sufficiently purging nitrogen with stirring to remove oxygen, 93 parts by weight of Bd were added to the system. And heated to 45 ° C. Polymerization was started by adding 0.02 part by weight of PHP and subsequently 0.10 part by weight of SFS. 0.025 parts by weight of PHP, 0.0006 parts by weight of EDTA, and 0.003 parts by weight of ferrous sulfate heptahydrate were added every 3 hours from the start of polymerization to 24 hours. At 30 hours after polymerization, the residual monomer was removed by devolatilization under reduced pressure to complete the polymerization, and a polybutadiene rubber latex (R-2) containing polybutadiene rubber as a main component was obtained. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 0.20 μm.

Production Example 2 Preparation of Core-Shell Polymer Latex (L) In Table 1, production examples of core-shell polymers (L-1) to (L-8) are shown as Production Example 2-1 to Production Example 2-8.

Production Example 2-1: Preparation of Core-Shell Polymer Latex (L-1) Polybutadiene rubber prepared in Production Example 1 in a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device 262 parts by weight of polybutadiene rubber latex (R-1) containing 87 parts by weight of particles and 59 parts by weight of deionized water were charged and stirred at 60 ° C. while performing nitrogen substitution. After adding 0.005 part by weight of EDTA, 0.001 part by weight of ferrous sulfate and heptahydrate, and 0.2 part by weight of SFS, 13 parts by weight of graft monomer (0.5 part by weight of styrene, A mixture of methyl methacrylate (12.5 parts by weight) and cumene hydroperoxide (0.035 parts by weight) was continuously added over 1.3 hours for graft polymerization. After completion of the addition, the reaction was terminated by further stirring for 2 hours to obtain a core-shell polymer latex (L-1). The volume average particle size of the core-shell polymer contained in the obtained latex was 0.10 μm.

Production Example 2-2 to Production Example 2-5
A core-shell polymer latex was prepared in the same manner with the polybutadiene rubber latex and graft monomer in Production Example 2-1 at the levels shown in Table 1. Table 1 shows the volume average particle diameters of the core-shell polymers (L-1) to (L-5).

Production Example 2-6: Preparation of Core-Shell Polymer Latex (L-6) Polybutadiene rubber obtained in Production Example 1 in a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device 195.9 parts by weight of latex (R-1) (including 65.3 parts by weight of polybutadiene rubber particles), 65.1 parts by weight of polybutadiene rubber latex (R-2) obtained in Production Example 2 (21.7 parts of polybutadiene rubber particles) And 56 parts by weight of deionized water were added and stirred at 60 ° C. while purging with nitrogen. After adding 0.002 part by weight of EDTA, 0.001 part by weight of ferrous sulfate heptahydrate, and 0.13 part by weight of SFS, 1.8 parts by weight of triallyl isocyanurate (TAIC) and cumene hydroperoxide 0.03 part by weight was added and stirred for 1 hour. Thereafter, a mixture of 13 parts by weight of graft monomer (11.5 parts by weight of methyl methacrylate and 1.5 parts by weight of glycidyl methacrylate) and 0.035 parts by weight of cumene hydroperoxide for forming the shell layer was added over 1.3 hours. Added continuously. After completion of the addition, the reaction was terminated by further stirring for 2 hours to obtain a core-shell polymer latex (L-6). The volume average particle size of the core-shell polymer contained in the obtained latex was 0.19 μm.

Production Example 2-7 and Production Example 2-8
The core-shell polymer latex was prepared in the same manner with the graft monomer in Production Example 2-6 at the level shown in Table 1. Table 1 shows the volume average particle diameters of the core-shell polymers (L-7) and (L-8).

Production Example 3; Preparation of epoxy resin (N) in which core-shell polymer is dispersed
Production Example 3-1: Preparation of Epoxy Resin (N-1) Dispersing Core-Shell Polymer Into a 1 L mixing tank at 25 ° C., 132 g of methyl ethyl ketone was introduced and stirred, while the core shell obtained in Production Example 2-1 was stirred. 132 g of aqueous latex (L-1) containing 40 g of polymer was added. After mixing uniformly, 200 g of water was added at a feed rate of 80 g / min. When water was supplied and stirring was immediately stopped, a slurry liquid composed of an aqueous phase partially containing a floating aggregate and an organic solvent was obtained. Next, an agglomerate containing a part of the aqueous phase was left, and 360 g of the aqueous phase was discharged from the discharge port at the bottom of the tank. 90 g of methyl ethyl ketone was added to the obtained aggregate and mixed uniformly to obtain a solution in which the core-shell polymer was dispersed. An epoxy resin (A-1: Mitsubishi Chemical Co., Ltd., JER828EL) 80 g is mixed with this solution, and volatile components are removed by a rotary evaporator to disperse the core-shell polymer. (N-1) was obtained.

Production Example 3-2 to Production Example 3-8
The core-shell polymer aqueous latex (L-1) of Production Example 3-1 was replaced with the core-shell polymer aqueous latex (L-2) to (L-8) of Production Example 3-1 to Production Example 3-8. Epoxy resins (N-2) to (N-8) in which the core-shell polymer was dispersed were obtained in the same manner as in Production Example 3-1.

Example 1-4 and Comparative Example 1-4
In Table 2, as Examples 1-4 and Comparative Examples 1-4, the mixing ratio and compounding composition and evaluation (thixotropic property, storage stability) of the curable epoxy resin composition, and the cured product of the curable epoxy resin composition Evaluation (shear adhesive strength, T-shaped peel adhesive strength, dynamic splitting resistance) is shown.

  Example 5 and Comparative Examples 5 and 6 Table 3 shows the evaluation (viscosity) of the curable epoxy resin composition in which (N) the core-shell polymer is dispersed as Example 5 and Comparative Examples 5 and 6.

<Combination agent>
In addition, the compounding raw material used in Table 2 and Table 3 is shown below.
(A) Epoxy resin (A-1) JER828EL (Mitsubishi Chemical make, bisphenol A type epoxy resin)
(N) Epoxy resin compositions (N-1) to (N-7) in which a core-shell polymer is dispersed; described in Production Examples 3-1 to 3-7.
(B) Core-shell polymers (B-1) to (B-7); core-shell polymers contained in the core-shell polymer latices (L-1) to (L-7) described in Production Examples 2-1 to 2-7 It is. See Table 1 for composition.
(C) Blocked isocyanate (C-1) Adeka Resin QR-9466 (manufactured by ADEKA, blocked isocyanate containing polypropylene glycol structure, block NCO equivalent 220, viscosity 30000 mPa · s / 25 ° C.)
(C-2) Flexibilizer DY 965 (manufactured by Huntsman, blocked isocyanate containing polytetramethylene glycol structure, Epoxide Eq. Weight 558-667 [EEW, g / eq], viscosity 4400-12800 cP / 25 ° C.)
(D) Epoxy resin curing agent (D-1) Dyhard 100S (AlzChem, dicyandiamide)
(E) Curing accelerator (E-1) Dyhard UR300 (AlzChem, 1,1-dimethyl-3-phenylurea)
Other ingredients (heavy calcium carbonate) Whiten SB red (Shiraishi calcium, untreated heavy calcium carbonate, average particle size: 1.8μm)
(Calcium oxide) CML # 31 (Omi Chemical Industries)
(Carbon black) MONARCH 280 (manufactured by Cabot)
(Reactive diluent) Cardula E10P (manufactured by Momentive, Versatic acid glycidyl ester)

Claims (13)

(A) For 100 parts by weight of epoxy resin,
(B) A curable epoxy resin composition containing 1 to 50 parts by weight of a core-shell polymer and (C) 1 to 50 parts by weight of a blocked isocyanate,
(B) The core layer of the core-shell polymer consists of any of diene rubber, acrylic rubber, and polysiloxane rubber,
(B) The shell layer of the core-shell polymer makes the total amount of monomers constituting the shell layer 100% by mass, the alkyl methacrylate monomer 30 to 98% by mass, the monomer having an epoxy group 0 to 25% by mass, and a monomer copolymerizable therewith A curable epoxy resin composition comprising 2 to 70% by mass. (B) The shell layer of the core-shell polymer makes the total amount of monomers constituting the shell layer 100% by mass, the alkyl methacrylate monomer 50 to 97% by mass, the monomer having an epoxy group 2 to 20% by mass, and a monomer copolymerizable therewith It consists of 1-48 mass%, The curable epoxy resin composition of Claim 1 characterized by the above-mentioned.   The curable epoxy resin composition according to claim 1, wherein the alkyl methacrylate monomer is at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, and propyl methacrylate.   The curable epoxy resin composition according to claim 1, wherein the monomer having an epoxy group is glycidyl methacrylate. (B) The curable epoxy resin composition according to any one of claims 1 to 4, wherein the core layer of the core-shell polymer is made of butadiene rubber and / or butadiene-styrene rubber. (B) The volume average particle diameter of the core-shell polymer is 0.05 to 0.30 μm, The curable epoxy resin composition according to any one of claims 1 to 5. The curable epoxy resin composition according to any one of claims 1 to 6, wherein (C) the blocked isocyanate is a compound obtained by capping a urethane prepolymer containing a polypropylene glycol structure with a blocking agent. The curable epoxy resin composition according to any one of claims 1 to 6, wherein (C) the blocked isocyanate is a compound obtained by capping a urethane prepolymer containing a polytetramethylene glycol structure with a blocking agent. Furthermore, 1-40 weight part of epoxy hardening | curing agents (D) are contained, The curable epoxy resin composition in any one of Claim 1 to 8 characterized by the above-mentioned. Furthermore, 0.1-10 weight part of hardening accelerators (E) are contained, The curable epoxy resin composition in any one of Claim 1 to 9 characterized by the above-mentioned. A cured product obtained by curing the curable epoxy resin composition according to claim 1. A structural adhesive comprising the curable epoxy resin composition according to claim 1. The structural adhesive for vehicles formed using the curable epoxy resin composition in any one of Claim 1 to 10.