JP6694425B2 - Curable epoxy resin composition having excellent thixotropy - Google Patents

Description

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

  Epoxy resins are used in a wide range of applications, one of which is an adhesive. The cured epoxy resin shows excellent mechanical properties, electrical properties, and durability, but in order to improve brittleness and impact resistance, a curable epoxy resin composition is used in structural adhesives for vehicles. There are cases where a core-shell polymer and a blocked isocyanate are contained in the product (Patent Document 1).

  This structural adhesive is also important in handleability in the production line and difficulty in being washed off in the shower process existing between the coating process and the curing process (Patent Document 2). In particular, in the shower step, the composition may be partially dissolved, scattered, or deformed due to water pressure, which leads to deterioration of the coated part. One solution to this problem is to increase the viscosity of the curable epoxy resin composition, but there is a problem in that the coating workability is reduced.

Japanese Patent Publication No. 2010-530472 JP-A-8-302278

In order to impart the wash-off resistance, it is considered effective that the curable epoxy resin composition has a so-called thixotropic property that the viscosity at low shear is higher than the viscosity at high shear. However, Patent Documents 1 and 2 above do not teach any means for improving thixotropy.
On the other hand, the present inventors have found that in the curable epoxy resin composition, thixotropy is changed depending on the shell layer component of the core-shell polymer and the amount thereof, and diligently studying the shell layer of the core-shell polymer. I chose
The present invention has been made in view of the above circumstances, and an object thereof is to provide a curable epoxy resin composition which is excellent in thixotropy and further excellent in adhesiveness of a cured product obtained.

  In the composition containing an epoxy resin, a core-shell polymer and a blocked isocyanate, the present inventors have found that when the shell layer of the core-shell polymer is composed of a specific monomer and a specific amount, the thixotropic property of the composition and the adhesion of the cured product thereof. The present invention has been completed by finding that the property is improved. The gist of the present invention is as follows.

  1) A curable epoxy resin composition containing 1 to 50 parts by mass of a core-shell polymer (B) and 1 to 50 parts by mass of a blocked isocyanate (C) with respect to 100 parts by mass of an epoxy resin (A), which is a core-shell polymer. The core layer of (B) is made of a diene rubber, an acrylic rubber, or a polysiloxane rubber, and the shell layer of the core-shell polymer (B) has 100% by mass of the total amount of monomers constituting the shell layer, and vinyl. 10 to 95% by weight of a monomer selected from the group consisting of a cyan monomer and an alkoxyalkyl (meth) acrylate monomer, 0 to 50% by weight of a monomer having an epoxy group, and 0 to 90% by weight of a monomer copolymerizable therewith. A curable epoxy resin composition characterized by the above.

  2) The curable epoxy resin composition according to 1), wherein the monomer copolymerizable with them is 5 to 90% by mass.

  3) The shell layer of the core-shell polymer (B), with the total amount of the monomers constituting the shell layer being 100% by mass, 20 to 40% by mass of a vinyl cyan monomer, 3 to 15% by mass of a monomer having an epoxy group, and copolymerization thereof. The curable epoxy resin composition according to 1) or 2), which comprises 60 to 80 mass% of possible monomers.

  4) In the shell layer of the core-shell polymer (B), the total amount of monomers constituting the shell layer is 100% by mass, and 50 to 95% by mass of an alkoxyalkyl (meth) acrylate monomer and 5 to 50% by mass of a monomer having an epoxy group. 1. The curable epoxy resin composition according to 1).

  5) The shell layer of the core-shell polymer (B) has 90% to 95% by mass of the alkoxyalkyl (meth) acrylate monomer and 5 to 10% by mass of the epoxy group-containing monomer, with the total amount of the monomers constituting the shell layer being 100% by mass. The curable epoxy resin composition according to 1) or 4).

  6) The curable epoxy resin composition according to any one of 1) to 3), wherein the vinyl cyan monomer is acrylonitrile.

  7) The curable epoxy resin composition according to any one of 1) to 6), wherein the monomer having an epoxy group is glycidyl methacrylate.

  8) The curable epoxy resin composition according to any one of 1), 2), 4) to 7), wherein the alkoxyalkyl (meth) acrylate monomer is 2-methoxyethyl acrylate.

  9) The curable epoxy resin composition according to any one of 1) to 8), wherein the core layer of the core-shell polymer (B) is made of butadiene rubber and / or butadiene-styrene rubber.

  10) The curable epoxy resin composition according to any one of 1) to 9), wherein the core-shell polymer (B) has a volume average particle diameter of 0.05 to 0.30 μm.

  11) The curable epoxy resin composition according to any one of 1) to 10), wherein the blocked isocyanate (C) is a compound obtained by capping a urethane prepolymer having a polypropylene glycol structure with a blocking agent.

  12) The curable epoxy resin composition according to any one of 1) to 10), wherein the blocked isocyanate (C) is a compound obtained by capping a urethane prepolymer having a polytetramethylene glycol structure with a blocking agent.

  13) The curable epoxy resin composition according to any one of 1) to 12), which further contains 1 to 40 parts by mass of an epoxy curing agent (D).

  14) The curable epoxy resin composition according to any one of 1) to 13), which further contains 0.1 to 10 parts by mass of a curing accelerator (E).

  15) A cured product obtained by curing the curable epoxy resin composition according to any one of 1) to 14).

  16) A structural adhesive comprising the curable epoxy resin composition according to any one of 1) to 14).

  17) A structural adhesive for vehicles, which comprises the curable epoxy resin composition according to any one of 1) to 14).

  The curable epoxy resin composition of the present invention has excellent thixotropy and adhesiveness to a cured product.

FIG. 1 shows the relationship between the storage stability and thixotropy of the epoxy group-containing monomer in the shell layer of the core-shell polymer in the curable epoxy resin composition of the present invention using a blocked isocyanate having a polypropylene glycol structure. FIG. FIG. 2 is a T-shaped peel adhesive strength (indicated by T-Peel in the figure) and a shear adhesive strength (FIG. 2) in the curable epoxy resin composition of the present invention using a blocked isocyanate having a polypropylene glycol structure. FIG. 3 is a diagram showing the relationship between the amount of monomer having an epoxy group in the shell layer of the core-shell polymer and the amount of monomer having Lap Shear). FIG. 3 shows the dynamic splitting resistance (indicated by Impact Peel in the figure) and the epoxy group of the shell layer of the core-shell polymer in the curable epoxy resin composition of the present invention using a blocked isocyanate having a polypropylene glycol structure. It is a figure which shows the relationship with the amount of monomers having. FIG. 4 shows the relationship between the amount of the epoxy group-containing monomer in the shell layer of the core-shell polymer and the storage stability and thixotropy in the curable epoxy resin composition of the present invention using the blocked isocyanate having a polytetramethylene glycol structure. FIG. FIG. 5 is a T-shaped peel adhesive strength (indicated by T-Peel in the figure) and a shear adhesive strength in the curable epoxy resin composition of the present invention using a blocked isocyanate having a polytetramethylene glycol structure. FIG. 3 is a diagram showing the relationship between (indicated by Lap Shear in the figure) and the amount of a monomer having an epoxy group in the shell layer of the core-shell polymer. FIG. 6 shows the dynamic cleavage resistance (indicated by Impact Peel in the figure) and the shell layer of the core-shell polymer in the curable epoxy resin composition of the present invention using a blocked isocyanate having a polytetramethylene glycol structure. It is a figure which shows the relationship with the amount of monomers having an epoxy group.

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

<Epoxy resin (A)>
(A-1) 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 the epoxy used in the present invention The resin is preferably an epoxy resin, also called polyepoxide. Examples of the epoxy resin include polyglycidyl ethers (bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenol type epoxy resin, such as addition reaction products of polyphenols such as bisphenol A 1, bisphenol F 2, biphenol, and phenol novolac with epichlorohydrin. Epoxy resin, phenol novolac type epoxy resin, etc.), polyamines such as aniline, diaminobenzene, aminophenol, phenylenediamine, diaminophenyl ether, etc., and polyvalent glycidylamine compounds derived from polyvalent amine, cycloaliphatic epoxy, etc. Alicyclic epoxy resins having a structure, addition reaction products of polyhydric alcohols with epichlorohydrin, and halogens in which a part of hydrogens thereof is replaced with a halogen element such as bromine Epoxy resins, such as homopolymers or copolymers obtained by polymerizing a monomer containing an unsaturated monoepoxide and allyl glycidyl ether can be exemplified. Many polyepoxides synthesized from polyhydric phenols are disclosed, for example, in US Pat. No. 4,431,782. Further examples of polyepoxides are those disclosed in U.S. Pat. Nos. 3,804,735, 3,892,819, 3,948,698, 4014771, and Epoxy Resin Handbook (Nikkan Kogyo Shimbun, 1987). Can be mentioned.

(A-2) Polyalkylene glycol diglycidyl ether, glycol diglycidyl ether, etc. Further, as the epoxy resin (A) of the present invention, polyalkylene glycol diglycidyl ether, glycol diglycidyl ether, diglycidyl aliphatic polybasic acid Esters, glycidyl ethers of dihydric or higher polyhydric 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 a reactive diluent, and the viscosity of the composition and the cured product. The balance of physical properties can be improved.

  The content of these epoxy resins is preferably 0.5 to 20% by mass in 100% by mass of the epoxy resin (A) component, more preferably 1 to 10% by mass, and further preferably 2 to 5% by mass. More specifically, examples of the polyalkylene glycol diglycidyl ether include polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether. Specific examples of the glycol diglycidyl ether include neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether. Be done. Specific examples of the diglycidyl ester of an aliphatic polybasic acid include dimer acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, and maleic acid diglycidyl ester. As the glycidyl ether of the dihydric or higher polyhydric aliphatic alcohol, more specifically, trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, castor oil modified polyglycidyl ether, propoxylated glycerin triglycidyl ether, sorbitol. Examples thereof include polyglycidyl ether.

(A-3) Epoxy Compound Obtained by Addition Reaction of Polybasic Acid or the Like with Epoxy Resin Furthermore, as the epoxy resin (A) of the present invention, epoxy resins such as those described in WO 2010/098950 can be used. 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. Further, chelate-modified epoxy resin, rubber-modified epoxy resin, and urethane-modified epoxy resin can also be used as the epoxy resin (A) component.

  The epoxy resin that can be used in the present invention is as described above, but generally, one having an epoxy equivalent of 80 to 2000 can be mentioned. These polyepoxides can be obtained by a well-known method, and a commonly used method includes, for example, reacting a polyhydric alcohol or a polyhydric phenol with an excess amount of epihalohydrin 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. A chelate-modified epoxy resin is a reaction product of an epoxy resin and a compound containing a chelate functional group (chelate ligand), and when added to the resin composition of the present invention and used as an adhesive for vehicles, it is an oily substance. It is possible to improve the adhesiveness to the surface of the metal substrate contaminated with. The chelate functional group is a functional group of a compound having a plurality of coordination sites in the molecule capable of coordinating to a metal ion, and examples thereof include a phosphorus-containing acid group (eg, —PO (OH) ₂ ), a carboxylic acid group (- CO ₂ H), a sulfur-containing acid group (for example, —SO ₃ H), an amino group and a hydroxyl group (particularly, hydroxyl groups adjacent to each other in an aromatic ring). Examples of the chelate ligand include ethylenediamine, bipyridine, ethylenediaminetetraacetic acid, phenanthroline, porphyrin, crown ether, and the like. Examples of commercially available chelate-modified epoxy resin include ADEKA Resin EP-49-10N manufactured by ADEKA. The amount of the chelate-modified epoxy resin used in 100% by mass of the epoxy resin (A) component 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 with an epoxy group-containing compound and having 1.1 or more epoxy groups per molecule on average. As the 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 may be a product obtained by reacting these rubber-based polymer with an epoxy resin at an appropriate mixing ratio by a known method. Among these, acrylonitrile-butadiene rubber-modified epoxy resin and polyoxyalkylene-modified epoxy resin are preferable from the viewpoint of adhesiveness and impact peeling adhesion of the resulting resin composition, and acrylonitrile-butadiene rubber-modified epoxy resin is more preferable. .. The acrylonitrile-butadiene rubber modified epoxy resin may be obtained, for example, by reacting a carboxyl group terminal NBR (CTBN) with a bisphenol A type epoxy resin. Further, the polyoxyalkylene-modified epoxy resin may be obtained, for example, by reacting an amino group-terminated polyoxyalkylene with a bisphenol A type epoxy resin.
The content of the acrylonitrile monomer component in 100% by mass of the acrylonitrile-butadiene rubber is preferably 5 to 40% by mass, and 10 to 35% by mass, from the viewpoint of the adhesiveness and impact peeling adhesiveness of the obtained resin composition. % Is more preferable, and 15 to 30% by mass is further preferable. From the viewpoint of thixotropy of the obtained resin composition, 20 to 30% by mass is particularly preferable.

  The average number of epoxide-reactive terminal 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 equivalent molecular weight measured by GPC.

  The method for producing the rubber-modified epoxy resin is not particularly limited, and for example, it can be produced by reacting the rubber with the epoxy group-containing compound in a large amount of the epoxy group-containing compound. Specifically, it is preferable to produce by reacting 2 equivalents or more of an epoxy group-containing compound with 1 equivalent of the epoxy-reactive terminal group in the rubber. More preferably, the resulting product is reacted with a sufficient amount of the epoxy group-containing compound to form a mixture of the rubber-epoxy group-containing compound adduct and the free epoxy group-containing compound. The rubber-modified epoxy resin may be 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 when producing the rubber-modified epoxy resin is not particularly limited, but a bisphenol A type epoxy resin or a bisphenol F type epoxy resin is preferable, and a bisphenol A type epoxy resin is more preferable. In the present invention, when an excess 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 the rubber-modified epoxy resin of the present application. It shall not be included.

  The rubber-modified epoxy resin can be modified by pre-reacting with the bisphenol component. The bisphenol component used for the modification is preferably 3 to 35 parts by mass, more preferably 5 to 25 parts by mass, based on 100 parts by mass 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 has excellent adhesion durability after exposure to high temperatures and also excellent 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, further preferably −40 ° C. or lower, particularly preferably −50 ° C. or lower.

The content of the rubber-modified epoxy resin in 100% by mass of the epoxy resin (A) component is preferably 1 to 40% by mass, more preferably 3 to 30% by mass, further preferably 5 to 25% by mass, and 10 to 20% by mass. % Is particularly preferred. If it is less than 1% by mass, the obtained cured product may be fragile and the impact peel adhesion may be low, and if it is more than 40% by mass, the heat resistance and elastic modulus (rigidity) of the obtained cured product may be low.
The rubber-modified epoxy resin can be used alone or in combination of two or more kinds.

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

The content of the urethane-modified epoxy resin in 100% by mass of the epoxy resin (A) component is preferably 1 to 40% by mass, more preferably 3 to 30% by mass, further preferably 5 to 25% by mass, and 10 to 20% by mass. % Is particularly preferred. If it is less than 1% by mass, the obtained cured product may be fragile and the impact peel adhesion may be low, and if it is more than 40% by mass, the heat resistance and elastic modulus (rigidity) of the obtained cured product may be low.
The urethane-modified epoxy resin can be used alone or in combination of two or more kinds.

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

  The epoxy equivalent of the epoxy resin (A) of the present invention is preferably less than 220, more preferably 90 or more and 210 or less, still more preferably 150 or more and 200 or less, from the viewpoint of high elastic modulus and heat resistance of the obtained cured product. 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 a liquid at room temperature and the resulting resin composition is easy to handle.

  The bisphenol A type epoxy resin or the bisphenol F type epoxy resin having an epoxy equivalent of 220 or more and less than 2000 is preferably contained in an amount of 40% by mass or less, more preferably 20% by mass or less in 100% by mass of the epoxy resin (A) component. When added, the resulting cured product is excellent in impact resistance, which is preferable.

<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. Further, 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, further preferably 0.05 to 0.30 μm, and 0.08. ˜0.30 μm is particularly preferable. It is often difficult to stably obtain particles having a volume average particle diameter of less than 0.03 μm, and when it exceeds 2.10 μm, the heat resistance and impact resistance of the final molded product may be deteriorated.

Hereinafter, each layer will be described.
(Core layer)
The core layer uses any of diene rubber, acrylic rubber, and polysiloxane rubber.
The core layer of the core-shell polymer (B) of the present invention contains 50 to 100 mass of at least one monomer (first monomer) selected from natural rubber and diene-based monomers (conjugated diene-based monomers) and (meth) acrylate-based monomers. %, And 0 to 50% by mass of another copolymerizable vinyl monomer (second monomer), a rubber elastic body, a polysiloxane rubber elastic body, or a combination thereof. The core layer of the core-shell polymer (B) has a high toughness-improving effect and a high impact-peeling-adhesion-improving effect on the resulting cured product, and has a low affinity with the matrix resin, so that the core layer swells over time. A diene rubber using a diene monomer is preferable because the viscosity is unlikely to increase. A (meth) acrylate rubber is preferable because a wide range of polymer designs can be made by combining various monomers. Further, in order to improve impact resistance at low temperature without lowering the heat resistance of the cured product, the elastic core layer is preferably a polysiloxane rubber. In addition, in this invention, (meth) acrylate means an acrylate and / or a methacrylate.

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

  The core layer of the core-shell polymer (B) has a high effect of improving the toughness and an effect of improving the adhesiveness against impact peeling, and has a low affinity with the matrix resin, so that the viscosity of the core layer is unlikely to increase with time due to swelling of the core layer. From the viewpoint, butadiene rubber using 1,3-butadiene and / or butadiene-styrene rubber which is a copolymer of 1,3-butadiene and styrene is preferable, and butadiene rubber is more preferable. Further, butadiene-styrene rubber is more preferable because it can increase the transparency of a cured product obtained by adjusting the refractive index.

(Core layer (acrylic rubber))
Examples of the (meth) acrylate rubber monomer as the first monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate. , Dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate and other alkyl (meth) acrylates; phenoxyethyl (meth) acrylate, benzyl (meth) acrylate and other aromatic ring-containing (meth) acrylates; 2 -Hydroxyalkyl (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 Examples thereof include polyfunctional (meth) acrylates such as (meth) acrylate and tetraethylene glycol di (meth) acrylate. These (meth) acrylate-based monomers may be used alone or in combination of two or more kinds. 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 vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; vinylcarboxylic 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 Examples thereof include polyfunctional monomers such as isocyanurate and divinylbenzene. These vinyl-based monomers may be used alone or in combination of two or more kinds. Particularly preferred is styrene.

(Polysiloxane rubber)
The polysiloxane rubber is composed of alkyl or aryl disubstituted silyloxy units such as dimethylsilyloxy, diethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, dimethylsilyloxy-diphenylsilyloxy. Examples thereof include polysiloxane-based polymers and polysiloxane-based polymers composed of alkyl- or aryl-1-substituted silyloxy units such as organohydrogensilyloxy in which a part of side chain alkyl is substituted with hydrogen atoms. These polysiloxane polymers may be used alone or in combination of two or more. Among them, dimethylsilyloxy, methylphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy are 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 polysiloxane-based rubber, the polysiloxane-based polymer portion is 80% by mass or more (more preferably 90% by mass) based on 100% by mass of the rubber elastic body in order not to impair the heat resistance of the cured product. Mass% or more) is preferable.

(Cross-linking of core layer)
From the viewpoint of maintaining dispersion stability in the curable epoxy resin composition, the core layer of the core-shell polymer (B) preferably has a crosslinked structure. Examples of the method of introducing a crosslinked structure include a method of adding a crosslinkable monomer such as a polyfunctional monomer or a mercapto group-containing compound to a polymer component, and then polymerizing. In addition, as a method for introducing a crosslinked structure into a polysiloxane-based polymer, a method in which a polyfunctional alkoxysilane compound is partially used during polymerization, or a reactive group such as a vinyl reactive group or a mercapto group is added to the polysiloxane-based polymer. Introduced into, then a method of radically reacting by adding a vinyl polymerizable monomer or an organic peroxide, or by adding a crosslinkable monomer such as a polyfunctional monomer or a mercapto group-containing compound to the polysiloxane polymer, Then, a method of polymerizing may be mentioned.

(Polyfunctional monomer)
Examples of the polyfunctional monomers include allylalkyl (meth) acrylates such as allyl (meth) acrylate and allylalkyl (meth) acrylate; allyloxyalkyl (meth) acrylates; (poly) ethylene glycol di (meth) acrylate; Multifunctional (meth) having two or more (meth) acryl groups such as butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate Acrylates; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene and the like can be mentioned. 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 properties as a rubber in order to enhance 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. It is more preferable that the amount is 95% by mass or more. The gel content is 0.5 g of the core-shell polymer obtained by coagulation and drying, immersed in 100 g of toluene, and allowed to stand at 23 ° C. for 24 hours and then separated from the insoluble content and the soluble content. Means the ratio of insoluble matter to the total amount of minutes.

(Tg of core layer)
In the present invention, the glass transition temperature (hereinafter sometimes simply referred to as “Tg”) of the core layer of the core-shell polymer (B) is preferably 0 ° C. or lower in order to enhance the toughness of the obtained 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 reduction in rigidity of the obtained cured product, the Tg of the core layer is preferably higher than 0 ° C, more preferably 20 ° C or higher, and further preferably 50 ° C or higher. 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 of higher than 0 ° C. and suppressing a decrease in rigidity of the obtained cured product, at least one monomer having a Tg of a homopolymer of higher than 0 ° C. is 50 to 100 mass. % (Preferably 65 to 99% by mass) and 0 to 50% by mass (preferably 1 to 35% by mass) of at least one monomer having a homopolymer Tg of 0 ° C. or less. Is mentioned.

  Monomers whose homopolymer Tg is higher than 0 ° C. include, for example, unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; vinyl-substituted aromatic compounds such as α-methylstyrene; 3-methylstyrene, Ring-alkylated vinyl aromatic compounds such as 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene and 2,4,6-trimethylstyrene; 4-methoxystyrene, Ring-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-hydroxylated vinyl aromatic compounds such as 4-hydroxystyrene; vinyl benzoate, vinyl chloride Vinyl esters such as hexanoate; Vinyl halides such as vinyl chloride; Aromatic monomers such as asenaphthalene and indene; Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and isopropyl methacrylate; Aromatic methacrylates such as phenyl methacrylate; Iso Methacrylates 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; and 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. Examples include monomers.

(Average particle size 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. It is often difficult to stably obtain particles having a volume average particle size of less than 0.03 μm, and if 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, and 80 to 90% based on 100% by mass of the entire core-shell polymer. 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 decrease. If the core layer is larger than 97% by mass, the polymer fine particles are likely to aggregate, and the curable epoxy resin composition may have high viscosity and may be difficult to handle.

(Multilayer structure of core layer)
In the present invention, the core layer may have a multi-layer 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 toughness improving effect and the impact peeling adhesion improving effect of the obtained cured product, it is preferable not to contain the following rubber surface cross-linking layer as the intermediate layer.

The rubber surface cross-linking layer is obtained by polymerizing a rubber surface cross-linking 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 another vinyl monomer. It has the effect of lowering the viscosity of the curable epoxy resin composition of the present invention and the effect of improving the dispersibility of the core-shell polymer (B) component in the epoxy resin (A) component. Further, the rubber surface cross-linking layer also has an effect of increasing the cross-linking density of the core layer and the grafting efficiency of the shell layer.
Specific examples of the polyfunctional monomer include the same monomers as the above-mentioned polyfunctional monomers, but allyl methacrylate and triallyl isocyanurate are preferable.

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

  The shell layer of the core-shell polymer (B) of the present invention is selected from the group consisting of a vinyl cyan monomer and an alkoxyalkyl (meth) acrylate monomer, with the total amount of the monomers constituting the shell layer being 100% by mass, from the viewpoint of increasing thixotropy. 10 to 95% by mass of the monomer, 0 to 50% by mass of the monomer having an epoxy group, and 0 to 90% by mass (preferably 5 to 90% by mass) of the monomer copolymerizable therewith.

  More preferably, the shell layer of the core-shell polymer (B) of the present invention has 100% by mass of the total amount of monomers constituting the shell layer from the viewpoint that the dynamic splitting resistance is high while maintaining storage stability. From 15 to 60% by mass of a monomer selected from the group consisting of a vinyl cyan monomer and an alkoxyalkyl (meth) acrylate monomer, 1 to 35% by mass of a monomer having an epoxy group, and 40 to 85% by mass of a monomer copolymerizable therewith. Become.

  More preferably, the shell layer of the core-shell polymer (B) of the present invention has high T-peel adhesion strength and high dynamic splitting resistance while maintaining storage stability, and the total amount of monomers constituting the shell layer is Is 100% by mass, the vinyl cyan monomer is 20 to 40% by mass, the monomer having an epoxy group is 3 to 15% by mass, and the monomer copolymerizable with them is 60 to 80% by mass. Particularly, when the amount of the epoxy group-containing monomer in the shell layer is within the above range, the T-peel adhesion strength and the dynamic splitting resistance can be significantly improved as compared with the case of using 20% by mass or more.

  More preferably, in the shell layer of the core-shell polymer (B), the total amount of monomers constituting the shell layer is 100% by mass, 50 to 95% by mass of an alkoxyalkyl (meth) acrylate monomer, and 5 to 50% by mass of a monomer having an epoxy group. %.

  Even more preferably, in the shell layer of the core-shell polymer (B), the total amount of the monomers constituting the shell layer is 100% by mass, 90 to 95% by mass of an alkoxyalkyl (meth) acrylate monomer, and 5 to 10 monomers having an epoxy group. It consists of mass%.

  Examples of the monomer selected from the group consisting of vinyl cyan monomer and alkoxyalkyl (meth) acrylate monomer include (meth) acrylonitrile, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, and 2- (2- Ethoxy) is exemplified. Acrylonitrile is particularly preferable from the viewpoint of thixotropy, shear adhesive strength, T-shaped peel adhesive strength or dynamic splitting resistance. From the viewpoint of thixotropy, 2-methoxyethyl (meth) acrylate is particularly preferable.

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

  Examples of monomers copolymerizable with them include styrene, α-methylstyrene, 1- or 2-vinylnaphthalene, monochlorostyrene, dichlorostyrene, bromostyrene, etc .; aromatic vinyl monomers, methyl (meth) acrylate, ethyl (meth) Examples are alkyl (meth) acrylates such as acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and behenyl (meth) acrylate. .. From the viewpoint of thixotropy, shear adhesive strength, T-shaped peel adhesive strength, or dynamic splitting resistance, styrene or methyl methacrylate is more preferable, and styrene and methyl methacrylate are particularly preferable.

(Graft ratio of shell layer)
The graft ratio of the shell layer is preferably 70% or more (preferably 80% or more, more preferably 90% or more). If the graft ratio is less than 70%, the viscosity of the liquid resin composition may increase. The method of calculating the graft ratio is to first coagulate and dehydrate the aqueous latex containing the core-shell polymer, and finally dry it to obtain a powder of the core-shell polymer. Then, 2 g of the core-shell polymer powder is immersed in 100 g of methyl ethyl ketone (MEK) at 23 ° C. for 24 hours, and then the MEK-soluble matter is separated from the MEK-insoluble matter, and further the methanol-insoluble matter is separated from the MEK-soluble matter. Then, it is calculated by obtaining the ratio of the MEK insoluble matter to the total amount of the MEK insoluble matter and the methanol insoluble matter.

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

  When the polymer forming the core layer is composed of a polysiloxane polymer, the core layer can be formed by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, or the like. The method described in WO2006 / 070664 can be used.

  The intermediate layer can be formed by polymerizing the intermediate layer-forming monomer by known radical polymerization. When the rubber elastic body forming 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. When the core-shell polymer precursor obtained by coating the core layer or the core layer with the intermediate layer is obtained as an emulsion, the shell layer-forming monomer is preferably polymerized by an emulsion polymerization method, for example, WO2005. It can be manufactured according to the method described in Japanese Patent Publication No. 028546.

  Examples of emulsifiers (dispersing agents) that can be used in emulsion polymerization include alkyl or aryl sulfonic acids represented by dioctylsulfosuccinic acid and dodecylbenzenesulfonic acid, alkyl or aryl ether sulfonic acids, and alkyl or aryl represented by dodecyl sulfuric acid. Sulfuric acid, alkyl or aryl ether sulfuric acid, alkyl or aryl substituted phosphoric acid, alkyl or aryl ether substituted phosphoric acid, N-alkyl represented by dodecyl sarcosinic acid or aryl sarcosinic acid, alkyl represented by oleic acid or stearic acid, or the like. Various acids such as arylcarboxylic acids, alkyl or aryl ether carboxylic acids, anionic emulsifiers (dispersants) such as alkali metal salts or ammonium salts of these acids; alkyl or ants 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 kinds.

The amount of the emulsifier (dispersant) used is preferably small as long as it does not affect the dispersion stability of the aqueous latex of the core-shell polymer. Further, the emulsifier (dispersant) is more preferable as it has higher water solubility. When the water solubility is high, the emulsifier (dispersant) can be easily removed by washing with water, and an adverse effect on the finally obtained cured product can be easily prevented.
When the emulsion polymerization method is adopted, a known initiator, that is, 2,2′-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, ammonium persulfate or the like can be used as the thermal decomposition initiator. ..

  In addition, organic peroxides such as t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Oxides; peroxides such as hydrogen peroxide, inorganic peroxides such as potassium persulfate and ammonium persulfate, and reducing agents such as sodium formaldehyde sulfoxylate and glucose, if necessary, and iron sulfate (II It is also possible to use a redox type initiator in which a transition metal salt such as), a chelating agent such as disodium ethylenediaminetetraacetate and the like, and a phosphorus-containing compound such as sodium pyrophosphate and the like are used in combination, if necessary.

  When a redox type initiator is used, the polymerization can be carried out 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 type initiator. The amount of the initiator used, and when the redox type initiator is used, the amount of the reducing agent, the transition metal salt, the chelating agent and the like can be used within a known range. Further, when polymerizing a monomer having two or more double bonds, a known chain transfer agent can be used within a known range. A surfactant can be additionally used, which is also within the known range.

  Conditions such as polymerization temperature, pressure and deoxidation in the polymerization can be within the known range. The polymerization of the intermediate layer-forming monomer may be carried out in one step or in two or more steps. For example, in addition to the method of adding the intermediate layer-forming monomer at once to the emulsion of the rubber elastic body forming the elastic core layer, the method of continuously adding the intermediate layer-forming monomer, the elastic core layer is added to the reactor in which the intermediate layer-forming monomer is charged in advance. It is possible to employ a method in which polymerization is carried out after adding the emulsion of the rubber elastic body to the composition.

(Amount of core-shell polymer (B))
The amount of the core-shell polymer (B) is 1 to 50 parts by mass with respect to 100 parts by mass of the epoxy resin (A), in view of the balance between the handleability of the resulting curable resin composition and the effect of improving the toughness of the resulting cured product. Is preferable, 10 to 40 parts by mass is more preferable, and 10 to 35 parts by mass is particularly preferable.

<Blocked isocyanate (C)>
In the present invention, the blocked isocyanate (C) is added for the purpose of further improving the performance such as toughness, impact resistance, shear adhesion, and T-shaped peel adhesion. The blocked isocyanate (C) component contributes to the improvement of the above performance when used in combination with the core-shell polymer (B) component.

  The blocked isocyanate (C) of the present invention is an elastomer type, and contains urethane groups and / or urea groups, and all or part of the terminal isocyanate groups of the compound having an isocyanate group at the terminal is active hydrogen. It is a compound capped with various blocking agents having a group. In particular, a compound in which all the terminal isocyanate groups are capped with a blocking agent is preferable. Such a compound is, for example, an organic polymer having an active hydrogen-containing group at the terminal, which is reacted with an excess polyisocyanate compound to give a urethane group and / or a urea group in the main chain and an isocyanate group at the terminal. It can be 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, a R ^{2 s} are each independently a hydrocarbon group having 1 to 20 carbon atoms. A represents an average number of capped isocyanate groups per molecule, and 1.1 or more. Are preferred, 1.5-8 are more preferred, 1.7-6 are still more preferred, and 2-4 are especially preferred.X is a residue obtained by removing an active hydrogen atom from the blocking agent described below. A is a residue obtained by removing the terminal isocyanate group from the isocyanate-terminated prepolymer.).

  The hydrocarbon group may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and a dodecyl group; an ethenyl group and a propenyl group. , Butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group and the like; and the like. The aliphatic hydrocarbon group may be linear or branched. Examples of the alicyclic hydrocarbon group include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, and other cycloalkyl groups; cyclopropenyl group, cyclobutenyl group, cyclopentenyl group. Group, cyclohexenyl group, cycloheptenyl group, cyclooctenyl group, cyclopentadienyl and the like. Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenyl group and a terphenyl group.

  The number average molecular weight of the blocked isocyanate is preferably 2,000 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000 in terms of polystyrene equivalent molecular weight measured by GPC. The molecular weight distribution (ratio between the weight average molecular weight and the number average molecular weight) is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

(C-1 Organic Polymer Having Active Hydrogen-Containing Group at 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-based polymers.

(Active hydrogen group)
Examples of the active hydrogen-containing group forming 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 ease of handling (viscosity) of the blocked isocyanate obtained.

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

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

  The number average molecular weight of the organic polymer having an active hydrogen-containing group at the terminal is preferably 800 to 7,000, more preferably 1500 to 5000, and particularly preferably 2000 to 4000 in terms of polystyrene equivalent molecular weight measured by GPC.

(Polyether polymer)
The polyether-based polymer essentially has the general formula (2):
-R ¹ -O- (2)
(In the formula, R ¹ is a linear or branched alkylene group having 1 to 14 carbon atoms.) A polymer having a repeating unit represented by the formula (2), wherein R ¹ is a carbon atom. A linear or branched alkylene group of the number 1 to 14, preferably 2 to 4, is preferred. Specific examples of the repeating unit represented by the general formula _{(2), -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- and the like. The main chain skeleton of the polyether polymer may be composed of only one kind of repeating unit or may be composed of two or more kinds of repeating units. In particular, a polymer composed mainly of polypropylene glycol having a repeating unit of propylene oxide of 50% by mass or more is preferable from the viewpoint of T-shaped peel adhesion strength. Further, polytetramethylene glycol (PTMG) obtained by ring-opening polymerization of tetrahydrofuran is preferable from the viewpoint of dynamic cleavage resistance.
Further, when used in combination with the core-shell polymer (B) component, the ratio of the core-shell polymer (B) component and the blocked isocyanate (C) component is 0.1 from the viewpoint of thixotropy of the resulting curable epoxy resin composition. It is preferably from 10 to 10, more preferably from 0.2 to 5, and particularly preferably from 0.3 to 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.

(Polyacrylic polyol)
Examples of the polyacrylic polyol include polyols having a (meth) acrylic acid alkyl ester (co) polymer as a skeleton and having a hydroxyl group in the molecule. In particular, a polyacrylic polyol obtained by copolymerizing a hydroxyl group-containing (meth) acrylic acid alkyl ester monomer such as 2-hydroxyethyl methacrylate is preferable.

(Polyester polyol)
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, A polymer obtained by polycondensing a polyhydric alcohol such as diethylene glycol, dipropylene glycol or neopentyl glycol in the temperature range of 150 to 270 ° C. in the presence of an esterification catalyst can be mentioned. 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, and polychloroprene polyol, 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; fatty acids such as isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated diphenylmethane diisocyanate. Examples thereof include group-based polyisocyanates. Of 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 primary amine blocking agents, secondary amine blocking agents, oxime blocking agents, lactam blocking agents, active methylene blocking agents, alcohol blocking agents, mercaptan blocking agents, and amides. Examples include a system-based blocking agent, an imide-based blocking agent, a heterocyclic aromatic compound-based blocking agent, a hydroxy-functional (meth) acrylate-based blocking agent, and a phenol-based blocking agent. Among these, oxime-based blocking agents, lactam-based blocking agents, hydroxy-functional (meth) acrylate-based blocking agents, and phenol-based blocking agents are preferable, and hydroxy-functional (meth) acrylate-based blocking agents and phenol-based blocking agents are more preferable. Further, a phenol type blocking agent is more preferable.

  Examples of the primary amine blocking agent include butylamine, isopropylamine, dodecylamine, cyclohexylamine, aniline, benzylamine and the like. Examples of the secondary amine blocking agent include dibutylamine, diisopropylamine, dicyclohexylamine, diphenylamine, dibenzylamine, morpholine and piperidine. Examples of the oxime-based blocking agent include formaldoxime, acetaldoxime, acetoxime, methylethylketoxime, diacetylmonooxime, cyclohexaneoxime and the like. Examples of the lactam-based 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. As the alcohol-based blocking agent, methanol, ethanol, propanol, isopropanol, butanol, amyl alcohol, cyclohexanol, 1-methoxy-2-propanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol , Methyl glycolate, butyl glycolate, diacetone alcohol, methyl lactate, 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, imidazoles such as 2-ethylimidazole, pyrroles, 2-methylpyrrole, pyrroles such as 3-methylpyrrole, pyridine, 2-methylpyridine, and 4-methyl. Examples thereof include pyridines such as pyridine, and diazabicycloalkenes such as diazabicycloundecene and diazabicyclononene.

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

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 more than one phenolic hydroxyl group, but preferably contains only one phenolic hydroxyl group. The phenolic compound may contain other substituents, but these substituents preferably do not react with the isocyanate group under the conditions of the capping reaction, and an alkenyl group and an allyl group are preferable. 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 phenol-based blocking agent include phenol, cresol, xylenol, chlorophenol, ethylphenol, allylphenol (particularly 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 attached to the end of the polymer chain of the urethane prepolymer in such a way that the end to which it is attached no longer has a reactive group.
The blocking agents 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.

The blocked isocyanate used in the present invention is preferably a compound obtained by capping a urethane prepolymer containing a polyalkylene glycol structure with a blocking agent, and the urethane prepolymer containing a polypropylene glycol structure is blocked with a blocking agent (preferably a phenol-based block). More preferably, it is a compound capped with an agent) or a urethane prepolymer containing a polytetramethylene glycol structure is capped with a blocking agent (preferably a phenol-based blocking agent). The blocked isocyanate can be preferably used because it improves thixotropy and adhesiveness.
A compound obtained by capping a urethane prepolymer containing a polypropylene glycol structure with a blocking agent (preferably a phenol-based blocking agent) may be used from the viewpoint of improving T-shaped peel adhesion strength, and a urethane containing a polytetramethylene glycol structure. A compound obtained by capping the prepolymer with a blocking agent (preferably a phenol-based blocking agent) may be used from the viewpoint of improving dynamic cleavage resistance.

  The blocked NCO equivalent of the blocked isocyanate is, for example, 10 to 500, preferably 50 to 300. The epoxide equivalent weight of the blocked isocyanate is, for example, 300 to 900 g / eq, preferably 400 to 800 g / eq. Blocked isocyanates having at least one of these properties are suitable for use in the present invention.

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

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

  Specific examples of the cross-linking agent and chain extender, trimethylolpropane, glycerin, trimethylolethane, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, sucrose, sorbitol, pentaerythritol, ethylenediamine, triethanolamine, monoethanol. Examples include amine, diethanolamine, piperazine, aminoethylpiperazine. Further, 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 mass, more preferably 10 to 40 parts by mass, and particularly preferably 10 to 35 parts by mass with respect to 100 parts by mass of the epoxy resin (A). If it is less than 1 part by mass, the modifying effects such as toughness, impact resistance and adhesiveness may not be sufficient, and if it is more than 50 parts by mass, the elastic modulus of the obtained cured product may be low. The blocked isocyanate may be used alone or in combination of two or more kinds.

<Epoxy curing agent (D)>
An epoxy curing agent (D) can be used in the curable epoxy resin composition of the present invention, if necessary.
When the curable epoxy resin composition of the present invention is temporarily used as a one-component adhesive, the epoxy curing agent (D) is used 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 select the components. On the contrary, it is preferable to select the epoxy curing agent (D) component and the below-mentioned (E) component so that even if it cures at room temperature (about 22 ° C.) or at a temperature up to at least 50 ° C., it becomes very slow.

  Examples of the epoxy curing agent (D) component include boron trichloride / amine complex, boron trifluoride / amine complex, dicyandiamide, melamine, diallylmelamine, guanamine (eg, acetoguanamine and benzoguanamine), aminotriazole (eg, 3 -Amino-1,2,4-triazole), hydrazides (eg adipic acid dihydrazide, stearic acid dihydrazide, isophthalic acid dihydrazide, semicarbazide), cyanoacetamide, and aromatic polyamines (eg diaminodiphenyl sulfone). It is more preferable to use dicyandiamide, isophthalic acid dihydrazide, adipic acid dihydrazide, or 4,4'-diaminodiphenyl sulfone, and dicyandiamide is particularly preferable.

  Among the above curing agents, latent epoxy curing agents such as boron trichloride / amine complex, boron trifluoride / amine complex, dicyandiamide, hydrazide and the like are preferable because the curable epoxy resin composition of the present invention can be made into one liquid. The epoxy curing agent (D) component may be used alone or in combination of two or more kinds.

  The epoxy curing agent (D) component is used in an amount sufficient to cure the composition. Typically, sufficient curative is provided to consume at least 80% of the epoxide groups present in the composition. Large excesses over that required for consumption of epoxide groups are usually not required. As for the usage-amount of an epoxy hardening agent (D) component, 1-40 mass parts is preferable with respect to 100 mass parts of (A) component, 2-30 mass parts is more preferable, 3-25 mass parts is further more preferable, 5 -20 parts by mass is particularly preferable. If it is less than 1 part by mass, the curability of the curable epoxy resin composition of the present invention may be deteriorated. If the amount is more than 40 parts by mass, the curable epoxy resin composition of the present invention may have poor storage stability and may be difficult to handle.

<Curing accelerator (E)>
A curing accelerator (E) can be used in the curable epoxy resin composition of the present invention, if necessary.
The curing accelerator (E) component is a catalyst for promoting the reaction of the epoxy group with the epoxide-reactive group on the other components of the curing agent and the adhesive.
Examples of the curing accelerator (E) component include ureas such as p-chlorophenyl-N, N-dimethylurea (Monuron), 3-phenyl-1,1-dimethylurea (Phenuron), and 3,4-dichlorophenyl-N. , N-dimethylurea (Diuron), N- (3-chloro-4-methylphenyl) -N ′, N′-dimethylurea (Chlortoluron), tert-acryl- or alkyleneamines, for example benzyldimethylamine, 2, 4,6-Tris (dimethylaminomethyl) phenol, 2,4,6-Tris (dimethylaminomethyl) phenol incorporated in a poly (p-vinylphenol) matrix, piperidine or their derivatives, imidazole derivatives, generally C1- C12 alkyleneimidazole or N-aryl Imidazole, such as 2-ethyl-2-methylimidazole or N- butyl imidazole, 6-caprolactam, and the like. The catalyst may be encapsulated or it may be latent only active at elevated temperatures. The curing accelerator (E) component may be used alone or in combination of two or more kinds.

  As for the usage-amount of a hardening accelerator (E) component, 0.1-10 mass parts is preferable with respect to 100 mass parts of (A) component, 0.2-5 mass parts is more preferable, 0.5-3 mass parts. Parts are more preferable, and 0.8 to 2 parts by mass is particularly preferable. If the amount is less than 0.1 part by mass, the curability of the curable epoxy resin composition of the present invention may deteriorate. If it is more than 10 parts by mass, the curable epoxy resin composition of the present invention may have poor storage stability and may be difficult to handle.

<Filler>
A filler may be used in the curable epoxy resin composition of the present invention, if necessary. Specific examples of the filler include dry silica such as hydrophobic fumed silica surface-treated with polydimethylsiloxane, wet silica, reinforcing filler such as aluminum silicate, magnesium silicate, calcium silicate, dolomite and carbon black. Plate-like fillers such as talc and wollastonite; colloidal calcium carbonate, ground calcium carbonate, magnesium carbonate, titanium oxide, ferric oxide, aluminum fine powder, zinc oxide, activated zinc oxide, and the like. Also, microballoons having an average particle size of up to 200 μm and a density of up to 0.2 g / cc can 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, Expancel manufactured by Akzo Nobel, and Microsphere manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.

<Reactive diluent>
Further, in the curable epoxy resin composition of the present invention, if necessary, a monoepoxide such as an aliphatic glycidyl ether such as butyl glycidyl ether, or phenyl glycidyl ether, cresyl glycidyl ether, or 2 as a reactive diluent. -Ethylhexyl glycidyl ether, C8-C10 alkyl glycidyl ether, C12-C14 alkyl glycidyl ether, p-tert butylphenyl glycidyl ether, and neodecanoic acid monoglycidyl ether may be contained.

(Other ingredients)
In the present invention, other compounding ingredients may be used as required. Other compounding ingredients include dehydrating agents such as calcium oxide, coloring agents such as pigments and dyes, extender pigments, ultraviolet absorbers, antioxidants, stabilizers (antigelling agents), plasticizers, leveling agents, and deodorants. Examples thereof include a foaming agent, a silane coupling agent, an antistatic agent, a flame retardant, a lubricant, a viscosity reducing agent, a low shrinking agent, an organic filler, a thermoplastic resin, a drying agent and a dispersant.

  The thixotropy of the curable epoxy resin composition of the present invention is preferably 1.00 or more, more preferably 1.1 or more, even more preferably 1.2 or more, and 1.25 or more. Is even more preferable. The upper limit of thixotropy is, for example, about 1.5. The thixotropy can be evaluated by a thixotropy index, a hysteresis loop, or the like. For example, the thixotropy index (TI) can be expressed as a ratio of viscosities ηa and ηb at rotation speeds a and b (TI = ηb / ηa).

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

(Use)
The curable epoxy resin composition of the present invention has excellent thixotropy and can be used as a one-component adhesive.
The curable epoxy resin composition of the present invention is an adhesive such as a structural adhesive for vehicles and aircraft, a coating material, a material for laminating with glass fiber, a material for laminating with carbon fiber, a printed wiring board, an electrical insulating material. It is preferably used for such purposes. In particular, it is useful as a structural adhesive for vehicles.

  The present application claims the benefit of priority based on Japanese Patent Application No. 2015-074446 filed on Mar. 31, 2015. The entire content of the specification of Japanese Patent Application No. 2015-074446 filed on Mar. 31, 2015 is incorporated herein by reference.

  Hereinafter, the present invention will be described in more detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited thereto and is appropriately modified and implemented within a range compatible with the gist of the preceding and following description. Are possible, and all of them are included in the technical scope of the present invention.

<Evaluation method>
With respect to the polybutadiene rubber particles in the polybutadiene rubber latex described in the production example and the core-shell polymer particles in the core-shell polymer latex, the measuring methods of the respective average particle diameters will be described below.

(Measurement of volume average particle size of butadiene rubber particles and core-shell polymer particles in latex)
The volume average particle diameters of the polybutadiene rubber particles in the polybutadiene rubber latex and the core-shell polymer particles in the core-shell polymer latex were measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.).

  A sample diluted with deionized water was used as a measurement sample. For the measurement, the refractive index of water or methyl ethyl ketone and the refractive index of each core-shell polymer (B) are input, the measurement time is 600 seconds, and the sample concentration is set so that the Signal Level is within the range of 0.6 to 0.8. Was adjusted.

(Thixotropic property)
Using a E-type viscometer, the viscosity of the curable epoxy resin composition measured under the condition that the shear rate was 1 (s ^-1 ) was ηa, and the shear rate was 2 (s ^-1 ). The viscosity of the curable epoxy resin composition was set to ηb, and ηb was set to 1, and the evaluation was made by the magnification of ηa. The higher the magnification of ηa where ηb is 1, the better the thixotropic property.
The E-type viscometer was measured by using a digital viscometer DV-II + Pro type manufactured by Brookfield. It measured at 23 degreeC using the spindle CPE-52.

(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 ) was η0, and the viscosity after storage at 40 ° C. for 7 days was η1. , Η0 was set to 1, and the evaluation was made by the magnification of η1. The lower the magnification of η1 where η0 is 1, the better the storage stability. The E-type viscometer was measured by using a digital viscometer DV-II + Pro type manufactured by Brookfield. It measured at 23 degreeC using the spindle CPE-52.

(Shear bond strength)
The shear bond strength was evaluated according to JIS K 6850. The curable epoxy resin composition is applied to two SPCC steel plates each having a width of 25 mm, a length of 100 mm, and a thickness of 1.6 mm, and the adhesive layer is adhered so as to have a width of 25 mm, a length of 12.5 mm, and a thickness of 0.13 mm. In addition, a test piece was prepared by curing the material at 170 ° C. for 1 hour.
The shear bond strength was measured in MPa as a unit 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)
The T-shaped peel adhesion strength was evaluated according to JIS K 6854. A curable epoxy resin composition is applied to two SPCC steel plates each having a width of 25 mm, a length of 200 mm, and a thickness of 0.5 mm, and the adhesive layers are bonded so that the adhesive layer has a width of 25 mm, a length of 150 mm, and a thickness of 0.26 mm. It was cured for 1 hour under the condition of 170 ° C. to prepare a test body. Under a measurement condition of a measurement temperature of 23 ° C. and a test speed of 254 mm / min, the T-shaped peel adhesive strength was measured with the unit of N / 25 mm.

(Dynamic cleavage resistance)
The dynamic splitting resistance was evaluated according to ISO 11343. A curable epoxy resin composition is applied to two SPCC steel plates each having a width of 20 mm, a length of 90 mm, and a thickness of 0.8 mm, and the adhesive layers are bonded so that the width is 20 mm, the length is 30 mm, and the thickness is 0.26 mm. A test body was prepared by curing under 170 ° C. for 1 hour.
The dynamic splitting resistance was measured with the unit of kN / m under the measurement conditions of the measurement temperature of 23 ° C., the impact energy of 50 J, and the 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, a method for preparing polybutadiene rubber latices (R-1) and (R-2) containing a polybutadiene rubber as a core layer of a core-shell polymer was described. The method for preparing core-shell polymer latexes (L-1) to (L-10) was described in Production Example 2-1 to Production Example 2-10. The method for preparing the epoxy resin (N) in which the core-shell polymer is dispersed is described in Production Example 3-1 to Production Example 3-10.

Production Example 1-1: Preparation of polybutadiene rubber latex (R-1) 200 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, disodium ethylenediaminetetraacetate (EDTA) 0.002 in a pressure resistant polymerization machine. Parts by mass, 0.001 parts by mass of ferrous sulfate heptahydrate and 1.55 parts by mass of sodium dodecylbenzenesulfonate (SDBS) were added, and nitrogen substitution was carried out while stirring to remove oxygen. After that, 100 parts by mass 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 mass of paramenthane hydroperoxide (PHP) and then 0.10 parts by mass of sodium formaldehyde sulfoxylate (SFS). 0.025 parts by mass of paramenthane hydroperoxide (PHP) was added at each of 3, 5 and 7 hours after the initiation of the polymerization. In addition, 0.0006 parts by mass of EDTA and 0.003 parts by mass of ferrous sulfate heptahydrate were added at 4, 6 and 8 hours after the initiation of polymerization. After 15 hours of polymerization, residual monomers were removed by evaporation 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 mass of the polybutadiene rubber latex (R-1) obtained in Production Example 1-1 (7 parts by mass of polybutadiene rubber are included in a pressure-resistant polymerization machine. ), 185 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, 0.002 parts by mass of EDTA, and 0.001 part by mass of ferrous sulfate heptahydrate, and sufficiently nitrogen with stirring. After substitution was performed to remove oxygen, 93 parts by mass of Bd was charged into the system and the temperature was raised to 45 ° C. Polymerization was initiated by adding 0.02 part by mass of PHP and then 0.10 part by mass of SFS. Every 3 hours until the 24th hour from the start of polymerization, 0.025 part by mass of PHP, 0.0006 part by mass of EDTA, and 0.003 part by mass of ferrous sulfate heptahydrate were added. After 30 hours of polymerization, residual monomers were removed by evaporation 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 the core-shell polymers (L-1) to (L-10) are described as Production Example 2-1 to Production Example 2-10.

Production Example 2-1: Preparation of Core-Shell Polymer Latex (L-1) A polybutadiene rubber prepared in Production Example 1 was placed in a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. 250 parts by mass of polybutadiene rubber latex (R-1) containing 83 parts by mass of particles and 65 parts by mass of deionized water were charged and stirred at 60 ° C. while performing nitrogen substitution. After adding 0.004 parts by mass of EDTA, 0.001 parts by mass of ferrous sulfate heptahydrate, and 0.2 parts by mass of SFS, 17 parts by mass of a graft monomer forming a shell layer (3.9 parts by mass of acrylonitrile, A mixture of 5.4 parts by mass of styrene, 7.7 parts by mass of methyl methacrylate) and 0.04 parts by mass of cumene hydroperoxide was continuously added over 2 hours for graft polymerization. After the addition was completed, the reaction was further completed by stirring for 2 hours to obtain a core-shell polymer latex (L-1). The volume average particle diameter of the core-shell polymer contained in the obtained latex was 0.10 μm.

Production Example 2-2 to Production Example 2-10
A core-shell polymer latex was prepared in the same manner by using the polybutadiene rubber latex and the graft monomer in Production Example 2-1 as the levels shown in Table 1. Table 1 shows the volume average particle diameters of the core-shell polymers (L-1) to (L-10).

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) in which Core Shell Polymer is Dispersed 132 g of methyl ethyl ketone in a 1 L mixing tank at 25 ° C. While introducing and stirring, 132 g of the aqueous latex (L-1) containing 40 g of the core-shell polymer obtained in Production Example 2-1 was added. After uniformly mixing, 200 g of water was added at a supply rate of 80 g / min. When the stirring was stopped immediately after supplying water, a slurry liquid consisting of an aqueous phase containing a part of the floating aggregates and the organic solvent was obtained. Next, while leaving an agglomerate containing a part of the aqueous phase, 360 g of the aqueous phase was discharged from the outlet at the bottom of the tank. 90 g of methyl ethyl ketone was added to the obtained aggregate and uniformly mixed to obtain a solution in which the core-shell polymer was dispersed. Epoxy resin in which the core-shell polymer is dispersed by mixing 80 g of the epoxy resin (A-1: Mitsubishi Chemical Corporation, JER828EL), which is the component (A), and removing the volatile components with a rotary evaporator. (N-1) was obtained.

Production Example 3-2 to Production Example 3-10
Substituting the core-shell polymer aqueous latex (L-1) of Production Example 3-1 with the core-shell polymer aqueous latex (L-2) to (L-10) of Production Example 3-2 to Production Example 3-10, Epoxy resins (N-2) to (N-10) in which the core-shell polymer was dispersed were obtained in the same manner as in Production Example 3-1.

Examples 1 to 16 and Comparative Example 1
In Tables 2 and 3, (A) epoxy resin, (N) core-shell polymer-dispersed epoxy resin, (C) blocked isocyanate, (D) epoxy curing agent, (E) curing accelerator, and other compounding ingredients The compounding composition of the curable epoxy resin composition containing the above and the evaluation results of the cured product of the curable epoxy resin composition are shown.

Further, in Tables 2 and 3, based on 100 parts by mass of (A) epoxy resin, (B) core-shell polymer, (C) blocked isocyanate, (D) epoxy curing agent, (E) curing accelerator, and other compounds. The mass parts of the raw materials are also shown.
In Table 2, as the (C) blocked isocyanate, (C-1) adecaresin QR-9466, which is a blocked isocyanate having a polypropylene glycol structure, was used.

  In Table 3, as the (C) blocked isocyanate, (C-2) Flexibilizer DY965, which is a blocked isocyanate having a polytetramethylene glycol structure, was used.

<Compounding agent>
The blended raw materials used in Tables 2 and 3 are shown below.
(A) Epoxy resin (A-1) JER828EL (manufactured by Mitsubishi Chemical, bisphenol A type epoxy resin)
(N) Epoxy resin compositions (N-1) to (N-10) in which the core-shell polymer is dispersed; described in Production Examples 3-1 to 3-10.
(B) Core-shell polymer (B-1) to (B-10); Core-shell polymer contained in core-shell polymer latex (L-1) to (L-10) described in Production Example 2-1 to Production Example 2-10. Is. See Table 1 for composition.
(C) Blocked isocyanate (C-1) ADEKA RESIN QR-9466 (made by ADEKA, blocked isocyanate containing polypropylene glycol structure, block NCO equivalent 220, viscosity 30000 mPa · s / 25 ° C.)
(C-2) Flexibleizer DY 965 (manufactured by Huntsman, blocked isocyanate containing a polytetramethylene glycol structure, Epoxide Eq. Weight 558-667 [EEW, g / eq], viscosity 4400-12800 cP / 25 ° C.)
(D) Epoxy curing agent (D-1) Dyhard 100S (manufactured by AlzChem, dicyandiamide)
(E) Curing accelerator (E-1) Dyhard UR300 (manufactured by AlzChem, 1,1-dimethyl-3-phenylurea)
Other blended raw materials (heavy calcium carbonate) Whiten SB Red (made of Shiraishi calcium, untreated heavy calcium carbonate, average particle diameter: 1.8 μm)
(Calcium oxide) CML # 31 (manufactured by Omi Chemical Industry)
(Carbon black) MONARCH 280 (made by Cabot)
(Reactive diluent) Cardula E10P (manufactured by Momentive, glycidyl ester of versatic acid)

1 and 4 show the relationship between the glycidyl methacrylate (GMA) of the shell layer of the core-shell polymer and the storage stability and thixotropy. When the shell layer contains a small amount of glycidyl methacrylate, the storage stability and thixotropy are good. (A blocked isocyanate having a polypropylene glycol structure was used in FIG. 1 (the GMA ratio% in the figure corresponds to that used in Examples 1, 5, 6, 7, and 8). In 4, a blocked isocyanate having a polytetramethylene glycol structure was used (% GMA ratio in the figure corresponds to that used in Examples 10, 12, 13, 14, and 15).
2 and 5 show glycidyl methacrylate (GMA), T-peel adhesion strength (indicated by T-Peel in the figure) and shear adhesion strength (indicated by Lap Shear in the figure) of the shell layer of the core-shell polymer. When the shell layer contains a predetermined amount of glycidyl methacrylate (more than 0% by mass and less than 20% by mass), these properties can be improved (in FIG. 2, a blocked isocyanate containing a polypropylene glycol structure is used). (The GMA ratio% in the figure corresponds to that used in Examples 1, 5, 6, 7, and 8.) In FIG. 5, a blocked isocyanate containing a polytetramethylene glycol structure was used (FIG. The GMA ratio% in the inside corresponds to that used in Examples 10, 12, 13, 14, and 15)).
3 and 6 show the relationship between the glycidyl methacrylate (GMA) of the shell layer of the core-shell polymer and the dynamic splitting resistance (indicated by Impact Peel in the figure). % To less than 20% by mass, the dynamic splitting resistance can be improved (in FIG. 3, a blocked isocyanate containing a polypropylene glycol structure was used (the GMA ratio% in the figure is the value of Example 1, (Corresponding to those used in 5, 6, 7, and 8.) In FIG. 6, a blocked isocyanate containing a polytetramethylene glycol structure was used (% of GMA in the figure is in Examples 10, 12, and 13). , 14 and 15))).

A compound obtained by capping a urethane prepolymer containing a polypropylene glycol structure with a blocking agent (preferably a phenol type blocking agent) is a compound obtained by capping a urethane prepolymer containing a polytetramethylene glycol structure with a blocking agent (preferably a phenol type blocking agent). T-peel adhesion strength can be improved (Examples 1 to 16, FIGS. 2 and 4).
A compound obtained by capping a urethane prepolymer containing a polytetramethylene glycol structure with a blocking agent (preferably a phenol type blocking agent) is a compound obtained by capping a urethane prepolymer containing a polypropylene glycol structure with a blocking agent (preferably a phenol type blocking agent). Storage stability and dynamic splitting resistance can be improved (see Examples 1 to 16, FIGS. 1, 3, 4, and 6).

Claims (15)

With respect to 100 parts by mass of the epoxy resin (A),
A curable epoxy resin composition containing 1 to 50 parts by mass of a core-shell polymer (B) and 1 to 50 parts by mass of a blocked isocyanate (C),
The core layer of the core-shell polymer (B) is made of any of diene rubber, acrylic rubber, and polysiloxane rubber,
Shell layer of the core shell polymer (B) is a total amount of monomers constituting the shell layer is 100 mass%, A Turkey alkoxyalkyl (meth) acrylate monomer-1 0 to 95 wt%, 0-50 wt of a monomer having an epoxy group %, And 0 to 90% by weight of a monomer copolymerizable therewith, a curable epoxy resin composition.   The curable epoxy resin composition according to claim 1, wherein the copolymerizable monomer is 5 to 90% by mass.   The shell layer of the core-shell polymer (B) comprises 50 to 95% by mass of an alkoxyalkyl (meth) acrylate monomer and 5 to 50% by mass of an epoxy group-containing monomer, with the total amount of monomers constituting the shell layer being 100% by mass. Item 2. The curable epoxy resin composition according to Item 1. The shell layer of the core-shell polymer (B) comprises 90 to 95% by mass of an alkoxyalkyl (meth) acrylate monomer and 5 to 10% by mass of an epoxy group-containing monomer, with the total amount of monomers constituting the shell layer being 100% by mass. Item 4. The curable epoxy resin composition according to Item 1 or 3 . The curable epoxy resin composition according to any one of claims 1 to 4 , wherein the monomer having an epoxy group is glycidyl methacrylate. The curable epoxy resin composition according to claim 1 , wherein the alkoxyalkyl (meth) acrylate monomer is 2-methoxyethyl acrylate. The curable epoxy resin composition according to any one of claims 1 to 6 , wherein the core layer of the core-shell polymer (B) is made of butadiene rubber and / or butadiene-styrene rubber. The curable epoxy resin composition according to any one of claims 1 to 7 , wherein the core-shell polymer (B) has a volume average particle diameter of 0.05 to 0.30 µm. The curable epoxy resin composition according to any one of claims 1 to 8 , wherein the blocked isocyanate (C) is a compound obtained by capping a urethane prepolymer having a polypropylene glycol structure with a blocking agent. The curable epoxy resin composition according to claim 1 , wherein the blocked isocyanate (C) is a compound obtained by capping a urethane prepolymer having a polytetramethylene glycol structure with a blocking agent. The curable epoxy resin composition according to claim 1, further comprising 1 to 40 parts by mass of an epoxy curing agent (D). The curable epoxy resin composition according to any one of claims 1 to 11 , which further contains 0.1 to 10 parts by mass of a curing accelerator (E). Cured product formed by curing a curable epoxy resin composition according to any one of claims 1 to 12. Structural adhesives comprising using a curable epoxy resin composition according to any one of claims 1 to 12. The vehicle structural adhesives comprising using a curable epoxy resin composition according to any one of claims 1 to 12.

Images