JP2010077305A - Epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition which includes excellent adhesive property and flexibility at low temperatures (about -20°C) to normal temperature as well as elevated temperatures (about 80°C) and is suitable for use as a structural adhesive. <P>SOLUTION: The epoxy resin composition includes 100 pts.mass of epoxy resin (A), 5-100 pts.mass of core-shell particles (B), and a curing agent (C), in which the core-shell particles (B) include acrylonitrile in the monomer used during the production of the shell layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an epoxy resin composition.

  Structural adhesives may require adhesive strength and flexibility at high temperatures as well as low temperatures.

  For example, in order to ensure vehicle body rigidity and strength in parts such as automobile roof rails and various pillars, a method that combines spot welding and an adhesive (weld bond method) has been adopted. It is desirable that the adhesive used has a high adhesive strength to the steel plate at a high temperature of about 80 ° C. This is because parts such as roof rails and various pillars may become hot when the automobile is running. Moreover, if the adhesive strength is high, the number of spots in spot welding can be reduced.

  In addition, for example, a part called an opening (lid) such as an automobile hood, door, or trunk lid is basically composed of an outer plate (outer panel) and an inner plate (inner panel), and its end portion. Has adopted a caulking structure called “hemming” over almost the entire circumference, but it is desirable that the adhesive used for bonding the hemming portion has adhesive strength and flexibility at high temperatures. This is because the hemming part may become as high as about 80 ° C. when the automobile is running. In addition, when a load is applied to the bonding portion of the hemming portion, the stress is not dispersed and is easily concentrated at one point.

As what is related to such an adhesive, the thing of patent document 1 is mentioned, for example.
In Patent Document 1, (A) a specific epoxy resin, (B) a core / shell type powdery polymer having a core / shell two-layer structure, and (C) a thermally activated curing agent are essential components. An epoxy resin-based adhesive composition having pseudo-curing characteristics is described. It is described that such a composition has characteristics such as excellent resistance to impact, adhesion properties such as tensile shear strength and T-peel strength, and good pseudo-curability.

JP-A-5-214310

  However, the inventor of the present application has found that an adhesive containing a conventional core-shell type powder having a two-layer structure has a high strength at a low temperature to a normal temperature, but the strength at a high temperature of about 80 ° C. decreases.

  The present invention provides an epoxy resin composition that is excellent in adhesive performance and flexibility not only from low temperature (about −20 ° C.) to normal temperature but also at high temperature (about 80 ° C.) and can be preferably used as a structural adhesive. That is.

As a result of intensive studies to solve the above problems, the inventors of the present application contain 100 parts by mass of an epoxy resin (A), 5 to 100 parts by mass of core-shell type particles (B), and a curing agent (C). The epoxy resin composition containing acrylonitrile as a monomer used in producing the shell layer in the core-shell type particle (B) is not only at a low temperature (about −20 ° C.) but at a high temperature (about 80 ° C.). Has also been found to be excellent in adhesive performance and flexibility and can be preferably used as a structural adhesive, and the present invention has been completed.
That is, this invention is 1-7 shown below.
1. Containing 100 parts by mass of epoxy resin (A), 5 to 100 parts by mass of core-shell type particles (B), and curing agent (C),
The epoxy resin composition in which the monomer used when manufacturing a shell layer in the said core-shell type particle | grains (B) contains acrylonitrile.
2. 2. The epoxy resin composition according to 1 above, wherein the shell layer has a glass transition temperature of 50 ° C. or higher, and an inner layer adjacent to the shell layer has a glass transition temperature of −30 ° C. or lower.
3. 3. The epoxy resin composition according to 1 or 2 above, wherein the core-shell type particles (B) are two layers and / or three layers.
4). 4. The epoxy resin composition according to any one of 1 to 3 above, wherein the average primary particle diameter of the core-shell type particles (B) is 50 nm to 500 nm.
5). The epoxy according to any one of 1 to 4 above, wherein the epoxy resin (A) contains at least one selected from the group consisting of a bisphenol A type epoxy resin having an epoxy equivalent of 220 or more, a urethane-modified epoxy resin, and a rubber-modified epoxy resin. Resin composition.
6). In the epoxy resin (A), the amount of the bisphenol A type epoxy resin having an epoxy equivalent of 220 or more is 0 to 100% by mass, the amount of the urethane-modified epoxy resin is 0 to 100% by mass, and the rubber-modified epoxy. 6. The epoxy resin composition according to 5 above, wherein the amount of the resin is 0 to 100% by mass.
7). The epoxy resin composition according to any one of 1 to 6 above, which is used as a structural adhesive.

  According to the present invention, there is provided an epoxy resin composition which is excellent in adhesive performance and flexibility not only from a low temperature (about −20 ° C.) to a normal temperature but also at a high temperature (about 80 ° C.) and can be preferably used as a structural adhesive. Can be provided.

The present invention will be described in detail.
This invention contains 100 mass parts of epoxy resins (A), 5-100 mass parts of core-shell type particles (B), and a curing agent (C), and produces a shell layer in the core-shell type particles (B). The monomer used in this case is an epoxy resin composition containing acrylonitrile.
The epoxy resin composition of the present invention is hereinafter also referred to as “the composition of the present invention”.

The epoxy resin (A) will be described.
The epoxy resin (A) contained in the composition of the present invention is not particularly limited as long as it is a compound having two or more epoxy groups. For example, epoxy compounds having a bisphenyl group such as bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, biphenyl type, polyalkylene glycol type, alkylene glycol Type epoxy compound, epoxy compound having naphthalene ring, bifunctional glycidyl ether type epoxy resin such as epoxy compound having fluorene group; phenol novolak type, orthocresol novolak type, trishydroxyphenylmethane type, tetraphenylolethane type Polyfunctional glycidyl ether type epoxy resin such as diglyceryl ester type epoxy resin of synthetic fatty acid such as dimer acid; N, N, N ′, N′-tetraglycidyl diaminodipheny Aromatic epoxy resin having glycidylamino group such as methane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N, N-diglycidylaniline; epoxy compound having tricyclodecane ring (For example, an epoxy compound obtained by a production method of reacting epichlorohydrin after polymerizing cresols or phenols such as dicyclopentadiene and m-cresol) and the like.

Examples of the epoxy resin (A) include an epoxy resin having a sulfur atom in the epoxy resin main chain such as Flep 10 manufactured by Toray Fine Chemical Co., Ltd .; rubber-modified epoxy resin; urethane-modified epoxy resin.
An epoxy resin (A) can be used individually or in combination of 2 types or more, respectively.

  The epoxy resin (A) is preferably a bisphenol A-type epoxy resin, a rubber-modified epoxy resin, or a urethane-modified epoxy resin from the viewpoint of superior adhesion performance and flexibility from low to high temperatures, and bisphenol A having an epoxy equivalent of 220 or more. More preferably, it contains at least one selected from the group consisting of type epoxy resins, rubber-modified epoxy resins and urethane-modified epoxy resins.

A bisphenol A type epoxy resin having an epoxy equivalent of 220 or more preferably has an epoxy equivalent of 220 to 300 g / eq from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature.
The amount of the bisphenol A type epoxy resin having an epoxy equivalent of 220 or more is preferably 0 to 100% by mass in the epoxy resin (A) from the viewpoint of being excellent in adhesive performance and flexibility from low temperature to high temperature. More preferably, it is mass%.

The rubber-modified epoxy resin is not particularly limited as long as it is an epoxy resin having two or more epoxy groups and a skeleton of rubber. Examples of the rubber forming the skeleton include polybutadiene, acrylonitrile butadiene rubber (NBR), and carboxyl group-terminated NBR (CTBN).
The rubber-modified epoxy resin preferably has an epoxy equivalent of 200 to 350 g / eq from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature.
The rubber-modified epoxy resins can be used alone or in combination of two or more.
The amount of the rubber-modified epoxy resin is preferably 0 to 100% by mass, and preferably 0 to 60% by mass in the epoxy resin (A) from the viewpoint that it is superior in adhesion performance and flexibility from low temperature to high temperature. More preferred.

The rubber-modified epoxy resin is not particularly limited for its production. For example, it can be produced by reacting rubber and epoxy in a large amount of epoxy. The epoxy (for example, epoxy resin) used when producing the rubber-modified epoxy resin is not particularly limited. For example, a conventionally well-known thing is mentioned.
In the present invention, the epoxy equivalent of the rubber-modified epoxy resin and the amount of addition thereof indicate the amount as the “rubber-modified epoxy resin containing the epoxy” because of the excess epoxy resin used in the production.

  The structure of the urethane-modified epoxy resin is not particularly limited as long as it is a resin having a urethane bond and two or more epoxy groups in the molecule. From the point that a urethane bond and an epoxy group can be efficiently introduced into one molecule, a urethane bond-containing compound (X) having an isocyanate group obtained by reacting a polyhydroxy compound and a polyisocyanate compound, and hydroxy A resin obtained by reacting the group-containing epoxy compound (Y) is preferable.

Examples of the polyhydroxy compound used in producing the urethane-modified epoxy resin include polyether polyols such as polypropylene glycol, polyester polyols, adducts of hydroxycarboxylic acid and alkylene oxide, polybutadiene polyols, and polyolefin polyols. It is done.
Of these, when a polyether polyol is used, a cured product having excellent adhesion and flexibility is obtained, which is preferable.

  The molecular weight of the polyhydroxy compound is preferably in the range of 300 to 5000, particularly 500 to 2000 as the mass average molecular weight from the viewpoint of excellent balance between flexibility and curability.

  The polyisocyanate compound used when producing the urethane-modified epoxy resin is not particularly limited as long as it is a compound having two or more isocyanate groups. Examples thereof include aliphatic polymer isocyanates, aromatic polyisocyanates, and polyisocyanate groups having aromatic hydrocarbon groups. Of these, aromatic polyisocyanates are preferred. Examples of the aromatic polyisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate.

  By the above reaction, a urethane prepolymer containing a free isocyanate group at the terminal is obtained. This is reacted with an epoxy resin having at least one hydroxyl group in one molecule (for example, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of aliphatic polyhydric alcohol and glycidol). A modified epoxy resin is obtained.

The urethane-modified epoxy resin preferably has an epoxy equivalent of 200 to 250 g / eq from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature.
The urethane-modified epoxy resins can be used alone or in combination of two or more.

The amount of the urethane-modified epoxy resin is preferably 0 to 100% by mass and preferably 0 to 50% by mass in the epoxy resin (A) from the viewpoint of excellent adhesion performance and flexibility from low temperature to high temperature. More preferred.
When the amount of the urethane-modified epoxy resin in the epoxy resin (A) is 5% by mass or more, adhesion to the steel sheet is more sufficient, and when it is 50% by mass or less, the adhesive strength can be increased. The role of the urethane-modified epoxy resin is to impart flexibility to the steel plate interface by localizing a highly polar urethane-modified epoxy at the steel plate interface.

The urethane-modified epoxy resin is not particularly limited for its production. For example, it can be produced by reacting urethane and epoxy in a large amount of epoxy (for example, epoxy resin). The epoxy used when producing the urethane-modified epoxy resin is not particularly limited. For example, a conventionally well-known thing is mentioned.
In the present invention, the epoxy equivalent of the urethane-modified epoxy resin and the amount of addition thereof indicate the amount as a urethane-modified epoxy resin containing an excess epoxy resin used in the production.

The core-shell type particle (B) will be described.
The core-shell type particle (B) contained in the composition of the present invention has at least a core layer and a shell layer, and the monomer used in producing the shell layer in the core-shell type particle (B) contains acrylonitrile. It is a waste.
The core-shell type particles (B) have a glass transition temperature of 50 ° C. or higher in the shell layer and a glass transition temperature of the inner layer adjacent to the shell layer of −30 from the viewpoint of excellent adhesion performance and flexibility from low temperature to high temperature. It is preferable that it is below ℃.
Moreover, it is preferable that the core-shell type particles (B) have two layers and / or three layers from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature.

  When the core-shell type particle (B) has a two-layer structure, the inner layer adjacent to the shell layer is a core layer, and the glass transition temperature of the core layer is −30 ° C. or lower.

When the core-shell type particle (B) has a three-layer structure, the core-shell type particle (B) has an intermediate layer as an inner layer adjacent to the shell layer, and the glass transition temperature of the intermediate layer is −30 ° C. or lower. The core-shell type particle (B) having a three-layer structure has a core layer having a glass transition temperature of 50 ° C. or higher at the center, and an intermediate layer having a glass transition temperature of −30 ° C. or lower so as to cover the core layer. A shell layer can be provided on the outermost shell having a glass transition temperature of 50 ° C. or higher so as to cover the intermediate layer.
The core-shell type particle (B) may have a structure of four or more layers. For example, a four-layer structure having a glass transition temperature of less than 50 ° C. inside the core layer may be used.

Each layer constituting the core-shell type particle (B) will be described.
First, the shell layer will be described.
In the present invention, the shell layer is the outermost shell layer of the core-shell type particles (B), and the monomer used in producing the shell layer contains acrylonitrile. Aggregation of core-shell particles can be prevented by the shell layer.

In the present invention, the monomer used in producing the shell layer includes acrylonitrile.
In this invention, when the monomer used when manufacturing a shell layer contains acrylonitrile with high polarity, compatibility with the epoxy resin (A) which is a matrix increases, and dispersibility improves.
Further, the polymer forming the shell layer has a nitrile group, and the nitrile group can form a hydrogen bond with a hydroxy group generated by curing of the epoxy resin (A). Further, the nitrile group can act on the interface of the adherend (for example, a steel plate) to enhance the adhesion.
As described above, the composition of the present invention has excellent adhesion performance from low temperature to high temperature and excellent flexibility due to the hydrogen bond with the epoxy resin (A) capable of forming a nitrile group and / or the action on the adherend. Can have sex.

In addition to acrylonitrile, the monomer used in producing the shell layer may further contain an aromatic vinyl monomer and a non-aromatic monomer other than acrylonitrile as a monomer copolymerizable with acrylonitrile. .
Examples of the aromatic vinyl monomer include styrene, vinyl toluene, α-methyl styrene, monochloro styrene, 3,4-dichlorostyrene, bromostyrene, and the like. Of these, styrene is preferred from the viewpoint of superior adhesion performance and flexibility from low to high temperatures.

  The amount of acrylonitrile is preferably in the range of 70% by mass or less, more preferably in the range of 50% by mass or less, based on the total amount of monomers used for producing the shell layer.

Examples of non-aromatic monomers other than acrylonitrile include alkyl acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate, alkyl methacrylates such as methyl methacrylate and butyl methacrylate; methacrylonitrile and the like. Examples include vinyl cyanide; vinylidene cyanide.
The amount of the non-aromatic monomer other than acrylonitrile is preferably in the range of 70% by mass or less, more preferably in the range of 50% by mass or less, based on the total amount of the monomers used for producing the shell layer. is there.

The shell layer may be crosslinked with a crosslinkable monomer.
Examples of the crosslinkable monomer that can be used in producing the shell layer include divinylbenzene and butylene glycol dimethacrylate. In particular, divinylbenzene is preferable from the viewpoint of excellent adhesion performance and flexibility from low temperature to high temperature. The amount of the crosslinkable monomer is usually in the range of 30% by mass or less, preferably in the range of 0.5 to 20% by mass, based on the total amount of the monomers used for producing the shell layer. Preferably it is the range of 5-15 mass%.

In the present invention, the shell layer is preferably a styrene-acrylonitrile copolymer or a styrene-acrylonitrile-divinylbenzene copolymer from the viewpoint that the shell layer is superior in adhesion performance and impact resistance from low temperature to high temperature.
In the present invention, the core-shell type particles (B) preferably have a glass transition temperature of 50 ° C. or higher, from 70 ° C. to 150 ° C., from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature. More preferably.
In the present invention, the glass transition temperature refers to the temperature of the peak value of tan δ in dynamic viscoelasticity measurement.

Next, the inner layer adjacent to the shell layer will be described below.
The inner layer adjacent to the shell layer preferably has a glass transition temperature of −30 ° C. or lower, more preferably −110 to −30 ° C., from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature. More preferably, the temperature is −110 to −40 ° C.

Monomers that can be used in producing the inner layer adjacent to the shell layer can include, for example, alkyl acrylates having 2 to 8 carbon atoms in the alkyl group, and butadiene.
Examples of the acrylic acid alkyl ester having 2 to 8 carbon atoms in the alkyl group include ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate.
Monomers that can be used in the production of the inner layer adjacent to the shell layer include, for example, acrylic acid alkyl esters or butadienes having an alkyl group with 2 to 8 carbon atoms, and other vinyl-based monomers copolymerizable therewith. A monomer can be used in combination. Examples of other vinyl monomers copolymerizable with acrylic acid alkyl ester include, for example, aromatic vinyl compounds such as styrene, vinyltoluene, and α-methylstyrene, aromatic vinylidene compounds, and cyanogen such as acrylonitrile and methacrylonitrile. And alkyl methacrylates such as vinyl chloride, vinylidene cyanide, methyl methacrylate, and butyl methacrylate.
The amount of the acrylic acid alkyl ester or other vinyl monomer copolymerizable with butadiene is usually in the range of 50% by weight or less based on the total amount of the monomers used in producing the inner layer adjacent to the shell layer. Preferably, it is the range of 30% by weight or less.

  The inner layer adjacent to the shell layer may be crosslinked with a crosslinkable monomer. The crosslinkable monomer has the same meaning as described above. The amount of the crosslinkable monomer used is usually in the range of 0.01 to 5% by mass, preferably 0.1%, based on the total amount of monomers that can be used when the inner layer adjacent to the shell layer is produced. It is the range of -2 mass%.

  Monomers that can be used in making the inner layer adjacent to the shell layer can further include a grafting monomer. The grafting monomer is not particularly limited.

The core layer in the case where the core-shell type particle (B) has three layers will be described below.
Examples of the monomer that can be used in producing the core layer in the three-layer core-shell type particle (B) include aromatic vinyl monomers. The aromatic vinyl monomer has the same meaning as described above.

In addition to the aromatic vinyl monomer, the monomer that can be used for producing the core layer in the three-layer core-shell type particle (B) is a non-aromatic monomer or a crosslinkable monomer. Can be included.
Examples of the non-aromatic monomer include alkyl acrylates such as ethyl acrylate and butyl acrylate, alkyl methacrylates such as methyl methacrylate and butyl methacrylate, vinyl cyanide and vinylidene cyanide such as acrylonitrile and methacrylonitrile. The amount of the non-aromatic monomer used is preferably in the range of 50% by mass or less, more preferably in the range of 20% by mass or less, based on the total amount of monomers that can be used when the core layer is produced. .

The core layer in the three-layer core-shell type particle (B) may be crosslinked with a crosslinkable monomer.
Examples of the crosslinkable monomer include monomers having two or more polymerizable ethylenically unsaturated bonds in the molecule. Specific examples include, for example, aromatic divinyl monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, hexanediol (meth) acrylate, oligoethylene glycol di (meth) acrylate, Examples include alkane polyol poly (meth) acrylates such as trimethylolpropane di (meth) acrylate and trimethylolpropane tri (meth) acrylate. Of these, divinylbenzene is particularly preferred.
The amount of the crosslinkable monomer used is usually in the range of 30% by mass or less, preferably in the range of 0.5 to 20% by mass, based on the total amount of monomers that can be used when the core layer is produced. Yes, more preferably in the range of 5 to 15% by mass.

The monomer that can be used in producing the core layer in the three-layer core-shell type particle (B) can further contain a grafting monomer.
It is preferable that the glass transition temperature of the core layer in the three-layer core-shell particle (B) is a material having a temperature of 50 ° C. or higher. The glass transition temperature of the core layer is more preferably 50 to 200 ° C, and further preferably 80 to 200 ° C. It is because the composition of this invention provided with adhesive force at higher temperature is obtained.

In the present invention, the core-shell type particles (B) preferably have an average primary particle diameter of 50 nm to 500 nm, and more preferably 50 to 300 nm. This is because the core-shell particles hardly aggregate and workability is good. Moreover, it is because the adhesive strength of the composition of this invention increases more.
The average value of the primary particle diameter of the core-shell particles means a value obtained by measurement using a zeta potential particle size distribution measuring apparatus (Beckman Coulter).
The core-shell type particles (B) can be used alone or in combination of two or more.

  The core-shell type particle (B) is not particularly limited for its production. For example, a conventionally well-known thing is mentioned.

  In the present invention, the amount of the core-shell type particles (B) is 5 to 100 parts by mass of the epoxy resin (A) from the viewpoint of excellent adhesion performance and flexibility from low temperature to high temperature and hardly causing interface fracture. 100 parts by mass. Further, the amount of the core-shell type particles (B) is preferably 5 to 100 parts by mass with respect to 100 parts by mass of the epoxy resin (A) from the viewpoint of superior adhesion performance and flexibility from low temperature to high temperature. More preferably, it is 10-100 mass parts.

Next, the curing agent (C) will be described.
The hardening | curing agent (C) contained in the composition of this invention is not specifically limited, What is normally used as a hardening | curing agent of an epoxy resin can be used. For example, dicyandiamide, 4,4′-diaminodiphenylsulfone, imidazole derivatives such as 2-n-heptadecylimidazole, isophthalic acid dihydrazide, N, N-dialkylurea derivatives, N, N-dialkylthiourea derivatives, tetrahydrophthalic anhydride An acid anhydride such as, isophoronediamine, m-phenylenediamine, N-aminoethylpiperazine, melamine, guanamine, boron trifluoride complex compound, trisdimethylaminomethylphenol, polythiol and the like can be used.

  The polythiol is not particularly limited as long as it is a compound having two or more mercapto groups. Examples of thiols having two mercapto groups include alkylene dithiols such as ethanedithiol, propanedithiol, butanedithiol, pentanedithiol, and hexanedithiol; benzenedithiol, toluene-3,4-dithiol, and 3,6-dichloro-1 , 2-benzenedithiol, 1,5-naphthalenedithiol, aromatic dithiols such as 4,4'-thiobisbenzenethiol; dithiols of aromatic hydrocarbon compounds such as benzenedimethanethiol; 2-di- heterocyclic compounds such as n-butylamino-4,6-dimercapto-s-triazine; 2-mercapto-3-thiahexane-1,6-dithiol, 5,5-bis (mercaptomethyl) -3,7-dithianonane -1,9-dithiol, 5- (2-mercap) Ethyl) -3,7 Jichianonan -1,9-thia compounds such as dithiol; dimercaptopropanol, compounds having a hydroxy group such as dithioerythritol, and the like.

Examples of the thiol having three or more mercapto groups include trithioglycerin, 1,3,5-triazine-2,4,6-trithiol (trimercapto-triazine), trimethylolpropane tristhioglycolate, trimethylolpropane. Tristhiopropionate, 1,2,4-tris (mercaptomethyl) benzene, 1,3,5-tris (mercaptomethyl) benzene, 2,4,6-tris (mercaptomethyl) mesitylene, tris (mercaptomethyl) Isocyanurates, tris (3-mercaptopropyl) isocyanurate, trithiols such as 2,4,5-tris (mercaptomethyl) -1,3-dithiolane; pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, Examples include tetrathiols such as 1,2,4,5-tetrakis (mercaptomethyl) benzene, tetramercaptobutane, and pentaerythrithiol.
Examples of the polythiol include polythiol (for example, “QE-340M” manufactured by Toray Fine Chemical Co., Ltd.) in which a mercapto group is introduced at the end of a polyether (for example, polyoxypropylene glycol).
You may use a hardening | curing agent (C) in combination of 2 or more types in these.

  Moreover, content in the composition of this invention of a hardening | curing agent (C) is not specifically limited, The optimal amount changes with kinds of hardening | curing agent. For example, the optimal amount for each curing agent known in the art can be preferably used. This optimum amount is described, for example, in Chapter 3 of “Review Epoxy Resin Basics” (Epoxy Resin Technical Association, published in 2003).

  In addition to the epoxy resin (A), the core-shell type particles (B) and the curing agent (C), the composition of the present invention may further include a catalyst, a curing accelerator, an inorganic filler, Alternatively, a polymer filler, a flame retardant, an antistatic agent, a conductivity imparting agent, a lubricant, a slidability imparting agent, a surfactant, a colorant and the like can be contained. Two or more of these may be contained.

  The manufacturing method of the composition of this invention is not specifically limited, For example, it can manufacture by a conventionally well-known method. For example, the epoxy resin (A), the core-shell type particles (B), the curing agent (C), and other components such as a curing accelerator as necessary can be obtained by uniformly mixing at room temperature.

  The composition of the present invention is excellent in adhesion performance and flexibility not only at a low temperature (about −20 ° C.) to a normal temperature but also at a high temperature (about 80 ° C.). Therefore, the composition of the present invention can be preferably used as a structural adhesive. Here, the “structural adhesive” is a highly reliable adhesive (JIS K6800) with little deterioration in adhesive properties even when a large load is applied for a long time. For example, it can be used as an adhesive for structural members in the fields of automobiles, vehicles (bullet trains, trains), civil engineering, architecture, electronics, aircraft, and the space industry.

1. Production of Epoxy Resin Composition Using the components shown in Table 1 in the amounts (parts by mass) shown in the same table, these were uniformly mixed to obtain the composition of the present invention.
2. Evaluation The epoxy resin composition obtained as described above was applied to the surface of a non-plated steel sheet at a thickness of 0.1 to 0.2 mm and subjected to a tensile shear strength test and a T-shaped peel strength test. Here, both tests were conducted according to JIS K-6850 (1999). The test piece (non-plated steel plate) used was 0.8 mm × 25 mm × 200 mm. The test results are shown in Table 1. Moreover, the fracture | rupture form in the T-shaped peel strength test at 80 degreeC was confirmed. The test results are shown in Table 1.

The details of each component shown in Table 1 are as follows.
Epoxy resin (A) 1: bisphenol A type epoxy resin, epoxy equivalent 190 g / eq (JER828, manufactured by Japan Epoxy Resin Co., Ltd.)
Epoxy resin (A) 2: urethane-modified epoxy resin, epoxy equivalent 211 g / eq (EPU-78-11, polyol component: polypropylene glycol (PPG), polyisocyanate component: tolylene diisocyanate (TDI), manufactured by ADEKA)
Epoxy resin (A) 3: rubber-modified epoxy resin, epoxy equivalent 305 g / eq (EBR-1309, NBR-modified BisA epoxy resin containing BisA epoxy resin, manufactured by ADEKA)
Core-shell type particle (B) 1: trade name IM-601 (manufactured by Ganz Kasei Co., Ltd., 3-layer structure, polymer forming shell layer is acrylonitrile / styrene copolymer, average particle size of primary particles = 200 to 300 nm The glass transition temperature of the shell layer: about 80 ° C. to 100 ° C., the glass transition temperature of the intermediate layer: about −50 ° C. to −60 ° C., the glass transition temperature of the core layer: about 80 ° C. to 100 ° C.)
Core-shell type particle (B) 2: Core-shell type according to the method described in JP-A-2-191614 using butyl acrylate as the monomer for forming the core and acrylonitrile and styrene as the monomers for forming the shell Particles were produced. The obtained core-shell type particles are referred to as “core-shell type particles (B) 2”. The core-shell type particles (B) 2 have an average primary particle size: 200 to 300 nm, a two-layer structure, components of the shell layer: acrylonitrile / styrene copolymer, a glass transition temperature of the shell layer: about 80 ° C. to 100 ° C., core Glass transition temperature of the layer: about −50 ° C. to −60 ° C.
Core-shell type particle (B) 3: Trade name F-351 (manufactured by Ganz Kasei, average primary particle size: 200 to 300 nm, two-layer structure, component of shell layer: MMA (methyl methacrylate), glass transition of shell layer (Temperature: 100 ° C to 120 ° C, glass transition temperature of core layer: about -50 ° C to -60 ° C)
Core-shell type particle (B) 4: MMA is used as a monomer for forming a core, butyl acrylate is used as a monomer for forming an intermediate layer, and methyl methacrylate is used as a monomer for forming a shell. Core-shell type particles were produced according to the method described in Japanese Patent Publication No. JP-A. The obtained core-shell type particles are referred to as “core-shell type particles (B) 4”. The core-shell type particle (B) 4 has an average primary particle size: 200 to 300 nm, a three-layer structure, a shell layer component: MMA (methyl methacrylate), a glass transition temperature of the shell layer: 100 ° C. to 120 ° C. Glass transition temperature: about −50 ° C. to −60 ° C., glass transition temperature of core layer: 100 ° C. to 120 ° C.
Curing agent (C): Dicyandiamide, trade name Dicy15 (manufactured by Japan Epoxy Resin Co., Ltd.)
Catalyst: 3- (3,4-dichlorophenyl) -1,1-dimethylurea, trade name DUMU99 (manufactured by Hodogaya Chemical Co., Ltd.)
-Filler: Silica (RY-200S, manufactured by Nippon Aerosil Co., Ltd.)

As is apparent from the results shown in Table 1, Comparative Examples 1 and 2 in which the monomer used for producing the shell layer did not contain acrylonitrile had poor dispersibility with the matrix resin and poor adhesion at high temperatures.
On the other hand, in Examples 1 to 5, the tensile shear strength and the T-shaped peel strength were good at any of −20 ° C., room temperature, and 80 ° C.
Moreover, Examples 1-3 which contain 10-100 mass parts of core-shell type | mold particles (B) with respect to 100 mass parts of epoxy resins (A) have the dispersibility of core-shell type particles (B) rather than Example 5. High and excellent in physical properties.
Examples 1 to 3 and 5 containing the core-shell type particles (B) having a three-layer structure were superior to Example 4 containing the core-shell type particles (B) having a two-layer structure in terms of high-temperature physical properties.
Further, regarding the fracture mode in the T-peel strength test at 80 ° C., Comparative Example 1 has a cohesive fracture of 60%, and Comparative Example 2 has a thin-layer cohesive fracture (the adhesive layer remains extremely thin on the surface of the adherend) 80% or more of Examples 1 to 5 were cohesive failure. Therefore, the reliability as an adhesive is high.

  It is to be noted that the interface failure occurs at the interface between the adhesive and the steel material that is the adherend, and the cohesive failure occurs within the adhesive layer. In order to ensure that the adhesive and the adherend are adhered, cohesive failure is preferred as the failure mode. Interfacial fracture is a condition in which the adhesive force cannot be controlled and is not reliable.

Claims (7)

Containing 100 parts by mass of epoxy resin (A), 5 to 100 parts by mass of core-shell type particles (B), and curing agent (C),
The epoxy resin composition in which the monomer used when manufacturing a shell layer in the said core-shell type particle | grains (B) contains acrylonitrile.   2. The epoxy resin composition according to claim 1, wherein a glass transition temperature of the shell layer is 50 ° C. or higher, and a glass transition temperature of an inner layer adjacent to the shell layer is −30 ° C. or lower.   The epoxy resin composition according to claim 1 or 2, wherein the core-shell type particles (B) have two layers and / or three layers.   The epoxy resin composition according to any one of claims 1 to 3, wherein an average primary particle diameter of the core-shell type particles (B) is 50 nm to 500 nm.   The said epoxy resin (A) contains at least 1 sort (s) chosen from the group which consists of a bisphenol A type epoxy resin with an epoxy equivalent of 220 or more, a urethane modified epoxy resin, and a rubber modified epoxy resin. Epoxy resin composition.   In the epoxy resin (A), the amount of the bisphenol A type epoxy resin having an epoxy equivalent of 220 or more is 0 to 100% by mass, the amount of the urethane-modified epoxy resin is 0 to 100% by mass, and the rubber modification The epoxy resin composition according to claim 5, wherein the amount of the epoxy resin is 0 to 100% by mass.   The epoxy resin composition according to any one of claims 1 to 6, which is used as a structural adhesive.