JP7184874B2 - adhesive composition - Google Patents

Description

The present invention relates to an adhesive composition comprising an adhesive resin and core-shell polymer particles.

In recent years, structural adhesives have been used in various fields. For example, in the automotive field, a method of strengthening the joints of structural members has been attempted as a technology to achieve both weight reduction and rigidity improvement of the car body. The technology (weld bond method) is attracting attention. Epoxy resin-based heat-curable adhesives (structural adhesives) are widely used as the adhesive applied to the joints, and are cured by heating after spot welding.

In the field of wind power generators, it is necessary to reduce the weight, increase the strength, and increase the rigidity of the blade itself in order to reduce the load applied to the entire device. It has become. In such a blade structure, a strength member is arranged in the longitudinal direction of the blade center, and members molded with a composite material along the shape of the blade surface and the blade back surface are bonded with an adhesive so as to sandwich the strength member. There are many things.

These adhesives are required to have high fatigue resistance to withstand long-term use, and generally attention is paid to the toughness of adhesives. As a method for improving the toughness of an adhesive, there is a method of adding fine polymer particles having a core-shell structure to an epoxy resin, as described in Patent Document 1, for example. However, when the toughness of the adhesive is improved, interfacial failure is induced at the interface between the adhesive layer and the adherend at the time of fatigue failure, and as a result, there is a problem that fatigue resistance is difficult to improve. As shown in FIG. 1, the reason for this is thought to be that cracks are induced and propagated at relatively weak interfaces due to the improved toughness of the adhesive.

The failure mode of the adhesive layer includes "cohesive failure" in which the inside of the adhesive layer is destroyed, and the above-mentioned "interfacial failure". Cohesive failure is preferable as the failure mode in order to ensure that the adhesive layer and the adherend are adhered. Interfacial failure is a state in which the adhesive force cannot be controlled, and reliability is poor. For the above reasons, there is a demand for an adhesive that has high fatigue resistance and exhibits cohesive failure when fatigue failure occurs.

Patent Document 2 discloses a structural adhesive composition excellent in resistance to running water pressure, containing an epoxy resin, core-shell rubber particles in a dispersed state in which primary particles and secondary aggregates are mixed, and a curing agent. is disclosed. This document does not describe fatigue resistance. In the adhesive composition described in this document, secondary agglomerates of core-shell type rubber particles must be mixed with primary particles. It is considered that the physical properties of the adhesive are not stable.

Patent Document 3 discloses an epoxy resin composition that can be used as a structural adhesive, comprising an epoxy resin, core-shell rubber particles, and a hollow polymer. This document does not describe fatigue resistance. Moreover, if a hollow polymer is used, it is considered that the hollow polymer will be broken by the impact received when the components are compounded and mixed, making it difficult to disperse the hollow polymer as primary particles.

WO2015/064561 JP 2015-108077 A JP 2010-270198 A

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide an adhesive composition that exhibits excellent fatigue resistance and causes cohesive failure at the time of fatigue failure.

As a result of intensive studies by the present inventors, in addition to nanometer-order core-shell polymer particles blended to improve the toughness of the adhesive, polymer particles having a particle size larger than the core-shell polymer particles are added at a specific ratio. By blending in the adhesive composition and dispersing all the particles as primary particles in the adhesive composition, the adhesive layer has high toughness and induces cracks inside the adhesive layer at the time of fatigue failure. As a result, the present inventors have found that a highly reliable adhesive composition can be obtained that has greatly improved fatigue resistance and undergoes cohesive failure at the time of fatigue failure, leading to the present invention. That is, the present invention provides the following 1) to 7).

1) Adhesive resin, core-shell polymer particles (A) having a volume average particle size of 10 to 300 nm, and polymer particles (B) having a volume average particle size of 400 nm to 10000 nm, core-shell polymer particles (A): polymer particles The weight ratio of (B) is 1:2 to 2:1, and the core-shell polymer particles (A) and the polymer particles (B) are each dispersed as primary particles in the adhesive composition. adhesive composition.
2) The adhesive composition according to 1), wherein the polymer particles (B) are polymer particles having no hollow structure.
3) The adhesive composition according to 1) or 2), wherein the polymer particles (B) are core-shell polymer particles.
4) the core layer of the core-shell polymer particle (A) or the core layer of the polymer particle (B) is selected from the group consisting of (i) a diene-based monomer and a (meth)acrylic acid ester-based monomer; (ii) polysiloxane rubber-based elastomer, (iii) an aromatic vinyl crosslinked product, or (iv) a mixture of two or more of the above (i) to (iii), wherein the other copolymerizable vinyl monomer is an aromatic vinyl compound or a vinyl cyanide compound; , unsaturated carboxylic acid derivatives, (meth)acrylic acid amide derivatives, and maleimide derivatives, the adhesive composition according to any one of 1) to 3).
5) The adhesive composition according to any one of 1) to 4), wherein the shell layer of the core-shell polymer particles (A) contains reactive groups.
6) The adhesive composition according to 5), wherein said reactive group comprises an epoxy group.
7) The content of the monomer unit having a reactive group contained in the polymer constituting the shell layer of the polymer particles (B) is 0 to 5 parts by weight with respect to 100 parts by weight of the polymer particles (B). , 3) to 6).
8) The adhesive composition according to any one of 1) to 7), wherein the adhesive resin comprises an epoxy resin.

According to the present invention, it is possible to provide an adhesive composition that exhibits excellent fatigue resistance and causes cohesive failure when fatigue failure occurs.

For comparison, a conceptual diagram showing the state of interfacial failure in which cracks occurred at the interface between the adhesive layer and the base material when an adhesive containing only the core-shell polymer particles (A) was used. For comparison, a conceptual diagram showing a state of cohesive failure in which cracks occur inside the adhesive layer when using an adhesive containing only polymer particles (B) having a large particle size. A conceptual diagram showing a state of cohesive failure in which cracks occur inside the adhesive layer when an adhesive containing core-shell polymer particles (A) and polymer particles (B) having a large particle size is used. A side view showing the test piece and the spacer in the process of manufacturing the shear adhesion test piece used in the evaluation of Examples and Comparative Examples. Side view showing a shear adhesion test piece used in the evaluation of Examples and Comparative Examples

The adhesive composition of the present invention contains an adhesive resin, core-shell polymer particles (A) having a volume average particle size of 10 to 300 nm, and polymer particles (B) having a volume average particle size of 400 nm to 10000 nm, and a core-shell The weight ratio of polymer particles (A):polymer particles (B) is 1:2 to 2:1, and core-shell polymer particles (A) and polymer particles (B) are dispersed as primary particles in the adhesive composition. It is characterized by having the form

(adhesive resin)
The adhesive resin, which is the matrix resin in the adhesive composition of the present invention, can be selected from various resins exhibiting adhesiveness regardless of whether they are thermoplastic or curable, and is not particularly limited. vinyl acetate copolymer resins, polyolefin resins, polyamide resins, synthetic rubbers, acrylic resins, polyurethane resins, etc.; Resin etc. are mentioned. Epoxy resins are preferred from the viewpoint of adhesiveness, coatability, heat resistance, and the like.

Epoxy resins may generally be compounds having two or more epoxy groups. Bifunctional glycidyl ether type such as epoxy compounds having a bisphenyl group such as AF type and biphenyl type, epoxy compounds such as polyalkylene glycol type and alkylene glycol type, epoxy compounds having a naphthalene ring, and epoxy compounds having a fluorene group. Epoxy resins, novolac type epoxy resins such as phenol novolac type and ortho cresol novolak type, polyfunctional glycidyl ether type epoxy resins such as tetraphenylol ethane type, etc., glycidyl ester type of synthetic fatty acids such as dimer acid Glycidylamino groups such as epoxy resins, N,N,N',N'-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N,N-diglycidylaniline Aromatic epoxy resins, trishydroxyphenylmethane type epoxy resins, epoxy compounds having a tricyclodecane ring (for example, dicyclopentadiene and cresols such as m-cresol or phenols are polymerized, and then epichlorohydrin is reacted. Epoxy compound obtained by a manufacturing method that causes the epoxy compound), trishydroxyphenylmethane-type epoxy resin, sorbitol-type epoxy resin, polyglycerol-type epoxy resin, glycidyl ester-type epoxy resin, heterocyclic epoxy resin, diarylsulfone-type epoxy resin, pentaerythritol-type Epoxy resins, trimethylolpropane-type epoxy resins, and the like are included. The epoxy resin can be appropriately selected according to the use of the adhesive composition, etc., and may be used alone or in combination of two or more. Bisphenol A-type epoxy resins and bisphenol F-type epoxy resins are particularly preferable in terms of facilitating adjustment of the viscosity of the adhesive composition.

A bisphenol A type epoxy resin is a polycondensation compound of bisphenol A and epichlorohydrin. The bisphenol A skeleton enhances heat resistance and toughness to increase tensile shear bond strength, and the ether groups in the skeleton enhance chemical resistance, and the methylene chains enhance flexibility. As the bisphenol A type epoxy resin, a liquid to a solid can be used depending on the molecular weight, but a liquid to a semi-solid at room temperature is preferred, and a liquid is particularly preferred. This is because the handleability and the coating workability of the composition are facilitated. Also, the epoxy equivalent is preferably in the range of 180 to 300 g/eq. The epoxy equivalent means the number of grams of resin containing 1 gram equivalent of epoxy group (unit: g/eq).

Furthermore, as the epoxy resin, it is also possible to use a modified epoxy resin such as a urethane-modified epoxy resin and a dimer acid-modified epoxy resin. 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. A resin obtained by reacting a urethane bond-containing compound having an isocyanate group with a hydroxy group-containing epoxy compound is preferred because it can be introduced into the molecule. These epoxy resins can be used alone or in combination of two or more.

The adhesive composition of the present invention may contain an appropriate curing agent depending on the type of adhesive resin. When the adhesive resin is an epoxy resin, the curing agent used in combination with it may have an active group capable of reacting with the epoxy group. Such curing agents include, for example, imidazole compounds such as dicyandiamide, 4,4'-diaminodiphenylsulfone, 2-n-heptadecylimidazole, adipic acid dihydrazide, stearic acid dihydrazide, isophthalic acid dihydrazide, and dibasic acid hydrazide. , organic acid hydrazide compounds such as isophthalic acid dihydrazide, urea compounds such as N,N-dialkylurea derivatives and N,N-dialkylthiourea derivatives, acid anhydrides such as tetrahydrophthalic anhydride, semicarbazide, cyanoacetamide, diamino Amine compounds such as diphenylmethane, tertiary amines, polyamines, isophoronediamine and m-phenylenediamine, aminotriazoles such as 3-amino-1,2,4-triazole, N-aminoethylpiperazine, melamines, acetoguanamine and benzoguanamine guanamines such as guanidines, dimethylureas, boron trifluoride complex compounds, boron trichloride complex compounds, liquid phenols such as trisdimethylaminomethylphenol, polythiol, triphenylphosphine, ketimine compounds, sulfonium salts, onium salts, A phenol novolak resin and the like are included. These may be used alone or in combination of two or more. Among them, dicyandiamide, 4,4'-diaminodiphenylsulfone, and isophoronediamine are preferable from the viewpoint of adhesive strength of the composition.

When a curing agent is blended, the blending amount is preferably in the range of 5 parts by weight to 30 parts by weight with respect to 100 parts by weight of the adhesive resin. When the amount of the curing agent is 5 parts by weight or more, the curing speed of the adhesive composition is high, and the curing reaction proceeds sufficiently to improve physical properties such as adhesive strength, which is preferable. Then, the desired physical properties required for the adhesive composition can be easily obtained. A preferred blending amount of the curing agent is in the range of 7 to 30 parts by weight.

(Core-shell polymer particles (A))
The adhesive composition of the present invention contains core-shell polymer particles (A) having a smaller particle size than polymer particles (B). By blending this, the toughness of the adhesive composition can be increased and excellent fatigue resistance can be achieved.

The volume average particle diameter of the core-shell polymer particles (A) is 10 nm to 300 nm, more preferably 30 nm to 250 nm, even more preferably 60 nm to 200 nm, and most preferably 80 nm to 150 nm. When the volume average particle size of the core-shell polymer particles (A) is less than 10 nm or greater than 300 nm, the effect of increasing the toughness of the adhesive composition by the core-shell polymer particles (A) is reduced.

In the present invention, the volume average particle diameter (Mv) of the core-shell polymer particles (A) is measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) while being dispersed in an aqueous latex or resin composition. value. When measuring the volume average particle diameter of particles in the aqueous latex, the aqueous latex is diluted with deionized water to adjust the sample concentration so that the Signal Level is within the range of 0.6 to 0.8, The refractive index of water and the refractive index of the polymer particles to be measured were input, and the measurement was performed with a measurement time of 600 seconds. When measuring the volume average particle diameter of the particles in the resin composition, the resin composition is diluted with methyl ethyl ketone to adjust the sample concentration so that the Signal Level is within the range of 0.6 to 0.8, The refractive index of methyl ethyl ketone and the refractive index of the polymer particles to be measured were input, and the measurement was performed with a measurement time of 600 seconds. Note that the above description regarding the measurement of the volume average particle size also applies to the measurement of the volume average particle size of the polymer particles (B).

The core-shell polymer particle (A) is a core-shell polymer particle in which a shell layer is formed by graft-polymerizing a graft-copolymerizable monomer (shell-forming monomer) to a crosslinked polymer serving as a core layer, It has a structure having a core layer made of a crosslinked polymer existing inside and at least one shell layer graft-polymerized on the surface of the core layer to cover the periphery or part of the crosslinked polymer. From the viewpoints of reducing the viscosity of the adhesive composition of the present invention to make it easy to handle, stably dispersing the core-shell polymer particles in the adhesive composition, and enhancing the effect of increasing the toughness of the adhesive composition, The weight ratio of the core layer to the shell layer is preferably in the range of 50/50 to 99/1 in terms of core layer/shell layer (weight ratio of monomers forming the polymer of each layer). /40 to 95/5, more preferably 70/30 to 90/10.

Preferably, the core layer is composed of a crosslinked polymer and is substantially insoluble in solvents. Therefore, the gel content of the core layer is preferably 60% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

The core layer contains (i) 50% by weight or more of one or more monomers selected from the group consisting of diene-based monomers and (meth)acrylic acid ester-based monomers, and other copolymerizable vinyl (ii) a polysiloxane rubber-based elastomer, (iii) an aromatic vinyl crosslinked body, or (iv) two of (i) to (iii) above. A mixture of the above is preferred. 1, wherein the other copolymerizable vinyl monomer is selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds, unsaturated carboxylic acid derivatives, (meth)acrylic acid amide derivatives, and maleimide derivatives; Seeds or more are preferred. In the present invention, (meth)acryl means acryl and/or methacryl.

Examples of the diene-based monomer include butadiene, isoprene, chloroprene, and the like, but butadiene is particularly preferred. Examples of the (meth)acrylate monomer include butyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate and the like, but butyl acrylate and 2-ethylhexyl acrylate are particularly preferred. These may be used alone or in combination of two or more.

The amount of one or more monomers selected from the group consisting of diene-based monomers and (meth)acrylic acid ester-based monomers is preferably 50% by weight or more, more Preferably, it is 60% by weight or more. If the amount of the monomer used is less than 50% by weight, the toughening effect exhibited by the core-shell polymer particles may decrease.

The core layer may be a homopolymer or copolymer obtained by polymerizing at least one monomer selected from the group consisting of diene-based monomers and (meth)acrylic acid ester-based monomers. may be a copolymer of a diene-based monomer and/or a (meth)acrylic acid ester-based monomer and a vinyl monomer copolymerizable therewith. Examples of such copolymerizable vinyl monomers include one selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds, unsaturated carboxylic acid derivatives, (meth)acrylic acid amide derivatives, and maleimide derivatives. The above monomers can be mentioned. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, vinylnaphthalene, and the like, and examples of vinyl cyanide compounds include (meth)acrylonitrile, substituted acrylonitrile, and the like. Examples of unsaturated carboxylic acid derivatives include (meth)acrylic acid, itaconic acid, crotonic acid, and maleic anhydride. (Meth)acrylamide derivatives include (meth)acrylamide (including N-substituents) and the like. Maleimide derivatives include maleimide (including N-substituted compounds) and the like. These may be used alone or in combination of two or more. The amount of these copolymerizable vinyl monomers used is preferably less than 50% by weight, more preferably less than 40% by weight, based on the weight of the entire core layer.

The core layer may be a crosslinked aromatic vinyl. Examples of the crosslinked product include a copolymer of an aromatic vinyl compound and a crosslinkable monomer. Examples of aromatic vinyl compounds include unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; substituted vinyl aromatic compounds such as α-methylstyrene; 3-methylstyrene, 4-methylstyrene, 2,4 - ring-alkylated vinyl aromatic compounds such as dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene and 2,4,6-trimethylstyrene; ring alkoxyls such as 4-methoxystyrene and 4-ethoxystyrene; vinyl aromatic compounds; ring-halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; ring ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene; ring compounds such as 4-hydroxystyrene Hydroxylated vinyl aromatic compounds may be mentioned. An adhesive composition containing core-shell polymer particles using an aromatic vinyl crosslinked body in the core layer is preferable because it can be toughened without lowering its rigidity.

When the core layer contains (i) a rubber elastomer or (iii) an aromatic vinyl crosslinked material, the polymer constituting the core layer is a copolymer obtained by copolymerizing a crosslinkable monomer in order to adjust the degree of crosslinking. is preferred. Examples of crosslinkable monomers include divinylbenzene, butanediol di(meth)acrylate, triallyl (iso)cyanurate, allyl (meth)acrylate, diallyl itaconate, and diallyl phthalate. The amount of the crosslinkable monomer used is 0.2 to 7% by weight, preferably 0.5 to 5% by weight, more preferably 1 to 3% by weight, based on the total weight of the core-shell polymer particles. If the amount used exceeds 7% by weight, the toughening effect and stress relaxation effect of the core-shell polymer particles may decrease.

The core layer may contain a polysiloxane rubber-based elastic body. As the polysiloxane rubber-based elastic body, polysiloxane rubber composed of alkyl- or aryl-disubstituted silyloxy units such as dimethylsilyloxy, methylphenylsilyloxy and diphenylsilyloxy can be used. In addition, the polysiloxane rubber-based elastic material may be crosslinked by partially using a polyfunctional alkoxysilane compound during polymerization, or by radically reacting a silane compound having a vinyl reactive group, if necessary. Those with introduced structures are more preferable.

The glass transition temperature (hereinafter sometimes simply referred to as “Tg”) of the core layer is preferably 0° C. or lower, and −20° C., in order to enhance the toughness and stress relaxation effect of the resulting adhesive composition. The following is more preferable, −40° C. or less is still more preferable, and −60° C. or less is particularly preferable.

The polymer constituting the shell layer in the core-shell polymer particles is a (meth)acrylic acid ester-based monomer, an aromatic vinyl-based monomer, a vinyl cyanide-based monomer, an unsaturated carboxylic acid derivative, or a (meth)acrylamide derivative. and a (co)polymer obtained by polymerizing one or more selected from the group consisting of maleimide derivatives.

In particular, the shell layer of the core-shell polymer particles (A) can effectively suppress re-aggregation of the core-shell polymer particles (A) during curing of the adhesive composition, resulting in deterioration of the dispersion state. It is preferred to have a group. As the reactive group, for example, at least one group selected from the group consisting of an epoxy group, a carboxyl group, a hydroxyl group, an amino group, and a carbon-carbon double bond is preferred. The shell layer having a reactive group contains a (meth)acrylic acid ester-based monomer, an aromatic vinyl-based monomer, a vinyl cyanide-based monomer, an unsaturated carboxylic acid derivative, a (meth)acrylamide derivative, and/or It is preferably composed of a copolymer obtained by copolymerizing a maleimide derivative and one or more vinyl monomers having a reactive group as described above. Among others, the reactive group of the shell layer of the core-shell polymer particle (A) preferably contains an epoxy group.

Examples of the (meth)acrylic acid ester-based monomers include (meth)acrylic esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. acid alkyl esters. Examples of aromatic vinyl-based monomers include styrene, alkyl-substituted styrenes such as α-methylstyrene, and halogen-substituted styrenes such as bromostyrene and chlorostyrene. Vinyl cyanide monomers include (meth)acrylonitrile, substituted (meth)acrylonitrile, and the like. Examples of unsaturated carboxylic acid derivatives include (meth)acrylic acid, itaconic acid, crotonic acid, and maleic anhydride. (Meth)acrylamide derivatives include (meth)acrylamide (including N-substituents) and the like. Maleimide derivatives include maleimide (including N-substituted compounds) and the like. Examples of monomers having a reactive group include (meth)acrylic esters having a reactive side chain, such as 2-hydroxyethyl (meth)acrylate, 2-aminoethyl (meth)acrylate, (meth) ) Glycidyl acrylate, etc.; Vinyl ethers having a reactive group include glycidyl vinyl ether, allyl vinyl ether, and the like.

In the present invention, the shell layer of the core-shell polymer particles (A) is composed of, for example, an aromatic vinyl monomer (particularly styrene) of 0 to 50% by mass (preferably 5 to 40% by mass) and a vinyl cyanide monomer. (Especially acrylonitrile) 0 to 50% by mass (preferably 1 to 30% by mass, more preferably 10 to 25% by mass), (meth) acrylic acid ester monomer (especially methyl methacrylate) 0 to 50% by mass ( preferably 5 to 45% by mass), and a monomer having a reactive group (especially glycidyl methacrylate) 0 to 50% by mass (preferably 5 to 30% by mass, more preferably 10 to 25% by mass). It is preferably composed of a polymer of layer-forming monomers (100 mass % in total).

The method for producing core-shell polymer particles is not particularly limited, and they can be produced by well-known methods such as emulsion polymerization, suspension polymerization, and microsuspension polymerization. Among these, a manufacturing method using multi-stage emulsion polymerization is particularly suitable. Specific examples of emulsifying (dispersing) agents used in emulsion polymerization include alkyl or aryl sulfonic acids such as dioctylsulfosuccinic acid and dodecylbenzenesulfonic acid, alkyl or aryl ether sulfonic acids, alkyl or aryl sulfuric acids such as dodecyl sulfate, Alkyl or aryl ether sulfates, alkyl or aryl ether substituted phosphates, alkyl or aryl ether substituted phosphates, N-alkyl or aryl sarcosinates such as dodecyl sarcosinate, alkyl or aryl carboxylic acids such as oleic acid and stearic acid, alkyl or aryl alkali metal salts or ammonium salts of various acids such as ether carboxylic acids; nonionic emulsifiers or dispersants such as alkyl- or aryl-substituted polyethylene glycols; dispersions such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, polyacrylic acid derivatives, etc. agents and the like. These can be used singly or in combination of two or more.

From the viewpoint of polymerization stability, the emulsifier is preferably an anionic emulsifier, more preferably an alkali metal salt anionic emulsifier, and still more preferably a sodium salt and/or potassium salt anionic emulsifier.

These emulsifying (dispersing) agents may be used in as small a quantity as possible in the process of producing an aqueous latex containing core-shell polymer particles, as long as the dispersion stability is not adversely affected. Alternatively, in the process of producing the adhesive composition of the present invention, it may be extracted and removed to the extent that the physical properties of the produced adhesive composition are not affected. For this reason, the emulsifying (dispersing) agent is more preferably water-soluble.

In the adhesive composition of the present invention, the core-shell polymer particles (A) are dispersed in the form of primary particles. Dispersion in the state of primary particles means that, for example, the value of volume average particle diameter (Mv)/number average particle diameter (Mn) of the particles measured in the adhesive composition is 3 or less. can be confirmed. This value is preferably 2.5 or less, more preferably 2 or less, and even more preferably 1.5 or less. When the volume average particle diameter (Mv)/number average particle diameter (Mn) of particles measured in the adhesive composition exceeds 3, the adhesive composition contains a large amount of secondary aggregates. As a result, the physical properties of the adhesive become unstable, such as making it difficult to develop high fatigue resistance. The value of volume average particle size (Mv)/number average particle size (Mn) is calculated using Microtrac UPA (manufactured by Nikkiso Co., Ltd.) according to the above description. It can be obtained by measuring the particle size (Mv) and the number average particle size (Mn) and dividing the volume average particle size (Mv) by the number average particle size (Mn).

The content of the core-shell polymer particles (A) in the adhesive composition of the present invention is preferably 0.5 to 20 parts by weight, more preferably 3 to 15 parts by weight, per 100 parts by weight of the adhesive composition. , more preferably 5 to 10 parts by weight. When the content of the core-shell polymer particles (A) is less than 0.5 parts by weight, the effect of increasing the toughness of the adhesive composition by the core-shell polymer particles (A) is small, and when it is more than 20 parts by weight, fatigue Cracks may propagate at the interface between the adhesive layer and the substrate upon fracture, degrading fatigue resistance.

(Polymer particles (B))
The adhesive composition of the present invention contains polymer particles (B) having a larger particle size than core-shell polymer particles (A). The polymer particles (B) are particles whose shape does not substantially change during the adhesive composition and after curing. For example, like the islands of a sea-island structure produced by a polymer alloy, the shape changes depending on the compounding ratio and curing conditions. Compounds of the class do not fall under polymer particles (B). Further, the polymer particles (B) are preferably polymer particles that do not have a hollow structure (that is, polymer particles that do not have voids containing liquid and/or gas inside the particles). This is because when such polymer particles are used, the particles are less likely to be broken even if they receive an impact when the components are blended and mixed, making it easier to disperse them as primary particles. By blending the polymer particles (B) as described above, it becomes easy to control the particle size and the content of the particles, and the physical properties of the adhesive are stabilized.

By blending the polymer particles (B), peeling occurs at the interface between the matrix resin inside the adhesive layer and the polymer particles (B), as shown in FIG. 3, as compared with the interface between the adhesive layer and the substrate. This makes it easier to induce cracks in the adhesive layer rather than at the interface between the adhesive layer and the substrate. As a result, cohesive failure is more likely to progress than interfacial failure during fatigue failure. However, as shown in FIG. 2, when only the polymer particles (B) are blended, the toughness of the adhesive layer is low and excellent fatigue resistance cannot be achieved. By blending both the core-shell polymer particles (A) with a small particle size and the polymer particles (B) with a large particle size, it is possible to synergistically achieve the effect of improving fatigue resistance.

The volume average particle diameter of the polymer particles (B) is 400 nm to 10000 nm, more preferably 500 nm to 8000 nm, even more preferably 1000 nm to 6000 nm, and most preferably 2000 nm to 4000 nm. When the volume average particle diameter of the polymer particles (B) is less than 400 nm, separation at the interface between the matrix resin and the polymer particles is less likely to occur, so the effect of inducing cracks in the adhesive layer is reduced. Further, when the volume average particle diameter of the polymer particles (B) is larger than 10000 nm, it becomes necessary to increase the content of the polymer particles (B) in order to induce cracks in the adhesive layer. difficult to express. The volume average particle size of the polymer particles (B) can be measured in the same manner as the volume average particle size of the core-shell polymer particles (A) described above.

The polymer particles (B) according to the present invention are particles composed of a polymer because they are suitable for relieving repeated stress during long-term use. The shape of the particles is not particularly limited, and the particles may be of any shape such as spherical or tabular. The type of polymer that constitutes the polymer particles (B) is not particularly limited. be done. The polymer particles (B) are preferably polyolefins, polysiloxanes, fluorine-containing resins, or core-shell polymer particles, since it is easy to design such that separation can be ensured at the interface between the matrix resin and the polymer particles (B). preferable. Specific examples of polyolefins include polyethylene and polypropylene, and specific examples of fluorine-containing resins include polytetrafluoroethylene.

The details of the core-shell polymer particles, which are a preferred embodiment of the polymer particles (B), are the same as the details of the core-shell polymer particles (A), so description thereof is omitted. However, since it is preferable that the polymer particles (B) separate from the matrix resin at the time of fatigue failure from the viewpoint of the effect of the invention, in the core-shell polymer particles, which is a preferred embodiment of the polymer particles (B), the shell layer is separated from the matrix resin. It is preferable to have no reactive groups to react with or, if they have them, the amount thereof is small. Specifically, the content of the monomer unit having a reactive group contained in the polymer constituting the shell layer of the core-shell polymer particles is 0 to 5 parts by weight with respect to 100 parts by weight of the polymer particles (B). 0 to 4 parts by weight is more preferred, 0 to 3 parts by weight is even more preferred, and 0 to 2 parts by weight is most preferred. The reactive group and the monomer having the reactive group are the same as described above.

In the adhesive composition of the present invention, the polymer particles (B) are dispersed in the form of primary particles, like the core-shell polymer particles (A). As in the case of the core-shell polymer particles (A), the primary dispersion means that the value of the volume average particle diameter (Mv)/number average particle diameter (Mn) of the particles measured in the adhesive composition is 3. This can be confirmed by: The preferred range and calculation method of volume average particle size (Mv)/number average particle size (Mn) are the same as those described above for the core-shell polymer particles (A).

The content of the polymer particles (B) in the adhesive composition of the present invention is preferably 1 to 10 parts by weight, more preferably 2 to 8 parts by weight, based on 100 parts by weight of the adhesive composition. More preferably 3 to 6 parts by weight, particularly preferably 4 to 5 parts by weight. When the content of the polymer particles (B) is less than 1 part by weight, the effect obtained by adding the polymer particles (B) is small, and when it is more than 10 parts by weight, the core-shell polymer particles (A) form an adhesive composition. In some cases, the adhesive composition becomes so brittle that the effect of increasing the toughness of the product is not exhibited, and the fatigue resistance is lowered.

In the adhesive composition of the present invention, the weight ratio of the core-shell polymer particles (A) and the polymer particles (B) is (A):(B) = 1:2 to 2:1, 2:3 to 3: 2 is preferred, 4:5 to 5:4 is more preferred, and 1:1 is even more preferred. When the amount of polymer particles (B) is relatively higher than 1:2, the adhesive composition becomes embrittled and fatigue resistance deteriorates. When the amount of the core-shell polymer particles (A) is relatively larger than 2:1, cracks propagate at the interface between the adhesive layer and the base material at the time of fatigue failure, resulting in interfacial failure and deterioration of fatigue resistance. do.

There are various methods for specifying the fracture form after the fatigue test described above. When the adhesive remains on the surface of the metal substrate, it is evaluated as cohesive failure (CF), and when it is less than 40%, it is evaluated as interfacial failure (AF). As a method other than visual observation, the fatigue fracture surface is observed with a backscattered electron image of a scanning electron microscope, and each pixel of the image obtained is divided into 255 monochrome gradations to represent the distribution of brightness. There is also a method of binarizing 0 to 218 as an adhesive and 219 to 255 tones as an adherend, and calculating the ratio of the area where the adhesive layer remains.

(Optional component)
A thixotropic agent may be added to the adhesive composition of the present invention in order to improve handling properties. Such a thixotropic agent is not particularly limited, but examples thereof include carbon black such as Ketjenblack, silica, fine grain calcium carbonate, and sepiolite. A thixotropic agent can be used alone or in combination of two or more. When a thixotropic agent is blended, the blending amount is preferably 10 parts by weight or less with respect to 100 parts by weight of the adhesive resin from the viewpoint of coating workability and adhesive strength. As the thixotropic agent, it is preferable to use solid particles having an average particle size in the range of 0.01 μm to 0.1 μm as measured by a laser diffraction/scattering method. If the average particle size is less than 0.01 µm, the viscosity of the adhesive composition may increase and the handleability may deteriorate. It's for.

In addition, the adhesive composition of the present invention may contain fillers to adjust the viscosity of the composition and improve the mechanical properties, etc., to the extent that the effects of the present invention are not impaired. Such fillers are not particularly limited, but examples include calcium carbonate, talc, magnesia, calcium silicate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, alumina, zircon, graphite, barium sulfate, clay, mica, Kaolin, wollastonite, mica, feldspar, syenite, chlorite, talc, bentonite, montmorillonite, barite, dolomite, quartz, diatomaceous earth, calcium silicate, aluminum silicate, barium carbonate, magnesium carbonate , zinc carbonate, textile fiber, glass fiber, aramid pulp, boron fiber, carbon fiber, phosphate, crystalline silica, amorphous silica, fused silica, fumed silica, pyrogenic silica, precipitated silica, pulverized (fine powder) silica, etc. silica, pyroxene, silica sand, cristobalite, cellulose, cement, calcium oxide, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, titanium dioxide, hollow inorganic beads such as hollow ceramic beads and hollow glass beads, polyester Hollow organic beads made of resin or the like, glass beads, metal powders, bituminous substances, and the like can be used. These may be used alone or in combination of two or more. From the point of view of dispersibility, etc., calcium carbonate is preferable. When a filler is blended, the blending amount is preferably 80 parts by weight or less with respect to 100 parts by weight of the adhesive resin from the viewpoint of coating workability and adhesive strength. Further, when the filler is particulate, it is preferable that the average particle diameter measured by a laser diffraction/scattering method is within the range of 0.05 μm to 500 μm. If the average particle size is less than 0.05 μm, the viscosity of the adhesive composition may increase and the handling property may become poor. have a nature.

The adhesive composition of the present invention may optionally contain various additives such as catalysts, curing accelerators, plasticizers, reactive diluents, reaction retarders, anti-aging agents, antioxidants, pigments, Dyes, colorants, coupling agents, leveling agents, thixotropic agents, adhesion agents, flame retardants, antistatic agents, conductivity agents, lubricants, slidability agents, UV absorbers, surfactants, A dispersant, a dispersion stabilizer, an antifoaming agent, a dehydrating agent, a cross-linking agent, an antirust agent, a solvent, and the like can be blended.

The adhesive composition of the present invention can be prepared by uniformly mixing and stirring these ingredients with a known mixing and dispersing machine such as a planetary mixer, disper, Henschel mixer, kneader, and the like. Alternatively, a mixture of the adhesive resin and the core-shell polymer particles (A) and a mixture of the adhesive resin and the polymer particles (B) are respectively prepared, and then the two mixtures are mixed to prepare the adhesive composition of the present invention. may Further, in order to disperse each of the core-shell polymer particles (A) and the polymer particles (B) as primary particles in the adhesive composition, can be achieved by distilling off the dispersion medium (or solvent) from the dispersion after dissolving the adhesive resin.

The adhesive composition of the present invention thus prepared is applied to an object to be adhered by a known method such as spray, gun or brush coating. In addition, it is also possible to use spot welding together after application (weld bond method) to improve the bondability of the adherend.

Since the adhesive composition of the present invention has high fatigue resistance and adhesion reliability, it can be used for automobiles, vehicles (bullet trains, trains), wind power generators, civil engineering, construction, electronics, ships, aircraft, space industry, etc. It can be used as an adhesive for structural members. At this time, spot welding or the like using electrodes or the like can be used in combination (weld bond method) to ensure high bonding strength to the structural portion. In addition, it can also be used as an adhesive for general office use, medical use, and electronic materials.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. For reagents, those manufactured by Wako Pure Chemical Industries, Ltd. were used unless otherwise specified.

Evaluation methods used in the present invention are described below.
[1] Volume average particle size (Mv)
The volume average particle size (Mv) of the polymer particles dispersed in the aqueous latex or resin composition was measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). A water-based latex diluted with deionized water and a resin composition diluted with methyl ethyl ketone were used as measurement samples. For measurement, the refractive index of water or methyl ethyl ketone and the refractive index of each polymer particle are input, the measurement time is 600 seconds, and the sample concentration is adjusted so that the Signal Level is within the range of 0.6 to 0.8. gone.

[2] Fabrication of Shear Adhesion Test Piece An aluminum alloy A2017P with a thickness of 4 mm was used as a substrate, and after polishing with abrasive paper with a grain size of 100, the substrate was degreased with an ultrasonic cleaner for 10 minutes with a cleaning liquid. An aluminum plate with a thickness of 1.0 mm and a Nitoflon (registered trademark, PTFE) tape with a thickness of 0.13 mm were used as spacers. As shown in FIG. 4, two aluminum plates 12 and 12' and two Nitoflon tapes 13 and 13' are placed as spacers between two substrates 11 and 11', and these are laminated, The formed space was filled with the adhesive composition 14 . After the adhesive composition was cured, the spacer was pulled out to obtain a test piece in which two substrates 11 and 11' were adhered by an adhesive layer 15 as shown in FIG.

[3] Shear adhesive fatigue test Using an electro-hydraulic servo type material testing machine (Shimadzu Corporation, Servo Pulser) as a testing machine, a sine wave vibration with a frequency of 5 Hz was applied to the test piece obtained above, and a maximum stress of 10 MPa was applied. , the number of vibrations until the test piece breaks was measured and defined as the breaking cycle number.

[4] Identification of fracture type after fatigue test Visually check the fracture surface of the test piece after the shear adhesive fatigue test, and if the adhesive remains on the metal substrate surface in an area of 40% or more of the fracture surface was evaluated as cohesive failure (CF) and less than 40% as interfacial failure (AF).

(Production Example 1) Preparation of rubber latex (Production Example 1-1) Preparation of acrylic rubber latex (R-1) Equipped with thermometer, stirrer, reflux condenser, nitrogen inlet, and addition device for monomer and emulsifier A glass reactor was charged with 180 parts by weight of deionized water, 0.002 parts by weight of disodium ethylenediaminetetraacetic acid (EDTA), 0.001 parts by weight of ferrous sulfate heptahydrate, and 0 parts by weight of sodium formaldehyde sulfoxylate (SFS). 0.04 part by weight and 0.5 part by weight of sodium dodecylbenzenesulfonate (SDBS) were charged, and the temperature was raised to 45° C. while stirring in a nitrogen stream. Next, a monomer mixture of 98 parts by weight of n-butyl acrylate (BA), 2 parts by weight of allyl methacrylate (ALMA) and 0.02 parts by weight of cumene hydroperoxide (CHP) was added dropwise over 5 hours. Along with the addition of the monomer mixture, 1 part by weight of SDBS in a 5% by weight aqueous solution was continuously added over 5 hours. Stirring was continued for 1 hour from the end of the addition of the monomer mixture to complete the polymerization, and an acrylic rubber latex (R-1) containing acrylic rubber particles was obtained. The volume average particle size of the acrylic rubber particles contained in the obtained latex was 100 nm.

(Production Example 1-2) Preparation of polybutadiene rubber latex (R-2) In a pressure-resistant polymerization machine, 200 parts by weight of water, 0.03 parts by weight of tripotassium phosphate, 0.002 parts by weight of EDTA, ferrous sulfate/7 0.001 parts by weight of a hydrated salt and 1.55 parts by weight of SDBS are charged, and the system is sufficiently purged with nitrogen while stirring to remove oxygen. The temperature was raised to 45°C. 0.03 parts by weight of paramenthane hydroperoxide (PHP) and then 0.10 parts by weight of SFS were added to initiate polymerization. After 3, 5 and 7 hours from the start of polymerization, 0.025 parts by weight of PHP was added. Further, 0.0006 parts by weight of EDTA and 0.003 parts by weight of ferrous sulfate heptahydrate were added after 4, 6 and 8 hours from the initiation of polymerization. After 15 hours from the start of the polymerization, the residual monomer was devolatilized and removed under reduced pressure to complete the polymerization to obtain a polybutadiene rubber latex (R-2) containing polybutadiene rubber particles. The volume average particle size of the polybutadiene rubber particles contained in the obtained latex was 80 nm.

(Production Example 1-3) Preparation of acrylic rubber latex (R-3) 0.35 parts by weight of allyl methacrylate (ALMA) and 0.07 parts by weight of stearyl acrylate (SMA) were added to 7 parts by weight of n-butyl acrylate (BA). , and 0.17 parts by weight of lauroyl peroxide (LPO) as an initiator was added and dissolved, and the temperature was adjusted to 30°C. Then, 0.13 parts by weight of SDBS was dissolved in 14 parts by weight of deionized water, and the temperature was adjusted. After being mixed with the solution, it was stirred for 10 minutes at a rate of 10000 rpm with a homomixer to obtain an emulsified monomer liquid.

173 parts by weight of deionized water, 0.3 parts by weight of SDBS, and 1% aqueous sodium nitrite solution were added to a glass reactor equipped with a thermometer, stirrer, reflux condenser, nitrogen inlet, and addition apparatus for monomers and emulsifiers. After adding 0.008 part by weight and adjusting the temperature to 30° C. in a nitrogen atmosphere, the emulsified monomer liquid obtained above was added. Thereafter, the temperature was raised to 65° C., and a monomer mixture of 83 parts by weight of BA and 4.15 parts by weight of ALMA was continuously added over 210 minutes. Along with the addition of the monomer mixture, 0.7 parts by weight of SDBS in a 5% strength by weight aqueous solution was continuously added over 210 minutes. Stirring was continued for 1 hour from the end of the addition of the monomer mixture to complete the polymerization, and an acrylic rubber latex (R-3) containing acrylic rubber particles was obtained. The volume average particle size of the acrylic rubber particles contained in the obtained latex was 3000 nm.

(Production Example 1-4) Preparation of acrylic rubber latex (R-4) 8.5 weight of BA was added to a glass reactor equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a device for adding monomers and emulsifiers. 0.17 parts by weight of ALMA, 0.16 parts by weight of SDBS, 0.003 parts by weight of CHP are added to 220 parts by weight of deionized water, and 0.0056 parts by weight of EDTA, and 0.0014 parts by weight of ferrous sulfate heptahydrate. and 0.06 parts by weight of SFS, the temperature is raised to 60° C., and a monomer mixture of 91.5 parts by weight of BA, 1.87 parts by weight of ALMA, and 0.03 parts by weight of CHP is continuously added over 350 minutes. added. After adding the monomer mixture, 0.15 parts by weight of SDBS was added four times at intervals of 60 minutes to obtain an acrylic rubber latex (R-4) containing acrylic rubber particles. The volume average particle size of the acrylic rubber particles contained in the obtained latex was 300 nm.

(Production Example 2) Preparation of core-shell polymer latex (Production Example 2-1) Preparation of core-shell polymer latex (L-1) Glass reaction with thermometer, stirrer, reflux condenser, nitrogen inlet, and monomer addition device 196 parts by weight of the acrylic rubber latex (R-1) (containing 70 parts by weight of acrylic rubber particles) and 65 parts by weight of water were charged in a vessel and stirred at 60°C while replacing with nitrogen. After adding 0.004 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS, 22.5 parts by weight of methyl methacrylate (MMA), glycidyl methacrylate (GMA)7. A mixture of 5 parts by weight and 0.08 parts by weight of t-butyl hydroperoxide (TBP) was added continuously over 110 minutes. 0.04 parts by weight of TBP was added, and stirring was continued for 1 hour to complete the polymerization, thereby obtaining an aqueous latex (L-1) containing core-shell polymer particles. The volume average particle size of the core-shell polymer particles contained in the obtained aqueous latex was 110 nm.

(Production Example 2-2) Preparation of core-shell polymer latex (L-2) The polybutadiene rubber latex (R- 2) 241 parts by weight (including 80 parts by weight of polybutadiene rubber particles) and 65 parts by weight of water were charged and stirred at 60°C while purging with nitrogen. After adding 0.004 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS, a mixture of 15 parts by weight of MMA, 5 parts by weight of GMA and 0.08 parts by weight of TBP was added for 110 minutes. was added continuously over a period of time. 0.04 part by weight of TBP was added, and stirring was continued for 1 hour to complete the polymerization, thereby obtaining an aqueous latex (L-2) containing core-shell polymer particles. The volume average particle size of the core-shell polymer particles contained in the obtained aqueous latex was 110 nm.

(Production Example 2-3) Preparation of core-shell polymer latex (L-3) The acrylic rubber latex (R- 3) After adding 308 parts by weight (including 90 parts by weight of acrylic rubber particles), 0.004 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS, 8 parts by weight of MMA parts, 2 parts by weight of GMA and 0.08 parts by weight of TBP were added continuously over 60 minutes. 0.04 part by weight of TBP was added, and stirring was continued for 30 minutes to complete the polymerization, thereby obtaining an aqueous latex (L-3) containing core-shell polymer particles. The volume average particle diameter of the core-shell polymer particles contained in the obtained aqueous latex was 3000 nm.

(Production Example 2-4) Preparation of core-shell polymer latex (L-4) The acrylic rubber latex (R- 4) 53.8 parts by weight (including 17.6 parts by weight of acrylic rubber particles), 0.0058 parts by weight of EDTA, 0.0014 parts by weight of ferrous sulfate heptahydrate, and 0.25 parts by weight of SFS were added. After that, 52.4 parts by weight of BA, 1.05 parts by weight of ALMA and 0.015 parts by weight of CHP were continuously added over 130 minutes. After 0.15 parts by weight of SDBS were added three times at intervals of 60 minutes, a mixture of 30 parts by weight of MMA and 0.08 parts by weight of TBP was added continuously over 180 minutes. 0.04 parts by weight of TBP was added, and stirring was continued for 30 minutes to complete the polymerization, thereby obtaining an aqueous latex (L-4) containing core-shell polymer particles. The volume average particle diameter of the core-shell polymer particles contained in the obtained aqueous latex was 500 nm.

(Production Example 3) Preparation of epoxy resin composition in which core-shell polymer particles (A) are dispersed as primary particles (Production Example 3-1) Preparation of core-shell polymer particles (A) dispersed epoxy resin composition (M-1) Preparation 126 parts by weight of methyl ethyl ketone (MEK) was charged into a 1 L mixing tank at 30° C., and 126 parts by weight of aqueous latex (L-1) of core-shell polymer particles was added while stirring. After uniformly mixing, 200 parts by weight of water was added at a feed rate of 80 parts by weight/minute. After the supply was completed, the stirring was promptly stopped to obtain a slurry containing floating aggregates. Next, 350 parts by weight of the liquid phase was discharged from the discharge port at the bottom of the tank, leaving the aggregates. 150 parts by weight of MEK was added to the resulting aggregates and mixed to obtain an MEK dispersion in which core-shell polymer particles were dispersed. To this MEK dispersion, a 1:1 mixture of bisphenol A-type diglycidyl ether (DGEBA, manufactured by Mitsubishi Chemical) jER828 and jER1001, which are epoxy resins, was added so that the weight ratio of the core-shell polymer particles and the epoxy resin mixture was 25:75. and MEK was distilled off under reduced pressure to obtain an epoxy resin composition (M-1) in which the core-shell polymer particles (A) were dispersed as primary particles.

(Production Example 3-2) Preparation of Core-Shell Polymer Particles (A) Dispersed Epoxy Resin Composition (M-2) An aqueous latex of core-shell polymer particles (L-1) is added to an aqueous latex of core-shell polymer particles (L-2). An epoxy resin composition (M-2) in which the core-shell polymer particles (A) were dispersed as primary particles was obtained in the same manner as in Production Example 1 except for the change.

(Production Example 4) Preparation of epoxy resin composition in which polymer particles (B) are dispersed as primary particles (Production Example 4-1) Preparation of polymer particle (B)-dispersed epoxy resin composition (N-1) Core shell An epoxy resin composition in which the polymer particles (B) are dispersed as primary particles in the same manner as in Production Example 1, except that the aqueous latex (L-1) of the polymer particles is changed to the aqueous latex (L-3) of the core-shell polymer particles. A product (N-1) was obtained.

(Production Example 4-2) Polymer Particle (B) Preparation of Epoxy Resin Composition (N-2) The aqueous latex of core-shell polymer particles (L-1) was changed to the aqueous latex of core-shell polymer particles (L-4). An epoxy resin composition (N-2) in which the polymer particles (B) were dispersed as primary particles was obtained in the same manner as in Production Example 1 except for the above.

(Examples 1-5 and Comparative Examples 1-5)
The epoxy resin, the core-shell polymer particles (A) dispersed epoxy resin composition, the polymer particles (B) dispersed epoxy resin composition, and the curing agent are rotated according to the compounding amounts described in the "mixing ratio" column of Table 1. - Mixed with a revolution mixer (manufactured by Thinky Corporation) to obtain an adhesive composition. In addition, a compounding quantity is a basis of weight. Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) was used to confirm that the core-shell polymer particles (A) and polymer particles (B) were dispersed as primary particles in the resulting adhesive composition.

The blending amounts of the epoxy resin, core-shell polymer particles (A), and polymer particles (B) with respect to 100 parts by weight of each adhesive composition are as shown in Table 1, "Composition" column. Table 1 shows the results of the number of rupture cycles and the type of failure measured or specified by performing fatigue tests using each adhesive composition.

Details of each raw material shown in Table 1 are as follows.
Epoxy resin: bisphenol A type epoxy resin (jER828 and jER1001, manufactured by Mitsubishi Chemical Corporation).
Core-shell polymer particle (A) dispersion epoxy resin composition: described in Production Example 3.
Polymer Particle (B) Dispersed Epoxy Resin Composition: Described in Production Example 4.
Curing agent: Diaminodiphenylsulfone (DDS) (SumiCure S, manufactured by Sumitomo Chemical Co., Ltd.)

In Examples 1 to 5, both the core-shell polymer particles (A) and the polymer particles (B) are dispersed as primary particles at an appropriate blending ratio in the epoxy resin composition, and the number of rupture cycles in the fatigue test is In many cases, the fatigue resistance was greatly improved, and the failure mode at the time of fatigue failure was cohesive failure (CF), indicating that an adhesive composition with high reliability was obtained. This is thought to be because, as shown in FIG. 3, the core-shell polymer particles (A) increase the toughness of the adhesive layer, and the polymer particles (B) can induce cracks in the adhesive layer at the time of fatigue fracture. be done.

Comparative Example 1 is an epoxy resin composition containing neither core-shell polymer particles (A) nor polymer particles (B). Comparative Examples 2 and 3 are epoxy resin compositions in which the core-shell polymer particles (A) are dispersed. but does not contain the polymer particles (B). In Comparative Examples 2 and 3, compared with Comparative Example 1, the number of fracture cycles in the fatigue test was not improved. This is presumably because, as shown in FIG. 1, the resistance to propagating cracks in the adhesive layer was high, and interfacial failure was induced.

Further, Comparative Example 4 is an epoxy resin composition in which the polymer particles (B) are dispersed without containing the core-shell polymer particles (A), and Comparative Example 5 is an epoxy resin composition containing both the core-shell polymer particles (A) and the polymer particles (B). is dispersed, but the epoxy resin composition has a high mixing ratio of the polymer particles (B) to the core-shell polymer particles (A). In these comparative examples, the failure mode at fatigue failure was cohesive failure (CF), but the number of fracture cycles in the fatigue test was not improved. This is probably because the core-shell polymer particles (A) were not included or the blending ratio thereof was small, so that the toughness of the adhesive layer was not improved.

(Examples 6 and 7 and Comparative Examples 6 and 7)
Along with the compounding amount described in the "mixing ratio" column of Table 2, the epoxy resin, the core-shell polymer particles (A) dispersed epoxy resin composition, the polymer particles (B), and the curing agent are mixed in a rotation/revolution mixer (( (manufactured by Thinky Co., Ltd.) to obtain an adhesive composition. In addition, a compounding quantity is a basis of weight. Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) was used to confirm that the core-shell polymer particles (A) and polymer particles (B) were dispersed as primary particles in the resulting adhesive composition.

The blending amounts of the epoxy resin, core-shell polymer particles (A), and polymer particles (B) with respect to 100 parts by weight of each adhesive composition are as shown in Table 2, "Composition". Table 2 shows the results of the number of rupture cycles and the type of failure measured or specified by performing fatigue tests using each adhesive composition.

The details of each raw material shown in Table 2 are the same as the details of each raw material shown in Table 1, except for those shown below.
Polymer particles (B):
N-3: Polypropylene spherical particles, PPW-5 (volume average particle size 5 μm, (manufactured by Seishin Enterprise Co., Ltd.)
N-4: Polytetrafluoroethylene spherical particles, Rubron L-5 (volume average particle size 5 μm, manufactured by Daikin)
N-5: Polytetrafluoroethylene spherical particles, lubricant L169J (volume average particle size 17 μm, manufactured by Asahi Glass Co., Ltd.)

In Examples 6 and 7, the materials constituting the polymer particles (B) were changed, respectively. Both are dispersed as primary particles, the number of fracture cycles in the fatigue test is large, the fatigue resistance is greatly improved, and the failure mode at the time of fatigue failure is cohesive failure (CF), making it a highly reliable adhesive. It can be seen that a composition was obtained. On the other hand, Comparative Example 6 is an epoxy resin composition using polymer particles (B) having a large volume average particle size of 17 μm, and Comparative Example 7 is the blending ratio of the polymer particles (B) to the core-shell polymer particles (A). is a low epoxy resin composition. In these comparative examples, the number of fracture cycles in the fatigue test was not improved, and the fracture mode during fatigue fracture was interfacial fracture (AF).

11 11' base material 12 12' spacer (aluminum plate)
13 13' Spacer (Nitoflon tape)
14 adhesive composition 15 adhesive layer

Claims (6)

adhesive resin,
Core-shell polymer particles (A) having a volume average particle size of 10 to 300 nm, and polymer particles (B) having a volume average particle size of 400 nm to 10000 nm,
The shell layer of the core-shell polymer particles (A) is composed of a polymer of shell layer-forming monomers containing 5 to 30% by weight of a monomer having a reactive group,
When the polymer particles (B) are polyolefin particles, polysiloxane particles, fluorine-containing resin particles, or core-shell polymer particles, and the polymer particles (B) are core-shell polymer particles, the polymer constituting the shell layer of the core-shell polymer particles The content of the monomer unit having a reactive group contained in is 0 to 5 parts by weight with respect to 100 parts by weight of the polymer particles (B),
The weight ratio of core-shell polymer particles (A): polymer particles (B) is 1:2 to 2:1,
An adhesive composition comprising core-shell polymer particles (A) and polymer particles (B) dispersed as primary particles in the adhesive composition. 2. The adhesive composition according to claim 1, wherein the polymer particles (B) are polymer particles having no hollow structure. 3. The adhesive composition according to claim 1, wherein the polymer particles (B) are core-shell polymer particles. The core layer of the core-shell polymer particles (A) or the core layer of the polymer particles (B),
(i) 50% by weight or more of one or more monomers selected from the group consisting of diene-based monomers and (meth)acrylic acid ester-based monomers, and 50 other copolymerizable vinyl monomers A rubber elastic body composed of less than % by weight,
(ii) a polysiloxane rubber-based elastic body,
(iii) an aromatic vinyl crosslinked product, or (iv) a mixture of two or more of the above (i) to (iii),
The other copolymerizable vinyl monomer is at least one selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds, unsaturated carboxylic acid derivatives, (meth)acrylic acid amide derivatives, and maleimide derivatives. The adhesive composition according to any one of claims 1 to 3, which is The adhesive composition according to any one of claims 1 to 4 , wherein the reactive group contained in the shell layer of the core-shell polymer particles (A) comprises an epoxy group. The adhesive composition according to any one of claims 1 to 5 , wherein the adhesive resin comprises an epoxy resin.

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