WO2019189238A1

WO2019189238A1 - Adhesive composition

Info

Publication number: WO2019189238A1
Application number: PCT/JP2019/012966
Authority: WO
Inventors: 秀輔吉原; 岸　肇; 松田　聡
Original assignee: 株式会社カネカ
Priority date: 2018-03-28
Filing date: 2019-03-26
Publication date: 2019-10-03
Also published as: JPWO2019189238A1; JP7184874B2

Abstract

An adhesive composition which contains an adhesive resin, core-shell polymer particles (A) that have a volume average particle diameter of 10-300 nm, and polymer particles (B) that have a volume average particle diameter of 400-10,000 nm, and which is configured such that the weight ratio of the core-shell polymer particles (A) to the polymer particles (B) is from 1:2 to 2:1, and the core-shell polymer particles (A) and the polymer particles (B) are dispersed in the adhesive composition in the form of primary particles, respectively.

Description

Adhesive composition

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

In recent years, structural adhesives have been used in various fields. For example, in the automobile field, a method of strengthening the joining of structural members has been attempted as a technique for achieving both weight reduction and rigidity improvement of a vehicle body, and as one of the joining methods, joining by using an adhesive and spot welding in combination. The technology (weld bond method) is drawing attention. As an adhesive to be applied to the joining site, an epoxy resin-based thermosetting adhesive (structural adhesive) is widely used, and is cured by heating after spot welding.

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

These adhesives are required to have high fatigue resistance that can withstand long-term use, and the toughness of the adhesive is generally noted. As a method for improving the toughness of the adhesive, for example, as described in Patent Document 1, there is a method of adding polymer fine particles having a core-shell structure to an epoxy resin. However, when the toughness of the adhesive is improved, there is a problem that an interface fracture that peels off at the interface between the adhesive layer and the adherend during fatigue failure is induced, and as a result, it is difficult to improve fatigue resistance. As shown in FIG. 1, this is considered to be caused by the fact that a crack is induced and progresses at a relatively weak interface due to the improvement in the toughness of the adhesive.

There are two types of adhesive layer destruction: “cohesive failure” in which the inside of the adhesive layer breaks and the above “interfacial failure”. In order to ensure that the adhesive layer 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. In view of the above, there is a demand for an adhesive that has high fatigue resistance and that undergoes cohesive failure during fatigue failure.

Patent Document 2 discloses a structural adhesive composition excellent in flowing water pressure resistance, which contains an epoxy resin, core-shell rubber particles in a dispersed form 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, it is necessary to mix the secondary aggregates of the core-shell type rubber particles with the primary particles. Therefore, it is difficult to control the particle size of the aggregates and the content of the aggregates, 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, and includes an epoxy resin, core-shell rubber particles, and a hollow polymer. This document does not describe fatigue resistance. In addition, when a hollow polymer is used, it is considered that the hollow polymer is destroyed by an impact received when the components are mixed and mixed, and it is difficult to disperse the hollow polymer as primary particles.

International Publication No. 2015/064561 JP2015-108077A JP 2010-270198 A

The present invention has been made in view of the above situation, and an object of the present invention is to provide an adhesive composition that is excellent in fatigue resistance and that undergoes cohesive failure at the time of fatigue failure.

As a result of intensive studies, the present inventors have determined that, in addition to the 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 at a specific ratio. By blending into 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 during fatigue failure As a result, the present inventors have found that a highly reliable adhesive composition that greatly improves fatigue resistance and undergoes cohesive failure at the time of fatigue failure can be obtained. That is, the present invention includes the following 1) to 7).

1) containing an adhesive resin, a core-shell polymer particle (A) having a volume average particle diameter of 10 to 300 nm, and a polymer particle (B) having a volume average particle diameter of 400 nm to 10000 nm; The weight ratio of (B) is 1: 2 to 2: 1, and each of the core-shell polymer particles (A) and the polymer particles (B) is 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 monomer and a (meth) acrylic acid ester monomer. A rubber elastic body composed of 50% by weight or more of at least one monomer and less than 50% by weight of another copolymerizable vinyl monomer, (ii) a polysiloxane rubber-based elastic body, (iii) Crosslinked aromatic vinyl, or (iv) a mixture of two or more of (i) to (iii) above, and the other copolymerizable vinyl monomer is an aromatic vinyl compound or a vinyl cyanide compound The adhesive composition according to any one of 1) to 3), which is at least one member selected from the group consisting of an unsaturated carboxylic acid derivative, a (meth) acrylic acid amide derivative, and a maleimide derivative.
5) The adhesive composition according to any one of 1) to 4), wherein the shell layer of the core-shell polymer particle (A) contains a reactive group.
6) The adhesive composition according to 5), wherein the reactive group includes 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 particle (B) is 0 to 5 parts by weight with respect to 100 parts by weight of the polymer particle (B). 3) The adhesive composition according to any one of 6) to 6).
8) The adhesive composition according to any one of 1) to 7), wherein the adhesive resin includes an epoxy resin.

According to the present invention, it is possible to provide an adhesive composition that is excellent in fatigue resistance and that undergoes cohesive failure at the time of fatigue failure.

For comparison, a conceptual diagram showing a state of interfacial fracture in which a crack occurs at the interface between the adhesive layer and the base material when an adhesive containing only the core-shell polymer particles (A) is used. For comparison, a conceptual diagram showing a state of cohesive failure in which cracks are generated inside the adhesive layer when an adhesive containing only polymer particles (B) having a large particle size is used. The conceptual diagram which shows the state of the cohesive failure which the crack produced inside the adhesive bond layer when using the adhesive agent which mix | blended the core-shell polymer particle (A) and the polymer particle (B) with a large particle size The side view which shows this test piece and spacer in the process of manufacturing the shearing-bonding test piece used by evaluation of an Example and a comparative example 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, a core-shell polymer particle (A) having a volume average particle diameter of 10 to 300 nm, and a polymer particle (B) having a volume average particle diameter of 400 nm to 10000 nm, The weight ratio of polymer particles (A): polymer particles (B) is 1: 2 to 2: 1, and the core-shell polymer particles (A) and the polymer particles (B) are dispersed as primary particles in the adhesive composition. It is characterized by being formed.

(Adhesive resin)
The adhesive resin which is a matrix resin in the adhesive composition of the present invention can be selected from various resins exhibiting adhesiveness regardless of thermoplasticity and curability, and is not particularly limited. Examples include vinyl acetate copolymer resin, polyolefin resin, polyamide resin, synthetic rubber, acrylic resin, polyurethane resin, etc. For curable resin, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, acrylic reaction Examples thereof include resins. From the viewpoints of adhesiveness, applicability, heat resistance, etc., an epoxy resin is preferable.

The epoxy resin may generally be a compound having two or more epoxy groups. For example, bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AD type, bisphenol Bifunctional glycidyl ether type such as epoxy compound having bisphenyl group such as AF type and biphenyl type, epoxy compound such as polyalkylene glycol type and alkylene glycol type, epoxy compound having naphthalene ring, epoxy compound having fluorene group Epoxy resin, phenol novolak type, orthocresol novolak type and other novolak type epoxy resin, polyfunctional glycidyl ether, tetraphenylol ethane type and other polyfunctional type glycidyl ether type epoxy resin, die -Glycidyl ester type epoxy resins of synthetic fatty acids such as acids, N, N, N ', N'-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N, Aromatic epoxy resins having a glycidylamino group such as N-diglycidylaniline, trishydroxyphenylmethane type epoxy resins, epoxy compounds having a tricyclodecane ring (for example, cresols such as dicyclopentadiene and m-cresol, or phenols) Epoxy compounds obtained by a production method in which epichlorohydrin is reacted after polymerizing the polymer), trishydroxyphenylmethane type epoxy resin, sorbitol type epoxy resin, polyglycerol type epoxy resin, glycidyl ester Ether type epoxy resins, heterocyclic epoxy resins, diaryl sulfone type epoxy resin, pentaerythritol type epoxy resin, trimethylol propane type epoxy resin and the like. An epoxy resin can be suitably selected according to the use etc. of an adhesive composition, and only 1 type may be used and it may be used in combination of 2 or more type. Bisphenol A-type epoxy resins and bisphenol F-type epoxy resins are particularly preferable in terms of facilitating the adjustment of the viscosity of the adhesive composition.

Bisphenol A type epoxy resin is a polycondensation compound of bisphenol A and epichlorohydrin. The bisphenol A skeleton enhances heat resistance and also improves toughness and tensile shear bond strength. Furthermore, the ether group in the skeleton improves chemical resistance, and the methylene chain increases flexibility. As this bisphenol A type epoxy resin, those ranging from liquid to solid can be used depending on the molecular weight, but those which are liquid to semi-solid at room temperature are preferred, and liquids are particularly preferred. This is because the handling property and the application workability of the composition become easy. The epoxy equivalent is preferably in the range of 180 to 300 g / eq. In addition, an epoxy equivalent means the gram number of the resin containing 1 gram equivalent of an epoxy group (unit: g / eq).

Furthermore, it is also possible to use a modified epoxy resin such as urethane-modified epoxy resin or dimer acid modification as the epoxy resin. As the urethane-modified epoxy resin, the structure is not particularly limited as long as it has a urethane bond and two or more epoxy groups in the molecule. From the point that it can be introduced into the molecule, a resin obtained by reacting a urethane bond-containing compound having an isocyanate group with a hydroxy group-containing epoxy compound is preferable. 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 the adhesive resin only needs to have an active group capable of reacting with an epoxy group. Examples of such curing agents include imidazole compounds such as dicyandiamide, 4,4′-diaminodiphenylsulfone, and 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 amine, polyamine, isophoronediamine, m-phenylenediamine, aminotriazole such as 3-amino-1,2,4-triazole, N-aminoethylpiperazine, melamines, acetog Guanamines such as anamin and benzoguanamine, guanidines, dimethylureas, boron trifluoride complex compounds, boron trichloride complex compounds, liquid phenols such as trisdimethylaminomethylphenol, polythiols, triphenylphosphine, ketimine compounds, sulfonium salts, Examples thereof include onium salts and phenol novolac resins. These may be used alone or in combination of two or more. Of these, dicyandiamide, 4,4′-diaminodiphenylsulfone, and isophoronediamine are preferable from the viewpoint of the adhesive strength of the composition.

When the curing agent is blended, the blending amount is preferably in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the adhesive resin. When the blending amount of the curing agent is 5 parts by weight or more, the curing rate of the adhesive composition is high, and the curing reaction proceeds sufficiently to improve physical properties such as adhesive strength. On the other hand, 30 parts by weight or less. When it is, it becomes easy to obtain the desired physical property requested | required of an adhesive composition. A preferable 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 compared to the polymer particles (B). By mix | blending this, the toughness of adhesive composition can be improved and the outstanding fatigue-resistant characteristic can be achieved.

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

In the present invention, the volume average particle size (Mv) of the core-shell polymer particles (A) is measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) while being dispersed in an aqueous latex or resin composition. Value. When measuring the volume average particle size of the particles in the aqueous latex, the aqueous latex is diluted with deionized water and the sample concentration is adjusted so that the Signal Level is in 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 time was 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 and the sample concentration is adjusted so that the signal level is in 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 time was 600 seconds. In addition, the description regarding the measurement of the above volume average particle diameter is applied also to the measurement of the volume average particle diameter of a polymer particle (B).

The core-shell polymer particle (A) is a core-shell polymer particle in which a shell layer is formed by graft polymerization of a graft copolymerizable monomer (a monomer for shell formation) to a crosslinked polymer to be a core layer, It has a structure having a core layer made of a cross-linked polymer existing inside and at least one shell layer covering the periphery or part of the cross-linked polymer by graft polymerization on the surface of the core layer. From the point that the viscosity of the adhesive composition of the present invention is kept low and easy to handle, the core-shell polymer particles are stably dispersed in the adhesive composition, and the toughening effect of the adhesive composition is enhanced. 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 the value of core layer / shell layer (weight ratio of monomers forming the polymer of each layer) / 40 to 95/5 is more preferable, and 70/30 to 90/10 is still more preferable.

The core layer is preferably composed of a crosslinked polymer and does not substantially dissolve in the solvent. Therefore, the gel content of the core layer is preferably 60% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, and particularly preferably 95% by weight or more.

The core layer comprises (i) 50% by weight or more of at least one monomer selected from the group consisting of diene monomers and (meth) acrylate monomers, and other copolymerizable vinyls. Rubber elastic body composed of less than 50% by weight of monomer, (ii) polysiloxane rubber-based elastic body, (iii) cross-linked aromatic vinyl, or (iv) two kinds of (i) to (iii) above It is preferable to consist of a mixture of the above. The other copolymerizable vinyl monomer is selected from the group consisting of an aromatic vinyl compound, a vinyl cyanide compound, an unsaturated carboxylic acid derivative, a (meth) acrylic acid amide derivative, and a maleimide derivative. It is preferable that it is a seed or more. In the present invention, (meth) acryl means acryl and / or methacryl.

Examples of the diene monomer include butadiene, isoprene, chloroprene and the like, and butadiene is particularly preferable. Examples of the (meth) acrylic acid ester monomer include butyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, and the like, and butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. 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 monomers and (meth) acrylic acid ester monomers is preferably 50% by weight or more based on the total weight of the core layer. Preferably it is 60 weight% or more. When the amount of the monomer used is less than 50% by weight, the toughening effect exhibited by the core-shell polymer particles may be reduced.

The core layer may be a homopolymer or a copolymer obtained by polymerizing one or more monomers selected from the group consisting of a diene monomer and a (meth) acrylic acid ester monomer. However, it may be a copolymer of a diene monomer and / or a (meth) acrylate monomer and a vinyl monomer copolymerizable therewith. As such a copolymerizable vinyl monomer, one kind 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 are mentioned. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, and vinyl naphthalene. Examples of the vinyl cyanide compound include (meth) acrylonitrile and substituted acrylonitrile. Examples of the unsaturated carboxylic acid derivative include (meth) acrylic acid, itaconic acid, crotonic acid, maleic anhydride and the like. Examples of the (meth) acrylamide derivative include (meth) acrylamide (including N-substituted product). Examples of the maleimide derivative include maleic imide (including N-substituted product). 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 cross-linked aromatic vinyl. Examples of the crosslinked body include a copolymer of an aromatic vinyl compound and a crosslinking monomer. Examples of the aromatic vinyl compound 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 dimethyl styrene, 2,5-dimethyl styrene, 3,5-dimethyl styrene, 2,4,6-trimethyl styrene; ring alkoxyl such as 4-methoxy styrene and 4-ethoxy styrene Vinyl aromatic compounds; ring halogenated aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; ring ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene; and rings such as 4-humanoxystyrene Examples include hydroxylated vinyl aromatics. An adhesive composition containing core-shell polymer particles using an aromatic vinyl cross-linked body in the core layer is preferable because it can be toughened without a decrease in rigidity.

When the core layer includes (i) a rubber elastic body or (iii) an aromatic vinyl crosslinked body, the polymer constituting the core layer is obtained by copolymerizing a crosslinking monomer in order to adjust the degree of crosslinking. Is preferred. Examples of the crosslinkable monomer include divinylbenzene, butanediol di (meth) acrylate, triallyl (iso) cyanurate, allyl (meth) acrylate, diallyl itaconate, diallyl phthalate, and the like. 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 be reduced.

The core layer may include a polysiloxane rubber-based elastic body. As the polysiloxane rubber-based elastic body, for example, a polysiloxane rubber composed of alkyl or aryl disubstituted silyloxy units such as dimethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy and the like can be used. In addition, the polysiloxane rubber-based elastic body may be crosslinked by using a polyfunctional alkoxysilane compound partly at the time of polymerization, or by radically reacting a silane compound having a vinyl reactive group, if necessary. What introduced the structure is more preferable.

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

The polymer constituting the shell layer in the core-shell polymer particle is a (meth) acrylic acid ester monomer, aromatic vinyl monomer, vinyl cyanide monomer, unsaturated carboxylic acid derivative, (meth) acrylamide derivative And (co) polymers 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 prevent the core-shell polymer particles (A) from reaggregating and deteriorating the dispersion state when the adhesive composition is cured. It preferably has 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 preferable. The shell layer having a reactive group is a (meth) acrylic acid ester monomer, an aromatic vinyl monomer, a vinyl cyanide 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 kinds of vinyl monomers having a reactive group as described above. Especially, it is preferable that the reactive group which the shell layer of a core shell polymer particle (A) has includes an epoxy group.

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

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

The production method of the core-shell polymer particles is not particularly limited, and can be produced by a known method such as emulsion polymerization, suspension polymerization, microsuspension polymerization, and the like. Among these, the production method by multistage emulsion polymerization is particularly preferable. Specific examples of emulsifying (dispersing) agents used in emulsion polymerization include alkyl or aryl sulfonic acids such as dioctyl sulfosuccinic acid and dodecylbenzene sulfonic acid, alkyl or aryl ether sulfonic acids, alkyl or aryl sulfuric acids such as dodecyl sulfuric acid, Alkyl or aryl ether sulfuric acid, alkyl or aryl substituted phosphoric acid, alkyl or aryl ether substituted phosphoric acid, N-alkyl or aryl sarcosine acid such as dodecyl sarcosine acid, alkyl or aryl carboxylic acid such as oleic acid or 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; Polyvinyl alcohol, Al Le substituted cellulose, polyvinyl pyrrolidone, dispersants such as polyacrylic acid derivatives. These can be used alone or in combination of two or more.

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

These emulsifying (dispersing) agents may be used as little as possible within the range that does not hinder the dispersion stability in the preparation process of the aqueous latex containing the core-shell polymer particles. Alternatively, in the process of producing the adhesive composition of the present invention, it may be extracted and removed to a residual amount that does not affect the physical properties of the produced adhesive composition. For this reason, it is more preferable that the emulsifying (dispersing) agent has water solubility.

In the adhesive composition of the present invention, the core-shell polymer particles (A) are dispersed in the form of primary particles. The 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 the particles measured in the adhesive composition exceeds 3, the adhesive composition contains a lot of secondary aggregates. As a result, the physical properties of the adhesive are not stable, for example, it is difficult to develop high fatigue resistance. In addition, the value of volume average particle diameter (Mv) / number average particle diameter (Mn) is the volume average of particles in the adhesive composition according to the above description using Microtrac UPA (manufactured by Nikkiso Co., Ltd.). The particle diameter (Mv) and the number average particle diameter (Mn) are measured, respectively, and the volume average particle diameter (Mv) is divided by the number average particle diameter (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 with respect to 100 parts by weight of the adhesive composition. More preferably, it is 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 toughening effect of the adhesive composition by the core-shell polymer particles (A) is reduced. At the time of fracture, cracks propagate at the interface between the adhesive layer and the substrate, and the fatigue resistance may be reduced.

(Polymer particles (B))
In the adhesive composition of this invention, the polymer particle (B) with a larger particle size is contained with a core-shell polymer particle (A) compared with this. The polymer particle (B) is a particle whose shape does not substantially change in the adhesive composition and after curing, and changes depending on the blending ratio and curing conditions, for example, an island part of a sea-island structure generated by polymer alloy. Such a formulation does not correspond to the polymer particles (B). The polymer particles (B) are preferably polymer particles that do not have a hollow structure (that is, polymer particles that do not have cavities containing liquid and / or gas inside the particles). When such polymer particles are used, the particles are not easily destroyed even when subjected to an impact when the components are blended and mixed, and it is easy to disperse as primary particles. By blending the polymer particles (B) as described above, control of the particle diameter and control of the content of the particles are facilitated, and the physical properties of the adhesive are stabilized.

By blending the polymer particles (B), peeling occurs at the interface between the matrix resin and the polymer particles (B) inside the adhesive layer as shown in FIG. 3 as compared with the interface between the adhesive layer and the substrate. Since it becomes easy, it becomes easy to induce a crack not in the interface of an adhesive bond layer and a base material but in an adhesive bond layer. As a result, cohesive failure is more likely to proceed than interface failure during fatigue failure. However, as shown in FIG. 2, the blending of only the polymer particles (B) has a low toughness of the adhesive layer and cannot achieve excellent fatigue resistance. By blending both the core-shell polymer particles (A) having a small particle size and the polymer particles (B) having a large particle size, an effect of synergistically improving the fatigue resistance can be achieved.

The volume average particle diameter of the polymer particles (B) is 400 nm to 10000 nm, more preferably 500 nm to 8000 nm, still 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, peeling at the interface between the matrix resin and the polymer particles is difficult to occur, so that the effect of inducing cracks in the adhesive layer is reduced. Moreover, when the volume average particle diameter of the polymer particles (B) is larger than 10000 nm, it is necessary to increase the content of the polymer particles (B) in order to induce cracks in the adhesive layer. Expression becomes difficult. The volume average particle diameter of the polymer particles (B) can be measured in the same manner as the volume average particle diameter of the core-shell polymer particles (A) described above.

The polymer particle (B) according to the present invention is a particle composed of a polymer because it is suitable for relieving repeated stress during long-term use. The shape of the particles is not particularly limited, and may be any shape such as a spherical shape or a flat plate shape. The type of polymer constituting the polymer particles (B) is not particularly limited, and examples thereof include rubbers, acrylic resins, polyolefins, polystyrenes, urethanes, polyesters, polyamides, polyimides, polysiloxanes, fluorine-containing resins, and core-shell polymers. It is done. The polymer particle (B) is a polyolefin, polysiloxane, fluorine-containing resin, or core-shell polymer particle because it is easy to design to ensure separation at the interface between the matrix resin and the polymer particle (B). preferable. Specific examples of the polyolefin include polyethylene and polypropylene, and specific examples of the fluorine-containing resin include polytetrafluoroethylene.

Details of the core-shell polymer particles, which is a preferred embodiment of the polymer particles (B), are the same as the details of the core-shell polymer particles (A), and thus description thereof is omitted. However, since it is preferable from the viewpoint of the effect of the invention that the polymer particles (B) are peeled from the matrix resin at the time of fatigue failure, in the core-shell polymer particles that are a preferred embodiment of the polymer particles (B), the shell layer is separated from the matrix resin. It is preferable that there is no reactive group that reacts, or the amount is small even if it has. Specifically, the content of the monomer unit having a reactive group contained in the polymer constituting the shell layer of the core-shell polymer particle is 0 to 5 parts by weight with respect to 100 parts by weight of the polymer particle (B). It is preferably 0 to 4 parts by weight, more preferably 0 to 3 parts by weight, and most preferably 0 to 2 parts by weight. 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 in the same manner as the core-shell polymer particles (A). As in the case of the core-shell polymer particles (A), the primary dispersion means that 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 following. 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, with respect to 100 parts by weight of the adhesive composition. The amount is more preferably 3 to 6 parts by weight, and 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 the addition of the polymer particles (B) is reduced. When the content is more than 10 parts by weight, the adhesive composition of the core-shell polymer particles (A) is used. The adhesive composition may become so brittle that the toughening effect of the product is not exhibited, and the fatigue resistance may be reduced.

In the adhesive composition of the present invention, the weight ratio of the core-shell polymer particles (A) to the polymer particles (B) is (A) :( B) = 1: 2 to 2: 1, and 2: 3 to 3: 2 is preferable, 4: 5 to 5: 4 is more preferable, and 1: 1 is further preferable. When the amount of the polymer particles (B) is relatively larger than 1: 2, the adhesive composition becomes brittle, and the fatigue resistance is lowered. 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 interface failure, and fatigue resistance characteristics are reduced. To do.

Although there are various methods for specifying the type of fracture after the fatigue test described above, in the present invention, the fracture surface of the test piece after the shear adhesion fatigue test is visually confirmed, and an area of 40% or more of the fracture surface The case where the adhesive remains on the surface of the metal substrate is evaluated as cohesive failure (CF), and the case where it is less than 40% is evaluated as interfacial failure (AF). As a method other than visual observation, the fatigue-breaked surface is observed with a reflection electron image of a scanning electron microscope, and each pixel of the obtained image is divided into monochrome 255 gradations to express the distribution of lightness. There is also a method of binarizing 0 to 218 as an adhesive and gradations from 219 to 255 as an adherend and calculating the ratio of the area where the adhesive layer remains.

(Optional component)
A thixotropic agent may be blended in the adhesive composition of the present invention in order to improve handling properties. Such a thixotropic agent is not particularly limited, and examples thereof include carbon black such as ketjen black, silica, fine calcium carbonate, sepiolite and the like. A thixotropic agent can be used 1 type or in combination of 2 or more types. When the 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 application workability and adhesive strength. As the thixotropic agent, it is preferable to use solid particles having an average particle diameter measured by a laser diffraction / scattering method within a range of 0.01 μm to 0.1 μm. If the average particle size is less than 0.01 μm, the viscosity of the adhesive composition may be increased and handling properties may be deteriorated. On the other hand, if the average particle size exceeds 0.1 μm, application workability and adhesive strength may be reduced. Because.

Further, the adhesive composition of the present invention can also be blended with a filler for adjusting the viscosity of the composition and improving mechanical properties to the extent that the effects of the present invention are not impaired. Such a filler is not particularly limited, for example, 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, diatomite, 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, calcined silica, precipitated silica, ground (fine powder) silica, etc. Silica, wax, quartz sand, sand Stovalite, cellulose, cement, calcium oxide, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, titanium dioxide, hollow ceramic beads, hollow inorganic beads such as hollow glass beads, hollow organic beads such as polyester resin, glass beads , Metal powders, bitumen substances and the like. These may be used alone or in combination of two or more. From the viewpoint of dispersibility and the like, calcium carbonate is preferred. When blending the filler, 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. When the filler is in the form of particles, the average particle diameter measured by a laser diffraction / scattering method is preferably in 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 be increased and the handleability may deteriorate, and if it exceeds 500 μm, the filler tends to settle and the uniformity of the composition may decrease. There is sex.

In the adhesive composition of the present invention, various additives such as a catalyst, a curing accelerator, a plasticizer, a reactive diluent, a reaction retarding agent, an antioxidant, an antioxidant, a pigment, Dyes, colorants, coupling agents, leveling agents, thixotropic agents, adhesion imparting agents, flame retardants, antistatic agents, conductivity imparting agents, lubricants, slidability imparting agents, UV absorbers, surfactants, A dispersant, a dispersion stabilizer, an antifoaming agent, a dehydrating agent, a crosslinking agent, a rust preventive 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 blended components with a known mixing and dispersing machine such as a planetary mixer, a disper, a Henschel mixer, a kneader and the like. Also, after preparing 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), respectively, the both mixtures are mixed to prepare the adhesive composition of the present invention. May be. 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, the core-shell polymer particles (A) and / or the polymer particles (B) are dispersed. This can be achieved by dissolving the adhesive resin and then distilling off the dispersion medium (or solvent) from the dispersion.

The adhesive composition of the present invention thus prepared is applied to an adherend by a known method such as spraying, gunning, brushing or the like. In addition, it is also possible to enhance the bondability of the adherend by using spot welding after application (weld bond method).

Since the adhesive composition of the present invention has high fatigue resistance and adhesion reliability, it can be used, for example, in automobiles, vehicles (bullet trains, trains), wind power generators, civil engineering, architecture, electronics, ships, aircraft, space industry, etc. It can be used as an adhesive for structural members. At this time, high joint strength to the structural part can be ensured by the combined use (weld bond method) such as spot welding using an electrode or the like. In addition, it can be used as an adhesive for general office work, medical use, and electronic materials.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, the thing made from Wako Purechemical was used if there is no special regulation.

The evaluation method used in the present invention will be described below.
[1] Volume average particle diameter (Mv)
The volume average particle diameter (Mv) of the polymer particles dispersed in the aqueous latex or resin composition was measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). The aqueous latex diluted with deionized water and the resin composition diluted with methyl ethyl ketone were used as measurement samples. For measurement, enter the refractive index of water or methyl ethyl ketone, and the refractive index of each polymer particle, and adjust the sample concentration so that the measurement time is 600 seconds and the Signal Level is in the range of 0.6 to 0.8. went.

[2] Preparation of Shear Adhesive Specimen A 4 mm thick aluminum alloy A2017P was used as a base material, which was polished with abrasive paper having a particle size of 100 and degreased with a cleaning liquid for 10 minutes using an ultrasonic cleaner. As the spacer, a 1.0 mm thick aluminum plate and a 0.13 mm thick nitoflon (registered trademark, PTFE) tape were used. As shown in FIG. 4, two

aluminum plates

12 and 12 ′ and two

nitroflon tapes

13 and 13 ′ are arranged as spacers between two

base materials

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 the two substrates 11 and 11 'were bonded together by the adhesive layer 15 as shown in FIG.

[3] Shear adhesion fatigue test Using an electrohydraulic servo type material tester (Shimadzu Corporation, Servo Pulser) as a tester, a sine wave vibration with a frequency of 5 Hz was applied to the test piece obtained above, and the maximum stress was 10 MPa. The frequency until the test piece broke was measured and used as the number of break cycles.

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

(Production Example 1) Preparation of rubber latex (Production Example 1-1) Preparation of acrylic rubber latex (R-1) A thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier addition device are included. In a glass reactor, 180 parts by weight of deionized water, 0.002 parts by weight of disodium ethylenediaminetetraacetate (EDTA), 0.001 part by weight of ferrous sulfate heptahydrate, sodium formaldehyde sulfoxylate (SFS) 0 .04 parts by weight and 0.5 parts 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 an aqueous solution having a concentration of 5% by weight was continuously added over 5 hours. Stirring was continued for 1 hour after completion of the monomer mixture addition to complete the polymerization, and an acrylic rubber latex (R-1) containing acrylic rubber particles was obtained. The volume average particle diameter 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 part by weight of tripotassium phosphate, 0.002 part by weight of EDTA, ferrous sulfate-7 After adding 0.001 part by weight of hydrated salt and 1.55 part by weight of SDBS, sufficiently purging with nitrogen and removing oxygen by stirring, 100 parts by weight of butadiene (Bd) was put into the system, The temperature was raised to 45 ° C. Polymerization was initiated by adding 0.03 part by weight of paramentane hydroperoxide (PHP), followed by 0.10 part by weight of SFS. 0.025 parts by weight of PHP was added after 3, 5, and 7 hours from the start of polymerization. In addition, 0.0006 part by weight of EDTA and 0.003 part by weight of ferrous sulfate heptahydrate were added after 4, 6 and 8 hours from the start of polymerization. After 15 hours from the start of polymerization, the residual monomer was removed by devolatilization under reduced pressure to complete the polymerization, and a polybutadiene rubber latex (R-2) containing polybutadiene rubber particles was obtained. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 80 nm.

(Production Example 1-3) Preparation of acrylic rubber latex (R-3) 7 parts by weight of n-butyl acrylate (BA) 0.35 parts by weight of allyl methacrylate (ALMA) and 0.07 parts by weight of stearyl acrylate (SMA) Then, 0.17 parts by weight of lauroyl peroxide (LPO) as an initiator was added and dissolved, the temperature was adjusted to 30 ° C., and then 0.13 parts by weight of SDBS was dissolved in 14 parts by weight of deionized water to adjust the temperature. After mixing with the solution, the mixture was stirred with a homomixer at a speed of 10,000 rpm for 10 minutes to obtain an emulsified monomer liquid.

In a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier addition device, 173 parts by weight of deionized water, 0.3 part by weight of SDBS, and 1% aqueous sodium nitrite solution After adding 0.008 part by weight and adjusting to 30 ° C. in a nitrogen atmosphere, the emulsified monomer solution obtained above was charged. 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 after completion of the monomer mixture addition to complete the polymerization, and an acrylic rubber latex (R-3) containing acrylic rubber particles was obtained. The volume average particle diameter of acrylic rubber particles contained in the obtained latex was 3000 nm.

(Production Example 1-4) Preparation of acrylic rubber latex (R-4) A glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and an apparatus for adding monomers and emulsifiers was charged with 8.5 wt. Parts, ALMA 0.17 parts, SDBS 0.16 parts, CHP 0.003 parts by weight in addition to 220 parts by weight of deionized water, 0.0056 parts by weight of EDTA, ferrous sulfate and heptahydrate 0.0014 parts by weight And 0.06 parts by weight of SFS, and then the temperature was 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 was continuously added over 350 minutes. Added. After the addition of 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 diameter 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 having thermometer, stirrer, reflux condenser, nitrogen inlet, and monomer addition device A vessel was charged with 196 parts by weight of the acrylic rubber latex (R-1) (including 70 parts by weight of acrylic rubber particles) and 65 parts by weight of water, and stirred at 60 ° C. while purging with nitrogen. After adding 0.004 part by weight of EDTA, 0.001 part by weight of ferrous sulfate heptahydrate and 0.2 part by weight of SFS, 22.5 parts by weight of methyl methacrylate (MMA) and 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 part by weight of TBP was added, and stirring was further continued for 1 hour to complete the polymerization to obtain 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-) was added to a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. 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 part by weight of EDTA, 0.001 part by weight of ferrous sulfate and heptahydrate, and 0.2 part by weight of SFS, a mixture of 15 parts by weight of MMA, 5 parts by weight of GMA and 0.08 part by weight of TBP is added for 110 minutes Over time. 0.04 part by weight of TBP was added, and stirring was further continued for 1 hour to complete the polymerization to obtain 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-) was added to a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. 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 part by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS, 8 parts by weight of MMA Part, 2 parts by weight of GMA and 0.08 parts by weight of TBP were continuously added over 60 minutes. 0.04 part by weight of TBP was added, and stirring was further continued for 30 minutes to complete the polymerization, thereby obtaining an aqueous latex (L-3) containing core-shell polymer particles. The volume average particle size 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-) was added to a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. 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. Thereafter, 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 was added three times at 60 minute intervals, a mixture of 30 parts by weight of MMA and 0.08 parts by weight of TBP was continuously added over 180 minutes. 0.04 part by weight of TBP was added, and stirring was further 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) Core-shell polymer particles (A) of dispersed epoxy resin composition (M-1) Preparation 126 parts by weight of methyl ethyl ketone (MEK) was charged in a 1 L mixing tank at 30 ° C., and 126 parts by weight of an aqueous latex (L-1) of core-shell polymer particles was charged with stirring. After mixing uniformly, 200 parts by weight of water was added at a feed rate of 80 parts by weight / min. After completion of the supply, the stirring was immediately stopped to obtain a slurry liquid containing floating aggregates. Next, the agglomerate was left, and 350 parts by weight of the liquid phase was discharged from the discharge port at the bottom of the tank. To the obtained aggregate, 150 parts by weight of MEK was added and mixed to obtain a MEK dispersion in which core-shell polymer particles were dispersed. In this MEK dispersion, a 1: 1 mixture of bisphenol A type diglycidyl ether (DGEBA, manufactured by Mitsubishi Chemical), which is an epoxy resin, jER828 and jER1001 is used so that the weight ratio of the core-shell polymer particles and the epoxy resin mixture is 25:75. Then, 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) The aqueous latex (L-1) of the core shell polymer particles was changed to the aqueous latex (L-2) of the core shell polymer particles. 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 Epoxy resin composition in which polymer particles (B) are dispersed as primary particles in the same manner as in Production Example 1 except that the aqueous latex of polymer particles (L-1) is changed to the aqueous latex of core-shell polymer particles (L-3) A product (N-1) was obtained.

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

(Examples 1 to 5 and Comparative Examples 1 to 5)
Rotate the epoxy resin, the core-shell polymer particle (A) -dispersed epoxy resin composition, the polymer particle (B) -dispersed epoxy resin composition, and the curing agent along the blending amounts described in the “mixing ratio” column of Table 1. -It mixed with the revolution mixer (made by Shinkey Co., Ltd.), and the adhesive composition was obtained. The blending amount is based on weight. It was confirmed by Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) that the core-shell polymer particles (A) and the polymer particles (B) were dispersed as primary particles in the obtained adhesive composition.

The compounding amounts of the epoxy resin, the core-shell polymer particles (A), and the polymer particles (B) with respect to 100 parts by weight of each adhesive composition are as described in the “Composition composition” column of Table 1. Table 1 shows the results of the number of fracture cycles and the type of fracture measured or specified by conducting a fatigue test using each adhesive composition.

The 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 particles (A) dispersed epoxy resin composition: described in Production Example 3.
Polymer particle (B) dispersed epoxy resin composition: described in Production Example 4.
Curing agent: Diaminodiphenyl sulfone (DDS) (SumiCure S, manufactured by Sumitomo Chemical Co., Ltd.)

In each of Examples 1 to 5, 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 fracture cycles in the fatigue test is In many cases, the fatigue resistance is greatly improved, and the failure mode at the time of fatigue failure is cohesive failure (CF), which indicates that an adhesive composition having high reliability was obtained. This is because, as shown in FIG. 3, the core-shell polymer particles (A) can make the adhesive layer tough, and the polymer particles (B) can induce cracks during fatigue failure in the adhesive layer. It is done.

Comparative Example 1 is an epoxy resin composition containing neither the core-shell polymer particles (A) nor the polymer particles (B). In Comparative Examples 2 and 3, the core-shell polymer particles (A) are dispersed in the epoxy resin composition. However, the polymer particles (B) are not included. In Comparative Examples 2 and 3, as compared with Comparative Example 1, the number of fracture cycles in the fatigue test was not improved, and the failure mode at the time of fatigue failure was interface failure (AF) as in Comparative Example 1. This is presumably because, as shown in FIG. 1, resistance was large for cracks to propagate in the adhesive layer, and interface fracture was induced.

Comparative Example 4 is an epoxy resin composition that does not contain core-shell polymer particles (A) and in which polymer particles (B) are dispersed, and Comparative Example 5 includes both core-shell polymer particles (A) and polymer particles (B). Is an epoxy resin composition having a high blending ratio of the polymer particles (B) to the core-shell polymer particles (A). In these comparative examples, the fracture mode at the time of fatigue fracture was cohesive fracture (CF), but the number of fracture cycles in the fatigue test was not improved. It is considered that the toughness of the adhesive layer was not improved because the core-shell polymer particles (A) were not included or the blending ratio was small.

(Examples 6 and 7 and Comparative Examples 6 and 7)
According to the blending amount described in the column of “Mixing ratio” in Table 2, the epoxy resin, the core-shell polymer particles (A) dispersed epoxy resin composition, the polymer particles (B), and the curing agent are rotated and revolved (( And an adhesive composition was obtained. The blending amount is based on weight. It was confirmed by Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.) that the core-shell polymer particles (A) and the polymer particles (B) were dispersed as primary particles in the obtained adhesive composition.

The compounding amounts of the epoxy resin, the core-shell polymer particles (A), and the polymer particles (B) with respect to 100 parts by weight of each adhesive composition are as described in the “Composition composition” column of Table 2. Table 2 shows the results of the number of fracture cycles and the type of fracture measured or specified by conducting a fatigue test 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 diameter 5 μm, manufactured by Seishin Enterprise Co., Ltd.)
N-4: Polytetrafluoroethylene spherical particles, Lubron L-5 (volume average particle diameter 5 μm, manufactured by Daikin)
N-5: Polytetrafluoroethylene spherical particles, Lubricant L169J (volume average particle diameter 17 μm, manufactured by Asahi Glass Co., Ltd.)

In Examples 6 to 7, the materials constituting the polymer particles (B) were changed, but in the epoxy resin composition, the core-shell polymer particles (A) and the polymer particles (B) were mixed at an appropriate blending ratio. Are dispersed as primary particles, have a large number of fracture cycles in fatigue tests, greatly improve fatigue resistance, and the fracture mode at the time of fatigue fracture is cohesive fracture (CF), which is 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 volume average particle diameter as large as 17 μm, and Comparative Example 7 is a blending ratio of polymer particles (B) to 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 at the time of fatigue fracture was also interface fracture (AF).

11 11 'Base material 12 12' Spacer (aluminum plate)
13 13 'Spacer (Nitoflon tape)
14 Adhesive composition 15 Adhesive layer

Claims

Adhesive resin,
A core-shell polymer particle (A) having a volume average particle diameter of 10 to 300 nm, and a polymer particle (B) having a volume average particle diameter of 400 nm to 10,000 nm,
The weight ratio of core-shell polymer particles (A): polymer particles (B) is 1: 2 to 2: 1,
Each of the core-shell polymer particles (A) and the polymer particles (B) is dispersed as primary particles in the adhesive composition.
The adhesive composition according to claim 1, wherein the polymer particles (B) are polymer particles having no hollow structure.
The adhesive composition according to claim 1 or 2, 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 at least one monomer selected from the group consisting of diene monomers and (meth) acrylic acid ester monomers, and other copolymerizable vinyl monomers 50 Rubber elastic body composed of less than wt%,
(Ii) a polysiloxane rubber-based elastic body,
(Iii) a cross-linked aromatic vinyl, or (iv) a mixture of two or more of (i) to (iii) above,
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, wherein
The adhesive composition according to any one of claims 1 to 4, wherein the shell layer of the core-shell polymer particles (A) contains a reactive group.
The adhesive composition according to claim 5, wherein the reactive group contains an epoxy group.
The content of the monomer unit having a reactive group contained in the polymer constituting the shell layer of the polymer particle (B) is 0 to 5 parts by weight with respect to 100 parts by weight of the polymer particle (B). Item 7. The adhesive composition according to any one of Items 3 to 6.
The adhesive composition according to any one of claims 1 to 7, wherein the adhesive resin contains an epoxy resin.