JPH06287410A - Structure-bonding epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition containing acrylic core/shell resin particles having a specific glass transition point, a phosphoric acid triester, an epoxy resin and a thermal activation-type curing agent, having excellent storage stability and bond strength and useful for the structural bonding of automobile, etc. CONSTITUTION:The objective resin composition is produced by compounding (A) resin particles obtained by the alkali treatment and saponification of polymer resin particles consisting of (i) a core component composed of a (meth) acrylate polymer having a glass transition point of <=-30 deg.C and (ii) a shell component composed of a polymer having a glass transition point of >=70 deg.C and produced by polymerizing a (meth)acrylate monomer or a monomer mixture composed mainly of the (meth)acrylate monomer and having the (core/shell) weight ratio of 10/1 to 1/4 with (B) an aliphatic and/or aromatic phosphoric acid triester having a molecular weight of 180-460 (e.g. tricresyl phosphate), (C) a bisphenol A or bisphenol F epoxy resin and (D) a thermal activation-type curing agent for epoxy resin (e.g. dicyandiamide).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel epoxy resin adhesive composition for structural adhesion of automobiles, and more particularly, to an ionically crosslinked acrylic reinforcing agent for imparting toughness and pseudo-curability. The present invention relates to an epoxy resin-based structural adhesive composition which is excellent in long-term storage stability and which is effective for a wide range of materials to be adhered, by incorporating a phosphoric acid ester-based modifier for obtaining good workability. It is a thing.

[0002]

2. Description of the Related Art Conventionally, since epoxy resins have various excellent properties, for example, adhesives, adhesive films, base resins, casting resins, powder molding resins, paints, electronic circuit sealing agents, Widely used for various applications such as base resin for composite materials. However, this epoxy resin has a drawback that its impact resistance is insufficient, and various improvements have been made so far. The method of improving the impact resistance can be roughly divided into a method of improving the chemical structure of the epoxy resin itself and a method of adding a separately prepared impact resistance improver to the epoxy resin, but the former method. By itself, an epoxy resin which can sufficiently satisfy the impact resistance cannot be obtained. on the other hand,
As the latter method, (1) a method of adding a soluble elastomer monomer to an uncured epoxy resin and simultaneously polymerizing the two, (2) a method of adding a compatible elastomer polymer, (3) fine particles There is known a method of dispersing a polymer for improving impact resistance in a shape. As for the method (1), n-butyl acrylate is mixed with SIPN (Simultaneous interface) in an epoxy resin.
As netrating networks),
A method for producing a rubber domain having a size of 1 to 0.2 μm has been attempted [see “Journal of Polymer Science Symposium (J Polymer Sci. S.
ymposium) ", Vol. 46, pp. 175-190 (1974)], this method generally has drawbacks such as a decrease in the softening point of the product and variations in mechanical strength. Regarding the method (2), various examples have been proposed in which an elastomer component such as a butadiene-acrylonitrile copolymer rubber having carboxyl groups and amino groups as terminal groups is added to modify the rubber, and some of them are put into practical use. However, the product obtained by this method is still not sufficiently satisfactory in terms of impact resistance and toughness for use as a structural adhesive. Regarding the method (3), many impact resistance improvers including polyamide resin-based ones have been proposed, but all of them have the drawback of insufficient pseudo-curability. By the way, it is generally known that when a rubber component having a glass transition temperature of −30 ° C. or less is added as an impact resistance improver for plastics, it acts to absorb external stress and the impact strength is significantly improved. ing. However, when many of such rubber components are mixed with a liquid epoxy resin as a matrix, the dispersibility thereof is easily affected by the mixing conditions, and the resulting composition has unstable storage properties, and thus has long-term storage properties. Is not practical as an adhesive that requires stability. Further, it is also important for the epoxy resin adhesive to have a pseudo-curing property, and in order to impart a pseudo-curing property to the epoxy resin while maintaining the impact resistance improving effect, the (meth) acrylate-based adhesive is used. It is known that a core-shell type modifier composed of a coalesced is effective (JP-A-2-
No. 80483). Pseudo-curability here refers to the property of solidifying to a non-adhesive or tacky state at a heating temperature lower than the temperature at which a liquid or paste adhesive is thermoset, and such pseudo-curability is as shown below. Have advantages.
That is, in the automobile industry, after applying a heat-curable adhesive composition based on an epoxy resin to a metal substrate, bending, cutting, degreasing cleaning, acid treatment and the like may be performed. However, there is a problem in that the work environment is deteriorated due to the dropping or scattering of the adhesive, or the removal of the excess adhesive protruding from the bonded portion, and the pretreatment liquid for coating is easily contaminated due to the elution of the adhesive. On the other hand, after applying the adhesive to the base material, heating it in a short time to form a pseudo-cured product makes it easier to remove the excess adhesive from the base material and also to prevent contamination of the pretreatment liquid. The problem of can be solved. However, since the pseudo-curable and impact resistance imparting agent particles using the (meth) acrylate resin as described above have high compatibility with the epoxy resin which is a medium of the adhesive composition, storage before heat curing is performed. In many cases, a remarkable increase in viscosity occurs, making it impossible to coat. In this case, the storage stability can be improved by cross-linking the (meth) acrylate layer serving as the shell component, but the original purpose is to lower the impact resistance, which is a contradictory result. Further, conventionally, an ion-crosslinked polymer is widely known as a so-called ionomer (trade name). This ionomer utilizes thermoreversible ionic cross-linking, which is a heat resistance, which is a drawback of polymers with a two-dimensional structure.
The ionic cross-linking structure improves mechanical properties such as solvent resistance or creep resistance at high temperatures, and moreover,
It is characterized by maintaining processability as a thermoplastic polymer, unlike ordinary three-dimensionally cross-linked polymers by covalent bonds. Ion-crosslinked polymers have been developed for a wide range of applications by utilizing this characteristic. On the other hand, in the processing technology for heat-curable adhesives, resin fine particles such as an impact resistance improver may be suspended and dispersed in a plasticizer, a liquid monomer, or a liquid polymer. In this case, these dispersions are applied or shaped before heating and then reacted by heat treatment to cure the medium and the resin fine particles into an integral substance. In view of mechanical properties, it is preferable that the compatibility parameter values of the substances of both the dispersion medium and the resin particles are close to each other. However, if such compatibility parameter values are used, the polymer particles are likely to swell due to the medium substance during storage of the resin fine particles as a dispersion, the viscosity of the entire dispersion is changed, and the storage stability thereof is improved. Is deteriorated, which hinders shaping operation and coating operation before heating, resulting in an unfavorable situation. By the way, in manufacturing an automobile, a predetermined mounting component is incorporated into a frame of the automobile, and then an outer plate of the body is attached. Generally, the attachment of the outer plate is simplified by spot welding instead of linear welding between the outer plate and a required portion of the frame, and by adhering the spots with an adhesive. ing. Also, many automobiles are manufactured by a monocoque body method in which a frame is eliminated and the body itself can withstand an external force. In this case, an adhesive is used between the spots in the joining between the units as in the above. As the adhesive used for such structural adhesion, cold rolled steel, which is a metal material for automobile manufacturing, hot rolled steel,
Furthermore, it must be capable of adhering an aluminum plate or the like with a large adhesive force. That is, for various kinds of materials to be adhered made of the above metal materials,
It must always exhibit a T-shaped peel strength of 0 kgf / 25 mm or more. Further, since the steel plate is generally coated with rust preventive oil for rust prevention, it must have a large adhesive force also to the oil surface. Conventional structural adhesives have not shown stable and high adhesive strength to such various adherend materials.

[0003]

Under the circumstances, the present invention provides an adhesive composition in which acrylate or methacrylate polymer resin fine particles are dispersed in an epoxy resin uncured medium having a close compatibility parameter, To provide an epoxy resin-based structural adhesive composition which prevents the resin fine particles from swelling by a medium, is excellent in storage stability for a long period of time, and has high adhesive strength to a wide range of adherend materials. It was done for the purpose.

[0004]

Means for Solving the Problems As a result of intensive studies to develop an epoxy resin-based adhesive composition having the above-mentioned preferable properties, the present inventors have found that the ionic crosslinked structure is a crosslinked structure but is thermoplastic. Paying attention to the unique phenomenon of maintaining, the core-shell type acrylate or methacrylate copolymer resin particles are saponified by alkali treatment to introduce a carboxy group into the polymer of the particle surface or a layer near the surface, and at the same time metal ions. The presence of the ion-crosslinking makes it possible to prevent the swelling phenomenon of the particles due to the epoxy resin medium, and the epoxy resin-based adhesive composition containing the resin particles having the ion-crosslinking structure has a long-term storage stability. Of excellent heat resistance and good mechanical strength of thermoset, and addition of specific additives to it More, the present invention has been completed based on this finding found that a large bond strength equal for a wide range of automotive structural material is obtained.

That is, in the present invention, (A) (a) a core component composed of an acrylate or methacrylate polymer having a glass transition point of -30 ° C. or lower and (b) an acrylate or methacrylate monomer alone or as a main component. And a shell component composed of a polymer having a glass transition point of 70 ° C. or higher obtained by polymerizing a monomer mixture as a component, and a core component / shell component weight ratio of 10/1 to 1/4. Derived from resin powder particles obtained by saponifying polymer resin particles in a range by alkali treatment, (B) aliphatic and / or aromatic phosphate triester having a molecular weight of 180 to 460, (C) bisphenol A or bisphenol F An epoxy resin-based structural adhesive composition comprising an epoxy resin and (D) a heat-activatable curing agent for an epoxy resin as essential components. That. Hereinafter, the present invention will be described in detail. In the composition of the present invention, the resin powder particles used as the component (A) are obtained by saponifying core-shell type acrylate or methacrylate copolymer resin particles by alkali treatment and ionically crosslinking them. In the production of the resin powder particles of the component (A), first, a rubber-like seed polymer made of an acrylate or methacrylate polymer having a glass transition temperature (Tg) of −30 ° C. or lower, which is the core component (a), is prepared. . Examples of the (meth) acrylate-based monomer that gives a polymer having a Tg of −30 ° C. or lower include ethyl acrylate, propyl acrylate, n-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate and the like. These may be used alone or in combination of two or more.

If desired, a crosslinkable monomer may be added to the above (meth) acrylate-based monomer to further enhance the rubber property. As a crosslinkable monomer for this,
Having two or more double bonds with substantially equal reactivity, such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate,
Aroma such as trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, hexanediol diacrylate, hexanediol methacrylate, oligoethylene diacrylate, oligoethylene dimethacrylate, and divinylbenzene. Group divinyl monomers, triallyl trimellitate, triallyl isocyanurate and the like can be used. These crosslinkable monomers may be used alone in the range where the Tg of the obtained polymer is −30 ° C. or lower, or may be used in combination of two or more kinds.
The amount used is usually 0.01-based on the total weight of the monomers.
It is selected in the range of 5% by weight, preferably 0.1 to 2% by weight. In addition to the (meth) acrylate-based monomer and the crosslinkable monomer, other copolymerizable monomers can be used if desired. As the other copolymerizable monomer used as desired, for example, styrene, vinyltoluene, aromatic vinyl compounds such as α-methylstyrene, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, Furthermore, vinylidene cyanide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxybutyl acrylate, 2-hydroxyethyl fumarate, hydroxybutyl vinyl ether, monobutyl maleate, glycidyl methacrylate, butoxyethyl methacrylate and the like can be mentioned. To be These may be used alone or in combination of two or more, and the amount to be used needs to be selected within the range where the Tg of the obtained polymer is -30 ° C or less, but usually a single amount is used. It is selected in the range of 50% by weight or less based on the total body weight.

Next, the (meth) acrylate polymer particles thus obtained are used as a core, and a monomer mixture containing a (meth) acrylate monomer alone or as a main component is graft-polymerized, (B) The second-stage emulsion polymerization for forming a shell made of a copolymer having a glass transition temperature of 70 ° C. or higher is performed. Examples of the raw material (meth) acrylate-based monomer used at this time include ethyl acrylate, n-butyl acrylate, methyl methacrylate,
Carbon number of alkyl group such as butyl methacrylate is 1 to
The (meth) acrylate of 4 may be used, and these may be used alone or in combination of two or more, and among these, methyl methacrylate is particularly preferable. At this time, a crosslinkable monomer may be added if desired. As the crosslinkable monomer, one kind or two or more kinds can be selected and used from those exemplified in the description of the (meth) acrylate polymer forming the core. The amount of the crosslinkable monomer used is usually 0.01 to 10% by weight, preferably 0.1 to 5%, based on the total weight of the monomers.
It is selected in the range of weight%. Furthermore, if desired, other monomers copolymerizable with the (meth) acrylate-based monomer and the crosslinkable monomer can be used. As the other copolymerizable monomer used as desired, one or two or more kinds selected from those exemplified in the description of the (meth) acrylate polymer forming the core may be used. it can. The amount used is based on the total weight of the monomers,
Usually, it is selected within the range of 50% by weight or less.

The transition temperature of the (meth) acrylate copolymer forming the shell is required to be 70 ° C. or higher, and if it is lower than 70 ° C., the storage stability is low when mixed with an epoxy resin to form an adhesive composition. Is insufficient, the polymer has a high heat fusion property, and may cause a nozzle clogging during spray drying. Latex containing a core-shell type polymer obtained by such a multi-stage emulsion polymerization,
Usually by direct spray drying with an inert gas,
A core-shell type powdery polymer having excellent dispersibility in an epoxy resin can be obtained. This core-shell type powdery polymer can be obtained by the multistage seed emulsion polymerization method of at least two stages as described above. In some cases, the seed latex prepared in the first stage is partially aggregated, and then the seed latex is formed thereon. It may be prepared by graft polymerization, and further, after emulsion polymerization, latex particles are coagulated and separated by a salt folding method or a freezing method, and a wet cake prepared by dehydration is dried in a fluidized bed or the like to obtain agglomerated particles. It can also be obtained as a form. In the present invention, the weight ratio of the core component / shell component needs to be in the range of 10/1 to 1/4. If the weight ratio deviates from the above range, the object of the present invention cannot be sufficiently achieved. Next, the core-shell type particles thus obtained are treated with alkali to saponify the ester portion of the (meth) acrylate of the shell layer. The alkali treatment method is carried out by adding an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide or sodium carbonate to an aqueous solution of a salt such as a carbonate, a nitric oxide or a salt of an alkaline earth metal such as barium hydroxide. Dip core shell particles, temperature 70-1
Leave at 00 ° C for 5 minutes to 10 hours. By this treatment, the ester of the (meth) acrylate monomer unit of the shell layer of the core-shell particles is saponified and a carboxyl group is introduced on the surface of the polymer particles. The above treatment may be performed on the latex after polymerization. The reason why the alkali metal or alkaline earth metal salt is used as the saponifying agent is that ionic crosslinks can be formed between the carboxyl groups on the surface of the produced polymer particles through a metal cation. Of course, the ester may be saponified with a strong acid such as sulfuric acid, and then a monovalent or divalent metal salt may be added to form ionic crosslinks. However, alkali treatment is preferred because it proceeds to ionic crosslinks in a single reaction. Further, even if the structure of the ionic crosslinked product is used, the above-mentioned pseudo-curability is not deteriorated.

The presence of this ionic cross-link can be easily analyzed by measuring the absorption of the carboxylate group by infrared absorption spectrum, quantifying the metal ion, and measuring the degree of swelling in a solvent. The dissociation property of ionic crosslinks can be confirmed by differential thermal analysis, and the density can be confirmed by measuring the degree of swelling. The ionic cross-linked product of the component (A) thus obtained differs from a cross-linked structure of a covalent bond such as a sulfur cross-link or a peroxide cross-link, because the formation of the cross-linked structure changes reversibly thermo-reversibly. The surface of the modified resin particles exhibits a property of a crosslinked structure at room temperature, while it exhibits a property of a structure in which the crosslinks are dissociated under the molding condition of heat curing, and as a result, the composition of the present invention is storage stable. And the mechanical strength of the molded product. That is, in the present invention, the cation as a cross-linking agent forms an ionic cross-link between the carboxyl groups introduced by alkali saponification in the shell part of the resin particle to form a three-dimensional polymer structure formed in the shell part of the resin particle. Swelling property at room temperature by the epoxy resin medium is reduced, and the heat-cured product of the base polymer and the dispersion medium does not impair the original physical properties and the storage stability of the composition is improved. . Further, in order to reduce the swelling property of the resin particles, the object can be achieved by providing an ionic crosslinked structure in at least the polymer of the shell portion, but if desired, the core portion of the resin particles may also be Providing an ionic crosslinked structure by copolymerizing a carboxyl group-containing monomer can also be appropriately adopted depending on the physical properties of the molded product. The core-shell type resin particles used as the component (A) in the composition of the present invention can be produced by, for example, an emulsion polymerization method, a fine suspension polymerization method or a suspension polymerization method. Further, in order to effectively modify the surface of fine particles having a size of about 0.1 to 5 μm by graft polymerization, particles obtained by mainly emulsion polymerization method or fine suspension polymerization method are aggregated, As described above, it is effective to polymerize the required monomers, then spray-dry or coagulate and dehydrate-dry, and then saponify the particles with an alkali to ionically crosslink the particles.

In the composition of the present invention, the fatty acid and / or aromatic phosphate triester having a molecular weight of 180 to 460 used as the component (B) is, for example, tricresyl phosphate or tri-2-ethylhexyl phosphate. , Tributyl phosphate, triphenyl phosphate, trixylyl phosphate, cresyl diphenyl phosphate, tributoxyethyl phosphate, triethyl phosphate, diphenyl-2
-Methacryloyloxyethyl phosphate, octyldiphenyl phosphate, dioctyl-2-methacryloyloxyethyl phosphate, trisdichloropropyl phosphate, trisdichloroethyl phosphate, etc., among which tricresyl phosphate is particularly preferred. Fates are preferred. These phosphate triesters may be used alone or in combination of two or more, and the addition amount thereof is usually 1 to 30 parts by weight with respect to 100 parts by weight of the epoxy resin as the component (C). Parts, preferably 5 to 20 parts by weight. Bisphenol A used as the component (C) in the composition of the present invention
Examples of epoxy resins derived from

[0011]

[Chemical 1]

Examples of epoxy resins derived from bisphenol F include those represented by the general formula

[0013]

[Chemical 2]

Examples include those represented by: Although n in these general formulas is a number of 0 or more, those having an average value of less than 1 are suitable because they are liquid at room temperature. Further, an epoxy resin derived from a compound obtained by adding 2 to 20 mol of ethylene oxide or propylene oxide to bisphenol A can also be used. In the composition of the present invention, the heat-activatable curing agent for epoxy resin used as the component (D) is, for example, dicyandiamide, 4,4′-diaminodiphenylsulfone,
Imidazole derivatives such as 2-n-heptadecyl imidazole, isophthalic acid dihydrazide, N, N-dialkylurea derivatives, N, N-dialkylthiourea derivatives,
Examples thereof include acid anhydrides such as tetrahydrophthalic anhydride, isophoronediamine, m-phenylenediamine, N-aminoethylpiperazine, melamine, guanamine, boron trifluoride complex compounds, and trisdimethylaminomethylphenol. These are one kind. They may be used, or two or more kinds may be used in combination, and among these, dicyandiamide is particularly preferable. The compounding amount of the heat-activatable curing agent as the component (D) is not particularly limited, but is usually 3 to 100 parts by weight of the epoxy resin as the component (C).
The ratio is 30 parts by weight, preferably 5 to 20 parts by weight.
If this amount is less than 3 parts by weight, curing failure will occur, causing a significant decrease in each adhesive strength, and if it exceeds 30 parts by weight, partial decomposition or thermal deterioration will occur due to excessive exothermic reaction during molding. As a result, each adhesive strength is significantly reduced or discolored. The epoxy resin-based adhesive composition of the present invention,
(C) Epoxy resin, (A) component ionically crosslinked resin powder particles, (B) component phosphate triester, (D) component heat-activatable curing agent, and optional components used as desired. Can be prepared by blending and homogeneously mixing. Examples of the additive component to be added to the adhesive composition as desired include, for example, plasticizers, diluents, stabilizers, emulsifiers, fillers, reinforcing agents, colorants, foaming agents, antioxidants, and UV inhibitors. Lubricants and the like can be mentioned. The epoxy resin-based adhesive composition of the present invention is particularly used as a structural adhesive for automobiles, and is used for bonding a wide range of materials to be bonded, such as cold rolled steel, hot rolled steel, cold rolled stainless steel, and aluminum. It is preferably used.

[0015]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The physical properties of the composition were evaluated by the methods described below. (1) Initial viscosity After the adhesive composition is allowed to stand at 25 ° C. for 1 hour, it is measured with a Brookfield (BH) type rotational viscometer [manufactured by Tokyo Keiki Co., Ltd.] using a rotor NO7 and a descending method. . Measure viscosity at 20 rpm for 60, 80 and 100 seconds, then 10 rp
Similarly, m is measured three times, and thereafter, the viscosity is similarly measured at 5 rpm and 2.5 rpm. The initial viscosity is the average of the three values at 2.5 rpm. (2) Viscosity storage stability After standing at 40 ° C. for 10 days, the viscosity was measured with a Brookfield H-type viscometer. It was evaluated by the value obtained by dividing the viscosity by the initial viscosity. (3) Pseudo-curability It was heated at 105 ° C. for 10 minutes to cause gelation, peeling removability was determined, and evaluation was performed according to the following criteria. ◯: The gelled adhesive composition could be easily peeled off Δ: The gelled adhesive composition was weak in strength and was torn at the removal stage x: Those which were not pseudo-cured by heating at 105 ° C. for 10 minutes (4) T-shaped peeling strength According to JIS K-6854, it was carried out using a test piece of 0.8 × 25 × 20 cm. (5) Tensile shear strength According to JIS K-6850. Examples 1 to 4, Comparative Examples 1 to 8 Using 49 parts by weight of n-butyl acrylate and 1 part by weight of 2-ethylhexyl acrylate, 1 part by weight of sodium alkyl sulfate having 12 to 18 carbon atoms as an emulsifier, potassium persulfate. 0.1 part by weight of catalyst was added and 15 parts of water were added.
The emulsion polymerization was carried out in 0 part by weight at a polymerization temperature of 70 ° C. for 180 minutes with stirring. Then, using the latex obtained by this polymerization as a seed, graft polymerization was carried out with 50 parts by weight of methyl methacrylate to produce a polymer for an acrylic reinforcing agent. The latex obtained after polymerization was heated at an inlet hot air temperature of 16
Spray drying was performed under the conditions of 0 ° C. and the outlet gas temperature of 55 ° C. to obtain an acrylic reinforcing agent. The obtained acrylic reinforcing agent powder was dispersed in water in which 5 parts by weight of sodium hydroxide was dissolved so as to be 30% by weight, and then mixed at 90 ° C. for 5 hours. Then, it was dehydrated, washed, and dried by a hot air circulation dryer at 45 ° C. Next, 200 parts by weight of an epoxy resin (Epicoat 828, manufactured by Shell Yuka Epoxy Co., Ltd.), 16 parts by weight of a latent curing agent (dicyandiamide), 100 parts by weight of the reinforcing agent and 15 parts by weight of a plasticizer were used as a basic composition. Blending is done with a planetary mixer with vacuum degassing, and it is applied to a steel plate of a specified size as a sample for T-shaped peel test, and 180 ° C.
Was cured by heating for 30 minutes to prepare a sample. The steel plate is a cold rolled steel plate (JIS G 3141 SPCC). The evaluation results of each physical property are shown in Table 1.

[0016]

[Table 1]

[0017]

[Table 2]

Note 1) The polymer concentration was adjusted to 30 wt% with respect to water, and saponification was carried out at each temperature for 5 hours while stirring. 2) A value obtained by dividing the viscosity of the adhesive when stored at 40 ° C. for 10 days by the initial viscosity. 3) Peeling removability after gelation when heated at 105 ° C. for 10 minutes.

[0019]

The epoxy resin-based adhesive composition of the present invention imparts toughness and pseudo-hardening property, and therefore, it is necessary to obtain good workability with an acrylic reinforcing agent whose particle surface is ionically cross-linked by alkali treatment. It contains a phosphoric acid ester-based modifier, is excellent in long-term storage stability, has high adhesive strength, and is suitably used as a structural adhesive for automobiles.

Claims (1)

[Claims] 1. A core component comprising (A) (a) an acrylate or methacrylate polymer having a glass transition point of -30 ° C. or lower, and (b) a single component containing an acrylate or methacrylate monomer alone or as a main component. A polymer having a glass transition point of 70 ° C. or higher obtained by polymerizing a monomer mixture, and a core component / shell component weight ratio of 10/1 to 1/4. Resin powder particles obtained by saponifying combined resin particles by alkali treatment, (B) aliphatic and / or aromatic phosphoric acid triester having a molecular weight of 180 to 460, (C) epoxy resin derived from bisphenol A or bisphenol F, and (D) An epoxy resin-based structural adhesive composition containing a heat-activatable curing agent for epoxy resin as an essential component.