Composition

Abstract

To satisfy both pot life and adhesion.SOLUTION: A composition containing (1) a (meth) acrylic monomer, (2) an elastomer having no (meth) acrylic group and having a carbon-carbon double bond structure in a proportion of 10% or more and 90% or less, (3) an organic peroxide, and (4) an organic compound containing cobalt, in which an amount of the component (2) is 20 parts by mass or less with respect to 100 parts by mass of a total of the component (1) and the component (2), and a number of carbon atoms in one molecule of the component (4) is 12 or more and 19 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition, particularly to a curable composition that exhibits long handling time and excellent metal adhesion. [Background technology]

[0002] Second-generation acrylic adhesive compositions (SGA), which are two-component acrylic adhesive compositions, are known as adhesives that cure at room temperature. SGAs are generally two-component adhesives consisting of a first component containing an organic peroxide and a second component containing a reducing agent that decomposes the organic peroxide contained in the first component and generates radicals, with both the first and second components containing main components such as polymerizable (meth)acrylic monomers and elastomers.

[0003] Two-component SGAs have the following characteristics: they can exhibit excellent adhesive properties without precisely mixing the first and second components, and they can adhere to oily surfaces. Various proposals have been made regarding such SGAs, as described in Patent Documents 1 to 5. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-160861 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-156426 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-206574 [Patent Document 4] Japanese Patent Application Publication No. 2017-075279 [Patent Document 5] Japanese Patent Application Publication No. 06-080937 Summary of the Invention [Problem to be solved by the invention]

[0005] However, prior art SGAs have not been able to solve the problem of a trade-off between metal adhesion and curing speed. For example, Patent Document 1 discloses a composition capable of bonding metals to porous materials such as concrete, paper, or cloth, which contains a (meth)acrylic acid ester monomer, cobalt soap, and a nitrogen-containing compound. This composition exhibits adhesion to porous materials due to the action of cobalt ions. However, given the current standards required as technology advances, it is believed that there is still room for improvement in the metal adhesion of this prior art.

[0006] Patent Document 2 discloses an adhesive composition containing a polymerizable vinyl monomer, a curing agent, a thiourea derivative, and an elastomer component, which has adhesive properties on oily surfaces. The adhesive strength of this composition depends on the polymerization reaction of the thiourea derivative. Therefore, compared to currently required standards, this prior art still has room for improvement in terms of achieving both usable time and adhesive strength.

[0007] Patent Documents 3 and 4 disclose two-component adhesives containing an elastomer such as chlorosulfonated polyethylene, a polymerizable monomer having a (meth)acryloyl group, an organic peroxide, nitrile butadiene rubber, an amine-based activator, and a copper-based compound or an organometallic compound. However, these adhesives derive their adhesive strength from the action of the amine-based activator, such as toluidine, which acts as a curing accelerator, and therefore cannot solve the problem of poor storage stability. Furthermore, the usable life is not sufficiently long compared to current standards, and attempts to extend the usable life result in a decrease in adhesive strength.

[0008] Patent Document 5 discloses a base-primer type acrylic adhesive comprising a base composed primarily of a polymerizable (meth)acrylic monomer and an organic peroxide, and a primer composed primarily of a reducing agent that forms a redox catalyst system with the organic peroxide in the base, wherein the primer is composed primarily of a condensate of an aldehyde and an amine and a soluble vanadium compound, and at least one of the base or primer contains one or more acidic compounds selected from acidic phosphorus compounds, organic carboxylic acids, and organic sulfonic acids. However, this adhesive also fails to solve the problem of an insufficiently long pot life in light of current standards, and requires a primer, which makes its use complicated. [Means for solving the problem]

[0009] The present inventors have conceived the present invention, which can solve the above problems. That is, the present invention can provide the following aspects.

[0010] Aspect 1. (1) a (meth)acrylic monomer; (2) an elastomer having no (meth)acrylic group and having a carbon-carbon double bond structure in a proportion of 10% to 90%; (3) an organic peroxide; (4) Cobalt-containing organic compounds A composition comprising: The amount of component (2) is 20 parts by mass or less, based on 100 parts by mass of the total of components (1) and (2), (4) The number of carbon atoms in one molecule of the component is 12 to 19. A composition characterized by:

[0011] Aspect 2. (2) The composition according to embodiment 1, wherein the carbon-carbon double bond structure of the component includes a butadiene structure.

[0012] Aspect 3. (4) The composition of any one of the preceding aspects, wherein the component comprises cobalt 2-ethylhexanoate.

[0013] Aspect 4. The composition of any one of Aspects 1 to 3, characterized in that the composition has a pot life of 100 minutes or more as measured by Method 5 "Determination by exothermic reaction temperature" as defined in JIS K 6870:2008, a tensile shear adhesive strength after 24 hours to iron-iron bonds of 10 MPa or more as measured by the method defined in JIS K 6850:1999, and the failure state is cohesive failure, and the surface of the cured product is non-tacky as determined by the Ballochny method as defined in JIS K 5600-3-2:1999.

[0014] Aspect 5. The composition according to any one of Aspects 1 to 4, which is a two-part composition, wherein a first part contains at least (3) an organic peroxide, and a second part contains at least (4) an organic compound containing cobalt.

[0015] Aspect 6. An adhesive composition comprising the composition according to any one of aspects 1 to 5.

[0016] Aspect 7. A bonded article obtained by bonding adherends using the adhesive composition according to embodiment 6.

[0017] Aspect 8. A bonding method comprising bonding adherends using the adhesive composition according to embodiment 6. [Effects of the Invention]

[0018] The composition provided by the embodiment of the present invention has the effect of ensuring sufficient usable time (also referred to as pot life or open time), while also providing excellent adhesion and metal adhesion. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. In this specification, "parts" and "%" are based on mass unless otherwise specified. Numerical ranges in this specification include upper and lower limit values ​​unless otherwise specified. In this specification, the "amount used" and "content" of a component refer to the amount based on the entire composition unless otherwise specified.

[0020] As used herein, the term "monofunctional (meth)acrylate" refers to a (meth)acrylate having one (meth)acryloyl group (sometimes referred to as a (meth)acrylic group) and the term "polyfunctional (meth)acrylate" refers to a (meth)acrylate having two or more (meth)acryloyl groups.

[0021] A preferred composition that can provide an embodiment of the present invention is a curable composition. The curable composition (hereinafter sometimes simply referred to as "composition") contains (1) a (meth)acrylic monomer, (2) an elastomer that has no (meth)acrylic groups and has carbon-carbon double bond structures in a proportion of 10% to 90%, (3) an organic peroxide, and (4) an organic compound containing cobalt.

[0022] The (1) (meth)acrylic monomer has the function of dissolving other components of the composition. Component (1) is preferably one or more monomers selected from (meth)acrylates and hydroxyalkyl (meth)acrylates having a hydrocarbon group. Such hydrocarbon groups are preferably unsubstituted or substituted hydrocarbon groups having 1 to 32 carbon atoms. The hydrocarbon groups may be linear, branched, or alicyclic aliphatic groups, aromatic groups, or combinations thereof. From the viewpoint of achieving sufficient solubility of other components, component (1) preferably contains one or more (meth)acrylates or hydroxyalkyl (meth)acrylates having an aliphatic group.

[0023] Component (1) may be a monofunctional (meth)acrylate, a polyfunctional (meth)acrylate, or a mixture thereof.

[0024] Examples of the monofunctional (1) component having a linear or branched aliphatic group include alkyl(meth)acrylates and hydroxyalkyl(meth)acrylates. Further examples of monofunctional (meth)acrylates include 2-hydroxyethyl(meth)acryloylphosphate, 4-butylhydroxy(meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, glycerin di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and caprolactone-modified 2-hydroxyethyl(meth)acrylate.

[0025] The alkyl(meth)acrylate is preferably a (meth)acrylate represented by the following formula (1). Formula (1) Z1-OR 11 (wherein Z1 represents a (meth)acryloyl group, and R 11 represents an alkyl group.

[0026] Examples of the (meth)acrylate represented by formula (1) include methyl (meth)acrylate, ethyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate (including 2-ethylhexyl (meth)acrylate), nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicodecyl (meth)acrylate.

[0027] R 11 represents an alkyl group. 11 is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms.

[0028] The alkyl group of the alkyl (meth)acrylate is preferably an unsubstituted, non-alicyclic, non-aromatic, and non-substituent alkyl group.

[0029] Among alkyl (meth)acrylates, it is preferable to use methyl (meth)acrylate and octyl (meth)acrylate in combination. When methyl (meth)acrylate and octyl (meth)acrylate are used in combination, the composition ratio by mass of methyl (meth)acrylate:octyl (meth)acrylate is preferably 50-99:1-50, more preferably 60-90:10-40, and most preferably 70-80:20-30.

[0030] The hydroxyalkyl (meth)acrylate is preferably a (meth)acrylate represented by the following formula (2). Formula (2) Z2-O-(R 12 O) p -H (wherein Z2 represents a (meth)acryloyl group, and R 12 represents an alkylene group, and p represents an integer of 1 to 10.

[0031] Examples of the (meth)acrylate represented by formula (2) include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0032] R 12 represents an alkylene group. 12 is -C2H4-, -C3H6-, -CH2CH(CH3)-, -C4H8- or -C6H 12p is preferably an integer of 1 to 10, and more preferably an integer of 1 to 4.

[0033] The hydroxyalkyl group of the hydroxyalkyl (meth)acrylate is preferably a hydroxyalkyl group that is unsubstituted, is not alicyclic, does not have an aromatic group, and does not have a substituent other than a hydroxy group.

[0034] Among monofunctional (meth)acrylates, it is preferable to use an alkyl (meth)acrylate and a hydroxyalkyl (meth)acrylate in combination. When an alkyl (meth)acrylate and a hydroxyalkyl (meth)acrylate are used in combination, the composition ratio by mass of alkyl (meth)acrylate:hydroxyalkyl (meth)acrylate is preferably 1-99:1-99, more preferably 50-95:5-50, and most preferably 70-90:10-30.

[0035] Among the components (1), a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate may be used in combination. When a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate are used in combination, the composition ratio by mass of the monofunctional (meth)acrylate:polyfunctional (meth)acrylate is preferably 50-99:1-50, more preferably 70-90:10-30, and most preferably 75-85:15-25.

[0036] Examples of monofunctional (meth)acrylates having an alicyclic aliphatic group or an aromatic group include adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, 1-(1-adamantyl)-1-methylethyl (meth)acrylate, benzyl (meth)acrylate, methylbenzyl (meth)acrylate, ethylbenzyl (meth)acrylate, propylbenzyl (meth)acrylate, and methoxybenzyl (meth)acrylate. Examples of the acrylate include benzyl (meth)acrylate, chlorobenzyl (meth)acrylate, 2,2-bis(4-(meth)acryloxyphenyl)propane, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypropoxyphenyl)propane, 2,2-bis(4-(meth)acryloxytetraethoxyphenyl)propane, and 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane.

[0037] Examples of polyfunctional (meth)acrylates include alkyl di(meth)acrylates, alkyl tri(meth)acrylates, and alkyl tetra(meth)acrylates having a linear, branched, or alicyclic aliphatic or aromatic group, and preferably, di(meth)acrylates having a bisphenol A skeleton can be used. Examples of di(meth)acrylates having a bisphenol A skeleton include (poly)ethoxy-modified bisphenol A di(meth)acrylates and (poly)propoxy-modified bisphenol A di(meth)acrylates, and one or more of these can be used. Among these, (poly)ethoxy-modified bisphenol A di(meth)acrylates are preferred. Among (poly)ethoxy-modified bisphenol A di(meth)acrylates, compounds represented by the following formula (3) are preferred. In the formula, m+n (i.e., ethoxy equivalent) is preferably 1 to 40, more preferably 3 to 20, most preferably 5 to 15, and even more preferably 10. In the formula, R 1 and R 2 may each independently be a hydrogen atom or a CH3 group.

[0038] [ka] (m and n are positive numbers)

[0039] Among the (1) (meth)acrylic monomers, monofunctional (meth)acrylates are preferred from the viewpoint of ensuring usable life. The proportion of the monofunctional (meth)acrylate is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, most preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and even more preferably 100 parts by mass, per 100 parts by mass of component (1).

[0040] Among the (1) (meth)acrylic monomers, polyfunctional (meth)acrylates are preferred from the viewpoint of adhesion. The proportion of the polyfunctional (meth)acrylate is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and most preferably 20 parts by mass or less, per 100 parts by mass of the (1) component. The proportion of the polyfunctional (meth)acrylate is preferably 1 part by mass or more, per 100 parts by mass of the (1) component.

[0041] The amount of component (1) used is preferably 80 parts by mass or more but less than 100 parts by mass, and more preferably 80 parts by mass or more but less than 99 parts by mass, where the total of components (1) and (2) is 100 parts by mass. If component (1) is less than 80 parts by mass, the viscosity of the composition becomes too high, making it difficult to produce a uniform composition. Furthermore, if component (2) is not included, there is a problem that sufficient tensile shear strength cannot be obtained.

[0042] (2) The elastomer, which does not have a (meth)acrylic group and has carbon-carbon double bond structures in a proportion of 10% to 90%, serves to impart tensile shear strength to the composition. In this specification, the term "elastomer" refers to a polymeric substance that has rubber-like elasticity at room temperature, and is preferably one that can be dissolved or dispersed in a polymerizable monomer.

[0043] If the proportion of carbon-carbon double bond structures in component (2) is 10% or more, curability can be improved, and if it is 90% or less, tensile shear strength and curability can be improved, and sufficient metal adhesion can be obtained. If the proportion of carbon-carbon double bond structures exceeds 90%, radicals generated in the system are consumed by the oxidation of the double bonds, which is thought to result in poor curing at the cured surface of the composition that comes into contact with air and at the interface with the adherend. More preferably, the proportion of carbon-carbon double bond structures in component (2) may be 20% to 80%, and even more preferably 30% to 80%. The carbon-carbon double bond structures in component (2) preferably include a butadiene structure.

[0044] The proportion of carbon-carbon double bond structures in component (2) can be determined by well-known techniques, such as Fourier transform infrared spectroscopy (FT-IR) or by calculating the iodine value by titration.

[0045] Component (2) has no (meth)acrylic groups, which allows for excellent curing properties. This is because component (2) undergoes phase separation with the (meth)acrylic monomer during the polymerization reaction, forming an island-in-a-sea structure, which does not inhibit the reaction between the (meth)acrylic monomers.

[0046] Examples of component (2) include various synthetic rubbers such as butadiene polymer, styrene-butadiene rubber (SBR, hereinafter also referred to as high styrene rubber), and nitrile rubber (NBR), natural rubber, and various thermoplastic elastomers. Component (2) preferably contains NBR having a butadiene structure in a proportion of 10% to 90%. These elastomer components may be used alone or in combination as long as compatibility is not an issue. Of the components (2), nitrile rubber (NBR) is preferred.

[0047] The amount of component (2) used is 20 parts by mass or less when the total of components (1) and (2) is 100 parts by mass. If the amount of component (2) exceeds 20 parts by mass, the viscosity of the composition becomes too high, which can cause a problem of making it difficult to produce a uniform composition.

[0048] (3) Organic peroxides (also called peroxides) serve as thermal radical polymerization initiators with excellent reactivity. Examples of component (3) include cumene hydroperoxide, paramenthane hydroperoxide, and tertiary butyl hydroperoxide. Among these, cumene hydroperoxide is preferred in terms of reactivity.

[0049] The amount of component (3) used is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, when the total of components (1) and (2) is 100 parts by mass. When component (3) is 0.1 part by mass or more, the curing rate can be appropriately increased, and when it is 20 parts by mass or less, storage stability can be improved.

[0050] (4) The cobalt-containing organic compound functions as a reducing agent. The inventors discovered that by limiting the number of carbon atoms in one molecule of component (4) to 12 or more and 19 or less, the steric hindrance of the ligand can be reduced while preventing the ligand from becoming excessively bulky, allowing the ligand to bond firmly to the central metal, cobalt. This allows the rate of the cobalt redox reaction to be moderately limited, resulting in the remarkable effect of efficiently decomposing organic peroxides.

[0051] Furthermore, the above-mentioned effects are believed to be only obtainable when cobalt is used as the central metal. Other reducing agents (e.g., those with nickel, manganese, or vanadium as the central metal) do not provide the above-mentioned effects, even if the carbon number is within the above range. This is because cobalt has the highest electronegativity among the first transition metals, which have unpaired shared electron pairs in the 3d orbitals.

[0052] Examples of component (4) include, but are not limited to, cobalt octylate (also known as "cobalt bis(2-ethylhexanoate)cobalt(II)" or "cobalt 2-ethylhexanoate", 16 carbon atoms per molecule), salcomine (also known as "N,N'-ethylenebis(salicylideneiminato)cobalt(II)", 16 carbon atoms per molecule), tris(2,4-pentanedionato)cobalt(III) (also known as "acetylacetonate cobalt(III)", 15 carbon atoms per molecule), and cyclopentadienyl(dimethyl fumarate)(triethyl phosphite)cobalt(I) (17 carbon atoms per molecule).

[0053] The amount of component (4) is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total of components (1) and (2). If the amount of component (4) is within this range, the rate of the redox reaction of cobalt can be appropriately limited. More preferably, the amounts of components (3) and (4) can be equal.

[0054] In some embodiments, the composition may be in a two-part form, more preferably a first part containing at least component (3) and a second part containing at least component (4).

[0055] The composition according to one embodiment may further contain a monomer or polymer of an acid phosphooxyalkyl (meth)acrylate, preferably in an amount of 0.1 to 5 parts by mass, more preferably 1 to 3 parts by mass, relative to 100 parts by mass of the total of components (1) and (2). Such an acid phosphooxyalkyl (meth)acrylate is preferably a monomer or polymer of a compound having the following formula (4):

[0056] [ka] In the formula, A (when there are more than one, each A is independently) a hydrogen atom, an alkyl group (preferably a C1-C6 alkyl group, more preferably a methyl group), or an alkylhalo group (preferably a C1-C6 alkylhalo group, more preferably a chloro C1-C6 alkyl group, even more preferably a chloromethyl group). n is an integer of 1 to 6. k is an integer of 1 or 2. R 1 may be a hydrogen atom or a CH3 group.

[0057] In some embodiments, the composition of the present invention may further contain paraffins to accelerate curing of the portions of the composition exposed to air. The amount of paraffins is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the total of components (1) and (2), in terms of curability and adhesion. Examples of such paraffins include paraffin, microcrystalline wax, carnauba wax, beeswax, lanolin, spermaceti, ceresin, and candelilla wax. Of these, paraffin is preferred. The melting point of the paraffins is preferably 40 to 100°C.

[0058] The composition according to some embodiments may further contain a polymerization inhibitor to improve storage stability. From the viewpoints of storage stability and adhesion, the amount of the polymerization inhibitor is preferably 0.001 to 3 parts by weight, more preferably 0.01 to 1 part by weight, per 100 parts by weight of the total of components (1) and (2). Examples of such polymerization inhibitors include methylhydroquinone, hydroquinone, 2,2-methylene-bis(4-methyl-6-tert-butylphenol), catechol, hydroquinone monomethyl ether (methoquinone), monotert-butylhydroquinone, 2,5-ditert-butylhydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-ditert-butyl-p-benzoquinone, picric acid, citric acid, phenothiazine, tert-butylcatechol, 2-butyl-4-hydroxyanisole, and 2,6-ditert-butyl-p-cresol.

[0059] In one embodiment, an adhesive composition containing the above-described composition can be provided. In another embodiment, a bonded structure formed by bonding adherends using the adhesive composition, as well as a bonding method thereof, can be provided. When the adherend is a metal, the adhesive composition exhibits excellent adhesion. When the metal is iron or aluminum, the adhesive composition exhibits even better adhesion.

[0060] In a preferred embodiment, the present composition has a pot life (gelation time) measured by Method 5 "Determination by exothermic reaction temperature" specified in JIS K 6870:2008 of preferably 100 minutes or more, more preferably 200 minutes or more, and even more preferably 500 minutes or more. When measuring the pot life, it is preferable that the composition is not uncured. The pot life is preferably 1000 minutes or less, more preferably 800 minutes or less.

[0061] In a preferred embodiment, the composition has a tensile shear adhesive strength of 10 MPa or more, more preferably 15 MPa or more, and most preferably 20 MPa or more, after 24 hours, measured according to the method specified in JIS K 6850:1999, when bonded to iron. The tensile shear adhesive strength of 10 MPa or more, more preferably 11 MPa or more, and most preferably 12 MPa or more, after 24 hours, measured according to the method specified in JIS K 6850:1999, when bonded to aluminum. Generally, strong adhesive strength is obtained when cohesive failure occurs, so the failure state is preferably cohesive failure. More preferably, the tensile shear adhesive strength is 10 MPa or more and the failure state is cohesive failure. In this specification, the failure state is determined to be cohesive failure when the proportion of cohesive failure is 80% or more of the total adhesive area, and when it is less than 80%, the failure state is determined to be interfacial or surface failure.

[0062] In one embodiment, it is particularly preferable that all of the following conditions be satisfied in order to have excellent performance. The pot life measured by method 5 specified in JIS K 6870:2008 is 100 minutes or more. The tensile shear adhesive strength after 24 hours between steel specimens measured using the method specified in JIS K 6850:1999 is 10 MPa or more, and the failure state is cohesive failure. The tensile shear adhesive strength after 24 hours between aluminum sheets measured using the method specified in JIS K 6850:1999 is 10 MPa or more, and the failure state is cohesive failure. - Based on the Ballochni method specified in JIS K 5600-3-2:1999, there must be no stickiness after curing for 24 hours at room temperature.

[0063] In this specification, "room temperature" refers to the range defined in JIS Z 8703:1983, that is, 5 to 35°C. [Example]

[0064] The present invention will be described in detail below with reference to examples. Curable compositions were prepared using the following materials according to the formulations shown in the table below. The amounts of components in the table are shown in parts by mass. Unless otherwise specified, the experiments were carried out in an environment of 23°C and 50% Rh (relative humidity).

[0065] <Materials used> The following commercially available (meth)acrylate monomers were used as they were. Methyl methacrylate: Acryester M (Mitsubishi Chemical Holdings) 2-Hydroxyethyl methacrylate: HEMA (Nippon Shokubai) 2-Ethylhexyl methacrylate: Light Ester EH (Kyoeisha Chemical) Ethoxy 10 mole-modified bisphenol A dimethacrylate: M-2101 (manufactured by Miwon Specialty Chemical Co., Ltd., in formula (3), R 1 and R 2 is a CH3 group, and m+n=10.)

[0066] The following commercially available elastomers were used as they were (Bd% is the amount of butadiene): Acrylonitrile butadiene rubber: JSR N220SH (Bd% = 58.5%) (manufactured by JSR) Acrylonitrile butadiene rubber: JSR N250S (Bd% = 80.5%) (manufactured by JSR) High styrene rubber: JSR 0061 (Bd% = 34%) (manufactured by JSR) Methacrylate-modified acrylonitrile butadiene rubber: DN612P (Bd%=73%) (manufactured by ZEON) Polybutadiene-modified dimethacrylate: TE-2000 (Nippon Soda) Polybutadiene: LBR-305 (Kuraray) Chlorosulfonated polyethylene: TS-340 (Tosoh)

[0067] The organic peroxide used was cumene hydroperoxide: Percumyl H-80 (manufactured by NOF Corp.).

[0068] In addition, the following raw materials were used as they were. 2-Hydroxyethyl methacrylate acid phosphate: JPA-514 (manufactured by Johoku Chemical Industry Co., Ltd., R 1 is a CH3 group, A is a hydrogen atom, n is 1, and k is 1 or 2.) Paraffin wax: Paraffin Wax-145 (manufactured by Nippon Seiro, melting point 63°C) Hydroquinone (Seiko Chemical) Metoquinone: MQ (Kawaguchi Chemical Industry Co., Ltd.) Cobalt octylate: CO-12E (Tokyo Fine Chemical) Vanadyl acetylacetonate (manufactured by Shinko Chemical Industry) Nickel octylate: Nickel octylate (manufactured by Nippon Chemical Industry Co., Ltd.) Manganese octylate: Nikka octylate manganese (manufactured by Nippon Chemical Industry Co., Ltd.) Cobalt(II) acetylacetonate (Tokyo Chemical Industry Co., Ltd.) Cobalt naphthenate (Tokyo Chemical Industry Co., Ltd.) Ethylenethiourea (Tokyo Chemical Industry Co., Ltd.)

[0069] <Formulation> The above raw materials were weighed as shown in the table below and added to a 1 L stainless steel flask. A stainless steel stirring blade was placed in the flask, and the mixture was stirred at 200 rpm for 24 hours using a Three-One motor to obtain a uniform viscous liquid.

[0070] <Evaluation> The samples obtained as described above were evaluated based on the following measurement methods. Note that, when performing all evaluations, the components A and B were quickly mixed at a mass ratio of 1:1 until homogeneous before use.

[0071] Pot life: Measured according to Method 5 of JIS K 6870:2008, and the results are shown in the table below. The unit is min.

[0072] Adhesion to iron (1-day tensile shear strength (23°C, iron / iron)): The tensile shear adhesive strength after 24 hours between iron specimens (SPCC-SD, manufactured by Test Piece Co., Ltd.) was measured using a universal testing machine, Instron model 4467 (manufactured by Instron), according to the method specified in JIS K 6850:1999. The results are shown in the table below. The unit is MPa.

[0073] Adhesion to aluminum (1-day tensile shear strength (23°C, Al / Al)): The tensile shear adhesive strength after 24 hours between aluminum sheets (AL5052, manufactured by Test Piece Co., Ltd.) was measured according to the method specified in JIS K 6850:1999 using an Instron model 4467 universal testing machine (manufactured by Instron), and the results are shown in the table below. The unit is MPa.

[0074] Curability: Curability at room temperature was evaluated by the following method. 100 g / m2 was applied to iron (SPCC-SD, manufactured by Test Piece Co., Ltd.). 2The mixed sample was applied so that the viscosity was 100% and then left to cure for 24 hours in an environment of 23°C and 50% RH. After curing, the surface dryness of the resulting coating film was evaluated using the Ballotini method specified in JIS K 5600-3-2:1999, and curing was judged. A coating film with a dry surface was rated as not sticky and had sufficient curing, i.e., judged as ◯. A coating film that could not be removed by lightly brushing the Ballotini was rated as sticky and had insufficient curing, i.e., judged as ×. Similarly, a sample that remained liquid and had not cured was also judged to have insufficient curing.

[0075] If all of the following conditions are met, a circle is marked in the "Judgment" column of the table below. If one or more of the following conditions are not met, an "X" is marked in the "Judgment" column of the table below. The pot life measured by method 5 specified in JIS K 6870:2008 was 100 minutes or more. The tensile shear adhesive strength of the steel-to-steel bond measured by the method specified in JIS K 6850:1999 after 24 hours is 10 MPa or more and the failure state is cohesive failure. The tensile shear adhesive strength of aluminum to aluminum after 24 hours measured using the method specified in JIS K 6850:1999 is 10 MPa or more and the failure state is cohesive failure. - Based on the Ballochni method specified in JIS K 5600-3-2:1999, there was no stickiness after curing for 24 hours at room temperature.

[0076] [Table 1]

[0077] [Table 2]

[0078] [Table 3]

Claims

1. (1) a (meth)acrylic monomer; (2) an elastomer having no (meth)acrylic group and having a carbon-carbon double bond structure in a proportion of 10% to 90%; (3) an organic peroxide; (4) Cobalt-containing organic compounds A composition comprising: The amount of component (2) is 20 parts by mass or less, based on 100 parts by mass of the total of component (1) and component (2), (4) The number of carbon atoms in one molecule of the component is 12 or more and 19 or less. A composition characterized by:

2. 2. The composition according to claim 1, wherein the carbon-carbon double bond structure of component (2) contains a butadiene structure.

3. The composition according to claim 1 or 2, wherein the component (4) comprises cobalt 2-ethylhexanoate.

4. The composition according to any one of claims 1 to 3, characterized in that it has a pot life of 100 minutes or more as measured by Method 5 "Determination by exothermic reaction temperature" as specified in JIS K 6870:2008, a tensile shear adhesive strength after 24 hours to iron-iron bonds as measured by the method specified in JIS K 6850:1999 of 10 MPa or more and the state of failure is cohesive failure, and the surface of the cured product is non-tacky as measured by the Ballochny method as specified in JIS K 5600-3-2:1999.

5. The composition according to any one of claims 1 to 4, which is a two-part type composition, wherein a first part contains at least (3) an organic peroxide, and a second part contains at least (4) an organic compound containing cobalt.

6. An adhesive composition comprising the composition according to any one of claims 1 to 5.

7. A bonded body obtained by bonding adherends using the adhesive composition according to claim 6.

8. A bonding method comprising bonding adherends using the adhesive composition of claim 6.

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