Two-component curable adhesive composition

Abstract

The two-component curable adhesive composition has a main component (A) and a curing agent (B), wherein the main component (A) contains a urethane prepolymer (a1) and an epoxy compound (a2), and the curing agent (B) contains a polyol compound (b1) and a polyamine compound (b2). The urethane prepolymer (a1) is obtained by reacting a raw material polyisocyanate with a polyol compound (a3) ​​having at least one hydroxyl group in the molecule so that the index is 2.05 to 12. The main component (A) also contains residual polyisocyanate (a4). The two-component curable adhesive composition contains a silane compound (X) in at least one of the main component (A) and the curing agent (B). The SP values ​​of the polyol compounds (a3) ​​and (b1) are each 14.0 to 21.0 (J / cm 3 ) 1 / 2 The difference in SP value between the polyol compound (a3) ​​and (b1) is 0.1 to 4.0 (J / cm 3 ) 1 / 2 .

Description

Technical Field

[0001] The present invention relates to a two-component curable adhesive composition comprising a main component and a curing agent. Background Art

[0002] In a structure such as a car body, parts made of different materials are sometimes joined together using an adhesive. By joining together using an adhesive, even if the difference in thermal expansion coefficients between the parts is large, the generation of strain and warping can be suppressed. For adhesives used in such applications, it is required that the bonding strength is good, especially for parts made of metal materials.

[0003] Patent Document 1 describes a polyurethane resin composition having high adhesion to metals, which contains a polyester polyol having a phosphorus compound residue as a constituent component and a polyurethane resin (A) and an epoxy resin (B) having an acid value and a urethane group concentration within a prescribed range.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5743042 Summary of the invention

[0007] Problems to be solved by the invention

[0008] For adhesives used in applications where components of a structure are joined together, the level of bonding strength relative to shear force is important. In addition, for adhesives used in such applications, not only bonding strength is required, but also good elongation at break is required to absorb the difference in thermal expansion between components. However, conventional polyurethane adhesives are difficult to exhibit excellent physical properties in terms of bonding strength relative to shear force and elongation at break.

[0009] An object of the present invention is to provide a polyurethane adhesive composition having excellent elongation at break and adhesive strength.

[0010] Means for solving problems

[0011] One embodiment of the present invention is a two-component curable adhesive composition, comprising a main component (A) and a curing agent (B).

[0012] The main agent (A) comprises a urethane prepolymer (a1) and an epoxy compound (a2),

[0013] The curing agent (B) comprises a polyol compound (b1) and a polyamine compound (b2),

[0014] The urethane prepolymer (a1) is obtained by reacting a raw material polyisocyanate with a polyol compound (a3) ​​having at least one hydroxyl group in the molecule so that the equivalent ratio of the isocyanate group in the raw material polyisocyanate to the hydroxyl group in the polyol compound (a3) ​​is 2.05 to 12 and all of the polyol compound (a3) ​​becomes a monomer unit of the urethane prepolymer (a1).

[0015] The main agent (A) further comprises, in addition to the urethane prepolymer (a1), a residual polyisocyanate (a4) which is a remainder of the raw material polyisocyanate that has not reacted with the polyol compound (a3),

[0016] At least one of the main agent (A) and the curing agent (B) contains a silane compound (X),

[0017] The SP values ​​of the polyol compound (a3) ​​and the polyol compound (b1) are each 14.0 to 21.0 (J / cm 3 ) 1 / 2 ,

[0018] The difference in SP value between the polyol compound (a3) ​​and the polyol compound (b1) is 0.1 to 4.0 (J / cm 3 ) 1 / 2 .

[0019] Preferably, the equivalent ratio of the isocyanate groups in the main agent (A) to the active hydrogen groups in the curing agent (B) is 0.8 to 4.

[0020] The equivalent ratio of the isocyanate group in the main agent (A) to the amino group in the polyamine compound (b2) is 1.2 to 6.

[0021] The polyol compound (a3) ​​is preferably at least one selected from polyester polyol, polytetramethylene ether glycol, polycarbonate polyol, polycaprolactone polyol, and partially modified products of these compounds.

[0022] The polyol compound (b1) is preferably at least one selected from the group consisting of polyoxypropylene diol, polybutadiene polyol, polyisoprene polyol, polyacrylic acid polyol, and partially modified products of these compounds.

[0023] The epoxy compound (a2) preferably has an epoxy equivalent of 100 to 500 g / eq.

[0024] The epoxy compound (a2) is preferably an epoxy compound having at least one urethane bond in the molecule.

[0025] The silane compound (X) is preferably a silane compound having at least one isocyanate group in the molecule.

[0026] The mass of the epoxy compound (a2) is preferably 0.1 to 30% by mass based on the mass of the two-component curable adhesive composition.

[0027] It is preferred that the tensile shear adhesive strength of a cured product obtained by curing the two-component curable adhesive composition be 10 MPa or more in accordance with JIS K6850.

[0028] Effects of the Invention

[0029] According to the two-component curable adhesive composition of the above embodiment, a polyurethane-based adhesive composition excellent in elongation at break and adhesive strength can be provided. DETAILED DESCRIPTION

[0030] Hereinafter, the two-component curable adhesive composition of this embodiment will be described. This embodiment includes various embodiments described below.

[0031] (Adhesive composition)

[0032] The two-component curable adhesive composition (hereinafter, also simply referred to as an adhesive composition) of the present embodiment comprises a main component (A) and a curing agent (B).

[0033] (Main agent (A))

[0034] The main agent (A) contains a urethane prepolymer (a1) and an epoxy compound (a2).

[0035] The urethane prepolymer (a1) is obtained by reacting a raw material polyisocyanate with a polyol compound (a3). Therefore, the urethane prepolymer (a1) has a monomer unit of a polyisocyanate and a monomer unit of a polyol compound (a3). Specifically, the reaction is carried out so that the equivalent ratio (hereinafter also referred to as an index) of the isocyanate group in the raw material polyisocyanate to the hydroxyl group in the polyol compound (a3) ​​is 2.05 to 12, and all the polyol compound (a3) ​​becomes a monomer unit of the urethane prepolymer (a1).

[0036] By making the index greater than 2.05 and making the isocyanate group greatly excessive relative to the hydroxyl group, a lot of hard segments that can generate hydrogen bonds with metals are formed in the cured product. In addition, since the index is greater than 2.05, a lot of residual polyisocyanates (residual isocyanates after the reaction of the raw material polyisocyanate and the polyol compound) that are easy to react with metals are contained in the main agent (A). Therefore, by making the index greater than 2.05, it is easy to obtain a cured product with excellent bonding strength to metals, specifically, it is easy to obtain a cured product with a bonding strength of more than 10MPa. In this specification, bonding strength refers to the tensile shear bonding strength according to JISK6850.

[0037] In addition, by making the index 2.05 or more and making the isocyanate group greatly excessive relative to the hydroxyl group, the remaining polyisocyanate can be fully reacted with the curing agent (B). As a result, it is easy to obtain a cured product with excellent elongation at break, specifically, it is easy to obtain a cured product with an elongation at break of 100% or more. In this specification, the elongation at break refers to the elongation at break according to JIS K6251.

[0038] Furthermore, by setting the index to 2.05 or more, the hard segments in the cured product increase, and thus a cured product having excellent breaking strength, specifically, a cured product having a breaking strength of 10 MPa or more, is easily obtained. In this specification, breaking strength refers to tensile strength in accordance with JIS K6251.

[0039] The index is preferably 3 or more, more preferably 4 or more. The higher the index, the more it is possible to avoid the situation where the isocyanate group is consumed and an excess of the polyol compound (b1) is produced when the main agent (A) and the curing agent (B) are mixed and reacted, and the adverse effects on the physical properties of the cured product can be avoided. On the other hand, if the equivalent ratio is too large, the elongation at break is sometimes excessively reduced. Therefore, the equivalent ratio is 12 or less, preferably 10 or less, and more preferably 8 or less.

[0040] According to the adhesive composition of the present embodiment, the following substances are formed in the cured product: the raw material polyisocyanate reacts with each active hydrogen group of the curing agent (B) after being added to the polyol compound (a3); and the raw material polyisocyanate does not react with the polyol compound (a3) ​​and remains and reacts with each active hydrogen group of the curing agent (B). As described above, due to the time lag between these reactions of the isocyanate group and the polyol compound (b1) mixed with the polyol compound (a3) ​​and the curing agent (B), a cured product with a characteristic structure can be obtained. In such a cured product formed on the metal surface, the following form can be taken: at least one of the soft segment and the hard segment is further bonded to the metal via the epoxy compound (a2) or the silane compound (X).

[0041] The raw material polyisocyanate has at least one, preferably two or more isocyanate groups in the molecule.

[0042] Specific examples of the polyisocyanate compound used as the raw material polyisocyanate include TDI (e.g., 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI)), MDI (e.g., 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI)), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), dimethyl Aromatic polyisocyanates such as 1,5-naphthalene diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), and triphenylmethane triisocyanate; aliphatic polyisocyanates such as pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, and norbornane diisocyanate (NBDI); trans-cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis(isocyanatomethyl)cyclohexane (H6XDI), dicyclohexylmethane diisocyanate (H 12 alicyclic polyisocyanates such as MDI); carbodiimide-modified polyisocyanates thereof; isocyanurate-modified polyisocyanates thereof; and the like.

[0043] Among them, the raw material polyisocyanate is preferably MDI.

[0044] Such polyisocyanates can be used alone or in combination of two or more.

[0045] According to one embodiment, the raw material polyisocyanate preferably contains at least one of diphenylmethane diisocyanate, polymethane diisocyanate, and isocyanurate group-containing isocyanate compound from the viewpoint of improving the reaction activity and exhibiting good strength when cured.

[0046] According to one embodiment, the raw material polyisocyanate preferably has at least one aromatic ring in the molecule. By including such a raw material polyisocyanate in the adhesive composition, the fracture strength of the cured product is improved. In addition, such a raw material polyisocyanate interacts well with the epoxy compound (a2).

[0047] The polyol compound (a3) ​​is a polyol compound having at least one, preferably at least two, hydroxyl groups in the molecule.

[0048] According to one embodiment, the number average molecular weight of the polyol compound (a3) ​​is preferably 250 or more, more preferably 500 or more. If the number average molecular weight of the polyol compound is lower than the above range, the elongation at break of the cured product may decrease, and the cured product may become too hard. The number average molecular weight of the polyol compound (a3) ​​is preferably 3000 or less.

[0049] From the viewpoint of contributing to improving the adhesive strength of the cured product, the polyol compound (a3) ​​is preferably at least one selected from polyester polyol, polytetramethylene ether glycol, polycarbonate polyol, polycaprolactone polyol, and partially modified products thereof.

[0050] Examples of the polyester polyol include condensates of low molecular weight polyols and polycarboxylic acids (condensation polyester polyols).

[0051] Specific examples of low molecular weight polyols include ethylene glycol (EG), diethylene glycol, propylene glycol (PG), dipropylene glycol, (1,3- or 1,4-)butanediol, pentanediol, neopentyl glycol, hexanediol, cyclohexanedimethanol, glycerol, 1,1,1-trimethylolpropane (TMP), 1,2,5-hexanetriol, pentaerythritol and the like; sugars such as sorbitol; and the like.

[0052] Examples of the polycarboxylic acid include glutaric acid, adipic acid, azelaic acid, fumaric acid, maleic acid, pimelic acid, suberic acid, sebacic acid, phthalic acid, terephthalic acid, isophthalic acid, dimer acid, pyromellitic acid, other low molecular weight carboxylic acids, oligomeric acids, castor oil, and hydroxycarboxylic acids such as a reaction product of castor oil and ethylene glycol (or propylene glycol).

[0053] The polycarbonate polyol is produced by, for example, a demethylation condensation reaction of a polyol and dimethyl carbonate, a dephenolation condensation reaction of a polyol and diphenyl carbonate, or a deglycolization condensation reaction of a polyol and ethylene carbonate. Examples of the polyol used in these reactions include various saturated or unsaturated diols such as 1,6-hexanediol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, octanediol, 1,4-butynediol, dipropylene glycol, tripropylene glycol, and polytetramethylene ether glycol, and alicyclic diols such as 1,4-cyclohexanediglycol and 1,4-cyclohexanedimethanol.

[0054] Examples of the polycaprolactone polyol include those having hydroxyl groups at both ends, which are obtained by ring-opening polymerization of lactone such as ε-caprolactone, α-methyl-ε-caprolactone, and ε-methyl-ε-caprolactone using an appropriate polymerization initiator.

[0055] Partially modified substances include, for example, substances obtained by introducing modifying groups into the molecules of polyester polyols, polytetramethylene ether glycols, polycarbonate polyols, and polycaprolactone polyols by copolymerization. As such partially modified substances, for example, modified substances obtained by replacing a part of the repeating units in the molecule with a modifying group can be mentioned. As a modifying group, for example, an alkylene group can be mentioned. As an alkylene group, specifically, ethylene, 1,2-propylene, 1,3-propylene, 2-methyl-1,3-propylene, 2,2-dimethyl-1,3-propylene, pentamethylene, hexamethylene, etc. can be preferably mentioned. The number of carbon atoms of the alkylene group is, for example, 2 to 10. The modification amount is, for example, 3 to 50% by weight. The type and modification amount of the alkylene group are not limited to the above-mentioned types and modification amounts, and can be appropriately selected. As a specific example of a partially modified substance, modified polytetramethylene ether glycol can be mentioned. As modified polytetramethylene ether glycol, there can be mentioned substances obtained by replacing a part of -(OH2)4-O- in the molecule of ordinary polytetramethylene ether glycol with -RO-. R is preferably an alkylene group of the above specific examples within the above range of carbon atoms. The modified polytetramethylene ether glycol can be produced by, for example, copolymerization of tetrahydrofuran and diol using heteropolyacid as catalyst, copolymerization of diol or cyclic ether as a condensate of diol and butanediol, etc.

[0056] The number average molecular weight of the urethane prepolymer (a1) is preferably 1,000 to 15,000, more preferably 1,000 to 10,000.

[0057] Here, the number average molecular weight is a number average molecular weight (in terms of polystyrene) measured by gel permeation chromatography (GPC), and tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) is preferably used as a solvent for the measurement.

[0058] The epoxy compound (a2) has at least one, preferably two or more epoxy groups in the molecule. The epoxy group is added to, for example, a molecular terminal.

[0059] According to the research of the inventors of the present application, the following discovery was obtained: by including the epoxy compound (a2) together with the silane compound (X) described later in the adhesive composition, the effect of improving the bonding strength of the cured product to the metal can be obtained. In addition, such epoxy compound (a2) interacts well with the polyamine compound (b2) having an aromatic ring, especially aromatic primary polyamines.

[0060] The epoxy compound (a2) is blended in the main agent (A) because of its high reactivity with the polyamine compound (b2) of the curing agent (B).

[0061] As the epoxy compound (a2), the following epoxy resins can be used alone or in combination: for example, epoxy compounds having biphenyl groups such as bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, biphenyl type, polyalkylene glycol type, alkylene glycol type epoxy compounds, epoxy compounds having a naphthalene ring, epoxy compounds having a fluorene group, and the like; difunctional glycidyl ether type epoxy resins; polyfunctional epoxy resins such as phenol novolac type, o-cresol novolac type, trihydroxyphenylmethane type, tetrahydroxyphenylethane type Glycidyl ether type epoxy resin; glycidyl ester type epoxy resin of synthetic fatty acid such as dimer acid; aromatic epoxy resin having a glycidylamino group such as N,N,N',N'-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N,N-diglycidylaniline; epoxy compound having a tricyclodecane ring (for example, epoxy compound obtained by a production method in which dicyclopentadiene and cresols or phenols such as m-cresol are polymerized and then reacted with epichlorohydrin), etc.

[0062] According to one embodiment, the epoxy compound (a2) is preferably an epoxy compound having at least one carbamate bond in the molecule (carbamate-modified epoxy compound). Such an epoxy compound (a2) is easy to react with the hydroxyl group present on the metal surface, and the effect of improving the bonding strength of the cured product is enhanced. In addition, such an epoxy compound (a2) has extremely good affinity with the carbamate part of the carbamate prepolymer (a1).

[0063] As the carbamate-modified epoxy compound, for example, a compound obtained by reacting a carbamate bond-containing compound (X) having an isocyanate group with an epoxy compound (Y) containing a hydroxyl group can be preferably used, wherein the carbamate bond-containing compound (X) is obtained by reacting a polyol compound (x1) with a polyisocyanate compound (x2).

[0064] Examples of the polyol compound (x1) include polyether polyols such as polypropylene glycol, polyester polyols, adducts of hydroxycarboxylic acids and alkylene oxides, polybutadiene polyols, polyolefin polyols, etc. The molecular weight of the polyol compound (x1) is preferably in the range of 300 to 5000, particularly 500 to 2000, in terms of mass average molecular weight, from the viewpoint of excellent balance between flexibility and curability.

[0065] The polyisocyanate compound (x2) is not particularly limited as long as it is a compound having two or more isocyanate groups. For example, aliphatic polyisocyanates, aromatic polyisocyanates, and polyisocyanate groups having aromatic hydrocarbon groups can be cited. Among them, aromatic polyisocyanates are preferred. As aromatic polyisocyanates, for example, toluene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate can be cited.

[0066] By reacting a compound (X) containing a urethane bond with an epoxy compound (Y) containing a hydroxyl group, a urethane prepolymer containing a free isocyanate group at the terminal can be obtained. By reacting it with an epoxy resin having at least one hydroxyl group in the molecule (e.g., diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of aliphatic polyols and glycidol, etc.), a urethane-modified epoxy compound can be obtained.

[0067] There is no particular restriction on the manufacture of carbamate-modified epoxy compounds. For example, carbamate and epoxide can be reacted in a large amount of epoxides (e.g., epoxy resins) to manufacture. There is no particular restriction on the epoxide used in the manufacture of carbamate-modified epoxy compounds. For example, conventionally known epoxides can be cited.

[0068] Specific examples of the urethane-modified epoxy compound that can be used include Adeka Electronics EPU-78-11, EPU-1395, EPU-17T-6, EPU-78-13S, EPU-6E, EPU-11N, EPU-15N, EPU-16AN, and EPU-18BN (manufactured by Adeka Corporation).

[0069] Such epoxy compounds (a2) can be used alone or in combination of two or more.

[0070] The epoxy equivalent of the epoxy compound (a2) is preferably 100 to 500 g / eq. If such an epoxy compound (a2) is included in the adhesive composition, the effect of improving the bonding strength of the cured product is enhanced. In this specification, the epoxy equivalent of the epoxy compound (a2) and its addition amount are expressed as the amount of the epoxy compound (e.g., urethane-modified epoxy compound) containing the excess epoxy resin used in the production.

[0071] Preferably, the adhesive composition contains 0.1 to 30% by mass of the epoxy compound (a2). If the content of the epoxy compound (a2) is less than 0.1% by mass, the effect of improving the bonding strength of the cured product cannot be fully obtained. If the content of the epoxy compound (a2) exceeds 30% by mass, the characteristics of the polyurethane adhesive cannot be fully exerted, and it is difficult to improve the elongation at break and the breaking strength of the cured product.

[0072] The main agent (A) contains residual polyisocyanate (a4) in addition to the urethane prepolymer (a1).

[0073] The residual polyisocyanate (a4) is the remaining part of the raw material polyisocyanate that has not reacted with the polyol compound (a3). By including the residual polyisocyanate (a4) in the main agent (A), it can react with the curing agent (B) quickly. As a result, the curing time can be shortened, the foaming caused by the reaction of the residual polyisocyanate (a4) with water can be suppressed, and the reduction of tensile properties such as elongation at break and breaking strength of the cured product can be suppressed.

[0074] (Curing agent (B))

[0075] The curing agent (B) contains a polyamine compound (b2) and a polyol compound (b1).

[0076] Since the polyamine compound (b2) reacts quickly with the isocyanate group and the epoxy compound (a2), it reacts quickly with the main agent (A). In this process, the carbamate prepolymer (a1) grows while curing. In addition, in the adhesive composition formed by mixing the main agent (A) and the curing agent (B), heat is generated along with the reaction of the polyamine compound (b2) and the main agent (A), thereby promoting the reaction of the polyol compound (b1) and the main agent (A). Since such a reaction-promoting effect brought about by the polyamine compound (b2) can be obtained, even if the isocyanate group in the main agent (A) is excessively contained, it is possible to suppress foaming and thus suppress the reduction of the physical properties of the cured product.

[0077] The polyamine compound (b2) has two or more amino groups in the molecule. As the polyamine compound (b2), a conventionally known polyamine compound can be used.

[0078] Specific examples of the polyamine compound (b2) include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, trimethylhexamethylenediamine, 1,2-propanediamine, iminobispropylamine, methyliminobispropylamine, and 1,5-diamino-2-methylpentane (MPMD, manufactured by Dupont Jamun Co., Ltd.); m-phenylenediamine, o-phenylenediamine , p-phenylenediamine, m-phenylenediamine (MXDA), diaminodiphenylmethane, diaminodiphenyl sulfone, diaminodiethyldiphenylmethane, diethylmethylphenylenediamine, 2-methyl-4,6-bis(methylthio)-1,3-phenylenediamine, 4,4'-methylenebis(2-chloroaniline), 4,4'-methylenebis(3-chloro-2,6-diethylaniline), trimethylenebis(4-aminobenzoate), bis(4-amino-2,3-dichlorophenyl)methane and other aromatic polyamines ; N-aminoethylpiperazine; monoamines having an ether bond in the main chain such as 3-butoxyisopropylamine; diamines having a polyether skeleton represented by Diefamine EDR148 manufactured by Suntec Chemical Co., Ltd.; alicyclic polyamines such as isophoronediamine, 1,3-bisaminomethylcyclohexane (1,3BAC, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 1-cyclohexylamino-3-aminopropane, and 3-aminomethyl-3,3,5-trimethyl-cyclohexylamine; norbornanediamine (NBDA, diamines having a norbornane skeleton such as those manufactured by Mitsui Chemicals Co., Ltd.; polyamide amines having an amino group at the molecular end of the polyamide; 2,5-dimethyl-2,5-hexamethylenediamine, menthylene diamine, 1,4-bis(2-amino-2-methylpropyl)piperazine, Diefamine D230 and Diefamine D400 manufactured by Suntec Chemical Co., Ltd. having polypropylene glycol (PPG) in the skeleton; and the like. These polyamine compounds can be used alone or in combination of two or more.

[0079] According to one embodiment, the polyamine compound (b2) is preferably the above-mentioned aromatic polyamine. With respect to polyamines other than aromatic polyamines, sometimes the reaction rate with the main agent (A) is too fast, and the bonding strength and elongation at break of the cured product cannot be fully improved. In addition, with respect to polyamines other than aromatic polyamines, it is difficult to obtain good interaction between them and the epoxy compound (a2) and the residual polyisocyanate (a4). From this viewpoint, among aromatic polyamines, the polyamine compound (b2) is particularly preferably an aromatic primary polyamine.

[0080] According to one embodiment, the number average molecular weight of the polyamine compound (b2) is preferably less than 500 from the viewpoint of increasing the reaction rate with the isocyanate group in the main agent (A).

[0081] The polyol compound (b1) has at least two hydroxyl groups in the molecule. The number average molecular weight of the polyol compound (b1) is preferably 500 or more, more preferably 1000 or more. By including such a polyol compound (b1) in the curing agent (B), the elongation at break of the cured product can be increased. If the number average molecular weight of the polyol compound (b1) is less than 500, the elongation at break of the cured product is sometimes reduced, and the cured product becomes excessively hard.

[0082] Furthermore, since the reaction between the polyol compound (b1) and the isocyanate group in the main agent (A) proceeds more slowly than that of the polyamine compound (b2), the curing time is not too short, which contributes to improved workability.

[0083] From the aspect of helping to improve the elongation at break of the cured product, the polyol compound (b1) is preferably selected from at least one of polyoxypropylene glycol, polybutadiene polyol, polyisoprene polyol, polyacrylic acid polyol, and partially modified compounds obtained by partially modifying each of them. The partially modified compound may include, for example, a substance obtained by introducing a modified group into the molecule of polyoxypropylene glycol, polybutadiene polyol, polyisoprene polyol, or polyacrylic acid polyol by copolymerization. As such a partially modified compound, a modified compound obtained by replacing a part of the repeating unit in the molecule with a modified group may be included. The modified group and the amount of modification are the same as those described for the polyol compound (a3).

[0084] The polyol compound (b1) is preferably a polyol compound different from the polyol compound (a3). If the polyol compound (b1) and the polyol compound (a3) ​​are the same polyol compound, it is difficult to achieve both the adhesive strength and the elongation at break of the cured product.

[0085] The difference in SP value between the polyol compound (a3) ​​and the polyol compound (b1) is 0.1 to 4.0 (J / cm 3 ) 1 / 2 By doing so, the SP value of the two polyol compounds was set to 0.1 (J / cm 3 ) 1 / 2 The above can easily achieve both the adhesive strength and elongation at break of the cured product, and by making it 4.0 (J / cm 3 ) 1 / 2 The difference in the SP value is preferably 0.1 to 2.0 (J / cm 3 ) 1 / 2 , more preferably 0.1 to 1.0 (J / cm 3 ) 1 / 2 .

[0086] In this specification, the SP value refers to the value δ calculated by the following Small formula.

[0087] δ=dΣG / M

[0088] Wherein, d represents density, G represents the intermolecular gravitational constant (Small constant), and M represents the molecular weight.

[0089] The SP values ​​of the polyol compound (a3) ​​and the polyol compound (b1) are each 14.0 to 21.0 (J / cm 3 ) 1 / 2 If the SP values ​​of the polyol compound (a3) ​​and the polyol compound (b1) are outside the above range, the polarity of each polyol compound is too high or too low, which impairs the effect of improving the adhesive strength and elongation at break of the cured product. The SP values ​​of the polyol compound (a3) ​​and the polyol compound (b1) are preferably 14.5 to 20.5 (J / cm 3 ) 1 / 2 , more preferably 14.0 to 20.0 (J / cm 3 ) 1 / 2 .

[0090] According to one embodiment, the equivalent ratio of the isocyanate group in the main agent (A) to the active hydrogen group in the curing agent (B) (hereinafter also referred to as the isocyanate group / active hydrogen group ratio) is preferably 0.8 to 4. In this specification, the active hydrogen group in the curing agent (B) refers to the hydroxyl group in the polyol compound (b1) and the amino group in the polyamine compound (b2). The isocyanate group in the main agent (A) refers to the isocyanate group in the urethane prepolymer (a1) and the residual polyisocyanate (a4).

[0091] Even if the isocyanate group / active hydrogen group ratio is changed within the range of 0.8 to 4, the bonding strength and elongation at break of the cured product will not change significantly. Specifically, relative to the bonding strength and elongation at break when the mixing ratio (mass ratio) of the main agent (A) and the curing agent (B) is 1:1, the change rate of the bonding strength and the elongation at break is suppressed to within ±20%. According to one embodiment, the mixing ratio (mass ratio) of the main agent (A) and the curing agent (B) can be 4:6 to 6:4.

[0092] The equivalent ratio of the isocyanate group in the main agent (A) to the amino group in the polyamine compound (b2) (hereinafter also referred to as the isocyanate group / amino group ratio) is preferably 1.2 to 6. If the isocyanate group / amino group ratio is lower than 1.2, the isocyanate group in the main agent (A) has less chance to react with the hydroxyl group of the polyol compound (b1), and it is difficult to improve the elongation at break of the cured product. On the other hand, if the isocyanate group / amino group ratio exceeds 6, the curing speed of the adhesive composition slows down, and the possibility of foaming increases.

[0093] According to one embodiment, the equivalent ratio of the isocyanate group in the main agent (A) to the hydroxyl group in the polyol compound (b1) (hereinafter referred to as the isocyanate group / hydroxyl group ratio) is preferably 2 to 12. If the isocyanate group / hydroxyl group ratio is lower than 2, when the isocyanate group / amino group ratio is small, the curing speed is too fast and the elongation at break of the cured product becomes small. On the other hand, when the isocyanate group / hydroxyl group ratio is lower than 2 and the isocyanate group / amino group ratio is large, the curing speed is slow and foaming is likely to occur, resulting in that the bonding strength is difficult to improve. In addition, if the isocyanate group / hydroxyl group ratio exceeds 12, foaming is likely to occur.

[0094] According to one embodiment, the polyol compound (b1) preferably contains at least one of polyethylene glycol and polypropylene glycol. In addition, according to one embodiment, the polyol compound (b1) is particularly preferably a compound having a primary hydroxyl group at a terminal.

[0095] According to one embodiment, the equivalent ratio of the amino group in the polyamine compound (b2) to the hydroxyl group in the polyol compound (b1) (hereinafter also referred to as the amino group / hydroxyl group ratio) is preferably 1.5 to 6. Thus, the curing reaction rate can be made appropriate, thereby improving the adhesive strength and elongation at break in a good balance. The above equivalent ratio is preferably 1.5 to 4.

[0096] According to one embodiment, from the viewpoint of adjusting the physical properties of the cured product, the ratio of the mass of the polyol compound (a3) ​​reacted with the raw material polyisocyanate to the mass of the polyol compound (b1) is preferably 1 or less.

[0097] Without prejudice to the purpose of the present invention, the main agent (A) and curing agent (B) described above may each further contain fillers, curing catalysts, plasticizers, anti-aging agents, antioxidants, pigments (dyes), thixotropy-imparting agents, ultraviolet absorbers, flame retardants, surfactants (including leveling agents), dispersants, dehydrating agents, adhesion-imparting agents, antistatic agents and other previously known additives as needed.

[0098] The main agent (A) preferably contains at least one selected from the group consisting of a filler, an antioxidant, a colorant, a viscosity modifier, and a plasticizer.

[0099] The curing agent (B) preferably contains at least one selected from the group consisting of fillers, antioxidants, colorants, viscosity modifiers, plasticizers, and polyols having a number average molecular weight of less than 500. Polyols having a number average molecular weight of less than 500 are used as a component for adjusting the physical properties of the cured product by curing agent (B). As polyols having a number average molecular weight of less than 500, for example, the above-mentioned low molecular weight polyols can be used. According to one embodiment, the number average molecular weight of the polyol is preferably 200 or less. The number of hydroxyl groups contained in the molecule of the polyol is, for example, 2 to 4. The curing agent (B) preferably contains 5 to 20% by mass of the polyol.

[0100] The adhesive composition does not necessarily have to contain a catalyst such as an organometallic compound or a tertiary amine. That is, according to one embodiment, the adhesive composition preferably does not contain a catalyst such as an organometallic compound or a tertiary amine.

[0101] (Silane compound (X))

[0102] The adhesive composition contains a silane compound (X) in at least one of the main agent (A) and the curing agent (B). By including the silane compound (X) in the adhesive composition, the bonding strength of the cured product to the metal can be improved. In a state where the ease of fusion of the adhesive to the metal is improved by using the epoxy compound (a2), the silane compound (X) forms a covalent bond with the metal, thereby obtaining a higher bonding strength improvement effect.

[0103] The silane compound (X) is preferably contained in a reagent that does not contain a component that is highly reactive with the silane compound (X) in the main agent (A) and the curing agent (B). This can avoid the situation where the silane compound (X) reacts with the component before the main agent (A) and the curing agent (B) are mixed.

[0104] From the viewpoint of improving the reactivity with the components in the main agent (A) and the curing agent (B), the silane compound (X) preferably has any one functional group of an isocyanate group, an amino group, an epoxy group, a mercapto group, an isocyanurate group, a ketimine group, etc. in the molecule. Among them, from the perspective of improving the bonding strength by bonding the soft segment in the cured product to the metal, a silane compound having at least one isocyanate group in the molecule is preferred. The silane compound containing an isocyanate group is contained in the main agent (A). The number of functional groups contained in the silane compound (X) is preferably 1 to 3.

[0105] According to one embodiment, the functional group is preferably bonded to the silicon atom via an alkylene group. The alkylene group preferably has 1 to 5 carbon atoms, and for example, a methylene group, an ethylene group, or a propylene group can be used.

[0106] According to one embodiment, from the viewpoint of improving the reactivity with metals, the silane compound (X) preferably has at least one functional group such as an alkoxy group in addition to the above functional groups. The functional group is preferably bonded to a silicon atom, and 1 to 3 functional groups are contained in the silane compound (X). The number of carbon atoms of the alkoxy group is preferably 1 to 3, and for example, a methoxy group or an ethoxy group can be preferably used.

[0107] Examples of the silane compound (X) having an isocyanate group include 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropylmethyldimethoxysilane, and 3-isocyanatepropylmethyldiethoxysilane.

[0108] Examples of the silane compound (X) having an amino group include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane.

[0109] Examples of the silane compound (X) having an epoxy group include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0110] Examples of the silane compound (X) having a mercapto group include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

[0111] As a silane compound (X) which has an isocyanurate group, tris(3-trimethoxysilylpropyl)isocyanurate etc. are mentioned, for example.

[0112] As a silane compound (X) which has a ketimine group, 3-trimethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine etc. are mentioned, for example.

[0113] According to the adhesive composition of the present embodiment, excellent physical properties in terms of bonding strength and elongation at break can be presented. Specifically, the bonding strength is more than 10MPa, and the elongation at break is more than 100%. The physical properties of such a cured product, the elongation at break is equivalent to that of a conventional polyurethane adhesive, and the bonding strength is a size based on the bonding strength of an epoxy resin adhesive. A cured product having such characteristics is suitable for joining components of a structural body such as a car body to each other.

[0114] The adhesive strength is preferably 15 MPa or more, and more preferably 20 MPa or more. The upper limit of the adhesive strength is not particularly limited, and is, for example, about 80 MPa.

[0115] The elongation at break is preferably 150% or more, more preferably 200% or more, and even more preferably 250% or more. The upper limit of the elongation at break is not particularly limited, and is, for example, about 500%.

[0116] In addition, according to the adhesive composition of this embodiment, excellent fracture strength can also be exhibited. Specifically, the fracture strength is 10MPa or more, preferably 15MPa or more, more preferably 20MPa or more, and further preferably 25MPa or more. The upper limit of the fracture strength is not particularly limited, for example, about 100MPa.

[0117] The adhesive composition of this embodiment is not limited to the body of a car, but can be used to join parts of various structures. In addition, the adhesive composition of this embodiment can be used as a coating, waterproof material, floor material, elastomer, artificial leather, spandex, etc. in addition to being used as an adhesive.

[0118] (Method for producing adhesive composition)

[0119] A method for producing an adhesive composition according to one embodiment includes: a step of preparing a main agent (A); and a step of preparing a curing agent (B).

[0120] In the step of preparing the main agent (A), the raw material polyisocyanate and the polyol compound (a3) ​​are reacted in such a manner that the index is 2.05 to 12 and all the polyol compounds (a3) ​​become monomer units of the urethane prepolymer (a1), thereby preparing the urethane prepolymer (a1), and the epoxy compound (a2) is added thereto. Thus, the main agent (A) containing the urethane prepolymer (a1), the epoxy compound (a2) and the residual polyisocyanate (a4) is prepared. Here, the raw material polyisocyanate, the polyol compound (a3), the urethane prepolymer (a1), the residual polyisocyanate (a4), and the epoxy compound (a2) are respectively constituted in the same manner as the raw material polyisocyanate, the polyol compound (a3), the urethane prepolymer (a1), the residual polyisocyanate (a4), and the epoxy compound (a2) described above.

[0121] In the step of preparing the curing agent (B), a curing agent (B) comprising a polyol compound (b1) and a polyamine compound (b2) is prepared. Here, the polyol compound (b1) and the polyamine compound (b2) have the same structure as the polyol compound (b1) and the polyamine compound (b2) described above.

[0122] In the present production method, a silane compound (X) is further added in at least one of the step of preparing the main agent (A) and the step of preparing the curing agent (B).

[0123] The adhesive composition described above can be produced using the above-described production method.

[0124] (Experimental example)

[0125] In order to investigate the effects of the present invention, adhesive compositions were prepared according to the blending amounts shown in Tables 1 and 2, and the breaking strength and breaking elongation of the cured products, and the bonding strength to aluminum materials and steel materials were measured.

[0126] Urethane prepolymers 1 to 5 were prepared as follows, and the epoxy compound (a2), silane compound (X) and additives shown in the table were added to prepare a main agent. In addition, the raw materials shown in the table were mixed to prepare a curing agent.

[0127] <Synthesis of urethane prepolymer 1>

[0128] In a nitrogen atmosphere, 100 g of polytetramethylene ether glycol and 100 g of 4,4′-diphenylmethane diisocyanate (index: 4.0) were stirred and reacted at 80° C. for 4 hours to synthesize a urethane prepolymer 1.

[0129] <Synthesis of urethane prepolymer 2>

[0130] In a nitrogen atmosphere, 100 g of polytetramethylene ether glycol and 150 g of 4,4′-diphenylmethane diisocyanate (index: 6.0) were stirred and reacted at 80° C. for 4 hours to synthesize a urethane prepolymer 2.

[0131] <Synthesis of urethane prepolymer 3>

[0132] In a nitrogen atmosphere, 100 g of polycarbonate diol and 100 g of 4,4′-diphenylmethane diisocyanate (index: 4.0) were stirred and reacted at 80° C. for 4 hours to synthesize a urethane prepolymer 3.

[0133] <Synthesis of urethane prepolymer 4>

[0134] In a nitrogen atmosphere, 100 g of polytetramethylene ether glycol and 50 g of 4,4′-diphenylmethane diisocyanate (index: 2.0) were stirred and reacted at 80° C. for 4 hours to synthesize a urethane prepolymer 4.

[0135] <Synthesis of urethane prepolymer 5>

[0136] In a nitrogen atmosphere, 100 g of silicone oil modified with carbinol at both ends and 31 g of 4,4′-diphenylmethane diisocyanate (index: 4.0) were stirred and reacted at 80° C. for 8 hours to synthesize a urethane prepolymer 5.

[0137] As the polytetramethylene ether glycol, polycarbonate diol, and 4,4′-diphenylmethane diisocyanate used in the preparation of the above urethane prepolymers 1 to 5, the following were used.

[0138] Polytetramethylene ether glycol:

[0139] PTMG1000 (number average molecular weight: 1000), manufactured by Mitsubishi Chemical

[0140] Polycarbonate diol:

[0141] Duranol T6001 (number average molecular weight: 1000), manufactured by Asahi Kasei Corporation

[0142] ·4,4'-Diphenylmethane diisocyanate:

[0143] Mirionet MT (molecular weight: 250), manufactured by Tosoh Corporation

[0144] ·Methanol-modified silicone oil at both ends:

[0145] Both-terminal methanol-modified silicone oil, KF-6002, manufactured by Shin-Etsu Chemical Co., Ltd.

[0146] In the table, the value of urethane prepolymers 1 to 5 represents the total amount of urethane prepolymers (a1) and residual polyisocyanate (a4). As raw materials other than urethane prepolymers 1 to 5 shown in the table, the following materials were used. In the table, the amount of raw materials is expressed in parts by mass.

[0147] Epoxide 1: Urethane-modified epoxide, ADEKA Epoxide EPU-1395 (epoxide equivalent: 215 g / eq), manufactured by ADEKA Corporation

[0148] Epoxide 2: Urethane-modified epoxide, EPU-80, epoxy equivalent weight 1400 g / eq, manufactured by ADEKA

[0149] · Epoxide 3: 2-functional reactive epoxide, ED-523T, epoxy equivalent weight 140 g / eq, manufactured by ADEKA

[0150] ·Silane 1: 3-isocyanatopropyltrimethoxysilane, Siliquest A-Link35, manufactured by モメンティブ・パフォーマンス・マテリアルズ

[0151] Silane 2: tris-(trimethoxysilylpropyl)isocyanurate, KBM-9659, manufactured by Shin-Etsu Chemical Co., Ltd.

[0152] ·Carbon black: 200MP, manufactured by Nippon Chemical Co., Ltd.

[0153] ·Calcium carbonate 1: Heavy calcium carbonate, Supro S, manufactured by Maruo Calcutta Co., Ltd.

[0154] ·Plasticizer: Diisononyl phthalate, manufactured by Dieplastic Co., Ltd.

[0155] Polyol 1: polypropylene glycol (number average molecular weight 2000 to 3000), Sannics PL-2100, manufactured by Sanyo Chemical Co., Ltd.

[0156] Polyol 2: Polyisoprene polyol, Poly ip, manufactured by Idemitsu Kosan Co., Ltd.

[0157] Polyol 3: Silicone oil modified with methanol at both ends, KF-6002, manufactured by Shin-Etsu Chemical Co., Ltd.

[0158] Polyol 4: polytetramethylene ether glycol, PTMG2000 (number average molecular weight: 2000), manufactured by Mitsubishi Chemical Co., Ltd.

[0159] ·Polyamine: Diethylmethylphenylenediamine, DETDA, manufactured by Mitsui Chemicals Fiber Co., Ltd.

[0160] ·Calcium carbonate 2: Light calcium carbonate, Calcium Carbon 200, manufactured by Maruo Calcium Co., Ltd.

[0161] ·Silica: Ryoro QS-102S, manufactured by Tokuta Co., Ltd.

[0162] The table also shows the isocyanate group / amino group ratio and the isocyanate group / hydroxyl group ratio. Although not shown in the table, the amino group / hydroxyl group ratio was adjusted within the range of 1.5 to 6.

[0163] The prepared main agent and curing agent were mixed at a mass ratio of 1:1, and the breaking strength, breaking elongation and bonding strength were measured according to the following points.

[0164] <Breaking strength, breaking elongation>

[0165] A dumbbell-shaped No. 3 test piece was made and subjected to a tensile test according to JIS K6251. The tensile strength (breaking strength) and the elongation at break (breaking elongation) were measured under the conditions of a temperature of 20°C and a crosshead speed (tensile speed) of 200 mm / min. The marking lines for measuring the breaking elongation were marked at intervals of 20 mm. As a result, the case where the breaking strength was 10 MPa or more was evaluated as excellent in the breaking strength, and the case where the breaking elongation was 100% or more was evaluated as excellent in the breaking elongation.

[0166] <Adhesion Strength>

[0167] Aluminum and steel test pieces were used as adherends, respectively, and tensile shear tests were performed in accordance with JIS K6850 to measure tensile shear bond strength (bonding strength) at a temperature of 20°C and a crosshead speed of 50 mm / min. As a result, a bonding strength of 10 MPa or more was evaluated as excellent.

[0168] Table 1

[0169]

[0170] Table 2

[0171]

[0172] From the comparison between Examples 1 to 9 and Comparative Examples 1 to 7, it can be seen that when the main agent contains a urethane prepolymer (a1) (which is prepared by using raw materials polyisocyanate and polyol compound (a3) ​​with an index of 2.05 to 12), an epoxy compound (a2), and a residual polyisocyanate (a4), the curing agent contains a polyol compound (b1) and a polyamine compound (b2), and at least one of the main agent (A) and the curing agent (B) contains a silane compound (X), the polyol compound (a3), and the polyol compound (b1), the SP values ​​are each 14.0 to 21.0 (J / cm 3 )1 / 2 The difference in SP value between the polyol compound (a3) ​​and the polyol compound (b1) is 0.1 to 4.0 (J / cm 3 ) 1 / 2 The adhesive composition of the present invention can obtain a cured product that can simultaneously achieve excellent bonding strength and elongation at break. It is found that a polyurethane adhesive having excellent bonding strength to metal materials can be obtained.

[0173] It is also known that the use of the adhesive composition can provide a polyurethane adhesive having excellent breaking strength. In other words, it is known that the use of the adhesive composition can simultaneously achieve excellent tensile properties such as elongation at break and breaking strength, and excellent bonding strength.

[0174] It should be noted that even if the isocyanate group / active hydrogen group ratio is changed within the range of 0.8 to 4, the change rate of the adhesive strength and the elongation at break is suppressed to within ±20% relative to the adhesive strength and the elongation at break when the mixing ratio (mass ratio) of the main agent (A) and the curing agent (B) is 1:1.

[0175] As mentioned above, the two-component curable adhesive composition of the present invention has been described, but the present invention is not limited to the above-mentioned embodiments and examples, and various improvements and changes can be made without departing from the scope of the present invention.

Claims

1. A two-component curable adhesive composition, characterized in that: It has a main agent (A) and a curing agent (B). The main agent (A) comprises a urethane prepolymer (a1) and an epoxy compound (a2), The curing agent (B) comprises a polyol compound (b1) and a polyamine compound (b2), The urethane prepolymer (a1) is obtained by reacting a raw material polyisocyanate with a polyol compound (a3) ​​having at least one hydroxyl group in the molecule so that the equivalent ratio of the isocyanate group in the raw material polyisocyanate to the hydroxyl group in the polyol compound (a3) ​​is 2.05 to 12 and all of the polyol compound (a3) ​​becomes a monomer unit of the urethane prepolymer (a1). The main agent (A) further comprises, in addition to the urethane prepolymer (a1), a residual polyisocyanate (a4) which is a remainder of the raw material polyisocyanate that has not reacted with the polyol compound (a3), At least one of the main agent (A) and the curing agent (B) contains a silane compound (X), The SP values ​​of the polyol compound (a3) ​​and the polyol compound (b1) are each 14.0 to 21.0 (J / cm 3 ) 1 / 2 , The difference in SP value between the polyol compound (a3) ​​and the polyol compound (b1) is 0.1 to 4.0 (J / cm 3 ) 1 / 2 , The equivalent ratio of the isocyanate groups in the main agent (A) to the active hydrogen groups in the curing agent (B) is 0.8 to 4, The equivalent ratio of the isocyanate group in the main agent (A) to the amino group in the polyamine compound (b2) is 1.2 to 6. The SP value is the value δ calculated by the following Small formula: δ=dΣG / M In the formula, d represents density, G represents the intermolecular gravitational constant, i.e., Small constant, and M represents molecular weight. 2 . The two-component curable adhesive composition according to claim 1 , wherein the polyol compound (a3) ​​is at least one selected from polyester polyol, polytetramethylene ether glycol, polycarbonate polyol, and partially modified products thereof. 3 . The two-component curable adhesive composition according to claim 1 , wherein the polyol compound (a3) ​​is at least one selected from the group consisting of polycaprolactone polyol and partially modified products thereof.

4. The two-component curable adhesive composition according to any one of claims 1 to 3, wherein the polyol compound (b1) is at least one selected from polyoxypropylene glycol, polybutadiene polyol, polyisoprene polyol, polyacrylic acid polyol, and partially modified products of each of these compounds. 5 . The two-component curable adhesive composition according to claim 1 , wherein the epoxy compound (a2) has an epoxy equivalent of 100 to 500 g / eq. 6 . The two-component curable adhesive composition according to claim 1 , wherein the epoxy compound (a2) is an epoxy compound having at least one urethane bond in a molecule. 7 . The two-component curable adhesive composition according to claim 1 , wherein the silane compound (X) is a silane compound having at least one isocyanate group in the molecule. 8 . The two-component curable adhesive composition according to claim 1 , wherein the mass of the epoxy compound (a2) is 0.1 to 30 mass % based on the mass of the two-component curable adhesive composition. 9 . The two-component curable adhesive composition according to claim 1 , wherein a cured product obtained by curing the two-component curable adhesive composition has a tensile shear adhesive strength of 10 MPa or more in accordance with JIS K6850.

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