Adhesive, adhesive for bonding different kinds of materials, adhesive sheet, and adhesive sheet for bonding different kinds of materials

Abstract

The present invention provides an epoxy-based adhesive capable of maintaining adhesive strength and achieving cohesive failure without interface peeling in adhesion of different materials. An epoxy-based adhesive characterized by comprising an epoxy resin (A) and a curing agent (B), as the epoxy resin (A), containing a bisphenol A-type epoxy resin (A1), a bisphenol F-type epoxy resin (A2), and a rubber-modified epoxy resin (A3), and the content ratio of the bisphenol A-type epoxy resin (A1) to the bisphenol F-type epoxy resin (A2) [(A1) / (A2)] is less than 2.7.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive. In detail, it relates to an adhesive capable of firmly bonding different kinds of materials, particularly different kinds of metals, when they are bonded. BACKGROUND

[0002] A cured product of a resin composition in which an epoxy resin is used as a main component is excellent in dimensional stability, mechanical strength, electrical insulation, heat resistance, water resistance, chemical resistance, and the like, and is used as a structural adhesive for a structural panel of a vehicle or the like.

[0003] Today, the use of an adhesive in combination with riveting and spot welding is increasing in the automobile field, and a structural adhesive having high adhesive strength is generally used as the adhesive used, and an adhesive having high shear adhesive strength is selected.

[0004] As an epoxy-based adhesive used in such a use, the improvement of the adhesive strength of the adhesive and the impartation of impact properties are performed by adding rubber and a reinforcing agent, polymer fine particles, or the like to an epoxy resin, and for example, Patent Literature 1 describes that the impact resistance and the peel strength of a cured product are improved by adding a rubber-modified epoxy resin and a reactive reinforcing agent, and further, Patent Literature 2 describes that a high elastic modulus can be maintained and a high adhesive force can be achieved by adding an epoxy resin and polymer fine particles.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-523800

[0008] Patent Literature 2: Japanese Patent Application Laid-Open No. 2015-182248 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, it is known that today, in order to reduce the environmental burden, the weight reduction of a vehicle body is also performed, and various materials such as aluminum, carbon fiber reinforced plastic (CFRP), and the like are used in vehicles such as automobiles on the basis of iron that has been generally used in the past, and in the case where different kinds of materials are bonded, problems such as bonding failure, that is, interfacial peeling, which do not occur in the bonding of the same material, easily occur.

[0011] In this situation, when the adhesive of the aforementioned Patent Documents 1 and 2 is used for adhesion of different kinds of materials, in a region where the amount of rubber, reinforcing agent, and polymer fine particles is small, there is a problem that adhesion to the material is low and interfacial peeling easily occurs, on the other hand, it is clear that if a large amount of rubber is used, cohesive failure occurs, but there is a problem that adhesion strength is reduced due to a large decrease in elastic modulus, which is fatal for use as a structural adhesive.

[0012] Thus, in the present application, in this background, an epoxy-based adhesive which can maintain adhesion strength and does not cause interfacial peeling in adhesion of different kinds of materials, and can cause cohesive failure is provided.

[0013] Solution to the problem

[0014] Thus, the present inventors and others have repeatedly conducted intensive research in view of the circumstances, and as a result, it has been found that by producing an adhesive which contains an epoxy resin (A) and a curing agent (B) in a specific composition ratio, and the epoxy resin (A) contains a bisphenol A type epoxy resin (Al), a bisphenol F type epoxy resin (A2), and a rubber-modified epoxy resin (A3), the present problem can be solved. That is, when a bisphenol A type epoxy resin (Al) and a bisphenol F type epoxy resin (A2) are used together in the past, the elastic modulus of the cured product is increased, and the glass transition temperature is increased, and therefore, a much larger amount of bisphenol A type epoxy resin (Al) than bisphenol F type epoxy resin (A2) is generally used, but by setting the content ratio of bisphenol A type epoxy resin (Al) to bisphenol F type epoxy resin (A2) to a specific amount or less, it has been unexpectedly found that adhesion strength can be maintained and adhesion can be improved in adhesion of different kinds of materials, interfacial peeling does not occur, and cohesive failure can be achieved.

[0015] That is, the present application provides the following [1] to

[15] .

[0016] [1] An epoxy-based adhesive characterized by containing an epoxy resin (A) and a curing agent (B),

[0017] As the aforementioned epoxy resin (A), a bisphenol A type epoxy resin (Al), a bisphenol F type epoxy resin (A2), and a rubber-modified epoxy resin (A3) are contained,

[0018] The content ratio of the aforementioned bisphenol A type epoxy resin (Al) to the aforementioned bisphenol F type epoxy resin (A2) [(Al) / (A2)] is less than 2.7.

[0019] [2] The epoxy-based adhesive according to [1], characterized in that, as the aforementioned rubber-modified epoxy resin (A3), at least one of a carboxyl-terminated butadiene nitrile rubber-modified epoxy resin or a nitrile butadiene rubber-modified epoxy resin is contained.

[0020] [3] The epoxy-based adhesive according to [1] or [2], characterized in that the content of the aforementioned rubber-modified epoxy resin (A3) is 5 to 45 mass% relative to the entire epoxy resin (A).

[0021] [4] The epoxy-based adhesive according to any one of [1] to [3], characterized in that, as the aforementioned epoxy resin (A), an aromatic ring-containing epoxy resin (A4) that is solid at 25°C and is other than the aforementioned (A1) to (A3) is contained.

[0022] [5] The epoxy-based adhesive according to any one of [1] to [4], characterized in that the content of the epoxy resin that is solid at 25°C is 50 mass% or more relative to the entire epoxy resin (A).

[0023] [6] The epoxy-based adhesive according to any one of [1] to [5], characterized in that, as the aforementioned curing agent (B), a dicyandiamide is contained.

[0024] [7] The epoxy-based adhesive according to any one of [1] to [6], characterized in that it further contains polymer microparticles (C) having a core-shell structure.

[0025] [8] The epoxy-based adhesive according to any one of [1] to [7], characterized in that it is solid at 25°C.

[0026] [9] The epoxy-based adhesive according to any one of [1] to [8], characterized in that the viscosity at 60°C is 0.01 to 5000 Pa-s.

[0027]

[10] The epoxy-based adhesive according to any one of [1] to [9], characterized in that it is used for the adhesion of dissimilar materials.

[0028]

[11] An adhesive sheet, characterized by comprising the epoxy-based adhesive according to any one of [1] to [9].

[0029]

[12] An adhesive sheet for the adhesion of dissimilar materials, characterized by comprising the epoxy-based adhesive according to

[10] .

[0030]

[13] An adhesive sheet, characterized by having an adhesive layer comprising an epoxy-based adhesive, the thickness of the aforementioned adhesive layer being 0.1 to 2 mm,

[0031] The epoxy-based adhesive comprises an epoxy resin (A) and a curing agent (B), as the aforementioned epoxy resin (A), a bisphenol A-type epoxy resin (Al), a bisphenol F-type epoxy resin (A2), and a rubber-modified epoxy resin (A3) are contained.

[0032]

[14] The adhesive sheet according to

[13] , wherein the adhesive layer is formed of a nonwoven fabric impregnated with the epoxy-based adhesive.

[0033]

[15] The adhesive sheet according to

[13] or

[14] , wherein at least one surface of the adhesive layer has a release film.

[0034] Effects of the Invention

[0035] The epoxy-based adhesive of the present application can maintain adhesive strength and does not cause interfacial peeling in adhesion of different materials, and can achieve cohesive failure. Thus, an adhesive with good adhesion can be provided. DETAILED DESCRIPTION

[0036] Hereinafter, the present application will be described in detail.

[0037] Note that, in the present specification, the term "epoxy resin" is generally used as the name of a classification in thermosetting resins, or the name of a classification of chemical substances that are compounds having one or more epoxy groups in the molecule, and is used in the latter meaning in the present application. In addition, in the present application, if it is a compound having one or more epoxy groups in the molecule, not only polymers having a specific degree of polymerization, but also monomers are included in the definition of epoxy resins.

[0038] Note that, in the present specification, "molecular weight" is the number average molecular weight unless otherwise specified. In addition, "room temperature" means 25°C, and "solid at 25°C" means that the softening point is 25°C or higher or the viscosity at 25°C is 1000 Pa-s or higher

[0039] In addition, in the present specification, in the case where it is stated as "X to Y" (X, Y are arbitrary numbers), unless otherwise specified, the meaning of "X or more and Y or less" and the meaning of "preferably greater than X" or "preferably less than Y" are included.

[0040] In addition, in the case where it is stated as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), the meaning of "preferably greater than X" or "preferably less than Y" is also included.

[0041] <Epoxy Resin (A)>

[0042] The epoxy-based adhesive of the present application uses an epoxy resin (A) as a curing component, and as the epoxy resin (A), a bisphenol A type epoxy resin (Al), a bisphenol F type epoxy resin (A2), and a rubber-modified epoxy resin (A3) are included as essential constituent components.

[0043] The content ratio of the bisphenol A type epoxy resin (A1) to the bisphenol F type epoxy resin (A2) in the epoxy-based adhesive of the present application must be less than 2.7, preferably less than 2.5, particularly preferably less than 1.5, further preferably less than 1.0, especially preferably less than 0.9, and more preferably less than 0.8.

[0044] If the content ratio of (A1) to (A2) is 2.7 or more, the failure mode becomes interfacial peeling, and the effect of the present application cannot be sufficiently exhibited, and thus is not preferred.

[0045] It should be noted that the lower limit of the content ratio is not particularly limited, and for example, is 0.01 or more.

[0046] As the bisphenol A type epoxy resin (A1) used in the present application, for example, EPON 825, jER 826, jER 827, jER 828, jER 834, jER 1001 (all manufactured by Mitsubishi Chemical Corporation); EPICLON 850 (manufactured by DIC Corporation); Epotohto YD-128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.); DER-331, DER-332 (both manufactured by Dow Chemical Japan Co., Ltd.); Bakelite EPR154, Bakelite EPR162, Bakelite EPR172, Bakelite EPR173, Bakelite EPR174 (all manufactured by Bakelite AG); and the like can be exemplified. Among these, from the viewpoint of the modulus of elasticity and the glass transition temperature of the cured product of the epoxy-based adhesive, jER 828 and jER 1001 are preferred.

[0047] The bisphenol A type epoxy resin (A1) can be used alone or in combination with two or more kinds.

[0048] The number average molecular weight of the bisphenol A type epoxy resin (A1) is preferably 200 to 100,000, particularly preferably 200 to 80,000, and further preferably 200 to 60,000.

[0049] If the number average molecular weight is too low, there is a tendency that the viscosity excessively decreases, and the handleability as an adhesive decreases. Even if the number average molecular weight is too high, there is a tendency that the solubility in other monomers decreases and the viscosity excessively increases, and the handleability decreases.

[0050] It should be noted that in the present specification, the "number average molecular weight" is a polystyrene conversion value measured by a gel permeation chromatography (GPC) method.

[0051] The epoxy equivalent weight of the bisphenol A type epoxy resin (A1) is preferably 20,000 or less, particularly preferably 10,000 or less, and further preferably 6,000 or less.

[0052] If the epoxy equivalent weight is too high, there is a tendency that the solubility in other monomers decreases and the handleability at compounding decreases. The lower limit of the epoxy equivalent weight is not particularly limited, and is, for example, 50 or more.

[0053] Note that, in the present specification, the "epoxy equivalent weight" is a value measured in accordance with JIS-K7236:2001.

[0054] The softening point of the bisphenol A type epoxy resin (A1) is preferably 160°C or less, particularly preferably 140°C or less, and further preferably 120°C or less.

[0055] If the softening point is too high, the viscosity at ordinary temperature after compounding increases, and thus there is a tendency that the handleability as an adhesive decreases. The lower limit of the softening point is not particularly limited, and is, for example, -50°C or more.

[0056] Note that, in the present specification, the "softening point" is a value measured in accordance with JIS-K7234:2008 (ring and ball method).

[0057] As the bisphenol F type epoxy resin (A2) used in the present application, for example, jER806, jER807, jER4005P, jER4007P, jER4010P, jER1750 (all of which are manufactured by Mitsubishi Chemical Corporation); EPICLON 830 (manufactured by DIC Corporation); Epotohto YD-170, Epotohto YD-175 (all of which are manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.); Bakelite EPR169 (manufactured by Bakelite AG); GY281, GY282, GY285 (all of which are manufactured by Huntsman Advanced Materials); and the like, which are commercially available, can be exemplified. Among these, from the viewpoint that the epoxy-based adhesive is excellent in adhesion after curing, jER806, jER807, and jER4005P are preferable.

[0058] The bisphenol F type epoxy resin (A2) can be used alone or in combination of two or more.

[0059] The number average molecular weight of the bisphenol F type epoxy resin (A2) is preferably 200 to 100,000, particularly preferably 200 to 80,000, and further preferably 200 to 60,000.

[0060] If the number average molecular weight is too low, there is a tendency that the operability as an adhesive decreases due to excessive decrease in viscosity. Even if the number average molecular weight is too high, there is a tendency that the operability decreases due to excessive increase in viscosity and decrease in solubility in other monomers.

[0061] The epoxy equivalent of the bisphenol F type epoxy resin (A2) is preferably 20,000 or less, particularly preferably 10,000 or less, and further preferably 6,000 or less.

[0062] If the epoxy equivalent is too high, there is a tendency that the solubility in other monomers decreases and the operability at the time of compounding decreases. The lower limit of the epoxy equivalent is not particularly limited, and is, for example, 50 or more.

[0063] The softening point of the bisphenol F type epoxy resin (A2) is preferably 160°C or less, particularly preferably 140°C or less, and further preferably 120°C or less.

[0064] If the softening point is too high, the viscosity at ordinary temperature after compounding increases, and thus there is a tendency that the operability as an adhesive decreases. The lower limit of the softening point is not particularly limited, and is, for example, -50°C or more.

[0065] In addition to the above-mentioned substances, a commercially available product in which both the bisphenol A type epoxy resin (Al) and the bisphenol F type epoxy resin (A2) are mixed can also be used. As the commercially available product, for example, jER4250, jER4275 (manufactured by Mitsubishi Chemical Corporation), and the like can be mentioned.

[0066] As the rubber-modified epoxy resin (A3) used in the present application, for example, an epoxy-terminated adduct of an epoxy resin and at least one non-crosslinking liquid rubber having an epoxy-reactive group (for example, an amino group or a carboxyl group) is used.

[0067] The rubber-modified epoxy resin (A3) can be used alone or in combination of two or more.

[0068] As the epoxy resin used as a raw material of the rubber-modified epoxy resin (A3), there is no particular limitation, and for example, a bisphenol type epoxy resin, a naphthalene type epoxy resin, a biphenyl type epoxy resin, a glycidyl amine type epoxy resin, a cyclic type epoxy resin, a dicyclopentadiene type epoxy resin, a phenol novolac type epoxy resin, an o-cresol novolac type epoxy resin, and the like can be mentioned.

[0069] The non-crosslinking liquid rubber used as a raw material of the rubber-modified epoxy resin (A3) is preferably a homopolymer of a conjugated diene or a copolymer of a conjugated diene, and particularly preferably a diene / nitrile copolymer. The conjugated diene rubber is preferably butadiene or isoprene, and particularly preferably butadiene. The preferred nitrile monomer is acrylonitrile. The preferred copolymer is a butadiene-acrylonitrile copolymer.

[0070] The non-crosslinked liquid rubber preferably has a glass transition temperature (Tg) of 20°C or lower, more preferably 10°C or lower, and further preferably 0°C or lower. The lower limit of the glass transition temperature is not particularly limited, and is, for example, -100°C or higher.

[0071] Note that, in the present specification, the "glass transition temperature" is represented by the temperature of the inflection point of a DSC curve of a sample measured using a differential scanning calorimeter.

[0072] The non-crosslinked liquid rubber preferably has an average of 1.5 to 2.5, more preferably an average of 1.8 to 2.2, of epoxide-reactive terminal groups per 1 molecule.

[0073] The number average molecular weight of the non-crosslinked liquid rubber is preferably 500 to 10,000, and more preferably 1,000 to 58,000.

[0074] As the rubber-modified epoxy resin (A3), a carboxyl-terminated butadiene nitrile rubber (CTBN)-modified epoxy resin, a nitrile butadiene rubber (NBR)-modified epoxy resin, and more preferably a carboxyl-terminated butadiene nitrile rubber (CTBN)-modified epoxy resin are preferred.

[0075] As the commercially available rubber-modified epoxy resin (A3), for example, ADEKA RESIN EPR series (EPR-1415-1, EPR-2000, EPR-2007, EPR-1630) manufactured by ADEKA Co., Ltd.; EPON Resin 58005, EPON Resin 58006 manufactured by Momentive; Hypox series (Hypox RA840, Hypox RA1340, Hypox RF1341) manufactured by CVC can be exemplified. Among these, from the viewpoint of adhesion and excellent elastic modulus after curing, the ADEKA RESIN EPR series manufactured by ADEKA Co., Ltd. is preferred, and EPR-1630 is more preferred.

[0076] The number average molecular weight of the rubber-modified epoxy resin (A3) is preferably 200 to 200,000, particularly preferably 200 to 100,000, and further preferably 200 to 80,000.

[0077] If the number average molecular weight is too low, there is a tendency that the viscosity excessively decreases and the handleability as an adhesive decreases, and even if the number average molecular weight is too high, there is a tendency that the solubility in other monomers decreases and the viscosity excessively increases, and the handleability decreases.

[0078] The epoxy equivalent of the rubber-modified epoxy resin (A3) is preferably 10,000 or less, particularly preferably 7,000 or less, and further preferably 5,000 or less.

[0079] If the epoxy equivalent is too high, the soft component does not disperse in the cured product, and thus there is a tendency for stress to concentrate in this portion and for the adhesive strength to decrease. The lower limit of the epoxy equivalent is not particularly limited, and is, for example, 50 or more.

[0080] The softening point of the rubber-modified epoxy resin (A3) is preferably 200°C or less, particularly preferably 180°C or less, and further preferably 160°C or less.

[0081] If the softening point is too high, the viscosity at normal temperature after compounding increases, and thus there is a tendency for the workability as an adhesive to decrease. The lower limit of the softening point is not particularly limited, and is, for example, -50°C or more.

[0082] In the present application, from the viewpoints of low water absorption and the elastic modulus and glass transition temperature of the cured product, it is preferable to further use an aromatic ring-containing epoxy resin (A4) that is in a solid state at normal temperature (which does not include the bisphenol A-type epoxy resin (Al), the bisphenol F-type epoxy resin (A2), and the rubber-modified epoxy resin (A3)), and examples thereof include a phenol aralkyl-type epoxy resin (as a commercial product, "YX7700" manufactured by Mitsubishi Chemical Corporation), a biphenyl-type epoxy resin (as a commercial product, "YX4000" manufactured by Mitsubishi Chemical Corporation), and the like.

[0083] The aromatic ring-containing epoxy resin (A4) that is in a solid state at normal temperature can be used alone or in combination with two or more.

[0084] The number average molecular weight of the aromatic ring-containing epoxy resin (A4) that is in a solid state at normal temperature is preferably 200 to 100,000, particularly preferably 200 to 80,000, and further preferably 200 to 60,000.

[0085] If the number average molecular weight is too low, there is a tendency for the workability as an adhesive to decrease due to excessive decrease in viscosity, and even if the number average molecular weight is too high, there is a tendency for the workability to decrease due to decrease in solubility in other monomers and excessive increase in viscosity.

[0086] The epoxy equivalent of the aromatic ring-containing epoxy resin (A4) that is in a solid state at normal temperature is preferably 10,000 or less, particularly preferably 7,000 or less, and further preferably 5,000 or less.

[0087] If the epoxy equivalent is too high, there is a tendency for the solubility in other monomers to decrease and for the workability at the time of compounding to decrease. The lower limit of the epoxy equivalent is not particularly limited, and is, for example, 50 or more.

[0088] The softening point of the epoxy resin containing an aromatic ring (A4) which is solid at ordinary temperature is preferably 160°C or lower, particularly preferably 140°C or lower, and further preferably 120°C or lower.

[0089] If the softening point is too high, there is a tendency that the viscosity at ordinary temperature after compounding increases and the handleability as an adhesive decreases. The lower limit of the softening point is not particularly limited, and is, for example, -50°C or higher.

[0090] The content of the epoxy resin (A) used in the present application is preferably 30 to 100 mass%, further preferably 40 to 100 mass%, and particularly preferably 50 to 100 mass%, relative to the entire epoxy-based adhesive.

[0091] The content of the bisphenol A type epoxy resin (Al) is preferably 0.01 to 70 mass%, further preferably 0.1 to 60 mass%, and particularly preferably 1 to 50 mass%, relative to the entire epoxy resin (A) (the total content of all the epoxy resins (A) contained in the epoxy-based adhesive).

[0092] The content of the bisphenol F type epoxy resin (A2) is preferably 1 to 70 mass%, further preferably 5 to 60 mass%, and particularly preferably 10 to 50 mass%, relative to the entire epoxy resin (A).

[0093] Further, in the case of a composition containing both the bisphenol A type epoxy resin (Al) and the bisphenol F type epoxy resin (A2), the content is calculated by dividing the composition into mass ratios. For example, in the case of a composition in which the bisphenol A type epoxy (Al) and the bisphenol F type epoxy (A2) are 1:1 and the content is 10 mass%, (Al) is calculated as 5 mass% and (A2) is calculated as 5 mass%.

[0094] The content of the rubber-modified epoxy resin (A3) is preferably 0.01 to 60 mass%, further preferably 1 to 50 mass%, and particularly preferably 5 to 40 mass%, relative to the entire epoxy resin (A).

[0095] Further, the content of the rubber-modified epoxy resin (A3) is preferably 0.01 to 55 mass%, further preferably 1 to 45 mass%, and particularly preferably 5 to 40 mass%, relative to the entire curing component other than the curing agent (B).

[0096] The content of the epoxy resin containing an aromatic ring (A4) which is solid at ordinary temperature is preferably 0 to 80 mass%, further preferably 1 to 70 mass%, and particularly preferably 5 to 60 mass%, relative to the entire epoxy resin (A).

[0097] The content ratio of the bisphenol A type epoxy resin (A1) to the rubber-modified epoxy resin (A3) [(A1) / (A3)] is preferably less than 3.0, particularly preferably less than 2.5, further preferably less than 2.0, and especially preferably less than 1.5. If the content ratio [(A1) / (A3)] is too high, there is a tendency that the failure mode becomes interfacial peeling, and thus it is not preferable.

[0098] Note that the lower limit value of the content ratio is not particularly limited, and is, for example, 0.01 or more.

[0099] Further, the epoxy-based adhesive of the present application is also preferably such that the content of the bisphenol A type epoxy resin (A1) is less than the content of the bisphenol F type epoxy resin (A2), and the content of the bisphenol A type epoxy resin (A1) is less than 1.5 times the content of the rubber-modified epoxy resin (A3).

[0100] The epoxy-based adhesive of the present application can further contain other epoxy resins than (A1) to (A4). As specific examples thereof, various epoxy resins such as alcohol type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl type epoxy resins, biphenyl type epoxy resins, triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, polyfunctional phenol type epoxy resins, and aliphatic epoxy resins can be exemplified.

[0101] The epoxy resin (A) used in the present application preferably contains 50% by mass or more of an epoxy resin which is solid at ordinary temperature, particularly preferably 55% by mass or more, and further preferably 60% by mass or more, relative to the entire epoxy resin (A). The upper limit value of the content of the epoxy resin which is solid at ordinary temperature is not particularly limited, and is, for example, 100% by mass or less.

[0102] <Curative (B)>

[0103] As the curative (B) used in the present application, for example, amines, acid anhydrides (carboxylic anhydrides), phenols (novolac resins, etc.), mercaptans, Lewis acid amine complexes, onium salts, imidazoles, and the like can be exemplified. As specific examples thereof, the curatives described in Chapter 3 of "Review of Epoxy Resins Vol. 1 (Epoxy Resin Technical Association, First Edition, issued in November 2003)", Chapter 2 of "General Description of Epoxy Resins Latest Developments I (Epoxy Resin Technical Association, First Edition, issued in March 2009)" can be used. Among these, from the viewpoint of adhesiveness, amines are preferably used.

[0104] The curative (B) can be used alone, or two or more kinds thereof can be used in combination.

[0105] As the above-mentioned amine, aromatic amines such as diaminodiphenylmethane, diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, dicyandiamide, tetramethylguanidine, thiourea addition amine and isomers thereof, modified products, and the like can be exemplified. Among these, dicyandiamide is particularly preferable from the viewpoint of excellent shelf life of the base resin composition.

[0106] The content of the curing agent (B) used in the present application is preferably 0.01 to 30% by mass, further preferably 0.1 to 25% by mass, and particularly preferably 1 to 20% by mass, relative to the entire epoxy resin-based adhesive.

[0107] <Polymers having a core-shell structure (C)>

[0108] The epoxy-based adhesive of the present application can contain a polymer having a core-shell structure (C). The polymer having a core-shell structure (C) refers to a polymer particle in which the central portion (core portion) and the peripheral portion (shell portion) differ in molecular structure, which is well known.

[0109] As the component constituting the core portion of the polymer having a core-shell structure (C), butadiene rubber (BR), acrylic rubber (ACM), silicone rubber (Si), butyl rubber (IIR), nitrile rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), ethylene propylene rubber (EPR), and the like can be exemplified. Among these, butadiene rubber is preferable.

[0110] It is preferable that the component constituting the shell portion of the polymer having a core-shell structure (C) is grafted to the aforementioned core portion and covalently bonded to the polymer constituting the core component.

[0111] As the component constituting the shell portion, acrylate-based monomers, methacrylate-based monomers, and aromatic-based vinyl monomers, and the like can be exemplified.

[0112] The polymer having a core-shell structure (C) can be exemplified by, as commercially available products, KANE-ACE series (B-11A, B-22, B-561, FM-21, M-701, M-711, M-300, FM-40, M-210, Pa-20, PA101, MR-01, MX-153, MX-257, MX-154, MX-267, MX-960, MX-136, MX-965, MX-217, MX227M75, MX-334M75, MX-416, MX-451, and the like) manufactured by KANEKA Corporation; METABLEN (METABLEN C, METABLEN E, METABLEN W, METABLEN S, and the like) manufactured by Mitsubishi Chemical Corporation; and the like.

[0113] Among these, from the viewpoint of flexibility and adhesion, the core portion is preferably a microparticle of the rubber type. In addition, the polymer microparticle (C) can be used directly as a particulate substance, or a substance obtained by dispersing in another solution or resin, and from the viewpoint of uniformly dispersing in another resin, it is more preferable to disperse in an epoxy resin, and specifically, MX-153, MX-154, MX-136, and MX-267 are preferable.

[0114] The polymer microparticle (C) having a core-shell structure can be used alone or in combination with two or more.

[0115] From the viewpoint of the modulus of elasticity, elongation, and shear strength of the cured product obtained from the epoxy-based resin, the primary particle diameter of the polymer microparticle (C) having a core-shell structure used in the present application is preferably 10 to 100,000 nm, more preferably 15 to 50,000 nm, and particularly preferably 20 to 10,000 nm.

[0116] Note that the primary particle diameter indicates the volume average particle diameter of primary particles, and can be measured using, for example, a NANOTRAC particle size distribution measuring device (manufactured by Nikkiso Co., Ltd.).

[0117] Note that, regarding the polymer microparticle (C) having a core-shell structure, when a dispersion of a bisphenol A-type epoxy (A1) or a bisphenol F-type epoxy (A2) is used, the content ratio of (A1) / (A2) and (A1) / (A3) is calculated by adding (A1) and (A2) used for dispersion.

[0118] The content of the polymer microparticle (C) having a core-shell structure is preferably 0 to 50% by mass, further preferably 1 to 40% by mass, and particularly preferably 2 to 30% by mass, relative to the entire epoxy-based adhesive excluding the curing agent (B).

[0119] From the viewpoint of improving the curing activity of the curing agent (B), the epoxy-based adhesive of the present application can contain a curing accelerator (D). For example, among the curing agents (B), dicyandiamide and the like have a high curing temperature by themselves, and thus a curing accelerator (D) can be used in order to improve the curing activity of dicyandiamide and the like. As the curing accelerator for dicyandiamide, urea derivatives such as 3-phenyl-l,l-dimethylurea, 3-(3,4-dichlorophenyl)-l,l-dimethylurea (DCMU), 2,4-diamino-6-(2-methylimidazolyl-(l))-ethyl-s-triazine, 3-(3-chloro-4-methylphenyl)-l,l-dimethylurea, 4,4-methylenebis(l,l-dimethyl-3-phenylurea), 2,4-bis(3,3-dimethylureido)toluene, imidazole derivatives, and the like can be exemplified. Among these, urea derivatives are preferred, and 2,4-diamino-6-(2-methylimidazolyl-(l))-ethyl-s-triazine is more preferred.

[0120] The content of the curing accelerator (D) used in the present application is preferably 0.01 to 30% by mass, further preferably 0.05 to 25% by mass, and particularly preferably 0.1 to 20% by mass, relative to the total of the curing agent (B) and the curing accelerator (D).

[0121] <epoxy-based adhesive>

[0122] In the epoxy-based adhesive of the present application, three components of a bisphenol A type epoxy resin (Al), a bisphenol F type epoxy resin (A2), and a rubber-modified epoxy resin (A3) are contained as the epoxy resin (A), and a curing agent (B) is further contained as a necessary component, and a polymer microparticle (C) having a core-shell structure, a curing accelerator (D) are further preferably contained.

[0123] In addition, in the epoxy-based adhesive of the present application, other compounding components can be used as needed within a range not impairing the effects of the present application (for example, at a content of 5% by mass or less relative to the entire epoxy-based adhesive). As the other compounding components, dehydrating agents such as calcium oxide; colorants such as pigments and dyes; extender pigments, ultraviolet absorbers, antioxidants, stabilizers (anti-gelling agents), plasticizers, leveling agents, defoaming agents, silane coupling agents, antistatic agents, flame retardants, lubricants, thickeners, low shrinkage agents, organic filler agents, inorganic filler agents, thermoplastic resins, drying agents, dispersants, and the like can be exemplified.

[0124] In the adhesion of different kinds of materials, the epoxy-based adhesive of the present application is preferably in a solid state at ordinary temperature from the viewpoint of preventing liquid sagging at the time of adhesion.

[0125] On the other hand, from the viewpoint of smooth adhesion to the adherend, the softening point of the epoxy-based adhesive is preferably 160°C or lower, more preferably 140°C or lower, and particularly preferably 120°C or lower. The lower limit of the softening point is not particularly limited, and is, for example, 30°C or higher.

[0126] The viscosity of the epoxy-based adhesive of the present application at 60°C under 1 atm is preferably 0.01 to 20,000 Pa-s, particularly preferably 0.01 to 10,000 Pa-s, further preferably 0.01 to 8,000 Pa-s, and more preferably 0.01 to 5,000 Pa-s. In addition, the viscosity is preferably 0.05 to 4,000 Pa-s, and can be 0.1 to 3,000 Pa-s, 1 to 1,000 Pa-s, or 10 to 800 Pa-s.

[0127] The viscosity is too high or too low, and there is a tendency that the coatability on the substrate when used as an adhesive is reduced.

[0128] Note that the viscosity is measured at 60°C using a B-type rotational viscometer (Brookfield viscometer) in accordance with JIS Z 8803.

[0129] The epoxy-based adhesive of the present application is suitably used for adhesion of different kinds of materials. As the combination of different kinds of materials, there are no particular limitations, and combinations of two kinds of various materials selected from hot-rolled steel sheets, cold-rolled steel sheets, high-tension steel sheets, stainless steel sheets, plated steel sheets (zinc-plated steel sheets, zinc-nickel steel sheets, etc.), aluminum sheets, aluminum alloy sheets (aluminum-manganese alloy sheets, aluminum-magnesium alloy sheets, etc.), carbon fibers, glass fibers, and fiber-reinforced plastic (FRP) sheets, carbon fiber-reinforced plastic (CFRP), etc. can be given. Among them, the epoxy-based adhesive of the present application is suitably used for adhesion of different kinds of metals and CFRP. Among different kinds of metals, adhesion of metals mainly composed of iron and aluminum is particularly preferable.

[0130] <Method for producing epoxy-based adhesive>

[0131] The epoxy-based adhesive of the present application can be produced by mixing the components.

[0132] The mixing method of the above components is preferably performed with heating to liquefy a part of the epoxy resin and the liquefiable component and mix them, and the mixing temperature is preferably 30°C or higher, more preferably 40°C or higher, and particularly preferably 50°C or higher. On the other hand, it is preferably 150°C or lower, more preferably 140°C or lower, and particularly preferably 120°C or lower. If the mixing temperature is lower than the lower limit, there is a tendency that the mixing is not good due to solidification of the components, and if it exceeds the upper limit, there is a tendency that the mixture is gelled by polymerization during the mixing.

[0133] The mixing time is usually 1 minute or more, preferably 10 minutes or more, and particularly preferably 20 minutes or more, and is usually 24 hours or less, preferably 18 hours or less, and particularly preferably 12 hours or less. If the mixing time is less than the lower limit, there is a tendency for the mixture to not be uniformly mixed, and if it exceeds the upper limit, there is a tendency for the mixture to gel due to polymerization during mixing.

[0134] The mixing method of the above components can use various methods for applying shear force, such as stirring, shaking, kneading, and the like, which are generally used for mixing epoxy adhesives. The mixing method is variously selected depending on the physical properties, production amount, and the like of the adhesive.

[0135] The state of the obtained epoxy adhesive can be a uniform state, or a non-uniform state in which particles are dispersed. The state is variously selected depending on the use of the adhesive.

[0136] From the viewpoint of handling, the epoxy adhesive of the present application is preferably a one-component type adhesive.

[0137] With regard to the epoxy adhesive of the present application, by applying the epoxy adhesive of the present application to one or both of a plurality of members that differ in linear expansion coefficient, and then adhering the members with the adhesive interposed therebetween, and then allowing the adhesive to cure, a laminate in which the different members are joined can be obtained.

[0138] As the curing conditions, there is no particular limitation, and for example, in the case of using a one-component adhesive, by heating to a temperature of 80°C or higher, preferably 130°C or higher, and more preferably 150°C or higher, the adhesive is allowed to cure within 60 minutes or less, and more preferably 30 minutes or less, and a laminate in which different members are joined can be obtained.

[0139] <Adhesive sheet>

[0140] The epoxy adhesive of the present application can be suitably used as an adhesive sheet containing the epoxy adhesive, and particularly preferably an adhesive sheet for adhering different materials.

[0141] The adhesive sheet containing the epoxy adhesive of the present application can be, for example, an adhesive sheet having an adhesive layer obtained using the aforementioned epoxy adhesive on a base film, or can have an adhesive layer obtained by impregnating the aforementioned epoxy adhesive in a support.

[0142] In the case of providing an adhesive layer containing the aforementioned epoxy adhesive on a base film, as the base film, for example, a release film subjected to a release treatment with silicone, melamine, or the like is preferably used, and specifically, a PET film subjected to a release treatment, a polyethylene film, a polypropylene film, a fluorine film, a polyimide film, and the like can be used.

[0143] In addition, in the case where the aforementioned epoxy-based adhesive is impregnated into the support body, as the support body, for example, nonwoven fabric, porous material, or the like can be used, of which nonwoven fabric is preferred.

[0144] From the viewpoint of inhibiting the flow of resin under pressure when a plurality of members are bonded, the retention of resin in the sheet-like adhesive form, and improving the adhesion that accompanies the rigidity of the adhesive layer, the density of the support body is preferably 0.05 g / cm3or more, more preferably 0.08 g / cm3or more, and further preferably 0.1 g / cm3or more. 3 More preferably, 0.08 g / cm3or more 3 Further preferably, 0.1 g / cm3or more 3 or more.

[0145] In addition, from the viewpoint of improving the impregnation of resin in the support body in the adhesive sheet, improving the lightweight property, and improving the interfacial adhesion, 1.0 g / cm3or more, more preferably 0.9 g / cm3or more, and further preferably 0.8 g / cm3or more is preferred. 3 More preferably, 0.9 g / cm3or more 3 Further preferably, 0.8 g / cm3or more 3 or more.

[0146] The thickness of the adhesive layer in the adhesive sheet is preferably 0.1 to 2.0 mm. By making the thickness of the adhesive layer within the above numerical range, the adhesion when bonding a plurality of members having different linear expansion coefficients is good and warpage can be reduced.

[0147] The thickness of the adhesive layer is preferably 0.2 mm or more, more preferably 0.3 mm or more, and further preferably 0.4 mm or more.

[0148] In addition, from the aspect that the higher the thickness of the adhesive layer, the higher the tensile shear adhesive strength after bonding, the thickness of the adhesive layer is preferably 1.8 mm or less, more preferably 1.6 mm or less, and further preferably 1.4 mm or less.

[0149] The adhesive sheet can be obtained by molding the epoxy-based adhesive into a sheet shape.

[0150] As a method of molding into a sheet shape, a method in which the aforementioned epoxy-based adhesive is laminated or coated on a base film to obtain a laminate of base film / epoxy-based adhesive / base film can be exemplified. Specifically, a method using an extrusion laminator such as a T-die, a roll, a double belt press, or the like, a sheet molding device, a comma coater method, a gravure coater method, a reverse coater method, a knife coater method, a dip coater method, a spray coater method, an air knife coater method, a spin coater method, a roll coater method, a printing method, an immersion method, a slide coater method, a curtain coater method, a die coater method, a flow casting method, a bar coater method, an extrusion coater method, or the like can be exemplified.

[0151] In the aforementioned sheet molding, an impregnation process in which the aforementioned epoxy-based adhesive is impregnated into the support body can be performed.

[0152] The impregnation method of the aforementioned epoxy-based adhesive in the impregnation step can be performed by a publicly known method. As the impregnation method, there can be listed a lamination method in which, for example, an object obtained by providing the aforementioned epoxy-based adhesive on the substrate film in the aforementioned sheet formation step is laminated with a support body in a manner of forming a substrate film / epoxy-based adhesive / support body / epoxy-based adhesive / substrate film, and impregnation is performed using a vacuum laminator, a roll, double belt pressurization, or the like; an impregnation / roll point method, a kiss coating method, a spray method, a curtain coating method, or the like in which the aforementioned epoxy-based adhesive is directly impregnated into the support body.

[0153] The thickness of the support body and the amount of the epoxy-based adhesive impregnated into the support body are preferably adjusted in a manner such that the thickness of the adhesive layer becomes 0.1 to 2.0 mm.

[0154] The laminate obtained using the epoxy-based adhesive of the present application can be used as a structural member (a panel member, a skeleton member, a floor member, or the like) of a transportation device such as a vehicle, an airplane, a ship, or the like, and is particularly preferably used as a structural panel, and is particularly useful as a structural panel for a vehicle.

[0155] Examples

[0156] Hereinafter, the present application will be more specifically described by way of examples, but the present application is not limited to the following examples as long as the gist thereof is not exceeded. In addition, "parts" and "%" refer to mass basis.

[0157] First, each of the constituent components of the adhesive epoxy resin composition used in the examples and comparative examples was prepared.

[0158] < Epoxy Resin (A) >

[0159] • Epoxy Resin 1: Bisphenol A type epoxy resin (Al-1) ("jER1001" manufactured by Mitsubishi Chemical Corporation, room temperature solid state)

[0160] • Epoxy Resin 2: Bisphenol F type epoxy resin (A2-1) ("jER807" manufactured by Mitsubishi Chemical Corporation, room temperature liquid state)

[0161] • Epoxy Resin 3: Bisphenol F type epoxy resin (A2-2) ("jER4005P" manufactured by Mitsubishi Chemical Corporation, room temperature solid state)

[0162] • Epoxy Resin 4: Bisphenol A type epoxy resin (Al-2) (room temperature liquid state) 15% dispersion product ("EPR-1630" manufactured by ADEKA Corporation) of rubber-modified (CTBN-modified) epoxy resin (A3) (room temperature solid state) [rubber-modified epoxy resin (A3): bisphenol A type epoxy resin (Al-2) = 85: 15]

[0163] • Epoxy resin 5: phenol aralkyl type epoxy resin (A4-1) (manufactured by Mitsubishi Chemical Corporation, "YX7700", room temperature solid)

[0164] • Epoxy resin 6: biphenyl type epoxy resin (A4-2) (manufactured by Mitsubishi Chemical Corporation, "YX4000", room temperature solid)

[0165] <Curative (B)>

[0166] • Curative (B-1): dicyandiamide (manufactured by Mitsubishi Chemical Corporation, "DUCY7")

[0167] <Core-shell structured polymer fine particles (C)>

[0168] • Core-shell structured polymer fine particles 1: bisphenol A type epoxy resin (A1-3) (room temperature liquid) 60% dispersion of core-shell rubber (C-1) (manufactured by KANEKA Corporation, "Kane Ace MX-154") [core-shell structured polymer fine particles (C-1): bisphenol A type epoxy resin (A1-3) = 40:60]

[0169] • Core-shell structured polymer fine particles 2: bisphenol A type epoxy resin (A1-4) (room temperature liquid) 3% and bisphenol F type epoxy resin (A2-3) (room temperature liquid) 59% dispersion of core-shell rubber (C-2) (manufactured by KANEKA Corporation, "KANE-ACE MX-267") [core-shell structured polymer fine particles (C-2): bisphenol A type epoxy resin (A1-4): bisphenol F type epoxy resin (A2-3) = 38:3:59]

[0170] <Curative accelerator (D)>

[0171] • Curative accelerator (D-1): 2,4-diamino-6-(2-methylimidazolyl-(1))-ethyl-sym-triazine (manufactured by Shikoku Chemicals Corporation, "2MZA-PW")

[0172] <Manufacture of epoxy-based adhesive>

[0173] [Example 1]

[0174] After mixing epoxy resin 2 20 parts, epoxy resin 3 10 parts, epoxy resin 4 20 parts, epoxy resin 5 40 parts, and core-shell structured polymer fine particles 1 10 parts, the mixture was stirred at 90°C until uniform. After the resin temperature was made 70°C by being put into a constant temperature bath at 70°C, curative (B-1) 8 parts and curative accelerator (D-1) 2 parts were further added, and stirred until uniformly dispersed, to obtain an adhesive. The adhesive of Example 1 was a solid at room temperature. In addition, the viscosity at 60°C was 160 Pa-s.

[0175] [Example 2]

[0176] After mixing epoxy resin 2 10 parts, epoxy resin 3 10 parts, epoxy resin 4 20 parts, epoxy resin 5 40 parts, and polymer microparticles 2 20 parts having a core-shell structure, the mixture was stirred at 90°C until uniform. The mixture was then placed in a constant-temperature bath at 70°C, and after the resin temperature was brought to 70°C, curing agent (B-1) 8 parts and curing accelerator (D-1) 2 parts were further added, and the mixture was stirred until uniformly dispersed, to obtain an adhesive. The adhesive of Example 2 was solid at room temperature.

[0177] [Example 3]

[0178] After mixing epoxy resin 2 10 parts, epoxy resin 3 10 parts, epoxy resin 4 20 parts, epoxy resin 6 40 parts, and polymer microparticles 2 20 parts having a core-shell structure, the mixture was stirred at 90°C until uniform. The mixture was then placed in a constant-temperature bath at 70°C, and after the resin temperature was brought to 70°C, curing agent (B-1) 8 parts and curing accelerator (D-1) 2 parts were further added, and the mixture was stirred until uniformly dispersed, to obtain an adhesive. The adhesive of Example 3 was solid at room temperature.

[0179] [Example 4]

[0180] After mixing epoxy resin 2 10 parts, epoxy resin 3 10 parts, epoxy resin 4 40 parts, epoxy resin 5 30 parts, and polymer microparticles 1 10 parts having a core-shell structure, the mixture was stirred at 90°C until uniform. The mixture was then placed in a constant-temperature bath at 70°C, and after the resin temperature was brought to 70°C, curing agent (B-1) 8 parts and curing accelerator (D-1) 2 parts were further added, and the mixture was stirred until uniformly dispersed, to obtain an adhesive. The adhesive of Example 4 was solid at room temperature.

[0181] [Example 5]

[0182] After mixing epoxy resin 2 10 parts, epoxy resin 3 10 parts, epoxy resin 4 20 parts, epoxy resin 5 40 parts, and polymer microparticles 1 20 parts having a core-shell structure, the mixture was stirred at 90°C until uniform. The mixture was then placed in a constant-temperature bath at 70°C, and after the resin temperature was brought to 70°C, curing agent (B-1) 8 parts and curing accelerator (D-1) 2 parts were further added, and the mixture was stirred until uniformly dispersed, to obtain an adhesive. The adhesive of Example 5 was solid at room temperature.

[0183] [Example 6]

[0184] The epoxy resin 1 15 parts, the epoxy resin 2 5 parts, the epoxy resin 4 25 parts, the epoxy resin 5 40 parts, and the polymer microparticles 2 15 parts having a core-shell structure were mixed, and stirred at 90°C until uniform. This was put into a constant-temperature bath at 70°C, and after the resin temperature was made to be 70°C, a curing agent (B-1) 8 parts and a curing accelerator (D-1) 2 parts were further added, and stirred until uniformly dispersed, to obtain an epoxy resin composition for an adhesive. The adhesive of Example 6 was in a solid state at ordinary temperature.

[0185] [Example 7]

[0186] The epoxy resin 1 20 parts, the epoxy resin 2 20 parts, the epoxy resin 4 20 parts, the epoxy resin 5 20 parts, and the polymer microparticles 2 20 parts having a core-shell structure were mixed, and stirred at 90°C until uniform. This was put into a constant-temperature bath at 70°C, and after the resin temperature was made to be 70°C, a curing agent (B-1) 8 parts and a curing accelerator (D-1) 2 parts were further added, and stirred until uniformly dispersed, to obtain an epoxy resin composition for an adhesive.

[0187] The adhesive of Example 7 was in a solid state at ordinary temperature.

[0188] [Example 8]

[0189] The epoxy resin 1 20 parts, the epoxy resin 2 20 parts, the epoxy resin 4 20 parts, the epoxy resin 5 20 parts, and the polymer microparticles 2 20 parts having a core-shell structure were mixed, and stirred at 90°C until uniform. This was put into a constant-temperature bath at 70°C, and after the resin temperature was made to be 70°C, a curing agent (B-1) 8 parts and a curing accelerator (D-1) 2 parts were further added, and stirred until uniformly dispersed, to obtain an epoxy resin composition for an adhesive.

[0190] The adhesive of Example 8 was in a solid state at ordinary temperature.

[0191] [Example 9]

[0192] The epoxy resin 1 25 parts, the epoxy resin 2 20 parts, the epoxy resin 4 15 parts, the epoxy resin 5 20 parts, and the polymer microparticles 2 20 parts having a core-shell structure were mixed, and stirred at 90°C until uniform. This was put into a constant-temperature bath at 70°C, and after the resin temperature was made to be 70°C, a curing agent (B-1) 8 parts and a curing accelerator (D-1) 2 parts were further added, and stirred until uniformly dispersed, to obtain an epoxy resin composition for an adhesive.

[0193] The adhesive of Example 9 was in a solid state at ordinary temperature.

[0194] [Comparative Example 1]

[0195] 2.5 parts epoxy resin, 20 parts epoxy resin, 5.55 parts epoxy resin, and 1.20 parts polymer microparticles with a core-shell structure were mixed and stirred at 90°C until homogeneous. The mixture was then placed in a constant temperature bath at 70°C. After the resin temperature reached 70°C, 8 parts curing agent (B-1) and 2 parts curing accelerator (D-1) were added, and the mixture was stirred until uniformly dispersed to obtain the adhesive. The adhesive of Comparative Example 1 is solid at room temperature.

[0196] [Comparative Example 2]

[0197] 10 parts of epoxy resin 3, 20 parts of epoxy resin 4, 30 parts of epoxy resin 5, and 40 parts of polymer microparticles with a core-shell structure were mixed and stirred at 90°C until homogeneous. The mixture was then placed in a constant temperature bath at 70°C. After the resin temperature reached 70°C, 8 parts of curing agent (B-1) and 2 parts of curing accelerator (D-1) were added, and the mixture was stirred until uniformly dispersed to obtain the adhesive. The adhesive of Comparative Example 2 is solid at room temperature.

[0198] The compositions of the adhesives obtained in Examples 1-9 and Comparative Examples 1-2 are shown in Table 1. It should be noted that the contents expressed in Table 1 are values ​​obtained by rounding the first decimal place, and the contents ratios of [(A1) / (A2)] and [(A1) / (A3)] shown in Table 1 are values ​​obtained by rounding the third decimal place of the values ​​calculated based on the contents recorded in Table 1.

[0199] The adhesives obtained in Examples 1-9 and Comparative Examples 1-2 were used to perform the following shear bond strength tests. The results are shown in Table 1.

[0200] <Shear Adhesion Strength Measurement>

[0201] Shear bond strength was determined using Al (aluminum) test pieces ("Standard Test Piece Al5052P" manufactured by Nippon Testpanel) and Fe (SPCC steel plate) test pieces ("Standard Test Piece SPCC-SB" manufactured by Nippon Testpanel) by the following method.

[0202] The adhesive obtained above was applied to the surface of the Fe test piece (12.5mm × 25mm × 1.6mm thickness) with a thickness of approximately 0.8mm, and then the thickness was adjusted using spacers on top. Subsequently, an Al test piece (12.5mm × 25mm × 1.6mm thickness) was overlapped on top, and the two test pieces were clamped together using two adhesive clamps (Lion Corporation "No. 107") to press them together and fix the Al / Fe thickness.

[0203] After the pressure bonding, a curing treatment was performed by using a hot air drying oven at 130°C for 20 minutes to obtain a sample for measurement.

[0204] After cooling to room temperature (25°C), the tensile shear force was measured for the sample for measurement using a tensile testing machine ("Autograph AG-X" manufactured by Shimadzu Corporation) in accordance with JIS K6850. Note that the measurement was performed under conditions where the test speed was 5 mm / minute and the test environment was 23°C, 50% RH.

[0205] (Evaluation Criteria for Adhesion)

[0206] The adhesion was evaluated based on the tensile shear force and the failure mode.

[0207] The results of the tensile shear test were evaluated using the value of the maximum breaking point of the tensile testing machine, and the case where the tensile shear force was "15 MPa or more" and the failure mode was "cohesive failure" was regarded as O (excellent), the case where the tensile shear force was "15 MPa or more" and the failure mode was "partial cohesive failure" was regarded as Δ (good), and the case where the tensile shear force was "less than 15 MPa" or the failure mode was "interfacial peeling" was regarded as X (poor).

[0208] Note that the failure mode was confirmed by visual observation and tactile sensation for the bonded surface of the peeled Al test piece and Fe test piece, and, with respect to the area to which the test pieces were bonded, it was determined to be cohesive failure if 60% or more of the area of both test pieces was adhered with the cured adhesive, partial cohesive failure if 3% or more and less than 60% of the area of either test piece was adhered with the adhesive, and interfacial peeling if less than 3% of the area of either test piece was adhered with the adhesive.

[0209] (Evaluation of Sheetability)

[0210] Whether or not the adhesive obtained in the above Examples 1 to 9 and Comparative Examples 1 to 2 was suitable for sheeting was confirmed by the following method. The results are shown in Table 1.

[0211] The adhesive obtained in the above Examples 1 to 9 and Comparative Examples 1 to 2 was filled in a mayonnaise bottle (size: No. 3K). At this time, the adhesive was made to have a height of 1 to 3 cm from the bottom of the mayonnaise bottle. Thereafter, the mayonnaise bottle filled with the adhesive was inverted with the mouth of the mayonnaise bottle facing downward, maintained for 30 seconds, and returned to the original state. Thereafter, the case where there was a trace of liquid run-off to 1.2 times or more the height at which the adhesive was filled was determined to be liquid run-off, and the sheetability was evaluated as X (poor). On the other hand, if it was less than 1.2 times the height at which the adhesive was filled, it was determined that there was no liquid run-off, and the sheetability was evaluated as O (good).

[0212] [Table 1]

[0213]

[0214] As shown in Table 1, the tensile shear force of the adhesive layers obtained by curing the adhesives of Examples 1 to 9 is 15 MPa or more, and the failure mode is cohesive failure or partial cohesive failure. It can be considered that by setting the content ratio of bisphenol A type epoxy resin (A1) to bisphenol F type epoxy resin (A2) to a certain amount or less, the rigid skeleton of bisphenol A type (A1) is reduced and the flexible skeleton of bisphenol F type (A2) is increased, thereby improving the adhesion and flexibility. Therefore, high shear force is maintained and the failure mode becomes cohesive failure or partial cohesive failure.

[0215] On the other hand, it can be considered that in the adhesive layer obtained by curing the adhesives of Comparative Examples 1 to 2, the amount of bisphenol A type epoxy resin (A1) added is greater than that of bisphenol F type epoxy resin (A2), thus lacking flexibility and adhesion, and all of it becomes interfacial peeling.

[0216] <Making of Adhesive Sheets>

[0217] [Example 10]

[0218] The adhesive obtained in Example 1 was applied to a silicone-treated PET film as the substrate film, allowing it to impregnate the glass fiber nonwoven fabric (density 0.16 g / cm³). 3 (The thickness is 0.77mm). Insert another substrate film from the other side and use a laminator to make an adhesive sheet (the thickness of the adhesive sheet is 0.8mm).

[0219] Using the adhesive sheet obtained above, tensile shear force was measured according to the same method as described above. The adhesive sheet obtained using the epoxy adhesive of the present invention exhibits excellent tensile shear bond strength.

[0220] The above embodiments illustrate specific aspects of the present invention, but these embodiments are merely illustrative and not intended to be limiting. It is understood that various modifications that will be obvious to those skilled in the art fall within the scope of the present invention.

[0221] Industrial availability

[0222] The epoxy adhesive of the present invention can be used for structural components (frames, panel parts, etc.) of transportation equipment such as vehicles, aircraft, and ships, as well as components of buildings and building materials, and is particularly useful for structural components of vehicles.

Claims

1. An epoxy-based adhesive, characterized in that, It comprises epoxy resin (A), curing agent (B), and polymer microparticles (C) with a core-shell structure. As the epoxy resin (A), it comprises bisphenol A type epoxy resin (A1), bisphenol F type epoxy resin (A2), rubber modified epoxy resin (A3), and an aromatic ring-containing epoxy resin (A4) that is solid at 25°C, other than (A1) to (A3). The content ratio of bisphenol A type epoxy resin (A1) to bisphenol F type epoxy resin (A2) [(A1) / (A2)] is less than 2.

5. The content of the bisphenol A type epoxy resin (A1) is 0.1% to 60% by mass relative to the total epoxy resin (A). The content of the bisphenol F type epoxy resin (A2) relative to the total epoxy resin (A) is greater than 10% by mass and less than 50% by mass. The content of the rubber-modified epoxy resin (A3) is 1-50% by mass relative to the total epoxy resin (A). The content of the aromatic ring-containing epoxy resin (A4), which is solid at 25°C, is 1-70% by mass relative to the total epoxy resin (A). The content of epoxy resin that is solid at 25°C is 50% by mass or more relative to the total epoxy resin (A).

2. The epoxy adhesive according to claim 1, characterized in that, As the rubber-modified epoxy resin (A3), it contains at least one of carboxyl-terminated butadiene nitrile rubber-modified epoxy resin or nitrile butadiene rubber-modified epoxy resin.

3. The epoxy adhesive according to claim 1 or 2, characterized in that, The curing agent (B) contains dicyandiamide.

4. The epoxy adhesive according to claim 1 or 2, characterized in that, It is solid at 25°C.

5. The epoxy adhesive according to claim 1 or 2, characterized in that, The viscosity at 60℃ is 0.01~5000Pa·s.

6. The epoxy adhesive according to claim 1 or 2, characterized in that, It is used for bonding different types of materials.

7. An adhesive sheet, characterized in that, It comprises the epoxy adhesive according to any one of claims 1 to 6.

8. An adhesive sheet for bonding different materials, characterized in that, It comprises the epoxy adhesive as described in claim 6.

9. An adhesive sheet, characterized in that, It has an adhesive layer comprising an epoxy-based adhesive, the thickness of which is 0.1–2 mm. The epoxy adhesive comprises epoxy resin (A), curing agent (B), and polymer microparticles (C) having a core-shell structure. The epoxy resin (A) contains bisphenol A type epoxy resin (A1), bisphenol F type epoxy resin (A2), rubber-modified epoxy resin (A3), and an aromatic ring-containing epoxy resin (A4) that is solid at 25°C, excluding (A1) to (A3). The content ratio of bisphenol A type epoxy resin (A1) to bisphenol F type epoxy resin (A2) [(A1) / (A2)] is less than 2.

5. The content of the bisphenol A type epoxy resin (A1) is 0.1% to 60% by mass relative to the total epoxy resin (A). The content of the bisphenol F type epoxy resin (A2) relative to the total epoxy resin (A) is greater than 10% by mass and less than 50% by mass. The content of the rubber-modified epoxy resin (A3) is 1-50% by mass relative to the total epoxy resin (A). The content of the aromatic ring-containing epoxy resin (A4), which is solid at 25°C, is 1-70% by mass relative to the total epoxy resin (A). The content of epoxy resin that is solid at 25°C is 50% by mass or more relative to the total epoxy resin (A).

10. The adhesive sheet according to claim 9, characterized in that, The adhesive layer is formed from a nonwoven fabric impregnated with the epoxy adhesive.

11. The adhesive sheet according to claim 9 or 10, characterized in that, At least one surface of the adhesive layer has a release film.

Images