JP2013040299A - Adhesive composition and adhesive sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition that has initial adhesion, can bind metals together, the metal and an organic material together, and the organic materials together, and can keep its transparency after thermal curing.SOLUTION: The adhesive composition comprises at least: a bisphenol A-type epoxy resin and a bisphenol A-type phenoxy resin, as a resin component; a hydrazide-based curing agent as a curing agent; and xylylene diisocyanate as a crosslinking agent.

Description

  The present invention relates to an adhesive composition. More specifically, the present invention can bond metals, metal and organic material, organic material and organic material, has initial tackiness, and excellent transparency even after thermosetting. The present invention relates to an adhesive composition that can maintain the properties, and an adhesive sheet using the same.

Conventionally, as a joining method for integrating two adherends, there are occlusion, welding, and an adhesive method using an adhesive or a pressure-sensitive adhesive, and they are frequently used depending on the application in each field. In recent years, in applications related to transport equipment such as automobiles, as a solution to problems such as the reduction of carbon dioxide CO ₂ emissions in order to prevent global warming, the weight reduction of vehicle bodies and the spread of hybrid cars and electric cars have been promoted. Therefore, there is an increasing tendency to use lightweight aluminum, magnesium, and FRP (CFRP: Carbon Fiber Reinforced Plastics, GFRP: Glass Fiber Reinforced Plastics) for the vehicle body.

  By the way, in the conventional welding method, it is very difficult to weld different materials such as aluminum and iron, and it is impossible to weld the FRP of glass fiber or carbon fiber. Are required to have a welding and identification bond strength. As a bonding method between materials that cannot be bonded by welding or the like, there is a method using an adhesive, but as an adhesive for bonding such a material, metals, metals and organic materials, organic materials and organic materials are used. And the adhesive strength is required to be strong so that it can be used for structural applications. In addition, there is a demand for having initial tackiness, good workability without steps such as preheating.

  In general, a thermosetting resin such as an epoxy resin is used as an adhesive that satisfies the above requirements. However, the epoxy adhesive has a high mechanical strength of the resin itself after curing, but is inferior in toughness. When an epoxy adhesive is used for an aircraft, automobile, etc., a decrease in adhesive strength due to brittle fracture becomes a problem. There is a case. In order to solve such a problem, a pressure-sensitive adhesive sheet in which a thermoplastic resin or the like is added to an epoxy resin to make the epoxy adhesive flexible is proposed (for example, Japanese Patent Application Laid-Open No. 2003-82034).

  Among the above-mentioned adhesive sheet, a thermosetting adhesive sheet having an initial tack is also known. According to the adhesive sheet having initial tackiness, the adherends to be bonded can be temporarily bonded together, and then the adhesive can be thermally cured, so that the working efficiency is improved. These adhesive sheets having initial tack are generally obtained by adding an adhesive resin such as acrylic to an adhesive layer made of a thermosetting resin.

JP 2003-82034 A

  In the previous application (Japanese Patent Application No. 2010-219057), the present inventors have initial tackiness and can bond metals, metal and organic material, organic material and organic material, and undergo temperature change. The adhesive sheet can maintain excellent adhesive strength. The adhesive composition used for this adhesive sheet contains an acrylic resin and an epoxy resin as essential components.

  Since said adhesive sheet loses transparency after thermosetting, there is a problem that it cannot be used in applications where aesthetics are required for the appearance of the bonded laminate. The present inventors say that the whitening when the adhesive sheet is thermally cured is due to the difference in the refractive index of light at the interface between the sea part and the island part resulting from the sea-island structure of the acrylic resin and the epoxy resin. I got the knowledge.

  And now, it turns out that it replaces with the acrylic resin added to a specific epoxy resin, both resins are compatible by using a specific resin, and transparency is maintained after thermosetting. Furthermore, by combining these resins with a specific curing agent and a crosslinking agent, an adhesive sheet having initial tackiness and capable of adhering metal to metal, metal to organic material, and organic material to organic material is obtained. I got the knowledge that Accordingly, an object of the present invention is to provide an adhesive composition having initial tackiness and capable of bonding metals, metal and organic material, organic material and organic material, and maintaining transparency after thermosetting. Is to provide.

  Another object of the present invention is to provide an adhesive sheet using the above-described adhesive composition.

The adhesive composition according to the present invention includes a bisphenol A type epoxy resin and a bisphenol A type phenoxy resin as a resin component, and a hydrazide-based curing agent as a curing agent.
It is characterized by comprising at least xylylene diisocyanate as a crosslinking agent.

  Moreover, according to the aspect of the present invention, it is preferable that the blending ratio of the bisphenol A type epoxy resin and the bisphenol A type phenoxy resin is included in a ratio of 1: 0.5 to 1: 2 on a mass basis.

  Moreover, according to the aspect of the present invention, it is preferable that the bisphenol A type epoxy resin is composed of a bisphenol A type epoxy resin that is liquid at room temperature with a main chain of 1 to 3.

  Moreover, according to the aspect of this invention, it is preferable that the average weight molecular weights of the said bisphenol A type phenoxy resin are 30,000-100,000.

  Moreover, according to the aspect of this invention, it is preferable that 65-80 mass parts of the said resin component, 13-22 mass parts of said hardening | curing agents, and 5-15 mass parts of said hardening | curing agents are included.

  An adhesive sheet according to another aspect of the present invention is an adhesive sheet obtained by laminating a first release paper, an adhesive layer, and a second release paper in this order, and the adhesive layer is bonded to the adhesive sheet. It comprises an agent composition.

An adhesion method according to another aspect of the present invention is a method of adhering the first adherend and the second adherend using the adhesive sheet,
From the adhesive sheet, the first release paper and the second release paper are peeled and removed to expose the adhesive layer,
Sandwiching the adhesive layer between the first adherend and the second adherend, and temporarily fixing the first adherend and the second adherend,
The adhesive layer is cured by heating to bond the first adherend and the second adherend.

  Moreover, according to this invention, the bonding body obtained by said adhesion method is also provided.

  According to the adhesive composition of the present invention, the resin component contains bisphenol A type epoxy resin and bisphenol A type phenoxy resin, these resins, a hydrazide-based curing agent that is a curing agent, and xylylene diisocyanate that is a crosslinking agent. In combination, the adhesive composition has initial tackiness and can bond metals, metal and organic materials, organic materials and organic materials, and maintain transparency even after thermosetting. it can.

1 is a schematic cross-sectional view according to an embodiment of an adhesive sheet according to the present invention. It is the cross-sectional schematic by the other embodiment of the adhesive sheet by this invention.

  The adhesive composition according to the present invention comprises, as essential components, bisphenol A type epoxy resin and bisphenol A type phenoxy resin as resin components, a hydrazide-based curing agent as a curing agent, and xylylene diisocyanate as a crosslinking agent. Including. Hereinafter, each component constituting the adhesive composition will be described.

<Resin component>
The resin component constituting the adhesive composition according to the present invention contains bisphenol A type epoxy resin and bisphenol A type phenoxy resin as essential components. By using such a specific resin, it has an adhesive property in an uncured state, has a strong adhesive property even after heat curing, and maintains transparency without whitening.

  Bisphenol A type phenoxy resins may be liquid at room temperature or solid at room temperature, depending on the number of repeating units of the bisphenol skeleton. A bisphenol A type epoxy resin having a main chain of 1 to 3 is liquid at normal temperature, and a bisphenol A type epoxy resin having a main chain of 2 to 10 is solid at normal temperature. In the present invention, it is preferable to use a bisphenol A type epoxy resin that is liquid at room temperature. Such a relatively low molecular weight bisphenol A type epoxy resin has a high crosslink density, and therefore has high mechanical strength, good chemical resistance, high curability, and low hygroscopicity (because the free volume is small). There is a characteristic.

  In the present invention, as the bisphenol A type epoxy resin, a bisphenol A type epoxy resin that is liquid at room temperature as described above and a bisphenol A type epoxy resin that is liquid at room temperature may be used in combination. By using both solid and liquid at room temperature, it is possible to obtain flexibility while maintaining mechanical strength, while maintaining the mechanical strength inherent to the resin (adhesive composition) Flexibility can be obtained. As a result, the bonding strength between adherends can be improved. As the bisphenol A type epoxy resin solid at room temperature, those having a glass transition temperature in the range of 50 to 150 ° C. are preferred from the viewpoint of mechanical strength and heat resistance. Specifically, as a bisphenol A type epoxy resin having a main chain of 1 to 3 which is liquid at normal temperature, JER828 manufactured by Japan Epoxy Resin Co., Ltd. is a bisphenol A type epoxy having a main chain of 2 to 10 which is solid at normal temperature. Examples of the resin include JER1001 manufactured by Japan Epoxy Resin Co., Ltd.

  The blending ratio of the bisphenol A type epoxy resin that is solid at room temperature and the bisphenol A type epoxy resin that is liquid at room temperature depends on the use of the adhesive, but is a ratio of 100: 300 to 300: 100 on a mass basis. It is preferable that it is contained. By setting the blending ratio of both in the above range, an adhesive having better adhesive strength can be obtained.

  In the present invention, bisphenol A type phenoxy resin is used in combination with the above-described bisphenol A type epoxy resin. Since the phenoxy resin has a chemical structure similar to that of the epoxy resin, the phenoxy resin is excellent in compatibility with the epoxy resin when uncured and after being cured. For this reason, even if the adhesive composition is heat-cured, it is considered that whitening does not occur and transparency is maintained. The compatibility with bisphenol A type epoxy resin is the same for both bisphenol A type phenoxy resin and bisphenol F type phenoxy resin, but bisphenol F type phenoxy resin has a glass transition temperature of about 68 ° C. The viscosity is low, and the stickiness is large when used as an adhesive sheet. In the present invention, by using a bisphenol A type phenoxy resin having a glass transition temperature higher than 80 ° C. in combination with a bisphenol A type epoxy resin, both initial adhesiveness and heat resistance can be achieved, and even after thermosetting. It is possible to provide a gluing composition that can maintain transparency without whitening.

  Among the bisphenol A type phenoxy resins described above, those having an average weight molecular weight of 30,000 to 100,000 can be suitably used in the present invention. In the present specification, the weight average molecular weight and the number average molecular weight are values measured by gel permeation chromatography using polystyrene as a standard substance. Commercially available bisphenol A type phenoxy resins may be used. For example, YP-50 (manufactured by Nippon Steel Chemical Co., Ltd.), EXA123 (manufactured by DIC Corporation), and the like can be suitably used.

  The blending ratio of the bisphenol A type epoxy resin and the bisphenol A type phenoxy resin is preferably a ratio of 1: 0.5 to 1: 2 on a mass basis. By setting it as this range, initial tackiness, adhesive strength, and transparency are further improved.

  The adhesive composition according to the present invention may contain a resin component other than the above-described bisphenol A type epoxy resin and bisphenol A type phenoxy resin. For example, bisphenol type epoxy resin such as bisphenol F epoxy resin, novolac epoxy resin, novolac type epoxy resin such as cresol novolac epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane Type epoxy resin, triazine nucleus-containing epoxy resin, dicyclopentadiene modified phenol type epoxy resin, phenol novolac resin, cresol novolac resin, bisphenol A novolac resin and other novolak type phenol resins, resol phenol resin and other phenol resins, urea (urea) Resins, resins having a triazine ring such as melamine resins, unsaturated polyester resins, bismaleimide resins, polyurethane resins, diallyl phthalates DOO resins, silicone resins, resins having a benzoxazine ring, cyanate ester resins, polyetheresteramide resins.

<Curing agent>
The above-described bisphenol A type epoxy resin and bisphenol A type phenoxy resin undergo a reaction by heating or the like to cure the adhesive composition, but in the present invention, in order to accelerate the curing reaction, A hydrazide curing agent is included. By using a hydrazide curing agent in combination with the above-described resin, an adhesive having excellent pot life can be obtained while maintaining high transparency after curing. Examples of the hydrazide curing agent include adipic acid hydrazide, sebacic acid hydrazide, isophthalic acid hydrazide, hydroquinone diglycolic acid dihydrazide, resorcinol diglycolic acid dihydrazide, valine dihydrazide, 1,11-octadecadien-1,18-dicarbohydrazide and the like. Can be used. Commercially available hydrazide-based curing agents may be used. For example, Amicure VDH, Amicure UDH (manufactured by Ajinomoto Co., Inc.) and the like can be preferably used.

  As the curing agent, in addition to the hydrazide-based curing agent described above, other curing agents may be used in combination. For example, aliphatics such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylylenediamine (MXDA). In addition to aromatic polyamines such as polyamine, diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), diaminodiphenylsulfone (DDS), dicyandiamide (DICY), hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA) Acid anhydride such as alicyclic acid anhydride (liquid acid anhydride), trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), benzophenone tetracarboxylic acid (BTDA), etc. Physical hardener, phenolic resin, etc. Nord curing agent can be exemplified. In particular, since dicyandiamide (DICY) is a latent curing agent, it has excellent storage stability and has a pot life of several weeks even at room temperature storage, so it is preferably used in combination with a hydrazide-based curing agent. Moreover, you may include imidazoles as a hardening accelerator.

  It is preferable that 13-22 mass parts is contained for content in the adhesive composition of a hardening | curing agent, when content of resin is 65-80 mass parts. When the blending ratio of the curing agent is less than this range, the heat resistance after joining is low, and the adhesive strength is likely to deteriorate due to a temperature change. When the content of the curing agent exceeds this range, when the adhesive sheet is stored until it is bonded to the adherend, the storage stability (pot life) during the storage period decreases, and after the adhesive is cured However, the unreacted curing agent remains, so that there is a problem that the adhesive strength is lowered.

<Crosslinking agent>
Moreover, the adhesive composition of this invention contains xylylene diisocyanate as an essential component as a crosslinking agent. By combining a resin component containing a bisphenol A type epoxy resin and a bisphenol A type phenoxy resin with the above-described xylylene diisocyanate crosslinking agent, the curability can be further improved and the adhesive strength can be improved.

  The content of the above-described crosslinking agent in the adhesive composition is preferably 5 to 15 parts by mass when the resin content is 65 to 80 parts by mass. When the blending ratio of the cross-linking agent is less than this range, there are few cross-links between the phenoxy resin and the epoxy resin, and the adhesive strength may be insufficient. On the other hand, if the content of the crosslinking agent exceeds this range, gelation may occur due to the influence of moisture in the air, or tack may remain even after heating.

  In addition, the adhesive composition may include, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slip properties, mold release properties, flame retardancy, antifungal properties. For the purpose of improving and modifying properties, electrical properties, strength, etc., for example, lubricants, plasticizers, fillers, fillers, antistatic agents, antiblocking agents, crosslinking agents, antioxidants, UV absorbers, Light stabilizers, colorants such as dyes and pigments, and the like may be added. Further, if necessary, a coupling agent such as silane, titanium, and aluminum can be further included. Thereby, the adhesiveness between the resin, the adherend, and the resin and the core material to be described later can be improved.

  The adhesive composition used in the present invention can be prepared by mixing the above-described components and kneading and dispersing as necessary. The mixing or dispersing method is not particularly limited, and a usual kneading and dispersing machine such as a two-roll mill, a three-roll mill, a pebble mill, a tron mill, a Szegvari attritor, a high-speed impeller disperser, a high-speed stone mill, A high speed impact mill, a desper, a high speed mixer, a ribbon blender, a kneader, an intensive mixer, a tumbler, a blender, a desperser, a homogenizer, an ultrasonic disperser, and the like can be applied. When multiple types are used as the hard epoxy resin, these are first mixed and stirred, then the curing agent is mixed and stirred, diluted with a solvent, and then the soft epoxy resin is mixed and stirred, and then the acrylic resin Are preferably mixed and stirred.

<Adhesive sheet>
As shown in FIG. 1, the adhesive sheet according to the present invention has a layer structure in which a first release paper and a second release paper are provided on both surfaces of an adhesive layer made of the above adhesive composition. In the present specification, the first release paper 21A and the second release paper 21B are collectively referred to as release paper 21. As shown in FIG. 2, the adhesive layer further includes a core material, and the core material may be impregnated with the adhesive. The core material is preferably a woven fabric or a non-woven fabric, and various conventionally known woven or non-woven fabrics can be used. Examples thereof include heat-resistant plastic fibers such as liquid crystal polymers, glass fibers, aramid fibers, and carbon fibers. A woven fabric and a non-woven fabric composed of these can be used.

  When the adhesive layer includes a core material, a first release paper 21 (described later) and the core material 15 are overlapped and run using a coating machine, and the above-described adhesive 13 composition is applied to the surface of the core material 15. Thus, since the core material 15 is impregnated, the second release paper 21B is bonded to the coated surface after drying, whereby the adhesive sheet 1 is obtained.

  The method for applying the adhesive composition to the release paper is not particularly limited. For example, roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coat, blade Coating, bar coating, wire bar coating, die coating, lip coating, dip coating, etc. can be applied. After the composition is applied to the release surface of the first release paper 21A or the first release paper 21A and the core material 15 by the coating method described above and dried, the second release paper is applied. The pattern paper 21B may be attached. The viscosity of the composition (coating solution) is adjusted to about 1 to 20000 centistokes (25 ° C.), preferably 1 to 2000 centistokes. In the case of impregnating and applying to the core material 15, a lower viscosity is preferable, and it is 1-1000 centistokes.

  The first release paper 21A and the second release paper 21B may be the same or different. As the release paper 21, conventionally known ones such as a release film, a separate paper, a separate film, a separate paper, a release film, and a release paper can be suitably used. Moreover, you may use what formed the release layer in the single side | surface or both surfaces of base materials for release paper, such as quality paper, a coated paper, an impregnation paper, and a plastic film. The release layer is not particularly limited as long as it is a material having releasability. For example, silicone resin, organic resin-modified silicone resin, fluororesin, aminoalkyd resin, melamine resin, acrylic resin, polyester resin, etc. There is. These resins can be used in any of emulsion type, solvent type and solventless type.

  The release layer is formed by applying a coating liquid in which a release layer component is dispersed and / or dissolved on one side of a release paper base film, followed by heat drying and / or curing. As a coating method of the coating liquid, a known and arbitrary coating method can be applied, for example, roll coating, gravure coating, spray coating and the like. Moreover, you may form a release layer in the whole surface or a part of at least single side | surface of a base film as needed.

  The peeling force of the first and second release papers is preferably about 1 to 2000 mN / cm, and more preferably 100 to 1000 mN / cm with respect to the adhesive sheet. When the release force of the release layer is less than 1 mN / cm, the release force from the adhesive sheet or the adherend is weak, and it peels off or partially floats. Moreover, when larger than 2000 mN / cm, the peeling force of a release layer is strong and it is hard to peel. From the viewpoint of stable releasability and processability, addition and / or polycondensation-type curable silicone resins for release paper, which are mainly composed of polydimethylsiloxane, are preferred.

<Adhesion method of adherend>
In the bonding with the adherend, the first release paper 21A and the second release paper 21B of the adhesive sheet 1 are peeled off and the adhesive layer 11 is exposed. The exposed adhesive layer 11 is sandwiched between two identical or different first adherends and second adherends and held with the adhesiveness of the adhesive layer 11. Next, the adhesive layer 11 can be cured by heating or pressurizing to firmly bond the first adherend and the second adherend. As described above, by using the adhesive sheet according to the present invention, the adherends can be temporarily fixed using the initial tackiness, and then the adhesive sheet is thermally cured by, for example, a batch method. Therefore, the process such as preheating can be omitted and the productivity is remarkably improved.

  The adherend is not particularly limited, and examples thereof include metals, inorganic materials, organic materials, composite materials combining these materials, and laminated materials.

  The heating temperature at the time of curing is about 100 to 200 ° C, preferably 110 to 180 ° C. The heating time is 1 to 240 minutes, preferably 60 to 180 minutes. Since the adhesive layer 11 of the cured adhesive sheet 1 has initial tackiness, there is no preheating process, and the work can be performed while holding the adherend with only the tackiness, so that the workability is good and the cost is low. Moreover, by selecting the material of the adhesive layer and the blending ratio thereof, the metals, the metal and the organic material, and the organic material and the organic material can be bonded. Furthermore, strong adhesive strength resulting from the epoxy resin is obtained, and this adhesive strength is not easily deteriorated even by temperature change, and because it is attributed to the acrylic resin, the brittleness is low, and excellent shear strength and high resistance to resistance are obtained. Since it has impact and heat resistance, it can be used for structural purposes.

<Bonded body>
By using the adhesive sheet according to the present invention, it is possible to strongly bond materials (adherents) such as FRP of glass fiber and carbon fiber, different metals, which are difficult with conventional welding methods. For example, metals such as aluminum and iron And a bonded body of FRP and CFRP can be obtained. These bonded bodies can maintain excellent adhesive strength without undergoing temperature change, have low brittleness, and have excellent shear strength, high impact resistance, and heat resistance. However, the present invention can be used in the fields of electronic devices, electronic device casings, home appliances, infrastructure structures, lifeline building materials, general building materials, and the like.

  Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to the contents of these examples. In addition, each composition of each layer is the mass part of solid content except a solvent.

Examples 1 and 2 and Comparative Examples 1-7
<Preparation of adhesive composition>
According to the composition shown in Table 1 below, an adhesive was prepared by mixing each component. In Table 1 below,
SG-P3 is an acrylic resin manufactured by Nagase Chemtech,
YP-50EK is a bisphenol A type phenoxy resin manufactured by Nippon Steel Chemical Co., Ltd.
JER828 and JER1001 are bisphenol A type epoxy resins manufactured by Japan Epoxy Resin Co., Ltd.
TPAE826 is a polyether ester amide manufactured by T & K Toka,
GK880 is an amorphous polyester resin manufactured by Toyobo Co., Ltd.
Amicure VDH is a hydrazide curing agent manufactured by Ajinomoto Fine Techno Co., Ltd.
Takenate 500 is a xylylene diisocyanate from Mitsui Chemicals,
DICY7 is a dicyandiamit manufactured by Mitsubishi Chemical Corporation.
Represent each.

<Preparation of adhesive sheet>
The obtained adhesive was applied to the surface of a Sepa film (SP-PET 03BU, manufactured by Tosero Co., Ltd.) with a comma coater so that the coating amount was 100 g / m ² to form an adhesive layer. An adhesive sheet was prepared by laminating a separate film (SP-PET 01BU, manufactured by Tosero) on the layer. In addition, the adhesive of Comparative Example 4 is difficult to form into a sheet, and the adhesive of Comparative Example 5 causes the resin to flow and repel due to heat during solvent drying when the adhesive is formed into a sheet. However, the film could not be formed.

<Production of bonded body>
The obtained adhesive sheet was cut into 25 mm × 12.5 mm, one of the separator films was peeled off to expose the adhesive layer, and one of the adherends CFRP (length 100 mm × width 25 mm × thickness 1.5 mm) ). The separator film is peeled off from the adhesive sheet attached to the CFRP to expose the adhesive layer, and the end of the other adherend CFRP (length 100 mm × width 25 mm × thickness 1.5 mm) is formed on the adhesive layer portion. The part was pasted.

  Next, a bonded body was obtained by applying a load of 3 kg onto the temporarily fixed adherend and heating and curing the adhesive layer at 120 ° C. for 2 hours.

<Evaluation of adhesive strength>
About each obtained bonding body, the adhesive strength in room temperature was evaluated. Both ends of the sample obtained above were fixed to Tensilon (Orientec RTA-1T), pulled at 0.5 mm / min, and shear strength was measured. The evaluation results were as shown in Table 2 below.

<Color of adhesive layer after curing>
The adhesive layer of the bonded body was visually observed and the color was evaluated. The evaluation results were as shown in Table 2 below.

1: Adhesive sheet 11: Adhesive layer 13: Adhesive 15: Core material 21: Release paper 21A: First release paper 21B: Second release paper

Claims (9)

As resin components, bisphenol A type epoxy resin and bisphenol A type phenoxy resin,
As a curing agent, a hydrazide-based curing agent,
As a crosslinking agent, xylylene diisocyanate,
An adhesive composition comprising at least   The adhesive composition according to claim 1, wherein a blending ratio of the bisphenol A type epoxy resin and the bisphenol A type phenoxy resin is included in a ratio of 1: 0.5 to 1: 2 on a mass basis.   The adhesive composition according to claim 1 or 2, wherein the bisphenol A type epoxy resin is composed of a bisphenol A type epoxy resin that is liquid at room temperature with a main chain of 1 to 3.   The adhesive composition according to any one of claims 1 to 3, wherein the bisphenol A-type phenoxy resin has a molecular weight of 30,000 to 100,000.   The adhesive composition according to any one of claims 1 to 4, comprising 65 to 80 parts by mass of the resin component, 13 to 22 parts by mass of the curing agent, and 5 to 15 parts by mass of the curing agent.   It is an adhesive sheet formed by laminating a first release paper, an adhesive layer, and a second release paper in this order, and the adhesive layer is the adhesive according to any one of claims 1 to 5. An adhesive sheet comprising the composition.   The adhesive sheet according to claim 6, wherein the adhesive layer further includes a core material, and the core material is impregnated with the adhesive. A method of bonding the first adherend and the second adherend using the adhesive sheet according to claim 6 or 7,
From the adhesive sheet, the first release paper and the second release paper are peeled and removed to expose the adhesive layer,
Sandwiching the adhesive layer between the first adherend and the second adherend, and temporarily fixing the first adherend and the second adherend,
The method comprising: curing the adhesive layer by heating to bond the first adherend and the second adherend.   The bonding body obtained by the method of Claim 8.

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