JP5717019B2 - Adhesive composition and adhesive sheet using the same - Google Patents

Description

  The present invention relates to an adhesive composition, and more particularly, to an adhesive composition that is excellent in pot life and can maintain high transparency even after curing, 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.

  When the glass fiber or carbon fiber FRP is bonded to a metal, an adhesive is used because it cannot be bonded by welding. As an adhesive, it is possible to bond metals, metal and organic material, organic material and organic material, adhesive strength is strong so that it can be used for structural applications, and adhesive strength does not deteriorate with temperature change, etc. Is required. In addition, there is a demand for having initial tackiness, good workability without steps such as preheating.

  Glass is also used in displays for electronic portable terminals, buildings that emphasize design, and platform doors that are installed on station platforms to prevent falls. Bonding with an adhesive is performed. Of course, high adhesive strength is required for the adhesive used for laminating these glasses, and depending on the application, the adhesive part can maintain high transparency even after the adhesive is cured. May be required. From such a background, there is a demand for an adhesive capable of bonding a metal such as aluminum, FRP, glass or the like and maintaining high transparency after bonding.

  In general, a thermosetting resin such as an epoxy resin is used as an adhesive when laminating glass or metal. In addition, these epoxy adhesives are those in which the epoxy group in the adhesive component is opened by heat to form a cross-linked structure to cure the resin, and a curing agent and a curing catalyst (curing accelerator) are used in combination. There is a case. Known curing agents for epoxy adhesives include dicyandiamide, polyhydrazides, phenol novolacs, alkenylphenol polymers, acid anhydrides, thiols and the like. Further, amine-based, imidazole-based and urea-based compounds are known as curing catalysts used with these curing agents.

  The above-mentioned curing agent and curing catalyst can increase the curing rate of the epoxy adhesive. For example, a thiol-based curing agent has high reactivity and is known as a rapid curing type curing agent at a low temperature. On the other hand, when a curing agent is added to a one-component adhesive, the curing reaction proceeds, so there is a problem that the period (pot life) in which the adhesive before use can be stably stored is shortened. Curing catalysts are not used for applications that require long-term pot life. Japanese Patent Laid-Open No. 63-243125 (Patent Document 1) proposes an isophorone bisurea compound as a curing catalyst capable of improving the pot life of an epoxy adhesive. However, the above patent document does not disclose the combined use with a thiol-based curing agent.

JP-A-63-243125

  Since a wide variety of curing agents and curing catalysts described above have been developed, there are innumerable combinations thereof. However, depending on the combination of the curing agent and the curing catalyst, the pot life property may deteriorate, or the cured adhesive may become cloudy or yellow.

  The inventors of the present invention have excellent pot life and high after curing by using a thiol-based curing agent, which is a low-temperature fast-curing curing agent, and a specific curing catalyst in combination with an epoxy resin. The knowledge that the adhesive composition which can maintain transparency was realizable was acquired. The present invention is based on this finding.

  Accordingly, an object of the present invention is an adhesive that can bond metal and glass to each other, metal and organic material, organic material and organic material, and has excellent pot life and can maintain high transparency even after curing. Providing an agent composition.

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

An adhesive composition according to the present invention is an adhesive composition comprising an epoxy resin, a curing agent, and a curing catalyst,
The curing agent comprises a thiol compound,
The curing catalyst is made of aliphatic dimethylurea.

  In the adhesive composition according to an embodiment of the present invention, the epoxy resin may be a bisphenol type epoxy resin.

  Further, the adhesive composition according to an embodiment of the present invention includes: a bisphenol type epoxy resin that is liquid at room temperature; and a bisphenol type epoxy that is solid at room temperature and has a glass transition temperature in the range of 50 to 170 ° C. It may consist of two types of resin bisphenol type epoxy resins.

  In the adhesive composition according to an embodiment of the present invention, the bisphenol-type epoxy resin that is liquid at normal temperature and the bisphenol-type epoxy resin that is solid at normal temperature are in a range of 0: 64.3 to 14.8: 44. 5 may be included.

  In the adhesive composition according to an embodiment of the present invention, the curing agent may be included in an amount of 0.59 to 1.08 phr with respect to the epoxy resin.

  In the adhesive composition according to an embodiment of the present invention, the curing catalyst may be included in an amount of 0.1 to 3.0% with respect to a total mass of the epoxy resin.

  Moreover, the adhesive composition according to one embodiment of the present invention may further include an acrylic resin.

  In the adhesive composition according to an embodiment of the present invention, the acrylic resin may contain a methyl methacrylate copolymer.

  In the adhesive composition according to an embodiment of the present invention, the acrylic resin may include a methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer or a modified product thereof.

An adhesion method according to another aspect of the present invention is a method of adhering a first adherend and a 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 present invention, by using a specific curing agent and a specific curing catalyst in combination with an epoxy resin, an adhesive composition that has excellent pot life and can maintain high transparency even after curing is realized. 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. It is the surface observation photograph of the adhesive of Example 1 and Example 4.

  The adhesive composition according to the present invention contains an epoxy resin, a curing agent, and a curing catalyst as essential components. Hereinafter, each component constituting the adhesive composition will be described.

<Epoxy resin>
The epoxy resin used in the adhesive composition according to the present invention means a resin obtained by curing a prepolymer having at least one epoxy group or glycidyl group by a crosslinking polymerization reaction in combination with a curing agent. Such epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, novolac type epoxy resins such as novolac epoxy resin and cresol novolac epoxy resin, biphenyl type epoxy resin, and stilbene type epoxy. Aromatic or alicyclic epoxy resins such as resins, triphenolmethane type epoxy resins, alkyl modified triphenolmethane type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene modified phenol type epoxy resins, Aliphatic epoxy resins, phenol novolac resins, cresol novolac resins, bisphenol A novolac resins and other novolac type phenol resins, and resole phenolic resins such as phenols. Resins having triazine rings such as vinyl resins, urea (urea) resins, melamine resins, unsaturated polyester resins, bismaleimide resins, polyurethane resins, diallyl phthalate resins, silicone resins, resins having benzoxazine rings, cyanate ester resins, etc. Is mentioned. Among these epoxy resins, in the present invention, an epoxy resin having a rigid structure such as a biphenyl skeleton, a bisphenol skeleton, or a stilbene skeleton in the main chain is preferable, more preferably a bisphenol type epoxy resin, and particularly preferably a bisphenol A type. It is an epoxy resin.

  The above-described bisphenol A type epoxy resin 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. Such a relatively low molecular weight bisphenol A type epoxy resin has crystallinity, and even a solid one that is crystallized at room temperature rapidly melts and changes to a low-viscosity liquid when the temperature reaches the melting point or higher. Therefore, in the step of bonding the adherends, the adhesive adheres to the adherend by heating and solidifies by solidifying the adhesive and the adherend, so that the adhesive strength can be increased. In addition, 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 hygroscopicity (because the free volume is small). ) Is also small.

  In the present invention, as the bisphenol A type epoxy resin, it is preferable to use a bisphenol A type epoxy resin that is solid at room temperature and a bisphenol A type epoxy resin that is liquid at room temperature. 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 normal temperature, those having a glass transition temperature in the range of 50 to 170 ° C. are preferable from the viewpoint of mechanical strength and heat resistance. Specifically, as a bisphenol A type epoxy resin having a main chain of 0 to 1 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 0: 64.3 to 14.8 on a mass basis. : It is preferably contained at a ratio of 44.5. By setting the blending ratio of both in the above range, an adhesive having better adhesive strength can be obtained. In addition, when there are too many compounding ratios of liquid bisphenol A type epoxy resin at normal temperature, it will become difficult to form into a film.

<Acrylic resin>
The adhesive composition according to the present invention may contain an acrylic resin. By including an acrylic resin in addition to the epoxy resin as the adhesive component, toughness can be imparted to the cured adhesive while maintaining the adhesive strength. Moreover, since initial adhesiveness can be provided to an adhesive agent, it can be applied to an adhesive sheet as described later. As a result, the adherends to be bonded can be preliminarily bonded together with an adhesive sheet, and then the adhesive can be thermally cured.

  The acrylic resin that can be used can be used without particular limitation as long as it is a resin that is well compatible or dispersed with an epoxy resin. For example, methyl (meth) acrylate, ethyl (meth) acrylate, ( Meth) propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, ( (Meth) acrylic acid alkyl esters such as octyl acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate, these acrylate monomers, maleic acid, itaconic acid, (meth) acrylic acid 2-hydroxyethyl, 2-hydroxypropyl (meth) acrylate, (meth) acrylamide, N- Functional group-containing monomers such as tyrolacrylamide, n-butoxy-N-methylolacrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid soda, diacetone acrylamide, glycidyl (meth) acrylate, styrene, vinyltoluene, Acrylic ester copolymers obtained by copolymerizing monomers such as vinyl acetate, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, ethyl vinyl ether and the like can be suitably used.

  Among the above copolymers, a methyl methacrylate copolymer comprising a methyl methacrylate unit and another monomer unit can be preferably used. Examples of such a copolymer include a methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer or a modified product thereof, or a methyl methacrylate-butadiene-styrene block copolymer or a modified product thereof. In these methyl methacrylate copolymers, a block copolymer consisting of a methacrylic acid ester polymer block (hereinafter sometimes abbreviated as MMA) and a butyl acrylate polymer block (hereinafter sometimes abbreviated as BA). By adding a block copolymer composed of coalescence or MMA, butadiene (hereinafter sometimes abbreviated as B) and styrene (hereinafter sometimes abbreviated as S) to the above-described epoxy resin, An adhesive that has toughness and can maintain excellent adhesive strength even in a high temperature environment can be realized. The reason is not clear, but can be estimated as follows.

  In the MMA-BA-MMA binary copolymer, the MMA portion becomes a “hard” segment and the BA portion becomes a “soft” segment. In the MMA-B-S binary copolymer, the MMA portion and the S portion are “hard” segments, and the B portion is a “soft” segment. In conventional adhesives, an acrylic resin has been added to impart toughness (flexibility) to the epoxy resin, but the addition of the acrylic resin reduces the heat resistance of the adhesive itself. Was. If the acrylic resin has both the “hard” and “soft” segments as described above, the “hard” segment will contribute to heat resistance, and the “soft” segment will contribute to toughness and flexibility. It is considered that an adhesive having toughness and capable of maintaining excellent adhesive strength even in a high temperature environment can be realized.

  The above binary block copolymer can be produced using general living radical polymerization. Among these, from the viewpoint of easy control of the polymerization reaction, it can be suitably produced by primordial transfer radical polymerization. The atom transfer radical polymerization method is a polymerization method using an organic halide or a sulfonyl halide compound as an initiator and a metal complex as a catalyst. When producing a binary copolymer of MMA-BA-MMA by the living radical polymerization method, a method of sequentially adding monomer units, a method of polymerizing the next polymer block using a polymer synthesized in advance as a polymer initiator, Examples thereof include a method in which polymer blocks polymerized separately are combined by reaction, and it is preferable to produce a MMA-BA-MMA binary copolymer by a method in which monomer units are sequentially added.

  In the method of producing a MMA-BA-MMA binary copolymer by sequential addition of monomer units, the order of addition of the methacrylic acid ester constituting the MMA block and the butyl acrylate constituting the BA block is as follows. There are a method of adding a butyl acrylate monomer after polymerizing a methacrylic acid ester monomer and a method of adding a methacrylic acid ester monomer after first polymerizing a butyl acrylate monomer. The polymerization control is easier when the MMA block is polymerized from the polymerization terminal of the BA block. The ratio of MMA to BA can be controlled by the amount of monomer introduced when the living radical polymerization reaction is performed. The ratio of the MMA block to the BA block in the MMA-BA-MMA binary copolymer increases the toughness and flexibility of the adhesive when the BA block ratio increases, while the MMA block ratio increases. The heat resistance of the adhesive is improved. In the present invention, from the viewpoint of the toughness and heat resistance of the adhesive, the ratio of the MMA block to the BA block is preferably 1: 1 to 50: 1 in the number of monomer units.

  The above-described MMA-BA-MMA binary copolymer may be a modified product in which a functional group such as a carboxylic acid or a hydroxyl group is introduced into a part of the BA block. By using such a modified product, the heat resistance is further improved and the compatibility with the above-described epoxy resin is also improved, so that the adhesive strength is further improved.

  When the MMA-BA-MMA binary copolymer is added to the above epoxy resin, the MMA block portion is compatible with the epoxy resin and the BA block portion is not compatible with the epoxy resin. Self-organization occurs. Therefore, it is considered that a structure in which an acrylic resin is finely dispersed in the epoxy resin appears, and as a result, interface fracture can be avoided and excellent adhesive strength can be maintained.

  The content of these epoxy resin and acrylic resin is preferably such that the epoxy resin and the acrylic resin are contained in a ratio of 97.5: 2.5 to 77.0: 23.0 on a mass basis. When the content of the epoxy resin is increased, the toughness is lowered and the film-forming property and the initial adhesiveness are lowered. On the other hand, when the content of the acrylic resin increases, the adhesive becomes difficult to cure and the adhesive strength also decreases.

<Curing agent>
The reaction between the acrylic resin and the epoxy resin proceeds by heating or the like and the adhesive composition is cured, but a curing agent may be added to the adhesive composition in order to accelerate the curing reaction. In the present invention, a thiol compound is used as a curing agent. In general, amine curing agents, acid anhydride curing agents, and the like are used as curing agents for epoxy resins. When these conventional curing agents are applied to the adhesive composition according to the present invention, the adhesive is cured. Later, it was found that the adhesive may become cloudy or yellow. In addition, these curing agents shorten the pot life. In the present invention, it has been found that by using a thiol compound as a curing agent for the acrylic resin and epoxy resin described above, the pot life can be extended and the transparency after curing can be maintained.

  As the thiol compound, a conventionally known compound can be used, and examples thereof include an ester bond type, an aliphatic ether bond type, an aromatic ether bond type, and among these, an ester bond type thiol compound. Can be used more suitably. More specifically, Karenz MTPE1 (manufactured by Showa Denko KK), Adeka Cardner series (manufactured by Asahi Denka Co., Ltd.), EpiCure QX40 (manufactured by Mitsubishi Chemical Corporation) and the like are suitably used as the ester bond type thiol compound. Can be used.

  The curing agent is preferably contained in the range of 0.59 to 1.08 phr with respect to the epoxy resin. By setting the blending ratio of the curing agent within this range, it is possible to realize an adhesive composition having excellent transparency and storage stability. Needless to say, if the addition amount of the curing agent is small, the curability deteriorates and the adhesive strength decreases. On the other hand, when the content of the curing agent is increased, transparency and walking pot life are lowered, and there is a problem that the adhesive strength is lowered due to the remaining unreacted curing agent after the adhesive is cured.

<Curing catalyst>
The adhesive composition according to the present invention contains aliphatic dimethylurea as a curing catalyst in addition to the above components. In general, amine-based catalysts, imidazole-based catalysts, urea-based catalysts, and the like are used as epoxy resin curing accelerators (curing catalysts). In the present invention, the above-described epoxy resins and thiols as curing agents are used. Addition of aliphatic dimethylurea as a curing catalyst to an adhesive composition containing an organic compound can improve storage stability and maintain excellent transparency even after curing The strength can be maintained.

  The aliphatic dimethylurea that can be used in the present invention is not particularly limited as long as it is a compound having a structure in which dimethylurea is bonded to an aliphatic group. For example, dimethylurea obtained from isophoridine isocyanate and dimethylamine, Examples include dimethylurea obtained from lenisocyanate and dimethylamine, and dimethylurea obtained from hexamethylene diisocyanate and dimethylamine. As these aliphatic dimethylureas, commercially available products may be used. For example, UCAT-3513N manufactured by San Apro Co., Ltd. can be suitably used.

  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 transparency is required, nanofibers or the like can be used as the core material.

  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 60 ° C to 250 ° C, preferably 100 ° C to 180 ° C. The heating time is 1 to 240 minutes, preferably 10 to 120 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 join materials (adherents) such as FRP of glass fiber and carbon fiber, glass, and dissimilar metals, which are difficult with conventional welding methods, such as aluminum and iron. Bonded bodies with other metals and bonded bodies between 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 1-22 and Comparative Examples 1-9
<Preparation of adhesive composition>
In accordance with the composition shown in Table 1 (Example) and Table 2 (Comparative Example) below, a curing agent is added to the bisphenol A type epoxy resin and mixed with a stirrer, and then an acrylic resin is added to the mixture and mixed Thus, an adhesive composition was prepared. In Table 1 below,
JER828 is a bisphenol A type epoxy resin (liquid at normal temperature) manufactured by Mitsubishi Chemical Corporation.
JER1001 is a bisphenol A type epoxy resin (solid at normal temperature, glass transition temperature = 64 ° C.) manufactured by Mitsubishi Chemical Corporation.
JER1009 is a bisphenol A type epoxy resin (solid at normal temperature, glass transition temperature = 144 ° C.) manufactured by Mitsubishi Chemical Corporation.
2021P is an aliphatic cyclic epoxy resin (liquid at normal temperature) manufactured by Daicel Chemical Industries, and EHPE3150 is an alicyclic solid epoxy resin (solid at normal temperature, glass transition temperature = 74 ° C.) manufactured by Daicel Chemical Industries,
M22N is a modified binary copolymer of methyl methacrylate-butyl acrylate-methyl methacrylate having a polar group introduced by Arkema (glass transition temperature = about 120 ° C.),
SK Dyne 1495 is an acrylic-vinyl acetate copolymer manufactured by Soken Chemical Co., Ltd.
WS-023 is an acrylic copolymer (Taisan Resin WS-023) having a carboxyl group and a hydroxyl group as a functional group manufactured by Nagase ChemteX Corporation.
QX40 is a thiol-based curing agent manufactured by Mitsubishi Chemical Corporation.
MH-700 is an alicyclic acid anhydride curing agent manufactured by Shin Nippon Rika Co., Ltd.
DICY7 is a dicyandiamit manufactured by Mitsubishi Chemical Corporation.
L45 is a tolylene diisocyanate-based crosslinking agent (Coronate L45) manufactured by Nippon Polyurethanes,
UCAT-3513N is an aliphatic dimethylurea manufactured by Sun Apro,
UCAT-5003 is a quaternary phosphonium bromide manufactured by San Apro.
UCAT-3512 is an aromatic dimethylurea manufactured by San Apro,
2E4MZ is an imidazole-based curing catalyst manufactured by Shikoku Kasei Co., Ltd.
JER3010 is a tertiary amine curing catalyst manufactured by Mitsubishi Chemical Corporation.
KBM403 is a silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd.
Represent each.

<Evaluation of adhesive composition>
The adhesive compositions of Example 1 and Comparative Example 10 were applied to the release-treated surface of a PET carrier film (product name POL382150, manufactured by Lintec Corporation) having a thickness of 38 μm that had been subjected to silicone release treatment so that the thickness when dried was 50 μm. After applying with an applicator and drying at 100 ° C. for 10 minutes, an adhesive layer was formed. Next, a hard coat film having a surface pencil hardness of 3H was bonded to the surface of the adhesive layer, and an adhesive sheet was obtained by aging for 1 week at normal humidity and normal temperature. After the obtained pressure-sensitive adhesive sheet is cut out to a size of 25 mm × 70 mm, the PET carrier film is peeled off, and the surface of the adhesive layer is bonded to a glass plate using a rubber roller to obtain a hard coat film with an adhesive layer. Obtained.

  The strength (peel strength) when peeling the adhesive layer from the hard coat film with the adhesive layer obtained as described above was measured at room temperature using a tensile tester (model 5565, manufactured by Instron). The measurement was performed under the conditions of speed = 300 mm / min and peel angle = 180 ° (based on JIS Z0237). The evaluation results were as shown in Table 1 below. In addition, in the hard coat film with an adhesive layer using the adhesive composition of Example 1, the hard coat film was torn at the time of peeling.

  In addition, the adhesive sheet is heat-treated in an autoclave apparatus at 0.5 MPa, 50 ° C. for 30 minutes, and then the carrier film and the hard coat film are peeled off from the adhesive sheet to form an adhesive (on the adhesive layer of the adhesive sheet). Only). The measurement of the storage elastic modulus E ′ of this adhesive at 25 ° C. was performed using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments Inc., and a dynamic viscoelasticity measurement method based on JIS K7244-1. (Attachment mode: compression mode, frequency: 1 Hz, temperature: −50 to 150 ° C., heating rate: 5 ° C./min). The measurement results were as shown in Table 1 below.

  Moreover, the pencil hardness (adhesive sheet pencil hardness) of the hard coat surface of the hard coat film with an adhesive layer bonded to the glass plate was measured according to JIS K5600-5-4. For comparison, a hard coat film having a surface pencil hardness of 3H was fixed on a glass plate, and the pencil hardness of the hard coat surface was measured under the same conditions as described above. The measurement results were as shown in Table 1 below.

<Preparation of adhesive sheet>
The obtained adhesive compositions of Examples and Comparative Examples were applied to one surface of a Sepa film (SP-PET 03BU, manufactured by Tosero Co., Ltd.) with a comma coater so that the application amount was 100 g / m ^2. Then, an adhesive layer was formed by drying at 100 ° C. for 3 minutes, and a separate film (SP-PET 01BU, manufactured by Tosero Corp.) was bonded onto the adhesive layer to prepare an adhesive sheet.

<Evaluation of initial tackiness>
In order to evaluate the initial tackiness of the adhesive composition, a test sample was prepared as follows. In the above-described production process of the adhesive sheet, an adhesive sheet was produced using a PET film (E-5100, manufactured by Toyobo Co., Ltd.) instead of one of the separator films. After the obtained adhesive sheet was allowed to stand in an environment of 23 ° C. and 50% RH for 24 hours, it was cut into 25 mm × 250 mm, the separator film was peeled off to expose the adhesive layer, and the adhesive layer portion was Place the aluminum plate (6061) whose surface has been washed, and then use the manual crimping device (JIS0237) to reciprocate once at a crimping speed of about 5 mm / sec to bond the adhesive sheet to the aluminum plate. A test piece was obtained.

  The peel-off strength (N / cm) of the test piece obtained above was measured using Tensilon (Orientec RTA-1T) at 180 ° and 300 mm / min. The evaluation results were as shown in Table 3 below.

<Evaluation of film forming property>
An adhesive is applied to a Sepa film (SP-PET 01BU, manufactured by Tosero Co., Ltd.) with a comma coater so that the coating amount after drying is 50 g / m ^2, and dried at 100 ° C. for 3 minutes. The appearance of was observed. The evaluation criteria were as follows.
○: The coating film has a uniform thickness (± 5 μm). X: There is a portion where the adhesive is repelled on the surface of the separator film and the evaluation result is as shown in Table 3 below.

<Evaluation of curability>
The separation film on one side of the adhesive sheet obtained above was peeled off, and after heat-curing the adhesive layer at 130 ° C. for 2 hours, a mixed solvent of methyl ethyl ketone / toluene (mixing ratio 1: 1) was dropped with a dropper, allowed to stand for 5 seconds, and then visually observed whether the cured adhesive layer was dissolved. The evaluation criteria were as follows.
◯: The surface is not changed at all ×: The surface is dissolved or the tactile feels tackiness The evaluation results are as shown in Table 3 below.

<Adhesive strength>
The obtained adhesive sheet is cut into 25 mm × 12.5 mm, one of the separator films is peeled to expose the adhesive layer, and the tip of one adherend (length 100 mm × width 25 mm × thickness 1.5 mm) Affixed to the part. The separation film is peeled off from the adhesive sheet attached to the adherend to expose the adhesive layer, and the tip of the other adherend (length 100 mm × width 25 mm × thickness 1.5 mm) is formed on the adhesive layer portion. Was attached, and a bonded body was obtained by applying a load of 3 kg on the temporarily fixed adherend and heating and curing the adhesive layer at 130 ° C. for 2 hours. As the bonded body, two types of adherends were manufactured: an iron plate and an iron plate, and iron and CFRP.

  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 1.0 mm / min, and measured for shear strength (MPa). The evaluation results were as shown in Table 3 below.

<Transparency evaluation>
About the obtained adhesive sheet, the presence or absence of the color was confirmed by visually observing the appearance. Further, after the adhesive sheet was cured, the color was confirmed in the same manner as described above. Furthermore, after the adhesive sheet was cured, it was immersed in hot water at 80 ° C. and allowed to stand for 24 hours, and then the color of the adhesive sheet was confirmed as described above. The evaluation results were as shown in Table 3 below.

<Evaluation of storage stability>
The adhesive sheet obtained above was allowed to stand at room temperature (25 ° C., 50% RH) for 1 month, and then the presence or absence of tack on the surface of the adhesive layer from which the separator film was peeled was examined. The presence or absence of tack was performed in the same manner as in the evaluation of various initial tacks described above, and the tack having an initial tack of 50% or more with respect to the initial tack after the production of the adhesive sheet was determined to be tacky. The evaluation results were as shown in Table 3 below.

Moreover, in order to confirm the compatibility state of the pressure-sensitive adhesive used in Example 4, an adhesive was applied to a Sepa film (SP-PET 01BU, manufactured by Toh cello) so that the coating amount after drying was 50 g / m ^2. About the thing which apply | coated with the comma coater and heated the adhesive agent for 2 hours at 100 degreeC, the surface observation of the adhesive was performed using the electron microscope (SU3500, Hitachi High-Tech company make). FIG. 3 is an electron micrograph obtained.

  Since the adhesive sheet using the adhesive composition according to the present invention has higher hardness after curing than conventional adhesives, exterior materials such as scattering prevention films, window films, antireflection films, heat ray reflection films, light selection In addition to a film, it can be suitably used for bonding a touch panel surface material and the like.

  Further, the adhesive sheet using the adhesive composition according to the present invention cures the adhesive by heating, but is in a liquid state at the stage of heating (before curing). It also has good adhesion. Therefore, it can be suitably used for applications such as touch panel cover glass bonding and bonding while filling in steps such as embedding of IC chips and electronic wiring of tags.

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

Claims (15)

An adhesive composition comprising an epoxy resin, a curing agent, and a curing catalyst,
The curing agent comprises a thiol compound,
An adhesive composition, wherein the curing catalyst comprises an aliphatic dimethylurea.   The adhesive composition according to claim 1, wherein the epoxy resin is a bisphenol type epoxy resin.   The said bisphenol-type epoxy resin consists of two types of bisphenol-type epoxy resins, a bisphenol-type epoxy resin that is liquid at room temperature and a bisphenol-type epoxy resin that is solid at room temperature and has a glass transition temperature in the range of 50 to 170 ° C. The adhesive composition described in 1.   The bisphenol-type epoxy resin that is liquid at normal temperature and the bisphenol-type epoxy resin that is solid at normal temperature are included in a ratio of 0: 64.3 to 14.8: 44.5. Adhesive composition. The adhesive composition according to any one of claims 1 to 4, wherein the thiol-based curing agent is an ester bond type thiol compound. The adhesive composition according to any one of claims 1 to 4, wherein the thiol-based curing agent is a tetrafunctional thiol compound. The adhesive composition according to any one of claims 1 to 6 , wherein the curing agent is contained in an amount of 0.59 to 1.08 phr with respect to the epoxy resin. The adhesive composition according to any one of claims 1 to 7 , wherein the curing catalyst is contained in an amount of 0.1 to 3.0% with respect to a total mass of the epoxy resin. The adhesive composition according to any one of claims 1 to 8 , further comprising an acrylic resin. The adhesive composition according to claim 9 , wherein the acrylic resin comprises a methyl methacrylate copolymer. The adhesive composition according to claim 9 or 10 , wherein the acrylic resin comprises a methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer or a modified product thereof. The adhesive composition according to claim 11, wherein the acrylic resin is a modified product of a methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer in which a functional group is introduced into a part of a butyl acrylate unit. 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 12. An adhesive sheet comprising the composition. A method of bonding the first adherend and the second adherend using the adhesive sheet according to claim 13 ,
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 14 .