JP5560746B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to an adhesive sheet, and more specifically, after the adhesive layer of the adhesive sheet is exposed and held between two adherends, the adhesive layer is formed by heating with pressure. The present invention relates to an adhesive sheet that can be cured to strongly adhere an adherend.

  In the present specification, “ratio”, “part”, “%” and the like indicating the composition are based on mass unless otherwise specified, and the “/” mark indicates that they are integrally laminated. In the present specification, “adhesive sheet” means “a sheet having an adhesive force at the moment of being attached to a substrate and then having an adhesive force by heating”, and “adhesive force” means “base”. “Adhesive strength” means “force that physically adheres by heating after being applied to a substrate”.

(Background Art) Conventionally, as a joining method for integrating two adherends, there are an occlusion, welding, and an adhesion 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 CO2 emissions to prevent global warming, the weight reduction of vehicle bodies and the spread of hybrid cars and electric cars have been promoted. For this reason, there is a growing trend to use lightweight aluminum and magnesium, FRP (CFRP = carbon fiber reinforced plastics, GFRP = garas fiber reinforced plastics) for the vehicle body.
However, it is extremely difficult to weld dissimilar materials such as aluminum and iron with conventional welding methods, and welding itself is impossible in the case of FRP of glass fiber or carbon fiber. A bonding material that can be strongly bonded is required. As a joining method, there is a method using an adhesive sheet or an adhesive sheet, but it is not sufficient. Furthermore, in the bonding operation to the adherend, if the adhesive sheet is not elastic, the handling property is poor and the workability is lowered.
Therefore, the following performance is required for the adhesive sheet. (1) It can bond metals, metal and organic material, and organic material and organic material. (2) Adhesive strength must be strong so that it can be used for structural purposes. (3) Adhesive strength should not deteriorate with temperature change. (4) It has initial tackiness, has no steps such as preheating, and has a small number of work steps. (5) Good workability in joining work to adherends.

JP 2006-237383 A JP-A-9-181421

(Prior Art) Conventionally, a die attach film in which a base material film (I), a pressure-sensitive adhesive layer, a base film (II) and a film adhesive layer are formed in this order, and the base film (II) The die-attach with a dicing sheet function, wherein the film-like adhesive layer side of the film is subjected to release treatment, and the film-like adhesive layer contains an acrylate copolymer and a thermosetting resin A film is known (for example, refer to Patent Document 1). However, there is a problem that the bonding temperature of the film adhesive layer to the wafer is 15 ° C. or more and 60 ° C. or less and there is initial tackiness, but the adhesive strength is low because it peels after processing.
Also, (a) a mold release having a thermosetting resin A layer on one side by applying and drying a thermosetting resin A that can be bonded to the metal foil by reheating even after heat curing. A step of preparing a film, (b) a prepreg obtained by impregnating and drying a thermosetting resin on a sheet-like base material is laminated on the layer side of the thermosetting resin A of the release film, and integrated by heat and pressure molding Forming a plate-like body, (c) making a through hole at a predetermined position of the plate-like body with or without peeling off the release film, and (d) thermosetting the plate-like body having undergone the above-mentioned step. A process for producing a metal foil-clad laminate characterized by passing through the steps (a) to (d) of the step of laminating a metal foil on the layer side of the conductive resin A and integrating it by heat and pressure molding is known. (For example, see Patent Document 2). However, it is thermoset even in a film state, it is thermoset even if integrated by heat and pressure molding, and there is a disadvantage that there are two thermoset steps, and the number of steps increases, and (b) Although the prepreg obtained by impregnating and drying the thermosetting resin on the sheet-like base material is laminated on the layer side of the thermosetting resin A, the process is integrated to form a plate-like body by heating and pressing, and the process is similar. The two-layer construction of “thermosetting resin A / thermosetting resin impregnated and dried and prepreg” has a large number of steps, and there is also a problem that strong adhesive strength cannot be obtained.
In addition, there are some thermosetting sheets with initial adhesion, but adhesive sheets with initial adhesion are generally made by adding an adhesive resin such as acrylic to the adhesive layer. It has been found that the adhesive strength decreases by adding. As a result, it was difficult to produce a pressure-sensitive adhesive sheet satisfying an adhesive strength of 15 to 20 MPa required for automotive applications.

  In order to solve the above-described problems, the present inventors have made extensive studies and have completed the present invention. The purpose is to provide an adhesive sheet satisfying the following performance. (1) It can bond metals, metal and organic material, and organic material and organic material. (2) Adhesive strength must be strong so that it can be used for structural purposes. (3) Adhesive strength should not deteriorate with temperature change. (4) It has initial tackiness, has no steps such as preheating, and has a small number of work steps. (5) Good handling and good workability in joining work with adherends.

In order to solve the above problems, the adhesive sheet according to the first aspect of the present invention comprises a first release paper, an adhesive layer, and a second release paper, and has both adhesiveness and adhesiveness. An adhesive sheet, wherein the adhesive layer is obtained by impregnating a core material composed of a liquid crystal polymer nonwoven fabric with an adhesive, and the adhesive includes an acrylic resin, an epoxy resin, and a curing agent. see containing the epoxy resin, to include a modified epoxy resin to contain a rubber component, bisphenyl skeletons, bisphenol skeleton, an epoxy resin having in the main chain either stilbene skeleton is obtained by.
The adhesive sheet according to the invention of claim 2 is the adhesive sheet according to claim 1, wherein the core material has a specific gravity of 0.15 or less.
According to a third aspect of the present invention, there is provided an adhesive sheet according to the first or second aspect, wherein the adhesive layer is formed such that an acrylic resin and an epoxy resin have a sea-island structure.
The adhesive sheet according to the invention of claim 4 is the adhesive sheet according to claims 1 to 3, the adhesive sheet according to the invention of claim 4 is the adhesive sheet according to claims 1 to 3, wherein the acrylic resin is ethyl acrylate-butyl acrylate. -An acrylic ester copolymer obtained by radical polymerization of a monomer having acrylonitrile , wherein the epoxy resin is composed of a nitrile butadiene rubber- modified epoxy resin and a bisphenol A type epoxy resin, and the curing agent is a dicyandiamide compound. As it was.
The pressure-sensitive adhesive sheet according to the invention of claim 5 is an acrylic ester copolymer obtained by radical polymerization of the monomer having ethyl acrylate-butyl acrylate-acrylonitrile in claim 1 to 3 of the acrylic resin. As you can see.
A bonding method according to a sixth aspect of the present invention is the bonding method according to any one of the first to fifth aspects, wherein the adhesive layer exposed by peeling and removing the release paper of the adhesive sheet is the same or different first adherend. And the second adherend, the adhesive layer is held with the adhesiveness, and the pressure-adhesive layer is cured by pressurization to adhere the first adherend and the second adherend. It is what you did.

According to the present invention of claim 1, since it has initial adhesiveness, the number of steps can be reduced by eliminating steps such as preheating, the handling property in the joining operation is excellent, and the workability is good. The adhesive strength is strong, and it has the effect of hardly deteriorating even with temperature changes.
According to the present invention of claim 2, in addition to the effect of claim 1, there is an effect that a stronger adhesive strength can be obtained.
According to the third aspect of the present invention, in addition to the effects of the first and second aspects, there is an effect that the metal and the organic material can be more strongly bonded with more stable initial tackiness.
According to this invention of Claim 4, in addition to the effect of Claims 1-3, there exists an effect which can select the material of the metal which is a to-be-adhered body, and an organic material more freely.
According to the present invention of claim 5, in addition to the effects of claims 1 to 3 , the dispersibility with the epoxy resin, the applicability and the film formability when forming the adhesive layer, The effect which can ensure the initial tackiness of an adhesive layer is produced.
According to the present invention of claim 6, since it has initial adhesiveness, it is possible to eliminate steps such as preheating, it is not necessary to temporarily fix, the handling property in the joining work is excellent, the workability is good, and the low There is an effect that can be joined at a cost.

It is sectional drawing of the adhesive sheet | seat which shows one Example of this invention. It is sectional drawing of the adhesive sheet which shows a prior art example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Adhesive Sheet) As shown in FIG. 1, the adhesive sheet 1 of the present invention comprises a first release paper 21A, an adhesive layer 11, and a second release paper 21B, and is adhesive. The layer 11 is obtained by impregnating a core material 15 made of a liquid crystal polymer nonwoven fabric with an adhesive 13, and the adhesive 13 includes an acrylic resin, an epoxy resin, and a curing agent, and is tacky and adhesive. Is an adhesive sheet having both Moreover, it is preferable that the specific gravity of the core material 15 shall be 0.15 or less. Further, the acrylic resin is an acrylic ester copolymer obtained by radical polymerization of a monomer having EA-BA-AN, and the epoxy resin comprises a nitrile butadiene rubber- modified epoxy resin and a bisphenol type epoxy resin, The curing agent is preferably a dicyandiamide compound. Note that EA-BA-AN represents ethyl acrylate-butyl acrylate-acrylonitrile. The adhesive sheet according to the invention of claim 2 is the adhesive sheet according to claim 1, wherein the core material has a specific gravity of 0.15 or less.

The most preferable adhesive 13 is an acrylic resin and an epoxy resin, and the epoxy resin is at least an NBR (nitrile butadiene rubber) -modified epoxy resin that is a soft rubber-like epoxy resin, and is hard. A bisphenol-type epoxy resin is used, and the acrylic resin is an acrylate copolymer obtained by radical polymerization of a monomer having EA-BA-AN having adhesiveness, and the curing agent is dicyandiamide. By using a system compound, the thermosetting adhesive sheet 1 satisfying the following performance and having initial adhesion can be obtained. That is, the adhesive sheet 1 has (1) initial tackiness, no steps such as preheating and good workability, and (2) adhesion between metals, metal and organic material, and organic material and organic material. (3) Adhesive strength is strong so that it can be used for structural purposes. (4) Adhesive strength does not deteriorate due to temperature changes. (5) Good handling in joining work with adherend. Effects such as good properties can be obtained.

  (Release paper) In this specification, the first release paper 21A and the second release paper 21B are collectively referred to as release paper 21. Further, the first release paper 21A and the second release paper 21B may be the same or different. The release paper 21 is also called a release film, a separate paper, a separate film, a separate paper, a release film, and a release paper. The release paper 21 has a release layer on one or both sides of a release paper substrate such as fine paper, coated paper, impregnated paper, and plastic film.

  (Release layer) 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 and the like. These resins can be used in any of emulsion type, solvent type and solventless type.

  (Formation of Release Layer) The release layer is formed by applying a coating liquid in which a release layer component is dispersed and / or dissolved on one surface of a release film base film, followed by heating and drying and / or curing. As a coating method of the coating liquid, a known and arbitrary coating method can be applied, and examples thereof include roll coating, gravure coating, and spray coating. 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.

  (Peeling force) The peeling force of the release layer is preferably about 1 to 2000 mN / cm and more preferably 100 to 1000 mN / cm with respect to the pressure-sensitive adhesive tape. When the release force of the release layer is less than 1 mN / cm, the release force from the pressure-sensitive adhesive sheet or the material to be bonded 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 workability, addition and / or polycondensation-type curable silicone resins for release paper, which are mainly composed of polydimethylsiloxane, are preferred.

  (Adhesive) As the adhesive 13, an acrylic resin having tackiness, an epoxy resin having adhesiveness to an adherend, and a curing agent that reacts with these resins are included. The adhesive sheet 1 having both adhesiveness and adhesiveness can be obtained.

(Epoxy) Examples of the epoxy resin include bisphenol type epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin, novolac type epoxy resins such as novolac epoxy resin and cresol novolac epoxy resin, biphenyl type epoxy resin, and stilbene type. Examples include epoxy resins such as epoxy resins, triphenolmethane type epoxy resins, alkyl-modified triphenolmethane type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene-modified phenol type epoxy resins, and also phenol novolac resins and cresol novolak resins. , Novolak type phenolic resin such as bisphenol A novolac resin, phenolic resin such as resol phenolic resin, urea (urea) resin, melamine resin, etc. Resins having a triazine ring, unsaturated polyester resins, bismaleimide resins, polyurethane resins, diallyl phthalate resins, silicon resins, resins having a benzoxazine ring, cyanate ester resins can be exemplified.

  From these resins, it is preferable to include at least a relatively soft epoxy resin and a hard epoxy resin. Here, “soft” and “hard” are relative comparisons, and a soft or hard material having a difference in hardness may be used.

(Hard epoxy) As the hard epoxy resin, a crystalline epoxy resin is preferable, and a rigid structure such as a biphenyl skeleton, a bisphenol skeleton, and a stilbene skeleton has a main chain and a relatively low molecular weight. Preferably, for example, bisphenol type epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin, and bisphenol A type epoxy resins are particularly preferable. 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. Among the crystalline epoxy resins, those that are crystallized and solid at room temperature also rapidly melt and change to a low-viscosity liquid when the temperature reaches the melting point or higher, so that the adhesive portion of the adhesive layer 13 is covered. It is possible to increase the adhesive strength by closely adhering to the back surface of the adherend in the initial stage and further adhering. A hard 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).

As the hard epoxy resin, a bisphenol A type epoxy resin is preferable, but it is more preferable to use a plurality of different hardnesses. Examples of the plural include ones having different numbers of main chains of a bisphenol skeleton having a rigid structure. For example, a bisphenol A type epoxy resin having a main chain of 1 to 3 and a bisphenol A type epoxy having a main chain of 2 to 10 What is necessary is just to use resin together. By using together, since some softness | flexibility can be obtained, maintaining mechanical strength, it is excellent in adhesiveness. By mixing solid epoxy, the film forming property can be improved. Here, the difference in hardness is a relative comparison, and it is sufficient if there is a difference in hardness, and a harder one or a harder one may be used. Specifically, as a bisphenol A type epoxy resin having a main chain of 1 to 3, manufactured by Japan Epoxy Resin Co., Ltd., JER828 is used as a bisphenol A type epoxy resin having a main chain of 2 to 10 manufactured by Japan Epoxy Resin Co., Ltd. JER1001 etc. can be illustrated.

  (Soft Epoxy) As the soft epoxy resin, an epoxy resin modified to include a rubber component is preferable. In particular, NBR (nitrile butadiene rubber) -modified epoxy resin is preferable because it is less likely to discolor due to heating and is easily mixed with a crystalline epoxy resin that is a hard epoxy resin. Specific examples include EPR4030 manufactured by ADEKA. In order to follow dimensional changes due to thermal expansion of the adherend, it is excellent in terms of improved heat resistance, impact resistance and flexibility.

The (acrylic) acrylic resin is not particularly limited as long as it has adhesiveness. For example, in addition to a polymer obtained by polymerizing acrylic acid, methacrylic acid and ester monomers thereof, non-polymerizable with the above monomers. A copolymer obtained by copolymerizing a saturated monomer (for example, vinyl acetate, styrene, acrylonitrile, etc.) can be used. As the acrylic resin, an acrylate copolymer is preferable, and a copolymer having at least one of acrylic acid, acrylic acid ester, methacrylic acid ester, and acrylonitrile as a monomer component is exemplified. Among these, an acrylate copolymer having a compound having an epoxy group, a hydroxyl group, a carboxyl group, a nitrile group, or the like as a functional group is preferable. Thereby, the adhesiveness to a to-be-adhered body improves more. Specific examples include SG-P3 manufactured by Nagase ChemteX Corporation.

  Particularly preferably, the acrylic resin is an acrylic ester copolymer formed by radical polymerization of a monomer having EA-BA-AN (ethyl acrylate-butyl acrylate-acrylonitrile), In addition, it is possible to improve applicability and film formability when forming the adhesive layer 11. Moreover, it is possible to ensure the initial tackiness of the adhesive layer 11.

  The weight average molecular weight of the acrylate copolymer is not particularly limited, but is preferably 100,000 or more, particularly preferably 150,000 to 1,000,000, and application of the adhesive 13 when the weight average molecular weight is within this range. Improves. In order to increase the cohesive strength, a rosin resin, a terpene resin, a coumarone resin, a phenol resin, a tackifier such as an aliphatic or aromatic petroleum resin, and the like may be added.

(Curing agent) Examples of the curing agent include aliphatic polyamines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylylene diamine (MXDA), diaminodiphenylmethane (DDM), and m-phenylenediamine (MPDA). In addition to aromatic polyamines such as diaminodiphenylsulfone (DDS), amine curing agents such as polyamine compounds including dicyandiamide (DICY) and organic acid dihydralazide, 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 curing agent, Phenolic curing agent such as Nord resin can be exemplified. In particular, dicyandiamide (DICY) is a latent curing agent, and thus is excellent in storage stability and has a pot life of several weeks even at room temperature storage. Moreover, you may include imidazoles as a hardening accelerator.

  (Additives) Further, the adhesive 13 may be processed, for example, in terms of workability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, releasability, difficulty. For the purpose of improving and modifying flammability, antifungal 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.

  (Sea Island) The adhesive 13 is mainly composed of an acrylic resin and an epoxy resin, but a sea island structure is preferable. It is preferable that the acrylic resin is in a sea state and the epoxy resin is in an island state in the sea. Although epoxy resin consists of multiple types, it is presumed to be in a compatible state. With this preferable structure, it is presumed that the sea state of the acrylic resin develops initial tackiness, and the island-shaped poxy resin comes into contact with and adheres to the adherend by pressure heating. Further, the dispersed state is preferable because a certain distance (several μm) at which the sea and the islands do not come into contact with each other can be avoided, and the interface strength can be kept high.

(Blend ratio) The adhesive 13 is composed of an acrylic resin, a hard epoxy resin, and a soft epoxy resin, and the blend ratio is acrylic resin: hard epoxy resin: soft epoxy resin: curing agent = 100: 75 to 175: 10 to about 100: 2 to 20, preferably acrylic resin: hard epoxy resin: soft epoxy resin = 100: 100 to 150: 25 to 75: 5 to 10. In addition, when using two or more hard epoxy resins, it is set as the sum total.
If the hard epoxy resin and the soft epoxy resin are less than this range with respect to the acrylic ester copolymer, the adhesive strength is too strong, resulting in defects when work needs to be replaced or reduced workability. In other words, the adhesive strength with the adherend is reduced. Above this range, the adhesive strength with the adherend is improved, but the adhesive strength is low, and temporary fixing is required and workability is reduced. Moreover, when the compounding 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. Above this range, the adhesive sheet 1 is stored until it is bonded to the adherend, but the shelf life of that period is lowered, and the unreacted curing agent remains, resulting in a problem that the adhesive strength is reduced. There is also a point.

  (Core material) As the core material 15, a liquid crystal polymer nonwoven fabric is used. The state in which the core material 15 is impregnated with the adhesive 13 is the adhesive layer 11. As the liquid crystal polymer, a polyarylate-based liquid crystal polymer is preferable, and a liquid crystal polymer made of wholly aromatic polyester is more preferable. The liquid crystal polymer non-woven fabric is preferably processed into a non-woven fabric by a melt blown method in which a liquid crystal polymer melted at a high temperature is sprayed on a mesh and fibers are instantly entangled to form a sheet directly. Specific examples include Kuraray's brand name Veclus.

The core material 15 made of a liquid crystal polymer non-woven fabric has the following characteristics and is reflected in the adhesive layer 11, so that it can be used for applications requiring these characteristics. (1) Water absorption; has a non-polar chemical skeleton and highly oriented microstructure, and has a low water absorption of 0.02% or less at a relative humidity of 65%, making it difficult to absorb water. Unaffected, good long-term reliability and hygroscopic dimensional stability. (2) Electrical characteristics: Since it is a skeleton with little polarity, it has excellent dielectric characteristics and electrical characteristics with low dielectric constant and dielectric loss tangent, dielectric constant in the GHz band is 2.8, and dielectric loss tangent is 0.002. It exhibits high signal propagation speed and low transmission loss, and its dielectric loss tangent value of 10 GHz or higher is lower than various glasses.
(3) Chemical properties; stable chemical structure and high orientation, chemical resistance to acids, alkalis, oxidants, solvents and lubricants. (4) Radiation properties: Excellent radiation resistance to withstand 100 mega gray radiation. (5) Voltage: Veculus (Kuraray Co., Ltd., trade name of liquid crystal polymer nonwoven fabric) whose density is adjusted to 1.3 has a withstand voltage of 30 KV / mm. (6) Cost: Since it is produced by a melt blow method, it has excellent processing characteristics, a simple process, can be produced at low cost, and has a fineness. (7) Flame retardancy: V-0 in UL94 standard. The LOI value is 28 and excellent flame retardancy. Further, the liquid crystal polymer nonwoven fabric constituting the core material 15 is composed of fibers having strength and elasticity that are several times that of general-purpose fibers. Further, the melting point is 350 ° C., and the decomposition point is 400 ° C. or more. have.

(Specific gravity) The adhesive layer 11 impregnates an adhesive 13 into a core 15 made of a liquid crystal polymer nonwoven fabric. It is preferable that the adhesive layer 11 includes the core material 15 because the handling is good and the workability of the joining work is improved. However, the adhesive strength with the adherend may be reduced. Then, workability and adhesive strength can be made compatible by setting the specific gravity of the core material 15 to 0.15 or less. The relationship between specific gravity and adhesive strength will be described in detail in Examples. The specific gravity (g / cm ³ ) can be calculated from the basis weight (g / mm ² ) and thickness (μm).

  (Manufacturing method) First, the adhesive 13 composition for forming the adhesive layer 11 is produced, and this adhesive 13 composition is apply | coated to the core material 15 surface piled up on the release paper 21. That's fine. When using multiple types as a hard epoxy resin using a stirrer, first mix and stir, then mix and stir the curing agent, dilute with a solvent, mix and stir the soft epoxy resin, and then acrylic The system resin was mixed and stirred to obtain an adhesive 13 composition. The core material 15 is impregnated by applying the adhesive 13 composition to the surface of the core material 15 by running the first release paper 21A and the core material 15 by using the coating method. After drying, the second release paper 21 </ b> B is bonded to the coated surface to obtain the adhesive sheet 1.

  (Stirring) The stirrer for producing the adhesive 13 composition may be prepared by mixing desired materials, kneading and dispersing as necessary, and is not particularly limited. Conventional kneading and dispersing machines such as two-roll mills, three-roll mills, pebble mills, tron mills, Szegvari attritors, high-speed impeller dispersers, high-speed stone mills, high-speed impact mills, despers, high-speed mixers, ribbon blenders, and kneaders Intensive mixers, tumblers, blenders, dispersers, homogenizers, ultrasonic dispersers, and the like can be applied.

  (Coating method) The coating method is not particularly limited. For example, roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coating, blade coating, bar coating, Wire bar coat, die coat, lip coat, dip coat, etc. can be applied. The first release paper 21A and the core material 15 are overlapped with each other, applied to the surface of the core material 15 by the coating method described above, and dried, and then the second release paper 21B may be bonded. The viscosity of the composition (coating liquid) is adjusted to about 1 to 20000 centistokes (25 ° C.), preferably 1 to 200 centistokes. When the core material 15 is impregnated and applied, the lower viscosity is preferable, and the viscosity is 1 to 100 centistokes.

  (Adhesion method) Bonding with an adherend peels and removes the first release paper 21A and the second release paper 21B of the adhesive sheet 1 to expose the adhesive layer 11. The exposed adhesive layer 11 is sandwiched between two identical or different first adherends and second adherends, and is held by 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. The heating temperature in this case is about 100 to 300 ° C, preferably 150 to 250 ° C. The heating time is 1 to 240 minutes, preferably 10 to 60 minutes. Since the adhesive layer 11 of the cured adhesive sheet 1 has initial tackiness, there is no preheating step, and the work can be performed while holding the adherend only with the adhesive force, so that the workability is good and low. In addition, since the core material 15 is included in the adhesive layer 11, the adhesive layer 11 has a waist and good handling properties. Therefore, the workability is improved and the joining work can be performed at a lower cost.

  Further, by selecting the material of the adhesive layer 11 and the blending ratio thereof, it is possible to join metals, metals and organic materials, inorganic materials and inorganic materials, organic materials and organic materials, and inorganic materials and organic materials. it can. 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. Furthermore, even if the adhesive strength 11 is the adhesive layer 11 including the core material 15 to the adhesive 13, a liquid crystal polymer nonwoven fabric is used as the core material 15 and the specific gravity is 0.15 or less. It can maintain by doing, and can make workability and adhesive strength compatible.

  (Adherent) Examples of the adherend include metals, inorganic materials, organic materials, composite materials combining these materials, and laminated materials.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, it is not limited to this. In addition, each composition of each layer is the mass part of solid content except a solvent. Further, the bisphenol A type epoxy resin (main chain 1 to 3) is referred to as EPX-1, the bisphenol A type epoxy resin (main chain 2 to 10) is referred to as EPX-2, and the NBR modified epoxy resin is referred to as EPX-3.

Example 1 The following raw materials were mixed with a stirrer to prepare an adhesive 13 composition.
・ Acrylic ester copolymer 100 parts ・ EPX-1 50 parts ・ EPX-2 100 parts ・ EPX-3 50 parts ・ Dicyandiamide 7 parts Next, as a core material 15, a specific gravity 0.144 g / cm ³ ) (Product name) manufactured by Kuraray Co., Ltd.) (Separator Film SP-PET03BU Tosero) was used as the release paper 21A. The core material 15 was stacked on the release paper 21A, and the adhesive 13 composition was coated on the surface of the core material 15 with a comma coater so that the coating amount after drying was 50 g / m ² and dried. Later, as light release release paper 21B, (separate film SP-PET01BU manufactured by Toh Cello) was pasted to obtain an adhesive sheet 1 of Example 1.

(Reference Example 1) An adhesive sheet 1 of Reference Example 1 was obtained in the same manner as in Example 1 except that the specific gravity of the core material 15 was 0.190 g / cm ³ .

(Reference Example 2) An adhesive sheet 1 of Reference Example 2 was obtained in the same manner as in Example 1 except that the specific gravity of the core material 15 was 0.409 g / cm ³ .

Reference Example 3 An adhesive sheet 1 of Reference Example 3 was obtained in the same manner as in Example 1 except that the specific gravity of the core material 15 was 0.246 g / cm ³ .

Reference Example 4 An adhesive sheet 1 of Reference Example 3 was obtained in the same manner as in Example 1 except that a vesicle having a specific gravity of 0.575 g / cm ³ of the core material 15 was used.

  Comparative Example 1 An adhesive sheet 1 of Comparative Example 1 was obtained in the same manner as in Example 1 except that the core material 15 was not added.

  (Evaluation method) Evaluation was made based on the adhesion strength (tensile shear force) between CFRP substrates, initial adhesive strength to the CFRP substrate, thermal cycle properties, and joining workability. The results are shown in Table 1.

  (Measurement Method) <Measurement Method of Adhesive Strength> The adhesive sheets 1 of Examples and Comparative Examples are cut into 25 mm × 12.5 mm, the release paper 21A is peeled off and removed, and a CFRP substrate ( Affixed to the tip of length 100 mm × width 25 mm × thickness 1.5 mm, and then release paper 21B is peeled off and removed, and CFRP substrate (length 100 mm × width 25 mm × thickness) as another adherend 1.5 mm) was attached to the tip, and 3 kg of weight was placed on the top of the stack, and heat cured at 180 ° C. for 1 hour to obtain a laminate, which was used as a test piece. Both ends of this evaluation sample were fixed to Tensilon (Orientec RTA-1T), pulled at 0.5 mm / min, and the shear strength was measured.

  <Method for Measuring Initial Adhesive Strength> An adhesive sheet that was allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH was cut into a width of 25 mm and a length of 250 mm to obtain a test sample. Thereafter, the upper release film of the adhesive sheet sample is peeled off and placed on the cleaned glass plate so that the adhesive surface is in contact. From there, it was pasted with a manual crimping apparatus (JIS0237), with a crimping speed of about 5 mm / sec, one reciprocation. One of the pasted test pieces was peeled off at a speed of 300 mm / min with Tensilon (Orientec RTC1310A), and the stress at that time was defined as adhesive strength. The peel strength between the release sheet and the pressure-sensitive adhesive layer is desirably in the range of 100 to 1,700 g, preferably in the range of 500 to 1,400 g, in the peeling method at 180 °.

  <Thermal cycleability> Using the laminate obtained by laminating two CFRP base materials on the adhesive sheet 1 of the example and the comparative example, after leaving at −40 ° C. for 30 minutes, leaving at + 150 ° C. for 30 minutes is 1 As a cycle, even after 500 cycles, the case where there was no significant change in the adhesive strength was accepted and the mark “◯” was marked, and the one that was clearly deteriorated was rejected and marked “x”.

  <Jointing workability> Using the adhesive sheets 1 of Examples and Comparative Examples, when preparing a sample for evaluation of <Measurement method of adhesive strength>, the handling property was observed, and an acceptable sample was regarded as acceptable. “○” marks were marked as “X” marks, which were clearly rejected as difficult to work.

  (Evaluation result) In Comparative Example 1, the joining workability was poor, and in Reference Examples 1 to 4, the adhesive strength by the core material 15 was slightly lowered. In Example 1, it was 19.2 MPa, which was slightly lower than the adhesive strength without the core material 15, but 15 MPa or more was maintained and was good, and it was in a range that could be applied to structural uses. In Reference Examples 1 to 4, although it was lower than the adhesive strength without the core material 15, 7.5 to 13.3 MPa was maintained, and it was in a usable range depending on the application.

  (Industrial Applicability) The main application of the adhesive sheet of the present invention is to strengthen materials (adherents) such as glass fiber and carbon fiber FRP, which are difficult to use with conventional welding methods. It can be joined to a member related to a transport machine such as an automobile. However, it has initial tackiness, has no preheating process, has good workability, can bond metals, metal and organic material, organic material and organic material, and has strong adhesive strength, and adhesive strength is temperature If it is an application that requires resistance to deterioration due to changes, it is not particularly limited. Printed wiring boards, IC package boards, high frequency electronic parts, heavy electrical parts, special motors, aircraft honeycombs It can also be used for other purposes.

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

Claims (6)

An adhesive sheet comprising a first release paper, an adhesive layer, and a second release paper, having both adhesiveness and adhesiveness, wherein the adhesive layer is adhesive to a core material made of a liquid crystal polymer nonwoven fabric agent becomes impregnated, the adhesive is an acrylic resin, saw-containing epoxy resin, and a curing agent, the epoxy resin is a modified epoxy resin to contain a rubber component, bisphenyl skeletons, An adhesive sheet comprising an epoxy resin having a bisphenol skeleton or a stilbene skeleton as a main chain .   The adhesive sheet according to claim 1, wherein the core material has a specific gravity of 0.15 or less. The adhesive sheet according to any one of claims 1 to 2, wherein the acrylic resin and epoxy resin of the adhesive layer have a sea-island structure. The acrylic resin is ethyl acrylate - butyl acrylate - a monomer with acrylonitrile in acrylate copolymer obtained by radical polymerization, before Symbol epoxy resin and a nitrile butadiene rubber-modified epoxy resins, bisphenol A type epoxy resin becomes, the adhesive sheet according to claim 1, before Symbol curing agent characterized in that it is a compound of dicyandiamide. The adhesive sheet according to any one of claims 1 to 3, wherein the acrylic resin is an acrylate copolymer obtained by radical polymerization of a monomer having ethyl acrylate-butyl acrylate-acrylonitrile. . The said adhesive layer exposed by peeling and removing the release paper of the adhesive sheet according to any one of claims 1 to 5 is composed of two same or different first and second adherends. A bonding method characterized in that the first and second adherends are bonded to each other by holding and holding with the adhesiveness of the adhesive layer and curing the adhesive layer by heating under pressure.

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