Adhesive sheet, adhesive composition, and structure

Abstract

The present invention provides an adhesive sheet for bonding a first member and a second member, the tensile modulus of elasticity of the first member being smaller than the tensile modulus of elasticity of the second member, and the elongation at break of the adhesive sheet being 60% or more. The tensile modulus of elasticity after curing of the adhesive sheet is equal to or greater than the tensile modulus of elasticity of the first member, and the tensile shear adhesive strength after curing of the adhesive sheet is 10 MPa or greater.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet, an adhesive composition and a structure. Background Art

[0002] Adhesives for bonding two components are used in various fields. In recent years, adhesives for bonding dissimilar materials have been developed. As such adhesives, for example, Patent Documents 1 and 2 propose epoxy resin adhesives.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5888349

[0006] Patent Document 2: Japanese Patent No. 6067828 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In a structure having a cured adhesive layer between two adherends comprising heterogeneous materials, the cured adhesive layer comprising a cured product of an adhesive composition, the cured adhesive layer may be strained due to external force or temperature change. At this time, if the strain of the cured adhesive layer is large, positional displacement of the adherend may occur in the above structure.

[0009] For example, in the case of a strain sensor being bonded to a measurement object using an adhesive, if the strain of the cured adhesive layer is large, the strain cannot be accurately measured. Also, in the case of a strain sensor being bonded to a strain generating body using an adhesive, if the strain of the cured adhesive layer is large, the strain cannot be accurately measured. This is a major cause of malfunction.

[0010] In addition, in the recent trend of miniaturization and multifunctionalization of electronic equipment, the high density of electronic components is further required. Therefore, in a substrate with built-in components, as the electronic components are denser, high position accuracy is required. However, when the electronic components are bonded to the substrate with built-in components using an adhesive, if the strain of the cured adhesive layer is large, there is a concern that the electronic components may shift or tilt. The shift or tilt of the electronic components becomes the cause of short circuit, reducing the reliability and insulation of the interlayer connection.

[0011] The present invention has been made in view of the above-mentioned actual situation, and a main object of the present invention is to provide an adhesive sheet and an adhesive composition capable of suppressing positional displacement of an adherend caused by strain of a cured adhesive layer.

[0012] Technical means of solving problems

[0013] One embodiment of the present invention provides an adhesive sheet having a tensile elastic modulus of 3.5 GPa or more after curing and a tensile shear adhesive strength of 10 MPa or more after curing.

[0014] Another embodiment of the present invention provides an adhesive sheet having an elongation at break of 60% or more, comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler, wherein the epoxy resin comprises a bisphenol A type epoxy resin and a trifunctional or higher epoxy resin, and the content of the inorganic filler is 30.0% by mass or more and 68.0% by mass or less.

[0015] Another embodiment of the present invention provides an adhesive sheet for bonding a first component to a second component, wherein the tensile elastic modulus of the first component is less than the tensile elastic modulus of the second component, the elongation at break of the adhesive sheet is greater than 60%, the tensile elastic modulus of the adhesive sheet after curing is greater than the tensile elastic modulus of the first component, and the tensile shear bonding strength of the adhesive sheet after curing is greater than 10 MPa.

[0016] Another embodiment of the present invention provides an adhesive sheet for bonding a first component to a second component, wherein the tensile elastic modulus of the first component is smaller than the tensile elastic modulus of the second component, the main material of the first component is a polyimide resin, the adhesive sheet contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler, the epoxy resin includes a bisphenol A type epoxy resin, and a trifunctional or higher epoxy resin, and the content of the inorganic filler is greater than 30.0% by mass and less than 68.0% by mass.

[0017] Another embodiment of the present invention provides an adhesive composition for bonding a first component to a second component, wherein the tensile elastic modulus of the first component is smaller than the tensile elastic modulus of the second component, the main material of the first component is a polyimide resin, the adhesive composition contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler, the epoxy resin includes a bisphenol A type epoxy resin, and a trifunctional or higher epoxy resin, and the content of the inorganic filler in the solid component of the adhesive composition is greater than 30.0 mass % and less than 68.0 mass %.

[0018] Another embodiment of the present invention provides a structure, which has a first component, a second component, and a cured adhesive layer that bonds the first component and the second component, wherein the first component is a resin component, the tensile elastic modulus of the cured adhesive layer is greater than 3.5 GPa, and the tensile shear bonding strength of the cured adhesive layer is greater than 10 MPa.

[0019] Effects of the Invention

[0020] The present invention can provide an adhesive sheet and an adhesive composition capable of suppressing positional displacement of an adherend due to strain of a cured adhesive layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic cross-sectional view showing an example of the adhesive sheet in the present invention.

[0022] Figure 2 This is a schematic cross-sectional view showing an example of the structure in the present invention. DETAILED DESCRIPTION

[0023] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings, etc. However, the present invention can be implemented in a variety of different ways, and is not to be interpreted in a restrictive manner by the contents of the embodiments illustrated below. In addition, in order to make the description clearer, the accompanying drawings sometimes show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual form, but it is ultimately an example and does not limit the interpretation of the present invention. In addition, in this specification and the drawings, the same elements as those described above with respect to the illustrated drawings are sometimes marked with the same symbols and the detailed description is appropriately omitted.

[0024] In this specification, when expressing a method of arranging another member on a certain member, if it is simply described as "on..." or "below...", unless otherwise specified, the following two cases are included: a case where another member is arranged directly above or directly below in a manner of contacting a certain member; and a case where another member is arranged above or below a certain member with other members interposed therebetween. In addition, in this specification, when expressing a method of arranging another member on the surface of a certain member, if it is simply described as "on the surface...", unless otherwise specified, the following two cases are included: a case where another member is arranged directly above or directly below in a manner of contacting a certain member; and a case where another member is arranged above or below a certain member with other members interposed therebetween.

[0025] In this specification, the term “sheet” also includes a member referred to as a “film.” In this specification, the term “film” also includes a member referred to as a “sheet.”

[0026] Hereinafter, the adhesive sheet, adhesive composition and structure in the present invention will be described in detail.

[0027] A. Adhesive sheet

[0028] The adhesive sheet in the present invention has four embodiments. Each embodiment will be described below.

[0029] I. First Embodiment of Adhesive Sheet

[0030] The first embodiment of the adhesive sheet in the present invention is an adhesive sheet for bonding a first component and a second component, the tensile elastic modulus of the first component is smaller than the tensile elastic modulus of the second component, the elongation at break of the adhesive sheet is greater than 60%, the tensile elastic modulus of the adhesive sheet after curing is greater than the tensile elastic modulus of the first component, and the tensile shear bonding strength of the adhesive sheet after curing is greater than 10 MPa.

[0031] Figure 1 2 is a schematic cross-sectional view illustrating an adhesive sheet according to this embodiment. Figure 1 As shown in the example, the adhesive sheet 1 of this embodiment usually has only an adhesive layer. The adhesive sheet 1 has predetermined physical properties.

[0032] In this embodiment, in the adhesive sheet used for bonding the first member and the second member, when the tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member, the rigidity of the adhesive sheet after curing can be improved by making the tensile elastic modulus of the adhesive sheet after curing equal to or greater than the tensile elastic modulus of the first member. Therefore, in a structure having a cured adhesive layer containing a cured product of the adhesive sheet between the first member and the second member, the strain of the cured adhesive layer due to external force and temperature change can be reduced. Thus, the position of the first member relative to the second member can be prevented from being offset due to the strain of the cured adhesive layer.

[0033] Here, as a method for improving the rigidity after curing of the adhesive sheet, for example, it is contemplated to add an inorganic filler. However, the addition of an inorganic filler has a tendency to cause the elongation of the adhesive sheet and the adhesive strength after curing to decrease. If the elongation of the adhesive sheet is low, then the processability will decrease, and therefore, for example, when the adhesive sheet is cut, cracks or fractures may occur.

[0034] In contrast, in this embodiment, the elongation of the adhesive sheet at break is above a predetermined value, and the tensile shear bonding strength of the adhesive sheet after curing is above a predetermined value. Therefore, the rigidity of the adhesive sheet after curing can be improved, and the processability can be improved, thereby improving the bonding strength after curing.

[0035] Hereinafter, each structure of the adhesive sheet of this embodiment will be described.

[0036] 1. Physical properties of adhesive sheet

[0037] (1) Elongation at break

[0038] The elongation at the time of fracture of the adhesive sheet of the present embodiment is more than 60%, preferably more than 100%, and more preferably more than 200%. By making the elongation at the above-mentioned fracture the above-mentioned range, processability can be improved. On the other hand, if the elongation at the above-mentioned fracture is too small, then, for example, when the adhesive sheet is cut, cracks or fractures may occur. In addition, the elongation at the above-mentioned fracture is, for example, less than 1000%, less than 500%, or less than 300%. If the elongation at the above-mentioned fracture is too large, the adhesive sheet may become too soft and difficult to operate. Specifically, the elongation at the above-mentioned fracture is more than 60% and less than 1000%, can also be more than 100% and less than 500%, can also be more than 200% and less than 300%.

[0039] Here, the elongation at break of the adhesive sheet is measured in accordance with JIS K7127: 1999. Specific measurement conditions are shown below. As a tensile tester, for example, "Tensilon RTF1150" manufactured by A&D Corporation is used.

[0040] (Measurement conditions)

[0041] ·Test piece: short strip with a width of 15 mm and a length of 150 mm

[0042] Distance between chucks: 100 mm

[0043] ·Stretching speed: 100 mm / min

[0044] Temperature: 23℃

[0045] Humidity: 50%RH

[0046] In addition, the elongation at break was calculated by the following formula.

[0047] Elongation at break (%) = (L-L0) / L0×100

[0048] (In the above formula, L0 is the length of the sample before the tensile test, and L is the length of the sample at fracture)

[0049] As a method for controlling the elongation at break of the adhesive sheet, for example, when the adhesive sheet contains an epoxy resin adhesive, the adhesive sheet may contain an acrylic resin. The acrylic resin can improve toughness and increase the elongation at break of the adhesive sheet.

[0050] (2) Tensile elastic modulus after curing

[0051] The tensile modulus of elasticity after curing of the adhesive sheet of the present embodiment is more than the tensile modulus of elasticity of the first member, preferably greater than the tensile modulus of elasticity of the first member. In this specification, the tensile modulus of elasticity of the first member refers to the tensile modulus of elasticity of the main material of the first member. That is, the tensile modulus of elasticity after curing of the adhesive sheet of the present embodiment is more than the tensile modulus of elasticity of the main material of the first member, preferably greater than the tensile modulus of elasticity of the main material of the first member. Thus, the rigidity of the adhesive sheet after curing can be improved. Therefore, in a structure having a cured adhesive layer of a cured product including an adhesive sheet between the first member and the second member, when the cured adhesive layer is strained due to external force or temperature change, the strain of the cured adhesive layer can be reduced. Thus, the positional offset of the first member relative to the second member caused by the cured adhesive layer can be suppressed.

[0052] In addition, the tensile elastic modulus of the adhesive sheet of the present embodiment after curing can be greater than the tensile elastic modulus of the first member, for example, it can be less than the tensile elastic modulus of the second member, or it can be greater than the tensile elastic modulus of the second member. In this specification, the tensile elastic modulus of the second member refers to the tensile elastic modulus of the main material of the second member. That is, the tensile elastic modulus of the adhesive sheet of the present embodiment after curing can be greater than the tensile elastic modulus of the main material of the first member, for example, it can be less than the tensile elastic modulus of the main material of the second member, or it can be greater than the tensile elastic modulus of the main material of the second member.

[0053] It should be noted that the tensile modulus of the adhesive sheet after curing refers to both the tensile modulus of the adhesive sheet in the MD direction and the tensile modulus of the adhesive sheet in the TD direction.

[0054] The MD direction refers to the direction in which the adhesive sheet is formed. The TD direction refers to the direction perpendicular to the MD direction. For example, when the adhesive sheet is in the form of a strip, the MD direction refers to the length direction of the adhesive sheet, and the TD direction refers to the width direction of the adhesive sheet.

[0055] Here, the tensile modulus of elasticity of the adhesive sheet after curing is measured in accordance with JIS K7127: 1999. Specific measurement conditions are shown below. As a tensile tester, for example, "Tensilon RTF1150" manufactured by A&D Corporation is used.

[0056] (Measurement conditions)

[0057] ·Test piece: short strip with a width of 15 mm and a length of 150 mm

[0058] Distance between chucks: 100 mm

[0059] ·Stretching speed: 1 mm / min

[0060] Temperature: 23℃

[0061] Humidity: 50%RH

[0062] When measuring the tensile elastic modulus of the adhesive sheet after curing, the curing conditions of the adhesive sheet are appropriately set according to the material of the adhesive sheet.

[0063] The main material of the first component is different depending on the composition of the first component. For example, when the first component is composed of a single component, the main material of the first component refers to the main component of the single component. In addition, for example, when the first component is composed of multiple components, the main material of the first component refers to the component with the smallest tensile elastic modulus among the tensile elastic moduli of the main components of each component. It should be noted that the main component refers to the component that contains the most.

[0064] The main material of the second member is different depending on the composition of the second member. For example, when the second member is composed of a single member, the main material of the second member refers to the main component of the single member. In addition, for example, when the second member is composed of a plurality of members, the main material of the second member refers to the member having the smallest tensile elastic modulus among the tensile elastic moduli of the main components of each member. It should be noted that the main component refers to the component that contains the most.

[0065] The tensile elastic modulus of the main material of the first member is different depending on the composition of the first member. For example, when the first member is composed of a single member, the tensile elastic modulus of the main material of the first member refers to the tensile elastic modulus of the main component of the single member. In addition, for example, when the first member is composed of a plurality of members, the tensile elastic modulus of the main material of the first member refers to the smallest tensile elastic modulus among the tensile elastic moduli of the main components of each member.

[0066] In addition, the tensile elastic modulus of the main material of the second member is different depending on the composition of the second member. For example, when the second member is composed of a single member, the tensile elastic modulus of the main material of the second member refers to the tensile elastic modulus of the main component of the single member. In addition, for example, when the second member is composed of a plurality of members, the tensile elastic modulus of the main material of the second member refers to the smallest tensile elastic modulus among the tensile elastic moduli of the main components of each member.

[0067] The tensile modulus of elasticity of the main material of the first component and the tensile modulus of elasticity of the main material of the second component are reference values. For example, reference values ​​recorded in "Nine Years of Science" (Maruzen Publishing) and Mechanical Engineering Handbook (Japan Society of Mechanical Engineers) can be used. It should be noted that the tensile modulus of elasticity is also called Young's modulus.

[0068] For reference, the tensile elastic modulus (Young's modulus) of some materials is shown.

[0069] Polyimide resin: 3.5 GPa to 4.5 GPa

[0070] Aluminum alloys: 65 GPa to 80 GPa

[0071] Glass-epoxy: 20 GPa to 30 GPa

[0072] In addition, as the analysis method of the material constituting the first member, a general analysis method can be applied, and it can be appropriately selected according to the material. The same applies to the analysis method of the material constituting the second member.

[0073] The tensile modulus of elasticity of the adhesive sheet of the present embodiment after curing only needs to be equal to or greater than the tensile modulus of elasticity of the main material of the first member, and can be appropriately set according to the tensile modulus of elasticity of the main material of the first member.

[0074] For example, when the main material of the first member is a polyimide-based resin, the tensile modulus of the adhesive sheet after curing is, for example, preferably 3.5 GPa or more, more preferably 4.0 GPa or more, and even more preferably 5.0 GPa or more.

[0075] For example, when the main material of the first member is a polyester resin, the tensile modulus of the adhesive sheet after curing is, for example, preferably 3.0 GPa or more, more preferably 3.5 GPa or more, and even more preferably 4.0 GPa or more.

[0076] In addition, the upper limit of the tensile elastic modulus of the adhesive sheet of the present embodiment after curing is not particularly limited, for example, it is less than 30 GPa, it can also be less than 20 GPa, and it can also be less than 10 GPa. Specifically, when the main material of the first component is a polyimide resin, the tensile elastic modulus of the adhesive sheet after curing is preferably 3.5 GPa or more and 30 GPa or less, more preferably 4.0 GPa or more and 20 GPa or less, and further preferably 5.0 GPa or more and 10 GPa or less. In addition, specifically, when the main material of the first component is a polyester resin, the tensile elastic modulus of the adhesive sheet after curing is, for example, preferably 3.0 GPa or more and 30 GPa or less, more preferably 3.5 GPa or more and 20 GPa or less, and further preferably 4.0 GPa or more and 10 GPa or less.

[0077] Examples of a method for controlling the tensile modulus of elasticity of the adhesive sheet after curing include a method of adding an inorganic filler to the adhesive sheet and a method of adjusting the crosslinking density of the adhesive sheet after curing.

[0078] The inorganic filler can increase the tensile modulus of the adhesive sheet after curing.

[0079] In the method of adjusting the crosslink density of the adhesive sheet after curing, as the crosslink density increases, the tensile modulus tends to increase. As a method of adjusting the crosslink density of the adhesive sheet after curing, for example, there is a method of making the adhesive sheet contain a multifunctional resin component.

[0080] (3) Tensile shear bond strength after curing

[0081] The tensile shear bonding strength after curing of the adhesive sheet of the present embodiment is more than 10 MPa, more preferably more than 15 MPa, and more preferably more than 20 MPa. By making the above-mentioned tensile shear bonding strength the above-mentioned range, excellent adhesion can be obtained. In addition, the upper limit of the above-mentioned tensile shear bonding strength is not particularly limited.

[0082] Here, the tensile shear bonding strength of the adhesive sheet after curing is measured in accordance with JIS K6850: 1999. As the bonded material, a cold-rolled steel sheet (SPCC-SD) with a thickness of 25 mm, a size of 100 mm × 16 mm, standard tempering treatment, and a matte surface treatment is used. In addition, as a tensile testing machine, for example, "TensilonRTF1350" manufactured by A&D Company is used. The specific measurement conditions are shown below.

[0083] (Measurement conditions)

[0084] Test piece: length 187.5 mm, width 25 mm

[0085] ·Stretching speed: 10 mm / min

[0086] Temperature: 23℃

[0087] Humidity: 50%RH

[0088] As a method for controlling the tensile shear bond strength after curing of the adhesive sheet, for example, a method for adjusting the crosslinking density of the adhesive sheet after curing can be cited. If the crosslinking density becomes higher, there is a tendency for the tensile shear bond strength to become larger. As a method for adjusting the crosslinking density of the adhesive sheet after curing, for example, a method for making the adhesive sheet contain a multifunctional resin component can be cited.

[0089] (4) Peak value of loss coefficient (tanδ) after curing

[0090] The peak value of the loss coefficient (tan δ) after curing of the adhesive sheet of the present embodiment is, for example, preferably above 120°C, but may also be above 130°C, or may also be above 150°C. If the peak value of the above tan δ is within the above range, the heat resistance can be improved. In addition, the peak value of the above tan δ is, for example, below 250°C, but may also be below 230°C, or may also be below 200°C. Specifically, the peak value of the above tan δ is above 120°C and below 250°C, but may also be above 130°C and below 230°C, or may also be above 150°C and below 200°C.

[0091] Here, tan δ of the adhesive sheet after curing is measured by dynamic viscoelasticity measurement (DMA) in accordance with JIS K7244-1:1998 and is determined according to the following formula.

[0092] Loss coefficient (tanδ) = loss modulus (M'') / storage modulus (M')

[0093] As a dynamic viscoelasticity measuring apparatus, for example, "RSA-III" manufactured by TA Instruments is used. Specific measurement conditions are shown below.

[0094] (Measurement conditions)

[0095] Accessory mode: Compact mode

[0096] Frequency: 1 Hz

[0097] Temperature: -50℃~300℃

[0098] Heating rate: 5℃ / min

[0099] In addition, when there are a plurality of tan δ peaks, the one with the higher temperature is taken as the tan δ peak.

[0100] As a method for controlling the peak value of tanδ after curing of the adhesive sheet, for example, a method of adjusting the crosslinking density of the adhesive sheet after curing can be cited. If the crosslinking density becomes higher, there is a tendency that the peak value of tanδ becomes larger. As a method for adjusting the crosslinking density after curing of the adhesive sheet, for example, a method of making the adhesive sheet contain a multifunctional resin component can be cited.

[0101] 2. Adhesive sheet material

[0102] The adhesive sheet of this embodiment preferably contains a thermosetting adhesive. If it is a thermosetting adhesive, it can be applied even when the first member and the second member are not transparent.

[0103] The adhesive sheet of the present embodiment preferably contains an epoxy resin adhesive. Specifically, the adhesive sheet of the present embodiment preferably contains an epoxy resin and a curing agent. Usually, the cured film of the epoxy resin adhesive is hard and tough, and is suitable for the bonding of components of hard materials such as metal components and glass components. In addition, the epoxy resin adhesive is usually excellent in heat resistance, insulation, chemical resistance, etc., has a small curing shrinkage, and can be applied to a wide range of uses.

[0104] Wherein, the adhesive sheet of present embodiment preferably contains epoxy resin, curing agent, acrylic resin, and inorganic filler.By containing acrylic resin, toughness is improved, and therefore the tendency of elongation increase when having fracture is increased.In addition, by containing inorganic filler, strength is improved, and therefore the tendency of tensile elastic modulus increase after curing is increased.

[0105] In particular, the epoxy resin preferably contains a trifunctional or higher epoxy resin. By containing a trifunctional or higher epoxy resin, the crosslinking density after curing becomes high, so there is a tendency for the tensile elastic modulus after curing and the tensile shear adhesive strength after curing to increase.

[0106] (1) Epoxy resin

[0107] Epoxy resin is a compound having at least one epoxy group or glycidyl group, which is cured by a cross-linking polymerization reaction when used in combination with a curing agent. Epoxy resin also includes monomers having at least one epoxy group or glycidyl group.

[0108] As epoxy resins, for example, aromatic epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins can be mentioned. Specifically, bisphenol epoxy resins, novolac epoxy resins, modified epoxy resins, biphenyl epoxy resins, distyrene epoxy resins, trisphenol methane epoxy resins, alkyl-modified trisphenol methane epoxy resins, epoxy resins containing triazine nuclei, dicyclopentadiene-modified phenol epoxy resins, and naphthalene epoxy resins can be mentioned. As bisphenol epoxy resins, for example, bisphenol A epoxy resins and bisphenol F epoxy resins can be mentioned. As novolac epoxy resins, for example, bisphenol A novolac epoxy resins, phenol novolac epoxy resins, and cresol novolac epoxy resins can be mentioned. As modified epoxy resins, for example, urethane-modified epoxy resins and rubber-modified epoxy resins can be mentioned. The epoxy resin may be used alone or in combination of two or more.

[0109] Among them, bisphenol epoxy resins are preferred, and bisphenol A epoxy resins are more preferred. Heat resistance can be improved by including a rigid epoxy resin having a bisphenol skeleton.

[0110] Bisphenol A epoxy resin can exist in a liquid state at room temperature or a solid state at room temperature, depending on the number of repeating units of the bisphenol skeleton. For example, a bisphenol A epoxy resin having a main chain bisphenol skeleton of 0 or more and 1 or less is liquid at room temperature. In addition, a bisphenol A epoxy resin having a main chain bisphenol skeleton of 2 or more and 10 or less is solid at room temperature.

[0111] The epoxy resin may include only a bisphenol A type epoxy resin that is solid at room temperature as the bisphenol A type epoxy resin, or may include only a bisphenol A type epoxy resin that is liquid at room temperature as the bisphenol A type epoxy resin, or may include a bisphenol A type epoxy resin that is solid at room temperature and a bisphenol type epoxy resin that is liquid at room temperature as the bisphenol A type epoxy resin.

[0112] If the bisphenol A epoxy resin, which is solid at room temperature, reaches a temperature above the melting point, it will melt quickly and become a low-viscosity liquid. Therefore, when the first component and the second component are bonded, the adhesive composition is made to fit the first component and the second component by heating, and then cured, so that the adhesive composition is firmly bonded to the first component and the second component. In addition, since the cross-linking density of such bisphenol A epoxy resin increases after curing, the mechanical strength is improved, the chemical resistance is improved, the curing property is improved, and the hygroscopicity is reduced (due to the reduction of free volume). Therefore, the bonding strength after curing can be improved.

[0113] In addition, by using a bisphenol A type epoxy resin which is solid at room temperature and a bisphenol type epoxy resin which is solid at room temperature in combination, it is possible to improve flexibility and film-forming properties while maintaining mechanical strength.

[0114] As described above, the epoxy resin preferably contains a trifunctional or higher-functional epoxy resin together with a bisphenol A-type epoxy resin.

[0115] Examples of the trifunctional or higher-functional epoxy resin include epoxy resins having a tris(hydroxyphenyl)methane structure, epoxy resins having a tetra(hydroxyphenyl)ethane structure, epoxy resins having an aminophenol structure, and epoxy resins having a bis(aminophenyl)methane structure.

[0116] The content ratio of bisphenol A epoxy resin to trifunctional or higher epoxy resin is, for example, 1:1 to 3:1 by mass, or 75:65 to 115:65. If the content ratio is within the above range, after curing, the bonding strength at room temperature is improved, and the bonding strength in a high-temperature hot water environment is also improved.

[0117] The epoxy resin preferably contains a phenol novolac epoxy resin together with a bisphenol A type epoxy resin and a trifunctional or higher epoxy resin. Heat resistance can be improved by containing a phenol novolac epoxy resin.

[0118] The content ratio of the bisphenol A type epoxy resin to the phenol novolac type epoxy resin is, for example, 100:50 to 100:20 on a mass basis, or 100:40 to 100:30.

[0119] The content of the epoxy resin is, for example, 40 parts by mass or more and 90 parts by mass or less relative to 100 parts by mass of the total amount of the resin component. In addition, the resin component contains the epoxy-modified silicone resin and acrylic resin described below in addition to the epoxy resin.

[0120] (2) Epoxy modified silicone resin

[0121] The adhesive sheet of this embodiment may contain epoxy-modified silicone resin. By containing epoxy-modified silicone resin, water resistance can be improved. In addition, heat resistance and flexibility (toughness) can be achieved at the same time.

[0122] Epoxy-modified silicone resin refers to a resin obtained by introducing an epoxy group or epoxy compound into a part of a silicone resin. Silicone resin is a compound having a polyorganosiloxane skeleton. Silicone resin is usually a compound in which the main skeleton (main chain) part mainly contains the repetition of an organosiloxane unit, and its main skeleton has at least one silanol group. Epoxy-modified silicone resin is obtained by the addition reaction of the silanol group with an epoxy compound. As long as the main skeleton of the silicone resin has at least one silanol group, it may also have a branched structure. In addition, epoxy-modified silicone resin may also be a reaction product of an epoxy resin and a silicone resin. For example, epoxy-modified silicone resin may also be a product obtained by the reaction of an OH group in an epoxy resin skeleton with a silanol group. It should be noted that the above-mentioned reaction product is considered to be an epoxy-modified silicone resin even if the reaction product is a reaction product in which one side of the epoxy resin is more and the silicone is apparently suspended from the epoxy resin. Epoxy-modified silicone resin can be used alone or in combination of two or more.

[0123] Examples of the epoxy-modified silicone resin include partial condensates of epoxy-modified silane compounds. Examples of the epoxy-modified silane compound include γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (γ-glycidyloxypropyl)(methyl)dimethoxysilane, (γ-glycidyloxypropyl)(ethyl)dimethoxysilane, (γ-glycidyloxypropyl)(methyl)diethoxysilane, (γ-glycidyloxypropyl)(ethyl)diethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](methyl)dimethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl)dimethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl)dimethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl)dimethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl) [2-(3,4-epoxycyclohexyl)ethyl](methoxy)diethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl)diethoxysilane, (γ-glycidyloxypropyl)(methoxy)dimethylsilane, (γ-glycidyloxypropyl)(methoxy)diethylsilane, (γ-glycidyloxypropyl)(ethoxy)dimethylsilane, (γ-glycidyloxypropyl)(ethoxy)diethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](methoxy)diethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](methoxy)diethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](ethoxy)dimethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](ethoxy)diethylsilane. The epoxy-modified silicone resin may be used alone or in combination of two or more.

[0124] The content of the epoxy-modified silicone resin is, for example, 5 parts by mass or more and 40 parts by mass or less relative to 100 parts by mass of the total amount of the resin components.

[0125] (3) Acrylic resin

[0126] As described above, the adhesive sheet of the present embodiment preferably contains an acrylic resin.

[0127] The acrylic resin is preferably compatible with the epoxy resin. Since the acrylic resin is compatible with the epoxy resin, the film forming property can be improved. In addition, since the acrylic resin is compatible with the epoxy resin, the toughness can be easily improved. Therefore, the elongation at break can be increased. In addition, the bonding strength after curing can be improved. Furthermore, a high bonding strength can be maintained.

[0128] Here, the compatibility of the acrylic resin and the epoxy resin in the curable adhesive sheet can be confirmed by, for example, the absence of micrometer-sized islands when observing the surface or cross-section of the adhesive sheet using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0129] The acrylic resin may be a homopolymer of an acrylate monomer and a mixed component containing two or more of the homopolymers, or a copolymer of two or more acrylate monomers and a component containing one or more copolymers. In addition, the acrylic resin may be a mixed component of the homopolymer and the copolymer. Specifically, the acrylic resin may be a mixture of a methacrylate polymer and an acrylate polymer, or may be an acrylate polymer such as acrylate-acrylate, methacrylate-methacrylate, or methacrylate-acrylate. Among them, the acrylic resin preferably contains a copolymer of two or more acrylate monomers.

[0130] In addition, regarding acrylic resin, "acrylic acid" also includes "methacrylic acid".

[0131] In addition, hereinafter, a "copolymer of two or more types of acrylate monomers" may be simply referred to as a "(meth)acrylate copolymer".

[0132] As the monomer components constituting the (meth)acrylate copolymer, for example, the monomer components described in Japanese Patent Publication No. 2014-065889 can be cited. The above-mentioned monomer components may also have the following polar groups. As the above-mentioned (meth)acrylate copolymer, for example, ethyl acrylate-butyl acrylate-acrylonitrile copolymer, ethyl acrylate-acrylonitrile copolymer, butyl acrylate-acrylonitrile copolymer can be cited.

[0133] The (meth)acrylate copolymer is preferably a block copolymer, and more preferably an acrylic block copolymer such as a methacrylate-acrylate copolymer. Examples of the (meth)acrylate constituting the acrylic block copolymer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, and benzyl acrylate.

[0134] Specific examples of methacrylate-acrylate copolymers include acrylic copolymers such as methyl methacrylate-butyl acrylate-methyl methacrylate (MMA-BA-MMA) copolymers. It should be noted that MMA-BA-MMA copolymers also include block copolymers of polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate (PMMA-PBA-PMMA).

[0135] The acrylic copolymer may not have a polar group, or may be a modified product obtained by introducing a polar group into a part thereof. Since the modified product is easily compatible with the epoxy resin, the bonding strength after curing is further improved. Examples of the polar group include epoxy, hydroxy, carboxyl, nitrile, and amide groups.

[0136] Among them, the acrylic resin is preferably a (meth)acrylate copolymer having a first polymer part having a glass transition temperature (Tg) of 10°C or less and a second polymer part having a glass transition temperature (Tg) of 20°C or more. Such a (meth)acrylate copolymer has a first polymer part that becomes a soft segment and a second polymer part that becomes a hard segment. By adding such a (meth)acrylate copolymer, the toughness before and after curing is improved, so that the elongation at break can be increased, and the adhesive strength after curing can be increased.

[0137] The manifestation of the above-mentioned effect can be inferred as follows. By using an acrylic resin having a soft segment and a hard segment together like the above-mentioned (meth) acrylate copolymer, the hard segment helps to improve heat resistance, and the soft segment helps to improve toughness or flexibility. Therefore, an adhesive sheet with good heat resistance, toughness and flexibility can be obtained. Therefore, it is believed that the elongation at break increases, and excellent adhesion can be obtained.

[0138] At least one of the first polymer part and the second polymer part contained in the (meth)acrylate copolymer is compatible with the epoxy resin. When the first polymer part is compatible with the epoxy resin, the flexibility can be improved. In addition, when the second polymer part is compatible with the epoxy resin, the cohesion and toughness can be improved.

[0139] In the case where one of the first polymer part or the second polymer part is not compatible with the epoxy resin, the (meth)acrylate copolymer has: a polymer part that is compatible with the epoxy resin, i.e., a compatible part, and a polymer part that is not compatible with the epoxy resin, i.e., an incompatible part. In this case, if the above-mentioned (meth)acrylate copolymer is added to the adhesive composition, the compatible part is compatible with the epoxy resin, and the incompatible part is not compatible with the epoxy resin, thereby producing fine phase separation. As a result, a fine sea island structure is revealed. The sea island structure varies depending on the type of the (meth)acrylate copolymer, the compatibility of the first polymer part and the second polymer part contained in the (meth)acrylate copolymer, and the presence or absence of modification based on the introduction of polar groups. For example, the following can be cited: a sea-island structure in which the compatible part of the cured epoxy resin and the (meth)acrylate copolymer is a sea and the incompatible part of the (meth)acrylate copolymer is an island; a sea-island structure in which the incompatible part of the (meth)acrylate copolymer is a sea and the compatible part of the cured epoxy resin and the (meth)acrylate copolymer is an island; a sea-island structure in which the (meth)acrylate copolymer is a sea and the cured epoxy resin is an island. By having such a sea-island structure, stress can be easily dispersed, so that interface damage can be avoided and excellent adhesion can be obtained after curing.

[0140] The above-mentioned (meth) acrylate copolymer is particularly preferably a block copolymer, and it is particularly preferred that the compatible site is set to polymer block A and the incompatible site is set to ABA block copolymer of polymer block B. It is further preferred that the first polymer part is the incompatible site, the second polymer part is the compatible site, the first polymer part is set to polymer block B, and the second polymer part is set to ABA block copolymer of polymer block A. By using such an ABA block copolymer as an acrylic resin, the island part can be reduced in the case of a sea island structure in which the compatible site of the cured product of epoxy resin and the (meth) acrylate copolymer is a sea and the incompatible site of the (meth) acrylate copolymer is an island structure such as an island, and the island part can be reduced. In addition, in the case of a sea island structure in which the incompatible site of the (meth) acrylate copolymer is a sea and the cured product of epoxy resin and the compatible site of the (meth) acrylate copolymer are an island structure such as an island, or in the case of a sea island structure in which the (meth) acrylate copolymer is a sea and the cured product of epoxy resin is an island, the sea part can be reduced. Therefore, after curing, the epoxy resin and the acrylic resin are in an apparently compatible state. By showing such an apparently compatible state, stress can be dispersed more easily after curing, so that interface destruction can be avoided and excellent bonding strength can be maintained.

[0141] The (meth)acrylate copolymer may be a modified product in which the polar group is introduced into a part of the first polymer part or the second polymer part. The compatibility with the epoxy resin is improved.

[0142] The Tg of the first polymer part contained in the (meth)acrylate copolymer may be 10°C or lower, -150°C to 10°C or lower, -130°C to 0°C or lower, or -110°C to -10°C or lower.

[0143] The Tg of the first polymer portion was calculated using the following formula based on the Tg (K) of each homopolymer described in “Polymer Handbook 3rd Edition” (published by John Wiley & Sons, Ink.).

[0144] 1 / Tg(K)=W1 / Tg1+W2 / Tg2+····+W n / Tg n

[0145] W n : Mass fraction of each monomer

[0146] Tg n: This is the Tg (K) of the homopolymer of each monomer, and a generally published value such as the value in the Polymer Handbook (3rd Ed., J. Brandrup and E. H. Immergut, WILEY INTERSCIENCE) may be used. The same applies to the Tg of the second polymer part described below.

[0147] The first polymer part contained in the above-mentioned (meth)acrylate copolymer may be a homopolymer or a copolymer, and a homopolymer is preferred. The monomer components and polymer components constituting the first polymer part may be monomer components and polymer components that can obtain the first polymer part having a Tg within a predetermined range, and examples thereof include: acrylate monomers such as butyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, and methyl acrylate, other monomers such as vinyl acetate, acetal, and urethane, polar group-containing monomers containing the above-mentioned polar groups, or copolymers such as EVA.

[0148] The Tg of the second polymer part contained in the (meth)acrylate copolymer may be 20°C or higher, 20°C or higher and 150°C or lower, 30°C or higher and 150°C or lower, or 40°C or higher and 150°C or lower.

[0149] The second polymer part contained in the (meth)acrylate copolymer may be a homopolymer or a copolymer, and a homopolymer is preferred. The monomer component constituting the second polymer part may be any monomer component that can obtain a second polymer part having a Tg within a predetermined range, and examples thereof include: acrylic acid ester monomers such as methyl methacrylate, acrylamide, styrene, vinyl chloride, amide, acrylonitrile, cellulose acetate, phenol, carbamate, vinylidene chloride, methylene chloride, methacrylonitrile and other monomers, and polar group-containing monomers containing the above-mentioned polar groups.

[0150] Specific examples of the (meth)acrylate copolymer having the first polymer part and the second polymer part include the MMA-BA-MMA copolymer.

[0151] In the MMA-BA-MMA copolymer, the ratio of the MMA block to the BA block can be appropriately set. If the ratio of the BA block increases, the toughness or softness is improved. On the other hand, if the ratio of the MMA block increases, the heat resistance is improved. Based on the viewpoints of toughness and heat resistance, the ratio of the MMA block to the BA block is preferably 1: 1 to 50: 1 in terms of the number of monomer units.

[0152] The content of the acrylic resin is preferably 4 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the epoxy resin. If the content of the acrylic resin is within the above range, the above-mentioned sea island structure can be manifested. Thus, excellent bonding strength can be maintained after curing.

[0153] (4) Curing agent

[0154] The adhesive composition is cured by reacting the epoxy resin, acrylic resin, and curing agent by heating, etc. The adhesive sheet of the present embodiment contains a curing agent to promote the curing reaction.

[0155] The curing agent is not particularly limited as long as it is a curing agent generally used for epoxy resin adhesives, and examples thereof include amine curing agents, acid anhydride curing agents, phenol curing agents, and isocyanate curing agents.

[0156] Examples of amine curing agents include aliphatic polyamines, aromatic polyamines, polyamide amines, dicyandiamide (DICY), and organic acid dihydrazides. Examples of aliphatic polyamines include diethylenetriamine (DETA), triethylenetetramine (TETA), and meta-xylylenediamine (MXDA). Examples of aromatic polyamines include diaminodiphenylmethane (DDM), meta-phenylenediamine (MPDA), and diaminodiphenylsulfone (DDS).

[0157] Examples of the acid anhydride curing agent include alicyclic acid anhydrides (liquid acid anhydrides) and aromatic acid anhydrides. Examples of the alicyclic acid anhydrides include hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA). Examples of the aromatic acid anhydrides include trimellitic anhydride (TMA), pyromellitic dianhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA).

[0158] As a phenolic curing agent, a phenol resin is mentioned, for example.

[0159] As an isocyanate type curing agent, blocked isocyanate is mentioned, for example.

[0160] Among them, amine-based curing agents are preferred, and dicyandiamide-based curing agents are more preferred.

[0161] In addition, a curing agent and a curing accelerator may be used in combination. It should be noted that the curing accelerator also includes a curing catalyst. Examples of the curing accelerator include tertiary amine compounds, amine adducts, imidazole compounds, and urea compounds.

[0162] The content of curing agent can be appropriately set according to the amine value and acid value of curing agent. When using dicyandiamide as curing agent, the content of curing agent is, for example, relative to 100 parts by mass of epoxy resin and epoxy-modified silicone resin, preferably 5 parts by mass or more and 30 parts by mass or less. If the content of curing agent is within the above range, the heat resistance after curing can be improved, and the bonding strength after curing can be suppressed from deteriorating due to temperature changes. In addition, the storage stability (applicable life) of the adhesive sheet can be maintained.

[0163] (5) Inorganic fillers

[0164] As described above, the adhesive sheet of the present embodiment preferably contains an inorganic filler.

[0165] The inorganic filler is not particularly limited as long as it is an inorganic filler commonly used in adhesive compositions, and examples thereof include silica, aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, aluminum nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum borate, potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, barium zirconate, calcium zirconate, glass, talc, clay, mica, and carbon.

[0166] The shape of the inorganic filler is not particularly limited, and examples thereof include spherical, needle-like, fibrous, and plate-like shapes.

[0167] Among them, the inorganic filler is preferably silica, and more preferably spherical silica, which can improve dispersibility.

[0168] The silica particles may be surface treated.

[0169] The average particle size of the inorganic filler is not particularly limited as long as it is equal to or smaller than the thickness of the adhesive sheet.

[0170] It should be noted that the average particle size of the inorganic filler is the particle size when the cumulative value reaches 50% in the particle size distribution obtained by the laser diffraction scattering method. In addition, when measuring the average particle size of the inorganic filler, the adhesive sheet is dissolved in a solvent and the inorganic filler is separated. As a solvent, as long as it is a solvent that can dissolve the components other than the inorganic filler contained in the adhesive sheet, it is not particularly limited and can be appropriately selected according to the type of each component contained in the adhesive sheet. For example, the solvent used in the adhesive composition used for the formation of the adhesive sheet can be used. Specifically, methyl ethyl ketone, ethyl acetate, toluene can be cited.

[0171] The content of the inorganic filler in the adhesive sheet can be appropriately set according to the application of the adhesive sheet.

[0172] (6) Other ingredients

[0173] The adhesive sheet of the present embodiment may also contain additives as needed. By means of additives, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, sliding properties, demoulding properties, flame retardancy, mildew resistance, electrical properties, and strength may be improved or modified. As additives, for example, lubricants, plasticizers, antistatic agents, antiblocking agents, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, colorants, organic fillers, and rubber particles may be cited. In addition, the adhesive sheet of the present embodiment may also contain coupling agents such as silane, titanium, and aluminum as needed. By means of coupling agents, the adhesion between the adhesive sheet and the first component and the second component may be improved.

[0174] (7) Material Optimization

[0175] A preferred embodiment of the material of the adhesive sheet is the same as that of the adhesive sheet of the second embodiment described below.

[0176] 3. Other aspects of adhesive sheets

[0177] The adhesive sheet of the present embodiment usually has only an adhesive layer containing the above-mentioned material. The thickness of the adhesive sheet (adhesive layer) can be appropriately set according to the purpose of the adhesive sheet. The thickness of the adhesive sheet is, for example, 10 μm or more and 100 μm or less, 15 μm or more and 80 μm or less, or 20 μm or more and 60 μm or less.

[0178] Here, the thickness of the adhesive sheet is a value measured from a cross section of the adhesive sheet in the thickness direction observed by a transmission electron microscope (TEM), a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM), and is taken as the average value of thicknesses at 10 randomly selected locations.

[0179] In addition, in the present embodiment, a peeling member may also be provided on one or both sides of the adhesive sheet. As the peeling member, for example, a peeling film and a peeling paper may be cited. The peeling film is sometimes also referred to as a release film, a separator, a release film, etc. In addition, the peeling paper is sometimes also referred to as a release paper, a separator, etc. In addition, the peeling member may be a single layer with peeling properties, or a release layer may be provided on one or both sides of the substrate layer. As the substrate layer, for example, wood-based paper, coated paper, impregnated paper, and resin film may be cited. As the material of the release layer, as long as it is a material with release properties, there is no particular limitation, for example, silicone resin, organic resin-modified silicone resin, fluororesin, aminoalkyd resin, melamine resin, acrylic resin, and polyester resin may be cited. These resins may be used in any of emulsion type, solvent type, or solvent-free type. Among them, based on the consideration of stable peeling properties and processability, silicone resins with polydimethylsiloxane as the main component are preferred.

[0180] When the peeling members are arranged on both surfaces of the pressure-sensitive adhesive sheet, the two peeling members may be the same or different from each other.

[0181] In addition, when a peeling member is disposed on one side or both sides of the PSA sheet, the above-mentioned physical properties of the PSA sheet refer to the physical properties of the PSA sheet alone after the peeling member is removed.

[0182] As a method for producing the adhesive sheet, for example, there is a method of applying an adhesive composition containing the above-mentioned materials on one surface of a release member and drying the composition.

[0183] The adhesive composition may contain a solvent as necessary.

[0184] The coating method of the adhesive composition is not particularly limited, and examples thereof include roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, notch wheel coating, rod coating, knife coating, rod coating, wire bar coating, die coating, lip coating, and dip coating.

[0185] 4. Purpose

[0186] The adhesive sheet of this embodiment is used for bonding a first member and a second member. In this case, the tensile elastic modulus of the main material of the first member is smaller than the tensile elastic modulus of the main material of the second member.

[0187] Examples of combinations of the first and second components include combinations of resin components, combinations of resin components and metal components, combinations of resin components and ceramic components, combinations of resin components and glass components, combinations of ceramic components and metal components, and combinations of metal components.

[0188] The adhesive sheet of this embodiment is used, for example, for bonding a strain sensor to an object to be measured, or bonding a strain sensor to a strain generating body. In this case, the first member is a substrate constituting the strain sensor, and the second member is the object to be measured or the strain generating body. As a substrate constituting the strain sensor, for example, a polyimide resin film can be cited. In addition, as a material of the strain generating body, for example, aluminum alloy, stainless steel, and nickel-chromium-molybdenum steel can be cited. It should be noted that the strain sensor is also called a strain gauge.

[0189] For example, when the base material constituting the strain sensor is a polyimide-based resin film, the tensile modulus of the adhesive sheet after curing only needs to be equal to or greater than the tensile modulus of the polyimide-based resin.

[0190] In addition, the adhesive sheet of the present embodiment is used, for example, for bonding electronic components in a substrate with built-in components to a substrate. In this case, the first component can be an electronic component and the second component can be a substrate, or the first component can be a substrate and the second component can be an electronic component. In addition, in this case, the cured adhesive layer of the cured product containing the adhesive sheet becomes an interlayer insulating layer. As electronic components, for example, active components such as semiconductors can be used, and passive components such as resistors, inductors, and capacitors can be used. As substrates, there are no special restrictions, and examples include: metal base substrates, metal core substrates, copper foil laminates, epoxy glass substrates, metal substrates such as metal foils or metal plates, and resin substrates. As metals constituting the above-mentioned substrates, for example, copper, aluminum, iron, stainless steel (SUS), etc. can be used.

[0191] For example, when the substrate constituting the substrate with built-in components is an epoxy glass substrate, the tensile elastic modulus of the adhesive sheet after curing only needs to be greater than the tensile elastic modulus of the epoxy glass. In addition, when the substrate constituting the substrate with built-in components is a polyimide resin substrate, the tensile elastic modulus of the adhesive sheet after curing only needs to be greater than the tensile elastic modulus of the polyimide resin. In addition, when the substrate constituting the substrate with built-in components is a polyester resin substrate, the tensile elastic modulus of the adhesive sheet after curing only needs to be greater than the tensile elastic modulus of the polyester resin.

[0192] II. Second Embodiment of Adhesive Sheet

[0193] The second embodiment of the adhesive sheet in the present invention is an adhesive sheet used for bonding a first component and a second component, wherein the tensile elastic modulus of the main material of the first component is smaller than the tensile elastic modulus of the main material of the second component, the main material of the first component is a polyimide resin, the adhesive sheet contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler, the epoxy resin includes a bisphenol A type epoxy resin, and a trifunctional or higher epoxy resin, and the content of the inorganic filler is greater than 30.0% by mass and less than 68.0% by mass.

[0194] Figure 1 2 is a schematic cross-sectional view illustrating an adhesive sheet according to this embodiment. Figure 1 As shown in the example, the adhesive sheet 1 of this embodiment usually has only an adhesive layer. The adhesive sheet 1 has a predetermined composition.

[0195] In this embodiment, in the adhesive sheet used for bonding the first member and the second member, the tensile elastic modulus of the main material of the first member is smaller than the tensile elastic modulus of the main material of the second member, and when the main material of the first member is a polyimide resin, the rigidity of the adhesive sheet after curing can be improved by making the content of the inorganic filler within a specified range. Therefore, in a structure having a cured adhesive layer including a cured product of the adhesive sheet between the first member and the second member, when the cured adhesive layer is strained due to external force or temperature change, the strain of the cured adhesive layer can be reduced. As a result, the positional displacement of the first member relative to the second member caused by the strain of the cured adhesive layer can be suppressed.

[0196] In the present embodiment, in the above case, by making the content of the inorganic filler within a predetermined range and containing a trifunctional or higher-functional epoxy resin, the adhesive strength of the adhesive sheet after curing can be improved.

[0197] In addition, in the present embodiment, by containing a bisphenol A type epoxy resin having a rigid skeleton and a trifunctional or higher epoxy resin, the heat resistance after curing can be improved.

[0198] In addition, in this embodiment, by containing an acrylic resin, film forming properties can be improved. Furthermore, elongation can also be increased. Therefore, processability becomes good, and therefore, for example, when the adhesive sheet is cut, the generation of cracks or breaks can be suppressed.

[0199] Hereinafter, each structure of the adhesive sheet of this embodiment will be described.

[0200] 1. Adhesive sheet material

[0201] The adhesive sheet of the present embodiment contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler. The epoxy resin includes a bisphenol A type epoxy resin and a trifunctional or higher epoxy resin, and the content of the inorganic filler is within a predetermined range.

[0202] (1) Epoxy resin

[0203] In the present embodiment, the epoxy resin includes a bisphenol A type epoxy resin and a trifunctional or higher functional epoxy resin.

[0204] In addition, the epoxy resin preferably further contains a phenol novolac type epoxy resin.

[0205] The bisphenol A type epoxy resin, trifunctional or higher epoxy resin, and phenol novolac type epoxy resin are the same as the bisphenol A type epoxy resin, trifunctional or higher epoxy resin, and phenol novolac type epoxy resin in the first embodiment.

[0206] (2) Epoxy modified silicone resin

[0207] The adhesive sheet of this embodiment may contain epoxy-modified silicone resin. By containing epoxy-modified silicone resin, water resistance can be improved. In addition, heat resistance and flexibility (toughness) can be achieved at the same time.

[0208] The epoxy-modified silicone resin is the same as the epoxy-modified silicone resin in the above-mentioned first embodiment.

[0209] (3) Acrylic resin

[0210] The acrylic resin is the same as the acrylic resin in the above-mentioned first embodiment.

[0211] (4) Curing agent

[0212] The curing agent is the same as the curing agent in the above-mentioned first embodiment.

[0213] (5) Inorganic fillers

[0214] The inorganic filler is the same as the inorganic filler in the above-mentioned first embodiment.

[0215] The content of the inorganic filler in the adhesive sheet is more than 30.0 mass %, preferably more than 40 mass %, more preferably more than 50 mass %. By making the content of the inorganic filler be the above-mentioned range, the tensile modulus of elasticity after curing can be improved. In addition, the content of the inorganic filler in the adhesive sheet is below 68.0 mass %, preferably below 65 mass %, more preferably below 60 mass %. By making the content of the inorganic filler be the above-mentioned range, the bonding strength after curing can be improved. In addition, if the content of the inorganic filler is many, rigidity is improved, but flexibility is reduced. If the content of the inorganic filler is made to be the above-mentioned range, flexibility can be suppressed to become too low. Thus, the occurrence of rupture can be suppressed, and operability becomes good.

[0216] Here, the content of the inorganic filler in the adhesive sheet is measured by thermogravimetric-differential thermal simultaneous determination (TG-DTA). Specifically, a thermogravimetric-differential thermal simultaneous determination device (TG-DTA) is used, and the temperature is raised from room temperature to 600°C at a heating rate of 10°C / min under a nitrogen atmosphere, and then maintained at 600°C for 3 hours. In addition, the value expressed as a percentage of the weight of the sample (adhesive sheet) after heating relative to the weight before heating is used as the content of the inorganic filler. As a thermogravimetric-differential thermal simultaneous determination device, for example, Thermo plus TG8120 manufactured by Rigaku Corporation is used.

[0217] (6) Other ingredients

[0218] The other components are the same as those in the above-mentioned first embodiment.

[0219] 2. Physical properties and other aspects of adhesive sheets

[0220] The adhesive sheet of the present embodiment preferably has the physical properties of the adhesive sheet of the first embodiment described above.

[0221] In the adhesive sheet of this embodiment, when a T-shaped peel test is performed using a polyimide resin film as an adherend after curing, peeling is preferably caused by material failure of the polyimide resin film. Thus, the adhesion between the first component containing the polyimide resin as a main material and the cured adhesive sheet can be improved.

[0222] In the above case, the peel strength of the adhesive sheet of the present embodiment after curing is preferably 20 N / 25 mm or more, more preferably 25 N / 25 mm or more, and further preferably 30 N / 25 mm or more. If the peel strength after curing is within the above range, the adhesion between the first member containing the polyimide resin as the main material and the adhesive sheet after curing can be improved.

[0223] Here, the T-peel test is performed in accordance with JIS K6854-3: 1999. As the bonded material, a polyimide resin film ("GF500H" manufactured by Toray DuPont) with a thickness of 0.75 mm and a size of 210 mm×297 mm is used. In addition, as a tensile testing machine, for example, "RTF1150H" manufactured by A&D is used. The specific measurement conditions are shown below.

[0224] (Measurement conditions)

[0225] Test piece: length 170 mm, width 25 mm

[0226] ·Stretching speed: 10 mm / min

[0227] Temperature: 23℃

[0228] Humidity: 50%RH

[0229] Examples of methods for controlling the peel strength of the adhesive sheet after curing include a method of adding an acrylic resin to the adhesive sheet and a method of adding rubber particles to the adhesive sheet. The acrylic resin and rubber particles can increase the peel strength of the adhesive sheet after curing.

[0230] The other aspects of the adhesive sheet of this embodiment are the same as those of the adhesive sheet of the first embodiment described above.

[0231] 3. Purpose

[0232] The adhesive sheet of this embodiment is used for bonding a first member and a second member. In this case, the tensile elastic modulus of the main material of the first member is smaller than that of the main material of the second member, and the main material of the first member is a polyimide resin.

[0233] Examples of the combination of the first member and the second member include a combination of resin members, a combination of a resin member and a metal member, a combination of a resin member and a ceramic member, and a combination of a resin member and a glass member.

[0234] The adhesive sheet of this embodiment is used, for example, for bonding a strain sensor to an object to be measured, or bonding a strain sensor to a strain-generating body. In this case, the first member is a substrate constituting the strain sensor, and the second member is the object to be measured or the strain-generating body. The strain sensor is the same as the strain sensor described in the first embodiment above.

[0235] In addition, the adhesive sheet of this embodiment is used, for example, for bonding an electronic component to a substrate in which components are built in. In this case, the first component is the substrate, and the second component is the electronic component. In this case, the cured adhesive layer containing the cured product of the adhesive sheet becomes an interlayer insulating layer. The substrate in which components are built in is the same as the content of the substrate in which components are built in described in the item of the first embodiment above.

[0236] III. Third Embodiment of Adhesive Sheet

[0237] In a third embodiment of the adhesive sheet of the present invention, the tensile elastic modulus of the adhesive sheet after curing is 3.5 GPa or more, and the tensile shear adhesive strength of the adhesive sheet after curing is 10 MPa or more.

[0238] Figure 1 2 is a schematic cross-sectional view illustrating an adhesive sheet according to this embodiment. Figure 1 As shown in the example, the adhesive sheet 1 of this embodiment usually has only an adhesive layer. The adhesive sheet 1 has predetermined physical properties.

[0239] In the present embodiment, the tensile modulus of elasticity after curing of the adhesive sheet is 3.5 GPa or more. It can be said that the tensile modulus of elasticity after curing of the adhesive sheet is relatively large compared with the tensile modulus of elasticity of a common resin. Therefore, when the first member is a resin member and the adhesive sheet is used for bonding the first member and the second member, by making the tensile modulus of elasticity after curing of the adhesive sheet be above a specified value, the rigidity of the adhesive sheet after curing can be relatively improved. Therefore, in a structure in which the first member is a resin member and a cured adhesive layer of a cured product containing the adhesive sheet is provided between the first member and the second member, the strain of the cured adhesive layer due to external force and temperature change can be reduced. Thus, the positional offset of the first member relative to the second member caused by the strain of the cured adhesive layer can be suppressed.

[0240] Here, as a method of improving the rigidity of the adhesive sheet after curing, for example, a method of adding an inorganic filler is considered. However, the addition of an inorganic filler tends to reduce the adhesive strength after curing.

[0241] In contrast, in the present embodiment, the tensile shear bonding strength of the adhesive sheet after curing is equal to or greater than a predetermined value, so that the rigidity of the adhesive sheet after curing can be increased, and the bonding strength after curing can be increased.

[0242] Hereinafter, each structure of the adhesive sheet of this embodiment will be described.

[0243] 1. Physical properties of adhesive sheet

[0244] (1) Tensile elastic modulus after curing

[0245] The tensile modulus of elasticity after curing of the adhesive sheet of the present embodiment is more than 3.5 GPa, preferably more than 4.0 GPa, and more preferably more than 5.0 GPa. In addition, the upper limit of the tensile modulus of elasticity after curing of the adhesive sheet of the present embodiment is not particularly limited, for example, less than 30 GPa, less than 20 GPa, and less than 10 GPa. Specifically, the tensile modulus of elasticity after curing of the adhesive sheet of the present embodiment is preferably more than 3.5 GPa and less than 30 GPa, more preferably more than 4.0 GPa and less than 20 GPa, and further preferably more than 5.0 GPa and less than 10 GPa.

[0246] The adhesive sheet of the present embodiment preferably has the same tensile modulus of elasticity after curing as the adhesive sheet of the first embodiment described above.

[0247] (2) Tensile shear bond strength after curing

[0248] The tensile shear adhesive strength after curing of the adhesive sheet of the present embodiment is the same as the tensile shear adhesive strength after curing of the adhesive sheet of the first embodiment described above.

[0249] (3) Elongation at break

[0250] The adhesive sheet of the present embodiment preferably has the same elongation at break as the adhesive sheet of the first embodiment described above.

[0251] (4) Peak value of loss coefficient (tanδ) after curing

[0252] The adhesive sheet of the present embodiment preferably has the same peak value of the loss coefficient (tan δ) after curing as the adhesive sheet of the first embodiment described above.

[0253] 2. Adhesive sheet material

[0254] The material of the adhesive sheet of this embodiment is the same as that of the adhesive sheet of the first embodiment described above.

[0255] 3. Other aspects of adhesive sheets

[0256] The other aspects of the adhesive sheet of this embodiment are the same as those of the adhesive sheet of the first embodiment described above.

[0257] 4. Purpose

[0258] The adhesive sheet of this embodiment is used for bonding the first component to the second component. In this case, the first component is a resin component. The tensile elastic modulus of the main material of the first component is preferably smaller than the tensile elastic modulus of the main material of the second component. Among them, the main material of the first component is preferably a polyimide resin or a polyester resin, and more preferably a polyimide resin.

[0259] Examples of the combination of the first member and the second member include a combination of resin members, a combination of a resin member and a metal member, a combination of a resin member and a ceramic member, and a combination of a resin member and a glass member.

[0260] The adhesive sheet of this embodiment is used, for example, for bonding a strain sensor to an object to be measured, or bonding a strain sensor to a strain-generating body. In this case, the first member is a substrate constituting the strain sensor, and the second member is the object to be measured or the strain-generating body. The strain sensor is the same as the strain sensor described in the first embodiment above.

[0261] In addition, the adhesive sheet of this embodiment is used, for example, for bonding an electronic component to a substrate in which components are built in. In this case, the first component is the substrate, and the second component is the electronic component. In this case, the cured adhesive layer containing the cured product of the adhesive sheet becomes an interlayer insulating layer. The substrate in which components are built in is the same as the content of the substrate in which components are built in described in the item of the first embodiment above.

[0262] IV. Fourth Embodiment of Adhesive Sheet

[0263] In the fourth embodiment of the adhesive sheet of the present invention, the elongation of the adhesive sheet at break is 60% or more, and the adhesive sheet contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler, the epoxy resin includes a bisphenol A type epoxy resin and a trifunctional or higher epoxy resin, and the content of the inorganic filler is 30.0% by mass or more and 68.0% by mass or less.

[0264] Figure 1 2 is a schematic cross-sectional view illustrating an adhesive sheet according to this embodiment. Figure 1 As shown in the example, the adhesive sheet 1 of this embodiment usually has only an adhesive layer. The adhesive sheet 1 has predetermined physical properties and a predetermined composition.

[0265] As described in the following embodiments, the inventors of the present invention have found that when the content of the inorganic filler is within a specified range, the rigidity of the adhesive sheet after curing is relatively higher than the rigidity of the usual resin. Therefore, when the first component is a resin component and the adhesive sheet is used for bonding the first component and the second component, the rigidity of the adhesive sheet after curing can be relatively improved by making the content of the inorganic filler within a specified range. Therefore, in a structure in which the first component is a resin component and there is a cured adhesive layer containing a cured product of the adhesive sheet between the first component and the second component, the strain of the cured adhesive layer caused by external force and temperature change can be reduced. Thus, the positional displacement of the first component relative to the second component caused by the strain of the cured adhesive layer can be suppressed.

[0266] In addition, in the present embodiment, by making the content of the inorganic filler within a predetermined range and containing a trifunctional or higher-functional epoxy resin, the adhesive strength of the adhesive sheet after curing can be improved.

[0267] In addition, in the present embodiment, by containing a bisphenol A type epoxy resin having a rigid skeleton and a trifunctional or higher epoxy resin, the heat resistance after curing can be improved.

[0268] In addition, in the present embodiment, by containing an acrylic resin, film forming properties can be improved. Furthermore, in the present embodiment, by containing an acrylic resin, elongation can also be improved. In addition, in the present embodiment, the elongation at the time of fracture of the adhesive sheet is above a specified value. Therefore, the processability becomes good, so that, for example, when the adhesive sheet is cut, the generation of cracks or fractures can be suppressed.

[0269] Hereinafter, each structure of the adhesive sheet of this embodiment will be described.

[0270] 1. Adhesive sheet material

[0271] The material of the adhesive sheet of this embodiment is the same as that of the adhesive sheet of the second embodiment described above.

[0272] 2. Physical properties of adhesive sheet

[0273] (1) Elongation at break

[0274] The elongation at break of the adhesive sheet of the present embodiment is the same as the elongation at break of the adhesive sheet of the first embodiment described above.

[0275] (2) Tensile elastic modulus after curing

[0276] The tensile modulus of elasticity after curing of the adhesive sheet of the present embodiment preferably has the same tensile modulus of elasticity after curing as the adhesive sheet of the first embodiment described above.

[0277] (3) Tensile shear bond strength after curing

[0278] The tensile shear adhesive strength after curing of the adhesive sheet of the present embodiment preferably has the tensile shear adhesive strength after curing of the adhesive sheet of the first embodiment described above.

[0279] (4) Peak value of loss coefficient (tanδ) after curing

[0280] The adhesive sheet of the present embodiment preferably has the same peak value of the loss coefficient (tan δ) after curing as the adhesive sheet of the first embodiment described above.

[0281] 3. Other aspects of adhesive sheets

[0282] The other aspects of the adhesive sheet of this embodiment are the same as those of the adhesive sheet of the first embodiment described above.

[0283] 4. Purpose

[0284] The use of the adhesive sheet of this embodiment is the same as the use of the adhesive sheet of the third embodiment described above.

[0285] B. Adhesive Composition

[0286] The adhesive composition in the present invention is used for bonding a first component and a second component, the tensile elastic modulus of the first component is smaller than the tensile elastic modulus of the second component, the main material of the first component is a polyimide resin, the adhesive composition contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler, the epoxy resin includes a bisphenol A type epoxy resin, and a trifunctional or higher epoxy resin, and the content of the inorganic filler in the solid component of the adhesive composition is greater than 30.0 mass % and less than 68.0 mass %.

[0287] The adhesive composition in the present invention exerts the same effects as those of the adhesive sheet according to the second embodiment described above.

[0288] The components contained in the adhesive composition of the present invention are the same as the components contained in the adhesive sheet of the second embodiment described above.

[0289] The adhesive composition may contain a solvent as necessary.

[0290] Adhesive composition can be prepared by mixing each component, and mixing and dispersing as required. Mixing method or dispersion method are not particularly limited, and common mixing and dispersing machine can be applied, such as double-roll mill, three-roll mill, pebble mill, ball mill, Szegvari grinding mill, high-speed impeller disperser, high-speed stone mill, high-speed impact mill, disperser (disper), high-speed mixer, ribbon blender, co-kneader, high-speed mixing machine (intensive mixer), drum blender, stirrer, disperser (disperser), homogenizer, ultrasonic disperser etc. When using multiple epoxy resins, preferably hard epoxy resin is mixed and stirred first, then curing agent is mixed and stirred, after being diluted by solvent, soft epoxy resin is mixed and stirred, then acrylic resin is mixed and stirred.

[0291] The use of the adhesive composition in the present invention is the same as the use of the adhesive sheet according to the second embodiment described above.

[0292] C. Structure

[0293] The structure in the present invention comprises a first component, a second component, and a cured adhesive layer bonding the first component and the second component together, wherein the first component is a resin component, the tensile elastic modulus of the cured adhesive layer is greater than 3.5 GPa, and the tensile shear bonding strength of the cured adhesive layer is greater than 10 MPa.

[0294] Figure 2 2 is a schematic cross-sectional view illustrating a structure in the present invention. Figure 2 As shown, the structure 10 includes a first member 11, a second member 12, and a cured adhesive layer 13 for bonding the first member 11 and the second member 12. The first member 11 is a resin member. The cured adhesive layer 13 has predetermined physical properties.

[0295] In the present invention, the tensile elastic modulus of the cured adhesive layer is 3.5 GPa or more. It can be said that the tensile elastic modulus of the cured adhesive layer is relatively large compared to the tensile elastic modulus of a common resin. Therefore, when the first component is a resin component, by making the tensile elastic modulus of the cured adhesive layer be above a specified value, the rigidity of the cured adhesive layer can be relatively improved. Therefore, when the first component is a resin component, the strain of the cured adhesive layer caused by external force and temperature change can be reduced. Thus, the positional offset of the first component relative to the second component caused by the strain of the cured adhesive layer can be suppressed.

[0296] Here, as a method of improving the rigidity of the cured adhesive layer, for example, a method of adding an inorganic filler can be considered. However, the addition of an inorganic filler tends to reduce the adhesive strength.

[0297] In contrast, in the present invention, the tensile shear bonding strength of the cured adhesive layer is equal to or greater than a predetermined value. Therefore, the cured adhesive layer can be improved and the bonding strength can be increased.

[0298] Hereinafter, each configuration of the structure in the present invention will be described.

[0299] 1. Curing the adhesive layer

[0300] In the present invention, the first member and the second member are bonded together by curing the adhesive layer.

[0301] (1) Physical properties of the cured adhesive layer

[0302] (a) Tensile elastic modulus

[0303] The tensile elastic modulus of the cured adhesive layer in the present invention is the same as the tensile elastic modulus of the adhesive sheet after curing according to the third embodiment described above.

[0304] When measuring the tensile elastic modulus of the cured adhesive layer, prepare the cured adhesive layer before curing. For example, in the case of a known cured adhesive layer before curing, use the cured adhesive layer before curing. In addition, in the case of an adhesive composition or its composition used by a known cured adhesive layer, use the adhesive composition, or prepare the adhesive composition of the composition to form the cured adhesive layer before curing. At this time, the thickness of the cured adhesive layer before curing is used as the thickness of the cured adhesive layer.

[0305] (b) Tensile shear bond strength

[0306] The tensile shear adhesive strength of the cured adhesive layer in the present invention is the same as the tensile shear adhesive strength of the adhesive sheet of the third embodiment after curing.

[0307] When measuring the tensile shear adhesive strength of the cured adhesive layer, a cured adhesive layer before curing is prepared. The cured adhesive layer before curing is as described above.

[0308] (2) Materials for curing adhesive layer

[0309] The cured adhesive layer in the present invention preferably contains a cured product of the adhesive sheet or a cured product of the adhesive composition.

[0310] (3) Other aspects of curing the adhesive layer

[0311] The thickness of the cured adhesive layer in the present invention is the same as the thickness of the adhesive sheet of the above-mentioned first embodiment.

[0312] 2. First component and second component

[0313] In the present invention, the first member is a resin member. The tensile elastic modulus of the main material of the first member is preferably smaller than the tensile elastic modulus of the main material of the second member. The main material of the first member is preferably a polyimide resin or a polyester resin, and more preferably a polyimide resin.

[0314] Examples of the combination of the first member and the second member include a combination of resin members, a combination of a resin member and a metal member, a combination of a resin member and a ceramic member, and a combination of a resin member and a glass member.

[0315] The structure in the present invention is, for example, a strain sensor. Specifically, the strain sensor and the object to be measured are bonded by a cured adhesive layer, or the strain sensor and the strain generating body are bonded by a cured adhesive layer. In this case, the first member is a substrate constituting the strain sensor, and the second member is the object to be measured or the strain generating body. The strain sensor is the same as the strain sensor described in the above-mentioned adhesive sheet.

[0316] In addition, the structure in the present invention is, for example, a substrate with built-in components. In this case, the first component is a substrate, and the second component is an electronic component. In this case, the cured adhesive layer becomes an interlayer insulating layer. The substrate with built-in components is the same as the content of the substrate with built-in components described in the item of the first embodiment.

[0317] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are examples, and those having substantially the same configuration and exerting the same effects as the technical concept described in the claims of the present invention are all included in the technical scope of the present invention.

[0318] [Example]

[0319] [Material]

[0320] The following materials were used.

[0321] Bisphenol A epoxy resin 1: liquid at room temperature, epoxy equivalent 184 g / eq~194 g / eq, weight average molecular weight 370

[0322] Bisphenol A epoxy resin 2: solid at room temperature, epoxy equivalent 450 g / eq~500 g / eq, number average molecular weight 900, softening point 64℃

[0323] ·Multifunctional epoxy resin 1: High viscosity liquid, epoxy equivalent 110 g / eq~130 g / eq, 4-functional, diaminodiphenylmethane type epoxy resin

[0324] ·Multifunctional epoxy resin 2: solid at room temperature, epoxy equivalent 200 g / eq to 220 g / eq, softening point 70°C, trifunctional or more, special novolac type epoxy resin

[0325] Rubber particle masterbatch: A masterbatch obtained by dispersing core-shell rubber particles in bisphenol A epoxy resin. The shell part is polymethacrylate and the core part is butadiene rubber. The amount of core-shell particles is 33% by mass.

[0326] ·Naphthalene epoxy resin: Epoxy equivalent 170 g / eq, softening point 95°C, melt viscosity at 150°C 9.0 Pa·s

[0327] · Phenol novolac type epoxy resin: epoxy equivalent 160 g / eq, softening point 65°C, trifunctional or above

[0328] · Epoxy modified silicone resin: (epoxy equivalent 160 g / eq, viscosity (25°C) 0.15 Pa·s to 0.3 Pa·s, non-volatile matter 43.0% to 43.7%)

[0329] Acrylic resin: PMMA-PBuA-PMMA (having an acrylamide group in one part), Tg: -20°C, 120°C, weight average molecular weight 150,000

[0330] Curing agent 1: dicyandiamide, particle size: less than 10 μm, melting point: 209°C (manufactured by Evonik, DYHARD100SH)

[0331] Curing agent 2: Novolac type phenolic resin, hydroxyl equivalent 104 g / eq, softening point 78°C to 82°C (manufactured by DIC Corporation, TD-2131)

[0332] Curing catalyst 1: Aliphatic dimethyl urea (manufactured by San-Apro, U-CAT 35131N)

[0333] Curing catalyst 2: Epoxy resin amine adduct (AmicureMY-H manufactured by Ajinomoto Fine-Techno Co., Ltd.)

[0334] Inorganic filler 1: Silica particles, average particle size 0.5 μm

[0335] Inorganic filler 2: Potassium titanate fiber, fiber diameter 0.3 μm to 0.6 μm, fiber length 10 μm to 20 μm

[0336] Inorganic filler 3: ground carbon fiber, fiber diameter 5 μm to 15 μm, fiber length 30 μm to 150 μm

[0337] Coupling agent: 3-glycidyloxypropyltrimethoxysilane

[0338] ·Antioxidant: Hindered phenol antioxidant

[0339] Solvents: methanol, methyl ethyl ketone, toluene

[0340] [Examples 1 to 5 and Comparative Examples 1 to 6]

[0341] First, an adhesive composition was prepared with the composition shown in Table 1 below. Then, the adhesive composition was applied to the release-treated surface of a release film ("SP-PET-O3-BU" manufactured by Mitsui Chemicals Tohcello, thickness 38 μm) in such a manner that the thickness after drying became 50 μm to form an adhesive sheet. Then, the release-treated surface of the release film ("SP-PET-O3-BU" manufactured by Mitsui Chemicals Tohcello, thickness 38 μm) was laminated to the surface of the adhesive sheet on the opposite side to the release film. Thus, an adhesive sheet having release films on both sides was obtained.

[0342] [evaluate]

[0343] (1) Physical properties before curing

[0344] (1-1) Processability

[0345] The adhesive sheet was cut using a cutter ("215B" manufactured by OLFA). The presence or absence of cracks in the cut portion was then visually checked. The workability was evaluated based on the following criteria.

[0346] A: No cracks.

[0347] B: Cracks appeared, but the cracked parts did not separate.

[0348] C: Cracks appeared and the cracked parts separated.

[0349] (1-2) Elongation at break

[0350] Using "Tensilon RTF1150" manufactured by A&D Corporation as a tensile testing machine, the elongation at break of the adhesive sheet was measured under the following conditions in accordance with JIS K7127:1999.

[0351] (Measurement conditions)

[0352] ·Test piece: short strip with a width of 15 mm and a length of 150 mm

[0353] Distance between chucks: 100 mm

[0354] ·Stretching speed: 100 mm / min

[0355] Temperature: 23℃

[0356] Humidity: 50%RH

[0357] (2) Physical properties after curing

[0358] (2-1) Tensile elastic modulus

[0359] First, the adhesive sheet was heated at 120° C. for 2 hours to be cured. Then, the tensile modulus of the adhesive sheet after curing was measured under the following conditions in accordance with JIS K7127:1999 using “Tensilon RTF1150” manufactured by A&D as a tensile tester.

[0360] (Measurement conditions)

[0361] ·Test piece: short strip with a width of 15 mm and a length of 150 mm

[0362] Distance between chucks: 100 mm

[0363] ·Stretching speed: 1 mm / min

[0364] Temperature: 23℃

[0365] Humidity: 50%RH

[0366] (2-2) Tensile shear bond strength

[0367] The tensile shear bonding strength of the adhesive sheet after curing was measured using the "Tensilon RTF1350" manufactured by A&D as a tensile testing machine in accordance with JIS K6850:1999 under the following conditions. As the bonded material, a cold-rolled steel sheet (SPCC-SD) with a thickness of 16 mm, a size of 100 mm × 25 mm, standard tempering treatment, and a matte surface treatment was used. In addition, the curing conditions of the adhesive sheet were set to 120°C, 2 hours, and 0.1 MPa.

[0368] (Measurement conditions)

[0369] Test piece: length 187.5 mm, width 25 mm

[0370] ·Stretching speed: 10 mm / min

[0371] Temperature: 23℃

[0372] Humidity: 50%RH

[0373] (2-3) Peel Adhesion Strength

[0374] The "Tensilon RTF1150" manufactured by A&D was used as a tensile testing machine. According to JIS K6854-3:1999, the peeling strength (T-shaped peeling) of the adhesive sheet after curing was measured under the following conditions. As the bonded material, a polyimide resin film ("GF500H" manufactured by Toray DuPont) with a thickness of 0.75 mm and a size of 210 mm × 297 mm was used. In addition, the curing conditions of the adhesive sheet were set to 120°C, 2 hours, and 0.1 MPa. In addition, regarding peeling, interface damage, material damage, and cohesive damage were visually confirmed.

[0375] (Measurement conditions)

[0376] Test piece: length 170 mm, width 25 mm

[0377] ·Stretching speed: 10 mm / min

[0378] Temperature: 23℃

[0379] Humidity: 50%RH

[0380] (2-4) Peak value of tanδ

[0381] First, the adhesive sheet was heated at 120°C for 2 hours to cure. Then, the tan δ of the adhesive sheet after curing was measured under the following conditions using the "RSA-III" manufactured by TA Instruments as a dynamic viscoelasticity measuring device by dynamic viscoelasticity measurement (DMA) in accordance with JIS K7244-1:1998. It should be noted that when there are multiple tan δ peaks, the one with the highest temperature is taken as the tan δ peak.

[0382] (Measurement conditions)

[0383] Accessory mode: Compact mode

[0384] Frequency: 1 Hz

[0385] Temperature: -50℃~300℃

[0386] Heating rate: 5℃ / min

[0387] (3) Sensor position deviation

[0388] A release film is peeled off from the adhesive sheet. Then, using a laminating machine ("GL835PRO" manufactured by ACCO BRANDS JAPAN), the surface of the adhesive sheet opposite to the other release film is bonded to the roughened surface of the copper foil ("RCF-T5B-35μ", thickness 35 μm, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.). Then, cut into 3 cm×5 cm. Then, peel off the other release film from the adhesive sheet. Then, a strain sensor ("QFLGB-02-11" manufactured by Tokyo Measuring Instruments Research Institute Co., Ltd.) is placed on the adhesive sheet. Then, the adhesive sheet is heated at 120°C for 2 hours to cure it. Using an image measuring instrument ("NEXIV VMR-H3030" manufactured by Nikon), the origin is determined at an arbitrary point, and the position of the strain sensor from the origin is measured. Then, the position offset of the strain sensor after being kept at 0°C for 1 hour and then kept at 100°C for 1 hour is calculated. The position offset of the sensor is evaluated according to the following criteria.

[0389] None: No position offset.

[0390] Yes: Position offset occurs.

[0391] [Table 1]

[0392]

[0393] In Examples 1 to 5, when the main material of the first component is a polyimide resin, the adhesive sheet has a prescribed physical property or a prescribed composition, so the processability is good and the sensor has no positional displacement. On the other hand, in Comparative Example 1, since it does not contain an acrylic resin, film formation cannot be performed and the physical properties cannot be measured. In addition, in Comparative Examples 2 to 4, since the content of the inorganic filler is small, the tensile elastic modulus after curing is reduced, and the sensor is positionally displaced. In addition, in Comparative Example 5, since it does not contain a trifunctional or higher epoxy resin, the tensile shear bonding strength after curing and the peel bonding strength after curing are low. In addition, in Comparative Example 6, since the content of the inorganic filler is high, the processability is poor, the elongation at break is low, and the tensile shear bonding strength after curing and the peel bonding strength after curing are also low.

[0394] The present invention provides the following inventions.

[0395] [1] An adhesive sheet having a tensile elastic modulus of 3.5 GPa or more after curing,

[0396] The adhesive sheet has a tensile shear adhesive strength of 10 MPa or more after curing.

[0397] [2] The adhesive sheet according to [1], wherein the elongation of the adhesive sheet at break is 60% or more.

[0398] [3] The adhesive sheet according to [1] or [2], comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler,

[0399] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0400] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0401] [4] The adhesive sheet according to any one of [1] to [3], which is used for bonding an electronic component to a substrate in which components are built.

[0402] [5] An adhesive sheet having an elongation at break of 60% or more,

[0403] It contains epoxy resin, acrylic resin, curing agent, and inorganic filler.

[0404] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0405] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0406] [6] An adhesive sheet for bonding a first member to a second member,

[0407] The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member.

[0408] The elongation of the adhesive sheet at break is 60% or more.

[0409] The tensile modulus of the adhesive sheet after curing is equal to or greater than the tensile modulus of the first member.

[0410] The adhesive sheet has a tensile shear adhesive strength of 10 MPa or more after curing.

[0411] [7] The adhesive sheet according to [6], wherein the main material of the first member is a polyimide resin,

[0412] The adhesive sheet has a tensile elastic modulus of 3.5 GPa or more after curing.

[0413] [8] The adhesive sheet according to [6] or [7], comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler,

[0414] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0415] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0416] [9] The adhesive sheet according to any one of [6] to [8], which is used for bonding an electronic component to a substrate in which components are built.

[0417] One of the first member and the second member is the electronic component, and the other is the substrate.

[0418]

[10] An adhesive sheet for bonding a first member to a second member.

[0419] The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member.

[0420] The main material of the first component is polyimide resin.

[0421] The adhesive sheet contains epoxy resin, acrylic resin, curing agent, and inorganic filler.

[0422] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0423] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0424]

[11] The adhesive sheet according to

[10] , wherein the epoxy resin further includes a phenol novolac-type epoxy resin.

[0425]

[12] An adhesive composition for bonding a first member to a second member,

[0426] The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member.

[0427] The main material of the first component is polyimide resin.

[0428] The adhesive composition contains epoxy resin, acrylic resin, curing agent, and inorganic filler.

[0429] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0430] The content of the inorganic filler in the solid content of the adhesive composition is 30.0 mass % or more and 68.0 mass % or less.

[0431]

[13] The adhesive composition according to

[12] , wherein the epoxy resin further comprises a phenol novolac-type epoxy resin.

[0432]

[14] A structure comprising a first member, a second member, and a cured adhesive layer for bonding the first member and the second member together,

[0433] The first component is a resin component.

[0434] The tensile elastic modulus of the cured adhesive layer is 3.5 GPa or more.

[0435] The cured adhesive layer has a tensile shear adhesive strength of 10 MPa or more.

[0436]

[15] The structure according to

[14] , wherein the cured adhesive layer contains a cured product of an adhesive composition comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler,

[0437] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0438] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0439]

[16] The structure as described in

[14] or

[15] , wherein the structure is a substrate with built-in components, the first component is the substrate, and the second component is an electronic component.

[0440]

[17] The structure according to any one of

[14] to

[16] , wherein the tensile modulus of elasticity of the first member is smaller than the tensile modulus of elasticity of the second member,

[0441] The tensile elastic modulus of the cured adhesive layer is equal to or greater than the tensile elastic modulus of the first member.

[0442]

[18] The structure described in any one of

[14] to

[17] , wherein a main material of the first member is a polyimide-based resin.

[0443] The present invention provides the following inventions.

[0444] [2-1] An adhesive sheet for bonding a first member to a second member,

[0445] The tensile elastic modulus of the main material of the first member is smaller than the tensile elastic modulus of the main material of the second member,

[0446] The elongation of the adhesive sheet at break is 60% or more.

[0447] The tensile modulus of elasticity of the adhesive sheet after curing is equal to or greater than the tensile modulus of elasticity of the main material of the first member.

[0448] The adhesive sheet has a tensile shear adhesive strength of 10 MPa or more after curing.

[0449] [2-2] The adhesive sheet according to [2-1], wherein the main material of the first member is a polyimide resin,

[0450] The adhesive sheet has a tensile elastic modulus of 3.5 GPa or more after curing.

[0451] [2-3] The adhesive sheet as described in [2-1] or [2-2], which contains an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler,

[0452] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0453] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0454] [2-4] An adhesive sheet for bonding a first member to a second member,

[0455] The tensile elastic modulus of the main material of the first member is smaller than the tensile elastic modulus of the main material of the second member,

[0456] The main material of the first component is polyimide resin.

[0457] The adhesive sheet contains epoxy resin, acrylic resin, curing agent, and inorganic filler.

[0458] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0459] The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

[0460] [2-5] The adhesive sheet according to [2-3] or [2-4], wherein the epoxy resin further includes a phenol novolac-type epoxy resin.

[0461] [2-6] An adhesive composition for bonding a first member to a second member,

[0462] The tensile elastic modulus of the main material of the first member is smaller than the tensile elastic modulus of the main material of the second member,

[0463] The main material of the first component is polyimide resin.

[0464] The adhesive composition contains epoxy resin, acrylic resin, curing agent, and inorganic filler.

[0465] The epoxy resin includes bisphenol A type epoxy resin and trifunctional or higher epoxy resin.

[0466] The content of the inorganic filler in the solid content of the adhesive composition is 30.0 mass % or more and 68.0 mass % or less.

[0467] [2-7] The adhesive composition according to [2-6], wherein the epoxy resin further includes a phenol novolac-type epoxy resin.

[0468] Description of Reference Numerals

[0469] 1: Adhesive sheet;

[0470] 10: structure;

[0471] 11: first component;

[0472] 12: second component;

[0473] 13: Curing the adhesive layer.

Claims

1. An adhesive sheet having a tensile elastic modulus of 3.5 GPa or more after curing, The adhesive sheet has a tensile shear bonding strength of 10 MPa or more after curing.

2. The adhesive sheet according to claim 1, wherein The adhesive sheet has an elongation of 60% or more at break.

3. The adhesive sheet according to claim 1 or 2, comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler. The epoxy resin includes bisphenol A epoxy resin and trifunctional or higher epoxy resin. The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less. 4 . The adhesive sheet according to claim 1 , which is used for bonding an electronic component to a substrate in which components are built.

5. An adhesive sheet having an elongation at break of 60% or more, The adhesive sheet contains epoxy resin, acrylic resin, curing agent, and inorganic filler. The epoxy resin includes bisphenol A epoxy resin and trifunctional or higher epoxy resin. The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

6. An adhesive sheet for bonding a first component to a second component. The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member, The elongation of the adhesive sheet at break is 60% or more, The tensile modulus of elasticity of the adhesive sheet after curing is equal to or greater than the tensile modulus of elasticity of the first member. The adhesive sheet has a tensile shear bonding strength of 10 MPa or more after curing.

7. The adhesive sheet according to claim 6, wherein The main material of the first component is polyimide resin. The adhesive sheet has a tensile elastic modulus of 3.5 GPa or more after curing.

8. The adhesive sheet according to claim 6 or 7, comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler. The epoxy resin includes bisphenol A epoxy resin and trifunctional or higher epoxy resin. The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

9. The adhesive sheet according to any one of claims 6 to 8, which is used for bonding an electronic component to a substrate in which components are built. One of the first member and the second member is the electronic component, and the other is the substrate.

10. An adhesive sheet for bonding a first component to a second component. The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member, The main material of the first component is polyimide resin. The adhesive sheet contains epoxy resin, acrylic resin, curing agent, and inorganic filler. The epoxy resin includes bisphenol A epoxy resin and trifunctional or higher epoxy resin. The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

11. The adhesive sheet according to claim 10, wherein The epoxy resin also includes a phenol novolac type epoxy resin.

12. An adhesive composition for bonding a first component to a second component. The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member, The main material of the first component is polyimide resin. The adhesive composition contains epoxy resin, acrylic resin, curing agent, and inorganic filler. The epoxy resin includes bisphenol A epoxy resin and trifunctional or higher epoxy resin. The content of the inorganic filler in the solid content of the adhesive composition is 30.0 mass % or more and 68.0 mass % or less.

13. The adhesive composition according to claim 12, wherein The epoxy resin also includes a phenol novolac type epoxy resin.

14. A structure comprising a first member, a second member, and a cured adhesive layer bonding the first member and the second member together, The first member is a resin member, The tensile elastic modulus of the cured adhesive layer is greater than 3.5 GPa, The tensile shear bonding strength of the cured adhesive layer is greater than 10 MPa.

15. The structure according to claim 14, wherein: The cured adhesive layer contains a cured product of an adhesive composition comprising an epoxy resin, an acrylic resin, a curing agent, and an inorganic filler. The epoxy resin includes bisphenol A epoxy resin and trifunctional or higher epoxy resin. The content of the inorganic filler is 30.0 mass % or more and 68.0 mass % or less.

16. The structure according to claim 14 or 15, wherein: The structure is a substrate with built-in components, the first member is a substrate, and the second member is an electronic component.

17. A structure according to any one of claims 14 to 16, wherein The tensile elastic modulus of the first member is smaller than the tensile elastic modulus of the second member, The tensile elastic modulus of the cured adhesive layer is equal to or greater than the tensile elastic modulus of the first member.

18. A structure according to any one of claims 14 to 17, wherein The main material of the first member is polyimide resin.

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