Adhesive composition, adhesive sheet, and bonded body

Abstract

The purpose of the present invention is to provide: an adhesive composition that is capable of adhering at room temperature, makes it possible to reduce adhesive strength by the application of voltage, and is capable of suppressing bending of an adherend when bonded to the adherend; and an adhesive sheet comprising an adhesive layer formed from the adhesive composition. The present invention relates to an adhesive composition containing a polymer, wherein the tensile storage elastic modulus E' at 25°C of an adhesive layer formed from the adhesive composition is 0.5 MPa or more, and the adhesive force reduction rate represented by the formula indicated below is 60% or more.　Formula: Adhesive strength reduction rate (%) = 100 - (adhesive strength after application of voltage / initial adhesive strength) × 100

Description

Adhesive composition, adhesive sheet, and bonding body

[0001] The present invention relates to an adhesive composition, an adhesive sheet containing an adhesive layer formed from the adhesive composition, and a bonding body between the adhesive sheet and an adherend.

[0002] In electronic component manufacturing processes, there is a growing demand for rework to improve yield and for recycling, which involves disassembling and recovering components after use. To meet these demands, double-sided adhesive sheets that possess both a certain level of adhesive strength and a certain level of release properties are sometimes used to join materials together in electronic component manufacturing processes.

[0003] As a double-sided adhesive sheet that achieves the above-mentioned adhesive strength and peelability, an adhesive sheet (electro-peelable adhesive sheet) is known that uses an ionic liquid consisting of cations and anions as a component forming the adhesive composition, and peels off by applying a voltage to the adhesive layer (Patent Documents 1 to 3). In the electro-peelable adhesive sheets of Patent Documents 1 to 3, it is thought that when a voltage is applied, the cations of the ionic liquid move on the cathode side, causing reduction, and the anions of the ionic liquid move on the anode side, causing oxidation, which weakens the adhesive strength at the adhesive interface and makes it easier to peel off.

[0004] Japanese Patent No. 2010-037354 Japanese Patent No. 6097112 Japanese Patent No. 4139851

[0005] Incidentally, recent electronic devices are increasingly larger, thinner, and have narrower bezels. To address this trend, a new need is emerging for adhesive sheets that can be processed and cut to extremely narrow widths (for example, in millimeters). Conventional adhesive sheets do not always have sufficient mechanical properties for use in such extremely narrow widths, raising concerns about a decrease in the structural strength and durability of electronic devices. In particular, there were concerns about the risk of bending or damage to electronic devices when physical pressure is applied.

[0006] The present invention has been completed in view of the above, and aims to provide an adhesive composition that can be bonded at room temperature, whose adhesive strength can be reduced by applying a voltage, and which can suppress bending of the adherend when bonded to the adherend, and an adhesive sheet comprising an adhesive layer formed from the adhesive composition.

[0007] As a result of repeated studies by the inventors, the above problem can be solved by an adhesive composition having a tensile storage modulus E' of 0.5 MPa or higher at 25°C and an adhesive strength reduction rate of 60% or less, as expressed by the following formula: Adhesive strength reduction rate (%) = 100 - (Adhesive strength after voltage application / Initial adhesive strength) × 100

[0008] The means for solving the above problems are as follows: [1] An adhesive composition containing a polymer, wherein the tensile storage modulus E' of the adhesive layer formed from the adhesive composition at 25°C is 0.5 MPa or more, and the adhesive strength reduction rate expressed by the following formula is 60% or more: Adhesive strength reduction rate (%) = 100 - (Adhesive strength after voltage application / Initial adhesive strength) × 100 (Initial adhesive strength) One side of the adhesive layer or adhesive sheet is attached to the metal layer surface of a metal layered film (thickness 25 μm), and the other side is attached to a stainless steel plate (SUS316L), pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 25°C and 50% RH. A 180° peel is performed at a tensile speed of 300 mm / min to peel the adhesive layer from the stainless steel plate. The initial adhesive strength shall be calculated according to Method 1 for Measuring Peel Adhesion, as described in JIS Z 0237:2009. (Adhesion after voltage application) The negative and positive electrodes of a DC current machine are attached to the stainless steel plate and the metal layer of the metal-layered film, respectively. A voltage of 30V is applied for 30 seconds, and immediately after, peeling is performed in the same manner as the initial adhesive strength measurement described above, and the adhesive layer or adhesive sheet is peeled off from the stainless steel plate. The adhesion strength after voltage application shall be calculated according to Method 1 for Measuring Peel Adhesion, as described in JIS Z 0237:2009.

[0009] [2] The adhesive composition according to [1], wherein the glass transition temperature (Tg) of the adhesive layer formed from the adhesive composition is -10°C or higher and less than 40°C. [3] The adhesive composition according to [1], wherein the polymer comprises a polyester polymer. [4] The adhesive composition according to [1], wherein the glass transition temperature (Tg) of the polymer that is present in an amount of 50% by mass or more relative to the total polymer is -12°C or higher and less than 10°C.

[0010] [5] The adhesive composition according to [1], comprising an ionic substance. [6] The adhesive composition according to [5], wherein the content of the ionic substance per 100 parts by mass of the polymer is 0.5 parts by mass or more and 30 parts by mass or less. [7] The adhesive composition according to [1], wherein the initial adhesive strength is 3.0 N / cm or more. [8] The adhesive composition according to [1], wherein the adhesive strength after voltage application is 1.0 N / cm or less.

[0011] [9] The adhesive composition according to [1], further comprising a filler.

[10] The adhesive composition according to [9], wherein the surface of the filler is composed of an organic material.

[11] The adhesive composition according to

[10] , wherein the surface of the filler is covered with urethane or silicone resin.

[12] The adhesive composition according to

[10] , wherein the filler is a hollow filler.

[13] The adhesive composition according to [9], wherein the content of the filler per 100 parts by mass of the polymer is 0.1 to 45 parts by mass.

[0012]

[14] The adhesive composition according to [1], wherein the polymer comprises a first polymer and a second polymer having different Tg values.

[15] The adhesive composition according to

[14] , wherein the second polymer is a polyester polymer.

[0013]

[16] An adhesive sheet comprising an adhesive layer formed from an adhesive composition according to any one of [1] to

[15] .

[17] An adhesive sheet comprising, in this order, an electrically conductive substrate having at least one conductive surface and an adhesive layer, wherein the conductive surface of the electrically conductive substrate and the adhesive layer are in contact, and the adhesive layer is formed from an adhesive composition according to any one of [1] to

[15] .

[18] The adhesive sheet according to

[17] , further comprising another adhesive layer, wherein the other adhesive layer is formed on the surface of the electrically conductive substrate opposite to the adhesive layer.

[19] The adhesive sheet according to

[17] , further comprising another adhesive layer, a second conductive substrate, and a second other adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer, the second conductive substrate and the second other adhesive layer are formed in this order on the surface of the adhesive layer opposite to the conductive substrate, and the conductive surface of the second conductive substrate is in contact with the adhesive layer.

[0014]

[20] A joint comprising the adhesive sheet described in

[17] and a conductive material, wherein the adhesive layer is attached to the conductive material.

[21] A joint comprising the adhesive sheet described in

[19] and an adherend material, wherein the other adhesive layer is attached to the adherend material.

[0015] The adhesive composition of the present invention is adhesive at room temperature, its adhesive strength can be reduced by applying a voltage, and it can also suppress bending of the adherend when bonded to it.

[0016] Figure 1 is a cross-sectional view showing an example of the adhesive sheet of the present invention. Figure 2 is a cross-sectional view showing an example of the laminated structure of the adhesive sheet of the present invention. Figure 3 is a cross-sectional view showing another example of the laminated structure of the adhesive sheet of the present invention. Figure 4 is a cross-sectional view showing an overview of the method for the 180° peel test in the embodiment. Figure 5 is an equivalent circuit diagram of a bonded sample for capacitance and ionic conductivity measurement.

[0017] The embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below.

[0018] [Adhesive Composition] The adhesive composition of this embodiment is an adhesive composition containing a polymer, wherein the tensile storage modulus E' of the adhesive layer formed from the adhesive composition at 25°C is 0.5 MPa or more, and the adhesive strength reduction rate expressed by the following formula is 60% or more. Adhesive strength reduction rate (%) = 100 - (Adhesive strength after voltage application / Initial adhesive strength) × 100 (Initial adhesive strength) One side of the adhesive layer or adhesive sheet is bonded to the metal layer surface of a metal layered film (thickness 25 μm), and the other side is bonded to a stainless steel plate (SUS316L), pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 25°C and 50% RH. A 180° peel is performed at a tensile speed of 300 mm / min to peel the adhesive layer from the stainless steel plate. The initial adhesive strength is the value calculated in accordance with the peel adhesive strength measurement method 1 described in JIS Z 0237:2009. (Adhesion after voltage application) The negative and positive electrodes of a DC current machine are attached to the stainless steel plate and the metal layer of the metal-layered film, respectively. A voltage of 30V is applied for 30 seconds, and immediately afterward, peeling is performed in the same manner as the initial adhesion measurement described above, and the adhesive layer or adhesive sheet is peeled off from the stainless steel plate. The adhesion after voltage application is calculated according to the peel-off adhesion measurement method 1 described in JIS Z 0237:2009.

[0019] In the above method, if the adhesive sheet of this embodiment is a double-sided adhesive sheet or a single-sided adhesive sheet that does not include a base layer, the initial adhesive strength is measured using the adhesive layer. On the other hand, if the adhesive sheet of this embodiment is a double-sided adhesive sheet that has a base layer, the initial adhesive strength is measured using the adhesive sheet. Furthermore, in the above method, using a value calculated in accordance with Method 1 for Measuring Peel Adhesion of the Test Plate described in JIS Z 0237:2009 means, more specifically, that after the start of measurement, the measurement value for the first 25 mm length is ignored, and the adhesive strength measurement values ​​for the 50 mm length peeled off the test plate are averaged and used as the value of peel adhesion.

[0020] In this embodiment, the tensile storage modulus E' of the adhesive composition at 25°C is preferably 0.5 MPa or higher, more preferably 0.8 MPa or higher, even more preferably 1.0 MPa or higher, and particularly preferably 2.0 MPa or higher. There is no particular upper limit to the tensile storage modulus E' at 25°C, but for example, it can be 6.5 MPa or lower, 5.0 MPa or lower, or 3.5 MPa or lower.

[0021] The tensile storage modulus E' of an adhesive composition at 25°C tends to increase with the inclusion of a high Tg material and / or an increased crosslinking density of the adhesive composition, and tends to decrease with the inclusion of a low Tg material and / or an decreased crosslinking density of the adhesive composition. Methods for adjusting the crosslinking density of an adhesive composition include, for example, adjusting the amount of functional groups that can act as crosslinking sites in the polymer of the adhesive composition, adjusting the functional group density, adjusting the molecular weight, and adjusting the amount of the crosslinking agent, as well as selecting the type of crosslinking agent, adjusting the amount of functional groups, adjusting the functional group density, adjusting the molecular weight, and adjusting the amount of the crosslinking agent.

[0022] In this specification, the tensile storage modulus at 25°C is sometimes referred to as the "25°C tensile storage modulus." Also, in this specification, the initial adhesive strength is sometimes referred to as the "adhesive strength when no voltage is applied." Furthermore, the property of adhesive strength decreasing when voltage is applied is called "electrorelease," and a large decrease in adhesive strength due to voltage application is sometimes referred to as "excellent electrorelease properties."

[0023] The glass transition temperature (Tg) of the adhesive layer formed from the adhesive composition of this embodiment is preferably -10°C or higher and less than 40°C. More preferably, the Tg of the adhesive layer is -5°C or higher, even more preferably -3°C or higher, and particularly preferably 0°C or higher. Furthermore, it is more preferably 20°C or lower, even more preferably 18°C ​​or lower, and particularly preferably 15°C or lower. A Tg of -10°C or higher makes it easy to increase the tensile storage modulus of the adhesive layer at 25°C. Also, a Tg of less than 40°C is advantageous from the viewpoint of adhesive flexibility and can increase the adhesion force to the adherend.

[0024] The glass transition temperature (Tg) of the adhesive layer can be measured, for example, using a solid viscoelasticity measuring device. To determine the Tg of the adhesive layer, the adhesive layer formed from the adhesive composition is cut into strips measuring 10 mm wide x 40 mm long. Next, dynamic viscoelasticity measurement is performed using a solid viscoelasticity measuring device. The temperature at which the loss tangent (tanδ) peak is observed from the dynamic viscoelasticity measurement results can be identified as the Tg of the adhesive layer. If multiple tanδ peaks are observed, the largest peak value (maximum peak value) is taken as the Tg of the adhesive layer. The conditions for dynamic viscoelasticity measurement are as follows: Measurement conditions: Frequency: 1 Hz, Deformation mode: Tensile, Chuck distance: 20 mm, Measurement temperature: -50 to 100°C, Heating rate: 10°C / min

[0025] The glass transition temperature (Tg) of the adhesive layer formed from the adhesive composition tends to increase with the selection of high-Tg material species and / or the amount of high-Tg material included in the adhesive composition, and tends to decrease with the selection of low-Tg material species and / or the amount of low-Tg material included.

[0026] <Components of the Adhesive Composition> (Polymer) The adhesive composition of this embodiment contains a polymer. In this embodiment, the polymer is not particularly limited as long as it is a general organic polymer compound, for example, a monomer polymer or partial polymer. The monomer may be a single monomer or a mixture of two or more monomers. A partial polymer means a polymer in which at least a part of the monomer or monomer mixture is partially polymerized.

[0027] The polymer in this embodiment is not particularly limited as long as it is commonly used as an adhesive and has adhesive properties, but examples include polyester polymers, acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyamide polymers, urethane polymers, fluoropolymers, and epoxy polymers. The polymers can be used alone or in combination of two or more. The total content of polyester polymers and acrylic polymers having carboxyl groups, alkoxy groups, hydroxyl groups and / or amide bonds in the polymer of this embodiment is preferably 60% by mass or more, and more preferably 80% by mass or more. In particular, in order to increase cost, productivity and initial adhesive strength, the polymer in this embodiment is preferably at least one selected from the group consisting of polyester polymers and acrylic polymers, and polyester polymers are more preferred. That is, the polymer contained in the adhesive composition of this embodiment preferably includes at least one selected from the group consisting of polyester polymers and acrylic polymers, and more preferably includes polyester polymers.

[0028] Polyester polymers are typically included in adhesive compositions as base polymers. Here, the base polymer refers to the main component of the rubbery polymer (a polymer that exhibits rubber elasticity in the temperature range around room temperature) included in the adhesive composition. In this specification, unless otherwise specified, "main component" refers to a component present in an amount exceeding 50% by mass. In this specification, a polyester polymer refers to a polymer obtained by polycondensation of a dicarboxylic acid and a diol.

[0029] (Dicarboxylic Acids) Any of the following dicarboxylic acids can be used in the synthesis of the above polyester polymers: aliphatic dicarboxylic acids, dimer acids, alicyclic dicarboxylic acids, unsaturated dicarboxylic acids, and aromatic dicarboxylic acids. Specific examples of dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, dimethylglutaric acid, adipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaic acid, dodecanedioic acid, sebacic acid, thiodipropionic acid, and diglycolic acid; dimer acids obtained by dimerizing fatty acids such as oleic acid and erucic acid; 1,2-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 4-methyl-1,2 Examples include alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, norbornanedicarboxylic acid, and adamantanedicarboxylic acid; unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, and dodecenyl succinic anhydride; aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, orthophthalic acid, benzylmalonic acid, 2,2'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-dicarboxydiphenyl ether, and naphthalenedicarboxylic acid; and derivatives thereof. The derivatives of the above dicarboxylic acids include derivatives of carboxylates, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters. By appropriately selecting and using one or more of these dicarboxylic acids, a polyester polymer can be obtained that can form an adhesive composition having desired properties (specifically, desired tensile storage modulus and adhesive strength reduction rate at 25°C).

[0030] In this embodiment, dimer acid can be used as the dicarboxylic acid. A polyester polymer synthesized using dimer acid, i.e., a polyester polymer containing a structure derived from dimer acid, makes it easy to form an adhesive layer that can achieve both practical adhesive properties and high modulus of elasticity. The reason for this is not particularly limited to this interpretation, but it is thought that the relatively long side chains introduced by the copolymerization of dimer acid contribute to improving the flexibility of the adhesive layer. Dimer acid can be used alone or in combination of two or more types. In the embodiment in which dimer acid is used as the dicarboxylic acid, the proportion of dimer acid in the total amount (total number of moles) of dicarboxylic acid as a monomer component of the polyester polymer may be 1 mol% or more, for example, 5 mol% or more, 10 mol% or more, or 15 mol% or more. Furthermore, the upper limit of the proportion of dimer acid is 100 mol%, but from the viewpoint of practicality such as achieving both adhesive properties and high modulus of elasticity, in this embodiment it may be 50 mol% or less, or 30 mol% or less. This embodiment can be carried out in any form in which the dicarboxylic acid used as a monomer component in the synthesis of the polyester polymer contains dimer acid, or in any form in which it does not contain dimer acid. For example, the proportion of dimer acid may be 10 mol% or less, 3 mol% or less, or less than 1 mol%, and the dicarboxylic acid used in the synthesis of the polyester polymer may not substantially contain dimer acid.

[0031] In this embodiment, sebacic acid can be used as the dicarboxylic acid. In the embodiment in which sebacic acid is used as the dicarboxylic acid, the proportion of sebacic acid in the total amount (total number of moles) of dicarboxylic acid as a monomer component of the polyester polymer may be 1 mol% or more, for example, 5 mol% or more, 10 mol% or more, or 15 mol% or more. Furthermore, the upper limit of the proportion of sebacic acid is 100 mol%, and from the viewpoint of practicality such as achieving both adhesive properties and high modulus of elasticity, in this embodiment it is preferably 50 mol% or less, more preferably 30 mol% or less, and even more preferably 25 mol% or less.

[0032] Furthermore, in this embodiment, aromatic dicarboxylic acids may be used as the dicarboxylic acids used in the synthesis of the polyester polymer. Using dicarboxylic acids containing aromatic dicarboxylic acids tends to increase cohesive strength and raise the tensile storage modulus at 25°C. Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, and orthophthalic acid, with isophthalic acid and terephthalic acid being preferred. Aromatic dicarboxylic acids can be used individually or in combination of two or more. From the viewpoint of improving cohesive strength and tensile storage modulus at 25°C, the polyester polymer contained in the adhesive layer according to the embodiment of the present invention preferably contains at least one selected from the group consisting of isophthalic acid, terephthalic acid, and orthophthalic acid as a structural unit, and more preferably contains at least one selected from the group consisting of isophthalic acid and terephthalic acid as a structural unit.

[0033] In embodiments where an aromatic dicarboxylic acid is used as the dicarboxylic acid, the proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of dicarboxylic acid in the monomer component of the polyester polymer may be 1 mol% or more, and may be 3 mol% or more, 5 mol% or more, or 7 mol% or more from the viewpoint of improving cohesive strength, etc. Furthermore, the upper limit of the proportion of aromatic carboxylic acid is appropriately set to, for example, 90 mol% or less in this embodiment, and from the viewpoint of obtaining adhesive properties such as adhesive strength with a high 25°C tensile storage modulus, it is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 72 mol% or less. On the other hand, the lower limit of the proportion of aromatic carboxylic acid is preferably 45 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, and particularly preferably 70 mol% or more. In this embodiment, the dicarboxylic acid used as a monomer component in the synthesis of the polyester polymer can be carried out in a manner that includes an aromatic dicarboxylic acid.

[0034] The molecular weight of the dicarboxylic acid used as a monomer component in the synthesis of polyester polymers is not particularly limited, but is preferably 100 or more, and may be 150 or more. In this embodiment, the molecular weight of the dicarboxylic acid used may be 200 or more, 250 or more, 350 or more, 450 or more, or 500 or more (for example, 530 or more). On the other hand, from the viewpoint of monomer availability and synthesizability, in this embodiment, the molecular weight of the dicarboxylic acid is preferably 1000 or less, and may be, for example, 800 or less, 700 or less, or 600 or less (for example, 550 or less).

[0035] In this specification, the molecular weight of a dicarboxylic acid is the molecular weight calculated from its chemical formula. In embodiments using two or more dicarboxylic acids, the molecular weight of the dicarboxylic acid is the sum of the products of the molecular weight and mass fraction of each dicarboxylic acid.

[0036] (Diol) In this embodiment, any of the following can be used as the diol for the synthesis of the polyester polymer: (poly)alkylene glycols, aliphatic diols, dimer diols, alicyclic diols, aromatic diols, and unsaturated diols. Specific examples of the above diols include, for example, (poly)alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, etc.; 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-hexanediol, 2,2,4-trimethyl-1, Examples include aliphatic diols such as 6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; dimergols (such as dimergols derived from fatty acids like oleic acid and erucic acid); alicyclic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; aromatic diols such as 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-,m- and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and their ethylene oxide and propylene oxide adducts; and so on. By appropriately selecting and using one or more of these diols, a polyester polymer capable of forming an adhesive layer with desired properties (specifically, desired 25°C tensile storage modulus and adhesive strength reduction rate) can be obtained.

[0037] In this embodiment, (poly)alkylene glycols, aliphatic diols, and alicyclic diols are preferred as diols, with (poly)alkylene glycols and aliphatic diols being more preferred. By synthesizing these diols (preferably ethylene glycol and aliphatic diols) in combination with the above-mentioned dicarboxylic acids (preferably aromatic dicarboxylic acids), polyester polymers having a high 25°C tensile storage modulus and excellent tackiness can be preferably obtained. Preferred examples include (poly)ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol, with ethylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol being more preferred from the viewpoint of reactivity, etc. These can be used individually or in combination of two or more. In this specification, the term (poly)ethylene glycol is used to encompass ethylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol.

[0038] The proportion of (poly)alkylene glycols, aliphatic diols, and alicyclic diols (preferably the proportion of ethylene glycol and aliphatic diols) in the total amount (total number of moles) of diols in the monomer components of the polyester polymer is not particularly limited, but in this embodiment it is appropriate to set it to 50 mol% or more, and from the viewpoint of obtaining good adhesive properties it is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more (for example, 99 to 100 mol%). In other embodiments, the proportion of (poly)alkylene glycols, aliphatic diols, and alicyclic diols (preferably the proportion of ethylene glycol and aliphatic diols) may be, for example, 95 mol% or less.

[0039] In other embodiments, (poly)ethylene glycol can be used as the diol. (Poly)ethylene glycol can be used alone or in combination of two or more types. In embodiments in which (poly)ethylene glycol is used as the diol, the proportion of (poly)ethylene glycol to the total amount (total number of moles) of diols as monomer components of the polyester polymer may be 1 mol% or more, for example, 10 mol% or more, 50 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more (for example, 95 to 100 mol%). In addition, in this embodiment, the proportion of (poly)ethylene glycol may be 95 mol% or less, 85 mol% or less, or 60 mol% or less. Furthermore, in this embodiment, the diol used as a monomer component in the synthesis of the polyester polymer can be either a form containing (poly)ethylene glycol or a form without (poly)ethylene glycol. Furthermore, in this embodiment, the proportion of (poly)ethylene glycol may be 50 mol% or less (for example, less than 50 mol%), 30 mol% or less, 10 mol% or less, 3 mol% or less, or less than 1 mol%, and the diol used in the synthesis of the polyester polymer may not substantially contain (poly)ethylene glycol.

[0040] In other embodiments, dimer ol can be used as the diol. Dimer ol can be used alone or in combination of two or more types. In embodiments in which dimer ol is used as the diol, the proportion of dimer ol to the total amount (total number of moles) of diol as monomer components of the polyester polymer may be 1 mol% or more, for example, 10 mol% or more, 50 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more (for example, 95 to 100 mol%). In this embodiment, the proportion of dimer ol may be 95 mol% or less, 85 mol% or less, or 60 mol% or less. In this embodiment, the diol used as a monomer component in the synthesis of the polyester polymer can be either a dimer ol-containing embodiment or a dimer ol-free embodiment. Furthermore, in this embodiment, the proportion of the dimerol may be 50 mol% or less (for example, less than 50 mol%), 30 mol% or less, 10 mol% or less, 3 mol% or less, or less than 1 mol%, and the diol used in the synthesis of the polyester polymer may not substantially contain dimerol.

[0041] The molecular weight of the diol described above is not particularly limited. In this embodiment, the molecular weight of the diol is suitable to be, for example, 1000 or less from the viewpoint of monomer availability and synthesizability, and may be, for example, 800 or less, 700 or less, or 600 or less. Also in this embodiment, the molecular weight of the diol is suitable to be 500 or less, and may be 300 or less, 150 or less, 100 or less, or 80 or less. Also, the molecular weight of the diol is suitable to be 50 or more, and may be, for example, greater than 100. A preferred example of a diol having the above molecular weight is neopentyl glycol. In other embodiments, the molecular weight of the diol may be 150 or more, 200 or more, 250 or more, 350 or more, 450 or more, or 500 or more. A preferred example of a diol having such a molecular weight is dimer ol.

[0042] In this specification, the molecular weight of a diol may be the molecular weight calculated from its chemical formula. In embodiments using two or more diols, the molecular weight of the diol may be the sum of the products of the molecular weight and mass fraction of each diol.

[0043] The polyester polymer according to this embodiment may be substantially composed of the dicarboxylic acid and diol described above, but other copolymer components other than dicarboxylic acid and diol may be copolymerized to the extent that the effects of this embodiment are not impaired, for purposes such as introducing desired functional groups or adjusting the molecular weight. Examples of such other copolymer components include polycarboxylic acids containing three or four or more carboxyl groups (trivalent or higher polycarboxylic acids such as trimellitic acid, pyromellitic acid, adamantanetricarboxylic acid, trimesic acid, trimeric acid, etc.), polyols containing three or four or more hydroxyl groups in one molecule (pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantanetriol, etc.), monocarboxylic acids, monoalcohols, hydroxycarboxylic acids, lactones, etc. The above other copolymer components can be used individually or in combination of two or more. In this embodiment, the proportion of the other copolymer components is appropriately less than 10 mol%, for example, less than 3 mol%, less than 1 mol%, or less than 0.1 mol% of the monomer component of the polyester polymer. This embodiment can preferably be carried out in a manner in which the monomer component of the polyester polymer substantially does not contain the other copolymer components.

[0044] In the monomer components used in the synthesis of the polyester polymer of this embodiment, although not particularly limited, the total proportion of dicarboxylic acid and diol is preferably 90 mol% or more, more preferably 95 mol% or more, more preferably 98 mol% or more, and even more preferably 99 mol% or more (for example, 99 to 100 mol%). This embodiment is preferably carried out in a manner that uses a polyester polymer synthesized substantially from dicarboxylic acid and diol.

[0045] In this embodiment, it is preferable that the polyester polymer has a limited content of aromatic rings within its polymer molecule. This is preferable from the viewpoint of improving initial adhesion. In some preferred embodiments, the copolymerization ratio of aromatic ring-containing monomers (typically aromatic dicarboxylic acids, aromatic diols) in the polyester polymer is 80 mol% or less, more preferably 60 mol% or less, even more preferably 40 mol% or less, and may be 30 mol% or less, 10 mol% or less, or even 1 mol% or less (for example, less than 1 mol%), from the viewpoint of obtaining an initial adhesion of a predetermined value or higher. Furthermore, in embodiments in which the polyester polymer has aromatic rings, the copolymerization ratio of aromatic ring-containing monomers is 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, from the viewpoint of obtaining a high modulus of elasticity. This embodiment can be particularly preferably carried out in a manner in which a polyester polymer containing aromatic rings in its molecule is used.

[0046] The method for obtaining the polyester polymer of this embodiment is not particularly limited, and polymerization methods known as synthesis methods for polyester polymers can be appropriately employed. For example, monomer raw materials used in the synthesis of the polyester polymer can be those formulated so that the amount of dicarboxylic acid is 0.95 to 1.05 equivalents (preferably 0.98 to 1.02 equivalents) per equivalent of diol. By formulating dicarboxylic acid and diol in the above proportions, high molecular weight polyester polymers can be easily obtained. Furthermore, by setting the molar ratio of dicarboxylic acid to diol within an appropriate range, a suitable crosslinked structure (for example, crosslinking based on reaction with a crosslinking agent such as an isocyanate-based crosslinking agent) can be obtained and the cohesive force can be adjusted. When using a polycarboxylic acid containing three or four or more carboxyl groups and / or a polyol containing three or four or more hydroxyl groups, the above preferred equivalents can be appropriately adjusted depending on the valency of the polycarboxylic acid and / or polyol used.

[0047] In this embodiment, the molar ratio of dicarboxylic acid and diol used as monomer components in the synthesis of the polyester polymer is not particularly limited, and an appropriate molar ratio can be set considering the desired polymer properties and synthesizability. In this embodiment, the ratio of the number of moles A1 of dicarboxylic acid and the number of moles A2 of diol used as the monomer components (molar ratio A1 / A2) may be 10 / 90 or more, or 30 / 70 or more. In some preferred embodiments, the above molar ratio (A1 / A2) is 50 / 50 or more, more preferably 60 / 40 or more, even more preferably 70 / 30 or more, and may also be 80 / 20 or more, or 90 / 10 or more. For example, by increasing the molar ratio of dicarboxylic acid as described above, properties based on dicarboxylic acid (e.g., isophthalic acid, terephthalic acid, and orthophthalic acid) can be suitably expressed. Also, the above molar ratio (A1 / A2) may be, for example, 95 / 5 or less, or 85 / 15 or less. In this embodiment, from the viewpoint of suitably exhibiting properties based on the diol, the above molar ratio (A1 / A2) may be 75 / 25 or less, or 50 / 50 or less (for example, 30 / 70 or less). When using a polycarboxylic acid containing three or four or more carboxyl groups and / or a polyol containing three or four or more hydroxyl groups, the above molar ratio can be appropriately adjusted depending on the valency of the polycarboxylic acid and / or polyol used.

[0048] In this embodiment, polyester polymers can be obtained by polycondensation of a dicarboxylic acid and a diol, similar to general polyesters. More specifically, polyester polymers can be synthesized by carrying out the reaction between the carboxyl group of the dicarboxylic acid and the hydroxyl group of the diol, while removing the water (product water) typically generated by the above reaction from the reaction system. Methods for removing the product water from the reaction system include blowing an inert gas into the reaction system and removing the product water along with the inert gas, azeotropic dehydration using a reaction water discharge solvent such as toluene or xylene, or distillation of the product water from the reaction system under reduced pressure (reduced pressure method).

[0049] The reaction temperature and reaction time when carrying out the above reactions (including esterification and polycondensation), and the degree of reduced pressure (pressure in the reaction system) when employing a reduced pressure method, can be appropriately set so that a polyester polymer with the desired properties (e.g., molecular weight) can be efficiently obtained. Although not particularly limited, it is generally appropriate to set the reaction temperature to 150°C or higher (e.g., 180°C to 260°C). By setting the reaction temperature within this range, a good reaction rate can be obtained, productivity can be improved, and degradation of the resulting polyester polymer can be easily prevented or suppressed. The reaction time is not particularly limited and may be 3 to 48 hours (e.g., 10 to 30 hours). When employing a reduced pressure method, although not particularly limited, it is generally appropriate to set the degree of reduced pressure to 10 kPa or less (e.g., 10 kPa to 0.1 kPa), for example, 4 kPa to 0.1 kPa. By setting the pressure in the reaction system within this range, the water produced by the reaction can be efficiently distilled out of the system, making it easier to maintain a good reaction rate. Furthermore, when the reaction temperature is relatively high, maintaining the pressure within the reaction system above the lower limit makes it easier to prevent the removal of the starting materials, such as dicarboxylic acids and diols, from the system. From the viewpoint of maintaining stable pressure within the reaction system, it is usually appropriate to set the pressure within the reaction system to 0.1 kPa or higher.

[0050] As with the synthesis of general polyesters, known or conventional catalysts can be used in appropriate amounts for esterification and condensation in the above reaction. Examples of such catalysts include various metal compounds such as titanium, germanium, antimony, tin, and zinc; and strong acids such as p-toluenesulfonic acid and sulfuric acid. The amount of catalyst used can be appropriately determined according to the reaction rate, etc., so a detailed explanation is omitted here.

[0051] In the above process of synthesizing a polyester polymer by reaction of a dicarboxylic acid and a diol, a solvent may or may not be used. The above synthesis can be carried out substantially without the use of organic solvents (for example, excluding the intentional use of organic solvents as reaction solvents in the above reaction). Synthesizing a polyester polymer substantially without the use of organic solvents in this way, and preparing a polyester adhesive layer using such a polyester polymer, is preferable as it meets the requirement to minimize the use of organic solvents in the manufacturing process.

[0052] Furthermore, since there is generally a correlation between the molecular weight of the synthesized polyester polymer and the viscosity of the reaction system during the above reaction, this can be used to control the molecular weight of the polyester polymer. For example, by continuously or intermittently measuring (monitoring) the torque of the stirrer and the viscosity of the reaction system during the reaction, it is possible to accurately synthesize a polyester polymer that meets the target molecular weight.

[0053] The weight-average molecular weight (Mw) of the polyester polymer is not particularly limited, and is usually 10,000 or more, for example, 20,000 or more is appropriate. In embodiments of the present invention, the Mw of the polyester polymer can be 30,000 or more, and is preferably greater than 50,000. From the viewpoint of obtaining better properties, it is preferably greater than 60,000, more preferably greater than 70,000, even more preferably greater than 80,000, particularly preferably greater than 90,000, and may even be 95,000 or more. By using a polyester polymer with an Mw of a predetermined value or higher, an adhesive layer with high cohesive strength is easily obtained. In preferred embodiments, the Mw of the polyester polymer can be 100,000 or more (for example, greater than 100,000), may be 110,000 or more, and may even be 115,000 or more. By using high molecular weight polyester polymers in this way, even adhesive compositions that tend to have low viscosity due to containing a certain amount or more of tackifying resin can easily obtain an appropriate viscosity and form a thin adhesive layer of good quality. Such adhesive compositions do not need to be excessively concentrated, and even compositions containing crosslinking agents tend to have a sufficient pot life and excellent handling properties. The upper limit of Mw for polyester polymers is usually 30 × 10 ４ The following is appropriate, and from the viewpoint of adhesive strength, etc., in this embodiment, preferably 20 × 10 ４ More preferably, 15 × 10 ４ The following is an example: 14 × 10 ４ The following is also acceptable.

[0054] The acrylic polymer preferably contains monomer units derived from alkyl (meth)acrylate esters having C1 to C14 alkyl groups (formula (1) below). Such monomer units are suitable for obtaining high initial adhesion. Furthermore, to increase the dielectric constant of components other than the ionic liquid in the adhesive layer, and to increase the ionic conductivity of the resulting adhesive layer and the capacitance per unit area of ​​the adhesive interface, thereby improving electropeelability, the alkyl group R in formula (1) below is preferable. ｂIt is preferably small in carbon number, particularly preferably 8 or less, and more preferably 4 or less. CH ２ =C(R ａ )COOR ｂ (1) [In formula (1), R ａ is a hydrogen atom or a methyl group, and R ｂ is an alkyl group having 1 to 14 carbon atoms]

[0055] Examples of the alkyl (meth)acrylate having 1 to 14 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, 1,3-dimethylbutyl acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, and n-tetradecyl (meth)acrylate. Among them, n-butyl acrylate, 2-ethylhexyl acrylate, and isononyl acrylate are preferred. The alkyl (meth)acrylate having 1 to 14 carbon atoms can be used alone or in combination of two or more.

[0056] Further, the polymer of the present embodiment may contain an ionic polymer. The ionic polymer is a polymer having an ionic functional group. By including an ionic polymer in the polymer, the relative permittivity of the polymer increases and the electrical peelability is improved. When the polymer contains an ionic polymer, the content of the ionic polymer is preferably 0.05 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the polymer.

[0057] In this embodiment, the polymer can be obtained by (co)polymerizing monomer components. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization (active energy ray polymerization). Solution polymerization is particularly preferred from the viewpoint of cost and productivity. When copolymerized, the polymer may be a random copolymer, block copolymer, alternating copolymer, graft copolymer, etc.

[0058] Solution polymerization methods are not particularly limited, but include methods in which monomer components, polymerization initiators, etc., are dissolved in a solvent, heated to polymerize, and a polymer solution containing the polymer is obtained.

[0059] Various common solvents can be used as solvents in solution polymerization. Examples of such solvents (polymerization solvents) include aromatic hydrocarbons such as toluene, benzene, and xylene; esters such as ethyl acetate and n-butyl acetate; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. Solvents can be used alone or in combination of two or more.

[0060] The amount of solvent used is not particularly limited, but is preferably 10 parts by mass or more and 1000 parts by mass or less relative to the total monomer components constituting the polymer (100 parts by mass). The upper limit of the amount of solvent used is more preferably 500 parts by mass, and the lower limit is more preferably 50 parts by mass.

[0061] Polymerization initiators used in solution polymerization are not particularly limited, but include peroxide-based polymerization initiators and azo-based polymerization initiators. Peroxide-based polymerization initiators are not particularly limited, but include peroxycarbonates, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, and peroxyesters. More specifically, examples include benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane. Azo polymerization initiators are not particularly limited, but include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionic acid)dimethyl, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis(2,4,4-trimethylpentane), and 4,4'-azobi Examples include s-4-cyanovaleric acid, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethylene isobutylamidine)hydrochloride, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate. Polymerization initiators can be used alone or in combination of two or more.

[0062] The amount of polymerization initiator used is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to the total monomer components constituting the polymer (100 parts by mass). The upper limit of the amount of polymerization initiator used is more preferably 3 parts by mass, and the lower limit is more preferably 0.05 parts by mass.

[0063] In solution polymerization, the heating temperature during polymerization is not particularly limited, but is, for example, 50°C to 80°C. The heating time is not particularly limited, but is, for example, 1 hour to 24 hours.

[0064] The weight-average molecular weight of the polymer is not particularly limited, but is preferably between 100,000 and 5,000,000. The upper limit of the weight-average molecular weight is more preferably 4,000,000, even more preferably 3,000,000, and the lower limit is more preferably 200,000, even more preferably 300,000. When the weight-average molecular weight is 100,000 or more, the cohesive force is reduced, which effectively suppresses the problem of adhesive residue remaining on the surface of the adherend after the adhesive layer has been peeled off. Furthermore, when the weight-average molecular weight is 5,000,000 or less, it effectively suppresses the problem of insufficient wettability on the surface of the adherend after the adhesive layer has been peeled off.

[0065] The weight-average molecular weight was obtained by measuring using gel permeation chromatography (GPC). More specifically, for example, using a GPC measuring device such as the "HLC-8220GPC" (manufactured by Tosoh Corporation), the measurement was performed under the following conditions, and the value was calculated based on the standard polystyrene equivalent. (Weight-average molecular weight measurement conditions) ・Sample concentration: 0.2% by mass (tetrahydrofuran solution) ・Sample injection volume: 30 μL ・Sample column: TSKguardcolumn SuperHZ-H (1 tube) + TSKgel SuperHZM-H (2 tubes) ・Reference column: TSKgel SuperH-RC (1 tube) ・Eluent: Tetrahydrofuran (THF) ・Flow rate: 0.2 mL / min ・Detector: Differential refractometer (RI) ・Column temperature (measurement temperature): 40°C ・Standard sample: Polystyrene (PS)

[0066] The glass transition temperature (Tg) of the polymer is not particularly limited, but is preferably -12°C or higher and less than 10°C. A Tg of -8°C or higher is more preferable, -5°C or higher is even more preferable, and -2°C or higher is particularly preferable. Furthermore, a Tg of 8°C or lower is more preferable, 6°C or lower is even more preferable, and 4°C or lower is particularly preferable. A Tg of -12°C or higher makes it easier to increase the 25°C tensile storage modulus of the adhesive. Also, a Tg of less than 10°C can be advantageous from the viewpoint of improving the flexibility of the adhesive.

[0067] The glass transition temperature (Tg) of a polymer tends to increase when the mobility of the main chain and side chains in the polymer backbone is reduced, and conversely, tends to decrease when the mobility of the main chain and side chains in the polymer backbone is increased. Methods for adjusting the Tg of a polymer include adjusting the monomer composition and adjusting the molecular weight of the polymer.

[0068] The glass transition temperature (Tg) of a polymer can be calculated, for example, based on the following equation (Y) (Fox equation): 1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + Wn / Tgn (Y) [In equation (Y), Tg is the glass transition temperature of the polymer (unit: K), Tgi (i = 1, 2, ..., n) is the glass transition temperature when monomer i forms a homopolymer (unit: K), and Wi (i = 1, 2, ..., n) represents the mass fraction of monomer i in the total monomer components]. The above equation (Y) is the calculation formula when the polymer is composed of n types of monomer components: monomer 1, monomer 2, ..., monomer n.

[0069] The glass transition temperature when forming a homopolymer refers to the glass transition temperature of the homopolymer of the monomer in question, and specifically refers to the glass transition temperature (Tg) of a polymer formed using only one monomer (sometimes referred to as "monomer X") as the monomer component. The specific values ​​are given in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). Note that the glass transition temperature (Tg) of a homopolymer not listed in the aforementioned literature refers to a value obtained, for example, by the following measurement method: In a reactor equipped with a thermometer, stirrer, nitrogen inlet tube, and reflux condenser, 100 parts by mass of monomer X, 0.2 parts by mass of 2,2'-azobisisobutyronitrile, and 200 parts by mass of ethyl acetate as the polymerization solvent are added, and the mixture is stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this manner, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution with a solid content of 33% by mass. Next, this homopolymer solution is cast onto a release liner and dried to prepare a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. Then, approximately 1-2 mg of this test sample is weighed into an aluminum open cell, and the reversing heat flow (specific heat component) behavior of the homopolymer is obtained using a temperature-modulated DSC (product name "Q-2000", manufactured by T.A. Instruments Corporation) at a heating rate of 10°C / min under a nitrogen atmosphere of 50 ml / min. Referring to JIS K 7121:1987, the glass transition temperature (Tg) of the homopolymer is defined as the temperature at the point where a line equidistant in the vertical axis direction from the line extending from the low-temperature baseline and the high-temperature baseline of the obtained reversing heat flow intersects with the curve of the step-like change portion of the glass transition.

[0070] The polymer content in the adhesive composition of this embodiment is preferably 50% by mass or more and 99.9% by mass or less, based on the total amount of the adhesive composition (100% by mass), with the upper limit being more preferably 99.5% by mass, even more preferably 99% by mass, and the lower limit being more preferably 60% by mass, even more preferably 70% by mass.

[0071] The polymer in the adhesive composition of this embodiment may include a first polymer and a second polymer having different Tg values. The polymer in the adhesive composition may further include an nth (n≧3) polymer with different Tg values. In such a form, the adhesive composition may be, for example, a combination of a medium-Tg polymer and a low-Tg polymer, or a combination of a medium-Tg polymer and a high-Tg polymer, as described later. When the adhesive composition contains multiple types of polymers, in this specification they will be referred to as "first polymer," "second polymer," "third polymer," etc., in order of decreasing content. If there are multiple types of polymers with the same content, they will be named in a way that does not overlap.

[0072] (Low Tg Polymer) In addition to a polymer with a glass transition temperature (Tg) of -12°C or higher and less than 10°C (hereinafter also referred to as "medium Tg polymer"), the adhesive composition of this embodiment may further contain a polymer with a Tg of -100°C or higher and less than -12°C (hereinafter also referred to as "low Tg polymer") as a second polymer. The content of the medium Tg polymer relative to the total polymer is preferably 50% by mass or more. In other words, the glass transition temperature (Tg) of the polymer that is included in 50% by mass or more of the total polymer is preferably -12°C or higher and less than 10°C. In other words, it is preferable that the medium Tg polymer is the first polymer. The low Tg polymer may be useful in imparting appropriate drop impact resistance and initial adhesion strength to the adhesive layer formed from the adhesive composition of this embodiment.

[0073] The content of the low-Tg polymer in the polymer component is not particularly limited and can be set according to the purpose. In some embodiments, the content of the low-Tg polymer may be, for example, 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more. Furthermore, the upper limit of the content of the low-Tg polymer can be 50% by mass. From the viewpoint of practicality, such as achieving both adhesive properties, high modulus of elasticity, and high impact resistance, it is preferable in this embodiment to adjust it in the range of 1 to 50% by mass. It may be 50% by mass or less, or 30% by mass or less. It may also be 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0074] In this embodiment, the Tg of the low-Tg polymer is preferably -100°C or higher and less than -12°C. The Tg of the polymer is more preferably -80°C or higher, even more preferably -60°C or higher, and particularly preferably -40°C or higher. Furthermore, it is more preferably -8°C or lower, even more preferably -6°C or lower, and particularly preferably -4°C or lower. A Tg of the polymer of -100°C or higher facilitates the securing of cohesive force and elastic modulus. Furthermore, a Tg of less than -12°C can be advantageous from the viewpoint of improving the flexibility of the adhesive and its resistance to peeling under impact.

[0075] The adhesive layer formed from the adhesive composition of this embodiment preferably has a peak value of tanδ (Tg) on ​​the low-temperature side when dynamic viscoelasticity is measured at a frequency of 1 Hz, which is -30°C to -5°C, more preferably -27°C to -6°C, and even more preferably -25°C to -7°C. A Tg of -30°C or higher facilitates the securing of cohesive force and elastic modulus. Furthermore, a Tg of -5°C or lower can be advantageous from the viewpoint of improving the flexibility of the adhesive and its resistance to peeling under impact.

[0076] Furthermore, since the magnitude of tanδ in the low-temperature region can be considered to approximate the property of losing (dissipating) the energy of impact, which is deformation in the high-speed region, the adhesive layer formed from the adhesive composition of this embodiment can be adjusted to have a peak value of tanδ in the range of 0.01 or more and 2.5 or less. Preferably, the peak value of tanδ is in the range of 0.02 to 2.5, and more preferably in the range of 0.03 to 2.5.

[0077] The peak value of tanδ (Tg) is expressed as the ratio of the loss modulus G'' to the storage modulus G' (G'' / G'). As described above, when the peak value (Tg) is in the region below -5°C and the value of this peak value (Tg) is high (i.e., the loss modulus G'' is large), it is thought that the ability to dissipate impact is enhanced, resulting in an adhesive layer with high impact resistance.

[0078] (High Tg Polymer) In addition to a medium-Tg polymer having a glass transition temperature (Tg) of -12°C or higher and less than 10°C, the adhesive composition of this embodiment may further contain a polymer with a Tg of 10°C or higher and 70°C or lower (hereinafter also referred to as "high Tg polymer") as a second polymer. The high Tg polymer may help to ensure a high modulus of elasticity in the adhesive layer formed from the adhesive composition of this embodiment.

[0079] The content of high-Tg polymers in the polymer components is not particularly limited and can be set according to the purpose. In this embodiment, the content of high-Tg polymers may be, for example, 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more. The upper limit of the content of low-Tg polymers can be 50% by mass. From the viewpoint of practicality, such as achieving both adhesive properties and high modulus of elasticity, it is preferable in this embodiment to adjust it in the range of 1 to 50% by mass. It may be 50% by mass or less, or 30% by mass or less. It may also be 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0080] In this embodiment, the Tg of the high-Tg polymer is preferably 10°C or higher and 70°C or lower. The Tg of the polymer is more preferably 20°C or higher, even more preferably 30°C or higher, and particularly preferably 40°C or higher. Furthermore, it is more preferably 68°C or lower, even more preferably 66°C or lower, and particularly preferably 64°C or lower. Having a Tg of 10°C or higher for the polymer can be advantageous from the viewpoint of improving cohesive strength and elastic modulus. Having a Tg of 70°C or lower can be advantageous from the viewpoint of flexibility and high elastic modulus of the adhesive.

[0081] (Second polymer) From the viewpoint of compatibility, in this embodiment, the second polymer is preferably a polyester polymer.

[0082] In addition to the medium-tg polymer described above, the adhesive composition of this embodiment may further contain a low-tg polymer and a high-tg polymer as the second polymer and the third polymer, or the third polymer and the second polymer, respectively.

[0083] (Ionic Substances and Ionic Liquids) The adhesive composition of this embodiment may contain an ionic substance, and it is preferable that the ionic substance contains an ionic liquid. The ionic liquid is not particularly limited as long as it is a molten salt (room temperature molten salt) composed of a pair of anions and a cation that is liquid at 25°C. Examples of anions and cations are given below, but among the ionic substances obtained by combining these, those that are liquid at 25°C are ionic liquids, and those that are solid at 25°C are not ionic liquids but ionic solids as described later.

[0084] Anions in ionic liquids are, for example, (FSO ２ ) ２ N － (CF ３ SO ２ ) ２ N － (CF ３ CF ２ SO ２ ) ２ N － (CF ３ SO ２ ) ３ C － , Br－ AlCl ４ － Al ２ Cl ７ － NO ３ － BF ４ － , PF ６ － ,CH ３ COO － CF ３ COO － CF ３ CF ２ CF ２ COO － CF ３ SO ３ － CF ３ (CF ２ ) ３ SO ３ － AsF ６ － SbF ６ － , and F (HF) ｎ － These are some examples. Among them, as for anions, (FSO ２ ) ２ N － [Bis(fluorosulfonyl)imide anion] and (CF ３ SO ２ ) ２ N － Anions of sulfonylime compounds such as [bis(trifluoromethanesulfonyl)imide anion] are preferred because they are chemically stable and suitable for improving electrolysis properties.

[0085] In ionic liquids, nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium cations are preferred because they are chemically stable and suitable for improving electrolysis, with imidazolium-based, ammonium-based, pyrrolidinium-based, and pyridinium-based cations being more preferred.

[0086] Examples of imidazolium-based cations include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-nonyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, and 1-dodecyl-3-methylimidazolium cation. Examples include 1-tridecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1-pentadecyl-3-methylimidazolium cation, 1-hexadecyl-3-methylimidazolium cation, 1-heptadecyl-3-methylimidazolium cation, 1-octadecyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, 1-benzyl-3-methylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, and 1,3-bis(dodecyl)imidazolium cation.

[0087] Examples of pyridinium-based cations include 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, and 1-octyl-4-methylpyridinium cation.

[0088] Examples of pyrrolidinium-based cations include 1-ethyl-1-methylpyrrolidinium cation and 1-butyl-1-methylpyrrolidinium cation.

[0089] Examples of ammonium-based cations include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethyl acrylate cation.

[0090] As for the ionic liquid, from the viewpoint of increasing the rate of decrease in adhesive strength when voltage is applied, it is preferable to select cations with a molecular weight of 160 or less as the constituent cations, and the above (FSO ２ ) ２ N － [Bis(fluorosulfonyl)imide anion] or (CF ３ SO ２ ) ２ N － An ionic liquid containing [bis(trifluoromethanesulfonyl)imide anion] and a cation with a molecular weight of 160 or less is particularly preferred. Examples of cations with a molecular weight of 160 or less include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-butyl-1-methylpyrrolidinium cation, tetraethylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethyl acrylate cation.

[0091] Furthermore, cations represented by the following formulas (2-A) to (2-D) are also preferred as cations of the ionic liquid.

[0092]

[0093] R in equation (2-A) １ R represents a hydrocarbon group having 4 to 10 carbon atoms (preferably a hydrocarbon group having 4 to 8 carbon atoms, more preferably a hydrocarbon group having 4 to 6 carbon atoms), and may contain heteroatoms. ２ and R ３ R represents the same or different hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, and even more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may also contain heteroatoms. However, if the nitrogen atom forms a double bond with an adjacent carbon atom,３ does not exist.

[0094] R in formula (2-B) ４ represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), and may contain a hetero atom. R ５ , R ６ , and R ７ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, still more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may contain a hetero atom.

[0095] R in formula (2-C) ８ represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), and may contain a hetero atom. R ９ , R １０ , and R １１ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 16 carbon atoms (preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 8 carbon atoms), and may contain a hetero atom.

[0096] X in formula (2-D) represents a nitrogen, sulfur, or phosphorus atom, and R １２ , R １３ , R １４ , and R １５ are the same or different and represent a hydrocarbon group having 1 to 16 carbon atoms (preferably a hydrocarbon group having 1 to 14 carbon atoms, more preferably a hydrocarbon group having 1 to 10 carbon atoms, still more preferably a hydrocarbon group having 1 to 8 carbon atoms, particularly preferably a hydrocarbon group having 1 to 6 carbon atoms), and may contain a hetero atom. However, when X is a sulfur atom, R １２ does not exist.

[0097] The molecular weight of cations in ionic liquids is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, even more preferably 250 or less, particularly preferably 200 or less, and most preferably 160 or less. It is also usually 50 or more. It is believed that cations in ionic liquids have the property of moving towards the cathode side in the adhesive layer when a voltage is applied, and becoming concentrated near the interface between the adhesive layer and the adherend. In this invention, for this reason, the adhesive strength decreases with voltage application compared to the initial adhesive strength, resulting in electrolysis. Cationics with a small molecular weight, such as 500 or less, are preferable because the movement of cations towards the cathode side in the adhesive layer is easier, and this increases the rate of decrease in adhesive strength when a voltage is applied.

[0098] Examples of commercially available ionic liquids include "Elexel AS-110," "Elexel MP-442," "Elexel IL-210," "Elexel MP-471," "Elexel MP-456," and "Elexel AS-804" from Daiichi Kogyo Seiyaku Co., Ltd., "HMI-FSI" from Mitsubishi Materials Corporation, and "CIL-312" and "CIL-313" from Nippon Carlit Co., Ltd.

[0099] The ionic conductivity of the ionic liquid is preferably 0.1 mS / cm to 10 mS / cm. The upper limit of the ionic conductivity is more preferably 5 mS / cm, even more preferably 3 mS / cm, and the lower limit is more preferably 0.3 mS / cm, even more preferably 0.5 mS / cm. Having an ionic conductivity within this range allows for a sufficient reduction in adhesive strength even at low voltages. The ionic conductivity can be measured, for example, by the AC impedance method using a Solartron 1260 frequency response analyzer.

[0100] While there are no particular restrictions on the content (amount blended) of an ionic substance, preferably an ionic liquid, in the adhesive composition of this embodiment, it is preferable that the content of the ionic substance per 100 parts by mass of polymer is 0.5 parts by mass or more and 30 parts by mass or less. From the viewpoint of reducing the adhesive strength when voltage is applied, the content of the ionic substance per 100 parts by mass of polymer is preferably 0.5 parts by mass or more, and from the viewpoint of increasing the initial adhesive strength, it is preferable that the content is 30 parts by mass or less. From the same viewpoint, it is more preferable that it is 20 parts by mass or less, even more preferable that it is 15 parts by mass or less, particularly preferable that it is 10 parts by mass or less, and most preferable that it is 5 parts by mass or less. Furthermore, it is more preferable that it is 0.6 parts by mass or more, even more preferable that it is 0.8 parts by mass or more, particularly preferable that it is 1.0 part by mass or more, and most preferable that it is 1.5 parts by mass or more.

[0101] (Other Components) The adhesive composition of this embodiment may contain one or more components other than polymers and ionic liquids (hereinafter sometimes referred to as "other components"), as necessary, to the extent that they do not impair the effects of the present invention. The other components that may be contained in the adhesive composition of this embodiment are described below.

[0102] The adhesive composition of this embodiment may contain an ionic additive for the purpose of controlling ionic conductivity. As the ionic additive, for example, an ionic solid can be used.

[0103] An ionic solid is an ionic substance that is solid at 25°C. The ionic solid is not particularly limited, but for example, an ionic substance that is solid among those obtained by combining anions and cations as exemplified in the section describing ionic liquids above can be used. When the adhesive composition contains an ionic solid, the content of the ionic solid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 2.5 parts by mass or less, per 100 parts by mass of polymer.

[0104] The adhesive composition of this embodiment may optionally contain a crosslinking agent for the purpose of improving creep and shear properties by crosslinking the polymer. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Examples of isocyanate-based crosslinking agents include toluene diisocyanate and methylene bisphenyl isocyanate. Commercially available isocyanate-based crosslinking agents include "Duranate TPA-100," "Duranate D101," and "Duranate D201" from Asahi Kasei Chemicals Corporation, "Coronate HL," "Coronate HK," "Coronate HX," and "Coronate 2096" from Tosoh Corporation, and "Takenate D-101E," "Takenate D-127N," and "Takenate D-131N" from Mitsui Chemicals, Inc.

[0105] Examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and 1,6-hexanediol diglycidyl ether. A commercially available epoxy crosslinking agent is the product "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0106] When a crosslinking agent is included, its content is preferably 0.001 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.01 parts by mass or more, per 100 parts by mass of polymer. For example, the content of the crosslinking agent can be 0.1 parts by mass or more, or 1.0 part by mass or more. Furthermore, the upper limit of the crosslinking agent content is preferably 50 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of polymer. The crosslinking agent can be used alone or in combination of two or more types.

[0107] The adhesive composition of this embodiment may, in addition to the crosslinking agent, optionally contain a crosslinking catalyst for the purpose of more effectively promoting the crosslinking reaction. The crosslinking catalyst is not particularly limited and may include zirconium-containing compounds such as zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium ethylacetoacetate, and zirconium octoate compounds (zirconium-based catalysts); tin (Sn)-containing compounds such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tetra-n-butyltin, trimethyltin hydroxide, and butyltin oxide (tin-based catalysts); and aluminum secondary butoxides. Examples of organometallic catalysts include aluminum-containing compounds such as aluminum trisacetylacetonate, aluminum bisethylacetoacetate, and aluminum trisethylacetoacetate (aluminum-based catalysts); iron-containing compounds such as ferric narsem (iron-based catalysts); and titanium-containing compounds such as tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetraoctyl titanate, titanium acetylacetonate, titanium tetraacetylacetonate, and titanium ethylacetoacetate (titanium-based catalysts). Crosslinking catalysts can be used individually or in combination of two or more.

[0108] While not particularly limited, in this embodiment, it is preferable to use a tin-containing compound with high catalytic activity as the crosslinking catalyst. Alternatively, in other embodiments, a non-tin compound may be used as the crosslinking catalyst from the viewpoint of environmental impact and safety. In such embodiments, the crosslinking catalyst does not need to substantially contain a tin-containing compound. Furthermore, in this embodiment, the crosslinking catalyst does not need to contain an iron-based catalyst. For example, in usage embodiments where transparency and optical properties are required for the adhesive layer, discoloration of the adhesive layer can be prevented or suppressed by avoiding the use of iron-based compounds.

[0109] The amount of crosslinking catalyst used is not particularly limited. The amount of crosslinking catalyst used can be, for example, 0.001 parts by mass or more per 100 parts by mass of polyester polymer, with 0.01 parts by mass or more being appropriate. Alternatively, the amount of crosslinking catalyst used can be, for example, 3 parts by mass or less per 100 parts by mass of polyester polymer, with 1 part by mass or less being appropriate, and it may also be 0.3 parts by mass or less, or even 0.1 parts by mass or less.

[0110] The adhesive composition of this embodiment may optionally contain polyethylene glycol or tetraethylene glycol dimethyl ether to assist in the movement of the ionic liquid when a voltage is applied. Polyethylene glycol or tetraethylene glycol dimethyl ether having a number average molecular weight of 100 to 6000 can be used. When these components are included, the content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of polymer.

[0111] The adhesive composition of this embodiment may contain a filler. The shape of the filler is not particularly limited, such as spherical, rod-shaped, plate-shaped, or bowl-shaped, but a spherical shape is preferred. When the filler is spherical, the isotropy of the shape reduces stress concentration on the filler, improving the impact resistance of the filler itself, and / or, non-localized delamination occurs at the interface between the filler and the adhesive layer, and the voids generated inside the adhesive layer grow uniformly and large, continuously relieving stress, and as a result, the impact resistance and / or initial adhesive strength of the adhesive layer are also thought to be improved. Furthermore, when the filler is spherical, the isotropy of the shape is thought to have little effect on the current path in the adhesive layer and thus little effect on electrolysis. Here, "spherical" refers to a shape in which the roundness value, which is expressed as the difference between the radii of two concentric geometric circles divided by 2, is 0.8 to 1.0.

[0112] The filler preferably has an organic surface. When the surface is composed of an organic material, the filler is preferably a hollow filler having a cavity in the center.

[0113] The filler is preferably covered on the surface with urethane or silicone resin, or its surface is modified with isocyanate groups, amino groups, azide groups, or epoxy groups.

[0114] The use of the aforementioned filler is preferable because it is possible to further improve impact resistance and / or initial adhesion while maintaining the electropenetration properties of the adhesive layer. The reason for this is not clear, but at least one of the following (i) to (iv) is possible: (i) The filler has excellent dispersibility in the adhesive layer, resulting in little effect on the current path and little effect on electropenetration. (ii) The dielectric constant of the filler surface is high, making it easier for the electrolyte to move in the adhesive layer. (iii) The molecular chains of the polymer constituting the adhesive layer are more likely to be oriented in the stress direction around the filler, resulting in improved impact absorption within the adhesive layer and thus improved impact resistance and / or initial adhesion. (iv) The filler, which has a lower elastic modulus than the adhesive layer, deforms locally and absorbs the impact, resulting in improved impact resistance and / or initial adhesion of the adhesive layer.

[0115] There are no particular restrictions on the filler content, but it is preferably 0.1 to 45 parts by mass per 100 parts by mass of polymer. More preferably, the filler content is 0.5% by mass or more, even more preferably 1% by mass or more, and particularly preferably 5% by mass or more. Also, it is more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less. A filler content of 0.1 parts by mass or more per 100 parts by mass of polymer is preferable from the viewpoint of increasing impact resistance. Also, a filler content of 45 parts by mass or less per 100 parts by mass of polymer is preferable from the viewpoint of increasing initial adhesion.

[0116] The adhesive composition of this embodiment may optionally contain a conductive filler for the purpose of imparting conductivity to the adhesive composition. The conductive filler is not particularly limited, and general known or conventional conductive fillers can be used, such as graphite, carbon black, carbon fiber, or metal powders such as silver or copper. When a conductive filler is included, the content is preferably 0.1 parts by mass or more and 200 parts by mass or less per 100 parts by mass of polymer. In this specification, a component that applies to both a filler and a conductive filler is referred to as a conductive filler.

[0117] The adhesive composition of this embodiment may optionally contain a corrosion inhibitor to suppress corrosion of the metal adherend. The corrosion inhibitor is not particularly limited, and general known or conventional corrosion inhibitors can be used, such as carbodiimide compounds, adsorption inhibitors, chelate-forming metal deactivators, etc. Examples of carbodiimide compounds include 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide, N,N'-di-tert-butylcarbodiimide, 1,3-bis(p-tolyl)carbodiimide, and polycarbodiimide resins using these as monomers. These carbodiimide compounds can be used individually or in combination of two or more. When the adhesive composition of this embodiment contains a carbodiimide compound, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polymer.

[0118] Examples of adsorbent inhibitors include alkylamines, carboxylates, carboxylic acid derivatives, and alkyl phosphates. Adsorbent inhibitors can be used alone or in combination of two or more. When alkylamines are included as adsorbent inhibitors in the adhesive composition of this embodiment, the content is preferably 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of polymer. When carboxylates are included as adsorbent inhibitors in the adhesive composition of this embodiment, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polymer. When carboxylic acid derivatives are included as adsorbent inhibitors in the adhesive composition of this embodiment, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polymer. When alkyl phosphates are included as adsorbent inhibitors in the adhesive composition of this embodiment, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polymer.

[0119] As the chelate-forming metal deactivator, for example, a triazole group-containing compound or a benzotriazole group-containing compound can be used. These are preferred because they have a high deactivating effect on the surface of metals such as aluminum and do not significantly affect adhesion when included in the adhesive component. The chelate-forming metal deactivator can be used alone or in combination of two or more types. When the adhesive composition of this embodiment contains the chelate-forming metal deactivator, the content is preferably 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of polymer.

[0120] The total content (amount blended) of the corrosion inhibitor is preferably 0.01 parts by mass or more and 30 parts by mass or less per 100 parts by mass of polymer.

[0121] The adhesive composition of this embodiment may also contain various additives such as fillers, plasticizers, anti-aging agents, antioxidants, pigments (dyes), flame retardants, solvents, surfactants (leveling agents), rust inhibitors, tackifying resins, and antistatic agents. The total content of these components is not particularly limited as long as the effects of the present invention are achieved, but it is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of polymer.

[0122] Examples of fillers include silica, iron oxide, zinc oxide, aluminum oxide, titanium oxide, barium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, pyrophyllite clay, kaolin clay, and calcined clay.

[0123] The plasticizer can be a commonly used plasticizer in general resin compositions, such as paraffin oil, process oil, liquid rubber such as liquid polyisoprene, liquid polybutadiene, and liquid ethylene-propylene rubber, tetrahydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, citric acid, and their derivatives, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate, diisononyl adipate (DINA), and isodecyl succinate.

[0124] Examples of anti-aging agents include hindered phenol compounds, aliphatic and aromatic hindered amine compounds, etc. Examples of antioxidants include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA), etc. Examples of pigments include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride salts, sulfates, azo pigments, and organic pigments such as copper phthalocyanine pigments, etc.

[0125] Examples of rust inhibitors include zinc phosphate, tannic acid derivatives, phosphate esters, basic sulfonates, and various rust-preventive pigments. Examples of adhesion promoters include titanium coupling agents and zirconium coupling agents. Examples of antistatic agents include quaternary ammonium salts, or hydrophilic compounds such as polyglycolic acid and ethylene oxide derivatives.

[0126] Examples of tackifying resins include rosin-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, as well as polyamide-based tackifying resins, epoxy-based tackifying resins, and elastomer-based tackifying resins. These tackifying resins can be used individually or in combination of two or more types.

[0127] <Ionic Conductivity of the Adhesive Layer> The ionic conductivity of the adhesive layer correlates with the ease with which the ionic liquid moves within the adhesive layer; the higher the ionic conductivity, the easier it is for the ionic liquid to move.

[0128] The above-mentioned ionic conductivity can be controlled by appropriately adjusting, for example, the polymer components in the adhesive composition, the type and content of the ionic liquid, and the type and content of the ionic additive, within the preferred range described above.

[0129] The ionic conductivity mentioned above refers to the ionic conductivity measured as follows.

[0130] (Manufacture of Sample for Measurement (Bonded Body Sample)) The adhesive layer (adhesive sheet) is made into a sheet with a size of 10 mm × 80 mm, and the metal layer side of a film with a metal layer (product name "Metalmy CR", manufactured by Toray Film Processing Co., Ltd., thickness 25 μm, size 10 mm × 100 mm) is bonded as the base material to obtain a single-sided adhesive sheet with a base material. Peel off the release liner of the single-sided adhesive sheet with a base material, and attach a stainless steel plate (SUS316L) as the adherend to the peeled surface, press it back and forth once with a 2 kg roller, and leave it in an environment of 25°C and 50% RH for 72 hours to obtain a bonded body composed of a stainless steel plate 6 / an electrically peelable adhesive layer (adhesive sheet) 1' / a film with a metal layer (base material for energization) 5'. The outline of the bonded body is shown in FIG. 4.

[0131] (Measurement of Capacitance and Ionic Conductivity) For the measurement of capacitance and ionic conductivity, a potentiostat / galvanostat (for example, SP-300 manufactured by Biologic) is used. First, apply an AC voltage of 10 mV between the stainless steel plate and the metal layer side of the film with a metal layer using a potentiostat / galvanostat, and change the frequency from 1 Hz to 200 kHz to obtain a Cole-Cole plot.

[0132] Next, consider the bulk of the adhesive layer as a parallel circuit of a resistance R ａｄｈ and a pseudo-capacitance Q ａｄｈ and set the equivalent circuit of the bonded body sample as shown in FIG. 5, and fit the obtained Cole-Cole plot by the following formula (A). The pseudo-capacitance Q ａｄｈ and the fractal parameter α obtained by fitting are substituted into the following formula (B) to calculate the capacitance C ａｄｈ . Note that the resistance component R ０ is the wiring resistance.

[0133]

[0134] Then, the ionic conductivity σ of the adhesive layer can be obtained using the following formula (C) with the resistance component R ａｄｈ of the bulk of the adhesive layer obtained from formula (A).

[0135]

[0136] In formula (C), l is the thickness of the adhesive layer, and A is the area of ​​the adhesive surface of the adhesive layer.

[0137] In this embodiment, the ionic conductivity of the adhesive layer is not particularly limited, but it is preferable that it be 0.02 μS / m or higher from the viewpoint of sufficiently reducing the adhesive strength after voltage application. The lower limit of the ionic conductivity of the adhesive layer is more preferably 0.03 μS / m or higher, even more preferably 0.04 μS / m or higher, and particularly preferably 0.05 μS / m or higher. There is no particular upper limit, but from the viewpoint of improving the reusability of the adhesive by increasing the number of times the adhesive strength is sufficiently reduced after peeling off after voltage application and reattaching to the adherend, it is preferable that it be less than 20 μS / m, more preferably less than 8 μS / m, even more preferably less than 1 μS / m, and particularly preferably less than 0.1 μS / m.

[0138] The ionic conductivity of the adhesive layer tends to increase with the selection of a polymer with a low Tg, and / or an ionic substance with low viscosity, and / or an increase in the amount of ionic substance added, and tends to decrease with the selection of a polymer with a high Tg, and / or an ionic substance with high viscosity, and / or a decrease in the amount of ionic substance added.

[0139] <Initial adhesive strength, adhesive strength after voltage application, and adhesive strength reduction rate> The initial adhesive strength, adhesive strength after voltage application, and adhesive strength reduction rate of the adhesive composition of this embodiment can be evaluated by the 180° peel test described herein.

[0140] (Initial Adhesion) In this embodiment, the initial adhesion is preferably 3.0 N / cm or more. The initial adhesion can be, for example, 4.0 N / cm or more, 5.0 N / cm or more, 6.0 N / cm or more, 7.0 N / cm or more, 8.0 N / cm or more, 9.0 N / cm or more, or 10.0 N / cm or more. When the initial adhesion is 3.0 N / cm or more, the adhesion to the adherend is sufficient, and the adherend is less likely to peel off or shift.

[0141] Initial adhesive strength tends to increase with the selection of polymers with a low Tg, and / or the reduction of ionic substances, and / or the reduction of crosslinking agents, and / or the reduction of fillers, and tends to decrease with the selection of polymers with a high Tg, and / or the increase of ionic substances, and / or the increase of crosslinking agents, and / or the increase of fillers.

[0142] (Adhesive strength after voltage application) In this embodiment, it is preferable that the adhesive strength after voltage application is sufficiently small compared to the initial adhesive strength. It is preferable that the adhesive strength after voltage application is 1.0 N / cm or less. The adhesive strength after voltage application can be, for example, 0.5 N / cm or less, 0.3 N / cm or less, 0.1 N / cm or less, or 0.05 N / cm or less. An initial adhesive strength of 1.0 N / cm or less is preferable because it allows for non-destructive peeling even of fragile adherends.

[0143] The adhesive strength after voltage application can be adjusted by the polymer's Tg, and / or the viscosity of the ionic substance, and / or the amount of ionic substance added, and / or the amount of crosslinking agent added, and / or the amount of filler added. More specifically, the adhesive strength after voltage application tends to decrease, for example, by lowering the elastic modulus of the adhesive composition, and / or by selecting a highly mobile ionic substance, and / or by increasing the amount of ionic substance added, and / or by decreasing the amount of filler added. Even more specifically, it tends to decrease, for example, by selecting a polymer with a low Tg, and / or by decreasing the amount of crosslinking agent added, and / or by selecting a low-viscosity ionic substance.

[0144] Furthermore, the adhesion reduction rate, calculated from the adhesive strength after voltage application and the initial adhesive strength measured by the above method using the following formula, is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. Adhesion reduction rate (%) = 100 - (Adhesion strength after voltage application / Initial adhesive strength) × 100 There is no particular upper limit to the adhesion reduction rate, but for example, it can be 99.999% or less.

[0145] The rate of decrease in adhesive strength can be adjusted by the same method as for adjusting the adhesive strength after voltage application, namely by the Tg of the polymer, and / or the viscosity of the ionic substance, and / or the amount of ionic substance added, and / or the amount of crosslinking agent added, and / or the amount of filler added.

[0146] The applied voltage and voltage application time during electrolysis are not limited to those described above, and are not particularly limited as long as the adhesive sheet can be peeled off. The preferred ranges are shown below. The applied voltage is preferably 1V or more, more preferably 3V or more, and even more preferably 6V or more. It is also preferably 100V or less, more preferably 50V or less, even more preferably 30V or less, and particularly preferably 15V or less. The voltage application time is preferably 60 seconds or less, more preferably 40 seconds or less, even more preferably 20 seconds or less, and particularly preferably 10 seconds or less. In such cases, workability is excellent. The shorter the application time, the better, but it is usually 1 second or more.

[0147] <Method for Producing the Adhesive Composition> The adhesive composition of the present invention is not particularly limited, but can be produced by appropriately stirring and mixing a polymer with, if necessary, an ionic liquid, additives, a crosslinking agent, a crosslinking catalyst, polyethylene glycol, a conductive filler, etc.

[0148] [Adhesive Sheet] (Composition of the Adhesive Sheet) The adhesive sheet of this embodiment is not particularly limited as long as it comprises an adhesive layer formed from the adhesive composition of this embodiment described above (hereinafter also referred to as the "electro-peelable adhesive layer"). The adhesive sheet of this embodiment may contain only one or two or more adhesive layers formed from the adhesive composition of this embodiment described above. The adhesive sheet of this embodiment may also have adhesive layers other than the electro-peelable adhesive layer (hereinafter sometimes referred to as "other adhesive layers"). In addition to the above, the adhesive sheet of this embodiment may also have a base material, a conductive layer, an electrical conductive base material, an intermediate layer, and a primer layer. The adhesive sheet of this embodiment may be, for example, in the form of a roll or in the form of a sheet. Note that "adhesive sheet" also means "adhesive tape". That is, the adhesive sheet of this embodiment may be an adhesive tape having a tape-like form.

[0149] The adhesive sheet of this embodiment may consist only of an electro-peelable adhesive layer without a base material, i.e., it may be a double-sided adhesive sheet without a base material layer (base material-less). The adhesive sheet of this embodiment may be a double-sided adhesive sheet having a base material, wherein both sides of the base material are adhesive layers (electro-peelable adhesive layers, or other adhesive layers). Alternatively, the adhesive sheet of this embodiment may be a single-sided adhesive sheet having a base material, wherein only one side of the base material is an adhesive layer (electro-peelable adhesive layer, or other adhesive layer). The adhesive sheet of this embodiment may have a release liner for the purpose of protecting the surface of the adhesive layer, but such release liner is not included in the adhesive sheet of this embodiment.

[0150] The adhesive sheet of this embodiment preferably comprises, in this order, an electrically conductive substrate having at least one conductive surface and an adhesive layer, wherein the conductive surface of the electrically conductive substrate and the adhesive layer are in contact, and the adhesive layer is formed from the adhesive composition of this embodiment described above.

[0151] Furthermore, it is preferable that the adhesive sheet of this embodiment further comprises another adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer.

[0152] Furthermore, the adhesive sheet of the present invention further comprises another adhesive layer, a second conductive substrate, and a second other adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer, and the second conductive substrate and the second other adhesive layer are formed in this order on the surface of the adhesive layer opposite to the conductive substrate, and the conductive surface of the second conductive substrate is in contact with the adhesive layer.

[0153] The structure of the adhesive sheet in this embodiment is not particularly limited, but adhesive sheet X1 shown in Figure 1, adhesive sheet X2 showing a laminated structure in Figure 2, and adhesive sheet X3 showing a laminated structure in Figure 3 are preferred. Adhesive sheet X1 is a substrate-less double-sided adhesive sheet consisting only of an electro-peelable adhesive layer 1. Adhesive sheet X2 is a substrate-attached double-sided adhesive sheet having a layer structure of adhesive layer 2, an electrical conductive substrate 5 (substrate 3 and conductive layer 4), and an electro-peelable adhesive layer 1. Adhesive sheet X3 is a substrate-attached double-sided adhesive sheet having a layer structure of adhesive layer 2, an electrical conductive substrate 5 (substrate 3 and conductive layer 4), an electro-peelable adhesive layer 1, an electrical conductive substrate 5 (substrate 3 and conductive layer 4), and an adhesive layer 2. In the electrical conductive substrate 5 of adhesive sheets X2 and X3 shown in Figures 2 and 3, the substrate 3 is not essential, and it may consist only of the conductive layer 4. Also, in the adhesive sheet X2 of Figure 2, it may be a single-sided adhesive sheet without an adhesive layer 2.

[0154] The base material 3 is not particularly limited, but examples include paper-based base materials such as paper, fiber-based base materials such as cloth and nonwoven fabric, plastic-based base materials such as films and sheets made of various plastics (polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, acrylic resins such as polymethyl methacrylate, etc.), and laminates thereof. The base material may have a single layer or a multi-layer form. The base material may be subjected to various treatments as needed, such as back treatment, antistatic treatment, and primer treatment.

[0155] The conductive layer 4 is not particularly limited as long as it is a conductive layer, but may be a metal-based substrate such as a metal foil (e.g., aluminum, magnesium, copper, iron, tin, gold, SUS304, SUS316, etc.), a metal plate (e.g., aluminum, magnesium, copper, iron, tin, silver, etc.), a conductive polymer, etc. It may also be a metal (e.g., aluminum, iron, niobium, titanium, chromium, nickel, etc.) provided on the substrate 3, or a material containing two or more of these metals, or an alloy mainly composed of these metals (e.g., nickel-chromium alloy, SUS304, SUS316, etc.) that has been sputtered or deposited. Furthermore, when a nickel-chromium alloy is used as the conductive layer 4 provided on the substrate 3, the chromium content is preferably 5 to 60 atm%, more preferably 8 to 23 atm%, for example, it can be 8 to 9 atm%, 15 to 16 atm%, or 22 to 23 atm%. Furthermore, when a plastic substrate is used as the base material 3 and a nickel-chromium alloy is used as the conductive layer 4 provided thereon, silicon may be formed as an intermediate layer because it exhibits excellent adhesion to both the plastic substrate and the nickel-chromium alloy.

[0156] The conductive substrate 5 is not particularly limited as long as it is a substrate having a conductive layer (conducts electricity), but examples include a substrate on which a metal layer has been formed on its surface. For example, a substrate as exemplified above may have a metal layer formed on its surface by methods such as plating, chemical vapor deposition, or sputtering. Examples of the metal layer include the metals exemplified above, alloys mainly composed of metal, metal plates, conductive polymers, etc.

[0157] In adhesive sheet X1, it is preferable that the adherends on both sides are adherends having a metal adhesion surface. In adhesive sheet X2, it is preferable that the adherend on the side with the electropenetrating adhesive layer 1 is an adherend having a metal adhesion surface.

[0158] Examples of metal-bonded surfaces include conductive surfaces made of metals such as aluminum, copper, iron, magnesium, tin, gold, silver, and lead, with surfaces made of metals containing aluminum being particularly preferred. Examples of adherends having a metal-bonded surface include sheets, parts, and plates made of metals such as aluminum, copper, iron, magnesium, tin, gold, silver, and lead. Adherends other than those having a metal-bonded surface are not particularly limited, but include fibrous sheets such as paper, cloth, and nonwoven fabrics, and films and sheets of various plastics.

[0159] From the viewpoint of initial adhesive strength, the thickness of the electro-release adhesive layer 1 is preferably 1 μm or more and 1000 μm or less. The upper limit of the thickness of the electro-release adhesive layer 1 is more preferably 500 μm, even more preferably 300 μm, particularly preferably 200 μm, and most particularly preferably 50 μm. The lower limit is more preferably 3 μm, even more preferably 5 μm, and particularly preferably 8 μm. Note that if the adhesive sheet is a substrate-less double-sided adhesive sheet (adhesive sheet X1 shown in Figure 1) consisting of only one electro-release adhesive layer, the thickness of the electro-release adhesive layer is the thickness of the adhesive sheet.

[0160] From the viewpoint of adhesive strength, the thickness of the adhesive layer 2 is preferably 1 μm or more and 2000 μm or less. The upper limit of the thickness of the adhesive layer 2 is more preferably 1000 μm, even more preferably 500 μm, and particularly preferably 100 μm, while the lower limit is more preferably 3 μm, even more preferably 5 μm, and particularly preferably 8 μm.

[0161] The thickness of the base material 3 is preferably 10 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500 μm, even more preferably 300 μm, and particularly preferably 100 μm. The lower limit is more preferably 12 μm, and even more preferably 25 μm.

[0162] The thickness of the conductive layer 4 is preferably 0.001 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500 μm, even more preferably 300 μm, even more preferably 50 μm, and even more preferably 10 μm, and the lower limit is more preferably 0.01 μm, even more preferably 0.03 μm, and even more preferably 0.05 μm.

[0163] The thickness of the conductive substrate 5 is preferably 10 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500 μm, even more preferably 300 μm, and particularly preferably 100 μm, while the lower limit is more preferably 12 μm, and even more preferably 25 μm.

[0164] The surfaces of the electro-peelable adhesive layer and other adhesive layers of the adhesive sheet in this embodiment may be protected by a release liner. The release liner is not particularly limited, but examples include a release liner in which the surface of a substrate (liner substrate) such as paper or plastic film is treated with silicone, and a release liner in which the surface of a substrate (liner substrate) such as paper or plastic film is laminated with a polyolefin resin. The thickness of the release liner is not particularly limited, but is preferably 10 μm or more and 100 μm or less.

[0165] The thickness of the adhesive sheet in this embodiment is preferably 20 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 μm, even more preferably 300 μm, and particularly preferably 200 μm, while the lower limit is more preferably 30 μm, and even more preferably 50 μm.

[0166] In particular, in the case of the adhesive sheet X2 shown in Figure 2, the thickness of the adhesive sheet is preferably 50 μm or more and 2000 μm or less. The upper limit of the thickness is more preferably 1000 μm, even more preferably 200 μm, and the lower limit is more preferably 80 μm, even more preferably 100 μm.

[0167] In particular, in the case of the adhesive sheet X3 shown in Figure 3, the thickness of the adhesive sheet is preferably 100 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 μm, even more preferably 300 μm, the lower limit is more preferably 150 μm, and even more preferably 200 μm.

[0168] (Method for Manufacturing Adhesive Sheets) The method for manufacturing the adhesive sheet of this embodiment can be a known or conventional manufacturing method. For the electropenetrating adhesive layer in the adhesive sheet of this embodiment, one method is to apply a solution obtained by dissolving the adhesive composition of this embodiment in a solvent as needed onto a release liner, and then drying and / or curing it. For other adhesive layers, one method is to apply a solution obtained by dissolving an adhesive composition that does not contain ionic liquids and additives in a solvent as needed onto a release liner, and then drying and / or curing it. The solvent and release liner can be those listed above.

[0169] Conventional coaters (e.g., gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray roll coaters, etc.) can be used for application.

[0170] By the above method, an electrorelease adhesive layer and other adhesive layers can be manufactured, and the adhesive sheet of this embodiment can be manufactured by laminating the electrorelease adhesive layer and other adhesive layers onto a substrate, a conductive layer, and an electrically conductive substrate as appropriate. Alternatively, instead of a release liner, an adhesive sheet may be manufactured by applying the adhesive composition to a substrate, a conductive layer, and an electrically conductive substrate.

[0171] (Method for electrolytically removing adhesive sheets) In this embodiment, the adhesive sheet can be removed from the adherend by applying a voltage to the electrolytically removable adhesive layer, thereby creating a potential difference in the thickness direction of the electrolytically removable adhesive layer. For example, in the case of adhesive sheet X1, if the adherend has metal adherends on both sides, the sheet can be removed by applying current to the metal adherends on both sides and applying a voltage to the electrolytically removable adhesive layer. In the case of adhesive sheet X2, if the adherend has a metal adherend on the electrolytically removable adhesive layer side, the sheet can be removed by applying current to the conductive adherend and the conductive layer 4 and applying a voltage to the electrolytically removable adhesive layer. In the case of adhesive sheet X3, the sheet can be removed by applying current to the conductive layers 4 on both sides and applying a voltage to the electrolytically removable adhesive layer. It is preferable to connect terminals to one end and the other end of the adhesive sheet so that the voltage is applied to the entire electrolytically removable adhesive layer. Note that the above-mentioned one end and the other end may be parts of the adherend that has a metal adherend if the adherend has a metal adherend. Furthermore, when peeling, water may be added to the interface between the metal adherend and the electropenetrating adhesive layer before applying voltage.

[0172] (Applications of Adhesive Sheets) Conventional re-peelable technologies include adhesive layers that harden and peel off with ultraviolet (UV) irradiation or adhesive layers that peel off with heat. Adhesive sheets using such adhesive layers cannot be used when ultraviolet (UV) irradiation is difficult or when heat damages the adherend. The adhesive sheet of this embodiment, which has the above-mentioned electro-peelable adhesive layer, does not use ultraviolet light or heat, and can be easily peeled off by applying voltage without damaging the adherend.

[0173] The uses of the adhesive sheet according to the embodiment of the present invention are not particularly limited and can be used without restriction for various purposes. For example, the adhesive sheet can be attached to components constituting electronic devices and used for purposes such as fixing, joining, and reinforcing components. The adhesive sheet according to the embodiment of the present invention is particularly suitable for fixing components of portable electronic devices. For example, a portable electronic device can include the adhesive sheet according to the embodiment of the present invention. The adhesive sheet according to the embodiment of the present invention can be preferably used, for example, in the form of a double-sided adhesive sheet for fixing or joining components.

[0174] Furthermore, examples of rigid members to be joined by the adhesive sheet in this embodiment include silicon substrates for semiconductor wafer applications, sapphire substrates, SiC substrates and metal base substrates for LEDs, TFT substrates and color filter substrates for displays, and base substrates for organic EL panels. Examples of fragile members to be joined by the double-sided adhesive sheet include semiconductor substrates such as compound semiconductor substrates, silicon substrates for MEMS devices, passive matrix substrates, surface cover glass for smartphones, OGS (One Glass Solution) substrates in which a touch panel sensor is attached to the cover glass, organic substrates and organic-inorganic hybrid substrates mainly composed of silsesquioxane, flexible glass substrates for flexible displays, and graphene sheets.

[0175] [Bonded Body] The bonded body of this embodiment preferably comprises the adhesive sheet of this embodiment described above and a conductive material, wherein the adhesive layer is attached to the conductive material.

[0176] Furthermore, it is also preferable that the bonded body of this embodiment comprises the adhesive sheet of this embodiment described above and an adherend material, wherein the other adhesive layer is attached to the adherend material.

[0177] The bonded structure of this embodiment may have a laminated structure including, for example, a substrate having a metal adhesion surface and an adhesive sheet in which an electro-peelable adhesive layer is bonded to the metal adhesion surface. Examples of substrates having a metal adhesion surface include those made of metals mainly composed of aluminum, copper, iron, magnesium, tin, gold, silver, and lead, with metals containing aluminum being particularly preferred.

[0178] Examples of the bonding bodies in this embodiment include an adhesive sheet X1 comprising an adherend having a metal adhesion surface on both sides of an electropenetrating adhesive layer 1, an adhesive sheet X2 comprising an adherend having a metal adhesion surface on the electropenetrating adhesive layer 1 side and an adherend on the adhesive layer 2 side, and an adhesive sheet X3 comprising an adherend having adherends on both sides of the adhesive layer 2.

[0179] The following are disclosed herein: <1> An adhesive composition comprising a polymer, wherein the tensile storage modulus E' of the adhesive layer formed from the adhesive composition at 25°C is 0.5 MPa or more, and the adhesive strength reduction rate expressed by the following formula is 60% or more: Adhesive strength reduction rate (%) = 100 - (Adhesive strength after voltage application / Initial adhesive strength) × 100 (Initial adhesive strength) One side of the adhesive layer or adhesive sheet is bonded to the metal layer surface of a metal layered film (thickness 25 μm), and the other side is bonded to a stainless steel plate (SUS316L), pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 25°C and 50% RH. The adhesive layer is peeled off the stainless steel plate by peeling 180° at a tensile speed of 300 mm / min. The initial adhesive strength shall be calculated according to Method 1 for Measuring Peel Adhesion, as described in JIS Z 0237:2009. (Adhesion after voltage application) The negative and positive electrodes of a DC current machine are attached to the stainless steel plate and the metal layer of the metal-layered film, respectively. A voltage of 30V is applied for 30 seconds, and immediately after, peeling is performed in the same manner as the initial adhesive strength measurement described above, and the adhesive layer or adhesive sheet is peeled off from the stainless steel plate. The adhesion strength after voltage application shall be calculated according to Method 1 for Measuring Peel Adhesion, as described in JIS Z 0237:2009.

[0180] <2> The adhesive composition according to <1>, wherein the glass transition temperature (Tg) of the adhesive layer formed from the adhesive composition is -10°C or higher and less than 40°C. <3> The adhesive composition according to <1> or <2>, wherein the polymer includes a polyester polymer. <4> The adhesive composition according to any one of <1> to <3>, wherein the glass transition temperature (Tg) of the polymer that is included in 50% by mass or more of the total polymer is -12°C or higher and less than 10°C.

[0181] <5> An adhesive composition according to any one of <1> to <4>, comprising an ionic substance. <6> An adhesive composition according to <5>, wherein the content of the ionic substance per 100 parts by mass of the polymer is 0.5 parts by mass or more and 30 parts by mass or less. <7> An adhesive composition according to any one of <1> to <6>, wherein the initial adhesive strength is 3.0 N / cm or more. <8> An adhesive composition according to any one of <1> to <7>, wherein the adhesive strength after voltage application is 1.0 N / cm or less.

[0182] <9> The adhesive composition according to any one of <1> to <8>, further comprising a filler. <10> The adhesive composition according to <9>, wherein the surface of the filler is composed of an organic material. <11> The adhesive composition according to <10>, wherein the surface of the filler is covered with urethane or silicone resin. <12> The adhesive composition according to <10> or <11>, wherein the filler is a hollow filler. <13> The adhesive composition according to any one of <9> to <12>, wherein the content of the filler per 100 parts by mass of the polymer is 0.1 to 45 parts by mass.

[0183] <14> The adhesive composition according to any one of <1> to <13>, wherein the polymer comprises a first polymer and a second polymer having different Tg values. <15> The adhesive composition according to <14>, wherein the second polymer is a polyester polymer.

[0184] <16> An adhesive sheet comprising an adhesive layer formed from an adhesive composition according to any one of <1> to <15>. <17> An adhesive sheet comprising, in this order, an electrically conductive substrate having at least one conductive surface and an adhesive layer, wherein the conductive surface of the electrically conductive substrate and the adhesive layer are in contact, and the adhesive layer is formed from an adhesive composition according to any one of <1> to <15>. <18> The adhesive sheet according to <17>, further comprising another adhesive layer, wherein the other adhesive layer is formed on the surface of the electrically conductive substrate opposite to the adhesive layer. <19> The adhesive sheet according to <17> or <18>, further comprising another adhesive layer, a second conductive substrate, and a second other adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer, the second conductive substrate and the second other adhesive layer are formed in this order on the surface of the adhesive layer opposite to the conductive substrate, and the conductive surface of the second conductive substrate is in contact with the adhesive layer.

[0185] <20> A bond comprising an adhesive sheet according to any one of <17> to <19> and a conductive material, wherein the adhesive layer is attached to the conductive material. <21> A bond comprising an adhesive sheet according to <19> and an adherend material, wherein the other adhesive layer is attached to the adherend material.

[0186] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to these examples. The weight-average molecular weights below were measured by gel permeation chromatography (GPC) using the method described above.

[0187] <Synthesis of Polymers> (Synthesis Example 1) A stirrer, thermometer, nitrogen tube, and water separator were attached to a four-necked separable flask, and polycarboxylic acid and polyol were charged in amounts of 1 equivalent each. Di-n-butyltin oxide (manufactured by Kishida Chemical Co., Ltd., molecular weight 249) was added as a polymerization catalyst at a rate of 0.05 parts per 100 parts of the total amount of polycarboxylic acid and polyol. Xylene was added as a solvent for evacuating reaction water, and the mixture was heated to 180°C while stirring under a nitrogen atmosphere, and this temperature was maintained. After a while, the efflux and separation of reaction water was observed, and the reaction began to proceed. The reaction was continued for about 24 hours to obtain the polyester polymer (polymer A) of Synthesis Example 1. In Synthesis Example 1, adipic acid (AD), sebacic acid (SB), isophthalic acid (IP), and terephthalic acid (TP) were used as polycarboxylic acids in a molar ratio of AD:SB:IP:TP = 3:12:35:0.1. Furthermore, neopentyl glycol (NPG), 1,4-butanediol (BD), and 1,6-hexanediol (HD) were used as polyols in a molar ratio of 32:9:9. The weight-average molecular weight (Mw) of the polyester polymer (polymer A) obtained in Synthesis Example 1 was 130,000, and the glass transition temperature (Tg) was -2°C.

[0188] (Synthesis Example 2) A polyester polymer (polymer B) was synthesized in the same manner as in Synthesis Example 1, except that adipic acid (AD), sebacic acid (SB), isophthalic acid (IP), and terephthalic acid (TP) were used as polycarboxylic acids in a molar ratio of AD:SB:IP:TP = 3:27:20:0.1, and neopentyl glycol (NPG), 1,4-butanediol (BD), and 1,6-hexanediol (HD) were used as polyols in a molar ratio of 32:9:9. The weight-average molecular weight (Mw) of the polyester polymer (polymer B) obtained in Synthesis Example 6 was 130,000, and the glass transition temperature (Tg) was -34°C.

[0189] (Synthesis Example 3) A polyester polymer (polymer C) was synthesized in the same manner as in Synthesis Example 1, except that adipic acid (AD), sebacic acid (SB), isophthalic acid (IP), and terephthalic acid (TP) were used as polycarboxylic acids in a molar ratio of AD:SB:IP:TP = 3:21:26:0.1, and neopentyl glycol (NPG), 1,4-butanediol (BD), and 1,6-hexanediol (HD) were used as polyols in a molar ratio of 32:9:9. The weight-average molecular weight (Mw) of the polyester polymer (polymer C) obtained in Synthesis Example 3 was 130,000, and the glass transition temperature (Tg) was -12°C.

[0190] (Synthesis Example 4) A polyester polymer (polymer D) was synthesized in the same manner as in Synthesis Example 1, except that dimer acid (DA), isophthalic acid (IP), and terephthalic acid (TP) were used as polycarboxylic acids in a molar ratio of DA:IP:TP = 25:15:10, and 3-methyl-1,5-pentanediol (MPD) was used as a polyol in equivalent amounts to the polycarboxylic acids. The weight-average molecular weight (Mw) of the polyester polymer (polymer D) obtained in Synthesis Example 4 was 130,000, and the glass transition temperature (Tg) was -34°C.

[0191] (Synthesis Example 5) A polyester polymer (polymer E) was synthesized in the same manner as in Synthesis Example 1, except that sebacic acid (SB), isophthalic acid (IP), and terephthalic acid (TP) were used as polycarboxylic acids in a molar ratio of SB:IP:TP = 2:23:25, and ethylene glycol (EG) and neopentyl glycol (NPG) were used as polyols in a molar ratio of 25:25. The weight-average molecular weight (Mw) of the polyester polymer (polymer E) obtained in Synthesis Example 5 was 60,000, and the glass transition temperature (Tg) was 61°C.

[0192] <Preparation of Adhesive Compositions> The polymers obtained above, along with additional components, were stirred and mixed to obtain the adhesive compositions of Examples 1 to 12 and Comparative Example 1. Tables 1 and 2 show the amounts of each component. The values ​​for each component in Tables 1 and 2 represent parts by mass. The amount of polymer (parts by mass) indicates the amount of solids in the polymer solution (parts by mass). The abbreviations for each component in Tables 1 and 2 are as follows.

[0193] (Crosslinking agent) T / C: Polyfunctional epoxy resin, trade name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Company, Inc. Takenate D-101E: Trimethylolpropane / tolylene diisocyanate trimer adduct, manufactured by Mitsui Chemicals, Inc. (Crosslinking catalyst) DBTDL: Dibutyltin dilaurate, manufactured by Tokyo Chemical Industry Co., Ltd. (Ionic liquid) AS-110: Cation: 1-ethyl-3-methylimidazolium cation, Anion: Bis(fluorosulfonyl)imide anion, trade name "Elexel AS-110", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0194] (Fillers) H-600T: Hollow urethane, manufactured by Negami Kogyo Co., Ltd. (average particle size 8-12 μm, spherical) KMP-601: Silicone resin coated silicone rubber filler, manufactured by Shin-Etsu Chemical Co., Ltd. (average particle size 12 μm, minimum particle size 2 μm, maximum particle size 25 μm, true specific gravity 0.98, water content 0.1%, rubber hardness 30, spherical) KE-P250: Silica filler, manufactured by Nippon Shokubai Co., Ltd. (average particle size 2.5 μm, true specific gravity 1.9, spherical)

[0195] <Physical Properties and Evaluation> [Tensile Storage Modulus E' at 25°C] The adhesive layer (thickness 50 μm) formed from each example's adhesive composition was cut into strips 10 mm wide x 40 mm long using a utility knife to serve as a sample for measurement. The dynamic viscoelasticity of the above sample was measured using a solid viscoelasticity analyzer (product name "RSAIII", manufactured by Rheometric Scientific) in tensile mode, at a frequency of 1 Hz and a chuck distance of 20 mm, in the range of -50 to 100°C at a heating rate of 10°C / min, and the tensile storage modulus E' at 25°C was calculated. The results are shown in Tables 1 and 2.

[0196] [Polymer Tg] Approximately 3 to 10 mg of polymer was weighed into an aluminum open cell, and the reversing heat flow (specific heat component) behavior of the homopolymer was obtained using a temperature-modulated DSC (product name "Q-2000", manufactured by T.A. Instruments Corporation) at a heating rate of 10°C / min under a nitrogen atmosphere of 50 ml / min. Referring to JIS K 7121:1987, the temperature at which the curve of the stepwise transition portion of the glass transition intersects a line equidistant in the vertical axis direction from the line extending from the low-temperature baseline and high-temperature baseline of the obtained reversing heat flow was defined as the polymer Tg. The measurement results are shown in Tables 1 and 2.

[0197] [Tg of the adhesive layer formed from the adhesive composition] Dynamic viscoelasticity measurements were performed in the same manner as the measurement of the tensile storage modulus E' at 25°C described above. Next, the temperature at which the loss tangent (tanδ) peak was observed, as confirmed from the results of the dynamic viscoelasticity measurement, was read as the Tg of the adhesive layer. If multiple tanδ peaks were observed, the temperature at which the largest peak value (maximum peak value) was observed was taken as the Tg of the adhesive layer. The measurement results are shown in Tables 1 and 2.

[0198] [Ionic Conductivity of the Adhesive Layer] Using the adhesive composition of each example, measurement samples (jointed samples) were prepared as follows, and the ionic conductivity of the adhesive layer was determined by the following method. The results are shown in Tables 1 and 2.

[0199] (Preparation of measurement samples (joint samples)) The adhesive composition of each example was applied to the peeled surface of a polyethylene terephthalate peel liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) using an applicator to achieve a uniform thickness. Next, after standing at room temperature for 10 minutes, it was heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 50 μm. Then, the obtained electro-peelable adhesive layer (adhesive sheet) was made into a sheet with a size of 10 mm x 80 mm, and the metal layer side of a metal-layered film (product name "MetalMe CR", manufactured by Toray Film Processing Co., Ltd., thickness 25 μm, size 10 mm x 100 mm) was laminated to it as a substrate to create a single-sided adhesive sheet with a substrate. The release liner of a single-sided adhesive sheet with a base material was peeled off, a stainless steel plate (SUS316L) was attached to the peeled surface as the adherend, and it was pressed once back and forth with a 2 kg roller. After being left for 72 hours in an environment of 25°C and 50% RH, a bonded body consisting of a stainless steel plate 6 / an electro-peelable adhesive layer (adhesive sheet) 1' / a metal-layered film (electrical-conducting base material) 5' was obtained. An outline of the bonded body is shown in Figure 4.

[0200] (Measurement of Capacitance and Ionic Conductivity) A potentiometer / galvanostat (Biologic, SP-300) was used to measure capacitance and ionic conductivity. First, an AC voltage of 10 mV was applied between the stainless steel plate and the metal layer surface of the metal-layered film of the bonded sample obtained using the potentiometer / galvanostat, and a cole-cole plot was obtained by changing the frequency from 10 Hz to 200 kHz.

[0201] Next, the bulk of the adhesive layer is subjected to resistance R ａｄｈ and pseudocapacitance Q ａｄｈ Considering it as a parallel circuit, the equivalent circuit of the junction sample was set as shown in Figure 5, and the obtained cole-cole plot was fitted using the following equation (A). The pseudocapacitance Q obtained by fitting was ａｄｈ By substituting the fractal parameter α into equation (B) below, the capacitance C ａｄｈ The following is calculated. Note that the resistance component R ０ This is the wiring resistance.

[0202]

[0203] Next, the bulk resistance component R of the adhesive layer, obtained from equation (A) ａｄｈ The ionic conductivity σ of the adhesive layer was determined using the following formula (C).

[0204]

[0205] In formula (C), l is the thickness of the adhesive layer, and A is the area of ​​the adhesive surface of the adhesive layer.

[0206] [Initial Adhesion] The adhesive composition for each example was applied to the peel-treated surface of a polyethylene terephthalate peel-off liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) using an applicator to achieve a uniform thickness. Next, after standing at room temperature for 10 minutes, it was heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 50 μm. Then, the obtained electro-peelable adhesive layer (adhesive sheet) was made into a sheet with a size of 10 mm x 80 mm, and the metal layer side of a metal-layered film (product name "MetalMe CR", manufactured by Toray Film Processing Co., Ltd., thickness 25 μm, size 10 mm x 100 mm) was bonded to it as a substrate to create a single-sided adhesive sheet with a substrate. The release liner of a single-sided adhesive sheet with a substrate was peeled off, and a stainless steel plate (SUS316L) was attached to the peeled surface as the adherend. A 2 kg roller was used to press down once back and forth, and the sheet was left for 72 hours in an environment of 25°C and 50% RH to obtain a bond consisting of a stainless steel plate 6 / an electro-peelable adhesive layer (adhesive sheet) 1' / a metal-layered film (electrically conductive substrate) 5'. An outline of the bond is shown in Figure 4. Subsequently, the bond was peeled in the direction of the arrow in Figure 4 using a peel test machine (product name "Variable Angle Peel Tester YSP", manufactured by Asahi Seiko Co., Ltd.), and the adhesive strength in a 180° peel test (tensile speed: 300 mm / min, peel temperature 25°C) was measured. The initial adhesive strength was calculated according to the measurement method 1 of peel adhesive strength described in JIS Z 0237:2009. The measurement results are shown in Tables 1 and 2.

[0207] [Adhesion after voltage application] Before peeling, the positive and negative electrodes of a DC current machine were attached to the α and β points in Figure 4 of the bonded body, respectively. The adhesion after voltage application was measured in the same manner as the initial adhesion measurement described above, except that the bond was peeled immediately after applying a voltage of 30V for 30 seconds. The adhesion after voltage application was calculated according to the method for measuring peel adhesion described in JIS Z 0237:2009. The measurement results are shown in Tables 1 and 2.

[0208] [Adhesion Reduction Rate] Using the initial adhesion and adhesion after voltage application measured by the method described above, the adhesion reduction rate due to voltage application was calculated using the following formula. The results are shown in Tables 1 and 2. Adhesion Reduction Rate (%) = 100 - (Adhesion after voltage application / Initial adhesion) × 100

[0209] [Bending Amount of Adhesive] The adhesive layer (thickness 50 μm) formed from the adhesive composition of each example was made into a sheet with dimensions of 35 mm x 100 mm. Aluminum plates (A5052P H32 (JIS H4000:2014), thickness 0.5 mm, size 35 mm x 100 mm) were attached to both sides of the sheet to obtain a joint consisting of aluminum plate / adhesive layer / aluminum plate. Subsequently, a bending test fixture was attached to an Autograph (AGX-V, manufactured by Shimadzu Corporation), and a bending test was performed with a support distance of 8 mm and a compression speed of 3 mm / min, and the bending amount when 30 N was applied was measured. The measurement results are shown in Tables 1 and 2.

[0210]

[0211]

[0212] As shown in Tables 1 and 2, the adhesive compositions of Examples 1 to 12, which had a tensile storage modulus E' of 0.5 MPa or higher at 25°C and an adhesive strength reduction rate of 60% or higher, were able to adhere at room temperature, reduce their adhesive strength by applying voltage, and further suppress the bending of the adherend when bonded to it. In contrast, the adhesive composition of Comparative Example 1 failed to suppress the bending of the adherend when bonded to it, showing inferior results compared to the examples.

[0213] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0214] This application is based on the Japanese Patent Application No. 2024-161378 filed on September 18, 2024, the contents of which are incorporated herein by reference.

[0215] An adhesive sheet comprising an adhesive layer formed from the adhesive composition of this embodiment can be used, for example, to fix components of portable electronic devices.

[0216] X1, X2, X3 Adhesive Sheet 1 Electropeelable adhesive layer 2 Adhesive layer 3 Substrate 4 Conductive layer 5 Conductive substrate

Claims

1. An adhesive composition containing a polymer, wherein the tensile storage modulus E' of the adhesive layer formed from the adhesive composition at 25°C is 0.5 MPa or more, and the adhesive strength reduction rate expressed by the following formula is 60% or more. Adhesive strength reduction rate (%) = 100 - (Adhesive strength after voltage application / Initial adhesive strength) × 100 (Initial adhesive strength) One side of the adhesive layer or adhesive sheet is bonded to the metal layer surface of a metal layered film (thickness 25 μm), and the other side is bonded to a stainless steel plate (SUS316L), pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 25°C and 50% RH. The adhesive layer is peeled off the stainless steel plate by performing a 180° peel at a tensile speed of 300 mm / min. The initial adhesive strength is the value calculated in accordance with the method for measuring peel adhesive strength 1 described in JIS Z 0237:2009. (Adhesion after voltage application) The negative and positive electrodes of a DC current machine are attached to the stainless steel plate and the metal layer of the metal-layered film, respectively. A voltage of 30V is applied for 30 seconds, and immediately afterward, peeling is performed in the same manner as the initial adhesion measurement described above, and the adhesive layer or adhesive sheet is peeled off from the stainless steel plate. The adhesion after voltage application is calculated according to the peel-off adhesion measurement method 1 described in JIS Z 0237:2009.

2. The adhesive composition according to claim 1, wherein the glass transition temperature (Tg) of the adhesive layer formed from the adhesive composition is -10°C or higher and less than 40°C.

3. The adhesive composition according to claim 1, wherein the polymer comprises a polyester polymer.

4. The adhesive composition according to claim 1, wherein the glass transition temperature (Tg) of the polymer, which is present in an amount of 50% by mass or more relative to the total polymer, is -12°C or higher and less than 10°C.

5. The adhesive composition according to claim 1, comprising an ionic substance.

6. The adhesive composition according to claim 5, wherein the content of the ionic substance per 100 parts by mass of the polymer is 0.5 parts by mass or more and 30 parts by mass or less.

7. The adhesive composition according to claim 1, wherein the initial adhesive strength is 3.0 N / cm or more.

8. The adhesive composition according to claim 1, wherein the adhesive strength after the application of the voltage is 1.0 N / cm or less.

9. The adhesive composition according to claim 1, further comprising a filler.

10. The adhesive composition according to claim 9, wherein the surface of the filler is composed of an organic material.

11. The adhesive composition according to claim 10, wherein the surface of the filler is covered with urethane or silicone resin.

12. The adhesive composition according to claim 10, wherein the filler is a hollow filler.

13. The adhesive composition according to claim 9, wherein the content of the filler is 0.1 to 45 parts by mass per 100 parts by mass of the polymer.

14. The adhesive composition according to claim 1, wherein the polymer comprises a first polymer and a second polymer having different Tg values.

15. The adhesive composition according to claim 14, wherein the second polymer is a polyester polymer.

16. An adhesive sheet comprising an adhesive layer formed from the adhesive composition according to any one of claims 1 to 15.

17. An adhesive sheet comprising, in this order, an electrically conductive substrate having at least one conductive surface, and an adhesive layer, wherein the conductive surface of the electrically conductive substrate and the adhesive layer are in contact, and the adhesive layer is formed from the adhesive composition described in any one of claims 1 to 15.

18. The adhesive sheet according to claim 17, further comprising another adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer.

19. The adhesive sheet according to claim 17, further comprising another adhesive layer, a second conductive substrate, and a second other adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer, the second conductive substrate and the second other adhesive layer are formed in this order on the surface of the adhesive layer opposite to the conductive substrate, and the conductive surface of the second conductive substrate is in contact with the adhesive layer.

20. A bond comprising the adhesive sheet described in claim 17 and a conductive material, wherein the adhesive layer is attached to the conductive material.

21. A bonding body comprising the adhesive sheet described in claim 19 and an adherend material, wherein the other adhesive layer is attached to the adherend material.

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