Adhesive composition, adhesive sheet, and bonding body

Abstract

The present invention provides an adhesive composition that can achieve the initial adhesive strength necessary for bonding, while also exhibiting extremely low adhesive strength after voltage application, thereby enabling a significant reduction in adhesive strength and providing excellent electropeelability. An adhesive composition comprising a polymer and an electrolyte, wherein the electrolyte has a reduced cation product with an HSP distance of 9 MPa from the polymer. 0.5 The following is true; the surface free energy is 24 mJ / m 2 ~36mJ / m 2 An adhesive composition wherein the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is less than 60%.

Description

[Technical Field]

[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. [Background technology]

[0002] Conventional adhesives were required to adhere strongly to the substrate once adhesion was complete, making them difficult to peel off afterward. On the other hand, adhesives that were required to be easily peelable even after adhesion was complete were inherently weak in terms of adhesive strength. The development of adhesives that are re-peelable, achieving strong adhesion and ensuring long-term reliability once adhesion to the substrate is complete, while also exhibiting easy delamination when a predetermined peeling trigger is applied. Such triggers include mechanical energy, thermal / ultraviolet (UV) energy, and electrical energy.

[0003] One application of adhesives that can be re-peeled using electrical energy is electrorelease tape. Electrorelease tape can adhere strongly to a substrate, but can be easily peeled off by applying voltage to it, and its adhesive strength is restored when the voltage is removed. As a double-sided adhesive sheet for electro-peelable tapes that achieves both adhesive strength and peelability, an adhesive sheet (electro-peelable adhesive sheet) is known in which an ionic liquid consisting of cations and anions is added to components such as polymers that constitute the adhesive composition, and by applying a voltage to the adhesive layer formed by the adhesive composition, the adhesive sheet that adheres to the adherend can be peeled off (Patent Documents 1-3). In the electropenetrating adhesive sheets described in Patent Documents 1 to 3, it is believed that when a voltage is applied to the electropenetrating adhesive sheet, reduction occurs at the cathode side of the electrode used to apply the voltage due to the movement of cations in the ionic liquid in the adhesive composition, and oxidation occurs at the anode side due to the movement of anions in the ionic liquid, thereby weakening the adhesive strength at the adhesive interface and making it easier to peel off. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-037354 [Patent Document 2] Patent No. 6097112 [Patent Document 3] Patent No. 4139851 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, with the regulation of the "right to repair," there has been a growing demand for technologies that enable users to repair their own products. Meanwhile, easy disassembly and recycling technologies are also becoming more widespread, and there is a need for peelable technologies that can strongly promote these technologies. Such technologies only need to function (e.g., electrolysis) when needed (when repair is desired), and as long as functions such as electrolysis are guaranteed, they can be realized with various adhesive compositions and adhesive sheet configurations. [Means for solving the problem]

[0006] As a result of diligent research, the inventors have discovered that desired electropenetration properties can be achieved by adjusting the mobility of the electrolyte cations contained in the adhesive composition to the interface between the adherend and the adhesive layer (ionic conductivity), the diffusion of the cation reduction product generated by the reduction reaction at the interface into the bulk of the adhesive layer (adhesion recovery rate), and the solubility of the cation reduction product accumulated at the interface into the polymer constituting the adhesive layer (HSP distance). This led to the present invention.

[0007] In other words, the present invention relates to an adhesive composition comprising a polymer and an electrolyte, The electrolyte is such that the reduced product of the cation of the electrolyte is The HSP distance to the aforementioned polymer is 9 MPa 0.5 The following; Surface free energy is 24 mJ / m 2 ~36mJ / m 2 It is that, The adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is less than 60%. This is an adhesive composition characterized by the following features.

[0008] Preferably, the adhesive composition has an ionic conductivity of 0.02 μS / m or higher for the adhesive layer formed from the adhesive composition. It is even more desirable that the ionic conductivity of the adhesive layer be 5 μS / m or higher. In the adhesive composition according to the present invention, it is desirable that the adhesive strength recovery rate after 2 minutes is 30% or less. In the adhesive composition according to the present invention, the surface free energy is 25 mJ / m 2 ~30mJ / m 2 It would be desirable for it to be so. In the adhesive composition according to the present invention, it is preferable that the polymer is an acrylic polymer, a polyester polymer, or a rubber polymer. In the adhesive composition according to the present invention, it is preferable that the polymer is a polyester-based polymer. In the adhesive composition according to the present invention, the polyester polymer comprises monomer units derived from a dicarboxylic acid and monomer units derived from a diol, and it is desirable that the total proportion of monomer units derived from the dicarboxylic acid and monomer units derived from the diol in the total monomer units (100 mol%) constituting the polyester polymer is 90 mol% or more. In the adhesive composition according to the present invention, it is desirable that the proportion of monomer units derived from aliphatic dicarboxylic acid to the total amount of monomer units derived from the dicarboxylic acid is greater than 60 mol%. In the adhesive composition according to the present invention, it is desirable that the proportion of monomer units containing aromatic rings in the total monomer units (100 mol%) constituting the polyester polymer is less than 20 mol%. In the adhesive composition according to the present invention, it is desirable that the proportion of monomer units derived from aromatic dicarboxylic acid in the total amount of the dicarboxylic acid is 45 mol% or more. In the adhesive composition according to the present invention, it is desirable that the proportion of monomer units containing aromatic rings in the total monomer units (100 mol%) constituting the polyester polymer is greater than 20 mol%. In the adhesive composition according to the present invention, it is preferable that the polymer is an acrylic polymer. In the adhesive composition according to the present invention, it is desirable that the ionic conductivity of the adhesive layer formed from the adhesive composition is 40 μS / m or higher. In the adhesive composition according to the present invention, it is desirable that the glass transition temperature of the adhesive layer formed from the adhesive composition is -30°C or higher. In the adhesive composition according to the present invention, it is preferable that the electrolyte is an ionic liquid. In the adhesive composition according to the present invention, it is desirable that the amount of electrolyte added to the adhesive composition is 10 parts or less based on the mass of the polymer. The present invention also relates to the above-mentioned adhesive composition for fixing components in electrical and electronic equipment. In the adhesive composition according to the present invention, it is desirable that the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 15 minutes is less than 15%. In the adhesive composition according to the present invention, it is desirable that the ionic conductivity is 20 μS / m or higher. In the adhesive composition according to the present invention, the ionic conductivity is given by the following formula Cmax = (Adhesion strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes (%)) × 0.445 + 10 It is desirable that the Cmax value is less than or equal to the value obtained by the formula μS / m. In the adhesive composition according to the present invention, the ionic conductivity is given by the following formula Cmax = (Adhesion strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes (%)) × 0.445 + 4.5 It is desirable that the Cmax value is less than or equal to the value obtained by the formula μS / m. In the adhesive composition according to the present invention, it is desirable that the haze value of the adhesive layer formed from the adhesive composition is 30% or less. In the adhesive composition according to the present invention, it is desirable that the ionic conductivity is less than 1 μS / m. In the adhesive composition according to the present invention, it is desirable that the Lewis basicity of the anion in the ionic liquid is 0.2 or less, or 0.27 or more and 0.60 or less. In the adhesive composition according to the present invention, it is desirable that the content of compounds having a polyoxyalkylene skeleton is less than 1% by mass. The present invention further comprises an electropenetrating adhesive sheet having an electropenetrating adhesive layer formed from the above-mentioned adhesive composition. In the electropenetrating adhesive sheet according to the present invention, it is preferable that the sheet further comprises a conductive substrate having at least one conductive surface, and that the conductive surface of the conductive substrate is in contact with the adhesive layer. In the electropenetrating adhesive sheet according to the present invention, it is preferable that the sheet further comprises another adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer. In the electropenetrating adhesive sheet according to the present invention, the sheet further comprises another adhesive layer, a second conductive substrate having at least one conductive surface, and a second other adhesive layer, wherein the other adhesive layer, the second conductive substrate, and the second other adhesive layer are formed in this order on the surface of the conductive substrate opposite to the adhesive layer, and it is preferable that the conductive surface of the second conductive substrate is in contact with the adhesive layer. In the electropenetrating adhesive sheet according to the present invention, it is desirable that the conductive substrate has protrusions that protrude in the planar direction from the adhesive layer. Preferably, the present invention further comprises the electropenetrating adhesive sheet and a conductive material, wherein the adhesive layer is attached to the conductive material. [Effects of the Invention]

[0009] The adhesive composition of the present invention can achieve the initial adhesive strength necessary for bonding, while having extremely low adhesive strength after voltage application, thus enabling a large reduction in adhesive strength and possessing excellent electropeelability. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view showing an example of the adhesive sheet of the present invention. [Figure 2] Figure 2 is a cross-sectional view showing an example of the laminated structure of the adhesive sheet of the present invention. [Figure 3] Figure 3 is a cross-sectional view showing another example of the laminated structure of the adhesive sheet of the present invention. [Figure 4] Figure 4 is a cross-sectional view showing yet another example of the laminated structure of the adhesive sheet of the present invention. [Figure 5] Figure 5 is a cross-sectional view illustrating the outline of the 180° peel test method in the embodiment. [Figure 6] Figure 6 is an equivalent circuit diagram of a junction sample for capacitance and ionic conductivity measurements. [Modes for carrying out the invention]

[0011] The adhesive composition according to the present invention is an adhesive composition comprising a polymer and an electrolyte, The electrolyte consists of a reduced form of the electrolyte cation and a polymer at 9 MPa. 0.5 The following HSP distances are present: The surface free energy of the reduced cation is 24 mJ / m². 2 More than 36mJ / m 2 The following: The adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is less than 60%. It is characterized by the following:

[0012] [Electro-peelable adhesive sheet] [Structure of electropenetrating adhesive sheet] The adhesive composition of the present invention is an adhesive composition used exclusively for electrolysis, and can be, for example, an electrolysis adhesive composition described later, and can also be an electrolysis adhesive sheet comprising an electrolysis adhesive layer formed from such an electrolysis adhesive composition.

[0013] An electropenetrating adhesive sheet may have multiple electropenetrating adhesive layers, and may also have conductive substrates, adhesive layers, intermediate layers, and undercoat layers in addition to the electropenetrating adhesive layers. The electropenetrating adhesive sheet may be in the form of a roll or a sheet. The term "electropenetrating adhesive sheet" also includes the meaning of "adhesive tape." That is, the electropenetrating adhesive sheet according to the embodiment of the present invention may be an adhesive tape having a tape-like form.

[0014] The electropenetrating adhesive sheet may consist only of an electropenetrating adhesive layer, or it may be a single-sided electropenetrating adhesive sheet having a conductive substrate and an electropenetrating adhesive layer on only one side of the conductive substrate. An electropenetrating adhesive sheet may further comprise other adhesive layers that do not have electropenetrating properties. For example, an electropenetrating adhesive sheet may comprise an electropenetrating adhesive layer and another adhesive layer on both sides of a conductive substrate. In the case where the conductive substrate has a conductive layer on one side of a support substrate, the other adhesive layer may be provided on the side of the electropenetrating adhesive sheet that faces the support substrate. Furthermore, the electropenetrating adhesive sheet may also be a double-sided electropenetrating adhesive sheet in which the conductive substrate has conductive layers on both sides of the supporting substrate, and each conductive layer is provided with an electropenetrating adhesive layer. Furthermore, while an electro-peelable adhesive sheet may have a release liner for the purpose of protecting the electro-peelable adhesive layer and the surface of other adhesive layers, such release liner shall not be included in the electro-peelable adhesive sheet.

[0015] Furthermore, the electro-peelable adhesive sheet may further comprise another adhesive layer, a second conductive layer, and a second other adhesive layer. In other words, it may have a five-layer configuration of other adhesive layer / conductive substrate / electro-peelable adhesive layer / second conductive substrate / second other adhesive layer. Here, in the case where the conductive substrate and the second conductive substrate have a conductive layer on one side of the support substrate, the other adhesive layer and the second other adhesive layer may be formed on the side of the support substrate opposite to the conductive layer. In other words, it may have a layer configuration of other adhesive layer / support substrate / conductive layer / electro-peelable adhesive layer / conductive layer / support substrate / second other adhesive layer.

[0016] The structure of the electropenetrating adhesive sheet is not particularly limited, but the electropenetrating adhesive sheet X0 shown in Figure 1, the electropenetrating adhesive sheet X1 shown in Figure 2, the electropenetrating adhesive sheet X2 shown in Figure 3, and the electropenetrating adhesive sheet X3 shown in Figure 4 are preferred.

[0017] The electropenetrating adhesive sheet X0 shown in Figure 1 is an electropenetrating adhesive sheet consisting only of an electropenetrating adhesive layer 1.

[0018] The electro-peelable adhesive sheet X1 shown in Figure 2 is an electro-peelable adhesive sheet in which a conductive substrate 5 consisting of a conductive layer 4 and a support substrate 3 is laminated on an electro-peelable adhesive layer 1.

[0019] The electro-peelable adhesive sheet X2 shown in Figure 3 is an electro-peelable adhesive sheet in which an additional adhesive layer 2 is provided on the support base 3 of the electro-peelable adhesive sheet X1 shown in Figure 2, which is made by laminating a conductive base 5 consisting of a conductive layer 4 and a support base 3 on an electro-peelable adhesive layer 1.

[0020] The electropenetrating adhesive sheet X3 shown in Figure 4 is a double-sided electropenetrating adhesive sheet having a conductive layer 4, a support substrate 3, and other adhesive layers 2 on both sides of the electropenetrating adhesive layer 1, in that order.

[0021] The conductive layer 4 is not particularly limited as long as it is a conductive layer, but may be a layer formed from a conductive material such as a metal substrate containing a metal-based material such as a metal foil (e.g., aluminum, magnesium, copper, iron, tin, gold, etc.), a metal substrate consisting of an alloy mainly composed of the metals exemplified above, a conductive polymer (e.g., a composite made of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid, etc.), or conductive carbon (e.g., graphene, carbon composed of carbon atoms having sp2 and sp3 bonds, etc.). Alternatively, the metal (niobium, titanium, chromium, nickel, copper, aluminum, gold, platinum, iron, silver, tin, silicon, magnesium, lead, or alloys mainly composed of these metals (e.g., SUS alloy) etc.) provided on the support substrate 3 may be a plating layer, a sputtered film, or a vapor-deposited film. The conductive layer 4 may have a single layer form or a multi-layer form. The conductive layer 4 may be a layer formed from one or more of the materials exemplified above. For example, it may be formed from a conductive composition in which the metal-based materials exemplified above are dispersed in a resin (for example, a conductive composition in which metal particles are dispersed in an epoxy resin).

[0022] 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 100 μm, even more preferably 50 μm, even more preferably 10 μm, even more preferably 5 μm, even more preferably 1 μm, and even more preferably 0.5 μm. The lower limit is more preferably 0.01 μm, even more preferably 0.02 μm, even more preferably 0.03 μm, even more preferably 0.04 μm, and even more preferably 0.05 μm. When the conductive layer 4 is a metal plating layer, sputtered layer, or vapor deposition film provided on the support substrate 3, it is preferably 0.001 μm or more and 1 μm or less. From the viewpoint of productivity, the upper limit of the thickness is preferably 0.5 μm or less, more preferably 0.3 μm or less, still more preferably 0.2 μm or less, and even more preferably 0.1 μm or less. From the viewpoint of electrical conductivity, the lower limit of the thickness is preferably 0.002 μm or more, and more preferably 0.003 μm or more. Further, the thickness of the conductive layer can be selected according to the purpose of use and use conditions, that is, the applied voltage conditions for which electrical peeling is desired (whether peeling is desired at a high voltage or a low voltage), that is, the required surface resistance value. For example, it may be 0.08 μm or less, 0.06 μm or less, 0.04 μm or less, or 0.02 μm or less. In some embodiments, the thickness of the conductive layer is 0.02 μm to 0.5 μm, preferably 0.03 μm to 0.3 μm, and more preferably 0.03 μm to 0.1 μm.

[0023] The surface resistance value of the conductive layer 4 is, for example, 1.0×10 4 Ω / sq or less, preferably 1.0×10 <000001​​​​​​​​The supporting substrate 3 is not particularly limited, but examples include paper-based substrates such as paper, fiber-based substrates such as cloth and nonwoven fabric, plastic-based substrates 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.), foam substrates of various plastics (polyolefin resins such as ethylene, polypropylene, ethylene-propylene copolymer polymer, and ethylene-vinyl acetate copolymer polymer; polyurethane resins; rubber-based resins such as acrylic rubber and other elastomers, etc.), and laminates thereof. The substrate may have a single layer or a multi-layer form. The substrate may be subjected to various treatments as needed, such as back treatment, antistatic treatment, and primer treatment.

[0025] The thickness of the support substrate 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, even more preferably 100 μm, even more preferably 70 μm, even more preferably 50 μm, and even more preferably 40 μm, while the lower limit is more preferably 12 μm and even more preferably 25 μm.

[0026] The conductive substrate 5 is not particularly limited as long as it is a conductive (electrically conductive) substrate. It may be a single-layer or laminated structure of a conductive material, and examples include films, sheets, nonwoven fabrics, woven fabrics, foam substrates made of conductive materials such as metals (e.g., aluminum, magnesium, copper, iron, tin, silver, gold, lead, or alloys thereof (e.g., stainless steel)), conductive metal oxides (e.g., ITO), inorganic materials such as carbon (e.g., graphene, carbon formed from carbon atoms having sp2 and sp3 bonds), and conductive polymers (e.g., composites made of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid). Examples of conductive foam substrates include, for example, a substrate containing a conductive filler in a foam substrate of the various plastics mentioned above. If it includes a support substrate 3 and a conductive layer 4, the conductive layer may be formed on the surface of the support substrate 3, and the method of formation is not particularly limited. The substrate surface can be configured to exhibit appropriate conductivity. For example, the conductive layer may be formed on the surface of the support substrate as exemplified above by methods such as plating, chemical vapor deposition, sputtering, conventional coating methods (e.g., spray coating, roll coating, dip coating, etc.), or bonding using adhesives or bonding agents. Furthermore, if the conductive substrate is a single-layer or multi-layer structure of conductive material, the surface resistance value is, for example, 1.0 × 10⁻⁶. 4 Ω / □ or less, preferably 1.0 × 10 3 The resistance is less than or equal to Ω / □. The surface resistance can be calculated by dividing the resistivity measured by the four-terminal method in accordance with JIS K 7194 (1994) by the thickness of the conductive substrate. Furthermore, the surface resistance of the conductive layer 4 can be selected according to the intended use and usage conditions, i.e., the conditions of the applied voltage required for electrical peeling. For example, 5.0 × 10 2 It can be less than or equal to Ω / □, and 1.0 × 10 2 It may be less than or equal to Ω / □, less than or equal to 50Ω / □, less than or equal to 40Ω / □, or less than or equal to 30Ω / □.

[0027] The thickness of the conductive substrate 5 is preferably 2 μm or more and 1000 μm or less. From the viewpoint of the conformability and processability of the adhesive sheet, the upper limit of the thickness is more preferably 500 μm, even more preferably 300 μm, even more preferably 150 μm, even more preferably 100 μm, even more preferably 70 μm, even more preferably 50 μm, even more preferably 40 μm, even more preferably 25 μm, and even more preferably 10 μm. As the thickness decreases, the conformability to the surface shape of the adherend tends to improve. From the viewpoint of the handling of the adhesive sheet, the lower limit is preferably 2 μm, more preferably 10 μm, even more preferably 12 μm, and even more preferably 25 μm. In some embodiments, the thickness of the conductive substrate is 2 μm to 1000 μm, preferably 10 μm to 500 μm, and more preferably 10 μm to 300 μm.

[0028] Electropeelable adhesive sheets can be attached to conductive materials to form a bonded structure. As for the conductive material, the description of the conductive material that can be used for the conductive layer 4 described above can be directly applied. For example, the adherend can be a metal adherend, and as the metal adherend, for example, it can be a surface made of a metal mainly composed of aluminum, copper, iron, magnesium, tin, gold, silver, and lead, and among these, it is preferable that it is a surface made of a metal containing aluminum. Examples of adherends having a metal adherend can be sheets, parts, and plates made of a metal mainly composed of aluminum, copper, iron, magnesium, tin, gold, silver, and lead. The adherend having a metal adherend may also be a non-conductive material adherend having a conductive layer as the adherend surface. As for the conductive layer provided on the non-conductive material adherend, the description of the conductive material that can be used for the conductive layer 4 described above can be directly applied. While not particularly limited, examples of non-conductive material substrates include Japanese paper, fine paper, kraft paper, crepe paper, cloth, and fibrous sheets such as woven and nonwoven fabrics; 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, polyimide resins, etc.); plastic substrates such as housings; glass substrates; and laminates thereof. The substrate may be in the form of a single layer or a multi-layer structure. If necessary, various treatments such as rust prevention treatment, back treatment, antistatic treatment, and primer treatment may be applied.

[0029] The adhesive sheet according to the embodiment of the present invention may further comprise a coating layer. Preferably, the coating layer is provided between the electrorelease adhesive layer and the conductive layer. By further comprising the coating layer, the adhesive sheet of this embodiment provides a barrier to the electrolyte contained in the electrorelease adhesive layer from penetrating into the conductive layer when a voltage is applied, thereby preventing the conductive layer from peeling off the substrate. Furthermore, the contact between the coating layer and the electrorelease adhesive layer improves the adhesion between the electrorelease adhesive layer and the conductive layer, preventing the delamination within the adhesive sheet caused by the thermal curing of the electrorelease adhesive layer when exposed to high-temperature environments, which would otherwise reduce the interfacial adhesion between the electrorelease adhesive layer and the conductive substrate.

[0030] The coating layer is a layer mainly composed of resin or inorganic material, and can be formed from a resin composition mainly composed of resin components or a composition mainly composed of inorganic material. The coating layer is made of at least one resin selected from polyester resins, acrylic resins, epoxy resins, urethane resins, or SiN x SiO x Preferably, it contains at least one inorganic substance selected from Al2O3, Ni, NiCr, and carbon.

[0031] [Adhesion strength to low-polarity substrates] • An electrorelease adhesive layer formed from the adhesive composition according to the present invention, or an electrorelease adhesive sheet equipped therewith, has an adhesive strength to an adherend with a water contact angle of 100°, preferably 0.5 N / mm or more, more preferably 3.0 N / mm, even more preferably 6.0 N / mm, and more preferably 8.0 N / mm. Since the electrorelease adhesive can be applied to low-polarity adherends, which generally do not exhibit high adhesive strength, it can be applied to a variety of adherends. • Adhesion to low-polarity adherends generally tends to increase as the Tg of the polymer decreases and the hydrogen bonding term (described later) in the HSP value of the polymer decreases. It can be further increased by adding a low-polarity tackifier.

[0032] [Corrosiveness of metal substrates] When the adherend is metal, there is a possibility that the adhesive composition may cause corrosion of the adherend, resulting in a defective appearance. The method for evaluating the corrosiveness of a metal substrate by an adhesive composition can be appropriately set depending on the type of metal substrate and the manner in which it is used. For example, it can be calculated as follows: the corrosion rate of the aluminum (area of ​​the corroded portion / area to which the electro-release adhesive layer formed from the adhesive composition is attached) × 100) when an electro-release adhesive layer formed from the adhesive composition is bonded to aluminum (A5052) and left to stand in an environment of 60°C 90%RH or 85°C 85%RH for 3 to 30 days. Specifically, first, the adhesive composition of the present invention is applied to the peeled surface of a polyethylene terephthalate peel liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) with a peeled surface using an applicator to obtain a uniform thickness, and then heated and dried under predetermined conditions to obtain an electro-release adhesive layer (adhesive sheet) with a thickness of 50 μm. Next, the obtained electro-peelable adhesive layer (adhesive sheet) is made into a sheet with dimensions of 10 mm x 80 mm, and the metal layer side of a metal-layered film (product name "1005CR", manufactured by Toray Film Processing Co., Ltd., thickness 12 μm, size 10 mm x 100 mm) is bonded to the side without the release liner to create a single-sided adhesive sheet with a substrate. Next, the release liner of the single-sided adhesive sheet with a base material is peeled off, and the peeled surface is attached to a metal plate (aluminum plate A5052) as the adherend. A 2kg roller is pressed back and forth once, and the sheet is left for 72 hours in an environment of 23±12℃ and 50±5%RH to obtain a bonded body consisting of a metal plate, an electro-peelable adhesive layer (adhesive sheet), and a film with a metal layer. The resulting bonded material is left to stand in a constant temperature chamber at 85°C and 85% RH for 500 hours, after which the single-sided adhesive sheet with the substrate is peeled off the metal plate. The peeled-off substrate is photographed using OM Digital Solutions Co., Ltd.'s "Tough TG-7". Corroded areas can be observed visually as changes in appearance such as loss of metallic luster or discoloration. They can also be observed as dark-colored objects using computer software (Image J ver. 1.54d). The photographs are taken indoors, with a shadow created using black paper to prevent direct light from hitting the substrate. The captured images are imported into computer software (Image J ver. 1.54d), converted to grayscale using the software, and then binarized (lower brightness limit: 145, upper brightness limit: 235). The corrosion rate (%) is calculated by performing the following calculations on the binarized image using the aforementioned software. A lower corrosion rate indicates that the metal plate is not corroded, meaning that the adhesive composition is capable of forming an adhesive layer that is less susceptible to metal corrosion. Corrosion rate [%] = [(Area of ​​dark-colored objects) / (Area of ​​light-colored objects + Area of ​​dark-colored objects)] × 100 The corrosion rate of the adhesive composition evaluated in this manner is preferably less than 50%, more preferably less than 30%, even more preferably less than 20%, and particularly preferably less than 5%. This is because it is considered that no appearance defects will occur due to corrosion of the adherend. Furthermore, because the corrosion of the metal adherend is minimal, a stable voltage can be applied to the adhesive layer via the conductive substrate and the metal adherend. From this perspective, the water content, water vapor permeability, and oxygen permeability of the adhesive composition should be as low as possible. These values ​​decrease as the polymer's Tg increases, its free volume decreases, and the hydrogen bonding term in the polymer's HSP value decreases. Furthermore, the higher the HOMO energy level and lower the LUMO energy level of the monomer constituting the polymer, the higher the polymer's coordination ability to metal, thereby suppressing corrosion. Monomers containing the element N, in particular, have high coordination ability and a high corrosion suppression effect. In addition, as will be described later, by having the Lewis basicity of the anion of the ionic substance within a specific range, it is possible to realize an adhesive composition that forms an adhesive layer that is less likely to cause metal corrosion.

[0033] The electropenetrating adhesive layer 1 is an adhesive layer that has the property of decreasing adhesive strength when a voltage is applied. The electropenetrating adhesive layer 1 contains a polymer acting as an adhesive and an electrolyte, which is an ionic substance containing electrically charged molecules (ions). Ionic substances are a general term for substances composed of at least one pair of anions and cations. Regardless of their form, they refer to substances that ionize in a polymer, in a solution, in a liquid state, or in a solid state and exhibit electrical conductivity. Ionic substances at room temperature (25°C) can be in any state other than gas. That is, ionic substances may be solids, liquids, or intermediate states between solid and liquid (e.g., liquid crystals, viscous crystals, viscous solids, viscous liquids) at room temperature (25°C). The state of an ionic substance at room temperature (25°C) depends on its molecular structure. For example, ionic liquids are compounds composed of cations and anions that have a melting point below room temperature (25°C) and are liquid at room temperature, such as 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Ionic solids are substances that have an ionic property and a melting point above 25°C, such as metal salts (e.g., sodium chloride and copper sulfate) and high-melting-point organic ionic solids (e.g., 1-ethyl-3-methylimidazolium bromide and 1-ethyl-1-methylpiperidinium iodide).

[0034] The electropenetrating adhesive layer 1 can be formed from an electropenetrating adhesive composition containing a polymer and an electrolyte. The following describes electropenetrating adhesive compositions, including those according to embodiments of the present invention.

[0035] In this specification, the adhesive strength when no voltage is applied may be referred to as "initial adhesive strength." Furthermore, among the components contained in electrolytic adhesive compositions, compositions consisting of components other than ionic substances, which are electrolytes, are sometimes called "ionic substance-free adhesive compositions." Furthermore, an adhesive layer formed by an adhesive composition that does not contain ionic substances is sometimes referred to as an "ionic substance-free adhesive layer." Furthermore, the property of adhesive strength decreasing when voltage is applied is called "electrodeposition," and a large decrease in adhesive strength due to voltage application is sometimes described as "excellent electrodeposition."

[0036] [Components of the adhesive composition] The adhesive composition according to an embodiment of the present invention comprises a polymer and an electrolyte.

[0037] (polymer) The adhesive composition according to an embodiment of the present invention 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 polymer or partial polymer of monomers. 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 portion of the monomer or monomer mixture is partially polymerized.

[0038] 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 acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluoropolymers, and epoxy polymers. The polymers can be used alone or in combination of two or more types. In order to increase the dielectric constant of components other than ionic substances in the resulting electropenetrating adhesive layer and improve electropenetration, it is preferable that the polymer has a high dielectric constant. From this viewpoint, it is particularly preferable that the polymer in this embodiment includes at least one selected from the group consisting of polyester polymers and acrylic polymers having carboxyl groups and / or hydroxyl groups. Since polyester polymers have hydroxyl groups at their ends that are easily polarized, and since acrylic polymers having carboxyl groups and / or hydroxyl groups have carboxyl groups and / or hydroxyl groups that are easily polarized, using these polymers makes it possible to obtain a polymer with a relatively high dielectric constant. The total content of polyester polymers and acrylic polymers having carboxyl groups and / or hydroxyl groups in the polymer according to the embodiment of the present invention is preferably 60% by mass or more, and more preferably 80% by mass or more. Furthermore, in order to increase cost, productivity, and initial adhesive strength, the polymer in this embodiment is preferably an acrylic polymer. In other words, the adhesive composition according to the embodiment of the present invention is preferably an acrylic electropenetrating adhesive composition containing an acrylic polymer as the polymer. Furthermore, from the viewpoint of easily forming an adhesive layer with a large HSP distance between the cation reducer and the polymer, and easily achieving an adhesive layer with an adhesive strength recovery rate of less than 60% after 2 minutes, the polymer in this embodiment is preferably a polyester polymer. Furthermore, from the viewpoint of realizing an adhesive with excellent electropenetration properties under low voltage conditions, and / or from the viewpoint of facilitating the realization of an adhesive with excellent repeatability of electropenetration, the polymer in this embodiment is preferably a polyester polymer. In this specification, low voltage refers to, for example, a voltage of 5V or less or 2V or less. That is, the adhesive composition according to the embodiment of the present invention is preferably a polyester electropenetrating adhesive composition containing a polyester polymer as the polymer.

[0039] In this specification, "acrylic polymer" refers to a polymer that includes monomer units derived from monomers having at least one (meth)acryloyl group in one molecule as monomer units constituting the polymer. Hereinafter, monomers having at least one (meth)acryloyl group in one molecule will also be referred to as "acrylic monomers." Therefore, in this specification, an acrylic polymer is defined as a polymer that includes monomer units derived from acrylic monomers. Here, a monomer unit refers to a monomer-derived constituent unit in a polymer. A typical example of an acrylic polymer is a polymer in which the proportion of acrylic monomers among the total monomers used in the synthesis of the acrylic polymer is more than 50% by mass (preferably more than 70% by mass, for example more than 90% by mass). Furthermore, in this specification, "(meth)acryloyl" comprehensively refers to acryloyl and methacryloyl. Similarly, "(meth)acrylate" comprehensively refers to acrylate and methacrylate, and "(meth)acrylic" comprehensively refers to acrylic and methacrylic. Therefore, the concept of acrylic monomer as used herein may encompass both monomers having an acryloyl group (acrylic monomers) and monomers having a methacryloyl group (methacrylic monomers).

[0040] The acrylic polymer preferably contains monomer units derived from alkyl (meth)acrylate esters having an alkyl group with 1 to 14 carbon atoms (formula (1) below). Such monomer units are suitable for obtaining high initial adhesion. Furthermore, to increase the dielectric constant of components other than ionic substances in the electropenetrating adhesive layer and improve electropenetration, the alkyl group R in formula (1) below is preferable. b The number of carbon atoms is preferably small, particularly preferably 8 or less, and more preferably 4 or less. CH2=C(R a )COOR b (1) [R in equation (1)] a R is a hydrogen atom or a methyl group, b [This is an alkyl group having 1 to 14 carbon atoms, which may have substituents, or a cyclic hydrocarbon group, which may have substituents.]

[0041] Examples of alkyl (meth)acrylate esters having an alkyl group with 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, and 2-ethylbutyl (meth)acrylate. Examples include lylate, 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, n-tetradecyl(meth)acrylate, and 2-methoxyethyl acrylate. Among these, n-butyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, and 2-methoxyethyl acrylate are preferred. Alkyl (meth)acrylate esters having an alkyl group with 1 to 14 carbon atoms can be used alone or in combination of two or more.

[0042] The proportion of alkyl (meth)acrylate ester having an alkyl group with 1 to 14 carbon atoms relative to the total monomer components (100% by mass) constituting the acrylic polymer is not particularly limited, but is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more. When the proportion of alkyl (meth)acrylate ester having an alkyl group with 1 to 14 carbon atoms is 70% by mass or more, it is easier to obtain a large initial adhesive strength.

[0043] The cyclic hydrocarbon group may be either an aromatic ring or a non-aromatic ring, and is not particularly limited. Examples of aromatic rings include aromatic carbocyclic rings [e.g., monocyclic carbocyclic rings such as benzene rings, and condensed carbocyclic rings such as naphthalene rings], and various aromatic heterocyclic rings. Examples of non-aromatic rings include non-aromatic aliphatic rings (non-aromatic alicyclic rings) [e.g., cycloalkane rings such as cyclopentane rings, cyclohexane rings, cycloheptane rings, and cyclooctane rings; cycloalkene rings such as cyclohexene rings], non-aromatic bridged rings [e.g., bicyclic hydrocarbon rings in pinane, pinene, bornane, norbornane, norbornene, etc.; triplicate or more aliphatic hydrocarbon rings (bridged hydrocarbon rings) in adamantane, etc.], and non-aromatic heterocyclic rings [e.g., epoxy rings, oxolane rings, oxetane rings, etc.].

[0044] Examples of (meth)acrylic acid esters having the above-mentioned cyclic hydrocarbon group include cycloalkyl (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-A Examples include (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings, such as damantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate; and (meth)acrylic acid esters having aromatic rings, such as aryl (meth)acrylates like phenyl (meth)acrylate, aryloxyalkyl (meth)acrylates like phenoxyethyl (meth)acrylate, and arylalkyl (meth)acrylates like benzyl (meth)acrylate. (Meth)acrylic acid esters having cyclic hydrocarbon groups may be used alone or in combination of two or more.

[0045] As an acrylic polymer, it is preferable to include monomer units derived from alkyl (meth)acrylate esters having alkyl groups with 1 to 14 carbon atoms, as well as monomer units derived from polar group-containing monomers copolymerizable with the alkyl groups, for the purpose of modifying cohesive strength, heat resistance, crosslinkability, etc. Such monomer units can provide crosslinking sites and are suitable for obtaining high initial adhesion. Furthermore, from the viewpoint of increasing the dielectric constant of components other than ionic substances in the electropenetrating adhesive layer and improving electropenetration, it is also preferable to include monomer units derived from polar group-containing monomers.

[0046] Examples of polar group-containing monomers include carboxyl group-containing monomers, hydroxyl group-containing monomers, cyano group-containing monomers, vinyl group-containing monomers, aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, vinyl ether monomers, N-acryloylmorpholine, sulfo group-containing monomers, phosphate group-containing monomers, and acid anhydride group-containing monomers. Among these, carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers are preferred due to their excellent cohesiveness, and carboxyl group-containing monomers are particularly preferred. Carboxyl group-containing monomers are especially suitable for obtaining high initial adhesion. Polar group-containing monomers can be used alone or in combination of two or more types.

[0047] Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Acrylic acid is particularly preferred. Carboxyl group-containing monomers can be used alone or in combination of two or more.

[0048] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, N-methylol (meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are particularly preferred. Hydroxyl group-containing monomers can be used individually or in combination of two or more.

[0049] Examples of amide group-containing monomers include (meth)acrylamide, N-vinylpyrrolidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and diacetoneacrylamide. Amide group-containing monomers can be used alone or in combination of two or more.

[0050] Examples of cyano group-containing monomers include acrylonitrile and methacrylonitrile.

[0051] Examples of vinyl group-containing monomers include vinyl acetate, vinyl propionate, and vinyl esters such as vinyl laurate, with vinyl acetate being particularly preferred.

[0052] Examples of aromatic vinyl monomers include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

[0053] Examples of imide group-containing monomers include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

[0054] Examples of amino group-containing monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate.

[0055] Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether.

[0056] Examples of vinyl ether monomers include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

[0057] The proportion of polar group-containing monomers to the total monomer components (100% by mass) constituting the acrylic polymer is preferably 0.1% by mass or more and 35% by mass or less. The upper limit of the proportion of polar group-containing monomers is more preferably 25% by mass, even more preferably 20% by mass, the lower limit is more preferably 0.5% by mass, even more preferably 1% by mass, and particularly preferably 2% by mass. When the proportion of polar group-containing monomers is 0.1% by mass or more, cohesive force is easily obtained, so adhesive residue is less likely to occur on the surface of the adherend after peeling off the electrorelease adhesive layer, and electrorelease properties are improved. Furthermore, when the proportion of polar group-containing monomers is 35% by mass or less, it becomes easier to prevent the electrorelease adhesive layer from adhering excessively to the adherend and causing excessive peeling. In particular, when it is 2% by mass or more and 20% by mass or less, it becomes easier to achieve both peelability to the adherend and adhesion between the electrorelease adhesive layer and the conductive layer. Preferably, a carboxyl group-containing monomer is used as the polar group-containing monomer. For example, in embodiments using acrylic acid, the acrylic acid content relative to the total monomer components (100% by mass) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, from the viewpoint of improving the cohesiveness of the adhesive. Furthermore, from the viewpoint of reducing the HSP distance between the polymer and the cation reducer described later, and facilitating improvement of electropenetration, it is preferably 5% by mass or less, more preferably 4% by mass or less, and may even be 3% by mass or less. The polar group-containing monomer constituting the acrylic polymer does not necessarily have to contain acrylic acid substantially.

[0058] Furthermore, the monomer components constituting the acrylic polymer may include polyfunctional monomers in order to introduce a cross-linked structure into the acrylic polymer and facilitate obtaining the necessary cohesive force.

[0059] Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinylbenzene, and N,N'-methylenebisacrylamide. Polyfunctional monomers can be used individually or in combination of two or more.

[0060] The content of polyfunctional monomers relative to the total monomer components (100% by mass) constituting the acrylic polymer is preferably 0.1% by mass or more and 15% by mass or less. The upper limit of the polyfunctional monomer content is more preferably 10% by mass, and the lower limit is more preferably 3% by mass. In embodiments where greater emphasis is placed on adhesive strength, the content of polyfunctional monomers is preferably 0.1 to 2 parts by mass, preferably 0.11 to 1 part by mass, and preferably 0.12 to 0.8 parts by mass. A polyfunctional monomer content of 0.1% by mass or more is preferable because it tends to improve the flexibility and adhesion of the electro-peelable adhesive layer. A polyfunctional monomer content of 15% by mass or less makes it easier to obtain appropriate adhesion without the cohesive force becoming too high.

[0061] Furthermore, in other embodiments, the acrylic polymer may include monomer units derived from alkyl (meth)acrylate esters having C1 to C14 alkyl groups, monomer units derived from polar group-containing monomers, and monomer units derived from at least one monomer selected from cyclic nitrogen-containing monomers and alicyclic structure-containing monomers. Cyclic nitrogen-containing monomers and alicyclic structure-containing monomers are preferred from the viewpoint of improving the repeatability of electrolysis at 10V30s, for example, because their homopolymers have a high Tg. The Tg of the homopolymers of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers is preferably 0 to 200°C, more preferably 5 to 180°C, and more preferably 10 to 160°C.

[0062] The cyclic nitrogen-containing monomers can be any monomer that has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure, without any particular limitations. The cyclic nitrogen structure is preferably one in which a nitrogen atom is contained within the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; and vinyl monomers having nitrogen-containing heterocycles such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. In addition, (meth)acrylic monomers containing heterocycles such as morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings can be used. Specifically, examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among the cyclic nitrogen-containing monomers, N-acryloylmorpholine is preferred. The cyclic nitrogen-containing monomers may be used alone or in combination of two or more.

[0063] The above-mentioned monomers containing the alicyclic structure can be any monomer having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and having an alicyclic structure, without any particular limitations. The alicyclic structure is a cyclic hydrocarbon structure, and is preferably a high-Tg monomer in which the glass transition temperature of the homopolymer is 10°C or higher, for example, from the viewpoint of improving the repeatability of electrolysis at 10V30s. Examples of monomers containing an alicyclic structure include (meth)acrylic monomers such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl acrylate (Tg: 15°C), cyclohexyl methacrylate (Tg: 66°C), cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl acrylate (Tg: 97°C), isobornyl methacrylate (Tg: 180°C), dicyclopentanyl acrylate (Tg: 120°C), and dicyclohexyl methacrylate (Tg: 175°C). Among these, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and cyclohexyl (meth)acrylate are preferred. The monomers containing an alicyclic structure may be used alone or in combination of two or more.

[0064] The ratio of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers to the total monomer components (100% by mass) constituting the acrylic polymer is preferably 10% by mass or more and 30% by mass or less, for example, from the viewpoint of improving the repeatability of electrolysis at 10V30s. The upper limit of the ratio of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers is more preferably 28% by mass, even more preferably 25% by mass, and may also be 23% by mass or 20% by mass. The lower limit of the ratio of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers is more preferably 12% by mass, even more preferably 15% by mass or 17% by mass. When the ratio of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers is 10% by mass or more, it is easier to realize an adhesive with better repeatability of electrolysis at 10V30s, for example. Furthermore, when the ratio of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers is 30% by mass or less, the flexibility of the adhesive is increased, and it is easier to realize an adhesive with good initial adhesion. In particular, if the ratio of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers to the total monomer components (100% by mass) constituting the acrylic polymer is 15% by mass or more and 25% by mass or less, it becomes easier to achieve both excellent repeatability of electrolysis at 10V30s and good initial adhesion.

[0065] Polyester polymers are typically polymers having a structure in which polycarboxylic acids such as dicarboxylic acids or their derivatives (hereinafter also referred to as "polycarboxylic acid monomers") and polyhydric alcohols such as diols or their derivatives (hereinafter referred to as "polyhydric alcohol monomers") are condensed together.

[0066] As the polyvalent carboxylic acid monomer, a dicarboxylic acid is preferred from the viewpoint of achieving a good balance between flexibility and cohesiveness in the electropenetrating adhesive layer. The dicarboxylic acid is not particularly limited, but any of aliphatic dicarboxylic acids, dimer acids, alicyclic dicarboxylic acids, unsaturated dicarboxylic acids, or aromatic dicarboxylic acids can be used. Specific examples of dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, succinic acid, dodecanediic acid, and sebacic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 4-methyl-1,2-cyclohexanedicarboxylic acid; unsaturated dicarboxylic acids such as dodecenyl succinic anhydride, maleic acid, maleic anhydride, itaconic acid, citraconic acid, and fumaric acid; alicyclic dicarboxylic acids such as hexahydrophthalic anhydride and tetrahydrophthalic 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 such as carboxylates, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters. These dicarboxylic acids can be used individually or in combination of two or more. Furthermore, in addition to the dicarboxylic acid component, 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, trimer acid, etc.) can also be used. The polycarboxylic acids containing three or four or more carboxyl groups can be used individually or in combination of two or more. In this embodiment, the proportion of the polycarboxylic acid containing three or four or more carboxyl groups is appropriately less than 10 mol%, for example, less than 3 mol%, less than 1 mol%, or less than 0.1 mol% in the monomer component of the polyester polymer. The polyester polymer in this embodiment can preferably be implemented in a manner in which the monomer component substantially does not contain the other copolymer components mentioned above. Polycarboxylic acid monomers can be used individually or in combination of two or more types.

[0067] In some embodiments, the dicarboxylic acid preferably includes an aliphatic dicarboxylic acid from the viewpoint of improving the flexibility of the adhesive, adjusting the initial adhesive strength, and / or improving electropenetration at low voltage, and / or improving the repeatability of electropenetration under low voltage conditions. That is, a polyester polymer containing an aliphatic dicarboxylic acid as a monomer unit is preferred. Examples of aliphatic dicarboxylic acids include adipic acid, azelaic acid, succinic acid, dodecanedioic acid, and sebacic acid, with adipic acid and sebacic acid being preferred. The aliphatic dicarboxylic acid can be used alone or in combination of two or more.

[0068] The proportion of aliphatic dicarboxylic acid in the total amount (total number of moles) of dicarboxylic acid as a monomer component of a polyester polymer can be set to realize an adhesive that achieves both the desired initial adhesion and electrorelease properties. In some embodiments, the proportion of aliphatic dicarboxylic acid in the total amount (total number of moles) of dicarboxylic acid may be 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 60 mol% or more.

[0069] In some embodiments, from the viewpoint of facilitating the realization of an adhesive having high initial adhesion and / or excellent electropenetration properties under low voltage conditions, and / or an adhesive having excellent repeatability of electropenetration under low voltage conditions, it is advantageous for the proportion of aliphatic dicarboxylic acid in the total amount (total number of moles) of dicarboxylic acid as a monomer component of the polyester polymer to be greater than 60 mol%, preferably 65 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and may also be 80 mol% or more, or 90 mol% or more. Substantially 100 mol% of the total amount (total number of moles) of the above dicarboxylic acid may be aliphatic dicarboxylic acid.

[0070] Furthermore, in some embodiments, from the viewpoint of facilitating the realization of an adhesive having better repeatability of electrolysis at, for example, 10V30s, it is advantageous for the proportion of aliphatic dicarboxylic acid in the total amount (total number of moles) of the dicarboxylic acid to be less than 60 mol%, preferably 55 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less, even more preferably 35 mol% or less, particularly preferably 30 mol% or less, and may be 25 mol% or more, 20 mol% or less, 10 mol% or less, 5 mol% or less, or less than 1 mol%. Although the practical use of aliphatic dicarboxylic acids is not required, from the viewpoint of achieving a good balance between good initial adhesion and excellent repeatability of electrolysis, for example at 10V30s, the proportion of aliphatic dicarboxylic acids in the total amount (total number of moles) of the above-mentioned dicarboxylic acids is preferably 10 mol% to 55 mol%, more preferably 15 mol% to 55 mol%, even more preferably 20 mol% to 50 mol%, even more preferably 25 mol% to 50 mol%, and may also be 30 mol% to 50 mol%.

[0071] In some embodiments, the dicarboxylic acid is preferably an aromatic dicarboxylic acid, for example, from the viewpoint of improving the repeatability of electrolysis at 10V30s. That is, a polyester polymer containing an aromatic dicarboxylic acid as a monomer unit is preferred. Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, orthophthalic acid, benzylmalonic acid, 2,2'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-dicarboxydiphenyl ether, naphthalenedicarboxylic acid, etc., and isophthalic acid and terephthalic acid can be preferably used. Aromatic dicarboxylic acids can be used individually or in combination of two or more.

[0072] The proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of dicarboxylic acid in the monomer component of a polyester polymer can be set to achieve an adhesive that balances the desired initial adhesion and electropenetration properties. The proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of dicarboxylic acid may be 1 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, or 40 mol% or more.

[0073] In some embodiments, from the viewpoint of facilitating the realization of an adhesive having better repeatability of electrolysis at, for example, 10V30s, the proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of the dicarboxylic acid is preferably 45 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, even more preferably 65 mol% or more, particularly preferably 70 mol% or more, may be 75 mol% or more, may be 80 mol% or more, may be 90 mol% or more, or may be 95 mol% or more. The proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of the above-mentioned dicarboxylic acid may be 100 mol%, but from the viewpoint of achieving a good balance between good initial adhesion and electropenetration, it is advantageous to have the proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of the above-mentioned dicarboxylic acid be less than 100 mol%, preferably 90 mol% or less, preferably 85 mol% or less, may also be 60 mol% or less, may also be 40 mol% or less, may also be 30 mol% or less, may also be 20 mol% or less, may also be 10 mol% or less, and may even be less than 1 mol%. The use of aromatic dicarboxylic acid may be substantially negligible. In some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and excellent repeatability of electrolysis, for example at 10V30s, the proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of the dicarboxylic acid is advantageous to be greater than 40 mol% and 90 mol% or less, preferably 45 mol% or more and 90 mol% or less, more preferably 50 mol% or more and 90 mol% or less, and even more preferably 50 mol% or more and 85 mol% or less. Furthermore, in some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and excellent electropenetration under low voltage conditions, the proportion of aromatic dicarboxylic acid in the total amount (total number of moles) of the above-mentioned dicarboxylic acid is preferably 35 mol% or less, more preferably 30 mol% or less, even more preferably 25 mol% or less, may be 20 mol% or less, may be 10 mol% or less, or may be less than 1 mol%. Aromatic dicarboxylic acid may be substantially omitted.

[0074] As for the polyhydric alcohol monomer, a diol is preferred from the viewpoint of achieving a good balance between flexibility and cohesiveness in the electrorelease adhesive layer. The diol is not particularly limited, but any of (poly)alkylene glycols, aliphatic diols, dimer diols, alicyclic diols, aromatic diols, or unsaturated diols can be used. Specific examples of diols include (poly)alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, and polytetramethylene glycol; 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, 1,6-hexanediol, 2-methyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1, Aliphatic diols such as 6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyloctane-1,8-diol, and 1,10-decanediol; dimerols (such as dimerols 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 the like can be used. In addition to the diol component, other polyhydric alcohol monomers with a trivalent or higher valency can also be used, such as pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, adamantanetriol, etc. These polyhydric alcohol monomers with a trivalent or higher valency can be used individually or in combination of two or more. In this embodiment, the proportion of these polyhydric alcohol monomers with a trivalent or higher valency is appropriately set to, for example, 10 mol% or less in the monomer components of the polyester polymer, but may also be 6 mol% or less, 3 mol% or less, 1 mol% or less, or 0.1 mol% or less. The polyhydric alcohol monomers can be used individually or in combination of two or more.

[0075] In some embodiments, the diol is preferably selected from the group consisting of (poly)alkylene glycols, aliphatic diols, and alicyclic diols, with aliphatic diols being more preferred, in terms of excellent reactivity. That is, polyester polymers containing aliphatic diols as monomer units are preferred. Examples of aliphatic diols include 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, 1,6-hexanediol, 2-methyl-1,3-hexanediol, 3- Examples include methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyloctane-1,8-diol, and 1,10-decanediol. 1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,4-butanediol, and 1,6-hexanediol can be preferably used. Aliphatic diols can be used individually or in combination of two or more. By synthesizing these diols (preferably aliphatic diols) in combination with the dicarboxylic acids mentioned above, adhesives with good initial adhesion and excellent electrorelease properties can be preferably obtained.

[0076] The proportion of (poly)alkylene glycols, aliphatic diols, and alicyclic diols (preferably the proportion of aliphatic diols) in the total amount (total number of moles) of diols in the monomer components of the polyester polymer is appropriately set to, for example, 50 mol% or more. From the viewpoint of obtaining good initial adhesion, 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 some other embodiments, the proportion of (poly)alkylene glycols, aliphatic diols, and alicyclic diols (preferably the proportion of aliphatic diols) may be, for example, 95 mol% or less.

[0077] The aforementioned polyester polymer is typically a polymer having a structure in which a polyvalent carboxylic acid monomer and a polyvalent alcohol monomer are condensed, but it may also contain monomer units derived from cyclic ester monomers.

[0078] Examples of the cyclic ester monomers include lactide, β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-hexanolactone, γ-octanolactone, δ-valerolactone, δ-hexalanolactone, δ-octanolactone, ε-caprolactone, δ-dodecanolactone, α-methyl-γ-butyrolactone, β-methyl-δ-valerolactone, glycolide, lactide, and other aliphatic lactones. One or more of these cyclic ester monomers can be used.

[0079] When monomer units derived from cyclic ester monomers are included, the content of cyclic ester monomers is preferably less than 40 mol%, more preferably less than 20 mol%, and more preferably less than 10 mol%, relative to the total monomer components (100 mol%) constituting the polyester polymer. In some embodiments, polyester polymers substantially free of cyclic ester monomers may be preferably used. "Substantially free" means that the amount of cyclic ester monomers in the total monomer components constituting the polymer is less than 1 mol%, preferably less than 0.1 mol% (for example, 0 mol% or more and less than 0.01 mol%). Such an electrorelease adhesive layer does not undergo thermal decomposition or hydrolysis originating from the monomer units, thereby improving the storage stability of the electrorelease adhesive layer.

[0080] In the monomer components used in the synthesis of polyester polymers, there are no particular limitations, but the total proportion of dicarboxylic acid and diol is preferably 90 mol% or more. From the viewpoint of achieving a good balance between good initial adhesion and excellent electropenetration, it is preferably 95 mol% or more, more preferably 97 mol% or more, and even more preferably 99 mol% or more (for example, 99 to 100 mol%). From the viewpoint of easily forming an adhesive layer with a large HSP distance between the cation reducer and the polymer, and easily realizing an adhesive layer with an adhesion recovery rate of less than 60% after 2 minutes, this embodiment is preferably carried out using a polyester polymer synthesized substantially from dicarboxylic acid and diol.

[0081] In some embodiments, the polyester polymer preferably has a limited content of aromatic rings within its polymer molecule, from the viewpoint of making it easier to realize an adhesive that achieves both desired initial adhesion and electropeelability. In some embodiments, from the viewpoint of obtaining initial adhesion and electropeelability above predetermined values, the copolymerization ratio of aromatic ring-containing monomers (typically aromatic dicarboxylic acids and aromatic diols) in the polyester polymer is preferably 90 mol% or less, more preferably 75 mol% or less, even more preferably 60 mol% or less, even more preferably 50 mol% or less, even more preferably 45 mol% or less, and may also be 40 mol% or less or 30 mol% or less. In some embodiments that emphasize excellent electropenetration properties under low voltage conditions, the copolymerization ratio of aromatic ring-containing monomers (typically aromatic dicarboxylic acids and aromatic diols) in the above polymer is preferably less than 20 mol%, preferably 18 mol% or less, more preferably 16 mol% or less, even more preferably 14 mol% or less, may be 12 mol% or less, may be 10 mol% or less, or may be less than 1 mol%. Although aromatic ring-containing monomers do not necessarily have to be used, in some embodiments where the repeatability of electrolysis at, for example, 10V30s is important, the copolymerization ratio of aromatic ring-containing monomers (typically aromatic dicarboxylic acids, aromatic diols) in the above polymer is preferably greater than 20 mol%, more preferably 23 mol% or more, even more preferably 25 mol% or more, even more preferably 30 mol% or more, particularly preferably 35 mol% or more, and may be 40 mol% or more, or 50 mol% or more. In some embodiments, from the viewpoint of achieving a good balance between initial adhesion and the repeatability of electrolysis at, for example, 10V30s, the copolymerization ratio of aromatic ring-containing monomers (typically aromatic dicarboxylic acids, aromatic diols) in the above polymer is preferably greater than 20 mol% and 50 mol% or less, more preferably 23 mol% or more and 45 mol% or less, and even more preferably 25 mol% or more and 45 mol% or less.

[0082] 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 blended 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 blending 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 to adjust the cohesive force. When using polycarboxylic acids containing three or four or more carboxyl groups and / or polyhydric alcohols containing three or four or more hydroxyl groups, the above preferred equivalent can be appropriately adjusted depending on the valency of the polycarboxylic acid and / or polyhydric alcohol used.

[0083] Furthermore, the polymer according to the embodiment of the present invention may also contain an ionic polymer. An ionic polymer is a polymer having an ionic functional group. The inclusion of an ionic polymer in the polymer increases the dielectric constant of the polymer and improves its electrolytic properties. 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 per 100 parts by mass of the polymer.

[0084] 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). In particular, from the viewpoint of cost and productivity, solution polymerization or photopolymerization (active energy ray polymerization) is preferred. Polyester polymers can be obtained by polycondensation of a polycarboxylic acid and a polyhydric alcohol, similar to general polyesters. More specifically, polyester polymers can be synthesized by carrying out the reaction between the carboxyl group of the polycarboxylic acid and the hydroxyl group of the polyhydric alcohol, while removing the water (product water) etc. generated by the above reaction from the reaction system. Methods for removing the above-mentioned water from the reaction system include blowing an inert gas into the reaction system and removing the water from the reaction system together with the inert gas, azeotropic dehydration using a reaction water discharge solvent such as toluene or xylene, and distillation of the water from the reaction system under reduced pressure (reduced pressure method). When polymerized, the polymer can be any type, such as a random copolymer, block copolymer, alternating copolymer, or graft copolymer.

[0085] 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.

[0086] 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 individually or in combination of two or more.

[0087] 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.

[0088] 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'-dimethyleneisobutylamidine)hydrochloride, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate. Polymerization initiators can be used alone or in combination of two or more.

[0089] The amount of polymerization initiator used is not particularly limited, but it 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.

[0090] In solution polymerization, the heating temperature during polymerization is not particularly limited, but is, for example, between 50°C and 80°C. The heating time is not particularly limited, but is, for example, between 1 hour and 24 hours.

[0091] Photopolymerization methods include UV polymerization, which is carried out by irradiating with light such as ultraviolet (UV) rays (typically carried out in the presence of a photopolymerization initiator), and radiation polymerization, which is carried out by irradiating with radiation such as beta rays and gamma rays. From the viewpoint of productivity, UV polymerization is preferred. UV polymerization will be described below.

[0092] When performing UV polymerization, it is preferable to include a photopolymerization initiator in the monomer component due to the advantage of being able to shorten the polymerization time. In this embodiment, the specific (meth)acrylic polymer can also be prepared as a partially polymerized monomer (prepolymer) by irradiating a mixture of the monomer component and the photopolymerization initiator with UV light. An adhesive composition can also be prepared by mixing the prepolymer with an electrolyte described later, and optionally with a polyfunctional monomer, other additives, etc., and this adhesive composition can be applied to a predetermined substrate and the polymerization can be completed by irradiating with UV light.

[0093] While not particularly limited, the following can be used as photopolymerization initiators: benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc. The polymerization initiators can be used alone or in combination of two or more types. Specifically, examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name "Omnirad651," manufactured by IGM Resins BV), anisoin methyl ether, and the like. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone (trade name "Omnirad184", manufactured by IGM Resins BV), 4-phenoxydichloroacetophenone, and 4-t-butyldichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-hydroxy-2-methylpropan-1-one. Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of benzoin-based photopolymerization initiators include benzoin. Examples of benzyl-based photopolymerization initiators include benzyl. Benzophenone-based photopolymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Ketal-based photopolymerization initiators include benzyldimethyl ketal, among others. Thioxanthone-based photopolymerization initiators include, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Acyl phosphine oxide-based photopolymerization initiators include, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0094] The amount of photopolymerization initiator used is not particularly limited, but it is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to the total monomer components (100 parts by mass) constituting the acrylic polymer. The upper limit of the amount of photopolymerization initiator used is more preferably 3 parts by mass, and the lower limit is more preferably 0.05 parts by mass.

[0095] The polymerization rate of the prepolymer is not particularly limited, but from the viewpoint of achieving a viscosity suitable for application to a substrate, 3 to 50% by mass is preferred, and 5 to 40% by mass is more preferred. The polymerization rate of the prepolymer can be adjusted to a desired range by adjusting the type and amount of photopolymerization initiator used, the irradiation intensity and irradiation time of active light such as UV light, etc. The polymerization rate of the prepolymer is calculated from the mass before and after heating at 130°C for 3 hours using the following formula. The polymerization rate of the adhesive layer is calculated using the same method. The polymerization rate of the adhesive layer is not particularly limited, but from the viewpoint of reducing monomer odor, 80 to 100% by mass is preferred, 90 to 100% by mass is more preferred, and 95 to 100% by mass is most preferred. The polymerization rate of the adhesive layer can be adjusted to a desired range by adjusting the type and amount of photopolymerization initiator used, the irradiation intensity and irradiation time of active light such as UV light, etc. Polymerization rate (%) = Mass after drying / Mass before drying × 100

[0096] The reaction temperature, reaction time, and degree of reduced pressure (pressure in the reaction system) when using a reduced pressure method to obtain polyester polymers by polycondensation of polycarboxylic acids and polyhydric alcohols (including esterification and polycondensation) can be appropriately set to efficiently obtain polyester polymers with the desired properties (e.g., molecular weight). 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 using 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 keeping the pressure within the reaction system within the above range, the water produced by the reaction can be efficiently distilled off the system, making it easier to maintain a good reaction rate. Furthermore, when the reaction temperature is relatively high, keeping the pressure within the reaction system above the lower limit makes it easier to prevent the distillation off of the starting materials, such as polycarboxylic acids and polyhydric alcohols. From the viewpoint of maintaining stable pressure within the reaction system, it is usually appropriate to keep the pressure within the reaction system at 0.1 kPa or higher.

[0097] 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.

[0098] In the above process of synthesizing a polyester polymer by reaction of a polycarboxylic acid and a polyhydric alcohol, a solvent may or may not be used. The above synthesis can be carried out without substantially using organic solvents (for example, by excluding the intentional use of organic solvents as reaction solvents in the above reaction). Synthesizing a polyester polymer without substantially using 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.

[0099] 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.

[0100] The weight-average molecular weight of the polymer is not particularly limited, but is preferably between 50,000 and 5,000,000, and more 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 50,000 or more, and more preferably 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 electrorelease adhesive layer is 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 electrorelease adhesive layer is peeled off.

[0101] The weight-average molecular weight was obtained by measuring using gel permeation chromatography (GPC). More specifically, for example, it can be measured using the "HLC-8220GPC" (manufactured by Tosoh Corporation) GPC measuring device under the following conditions and calculated using the standard polystyrene equivalent value. (Weight average molecular weight measurement conditions) • Sample concentration: 0.2% by mass (tetrahydrofuran solution) • Sample injection volume: 10 μL • Sample column: TSKguard column SuperHZ-H (1 tube) + TSKgel SuperHZM-H (2 tubes) • Reference column: TSKgel SuperH-RC (1 tube) • Eluent: Tetrahydrofuran (THF) ·Flow rate: 0.6mL / min • Detector: Differential refractometer (RI) Column temperature (measurement temperature): 40°C • Standard sample: Polystyrene (manufactured by Agilent)

[0102] In embodiments where the polymer is a polyester polymer, the weight-average molecular weight (Mw) of the polymer is not particularly limited and may be in the range of 80,000 to 200,000 from the viewpoint of easily obtaining an adhesive layer with high cohesive strength. In a preferred embodiment, the Mw of the polyester polymer can be 100,000 or more (e.g., greater than 100,000), may be 110,000 or more, or may be 115,000 or more. By using a high molecular weight polyester polymer in this way, even with an adhesive composition that tends to have low viscosity due to containing a predetermined amount or more of tackifying resin, for example, it is easy to obtain an appropriate viscosity and easily form a thin adhesive layer of good quality. Such an adhesive composition does not need to be excessively concentrated, and even if it is a composition containing a crosslinking agent, it tends to have a sufficient pot life and is easy to handle. From the viewpoint of easily obtaining good initial adhesion, the Mw of the polyester polymer is preferably 115,000 to 150,000, and more preferably 115,000 to 140,000.

[0103] The weight-average molecular weight of polyester polymers is obtained by measuring using gel permeation chromatography (GPC). More specifically, for example, it can be measured using the "TSKgel GMH-H(S)" (manufactured by Tosoh Corporation) GPC measuring device under the following conditions and calculated using the standard polystyrene equivalent value. (Measurement conditions for the weight-average molecular weight of polyester polymers) • Sample concentration: 0.2% by mass (tetrahydrofuran solution) • Sample injection volume: 100 μL • Sample column: TSKgel GMH-H(S) • Eluent: Contains tetrahydrofuran (THF) amine-based components. ·Flow rate: 0.5mL / min • Detector: Differential refractometer (RI) Column temperature (measurement temperature): 40°C • Standard sample: Polystyrene (manufactured by Agilent)

[0104] The glass transition temperature (Tg) of the polymer is not particularly limited, but it is preferably 0°C or lower because it suppresses the decrease in initial adhesive strength, more preferably -10°C or lower, and even more preferably -20°C or lower. Furthermore, it is particularly preferable to have a temperature of -40°C or lower because the rate of decrease in adhesive strength due to voltage application is particularly large, and most preferably -50°C or lower. Furthermore, the glass transition temperature (Tg) of the polymer may be -60°C or higher. In some embodiments where the polymer is an acrylic polymer, from the viewpoint of facilitating the realization of an adhesive with better repeatability of electrolysis, for example at 10V30s, the glass transition temperature (Tg) of the acrylic polymer is preferably -30°C or higher, more preferably -27°C or higher, and may be -25°C or higher. In some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and excellent repeatability of electrolysis, for example at 10V30s, the glass transition temperature (Tg) of the acrylic polymer is preferably -30°C or higher and -10°C or lower, and more preferably -30°C or higher and -15°C or lower.

[0105] In embodiments where the polymer is a polyester polymer, the glass transition temperature (Tg) of the polymer is appropriately 20°C or lower, preferably 17°C or lower, more preferably 10°C or lower, even more preferably 0°C or lower, and may also be -10°C or lower, -20°C or lower, -30°C or lower, or -40°C or lower. A low glass transition temperature (Tg) can be advantageous from the viewpoint of improving the initial adhesive strength of the adhesive layer. Furthermore, a glass transition temperature (Tg) of 0°C or lower is particularly preferable because the rate of decrease in adhesive strength due to voltage application is particularly large. In addition, from the viewpoint of the cohesive strength of the adhesive layer, the glass transition temperature (Tg) of the polyester polymer is appropriately -80°C or higher, and preferably -60°C or higher. In some embodiments, from the viewpoint of facilitating the realization of an adhesive having better repeatability of electrolysis at, for example, 10V30s, the glass transition temperature (Tg) of the polyester polymer is preferably -40°C or higher, more preferably -35°C or higher, may also be -30°C or higher, may be -20°C or higher, may be -10°C or higher, or may be 0°C or higher. In some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and high repeatability of electrolysis at 10V30s, the glass transition temperature (Tg) of the polyester polymer is preferably -40°C or higher and 20°C or lower, and more preferably -35°C or higher and 17°C or lower. Furthermore, in some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and high electropenetration under low voltage conditions, the glass transition temperature (Tg) of the polyester polymer is preferably -80°C or higher and less than -40°C, more preferably -60°C or higher and less than -40°C, and even more preferably -60°C or higher and less than -45°C. Furthermore, the glass transition temperature (Tg) of the adhesive layer formed from the electro-release adhesive composition is not particularly limited, but it is preferably 0°C or lower because it suppresses the decrease in initial adhesive strength, more preferably -10°C or lower, and even more preferably -20°C or lower. It is also particularly preferable to have a glass transition temperature of -40°C or lower because the rate of decrease in adhesive strength due to voltage application is particularly large, and most preferably -50°C or lower. Furthermore, from the viewpoint of the glass transition temperature (Tg) of the adhesive layer and the cohesive force of the adhesive layer, a temperature of -70°C or higher is appropriate, and a temperature of -60°C or higher is preferable. In some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and excellent electropenetration under low voltage conditions, the glass transition temperature (Tg) of the adhesive layer is preferably -60°C or higher and less than -40°C, and more preferably -55°C or higher and less than -45°C. Furthermore, in some embodiments, from the viewpoint of facilitating the realization of an adhesive having better repeatability of electrolysis, for example at 10V30s, the glass transition temperature (Tg) of the adhesive layer is preferably -35°C or higher, more preferably -30°C or higher, may also be -25°C or higher, may also be -20°C or higher, may also be -10°C or higher, may also be -7°C or higher, or may be -5°C or higher. In some embodiments, from the viewpoint of achieving a good balance between good initial adhesion and excellent repeatability of electrolysis, for example at 10V30s, the glass transition temperature (Tg) of the adhesive layer is preferably -35°C or higher and 0°C or lower, more preferably -30°C or higher and 0°C or lower, may also be -20°C or higher and 0°C or lower, or may also be -10°C or higher and 0°C or lower.

[0106] The glass transition temperature (Tg) is the value obtained by the following measurement method, as described later in the Examples. Specifically, a polymer solution is obtained by the synthesis method described in the Examples. Next, this polymer solution is cast onto a release liner and dried to prepare a test sample (sheet-like polymer) with a thickness of approximately 2 mm. When measuring the glass transition temperature (Tg) of the adhesive layer formed from the adhesive composition, an adhesive layer sample is prepared by the method described in the Examples section and used as the test sample. Then, approximately 3 to 10 mg of this test sample is weighed into an aluminum open cell, and the reversing heat flow (specific heat component) behavior of the polymer or adhesive layer 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, the temperature at the point where a line equidistant in the vertical direction from the line extending from the low-temperature and high-temperature baselines of the obtained Reversing Heat Flow intersects with the curve of the step-like change portion of the glass transition is defined as the glass transition temperature (Tg) of the polymer or adhesive layer. If two or more glass transition temperatures are observed, the one with the largest baseline shift (change in heat capacity before and after the glass transition) shall be adopted.

[0107] The polymer content in the adhesive composition according to the embodiment of the present invention 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.

[0108] (Electrolytes (ionic substances)) The adhesive composition according to the embodiment of the present invention contains an electrolyte. Furthermore, the adhesive composition according to the embodiment of the present invention may be an electropenetrating adhesive composition, and the ionic substance that is the electrolyte may be an ionic liquid. From the viewpoint of achieving good electropenetration, an ionic liquid is preferred as the electrolyte contained in the electropenetrating adhesive composition. Furthermore, in some embodiments, a material metal salt with a melting point higher than 25°C (such as sodium chloride or lithium bis(fluorosulfonyl)imide) may be preferably used that is substantially free of such salts. Here, "substantially free" means that the amount of metal salt in the adhesive layer formed from the adhesive composition is less than 1% by mass, preferably less than 0.1% by mass (for example, 0% by mass or more and less than 0.01% by mass). Such an electropenetrating adhesive layer does not leave any solid contaminants on the surface of the adherend after the electropenetrating adhesive layer has been peeled off by applying a voltage, thus making it easier to reuse the adherend after the adhesive layer has been peeled off.

[0109] Anions in ionic substances are, for example, (FSO2)2N - (CF3SO2)2N - , (CF3CF2SO2)2N - , (CF3SO2)3C - , B(CN)4 - , C(CN)3 - , N(CN)2 - , Br - AlCl4 - Al2Cl7 - NO3 - BF4 - PF6 - CH3COO - CF3COO - , CF3CF2CF2COO - CF3SO3 - CF3(CF2)3SO3 - AsF6 - SbF6 - , and F(HF) n - These are some examples. Among them, as an anion, (FSO2)2N - [Bis(fluorosulfonyl)imido anion] and (CF3SO2)2N -Anions of sulfonylime compounds, such as [bis(trifluoromethanesulfonyl)imide anion], are commonly used because they are chemically stable and suitable for providing good electrolytic properties. In other words, the anions of ionic substances are generally selected from the group consisting of bis(fluorosulfonyl)imide anions and bis(trifluoromethanesulfonyl)imide anions.

[0110] If the anion of an ionic substance contains a trifluoromethane group, it may be subject to regulations as an organofluorine compound (PFAS). For this reason, in some embodiments of the electrolytic adhesive compositions disclosed herein, it is preferable that the anion of the ionic substance does not contain a trifluoromethane group.

[0111] In some embodiments of the technology disclosed herein, the anion of the ionic substance may preferably be an anion having a Lewis basicity of 0.20 or less, or 0.27 to 0.60. By having an anion of the ionic substance contained in the electropenetrating adhesive composition have a Lewis basicity within a specific range, it is possible to preferably realize an electropenetrating adhesive composition that can form an electropenetrating adhesive layer that is less likely to cause metal corrosion even when placed in a high-temperature, high-humidity environment in contact with a metal.

[0112] Here, we will explain the corrosion mechanism. Although not bound by any particular theory, it is thought that corrosion products are produced when anions from ionic substances react with the base metal during the corrosion process of base metals. The following are examples of the processes by which corrosion products are generated: (1) to (3). (1) Anions from ionic substances destroy the oxide film (hereinafter also called the "passivation film") on the surface of base metals. (2) Oxidation reactions occur on the exposed base metal surface, generating base metal cations (at the same time, oxygen in the system accepts water and electrons, forming hydroxide ions (OH) - A reduction reaction occurs that produces (O2 + H2O + 2e - →2OH -)) (3) A base metal cation interacts with an anion of an ionic substance to form corrosion products (in this specification, "corrosion products" means a complex formed by the interaction of a base metal cation and an anion of an ionic substance).

[0113] According to our investigations, we have found that in a bonded body joined by an electropenetrating adhesive layer containing an ionic substance, the metal in contact with the electropenetrating adhesive layer corrodes when stored for a long period of time in a humid and hot environment, that is, the phenomenon of corrosion of the metal (described later) occurs, is influenced by the solubility of the corrosion products in the electropenetrating adhesive layer.

[0114] While not bound by any particular theory, if the corrosion products exhibit high solubility in the electropenetrating adhesive layer, it is thought that the corrosion products diffuse into the electropenetrating adhesive layer. Then, the above-described processes of corrosion product formation (2) to (3) occur repeatedly. As a result, corrosion products continue to be generated and accumulate, and are observed as corroded areas.

[0115] On the other hand, if the corrosion products exhibit low solubility in the electropenetrating adhesive layer, it is thought that the corrosion products do not diffuse into the electropenetrating adhesive layer but instead form a film on the base metal surface. This film protects the base metal surface and is not destroyed by anions from ionic substances. The above-described processes of corrosion product formation (2) to (3) do not occur repeatedly, and as a result, the formation of corrosion is not observed.

[0116] Corroded areas can be observed visually as changes in appearance such as loss of metallic luster or discoloration. Furthermore, in the aforementioned corrosion rate evaluation, these areas can be observed as dark-colored objects using computer software (Image J ver. 1.54d). On the other hand, areas where a passive film and a coating formed by corrosion products have formed retain their metallic luster. Moreover, these areas with the passive film and coating are not observed as dark-colored objects using computer software (Image J ver. 1.54d) in the aforementioned corrosion rate evaluation. A larger area of ​​corrosion, i.e., a higher corrosion rate, indicates a greater degree of metal corrosion. Furthermore, in a bonded structure using an electropenetrating adhesive layer, if the degree of corrosion of the conductive substrate or adherend is high, there is a risk that a stable voltage cannot be applied to the electropenetrating adhesive layer.

[0117] Further investigations by the present inventors revealed that the solubility of corrosion products in the electropenetrating adhesive layer is correlated with the Lewis basicity of the anions of the ionic substances contained in the electropenetrating adhesive composition constituting the electropenetrating adhesive layer. While not bound by any particular theory, the Lewis basicity of anions in ionic substances is a parameter that correlates with the hydrophilicity and hydrophobicity of the anions, and thus correlates with the solubility of ionic substances in dispersion media. When possessing a specific range of hydrophilicity and hydrophobicity, the solubility of ionic substances in polymers tends to be particularly high. Here, when an electro-peelable adhesive layer containing an ionic substance is bonded to a base metal and stored for a long period in a humid and hot environment, the corrosion products that are generated are thought to be complexes of base metal cations and anions of the ionic substance contained in the electro-peelable adhesive layer. In other words, under these conditions, the solubility of the corrosion products in the polymer is thought to be correlated with the Lewis basicity of the anions of the ionic substance contained in the electro-peelable adhesive composition constituting the electro-peelable adhesive layer, according to the mechanism described above.

[0118] As a result of further intensive research by the inventors, it has been discovered that when the anions of the ionic substances contained in the electropenetrating adhesive composition have a predetermined Lewis basicity, it is possible to realize an electropenetrating adhesive composition that forms an electropenetrating adhesive layer that is less likely to cause metal corrosion. As mentioned above, if corrosion products are difficult to dissolve in the electropenetrating adhesive layer, corrosion is less likely to occur. The solubility of corrosion products in the electropenetrating adhesive layer is thought to correlate with the Lewis basicity of the anions of the ionic substances contained in the electropenetrating adhesive composition that constitutes the electropenetrating adhesive layer. Here, it was found that when the anions of the ionic substances have a Lewis basicity within a predetermined range, the solubility of the ionic substances in the polymer tends to be low. Specifically, it was found that when the Lewis basicity of the anions of the ionic substances is low or moderate, that is, in the region of high or moderate hydrophobicity, the solubility of the ionic substances in the polymer tends to be low. For this reason, it is thought that corrosion is less likely to occur in the region where the Lewis basicity of the anions of the ionic substances is low or moderate because the solubility of corrosion products is low. Furthermore, if the Lewis basicity of the anions is too high (too hydrophilic), it is thought that corrosion will progress due to the increased water content of the adhesive layer.

[0119] Based on these findings, the electropenetrating adhesive composition obtained contains an ionic substance whose anion has a Lewis basicity of 0.20 or less, or 0.27 to 0.60 or less. Having a Lewis basicity of 0.20 or less, or 0.27 to 0.60 or less, is suitable for realizing an electropenetrating adhesive layer that has good electropenetration properties while being less likely to cause metal corrosion even when placed in a high-temperature, high-humidity environment in contact with metal, because the solubility of the ionic substance in the polymer is moderately low. The anion of the ionic substance has a Lewis basicity of 0.20 or less, or 0.27 to 0.60 or less, preferably 0.01 to 0.20 or 0.27 to 0.50, and from the viewpoint of easily achieving a low corrosion rate, preferably 0.01 to 0.20 or 0.28 to 0.45, and more preferably 0.01 to 0.10 or 0.28 to 0.42. Anions with a Lewis basicity of 0.20 or less are preferably tetraphenylboric acid derivatives in which a fluorine atom is directly bonded to a phenyl group, such as tetrakis(4-fluorophenyl)boric acid (TFPB) and pentafluorophenyl)boric acid (TPFPB). Furthermore, anions with a Lewis basicity of 0.27 to 0.60 include, for example, tricyanomethanide (TCM) and tetracyanoborate (TCB).

[0120] The Lewis basicity of anions in ionic substances is obtained by nuclear magnetic resonance (NMR) spectroscopy, and more specifically, it refers to the value obtained by measuring under the following conditions using an NMR spectrometer. (Measurement of Lewis basicity of anions in ionic substances) Weigh the ionic substance, 4-fluorophenol, and 4-fluoroanisole separately, and prepare Solution 1 so that the concentration of 4-fluorophenol is 0.01 mol / L or less, and Solution 2 so that the concentration of 4-fluoroanisole is 0.1 mol / L or less. The solvent used to prepare the solutions will be selected according to the properties of the ionic substance. If the ionic substance is an ionic liquid, the ionic liquid itself will be used as the solvent. On the other hand, if the ionic substance is not an ionic liquid, prepare a 1,2-dichloroethane solution containing 4% by mass of the ionic substance and use this as the solvent. Place these two solutions (Solution 1 and Solution 2) inside separate double NMR tubes, and place deuterated chloroform containing dissolved hexafluorobenzene inside the double NMR tubes. These two samples were subjected to 19F-NMR measurements using an NMR spectrometer (Bruker Biospin, AVANCE NEO-600 with CryoProbe) (frequency: 565 MHz, measurement temperature: 300 K, chemical shift reference: hexafluorobenzene - 162.20 ppm). The Lewis basicity β1 of an anion in an ionic substance is calculated according to the following formula. β1={δ(19F)(OH)-δ(19F)(OMe)} / 3.041 Here, δ(19F)(OH) is the absolute value of the chemical shift in the 19F-NMR measurement of 4-fluorophenol, and δ(19F)(OMe) is the absolute value of the chemical shift in the 19F-NMR measurement of 4-fluoroanisole.

[0121] In ionic materials, cations are generally selected from the group consisting of nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations because they are chemically stable and suitable for improving electrolysis. Imidazolium-based, ammonium-based, pyrrolidinium-based, and pyridinium-based cations are more commonly used.

[0122] 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, 1-dodecyl-3-methylimidazolium cation, and 1-tridecyl-3-methylimidazolium cation. Examples include cyl-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, 1,3-bis(dodecyl)imidazolium cation, and 1-allyl-3-methylimidazolium cation.

[0123] 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.

[0124] Examples of pyrrolidinium-based cations include 1-ethyl-1-methylpyrrolidinium cation, 1-propyl-1-methylpyrrolidinium cation, and 1-butyl-1-methylpyrrolidinium cation.

[0125] Examples of ammonium cations include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, tributylmethylammonium cation, and (2-acryloyloxyethyl)trimethylammonium cation.

[0126] As for ionic materials, from the viewpoint of significantly reducing the rate of decrease in adhesive strength when voltage is applied, cations with a molecular weight of 160 or less are generally used as constituent cations, such as the above (FSO2)2N-[bis(fluorosulfonyl)imide anion] or (CF3SO2)2N - Ionic substances containing [bis(trifluoromethanesulfonyl)imide anion] and a cation with a molecular weight of 160 or less are particularly commonly used. 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-propyl-1-methylpyrrolidinium cation, 1-butyl-1-methylpyrrolidinium cation, tetraethylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethyl acrylate cation.

[0127] Furthermore, cations represented by the following formulas (2-A) to (2-D) are also commonly used as cations of ionic substances.

[0128] [ka]

[0129] 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 It does not exist.

[0130] R in equation (2-B) 4 R 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 heteroatoms. 5 , R 6 , and R 7 These represent, either identically or differently, 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, and even more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may also contain heteroatoms.

[0131] R in equation (2-C) 8 R 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 heteroatoms. 9 , R 10 , and R 11 These represent, either identically or differently, 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 also contain heteroatoms.

[0132] In formula (2-D), X represents a nitrogen, sulfur, or phosphorus atom, and R 12 , R 13 , R 14 , and R 15 R represents a hydrocarbon group having 1 to 16 carbon atoms, either identical or different, (preferably a hydrocarbon group having 1 to 14 carbon atoms, more preferably a hydrocarbon group having 1 to 10 carbon atoms, even more preferably a hydrocarbon group having 1 to 8 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 6 carbon atoms), and may contain heteroatoms. However, if X is a sulfur atom, R 12 It does not exist.

[0133] The molecular weight of cations in ionic materials 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. Furthermore, it is particularly preferably 140 or less, even more particularly preferably 120 or less, and most preferably 115 or less. Also, it is usually 50 or more. It is thought that cations in ionic materials have the property of moving to the cathode side when a voltage is applied in the electropenetrating adhesive layer and becoming biased near the interface between the electropenetrating adhesive layer and the adherend. In the embodiments of the present invention, for this reason, the adhesive strength decreases when a voltage is applied compared to the initial adhesive strength, and electropenetration occurs. Cations with a small molecular weight, such as 500 or less, are suitable for increasing the rate of decrease in adhesive strength due to voltage application because the movement of cations to the cathode side in the electropenetrating adhesive layer is easier.

[0134] The amount of electrolyte (ionic substance) added to the adhesive composition according to the present invention is preferably 10 parts or less, more preferably 5 parts or less, even more preferably 2 parts or less, and more preferably 1 part or less, based on the mass of polymer in the adhesive composition, and this amount is sufficient to make the adhesive composition electrodetached. This is because it is believed that metal corrosion by anions of the ionic substance can be suppressed and the decrease in normal peel strength associated with the addition of ionic substances can be suppressed. The amount of ionic substance added is preferably 1 part or more, more preferably 2 parts or more, even more preferably 5 parts or more, and more preferably 10 parts or more, based on the mass of polymer in the adhesive composition. This is because it is expected that the electrorelease properties of the electrorelease adhesive will be improved, and the impact resistance will be improved by plasticizing the polymer.

[0135] Examples of commercially available ionic substances include "Elexel AS-110" from Daiichi Kogyo Seiyaku Co., Ltd., "E1452", "E0599", "M2098", "M2980", "M2981", and "M2998" from Tokyo Kasei Kogyo Co., Ltd., "HMI-FSI" from Mitsubishi Materials Corporation, and "CIL-312" and "CIL-313" from Nippon Carlit Co., Ltd.

[0136] [Mechanism of electrolysis] In electropenetrating adhesive sheets, the application of voltage causes cations of the electrolyte (ionic substance) to move at the cathode, leading to reduction, while on the anode side, anions of the ionic substance move, leading to oxidation. This weakens the adhesive strength at the bonding interface, making it easier to peel off. While not bound by any particular theory, when a voltage is applied to an electropenetrating adhesive sheet, it is thought that the higher the ionic conductivity of the adhesive layer, which is composed of an adhesive containing a polymer, the greater the mobility of electrolyte cations to the interface between the adherend and the adhesive layer. The greater the amount (or frequency) of cations reaching the interface, the higher the likelihood of improved electropenetration. Next, the cations that have moved to the cathode side undergo a reduction reaction to become their reduced forms (cationic reduced forms). Some of these diffuse into the bulk of the adhesive layer, but the rest remain at the interface between the adherend and the adhesive layer, and as this process repeats, the reduced forms accumulate at the interface. It is thought that the smaller the proportion (or speed) at which the cationic reduced forms diffuse into the bulk, the higher the electropenetration. Furthermore, if the solubility of the reduced forms accumulated at the interface is within a certain range, it becomes easier to peel the adhesive layer from the adherend.

[0137] [Ionic conductivity of the adhesive layer] The ionic conductivity of the adhesive layer composed of the adhesive composition according to the present invention is preferably 0.02 μS / m or higher, more preferably 5 μS / m or higher, even more preferably 15 μS / m or higher, even more preferably 40 μS / m or higher, and particularly preferably 60 μS / m or higher. The adhesive composition according to the present invention contains a polymer and an electrolyte. Generally, the lower the Tg of the polymer, the higher the ionic conductivity of the adhesive layer formed from the adhesive composition tends to be. Furthermore, when the amount of electrolyte (ionic substance) added to the adhesive composition is large, or when the viscosity of the ionic substance is low, or when the Tg of the ionic substance is low, the ionic conductivity of the adhesive layer formed from the adhesive composition tends to be high. For ionic conductivity to be exhibited, the polymer and electrolyte (ionic substance) contained in the adhesive composition constituting the adhesive layer must be miscible. For example, by using a polymer in which a second polymer, which is miscible with the first polymer and the ionic substance, is added in a smaller amount than the first polymer, it is possible to increase the concentration of the ionic substance in the first polymer phase, thereby contributing to improved ionic conductivity. It is thought that the higher the ionic conductivity, the greater the amount of cations that move from the adhesive bulk to the interface between the adherend and the adhesive layer, and the greater the amount of reduced cations that can contribute to peeling. The upper limit of the ionic conductivity of the adhesive layer composed of the adhesive composition according to the present invention is not particularly limited, but may be, for example, 200 μS / m or less. The techniques disclosed herein can be preferably implemented, for example, in a manner in which the ionic conductivity of the adhesive layer is in the range of 0.02 μS / m or more and 200 μS / m or less, more preferably 0.02 μS / m or more and 100 μS / m or less.

[0138] (Haze value of the adhesive layer) The haze value of the adhesive layer formed from the adhesive composition according to the present invention is preferably 30.0% or less, 20.0% or less, 10.0% or less, 5.0%p or less, 3.0% or less, 2.0% or less, or 1.0% or less. The haze value of the adhesive layer can be adjusted by the combination of constituent materials. For example, it can be adjusted by a combination of two or more polymers or a combination of polymer and electrolyte (ionic substance). Such adhesive layers are less prone to deterioration of polymer compatibility and changes in adhesive properties even when stored in a heated or humid thermal environment, thus improving the storage stability of the adhesive layer. Furthermore, segregation and precipitation of the electrolyte (ionic substance) do not occur when no voltage is applied, further enhancing the storage stability of the adhesive layer.

[0139] Here, "haze value" refers to the ratio of diffusely transmitted light to total transmitted light when visible light is shone on the object being measured. It is also called the cloudiness value. The haze value can be expressed by the following formula. Th(%) = Td / Tt × 100 In the above formula, Th is the haze value (%), Td is the scattered light transmittance, and Tt is the total light transmittance. The haze value of the adhesive layer can be measured as follows. First, a composition consisting only of polymer or only of polymer and electrolyte is prepared, and each sample for measurement (adhesive layer consisting only of polymer or adhesive layer consisting only of polymer and electrolyte, thickness 50 μm) is prepared by coating and drying it on a release liner as described in the Examples section. The obtained adhesive layer is bonded to a glass slide (for example, one with a total light transmittance of 92% and a haze of 0.2%), and then left to stand for at least 24 hours in an environment of 25°C and 50% RH to prepare a test specimen. Next, the haze value of the test specimen is measured using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150N") in a measurement environment of 25°C. Then, the value obtained by subtracting the haze value of the glass slide from the measured value can be calculated as the haze value of the adhesive layer.

[0140] Furthermore, it is believed that the higher the ionic conductivity, the easier it is to peel off at a lower voltage during electrolysis. In particular, when the cation reducer does not easily diffuse into the bulk (low diffusivity of the cation reducer), for example, as described later, when the adhesion recovery rate is low (e.g., less than 60%), the high ionic conductivity allows for peeling at a low voltage. This makes it possible to suppress the amount of reaction within the adhesive composition required for electrolysis (specifically, the amount of cation reduction reaction required to obtain high electrolysis), which is expected to be advantageous for the repeatability of electrolysis. Furthermore, if the adherend is a metal, there is a possibility that the adhesive composition may corrode the adherend, resulting in a defective appearance. From this perspective, a lower ionic conductivity is desirable because it may suppress corrosion by reducing the reactivity of anions with the adherend metal.

[0141] Furthermore, in some embodiments, the upper limit of the ionic conductivity of the adhesive layer composed of the adhesive composition according to the present invention is advantageous to be less than 11 μS / m, preferably 7 μS / m or less, more preferably 3 μS / m or less, even more preferably 2 μS / m or less, even more preferably 1.0 μS / m or less, and may also be 0.7 μS / m or less, 0.4 μS / m or less, 0.2 μS / m or less, or 0.15 μS / m or less. In particular, if the cation reducer does not easily diffuse into the bulk of the adhesive layer (the diffusivity of the cation reducer is low), more specifically, if the adhesive has a low adhesion recovery rate (e.g., less than 60%), as will be described later, and if the ionic conductivity of the adhesive layer is set to be low, the repeatability of electrolysis at 10V30s can be improved, for example. Having a low adhesion recovery rate (e.g., less than 60%) in the adhesive layer suppresses the amount of cation reduction reaction required to obtain electrolysis, and having a low ionic conductivity in the adhesive layer makes it less likely for excess cation reduction reactions to occur relative to the amount of cation reducer required to obtain electrolysis, so it is expected to work favorably, for example, in improving the repeatability of electrolysis at 10V30s. As described above, for example, from the viewpoint of improving the repeatability of electrolysis at 10V30s, the ionic conductivity of the adhesive layer composed of the adhesive composition according to the present invention is preferably less than 11 μS / m, more preferably 6 μS / m or less, even more preferably 3 μS / m or less, and particularly preferably 1.0 or less.

[0142] While various methods exist for measuring the ionic conductivity of an adhesive layer, a simple method involves preparing a sample using the adhesive composition and then determining the ionic conductivity of the adhesive layer. Specifically, as described in the examples, a bonded body is prepared by attaching an adherend (stainless steel plate, etc.) to the other side of an electropenetrating adhesive layer on which a substrate (such as a metal-layered film) is bonded to one side. A small amplitude AC voltage (e.g., 10 mV) is applied to this bonded body sample, and the impedance is measured by sweeping the frequency to obtain a Cole-Cole plot. The bulk of the adhesive layer resists R adh and the parameters of the Constant Phase Element (CPE) (CPE-T:Q adh The circuit is modeled as a parallel circuit using the combination of CPE-P:α). The series resistance of the wiring is R0, and the equivalent circuit of the junction sample is set as shown in Figure 6. The obtained cole-cole plot is fitted using the following equation (A) (ω: angular frequency, Z(ω): complex impedance at angular frequency ω, j: imaginary unit). The Q obtained by fitting is... adh By substituting α into equation (B) below, the capacitance C adh The following is calculated. It is preferable to exclude the linear response of the electrode interface observed in the low-frequency region from the analysis and use only the semicircular portion.

[0143]

number

[0144] Next, the bulk resistance component R of the adhesive layer, obtained from equation (A) adhThe ionic conductivity σ of the adhesive layer can be determined using the following formula (C).

[0145]

number

[0146] In equation (C), l is the thickness of the adhesive layer, and A is the area of ​​the adhesive surface of the adhesive layer.

[0147] [HSP distance between cation reducer and polymer] The solubility of a cation reducer can be evaluated by the Hansen solubility parameter distance (HSP distance) between the cation reducer and the polymer constituting the adhesive layer (adhesive composition). The HSP distance is determined by the following formula, using the Hansen solubility parameters (HSP value) of the polymer (dispersion term (dDp), polarity term (dPp), hydrogen bonding term (dHp)) and the HSP value of the cation reducer (dispersion term (dDc), polarity term (dPc), hydrogen bonding term (dHc)), as described later.

number

[0148] The electrolyte contained in the adhesive composition according to the present invention has a reduced cation of this electrolyte that, in relation to the polymer contained in the adhesive composition, has a coefficient of 9 MPa. 0.5 It has the following HSP distance. HSP distance is 3 MPa 0.5 Preferably, the above, and moreover, 3.5 MPa 0.5 The above is preferable. Also, the HSP distance should be 8 MPa. 0.5 Preferably the following, and furthermore 7 MPa 0.5 The following is preferable. Also, 6.5 MPa 0.5 The following is also acceptable: 6 MPa 0.5 The following is also acceptable: 5 MPa 0.5 The following is also acceptable. Furthermore, in some embodiments, from the viewpoint of easily achieving a low 15-minute adhesion recovery rate, the lower limit of the HSP distance between the cation reducer and the polymer is 5 MPa. 0.5 Preferably, it is 5.5 MPa or higher. 0.5 More preferably, the MPa is 6 MPa. 0.5 The above is also acceptable, 6.5 MPa 0.5 The above is also acceptable, or 7 MPa 0.5 The above is also acceptable. The upper limit of the HSP distance between the cation reducer and the polymer is 9 MPa. 0.5 The following is preferable: 8 MPa 0.5 The following is also acceptable: 7.5 MPa 0.5 The following is also acceptable. One method for adjusting the HSP value of a cation reducer is to adjust the type of cation. Another method for adjusting the HSP value of a polymer is to adjust the monomer composition of the polymer.

[0149] Generally, if the cation reducer has high solubility in the polymer, that is, high compatibility with the polymer, it becomes easier to peel the adhesive layer from the adherend. In other words, from the perspective of electropenetration, it is thought that the smaller the HSP distance (higher compatibility between the cation reducer and the polymer), the greater the rate of decrease in adhesive strength due to voltage application. Generally, if the compatibility of the cation reducer with the polymer is low, the diffusion rate of the cation reducer into the adhesive bulk will be low. In other words, from the perspective of voltage during electrolysis, the larger the HSP distance (lower compatibility between the cation reducer and the polymer), the lower the diffusion rate of the cation reducer into the adhesive bulk, resulting in easier peeling at lower voltages. In particular, in the case of adhesives where the cation reducer does not easily diffuse into the bulk of the adhesive layer (low diffusivity of the cation reducer), more specifically, as described later, and which have a low adhesion recovery rate (e.g., less than 60%), and where the ionic conductivity of the adhesive layer is set to be high, it becomes easier to realize an adhesive with excellent electropenetration properties under low voltage conditions. Because the adhesive layer has a low adhesion recovery rate after 15 minutes, a relatively small amount of cation reduction reaction is sufficient to obtain electropenetration, and because the adhesive layer has high ionic conductivity, it tends to be easier to obtain the amount of cation reducer necessary to obtain electropenetration even at low applied voltages, so it is expected to work favorably for the development of high electropenetration properties even under low voltage conditions (e.g., 2V30s). As described above, in terms of improving electropenetration under low voltage conditions (e.g., 2V30s), the ionic conductivity of the adhesive layer composed of the adhesive composition according to the present invention is preferably greater than 11 μS / m, more preferably 15 μS / m or more, even more preferably 20 μS / m or more, even more preferably 30 μS / m or more, even more preferably 35 μS / m or more, and particularly preferably 50 μS / m or more. Furthermore, in order to facilitate the formation of an adhesive layer in which the amount of cation reductants generated is greater than the amount of cation reductants diffused into the adhesive bulk, and to facilitate the realization of an adhesive layer with an adhesive strength recovery rate of less than 60% after 2 minutes, in one preferred embodiment of this product, the polymer contained in the adhesive composition is an acrylic polymer, and the ionic conductivity of the adhesive layer formed from the adhesive composition is preferably 40 μS / m or more. From a similar viewpoint, the ionic conductivity of the adhesive layer is more preferably 50 μS / m or more, and more preferably 55 μS / m or more. Furthermore, from the viewpoint of easily forming an adhesive layer in which the diffusion rate of the cationic reduced product into the adhesive bulk is low, and easily realizing an adhesive layer in which the adhesive strength recovery rate after 2 minutes is less than 60%, in one preferred embodiment of this model, it is preferable that the polymer contained in the adhesive composition is an acrylic polymer and that the Tg of the polymer is -30°C or higher. From a similar viewpoint, it is more preferable that the Tg of the polymer is -29°C or higher, and even more preferable that it is -28°C or higher.

[0150] The Hansen solubility parameter (HSP value) is expressed by the following formula, where dH is the hydrogen bonding term representing the energy derived from intermolecular hydrogen bonding forces, dD is the dispersion term representing the energy derived from intermolecular dispersion forces, and dP is the polarization term representing the energy derived from intermolecular polar forces.

number

[0151] [HSP value of polymers] The dispersion term (dDp), polarity term (dPp), and hydrogen bonding term (dHp) in the HSP value of a polymer are calculated using the commercially available computer software Hansen Solubility Parameters in Practice (HSPiP). When two or more monomers are copolymerized, or when two or more polymers are blended, the HSP value of the polymer when each component is miscible can be determined from the HSP value when each component forms a homopolymer and the volume fraction of each monomer. For example, when monomer 1 and monomer 2 are randomly copolymerized in a volume fraction a:b, the dispersion term (dD1), polarity term (dP1), and hydrogen bonding term (dH1) of the HSP value of monomer 1, and the dispersion term (dD2), polarity term (dP2), and hydrogen bonding term (dH2) of the HSP value of monomer 2 can be used to calculate the HSP value using the following formula.

number

[0152] a and b may be calculated from the weight fractions of monomer 1 and monomer 2, and the densities when monomer 1 and monomer 2 each form a homopolymer. Furthermore, when two or more monomers are copolymerized, or when two or more polymers are blended, and each component is in phase separation, the ionic component moves through the matrix phase, and a cation reducer is formed at the interface between the matrix phase and the adherend. Therefore, in this case, the HSP value of the polymer constituting the matrix phase is used.

[0153] When the polarity of the adherend is low, it is thought that the smaller the hydrogen bonding term in the polymer's HSP value, the greater the adhesive strength to the adherend tends to be. From the perspective of preventing cosmetic defects caused by corrosion of the adherend by the adhesive composition, it is thought that the smaller the hydrogen bonding term in the HSP value, the lower the water content, water vapor permeability, and oxygen permeability of the adhesive, and as a result, a lower corrosion rate is expected.

[0154] [HSP value of cation reducers] Cation reduction refers to a reaction in which a group (alkyl group, ether group, or other group) bonded to a positively charged element (nitrogen (N), phosphorus (P), or other central element) is eliminated as a radical, or otherwise reacts to produce a corresponding neutral compound (amine, phosphine, or other compound). The structure of the cation reduced product is defined based on the following.

[0155] [Definition of a cation reducer] (Reduced imidazolium cations) The carbon atom at position 2 of the imidazolium ring loses its aromaticity and becomes a neutral radical when it accepts an electron. Subsequently, it transforms into an N-heterocyclic carbene with the elimination of a hydrogen atom. Since HSPiP cannot calculate carbenes, when calculating HSP values ​​and surface free energy using HSPiP, the calculation is performed on a structure in which two hydrogen atoms are attached to the carbon atom at position 2.

[0156] (Reduced organic cations other than imidazolium) The reduction of organic cations other than imidazolium involves the elimination of a group (alkyl group, ether group, or other group) bonded to a positively charged element (nitrogen (N), phosphorus (P), or other central element) as a radical, generating the corresponding neutral compound (amine, phosphine, or other compound). The group that is eliminated is determined based on the stability of the resulting radical. • Stability of radicals: Tertiary radical > Secondary radical > Primary radical > Methyl radical > Hydrogen radical • When a radical is adjacent to a double bond, it undergoes resonance stabilization, so allyl radicals and benzyl radicals have the same stability as secondary radicals. • If ether groups or other electron-donating groups are present, the stability of the radicals formed by those groups should also be considered (e.g., ether groups can be stabilized by the electron-donating effect of adjacent oxygen atoms). • In the case of equivalent stability, the group with the longer chain length will be eliminated. Examples of groups that leave the system: alkyl groups (hydrocarbon groups such as methyl, ethyl, and propyl), ether groups (-OR type groups such as methoxy and ethoxy groups, where R includes an aryl group), alkyl halides, aryl groups (such as -Ph), etc. • Types of products In the case of cyclic cations other than imidazolium-based cations (e.g., pyrrolidinium-based, piperidinium-based, pyridinium-based), neutral compounds that maintain the ring structure are produced. In the case of acyclic cations (e.g., ammonium-based, phosphonium-based), alkylamines, alkylphosphines, or analogs thereof are produced. Examples of reduced forms for each cation species are shown below.

[0157] (Reduced forms of pyrrolidinium and piperidinium cations) When a substituent other than hydrogen is added to the N element of the pyrrolidinium ring or piperidinium ring, the substituent other than hydrogen is eliminated to form pyrrolidine or piperidine. For example, when two alkyl groups are added to the N element, one of them is eliminated as a radical to form alkylpyrrolidine or alkylpiperidine. At this time, the conditions for the eliminating group follow those described above. For example, in the case of 1-butyl-1-methylpyrrolidinium, it is the butyl group that becomes a primary radical rather than the methyl group that becomes a methyl radical that is eliminated, and N-methylpyrrolidine is formed.

[0158] (Reduced form of pyridinium-based cation) The substituent attached to the N element of the pyridinium ring is eliminated as a radical to form a pyridine-based compound.

[0159] (Reduction of ammonium-based cation) The substituent attached to the positively charged N element is eliminated as a radical to form an amine-based compound. The conditions for the eliminating group follow those described above.

[0160] (Reduction of phosphonium-based cation) The substituent attached to the positively charged P element is eliminated as a radical to form a phosphine-based compound. The conditions for the eliminating group follow those described above.

[0161] Although it is conceivable to calculate the HSP values of the cationic reductants defined as above by various methods, it is convenient to input the chemical structure of the cationic reductant in the SMILES notation into commercially available computer software (such as Hansen Solubility Parameters in Practice (HSPiP)) and calculate the HSP values (dispersion term (dDc), polar term (dPc), hydrogen bonding term (dHc)) of the cationic reductant.

[0162] [Surface free energy of cationic reductant] The electrolyte contained in the adhesive composition according to the present invention is such that the reduced form of the cation of this electrolyte is ...... 2 ~36mJ / m 2has a surface free energy. The surface free energy of the reduced form of the cation of the electrolyte is preferably 20 mJ / m 2 or more, more preferably 24 mJ / m 2 or more, still more preferably 25 mJ / m 2 or more, particularly preferably 26 mJ / m 2 or more. Preferably 40 mJ / m 2 or less, more preferably 36 mJ / m 2 or less, still more preferably 30 mJ / m 2 or less, particularly preferably 27 mJ / m 2 or less.

[0163] When the surface free energy of the reduced form of the cation of the electrolyte is within the above range, good electrical peelability can be exhibited.

[0164] Various methods can be considered for calculating the surface free energy of the reduced form of the cation. However, considering the chemical structure of the reduced form of the cation, inputting the chemical structure of the reduced form of the cation into commercially available computer software (such as Hansen Solubility Parameters in Practice (HSPiP)), and obtaining the parameters (Mwt, density (ρ), Parachor (P)) for calculating the surface free energy (γ) of the reduced form of the cation from the following formula is a simple method.

[0165]

Equation

[0166] (Other components) The electrically peelable adhesive composition according to an embodiment of the present invention may contain one or more components other than the polymer and the ionic substance (hereinafter sometimes referred to as "other components") as long as the effects of the present invention are not impaired. Hereinafter, the other components that can be contained in the electrically peelable adhesive composition according to an embodiment of the present invention will be described.

[0167] The electrolytic adhesive compositions according to embodiments of the present invention 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, carbodiimide-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. Examples of epoxy-based crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and 1,6-hexanediol diglycidyl ether. Other examples of crosslinking agents include monomers having two or more ethylenically unsaturated groups in one molecule, i.e., polyfunctional monomers. For examples of polyfunctional monomers, the description of polyfunctional monomers above can be directly applied. When a crosslinking agent is included, the content is preferably 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of polymer. Furthermore, 0.001 parts by mass or more and 5.0 parts by mass or less is preferred. From the viewpoint of improving the flexibility of the adhesive, in some embodiments, the content of the crosslinking agent is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, may also be 1.0 part by mass or less, may also be 0.5 parts by mass or less, or may also be 0.2 parts by mass or less, per 100 parts by mass of polymer. Also, from the viewpoint of appropriately exhibiting the effect of using the crosslinking agent, in some embodiments, the content of the crosslinking agent may be, for example, 0.005 parts by mass or more, may also be 0.01 parts by mass or more, may also be 0.03 parts by mass or more, or may also be 0.05 parts by mass or more, per 100 parts by mass of polymer. Furthermore, the crosslinking agent can be used alone or in combination of two or more types.

[0168] To more effectively advance the crosslinking reaction, a crosslinking catalyst may be used. Examples of crosslinking catalysts include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric narcem, butyltin oxide, dioctyltin dilaurate, and dibutyltin dilaurate. Among these, tin-based crosslinking catalysts such as dioctyltin dilaurate and dibutyltin dilaurate are preferred. The amount of crosslinking catalyst used is not particularly limited. Considering the balance between the speed of the crosslinking reaction and the length of the pot life of the adhesive composition, the content of the crosslinking catalyst can be in the range of, for example, 0.001 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of polymer, and preferably in the range of 0.005 parts by mass or more and 0.5 parts by mass or less.

[0169] The electrolytic adhesive composition according to the embodiment of the present invention may optionally contain a compound having a polyoxyalkylene skeleton for the purpose of assisting the movement of ionic substances when voltage is applied. Examples of compounds having a polyoxyalkylene skeleton include polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); polyethers containing polyoxyethylene units, polyethers containing polyoxypropylene units, compounds containing oxyethylene units and oxypropylene units (the arrangement of these units may be random or block-like); derivatives thereof; and the like. In one embodiment, the electrolytic adhesive composition may contain polyethylene glycol. The molecular weight of the compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol) is not particularly limited, and those having a number average molecular weight of 200 to 6000 can be used. From the viewpoint of uniform mixing, it is appropriate, for example, to be less than 1000, and preferably 600 or less (e.g., 500 or less). The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol) is not particularly limited, but those with a molecular weight of 100 or more (e.g., 200 or more, and even more preferably 300 or more) are preferably used. In one embodiment, polyethylene glycol having a number average molecular weight of 200 to 6000 can be used. If a compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol) is included, the content is preferably 0.1 parts by mass or more and 30 parts by mass or less per 100 parts by mass of polymer. In some embodiments, compounds having a polyoxyalkylene skeleton (e.g., polyethylene glycol) may be substantially free of being used. Here, "substantially free" means that the amount of the compound in the adhesive layer formed from the adhesive composition is less than 1% by mass, preferably less than 0.1% by mass (e.g., 0% by mass or more and less than 0.01% by mass). Such an electropenetrating adhesive layer does not undergo segregation and precipitation of the compound, and the storage stability of the electropenetrating adhesive layer can be improved.

[0170] The adhesive composition for electrical peeling according to an embodiment of the present invention may contain a conductive filler as needed for the purpose of imparting conductivity to the adhesive composition for electrical peeling. The conductive filler is not particularly limited, and general known or commonly used conductive fillers can be used. For example, graphite, carbon black, carbon fiber, metal powders such as silver and copper, etc. can be used. When containing a conductive filler, the content is preferably 0.1 part by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the polymer.

[0171] The adhesive composition for electrical peeling according to an embodiment of the present invention may also contain various additives such as a filler, a plasticizer, an anti-aging agent, an antioxidant, a pigment (dye), a flame retardant, a solvent, a surfactant (leveling agent), a rust preventive agent, an adhesion-imparting agent, an adhesion-imparting resin, a corrosion preventive agent, and an antistatic agent. 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 part by mass or more and 20 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 5 parts by mass or less with respect to 100 parts by mass of the polymer.

[0172] Examples of the filler include silica, iron oxide, zinc oxide, aluminum oxide, titanium oxide, barium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, wax stone clay, kaolin clay, and fired clay.

[0173] As the plasticizer, known and commonly used plasticizers used in general resin compositions and the like can be used. For example, oils such as paraffin oil and process oil, liquid rubbers 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 can be used.

[0174] Examples of anti-aging agents include compounds such as hindered phenols, aliphatic and aromatic hindered amines, etc.

[0175] Examples of antioxidants include butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), etc.

[0176] Examples of pigments include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, sulfate, etc., azo pigments, and organic pigments such as copper phthalocyanine pigments, etc.

[0177] Examples of rust inhibitors include zinc phosphate, tannic acid derivatives, phosphate esters, basic sulfonates, and various rust-inhibiting pigments, etc.

[0178] Examples of adhesion promoters include titanium coupling agents, zirconium coupling agents, etc.

[0179] Examples of antistatic agents generally include quaternary ammonium salts, or hydrophilic compounds such as polyglycolic acid and ethylene oxide derivatives, etc.

[0180] Examples of tackifiers include tackifying resins, acrylic oligomers, epoxy oligomers, styrene oligomers, etc. 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, etc. The tackifying resins can be used alone or in combination of two or more. Examples of acrylic oligomers include low molecular weight polymers of monomer components containing one or more of the acrylic monomers exemplified above (for example, Mw is approximately 10×10 4 less than, preferably 5×10 4Acrylic oligomers (less than 100 mg) can be used. Acrylic oligomers can also be obtained by polymerizing the corresponding monomer components by known methods. When producing the above oligomers by radical polymerization, polymerization initiators, chain transfer agents, emulsifiers, etc. used in radical polymerization can be added to the monomer components as appropriate, and polymerization can be carried out. The polymerization initiators, chain transfer agents, emulsifiers, etc. used in radical polymerization are not particularly limited and can be selected and used as appropriate. The weight-average molecular weight of the oligomer can be controlled by the amount of polymerization initiator and chain transfer agent used and the reaction conditions, and the amount used can be adjusted as appropriate depending on the type of these agents.

[0181] Examples of corrosion inhibitors include carbodiimide compounds, adsorption-type inhibitors, and chelate-forming metal deactivators. For example, those described in Japanese Patent Publication No. 2019-059908 can be used.

[0182] [Uses of electrolytic adhesive compositions] As described above, the electropenetrating adhesive composition according to the embodiment of the present invention exhibits the function of sufficiently reducing adhesive strength upon application of voltage. Due to this characteristic, the electropenetrating adhesive composition according to the embodiment of the present invention can be suitably applied to the applications described later for electropenetrating adhesive sheets. In particular, it can be preferably used for fixing components in electrical and electronic equipment.

[0183] [Initial adhesive strength, adhesive strength after voltage application, rate of decrease in adhesive strength due to voltage application] The adhesive strength of the electropenetrating adhesive layer according to the embodiment of the present invention can be evaluated by various methods, but for example, it can be evaluated by the 180° peel test described in the Examples section.

[0184] In this embodiment, the initial adhesive strength is preferably 4.4 N / cm or higher. The initial adhesive strength can be, for example, 5.0 N / cm or higher, 6.0 N / cm or higher, or 7.0 N / cm or higher. When the initial adhesive strength is 4.4 N / cm or higher, the adhesion to the adherend is sufficient, and the adherend is less likely to peel off or shift.

[0185] In the embodiment of the present invention, the electropenetrating adhesive layer is formed by creating an electropenetrating adhesive sheet as described in the Examples section, applying a voltage, and then performing a 180° peel test to measure the adhesive strength after applying a voltage of 2V for 30 seconds and / or after applying a voltage of 10V for 30 seconds (electropenetrating force), which is preferably 4.3 N / cm or less, more preferably 4.0 N / cm or less, even more preferably 3.0 N / cm or less, preferably 2.0 N / cm or less, and even more preferably 1.0 N / cm or less. If the adhesive strength after voltage application is 4.3 N / cm or less, the adherend can be separated by hand. In some embodiments where separation of the adherend with less force is important, the adhesive strength after voltage application is preferably 0.5 N / cm or less, more preferably 0.3 N / cm or less, and even more preferably 0.1 N / cm or less. Furthermore, the greater the difference from the initial adhesive strength, the better the electropenetrating performance, and the difference from the initial adhesive strength is preferably 3.0 N / cm or more, and more preferably 6.0 N / cm or more. Furthermore, it is preferable that the value be 8.0 N / cm or higher, more preferably 10 N / cm or higher, and particularly preferable 12 N / cm or higher.

[0186] In the embodiment of the present invention, the electropenetrating adhesive layer preferably has a voltage-induced decrease in adhesive strength of 40% or more, more preferably 50% or more, and even more preferably 60% or more, which can be calculated using the following formula based on the initial adhesive strength and adhesive strength after voltage application measured by the above method. There is no particular upper limit to the voltage-induced decrease in adhesive strength, but for example, it can be 99.999% or less. Percentage decrease in adhesive strength due to voltage application (%) = {1 - (electrolytic peeling force / initial adhesive strength)} × 100

[0187] The applied voltage is appropriately set according to the purpose and manner of use and is not limited to a specific range. The applied voltage may be, for example, 1V to 500V. In some embodiments, from the viewpoint of the safety of the operator applying the voltage, it is advantageous for the applied voltage to be 300V or less, preferably 100V or less, and more preferably 75V or less. In some embodiments, from the viewpoint of operator safety or ease of handling of the power supply, the applied voltage is preferably 50V or less, more preferably 30V or less, more preferably 10V or less, even more preferably 5V or less, and particularly preferably 2V or less. This is because it is considered to contribute to higher operator safety and a reduction in energy consumption required during stripping. In some embodiments, from the viewpoint of ease of power supply availability, the applied voltage is preferably 12V or less, but may also be 9V or less, or 4V or less. A low applied voltage is also preferable from the viewpoint of enabling stripping work using readily available power sources such as dry cell batteries. Furthermore, from the viewpoint of worker safety, the lower the applied voltage, the better, but it is usually 1V or higher. In some embodiments, from the viewpoint of suppressing unintended stripping due to leakage current from electrical and electronic equipment, the applied voltage is preferably 4V or higher, but may also be 10V or higher, 20V or higher, 100V or higher, or 200V or higher. The voltage application time is appropriately set according to the purpose and manner of use and is not limited to a specific range. The voltage application time may be, for example, 5 seconds or more and 24 hours or less. In some embodiments, from the viewpoint of work efficiency, it is advantageous for the voltage application time to be 1 hour or less, and preferably 30 minutes or less. In some embodiments, from the viewpoint of the work efficiency of the worker applying the voltage, the voltage application time is preferably 600 seconds or less, preferably 300 seconds or less, more preferably 180 seconds or less, even more preferably 120 seconds or less, even more preferably 60 seconds or less, and particularly preferably 30 seconds or less. In such cases, workability is excellent. It is also preferable that the voltage application time is not too long, from the viewpoint that it can be quickly peeled off in the rework process and recycling process in the manufacturing process. Also, from the viewpoint of work efficiency, the shorter the application time, the better, but it is usually 1 second or more. In some embodiments, from the viewpoint of suppressing unintended peeling due to leakage current from electrical and electronic equipment, the voltage application time is preferably 5 seconds or more, may be 1 minute or more, may be 10 minutes or more, may be 30 minutes or more, or may be 1 hour or more. Generally, a material is considered to be more easily peeled off at lower voltages if it has a low adhesion recovery rate (low diffusivity of the cation reducer), high ionic conductivity, low compatibility between the cation reducer and the polymer (large HSP distance), the cation reducer spreads easily to the adherend (surface free energy of the reducer), and a low reduction potential of the ionic substance.

[0188] [Adhesion strength recovery rate after 2 minutes] The adhesive layer formed from the adhesive composition according to the present invention has an adhesive strength recovery rate of less than 60% after 2 minutes. In this specification, "adhesion recovery rate after 2 minutes" means the adhesion recovery rate after 2 minutes have elapsed since the application of the voltage that reduces the adhesive strength of the adhesive composition (i.e., the adhesive strength of the adhesive layer formed from the adhesive composition) was stopped. "Adhesion recovery rate after 15 minutes" is defined similarly. The adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is preferably 50% or less, more preferably 30% or less, even more preferably 10% or less, particularly preferably 5% or less, and most preferably 1% or less. Generally, a low 2-minute adhesion recovery rate means that the electro-peelable adhesive sheet can be peeled off the substrate even if there is an interval after the voltage application to the electro-peelable adhesive layer is stopped. Therefore, electro-peelable adhesive sheets with a low adhesion recovery rate can be said to have superior workability. A longer interval is better, but usually 2 minutes or more is sufficient. It is thought that the greater the amount of cation reductates generated at the adherend interface upon voltage application, and the less the amount of cation reductates diffusing into the adhesive bulk, the lower the adhesion recovery rate after 2 minutes tends to be. Furthermore, even in embodiments where the amount of cation reductates generated is greater than the amount of cation reductates diffusing into the adhesive bulk, the adhesion recovery rate after 2 minutes tends to be lower. The amount of cation reductates generated tends to increase with higher ionic conductivity of the adhesive layer, as this increases the amount of cations moving from the adhesive bulk to the interface between the adhesive layer and the adherend. Regarding the diffusivity of cation reductates, it is thought that the lower the compatibility of the cation reductates with the polymer, i.e., the larger the HSP distance between the cation reductates and the polymer, the higher the Tg of the polymer, and the higher the crystallinity of the polymer, the lower the diffusion rate of the cation reductates into the adhesive bulk. In the adhesive composition, adding a second polymer or tackifier with a higher Tg than the first polymer, in addition to the main component first polymer, is also effective in raising the Tg of the adhesive / adherend interface, thus lowering the adhesion recovery rate after 2 minutes. In this case, the second polymer and the first polymer may be compatible, but it is more preferable that they are not compatible. Furthermore, from the perspective of voltage during electrolysis, it is considered that the smaller the rate of adhesive strength recovery after 2 minutes, the easier it is to detach at a lower voltage. The 2-minute adhesive strength recovery rate of the adhesive composition according to the present invention can be evaluated by various methods, but for example, it can be evaluated by the following method.

[0189] [Electrical peeling properties at low voltage] When it is desired to set the applied voltage during electrical peeling to a low voltage (for example, 2 V or less), in addition to having a high ionic conductivity and an adhesive force recovery rate of less than 60% after 2 minutes of the adhesive composition, it is preferable that the adhesive force recovery rate after 15 minutes is low. The ionic conductivity of the adhesive layer is preferably 15 μS / m or more, more preferably 30 μS / m or more, still more preferably 40 μS / m or more, particularly preferably 60 μS / m or more. The adhesive force recovery rate after 15 minutes is preferably 90% or less, preferably 80% or less, preferably 50% or less, more preferably 30% or less, still more preferably 10% or less, particularly preferably 5% or less, and most preferably 1% or less.

[0190] 〔Repeatability of electrical peeling〕 The repeatability of electrical peeling means how many times electrical peeling → re-bonding → electrical peeling can be repeated. Along with the application of voltage, while the reduction reaction of cations proceeds at the adherend interface, on the substrate side (for example, an aluminum vapor-deposited substrate), the oxidation reaction of the metal (such as aluminum) constituting the substrate proceeds. In some embodiments, with the progress of the oxidation reaction of the metal (such as aluminum) of the substrate due to repeated electrical peeling, the adhesion between the adhesive and the substrate decreases and anchor failure occurs, so there may be a problem that it cannot be used repeatedly. Also, along with the application of voltage, cations are reduced at the interface between the adherend and the adhesive layer, and the cation reduction product accumulates at the interface between the adherend and the adhesive layer. In some embodiments, since the cation reduction product that accumulates in excess relative to the amount of cation reduction product required to obtain electrical peelability accumulates at the interface between the adherend and the adhesive layer without diffusing into the bulk of the adhesive layer, there may be a problem that sufficient adhesive force cannot be obtained when the voltage is not applied even when re-bonded to the adherend. In some embodiments, when the adhesive strength is reduced by the application of voltage and then re-bonded, that is, when the adhesive strength is reduced by the application of voltage and then re-bonded after the application of voltage is stopped, the adhesive strength when no voltage is applied is appropriately 1.0 N / cm or more, preferably 2.0 N / cm or more, more preferably 3.0 N / cm or more, and even more preferably 4.0 N / cm or more. When the adhesive strength is reduced by the application of voltage and then re-bonded after the application of voltage is stopped, the adhesive strength when no voltage is applied can be, for example, 5.0 N / cm or more, 6.0 N / cm or more, or 7.0 N / cm or more. Furthermore, it is preferable that the adhesive strength when the bond is not applied, after the adhesive strength has decreased due to voltage application and the bond is reattached after the voltage application is stopped, is sufficiently recovered compared to the adhesive strength when the voltage is not applied in the electrorelease adhesive layer that has never had voltage applied. That is, the recovery rate of the adhesive strength, which can be calculated using the following formula using the adhesive strength when the voltage is not applied after the bond is reattached after the voltage application is stopped and the adhesive strength when the voltage is not applied in the electrorelease adhesive layer that has never had voltage applied, is appropriately 40% or more, preferably 50% or more, more preferably 60% or more, and even more preferably 80% or more. If the recovery rate of the adhesive strength is 50% or more, it is possible to firmly bond the bond to the adherend again. Adhesion recovery rate (%) = {(Adhesion when voltage is not applied, after the adhesive strength decreases due to voltage application and the parts are reattached after the voltage application is stopped) / (Adhesion when voltage is not applied to the electropenetrating adhesive layer that has never been subjected to voltage)} × 100 The repeatability of the electrolysis is preferably 2 times or more, more preferably 4 times or more, even more preferably 6 times or more, and particularly preferably 10 times or more. If the cation reducer has low diffusivity and high ionic conductivity (allowing for low-voltage peeling and thus suppressing the amount of reaction within the adhesive composition), or if it has low ionic conductivity (allowing for suppression of the reaction even when high voltage is applied), then improved repeatability of electrolysis can be expected. For example, when peeling is performed under specific voltage application conditions such as 10V30s, lower ionic conductivity leads to a smaller reaction amount, thus improving repeatability. Furthermore, if electrolysis is possible at low voltage, further reducing the voltage during electrolysis can suppress the reaction amount, thus improving repeatability.

[0191] For example, in order to facilitate the realization of an adhesive layer having excellent repeatability of electrolysis at 10V30s, in a preferred embodiment, the ionic conductivity of the adhesive layer formed from the adhesive composition is preferably less than or equal to Cmax, which is calculated by the following formula. Cmax (μS / m) = (Adhesion strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes (%)) × 0.445 + 10 Furthermore, in order to further improve the repeatability of electrolysis at 10V20s, the ionic conductivity of the adhesive layer formed from the adhesive composition may be less than or equal to Cmax, which is calculated by the following formula. Cmax (μS / m) = (Adhesion strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes (%)) × 0.445 + 4.5 For example, from the viewpoint of facilitating the realization of an adhesive layer with excellent repeatability of electrolysis at 10V30s, if the 2-minute adhesion recovery rate (%) of the adhesive layer formed from the adhesive composition is low, it is preferable that the ionic conductivity of the adhesive layer formed from the adhesive composition is low. For example, if the 2-minute adhesion recovery rate (%) of the adhesive layer formed from the adhesive composition is <1%, it is preferable that the ionic conductivity of the adhesive layer formed from the adhesive composition be 10 μS / m or less, more preferably 7.5 μS / m or less, even more preferably 4.5 μS / m or less, and particularly preferably 2.0 μS / m or less. In this case, it is expected that the amount of excess cation reducers will be suppressed relative to the amount of cation reducers necessary to obtain electrolysis. On the other hand, if the adhesive strength recovery rate (%) after 2 minutes of the adhesive layer formed from the adhesive composition is high, To obtain good electropenetration properties, for example, from the viewpoint of increasing the rate of decrease in adhesive strength after applying 10V for 30s, it is preferable that the ionic conductivity of the adhesive layer formed from the adhesive composition is moderately high. For example, if the adhesive strength recovery rate (%) after 2 minutes of the adhesive layer formed from the adhesive composition is 44%, the ionic conductivity of the adhesive layer formed from the adhesive composition is preferably 2.0 μS / m or higher, more preferably 2.5 μS / m or lower, even more preferably 3.0 μS / m or lower, and particularly preferably 3.5 μS / m or lower. Furthermore, from the viewpoint of facilitating the realization of an adhesive layer having excellent repeatability of electrolysis at 10V30s, for example, it is preferable that the ionic conductivity of the adhesive layer formed from the adhesive composition be moderately low. For example, if the adhesive strength recovery rate (%) after 2 minutes of the adhesive layer formed from the adhesive composition is 44%, the ionic conductivity of the adhesive layer formed from the adhesive composition is preferably 30 μS / m or less, more preferably 27 μS / m or less, and even more preferably 25 μS / m or less. In this case, it is expected that the oxidation reaction of the metal on the opposite side of the cathode, i.e., the anode, which is the target of peeling by voltage application, will be moderately suppressed.

[0192] The electrolytic adhesive composition according to the embodiment of the present invention is not particularly limited, but can be produced by appropriately stirring and mixing a polymer, an ionic substance, and additives such as a crosslinking agent, polyethylene glycol, and conductive filler, which may be added as needed.

[0193] The thickness of the electropenetrating adhesive layer 1 is preferably 1 μm or more and 1000 μm or less, from the viewpoint of initial adhesion. The upper limit of the thickness of the electropenetrating adhesive layer 1 is more preferably 500 μm, even more preferably 300 μm, even more preferably 200 μm, even more preferably 150 μm, even more preferably 100 μm, even more preferably 80 μm, even more preferably 70 μm, even more preferably 60 μm, and even more preferably 50 μm. The lower limit is more preferably 5 μm, even more preferably 10 μm, even more preferably 20 μm, and even more preferably 30 μm. Having an electropenetrating adhesive layer that is not too thick can be advantageous from the viewpoint of making the electropenetrating adhesive sheet thinner. Having an electropenetrating adhesive layer that is not too thin makes it easier to obtain good initial adhesion. The technology disclosed herein can be preferably implemented, for example, in a manner in which the thickness of the electropenetrating adhesive layer is in the range of 20 μm to 500 μm, more preferably 30 μm to 200 μm, and more preferably 40 μm to 100 μm.

[0194] The thickness of the electropenetrating adhesive sheet according to the embodiment of the present invention 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 500 μm, even more preferably 300 μm, even more preferably 250 μm, even more preferably 200 μm, even more preferably 150 μm, even more preferably 100 μm, and may be 75 μm or less. The lower limit is more preferably 30 μm, and even more preferably 50 μm.

[0195] In particular, in the case of the electropenetrating adhesive sheets X1 and X2 shown in Figures 2 and 3, the thickness of the electropenetrating adhesive sheet is preferably 20 μm or more and 2000 μm or less. The upper limit of the thickness is more preferably 1000 μm, even more preferably 500 μm, even more preferably 300 μm, even more preferably 250 μm, even more preferably 200 μm, even more preferably 150 μm, and may be 120 μm or less, 100 μm or less, or 75 μm or less. The lower limit is more preferably 30 μm, even more preferably 50 μm, and even more preferably 100 μm.

[0196] In particular, in the case of the electropenetrating adhesive sheet X3 shown in Figure 4, the thickness of the electropenetrating adhesive sheet is preferably 50 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 μm, even more preferably 500 μm, and the lower limit is more preferably 50 μm, even more preferably 100 μm, and even more preferably 200 μm.

[0197] The surface of the electropenetrating adhesive layer of the electropenetrating adhesive sheet according to the embodiment of the present invention, and the surface of the adhesive layer when other adhesive layers are present, 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, more preferably 20 μm or more, even more preferably 30 μm or more, preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less.

[0198] [Method for manufacturing electropenetrating adhesive sheets] A known or conventional manufacturing method can be used for manufacturing an electropenetrating adhesive sheet according to an embodiment of the present invention. In the electropenetrating adhesive sheet according to the embodiment of the present invention, the electropenetrating adhesive layer can be formed by applying a solution of the electropenetrating adhesive composition according to the embodiment of the present invention dissolved in a solvent as needed onto a release liner, and then drying and / or curing it. Furthermore, if another adhesive layer is provided, the other adhesive layer can be formed by applying a solution of the adhesive composition, which does not contain ionic substances and additives, dissolved 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.

[0199] 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.

[0200] When the electro-peelable adhesive composition is an ultraviolet-curable adhesive compound, the adhesive layer in the electro-peelable adhesive sheet according to the embodiment of the present invention can be produced by irradiating a coating film formed from the ultraviolet-curable adhesive composition (pre-curing composition) with ultraviolet light. When performing ultraviolet irradiation in this manner, in order to prevent polymerization inhibition by oxygen, it is preferable to attach a cover sheet to the surface of the coating film and irradiate the electro-peelable adhesive compound with ultraviolet light while sandwiched between two sheets. Any suitable substrate can be used as the base material and cover sheet used to form the adhesive sheet. The base material and cover sheet may also be a release liner having a release treatment layer on the contact surface with the adhesive sheet. The light source for ultraviolet irradiation is not particularly limited as long as it can irradiate light in the wavelength range to which the photopolymerization initiator contained in the electrolytic adhesive composition is sensitive. Black light lamps, LED light sources, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, etc., are preferably used.

[0201] The irradiation intensity of the ultraviolet light is 3 mW / cm². 2 The above is preferable. The irradiance of the ultraviolet light is 3 mW / cm². 2If the UV intensity is below this level, the polymerization reaction time will be longer, which may result in lower productivity. The UV intensity in question is 200 mW / cm². 2 The following is preferable: The irradiance of the ultraviolet light is 200 mW / cm². 2 If the UV radiation level exceeds a certain point, the photopolymerization initiator is rapidly consumed, leading to a decrease in the molecular weight of the polymer, which can particularly reduce its retention capacity at high temperatures. Furthermore, the cumulative UV radiation level is between 100 mJ / cm² and 5000 mJ / cm². 2 It is preferable that this be the case. By irradiating an electro-removable adhesive composition applied to a substrate with ultraviolet light, unreacted monomer components and polyfunctional monomers in the UV-curable adhesive composition (pre-curing composition) react to obtain a polymer in which a cross-linked structure is introduced into the polymer chain.

[0202] By the above method, an electropenetrating adhesive layer and other adhesive layers can be manufactured, and by laminating a conductive substrate, an electropenetrating adhesive layer, and other adhesive layers as needed, an electropenetrating adhesive sheet according to the embodiment of the present invention can be manufactured.

[0203] [Method for electrolyzing off electrolyzable adhesive sheets] The peeling of the electropenetrating adhesive sheet from the adherend according to the embodiment of the present invention can be performed by applying a voltage to the electropenetrating adhesive layer, thereby generating a potential difference in the thickness direction of the electropenetrating adhesive layer. For example, a bond in which an electro-peelable adhesive sheet X1 or X2 is attached to a conductive adherend can be peeled off by, for example, connecting electrodes to the conductive layer and the conductive adherend and applying an electric current, thereby applying a voltage to the electro-peelable adhesive layer. For example, in the case of an electropenetrating adhesive sheet X3, electrodes can be connected to both conductive layers and current can be passed through them, and the sheet can be peeled off from the adherend by applying a voltage to the electropenetrating adhesive layer. It is preferable to apply current by connecting terminals to one end and the other end of the electropenetrating adhesive sheet so that a voltage is applied to the entire electropenetrating adhesive layer. Note that if the adherend has a metal adherend, the one end and the other end may be part of the adherend having a metal adherend. Note that when peeling, water may be added to the interface between the adherend surface of the conductive adherend and the electropenetrating adhesive layer before applying the voltage. The connection of the electrodes can be appropriately selected depending on the adhesive interface to be separated. For example, in a bond in which an electropenetrating adhesive sheet X1 or X2 is attached to a conductive adherend, the anode may be connected to the conductive layer and the cathode to the conductive adherend, or the cathode may be connected to the conductive layer and the cathode to the conductive adherend.

[0204] The configuration of the electropenetrating adhesive sheet is not particularly limited, but the conductive substrate 5 may have an extended portion that extends beyond the electropenetrating adhesive layer 1 and / or other adhesive layer 2 in the direction of surface expansion of the conductive substrate. In such a configuration, electrical connection between one terminal of a voltage application device or DC power supply device and the conductive substrate can be easily achieved via the extended portion of the conductive substrate.

[0205] [Applications of electropenetrating 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. However, electro-peelable adhesive sheets using such adhesive layers cannot be used when ultraviolet (UV) irradiation is difficult or when heat damages the adherend. The electro-peelable adhesive sheet according to the embodiment of the present invention, which has the above-mentioned electro-peelable adhesive layer, does not use ultraviolet light or heat, and can therefore be easily peeled off by applying voltage without damaging the adherend. For this reason, the electro-peelable adhesive sheet according to the embodiment of the present invention is suitable for fixing secondary batteries (e.g., lithium-ion battery packs) used in mobile terminals such as smartphones, mobile phones, laptop computers, video cameras, and digital cameras to their casings.

[0206] Furthermore, examples of rigid members to be joined by the electropenetrating adhesive sheet according to the embodiment of the present invention 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 electropenetrating 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 mainly composed of silsesquioxane and organic-inorganic hybrid substrates, flexible glass substrates for flexible displays, and graphene sheets.

[0207] [zygote] An embodiment of the present invention comprises an electro-peelable adhesive sheet according to the present invention and a conductive material, wherein the electro-peelable adhesive layer of the electro-peelable adhesive sheet is attached to the conductive material.

[0208] Examples of the bonded body according to the embodiment of the present invention include an electro-peelable adhesive sheet X1 and a bonded body in which the electro-peelable adhesive layer 1 side of the electro-peelable adhesive sheet X1 is attached to a conductive adherend having, for example, a metal adherend surface.

[0209] In an embodiment of the present invention, an electropenetrating adhesive sheet further comprises another adhesive layer, a second conductive substrate containing a resin component, and a second other adhesive layer, wherein the other adhesive layer is formed on the surface of the support substrate opposite to the conductive layer, and the second conductive substrate and the second other adhesive layer are formed in this order on the surface of the electropenetrating adhesive layer opposite to the conductive layer, and the electropenetrating adhesive layer and the second conductive substrate are in contact, another embodiment of the bonded body according to the present invention comprises an electropenetrating adhesive sheet according to the present invention and an adherend material, wherein the other adhesive layer is attached to the adherend material. The adherend material is selected from conductive materials and non-conductive materials.

[0210] Examples of the bonded bodies according to the embodiment of the present invention include a bonded body in which the other adhesive layers 2 on both sides of the electropenetrating adhesive sheet X3 are attached to a conductive material having, for example, a metal-adhering surface, and a bonded body in which either of the other adhesive layers 2 of the electropenetrating adhesive sheet X3 is attached to a non-conductive material. [Examples]

[0211] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0212] <Polymer synthesis> (Synthesis Example 1) A four-necked separable flask was equipped with a stirrer, thermometer, nitrogen tube, and water separator, 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 evaporating 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 approximately 24 hours to obtain a polyester polymer (Polyester A). As polycarboxylic acids, adipic acid (AD), sebacic acid (SB), and isophthalic acid (IP) were used in a molar ratio of AD:SB:IP = 3:21:26. Furthermore, as polyols, neopentyl glycol (NPG), 1,4-butanediol (BD), and 1,6-hexanediol (HD) were used in a molar ratio of 32:9:9. The weight-average molecular weight (Mw) of the polyester polymer (Polyester A) obtained in Synthesis Example 1 was 130,000, and its glass transition temperature (Tg) was -12°C.

[0213] (Synthesis Example 2) A polycarboxylic acid consisting of adipic acid (AD), sebacic acid (SB), and isophthalic acid (IP) was used in a molar ratio of AD:SB:IP = 3:12:35. A polyester polymer (Polyester B) was synthesized using the same method as in Synthesis Example 1, except that 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 (Polyester B) obtained in Synthesis Example 2 was 130,000, and its glass transition temperature (Tg) was -2°C.

[0214] (Synthesis Example 3) A polyester polymer (Polyester C) was synthesized using the same method as in Synthesis Example 1, except that adipic acid (AD), sebacic acid (SB), and isophthalic acid (IP) were used as polycarboxylic acids in a molar ratio of AD:SB:IP = 3:27:20, 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 (Polyester C) obtained in Synthesis Example 3 was 130,000, and its glass transition temperature (Tg) was -34°C.

[0215] (Synthesis Example 4) A polyester polymer (Polyester D) was synthesized in the same manner as in Synthesis Example 1, except that sebacic acid (SB) and isophthalic acid (IP) were used as polycarboxylic acids in a molar ratio of SB:IP = 40:10, 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 (Polyester D) obtained in Synthesis Example 4 was 130,000, and its glass transition temperature (Tg) was -48°C.

[0216] (Synthesis Example 5) A polyester polymer (Polyester E) was synthesized in the same manner as in Synthesis Example 1, except that sebacic acid (SB) and isophthalic acid (IP) were used as polycarboxylic acids in a molar ratio of SB:IP = 10:40, and neopentyl glycol (NPG), trimethylolpropane (TMP), 1,4-butanediol (BD), and 1,6-hexanediol (HD) were used as polyols in a molar ratio of 32:3:9:6. The weight-average molecular weight (Mw) of the polyester polymer (Polyester E) obtained in Synthesis Example 5 was 130,000, and its glass transition temperature (Tg) was 15°C.

[0217] (Synthesis Example 6) 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 77 parts by mass, isobornyl acrylate (IBXA): 20 parts by mass, acrylic acid (AA): 3 parts by mass) and 150 parts by mass of ethyl acetate as a polymerization solvent were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the mixture was heated to 63°C and reacted for 6 hours. Subsequently, ethyl acetate was added to obtain a polymer solution in which a polymer (BA / AA / IBXA = 77 / 3 / 20) with a solid content of 40% by mass was dissolved. The weight-average molecular weight of the obtained polymer was 750,000, and the glass transition temperature (Tg) was -28°C.

[0218] (Synthesis Example 7) A polymer (BA / AA / MEA = 87 / 3 / 10) was obtained by the same method as in Synthesis Example 6, except that n-butyl acrylate (BA): 87 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, and acrylic acid (AA): 3 parts by mass were used as monomer components. The weight-average molecular weight of the obtained polymer was 750,000, and the glass transition temperature (Tg) was -44°C.

[0219] (Synthesis Example 8) 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 67 parts by mass, N-acryloylmorpholine (ACMO): 20 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass) were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, 0.1 parts by mass of 1-hydroxycyclohexylphenyl ketone was added as a polymerization initiator, and the mixture was reacted for 15 minutes while stirring and irradiated with ultraviolet light at an intensity of 3 mW. Subsequently, a polymer solution in which a polymer with a solid content concentration of 5% by mass (BA / AA / ACMO / MEA = 67 / 3 / 20 / 10) was dissolved was obtained. The weight-average molecular weight of the obtained polymer was 3.1 million, and the glass transition temperature (Tg) was -25°C.

[0220] <Synthesis of tackifiers> (Synthesis Example 9) As monomer components, cyclohexyl methacrylate (CHMA): 95 parts by mass, acrylic acid (AA): 5 parts by mass, ethyl acetate: 300 parts by mass as polymerization solvent, and 2-mercaptoethanol (thioglycol): 3 parts by mass as chain transfer agent were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, 2,2'-azobisisobutyronitrile (AIBN): 0.2 parts by mass was added as polymerization initiator, the temperature was raised to 65°C and the reaction was carried out for 3 hours, followed by the reaction at 75°C for 2 hours to obtain an acrylic oligomer with a solid content of 25% by mass. The weight-average molecular weight of the acrylic oligomer was 4000.

[0221] <Preparation of adhesive composition> The polymers obtained above and additional components were added, stirred, and mixed to obtain the adhesive compositions of Examples 1 to 17 and Comparative Example 1. The amounts of each component are shown in Tables 1 and 2. Note that the values ​​for each component in Tables 1 and 2 represent parts by mass. Furthermore, the polymer content (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:

[0222] (Ionic substances) The following commercially available ionic liquids were used. 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. [Py13][FSI]: Cation: 1-propyl-1-methylpyrrolidinium cation, Anion: bis(fluorosulfonyl)imide anion, manufactured by Tokyo Chemical Industry Co., Ltd. [Emim][TCB]: Cation: 1-ethyl-3-methylimidazolium cation, Anion: Tetracyanobolate anion, manufactured by Sigma-Aldrich. [Emim][C(CN)3]: Cation: 1-ethyl-3-methylimidazolium cation, Anion: Tricyanomethanide, manufactured by Tokyo Chemical Industry Co., Ltd. [4MOP][TFSI]: Cation: 1-Octyl-4-methylpyridinium cation, Anion: Bis(fluorosulfonyl)imide anion, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. [N1444][FSI]: Cation: Tributylmethylammonium cation, Anion: Bis(fluorosulfonyl)imido anion, manufactured by Kanto Chemical Co., Ltd. [Hmim][FSI]: 1-Hexyl-3-methylimidazolium cation, Anion: Bis(fluorosulfonyl)imide anion, Trade name "HMI-FSI", Manufactured by Mitsubishi Materials Corporation

[0223] (Crosslinking agent) T / C: Polyfunctional epoxy resin (1,3-bis(N,N-diglycidylaminomethyl)cyclohexane), trade name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Company, Inc. Takenate D-101E: Trimethylolpropane / Tolylene diisocyanate trimer adduct, manufactured by Mitsui Chemicals, Inc. Takenate D-110N: Trimethylolpropane / xylylene diisocyanate adduct, manufactured by Mitsui Chemicals, Inc.

[0224] (Crosslinking catalyst) DBTDL: Dibutyltin dilaurate, manufactured by Tokyo Chemical Industry Co., Ltd. Nasem Ferric:Iron Trisacetylacetonate, manufactured by Nippon Chemical Industries, Ltd.

[0225] <Physical properties and evaluation>

[0226] [Tg of polymer] The above polymer solution was cast onto a peeling liner and dried to prepare a test sample (sheet-like polymer) with a thickness of approximately 2 mm. Approximately 3 to 10 mg of this test sample was weighed into an aluminum open cell, and the reversing heat flow (specific heat component) behavior of the polymer was obtained using a temperature-modulated DSC (product name "Q-2000," manufactured by T.A. Instruments) at a heating rate of 10°C / min under a nitrogen atmosphere of 50 ml / min. Referring to JIS K 7121 (2012), the temperature at which the polymer's Tg intersects with the curve of the stepwise transition portion of the glass transition is defined as the temperature at which the polymer's Tg intersects with a line equidistant in the vertical direction from the line extending from the baselines on the low and high temperature sides of the obtained reversing heat flow.

[0227] [Tg of the adhesive layer formed from the adhesive composition] Using the adhesive compositions of each example, measurement samples (adhesive layer samples) were prepared as follows, and the Tg was measured using temperature-modulated DSC in the same manner as the Tg measurement of the polymers described above.

[0228] (Manufacturing of measurement samples (adhesive layer samples)) Each example of the adhesive composition 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 3 minutes, the sheets were heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 50 μm.

[0229] [Ionic conductivity of the adhesive layer] Using the adhesive compositions 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.

[0230] (Manufacturing of measurement samples (joint samples)) Each example of the adhesive composition 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 3 minutes, the sheets were heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 50 μm. Next, 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 "1005CR", manufactured by Toray Film Processing Co., Ltd., thickness 12 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 the single-sided adhesive sheet with a substrate was peeled off, and a stainless steel plate (SUS316L (2B finish, calculated average roughness (Ra) 0.2 μm)) was attached to the peeled surface as an adherend, pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 25°C and 50% RH to obtain a bond consisting of stainless steel plate 6 / electro-peelable adhesive layer (adhesive sheet) 1' / metal-layered film (conductive substrate) 5'. An outline of the bond is shown in Figure 5.

[0231] (Measurement of capacitance and ionic conductivity) Capacitance and ionic conductivity were measured using a potentiometer / galvanostat (Biologic SP-300). Fitting was performed using the analysis function (ZFit) of computer software (EC-Lab V11.60). First, a DC voltage E=0V (vs, open-circuit voltage Eoc) and voltage amplitude Va=10mV were applied between the stainless steel plate and the metal layer surface of the metal-layered film of the bonded sample obtained using a potentiometer / galvanostat, and the frequency was varied from 10Hz to 200kHz to obtain a Cole-Cole plot. Here, the horizontal axis represents the real component of impedance, and the vertical axis represents the imaginary component. The shape of the semicircle in the obtained plot reflects the bulk response of the adhesive.

[0232] Next, the bulk response of the adhesive layer is the resistance (R adh ) and the parameters of the Constant Phase Element (CPE) (CPE-T:Q adh The circuit was modeled as a parallel circuit using the combination of CPE-P:α). The series resistance of the wiring was set to Rn, and the equivalent circuit of the junction sample was set as shown in Figure 6. The obtained Cole-Cole plot was fitted using the following equation (A) (ω: angular frequency, Z(ω): complex impedance at angular frequency ω, j: imaginary unit). The Q obtained by fitting was... adh By substituting α into equation (B) below, the capacitance C adh This is calculated.

[0233]

number

[0234] 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 equation (C).

[0235]

number

[0236] In equation (C), l is the thickness of the adhesive layer, and A is the area of ​​the adhesive surface of the adhesive layer.

[0237] [Initial adhesive strength] 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 3 minutes, the material was heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 60 μm. For Examples 5 and 13, the material was further heat-treated at 50°C for 72 hours. Next, 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 "1005CR", manufactured by Toray Film Processing Co., Ltd., thickness 12 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 the single-sided adhesive sheet with a substrate was peeled off, and a stainless steel plate (SUS316L (2B finish, calculated average roughness (Ra) 0.2 μm)) was attached to the peeled surface as an adherend, pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 25°C and 50% RH to obtain a bond consisting of stainless steel plate 6 / electro-peelable adhesive layer (adhesive sheet) 1' / metal-layered film (conductive substrate) 5'. For Example 9, a 2 kg roller After pressing once back and forth, the joint was pressed with a hot press (120°C, 0.35 MPa, 30 seconds) and left for 72 hours in an environment of 25°C, 50% RH. An overview of the joint is shown in Figure 5. Subsequently, the joint was peeled in the direction of the arrow in Figure 5 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 adhesion described in JIS Z 0237:2009. The measurement results are shown in Tables 1 and 2.

[0238] [Adhesive strength after voltage application] Before peeling, the positive and negative electrodes of a DC current machine were attached to points α and β in Figure 5 of the bonded body, respectively. Except for the point where the peel was performed immediately after applying a voltage of 10V for 30 seconds or 2V for 30 seconds, the adhesive strength after voltage application (i.e., adhesive strength after 10V 30s application or 2V 30s application) was measured in the same manner as the initial adhesive strength measurement described above. The adhesive strength after voltage application was calculated according to the method 1 for measuring peel-off adhesive strength described in JIS Z 0237:2009. The measurement results are shown in Tables 1 and 2.

[0239] [Adhesive strength reduction rate] Using the initial adhesive strength and the adhesive strength after voltage application measured by the method described above, the rate of decrease in adhesive strength due to voltage application (i.e., the rate of decrease in adhesive strength after 10V 30s application, or the rate of decrease in adhesive strength after 2V 30s 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 The measurement results are shown in Tables 1 and 2.

[0240] [Adhesion recovery rate] Before peeling, the positive and negative electrodes of a DC current machine were attached to points α and β in Figure 5 of the bonded body, respectively, and a voltage of 30V was applied for 30 seconds. After stopping the voltage application, a 2kg roller was pressed back and forth twice (roller movement speed: 10cm / s), and under room temperature (25℃) conditions, the adhesive strength was measured 2 minutes after stopping the voltage application and 15 minutes after stopping the voltage application, in the same manner as the initial adhesive strength measurement described above, except for the point where peeling occurred 2 minutes or 15 minutes after stopping the voltage application. The adhesive strength 2 minutes after stopping the voltage application and 15 minutes after stopping the voltage application were calculated according to the method 1 for measuring peelable adhesive strength described in JIS Z 0237:2009. The adhesive strength recovery rate was calculated using the initial adhesive strength, the adhesive strength 2 minutes after stopping the voltage application, and the adhesive strength 15 minutes after stopping the voltage application, using the following formula. Adhesion recovery rate after 2 minutes (%) = (Adhesion strength 2 minutes after voltage application is stopped / Initial adhesion strength) × 100 Adhesion recovery rate after 15 minutes (%) = (Adhesion strength 15 minutes after voltage application is stopped / Initial adhesion strength) × 100 The measurement results are shown in Tables 1 and 2.

[0241] [HSP value of polymers] The chemical structures of each monomer constituting the polymer when they form a homopolymer were converted into strings using SMILES notation and input into computer software (Hansen Solubility Parameters in Practice (HSPiP) Ver. 5.3.03) to determine the HSP values ​​when the monomers form a homopolymer. The HSP values ​​of the polymer (dispersion term (dDp), polarity term (dPp), hydrogen bonding term (dHp)) were determined from the HSP values ​​of each monomer when they form a homopolymer and the volume fraction of each monomer. For example, when monomer 1 and monomer 2 are randomly copolymerized in a volume fraction a:b, the HSP values ​​were calculated using the following formula with the dispersion term (dD1), polarity term (dP1), and hydrogen bonding term (dH1) of monomer 1's HSP value and the dispersion term (dD2), polarity term (dP2), and hydrogen bonding term (dH2) of monomer 2's HSP value.

[0242]

number

[0243] The volume fractions a and b of monomer 1 and monomer 2 were calculated from the weight fractions of monomer 1 and monomer 2, and the densities of monomer 1 and monomer 2 when they form homopolymers, as calculated by HSPiP.

[0244] [HSP value of cation reducers] The structure of the cation reducer was defined as follows, according to the "Definition of Cation Reducer" above. AS-110, [Emim][C(CN)3], [Emim][TCB]: 1-ethyl-3-methylimidazole-2-ylidene • [Py13][FSI]: 1-methylpyrrolidine • [4MOP][TFSI]: 4-methylpyridine • [Hmim][FSI]: 1-Hexyl-3-methylimidazole-2-ylidene • [N1444][FSI]: Dibutylmethylamine Next, the chemical structure of the cation reduction was converted into a string using SMILES notation. The converted chemical structure was then entered into computer software (Hansen Solubility Parameters in Practice (HSPiP) Ver. 5.3.03) to determine the HSP value of the cation reduction (dispersion term (dDc), polarity term (dPc), hydrogen bonding term (dHc)).

[0245] [HSP distance] The HSP distance between the polymer and the cation reducer was determined by substituting the HSP values ​​of the polymer (dispersion term (dDp), polarity term (dPp), hydrogen bonding term (dHp)) and the HSP values ​​of the cation reducer (dispersion term (dDc), polarity term (dPc), hydrogen bonding term (dHc)), calculated using the method described above, into the following formula.

number

[0246] The results are shown in Tables 1 and 2.

[0247] [Surface free energy of cation reduction] (1) MWt, density (ρ), and Parachor (P) were determined by inputting the chemical structure of the cation reduction into computer software (Hansen Solubility Parameters in Practice (HSPiP) Ver. 5.3.03) using SMILES notation. (2) Next, the surface free energy (γ) of the cation reduced product was calculated based on the following formula.

[0248]

number

[0249] The results are shown in Tables 1 and 2.

[0250] [Repeatability of electrolysis] Operation 1: Except for changing the conditions for attaching a stainless steel plate (SUS316L (2B finish, calculated average roughness (Ra) 0.2 μm) as the adherend to the adhesive layer surface of a single-sided adhesive sheet with a substrate to 30 minutes under conditions of 25°C and 50% RH, a bonded body consisting of a stainless steel plate 6 / electropenetrating adhesive layer (adhesive sheet) 1' / metal layered film (conductive substrate) 5' was obtained in the same manner as in "Production of measurement sample (jointed sample)" described above. Operation 2: In the same manner as the measurement of "adhesion strength after voltage application" described above, the single-sided adhesive sheet with the substrate (electro-peelable adhesive layer (adhesive sheet) 1' / metal layer film (conductive substrate) 5) was peeled off from the stainless steel plate. Operation 3: The joint was prepared in the same manner as in "Operation 1" above, except that the single-sided adhesive sheet with the substrate that was peeled off in Operation 2 was attached to another stainless steel plate, and the conditions for leaving it attached were changed to 5 minutes in an environment of 25°C and 50% RH. Operation 4: Repeat operations 2 and 3 three more times for a total of four times. The resulting bonded material was left to stand for another 25 minutes in an environment of 25°C and 50%RH. Then, using a peel tester (product name "YSP Variable Angle Peel Tester", manufactured by Asahi Seiko Co., Ltd.), the material was peeled in the direction of the arrow in Figure 5, and the adhesive strength in a 180° peel test (tensile speed: 300 mm / min, peel temperature: 25°C) was measured. In Operation 2, the condition where a voltage of 10V was applied for 30 seconds was defined as the adhesive strength [N / cm] when the voltage was not applied after four cycles of 10V 30s. Similarly, in Operation 2, the condition where a voltage of 2V was applied for 30 seconds was defined as the adhesive strength [N / cm] when the voltage was not applied after four cycles of 2V 30s. Regarding the peeling morphology of the electropenetrating adhesive layer, when the surface of the adherend (stainless steel plate) was touched after peeling off the electropenetrating adhesive layer, cases where there was no feel of adhesive (i.e., the electropenetrating adhesive layer had been completely peeled off) were judged as "interfacial failure," and cases where there was a feel of adhesive (i.e., the electropenetrating adhesive layer remained on the adherend during peeling) were judged as "anchoring failure." The results are shown in Tables 1 and 2. In Examples 1, 2, 4, 8, 10-12, 14, and 15 all exhibited "anchoring failure."

[0251] [Haze value of the adhesive layer] Each adhesive composition was coated onto a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) and dried to create an adhesive layer with a thickness of 50 μm. The obtained adhesive layer was bonded to a glass slide (for example, one with a total light transmittance of 92% and a haze of 0.2%), and then left to stand for at least 24 hours in an environment of 25°C and 50% RH to prepare a test specimen. Next, the haze value of the test specimen was measured using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150N") in a measurement environment of 25°C. Then, the haze value of the adhesive layer was calculated by subtracting the haze value of the glass slide from the measured value. The results are shown in Table 1.

[0252] [Table 1]

[0253] [Table 2]

[0254] The results in Tables 1 and 2 confirm that the present invention provides desirable electropenetrating adhesive properties. [Explanation of Symbols]

[0255] X0, X1, X2, X3 electro-peelable adhesive sheets 1,1' Electropeelable adhesive layer 2. Other adhesive layers 3 Supporting base material 4. Conductive layer 5,5' conductive substrate 6 Stainless steel plate

Claims

1. An adhesive composition comprising a polymer and an electrolyte, The electrolyte is such that the reduced product of the cation of the electrolyte is The HSP distance with the polymer is 9 MPa 0.5 The following: Surface free energy is 24 mJ / m 2 ~36mJ / m 2 That is It is, When a voltage of 30V is applied to the adhesive layer formed from the adhesive composition for 30 seconds, the adhesive strength recovery rate 2 minutes after the voltage application is stopped is less than 60%. The adhesive composition has an ionic conductivity of 0.02 μS / m or higher for the adhesive layer formed from the adhesive composition. The aforementioned ionic conductivity is given by the following formula Cmax = (Adhesion strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes (%)) × 0.445 + 10 The Cmax obtained is less than or equal to μS / m. An adhesive composition characterized by the following features.

2. The ionic conductivity of the adhesive layer is 5 μS / m or higher. The adhesive composition according to claim 1, characterized in that...

3. The aforementioned adhesive strength recovery rate after 2 minutes is 30% or less. The adhesive composition according to claim 1, characterized in that...

4. The aforementioned surface free energy is 25 mJ / m 2 ~30 mJ / m 2 That is The adhesive composition according to claim 1, characterized in that...

5. The polymer is one of an acrylic polymer, a polyester polymer, or a rubber polymer. The adhesive composition according to claim 1, characterized in that...

6. The polymer is a polyester polymer. The adhesive composition according to claim 1, characterized in that...

7. The adhesive composition according to claim 6, wherein the polyester polymer comprises monomer units derived from a dicarboxylic acid and monomer units derived from a diol, and the total proportion of monomer units derived from the dicarboxylic acid and monomer units derived from the diol in the total monomer units (100 mol%) constituting the polyester polymer is 90 mol% or more.

8. The adhesive composition according to claim 7, characterized in that the proportion of monomer units derived from aromatic dicarboxylic acid to the total amount (sum) of the dicarboxylic acid is 45 mol% or more.

9. The adhesive composition according to claim 8, characterized in that the proportion of monomer units containing aromatic rings in the total monomer units (100 mol%) constituting the polyester polymer is greater than 20 mol%.

10. The polymer is an acrylic polymer. The adhesive composition according to claim 1, characterized in that...

11. The adhesive composition according to claim 10, characterized in that the glass transition temperature of the adhesive layer formed from the adhesive composition is -30°C or higher.

12. The electrolyte is an ionic liquid. The adhesive composition according to claim 1, characterized in that...

13. The amount of electrolyte added to the adhesive composition is 10 parts or less based on the mass of the polymer. The adhesive composition according to claim 1, characterized in that...

14. The adhesive composition according to claim 1, for use in fixing components in electrical and electronic equipment.

15. The adhesive composition according to claim 1, characterized in that the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition is less than 15% after 15 minutes when a voltage of 30V is applied for 30 seconds and the voltage application is stopped.

16. The adhesive composition according to claim 15, characterized in that the haze value of the adhesive layer formed from the adhesive composition is 30% or less.

17. The adhesive composition according to claim 1, characterized in that the ionic conductivity is less than 1 μS / m.

18. The adhesive composition according to claim 12, characterized in that the ionic liquid has an anion Lewis basicity of 0.2 or less or 0.27 or more and 0.60 or less.

19. The adhesive composition according to claim 1, characterized in that the content of a compound having a polyoxyalkylene skeleton is less than 1% by mass.

20. An electropenetrating adhesive sheet comprising an electropenetrating adhesive layer formed from the adhesive composition according to any one of claims 1 to 19.

21. The present invention further comprises a conductive substrate having at least one conductive surface, The electropenetrating adhesive sheet according to claim 20, characterized in that the conductive surface of the conductive substrate and the adhesive layer are in contact.

22. The electropenetrating adhesive sheet according to claim 21, further comprising another adhesive layer, characterized in that the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer.

23. The device further comprises another adhesive layer, a second conductive substrate having at least one conductive surface, and a second other adhesive layer. On the surface of the conductive substrate opposite to the adhesive layer, the other adhesive layer, the second conductive substrate, and the second other adhesive layer are formed in this order. The electropenetrating adhesive sheet according to claim 21, characterized in that the conductive surface of the second conductive substrate and the adhesive layer are in contact.

24. The electropenetrating adhesive sheet according to claim 21, characterized in that the conductive substrate has protrusions that protrude in the planar direction from the adhesive layer.

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

26. A bonded body comprising the adhesive sheet described in claim 21 and a conductive material, wherein the adhesive layer is attached to the conductive material.

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