Adhesive composition, adhesive sheet, and bonded body

Abstract

The present invention provides an adhesive composition which is capable of achieving an initial adhesive force necessary for bonding, while achieving a large adhesive force reduction rate since the adhesive force after voltage application is extremely small, and having excellent electrical peeling performance.　The present invention specifically provides an adhesive composition which contains a polymer and an electrolyte, wherein: the HSP distance between a reduced product of a cation of the electrolyte and the polymer is 2.5 MPa0.5 to 5.0 MPa0.5; and the ionic conductivity of an adhesive layer that is formed of the adhesive composition is 5.0 µS / m or more; and the adhesive force recovery rate after two minutes of an adhesive layer that is formed of the adhesive composition is 60% or more.

Description

Adhesive Composition, Adhesive Sheet, and Bonded Body

[0001] The present invention relates to an adhesive composition, an adhesive sheet including an adhesive layer formed from the adhesive composition, and a bonded body of the adhesive sheet and an adherend.

[0002] Conventional adhesives have been required to adhere strongly so that they are difficult to peel off after adhesion to an adherend is once completed. On the other hand, adhesives that are required to be easily peeled off even after adhesion to an adherend is once completed have inherently weak adhesive strength. When adhesion to an adherend is completed, strong adhesion is achieved and long-term reliability of adhesiveness is ensured. On the other hand, the development of adhesives that can be re-peeled, in which easy disassembly is exhibited when a predetermined peeling trigger is given, has been carried out. Such triggers include mechanical energy, thermal / ultraviolet (UV) energy, electrical energy, and the like.

[0003] As an application of an adhesive that can be re-peeled using electrical energy as a trigger, there is an electrically detachable tape. The electrically detachable tape can be strongly adhered to an adherend, can be easily peeled off by applying a voltage to the electrically detachable tape, and the adhesive strength is restored when the voltage is removed. As a double-sided adhesive sheet for an electrically detachable tape that realizes adhesive strength and peelability, an ionic liquid composed of a cation and an anion is added to a component such as a polymer constituting the adhesive composition, and a voltage is applied to an adhesive layer formed of the adhesive composition. Thus, an adhesive sheet (electrically detachable adhesive sheet) capable of peeling off the adhesive sheet adhered to an adherend is known (Patent Documents 1 to 3). In the electrically detachable adhesive sheets of Patent Documents 1 to 3, when a voltage is applied to the electrically detachable adhesive sheet, on the cathode side of the electrodes for applying the voltage, the cations of the ionic liquid in the adhesive composition move and reduction occurs, and on the anode side, the anions of the ionic liquid move and oxidation occurs, and it is considered that the adhesive strength at the adhesion interface becomes weak and peeling becomes easy.

[0004] JP-A-2010-037354, Patent No. 6097112, Patent No. 4139851

[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.

[0006] As a result of diligent research, the present 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), which led to the present invention.

[0007] In other words, the present invention relates to an adhesive composition comprising a polymer and an electrolyte, wherein the HSP distance between the reduced cation of the electrolyte and the polymer is 2.5 MPa. 0.5 ~5.0 MPa 0.5 The adhesive composition is characterized in that the ionic conductivity of the adhesive layer formed from the adhesive composition is 5.0 μS / m or more, and the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is 60% or more.

[0008] The surface free energy of the reduced cation of the aforementioned electrolyte is 25 mJ / m². 2 ~35 mJ / m 2It is desirable that the adhesive layer has an ionic conductivity of 15 μS / m or more. It is desirable that the adhesive strength recovery rate is 80% or more. In the adhesive composition according to the present invention, it is desirable 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 desirable that the polymer is an acrylic polymer. It is desirable that the glass transition temperature of the acrylic polymer is -30°C or lower. It is desirable that the weight-average molecular weight of the acrylic polymer is 1 million or less. In the adhesive composition according to the present invention, it is desirable that the gel fraction of the adhesive layer formed from the adhesive composition is 70% or more. It is desirable that the proportion of monomers with a homopolymer glass transition temperature of 0°C or higher relative to the total monomer components (100% by mass) constituting the acrylic polymer is 2% by mass or more and 13% by mass or less. In the adhesive composition according to the present invention, it is desirable 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 is 85% or less. 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. 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. The present invention further relates to an electropenetrating adhesive sheet comprising an electropenetrating adhesive layer formed from the above-mentioned adhesive composition. In the electropenetrating adhesive sheet according to the present invention, it is desirable that the sheet further comprises a conductive substrate having at least one conductive surface, and that the conductive surface of the conductive substrate and the adhesive layer are in contact.In the electropenetrating adhesive sheet according to the present invention, it is preferable that the electropenetrating adhesive 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, it is preferable that the electropenetrating adhesive 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 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 preferable that the conductive substrate has a protrusion that protrudes in the surface direction from the adhesive layer. The present invention further comprises the electropenetrating adhesive sheet and a conductive material, wherein it is preferable that the adhesive layer is a bonded body attached to the conductive material.

[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.

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

[0011] The adhesive composition according to the present invention is an adhesive composition comprising a polymer and an electrolyte, wherein the HSP distance between the reduced cation of the electrolyte and the polymer is 2.5 MPa. 0.5 ~5.0 MPa 0.5The adhesive composition is characterized in that the ionic conductivity of the adhesive layer formed from the adhesive composition is 5.0 μS / m or higher, and the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is 60% or higher.

[0012] [Electro-peelable adhesive sheet] [Structure of electro-peelable adhesive sheet] The adhesive composition of the present invention is an adhesive composition used exclusively for electro-peeling, and can be, for example, an electro-peelable adhesive composition described later, and can be an electro-peelable adhesive sheet comprising an electro-peelable adhesive layer formed from such an electro-peelable 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, for example. 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] An 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 include other adhesive layers that do not have electropenetrating properties, for example, an electropenetrating adhesive sheet having 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, an electropenetrating adhesive sheet may be a double-sided electropenetrating adhesive sheet having conductive layers on both sides of a support substrate, with an electropenetrating adhesive layer on each conductive layer. An electropenetrating adhesive sheet may have a release liner for the purpose of protecting the surfaces of the electropenetrating adhesive layer and other adhesive layers, but such release liner is not included in the electropenetrating 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 metal-based substrate containing metal-based materials such as metal foil (e.g., aluminum, magnesium, copper, iron, tin, gold, etc.), metal plates (e.g., aluminum, magnesium, copper, iron, tin, silver, etc.), a metal-based substrate made of an alloy mainly composed of the metals exemplified above, a layer formed from conductive materials such as conductive polymer (e.g., a composite made of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid), conductive carbon (e.g., graphene, carbon composed of carbon atoms having sp2 and sp3 bonds), conductive carbon, etc., or conductive carbon, and 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 alloys, etc.)) provided on the support substrate 4 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 a mixture of two 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, even more preferably 0.5 μm, and 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, even more preferably 0.05 μm. When the conductive layer 4 is a metal plating layer, sputter layer or vapor deposition film provided on the support substrate 3, 0.001 μm or more and 1 μm or less is preferable. 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, even 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, more preferably 0.003 μm or more. Also, 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 3 Ω / sq or less. The surface resistance value 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 layer 4. Also, the surface resistance value of the conductive layer 4 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, 5.0×10 2It can also 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 / □.

[0024] The supporting substrate 3 is not particularly limited, but examples include paper-based substrates such as paper, fibrous substrates such as cloth and nonwoven fabric, plastic 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 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, even more preferably 40 μm, and the lower limit is more preferably 12 μm, 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, substrates containing conductive fillers in foam substrates of various plastics as described 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. The surface resistance value when the conductive substrate is a single-layer or laminated structure of conductive material 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 3 can be selected according to the intended use and usage conditions, i.e., the conditions of the applied voltage required for electrolysis. For example, 5.0 × 10 2 It can also 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] The electropenetrating adhesive sheet can be attached to a conductive material to form a bonded body. The description of the conductive material that can be used for the conductive layer 4 described above can be directly applied to the conductive material. For example, the adherend can be a metal adherend, and the metal adherend can be a surface made of a metal mainly composed of aluminum, copper, iron, magnesium, tin, gold, silver, and lead, and among these, a surface made of a metal containing aluminum is preferred. 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 its adherend surface. The description of the conductive material that can be used for the conductive layer 4 described above can be directly applied to the conductive layer provided on the non-conductive material adherend. 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. In this embodiment, the coating layer acts as a barrier to the electrolyte contained in the electrorelease adhesive layer entering the conductive layer when a voltage is applied, thereby preventing the conductive layer from peeling off the substrate. Furthermore, the coating layer being in contact with the electrorelease adhesive layer improves the adhesion between the electrorelease adhesive layer and the conductive layer, preventing the interfacial adhesion between the electrorelease adhesive layer and the conductive substrate from decreasing and causing peeling within the adhesive sheet due to thermal curing of the electrorelease adhesive layer exposed to a high-temperature environment.

[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 may be made from 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 to Low-Polarity Adherents] 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. Generally, the adhesive strength to low-polarity adherends 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 Adhesion] When the adherend is metal, there is a possibility of appearance defects due to corrosion of the adherend by the adhesive composition. The method for evaluating the corrosiveness of metal adherends by the adhesive composition can be appropriately set depending on the type of metal adherend and the manner of use, but for example, it can be calculated as follows: the corrosion rate of aluminum (area of ​​the corroded part / 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. Then, the release liner is peeled off the single-sided adhesive sheet with the substrate, and the peeled surface is attached to a metal plate (aluminum plate A5052) as the adherend, and pressed once back and forth with a 2 kg roller, and left for 72 hours in an environment of 23 ± 12 °C and 50 ± 5% RH to obtain a bonded body consisting of a metal plate / electro-peelable adhesive layer (adhesive sheet) / metal-layered film. The obtained bonded body is left to stand in a constant temperature bath at a temperature of 85 °C and humidity of 85% RH for 500 hours, and then the single-sided adhesive sheet with the substrate is peeled off from the metal plate. The delaminated surface 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 photography is performed indoors, with a shadow created using black paper to prevent direct light from hitting the surface.The captured image is 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 following calculation is performed on the binarized image using the aforementioned software to calculate the corrosion rate (%). Corrosion rate [%] = [(Area of ​​dark-colored objects) / (Area of ​​light-colored objects + Area of ​​dark-colored objects)] × 100 A smaller corrosion rate means that the metal plate is not corroded, that is, it means that the adhesive composition can form an adhesive layer in which metal corrosion is less likely to occur. The corrosion rate of the adhesive composition evaluated in this way 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 there is little corrosion of the metal adherend, a voltage can be stably 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 energy level of the HOMO and the lower the energy level of the LUMO 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 electro-peelable adhesive layer 1 is an adhesive layer that has the property of decreasing adhesive strength when a voltage is applied. The electro-peelable adhesive layer contains a polymer that acts as an adhesive, and an electrolyte that 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. At room temperature (25°C), ionic substances can be in any state other than gas. That is, at room temperature (25°C), ionic substances may be solid, liquid, or in an intermediate state between solid and liquid (e.g., liquid crystal, flexible crystal, viscous solid, viscous liquid). The state in which an ionic substance is 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 a melting point above 25°C and are ionic, 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 an electrolytic adhesive composition, a composition consisting of components other than ionic substances which are electrolytes may be referred to as an "ionic substance-free adhesive composition." Furthermore, an adhesive layer formed by an ionic substance-free adhesive composition may be referred to as an "ionic substance-free adhesive layer." In addition, the property of adhesive strength decreasing when voltage is applied is called "electrorelease property," and a large decrease in adhesive strength due to voltage application may be referred to as "excellent electrorelease properties."

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

[0037] (Polymer) The adhesive composition according to the 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 monomer polymer or partial polymer. The monomer may be a single monomer or a mixture of two or more monomers. A partial polymer means a polymer in which at least a part of the monomer or monomer mixture is partially polymerized.

[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 polymer can be used alone or in combination of two or more. In order to increase the dielectric constant of the components other than ionic substances in the resulting electropeelable adhesive layer and improve electropeelability, 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 easily polarizable hydroxyl groups at their ends, and since the carboxyl groups and / or hydroxyl groups of acrylic polymers have easily polarizable carboxyl groups and / or hydroxyl groups, 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 polymers according to the embodiments of the present invention is preferably 60% by mass or more, and more preferably 80% by mass or more. In particular, in order to increase cost, productivity, and initial adhesive strength, the polymer in this embodiment is preferably an acrylic polymer. That is, the adhesive composition according to the embodiments of the present invention is preferably an acrylic electrolytic adhesive composition containing an acrylic polymer as the polymer.

[0039] In this specification, "acrylic polymer" refers to a polymer that includes a constituent unit derived from a monomer having at least one (meth)acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule will also be referred to as an "acrylic monomer." Therefore, in this specification, an acrylic polymer is defined as a polymer that includes monomer units derived from an acrylic monomer. 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). Also 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 monomers as used here can 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 used. 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 becomes 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)acrylic acid esters 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. In particular, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred. Hydroxyl group-containing monomers can be used alone 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. A polyfunctional monomer content of 0.1% by mass or more is preferable because it easily improves the flexibility and adhesion of the electrorelease 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 monomers whose homopolymer Tg is 0°C or higher. The homopolymer Tg is preferably 0°C to 200°C, more preferably 5°C to 180°C, and even more preferably 10°C to 160°C. Including monomers whose homopolymer Tg is 0°C or higher is preferable from the viewpoint of facilitating the realization of an adhesive layer having a moderate 2-minute adhesion recovery rate (e.g., 60% to 90%). As monomers whose homopolymer Tg is 0°C or higher, it is preferable to include at least one selected from the group consisting of alkyl (meth)acrylate esters having linear alkyl groups having C1 to C3, alkyl (meth)acrylate esters having branched alkyl groups having C3 or C4, cyclic nitrogen-containing monomers, and alicyclic structure-containing monomers. The monomers whose homopolymer Tg is 0°C or higher can be used alone or in combination of two or more types.

[0062] Examples of alkyl (meth)acrylate esters having a linear alkyl group with 1 to 3 carbon atoms include methyl acrylate (Tg: 8°C) and methyl methacrylate (Tg: 105°C), with methyl methacrylate being particularly preferred.

[0063] As an alkyl (meth)acrylate having a branched alkyl group with 3 or 4 carbon atoms, t-butyl acrylate (Tg: 14°C) is particularly preferred.

[0064] The cyclic nitrogen-containing monomers 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 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.

[0065] The above-mentioned monomers containing an alicyclic structure 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 also has an alicyclic structure, without any particular limitations. Examples of monomers containing an alicyclic structure include (meth)acrylic monomers such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate (Tg: 15°C), cyclohexyl methacrylate (Tg: 66°C), cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl (meth)acrylate (Tg: 97°C), isobornyl methacrylate (Tg: 180°C), dicyclopentanyl (meth)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 alicyclic structure-containing monomers may be used individually or in combination of 22 or more types.

[0066] The lower limit of monomers whose homopolymer Tg is 0°C or higher relative to the total monomer components (100% by mass) constituting the acrylic polymer is preferably 1% by mass or more, preferably 2% by mass or more, may be 3% by mass or more, may be 4% by mass or more, may be 5% by mass or more, or may be 6% by mass or more, from the viewpoint of making it easier to realize an adhesive layer having an appropriate adhesive strength recovery rate after 2 minutes (for example, 60% to 90%). The upper limit of the proportion of monomers whose homopolymer Tg is 0°C or higher is preferably 20% by mass or less, more preferably 15% by mass or less, more preferably 13% by mass or less, even more preferably 12% by mass or less, may be 10% by mass or less, or may be 8% by mass or less, from the viewpoint of making it easier to realize an adhesive with increased flexibility and good initial adhesive strength. In particular, if the proportion of monomers with a ring-paired homopolymer Tg of 0°C or higher relative to the total monomer components constituting the acrylic polymer (100% by mass) is 2% by mass or more and 12% by mass or less, it becomes easier to achieve both good initial adhesion and a moderate adhesion recovery rate after 2 minutes (for example, 60% to 90%).

[0067] 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.

[0068] The polycarboxylic acid monomers are not particularly limited, but examples include adipic acid, azelaic acid, dimer acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenyl succinic anhydride, fumaric acid, succinic acid, dodecanediic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, citraconic acid, and derivatives thereof. The polycarboxylic acid monomers can be used alone or in combination of two or more types.

[0069] The polyhydric alcohol monomer is not particularly limited, but examples include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, and derivatives thereof. The polyhydric alcohol monomer can be used alone or in combination of two or more types.

[0070] 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. By including an ionic polymer in the polymer, the dielectric constant of the polymer increases, and the electrolytic properties are improved. When the polymer contains an ionic polymer, the content of the ionic polymer is preferably 0.05 parts by mass or more and 2 parts by mass or less per 100 parts by mass of the polymer.

[0071] 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. When copolymerized, the polymer may be a random copolymer, block copolymer, alternating copolymer, graft copolymer, etc.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] Polymerization initiators used in solution polymerization are not particularly limited, but include peroxide-based polymerization initiators and azo-based polymerization initiators. Peroxide-based polymerization initiators are not particularly limited, but include peroxycarbonates, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, and peroxyesters. More specifically, examples include benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane. Azo polymerization initiators are not particularly limited, but include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionic acid)dimethyl, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis(2,4,4-trimethylpentane), and 4,4'-azobi Examples include s-4-cyanovaleric acid, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethylene isobutylamidine)hydrochloride, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate. Polymerization initiators can be used alone or in combination of two or more.

[0076] The amount of polymerization initiator used is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to the total monomer components constituting the polymer (100 parts by mass). The upper limit of the amount of polymerization initiator used is more preferably 3 parts by mass, and the lower limit is more preferably 0.05 parts by mass.

[0077] In solution polymerization, the heating temperature during polymerization is not particularly limited, but is, for example, 50°C to 80°C. The heating time is not particularly limited, but is, for example, 1 hour to 24 hours.

[0078] 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.

[0079] 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.

[0080] 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. 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 "Omnirad 651," manufactured by IGM Resins B.V.), anisoin methyl ether, etc. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone (trade name "Omnirad 184", manufactured by IGM Resins B.V.), 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.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. Acylphosphine oxide-based photopolymerization initiators include, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0081] The amount of photopolymerization initiator used is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to the total monomer components (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.

[0082] The polymerization rate of the prepolymer is not particularly limited, but from the viewpoint of achieving a viscosity suitable for coating onto 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

[0083] The weight-average molecular weight of the polymer is not particularly limited, but is preferably between 100,000 and 5,000,000. The upper limit of the weight-average molecular weight is more preferably 4,000,000, even more preferably 3,000,000, and may be 2,000,000 or less, or 1,000,000 or less. The lower limit is more preferably 200,000, and even more preferably 300,000. When the weight-average molecular weight is 100,000 or more, the cohesive force is reduced, which effectively suppresses the problem of adhesive residue remaining on the adherend surface after the electro-peelable 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 adherend surface after the electro-peelable adhesive layer is peeled off. In some embodiments, from the viewpoint of facilitating the realization of an adhesive layer having an appropriate 2-minute adhesive strength recovery rate (e.g., 60% to 90%), the weight-average molecular weight of the polymer contained in the adhesive composition is preferably 400,000 or more, more preferably 600,000 or more, even more preferably 2,000,000 or more, may be 3,000,000 or more, or may be 4,000,000 or more. In other embodiments, in terms of facilitating the formation of an adhesive layer with a moderately high diffusion rate of the cation reduction into the adhesive bulk, and facilitating the realization of an adhesive layer with an adhesion recovery rate of 60% or more and 80% or less after 2 minutes, the weight-average molecular weight of the polymer contained in the adhesive composition is preferably 1 million or more, more preferably 1.5 million or more, even more preferably 2 million or more, particularly preferably 2.3 million or more, and may also be 2.5 million or more, or 2.7 million or more.

[0084] The weight-average molecular weight was obtained by measuring using gel permeation chromatography (GPC). More specifically, for example, using a GPC measuring device such as the "HLC-8220GPC" (manufactured by Tosoh Corporation), the measurement was performed under the following conditions, and the value was calculated based on the standard polystyrene equivalent. (Weight-average molecular weight measurement conditions) ・Sample concentration: 0.2% by mass (tetrahydrofuran solution) ・Sample injection volume: 10 μL ・Sample column: TSKguardcolumn SuperHZ-H (1 tube) + TSKgel SuperHZM-H (2 tubes) ・Reference column: TSKgel SuperH-RC (1 tube) ・Eluent: Tetrahydrofuran (THF) ・Flow rate: 0.6 mL / min ・Detector: Differential refractometer (RI) ・Column temperature (measurement temperature): 40°C ・Standard sample: Polystyrene (manufactured by Agilent)

[0085] The glass transition temperature (Tg) of the polymer is not particularly limited, but 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 preferred when it is -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. In some embodiments, from the viewpoint of making it easier to realize an adhesive layer having a moderate adhesive strength recovery rate after 2 minutes (for example, 60% to 90%), the glass transition temperature (Tg) of the polymer is preferably -50°C or higher, more preferably -45°C or higher, even more preferably -40°C or higher, and may be -35°C or higher, or -30°C or higher. Furthermore, the glass transition temperature (Tg) of the adhesive composition formed from the electrorelease adhesive composition is not particularly limited, but 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, a temperature of -40°C or lower is particularly preferable because the rate of decrease in adhesive strength due to voltage application is particularly large, and most preferably -50°C or lower. In some embodiments, from the viewpoint of facilitating the realization of an adhesive layer having a moderate adhesive strength recovery rate after 2 minutes (for example, 60% to 90%), the glass transition temperature (Tg) of the adhesive layer is preferably -50°C or higher, more preferably -45°C or higher, even more preferably -40°C or higher, and may be -35°C or higher, or -30°C or higher. Also, from the viewpoint of facilitating the formation of an adhesive layer with a high diffusion rate of cationic reduced substances into the adhesive bulk, and facilitating the realization of an adhesive layer with an adhesive strength recovery rate of 60% or higher after 2 minutes, the polymer contained in the adhesive composition in this embodiment is an acrylic polymer, and the glass transition temperature (Tg) of the polymer is preferably -30°C or lower, more preferably -35°C or lower, may be -37°C or lower, may be -40°C or lower, or may be -42°C or lower.

[0086] 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 baseline and high-temperature baseline 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.

[0087] 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.

[0088] (Electrolyte (Ionic Substance)) 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. In some embodiments, it is preferable to use an adhesive that substantially does not contain a substance metal salt (such as sodium chloride or lithium bis(fluorosulfonyl)imide) with a melting point higher than 25°C. Here, substantially does not contain means that the amount of metal salt in the adhesive layer formed from the adhesive composition is less than 1% by mass, and 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 solid contaminants on the surface of the adherend after the electropenetrating adhesive layer is peeled off by applying a voltage, so the adherend can be easily reused after the adhesive layer is peeled off.

[0089] 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, (FSO2)2N is a notable anion. - [Bis(fluorosulfonyl)imide 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 improving electrolysis. In other words, the anion of the ionic substance is generally selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion.

[0090] 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.

[0091] 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.

[0092] 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 processes by which corrosion products are generated include the following (1) to (3): (1) Anions from ionic substances destroy the oxide film (hereinafter also called the "passivation film") on the surface of the base metal. (2) An oxidation reaction occurs on the exposed base metal surface, and base metal cations are generated (simultaneously, oxygen in the system accepts water and electrons, forming hydroxide ions (OH) - A reduction reaction occurs that produces (O2 + H2O + 2e - →2OH -(3) The base metal cation and the anion of the ionic substance interact to form corrosion products (in this specification, "corrosion products" means complexes formed by the interaction of the base metal cation and the anion of the ionic substance).

[0093] 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.

[0094] 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.

[0095] 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 occurrence of corrosion is not observed.

[0096] Corroded areas can be observed visually as changes in appearance such as loss of metallic luster or discoloration. Furthermore, in the corrosion rate evaluation described above, 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 formed coatings are not observed as dark-colored objects using computer software (Image J ver. 1.54d) in the corrosion rate evaluation described above. A larger area of ​​corrosion, i.e., a higher corrosion rate, indicates a greater degree of metal corrosion. In a bonded structure using an electropenetrating adhesive layer, if the degree of corrosion of the metal, such as the conductive substrate or adherend, is high, there is a risk that a stable voltage cannot be applied to the electropenetrating adhesive layer.

[0097] Further investigation by the present inventors revealed that the solubility of corrosion products in the electropenetrating adhesive layer correlates 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 theory, the Lewis basicity of the anions of ionic substances is a parameter that correlates with the hydrophilicity of the anions, and thus correlates with the solubility of the ionic substances in the dispersion medium. When a substance has a specific range of hydrophilicity, the solubility of the ionic substance in the polymer tends to be particularly high. Here, when an electropenetrating 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 considered to be composites of base metal cations and anions of the ionic substances contained in the electropenetrating adhesive layer. That is, under these conditions, the solubility of the corrosion products in the polymer is considered to correlate with the Lewis basicity of the anions of the ionic substances contained in the electropenetrating adhesive composition constituting the electropenetrating adhesive layer, according to the mechanism described above.

[0098] As a result of further intensive research by the present inventors, it has been found 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 described above, if corrosion products are not easily soluble in the electropenetrating adhesive layer, corrosion is less likely to occur. The solubility of corrosion products in the electropenetrating adhesive layer is thought to be correlated with the Lewis basicity of the anions of the ionic substances contained in the electropenetrating adhesive composition that constitute the electropenetrating adhesive layer. Here, it was found that when the ionic substance has a Lewis basicity within a predetermined range, the solubility of the ionic substance in the polymer tends to be low. Specifically, it was found that when the Lewis basicity of the anions of the ionic substance is low or moderate, that is, in a region of high or moderate hydrophobicity, the solubility of the ionic substance in the polymer tends to be low. For this reason, it is thought that corrosion is less likely to occur in a region where the Lewis basicity of the anions of the ionic substance is low or moderate, because the solubility of corrosion products is low. Furthermore, if the Lewis basicity of the anion is too high (too hydrophilic), it is thought that corrosion will progress due to a high water content in the adhesive layer.

[0099] Based on these findings, the electrolytic adhesive composition obtained contains an ionic substance whose anion has a Lewis basicity of 0.02 or more, or 0.27 or more and 0.60 or less. The Lewis basicity of the anion being 0.02 or more, or 0.27 or more and 0.60 or less, is suitable for realizing an electrolytic adhesive layer that has good electrolytic properties while being less likely to cause metal corrosion even when placed in a high temperature and high humidity environment in contact with the 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 more, or 0.27 or more and 0.60 or less, preferably 0.01 or more and 0.20 or less, or 0.27 or more and 0.50 or less, preferably 0.01 or more and 0.20 or less, or 0.28 or more and 0.45 or less, and more preferably 0.01 or more and 0.10 or less, or 0.28 or more and 0.42 or less. 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). Anions with a Lewis basicity of 0.27 or more and 0.60 or less are, for example, tricyanomethanide (TCM) and tetracyanoborate (TCB).

[0100] The Lewis basicity of anions in ionic substances is obtained by measurement using nuclear magnetic resonance (NMR), and more specifically, it refers to the value obtained by measurement using an NMR apparatus under the following conditions. (Measurement of Lewis basicity of anions in ionic substances) The ionic substance, 4-fluorophenol, and 4-fluoroanisole are weighed separately, and solution 1 is prepared so that the concentration of 4-fluorophenol is 0.01 mol / L or less, and solution 2 is prepared so that the concentration of 4-fluoroanisole is 0.1 mol / L or less. The solvent used to prepare the solutions is selected according to the properties of the ionic substance. If the ionic substance is an ionic liquid, the ionic liquid itself is used as the solvent. On the other hand, if the ionic substance is not an ionic liquid, a 1,2-dichloroethane solution containing 4% by mass of the ionic substance is prepared and used as the solvent. These two solutions (solution 1 and solution 2) are placed inside separate double NMR tubes, and deuterated chloroform in which hexafluorobenzene is dissolved is placed outside 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 the anion of the ionic substance was calculated according to the following formula: β1 = {δ(19F)(OH) - δ(19F)(OMe)} / 3.041, where 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.

[0101] 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.

[0102] 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 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.

[0103] 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.

[0104] Examples of pyrrolidinium-based cations include 1-ethyl-1-methylpyrrolidinium cation, 1-propyl-1-methylpyrrolidinium cation, and 1-butyl-1-methylpyrrolidinium cation.

[0105] Examples of ammonium cations include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, tributylmethylammonium cation, and (2-acryloyloxyethyl)trimethylammonium cation.

[0106] 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 (FSO2)2N-[bis(fluorosulfonyl)imide anion] or (CF3SO2)2N - Ionic substances containing a [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.

[0107] Furthermore, cations represented by the following formulas (2-A) to (2-D) are also commonly used as cations of ionic substances.

[0108]

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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 even 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 electropenetrateable. 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 the ionic substance 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 even more preferably 10 parts or more, based on the mass of polymer in the adhesive composition. This is because it is expected that the electropenetration properties of the electropenetrate will be improved and the impact resistance will be improved by the plasticization of the polymer.

[0115] Examples of commercially available ionic substances include "Elexel AS-110" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "E1452", "E0599", "M2098", "M2980", "M2981", and "M2998" manufactured by Tokyo Kasei Kogyo Co., Ltd., "HMI-FSI" manufactured by Mitsubishi Materials Corporation, and "CIL-312" and "CIL-313" manufactured by Nippon Carlit Co., Ltd.

[0116] [Mechanism of Electrolysis] In electrolysis adhesive sheets, when a voltage is applied, cations of the electrolyte (ionic substance) move on the cathode side, causing reduction, and anions of the ionic substance move on the anode side, causing oxidation. This weakens the adhesive strength at the bonding interface, making it easier to peel off. Although not bound by any theory, when a voltage is applied to an electrolysis adhesive sheet, it is thought that the higher the ionic conductivity of the adhesive layer, which is composed of an adhesive composition 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 possibility of improved electrolysis. Next, the cations that have moved to the cathode side undergo a reduction reaction to become their reduced form (cation reduced form). 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 is repeated, the reduced form accumulates at the interface. It is thought that the smaller the proportion (or speed) at which the cation reduced form diffuses into the bulk, the higher the electrolysis. Conversely, if the rate (or speed) of cation reduction diffusing into the bulk is high, to achieve high electropenetration, it is considered necessary to increase the mobility of cations in the electrolyte to the interface (i.e., to increase the ionic conductivity of the adhesive layer). Furthermore, if the solubility of the reduced material accumulated at the interface is within a certain range, it becomes easier to peel the adhesive layer from the adherend.

[0117] [Ionic Conductivity of the Adhesive Layer] The ionic conductivity of the polymer contained in the adhesive composition according to the present invention is 5.0 μS / m or higher. Preferably, the ionic conductivity is 10 μS / m or higher, more preferably 15 μS / m or higher, and even more preferably 20 μS / m or higher. The adhesive composition according to the present invention contains a polymer and an electrolyte, and generally, the lower the Tg of the polymer, the higher the ionic conductivity of the adhesive layer made from the adhesive composition tends to be. Also, 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 made from the adhesive composition tends to be high. In order to exhibit ionic conductivity, the polymer and electrolyte (ionic substance) contained in the adhesive composition constituting the adhesive layer must be compatible. For example, by using a polymer in which a second polymer, which is immiscible with the first polymer and the ionic substance, is added in a smaller amount than the first polymer, the concentration of the ionic substance in the first polymer phase can be increased, which is thought to contribute to improving 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 can be expected to be generated. There is no particular upper limit to the ionic conductivity of the adhesive layer composed of the adhesive composition according to the present invention, but it may be, for example, 200 μS / m or less. The technology disclosed herein can preferably be implemented 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.

[0118] (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 a polymer and an electrolyte (ionic substance). Such an adhesive layer is less prone to a decrease in the compatibility of polymers, etc., and a change in the adhesive properties of the adhesive layer even when stored in a heated or humidified thermal environment, thereby 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 improving the storage stability of the adhesive layer.

[0119] Here, "haze value" refers to the ratio of diffusely transmitted light to total transmitted light when visible light is irradiated onto the object to be 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 a composition consisting only of polymer and electrolyte is prepared, and each measurement sample (adhesive layer consisting only of polymer or adhesive layer consisting only of polymer and electrolyte with a thickness of 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 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 piece. Next, the haze value of the test piece 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 haze value of the adhesive layer can be calculated by subtracting the haze value of the slide glass from the measured value.

[0120] Furthermore, the higher the ionic conductivity, the easier it is to remove the adhesive 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, when the adhesion recovery rate is low (e.g., less than 60%), high ionic conductivity allows for removal at a lower voltage. This makes it possible to suppress the amount of reaction required within the adhesive composition 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. However, when the adherend is a metal, there is a possibility of cosmetic defects due to corrosion of the adherend by the adhesive composition. From this perspective, a lower ionic conductivity is desirable because it may suppress corrosion by reducing the reactivity of the anion with respect to the adherend metal.

[0121] Various methods can be considered for measuring the ionic conductivity of an adhesive layer, but a simple method involves preparing a measurement sample using the adhesive composition and determining the ionic conductivity of the adhesive layer. Specifically, as described in the example, a bonded body is prepared by attaching an adherend (stainless steel plate, etc.) to the other side of an electropenetrating adhesive layer, which has a substrate (such as a metal-layered film) attached 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 is subjected to resistance 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 set to 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 adhThe 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.

[0122]

[0123] Next, the bulk resistance component R of the adhesive layer, obtained from equation (A) adh The ionic conductivity σ of the adhesive layer can be determined using the following formula (C).

[0124]

[0125] In formula (C), l is the thickness of the adhesive layer, and A is the area of ​​the adhesive surface of the adhesive layer.

[0126] [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.

[0127] 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 pressure of 2.5 MPa. 0.5 ~5.0 MPa 0.5 It has an HSP distance of 3 MPa. 0.5 Preferably, the above, and more preferably 3.5 MPa 0.5 The above is preferable. Also, the HSP distance is 4 MPa. 0.5 The following is preferable:

[0128] Generally, high solubility of the cation reducer in the polymer, i.e., high compatibility of the cation reducer with the polymer, makes it easier to peel the adhesive layer from the adherend. In other words, from the viewpoint of electropenetration, it is thought that the smaller the HSP distance (high compatibility between the cation reducer and the polymer), the greater the rate of decrease in adhesive strength due to voltage application. One method for adjusting the HSP value of the cation reducer is to adjust the type of cation. One method for adjusting the HSP value of the polymer is to adjust the monomer composition of the polymer. Generally, if the compatibility of the cation reducer with the polymer is low, the diffusion rate of the cation reducer into the adhesive bulk decreases. In other words, from the viewpoint of voltage during electropenetration, the larger the HSP distance (low 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. Furthermore, from the viewpoint of easily forming an adhesive layer with a small HSP distance between the cation reducer and the polymer, and easily achieving an adhesive layer with an adhesive strength recovery rate of 60% or more after 2 minutes, the polymer in this embodiment is preferably an acrylic polymer.

[0129] 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.

[0130] [HSP Values ​​of Polymers] The dispersion term (dDp), polarity term (dPp), and hydrogen bonding term (dHp) in the HSP value of polymers 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 HSP value can be calculated using 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, using the following formula.

[0131] 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.

[0132] 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. 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.

[0133] [HSP Value of Cation Reduced Forms] 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 a cation reduced form is defined based on the following.

[0134] [Definition of Cation Reduced Form] (Reduced form of imidazolium cation) The carbon at position 2 of the imidazolium ring loses its aromaticity and becomes a neutral radical by accepting an electron. Subsequently, it changes to an N-heterocyclic carbene with the elimination of hydrogen. 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 at position 2.

[0135] (Reduction of organic cations other than imidazolium) 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 a 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 an ether group or other electron-donating group is present, the stability of the radical formed by those groups is also considered (e.g., an ether group may be stabilized by the electron-donating effect of an adjacent oxygen atom). • In the case of equivalent stability, the group with the longer chain length is eliminated. Examples of groups that leave the compound: 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 (e.g., pyrrolidinium, piperidinium, and pyridinium), neutral compounds that maintain the ring structure are produced. In the case of acyclic cations (e.g., ammonium and phosphonium), alkylamines, alkylphosphines, or analogs thereof are produced. Examples of reduced products for each cation species are shown below.

[0136] (Reduced forms of pyrrolidinium and piperidinium cations) When hydrogen and non-hydrogen substituents are attached to the nitrogen element of a pyrrolidinium or piperidinium ring, the non-hydrogen substituent is eliminated, producing pyrrolidine and piperidine. For example, when two alkyl groups are attached to the nitrogen element, one is eliminated as a radical, producing alkylpyrrolidine and alkylpiperidine. In this case, the conditions for the group that is eliminated follow the above. For example, in the case of 1-butyl-1-methylpyrrolidinium, the butyl group, which becomes a primary radical, is eliminated, rather than the methyl group, which becomes a methyl radical, and N-methylpyrrolidine is produced.

[0137] (Reduced pyridinium cations) Substituents attached to the N element of the pyridinium ring are eliminated as radicals, generating pyridine compounds.

[0138] (Reduction of ammonium cations) Substituents attached to the positively charged N element are eliminated as radicals, generating amine compounds. The conditions for the eliminated group are as described above.

[0139] (Reduction of phosphonium cations) Substituents attached to a positively charged P element are eliminated as radicals, generating phosphine compounds. The conditions for the eliminated group are as described above.

[0140] Based on the above, the HSP values ​​of the cation reductate can be calculated by various methods, but a simple method is to input the chemical structure of the cation reductate into commercially available computer software (such as Hansen Solubility Parameters in Practice (HSPiP)) using SMILES notation and calculate the HSP values ​​of the cation reductate (dispersion term (dDc), polarity term (dPc), hydrogen bonding term (dHc)).

[0141] [Surface Free Energy of Cation Reduced Form] The electrolyte contained in the adhesive composition according to the present invention preferably has a surface free energy of 20 mJ / m² of the reduced cation of the electrolyte. 2 More preferably 24 mJ / m 2 More preferably 25 mJ / m 2 In particular, 26 mJ / m 2 That's all. Preferably 40 mJ / m 2 More preferably, 36 mJ / m 2 More preferably, 30 mJ / m 2 The following is particularly preferable: 27 mJ / m 2 The following is the result: The wettability of the cationic reducer to the metal substrate is increased, thereby improving electrolysis.

[0142] If the surface free energy of the electrolyte's cation reduction is within the above range, good electrolytic properties can be achieved.

[0143] While various methods exist for calculating the surface free energy of a cation reducer, a simple method involves considering the chemical structure of the cation reducer, inputting its chemical structure into commercially available computer software (such as Hansen Solubility Parameters in Practice (HSPiP)), and then determining the parameters (Mwt, density (ρ), Parachor (P)) for calculating the surface free energy (γ) of the cation reducer from the following formula.

[0144]

[0145] (Other Components) The electrolytic adhesive composition according to the embodiment of the present invention may contain one or more components other than polymers and ionic substances (hereinafter sometimes referred to as "other components"), as necessary, to the extent that they do not impair the effects of the present invention. The other components that may be contained in the electrolytic adhesive composition according to the embodiment of the present invention will be described below.

[0146] The electrolytic adhesive composition according to the embodiment 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 above-mentioned description of polyfunctional monomers 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 effects 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.

[0147] A crosslinking catalyst may be used to more effectively advance the crosslinking reaction. 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.

[0148] 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 blocky); 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. When 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, a compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol, etc.) that is substantially absent may be preferably used. Here, substantially absent 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 to 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.

[0149] The electrolytic adhesive composition according to the embodiment of the present invention may optionally contain a conductive filler for the purpose of imparting conductivity to the electrolytic adhesive composition. The conductive filler is not particularly limited, and general known or conventional conductive fillers can be used, such as graphite, carbon black, carbon fiber, or metal powders such as silver or copper. When a conductive filler is included, the content is preferably 0.1 parts by mass or more and 200 parts by mass or less per 100 parts by mass of polymer.

[0150] The electrolytic adhesive composition according to the embodiment of the present invention may also contain various additives such as fillers, plasticizers, anti-aging agents, antioxidants, pigments (dyes), flame retardants, solvents, surfactants (leveling agents), rust inhibitors, adhesion promoters, tackifying resins, corrosion inhibitors, and antistatic agents. The total content of these components is not particularly limited as long as the effects of the present invention are achieved, but is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of polymer.

[0151] Examples of fillers include silica, iron oxide, zinc oxide, aluminum oxide, titanium oxide, barium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, pyrophyllite clay, kaolin clay, and calcined clay.

[0152] The plasticizer can be a commonly used plasticizer in general resin compositions, such as paraffin oil, process oil, liquid rubber such as liquid polyisoprene, liquid polybutadiene, and liquid ethylene-propylene rubber, tetrahydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, citric acid, and their derivatives, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate, diisononyl adipate (DINA), and isodecyl succinate.

[0153] Examples of anti-aging agents include hindered phenol compounds, aliphatic and aromatic hindered amine compounds, and others.

[0154] Examples of antioxidants include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA).

[0155] Examples of pigments include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopon, lead, cadmium, iron, cobalt, aluminum, hydrochloride salts, and sulfates, as well as azo pigments and organic pigments such as copper phthalocyanine pigments.

[0156] Examples of rust inhibitors include zinc phosphate, tannic acid derivatives, phosphate esters, basic sulfonates, and various rust-inhibiting pigments.

[0157] Examples of adhesion promoters include titanium coupling agents and zirconium coupling agents.

[0158] Common examples of antistatic agents include quaternary ammonium salts, or hydrophilic compounds such as polyglycolic acid and ethylene oxide derivatives.

[0159] Examples of tackifiers include tackifying resins, acrylic oligomers, epoxy oligomers, and styrene oligomers. 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. 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 acrylic monomers as exemplified above (for example, Mw is approximately 10 × 10 4 Less than 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.

[0160] 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.

[0161] [Applications of the electropenetrating adhesive composition] As described above, the electropenetrating adhesive composition according to the embodiment of the present invention exhibits the function of sufficiently reducing adhesive strength when voltage is applied. Due to this characteristic, the electropenetrating adhesive composition according to the embodiment of the present invention can be suitably applied to the applications of electropenetrating adhesive sheets described later. In particular, it can be preferably used for fixing components in electrical and electronic equipment.

[0162] [Initial adhesive strength, adhesive strength after voltage application, rate of decrease in adhesive strength due to voltage application, adhesive strength 2 minutes after voltage application is stopped] 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.

[0163] 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.

[0164] In the embodiment of the present invention, the electropenetrating adhesive layer is formed as described in the Examples section, and after applying a voltage, an electropenetrating adhesive sheet is formed, and the electropenetrating force measured by a 180° peel test 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. When the adhesive force 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 force 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 force, the better the electropenetrating performance, and the difference from the initial adhesive force is preferably 3.0 N / cm or more, and more preferably 6.0 N / cm or more. Furthermore, it is preferable that the strength be 8.0 N / cm or higher, more preferably 10 N / cm or higher, and particularly preferable 12 N / cm or higher.

[0165] In the embodiment of the present invention, the electropenetrating adhesive layer preferably has a reduction rate of adhesive strength due to voltage application of 40% or more, more preferably 50% or more, and even more preferably 60% or more, which can be determined by the following formula using the initial adhesive strength and adhesive strength after voltage application measured by the above method. There is no particular upper limit to the reduction rate of adhesive strength due to voltage application, but for example, it can be 99.999% or less. Reduction rate of adhesive strength due to voltage application (%) = {1 - (electropenetrating strength / initial adhesive strength)} × 100

[0166] 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 obtaining a power supply, it is preferably 12V or less, may also be 9V or less, or 4V or less. A low applied voltage is also preferable from the viewpoint that stripping work can be performed using an easily available power supply such as a dry cell battery. Also, from the viewpoint of operator safety, the lower the applied voltage, the better, but it is usually 1V or higher. In some embodiments, from the viewpoint of suppressing unintended peeling due to leakage current from electrical and electronic equipment, the applied voltage is preferably 4V or higher, may 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 of being able to peel quickly 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, but may also be 1 minute or more, 10 minutes or more, 30 minutes or more, or 1 hour or more. Generally, it is considered that peeling is easier at lower voltages when the adhesive strength recovery rate is small (low diffusivity of the cation reducer), the ionic conductivity is high, the compatibility between the cation reducer and the polymer is low (large HSP distance), the cation reducer spreads easily to the adherend (surface free energy of the reducer), and the reduction potential of the ionic substance is small.

[0167] [Adhesion Recovery Rate] The adhesive layer formed from the adhesive composition according to the present invention has an adhesion recovery rate of 60% or more after 2 minutes. In some embodiments, the adhesion recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is preferably 61% or more, may be 63% or more, 65% or more, 70% or more, or 73% or more. With an adhesive layer having such an adhesion recovery rate after 2 minutes, temporary fixing of the adherend by the adhesive layer and adjustment of the bonding position of the adhesive layer and adherend can be easily achieved in a short time after the voltage is applied. In some embodiments, the adhesion recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is preferably 80% or more, more preferably 100% or more. With an adhesive layer having such an adhesion recovery rate after 2 minutes, sufficient adhesive strength to fix the adherend can be easily obtained in a short time after the voltage is applied. Furthermore, there is no particular limit to the upper limit of the adhesive strength recovery rate. For example, from the viewpoint of making it easier to adjust the position when reattaching the adherend by maintaining a slightly tacky state for a certain period of time without reapplying voltage, and from the viewpoint of preventing damage to the adherend during position adjustment due to a rapid recovery of adhesive strength, it may be set to, for example, 100% or less, preferably 95% or less, more preferably 90% or less, even more preferably 85% or less, particularly preferably 80% or less, even more preferably 75% or less, and most preferably 70% or less. In particular, from the viewpoint of making it easier to realize an adhesive that can temporarily fix the adherend in a short time after voltage is applied and allows for easy adjustment of the attachment position, the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is preferably in the range of 60 to 80%, and more preferably in the range of 61 to 75%. If the adhesive composition has a predetermined adhesive strength recovery rate, even if voltage is applied by mistake, the adhesive strength will recover by leaving it for a predetermined time, and it will be possible to continue fixing the member. While a shorter standing time is generally preferable, too short a time can worsen workability during electrolysis, so it is usually between 30 seconds and 2 minutes. It is believed that the greater the amount of cation reduction generated at the substrate interface by voltage application and its diffusion into the adhesive bulk, the higher the adhesive strength recovery rate tends to be.Regarding the diffusivity of the cation reducer, it is thought that the diffusion rate of the cation reducer into the adhesive bulk increases as the compatibility of the cation reducer with the polymer increases, i.e., the smaller the HSP distance between the cation reducer and the polymer, the lower the polymer's Tg, the lower the polymer's crystallinity, the lower the polymer's molecular weight, and the lower the gel fraction of the adhesive composition.

[0168] In an adhesive composition, adding a second polymer having a lower Tg than the first polymer, in addition to the first polymer which is the main component, is also effective in lowering the Tg of the adhesive / adherent interface and improving the adhesive strength recovery rate. In this case, the second polymer and the first polymer may be miscible, but it is more preferable that they are not miscible. The 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.

[0169] [Repeatability of Electrodeposition] Repeatability of electrodeposition refers to how many times the process of electrodeposition → re-bonding → electrodeposition can be repeated. When voltage is applied, a cation reduction reaction proceeds at the substrate interface, while on the substrate side (e.g., aluminum vapor-deposited substrate), an oxidation reaction of the metal (aluminum, etc.) constituting the substrate proceeds. In some embodiments, as the oxidation reaction of the metal (aluminum, etc.) of the substrate progresses due to repeated electrodeposition, the adhesion strength between the adhesive and the substrate decreases and anchoring breaks, which may lead to the problem of not being able to use it repeatedly. In addition, when voltage is applied, cations are reduced at the interface between the substrate and the adhesive layer, and cation reducers accumulate at the interface between the substrate and the adhesive layer. In some embodiments, excess cation reducers that accumulate in excess of the amount of cation reducers necessary to obtain electrodeposition accumulate at the interface between the substrate and the adhesive layer without diffusing into the bulk of the adhesive layer, so even if the substrate is bonded again, a problem may arise in which sufficient adhesion strength cannot be obtained when voltage is not applied. In some embodiments, when electrolyzed and then re-bonded, that is, when the adhesive strength decreases due to voltage application and the bond is re-bonded after the voltage application 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 decreases due to voltage application and the bond is re-bonded after the voltage application 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 no voltage is applied after the adhesive strength decreases due to voltage application and the bond is re-bonded after the voltage application is stopped, is sufficiently recovered compared to the adhesive strength when no voltage is applied in the electrolyzed adhesive layer that has never had voltage applied. In other words, the adhesive strength decreases when voltage is applied, and the adhesive strength when the parts are bonded again after the voltage is stopped is used. Using the adhesive strength when voltage is not applied in the electropenetrating adhesive layer that has never been subjected to voltage, the recovery rate of the adhesive strength, which can be calculated using the following formula, is appropriately 40% or more, preferably 50% or more, more preferably 60% or more, and even more preferably 80% or more.If the adhesive strength recovery rate is 50% or more, it is possible to firmly bond the substrate again. Adhesion strength recovery rate (%) = {(Adhesion strength when voltage is not applied, when the adhesive strength decreases due to voltage application and the substrate is bonded again after the voltage application is stopped) / (Adhesion strength when voltage is not applied in the electropenetrating adhesive layer that has never had voltage applied)} × 100 The repeatability of electropenetration is preferably 2 times or more, more preferably 4 times or more, even more preferably 5 times or more, and particularly preferably 7 times or more. • If the diffusivity of the cation reducer is low and the ionic conductivity is high (it is possible to suppress the amount of reaction in the adhesive composition because it can be peeled at a low voltage), or if the ionic conductivity is low (it is possible to suppress the amount of reaction even when a high voltage is applied), it is expected that the repeatability of electropenetration will improve. For example, when peeling is performed under specific voltage application conditions such as 30V 30s, lower ionic conductivity improves repeatability because the amount of reaction is small. Also, if electropenetration is possible at a low voltage, repeatability is improved because the amount of reaction can be suppressed by electropenetrating at an even lower voltage.

[0170] 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.

[0171] From the viewpoint of initial adhesion, the thickness of the electropenetrating adhesive layer 1 is preferably 1 μm or more and 1000 μm or less. 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] The gel fraction of the adhesive layer is appropriately set according to the purpose and manner of use, and is not limited to a specific range. The gel fraction is, for example, 99% or less, and 97% or less is appropriate. From the viewpoint of appropriately following the surface of the adherend and adhering well, the gel fraction of the adhesive layer is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less. In some embodiments, the gel fraction may be 60% or less, 50% or less, or 40% or less. Furthermore, from the viewpoint of imparting appropriate cohesiveness to the adhesive and appropriately exhibiting adhesive properties, the gel fraction of the adhesive layer is, for example, 10% or more, preferably 20% or more, and may be 30% or more. From the viewpoint of the deformation resistance of the adhesive layer (prevention of overflow due to pressure and bubble formation due to foreign matter inclusion, etc.), the gel fraction is preferably 40% or more, more preferably 60% or more, may be 70% or more, or 80% or more. In some embodiments, the gel fraction may be 60% or more, more preferably 80% or more, from the viewpoint of facilitating the realization of an adhesive layer having a moderate adhesive strength recovery rate after 2 minutes (e.g., 60% to 90%). Furthermore, from the viewpoint of facilitating the formation of an adhesive layer with a moderately large diffusion rate of the cation reduction into the adhesive bulk, and facilitating the realization of an adhesive layer with a 2-minute adhesive strength recovery rate (e.g., 60% to 80%), the gel fraction may be 70% or more, more preferably 75% or more, and even more preferably 78% or more. The gel fraction can be adjusted by the molecular weight, molecular structure, concentration, type of crosslinking agent, degree of crosslinking, etc. of the base polymer. The gel fraction is measured by the following method.

[0177] Approximately 0.1 g of the adhesive layer sample prepared by the method described in the Examples section was taken, wrapped in a porous tetrafluoroethylene sheet with an average pore size of 0.2 μm (product name "NTF1122", manufactured by Nitto Denko Corporation), tied with kite string, and its mass was measured. This mass was defined as the mass before immersion (Z). The mass before immersion is the total mass of the adhesive layer (the adhesive layer taken above), the tetrafluoroethylene sheet, and the kite string. The total mass of the tetrafluoroethylene sheet and the kite string was also measured and defined as the mass of the package (Y). Next, the adhesive layer wrapped in the tetrafluoroethylene sheet and tied with kite string (referred to as the "sample") was placed in a 50 ml container filled with ethyl acetate and left to stand at 25°C for 7 days. Subsequently, the sample (after ethyl acetate treatment) is removed from the container, transferred to an aluminum cup, and dried in an oven at 130°C for 2 hours to remove the ethyl acetate. The mass is then measured and designated as the mass after immersion (X). The gel fraction is calculated using the following formula: Gel fraction [% (mass%)] = (X - Y) / (Z - Y) × 100

[0178] [Method for Manufacturing an Electrorelease Adhesive Sheet] The method for manufacturing an electrorelease adhesive sheet according to the embodiment of the present invention can be a known or conventional manufacturing method. The electrorelease adhesive layer in the electrorelease adhesive sheet according to the embodiment of the present invention can be formed by applying a solution obtained by dissolving the electrorelease adhesive composition according to the embodiment of the present invention in a solvent as needed onto a release liner, and then drying and / or curing it. If other adhesive layers are provided, the other adhesive layers can be formed by applying a solution obtained by dissolving an adhesive composition that does not contain ionic substances and additives in a solvent as needed onto a release liner, and then drying and / or curing it. The solvent and release liner can be those listed above.

[0179] 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.

[0180] 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.

[0181] [Method for electrolytically peeling off an electrolytically peelable adhesive sheet] In the embodiment of the present invention, the electrolytically peelable adhesive sheet can be peeled off from the adherend by applying a voltage to the electrolytically peelable adhesive layer, thereby generating a potential difference in the thickness direction of the electrolytically peelable adhesive layer. For example, a bond in which an electrolytically peelable adhesive sheet X1 or X2 is attached to a conductive adherend can be peeled off by connecting electrodes to the conductive layer and the conductive adherend, for example, and applying a voltage to the electrolytically peelable adhesive layer. For example, in the case of an electrolytically peelable adhesive sheet X3, it can be peeled off from the adherend by connecting electrodes to both conductive layers, for example, and applying a voltage to the electrolytically peelable adhesive layer. It is preferable to apply the current by connecting terminals to one end and the other end of the electrolytically peelable adhesive sheet so that the voltage is applied to the entire electrolytically peelable adhesive layer. Note that if the adherend has a metal adherend, the above-mentioned one end and the other end may be a part of the adherend having a metal adherend. Furthermore, when peeling, water may be added to the interface between the adhesive surface of the conductive adherend and the electropenetrating adhesive layer before applying 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.

[0182] 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.

[0183] [Applications of Electro-Removable Adhesive Sheets] Conventional re-peelable technologies include adhesive layers that harden and peel off by ultraviolet (UV) irradiation or adhesive layers that peel off by heat. Electro-removable adhesive sheets using such adhesive layers cannot be used when ultraviolet (UV) irradiation is difficult or when heat damages the adherend. The electro-removable adhesive sheet according to the embodiment of the present invention, which includes the above-mentioned electro-removable adhesive layer, does not use ultraviolet light or heat, and therefore can be easily peeled off by applying voltage without damaging the adherend. Thus, the electro-removable 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.

[0184] 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 and organic-inorganic hybrid substrates mainly composed of silsesquioxane, flexible glass substrates for flexible displays, and graphene sheets.

[0185] [Bonded Body] The bonded body according to the embodiment of the present invention comprises an electropenetrating adhesive sheet according to the embodiment of the present invention and a conductive material, wherein the electropenetrating adhesive layer of the electropenetrating adhesive sheet is attached to the conductive material.

[0186] 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.

[0187] 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.

[0188] 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 any of the other adhesive layers 2 of the electropenetrating adhesive sheet X3 is attached to a non-conductive material.

[0189] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0190] <Synthesis of Polymers> (Synthesis Example 1) 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 97 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 temperature was raised to 63°C and the reaction was carried out for 6 hours. Then, ethyl acetate was added to obtain a polymer solution in which a polymer (BA / AA / =97 / 3) 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 -45°C.

[0191] (Synthesis Example 2) A polymer (BA / AA / MMA = 92 / 3 / 5) was obtained by the same method as in Synthesis Example 1, except that n-butyl acrylate (BA): 92 parts by mass, methyl methacrylate (MMA): 5 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 -39°C.

[0192] (Synthesis Example 3) A polymer (BA / AA / MEA = 92 / 3 / 5) was obtained by the same method as in Synthesis Example 1, except that n-butyl acrylate (BA): 92 parts by mass, 2-methoxyethyl acrylate (MEA): 5 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 -45°C.

[0193] (Synthesis Example 4) A polymer (BA / AA / MMA = 87 / 3 / 10) was obtained by the same method as in Synthesis Example 1, except that n-butyl acrylate (BA): 87 parts by mass, methyl methacrylate (MMA): 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 770,000, and the glass transition temperature (Tg) was -35°C.

[0194] (Synthesis Example 5) A polymer (BA / AA / MEA = 87 / 3 / 10) was obtained by the same method as in Synthesis Example 1, 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 720,000, and the glass transition temperature (Tg) was -42°C.

[0195] (Synthesis Example 6) 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 84 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass, dicyclopentanyl acrylate (DCPA): 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-hydroxycyclohexyl phenyl ketone was added as a polymerization initiator, and the mixture was reacted for 15 minutes while stirring and irradiated with ultraviolet light at an irradiance of 3 mW. Subsequently, a polymer solution was obtained in which a polymer with a solid content concentration of 5% by mass (BA / AA / MEA / DCPA = 84 / 3 / 10 / 3) was dissolved. The weight-average molecular weight of the obtained polymer was 3 million, and the glass transition temperature (Tg) was -43°C.

[0196] (Synthesis Example 7) A polymer solution containing a dissolved polymer (BA / AA / MEA / DCPA = 82 / 3 / 10 / 5) was obtained by the same method as in Synthesis Example 6, except that the monomer components used were n-butyl acrylate (BA): 82 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass, and dicyclopentanyl acrylate (DCPA): 5 parts by mass. The weight-average molecular weight of the obtained polymer was 3 million, and the glass transition temperature (Tg) was -41°C.

[0197] (Synthesis Example 8) A polymer solution containing a dissolved polymer (BA / AA / MEA / DCPA = 80 / 3 / 10 / 7) was obtained by the same method as in Synthesis Example 6, except that the monomer components used were n-butyl acrylate (BA): 80 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass, and dicyclopentanyl acrylate (DCPA): 5 parts by mass. The weight-average molecular weight of the obtained polymer was 3 million, and the glass transition temperature (Tg) was -40°C.

[0198] (Synthesis Example 9) A polymer solution containing a dissolved polymer (BA / AA / MEA / DCPA = 77 / 3 / 10 / 10) was obtained by the same method as in Synthesis Example 6, except that the monomer components used were n-butyl acrylate (BA): 77 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass, and dicyclopentanyl acrylate (DCPA): 10 parts by mass. The weight-average molecular weight of the obtained polymer was 3 million, and the glass transition temperature (Tg) was -37°C.

[0199] (Synthesis Example 10) A polymer solution containing the polymer (BA / AA / MEA / CHA = 77 / 3 / 10 / 10-A) was obtained by the same method as in Synthesis Example 6, except that the monomer components used were n-butyl acrylate (BA): 77 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass, and cyclohexyl acrylate (CHA): 10 parts by mass. The weight-average molecular weight of the obtained polymer was 2.6 million, and the glass transition temperature (Tg) was -39°C.

[0200] (Synthesis Example 11) 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 77 parts by mass, acrylic acid (AA): 3 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, cyclohexyl acrylate (CHA): 10 parts by mass) and 100 parts by mass of toluene 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 temperature was raised to 63°C and the reaction was carried out for 8 hours. Then, toluene was added to obtain a polymer solution in which a polymer (BA / AA / MEA / CHA = 77 / 3 / 10 / 10-B) with a solid content of 34% by mass was dissolved. The weight-average molecular weight of the obtained polymer was 450,000, and the glass transition temperature (Tg) was -38°C.

[0201] (Synthesis Example 12) A polymer solution containing a polymer (BA / AA / MEA / CHA = 74 / 3 / 10 / 13) with a solid content of 34% was obtained by the same method as in Synthesis Example 11, except that 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 74 parts by mass, acrylic acid (AA): 3 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, cyclohexyl acrylate (CHA): 13 parts by mass) was used. The weight-average molecular weight of the obtained polymer was 620,000, and the glass transition temperature (Tg) was -37°C.

[0202] (Synthesis Example 13) A polymer solution containing a polymer (BA / AA / MEA / CHA = 72 / 3 / 10 / 15) with a solid content of 34% was obtained by the same method as in Synthesis Example 11, except that 100 parts by mass of acrylic monomer components (n-butyl acrylate (BA): 72 parts by mass, acrylic acid (AA): 3 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, cyclohexyl acrylate (CHA): 15 parts by mass) was used. The weight-average molecular weight of the obtained polymer was 620,000, and the glass transition temperature (Tg) was -36°C.

[0203] (Synthesis Example 14) A polymer with a solid content of 34% by mass (BA / AA / MEA / MMA = 77 / 3 / 10 / 10) was obtained by the same method as in Synthesis Example 13, except that the monomer components were n-butyl acrylate (BA): 77 parts by mass, acrylic acid (AA): 3 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, methyl methacrylate (MMA): 10 parts by mass, and toluene: 65 parts by mass per 100 parts by mass of acrylic monomer components as the polymerization solvent. The weight-average molecular weight of the obtained polymer was 700,000, and the glass transition temperature (Tg) was -36°C.

[0204] (Synthesis Example 15) A polymer with a solid content of 34% by mass (BA / AA / MEA / MMA = 80 / 3 / 10 / 7) was obtained by the same method as in Synthesis Example 13, except that n-butyl acrylate (BA): 80 parts by mass, acrylic acid (AA): 3 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, and methyl methacrylate (MMA): 7 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 -38°C.

[0205] (Synthesis Example 16) A polymer with a solid content of 34% by mass (BA / AA / MEA / MMA = 82 / 3 / 10 / 5) was obtained by the same method as in Synthesis Example 13, except that n-butyl acrylate (BA): 82 parts by mass, acrylic acid (AA): 3 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, and methyl methacrylate (MMA): 5 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 -40°C.

[0206] <Synthesis of Ionic Substances> In addition to the following commercially available ionic liquids, ionic liquids synthesized according to the following synthesis examples 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. [4MOP][TFSI]: Cation: 1-octyl-4-methylpyridinium cation, Anion: bis(fluorosulfonyl)imide anion, Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. [Omim][PF6]: Cation: 1-octyl-3-methylimidazolium cation, Anion: Hexafluorophosphate anion, Manufactured by Tokyo Chemical Industry Co., Ltd. [P66614][TFSI]: Cation: Trihexyl(tetradecyl)phosphonium cation, Anion: bis(trifluoromethanesulfonyl)imide anion, Manufactured by Tokyo Chemical Industry Co., Ltd.

[0207] (Synthesis Example 17) (1) 1-hexyl-3-methylimidazolium bromide and lithium difluoro(oxalato)borate were mixed in deionized water in a 1:1 molar ratio and stirred for 10 minutes. At this time, the amount of deionized water was 60 parts by mass. (2) The mixture was placed in a centrifuge to separate the aqueous phase and the ionic liquid phase. (3000G, 3 minutes) (3) The aqueous phase was discarded, fresh deionized water was added, and the mixture was stirred for 3 minutes. (4) Steps (2) and (3) were repeated 10 times to remove bromide ions and lithium ions by purification. (5) It was confirmed that no white precipitate originating from residual bromide ions was formed when an aqueous silver nitrate solution (concentration 0.1 mol / L) was added dropwise to the separated aqueous phase. (6) The remaining water was removed in a vacuum dryer (60°C for 2 hours) to obtain [Hmim][DFOB].

[0208] (Synthesis Example 18) (1) [Hmim] [BOB] was obtained by the same method as in synthesis method 6, except that 1-hexyl-3-methylimidazolium bromide and lithium bis(oxalate)borate were used.

[0209] (Synthesis Example 19) (1) 1-methylimidazole and methoxymethyl bromide were mixed in a 1:1 molar ratio, and acetonitrile three times their weight was added. (2) The mixture was heated at 80°C for 7 hours. (3) The mixture was dried under reduced pressure at 40°C for 2 hours using an evaporator and dissolved in 10 mL of deionized water. (4) To remove unreacted material from the aqueous solution, 10 mL of ethyl acetate was added and stirred. The mixture was placed in a centrifuge (3000 G, 3 minutes) to separate the aqueous phase from the ethyl acetate phase, and then the ethyl acetate phase was removed. This operation was repeated three times. (5) The remaining aqueous phase was dried under reduced pressure at 60°C for 2 hours using an evaporator to obtain [C1OC1mim][Br]. (6) From there, [C1OC1mim][TFSI] was obtained by the same method as in Synthesis Method 17, except that [C1OC1mim][Br] and lithium bis(fluorosulfonyl)imide were used.

[0210] <Preparation of Adhesive Compositions> The polymers, ionic substances, and additional components obtained above were added and stirred and mixed to obtain the adhesive compositions of Examples 1 to 20 and Comparative Examples 1 to 3. The amounts of each component are shown in Tables 1 and 2. The values ​​for each component in Tables 1 and 2 represent parts by mass. The amount of polymer (parts by mass) indicates the amount of solids in the polymer solution (parts by mass). The abbreviations for each component in Tables 1 and 2 are as follows.

[0211] (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:, trade name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Company, Inc.

[0212] <Physical properties and evaluation>

[0213] [Polymer Tg] 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 homopolymer was obtained using a temperature-modulated DSC (product name "Q-2000", manufactured by T.A. Instruments Corporation) at a heating rate of 10°C / min under a nitrogen atmosphere of 50 ml / min. Referring to JIS K 7121 (2012), the temperature at which the curve of the stepwise change portion of the glass transition intersects with a line equidistant in the vertical axis direction from the line extending from the low-temperature baseline and the high-temperature baseline of the obtained reversing heat flow was defined as the polymer Tg.

[0214] [Tg of the adhesive layer formed from the adhesive composition] Using the adhesive composition of each example, a sample for measurement (adhesive layer sample) was prepared as follows, and the Tg was measured using temperature-modulated DSC in the same manner as the Tg measurement of the polymer described above.

[0215] (Preparation of measurement samples (adhesive layer samples)) The adhesive composition of each example was applied to the peeled surface of a polyethylene terephthalate peel liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) using an applicator to achieve a uniform thickness. Next, after standing at room temperature for 3 minutes, it was heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 50 μm.

[0216] [Ionic Conductivity of the Adhesive Layer] Using the adhesive composition of each example, measurement samples (jointed samples) were prepared as follows, and the ionic conductivity of the adhesive layer was determined by the following method.

[0217] (Preparation of measurement samples (joint samples)) The adhesive composition of each example was applied to the peeled surface of a polyethylene terephthalate peel liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) using an applicator to achieve a uniform thickness. Next, after standing at room temperature for 3 minutes, it was heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 50 μm. Then, the obtained electro-peelable adhesive layer (adhesive sheet) was made into a sheet with a size of 10 mm x 80 mm, and the metal layer surface 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 laminated to it as a substrate to create a single-sided adhesive sheet with a substrate. The release liner of a single-sided adhesive sheet with a 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 the adherend. The sheet was 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 bonded body consisting of a stainless steel plate 6 / an electro-peelable adhesive layer (adhesive sheet) 1' / a metal-layered film (conductive substrate) 5'. An outline of the bonded body is shown in Figure 5.

[0218] (Measurement of Capacitance and Ionic Conductivity) A potentiometer / galvanostat (Biologic, SP-300) was used to measure capacitance and ionic conductivity. 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 the potentiometer / galvanostat, and a cole-cole plot was obtained by varying the frequency from 10Hz to 200kHz. 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.

[0219] 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, it was modeled as a parallel circuit by the combination of CPE-P:α). The series resistance of the wiring was designated as Rn, and the equivalent circuit of the junction sample was set as shown in FIG. 6. The obtained Cole-Cole plot was fitted by the following formula (A) (ω: angular frequency, Z(ω): complex impedance at angular frequency ω, j: imaginary unit). The Q adh and α were substituted into the following formula (B) to calculate the capacitance C adh .

[0220]

[0221] Next, the ionic conductivity σ of the adhesive layer was determined using the following formula (C) with the resistance component R adh of the bulk of the adhesive layer obtained from formula (A).

[0222]

[0223] In formula (C), l is the thickness of the adhesive layer, and A is the area of the adhesive surface of the adhesive layer.

[0224] [Initial Adhesion] The adhesive composition for each example was applied to the peel-treated surface of a polyethylene terephthalate peel-off liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) using an applicator to achieve a uniform thickness. Next, after standing at room temperature for 3 minutes, it was heated and dried at 130°C for 5 minutes to obtain an electro-peelable adhesive layer (adhesive sheet) with a thickness of 60 μm. Then, the obtained electro-peelable adhesive layer (adhesive sheet) was made into a sheet with a size of 10 mm x 80 mm, and the metal layer side of a metal-layered film (product name "1005CR", manufactured by Toray Film Processing Co., Ltd., thickness 12 μm, size 10 mm x 100 mm) was laminated to it as a substrate to create a single-sided adhesive sheet with a substrate. The release liner of a single-sided adhesive sheet with a 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 the adherend. A 2 kg roller was used to press the plate back and forth once, and the plate was left for 72 hours in an environment of 25°C and 50% RH to obtain a bond consisting of a stainless steel plate 6 / electropenetrating adhesive layer (adhesive sheet) 1' / metal layered film (conductive substrate) 5'. An outline of the bond is shown in Figure 5. Subsequently, the bond 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 adhesive strength described in JIS Z 0237:2009. The measurement results are shown in Tables 1 and 2.

[0225] [Adhesion after voltage application] Before peeling, the positive and negative electrodes of a DC current machine were attached to the α and β points in Figure 5 of the bonded body, respectively. The adhesion after voltage application was measured in the same manner as the initial adhesion measurement described above, except that the bond was peeled immediately after applying a voltage of 10V for 30 seconds or 2V for 30 seconds. The adhesion after voltage application was calculated according to the method for measuring peel adhesion described in JIS Z 0237:2009. The measurement results are shown in Tables 1 and 2.

[0226] [Adhesion Reduction Rate] Using the initial adhesion and adhesion after voltage application measured by the method described above, the adhesion reduction rate due to voltage application was calculated using the following formula. The results are shown in Tables 1 and 2. Adhesion Reduction Rate (%) = 100 - (Adhesion after voltage application / Initial adhesion) × 100 The measurement results are shown in Tables 1 and 2.

[0227] [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 the adhesion strength 2 minutes after stopping the voltage application was measured in the same manner as the initial adhesion strength measurement described above, except that the peel was performed 2 minutes after stopping the voltage application in a room temperature (25°C) environment. The adhesion strength 2 minutes after stopping the voltage application was calculated according to the method for measuring peel adhesion strength 1 described in JIS Z 0237:2009. The adhesion recovery rate was calculated using the initial adhesion strength and the adhesion strength 2 minutes after stopping the voltage application using the following formula: Adhesion recovery rate (%) = (Adhesion strength 2 minutes after stopping voltage application / Initial adhesion strength) × 100 The measurement results are shown in Tables 1 and 2.

[0228] [HSP Values ​​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 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 ​​when each monomer 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 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.

[0229]

[0230] 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.

[0231] [HSP values ​​of cation reducers] The structure of the cation reducer was defined as follows, according to the "Definition of Cation Reducer" above: AS-110: 1-ethyl-3-methylimidazole-2-ylidene [Hmim][DFOB], [Hmim][BOB]: 1-hexyl-3-methylimidazole-2-ylidene [C1OC1mim][TFSI]: 1-methoxymethyl-3-methylimidazole-2-ylidene [4MOP][TFSI]: 4-methylpyridine [Omim][PF6]: 1-octyl-3-methylimidazole-2-ylidene [P66614][TFSI]: trihexylphosphine Next, the chemical structure of the cation reducer was converted into a string using SMILES notation. The HSP values ​​(dispersion term (dDc), polarity term (dPc), hydrogen bonding term (dHc)) of the cation reduction were determined by inputting the stringified chemical structure into computer software (Hansen Solubility Parameters in Practice (HSPiP) Ver. 5.3.03).

[0232] [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.

[0233] The results are shown in Tables 1 and 2.

[0234] [Surface Free Energy of Cation Reduced Forms] (1) The chemical structure of the cation reduced form was entered into computer software (Hansen Solubility Parameters in Practice (HSPiP) Ver. 5.3.03) using SMILES notation to obtain MWt, density (ρ), and parachor (P). (2) Next, the surface free energy (γ) of the cation reduced form was calculated based on the following formula.

[0235]

[0236] The results are shown in Tables 1 and 2.

[0237] [Haze Value of Adhesive Layer] The adhesive composition of each example 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 value obtained by subtracting the haze value of the glass slide from the measured value was calculated as the haze value of the adhesive layer. All of Examples 1 to 20 had a haze value of 1.0 or less.

[0238]

[0239]

[0240] The results in Tables 1 and 2 confirm that the present invention provides desirable electropenetrating adhesive properties.

[0241] X0, X1, X2, X3 Electropeelable adhesive sheets 1, 1' Electropeelable adhesive layer 2 Other adhesive layers 3 Support substrate 4 Conductive layer 5, 5' Conductive substrate 6 Stainless steel plate

Claims

1. An adhesive composition comprising a polymer and an electrolyte, wherein the HSP distance between the reduced cation of the electrolyte and the polymer is 2.5 MPa. 0.5 ~5.0 MPa 0.5 An adhesive composition characterized in that the ionic conductivity of the adhesive layer formed from the adhesive composition is 5.0 μS / m or more, and the adhesive strength recovery rate of the adhesive layer formed from the adhesive composition after 2 minutes is 60% or more.

2. The surface free energy of the reduced cation of the electrolyte is 25 mJ / m 2 ~35 mJ / m 2 The adhesive composition according to claim 1, characterized in that it is the same as the one described in claim 1.

3. The adhesive composition according to claim 1, characterized in that the ionic conductivity of the adhesive layer is 15 μS / m or more.

4. The adhesive composition according to claim 1, characterized in that the adhesive strength recovery rate is 80% or more.

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

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

7. The adhesive composition according to claim 6, characterized in that the glass transition temperature of the polymer is -30°C or lower.

8. The adhesive composition according to claim 6, characterized in that the weight-average molecular weight of the polymer is 1 million or less.

9. The adhesive composition according to claim 6, characterized in that the gel fraction of the adhesive layer formed from the adhesive composition is 70% or more.

10. The adhesive composition according to claim 6, characterized in that the proportion of monomers whose homopolymer glass transition temperature is 0°C or higher is 2% by mass or more and 13% by mass or less, relative to the total monomer components (100% by mass) constituting the polymer.

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

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

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

14. The adhesive composition according to claim 1, characterized in that the adhesive strength recovery rate is 85% or less.

15. The adhesive composition according to claim 6, 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.

16. 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.

17. The adhesive composition according to claim 1, characterized in that the haze value of the adhesive layer formed from the adhesive composition is 30% or less.

18. An electropenetrating adhesive sheet comprising an electropenetrating adhesive layer formed from the adhesive composition according to any one of claims 1 to 17.

19. The electropenetrating adhesive sheet according to claim 18, further comprising a conductive substrate having at least one conductive surface, wherein the conductive surface of the conductive substrate is in contact with the adhesive layer.

20. The electropenetrating adhesive sheet according to claim 19, further comprising another adhesive layer, wherein the other adhesive layer is formed on the surface of the conductive substrate opposite to the adhesive layer.

21. The electropenetrating adhesive sheet according to claim 19, further comprising 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 the conductive surface of the second conductive substrate is in contact with the adhesive layer.

22. The electropenetrating adhesive sheet according to claim 19, characterized in that the conductive substrate has protrusions that protrude in the planar direction from the adhesive layer.

23. A bond comprising the adhesive sheet described in claim 18 and a conductive material, wherein the adhesive layer is attached to the conductive material.

24. A bond comprising an adhesive sheet according to any one of claims 19 to 22 and a conductive material, wherein the adhesive layer is attached to the conductive material.

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