Electrically-detachable pressure-sensitive adhesive sheet and joined body

Abstract

Provided are: an electrically-detachable pressure-sensitive adhesive sheet that has an electric detachment function sufficient as an electrically-detachable pressure-sensitive adhesive sheet even in a high-temperature and high-humidity environment for a long period of time, and that can suppress a decrease in adhesive force between a conductive base material and an electrically-detachable pressure-sensitive adhesive agent layer; and a joined body. The present invention pertains to an electrically-detachable pressure-sensitive adhesive sheet that is provided with: a conductive base material including a support base material and a conductive carbon layer; and an electrically-detachable pressure-sensitive adhesive agent layer in which the pressure-sensitive adhesive force becomes lower when voltage is applied. The electrically-detachable pressure-sensitive adhesive agent layer and the conductive carbon layer are in contact with each other.

Description

Electrically peelable adhesive sheet and bonded body

[0001] The present invention relates to an electrically releasable pressure-sensitive adhesive sheet and a bonded body.

[0002] In electronic component manufacturing processes, etc., there is an increasing demand for rework to improve yields and recycling by disassembling and recovering components after use. To meet these demands, double-sided / single-sided electrically releasable pressure-sensitive adhesive sheets that have a certain level of adhesive strength and releasability are sometimes used to join components in electronic component manufacturing processes, etc.

[0003] Known double-sided / single-sided electrically peelable adhesive sheets that achieve the above-mentioned adhesive strength and releasability include electrically peelable adhesive sheets that use an ionic liquid consisting of cations and anions as the component that forms the adhesive layer, and that peel off when a voltage is applied to the adhesive layer.

[0004] For example, Patent Document 1 describes an electrically releasing pressure-sensitive adhesive sheet that uses a conductive substrate having a metal vapor deposition layer on a support substrate as the conductive substrate, and that includes, in this order, a support substrate, a conductive layer (metal vapor deposition layer), a coating layer for protecting the conductive layer, and an electrically releasing pressure-sensitive adhesive layer whose adhesive strength decreases upon application of a voltage. Patent Document 1 describes a method in which, when an electrically releasing pressure-sensitive adhesive layer is attached to a conductive support, a voltage is applied to the pressure-sensitive adhesive layer via the conductive support and the conductive substrate attached using the pressure-sensitive adhesive layer, thereby peeling the pressure-sensitive adhesive layer from the conductive support.

[0005] Japanese Patent Application Publication No. 2022-126243

[0006] It is preferable that the electrically peelable pressure-sensitive adhesive sheet firmly bonds members when no voltage is applied, and can be peeled off with little force when a voltage is applied.

[0007] However, when an assembly in which a conventional electrically-release pressure-sensitive adhesive sheet described in Patent Document 1 is attached to a conductive adherend is left in a high-temperature, high-humidity environment for a long period of time (e.g., 600 hours or more), and then a voltage is applied to the electrically-release pressure-sensitive adhesive layer via the conductive substrate and the conductive adherend, the metal vapor deposition layer on the conductive substrate corrodes, which could make it impossible to apply a voltage to the electrically-release pressure-sensitive adhesive layer. Furthermore, the corrosion of the metal vapor deposition layer could cause a decrease in the adhesive strength between the electrically-release pressure-sensitive adhesive layer and the conductive substrate (anchor failure).

[0008] The present invention has been completed in view of the above, and aims to provide an electrically releasing pressure-sensitive adhesive sheet and an assembly that have sufficient electrical release function as an electrically releasing pressure-sensitive adhesive sheet even when stored in a high-temperature, high-humidity environment for a long period of time, and that can suppress a decrease in the adhesive strength between the electrically releasing pressure-sensitive adhesive layer and a conductive substrate. In this specification, electrical release function means that the adhesive strength of the electrically releasing pressure-sensitive adhesive layer is weakened to the extent that it can be easily peeled off by applying a voltage to the electrically releasing pressure-sensitive adhesive layer.

[0009] As a result of extensive investigations, the inventors have found that by providing an electrically peelable adhesive sheet comprising a conductive substrate including a support substrate and a conductive carbon layer, and an electrically peelable adhesive layer whose adhesive strength decreases when a voltage is applied, in which the electrically peelable adhesive layer and the conductive carbon layer are in contact with each other, the electrically peelable adhesive sheet has sufficient electrical peeling function even when left in a high-temperature, high-humidity environment for a long period of time, and is able to suppress a decrease in the adhesive strength between the electrically peelable adhesive layer and the conductive substrate.

[0010] The means for solving the above problems are as follows: [1] An electrically peelable pressure-sensitive adhesive sheet comprising a conductive substrate including a support substrate and a conductive carbon layer, and an electrically peelable pressure-sensitive adhesive layer whose adhesive strength decreases upon application of a voltage, wherein the electrically peelable pressure-sensitive adhesive layer and the conductive carbon layer are in contact with each other. [2] An electrically peelable pressure-sensitive adhesive sheet comprising: a conductive substrate including a support substrate and a conductive carbon layer; ２ Bonds and sp ３ [3] The electrically peelable pressure-sensitive adhesive sheet according to [1], wherein the conductive carbon layer is formed from carbon having sp bonds, represented by the following formula (A): ３The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom is the sum of the number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom. ３ The electrically peelable pressure-sensitive adhesive sheet according to [1], wherein the ratio of the number of bonded carbon atoms is 20 at % or more. ３ Number of carbon atoms bonded / (carbon atoms sp ３ Number of carbon atoms bonded + sp to carbon atoms ２(number of carbon atoms singly bonded to oxygen atoms + number of carbon atoms singly bonded to nitrogen atoms) × 100 (A) [4] The electrically releasing pressure-sensitive adhesive sheet of [1], wherein the electrically releasing pressure-sensitive adhesive layer contains a polymer and an electrolyte. [5] The electrically releasing pressure-sensitive adhesive sheet of [4], wherein the content of the electrolyte is 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the polymer. [6] The electrically releasing pressure-sensitive adhesive sheet of [4], wherein the electrolyte is an ionic liquid, and the anion of the ionic liquid is at least one selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion. [7] The electrically releasing pressure-sensitive adhesive sheet of [4], wherein the electrolyte is an ionic liquid, and the cation of the ionic liquid is at least one selected from the group consisting of nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations. [8] The electrically releasing pressure-sensitive adhesive sheet according to [1], further comprising another pressure-sensitive adhesive layer, the other pressure-sensitive adhesive layer being formed on the surface of the support substrate opposite the conductive carbon layer. [9] The electrically releasing pressure-sensitive adhesive sheet according to [1], further comprising another pressure-sensitive adhesive layer, a second conductive carbon layer, and a second other pressure-sensitive adhesive layer, the other pressure-sensitive adhesive layer being formed on the surface of the support substrate opposite the conductive carbon layer, the second conductive carbon layer and the second other pressure-sensitive adhesive layer being formed in this order on the surface of the electrically releasing pressure-sensitive adhesive layer opposite the conductive carbon layer.

[10] A joined body comprising the electrically releasing pressure-sensitive adhesive sheet according to any one of [1] to [8] and a conductive material, the electrically releasing pressure-sensitive adhesive layer being adhered to the conductive material.

[11] A joined body comprising the electrically releasing pressure-sensitive adhesive sheet according to [9] and an adherend material, the other pressure-sensitive adhesive layer being adhered to the adherend material.

[0011] The electrically peelable pressure-sensitive adhesive sheet of the present invention has sufficient electrical peeling function as an electrically peelable pressure-sensitive adhesive sheet even when stored in a high-temperature, high-humidity environment for a long period of time, and can suppress a decrease in the adhesive strength between the electrically peelable pressure-sensitive adhesive layer and the conductive substrate.

[0012] Fig. 1 is a schematic cross-sectional view showing one example of the electrically releasing pressure-sensitive adhesive sheet of the present invention. Fig. 2 is a schematic cross-sectional view showing another example of the electrically releasing pressure-sensitive adhesive sheet of the present invention. Fig. 3 is a schematic cross-sectional view showing another example of the electrically releasing pressure-sensitive adhesive sheet of the present invention. Fig. 4 is a cross-sectional view showing an outline of a method for a 180° peel test on a three-layer electrically releasing pressure-sensitive adhesive sheet. Fig. 5 is a cross-sectional view showing an outline of a method for a 180° peel test in the examples.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes in detail the embodiments of the present invention, but the present invention is not limited to the embodiments described below.

[0014] [Electrically Peelable Pressure-Sensitive Adhesive Sheet] [Configuration of Electrically Peelable Pressure-Sensitive Adhesive Sheet] The electrically peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises a conductive substrate including a support substrate and a conductive carbon layer, and an electrically peelable pressure-sensitive adhesive layer whose adhesive strength decreases upon application of a voltage, and the electrically peelable pressure-sensitive adhesive layer and the conductive carbon layer are in contact with each other.

[0015] The electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention exhibits sufficient electrical release function as an electrically releasing pressure-sensitive adhesive sheet even when stored in a high-temperature, high-humidity environment for a long period of time, and is also capable of suppressing a decrease in the adhesive strength between the electrically releasing pressure-sensitive adhesive layer and the conductive substrate. The present inventors believe that the reason for this is as follows.

[0016] In conventional electrically peelable pressure-sensitive adhesive sheets, a metal layer is used as the conductive layer, and a coating layer is provided to protect the conductive layer (metal layer). However, when exposed to high temperature and high humidity for a long period of time, the resin components in the coating layer are hydrolyzed, causing the coating layer to deteriorate, and it is thought that the components of the electrically peelable pressure-sensitive adhesive layer pass through the conductive layer. As a result, the components of the electrically peelable pressure-sensitive adhesive layer migrate between the support substrate and the conductive layer, reducing the adhesion between the two layers and causing the conductive layer to peel off from the support substrate under high temperature and high humidity conditions.

[0017] Meanwhile, the conductive substrate in the electrically peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises a conductive substrate including a support substrate and a conductive carbon layer. While the details of the mechanism are unknown, the conductive carbon layer has strong and dense carbon-carbon covalent bonds that make it difficult for the components of the electrically peelable pressure-sensitive adhesive layer to penetrate or pass through. Furthermore, because the conductive carbon layer has excellent durability and is resistant to deterioration even in high-temperature, high-humidity environments, it is thought that the components are prevented from penetrating or passing through the conductive carbon layer.

[0018] The electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention may have a plurality of conductive substrates and a plurality of electrically releasing pressure-sensitive adhesive layers, or may have a pressure-sensitive adhesive layer, an intermediate layer, an undercoat layer, etc. in addition to the conductive substrate and the electrically releasing pressure-sensitive adhesive layer. Furthermore, in the electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention, the conductive substrate may have a plurality of support substrates and a plurality of conductive carbon layers. The electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention may be, for example, in the form of a roll or in the form of a sheet. The term "electrically releasing pressure-sensitive adhesive sheet" also includes the meaning of "adhesive tape." That is, the electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention may be an adhesive tape in the form of a tape.

[0019] The electrically releasing pressure-sensitive adhesive sheet according to an embodiment of the present invention may be a single-sided electrically releasing pressure-sensitive adhesive sheet having a conductive substrate and an electrically releasing pressure-sensitive adhesive layer on only one side of the conductive substrate. The electrically releasing pressure-sensitive adhesive sheet according to an embodiment of the present invention may further comprise another pressure-sensitive adhesive layer that does not have electrical release properties, or may further comprise another pressure-sensitive adhesive layer on the surface of the electrically releasing pressure-sensitive adhesive sheet facing the support substrate. The electrically releasing pressure-sensitive adhesive sheet according to an embodiment of the present invention may also be a double-sided electrically releasing pressure-sensitive adhesive sheet having a conductive substrate having conductive carbon layers on both sides of the support substrate, and an electrically releasing pressure-sensitive adhesive layer on each conductive carbon layer. The electrically releasing pressure-sensitive adhesive sheet according to an embodiment of the present invention may have a release liner for the purpose of protecting the electrically releasing pressure-sensitive adhesive layer and the surface of the other pressure-sensitive adhesive layers, but such release liner is not included in the electrically releasing pressure-sensitive adhesive sheet according to an embodiment of the present invention.

[0020] The electrically peelable pressure-sensitive adhesive sheet according to the embodiment of the present invention is also preferably an electrically peelable pressure-sensitive adhesive sheet further comprising another pressure-sensitive adhesive layer, the other pressure-sensitive adhesive layer being formed on the surface of the support substrate opposite to the conductive carbon layer.

[0021] The electrically peelable pressure-sensitive adhesive sheet according to the embodiment of the present invention is also preferably an electrically peelable pressure-sensitive adhesive sheet further comprising an additional pressure-sensitive adhesive layer, a second conductive carbon layer, and a second additional pressure-sensitive adhesive layer, wherein the additional pressure-sensitive adhesive layer is formed on the surface of the support substrate opposite to the conductive carbon layer, and the second conductive carbon layer and the second additional pressure-sensitive adhesive layer are formed in this order on the surface of the electrically peelable pressure-sensitive adhesive layer opposite to the conductive carbon layer.Furthermore, it is also preferable that the electrically peelable pressure-sensitive adhesive layer and the second conductive carbon layer are in contact with each other.

[0022] The structure of the electrically peelable adhesive sheet according to the embodiment of the present invention is not particularly limited, but preferred examples include electrically peelable adhesive sheet X1 shown in FIG. 1, electrically peelable adhesive sheet X2 shown in FIG. 2, and electrically peelable adhesive sheet X3 shown in FIG. 3.

[0023] The electrically peelable pressure-sensitive adhesive sheet X1 shown in FIG. 1 is an electrically peelable pressure-sensitive adhesive sheet having a layer structure of an electrically peelable pressure-sensitive adhesive layer 1 and a conductive substrate 5 (conductive carbon layer C, conductive layer 3, and supporting substrate 4).

[0024] The electrically peelable pressure-sensitive adhesive sheet X2 shown in Figure 2 is an electrically peelable pressure-sensitive adhesive sheet having a layer structure of another pressure-sensitive adhesive layer 6, a conductive substrate 5 (support substrate 4, conductive layer 3, and conductive carbon layer C), and an electrically peelable pressure-sensitive adhesive layer 1.

[0025] The electrically releasing pressure-sensitive adhesive sheet X3 shown in Fig. 3 is an electrically releasing pressure-sensitive adhesive sheet having a layer configuration comprising, in this order, another pressure-sensitive adhesive layer 6, a conductive substrate 5 (support substrate 4, conductive layer 3, and conductive carbon layer C), an electrically releasing pressure-sensitive adhesive layer 1, a conductive substrate 5 (conductive carbon layer C, conductive layer 3, and support substrate 4), and another pressure-sensitive adhesive layer 6. That is, the electrically releasing pressure-sensitive adhesive layer 1 in the electrically releasing pressure-sensitive adhesive sheet X3 shown in Fig. 3 is a double-sided electrically releasing pressure-sensitive adhesive sheet comprising, on both sides thereof, a conductive carbon layer C, a conductive layer 3, a support substrate 4, and another pressure-sensitive adhesive layer 6, in this order.

[0026] The electrically releasing adhesive sheet according to the embodiment of the present invention is particularly effective in the case of electrically releasing adhesive sheet X3, in which the electrically releasing adhesive layer is separated from the conductive carbon layer contained in the electrically releasing adhesive sheet. In such an electrically releasing adhesive sheet, a coating layer has generally been provided adjacent to the electrically releasing adhesive layer. However, when exposed to high temperature and high humidity for a long period of time, the components of the electrically releasing adhesive layer may pass through the coating layer, causing the support substrate and the conductive layer to peel off, and there is a risk that separation will not occur even when a current is applied to the electrically releasing adhesive layer. On the other hand, when a single metal layer is used as the conductive layer, without the above-mentioned coating layer, there is a risk that the metal layer will corrode if exposed to high temperature and high humidity for a long period of time. In contrast, the electrically releasing adhesive sheet according to the embodiment of the present invention allows for good separation between the conductive carbon layer and the electrically releasing adhesive layer by applying current to the electrically releasing adhesive layer, even when exposed to high temperature and high humidity for a long period of time.

[0027] The conductive carbon layer C is a layer in contact with the electrically releasing pressure-sensitive adhesive layer 1. By having the conductive carbon layer C in contact with the electrically releasing pressure-sensitive adhesive layer 1, the electrically releasing function of the electrically releasing pressure-sensitive adhesive sheet is sufficient even when stored in a high-temperature, high-humidity environment for a long period of time, and a decrease in the adhesive strength between the electrically releasing pressure-sensitive adhesive layer and the conductive substrate can be suppressed.

[0028] The conductive carbon layer C according to the embodiment of the present invention is not particularly limited as long as it is made of conductive carbon. From the viewpoint of electrical peeling property and durability under high temperature and humidity for a long period of time, the conductive carbon is preferably sp ２Bonds and sp ３ The conductive carbon layer is preferably formed from carbon atoms having sp bonds. ２ Bonds and sp ３ When formed from carbon atoms with bonds, the conductive carbon layer is a layer having a graphite-type structure and a diamond structure.

[0029] sp on carbon atom ３ The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the sp ３ The ratio of the number of bonded carbon atoms (sp ３ / (sp ３ +sp ２ )) is, for example, 0.1 or more, preferably 0.2 or more, more preferably 0.25 or more, and even more preferably 0.3 or more. ３ The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the sp ３ The ratio of the number of bonded carbon atoms (sp ３ / (sp ３ +sp ２ ) is, for example, 0.9 or less, preferably 0.7 or less.

[0030] sp on carbon atom ３ The ratio of the number of bonded carbon atoms (sp ３ / (sp ３ +sp ２ )) is preferably at least the above lower limit, since the electrically peeling function of the electrically peeling pressure-sensitive adhesive sheet is sufficient even when it is left in a high-temperature, high-humidity environment for a long period of time, and the decrease in the adhesive strength between the electrically peeling pressure-sensitive adhesive layer and the conductive substrate is suppressed. ２ Bond peak intensity and sp ３ The ratio can be calculated based on the peak intensity of the bond. In other words, the ratio can be determined from the ratio of the peak areas of the respective peaks.

[0031] In the conductive carbon layer, the carbon atom is provided with sp ３ The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom is the sum of the number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom. ３ The ratio of the number of bonded carbon atoms is, for example, 20 at% or more, preferably 25 at% or more, more preferably 29 at% or more, and even more preferably 30 at% or more. The ratio of the number of atoms represented by formula (A) is, for example, 90 at% or less, preferably 70 at% or less, more preferably 50 at% or less, and even more preferably 44 at% or less. The ratio of the number of atoms (at%) = carbon atoms to sp ３ Number of carbon atoms bonded / (carbon atoms sp ３ Number of carbon atoms bonded + sp to carbon atoms ２ (number of carbon atoms singly bonded to oxygen atoms + number of carbon atoms singly bonded to nitrogen atoms) × 100 (A)

[0032] When the ratio of the number of atoms represented by formula (A) is equal to or greater than the above-mentioned lower limit, the electrically peeling function of the electrically peeling pressure-sensitive adhesive sheet is sufficient even when the sheet is left in a high-temperature, high-humidity environment for a long period of time, and a decrease in the adhesive strength between the electrically peeling pressure-sensitive adhesive layer and the conductive substrate can be suppressed, which is preferable. ２ Peak intensity and sp of bond (C=C) ３ It can be calculated based on the peak intensity of the C-C bond, the peak intensity of the C-O bond, and the peak intensity of the C-N bond. In other words, the ratio of the number of atoms represented by the formula (A) can be obtained from the ratio of the peak areas of the above peaks.

[0033] The surface roughness Ra of the upper surface of the conductive carbon layer according to an embodiment of the present invention is, for example, 20 nm or less, preferably 10 nm or less, more preferably 5 nm or less, even more preferably 1 nm or less, and most preferably 0.9 nm or less (or less than 1 nm). The surface roughness Ra of the upper surface of the conductive carbon layer is, for example, 0.01 nm or more, or 0.05 nm or more. From the viewpoint of electrical peelability, it is preferable that the surface roughness Ra is below the above upper limit.

[0034] The surface roughness Ra of the upper surface of the conductive carbon layer can be measured by observing a 500 nm square of the upper surface of the conductive carbon layer using an atomic force microscope. Here, the upper surface of the conductive carbon layer refers to the surface of the conductive carbon layer that comes into contact with the electrically peelable pressure-sensitive adhesive layer.

[0035] The surface resistance value of the conductive carbon layer C alone according to the embodiment of the present invention is, for example, 1.0×10 ８ Ω / □ or less, preferably 1.0×10 ３ 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 carbon layer C.

[0036] The surface resistance value of the upper surface of the conductive carbon layer C of the conductive substrate (conductive carbon layer C / conductive layer 3) according to an embodiment of the present invention is, for example, 1.0×10 ４ Ω / □ or less, preferably 1.0×10 ３ Ω / □ or less, and 5.0×10 ２ It may be Ω / □ or less, and 1.0×10 ２ The surface resistance may be Ω / □ or less, 50 Ω / □ or less, 40 Ω / □ or less, or 30 Ω / □ or less. 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 sum of the thicknesses of the conductive carbon layer C and the conductive layer 3.

[0037] The thickness of the conductive carbon layer according to the embodiment of the present invention is preferably 1 nm or more, more preferably 2 nm or more, even more preferably 3 nm or more, and particularly preferably 5 nm or more. The upper limit of the thickness is preferably 200 nm or less, more preferably 100 nm or less, even more preferably 70 nm or less, particularly preferably 50 nm or less, and most preferably 40 nm or less, and may be 30 nm or less, 20 nm or less, or 10 nm or less. It is preferable that the thickness of the conductive carbon layer is equal to or greater than the above-mentioned lower limit from the viewpoint of durability under high temperature and high humidity for a long period of time. On the other hand, it is preferable that the thickness of the conductive carbon layer is equal to or less than the above-mentioned upper limit from the viewpoint of electrical peelability. The thickness of the conductive carbon layer can be calculated by measuring its X-ray reflectance.

[0038] The conductive carbon layer according to the embodiment of the present invention may contain other additives in addition to carbon. The conductive carbon layer may be composed of multiple layers with different structures, compositions, additive concentrations, etc., and may be configured such that the structure, composition, additive concentration, etc. change stepwise (in a gradational manner).

[0039] The conductive carbon layer according to the embodiment of the present invention can be preferably formed by a dry method, such as a PVD method (physical vapor deposition method) or a CVD method (chemical vapor deposition method), and preferably a PVD method.

[0040] Examples of PVD methods include sputtering, vacuum deposition, laser deposition, and ion plating (such as arc deposition). Sputtering is preferred from the viewpoint of reducing the amount of hydrogen contained in the conductive carbon layer and more reliably forming the conductive carbon layer. Examples of sputtering methods include unbalanced magnetron sputtering (UBM sputtering), high-power pulse sputtering, electron cyclotron resonance sputtering, RF sputtering, DC sputtering (such as DC magnetron sputtering), DC pulse sputtering, ion beam sputtering, and ECR sputtering (electron cyclotron resonance sputtering).

[0041] When sputtering is employed, the target material may be carbon (preferably sintered carbon). The target material may contain known additives from the viewpoints of adjusting film quality and process stability.

[0042] Examples of the sputtering gas introduced into the film formation chamber include inert gases such as Ar and Xe.

[0043] The sputtering method is carried out under vacuum. Specifically, the air pressure during sputtering is, for example, 1 Pa or less, preferably 0.7 Pa or less, from the viewpoints of suppressing a decrease in the sputtering rate and ensuring discharge stability. The film formation temperature is, for example, 200°C or less, preferably 120°C or less, and for example, -40°C or more, preferably -10°C or more. In order to form a conductive carbon layer of a desired thickness, the sputtering method may be carried out multiple times by appropriately setting the target material, sputtering conditions, and the like.

[0044] The electrically peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention may include a conductive layer 3. The conductive layer 3 is not particularly limited as long as it is a layer having conductivity, but may be a metal substrate such as a metal (e.g., aluminum, magnesium, copper, iron, tin, gold, etc.) foil or a metal plate (e.g., aluminum, magnesium, copper, iron, tin, silver, etc.), a conductive polymer, or the like, or may be a film formed on a supporting substrate 4 by sputtering or vapor-depositing a metal (niobium, titanium, nickel, copper, aluminum, gold, platinum, iron, silver, tin, silicon, magnesium, SUS alloy, etc.).

[0045] The thickness of the conductive layer 3 according to the embodiment of the present invention is preferably 1 nm or more and 1000 nm or less. The upper limit of the thickness is more preferably 500 nm, even more preferably 300 nm, particularly preferably 200 nm, and most preferably 100 nm, and may be 80 nm, 60 nm, 40 nm, or 20 nm. The lower limit is more preferably 1 nm, and even more preferably 3 nm. The surface resistance value of the upper surface of the conductive layer 3 is, for example, 1.0×10 ４ Ω / □ or less, preferably 1.0×10３ Ω / □ or less, and 5.0×10 ２ It may be Ω / □ or less, and 1.0×10 ２ The surface resistance may be Ω / □ or less, 50 Ω / □ or less, 40 Ω / □ or less, or 30 Ω / □ or less. In this specification, the surface resistance refers to a value that can be calculated by dividing the resistivity measured by a four-terminal method in accordance with JIS K 7194 (1994) by the thickness of the conductive layer 3.

[0046] The support substrate 4 according to the embodiment of the present invention is not particularly limited, but examples thereof include paper-based substrates such as paper, fiber-based substrates such as cloth and nonwoven fabric, plastic-based substrates such as films and sheets made of various plastics (polyolefin-based resins such as polyethylene and polypropylene, polyester-based resins such as polyethylene terephthalate, acrylic resins such as polymethyl methacrylate, etc.), and laminates thereof. The substrate may have a single layer structure or a multi-layer structure. The substrate may be subjected to various treatments such as back surface treatment, antistatic treatment, and primer treatment (adhesion-enhancing treatment) as necessary.

[0047] The thickness of the support substrate 4 according to the embodiment of the present invention can be any thickness depending on the purpose. For example, a thickness of 10 μm or more and 1000 μm or less is preferable. The upper limit of the thickness is more preferably 500 μm, and even more preferably 300 μm, and the lower limit is more preferably 12 μm, and even more preferably 25 μm.

[0048] The conductive substrate 5 according to the embodiment of the present invention is not particularly limited as long as it includes a support substrate 4 and a conductive carbon layer C. For example, a conductive layer may be formed on the surface of the support substrate, and a conductive carbon layer may be further formed on the surface of the conductive layer on the side opposite to the support substrate.

[0049] The thickness of the conductive substrate 5 according to the embodiment of the present invention can be any thickness depending on the purpose. For example, a thickness of 10 μm or more and 1000 μm or less is preferable. The upper limit of the thickness is more preferably 500 μm, even more preferably 300 μm, even more preferably 100 μm, and even more preferably 50 μm. The lower limit is more preferably 12 μm, even more preferably 20 μm.

[0050] The electrically peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention can be attached to a conductive material to form a bonded body. Examples of conductive materials include adherends such as metal surfaces. Examples of metal surfaces include surfaces made of metals primarily composed of aluminum, copper, iron, magnesium, tin, gold, silver, and lead, with aluminum being preferred. Examples of adherends having a metal surface include sheets, parts, and plates made of metals primarily composed of aluminum, copper, iron, magnesium, tin, gold, silver, and lead. Adherends other than those having a metal surface include, but are not limited to, fiber sheets such as paper, cloth, and nonwoven fabric, as well as various plastic films and sheets.

[0051] The electrically releasing pressure-sensitive adhesive layer 1 is a pressure-sensitive adhesive layer whose adhesive strength decreases upon application of a voltage. The electrically releasing pressure-sensitive adhesive layer preferably contains a polymer as an adhesive and an electrolyte. The electrolyte preferably contained in the electrically releasing pressure-sensitive adhesive layer is a substance that can be ionized into anions and cations. Examples of such electrolytes include ionic liquids, alkali metal salts, and alkaline earth metal salts. From the perspective of achieving good electrical peelability in the electrically releasing pressure-sensitive adhesive layer, an ionic liquid is preferred as the electrolyte contained in the electrically releasing pressure-sensitive adhesive layer. An ionic liquid is a salt that is liquid at room temperature (approximately 25°C) and contains an anion and a cation. That is, the electrically releasing pressure-sensitive adhesive layer preferably contains a polymer and an ionic liquid. The electrically releasing pressure-sensitive adhesive layer 1 can be formed from a pressure-sensitive adhesive composition containing a polymer and an ionic liquid. The pressure-sensitive adhesive composition according to an embodiment of the present invention will be described below. Note that, in this specification, the adhesive strength when no voltage is applied may be referred to as "initial adhesive strength." Furthermore, a composition containing components other than the ionic liquid among the components contained in the pressure-sensitive adhesive composition may be referred to as an "ionic liquid-free pressure-sensitive adhesive composition." A pressure-sensitive adhesive layer formed from an ionic liquid-free pressure-sensitive adhesive composition is sometimes referred to as an “ionic liquid-free pressure-sensitive adhesive layer.” The property of adhesive strength decreasing upon voltage application is sometimes referred to as “electrical peeling property,” and a large rate of decrease in adhesive strength upon voltage application is sometimes referred to as “excellent electrical peeling property.”

[0052] <Components of Pressure-Sensitive Adhesive Composition> (Polymer) The pressure-sensitive adhesive composition according to the embodiment of the present invention preferably contains a polymer. In the present embodiment, the polymer is not particularly limited as long as it is a general organic polymer compound, and is, for example, a polymer or partial polymer of a monomer. The monomer may be one type of monomer or a mixture of two or more types of monomers. Note that a partial polymer refers to a polymer in which at least a part of the monomer or monomer mixture is partially polymerized.

[0053] The polymer in this embodiment is not particularly limited as long as it is typically used as a pressure-sensitive adhesive and has adhesive properties, but examples include acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine-based polymers, and epoxy polymers. The polymers can be used alone or in combination of two or more. In order to increase the dielectric constant of the components other than the ionic liquid in the resulting electrically peelable pressure-sensitive adhesive layer and improve the electrical peelability, it is preferable that the polymer have a high dielectric constant. From this perspective, 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. Because polyester polymers have easily polarizable hydroxyl groups at their terminals, and because acrylic polymers having carboxyl groups and / or hydroxyl groups have easily polarizable carboxyl groups and / or hydroxyl groups, the use of these polymers can produce polymers with relatively high dielectric constants. The total content of the polyester polymer and the acrylic polymer having a carboxyl group and / or a hydroxyl group in the polymer according to the embodiment of the present invention is preferably 60% by mass or more, more preferably 80% by mass or more. Furthermore, particularly for improving costs, productivity, and initial adhesive strength, the polymer according to the present embodiment is preferably an acrylic polymer. That is, the pressure-sensitive adhesive composition according to the embodiment of the present invention is preferably an acrylic pressure-sensitive adhesive composition containing an acrylic polymer as the polymer.

[0054] The acrylic polymer preferably contains a monomer unit derived from a (meth)acrylic acid alkyl ester (the following formula (1)) having an alkyl group having 1 to 14 carbon atoms. Such a monomer unit is suitable for obtaining a large initial adhesive strength. In addition, in order to increase the relative dielectric constant of the components of the electrically peelable pressure-sensitive adhesive layer other than the ionic liquid and improve the electrical peelability, the alkyl group R ｂThe number of carbon atoms in is preferably small, particularly preferably 8 or less, and more preferably 4 or less. ２ = C(R ａ ) COOR ｂ (1) [R in formula (1)] ａ is a hydrogen atom or a methyl group, and R ｂ is an alkyl group having 1 to 14 carbon atoms which may have a substituent.

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

[0056] The proportion of the (meth)acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms relative to all 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 the (meth)acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms is 70% by mass or more, a large initial adhesive strength is easily obtained.

[0057] For the purpose of improving cohesive strength, heat resistance, crosslinkability, etc., the acrylic polymer preferably contains a monomer unit derived from a polar group-containing monomer copolymerizable with a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms, in addition to the monomer unit. Such a monomer unit can impart crosslinking points and is suitable for obtaining high initial adhesive strength. Furthermore, from the viewpoint of increasing the relative permittivity of components other than the ionic liquid in the electrically peelable pressure-sensitive adhesive layer and improving electrical peelability, it is also preferable to contain a monomer unit derived from a polar group-containing monomer.

[0058] 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 from the viewpoint of excellent cohesiveness, and carboxyl group-containing monomers are particularly preferred. Carboxyl group-containing monomers are particularly suitable for obtaining high initial adhesive strength. Polar group-containing monomers can be used alone or in combination of two or more.

[0059] 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. The carboxyl group-containing monomers can be used alone or in combination.

[0060] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, N-methylol (meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. 2-Hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are particularly preferred. The hydroxyl group-containing monomers may be used alone or in combination of two or more.

[0061] Examples of amide group-containing monomers include acrylamide, methacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, and diacetoneacrylamide. The amide group-containing monomers can be used alone or in combination of two or more.

[0062] Examples of cyano group-containing monomers include acrylonitrile and methacrylonitrile.

[0063] Examples of vinyl group-containing monomers include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate, with vinyl acetate being particularly preferred.

[0064] Examples of aromatic vinyl monomers include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

[0065] Examples of imide group-containing monomers include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

[0066] Examples of amino group-containing monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate.

[0067] Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and allyl glycidyl ether.

[0068] Examples of vinyl ether monomers include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

[0069] The proportion of the polar group-containing monomer relative 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 polar group-containing monomer proportion is more preferably 25% by mass, even more preferably 20% by mass, and 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 the polar group-containing monomer is 0.1% by mass or more, cohesive strength is easily obtained, so that adhesive residue is less likely to remain on the adherend surface after peeling the electrically-release pressure-sensitive adhesive layer, and the electrical releasability is improved. Furthermore, when the proportion of the polar group-containing monomer is 35% by mass or less, it is easy to prevent the electrically-release pressure-sensitive adhesive layer from excessively adhering to the adherend and causing heavy peeling. In particular, when the proportion is 2% by mass or more and 20% by mass or less, it is easy to achieve both releasability from the adherend and adhesion between the electrically-release pressure-sensitive adhesive layer and the conductive carbon layer.

[0070] Furthermore, the monomer components constituting the acrylic polymer may contain a polyfunctional monomer in order to introduce a crosslinked structure into the acrylic polymer and make it easier to obtain the required cohesive strength.

[0071] 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. The polyfunctional monomers can be used alone or in combination of two or more.

[0072] The content of the polyfunctional monomer 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. When the content of the polyfunctional monomer is 0.1% by mass or more, the flexibility and adhesiveness of the electrically peelable pressure-sensitive adhesive layer are easily improved, which is preferable. When the content of the polyfunctional monomer is 15% by mass or less, the cohesive force is not too high, and appropriate adhesiveness is easily obtained.

[0073] A polyester-based polymer is typically a polymer having a structure in which a polycarboxylic acid such as a dicarboxylic acid or a derivative thereof (hereinafter also referred to as a "polycarboxylic acid monomer") is condensed with a polyhydric alcohol such as a diol or a derivative thereof (hereinafter also referred to as a "polyhydric alcohol monomer").

[0074] The polycarboxylic acid monomer is not particularly limited, but examples thereof 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, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanedioic 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.

[0075] The polyhydric alcohol monomer is not particularly limited, but examples thereof 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 monomers can be used alone or in combination of two or more.

[0076] Furthermore, the polymer according to the embodiment of the present invention may contain an ionic polymer. The ionic polymer is a polymer having an ionic functional group. When the polymer contains the ionic polymer, the relative dielectric constant of the polymer increases, and the electrodetachment property is improved. When the polymer contains the 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.

[0077] In this embodiment, the polymer can be obtained by (co)polymerizing monomer components. The polymerization method is not particularly limited, but examples thereof include solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization (active energy ray polymerization). In particular, from the viewpoints of cost and productivity, solution polymerization is preferred. When copolymerized, the polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, and the like.

[0078] The solution polymerization method is not particularly limited, but examples thereof include a method in which a monomer component, a polymerization initiator, etc. are dissolved in a solvent and heated to polymerize, thereby obtaining a polymer solution containing a polymer.

[0079] As the solvent used in the solution polymerization method, various common solvents can be used. Examples of such solvents (polymerization solvents) include organic solvents such as 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 ketones such as methyl ethyl ketone and methyl isobutyl ketone. The solvents can be used alone or in combination of two or more.

[0080] The amount of the solvent used is not particularly limited, but is preferably 10 parts by mass or more and 1,000 parts by mass or less relative to the total monomer components (100 parts by mass) constituting the polymer. The upper limit of the amount of the solvent used is more preferably 500 parts by mass, and the lower limit is more preferably 50 parts by mass.

[0081] The polymerization initiator used in the solution polymerization method is not particularly limited, but examples thereof include peroxide-based polymerization initiators, azo-based polymerization initiators, etc. Examples of the peroxide-based polymerization initiator are not particularly limited, but examples thereof include peroxycarbonate, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, and peroxyester, and more specific examples thereof 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, etc. The azo polymerization initiator is not particularly limited, but examples thereof include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionate)dimethyl, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), 4,4'-azobis Examples of the polymerization initiator include 4-cyanovaleric acid, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine) hydrochloride, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate. The polymerization initiator can be used alone or in combination of two or more.

[0082] The amount of the polymerization initiator used is not particularly limited, but is preferably 0.01 to 5 parts by mass relative to the total monomer components (100 parts by mass) constituting the polymer. The upper limit of the amount of the polymerization initiator used is more preferably 3 parts by mass, and the lower limit is more preferably 0.05 parts by mass.

[0083] In the solution polymerization method, the heating temperature when polymerizing by heating 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.

[0084] The weight-average molecular weight of the polymer is not particularly limited, but is preferably 100,000 or more and 5,000,000 or less. The upper limit of the weight-average molecular weight is more preferably 4,000,000, even more preferably 3,000,000, and the lower limit is more preferably 200,000, even more preferably 300,000. When the weight-average molecular weight is 100,000 or more, the cohesive force is reduced, and the problem of adhesive residue remaining on the adherend surface after peeling off the electrically-peeling pressure-sensitive adhesive layer can be effectively suppressed. Furthermore, when the weight-average molecular weight is 5,000,000 or less, the problem of insufficient wettability on the adherend surface after peeling off the electrically-peeling pressure-sensitive adhesive layer can be effectively suppressed.

[0085] The weight-average molecular weight is obtained by measurement by gel permeation chromatography (GPC). More specifically, for example, measurement is performed using a GPC measurement device under the trade name "HLC-8220GPC" (manufactured by Tosoh Corporation) under the following conditions, and the weight-average molecular weight can be calculated in terms of a standard polystyrene. (Weight-average molecular weight measurement conditions) Sample concentration: 0.2% by mass (tetrahydrofuran solution) Sample injection amount: 10 μL Sample column: TSKguard column SuperHZ-H (1 column) + TSKgel SuperHZM-H (2 columns) Reference column: TSKgel SuperH-RC (1 column) Eluent: tetrahydrofuran (THF) Flow rate: 0.6 mL / min Detector: differential refractometer (RI) Column temperature (measurement temperature): 40°C

[0086] The glass transition temperature (Tg) of the polymer is not particularly limited, but is preferably 0° C. or lower because this can suppress a decrease in the initial adhesive strength, more preferably −10° C. or lower, and even more preferably −20° C. or lower. Furthermore, if it is −40° C. or lower, the rate of decrease in adhesive strength due to voltage application becomes particularly large, so it is particularly preferred, and most preferably −50° C. or lower.

[0087] The glass transition temperature (Tg) can be calculated, for example, based on the following formula (Y) (Fox formula): 1 / Tg=W1 / Tg1+W2 / Tg2+ ... +Wn / Tgn ... (Y) [In formula (Y), Tg is the glass transition temperature (unit: K) of the polymer, Tgi (i = 1, 2, ... n) is the glass transition temperature (unit: K) when monomer i forms a homopolymer, and Wi (i = 1, 2, ... n) is the mass fraction of monomer i in all monomer components] The above formula (Y) is a calculation formula when a polymer is composed of n types of monomer components, i.e., monomer 1, monomer 2, ..., monomer n.

[0088] The glass transition temperature when a homopolymer is formed refers to the glass transition temperature of a homopolymer of the monomer, and refers to the glass transition temperature (Tg) of a polymer formed using only a certain monomer (sometimes referred to as "monomer X") as the monomer component. Specific values ​​are listed in "Polymer Handbook" (3rd Edition, John Wiley & Sons, Inc., 1989). The glass transition temperature (Tg) of a homopolymer not described in this document refers to a value obtained, for example, by the following measurement method. Specifically, 100 parts by mass of monomer X, 0.2 parts by mass of 2,2'-azobisisobutyronitrile, and 200 parts by mass of ethyl acetate as a polymerization solvent are placed in a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and the mixture is stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature is raised to 63°C and the reaction is allowed to proceed for 10 hours. The mixture is then cooled to room temperature to obtain a homopolymer solution with a solids concentration of 33% by mass. Next, this homopolymer solution is cast onto a release liner and dried to prepare a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. Approximately 1 to 2 mg of this test sample is weighed into an aluminum open cell, and the reversing heat flow (specific heat component) behavior of the homopolymer is measured using a temperature-modulated DSC (trade name "Q-2000" manufactured by TA Instruments) at a heating rate of 5°C / min under a nitrogen atmosphere of 50 ml / min. Referring to JIS K 7121 (2012), the glass transition temperature (Tg) of the homopolymer is determined as the temperature at the point where a line equidistant in the vertical direction from a line extending the low-temperature baseline and the high-temperature baseline of the obtained reversing heat flow intersects with the curve representing the stepwise change in the glass transition.

[0089] The polymer content in the pressure-sensitive adhesive composition according to the embodiment of the present invention is preferably 50% by mass or more and 99.9% by mass or less, relative to the total amount (100% by mass) of the pressure-sensitive adhesive composition, the upper limit is more preferably 99.5% by mass, and even more preferably 99% by mass, and the lower limit is more preferably 60% by mass, and even more preferably 70% by mass.

[0090] (Ionic Liquid) The ionic liquid in this embodiment is not particularly limited as long as it is a molten salt (room-temperature molten salt) composed of a pair of anion and cation and is liquid at 25° C. Examples of anions and cations are given below, but among the ionic substances obtained by combining these, those that are liquid at 25° C. are ionic liquids, and those that are solid at 25° C. are not ionic liquids but are ionic solids described below.

[0091] The anion of the ionic liquid is, for example, (FSO ２ ) ２ N － , (CF ３ SO ２ ) ２ N － , (CF ３ CF ２ SO ２ ) ２ N － , (CF ３ SO ２ ) ３ C － ,Br － , AlCl ４ － , Al ２ Cl ７ － , NO ３ － , B.F. ４ － , P.F. ６ － , C.H. ３ COO － , C.F. ３ COO － , C.F. ３ CF ２ CF ２ COO － , C.F. ３ SO ３ － , C.F. ３ (CF ２ ) ３ SO ３ － , AsF ６ － , SbF ６ － , and F(HF) ｎ －Among them, the anion is (FSO ２ ) ２ N － [bis(fluorosulfonyl)imide anion], and (CF ３ SO ２ ) ２ N － Anions of sulfonylimide compounds such as bis(trifluoromethanesulfonyl)imide anions are preferred because they are chemically stable and suitable for improving electrical peelability. That is, the anion of the ionic liquid is preferably at least one selected from the group consisting of bis(fluorosulfonyl)imide anions and bis(trifluoromethanesulfonyl)imide anions.

[0092] The cation in the ionic liquid is preferably at least one selected from the group consisting of nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations, as these are chemically stable and suitable for improving electrical peelability, and imidazolium-based, ammonium-based, pyrrolidinium-based, and pyridinium-based cations are more preferred.

[0093] Examples of imidazolium cations include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-nonyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, and 1-dodecyl-3-methylimidazolium cation. imidazolium cation, 1-tridecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1-pentadecyl-3-methylimidazolium cation, 1-hexadecyl-3-methylimidazolium cation, 1-heptadecyl-3-methylimidazolium cation, 1-octadecyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, 1-benzyl-3-methylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, and 1,3-bis(dodecyl)imidazolium cation.

[0094] Examples of pyridinium cations include 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, and 1-octyl-4-methylpyridinium cation.

[0095] Examples of pyrrolidinium cations include 1-ethyl-1-methylpyrrolidinium cation and 1-butyl-1-methylpyrrolidinium cation.

[0096] Examples of ammonium-based cations include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethylacrylate cation.

[0097] From the viewpoint of increasing the rate of decrease in adhesive strength when a voltage is applied, it is preferable to select a cation having a molecular weight of 160 or less as the constituent cation of the ionic liquid. ２ ) ２ N － [bis(fluorosulfonyl)imide anion] or (CF ３ SO ２ ) ２ N － Particularly preferred is an ionic liquid containing a bis(trifluoromethanesulfonyl)imide anion and a cation having a molecular weight of 160 or less. Examples of the cation having a molecular weight of 160 or less include a 1-methylimidazolium cation, a 1-ethyl-3-methylimidazolium cation, a 1-propyl-3-methylimidazolium cation, a 1-butyl-3-methylimidazolium cation, a 1-pentyl-3-methylimidazolium cation, a 1-butylpyridinium cation, a 1-hexylpyridinium cation, a 1-butyl-3-methylpyridinium cation, a 1-butyl-4-methylpyridinium cation, a 1-ethyl-1-methylpyrrolidinium cation, a 1-butyl-1-methylpyrrolidinium cation, a tetraethylammonium cation, a glycidyltrimethylammonium cation, and a trimethylaminoethyl acrylate cation.

[0098] Furthermore, as the cation of the ionic liquid, cations represented by the following formulas (2-A) to (2-D) are also preferred.

[0099]

[0100] R in formula (2-A) １ 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), which may contain a heteroatom; R ２ and R ３ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, and even more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may contain a heteroatom. However, when a nitrogen atom forms a double bond with an adjacent carbon atom, R３ does not exist.

[0101] R in formula (2-B) ４ represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), which may contain a heteroatom; R ５ , R ６ , and R ７ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, and even more preferably a hydrocarbon group having 2 to 4 carbon atoms), which may contain a heteroatom.

[0102] R in formula (2-C) ８ represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), which may contain a heteroatom; R ９ , R １０ , and R １１ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 16 carbon atoms (preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 8 carbon atoms), which may contain a heteroatom.

[0103] In formula (2-D), X represents a nitrogen, sulfur, or phosphorus atom; １２ , R １３ , R １４ , and R １５ are the same or different and represent a hydrocarbon group having 1 to 16 carbon atoms (preferably a hydrocarbon group having 1 to 14 carbon atoms, more preferably a hydrocarbon group having 1 to 10 carbon atoms, even more preferably a hydrocarbon group having 1 to 8 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 6 carbon atoms), which may contain a heteroatom. However, when X is a sulfur atom, R １２ does not exist.

[0104] The molecular weight of the cation in the ionic liquid is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, even more preferably 250 or less, particularly preferably 200 or less, and most preferably 160 or less. It is usually 50 or more. It is believed that the cation in the ionic liquid has the property of migrating to the cathode side in the electrically releasing pressure-sensitive adhesive layer upon application of a voltage, and being biased toward the interface between the electrically releasing pressure-sensitive adhesive layer and the adherend. For this reason, in the present invention, the adhesive strength during voltage application decreases relative to the initial adhesive strength, resulting in electro-releasability. Cations with a small molecular weight, such as a molecular weight of 500 or less, are suitable for facilitating the migration of cations to the cathode side in the electrically releasing pressure-sensitive adhesive layer and increasing the rate of decrease in adhesive strength upon application of a voltage.

[0105] Examples of commercially available ionic liquids include "ELEXEL AS-110," "ELEXEL MP-442," "ELEXEL IL-210," "ELEXEL MP-471," "ELEXEL MP-456," and "ELEXEL AS-804" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; "HMI-FSI" manufactured by Mitsubishi Materials Corporation; and "CIL-312" and "CIL-313" manufactured by Nippon Carlit Co., Ltd.

[0106] The ionic conductivity is preferably 0.1 mS / cm or more and 10 mS / cm or less. The upper limit of the ionic conductivity is more preferably 5 mS / cm, even more preferably 3 mS / cm, and the lower limit is more preferably 0.3 mS / cm, even more preferably 0.5 mS / cm. By having an ionic conductivity in this range, the adhesive strength is sufficiently reduced even at a low voltage. The ionic conductivity can be measured by the AC impedance method, for example, using a Solartron 1260 frequency response analyzer.

[0107] The content (blending amount) of the electrolyte or ionic liquid in the pressure-sensitive adhesive composition according to the embodiment of the present invention is preferably 0.5 parts by mass or more relative to 100 parts by mass of the polymer in order to reduce adhesive strength during voltage application, and preferably 30 parts by mass or less in order to increase initial adhesive strength. From the same viewpoint, it is more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and most preferably 5 parts by mass or less. Furthermore, it is more preferably 0.6 parts by mass or more, even more preferably 0.8 parts by mass or more, particularly preferably 1.0 part by mass or more, and most preferably 1.5 parts by mass or more.

[0108] (Other Components) The pressure-sensitive adhesive composition according to the embodiment of the present invention may contain one or more components other than the polymer and the ionic liquid (hereinafter, sometimes referred to as "other components"), as needed, within a range that does not impair the effects of the present invention. Hereinafter, other components that may be contained in the pressure-sensitive adhesive composition according to the embodiment of the present invention will be described.

[0109] The pressure-sensitive adhesive composition according to the embodiment of the present invention may contain an ionic additive. As the ionic additive, for example, an ionic solid can be used.

[0110] The ionic solid is an ionic substance that is solid at 25° C. There are no particular limitations on the ionic solid, but for example, a solid ionic substance obtained by combining an anion and a cation as exemplified in the section describing the ionic liquid above can be used. When the pressure-sensitive adhesive composition contains an ionic solid, the content of the ionic solid is preferably 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polymer.

[0111] The pressure-sensitive adhesive composition according to the present invention may contain a crosslinking agent, if necessary, for the purpose of improving creep resistance and shear resistance 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-xylylene diamine, diglycidyl aniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and 1,6-hexanediol diglycidyl ether. When a crosslinking agent is contained, the content thereof is preferably 0.1 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the polymer. The crosslinking agents may be used alone or in combination of two or more.

[0112] The pressure-sensitive adhesive composition according to the embodiment of the present invention may contain polyethylene glycol, if necessary, to aid the movement of the ionic liquid when a voltage is applied. As the polyethylene glycol, one having a number average molecular weight of 200 to 6000 can be used. When polyethylene glycol is contained, the content is preferably 0.1 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the polymer.

[0113] The pressure-sensitive adhesive composition according to the embodiment of the present invention may contain a conductive filler, if necessary, for the purpose of imparting electrical conductivity to the pressure-sensitive adhesive composition. The conductive filler is not particularly limited, and a commonly known or commonly used conductive filler can be used, such as graphite, carbon black, carbon fiber, or metal powder such as silver or copper. When a conductive filler is contained, the content thereof is preferably 0.1 parts by mass or more and 200 parts by mass or less relative to 100 parts by mass of the polymer.

[0114] The pressure-sensitive adhesive composition according to the embodiment of the present invention may also contain various additives such as fillers, plasticizers, antioxidants, antioxidants, pigments (dyes), flame retardants, solvents, surfactants (leveling agents), rust inhibitors, adhesion-imparting 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 the polymer.

[0115] 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. Examples of plasticizers that can be used include known and commonly used plasticizers used in general resin compositions, and examples of such plasticizers include oils such as paraffin oil and process oil, liquid rubbers such as liquid polyisoprene, liquid polybutadiene, and liquid ethylene-propylene rubber, tetrahydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, citric acid, and derivatives thereof, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate, diisononyl adipate (DINA), and isodecyl succinate. Examples of antioxidants include hindered phenol compounds, aliphatic and aromatic hindered amine compounds, etc. Examples of antioxidants include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA). Examples of pigments include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, and sulfate, and organic pigments such as azo pigments and copper phthalocyanine pigments. Examples of rust inhibitors include zinc phosphate, tannic acid derivatives, phosphate esters, basic sulfonates, and various rust-preventive pigments. Examples of adhesion promoters include titanium coupling agents and zirconium coupling agents. Examples of antistatic agents generally include quaternary ammonium salts, or hydrophilic compounds such as polyglycolic acid and ethylene oxide derivatives. Examples of tackifying resins include rosin-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, as well as polyamide-based tackifying resins, epoxy-based tackifying resins, and elastomer-based tackifying resins. These tackifying resins can be used alone or in combination of two or more.Examples of corrosion inhibitors include carbodiimide compounds, adsorption inhibitors, and chelating-type metal deactivators. For example, those described in JP 2019-059908 A can be used.

[0116] <Initial Adhesion Strength, Electrical Peel Strength, and Decrease Rate of Adhesion Strength Due to Voltage Application> The adhesion strength of the electrically peelable pressure-sensitive adhesive layer according to the embodiment of the present invention can be evaluated by various methods, for example, the 180° peel test described in the Examples section.

[0117] The pressure-sensitive adhesive composition according to the embodiment of the present invention preferably has an initial adhesive strength of 2.0 N / cm or more, more preferably 2.5 N / cm or more, and even more preferably 3.0 N / cm or more, as measured by forming a pressure-sensitive adhesive sheet as described in the Examples section and conducting a 180° peel test. When the initial adhesive strength is 3.0 N / cm or more, the adhesion to the adherend is sufficient, and the adherend is unlikely to peel off or slip.

[0118] Furthermore, it is preferable that the adhesive composition according to the embodiment of the present invention forms an adhesive sheet as described in the Examples section, and the adhesive strength measured in a 180° peel test immediately after applying a voltage of 30 V for 30 seconds, i.e., the electrical peel strength, is sufficiently smaller than the initial adhesive strength.

[0119] The pressure-sensitive adhesive composition according to the embodiment of the present invention is formed into a pressure-sensitive adhesive sheet as described in the Examples section, and the electrical peel strength measured in a 180° peel test after applying a voltage of 30 V for 30 seconds is preferably 1.0 N / cm or less, more preferably 0.5 N / cm or less, even more preferably 0.3 N / cm or less, and particularly preferably less than 0.1 N / cm. When the electrical peel strength is 1.0 N / cm or less, the electrical peelability is excellent, resulting in improved reworkability and ease of recycling.

[0120] The electrically peelable pressure-sensitive adhesive layer according to an embodiment of the present invention is formed into an electrically peelable pressure-sensitive adhesive sheet as described in the Examples section, and after long-term storage under high temperature and high humidity conditions, the adhesive strength when no voltage is applied, as measured by a 180° peel test, is preferably 2.0 N / cm or more, more preferably 2.5 N / cm or more, and most preferably 3.0 N / cm or more. When the adhesive strength when no voltage is applied is 3.0 N / cm or more, the adhesion to the adherend is sufficient and the adherend is unlikely to peel off or slip.

[0121] The electrically releasing pressure-sensitive adhesive layer according to an embodiment of the present invention is prepared by forming an electrically releasing pressure-sensitive adhesive sheet as described in the Examples section, storing it under high temperature and high humidity for a long period of time, and then applying a voltage of 30 V for 30 seconds, followed by a 180° peel test. The electrical peel strength measured is, for example, preferably 2.0 N / cm or less, more preferably 1.0 N / cm or less, even more preferably 0.5 N / cm or less, particularly preferably 0.3 N / cm or less, and most preferably less than 0.1 N / cm. The greater the difference from the initial adhesive strength, the better the electrical peelability, and the difference from the initial adhesive strength is, for example, preferably 3.0 N / cm or more, more preferably 6.0 N / cm or more.

[0122] The applied voltage is preferably 1 V or more, more preferably 3 V or more, more preferably 5 V or more, more preferably 6 V or more, and even more preferably 10 V or more. It is also preferably 500 V or less, more preferably 300 V or less, even more preferably 100 V or less, and particularly preferably 50 V or less. The voltage application time is 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 this case, workability is excellent. The shorter the application time, the better, but it is usually 1 second or more.

[0123] The pressure-sensitive adhesive composition according to an embodiment of the present invention is not particularly limited, but can be produced by appropriately stirring and mixing a polymer, an ionic liquid, and additives, such as a crosslinking agent, polyethylene glycol, and a conductive filler, which may be blended as needed.

[0124] From the viewpoint of initial adhesive strength, the thickness of the electrically peeling pressure-sensitive adhesive layer 1 is preferably 1 μm or more and 1,000 μm or less. The upper limit of the thickness of the electrically peeling pressure-sensitive 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, even more preferably 50 μm, and the lower limit is more preferably 5 μm, even more preferably 10 μm, even more preferably 20 μm, even more preferably 30 μm.

[0125] The thickness of the electrically peelable pressure-sensitive 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 the lower limit is more preferably 30 μm, even more preferably 50 μm.

[0126] In particular, in the case of electrically peelable pressure-sensitive adhesive sheets X1 and X2 shown in Figures 1 and 2, the thickness of the electrically peelable pressure-sensitive 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 the lower limit is more preferably 30 μm, even more preferably 50 μm, even more preferably 100 μm.

[0127] In particular, in the case of the electrically peelable pressure-sensitive adhesive sheet X3 shown in Fig. 3, the thickness of the electrically peelable pressure-sensitive adhesive sheet is preferably 50 µm or more and 3000 µm or less. The upper limit of the thickness is more preferably 1000 µm, and even more preferably 500 µm, and the lower limit is more preferably 50 µm, and even more preferably 100 µm, and even more preferably 200 µm.

[0128] The electrically releasing adhesive layer of the electrically releasing adhesive sheet according to an embodiment of the present invention, and the surface of the adhesive layer if any, may be protected by a release liner. Examples of release liners include, but are not limited to, release liners in which the surface of a substrate (liner substrate) such as paper or plastic film is silicone-treated, and release liners 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, but is not limited to, preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less.

[0129] [Method for manufacturing electrically releasing pressure-sensitive adhesive sheet] The electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention can be manufactured by a known or conventional manufacturing method. The electrically releasing pressure-sensitive adhesive layer in the electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention can be formed by, for example, applying a solution of the pressure-sensitive adhesive composition according to the embodiment of the present invention, optionally in a solvent, onto a release liner, followed by drying and / or curing. When other pressure-sensitive adhesive layers are provided, the other pressure-sensitive adhesive layers can be formed by, for example, applying a solution of the pressure-sensitive adhesive composition, optionally in a solvent, onto a release liner, followed by drying and / or curing. The solvents and release liners listed above can be used.

[0130] For application, a conventional coater (for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray roll coater, etc.) can be used.

[0131] The above-described method can be used to produce an electrically peelable pressure-sensitive adhesive layer and other pressure-sensitive adhesive layers, and by appropriately laminating a conductive substrate, an electrically peelable pressure-sensitive adhesive layer, and, if necessary, other pressure-sensitive adhesive layers, an electrically peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention can be produced.

[0132] [Method for Electrically Peeling Electrically Peelable Pressure-Sensitive Adhesive Sheet] Peeling of the electrically peelable pressure-sensitive adhesive sheet according to the embodiment of the present invention from an adherend can be achieved by applying a voltage to the electrically peelable pressure-sensitive adhesive layer to generate a potential difference in the thickness direction of the electrically peelable pressure-sensitive adhesive layer. For example, an assembly in which electrically peelable pressure-sensitive adhesive sheet X1 or X2 is attached to a conductive adherend can be peeled by passing a current between the conductive carbon layer and the conductive adherend and applying a voltage to the electrically peelable pressure-sensitive adhesive layer. For example, in the case of electrically peelable pressure-sensitive adhesive sheet X3, it can be peeled from the adherend by passing a current through both conductive carbon layers and applying a voltage to the electrically peelable pressure-sensitive adhesive layer. The current is preferably applied by connecting terminals to one end and the other end of the electrically peelable pressure-sensitive adhesive sheet so that a voltage is applied to the entire electrically peelable pressure-sensitive adhesive layer. Note that, if the adherend has a metal surface, the one end and the other end may be part of the adherend having a metal surface. Note that, during peeling, water may be added to the interface between the adherend surface of the conductive adherend and the electrically peelable pressure-sensitive adhesive layer before applying a voltage.

[0133] [Uses of Electrically Releaseable Pressure-Sensitive Adhesive Sheets] Conventional re-peeling technologies include adhesive layers that are cured and peeled by ultraviolet (UV) irradiation, and adhesive layers that peel off by heat. Electrically releaseable pressure-sensitive adhesive sheets using such adhesive layers cannot be used in cases where ultraviolet (UV) irradiation is difficult or where heat damages the adherend. The electrically releaseable pressure-sensitive adhesive sheet according to an embodiment of the present invention, which includes the electrically releaseable pressure-sensitive adhesive layer, does not use ultraviolet or heat, and therefore can be easily peeled off by applying a voltage without damaging the adherend. Therefore, the electrically releaseable pressure-sensitive adhesive sheet according to an embodiment of the present invention is suitable for use in fixing secondary batteries (e.g., lithium-ion battery packs) used in mobile devices such as smartphones, mobile phones, laptops, video cameras, and digital cameras to the housings.

[0134] In addition, examples of rigid members that can be bonded with the electrically peelable pressure-sensitive adhesive sheet according to the embodiment of the present invention include silicon substrates for semiconductor wafers, sapphire substrates for LEDs, SiC substrates and metal-based substrates, TFT substrates and color filter substrates for displays, and base substrates for organic EL panels. Examples of fragile members that can be bonded with the double-sided electrically peelable pressure-sensitive 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.

[0135] [Joint] The joined structure according to an embodiment of the present invention comprises an electrically peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention and a conductive material, in which the electrically peelable pressure-sensitive adhesive layer of the electrically peelable pressure-sensitive adhesive sheet is adhered to the conductive material. The conductive material is preferably an adherend having a metal adhesion surface. Examples of adherends having a metal adhesion surface include those made of a metal primarily composed of aluminum, copper, iron, magnesium, tin, gold, silver, lead, etc., and among these, metals containing aluminum are preferred.

[0136] An example of a bonded body according to an embodiment of the present invention is a bonded body in which the electrically peelable pressure-sensitive adhesive layer 1 side of the electrically peelable pressure-sensitive adhesive sheet X1 is attached to a conductive adherend having, for example, a metal adherend surface.

[0137] In the case where the electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention further comprises another pressure-sensitive adhesive layer, a second conductive substrate containing a resin component, and a second other pressure-sensitive adhesive layer, the other pressure-sensitive adhesive layer being formed on the surface of the support substrate opposite the conductive carbon layer, the second conductive substrate and the second other pressure-sensitive adhesive layer being formed in this order on the surface of the electrically releasing pressure-sensitive adhesive layer opposite the conductive carbon layer, and the electrically releasing pressure-sensitive adhesive layer and the second conductive substrate being in contact with each other, another aspect of the joined body according to the embodiment of the present invention is a joined body comprising the electrically releasing pressure-sensitive adhesive sheet according to the embodiment of the present invention and an adherend material, and the other pressure-sensitive adhesive layer being attached to the adherend material. The adherend material is selected from conductive materials and non-conductive materials.

[0138] Examples of the bonded body according to the embodiment of the present invention include a bonded body in which the other adhesive layers 6 on both sides of the electrically peeling adhesive sheet X3 are adhered to a conductive material having, for example, a metal coating surface, and a bonded body in which any of the other adhesive layers 6 in the electrically peeling adhesive sheet X3 are adhered to a non-conductive material.

[0139] As explained above, the present specification discloses the following: <1> An electrically peelable pressure-sensitive adhesive sheet comprising: a conductive substrate including a support substrate and a conductive carbon layer; and an electrically peelable pressure-sensitive adhesive layer whose adhesive strength decreases upon application of a voltage, wherein the electrically peelable pressure-sensitive adhesive layer and the conductive carbon layer are in contact with each other. <2> The conductive carbon layer is sp ２ Bonds and sp ３ <3> The electrically peelable pressure-sensitive adhesive sheet according to <1>, wherein the conductive carbon layer is formed from carbon having a bond represented by the following formula (A): ３ The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom is the sum of the number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom. ３ <1> or <2>, wherein the ratio of the number of bonded carbon atoms is 20 at % or more. ３Number of carbon atoms bonded / (carbon atoms sp ３ Number of carbon atoms bonded + sp to carbon atoms ２ (number of carbon atoms singly bonded to oxygen atoms + number of carbon atoms singly bonded to nitrogen atoms) × 100 (A) <4> The electrically releasing pressure-sensitive adhesive sheet according to any one of <1> to <3>, wherein the electrically releasing pressure-sensitive adhesive layer contains a polymer and an electrolyte. <5> The electrically releasing pressure-sensitive adhesive sheet according to <4>, wherein the content of the electrolyte is 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the polymer. <6> The electrically releasing pressure-sensitive adhesive sheet according to <4> or <5>, wherein the electrolyte is an ionic liquid, and the anion of the ionic liquid is at least one selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion. <7> The electrically releasing pressure-sensitive adhesive sheet according to any one of <4> to <6>, wherein the electrolyte is an ionic liquid, and the cation of the ionic liquid is at least one selected from the group consisting of nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations. <8> The electrically releasing pressure-sensitive adhesive sheet according to any one of <1> to <7>, further comprising an additional pressure-sensitive adhesive layer, the additional pressure-sensitive adhesive layer being formed on the surface of the support substrate opposite the conductive carbon layer. <9> The electrically releasing pressure-sensitive adhesive sheet according to any one of <1> to <7>, further comprising an additional pressure-sensitive adhesive layer, a second conductive carbon layer, and a second additional pressure-sensitive adhesive layer, the additional pressure-sensitive adhesive layer being formed on the surface of the support substrate opposite the conductive carbon layer, the second conductive carbon layer and the second additional pressure-sensitive adhesive layer being formed in this order on the surface of the electrically releasing pressure-sensitive adhesive layer opposite the conductive carbon layer. <10> A joined body comprising the electrically releasing pressure-sensitive adhesive sheet according to any one of <1> to <8> and a conductive material, the electrically releasing pressure-sensitive adhesive layer being adhered to the conductive material. <11> A joined body comprising the electrically releasing pressure-sensitive adhesive sheet according to <9> and an adherend material, the additional pressure-sensitive adhesive layer being adhered to the adherend material.

[0140] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The weight average molecular weights shown below were measured by gel permeation chromatography (GPC) using the method described above.

[0141] (Preparation of Acrylic Polymer Solution) As monomer components, 87 parts by mass of n-butyl acrylate (BA), 10 parts by mass of 2-methoxyethyl acrylate (MEA), 3 parts by mass of acrylic acid (AA), and 150 parts by mass of ethyl acetate as a polymerization solvent were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the mixture was heated to 63 ° C. and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer solution with a solids concentration of 30% by mass. The weight average molecular weight of the obtained acrylic polymer was 700,000.

[0142] [Example 1] (Preparation of electrically peelable pressure-sensitive adhesive layer) The acrylic polymer (solution), a crosslinking agent, an ionic liquid, an additive (corrosion inhibitor), and ethyl acetate obtained above were added and stirred and mixed to obtain an electrically peelable pressure-sensitive adhesive composition (solution) adjusted to a solids concentration of 25 mass %.

[0143] Table 1 shows the blending amount of each component. The value of each component in Table 1 below means parts by mass. The obtained electrically peelable pressure-sensitive adhesive composition (solution) was applied to a uniform thickness using an applicator onto the release-treated surface of a polyethylene terephthalate separator (trade name "MRF38", manufactured by Mitsubishi Chemical Corporation) whose surface had been release-treated. This was then heated and dried at 150°C for 3 minutes, and the release-treated surface of a polyethylene terephthalate separator (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation) whose surface had been release-treated was laminated onto the pressure-sensitive adhesive using a hand roller, to obtain an electrically peelable pressure-sensitive adhesive layer having a thickness of 60 μm.

[0144] The abbreviations for the ionic liquid, crosslinking agent, and corrosion inhibitor in Table 1 are as follows:

[0145] (Ionic liquid) AS-110: cation: 1-ethyl-3-methylimidazolium cation, anion: bis(fluorosulfonyl)imide anion, trade name "Elexel AS-110", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (Crosslinking agent) V-05: polycarbodiimide resin, trade name "Carbodilite V-05", manufactured by Nisshinbo Chemical Inc. (Corrosion inhibitor) Amine O: 2-(8-heptadecen-1-yl)-4,5-dihydro-1H-imidazole-1-ethanol, trade name "AMINE O", manufactured by BASF Japan Ltd. Irgacor DSSG: sodium sebacate, trade name "Irgacor DSSG", manufactured by BASF Japan Ltd. Irgamet 30: N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, trade name "Irgamet 30", manufactured by BASF Japan Ltd.

[0146] (Preparation of Single-Sided PSA Sheet with Substrate) The obtained electrically releasing adhesive layer was cut into a sheet measuring 10 mm x 80 mm, and the release liner (MRE38) was peeled off. The surface of the exposed electrically releasing adhesive layer was attached to the conductive carbon layer side of a conductive substrate (10 mm x 100 mm) so that it protruded about 20 mm from one edge of the adhesive layer, to obtain a single-sided PSA sheet with a substrate. Here, the conductive substrate was prepared as follows. A niobium (Nb) layer (conductive layer) was formed on the surface of a supporting substrate PET (polyethylene terephthalate approximately 25 μm, manufactured by Mitsubishi Chemical Corporation) by DC magnetron sputtering to a thickness of 32 nm. Thereafter, a conductive carbon layer made of conductive carbon and having a thickness of 10 nm (in this specification, a conductive carbon layer having a thickness of nanometer order is also referred to as a "nanocarbon layer") was subsequently formed by the same method, to obtain a conductive substrate. The sputtering conditions were as follows: niobium and sintered carbon were used as target materials, the argon pressure was 0.2 Pa, the target power was 1.6 kW and 2.3 kW, respectively, and the substrate temperature was 120° C. or lower.

[0147] The surface resistance value of the upper surface of the conductive carbon layer of the conductive substrate was calculated by dividing the resistivity measured by the four-terminal method in accordance with JIS K 7194 (1994) by the sum of the thicknesses of the conductive carbon layer C and the conductive layer 3.

[0148] (sp ２ Bonds (C=C) and sp ３ Measurement of C-C bonds, C-O single bonds, and C-N single bonds) X-ray photoelectron spectroscopy was performed on the upper surface of each conductive carbon layer under the following measurement conditions. Specifically, narrow scan spectra were obtained for carbon, nitrogen, oxygen, and fluorine on one side of the measurement sample in the thickness direction (surface of the conductive carbon layer), and the element ratios were calculated from the ratios of the areas of each peak. Furthermore, in the C1s narrow scan spectrum, sp ２ Peaks attributable to bonds (C=C), sp ３ The peaks attributable to the bond (C-C), the peaks attributable to COO or -N(H)COO, the peaks attributable to C-O or C-N, and the peaks attributable to C=O or >NC(=O) were confirmed. ２ Bonded carbon atoms and sp ３ The areas of the peaks corresponding to the carbon atoms bonded (C-C), the C-O single bond, and the C-N single bond were determined. The peak tops were assigned as follows: ２ Peak attributable to bond (C═C): ​​284.0 eV to 284.5 eV sp ３ Peak attributable to bond (C-C): 285.0 eV Peak attributable to C-O or C-N: 286.0 eV to 287.0 eV Peak attributable to C=O or >NC(=O): 287.3 eV to 288.2 eV Peak attributable to COO or -N(H)COO: 288.3 eV to 289.2 eV From the ratio of the obtained peak areas, the peak attributable to the carbon atom represented by the following formula (A) was determined. ３ The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom is the sum of the number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom. ３The ratio of the number of bonded carbon atoms was calculated. The results are shown in Table 1. Ratio of the number of atoms (at%) = sp to carbon atoms ３ Number of carbon atoms bonded / (carbon atoms sp ３ Number of carbon atoms bonded + sp to carbon atoms ２ (number of carbon atoms singly bonded to oxygen atoms + number of carbon atoms singly bonded to nitrogen atoms) × 100 ... (A) <Measurement conditions> Measurement device: X-ray photoelectron spectrometer (manufactured by Shimadzu Corporation, product name "KRATOS ULTRA2") X-ray source: Monochrome Al Kα X Ray setting: 700 μm × 300 μm [5 mA, 75 W, Resolution 20] Photoelectron take-off angle: 90 degrees to the sample surface Charge neutralization conditions: Charge neutralization mechanism used Analysis fitting software: ESCApe

[0149] (Preparation of 5-layer electrically peelable pressure-sensitive adhesive sheet) The release liner (MRF38) was peeled off from a single-sided pressure-sensitive adhesive sheet with a substrate, and the conductive carbon layer side of the same conductive substrate as used in preparing the single-sided pressure-sensitive adhesive sheet was attached to the peeled surface as an adherend, so that it protruded from one edge of the pressure-sensitive adhesive sheet by about 20 mm, and the sheet was pressed back and forth once with a 2 kg roller and left to stand for 72 hours in an environment of 23° C. Furthermore, a double-sided tape (product name "No. 56405", manufactured by Nitto Denko Corporation) was attached to the surface of the conductive substrate facing the support substrate, to obtain a 5-layer electrically peelable pressure-sensitive adhesive sheet of Example 1 in which both surfaces were made of the other pressure-sensitive adhesive.

[0150] (Preparation of Bonded Structure) The release liner on one side of the five-layer electrically peeling pressure-sensitive adhesive sheet obtained above was peeled off, and an acrylic plate (size: 30 mm × 80 mm) was attached as an adherend to the peeled surface so that one end of the pressure-sensitive adhesive sheet protruded from the adherend by about 20 mm, and the sheet was pressed back and forth once with a 2 kg roller, and left to stand in an environment of 23°C for 72 hours, to obtain a bonded structure in which the other pressure-sensitive adhesive layer of the five-layer electrically peeling pressure-sensitive adhesive sheet was attached to the adherend.

[0151] [Example 2] A five-layer electrically peelable pressure-sensitive adhesive sheet and an assembly of Example 2 were obtained using the same procedures and conditions as in Example 1, except that in the preparation of the conductive substrate, the formation of the conductive layer was changed to the formation of a titanium (Ti) layer by DC magnetron sputtering, and the thickness of the conductive layer was changed to 8 nm.

[0152] [Example 3] A five-layer electrically peelable pressure-sensitive adhesive sheet and an assembly of Example 3 were obtained using the same procedures and conditions as in Example 1, except that in the preparation of the conductive substrate, the formation of the conductive layer was changed to the formation of an aluminum (Al) layer by DC magnetron sputtering, and the thickness of the conductive layer was changed to 30 nm.

[0153] [Example 4] A five-layer electrically peelable pressure-sensitive adhesive sheet and an assembly of Example 4 were obtained using the same procedures and conditions as in Example 1, except that in the preparation of the conductive substrate, the formation of the conductive layer was changed to the formation of a stainless steel (SUS) layer by DC magnetron sputtering, and the thickness of the conductive layer was changed to 30 nm.

[0154] [Example 5] In preparing a conductive substrate, a niobium (Nb) layer was formed on the surface of the conductive substrate by DC magnetron sputtering to a thickness of 32 nm. Then, a 10 nm-thick nanocarbon layer made of conductive carbon was subsequently formed using a high-power impulse magnetron (HiPIMS). The five-layer electrically peelable pressure-sensitive adhesive sheet and bonded body of Example 5 were obtained under the same procedures and conditions as in Example 1. The sputtering conditions were as follows: niobium and sintered carbon were used as target materials, the argon pressure was 0.2 Pa, and the substrate temperature was 120°C or less. The target power for the Nb layer was 1.6 kW, and the applied voltage for the carbon layer was 1.7 kV, with a pulse width of 30 μs and a frequency of 210 Hz.

[0155] Comparative Example 1 A five-layer electrically peelable pressure-sensitive adhesive sheet and assembly of Comparative Example 1 were obtained using the same procedures and conditions as in Example 1, except that in producing the conductive substrate, no carbon layer was formed and only a niobium layer was formed on the supporting substrate.

[0156] Comparative Example 2 A five-layer electrically peelable double-sided PSA sheet and assembly of Comparative Example 2 were obtained using the same procedures and conditions as in Example 1, except that a metal layer-attached film (product name "1005CR", Toray Advanced Film Co., Ltd.), which is a laminate comprising a resin coating layer, a conductive layer (aluminum metal layer), and a support substrate laminated in this order, was used as the conductive substrate.

[0157] [Evaluation] Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated as follows. (Initial Adhesion Strength) The initial adhesion strength was measured in accordance with the measurement for the three-layer electrically peelable pressure-sensitive adhesive sheet shown in Fig. 4. That is, as shown in Fig. 5, the produced bonded body was set in a peel tester (product name "Variable Angle Peel Tester YSP", Asahi Seiko Co., Ltd.), the conductive substrate on the side opposite the acrylic plate was chucked, and the bonded body was peeled in the direction of the arrow in Fig. 5 so as to peel from the electrically peelable pressure-sensitive adhesive layer 1, and the initial adhesion strength was measured in a 180° peel test (tensile speed: 300 mm / min, peel temperature: 23°C).

[0158] (Electrical Peeling Force) Before peeling, an electrode was attached to each of the two conductive substrates of the bonded structure. The positive pole of a DC current machine was attached to the conductive substrate closest to the adherend, and the negative pole was attached to the other conductive substrate. A voltage of 30 V was applied for 30 seconds, and immediately thereafter, the bonded structure was peeled off from the electrically releasing pressure-sensitive adhesive layer 1. The electrical peeling force was measured in the same manner as in the measurement of the initial adhesive strength described above.

[0159] (Humidity and heat resistance test) 60°C, 90% RH, 600 hours The bonded body was stored in a thermo-hygrostat at 60°C, 90% RH for 600 hours, and after removal, it was left to stand at 22°C, 50% RH for 30 minutes to cool down. Thereafter, the electrical peeling force was measured in the same manner as in the electrical peeling force measurement described above.

[0160] The results obtained are shown in Table 1.

[0161]

[0162] The results in Table 1 show that the electrically peelable pressure-sensitive adhesive sheets of Examples 1 to 5 not only had good adhesive properties (initial adhesive strength and electrical peel strength), but also showed a sufficiently small electrical peel strength in the moist heat resistance test, thereby achieving good results.

[0163] On the other hand, it was shown that the electrically peelable pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 could not achieve both good adhesive properties and good resistance to moist heat.

[0164] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0165] This application is based on a Japanese patent application (Patent Application No. 2024-013138) filed on January 31, 2024, the contents of which are incorporated herein by reference.

[0166] The electrically peelable pressure-sensitive adhesive sheet of the present invention can be used, for example, to fix a secondary battery used in a mobile terminal to a housing, and to join rigid or fragile members.

[0167] X1, X2, X3 Electrically peelable pressure-sensitive adhesive sheet 1 Electrically peelable pressure-sensitive adhesive layer 3 Conductive layer 4 Support substrate 5 Conductive substrate 6 Other pressure-sensitive adhesive layer 7 Conductive adherend 7' Non-conductive adherend 8 Laminate C Conductive carbon layer

Claims

1. An electrically peelable pressure-sensitive adhesive sheet comprising: a conductive substrate including a support substrate and a conductive carbon layer; and an electrically peelable pressure-sensitive adhesive layer whose adhesive strength decreases upon application of a voltage, wherein the electrically peelable pressure-sensitive adhesive layer and the conductive carbon layer are in contact with each other.

2. The conductive carbon layer is sp ２ Bonds and sp ３ The electrically releasable pressure-sensitive adhesive sheet according to claim 1 , which is formed from carbon atoms having bonds.

3. In the conductive carbon layer, a carbon atom is provided with sp ３ The number of carbon atoms bonded and the carbon atom ２ The number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom is the sum of the number of carbon atoms bonded to the oxygen atom and the number of carbon atoms bonded to the nitrogen atom. ３ 2. The electrically peelable pressure-sensitive adhesive sheet according to claim 1, wherein the ratio of the number of bonded carbon atoms is 20 at % or more. ３ Number of carbon atoms bonded / (carbon atoms sp ３ Number of carbon atoms bonded + sp to carbon atoms ２ (number of carbon atoms singly bonded to oxygen atoms + number of carbon atoms singly bonded to nitrogen atoms) × 100 (A) 4. The electrically peelable pressure-sensitive adhesive sheet according to claim 1, wherein the electrically peelable pressure-sensitive adhesive layer contains a polymer and an electrolyte.

5. The electrically peelable pressure-sensitive adhesive sheet according to claim 4, wherein the content of the electrolyte is 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the polymer.

6. The electrically peelable pressure-sensitive adhesive sheet according to claim 4, wherein the electrolyte is an ionic liquid, and the anion of the ionic liquid is at least one selected from the group consisting of a bis(fluorosulfonyl)imide anion and a bis(trifluoromethanesulfonyl)imide anion.

7. The electrically peelable pressure-sensitive adhesive sheet according to claim 4, wherein the electrolyte is an ionic liquid, and the cation of the ionic liquid is at least one selected from the group consisting of nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations.

8. The electrically peelable adhesive sheet according to claim 1, further comprising another adhesive layer, said other adhesive layer being formed on the surface of said support substrate opposite said conductive carbon layer.

9. The electrically peeling adhesive sheet according to claim 1, further comprising another adhesive layer, a second conductive carbon layer, and a second other adhesive layer, wherein the other adhesive layer is formed on the surface of the support substrate opposite to the conductive carbon layer, and the second conductive carbon layer and the second other adhesive layer are formed in this order on the surface of the electrically peeling adhesive layer opposite to the conductive carbon layer.

10. A bonded body comprising the electrically peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 8 and a conductive material, wherein the electrically peelable pressure-sensitive adhesive layer is adhered to the conductive material.

11. A bonded body comprising the electrically peelable adhesive sheet according to claim 9 and an adherend material, wherein the other adhesive layer is attached to the adherend material.

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