Electrically peelable adhesive sheet

Abstract

To provide a novel electric peelable adhesive sheet that is less prone to a short circuit by, for example, voltage application, and facilitates a reduction of adhesion.SOLUTION: An electric peelable adhesive sheet includes a conductive base material (Y) and a layer (X) laminated on at least part of one or both faces of the conductive base material (Y). The layer (X) includes: an electric peelable adhesive layer (X1) that is composed of an electric peelable adhesive composition, which can show a reduction of adhesion in response to voltage application, and includes a surface (β) in contact with the conductive base material (Y) and an adhesive surface (α) which can be bonded to a conductive adherend; and an insulating layer (X2). When the layer (X) is viewed from the adhesive surface (α) side in plan view, the adhesive surface (α) exists at a position surrounded by the insulating layer (X2).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrically peelable pressure-sensitive adhesive sheet and a method for peeling off a conductive adherend. [Background technology]

[0002] One of the properties required for a pressure-sensitive adhesive sheet is removability, for example, in applications such as temporary fixing tapes, surface protection films, painting or decorative masking tapes, and removably removable memos. A removable adhesive sheet is required to have sufficient adhesive strength when applied to an adherend so that it will not peel off from the adherend during transportation, storage, processing, etc., yet is also required to be easily removable once it has completed fulfilling its function.

[0003] As adhesives used in such removable adhesive sheets, various electrically removable adhesive sheets have been proposed, the adhesive strength of which can be reduced by application of a voltage. For example, Patent Document 1 discloses an electrically peelable adhesive sheet having an electrically conductive substrate having a conductive layer and a substrate layer, an electrically peelable first adhesive layer formed on the conductive layer side, and a second adhesive layer formed on the substrate layer side, in which the electrically conductive substrate has an extension portion that extends beyond the first adhesive layer and the second adhesive layer in the surface extension direction of the adhesive sheet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-156914 A Summary of the Invention [Problem to be solved by the invention]

[0005] Since the electro-releasable pressure-sensitive adhesive sheet described in Patent Document 1 has an extending portion where the energizing base material extends in the plane direction, for example, when it is used for temporary fixing of electronic components, the extending portion of the energizing base material may come into contact with other members, which may cause malfunction and problems of electronic devices. In addition, when applying a voltage by connecting electrodes to the conductive adherend and the energizing base material respectively to peel off the electro-releasable pressure-sensitive adhesive sheet attached from the conductive adherend, the energizing base material may come into contact with the conductive adherend and cause a short circuit. Under such circumstances, for example, there is a demand for a novel electro-releasable pressure-sensitive adhesive sheet that is less likely to cause a short circuit and can easily reduce the adhesive force by applying a voltage.

Means for Solving the Problems

[0006] The present invention provides an electro-releasable pressure-sensitive adhesive sheet having a conductive base material and a layer laminated on at least a part of one side or the surface of the conductive adherend, the layer including an electro-releasable pressure-sensitive adhesive layer and an insulating layer, and when the layer is viewed in plan from the adhesive surface side, the adhesive surface (α) is located at a position surrounded by the insulating layer (X2). Specifically, the present invention provides the following aspects. [1] Having a conductive base material (Y) and a layer (X) laminated on at least a part of one side or both sides of the conductive base material (Y), The layer (X) is formed from an electro-releasable pressure-sensitive adhesive composition whose adhesiveness can be reduced by applying a voltage, and includes an electro-releasable pressure-sensitive adhesive layer (X1) having a surface (β) in contact with the conductive base material (Y) and an adhesive surface (α) that can be attached to the conductive adherend, and an insulating layer (X2). When the layer (X) is viewed in plan from the adhesive surface (α) side, the adhesive surface (α) is located at a position surrounded by the insulating layer (X2). Electro-releasable pressure-sensitive adhesive sheet. [2] The electro-releasable pressure-sensitive adhesive sheet according to [1] above, wherein at least a part of the surface of the insulating layer (X2) is in contact with the conductive base material (Y). [3]When the layer (X) is viewed in a plan view from the pressure-sensitive adhesive surface (α) side, the electrical peelable pressure-sensitive adhesive sheet according to the above [1] or [2], wherein at least one of the outer peripheral end portion of the pressure-sensitive adhesive surface (α) and the inner peripheral end portion of the insulating layer (X2) forms a boundary between the pressure-sensitive adhesive surface (α) and the insulating layer (X2). [4]The electrical peelable pressure-sensitive adhesive sheet according to any one of the above [1] to [3], wherein when the layer (X) is viewed in a plan view from the pressure-sensitive adhesive surface (α) side, the insulating layer (X2) is positioned so as to be substantially parallel to the outer peripheral end portion with a void portion (X3) interposed therebetween at at least a part of the outer peripheral end portion of the pressure-sensitive adhesive surface (α). [5]The electrical peelable pressure-sensitive adhesive sheet according to any one of the above [1] to [4], wherein the pressure-sensitive adhesive layer (X1) and the insulating layer (X2) are adjacent to each other in the plane direction. [6]The electrical peelable pressure-sensitive adhesive sheet according to any one of the above [1] to [5], wherein at least a part of the insulating layer (X2) is laminated on the pressure-sensitive adhesive layer (X1). [7]The electrical peelable pressure-sensitive adhesive sheet according to [6] above, wherein the insulating layer (X2) is laminated on the pressure-sensitive adhesive layer (X1) without contacting the conductive base material (Y). [8]The electrical peelable pressure-sensitive adhesive sheet according to any one of the above [1] to [7], wherein the insulating layer (X2) includes a resin layer containing a resin. [9]The electrical peelable pressure-sensitive adhesive sheet according to any one of the above [1] to [8], wherein the insulating layer (X2) is a release material.

[10] Formed from an electrical peelable pressure-sensitive adhesive composition capable of reducing adhesiveness by applying a voltage, having a pressure-sensitive adhesive surface (α) capable of adhering to a first conductive adherend and a pressure-sensitive adhesive surface (β) capable of adhering to a second conductive adherend on the opposite side of the pressure-sensitive adhesive surface (α), and having a layer (X) including a pressure-sensitive adhesive layer (X1) and an insulating layer (X2), When the layer (X) is viewed in a plan view from at least one side of the pressure-sensitive adhesive surfaces (α) and (β), the pressure-sensitive adhesive surface (α) or (β) is present at a position surrounded by the insulating layer (X2). Electrical peelable pressure-sensitive adhesive sheet.

[11] A method for peeling a conductive adherend attached to the pressure-sensitive adhesive surface (α) of the electrical peelable pressure-sensitive adhesive sheet according to any one of the above [1] to [9], The peeling method having the following steps (1a) to (3a). · Step (1a): A step of electrically connecting the conductive base material (Y) of the electrically peelable adhesive sheet and the electrode (I), and electrically connecting the surface of the conductive adherend and the electrode (II). · Step (2a): A step of applying a voltage between the electrodes (I) and (II). · Step (3a): A step of peeling the conductive adherend from the adhesive surface (α).

[12] A method for peeling a first conductive adherend attached to the adhesive surface (α) or a second conductive adherend attached to the adhesive surface (β) of the electrically peelable adhesive sheet described in

[10] above, A peeling method having the following steps (1b) to (3b). · Step (1b): A step of electrically connecting the first conductive adherend and the electrode (I), and electrically connecting the surface of the second conductive adherend and the electrode (II). · Step (2b): A step of applying a voltage between the electrodes (I) and (II). · Step (3b): A step of peeling the first conductive adherend or the second conductive adherend from the adhesive surface (α) or the adhesive surface (β).

Advantages of the Invention

[0007] The electrically peelable adhesive sheet according to a preferred embodiment of the present invention is less likely to cause a short circuit by applying a voltage, and can easily reduce the adhesive force.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0009] The numerical ranges described in this specification can be arbitrarily combined with the upper limit value and the lower limit value. For example, when the numerical range is described as "preferably 20 to 120, more preferably 40 to 90", ranges such as "20 to 90" and "40 to 120" are also included in the numerical ranges described in this specification. Further, for example, when the numerical range is described as "preferably 20 or more, more preferably 40 or more, and preferably 120 or less, more preferably 90 or less", ranges such as "20 to 90" and "40 to 120" are also included in the numerical ranges described in this specification. In addition, as the numerical range described in this specification, for example, the description "60 to 100" means a range of "60 or more and 100 or less".

[0010] In this specification, for example, "(meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms. In addition, the "active ingredient" of the electrically peelable pressure-sensitive adhesive composition means the components included in the electrically peelable pressure-sensitive adhesive composition excluding the diluting solvents such as water and organic solvents.

[0011] In this specification, the thickness of each layer constituting the electrically peelable pressure-sensitive adhesive sheet means a value measured in accordance with JIS K6783, Z1702, and Z1709. For example, it can be measured using a constant pressure thickness measuring instrument (manufactured by Techlock Co., Ltd., product name "PG-02J").

[0012] In this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values in terms of polystyrene measured by gel permeation chromatography (GPC) method, specifically, the values measured based on the method described in the examples.

[0013] In this specification, the determination of whether the object is "conductive" or "insulating" can be made based on the following test method. (Test method for determining conductivity or insulation) Connect the object through lead wires in the middle of an electric circuit in which a DC power supply device and a pea lamp are connected in series to create an electric circuit. Note that the tip of the lead wire is brought into contact with the surface of the object to be connected to the adherend. Apply a voltage of 2.5 V with the DC power supply device and visually observe whether the pea lamp lights up when the created electric circuit is energized. If the lighting of the pea lamp is confirmed, the object is determined to be "conductive". On the other hand, if the lighting of the pea lamp cannot be confirmed, the object is determined to be "insulating (non-conductive)".

[0014] In this specification, the determination of whether the target adhesive layer has "electrical peelability" can be made based on the following test method. (Test method for determining electrical peelability or not) Lay aluminum foil (for example, manufactured by Nippon Metal Foil Industry Co., Ltd., product name "Aluminum Tan Tai S Gloss 50 Fukoka", thickness: 50 μm) on one adhesive surface of the target adhesive layer to prepare a test sheet. Stick the other adhesive surface of the adhesive layer of the test sheet to a stainless steel plate (SUS304, 360# polished) as the adherend, and use a roller with a weight of 2 kg to reciprocate once to press the test sheet onto the adherend. Then, after standing for 30 minutes after sticking in an environment of 23°C and 50% RH (relative humidity), it is used as a measurement sample. Note that two measurement samples are prepared. For one of the measurement samples, in an environment of 23°C and 50% RH (relative humidity), using a tensile testing machine (for example, manufactured by Orientec Co., Ltd., product name "Tensilon"), under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180°, the value measured when the test sheet of the measurement sample is peeled from the adherend (unit: N / 25 mm) is defined as the adhesive strength before voltage application. Next, for the other adhesive strength measurement sample, using a voltage application device (for example, manufactured by Takasago Seisakusho Co., Ltd., product name "KH-100H"), connect the anode terminal to the aluminum foil of the test sheet and the cathode terminal to the stainless steel plate as the adherend, and apply a voltage of 10 V for 60 seconds. Then, after leaving it for 1 minute after voltage application, in an environment of 23°C and 50% RH (relative humidity), using a tensile testing machine, under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180°, the value measured when the test sheet of the measurement sample is peeled is defined as the adhesive strength after voltage application. From the values of the adhesive strength before and after voltage application, the adhesive strength reduction rate is calculated by the following formula (f1). · Formula (f1): [Adhesive strength reduction rate (%)] = 100 - [Adhesive strength after voltage application] / [Adhesive strength before voltage application] × 100 Here, if the above adhesive strength reduction rate is 50% or more, the adhesive layer to be measured is determined to be an "electrically peelable adhesive layer". On the other hand, if the adhesive strength reduction rate is less than 50%, the adhesive layer to be measured is determined to be a "non-electrically peelable adhesive layer".

[0015] [Configuration of Electrically Peelable Adhesive Sheet] The electrically peelable adhesive sheet according to one aspect of the present invention (hereinafter, also simply referred to as "adhesive sheet") has a conductive substrate (Y) and a layer (X) laminated on at least a part of the surface of one or both sides of the conductive substrate (Y). The layer (X) included in the adhesive sheet according to one aspect of the present invention includes an electrically peelable adhesive layer (X1) and an insulating layer (X2). The electrically peelable adhesive layer (X1) is a layer formed from an electrically peelable adhesive composition whose adhesiveness can be reduced by applying a voltage, and has a surface (β) in contact with the conductive substrate (Y) and an adhesive surface (α) that can be attached to the conductive adherend. Then, in the pressure-sensitive adhesive sheet according to one aspect of the present invention, when the layer (X) is viewed in a plan view from the pressure-sensitive adhesive surface (α) side, the pressure-sensitive adhesive surface (α) is present at a position surrounded by the insulating layer (X2).

[0016] Figs. 1 to 4 show an example of the configuration of the electrically peelable pressure-sensitive adhesive sheet with the conductive substrate (Y) according to the first to fourth aspects of the present invention. In each figure, (a) is a schematic perspective view of the pressure-sensitive adhesive sheet, (b) is a schematic plan view when the layer (X) is viewed in a plan view from the pressure-sensitive adhesive surface (α) side, and (c) is a schematic cross-sectional view when the pressure-sensitive adhesive sheet is cut in the thickness direction z by a straight line Z1-Z2 extending in the direction x. As in the pressure-sensitive adhesive sheet shown in Figs. 1 to 4, the surface (β) of the electrically peelable pressure-sensitive adhesive layer (X1) included in the pressure-sensitive adhesive sheet according to one aspect of the present invention is brought into contact with and adhered to the conductive substrate (Y), and the pressure-sensitive adhesive surface (α) is adhered to a conductive adherend (not shown in Figs. 1 to 4). In the pressure-sensitive adhesive sheet shown in Figs. 1 to 4, the pressure-sensitive adhesive surface (α) is exposed. However, in order to protect the pressure-sensitive adhesive surface (α), the pressure-sensitive adhesive sheet according to one aspect of the present invention may have a configuration in which a release material is further laminated on the pressure-sensitive adhesive surface (α).

[0017] After a conductive adherend is adhered to the pressure-sensitive adhesive surface (α) of the electrically peelable pressure-sensitive adhesive layer (X1) included in the pressure-sensitive adhesive sheet according to one aspect of the present invention, when the conductive adherend is peeled from the pressure-sensitive adhesive surface (α), electrodes are electrically connected to the conductive substrate (Y) and the conductive adherend, respectively, and a voltage is applied. Then, a current flows through the inside of the electrically peelable pressure-sensitive adhesive layer (X1) via the conductive substrate (Y) and the conductive adherend, and the adhesive force of the electrically peelable pressure-sensitive adhesive layer (X1) decreases. As a result, the conductive adherend can be easily peeled from the pressure-sensitive adhesive surface (α).

[0018] Here, in the process of electrically connecting electrodes to the conductive substrate (Y) and the conductive adherend and applying a voltage, there is a concern that a short circuit may occur if the conductive substrate (Y) and the conductive adherend come into contact with each other. Also, during the process of applying a voltage, due to some factor, for example, the electrode connected to the conductive adherend may become detached, and a situation may occur where the electrode comes into contact with the conductive substrate (Y). In such a case, a short circuit may also occur. To avoid the occurrence of such a short circuit, for example, as shown in the plan view of FIG. 1(b), in the adhesive sheet of one aspect of the present invention, when the layer (X) is viewed in plan from the adhesive surface (α) side, the adhesive surface (α) of the electrically peelable adhesive layer (X1) is provided so as to be located within a position surrounded by the insulating layer (X2). Here, since the adhesive surface (α) is located within a position surrounded by the insulating layer (X2), when an electrode is electrically connected to the conductive adherend attached to the adhesive surface (α) and a voltage is applied, the presence of the insulating layer (X2) makes it difficult for the electrode to come into contact with the conductive substrate (Y). As a result, the adhesive sheet of one aspect of the present invention can effectively prevent the occurrence of a short circuit.

[0019] In this specification, "viewing the layer (X) in plan from the adhesive surface (α) side" means, for example, in the adhesive sheet 1A of FIG. 1(a), observing the layer (X) existing on the x-y plane from the adhesive surface (α) side along the thickness direction z. For example, when the adhesive sheet 1A of FIG. 1(a) is viewed in plan from the adhesive surface (α) side, the adhesive sheet 1A is observed as shown in FIG. 1(b). Also, when another layer such as a release material is laminated on the adhesive surface (α) and the adhesive surface (α) cannot be directly observed, after removing the other layer laminated on the adhesive surface (α), it is observed in plan view.

[0020] In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the area ratio [(α) / (X2)] of the pressure-sensitive adhesive surface (α) of the electrically peelable pressure-sensitive adhesive layer (X1) to the insulating layer (X2) when the layer (X) is viewed in plan from the pressure-sensitive adhesive surface (α) side is appropriately set according to the type and size of the conductive adherend. From the viewpoint of ensuring a pressure-sensitive adhesive surface (α) sufficient for attaching to the conductive adherend, it may be 10 / 90 or more, 15 / 85 or more, 20 / 80 or more, 25 / 75 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, 45 / 55 or more, 50 / 50 or more, 55 / 45 or more, 60 / 40 or more, 65 / 35 or more, 70 / 30 or more, 75 / 25 or more, or 80 / 20 or more. Also, from the viewpoint of obtaining a pressure-sensitive adhesive sheet that can effectively prevent the occurrence of a short circuit, it may be 95 / 5 or less, 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, 60 / 40 or less, 55 / 45 or less, 50 / 50 or less, 45 / 55 or less, 40 / 60 or less, 35 / 65 or less, 30 / 70 or less, 25 / 75 or less, or 20 / 80 or less.

[0021] Further, the position where the insulating layer (X2) is provided is not particularly limited as long as, when the layer (X) is viewed in plan from the pressure-sensitive adhesive surface (α) side, the pressure-sensitive adhesive surface (α) is disposed at a position surrounded by the insulating layer (X2). In this specification, "the pressure-sensitive adhesive surface (α) is disposed at a position surrounded by the insulating layer (X2)" means that, as shown in FIGS. 1(b), 3(b), and 4(b), when the layer (X) is viewed in plan from the pressure-sensitive adhesive surface (α) side, at least one of the outer peripheral end portion of the pressure-sensitive adhesive surface (α) and the inner peripheral end portion of the insulating layer (X2) is located at the boundary between the pressure-sensitive adhesive surface (α) and the insulating layer (X2), including the mode in which the pressure-sensitive adhesive surface (α) and the insulating layer (X2) are positioned. As another aspect, as shown in FIG. 2(b), when the layer (X) is viewed in plan from the pressure-sensitive adhesive surface (α) side, the inner peripheral end portion (x21) of the insulating layer (X2) is positioned so as to be substantially parallel to at least a part of the outer peripheral end portion (x11) of the pressure-sensitive adhesive surface (α) of the electrically peelable pressure-sensitive adhesive layer (X1) with a gap portion (X3) therebetween. In the present specification, "substantially parallel" includes not only the case where the angle formed by the straight line of the outer peripheral end portion (x11) of the adhesive surface (α) in a plan view and the straight line of the inner peripheral end portion (x21) of the insulating layer (X2) facing the outer peripheral end portion (x11) is 0 degrees, but also the case where the formed angle has a slight inclination that can be regarded as substantially parallel (for example, when the formed angle is 5 degrees or less, preferably 2 degrees or less). Also, the void portion (X3) is included as one of the components of the layer (X).

[0022] In an embodiment such as the adhesive sheet 2A shown in FIG. 2, from the viewpoint of making the adhesive sheet capable of effectively preventing the occurrence of a short circuit, the average value of the interval d of the void portions (X3) is preferably 10.0 mm or less, more preferably 8.0 mm or less, more preferably 6.0 mm or less, still more preferably 5.0 mm or less, still more preferably 4.0 mm or less, even more preferably 3.0 mm or less, particularly preferably 2.0 mm or less, and may also be 0.1 mm or more, 0.5 mm or more, 0.7 mm or more, or 1.0 mm or more. Note that the "interval d of the void portion (X3)" is, for example, represented by the interval d in FIG. 2(c), and means the distance between the outer peripheral end portion (x11) of the electrically peelable adhesive layer (X1) and the inner peripheral end portion (x21) on the electrically peelable adhesive layer (X1) side of the insulating layer (X2). Also, the "average value of the interval d of the void portion (X3)" can be calculated from the average value of the intervals d at five arbitrarily selected locations among the void portions (X3).

[0023] In the adhesive sheet according to one embodiment of the present invention, the thickness of the electrically peelable adhesive layer (X1) and the thickness of the insulating layer (X2) may be substantially the same as in the adhesive sheets 1A and 2A shown in FIGS. 1 and 2, or may be adjusted to be different from each other as in the adhesive sheet 3A shown in FIG. 3. The phrase "the thickness of the electrically peelable pressure-sensitive adhesive layer (X1) is substantially the same as the thickness of the insulating layer (X2)" means that the ratio [(X1) / (X2)] of the thickness of the electrically peelable pressure-sensitive adhesive layer (X1) to the thickness of the insulating layer (X2) is in the range of 45 / 55 to 55 / 45. However, the ratio [(X1) / (X2)] may also be 46 / 54 to 54 / 46, 47 / 53 to 53 / 47, 48 / 52 to 52 / 48, 49 / 51 to 51 / 49, or 49.5 / 50.5 to 50.5 / 49.5.

[0024] Further, in the pressure-sensitive adhesive sheet of one aspect of the present invention, the ratio [(X1) / (X2)] of the thickness of the electrically peelable pressure-sensitive adhesive layer (X1) to the thickness of the insulating layer (X2) is appropriately adjusted according to the type and size of the adherend, etc., and may be 5 / 95 or more, 10 / 90 or more, 15 / 85 or more, 20 / 80 or more, 25 / 75 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, or 45 / 55 or more. Also, it may be 95 / 5 or less, 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, 60 / 40 or less, or 55 / 45 or less.

[0025] In one aspect of the present invention, as in the pressure-sensitive adhesive sheets 1A, 2A, and 3A shown in FIGS. 1 to 3, the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) may be configured to be adjacent in the plane direction (the x-y plane in FIGS. 1(b), 2(b), and 3(b)). Note that the configuration in which "the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) are adjacent in the plane direction" is not limited to the configuration of the pressure-sensitive adhesive sheet 1A in FIG. 1. As in the pressure-sensitive adhesive sheet 2A in FIG. 2, a configuration in which at least a part of the boundary between the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) is adjacent via a void portion (X3) is also included. Also, as in the pressure-sensitive adhesive sheet 3A in FIG. 3, although the thicknesses of the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) are different, a configuration in which they are adjacent in the plane direction is also included.

[0026] Further, in the pressure-sensitive adhesive sheet of one aspect of the present invention, as in the pressure-sensitive adhesive sheets 1A, 2A, and 3A shown in FIGS. 1 to 3, a configuration may be adopted in which at least a part of the surface of the insulating layer (X2) is in contact with the conductive base material (Y). In this configuration, the area ratio [(X1) / (X2)] of the electrically peelable adhesive layer (X1) and the insulating layer (X2) in contact with the conductive substrate (Y) is appropriately set according to the type and size of the conductive adherend. However, from the viewpoint of ensuring an adhesive surface (α) sufficient for attaching to the conductive adherend, it may be 10 / 90 or more, 15 / 85 or more, 20 / 80 or more, 25 / 75 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, 45 / 55 or more, 50 / 50 or more, 55 / 45 or more, 60 / 40 or more, 65 / 35 or more, 70 / 30 or more, 75 / 25 or more, or 80 / 20 or more. Also, from the viewpoint of obtaining an adhesive sheet that can effectively prevent the occurrence of a short circuit, it may be 95 / 5 or less, 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, 60 / 40 or less, 55 / 45 or less, 50 / 50 or less, 45 / 55 or less, 40 / 60 or less, 35 / 65 or less, 30 / 70 or less, 25 / 75 or less, or 20 / 80 or less.

[0027] The adhesive sheet according to one aspect of the present invention may have a configuration in which at least a part of the insulating layer (X2) is laminated on the electrically peelable adhesive layer (X1). In this aspect, as in the adhesive sheet 4A shown in FIG. 4, the insulating layer (X2) may be laminated on the electrically peelable adhesive layer (X1) without contacting the conductive substrate (Y). The adhesive sheet 4A shown in FIG. 4 has a configuration in which an electrically peelable adhesive (X1) is laminated on a conductive substrate (Y), and an insulating layer (X2) is further laminated on a part of the surface of the electrically peelable adhesive (X1). In the adhesive sheet 1A shown in FIG. 4, the surface of the electrically peelable adhesive (X1) on which the insulating layer (X2) is not laminated becomes the adhesive surface (α) and is attached to the conductive adherend. In view of obtaining an adhesive sheet with good productivity because the formation of the insulating layer (X2) is easy, in the adhesive sheet 4A shown in FIG. 4, the insulating layer (X2) is preferably composed of a release material. The release material used as the insulating layer (X2) is preferably a release material that has been cut by punching in advance so that the adhesive surface (α) of the electrically peelable adhesive (X1) is exposed by removing a part thereof. Details of the release material will be described later.

[0028] The pressure-sensitive adhesive sheet according to one aspect of the present invention may have a configuration in which a layer (X) is provided on one side of a conductive base material (Y), like the pressure-sensitive adhesive sheets shown in FIGS. 1 to 4, or may have a configuration in which layers (X) are provided on both sides of the conductive base material (Y), respectively.

[0029] Furthermore, the pressure-sensitive adhesive sheet according to one aspect of the present invention may have a configuration in which the layer (X) is laminated on all the surfaces on one side or both sides of the conductive base material (Y), like the pressure-sensitive adhesive sheets shown in FIGS. 1 to 4, or may have a configuration in which the layer (X) is laminated on some of the surfaces on one side or both sides of the conductive base material (Y), and the remaining surfaces are exposed without the layer (X) being laminated. However, from the viewpoint of obtaining a pressure-sensitive adhesive sheet that can effectively suppress the occurrence of short circuits, the smaller the area ratio of the surface of the conductive base material (Y) on the side where the layer (X) is laminated and exposed without the layer (X) being laminated, the more preferable it is. In the pressure-sensitive adhesive sheet according to one aspect of the present invention, from the above viewpoint, the area ratio occupied by the surface on which the layer (X) is laminated with respect to the total area 100 of the surface of the conductive base material (Y) on the side where the layer (X) is laminated is preferably 50 to 100, more preferably 60 to 100, still more preferably 70 to 100, further preferably 80 to 100, even more preferably 90 to 100, and particularly preferably 95 to 100.

[0030] 〔Configuration of the Electrically Peelable Pressure-Sensitive Adhesive Sheet without a Base Material〕 One aspect of the present invention also provides an electrically peelable pressure-sensitive adhesive sheet without a base material (hereinafter, also referred to as an "adhesive sheet without a base material"). The adhesive sheet without a base material according to one aspect of the present invention is formed from an electrically peelable pressure-sensitive adhesive composition whose adhesiveness can be reduced by applying a voltage, and has an electrically peelable pressure-sensitive adhesive layer (X1) having an adhesive surface (α) that can be attached to a first conductive adherend and an adhesive surface (β) that can be attached to a second conductive adherend on the side opposite to the adhesive surface (α), and an insulating layer (X2). And, in the adhesive sheet without a base material according to one aspect of the present invention, when the layer (X) is viewed in a plan view from at least one side of the adhesive surfaces (α) and (β), the adhesive surface (α) or (β) exists at a position surrounded by the insulating layer (X2). In addition, when another layer such as a release material is laminated on the adhesive surfaces (α) and (β) as shown in FIGS. 5 to 8(a) and the adhesive surface (α) cannot be directly observed, the observation is made in a plan view after removing the other layer laminated on the adhesive surfaces (α) and (β).

[0031] FIGS. 5 to 7 are a schematic cross-sectional view when each adhesive sheet is cut in the thickness direction z, and a schematic plan view when the layer (X) exposed when the release material 21 of each adhesive sheet is removed, showing an example of the configuration of the substrate-free adhesive sheet according to one aspect of the present invention. The substrate-free adhesive sheet according to one aspect of the present invention may have a configuration in which release materials 21 and 22 are laminated on the adhesive surface (α) side and the adhesive surface (β) side of the layer (X), respectively, as in the adhesive sheet shown in FIGS. 5 to 7. The release materials 21 and 22 can protect the adhesive surfaces (α) and (β) of the electrically releasable adhesive layer (X1) and the surface of the insulating layer (X2).

[0032] For example, FIG. 5(b) is a schematic plan view when the release material 21 of the adhesive sheet 1B in (a) is removed and the adhesive surface (α) side of the exposed layer (X) is viewed in a plan view. As shown in FIG. 5(b), when the layer (X) is viewed in a plan view from the adhesive surface (α) side, the adhesive surface (α) is located at a position surrounded by the insulating layer (X2). Since the insulating layer (X2) is provided at such a position, it is possible to obtain an adhesive sheet that can effectively suppress the occurrence of a short circuit when a voltage is applied. That is, after the first conductive adherend and the second conductive adherend are respectively attached to the adhesive surfaces (α) and (β) of the layer (X) of the substrate-free adhesive sheet according to one aspect of the present invention, when either one of the first conductive adherend and the second conductive adherend is peeled off from the adhesive surface, electrodes are electrically connected to the first conductive adherend and the second conductive adherend, respectively, and when a voltage is applied, for example, even if the electrode connected to the first conductive adherend comes off due to some factor, the adhesive surface (α) is located at a position surrounded by the insulating layer (X2), so that it is possible to prevent the electrode from contacting the second conductive adherend and effectively suppress the occurrence of a short circuit.

[0033] In this specification, the statement that "the adhesive surface (α) or (β) is present at a position surrounded by the insulating layer (X2)" means that, as shown in FIGS. 5(b) and 7(b), when the layer (X) is viewed in plan from the side of the adhesive surface (α) or (β), at least one of the outer peripheral end of the adhesive surface (α) or (β) and the inner peripheral end of the insulating layer (X2) is positioned such that it forms the boundary between the adhesive surface (α) or (β) and the insulating layer (X2). As another aspect, as shown in FIG. 6(b), when the layer (X) is viewed in plan from the side of the adhesive surface (α) or (β), the inner peripheral end (x21) of the insulating layer (X2) is positioned so as to be substantially parallel to at least a part of the outer peripheral end (x11) of the adhesive surface (α) or (β) of the electrically peelable adhesive layer (X1) with a void (X3) therebetween. In this specification, "substantially parallel" means that the angle formed by the straight line of the outer peripheral end (x11) of the adhesive surface (α) or (β) when viewed in plan and the straight line of the inner peripheral end (x21) of the insulating layer (X2) facing the outer peripheral end (x11) is not only 0 degrees, but also includes cases where the angle has a slight inclination such that it can be regarded as substantially parallel (for example, when the angle is 5 degrees or less, preferably 2 degrees or less). Also, the void (X3) is included as one of the components of the layer (X).

[0034] In the aspect such as the adhesive sheet 2B shown in FIG. 6, the preferred range of the average value of the interval d of the voids (X3) is the same as the above-mentioned range defined for the adhesive sheet with a substrate such as the adhesive sheet 2A shown in FIG. 2 above.

[0035] Also, in the adhesive sheet without a substrate according to one aspect of the present invention, the thickness of the electrically peelable adhesive layer (X1) and the thickness of the insulating layer (X2) may be substantially the same as in the adhesive sheets 1B and 2B shown in FIGS. 5 and 6, or may be adjusted to be different from each other as in the adhesive sheet 3B shown in FIG. 7. Note that "the thickness of the electrically peelable adhesive layer (X1) and the thickness of the insulating layer (X2) are substantially the same" is the same as the explanation for the adhesive sheet with a substrate above. Further, regarding the range of the ratio [(X1) / (X2)] between the thickness of the electrically peelable pressure-sensitive adhesive layer (X1) and the thickness of the insulating layer (X2) in the pressure-sensitive adhesive sheet without a base material according to one aspect of the present invention, it is the same as the defined range of the above-described pressure-sensitive adhesive sheet with a base material.

[0036] In one aspect of the present invention, as in the pressure-sensitive adhesive sheets 1B, 2B, and 3B shown in FIGS. 5 to 7, the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) may be configured to be adjacent in the plane direction (the x-y plane in FIGS. 5(b), 6(b), and 7(b)). Note that the "configuration in which the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) are adjacent in the plane direction" is not limited to the configuration of the pressure-sensitive adhesive sheet 1B in FIG. 5, and includes a configuration in which at least a part of the boundary between the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) is adjacent via a void portion (X3), as in the pressure-sensitive adhesive sheet 2B in FIG. 6. Further, as in the pressure-sensitive adhesive sheet 3B in FIG. 7, a configuration in which the thicknesses of the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) are different but they are adjacent in the plane direction is also included.

[0037] Further, the pressure-sensitive adhesive sheet without a base material according to one aspect of the present invention may be configured such that the insulating layer (X2) is laminated on one side and a part of both sides of the electrically peelable pressure-sensitive adhesive layer (X1). Specifically, the pressure-sensitive adhesive sheet without a base material according to one aspect of the present invention has a configuration in which the electrically peelable pressure-sensitive adhesive layer (X1) is sandwiched between two release materials 21 and 22, as in the pressure-sensitive adhesive sheet 4B shown in FIG. 8. The two release materials 21 and 22 are each formed with cuts 21a and 22a in the thickness direction so that a part of the release materials 21 and 22 can be removed. By removing a part of the release materials 21 and 22 along the cuts 21a and 22a, the adhesive surfaces (α) and (β) of the electrically peelable pressure-sensitive adhesive layer (X1) can be exposed. The pressure-sensitive adhesive sheet may have such a configuration. In the pressure-sensitive adhesive sheet 4B shown in FIG. 8, the release materials 21 and 22 serve as the insulating layer (X2). That is, in the pressure-sensitive adhesive sheet 4B, the layer (X) is composed of the electrically peelable pressure-sensitive adhesive layer (X1) and the release materials 21 and 22 which are the insulating layer (X2).

[0038] As shown in FIG. 8(a), cuts 21a and 22a are formed in the release materials 21 and 22 of the adhesive sheet 4B in the thickness direction, respectively. The cuts 21a and 22a may be in any form as long as a part of the release materials 21 and 22 can be easily removed by hand, for example, they may be perforations or the like. Note that the cuts 21a and 22a can be formed by punching the release material base materials of the release materials 21 and 22.

[0039] FIG. 8(b) is a schematic cross-sectional view of the adhesive sheet 4B when a part of the release materials 21 and 22 is removed along the cuts 21a and 22a to expose the adhesive surfaces (α) and (β) of the electrically releasable adhesive layer (X1), and FIG. 8(c) is a schematic plan view when viewed from the adhesive surface (α) side in a plan view at that time. In the schematic plan view of the adhesive sheet 4B in FIG. 8(c), the cuts 21a and 22a become the inner peripheral end portions (x21) of the remaining release material 21 and form the boundary between the adhesive surface (α) of the electrically releasable adhesive layer (X1) and the insulating layer (X2) which is the release material 21. Note that in FIG. 8(b), the adhesive surfaces (α) and (β) of the electrically releasable adhesive layer (X1) exist in the same shape and at the same position so as to face each other in the thickness direction, but the adhesive surfaces (α) and (β) may have different shapes from each other, and may also exist at different positions from each other.

[0040] 〔Regarding each component of the adhesive sheet according to an aspect of the present invention〕 Hereinafter, a conductive base material (Y), an electrically releasable adhesive layer (X1), an insulating layer (X2), a release material, and a conductive adherend to be adhered, which constitute an adhesive sheet according to an aspect of the present invention (including both the adhesive sheet with a base material in FIGS. 1 to 4 and the adhesive sheet without a base material in FIGS. 5 to 8), will be described.

[0041] <Conductive base material (Y)> The conductive base material (Y) included in the adhesive sheet according to an aspect of the present invention may be any base material that is determined to have conductivity by the above-described test method.

[0042] The thickness of the conductive substrate (Y) used in one aspect of the present invention is appropriately set according to the application, and may be 1.0 μm or more, 5.0 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, or 45 μm or more, and may also be 1000 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, or 90 μm or less.

[0043] As the conductive substrate (Y) used in one aspect of the present invention, any substrate containing a material determined to be conductive by the above-mentioned "test method for determining conductivity or insulation" may be used. For example, a metal substrate containing various metals, a conductive polymer substrate containing a conductive polymer, a metal vapor deposition substrate formed by forming a metal vapor deposition film on a resin film such as polyethylene terephthalate, and the like can be mentioned. The conductive substrate (Y) used in one aspect of the present invention may be a substrate composed of a single layer, or may be a substrate composed of a multilayer formed by laminating two or more layers.

[0044] Examples of the metal constituting the metal substrate and the metal constituting the metal vapor deposition film of the metal vapor deposition substrate include single metals such as aluminum, copper, tungsten, iron, molybdenum, nickel, titanium, silver, and gold; steels such as stainless steel and carbon steel, alloys such as brass, phosphor bronze, zirconium copper alloy, beryllium copper, iron nickel, nichrome, nickel titanium, kanthal, hastelloy, and rhenium tungsten; metal substrates such as tin-doped indium oxide, metals such as aluminum, tin-doped indium oxide, copper, iron, silver, platinum, and gold, and alloys of these metals.

[0045] <Electrically peelable adhesive layer (X1)> The electrically peelable adhesive layer (X1) of the adhesive sheet of one aspect of the present invention may be an adhesive layer determined to have electrical peelability by the above-mentioned test method. In one aspect of the present invention, the adhesion reduction rate calculated from the above formula (f1) of the electrically peelable pressure-sensitive adhesive layer (X1) is 50% or more, preferably 55% or more, more preferably 60% or more, more preferably 65% or more, still more preferably 70% or more, still more preferably 75% or more, even more preferably 80% or more, and particularly preferably 85% or more.

[0046] The thickness of the electrically peelable pressure-sensitive adhesive layer (X1) is appropriately set according to the use and the like, and may be 0.5 μm or more, 1.0 μm or more, 3.0 μm or more, 5.0 μm or more, 7.0 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, or 50 μm or more, and may also be 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less.

[0047] In the pressure-sensitive adhesive sheet of one aspect of the present invention, the ratio [(X1) / (Y)] of the thickness of the electrically peelable pressure-sensitive adhesive layer (X1) to the thickness of the conductive substrate (Y) may be 1 / 99 or more, 5 / 95 or more, 10 / 90 or more, 15 / 85 or more, 20 / 80 or more, 25 / 75 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, or 45 / 55 or more, and may also be 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, 60 / 40 or less, or 55 / 45 or less.

[0048] The adhesion of the adhesive surface (α) or (β) of the electrically peelable pressure-sensitive adhesive layer (X1) to the conductive adherend is preferably 1.0 N / 25 mm or more, more preferably 2.0 N / 25 mm or more, still more preferably 3.0 N / 25 mm or more, even more preferably 5.0 N / 25 mm or more, and particularly preferably 7.0 N / 25 mm or more. In this specification, the adhesion of the pressure-sensitive adhesive layer means a value measured under the conditions of a temperature of 23°C, a relative humidity (RH) of 50%, using a tensile tester (for example, manufactured by Orientec Co., Ltd., product name "Tensilon") at a peeling speed of 300 mm / min and a peeling angle of 180°.

[0049] As a forming material for the electrically peelable pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet according to one aspect of the present invention, there is no particular limitation as long as it can form a pressure-sensitive adhesive layer having electrical peelability by the above-described test method, but the following electrically peelable pressure-sensitive adhesive composition (x) (hereinafter, also referred to as "pressure-sensitive adhesive composition (x)") is preferable.

[0050] (Electrically peelable pressure-sensitive adhesive composition (x)) The pressure-sensitive adhesive composition (x) can be adjusted by blending an ionic compound (B) (hereinafter, also referred to as "component (B)") described later with a pressure-sensitive adhesive resin. Examples of the pressure-sensitive adhesive resin include acrylic polymers, urethane polymers, rubber polymers, polyester polymers, olefin polymers, silicone polymers, and curable polymers having polymerizable functional groups in these polymers. These pressure-sensitive adhesive resins may be used alone or in combination of two or more. The pressure-sensitive adhesive resin may be an emulsion-type polymer or a non-emulsion-type polymer.

[0051] From the viewpoint of making the adhesive strength of the formed pressure-sensitive adhesive layer good, the mass average molecular weight (Mw) of the pressure-sensitive adhesive resin used in one aspect of the present invention is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,800,000, still more preferably 30,000 to 1,500,000, even more preferably 40,000 to 1,200,000, and particularly preferably 50,000 to 1,000,000.

[0052] Among these pressure-sensitive adhesive resins, it is preferable to contain an acrylic polymer. That is, the pressure-sensitive adhesive composition (x) used in one aspect of the present invention is preferably a composition obtained by blending an acrylic polymer (A) (hereinafter, also referred to as "component (A)") as a pressure-sensitive adhesive resin together with the ionic compound (B). In the present specification, for example, the phrase "a composition comprising component (A) and component (B)" means that components (A) and (B) are used as raw materials of the composition. Therefore, for example, when component (B) is an alkali metal salt, the mode in which the alkali metal salt is ionized into cations and anions in the pressure-sensitive adhesive composition is also included.

[0053] In the pressure-sensitive adhesive composition (x) used in one aspect of the present invention, from the viewpoint of obtaining a pressure-sensitive adhesive composition that has high adhesiveness before voltage application and can easily reduce its adhesiveness by voltage application, the total blending amount of component (A) and component (B) is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass with respect to the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition (x).

[0054] The pressure-sensitive adhesive composition (x) used in one aspect of the present invention preferably contains or comprises at least one selected from a tackifier (C), a crosslinking agent (D), and a compound (E) having a polyoxyalkylene chain. Also, the pressure-sensitive adhesive composition (x) used in one aspect of the present invention may contain various additives, and may be further diluted with water or an organic solvent to be in the form of a solution.

[0055] (A) Component: Acrylic polymer The acrylic polymer (A) used in one aspect of the present invention may be a pressure-sensitive adhesive resin having a structural unit (a1) derived from an alkyl (meth) acrylate (hereinafter also referred to as "monomer (a1')"), but from the viewpoint of obtaining a pressure-sensitive adhesive composition that has high adhesiveness before voltage application and can easily reduce its adhesiveness by voltage application, it is preferably a copolymer having a structural unit (a2) derived from a functional group-containing monomer (hereinafter also referred to as "monomer (a2')") together with the structural unit (a1).

[0056] When the acrylic polymer (A) is a copolymer, the form of copolymerization is not particularly limited, and it may be any of a random copolymer, a block copolymer, and a graft copolymer. The acrylic polymer (A) used in one aspect of the present invention may be used alone or in combination of two or more.

[0057] From the viewpoint of obtaining a pressure-sensitive adhesive composition having high tackiness before voltage application, the mass average molecular weight (Mw) of the acrylic polymer (A) is preferably 50,000 to 2,000,000, more preferably 100,000 to 1,500,000, still more preferably 200,000 to 1,200,000, even more preferably 300,000 to 1,000,000, and particularly preferably 400,000 to 900,000.

[0058] The acrylic polymer (A) used in one aspect of the present invention may be a copolymer having a structural unit (a3) derived from a monomer other than the monomers (a1') and (a2') (hereinafter also referred to as "monomer (a3')").

[0059] In the acrylic polymer (A) used in one aspect of the present invention, the content ratio of the structural units (a1) and (a2) may be 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more, and may also be 100% by mass or less, 99% by mass or less, 95% by mass or less, 90% by mass or less, or 85% by mass or less, based on the total amount (100% by mass) of the structural units of the acrylic polymer (A).

[0060] [Monomer (a1'), Structural unit (a1)] The number of carbon atoms of the alkyl group of the monomer (a1') is preferably 1 to 30, more preferably 1 to 20, still more preferably 1 to 16, even more preferably 1 to 12, and particularly preferably 4 to 8. The alkyl group of the monomer (a1') may be a linear alkyl group or a branched alkyl group.

[0061] Specific monomers (a1') include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate (n-propyl (meth)acrylate, i-propyl (meth)acrylate), butyl (meth)acrylate (n-butyl (meth)acrylate, i-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate), pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, and the like. These monomers (a1') may be used alone or in combination of two or more. Among these, as the monomer (a1'), at least one selected from butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable, butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is more preferable, and butyl (meth)acrylate is even more preferable.

[0062] In the acrylic polymer (A) used in one aspect of the present invention, the content ratio of the constitutional unit (a1) is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 70% by mass or more, and preferably 99.99% by mass or less, more preferably 99.90% by mass or less, still more preferably 99.0% by mass or less, even more preferably 97.0% by mass or less, particularly preferably 95.0% by mass or less, from the viewpoint of making the adhesiveness before voltage application better, securing the content ratio of the above-described constitutional unit (a2), and obtaining an adhesive composition with improved cohesive force. Further, it may be 90.0% by mass or less, or 85% by mass or less.

[0063] [Monomer (a2’), structural unit (a2)] Examples of the monomer (a2’) include hydroxy group-containing monomers, carboxy group-containing monomers, epoxy group-containing monomers, and the like. These monomers (a2’) may be used alone or in combination of two or more.

[0064] Examples of the hydroxy group-containing monomers include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol. The number of carbon atoms of the alkyl group in the hydroxyalkyl (meth) acrylates is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and even more preferably 2 to 4. The alkyl group may be a linear alkyl group or a branched alkyl group.

[0065] Examples of the carboxy group-containing monomers include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid; 2-carboxyethyl (meth) acrylate, and the like.

[0066] Examples of the epoxy group-containing monomers include epoxy group-containing (meth) acrylic acid esters such as glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, (3,4-epoxycyclohexyl) methyl (meth) acrylate, 3-epoxycyclo-2-hydroxypropyl (meth) acrylate; glycidyl crotonate, allyl glycidyl ether, and the like.

[0067] Among these, the acrylic polymer (A) used in one aspect of the present invention is preferably a copolymer having a structural unit (a2-1) derived from a hydroxy group-containing monomer as the structural unit (a2). As the hydroxy group-containing monomer, 2-hydroxyethyl (meth)acrylate is preferable.

[0068] From the above viewpoints, in the acrylic polymer (A) used in one aspect of the present invention, the content ratio of the structural unit (a2-1) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, further preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, particularly preferably 95 to 100% by mass, based on the total amount (100% by mass) of the structural units (a2) that the acrylic polymer (A) has.

[0069] In the acrylic polymer (A) used in one aspect of the present invention, the content ratio of the structural unit (a2) is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, still more preferably 1.0% by mass or more, even more preferably 3.0% by mass or more, particularly preferably 5.0% by mass or more, from the viewpoint of making the adhesive composition have better adhesiveness before voltage application while improving the cohesive force and ensuring the content of the structural unit (a1). Further, it may be 10.0% by mass or more, or 15% by mass or more. Also, it is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less, even more preferably 30% by mass or less, particularly preferably 20% by mass or less, based on the total amount (100% by mass) of the structural units of the acrylic polymer (A).

[0070] [Monomer (a3’), Structural unit (a3)] As the monomer (a3') other than the monomers (a1') and (a2'), there is no particular limitation. For example, olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene, and chloroprene; styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, (meth)acrylamide, (meth)acrylonitrile, (meth)acryloylmorpholine, N-vinylpyrrolidone, etc. may be mentioned. These monomers (a3') may be used alone or in combination of two or more.

[0071] In the acrylic polymer (A) used in one embodiment of the present invention, as the content ratio of the structural unit (a3), it may be 0% by mass or more, 1% by mass or more, or 5% by mass or more, and also 45% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less with respect to the total amount (100% by mass) of the structural units of the acrylic polymer (A).

[0072] In the pressure-sensitive adhesive composition (x) used in one embodiment of the present invention, from the viewpoint of obtaining a pressure-sensitive adhesive composition that has high adhesiveness before voltage application and can easily reduce the adhesiveness by voltage application, the blending amount (content) of the component (A) is preferably 25 to 97% by mass, more preferably 30 to 95% by mass, still more preferably 40 to 93% by mass, even more preferably 50 to 90% by mass, and particularly preferably 60 to 87% by mass with respect to the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition (x).

[0073] Component (B): Ionic compound Examples of the ionic compound (B) used in one embodiment of the present invention include one or more selected from alkali metal salts (B1), organic quaternary ammonium salts (B2), and ionic liquids (B3).

[0074] Among these, the component (B) used in one embodiment of the present invention preferably contains one or more selected from the alkali metal salts (B1) and the ionic liquids (B3). Also, as the main component, it is preferable to use an alkali metal salt (B1) or an ionic liquid (B3) for the component (B) used in one embodiment of the present invention. In the present specification, the above-mentioned "main component" means the component having the largest content among the components constituting the component (B).

[0075] When the main component of the component (B) is the alkali metal salt (B1), the content of the component (B) other than the alkali metal salt (B1) is less than 100 parts by mass, 0 to 90 parts by mass, 0 to 50 parts by mass, 0 to 30 parts by mass, 0 to 20 parts by mass, 0 to 10 parts by mass, 0 to 5 parts by mass, 0 to 1 part by mass, 0 to 0.1 part by mass, 0 to 0.01 part by mass, 0 to 0.001 part by mass, or 0 to 0.0001 part by mass with respect to 100 parts by mass of the total amount of the alkali metal salt (B1).

[0076] When the main component of the component (B) is the ionic liquid (B3), the content of the component (B) other than the ionic liquid (B3) is less than 100 parts by mass, 0 to 90 parts by mass, 0 to 50 parts by mass, 0 to 30 parts by mass, 0 to 20 parts by mass, 0 to 10 parts by mass, 0 to 5 parts by mass, 0 to 1 part by mass, 0 to 0.1 part by mass, 0 to 0.01 part by mass, 0 to 0.001 part by mass, or 0 to 0.0001 part by mass with respect to 100 parts by mass of the total amount of the ionic liquid (B3).

[0077] In the pressure-sensitive adhesive composition (x) used in the present invention, from the viewpoint of obtaining a pressure-sensitive adhesive composition whose adhesiveness can be easily reduced by applying a voltage, the blending ratio of component (B) based on 100 parts by mass of the total amount of the pressure-sensitive adhesive resin (component (A)) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, even more preferably 13 parts by mass or more, particularly preferably more than 15 parts by mass. Further, from the viewpoint of obtaining a pressure-sensitive adhesive composition having high adhesiveness before applying a voltage, it is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, still more preferably 160 parts by mass or less, even more preferably 150 parts by mass or less, even more preferably 130 parts by mass or less, particularly preferably 120 parts by mass or less. Furthermore, it may be 100 parts by mass or less, 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, or 30 parts by mass or less.

[0078] ≪Component (B1): Alkali metal salt≫ As the alkali metal salt (B1) used in one aspect of the present invention, any compound that is solid at normal temperature (25 ° C) but ionizes into cations (alkali metal ions) and anions in a liquid may be used. Specific examples of the alkali metal salt (B1) include, for example, MCl, MBr, MI, MAlCl4, MAl2Cl7, MBF4, MPF6, MSCN, MClO4, MNO3, CH3COOM, C9H 19 COOM, CF3COOM, C3F7COOM, MCH3SO3, MCF3SO3, MC4F9SO3, MC2H5OSO3, MC6H 13 OSO3, MC8H 17OSO3, M(CF3SO2)2N, M(C2F5SO2)2N, M(C3F7SO2)2N, M(C4F9SO2)2N, M(CF3SO2)3C, MAsF6, MSbF6, MNbF6, MTaF6, M(CN)2N, M(CF3SO2)(CF3CO)N, M(CH3)2PO4, M(C2H5)2PO4, MCH3(OC2H4)2OSO3, MC6H4(CH3)SO3, M(C2F5)3PF3, CH3CH(OH)COOM, M(FSO2)2N, etc. (where M is an alkali metal atom) can be mentioned. M is preferably Li, Na, or K, more preferably Na or K, and even more preferably Na. These alkali metal salts (B1) may be used alone or in combination of two or more.

[0079] Among these, the alkali metal salt (B1) used as component (B) in one aspect of the present invention preferably contains an alkali metal salt (B11) represented by the following general formula (b-1).

Chemical formula

[0080] In the above formula (b-1), R F are each independently a fluorine atom or a fluorinated alkyl group. The number of carbon atoms of the fluorinated alkyl group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 4, even more preferably 1 to 3, and particularly preferably 1 to 2. In this specification, the "fluorinated alkyl group" means a group in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom, and it may be linear or branched. Among the fluorinated alkyl groups, a perfluoroalkyl group in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is preferred. The preferred range of the number of carbon atoms of the perfluoroalkyl group is the same as the preferred range of the number of carbon atoms of the above-mentioned fluorinated alkyl group. In one aspect of the present invention, R Fis preferably a fluorine atom or a perfluoroalkyl group, more preferably a fluorine atom, -CF3, -C2F5, -C3F7, or -C4F9, and still more preferably a fluorine atom or -CF3.

[0081] M is an alkali metal atom (lithium atom (Li), sodium atom (Na), potassium atom (K), rubidium atom (Rb), cesium atom (Cs), francium atom (Fr)), preferably Li, Na or K, more preferably Na or K, and still more preferably Na.

[0082] <<Component (B2): Organic quaternary ammonium salt>> The organic quaternary ammonium salt (B2) used in one aspect of the present invention may be a compound that is solid at room temperature (25°C) and represented by the following general formula (b-2). The organic quaternary ammonium salt (B2) may be used alone or in combination of two or more. [Chemical formula]

[0083] In the above general formula (b-2), R 11 ~R 14 are each independently an alkyl group having 1 to 4 carbon atoms. X is F, Cl, Br, I, ClO4, BF4, PF6, or [(R 15 )4N]2SO4 (R 15 are each independently an alkyl group having 1 to 4 carbon atoms).

[0084] Specific organic quaternary ammonium salts (B2) include, for example, ammonium bromide or ammonium chloride such as tetrabutyl, tetrapropyl, tetraethyl, tetramethyl, triethylbutyl, triethylpropyl, triethylmethyl, etc.; ammonium tetrafluoroborate such as tetrabutyl, tetrapropyl, tetraethyl, tetramethyl, triethylbutyl, triethylpropyl, triethylmethyl, etc.; ammonium hexafluorophosphate such as tetrabutyl, tetrapropyl, tetraethyl, tetramethyl, triethylbutyl, triethylpropyl, triethylmethyl, etc.; ammonium perchlorate such as tetrabutyl, tetrapropyl, tetraethyl, tetramethyl, triethylbutyl, triethylpropyl, triethylmethyl, etc.; ammonium sulfate such as tetrabutyl, tetrapropyl, tetraethyl, tetramethyl, triethylbutyl, triethylpropyl, triethylmethyl, etc.; and the like.

[0085] ≪Component (B3): Ionic liquid≫ The ionic liquid (B3) used in one aspect of the present invention may be a molten salt that is liquid at room temperature (25 °C), and may be a compound composed of an organic cation and an anion that is its counter ion. Examples of the organic cation constituting the ionic liquid (B3) include cations represented by any of the following general formulas (b-3-i) to (b-3-viii). Among these, the organic cation constituting the ionic liquid (B3) is preferably a cation represented by the following general formula (b-3-ii).

Chemical formula

[0086] In the above formulas (b-3-i) to (b-3-iv), R a is each independently an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 1 to 20 carbon atoms. Also, in the above formulas (b-3-v) to (b-3-viii), R b is each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, -(C2H4O) n-R c represents a group (where n is an integer from 1 to 20, and R c is an alkyl group having 1 to 20 carbon atoms), or an amino group.

[0087] R a 、R b and R c As the alkyl group that can be selected, for example, there are a methyl group, an ethyl group, a propyl group (n-propyl group, i-propyl group), a butyl group (n-butyl group, i-butyl group, s-butyl group, t-butyl group), a pentyl group (n-pentyl group, i-pentyl group, neopentyl group), a hexyl group, a heptyl group, an octyl group, 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, etc. The alkyl group may be a linear alkyl group or a branched alkyl group.

[0088] R a and R b As the alkenyl group that can be selected, for example, there are an ethenyl group (vinyl group), a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, an octadecenyl group, etc. The alkenyl group may be a linear alkyl group or a branched alkyl group.

[0089] In addition, at least one hydrogen atom bonded to the carbon atom of the cation represented by any of the general formulas (b-3-i) to (b-3-ii) may be substituted with an alkyl group having 1 to 20 carbon atoms. Specific examples of such an alkyl group are as described above.

[0090] Examples of the cation represented by the general formula (b-3-i) and the cation in which at least one hydrogen atom of the cation is substituted with the alkyl group include cations represented by any of the following formulas (b-3-i-1) to (b-3-i-11). [Chemical formula]

[0091] Examples of the cation represented by the general formula (b-3-ii) and the cation in which at least one hydrogen atom of the cation is substituted with the alkyl group include cations represented by any of the following formulas (b-3-ii-1) to (b-3-ii-26). Among them, cations represented by any of the following formulas (b-3-ii-1) to (b-3-ii-15) are preferable, cations represented by any of the following formulas (b-3-ii-1) to (b-3-ii-3) and (b-3-ii-9) to (b-3-ii-10) are more preferable, cations represented by any of the following formulas (b-3-ii-1) to (b-3-ii-3) are still more preferable, and the cation represented by the following formula (b-3-ii-2) is even more preferable. [Chemical formula]

[0092] Examples of the cation represented by the general formula (b-3-iii) include cations represented by any of the following formulas (b-3-iii-1) to (b-3-iii-6). [Chemical formula]

[0093] Examples of the cation represented by the general formula (b-3-iv) include cations represented by any of the following formulas (b-3-iv-1) to (b-3-iv-6). [Chemical formula]

[0094] Examples of the cation represented by any of the general formulas (b-3-v) to (b-3-viii) include cations represented by any of the following formulas.

Chemical formula

[0095] Examples of the anion constituting the ionic liquid (B3) include Cl - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , SCN - , ClO4 - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , C4F9SO3 - , (CF3SO2)2N - , (C2F5SO2)2N - , (C3F7SO2)2N - , (C4F9SO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , (CN)2N - , C4F9SO3 - , (C2F5SO2)2N - , C3F7COO - , (CF3SO2)(CF3CO)N - , C9H 19 COO - , (CH3)2PO4 - , (C2H5)2PO4 - , CH3OSO3 - , C2H5OSO3 - , C4H9OSO3 - , C6H 13 OSO3 - , C8H 17 OSO3- , CH3(OC2H4)2OSO3 - , C6H4(CH3)SO3 - , (C2F5)3PF3 - , CH3CH(OH)COO - , (FSO2)2N - , B(CN)4 - , C(CN)3 - , N(CN)2 - , Examples include p-toluenesulfonate anion, 2-(2-methoxyethyl)ethyl sulfate anion, etc. Among these, as the anion constituting the ionic liquid (B3) used in one aspect of the present invention, (CF3SO2)2N - or (FSO2)2N - is preferred.

[0096] Component (C): Tackifier The pressure-sensitive adhesive composition (x) used in one aspect of the present invention is preferably a composition further blended with a tackifier (C). By blending the tackifier (C), a pressure-sensitive adhesive composition having high tack before voltage application can be obtained. Note that the tackifier (C) may be used alone or in combination of two or more.

[0097] Examples of the tackifier (C) used in one aspect of the present invention include rosin-based resins such as rosin-containing diols; hydrogenated rosin-based resins obtained by hydrogenating rosin-based resins; terpene-based resins such as terpene resins, terpene phenol resins, and aromatic-modified terpene resins; hydrogenated terpene-based resins obtained by hydrogenating these terpene-based resins; C5-based petroleum resins obtained by copolymerizing C5 fractions such as pentene, isoprene, piperine, and 1,3-pentadiene generated by thermal decomposition of petroleum naphtha, and hydrogenated petroleum resins of this C5-based petroleum resin; C9-based petroleum resins obtained by copolymerizing C9 fractions such as indene, vinyltoluene, α-methylstyrene, and β-methylstyrene generated by thermal decomposition of petroleum naphtha, and hydrogenated petroleum resins of this C9-based petroleum resin; and the like.

[0098] Among these, from the viewpoint of obtaining an adhesive composition which has high adhesiveness before voltage application and can easily reduce the adhesiveness by voltage application, the tackifier (C) used in one embodiment of the present invention preferably contains a rosin-containing diol (C1). The content ratio of the rosin-containing diol (C1) is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, particularly preferably 95 to 100% by mass, relative to the total amount (100% by mass) of the component (C) contained in the adhesive composition (x).

[0099] The rosin-containing diol (C1) used in one embodiment of the present invention may be any diol having a skeleton derived from rosin, and examples thereof include a reaction product of rosin and an epoxy compound. The rosin constituting the rosin-containing diol (C1) means a residual resin obtained by using resin oil obtained from plants of the Pinaceae family as a raw material and distilling off volatile substances such as essential oils. The residual resin is usually a mixture containing resin acids mainly composed of abietic acid and its analogs and a small amount of neutral components. Examples of the resin acids include abietic acid, dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, diabietic acid, neoabietic acid, levopimaric acid, hydrogenated rosins obtained by hydrogenating these, disproportionated rosins obtained by disproportionating these, and the like. Examples of the epoxy compound constituting the rosin-containing diol (C1) include acyclic aliphatic diglycidyl ethers such as ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether; aromatic diglycidyl ethers or cycloaliphatic diglycidyl ethers such as 2,2-bis(4-hydroxyphenyl)propane diglycidyl ether, bis(4-hydroxyphenyl)methane diglycidyl ether, 1,1-bis(4-hydroxyphenyl)ethane diglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl diglycidyl ether, 2,2'-bis(4-(β-hydroxypropoxy)phenyl)propane diglycidyl ether; cycloaliphatic cyclic oxiranes such as 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclohexanecarboxylate, vinylcyclohexene dioxide; and the like.

[0100] Among these, the rosin-containing diol (C1) used in one embodiment of the present invention is preferably a compound having two rosin-derived skeletons and two hydroxyl groups in the molecule. The softening point of the rosin-containing diol (C1) used in one aspect of the present invention is preferably 60 °C or higher, more preferably 65 °C or higher, still more preferably 70 °C or higher, even more preferably 75 °C or higher, particularly preferably 80 °C or higher, and preferably 160 °C or lower, more preferably 150 °C or lower, still more preferably 140 °C or lower, even more preferably 130 °C or lower, still more preferably 120 °C or lower, even more preferably 110 °C or lower, particularly preferably 104 °C or lower, from the viewpoint of obtaining an adhesive composition having good compatibility with components (A) and (B), having high adhesiveness before voltage application, and being able to easily reduce the adhesiveness by voltage application. In the present specification, the softening point means a value measured in accordance with the ring and ball method defined in JIS K5902.

[0101] The acid value of the rosin-containing diol (C1) used in one aspect of the present invention is preferably 0 to 10.0 mgKOH / g, more preferably 0 to 4.9 mgKOH / g, still more preferably 0 to 1.9 mgKOH / g, even more preferably 0 to 1.4 mgKOH / g, particularly preferably 0 to 1.1 mgKOH / g, from the viewpoint of obtaining an adhesive composition having good compatibility with components (A) and (B), having high adhesiveness before voltage application, and being able to easily reduce the adhesiveness by voltage application. The hydroxyl value of the rosin-containing diol (C1) used in one aspect of the present invention is preferably 30 mgKOH / g or higher, more preferably 50 mgKOH / g or higher, still more preferably 70 mgKOH / g or higher, even more preferably 80 mgKOH / g or higher, particularly preferably 90 mgKOH / g or higher, and preferably 300 mgKOH / g or lower, more preferably 250 mgKOH / g or lower, still more preferably 200 mgKOH / g or lower, even more preferably 180 mgKOH / g or lower, particularly preferably 150 mgKOH / g or lower, from the viewpoint of obtaining an adhesive composition having good compatibility with components (A) and (B), having high adhesiveness before voltage application, and being able to easily reduce the adhesiveness by voltage application. In the present specification, the acid value and the hydroxyl value mean values measured in accordance with the potentiometric titration method defined in JIS K0070.

[0102] In the pressure-sensitive adhesive composition (x) used in one aspect of the present invention, from the viewpoint of obtaining a pressure-sensitive adhesive composition that has high adhesiveness before voltage application and can easily reduce its adhesiveness by voltage application, the blending ratio of component (C) with respect to 100 parts by mass of the total amount of component (A) contained in the pressure-sensitive adhesive composition (x) is preferably 2.0 parts by mass or more, more preferably 5.0 parts by mass or more, still more preferably 8.0 parts by mass or more, further preferably 12.0 parts by mass or more, even more preferably 18.0 parts by mass or more, particularly preferably 22.0 parts by mass or more. Furthermore, it may be 25.0 parts by mass or more, or 30.0 parts by mass or more. Also, it is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 150 parts by mass or less, further preferably 130 parts by mass or less, even more preferably 120 parts by mass or less, particularly preferably 110 parts by mass or less. Furthermore, it may be 100 parts by mass or less, 90 parts by mass or less, 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less.

[0103] Component (D): Crosslinking agent The pressure-sensitive adhesive composition (x) used in one aspect of the present invention is preferably a composition further blended with a crosslinking agent (D). By blending the crosslinking agent (D), it becomes easier to prepare a pressure-sensitive adhesive composition that has high adhesiveness before voltage application and can easily reduce its adhesiveness by voltage application. Note that the crosslinking agent (D) may be used alone or in combination of two or more. Examples of the crosslinking agent (D) used in one aspect of the present invention include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, imine-based crosslinking agents, metal chelate-based crosslinking agents, and the like.

[0104] In the pressure-sensitive adhesive composition (x) used in one aspect of the present invention, from the viewpoint of facilitating preparation with a pressure-sensitive adhesive composition that has high adhesiveness before voltage application and can easily reduce adhesiveness by voltage application, the blending amount of component (D) is preferably 0.001 to 10.0 parts by mass, more preferably 0.005 to 7.0 parts by mass, still more preferably 0.010 to 5.0 parts by mass, even more preferably 0.015 to 2.0 parts by mass, particularly preferably 0.020 to 1.0 part by mass, based on 100 parts by mass of the total amount of the pressure-sensitive adhesive resin (component (A)).

[0105] Component (E): Compound having a polyoxyalkylene chain The pressure-sensitive adhesive composition (x) used in one aspect of the present invention is preferably a composition further blended with a compound (E) having a polyoxyalkylene chain. By blending the compound (E), it becomes easier to prepare with a pressure-sensitive adhesive composition that can easily reduce adhesiveness by voltage application. Note that the compound (E) may be used alone or in combination of two or more.

[0106] As the compound (E) used in one aspect of the present invention, a compound represented by the following general formula (e-1) is preferable.

Chemical formula

[0107] In the above general formula (e-1), R 1 is an alkylene group having 1 to 8 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, still more preferably 2 or 3 carbon atoms). R 2 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 3 carbon atoms), or a hydroxy group. R 3 is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 3 carbon atoms). n is an integer of 1 or more.

[0108] R 1Examples of the alkylene group that can be selected as the alkylene group include a methylene group (-CH2-), an ethylene group (-CH2CH2-), an ethylidene group (-CH(CH3)-), a trimethylene group (-CH2CH2CH2-), a propylene group (-CH(CH3)CH2-), a propylidene group (-CHCH2(CH3)-), an isopropylidene group (-C(CH3)2-), a tetramethylene group (-CH2CH2CH2CH2-), a 1-methyltrimethylene group (-CH(CH3)CH2CH2-), a 2-methyltrimethylene group (-CH2CH(CH3)CH2-), a butylene group (-C(CH3)2CH2-), and -(CH2) m - (where m is an integer from 1 to 8) and the like. Among these, R 1 is preferably an ethylene group or a propylene group, and more preferably an ethylene group.

[0109] R 2 and R 3 Examples of the alkyl group that can be selected as the alkyl group include a methyl group, an ethyl group, a propyl group (n-propyl group, i-propyl group), a butyl group (n-butyl group, i-butyl group, s-butyl group, t-butyl group), a pentyl group (n-pentyl group, i-pentyl group, neopentyl group), a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, and the like.

[0110] Compound (E) used in one aspect of the present invention is preferably a polyalkylene glycol in which R 2 in the general formula (e-1) is a hydroxy group and R 3 is a hydrogen atom, more preferably polyethylene glycol or polypropylene glycol, and even more preferably polyethylene glycol.

[0111] The number average molecular weight (Mn) of compound (E) used in one aspect of the present invention is preferably 50 to 2,000, more preferably 90 to 1,000, even more preferably 130 to 500, and still more preferably 170 to 300.

[0112] In the pressure-sensitive adhesive composition (x) used in one aspect of the present invention, from the viewpoint of facilitating preparation with a pressure-sensitive adhesive composition that can easily reduce its adhesiveness by applying a voltage, the blending amount (content) of component (E) is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, still more preferably 1.0 part by mass or more, even more preferably 2.5 part by mass or more, particularly preferably 4.0 part by mass or more, based on 100 parts by mass of the total amount of component (A). Also, it is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, even more preferably 16 parts by mass or less, particularly preferably 12.0 parts by mass or less.

[0113] Other additives The pressure-sensitive adhesive composition (x) used in one aspect of the present invention may contain various additives contained in general pressure-sensitive adhesive compositions, in addition to components (A) to (D), as long as the effects of the present invention are not impaired. Examples of such various additives include compatibilizers, wetting agents, thickeners, defoamers, antioxidants, ultraviolet absorbers, softeners (plasticizers), fillers, rust preventives, pigments, dyes, and the like. These various additives may be used alone or in combination of two or more.

[0114] The blending amount of each of the various additives is appropriately set according to the type of the additive. However, based on 100 parts by mass of the total amount of component (A) contained in the pressure-sensitive adhesive composition (x), it is preferably 0.01 to 50 parts by mass, more preferably 0.05 to 40 parts by mass, still more preferably 0.1 to 30 parts by mass.

[0115] Also, the electrically peelable pressure-sensitive adhesive layer (X1) can be formed by applying the pressure-sensitive adhesive composition (x) onto the peeling treatment surface of a conductive substrate or a release material to form a coating film and drying the coating film. Here, from the viewpoint of improving coatability, the pressure-sensitive adhesive composition (x) may be further diluted with water or an organic solvent to be in the form of a solution. Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, and the like. These organic solvents may be the same as those used in the synthesis of the pressure-sensitive adhesive resin, or one or more organic solvents other than those used in the synthesis of component (A) may be added.

[0116] <Insulating layer (X2)> The insulating layer (X2) of the pressure-sensitive adhesive sheet according to one embodiment of the present invention may be a layer determined to be insulating by the above-mentioned "test method for determining conductivity or insulation".

[0117] The thickness of the insulating layer (X2) used in one embodiment of the present invention is appropriately set according to the use and the like, and may be 0.5 μm or more, 1.0 μm or more, 3.0 μm or more, 5.0 μm or more, 7.0 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more, and may also be 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less.

[0118] In the pressure-sensitive adhesive sheet according to one embodiment of the present invention, the ratio [(X2) / (Y)] of the thickness of the insulating layer (X2) to the thickness (Y) of the conductive substrate may be 1 / 99 or more, 5 / 95 or more, 10 / 90 or more, 15 / 85 or more, 20 / 80 or more, 25 / 75 or more, or 30 / 70 or more, and may also be 60 / 40 or less, 55 / 45 or less, 50 / 50 or less, 48 / 52 or less, 45 / 55 or less, 42 / 58 or less, or 40 / 60 or less.

[0119] Examples of the material for forming the insulating layer (X2) used in one embodiment of the present invention include materials determined to be insulating by the "test method for determining conductivity or insulation", and specifically include resins, papers, woods, glasses, ceramics, carbon fiber reinforced plastics, and the like. These forming materials may be used alone or in combination of two or more. Further, the insulating layer (X2) may be composed of a single layer or may be composed of a multi-layer formed by laminating two or more layers.

[0120] From the viewpoints of ease of forming the insulating layer (X2) and ease of adjusting the thickness, the insulating layer (X2) used in one aspect of the present invention preferably includes a resin layer containing a resin. When the insulating layer (X2) includes a resin layer, the insulating layer (X2) may be a single layer composed of a single resin layer, may be a multi-layer formed by laminating two or more resin layers, or may be a laminate formed by laminating a layer made of an insulating material other than the resin layer and one or more resin layers.

[0121] Examples of the resin contained in the resin layer constituting the insulating layer (X2) include acrylic resins, urethane resins, rubber resins, polyester resins, polycarbonate resins, olefin resins, polystyrene resins, silicone resins, and curable resins obtained by introducing polymerizable functional groups into these resins. These resins may be used alone or in combination of two or more. Further, the resin layer constituting the insulating layer (X2) may contain various additives such as compatibilizers, wetting agents, thickeners, defoaming agents, antioxidants, ultraviolet absorbers, softening agents (plasticizers), fillers, rust preventives, pigments, and dyes.

[0122] In the pressure-sensitive adhesive sheet of one aspect of the present invention, the resin layer constituting the insulating layer (X2) may be a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive resin. The pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive layer is not particularly limited as long as it is a resin having pressure-sensitive adhesiveness. Examples thereof include acrylic polymers, urethane polymers, rubber polymers, polyester polymers, olefin polymers, silicone polymers, and curable polymers having polymerizable functional groups in these polymers. These pressure-sensitive adhesive resins may be used alone or in combination of two or more. Further, the pressure-sensitive adhesive resin may be an emulsion-type polymer or a non-emulsion-type polymer. The pressure-sensitive adhesive layer may be a layer formed from the above-described pressure-sensitive adhesive composition (x), or may be a layer formed from the same pressure-sensitive adhesive composition (x) as the layer (X1). In this case, the layer (X1) is a layer including the pressure-sensitive adhesive surface (α) or (β) to be attached to the conductive adherend, and the insulating layer (X2) is a layer including a pressure-sensitive adhesive surface other than the pressure-sensitive adhesive surface (α) or (β), and is classified.

[0123] In the pressure-sensitive adhesive sheet according to one aspect of the present invention, a release material may be used as the insulating layer (X2). Generally, a release material has a release agent layer formed from a release agent containing a release agent resin on one or both surfaces of a release material base material. Since the release agent layer corresponds to a resin layer, a release material using an insulating base material as the release material base material can be used as the insulating layer (X2). Hereinafter, details of the release material will be described.

[0124] <Release material> The release material included in the pressure-sensitive adhesive sheet according to one aspect of the present invention has a release agent layer formed from a release agent containing a release agent resin on one or both surfaces of a release material base material. In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the release material may be laminated and used on the layer (X) for the purpose of protecting the surface of the layer (X), or may be used as the insulating layer (X2).

[0125] When using the release material as the insulating layer (X2), the release material base material may be any insulating base material. For example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene (meth) acrylic acid copolymer, polystyrene, polycarbonate, fluororesin, low-density polyethylene, linear low-density polyethylene, resin films such as triacetyl cellulose, high-quality paper, coated paper, paper base materials such as glassine paper, and laminated papers obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials can be mentioned. In addition, when the release material is not used as the insulating layer (X2) but is used for the purpose of protecting the surface of the layer (X), as the release material substrate, in addition to the above-described insulating substrate, a conductive substrate similar to the above-described conductive substrate (Y) can also be used.

[0126] Examples of the resin for the release material contained in the release agent for forming the release agent layer include silicone resins, olefin resins, long-chain alkyl resins, alkyd resins, fluorine resins, rubber elastomers such as isoprene resins and butadiene resins, and the like. These resins may be used alone or in combination of two or more.

[0127] When the release material is used as the insulating layer (X2), the thickness of the release material is the same as the preferred range of the thickness of the above-described insulating layer (X2). In addition, when the release material is not used as the edge layer (X2) but is used for the purpose of protecting the surface of the layer (X), the thickness of the release material is not particularly limited, but is preferably 5 to 300 μm, more preferably 10 to 200 μm. When a resin film is used as the release material substrate, it is preferably 10 to 100 μm.

[0128] <Conductive adherend> The conductive adherend to which the pressure-sensitive adhesive sheet according to one embodiment of the present invention is to be attached is not particularly limited. Examples of the conductive material constituting the conductive adherend include materials determined to be conductive by the above-described "test method for determining conductivity or insulation", and specifically include metals such as aluminum, tin-doped indium oxide, copper, iron, silver, platinum, and gold, alloys of these metals, conductive polymers, and the like. The conductive adherend used in one embodiment of the present invention may be an adherend composed of only one of these conductive materials, or may be an adherend composed of a combination of two or more.

[0129] 〔Method for peeling the electrically releasable pressure-sensitive adhesive sheet〕 Examples of the method for peeling the conductive adherend attached to the electrically releasable pressure-sensitive adhesive sheet according to one embodiment of the present invention include the peeling methods shown below. Hereinafter, a method for peeling a conductive adherend attached to an adhesive sheet with a base material such as the adhesive sheet shown in FIGS. 1 to 4 and an adhesive sheet without a base material such as the adhesive sheet shown in FIGS. 5 to 8 will be described respectively.

[0130] <Method for Peeling Adhesive Sheet with Base Material> As a method for peeling a conductive adherend attached to the adhesive surface (α) of the electrically peelable adhesive layer (X1) of an adhesive sheet with a base material such as the adhesive sheet shown in FIGS. 1 to 4, a peeling method having the following steps (1a) to (3a) can be mentioned. · Step (1a): A step of electrically connecting the conductive base material (Y) of the adhesive sheet with a base material and the electrode (I), and electrically connecting the surface of the conductive adherend and the electrode (II). · Step (2a): A step of applying a voltage between the electrodes (I) and (II). · Step (3a): A step of peeling the conductive adherend from the adhesive surface (α).

[0131] (Step (1a)) In step (1a), it is a step of electrically connecting the electrodes (I) and (II) connected from the voltage application device to the conductive base material (Y) and the conductive adherend. Which of the electrodes (I) and (II) is connected to the anode and cathode of the voltage application device respectively is selected so that the conductive adherend can be peeled from the adhesive surface (α) in step (3a) in consideration of the characteristics of the electrically peelable adhesive layer (X1).

[0132] (Step (2a)) In step (2a), it is a step of applying a voltage between the electrodes (I) and (II). The magnitude of the applied voltage can be performed by the voltage application device to which the electrodes (I) and (II) are connected. The voltage (applied voltage) applied in this step is preferably 1 to 200 V, more preferably 3 to 140 V, still more preferably 6 to 120 V, and the time (application time) for applying the voltage in this range is preferably 1 to 180 seconds, more preferably 5 to 120 seconds, still more preferably 10 to 90 seconds. By this process, a voltage can be applied to the electrically peelable adhesive layer (X1) located between the conductive substrate (Y) connected to the electrode (I) and the conductive adherend connected to the electrode (II), thereby reducing the adhesive force. At this time, since the adhesive sheet of one aspect of the present invention has the insulating layer (X2), even if one of the electrodes (I) and (II) comes off, it is possible to prevent the detached electrode from coming into contact with the conductive adherend or the conductive substrate (Y), so that the occurrence of a short circuit can be effectively suppressed.

[0133] (Step (3a)) Step (3a) is a step of peeling the conductive adherend from the adhesive surface (α). In step (2a), a voltage is applied to the electrically peelable adhesive layer (X1), and the adhesive force is reduced. Therefore, the conductive adherend can be peeled from the adhesive surface (α) with a slight force.

[0134] <Method for Peeling Adhesive Sheet without Substrate> As a method for peeling the first conductive adherend attached to the adhesive surface (α) of the electrically peelable adhesive layer (X1) of the adhesive sheet without a substrate, such as the adhesive sheet shown in FIGS. 5 to 8, or the second conductive adherend attached to the adhesive surface (β), a peeling method having the following steps (1b) to (3b) can be mentioned. · Step (1b): A step of electrically connecting the first conductive adherend and the electrode (I), and electrically connecting the surface of the second conductive adherend and the electrode (II). · Step (2b): A step of applying a voltage between the electrodes (I) and (II). · Step (3b): A step of peeling the first conductive adherend or the second conductive adherend from the adhesive surface (α) or the adhesive surface (β).

[0135] <Step (1b)> Step (1b) is a step of electrically connecting the electrodes (I) and (II) connected from the voltage application device to the first conductive adherend and the second conductive adherend. Whether to connect the electrodes (I) and (II) to the anode and cathode of the voltage application device, respectively, is selected in step (3a) depending on which of the first conductive adherend or the second conductive adherend can be peeled off from the adhesive surface, taking into account the characteristics of the electrically peelable adhesive layer (X1).

[0136] <Step (2b)> Step (2b) is a step of applying a voltage between the electrodes (I) and (II). The magnitude of the applied voltage can be carried out by the voltage application device to which the electrodes (I) and (II) are connected. The preferred range of the voltage (applied voltage) applied in this step is preferably 1 to 200 V, more preferably 3 to 140 V, and even more preferably 6 to 120 V. The time (application time) for applying the voltage within this range is preferably 1 to 180 seconds, more preferably 5 to 120 seconds, and even more preferably 10 to 90 seconds. By this step, a voltage is applied to the electrically peelable adhesive layer (X1) located between the first conductive adherend connected to the electrode (I) and the second conductive adherend connected to the electrode (II), and the adhesive force can be reduced. At this time, since the adhesive sheet of one aspect of the present invention has the insulating layer (X2), even if one of the electrodes (I) and (II) comes off, it is possible to prevent the detached electrode from contacting the other conductive adherend, so that the occurrence of a short circuit can be effectively suppressed.

[0137] <Step (3b)> Step (3b) is a step of peeling the first conductive adherend or the second conductive adherend from the adhesive surface (α) or the adhesive surface (β). In step (2b), a voltage is applied to the electrically peelable adhesive layer (X1) and the adhesive force is reduced. Therefore, the first conductive adherend or the second conductive adherend can be peeled off from the adhesive surface with a slight force.

Example

[0138] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples. The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by the methods described below. <Weight average molecular weight (Mw) and number average molecular weight (Mn)> Using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8220GPC"), measurements were taken under the following conditions, and the values measured in terms of standard polystyrene conversion were used. (Measurement conditions) · Column: A series of columns "TSK guard column SuperH-H", "TSK gel SuperHM-H", "TSK gel SuperHM-H", "TSK gel SuperH2000" (all manufactured by Tosoh Corporation) connected in sequence · Column temperature: 40 °C · Developing solvent: Tetrahydrofuran · Flow rate: 1.0 mL / min

[0139] Example 1 [Production of pressure-sensitive adhesive sheet] A pressure-sensitive adhesive sheet having the same configuration as the pressure-sensitive adhesive sheet 1 shown in Fig. 1(b) was produced by the following procedure. (1) Preparation of electro-releasable pressure-sensitive adhesive composition (x) The components used in the preparation of the electro-releasable pressure-sensitive adhesive composition (x) are as follows. · "Acrylic polymer": A copolymer having structural units derived from n-butyl acrylate (BA), methyl acrylate (MA), and 2-hydroxyethyl acrylate (2-HEA) (structural unit ratio: BA / MA / 2-HEA = 60 / 20 / 20 (mass ratio)), a pressure-sensitive adhesive resin, Mw = 600,000. · "Ionic liquid": Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name "AS-210", 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, an ionic liquid that is liquid at room temperature (25 °C). · "Rosin-containing diol": Manufactured by Arakawa Chemical Industries, Ltd., product name "Pink Crystal D-6011", rosin-containing diol, softening point = 84 - 99°C, acid value = 1 mgKOH / g or less, hydroxyl value = 110 - 125 mgKOH / g. · "Isocyanate crosslinking agent": Manufactured by Tosoh Corporation, product name "Coronate L", isocyanate crosslinking agent. · "PEG": Polyethylene glycol with Mn = 200, liquid at room temperature (25°C).

[0140] 100 parts by mass (active ingredient ratio) of the above acrylic polymer, 16.0 parts by mass (active ingredient ratio) of the above ionic liquid, 40.0 parts by mass (active ingredient ratio) of the above rosin-containing diol, 0.20 parts by mass (active ingredient ratio) of the above isocyanate crosslinking agent, and 9.0 parts by mass (active ingredient ratio) of the above PEG were added and diluted with ethyl acetate as a diluting solvent to prepare an electrically peelable pressure-sensitive adhesive composition (x).

[0141] (2) Preparation of electrically peelable pressure-sensitive adhesive sheet A square cut with a side length of 50 mm was made by punching in the central part of a double-release film (manufactured by Lintec Corporation, product name "SP-PET382150", thickness: 38 μm), and at least the four corners of the square were connected to the part outside the square area, and the part of the release film was processed so that it could be removed along the cut. The electrically peelable pressure-sensitive adhesive composition (x) prepared in the above (1) was applied onto the release-treated surface of a light-release film (manufactured by Lintec Corporation, product name "SP-PET381031", thickness: 38 μm) so that the thickness after drying would be 50 μm, and dried at 100°C for 2 minutes to form an electrically peelable pressure-sensitive adhesive layer on the release film, and the above-mentioned double-release film was laminated. Next, the light release film was peeled off, and the exposed surface of the formed electrically releasable adhesive layer was bonded to an aluminum foil with a thickness of 50 μm (manufactured by Nippon Metal Foil Industry Co., Ltd., product name "Aluminum Tantalum S Gloss 50 Fukoka"), which is a conductive base material. Then, it was cut into a size of 150 mm in length and 70 mm in width so that the square cut portion formed in the release film was located at the center. Along the cut formed in the double release film, a release film with a size of a square with a side length of 50 mm was removed to expose the electrically releasable adhesive layer, and an electrically releasable adhesive sheet having the same configuration as the adhesive sheet 4A in FIG. 4 was produced.

[0142] [Electrically Releasable Test] Using the electrically releasable adhesive sheet produced in (2) above, an electrically releasable test was conducted to determine whether the conductive adherend could be peeled off by applying a voltage based on the following method. A stainless steel plate with a size of a square with a side length of 60 mm, which is a conductive adherend, was attached to the adhesive surface (α) of the exposed electrically releasable adhesive layer (X1) of the produced electrically releasable adhesive sheet. Then, the aluminum foil, which is the conductive base material of the electrically releasable adhesive sheet, was electrically connected to the electrode (I), and the stainless steel plate, which is the conductive adherend, was electrically connected to the electrode (II). Next, the anode-side terminal of a voltage application device (manufactured by Takasago Seisakusho Co., Ltd., product name "DC Power Supply Device (KX-100H)") was connected to the electrode (I), and the cathode-side terminal was connected to the electrode (II) to form a circuit. Then, a voltage of 10 V was applied for 60 seconds, and after the voltage application, it was left standing for 1 minute. After standing, when the conductive adherend 50 was peeled off by hand from the adhesive surface (α) in an environment of 23°C and 50% RH (relative humidity), it was confirmed that it could be easily peeled off with a slight force. Also, after preparing another sample, while applying a voltage under the same conditions as above, the wire connecting the electrode (II) and the terminal was pulled, and the connection of the electrode (II) to the conductive adherend was removed. At this time, the electrode (II) did not come into contact with the electrically releasable adhesive layer (X1) and came into contact with the surface of the release film, which is the insulating layer (X2), and no short circuit occurred. [Explanation of Reference Signs]

[0143] 1A, 2A, 3A, 4A, 1B, 2B, 3B Adhesive Sheets Y Conductive Substrate X Layer X1 Electrically Peeling Adhesive Layer x11 Outer Peripheral End X2 Insulating Layer x21 Inner Peripheral End X3 Void Portion 21, 22 Release Materials 21a, 22a Cuts

Claims

1. It has a conductive substrate (Y) and a layer (X) laminated on at least a part of the surface of one side or both sides of the conductive substrate (Y), The layer (X) is formed from an electrically peelable pressure-sensitive adhesive composition whose adhesiveness can be reduced by applying a voltage, and has a surface (β) in contact with the conductive substrate (Y) and an adhesive surface (α) that can be attached to a conductive adherend, and includes an electrically peelable pressure-sensitive adhesive layer (X1) and an insulating layer (X2), When the layer (X) is viewed in plan from the adhesive surface (α) side, the adhesive surface (α) exists at a position surrounded by the insulating layer (X2), An electrically peelable adhesive sheet.

2. The electrically peelable adhesive sheet according to claim 1, wherein at least a part of the surface of the insulating layer (X2) is in contact with the conductive substrate (Y).

3. The electrically peelable adhesive sheet according to claim 1 or 2, wherein when the layer (X) is viewed in plan from the adhesive surface (α) side, at least one of the outer peripheral end of the adhesive surface (α) and the inner peripheral end of the insulating layer (X2) forms a boundary between the adhesive surface (α) and the insulating layer (X2).

4. The electrically peelable adhesive sheet according to any one of claims 1 to 3, wherein when the layer (X) is viewed in plan from the adhesive surface (α) side, the insulating layer (X2) is positioned so as to be substantially parallel to the outer peripheral end of at least a part of the adhesive surface (α) with a gap (X3) therebetween.

5. The electrically peelable adhesive sheet according to any one of claims 1 to 4, wherein the electrically peelable pressure-sensitive adhesive layer (X1) and the insulating layer (X2) are adjacent to each other in the plane direction.

6. The electrically peelable adhesive sheet according to any one of claims 1 to 5, wherein at least a part of the insulating layer (X2) is laminated on the electrically peelable pressure-sensitive adhesive layer (X1).

7. The electrically peelable adhesive sheet according to claim 6, wherein the insulating layer (X2) is laminated on the electrically peelable pressure-sensitive adhesive layer (X1) without contacting the conductive substrate (Y).

8. The electrically peelable adhesive sheet according to any one of claims 1 to 7, wherein the insulating layer (X2) includes a resin layer containing a resin.

9. The electrically peelable adhesive sheet according to any one of claims 1 to 8, wherein the insulating layer (X2) is a release material.

10. It has a layer (X) including an electrically peelable pressure-sensitive adhesive layer (X1) formed from an electrically peelable pressure-sensitive adhesive composition whose adhesiveness can be reduced by applying a voltage, having an adhesive surface (α) that can be attached to a first conductive adherend, and an adhesive surface (β) that can be attached to a second conductive adherend on the side opposite to the adhesive surface (α), and an insulating layer (X2), When the layer (X) is viewed in a plan view from at least one side of the adhesive surfaces (α) and (β), the adhesive surface (α) or (β) is present at a position surrounded by the insulating layer (X2). Electrically peelable adhesive sheet.

11. A method for peeling a conductive adherend attached to the adhesive surface (α) of the electrically peelable adhesive sheet according to any one of Claims 1 to 9, The peeling method having the following steps (1a) to (3a). - Step (1a): A step of electrically connecting the conductive base material (Y) of the electrically peelable adhesive sheet and the electrode (I), and electrically connecting the surface of the conductive adherend and the electrode (II). - Step (2a): A step of applying a voltage between the electrodes (I) and (II). - Step (3a): A step of peeling the conductive adherend from the adhesive surface (α).

12. A method for peeling a first conductive adherend attached to the adhesive surface (α) of the electrically peelable adhesive sheet according to Claim 10 or a second conductive adherend attached to the adhesive surface (β), The peeling method having the following steps (1b) to (3b). - Step (1b): A step of electrically connecting the first conductive adherend and the electrode (I), and electrically connecting the surface of the second conductive adherend and the electrode (II). - Step (2b): A step of applying a voltage between the electrodes (I) and (II). - Step (3b): A step of peeling the first conductive adherend or the second conductive adherend from the adhesive surface (α) or the adhesive surface (β).

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