WO2022137924A1

WO2022137924A1 - Structure, adhesive sheet, set and method

Info

Publication number: WO2022137924A1
Application number: PCT/JP2021/042522
Authority: WO
Inventors: 尚史小坂; 陽介清水; 健太熊倉
Original assignee: 日東電工株式会社
Priority date: 2020-12-25
Filing date: 2021-11-19
Publication date: 2022-06-30
Also published as: TW202239900A

Abstract

The present invention provides a structure wherein two adherends are able to be separated by means of water peeling that utilizes an aqueous liquid such as water even in cases where the surfaces of the two adherends to be bonded with each other are hydrophobic. The present invention provides a structure which sequentially comprises a first adhesive layer, an intermediate layer and a second adhesive layer in this order. With respect to this structure, at least one surface of the intermediate layer is a hydrophilic surface. In addition, at least one of the first adhesive layer and the second adhesive layer has a layer A that is arranged on the hydrophilic surface of the intermediate layer. With respect to this structure, the water peel strength decrease rate, which is calculated from the water peel strength A1 (N/10 mm) of the adhesive layer that has the layer A with respect to the intermediate layer and the peel strength A0 (N/10 mm) of the adhesive layer that has the layer A with respect to the intermediate layer by formula (1 – (A1/A0)) × 100, is 70% or more.

Description

Structures, adhesive sheets, sets and methods

The present invention relates to structures, adhesive sheets, sets and methods.
This application claims priority under Japanese Patent Application No. 2020-217630 filed on December 25, 2020, the entire contents of which are incorporated herein by reference. ..

Generally, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid state (viscous elastic body) in a temperature range near room temperature, and has a property of easily adhering to an adherend by pressure. Taking advantage of these properties, the pressure-sensitive adhesive is widely used in various fields in the form of a pressure-sensitive adhesive sheet with a support having a pressure-sensitive adhesive layer on the support or in the form of a support-less pressure-sensitive adhesive sheet having no support. It's being used. Patent Document 1 is mentioned as a technical document relating to the pressure-sensitive adhesive sheet.

Japanese Patent Application Publication No. 2020-23656

Adhesives are required to have various properties depending on the application. Some of these characteristics are difficult to achieve at a high level, for example, when trying to improve one characteristic, the other characteristic tends to decrease. As an example of such properties that are difficult to achieve at the same time, there is an adhesive force to the adherend and a peeling / removing property. For example, after fixing the adherend using the adhesive sheet, when the adhesive sheet is peeled off and removed from the adherend, the adherend is covered in order to prevent damage or deformation of the adherend, as opposed to the above-mentioned fixing. It may be required to keep the peeling force of the adhesive sheet from the adherend (that is, the adhesive force to the adherend) low. For example, when the adherend is brittle or thin, it is not easy to realize an adhesive sheet having good peeling and removing properties and high adhesive strength.

In response to the above problems, the present inventors have described in Patent Document 1 a novel method that can be easily peeled off by using an aqueous liquid such as water and has improved water resistance reliability at the time of joining. An adhesive sheet (water-removable adhesive sheet) was proposed. According to the water-removable adhesive sheet, the adhesive sheet can be removed from the adherend without damaging the adherend, which is the object to be peeled off, or with less physical load, by water-peeling using an aqueous liquid such as water. Since it can be removed, for example, recycling or repair of the adherend can be suitably realized. Here, recycling means making the adherend peeled off from the adhesive sheet into a reusable state, and here includes reuse. After the product to which the parts etc. are fixed using the adhesive sheet reaches the user's hand and the product life is over, each part is disassembled without damaging the part and without leaving the adhesive sheet. If it can be reused, it is meaningful from the viewpoint of effective use of resources and reduction of environmental load. In addition, repair means to replace, repair, or inspect the part when a defect such as a failure occurs during use of the product, and the part fixed by the adhesive sheet is peeled off and removed to remove the part. If it can be replaced, repaired, and inspected, it will lead to cost reduction for product users and reduction of environmental load, which is beneficial. The above recycling and repair may include removal or replacement of a battery or the like.

The surface of the adherend needs to have a certain degree of hydrophilicity in order to satisfactorily exhibit the water releasability of the water releasable adhesive sheet. For example, in order to separate a structure obtained by joining two adherends with a water-removable pressure-sensitive adhesive sheet by water-separation, at least one of the two adherends needs to have a hydrophilic surface. The hydrophilic surface can be obtained by using a hydrophilic material or by hydrophilizing the hydrophobic surface, but the hydrophilic treatment of the adherend is an additional step, so that it is not always an efficient method. Further, depending on the adherend, hydrophilization treatment may not be possible or desirable, and even if water exfoliation is performed on such an adherend after joining with a water-removable adhesive sheet, the intended water exfoliation is performed. In some cases, the sex does not develop and the adherend cannot be separated smoothly.

The present invention has been created in view of the above circumstances, and is an aqueous liquid such as water even when the adhered surfaces of the two adherends bonded by using the pressure-sensitive adhesive layer are hydrophobic. It is an object of the present invention to provide a structure and a method capable of separating the two adherends by water separation using the above. Another object of the present invention is to provide a set, an adhesive sheet and a structure used in the above structure or method.

According to this specification, a structure including a first pressure-sensitive adhesive layer, an intermediate layer, and a second pressure-sensitive adhesive layer is provided in this order. In this structure, at least one surface of the intermediate layer is a hydrophilic surface. Further, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer. Then, in the structure, 20 μL of distilled water is supplied between the intermediate layer and the A layer, and the distilled water is allowed to enter one end of the interface between the A layer and the intermediate layer, and then JIS. Z0237: 2009 10.4.1 Method 1: Measured according to the 180 ° peeling adhesive force to the test plate at a test temperature of 23 ° C. using a tensile tester under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees. From the water peeling force A1 [N / 10 mm] and the peeling strength A0 [N / 10 mm] of the pressure-sensitive adhesive layer having the A layer with respect to the intermediate layer, the following formula: (1- (A1 / A0)) × 100 The rate of decrease in water peeling force calculated by; is 70% or more.
According to the above configuration, even if the adhered surface of the two adherends to be joined is hydrophobic, the two adherends can be separated by water separation using an aqueous liquid such as water. can.

The techniques disclosed herein (structure, double-sided adhesive sheet, method for separating adherends, method for separating and joining adherends, adhesive sheet set, structure set, adhesive sheet used for the set, and structure are included. In some preferred embodiments of), the water contact angle of the hydrophilic surface of the intermediate layer is 30 degrees or less. With such a configuration, the water releasability is better developed on the hydrophilic surface, and the adherend can be separated more smoothly.

In some preferred embodiments of the techniques disclosed herein, the hydrophilic surface of the intermediate layer has a non-existent region of the pressure-sensitive adhesive layer at the end of the intermediate layer. By providing the pressure-sensitive adhesive layer non-existing region on the hydrophilic surface of the intermediate layer as described above, when the pressure-sensitive adhesive layer is water-peeled from the hydrophilic surface of the intermediate layer, the pressure-sensitive adhesive layer non-existing region at the end is provided. Aqueous liquid can be applied to the water to start and proceed with water separation. In short, the region where the pressure-sensitive adhesive layer does not exist on the hydrophilic surface of the intermediate layer can be a starting point for water exfoliation.

In some aspects of the technique disclosed herein, the intermediate layer has a hydrophilic layer constituting the hydrophilic surface. By providing a hydrophilic layer in the intermediate layer or using the intermediate layer itself as a hydrophilic layer, a hydrophilic surface suitable for water exfoliation can be preferably obtained. The hydrophilic layer may be a hydrophilic layer containing an inorganic material or may be a hydrophilic layer containing an organic material. In some preferred embodiments, the hydrophilic layer is an inorganic oxide-containing layer. By using an inorganic oxide as the hydrophilic layer material on the surface of the pressure-sensitive adhesive layer of the intermediate layer, the water contact angle of the surface is effectively lowered, and excellent water peelability can be easily obtained. Silicon oxide is used as a particularly preferable inorganic oxide.

In some preferred embodiments, the A layer is a layer formed from a photocurable or solvent type pressure-sensitive adhesive composition. In the configuration including the A layer formed from the photocurable or solvent type pressure-sensitive adhesive composition, the effects of the techniques disclosed herein are preferably exhibited.

In some preferred embodiments, the A layer contains a water affinity. According to the layer A containing a water-affinitive agent, it is easy to obtain a pressure-sensitive adhesive that preferably has both peeling strength in a normal state (normal state) and water-peeling property, and a pressure-sensitive adhesive in which the rate of decrease in peeling power after immersion in water is suppressed is obtained. Easy to obtain.

In some aspects of the technique disclosed herein, the structure (typically a double-sided adhesive sheet) is used by being attached to a surface (adhesive surface) having a water contact angle of 40 degrees or more. For example, the pressure-sensitive adhesive layer having the A layer among the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is attached to the surface of an adherend having a water contact angle of 40 degrees or more. Even in the embodiment of being attached to an adherend having such a hydrophobic surface, according to the technique disclosed herein, two adherends can be separated by utilizing water separation. Although not particularly limited, the surface of the adherend to which the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are attached may be a surface having a water contact angle of 40 degrees or more, and only one of them may be attached. Although the surface may have a water contact angle of 40 degrees or more, the structure disclosed here (typically, a double-sided adhesive sheet) has a water contact angle on each of the adhered surfaces of the two adherends. It is particularly suitable for usage modes of 40 degrees or higher. In such a hydrophobic adherend, it is usually difficult to exfoliate and remove the pressure-sensitive adhesive by water exfoliation, but by applying the technique disclosed herein, the hydrophobic adherend can be utilized by water exfoliation. Can be separated.

The structure disclosed herein (typically a double-sided pressure-sensitive adhesive sheet) may be in the form of a double-sided pressure-sensitive adhesive sheet with a release liner whose adhesive surface is protected by a release liner before use. Such a double-sided pressure-sensitive adhesive sheet with a release liner can be obtained by adhering one of the structures disclosed herein (typically, a double-sided pressure-sensitive adhesive sheet) to the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. It comprises at least one release liner that protects the surface. Such a double-sided adhesive sheet with a release liner may be in the form of a sheet, or may be a roll body (double-sided adhesive sheet roll with a release liner).

In some embodiments, the structure further comprises a first adherend that adheres to the first pressure-sensitive adhesive layer and a second adherend that adheres to the second pressure-sensitive adhesive layer. The first adherend and the second adherend can be separated from each other by water-separating the structure having such a structure on the hydrophilic surface of the intermediate layer. The structure has a structure including a first adherend, a first pressure-sensitive adhesive layer, an intermediate layer, a second pressure-sensitive adhesive layer, and a second adherend in this order.

In some embodiments, of the first adherend and the second adherend, the adherend that adheres to the pressure-sensitive adhesive layer having the A layer is in water contact with the surface to which the pressure-sensitive adhesive layer adheres. The angle is 40 degrees or more. It is possible to separate the two bonded adherends by performing a separation operation using water peeling on the structure in which the adherend having such a hydrophobic surface is adhered to the pressure-sensitive adhesive layer. can. Although not particularly limited, the surfaces of the first adherend and the second adherend to which the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are attached have a water contact angle of 40 degrees or more. It may be a surface, or only one surface may have a water contact angle of 40 degrees or more, but the water contact angle of the adhered surface of the first adherend and the adhered surface of the second adherend are both. It is particularly suitable for usage modes of 40 degrees or higher. Such a hydrophobic adherend is usually difficult to peel off and remove the adhesive by water peeling, but by applying the technique disclosed herein, the hydrophobicity bonded by utilizing water peeling is used. The adherend can be separated.

Since the structure disclosed here (for example, a double-sided adhesive sheet) can separate two adherends attached to each adhesive surface of the structure, the above-mentioned structure (for example, the above-mentioned structure (for example) can be utilized by utilizing this feature. For example, it is preferably used for recycling and repairing parts fixed by a double-sided adhesive sheet). For example, it is suitable for fixing members constituting electronic devices. Further, the structure disclosed here (for example, a double-sided adhesive sheet) fixes a battery, which is often removed during repair or replacement of a member constituting an electronic device, product inspection, etc., to the electronic device (main body). It is particularly preferably used as a structure of use (for example, a double-sided adhesive sheet). In some preferred embodiments, one of the first and second adherends is an electronic device body (eg, a housing of an electronic device) and the other adherend is a battery. Is. Further, according to the present specification, there is provided an electronic device in which a member (for example, a battery) is fixed by a structure (for example, a double-sided adhesive sheet).

Further, according to this specification, a method for separating the joined first adherend and the second adherend is provided. In this method, the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order between the joined first adherend and the second adherend. Further, at least one surface of the intermediate layer is a hydrophilic surface. Further, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer. The method includes a step of peeling the pressure-sensitive adhesive layer having the A layer from the intermediate layer. In the step of peeling the pressure-sensitive adhesive layer from the intermediate layer, the peeling front is in a state where an aqueous liquid is present at the interface between the intermediate layer and the pressure-sensitive adhesive layer in the peeling front of the pressure-sensitive adhesive layer from the intermediate layer. This is a water peeling step of peeling the pressure-sensitive adhesive layer from the intermediate layer while advancing the invasion of the aqueous liquid into the interface following the movement of the water-based liquid. Here, the peeling front refers to a place where the pressure-sensitive adhesive layer begins to separate from the middle layer when the pressure-sensitive adhesive layer is peeled off from the intermediate layer.
According to the water peeling step, the surface on the side of the pressure-sensitive adhesive layer A of the intermediate layer is a hydrophilic surface, so that the pressure-sensitive adhesive layer is peeled off from the intermediate layer by effectively using the aqueous liquid, and the first adhesion is performed. The body and the second adherend can be separated. The configuration in which the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order may be a pressure-sensitive adhesive sheet before joining the adherend.

Further, according to this specification, there is provided a method of separating the joined first adherend and the second adherend and joining the third adherend to the second adherend. In this method, the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order between the joined first adherend and the second adherend. Further, at least one surface of the intermediate layer is a hydrophilic surface. Further, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer. Then, the method is: a step of peeling the pressure-sensitive adhesive layer having the A layer from the intermediate layer to separate the first adherend and the second adherend; the third adherend. A step of joining to the second adherend by an adhesive sheet; Here, in the step of peeling the pressure-sensitive adhesive layer from the intermediate layer, an aqueous liquid is present at the interface between the intermediate layer and the pressure-sensitive adhesive layer in the peeling front of the pressure-sensitive adhesive layer from the intermediate layer. This is a water peeling step of peeling the pressure-sensitive adhesive layer from the intermediate layer while advancing the invasion of the aqueous liquid into the interface following the movement of the peeling front.
According to the water peeling step, the surface on the side of the pressure-sensitive adhesive layer A of the intermediate layer is a hydrophilic surface, so that the pressure-sensitive adhesive layer is peeled off from the intermediate layer by effectively using the aqueous liquid, and the first adhesion is performed. The body and the second adherend can be separated. Then, for example, a third adherend different from the first adherend can be joined to the second adherend by using an adhesive sheet at the place where the first adherend was present, so that the second adherend can be joined. In the body, the first adherend and the third adherend can be exchanged or replaced. The configuration in which the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order may be a pressure-sensitive adhesive sheet before joining the adherend.

Further, in some preferred embodiments, after the pressure-sensitive adhesive layer having the A layer is peeled off from the intermediate layer, the intermediate layer remains in the second adherend. Further, the pressure-sensitive adhesive sheet used for joining the third adherend to the second adherend includes a pressure-sensitive adhesive layer having an A layer. Further, in the adhesive sheet, the A layer side is attached to a surface of an alkaline glass plate produced by a float method as an adherend and having a contact angle of 5 to 10 degrees with respect to distilled water, and after 1 day at room temperature, the said. After dropping 20 μL of distilled water onto the adherend and allowing the distilled water to enter one end of the interface between the A layer and the adherend, JIS Z0237: 2009 10.4.1 Method 1: Test. A water peeling force B1 [N / 10 mm] measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees using a tensile tester at a test temperature of 23 ° C according to the 180 ° peeling adhesive force to the plate. The A layer side is attached to the surface of the alkaline glass plate produced by the float method as a body, which has a contact angle of 5 to 10 degrees with respect to distilled water, and the adhesive strength B0 [N / 10 mm] after 1 day at room temperature. Therefore, the water separation reduction rate calculated by the following equation: (1- (B1 / B0)) × 100; is 70% or more. As a result, after the third adherend is bonded to the second adherend, water separation is performed between the A layer of the pressure-sensitive adhesive layer to which the third adherend is bonded and the intermediate layer at an appropriate timing. Then, the third adherend and the second adherend can be separated. Further, according to the above method, for example, a fourth adherend different from the third adherend can be joined to the second adherend by using an adhesive sheet at a place where the third adherend was. It will be possible. As described above, by applying the technique disclosed herein, the adherend bonded to the second adherend (specifically, the first adherend, the third adherend, and the fourth adherend). The body, etc.) can be repeatedly separated and joined. Such an adherend (specifically, a first adherend, a third adherend, a fourth adherend, etc.) may be different parts or articles of the same type. Alternatively, the adherend (specifically, the first adherend, the third adherend, the fourth adherend, etc.) may be the same parts or articles.

Further, according to this specification, a set including the first adhesive sheet and the second adhesive sheet (for example, an adhesive sheet set) is provided. The first pressure-sensitive adhesive sheet contains a pressure-sensitive adhesive layer. On the other hand, the second pressure-sensitive adhesive sheet includes a base material layer and a pressure-sensitive adhesive layer provided on one surface of the base material layer. At least one surface of the substrate layer is a hydrophilic surface. In the set, the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet has an A layer to be attached to the hydrophilic surface, or the pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet is provided on the hydrophilic surface. It has a layer A or both. By using such a set (for example, an adhesive sheet set) in combination with the first adhesive sheet and the second adhesive sheet, the structure of the structure disclosed herein can be obtained. In addition, the above set is preferably used for joining two adherends scheduled to be separated. The above set is preferably used in the methods disclosed herein (method for separating adherends, method for separating and joining adherends).

For example, in some preferred embodiments, the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet is configured to have an A layer, and the A layer is bonded to the hydrophilic surface of the base material layer of the second pressure-sensitive adhesive sheet to form the above structure. It can be a body composition. Such a set (eg, a pressure-sensitive adhesive sheet set) includes a first pressure-sensitive adhesive sheet and a second pressure-sensitive adhesive sheet, and the first pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer having an A layer. On the other hand, the second pressure-sensitive adhesive sheet includes a base material layer and a pressure-sensitive adhesive layer provided on one surface of the base material layer, and the other surface of the base material layer is a hydrophilic surface. Then, the A layer of the first pressure-sensitive adhesive sheet is attached to the hydrophilic surface of the base material layer of the second pressure-sensitive adhesive sheet.

From the above, according to this specification, an adhesive sheet is provided. This pressure-sensitive adhesive sheet includes a base material layer and a pressure-sensitive adhesive layer provided on one surface of the base material layer. Also, at least one surface of the substrate layer is a hydrophilic surface. This pressure-sensitive adhesive sheet is preferably used for joining two adherends scheduled to be separated. Further, it is suitable as a pressure-sensitive adhesive sheet (second pressure-sensitive adhesive sheet) used in the set disclosed herein (for example, a pressure-sensitive adhesive sheet set). Alternatively, it can be preferably used in the methods disclosed herein (method for separating adherends, method for separating and joining adherends).

Further, from the above, according to this specification, an adhesive sheet is provided. This pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer having an A layer. Then, the A layer side is attached to the surface of the alkaline glass plate produced by the float method as an adherend having a contact angle of 5 to 10 degrees with respect to distilled water, and after 1 day at room temperature, 20 μL is applied to the adherend. After dropping the distilled water of JIS Z0237: 2009 at one end of the interface between the layer A and the adherend, Method 1: peeling 180 ° from the test plate. A water peeling force B1 [N / 10 mm] measured at a test temperature of 23 ° C. using a tensile tester at a tensile speed of 300 mm / min and a peeling angle of 180 degrees according to the adhesive force, and a float method as an adherend. The A layer side is attached to the surface of the alkaline glass plate produced in 1) having a contact angle of 5 to 10 degrees with respect to distilled water, and the adhesive strength is B0 [N / 10 mm] one day after room temperature. The rate of decrease in water peeling calculated by (1- (B1 / B0)) × 100; is 70% or more. This pressure-sensitive adhesive sheet is preferably used for joining two adherends scheduled to be separated. Further, it is suitable as a pressure-sensitive adhesive sheet (first pressure-sensitive adhesive sheet or second pressure-sensitive adhesive sheet) used in the set disclosed herein (for example, a pressure-sensitive adhesive sheet set). Further, the pressure-sensitive adhesive sheet can be preferably used in the methods disclosed herein (method for separating adherends, method for separating and joining adherends).

Further, according to this specification, a set including the first structure and the second structure is provided. The first structure has a first adherend and a first pressure-sensitive adhesive layer. On the other hand, the second structure has a second adherend, a second pressure-sensitive adhesive layer, and a layer having a hydrophilic surface in this order. Then, in the above set, the first pressure-sensitive adhesive layer has an A layer attached to the hydrophilic surface, or the second pressure-sensitive adhesive layer has an A layer provided on the hydrophilic surface. Or both. Such a set (typically a structure set) can be the structure disclosed herein by using the first structure and the second structure in combination. In addition, the above set can be preferably used in the methods disclosed herein (method for separating adherends, method for separating and joining adherends).

For example, in some preferred embodiments, the first pressure-sensitive adhesive layer is configured to have an A layer, and the A layer is attached to the hydrophilic surface of the layer having a hydrophilic surface, whereby the structure disclosed herein. It can be a body composition. In such a set (typically a structure set), the first structure comprises a first pressure-sensitive adhesive layer having an A layer. The first pressure-sensitive adhesive layer is typically attached to one surface of the first adherend. On the other hand, in the second structure, the second pressure-sensitive adhesive layer is arranged on the other surface of the layer having a hydrophilic surface. Then, the A layer of the pressure-sensitive adhesive layer constituting the first structure is attached to the hydrophilic surface of the second structure.

From the above, according to this specification, a structure having an adherend, an adhesive layer, and a layer having a hydrophilic surface is provided in this order. This structure is suitable as a structure (second structure) used in the set disclosed herein (typically a structure set). Alternatively, it can be preferably used in the methods disclosed herein (method for separating adherends, method for separating and joining adherends).

Further, from the above, according to this specification, a structure having an adherend and an adhesive layer is provided. In this structure, the pressure-sensitive adhesive layer has an A layer. Then, in the above structure, the A layer side is attached to a surface of an alkaline glass plate produced by a float method as an adherend having a contact angle of 5 to 10 degrees with respect to distilled water, and one day after room temperature, the structure is described. After dropping 20 μL of distilled water onto the adherend and allowing the distilled water to enter one end of the interface between the A layer and the adherend, JIS Z0237: 2009 10.4.1 Method 1: Test plate. Water peeling force B1 [N / 10 mm] measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees using a tensile tester at a test temperature of 23 ° C. The A layer side is attached to the surface of the alkaline glass plate produced by the float method as a body having a contact angle of 5 to 10 degrees with respect to distilled water, and the adhesive strength is B0 [N / 10 mm] after 1 day at room temperature. Therefore, the water peeling reduction rate calculated by the following formula: (1- (B1 / B0)) × 100; is 70% or more. This structure is suitable as a structure (first structure or second structure) used in the set disclosed herein (typically a structure set). In addition, the above structure can be preferably used in the methods disclosed herein (method for separating adherends, method for separating and joining adherends).

It should be noted that an appropriate combination of the above-mentioned elements may be included in the scope of the invention for which protection by the patent is sought by the present patent application.

It is sectional drawing which shows typically the structure of the structure (double-sided adhesive sheet) which concerns on one Embodiment. It is sectional drawing which shows typically the structure of the structure (double-sided adhesive sheet) which concerns on another embodiment. It is sectional drawing which shows typically the structure of the structure (double-sided adhesive sheet) which concerns on another embodiment. It is sectional drawing which shows typically the modification of the structure (double-sided adhesive sheet) shown in FIG. It is sectional drawing which shows typically the structure of the structure (joint body) which concerns on one Embodiment. It is sectional drawing which shows typically the modification of the structure (joint) shown in FIG. It is sectional drawing which shows the other modification of the structure (joint) shown in FIG. 5 schematically. It is sectional drawing which shows the other modification of the structure (joint) shown in FIG. 5 schematically. It is sectional drawing which shows typically the structure of the 1st adhesive sheet used as a set. It is sectional drawing which shows typically the structure of the 2nd adhesive sheet used as a set. It is sectional drawing which shows typically the structure of the 1st structure used as a set. It is sectional drawing which shows typically the structure of the 2nd structure used as a set.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings regarding the implementation of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art. Further, in the following drawings, members / parts having the same function may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are schematically for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actually provided product.

In this specification, the "acrylic polymer" refers to a polymer derived from a monomer component containing an acrylic monomer in an amount of more than 50% by weight. The acrylic monomer refers to a monomer derived from a monomer having at least one (meth) acryloyl group in one molecule. Further, in this specification, "(meth) acryloyl" means a comprehensively referring to acryloyl and methacryloyl. Similarly, "(meth) acrylate" means acrylate and methacrylate, and "(meth) acrylic" means acrylic and methacrylic, respectively. The acrylic polymer may be an acrylic polymer. The acrylic polymer may be, for example, an acrylic polymer contained as a base polymer (main constituent polymer) in a water-dispersible type or solvent type pressure-sensitive adhesive. In this case, the "monomer component constituting the acrylic polymer" in the present specification can be paraphrased as "monomer component constituting the acrylic polymer". Further, in the present specification, the content of the additive component represented by the relative amount of the "monomer component constituting the polymer" and the "monomer component constituting the acrylic polymer" is relative to the "acrylic polymer". It can be rephrased as quantity.

<Structure example of structure>
The structure disclosed herein can be, for example, in the form of a double-sided pressure-sensitive adhesive sheet having the cross-sectional structure schematically shown in FIG. The structure 1 is configured as a double-sided pressure-sensitive adhesive sheet containing the first pressure-sensitive adhesive layer 11, the intermediate layer 20, and the second pressure-sensitive adhesive layer 12 in this order. The intermediate layer 20 is also referred to as a base material layer in the double-sided adhesive sheet 1. In this structure 1, the first pressure-sensitive adhesive layer 11 and the second pressure-sensitive adhesive layer 12 are provided on each surface of the intermediate layer 20, respectively. The adhesive surface 11A of the first adhesive layer 11 and the adhesive surface 12A of the second adhesive layer 12 are the surfaces (each adhesive surface) 1A and 1B of the structure (double-sided adhesive sheet) 1. In this structure 1, one surface 20A of the intermediate layer 20 is a hydrophilic surface. Specifically, the intermediate layer 20 has a laminated structure of the main layer 22 and the hydrophilic layer 24, and the surface 20A, which is the surface of the hydrophilic layer 24, is a hydrophilic surface. In this embodiment, the hydrophilic layer 24 is formed on one surface of the main layer 22. The first pressure-sensitive adhesive layer 11 is in close contact with the hydrophilic surface 20A of the intermediate layer 20, and specifically, one surface of the first pressure-sensitive adhesive layer 11 (the surface opposite to the pressure-sensitive adhesive surface 11A) 11B is in the middle. It is laminated in direct contact with the hydrophilic layer 24 of the layer 20. Further, in the example shown in FIG. 1, the first pressure-sensitive adhesive layer 11 has a single-layer structure. That is, the entire first pressure-sensitive adhesive layer 11 is composed of the A layer constituting one surface (the surface on the hydrophilic surface 20A side of the intermediate layer 20) 11B of the first pressure-sensitive adhesive layer 11. On the other hand, the second pressure-sensitive adhesive layer 12 is in close contact with the other surface 20B of the intermediate layer 20, and one surface (the surface opposite to the pressure-sensitive adhesive surface 12A) 12B of the second pressure-sensitive adhesive layer 12 is the intermediate layer 20. It is laminated in direct contact with the main layer 22. The second pressure-sensitive adhesive layer 12 also has a single-layer structure. The other surface 20B of the intermediate layer 20 is a hydrophobic surface in this embodiment.

As shown in FIG. 1, for example, the adhesive surface 1A (adhesive surface 11A of the first adhesive layer 11) of the structure (double-sided adhesive sheet) 1 before use (before attachment to the adherend) is at least adhesive. The surface 1A (the first pressure-sensitive adhesive layer 11) is protected by a release liner 31 having a peelable surface (peeling surface), and the pressure-sensitive adhesive surface 1B (the adhesive surface 12A of the second pressure-sensitive adhesive layer 12) is at least. It may be in the form of a double-sided pressure-sensitive adhesive sheet (structure) 51 with a release liner protected by a release liner 32 whose adhesive surface 1B (second adhesive layer 12) side is a releaseable surface (release surface). Alternatively, the back surface 31A of the release liner 31 (the surface opposite to the surface on the first adhesive layer 11 side) is the release surface, and the adhesive surface 1B (the adhesive surface 12A of the second adhesive layer 12) is on the back surface 31A. ) May be in a form in which the

adhesive surfaces

1A and 1B (

adhesive surfaces

11A and 12A) are protected by being wound or laminated so as to be in contact with each other.

FIG. 2 shows another configuration example of the structure (double-sided adhesive sheet) disclosed here. In this structure 2, a first pressure-sensitive adhesive layer 110 and a second pressure-sensitive adhesive layer 120 are provided on each surface of the intermediate layer 20, respectively, and one surface 20A of the intermediate layer 20 is a hydrophilic surface, and the intermediate layer is formed. 20 has the same structure as that shown in FIG. 1 in that the main layer 22 and the hydrophilic layer 24 have a laminated structure, but the structure of the first pressure-sensitive adhesive layer 110 is different from the structure shown in FIG. Specifically, in the structure 2 shown in FIG. 2, one surface 110A of the first pressure-sensitive adhesive layer 110 is a pressure-sensitive surface. Further, the first pressure-sensitive adhesive layer 110 is a layer A 112 constituting the other surface (surface on the intermediate layer 20 side) 110B of the first pressure-sensitive adhesive layer 110, and a layer B 114 laminated on the back surface side of the layer A 112. It has a two-layer structure consisting of and. The A layer 112 of the first pressure-sensitive adhesive layer 110 is in close contact with the hydrophilic surface 20A of the intermediate layer 20, and specifically, the surface 110B of the first pressure-sensitive adhesive layer 110 is directly connected to the hydrophilic surface 24 of the intermediate layer 20. They are laminated in contact with each other.

The structure (double-sided adhesive sheet) 2 before use (before being attached to the adherend) has an adhesive surface 2A (surface 110A of the B layer 114), similarly to the structure (double-sided adhesive sheet) 1 shown in FIG. Double-sided adhesive sheet with a release liner (structure) protected by

release lines

31 and 32 whose adhesive surface 2B (adhesive surface 120A of the second adhesive layer 120) has at least the adhesive surface side as a peelable surface (peeling surface). ) 52 can be in the form. Alternatively, the back surface 31A of the release liner 31 (the surface opposite to the surface on the first adhesive layer 110 side) is the release surface, and the adhesive surface 2B (the adhesive surface 120A of the second adhesive layer 120) is on the back surface 31A. ) May be in a form in which the

adhesive surfaces

2A and 2B (110A and 120A) are protected by being wound or laminated so as to be in contact with each other. Regarding the configuration of the structure 2, the description of the portion overlapping with the structure 1 shown in FIG. 1 will be omitted.

Further, FIG. 3 shows another configuration example of the structure (double-sided adhesive sheet) disclosed here. In this structure 3, a first pressure-sensitive adhesive layer (A layer) 11 and a second pressure-sensitive adhesive layer 12 are provided on each surface of the intermediate layer 200, respectively, and one surface 200A of the intermediate layer 200 is a hydrophilic surface. The configuration is the same as that shown in FIG. 1, but the configuration of the intermediate layer 200 is different from the configuration shown in FIG. Specifically, in the structure 3 shown in FIG. 3, the intermediate layer 200 has a single-layer structure. The intermediate layer 200 is formed by using a hydrophilic material, so that its surface, 200A, is a hydrophilic surface. In the intermediate layer 200, the

surfaces

200A and 200B of the intermediate layer 200 are hydrophilic surfaces. Regarding the configuration of the structure 3, the description of the portion overlapping with the structure 1 shown in FIG. 1 will be omitted.

Further, a modified example of the structure (double-sided adhesive sheet) 1 is shown in FIG. The structure 4 shown in FIG. 4 is provided with a first pressure-sensitive adhesive layer 13 and a second pressure-sensitive adhesive layer 12 on each surface of the intermediate layer 20, respectively, and one surface 20A of the intermediate layer 20 is a hydrophilic surface. The intermediate layer 20 has a laminated structure of the main layer 22 and the hydrophilic layer 24, which is the same as the configuration of FIG. 1, but the laminated state of the first pressure-sensitive adhesive layer 13 and the intermediate layer 20 is the configuration shown in FIG. Different from. Specifically, in the structure 4 shown in FIG. 4, the first pressure-sensitive adhesive layer (A layer) 13 is arranged on the hydrophilic surface (surface of the hydrophilic layer 24) which is one surface 20A of the intermediate layer 20. However, the first pressure-sensitive adhesive layer 13 is not arranged on the entire surface (hydrophilic surface) 20A of the intermediate layer 20, and is partially covered with a hydrophilic surface (hydrophilic surface) including the end portion of the intermediate layer 20. 24 surface) 20A has a pressure-sensitive adhesive layer non-existent region 25 in which the first pressure-sensitive adhesive layer 13 is not provided. The pressure-sensitive adhesive layer non-existent region 25 is an exposed surface in the structure (double-sided pressure-sensitive adhesive sheet) 4. On the other hand, the other surface 20B of the intermediate layer 20 is not provided with the region where the pressure-sensitive adhesive layer does not exist as described above, and the second pressure-sensitive adhesive layer 12 is arranged on almost the entire surface of the surface 20B. Therefore, in this embodiment, the size (surface size) of the first pressure-sensitive adhesive layer 13 is smaller than that of the second pressure-sensitive adhesive layer 12, and the pressure-sensitive adhesive surface 13A (adhesive surface 4A) of the first pressure-sensitive adhesive layer 13 is the first. 2 It is configured to be smaller than the adhesive surface 12A (adhesive surface 4B) of the adhesive layer 12. Further, also in the double-sided adhesive sheet 54 with a release liner provided with the structure (double-sided adhesive sheet) 4, the size of the release liner 33 that protects the adhesive surface 4A is smaller than that of the release liner 32 that protects the adhesive surface 4B. There is. Regarding the configuration of the structure 4, the description of the portion overlapping with the structure 1 shown in FIG. 1 will be omitted.

The structure disclosed herein may be, for example, in the form of a bonded body having a cross-sectional structure schematically shown in FIG. The structure 5 has a structure of a laminated body including the first pressure-sensitive adhesive layer 11, the intermediate layer 20, and the second pressure-sensitive adhesive layer 12 in this order, and in this respect, the structure shown in FIG. Is the same as. Unlike the structure (double-sided adhesive sheet) 1 of FIG. 1, this structure (bonded body) 5 has a first adherend 60 attached to one surface (adhesive surface) 11A of the first adhesive layer 11. The first adherend 60 is adhered (non-peelable adhesive) to the first pressure-sensitive adhesive layer 11. Further, the second adherend 70 is attached to one surface (adhesive surface) 12A of the second adhesive layer 12, and the second adherend 70 is adhered (non-adhesive) to the second adhesive layer 12. (Peelable adhesion). As described above, the structure 5 further includes the first adherend 60 and the second adherend 70, and the first adherend 60 and the second adherend 70 are the first adhesive layer 11. , It is joined via the intermediate layer 20 and the second pressure-sensitive adhesive layer 12. In other words, the structure 5 has a structure of a junction of the first adherend 60 and the second adherend 70. The structure 5 has a structure including a first adherend 60, a first pressure-sensitive adhesive layer 11, an intermediate layer 20, a second pressure-sensitive adhesive layer 12, and a second adherend 70 in this order. In the structure 5 of this embodiment, as in the configuration of FIG. 1, one surface 20A of the intermediate layer 20 is a hydrophilic surface, and the first pressure-sensitive adhesive layer (A layer) 11 is the intermediate layer 20. It is in close contact with the hydrophilic surface 20A. Further, in this embodiment, both the first adherend 60 and the second adherend 70 are hydrophobic adherends made of a hydrophobic material having a hydrophobic adhered surface. Regarding the configuration of the structure 5, the description of the portion overlapping with the structure 1 shown in FIG. 1 will be omitted. Further, the non-peeling adhesive refers to an adhesive form in which peeling is not intended or planned, and does not exclude an adhesive capable of forced peeling which may be accompanied by damage to the adherend.

According to the above configuration, even if the adhered surface of the two adherends to be joined is hydrophobic, the two adherends can be separated by water separation using an aqueous liquid such as water. can. Specifically, two adherends joined by the structure by separating the structure (for example, a double-sided pressure-sensitive adhesive sheet) between the pressure-sensitive adhesive layer having the A layer and the hydrophilic surface of the intermediate layer by water peeling. The body can be separated. The structure (eg, double-sided adhesive sheet) is preferably used for joining the adherends, for example, when both of the two adherends to be separated have a hydrophobic surface. Detachment of the adhesive using water peeling is convenient in that it can be carried out without damaging the adherend or with less physical load, but when the adherend is hydrophobic, it is excellent. Usually, there is a limitation that it is difficult to remove the adhesive by peeling with water. In response to such technical issues, we intentionally adopted a new configuration based on the technical idea of separating a structure (for example, a double-sided adhesive sheet) between an intermediate layer and an adhesive layer using water separation. By doing so, even in the usage mode of joining the hydrophobic adherend as described above, in other words, the adherence bonded by the adhesive by utilizing water peeling regardless of the type of the adherend. It becomes possible to separate the body.

Further, by providing the adhesive layer non-existing region on the hydrophilic surface of the intermediate layer as in the structure shown in FIG. 4, when the adhesive layer is water-peeled from the hydrophilic surface of the intermediate layer, the end An aqueous liquid can be applied to the region where the pressure-sensitive adhesive layer does not exist in the portion to start and proceed with water peeling. In short, the region where the pressure-sensitive adhesive layer does not exist on the hydrophilic surface of the intermediate layer can be a starting point for water exfoliation.

The structure 6 shown in FIG. 6 is a modified example of the structure (joint body) 5. The structure 6 shown in FIG. 6 has the same as the structure 5 shown in FIG. 5, the first adherend 60, the first adhesive layer 11, the intermediate layer 20, the second adhesive layer 12, and the second adherend. It has a configuration including 70 in this order. Further, one surface 20A of the intermediate layer 20 is a hydrophilic surface, and the first pressure-sensitive adhesive layer (A layer) 11 is in close contact with the hydrophilic surface 20A of the intermediate layer 20. Further, the structure 6 is provided with the pressure-sensitive adhesive layer non-existing region 25 at the end of the intermediate layer 20 as in the configuration shown in FIG. Further, a pickup tape 80 is attached to the end of the first adherend 60 to the structure 6. Specifically, the pickup tape 80 is fixed to the end portion of the intermediate layer 20 on the side where the pressure-sensitive adhesive layer non-existent region 25 is provided. By using this pickup tape 80, the first adherend 60 and the second adherend 70 are separated more smoothly. As the pickup tape 80, a known or conventional adhesive tape can be used. Regarding the configuration of the structure 6, the description of the portion overlapping with the structure 5 shown in FIG. 5 will be omitted.

The structure 7 shown in FIG. 7 is another modification of the structure (joint) 5. In FIG. 7, for convenience of explanation, the structure 7 is turned upside down, but the structure 7 has the first adherend 60 and the first adherend, similarly to the

structures

5 and 6 shown in FIGS. 5 and 6. It has a structure including the pressure-sensitive adhesive layer 11, the intermediate layer 20, the second pressure-sensitive adhesive layer 12, and the second adherend 70 in this order. Then, in the structure 7, the pickup tape 80 is attached to the end portion of the second adherend 70. Specifically, the pickup tape 80 is fixed to the end portion of the intermediate layer 20 on the side where the pressure-sensitive adhesive layer non-existent region 25 is provided. Regarding the configuration of the structure 7, the description of the portion overlapping with the structure 5 shown in FIG. 5 will be omitted.

The structure 8 shown in FIG. 8 is another modification of the structure (joint) 5. In FIG. 8, for convenience of explanation, the structure 8 is turned upside down, but the structure 8 has the first adherend 60 and the first adherend, similarly to the

structures

5 and 6 shown in FIGS. 5 and 6. It has a structure including the pressure-sensitive adhesive layer 11, the intermediate layer 20, the second pressure-sensitive adhesive layer 12, and the second adherend 70 in this order. Then, in the structure 8, the laminated structure portion (which may be a double-sided pressure-sensitive adhesive sheet) of the first pressure-sensitive adhesive layer 11, the intermediate layer 20, and the second pressure-sensitive adhesive layer 12 is the first adherend 60 and the second cover. It has an extending portion 90 extending from a portion sandwiched between the body 70 and the body 70. The extended portion 90 is a grip portion that protrudes from the structure 8 and can be gripped with bare hands, and can exhibit the same function as the above-mentioned pickup tape. That is, by using the extending portion 90, the first adherend 60 and the second adherend 70 can be separated more smoothly. The extending portion 90 may be in a state of being attached to the back surface of the second adherend 70 as shown in the figure before the adherend is separated. Regarding the configuration of the structure 8, the description of the portion overlapping with the structure 5 shown in FIG. 5 will be omitted.

According to the above configuration, when the first adherend 60 and the second adherend 70 are separated, the aqueous liquid is applied to the pressure-sensitive adhesive layer non-existent region 25 of the hydrophilic surface 20A of the intermediate layer 20. By pulling the pickup tape 80 or the extending portion 90, water separation is started between the hydrophilic surface side surface 11B of the first pressure-sensitive adhesive layer (A layer) 11 and the hydrophilic surface 20A of the intermediate layer 20. The first pressure-sensitive adhesive layer 11 and the intermediate layer 20 can be separated, and the first adherend 60 and the second adherend 70 can be separated.

From the explanation of each of the above configuration examples, the structure may be in the form of either a double-sided pressure-sensitive adhesive sheet with a base material, a double-sided pressure-sensitive adhesive sheet with a release liner, or a bonded body.

Further, the intermediate layer may be formed as long as at least one surface thereof is a hydrophilic surface, and for example, both sides may be composed of a hydrophilic surface. In that case, the intermediate layer is not limited to a single-layer structure made of a hydrophilic material, and may be, for example, one in which hydrophilic layers are formed on both sides of the intermediate layer. In that case, the intermediate layer may have a laminated structure including the hydrophilic layer, the main layer, and the hydrophilic layer in this order.

Further, each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may have a single-layer structure or a multi-layer structure. For example, the second pressure-sensitive adhesive layer may include an A layer and a B layer. Further, in the configuration in which the intermediate layer has a hydrophilic surface on the side of the second pressure-sensitive adhesive layer, the first pressure-sensitive adhesive layer may not contain the A layer.

Further, the above configuration example and modification configuration can be applied to other configuration examples and modification examples. Each element in the above-mentioned configuration example and modification example can be combined. For example, the structure of the structure 4 shown in FIG. 4 (the structure having the adhesive layer non-existing region on the hydrophilic surface of the intermediate layer) is applied to the structures (double-sided pressure-sensitive adhesive sheets) 2 and 3 shown in FIGS. 2 and 3. Needless to say, it can be applied not only to the structure (joint body) 5 shown in FIG. Further, the structure (bonded body) 5 shown in FIG. 5 has a structure as shown in FIG. 2 (a structure in which the first pressure-sensitive adhesive layer has an A layer and a B layer) and a structure shown in FIG. 3 (a single-layer structure). It is also possible to adopt a configuration having an intermediate layer).

Further, in the structure (bonded body) shown in FIG. 5, both the first adherend and the second adherend were hydrophobic adherends, but the first adherend was not limited to this. And only one of the second adherends may be a hydrophobic adherend, and neither the first adherend nor the second adherend may be a hydrophobic adherend. The techniques disclosed herein are suitable, but not limited to, the separation of hydrophobic adherends. The advantages of the techniques disclosed herein may include versatility and convenience that allow the adherend to be separated regardless of the type of adherend. Therefore, the type of adherend is not particularly limited.

Further, the laminated structure of the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer in the structure shown in FIG. 5 is obtained from the double-sided pressure-sensitive adhesive sheet shown in any one of FIGS. 1 to 4 in some embodiments. be able to. Specifically, by attaching each adhesive surface of the above-mentioned double-sided adhesive sheet to the first adherend and the second adherend, respectively, a structure in which the two adherends are joined can be obtained. .. Alternatively, the laminated structure of the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer in the bonded body is, in some other embodiments, a first pressure-sensitive adhesive sheet including the first pressure-sensitive adhesive layer and a second. It can also be obtained by using it in combination with a second pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive layer. In that case, the intermediate layer may be contained in either the first adhesive sheet or the second adhesive sheet, and separately from the first adhesive sheet and the second adhesive sheet, the first adhesive sheet is formed at the time of forming the bonded body. It may be in the form of a sheet material (intermediate layer sheet) interposed between the agent layer and the second pressure-sensitive adhesive layer. The first pressure-sensitive adhesive sheet and the second pressure-sensitive adhesive sheet may be a first pressure-sensitive adhesive sheet and a second pressure-sensitive adhesive sheet, which are constituent elements of the pressure-sensitive adhesive sheet set described later, respectively.

<Example of set configuration>
The set disclosed herein includes, for example, a first pressure-sensitive adhesive sheet 410 having a cross-sectional structure schematically shown in FIG. 9 and a second pressure-sensitive adhesive sheet 420 having a cross-section structure schematically shown in FIG. ..

As shown in FIG. 9, the first adhesive sheet 410 constituting the set (adhesive sheet set) 400 does not have a support (base material) composed of an adhesive layer (also referred to as a first adhesive layer in the set 400) 411. It is configured as a double-sided adhesive sheet. The pressure-sensitive adhesive layer 411 has an A layer. In the example shown in FIG. 9, the pressure-sensitive adhesive layer 411 has a single-layer structure, and the entire pressure-sensitive adhesive layer 411 is composed of the layer A constituting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer 411. The first adhesive sheet 410 may be in the form of an adhesive sheet 451 with a release liner before use (before attachment to an adherend). In some embodiments, the first pressure-sensitive adhesive sheet 410 is protected by a release liner 431,432 in which each

surface

411A, 411B of the pressure-sensitive adhesive layer 411 has at least a peelable surface (peeling surface) on the pressure-sensitive adhesive layer side. It can be a form. Alternatively, the back surface of the release liner 431 (the surface opposite to the adhesive side) is the release surface, and the adhesive surface is wound or laminated so that the adhesive surface 411B abuts on the back surface of the release liner 431. 411A and 411B may be in a protected form.

Further, as shown in FIG. 10, the second adhesive sheet 420 constituting the set (adhesive sheet set) 400 includes an adhesive layer (also referred to as a second adhesive layer in the set 400) 422 and an adhesive layer 422. It is configured as a single-sided adhesive adhesive sheet containing a base material layer 425 laminated on one surface 422B. One surface 420A of the pressure-sensitive adhesive sheet 420 is a hydrophilic surface. On the other hand, the other surface 420B of the pressure-sensitive adhesive sheet 420 is composed of the other surface (adhesive surface) 422A of the pressure-sensitive adhesive layer 422, and is a surface to be attached to the adherend. The base material layer 425 has a laminated structure of a main layer 427 and a hydrophilic layer 428, and specifically constitutes one surface (hydrophilic surface) 425A of the main layer 427 and the base material layer 425. It is provided with a hydrophilic layer 428. The pressure-sensitive adhesive layer 422 is in close contact with the pressure-sensitive adhesive layer side surface 425B (opposite surface of one surface 425A) which is the other surface of the base material layer 425, and the pressure-sensitive adhesive layer 422 is one surface of the base material layer 425. It is fixedly bonded to 425B. In the second pressure-sensitive adhesive sheet 420 before use (before sticking to the adherend), for example, as shown in FIG. 10, the pressure-sensitive adhesive surface 422A of the pressure-sensitive adhesive layer 422 has a peelable surface (peeling surface) at least on the pressure-sensitive adhesive layer side. It may be in the form of an adhesive sheet 452 with a release liner, which is protected by the release liner 433.

As described above, by using the first adhesive sheet 410 and the second adhesive sheet 420 as a set, the structure disclosed here can be obtained. Specifically, before and after the attachment to the adherend, the release liner 431 covering the adhesive layer 411 of the first adhesive sheet 410 is peeled off, and the exposed adhesive surface 411A is removed from the base material layer 425 of the second adhesive sheet 420. By adhering to one surface (hydrophilic surface) 425A, the structure of the structure disclosed herein can be obtained.

In the above configuration example, the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet is composed of the A layer, and the A layer is attached to the hydrophilic surface of the base material layer of the second pressure-sensitive adhesive sheet. Not limited to this. The layer A may be any as long as it is arranged on the hydrophilic surface of the base material layer, and as long as the layer A has the A layer, both the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet have the A layer. Alternatively, only the pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet may have the A layer. When the second pressure-sensitive adhesive sheet has an A layer, the A layer is arranged on the hydrophilic surface side of the base material layer.

Further, in the above configuration example, the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet both have a single-layer structure, but the present invention is not limited to this, and the layer A is hydrophilic of the base material layer. Each pressure-sensitive adhesive layer may have a multi-layer structure including, for example, an A layer and a B layer as long as they are arranged on a property surface.

Further, the base material layer may be such that at least one surface thereof is a hydrophilic surface, and for example, both sides may be composed of a hydrophilic surface. In that case, the base material layer is not limited to a single-layer structure made of a hydrophilic material, and may be, for example, one in which hydrophilic layers are formed on both sides of the base material layer. In that case, the base material layer may have a laminated structure including the hydrophilic layer, the main layer, and the hydrophilic layer in this order.

Further, it is preferable that the first pressure-sensitive adhesive sheet and the second pressure-sensitive adhesive sheet are superposed so that the hydrophilic surface of the second pressure-sensitive adhesive sheet has a region where the pressure-sensitive adhesive layer does not exist at the end thereof. As an example of such means, a method of making the first adhesive sheet smaller than the second adhesive sheet, or making the adhesive surface (A layer surface) of the first adhesive sheet smaller than the hydrophilic surface of the second adhesive sheet. There is a way to do it.

Further, the set disclosed herein includes, for example, a first structure 510 having a cross-sectional structure schematically shown in FIG. 11 and a second structure 520 having a cross-sectional structure schematically shown in FIG. including.

As shown in FIG. 11, the first structure 510 constituting the set (structure set) 500 is one of an adherend (also referred to as a first adherend in the set 500) 512 and an adherend 512. It has a pressure-sensitive adhesive layer (also referred to as a first pressure-sensitive adhesive layer in the set 500) 511 attached to the surface. The pressure-sensitive adhesive layer 511 has an A layer. In the example shown in FIG. 11, the pressure-sensitive adhesive layer 511 has a single-layer structure, and the entire pressure-sensitive adhesive layer 511 is composed of the layer A constituting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer 511. One surface 511A of the pressure-sensitive adhesive layer 511 is attached to the adhered surface 512A of the adherend 512, and the adherend 512 is adhered (non-peelable adhesion) to the pressure-sensitive adhesive layer 511. The other surface 511B of the pressure-sensitive adhesive layer 511 is an adhesive surface to be attached to the hydrophilic surface 520A of the second structure 520 described later, and at least one surface becomes a peelable surface (peeling surface) before the attachment. It can be in a form protected by a release liner (not shown). In this embodiment, the first adherend 512 is a hydrophobic adherend made of a hydrophobic material having a hydrophobic surface 512A to be adhered.

Further, as shown in FIG. 12, the second structure 520 constituting the (structure set) 500 includes an adherend (also referred to as a second adherend in the set 500) 522 and an adhesive layer (set 500). In the above, it is also referred to as a second pressure-sensitive adhesive layer.) 521 and a layer 525 having a hydrophilic surface are provided in this order. One surface 520A of this structure 520 is a hydrophilic surface. The layer 525 having a hydrophilic surface has a laminated structure of a main layer 527 and a hydrophilic layer 528, and specifically, one surface of the main layer 527 and the layer 525 having a hydrophilic surface (hydrophilicity). Surface) A hydrophilic layer 528 constituting 525A is provided. One surface 521B of the pressure-sensitive adhesive layer 521 is attached to the adhered surface 522A of the adherend 522, and the adherend 522 is adhered (non-peelable adhesion) to the pressure-sensitive adhesive layer 521. The other surface 521A of the pressure-sensitive adhesive layer 521 is in close contact with the other surface 525B (opposite surface of one surface 525A) of the layer 525 having a hydrophilic surface, and the pressure-sensitive adhesive layer 521 is a layer 525 having a hydrophilic surface. It is fixedly bonded to the other surface 525B of.

As described above, by using the first structure 510 and the second structure 520 as a set, the structure disclosed here can be obtained. Specifically, by laminating the adhesive surface 511B of the pressure-sensitive adhesive layer 511 of the first structure 510 to the hydrophilic surface 520A of the second structure 520, the structure of the structure disclosed here can be obtained.

In the above configuration example, the pressure-sensitive adhesive layer of the first structure is composed of the A layer, and the A layer is attached to the hydrophilic surface of the second structure, but the present invention is not limited to this. .. The layer A may be any as long as it is arranged on the hydrophilic surface of the layer having a hydrophilic surface, and as long as the layer A, both the pressure-sensitive adhesive layer of the first structure and the pressure-sensitive adhesive layer of the second structure are the A layer. May have, and only the pressure-sensitive adhesive layer of the second structure may have the A layer. When the second structure has an A layer, the A layer is arranged on the hydrophilic surface side of the layer having a hydrophilic surface.

Further, in the above configuration example, the pressure-sensitive adhesive layer of the first structure and the pressure-sensitive adhesive layer of the second structure are both single-layer structures, but the present invention is not limited to this, and the layer A is arranged on the hydrophilic surface. Each pressure-sensitive adhesive layer may have a multi-layer structure including, for example, an A layer and a B layer.

Further, the layer having a hydrophilic surface may be such that at least one surface thereof is a hydrophilic surface, and for example, both sides may be composed of a hydrophilic surface. In that case, the layer is not limited to a single-layer structure made of a hydrophilic material, and may be, for example, a layer having hydrophilic layers formed on both sides. In that case, the layer may have a laminated structure including a hydrophilic layer, a main layer, and a hydrophilic layer in this order.

Further, it is preferable that the first structure and the second structure are superposed so that the hydrophilic surface of the second structure has a region where the adhesive layer does not exist at the end thereof. As an example of such means, there is a method of forming the adhesive surface of the first structure smaller than the hydrophilic surface of the second structure.

<Characteristics of structure>
(Rate of decrease in water peeling power)
The structure disclosed here has a water peeling force reduction rate of 70% or more. The structure showing the rate of decrease in water peeling force can easily peel the pressure-sensitive adhesive layer from the intermediate layer by using an aqueous liquid such as water. For example, a small amount of an aqueous liquid is supplied between the intermediate layer of the structure and the pressure-sensitive adhesive layer, and the aqueous liquid is allowed to enter the interface between the intermediate layer and the pressure-sensitive adhesive layer from one end of the structure to trigger peeling. By making it, the peeling strength of the pressure-sensitive adhesive layer from the intermediate layer can be significantly reduced. Utilizing this property, the intermediate layer and the pressure-sensitive adhesive layer can be separated by water exfoliation using an aqueous liquid such as water, and the two bonded bodies can be separated. In some preferred embodiments, the rate of decrease in water peeling power may be, for example, 75% or more, 85% or more, 90% or more, 95% or more, or 97% or more. The rate of decrease in water peeling force is 100% or less in principle, and typically less than 100%.
The rate of decrease in water peeling power is calculated by the formula:
Water peeling power reduction rate [%] = (1- (A1 / A0)) × 100
Can be obtained from. Here, A1 is a water peeling force A1 [N / 10 mm] described later, and A0 is a peeling strength A0 [N / 10 mm] described later. In the technique disclosed herein, the water peeling force reduction rate is realized by selecting an intermediate layer material, a hydrophilic layer formation, a hydrophilic layer constituent material, an adhesive type, a composition, and the like.

(Peeling strength A0)
In the structure disclosed herein, the peel strength A0 of the pressure-sensitive adhesive layer with respect to the intermediate layer is not particularly limited, but is preferably 2.0 N / 10 mm or more. Here, the peel strength A0 is a peel strength (normal peel strength) measured under the conditions of a temperature of 23 ° C., a tensile speed of 300 mm / min, and a peeling angle of 180 degrees. It can also be said that the pressure-sensitive adhesive layer having the peel strength A0 is adhered to the intermediate layer with a peel strength A0 of a predetermined value or more. As a result, the pressure-sensitive adhesive layer of the structure is stably adhered to the intermediate layer, and it is possible to prevent the occurrence of a problem that the pressure-sensitive adhesive layer is unintentionally peeled off from the intermediate layer during use. The structure having the peel strength can show good adhesiveness to the adherend. Therefore, it is possible to achieve both adhesive reliability during normal use and good separability during adhesion separation. In some embodiments, the peel strength A0 may be, for example, 2.5N / 10mm or more, and may be 3.0N /, from the viewpoint of adhesion between the pressure-sensitive adhesive layer and the intermediate layer and adhesion to the adherend. It may be 10 mm or more, 3.5 N / 10 mm or more, 4.0 N / 10 mm or more, 4.5 N / 10 mm or more, or 5.0 N / 10 mm or more. In some other embodiments, the peel strength A0 may be, for example, 6.0 N / 10 mm or more, 7.0 N / 10 mm or more, 8.0 N / 10 mm or more, 9.0 N / 10 mm or more. It may be 10.0 N / 10 mm or more, or 11.0 N / 10 mm or more. The upper limit of the peel strength A0 is not particularly limited, and may be, for example, 30 N / 10 mm or less. The peel strength A0 may be 20 N / 10 mm or less, or 15 N / 10 mm or less (for example, 12 N / 10 mm or less). In some embodiments, the peel strength A0 may be less than 10N / 10mm or less than 8N / 10mm. The peel strength A0 is specifically measured by the method described in Examples described later.

(Water peeling force A1)
The structure disclosed herein supplies 20 μL of distilled water between the intermediate layer and the pressure-sensitive adhesive layer, and after the distilled water is allowed to enter one end of the interface between the pressure-sensitive adhesive layer and the intermediate layer. , JIS Z0237: 2009 10.4.1 Method 1: 180 ° peeling adhesive force to the test plate, specifically, using a tensile tester at a test temperature of 23 ° C., tensile speed 300 mm / min, peeling angle The water peeling force A1 [N / 10 mm] measured under the condition of 180 degrees may be limited to a predetermined value or less. According to the structure in which the water peeling force A1 is limited, the pressure-sensitive adhesive layer is easily peeled off by applying an aqueous liquid such as water to the surface of the intermediate layer and allowing it to enter the interface between the surface of the intermediate layer and the surface of the pressure-sensitive adhesive layer. be able to. Although not particularly limited, the water peeling force A1 may be, for example, 3.5 N / 10 mm or less, 2.5 N / 10 mm or less, 1.6 N / 10 mm or less, or 1.2 N / 10 mm. It may be less than or equal to, and may be 1.0 N / 10 mm or less. According to the structure having a low water peeling force A1, the load applied to the adherend at the time of water peeling can be reduced. The structure is also suitably carried out, for example, in an embodiment in which the water peeling force A1 is 0.75 N / 10 mm or less, 0.50 N / 10 mm or less, 0.25 N / 10 mm or less, or 0.15 N / 10 mm or less. obtain. The lower limit of the water peeling force A1 is not particularly limited, and may be substantially 0N / 10mm or more than 0N / 10mm.
From the viewpoint of reworkability and the like, in the measurement of the water peeling force A1, it is preferable that the pressure-sensitive adhesive layer can be peeled off from the intermediate layer without leaving the pressure-sensitive adhesive on the intermediate layer. That is, it is preferable that the pressure-sensitive adhesive layer is excellent in non-adhesive residue in peeling from the intermediate layer. The presence or absence of the adhesive remaining on the intermediate layer can be grasped, for example, by visually observing the intermediate layer after the adhesive layer is peeled off.
The water peeling force A1 is specifically measured by the method described in Examples described later.

(Rate of decrease in peeling force after immersion in water)
The structure disclosed herein can be easily peeled off using an aqueous liquid such as water as described above, and the structure is immersed in water for 30 minutes and then pulled out of the water to wipe off the adhering water. After soaking in water, the peel strength A2 [N / 10 mm] measured under the same conditions as the measurement condition of the peel strength A0 is the formula:
Rate of decrease in peeling force after immersion in water [%] = (1- (A2 / A0)) × 100
It is preferable to satisfy the peeling force reduction rate of 30% or less after immersion in water. That is, the formula:
(1- (A2 / A0)) × 100 ≦ 30 [%]
It is preferable to satisfy; This formula means the following formula: A2 ≧ 0.7A0 ;. A pressure-sensitive adhesive that satisfies the above-mentioned rate of decrease in peeling force after immersion in water (30% or less) is excellent in water resistance and reliability. From the viewpoint of obtaining higher water resistance reliability, the rate of decrease in peeling force after immersion in water is preferably, for example, 20% or less, more preferably 10% or less, and may be 7% or less. The lower limit of the rate of decrease in peeling force after immersion in water is typically 0% or more. In the above structure, the difference between the rate of decrease in peeling force after water immersion [%] and the rate of decrease in peeling force after immersion in water [%] is, for example, 45% or more, 55% or more, 70% or more, or 80% or more, or It can be preferably carried out in an embodiment of 90% or more. The post-water immersion peel strength A2 for calculating the rate of decrease in the post-water immersion peeling force is measured by the method described in Examples described later.

In some embodiments, it is appropriate that the haze value of the structure (eg, the pressure-sensitive adhesive sheet before the adherends are laminated, preferably the double-sided pressure-sensitive adhesive sheet) is approximately 10% or less, and approximately 5% or less ( For example, it can be about 3% or less). The haze value is preferably 1.0% or less. Such a highly transparent structure is suitable for optical applications where high light transmission is required. The haze value of the structure may be less than 1.0%, less than 0.7%, or less than 0.5% (eg 0-0.5%). The range of haze values for the structure may also apply to the haze values of the pressure-sensitive adhesive layer and the intermediate layer in the techniques disclosed herein.

Here, the "haze value" refers to the ratio of diffuse transmitted light to total transmitted light when the measurement target is irradiated with visible light. Also called cloudy price. The haze value can be expressed by the following equation.
Th [%] = Td / Tt × 100
In the above formula, Th is a haze value [%], Td is a scattered light transmittance, and Tt is a total light transmittance.
The haze value can be measured using a haze meter (for example, "MR-100" manufactured by Murakami Color Technology Laboratory). The haze value can be adjusted by selecting, for example, the composition and thickness of the pressure-sensitive adhesive layer, the material of the intermediate layer, the thickness, and the like.

In the above structure, the pressure-sensitive adhesive constituting the A layer arranged on the hydrophilic surface side of the pressure-sensitive adhesive layer is preferably water-insoluble. According to the water-insoluble layer A, it is easy to obtain a structure having a high peeling strength A2 after immersion in water and a low rate of decrease in peeling force after immersion in water. The fact that the A layer is water-insoluble is also preferable from the viewpoint of preventing the phenomenon that the adhesive remains on the intermediate layer in peeling using an aqueous liquid such as water. Further, the fact that the A layer is water-insoluble may be advantageous from the viewpoint of preventing the phenomenon that the transparency of the structure is lowered due to water immersion or moisture in the environment. This can be an advantageous feature in an optical structure in which the adherend is an optical member.

The pressure-sensitive adhesive constituting the A layer is preferably non-water-swellable. According to the non-water-swellable layer A, it is easy to obtain a structure having a high peeling strength A2 after immersion in water and a low rate of decrease in peeling force after immersion in water. Further, in peeling using an aqueous liquid such as water, a small amount of the aqueous liquid can be effectively used to exhibit good peelability. The non-water swelling property of the A layer is also preferable from the viewpoint of preventing the phenomenon that the adhesive remains on the intermediate layer in the peeling using the aqueous liquid. Further, the fact that the layer A is non-water swelling may be advantageous from the viewpoint of preventing the phenomenon that the transparency of the structure is lowered due to water immersion or moisture in the environment. This can be an advantageous feature in an optical structure in which the adherend is an optical member.

Here, in the present specification, the adhesive is water-insoluble means that the gel fraction measured by the following method is 75% or more. Further, the non-water swelling property of the pressure-sensitive adhesive means that the swelling degree measured by the following method is 2 or less.
That is, about 0.5 g of the pressure-sensitive adhesive to be measured is weighed, and the weight thereof is defined as W1. This pressure-sensitive adhesive is immersed in 500 ml of distilled water at room temperature (about 23 ° C.) for 48 hours, then filtered through a nylon mesh, and the weight W2 of the pressure-sensitive adhesive containing water is measured. Then, the pressure-sensitive adhesive is dried at 130 ° C. for 5 hours, and the weight W3 of the non-volatile component is measured. The gel fraction and swelling degree are calculated by the following formulas.
Gel fraction [%] = (W3 / W1) x 100
Swelling degree = W2 / W1

In some embodiments, the gel fraction of layer A may be, for example, 80% or more, 90% or more, 95% or more, or 98% or more. The gel fraction of the A layer is 100% or less in principle. Further, in some embodiments, the degree of swelling of the layer A may be, for example, 1.7 or less, 1.5 or less, or 1.2 or less. The degree of swelling of the layer A is, for example, 1.0 or more, and typically more than 1.0.

In the structure in which the pressure-sensitive adhesive layer includes the A layer and the B layer arranged on the back surface side of the A layer, the gel fraction of the B layer is not particularly limited. In some embodiments, the gel fraction of the B layer is preferably equal to or greater than the gel fraction of the A layer and may be higher than the gel fraction of the A layer. The gel fraction of the B layer may be, for example, 90% or more, 95% or more, 98% or more, or 99% or more. The gel fraction of the B layer is 100% or less in principle. The gel fraction of the entire pressure-sensitive adhesive layer may be, for example, 85% or more, 90% or more, 95% or more, 98% or more, or 99% or more. In the pressure-sensitive adhesive layer consisting of only the A layer, the gel fraction of the entire pressure-sensitive adhesive layer means the gel fraction of the A layer.

In a structure in which the pressure-sensitive adhesive layer includes an A layer and a B layer arranged on the back surface side of the A layer, the degree of swelling of the B layer is not particularly limited. In some embodiments, the degree of swelling of the layer B is preferably equal to or less than the degree of swelling of the layer A, and may be lower than the degree of swelling of the layer A. The degree of swelling of the B layer may be, for example, 1.5 or less, 1.3 or less, or 1.1 or less. The degree of swelling of the B layer is, for example, 1.0 or more, and typically more than 1.0. The degree of swelling of the entire pressure-sensitive adhesive layer may be, for example, 1.6 or less, 1.4 or less, 1.2 or less, or 1.1 or less. In the pressure-sensitive adhesive layer consisting of only the A layer, the degree of swelling of the entire pressure-sensitive adhesive layer means the degree of swelling of the A layer.

The gel fraction and swelling degree of the pressure-sensitive adhesive with respect to water are general methods for those skilled in the art at the time of filing the application, such as composition of monomer components, weight average molecular weight of polymers, use of cross-linking agents and polyfunctional monomers. Can be adjusted by appropriately adopting.

<Middle layer>
The structure disclosed herein has an intermediate layer disposed between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The intermediate layer is characterized by having a hydrophilic surface on at least one surface. According to the configuration having an intermediate layer having a hydrophilic surface, the hydrophilic surface and the pressure-sensitive adhesive layer on the hydrophilic surface can be separated by water peeling. It is preferable that only one surface (one side) of the intermediate layer is a hydrophilic surface. Alternatively, both sides of the intermediate layer may be hydrophilic surfaces.

The water contact angle of the hydrophilic surface of the intermediate layer is limited to a predetermined value or less. As a result, water peelability is exhibited on the hydrophilic surface. In some embodiments, the water contact angle of the hydrophilic surface may be, for example, 45 degrees or less, 40 degrees or less, or 35 degrees or less. When the water contact angle of the hydrophilic surface becomes small, water tends to get wet and spread along the surface, and the water peelability of the pressure-sensitive adhesive layer from the intermediate layer tends to be improved. This is preferable from the viewpoint of removability from the intermediate layer of the pressure-sensitive adhesive layer and separability. In some preferred embodiments, the hydrophilic surface has a water contact angle of 30 degrees or less, less than 25 degrees is suitable, may be less than 20 degrees, may be less than 15 degrees, or may be less than 10 degrees. .. The lower limit of the water contact angle is 0 degrees in principle. In some embodiments, the water contact angle may be greater than 0 degrees, greater than 1 degree, greater than 3 degrees, or greater than or equal to 5 degrees. According to the technique disclosed herein, better water peelability can be achieved by selecting an intermediate layer material, a hydrophilic layer material, and an adhesive type. Therefore, in some embodiments, the water contact angle of the hydrophilic surface is achieved. May be 8 degrees or more, 12 degrees or more, 16 degrees or more, and 20 degrees or more (for example, 24 degrees or more). The water contact angle of the hydrophilic surface can be set by selecting the material constituting the intermediate layer or the hydrophilic layer, the thickness of the hydrophilic layer, the surface treatment, and the like. The water contact angle of the intermediate layer can be measured by the method described in Examples described later.

In an embodiment where only one surface of the intermediate layer is a hydrophilic surface and the other surface is not a hydrophilic surface, the water contact angle WCA1 of the hydrophilic surface, which is one surface of the intermediate layer, is typically the intermediate layer. It is smaller than the water contact angle WCA2 on the other surface of the. The WCA1 is preferably less than 70%, more preferably less than 50%, even more preferably less than 30%, and even less than 20% of the WCA2.

In an embodiment in which only one surface of the intermediate layer is a hydrophilic surface and the other surface is not a hydrophilic surface, the water contact angle of the other surface of the intermediate layer is not particularly limited, and is, for example, more than 30 degrees. The other surface of the intermediate layer may be a hydrophobic surface having a water contact angle of 40 degrees or more. The water contact angle of the hydrophobic surface may be 50 degrees or more (for example, more than 50 degrees) or 60 degrees or more (for example, 65 degrees or more). The upper limit of the water contact angle of the other surface of the intermediate layer is not particularly limited, and may be, for example, less than 115 degrees, may be less than 105 degrees, or may be less than 95 degrees.

Further, from the viewpoint of water peelability, it is preferable that the hydrophilic surface of the intermediate layer is formed smoothly. For example, the arithmetic mean roughness Ra of the hydrophilic surface is less than 10 μm. According to the hydrophilic surface in which the unevenness is suppressed as described above, it is easy to realize the desired water peelability. The arithmetic mean roughness Ra is preferably less than 5 μm, more preferably less than 3 μm (specifically less than 1.0 μm). Further, from the viewpoint of maintaining the water removability for a long period of time, it is preferable that the arithmetic mean roughness Ra of the hydrophilic surface is even smaller. For example, the arithmetic mean roughness Ra is preferably less than 100 nm, more preferably less than 10 nm, still more preferably less than 3 nm (specifically less than 1.0 nm). The smoothness of the hydrophilic surface can be adjusted by selecting and forming the intermediate layer material and the hydrophilic layer material, the thickness of the hydrophilic layer, and the like. In the present specification, the arithmetic mean roughness is defined as a general surface roughness measuring device (for example, a non-contact three-dimensional surface shape measuring device manufactured by Veco, model "Wyko NT-3300", or manufactured by Hitachi High Technologies. It can be measured using an atomic force microscope, model "AFM5500M").

(Hydrophilic layer)
In some preferred embodiments, the intermediate layer has a hydrophilic layer on at least one surface. In other words, the intermediate layer has a hydrophilic layer as a layer (outermost layer of the intermediate layer) constituting the surface on the pressure-sensitive adhesive layer side. Here, the hydrophilic layer is defined as a layer having a hydrophilic surface. By having the hydrophilic layer, good water peelability can be easily obtained regardless of the other intermediate layer material, the type of the pressure-sensitive adhesive laminated on the hydrophilic layer, and the like. As the range of the water contact angle value of the surface of the hydrophilic layer, the range of the water contact angle value of the hydrophilic surface can be adopted. Further, the range of the arithmetic average roughness Ra of the surface of the hydrophilic layer is not particularly limited, but the range of the arithmetic average roughness Ra of the hydrophilic surface can be adopted.

The material of the hydrophilic layer is not particularly limited, and one or more of various organic materials, inorganic materials, and organic-inorganic composite materials capable of forming a hydrophilic surface can be used. In some preferred embodiments, an inorganic material is used as the hydrophilic layer forming material. Since the hydrophilic layer contains an inorganic material, good water peelability can be easily obtained. As the inorganic material, a material capable of forming a hydrophilic surface from various metal materials including transition metal elements, simple substances of semi-metal elements, alloys, and inorganic compounds such as inorganic oxides is used. The above-mentioned inorganic materials may be used alone or in combination of two or more. Preferable examples of the inorganic material are oxides such as titanium oxide, zinc oxide, magnesium oxide, aluminum oxide, silicon oxide, cerium oxide, chromium oxide, zirconium oxide, manganese oxide, zinc oxide, iron oxide, tin oxide and niobium oxide. (Inorganic oxides, typically metal oxides). Among them, an inorganic oxide such as silicon oxide is used as a preferable inorganic material. In addition to the inorganic material, the hydrophilic layer may or may not contain various organic materials including an organic polymer compound that can be used as a coating agent or a binder.

The amount of the inorganic material (for example, an inorganic oxide such as silicon oxide) in the hydrophilic layer can be an appropriate amount to obtain the desired hydrophilic surface, and is not limited to a specific range. For example, the content ratio of the inorganic material in the hydrophilic layer can be about 30% by weight or more, about 50% by weight or more (for example, more than 50% by weight) is appropriate, and even if it is about 70% by weight or more. good. In some preferred embodiments, the content of the inorganic material in the hydrophilic layer is approximately 90-100% by weight (eg, approximately 95% by weight or more).

In some preferred embodiments, as the inorganic material, an inorganic oxide such as silicon oxide (typically silicon oxide represented by SiO _X or silicon dioxide represented by SiO ₂ ) is used. The ratio of the inorganic oxide (typically silicon oxide) to the above-mentioned inorganic material can be an appropriate amount to obtain the desired hydrophilic surface, and is not limited to a specific range, for example, by about 30 weight. % Or more, about 50% by weight or more (for example, more than 50% by weight) is suitable, and may be about 70% by weight or more. In some preferred embodiments, the proportion of the inorganic oxide (typically silicon oxide) in the inorganic material is approximately 90-100% by weight (eg, approximately 95% by weight or more).

The method for forming the hydrophilic layer is not particularly limited, and it can be formed by an appropriate method according to the target thickness and the like. For example, an inorganic material formed in layers by using a known film forming method such as a vacuum vapor deposition method, a sputtering method, or a plating method can be used as a hydrophilic layer. When an inorganic compound is used as the inorganic material, various vapor deposition methods can be used. For example, a physical vapor deposition method (PVD) such as a vacuum vapor deposition method, a sputtering method, or an ion plating method, an atomic layer deposition layer, or the like can be used. The chemical vapor deposition method (CVD) of the above can be adopted. The coating layer containing an inorganic polymer such as polysiloxane can be formed by appropriately selecting a known coating agent that can obtain a surface showing a desired water contact angle and using it by a conventional method.

In some other embodiments, an organic material is used as the hydrophilic layer forming material. As the organic material, one kind or two or more kinds of organic materials capable of forming a hydrophilic surface can be used. For example, a polymer having a hydrophilic functional group such as a sulfonic acid group, a phosphoric acid group, a carboxy group, and a silanol group can be used as a hydrophilic layer forming material. The hydrophilic layer forming material can be referred to as a hydrophilic treatment agent or a hydrophilic coating agent, and the hydrophilic layer can be formed by applying the hydrophilic treatment agent or the hydrophilic coating agent. Examples of the organic material for forming a hydrophilic layer include a polysiloxane-based coating agent (for example, a polysiloxane-type coating agent having an ethylsilicate skeleton), a polysilazane-based hydrophilic coating agent (for example, perhydroxypolysilazane), and a polymer brush-type hydrophilicity. Examples thereof include coating agents and other hydrophilic polymer-containing coating agents (for example, polyvinylpyrrolidone-based coating agents).

Commercially available products of the hydrophilizing treatment agent and the hydrophilic coating agent that can be used for forming the hydrophilic layer include, for example, product names "Colcoat N103X", "Colcoat CS3001" (manufactured by Colcoat), and product names "DURAZANE2800" (Merk). , Product name "LAMBIC 771W", "LAMBIC 1000W" (manufactured by Osaka Organic Chemical Industries, Ltd.), product name "Polypolypyrrolidone K90" (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and the like.

The method for forming the organic hydrophilic layer is not particularly limited, and for example, the surface of the main layer of the intermediate layer forming the hydrophilic layer may be subjected to surface treatment such as corona treatment, plasma treatment, ultraviolet treatment, or an appropriate primer, if necessary. The method of applying the above-mentioned hydrophilic layer forming material after applying the above-mentioned material can be adopted.

Further, in some other aspects, the intermediate layer may be composed of a hydrophilic layer having a single layer structure. The intermediate layer made of a hydrophilic layer has a hydrophilic surface on both sides thereof. The material for forming such a hydrophilic layer is not particularly limited, and one or more of various materials having a hydrophilic surface can be used. Examples thereof include a hydrophilic layer formed of glass such as an alkaline glass plate and non-alkali glass, a metal material such as iron, and a ceramic material such as silica. Such a hydrophilic layer is typically a layer made of an inorganic material. Of these, a hydrophilic layer made of a glass material such as an alkaline glass plate or non-alkali glass is preferable.

The thickness of the hydrophilic layer is not particularly limited. In the embodiment in which the hydrophilic layer is formed on the surface of the main layer, which will be described later, the thickness of the hydrophilic layer is specifically about 5 μm or less (specifically, from the viewpoint of not impairing the function of the main body of the intermediate layer (main layer of the intermediate layer). For example, less than 5000 nm) is suitable, and may be approximately 2 μm or less (for example, less than 2000 nm). In some preferred embodiments, the thickness of the hydrophilic layer is less than 1000 nm, more preferably less than 500 nm, even more preferably less than 100 nm, particularly preferably less than 50 nm, and may be about 30 nm or less, about 20 nm or less. However, it may be about 15 nm or less (for example, less than 10 nm). By forming such a thin hydrophilic layer, the water peelability can be improved without impairing the function of the intermediate layer. Having a thin hydrophilic layer is also advantageous from the viewpoint of optical characteristics. Further, the thickness of the hydrophilic layer is preferably 1 nm or more (for example, 3 nm or more), and may be about 5 nm or more, and may be about 10 nm or more (for example, from the viewpoint of improving the hydrophilicity of the surface and improving the water peelability). 15 nm or more) may be used. For a thin (for example, nano-order) hydrophilic layer, the thickness can be measured by the method described in Examples described later. Further, in the embodiment in which the intermediate layer is composed of a hydrophilic layer, the thickness of the hydrophilic layer is the same as the range of the thickness of the intermediate layer described later.

(Other layers)
In some embodiments, the intermediate layer may include other layers in addition to the hydrophilic layer. The other layers are not particularly limited and may be one layer or two or more layers formed of various materials. The other layer may be, for example, a layer constituting the main body of the intermediate layer. Such a layer is called the main layer of the middle layer. The main layer of the intermediate layer disclosed herein (also referred to as "intermediate layer main layer", or for convenience, may be simply referred to as "intermediate layer"; the same shall apply hereinafter unless otherwise specified) is not particularly limited. It can be appropriately selected according to the purpose of use, the mode of use, and the like. In some embodiments, the intermediate layer forms a hydrophilic layer on at least one surface of the main layer to reduce the water contact angle of the surface of the intermediate layer and obtain improved water exfoliation properties. Therefore, the water contact angle on the surface of the intermediate layer alone (main layer) without the hydrophilic layer is typically larger than the water contact angle on the surface of the hydrophilic layer. As the water contact angle on the surface of the main layer of the intermediate layer, a range of the water contact angle value of the other surface of the intermediate layer can be adopted.

Non-limiting examples of the materials of the other layers (typically the main layer) constituting the intermediate layer are various resin films such as polyolefin films, polyester films and polyvinyl chloride films; polyurethane foams, polyethylene foams and polys. Foam sheet made of foam such as chloroprene foam; various fibrous substances (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) alone or Woven fabrics and non-woven fabrics produced by blending and the like; papers such as Japanese paper, high-quality paper, kraft paper, and crepe paper; metal foils such as aluminum foil, copper foil, and stainless steel (SUS); and the like. It may be a layered body having a structure in which these are combined. Examples of the main layer of the intermediate layer having such a composite structure include, for example, a laminate having a structure in which a metal foil and the above resin film are laminated (multilayer structure intermediate layer), a resin sheet reinforced with an inorganic fiber such as glass cloth, and the like. Can be mentioned.

Various films can be preferably used as the material of the other layer (typically the main layer) constituting the intermediate layer. The film may be a porous film such as a foam film or a non-woven fabric sheet, or may be a non-porous film, and has a structure in which a porous layer and a non-porous layer are laminated. It may be a film of. In some embodiments, as the film, a film containing an independently shape-maintainable (self-supporting or independent) resin film as a base film can be preferably used. As used herein, the term "resin film" means a resin film (of voidless) having a non-porous structure and typically containing substantially no bubbles. Therefore, the resin film is a concept that is distinguished from foam films and non-woven fabrics. The resin film may have a single-layer structure or a multi-layer structure having two or more layers (for example, a three-layer structure).

Examples of the resin material constituting the resin film include polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyolefins such as polypropylene and ethylene-propylene copolymers; and aliphatic ring structures such as norbornene structure. Polycycloolefin derived from monomer; Polyamide (PA) such as nylon 6, nylon 66, and partially aromatic polyamide; Polyamide (PI) such as transparent polyimide (CPI), Polyamideimide (PAI); Polyether ether ketone (PEEK) Polyether sulfone (PES); Polyphenylene sulfide (PPS); Polycarbonate (PC); Polyurethane (PU); Ethylene-vinyl acetate copolymer (EVA); Polyvinyl alcohol (PVA); Polystyrene; ABS resin; Polyvinyl chloride; Polyvinylidene chloride; Fluorine resin such as polytetrafluoroethylene (PTFE); Acrylic resin such as polymethylmethacrylate; Cellulous polymer such as diacetylcellulose and triacetylcellulose (TAC); Vinylbutyral polymer; Arilate polymer; Polyoxy Methylene-based polymer; A resin such as an epoxy-based polymer can be used. The surface of the main layer of the intermediate layer disclosed herein may be composed of the above resin material. The resin film that can be used as the main layer of the intermediate layer may be formed by using a resin material containing one kind of the above resin alone, or is formed by using a resin material in which two or more kinds are blended. It may be a plastic one. The resin film is a composite resin film in which a resin layer containing one or more kinds of resin materials and a resin layer containing one or more kinds of resin materials of the same type or different types from the resin layer are laminated. There may be. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Preferable examples of the resin material constituting the resin film include polyester resin, PPS resin, polyolefin resin, and polyimide resin. Here, the polyester-based resin refers to a resin containing polyester in a proportion of more than 50% by weight. Similarly, the PPS resin is a resin containing PPS in a proportion of more than 50% by weight, the polyolefin resin is a resin containing a polyolefin in a proportion of more than 50% by weight, and the polyimide resin is a polyimide resin. A resin containing polyimide in a proportion of more than 50% by weight.

As the polyester-based resin, a polyester-based resin containing polyester as a main component, which is obtained by polycondensing a dicarboxylic acid and a diol, is typically used. Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate and the like.

As the polyolefin resin, one kind of polyolefin can be used alone, or two or more kinds of polyolefins can be used in combination. The polyolefin can be, for example, a homopolymer of an α-olefin, a copolymer of two or more kinds of α-olefins, or a copolymer of one kind or two or more kinds of α-olefins and another vinyl monomer. Specific examples include ethylene-propylene copolymers such as polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene propylene rubber (EPR), and ethylene-propylene-. Examples thereof include a butene copolymer, an ethylene-butene copolymer, an ethylene-vinyl alcohol copolymer, and an ethylene-ethyl acrylate copolymer. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, medium density polyethylene (MDPE). Examples thereof include a film, a high-density polyethylene (HDPE) film, a polyethylene (PE) film in which two or more types of polyethylene (PE) are blended, and a PP / PE blend film in which polypropylene (PP) and polyethylene (PE) are blended.

Specific examples of the resin film that can be preferably used as the main layer of the intermediate layer include PET film, PEN film, PPS film, PEEK film, CPI film, CPP film, OPP film, and TAC film. Preferred examples from the viewpoint of strength include PET film, PEN film, PPS film, PEEK film, and CPI film. Preferred examples include PET film, CPI film, and TAC film from the viewpoint of availability, dimensional stability, optical characteristics, and the like.

Known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dye, pigment, etc.), fillers, slip agents, antiblocking agents, etc. shall be added to the resin film, if necessary. Can be done. The blending amount of the additive is not particularly limited, and can be appropriately set according to the intended use and the like.

The method for manufacturing the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be appropriately adopted.

The other layer (typically, the main layer of the intermediate layer) may be substantially composed of such a resin film. Alternatively, the other layer may include an auxiliary layer in addition to the resin film. Examples of the auxiliary layer include an optical property adjusting layer (for example, a colored layer and an antireflection layer), a surface such as a printing layer or a laminating layer for imparting a desired appearance, an antistatic layer, an undercoat layer, and a peeling layer. A processing layer may be mentioned.

In addition, other layers (for example, the main layer) of the intermediate layer disclosed herein are acrylic, polyester, alkyd, melamine, urethane, acid-epoxy crosslinked, or the above resin film, metal foil, or the like. It may be coated with a paint such as these composite systems (for example, acrylic melamine system, alkyd melamine system), or plated with zinc plating or the like.

Although not particularly limited, the other layers (typically the main layer) of the intermediate layer disclosed herein do not typically include a glass layer such as an alkaline glass plate or non-alkali glass. In an embodiment using such an intermediate layer material, the effect of improving water peelability by providing the hydrophilic layer can be preferably exhibited.

In an embodiment in which the intermediate layer has another layer (typically, a main layer), the thickness of the other layer (in the case of having a plurality of layers other than the hydrophilic layer, the total thickness of the layers other than the hydrophilic layer) is determined. It is appropriate that the total thickness of the intermediate layer is 50% or more, preferably 70% or more, more preferably 90% or more, and 97% or more (for example, 99% or more).

The total thickness of the intermediate layer is not particularly limited and can be selected according to the purpose of use and the mode of use of the structure. The total thickness of the intermediate layer may be, for example, about 1000 μm or less, may be about 500 μm or less, and from the viewpoint of weight reduction and thinning, about 300 μm or less is suitable, preferably about 150 μm or less, and more preferably about 120 μm. It may be 100 μm or less, or 70 μm or less. As the total thickness of the intermediate layer becomes smaller, the flexibility of the structure and the followability to the surface shape of the adherend tend to improve. Further, from the viewpoint of handleability, workability and the like, the total thickness of the intermediate layer may be, for example, 2 μm or more, and may be more than 5 μm or more than 10 μm. In some embodiments, the total thickness of the intermediate layer is preferably about 20 μm or more, preferably about 30 μm or more, for example, about 50 μm or more, or about 70 μm or more.

The surface of the intermediate layer (eg, a hydrophilic surface, and thus the surface of the hydrophilic layer) may be further subjected to a hydrophilic treatment such as a corona treatment or a plasma treatment in order to further increase the hydrophilicity. .. The apparatus and treatment conditions used for the corona treatment and the plasma treatment can be set so as to obtain a surface showing a desired water contact angle based on conventionally known techniques. Further, the surface of the intermediate layer on the adhesive layer side may be subjected to conventionally known surface treatments such as ultraviolet irradiation treatment, acid treatment, and alkali treatment, if necessary. Such a surface treatment may be a treatment for improving the adhesion between the intermediate layer and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer to the intermediate layer. Further, the surface of the main layer of the intermediate layer (for example, the surface on the hydrophilic layer side) may be subjected to surface treatments such as the above-mentioned various surface treatments, application of an undercoating agent (primer), and antistatic treatment. The composition of the primer is not particularly limited and can be appropriately selected from known ones. The thickness of the undercoat layer is not particularly limited, but for example, about 0.01 μm to 1 μm is appropriate, and about 0.1 μm to 1 μm is preferable.

<Adhesive layer>
(1) Layer A In the structure disclosed here, the layer A contained in at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is, for example, an acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive ( Natural rubber-based, synthetic rubber-based, mixed systems, etc.), silicone-based adhesives, polyester-based adhesives, urethane-based adhesives, polyether-based adhesives, polyamide-based adhesives, fluorine-based adhesives, and other various adhesives. It may be a pressure-sensitive adhesive layer composed of one type or two or more types of pressure-sensitive adhesive selected from the above. Here, the acrylic pressure-sensitive adhesive refers to a pressure-sensitive adhesive containing an acrylic polymer as a main component. The same meaning applies to rubber-based pressure-sensitive adhesives and other pressure-sensitive adhesives.

(Acrylic adhesive)
From the viewpoint of transparency, weather resistance, and the like, an acrylic pressure-sensitive adhesive may be preferably adopted as the constituent material of the A layer in some embodiments.

The acrylic pressure-sensitive adhesive is composed of, for example, a monomer component containing more than 50% by weight of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms at the ester terminal. Those containing an acrylic polymer are preferable. Hereinafter, a (meth) acrylic acid alkyl ester having an alkyl group having an number of carbon atoms of X or more and Y or less at the ester terminal may be referred to as “(meth) acrylic acid _CXY alkyl ester”. Since it is easy to balance the characteristics, the proportion of (meth) acrylic acid C _1-20 alkyl ester in the entire monomer component may be, for example, 55% by weight or more, 60% by weight or more, or 70% by weight or more. But it may be. For the same reason, the proportion of (meth) acrylic acid C _1-20 alkyl ester in the monomer component may be, for example, 99.9% by weight or less, 99.5% by weight or less, or 99% by weight or less. good.

Non-limiting specific examples of the (meth) acrylic acid C _1-20 alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, (meth). N-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) Hexyl acrylate, (meth) heptyl acrylate, (meth) octyl acrylate, (meth) 2-ethylhexyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, (meth) ) Decyl acrylate, (meth) isodecyl acrylate, (meth) undecyl acrylate, (meth) dodecyl acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, (meth) Examples thereof include hexadecyl acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecil (meth) acrylate, and eicocil (meth) acrylate.

Of these, it is preferable to use at least (meth) acrylic acid C _4-20 alkyl ester, and it is more preferable to use at least (meth) acrylic acid C _4-18 alkyl ester. For example, an acrylic pressure-sensitive adhesive containing one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) as the monomer component is preferable, and an acrylic pressure-sensitive adhesive containing at least 2 EHA is particularly preferable. Other examples of (meth) acrylic acid C _4-20 alkyl esters that may be preferably used include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (ISTA). ) Etc. can be mentioned.

In some embodiments, the monomer component constituting the acrylic polymer may contain (meth) acrylic acid C _4-18 alkyl ester in a proportion of 40% by weight or more. As described above, the monomer component containing a relatively large amount of (meth) acrylic acid alkyl ester having an alkyl group having 4 or more carbon atoms at the ester terminal tends to form an acrylic polymer having high lipophilicity. According to the acrylic polymer having high lipophilicity, a pressure-sensitive adhesive layer having a low rate of decrease in peeling force after immersion in water is likely to be formed. The ratio of the (meth) acrylic acid C _4-18 alkyl ester to the monomer component may be, for example, 60% by weight or more, 70% by weight or more, 75% by weight or more, or 80% by weight or more. It may be a monomer component containing (meth) acrylic acid C _6-18 alkyl ester at a rate equal to or higher than any of the above-mentioned lower limit values.
Further, from the viewpoint of enhancing the cohesiveness of the pressure-sensitive adhesive layer (A layer) and preventing cohesive failure, the ratio of (meth) acrylic acid C _4-18 alkyl ester to the monomer component is 99.5% by weight or less. It may be 99% by weight or less, 98% by weight or less, or 97% by weight or less. From the viewpoint of improving the cohesiveness of the pressure-sensitive adhesive layer (A layer), in some embodiments, the ratio of the (meth) acrylic acid C _4-18 alkyl ester to the monomer component is 95% by weight or less, for example, 90% by weight. % Or less is appropriate. In some other embodiments, the proportion of (meth) acrylic acid C _4-18 alkyl ester in the monomer component may be 85% by weight or less, or 75% by weight or less. It may be a monomer component containing (meth) acrylic acid C _6-18 alkyl ester at a ratio equal to or less than any of the above-mentioned upper limit values.

The monomer component constituting the acrylic polymer contains a (meth) acrylic acid alkyl ester and, if necessary, another monomer (copolymerizable monomer) copolymerizable with the (meth) acrylic acid alkyl ester. May be good. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxy group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be preferably used. Monomers having polar groups can be useful for introducing cross-linking points in acrylic polymers and enhancing the cohesive force of adhesives. The copolymerizable monomer may be used alone or in combination of two or more.

Non-limiting specific examples of the copolymerizable monomer include the following.
Carboxy group-containing monomers: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.
Acid anhydride group-containing monomer: For example, maleic anhydride, itaconic anhydride.
Hydroxyl-containing monomers: For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic. 4-Hydroxybutyl acid, 6-hydroxyhexyl (meth) acrylic acid, 8-hydroxyoctyl (meth) acrylic acid, 10-hydroxydecyl (meth) acrylic acid, 12-hydroxylauryl (meth) acrylic acid, (4-hydroxy) (Methylcyclohexyl) Methyl (meth) acrylate and the like (meth) hydroxyalkyl acrylate and the like.
Monomer containing a sulfonic acid group or a phosphate group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfo. Propyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc.
Epoxide group-containing monomer: For example, epoxy group-containing acrylate such as (meth) glycidyl acrylate and (meth) -2-ethyl glycidyl ether, allyl glycidyl ether, glycidyl ether (meth) acrylate and the like.
Cyano group-containing monomer: For example, acrylonitrile, methacrylonitrile, etc.
Isocyanate group-containing monomer: For example, 2-isocyanatoethyl (meth) acrylate and the like.
Amid group-containing monomers: For example, (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth). N, N-dialkyl (meth) acrylamide, such as acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide; N-ethyl (meth) N-alkyl (meth) acrylamide such as acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide; N-vinylcarboxylic acid amide such as N-vinylacetamide. Kind; Monomer having a hydroxyl group and an amide group, for example, N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth). Acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) ( N-hydroxyalkyl (meth) acrylamide, such as meta) acrylamide; monomers with an alkoxy group and an amide group, such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl ( N-alkoxyalkyl (meth) acrylamide such as meta) acrylamide; and N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholin and the like.
Amino group-containing monomer: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.
Monomers having an epoxy group: for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloylpyrrolidin, N-vinylmorpholin, N-vinyl-3. -Morholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinyl Thiasol, N-vinylisothiazole, N-vinylpyridazine and the like (eg, lactams such as N-vinyl-2-caprolactam).
Monomers having a succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide and the like.
Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.
Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl. Itaconimide, etc.
Aminoalkyl (meth) acrylates: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t (meth) acrylate. -Butyl aminoethyl.
Alkoxy group-containing monomers: for example, 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, (meth) acrylate. Alkoxyalkyls (meth) acrylates such as butoxyethyl, ethoxypropyl (meth) acrylates; alkoxyalkylene glycols (meth) acrylates such as methoxyethylene glycol (meth) acrylates, methoxypolypropylene glycols (meth) acrylates, etc. Kind.
Alkoxysilyl group-containing monomers: for example 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxy Propylmethyldiethoxysilane.
Vinyl esters: For example, vinyl acetate, vinyl propionate and the like.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene and the like.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene and the like.
(Meta) acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate and the like. ..
(Meta) acrylic acid ester having an aromatic hydrocarbon group: For example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate and the like.
In addition, heterocyclic-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride and fluorine atom-containing (meth) acrylates, and silicon atom-containing silicone (meth) acrylates. (Meta) acrylate, (meth) acrylic acid ester obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is appropriate to use 0.01% by weight or more of the total monomer component. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more of the entire monomer component, or 0.5% by weight or more. Further, from the viewpoint of facilitating the balance of the adhesive properties, the amount of the copolymerizable monomer used is preferably 50% by weight or less, preferably 40% by weight or less of the entire monomer component.

In some embodiments, the monomer component constituting the acrylic polymer may contain a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force of the pressure-sensitive adhesive and the degree of cross-linking (for example, cross-linking with an isocyanate cross-linking agent) can be suitably adjusted, and the peel strength A0 can be improved. As the hydroxyl group-containing monomer, those exemplified above can be used, and for example, 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4HBA) can be preferably adopted. The hydroxyl group-containing monomer may be used alone or in combination of two or more.

When a hydroxyl group-containing monomer is used, the amount used is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more of the entire monomer component. It may be 1% by weight or more, 5% by weight or more, or 10% by weight or more. In some embodiments, the amount of the hydroxyl group-containing monomer used is 15% by weight or more, preferably 20% by weight or more, preferably 25% by weight or more, and 30% by weight or more, based on the total amount of the monomer components. It may be 35% by weight or more, or 40% by weight or more. By using the hydroxyl group-containing monomer in the above range, it is possible to preferably obtain a pressure-sensitive adhesive layer in which the peeling strength and the rate of decrease in water peeling power are well-balanced. Further, from the viewpoint of suppressing the water absorption of the pressure-sensitive adhesive layer, it is appropriate that the amount of the hydroxyl group-containing monomer used is, for example, 50% by weight or less (for example, 45% by weight or less) of the entire monomer component in some embodiments. Yes, it may be 30% by weight or less, 25% by weight or less, 20% by weight or less, 10% by weight or less, or 5% by weight or less.

In some embodiments, the monomer component constituting the acrylic polymer may include a monomer having a nitrogen atom. By using a monomer having a nitrogen atom, the cohesive force of the pressure-sensitive adhesive can be enhanced, and the peel strength after photocuring can be preferably improved. A preferred example of a monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used, and for example, the general formula (1):

The N-vinyl cyclic amide represented by is used. Here, in the general formula (1), R ¹ is a divalent organic group, specifically − (CH ₂ ) _n −. n is an integer of 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably adopted. Another preferred example of a monomer having a nitrogen atom is (meth) acrylamide.

The amount of the monomer having a nitrogen atom (preferably the monomer having a nitrogen atom-containing ring) is not particularly limited, and may be, for example, 1% by weight or more or 3% by weight or more of the entire monomer component. Further, it can be 5% by weight or more or 7% by weight or more. In some embodiments, the amount of the monomer having a nitrogen atom used may be 10% by weight or more, 15% by weight or more, or 20% by weight, based on the total amount of the monomer components, from the viewpoint of improving the adhesive strength. It may be the above. Further, the amount of the monomer having a nitrogen atom is appropriately set to, for example, 40% by weight or less of the total monomer component, 35% by weight or less, 30% by weight or less, or 25% by weight or less. May be good. In some other embodiments, the amount of the monomer having a nitrogen atom used may be, for example, 20% by weight or less of the total monomer component, or 15% by weight or less. In some other embodiments, the amount of the monomer having a nitrogen atom used may be, for example, 20% by weight or less, 12% by weight or less, 8% by weight or less, or 6% by weight or less of the total monomer component. But it may be.

In some embodiments, the monomer component comprises a carboxy group-containing monomer. Preferable examples of the carboxy group-containing monomer include acrylic acid (AA) and methacrylic acid (MAA). AA and MAA may be used in combination. When AA and MAA are used in combination, their weight ratio (AA / MAA) is not particularly limited, and can be, for example, in the range of about 0.1 to 10. In some embodiments, the weight ratio (AA / MAA) may be, for example, approximately 0.3 or more, and may be approximately 0.5 or more. Further, the weight ratio (AA / MAA) may be, for example, about 4 or less, or about 3 or less.

By using a carboxy group-containing monomer, an aqueous liquid such as water can be quickly blended into the surface of the A layer. This may help reduce the water peeling force A1. The amount of the carboxy group-containing monomer used may be, for example, 0.05% by weight or more of the entire monomer component, 0.1% by weight or more, 0.3% by weight or more, and 0.5% by weight or more. However, it may be 0.8% by weight or more. The ratio of the carboxy group-containing monomer may be, for example, 15% by weight or less, 10% by weight or less, 5% by weight or less, 4.5% by weight or less, and 3.5% by weight or less. However, it may be 3.0% by weight or less, or 2.5% by weight or less. It is preferable that the amount of the carboxy group-containing monomer used is not too large from the viewpoint of suppressing the diffusion of water into the bulk of the A layer and suppressing the decrease in the peel strength A2 after immersion in water. Further, the fact that the amount of the carboxy group-containing monomer used is not too large may be advantageous from the viewpoint of preventing the event that the water used for measuring the water peeling force A1 is absorbed by the A layer and the water is insufficient during the peeling. ..

In some embodiments, the monomer component may include an alkoxysilyl group-containing monomer. The alkoxysilyl group-containing monomer is typically an ethylenically unsaturated monomer having at least one (preferably two or more, for example two or three) alkoxysilyl groups in one molecule. Specific examples are as described above. The above-mentioned alkoxysilyl group-containing monomer may be used alone or in combination of two or more. By using the alkoxysilyl group-containing monomer, a crosslinked structure by a silanol group condensation reaction (silanol condensation) can be introduced into the pressure-sensitive adhesive layer (layer A). The alkoxysilyl group-containing monomer can also be grasped as a silane coupling agent described later.

In the embodiment in which the monomer component contains an alkoxysilyl group-containing monomer, the ratio of the alkoxysilyl group-containing monomer to the entire monomer component can be, for example, 0.005% by weight or more, and 0.01% by weight or more. Is appropriate. Further, the ratio of the alkoxysilyl group-containing monomer may be, for example, 0.5% by weight or less, 0.1% by weight or less, or 0.05% by weight or less from the viewpoint of improving the adhesion to the adherend. But it may be.

Further, in the monomer component of the acrylic polymer according to some preferred embodiments, the total ratio of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate is limited to less than 20% by weight from the viewpoint of suppressing gelation. Has been done. The total proportion of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate is more preferably less than 10% by weight, still more preferably less than 3% by weight, particularly preferably less than 1% by weight, and some In aspects, the monomer component is substantially free of alkoxyalkyl (meth) acrylates and alkoxypolyalkylene glycol (meth) acrylates (content 0-0.3% by weight).
Similarly, the monomer component of the acrylic polymer disclosed herein may or may not contain an alkoxy group-containing monomer in a proportion of less than 20% by weight. The amount of the alkoxy group-containing monomer in the monomer component is preferably less than 10% by weight, more preferably less than 3% by weight, still more preferably less than 1% by weight, and in a particularly preferable embodiment, the monomer component contains an alkoxy group. Substantially free of monomers (content 0-0.3% by weight).

Further, in some preferred embodiments, the proportion of the hydrophilic monomer in the monomer component of the acrylic polymer is set in an appropriate range. As a result, water peelability is preferably exhibited. Here, the "hydrophilic monomer" in the present specification contains an amide group such as a carboxy group-containing monomer, an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, and a monomer having a nitrogen atom (typically, (meth) acrylamide). It refers to a monomer, a monomer having a nitrogen atom-containing ring such as N-vinyl-2-pyrrolidone) and an alkoxy group-containing monomer (typically, an alkoxyalkyl (meth) acrylate and an alkoxypolyalkylene glycol (meth) acrylate). do. In this embodiment, the proportion of the hydrophilic monomer in the monomer component of the acrylic polymer is preferably 40% by weight or less (for example, 35% by weight or less), preferably 32% by weight or less, and for example, 30% by weight. It may be less than or equal to 28% by weight or less. Although not particularly limited, the proportion of the hydrophilic monomer in the monomer component of the acrylic polymer may be 1% by weight or more, 10% by weight or more, or 20% by weight or more. There may be.

In some embodiments, the monomer component constituting the acrylic polymer may contain an alicyclic hydrocarbon group-containing (meth) acrylate. This makes it possible to increase the cohesive force of the pressure-sensitive adhesive and improve the peel strength. As the alicyclic hydrocarbon group-containing (meth) acrylate, those exemplified above can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably adopted. When the alicyclic hydrocarbon group-containing (meth) acrylate is used, the amount used is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the entire monomer component. In some embodiments, the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used may be 10% by weight or more, or 15% by weight or more, based on the total amount of the monomer components. It is appropriate that the upper limit of the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used is approximately 40% by weight or less, for example, 30% by weight or less, and 25% by weight or less (for example, 15% by weight). % Or less, and even 10% by weight or less).

The composition of the monomer component is such that the glass transition temperature (hereinafter, also referred to as “glass transition temperature of the polymer”) determined by the Fox formula based on the composition of the monomer component is −75 ° C. or higher and −10 ° C. or lower. Can be set to. In some embodiments, the glass transition temperature (Tg) of the polymer (eg, acrylic polymers, typically acrylic polymers) is preferably −20 ° C. or lower, preferably −30 ° C. or lower. It is preferably -40 ° C or lower, more preferably -50 ° C or lower, and may be, for example, −55 ° C or lower. When the Tg of the polymer is low, the adhesion of the A layer to the intermediate layer and the adhesiveness to the adherend generally tend to be improved. According to the layer A having high adhesion to the intermediate layer, it is easy to suppress water infiltration into the interface between the intermediate layer and the layer A when the pressure-sensitive adhesive layer is not intended to be peeled off. This can be advantageous from the viewpoint of improving the peeling strength A2 after immersion in water and reducing the rate of decrease in peeling force after immersion in water. Further, the Tg of the polymer may be, for example, −70 ° C. or higher, or −65 ° C. or higher, from the viewpoint of facilitating the increase in the peel strength A0. In some other embodiments, the Tg may be, for example, −60 ° C. or higher, −50 ° C. or higher, −45 ° C. or higher, or −40 ° C. or higher.

Here, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below. ..
1 / Tg = Σ (Wi / Tgi)
In the above Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer.

As the glass transition temperature of the homopolymer used for calculating Tg, the value described in the publicly known material shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomer.
2-Ethylhexyl acrylate -70 ° C
n-Butyl acrylate -55 ° C
Isostearyl acrylate -18 ° C
Methyl methacrylate 105 ° C
Methyl acrylate 8 ℃
Cyclohexyl acrylate 15 ° C
N-vinyl-2-pyrrolidone 54 ° C
2-Hydroxyethyl acrylate -15 ° C
4-Hydroxybutyl acrylate -40 ° C
Dicyclopentanyl methacrylate 175 ° C
Isobornyl acrylate 94 ° C
Acrylic acid 106 ℃
Methacrylic acid 228 ° C

For the glass transition temperature of homopolymers of monomers other than those exemplified above, the numerical values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple types of values are described in this document, the highest value is adopted.

For monomers for which the glass transition temperature of homopolymer is not described in the above Polymer Handbook, the values obtained by the following measurement methods shall be used (see Japanese Patent Application Publication No. 2007-51271). Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 100 parts by weight of a monomer, 0.2 part by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent are added. Add and stir for 1 hour while circulating nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by weight. Next, this homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to shear strain at a frequency of 1 Hz using a viscoelasticity tester (ARES, manufactured by Leometrics) in a temperature range of −70 to 150 ° C. The viscoelasticity is measured in a shear mode at a heating rate of 5 ° C./min, and the peak top temperature of tan δ is defined as Tg of the homopolymer.

The polymer (for example, an acrylic polymer, typically an acrylic polymer) contained in the pressure-sensitive adhesive layer (layer A) disclosed herein is not particularly limited, but has an SP value of 23.0 (). MJ / m ³ ) It is preferably ^1/2 or less. The pressure-sensitive adhesive containing a polymer having such an SP value preferably contains, for example, a water-affinitive agent described later, thereby preferably realizing a pressure-sensitive adhesive having sufficient adhesive strength and excellent water peelability. Can be. The SP value is more preferably 21.0 (MJ / m ³ ) ^1/2 or less (for example, 20.0 (MJ / m ³ ) ^1/2 or less). The lower limit of the SP value is not particularly limited, and it is appropriate that it is, for example, about 10.0 (MJ / m ³ ) ^1/2 or more, and about 15.0 (MJ / m ³ ) ^1/2 or more. Yes, preferably 18.0 (MJ / m ³ ) ^1/2 or more.

For the SP value of the above-mentioned polymer, refer to the Fedors calculation method ["Polymer Engineering and Science (POLYMER ENG. &SCI.)", Vol. 14, No. 2 (1974), pp. 148-154. ] That is, the formula:
SP value δ = (Σ △ e / Σ △ v) ^1/2
(In the above equation, Δe is the evaporation energy Δe of each atom or atomic group at 25 ° C., and Δv is the molar volume of each atom or atomic group at the same temperature.);
Can be calculated according to. The polymer having the above SP value can be obtained by appropriately determining the monomer composition based on the common general technical knowledge of those skilled in the art.

The pressure-sensitive adhesive layer (layer A) contains a monomer component having the above-mentioned composition in the form of a polymer, a non-polymer (that is, a form in which a polymerizable functional group is unreacted), or a mixture thereof. It can be formed using a composition (hereinafter, also referred to as "adhesive composition A"). The pressure-sensitive adhesive composition A is a water-dispersible pressure-sensitive adhesive composition in which a pressure-sensitive adhesive (adhesive component) is dispersed in water, a solvent-type pressure-sensitive adhesive composition in which the pressure-sensitive adhesive is contained in an organic solvent, ultraviolet rays, radiation, and the like. An active energy ray-curable adhesive composition prepared to be cured by the active energy rays of the above to form an adhesive, a hot melt type adhesive that is applied in a heat-melted state and forms an adhesive when cooled to near room temperature. It can be in various forms such as an agent composition.

In the polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator may be used depending on the polymerization method, polymerization mode and the like. Such a polymerization initiator may be used alone or in combination of two or more.

The thermal polymerization initiator is not particularly limited, but is, for example, an azo-based polymerization initiator, a peroxide-based initiator, a redox-based initiator by a combination of a peroxide and a reducing agent, and a substituted ethane-based initiator. Etc. can be used. More specifically, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (2-amidinopropane) dihydrochloride. , 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutyramidin), 2,2' -Azobis [N- (2-carboxyethyl) -2-methylpropionamidine] Azo-based initiators such as hydrate; persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxides and t-butyl hydroperoxides. , Peroxide-based initiators such as hydrogen peroxide; for example, substituted ethane-based initiators such as phenyl-substituted ethane; for example, redox such as a combination of persulfate and sodium hydrogen sulfite, a combination of peroxide and sodium ascorbate, etc. System initiators; and the like are exemplified, but not limited thereto. The thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100 ° C. (typically 40 to 80 ° C.).

The photopolymerization initiator is not particularly limited, but is, for example, a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, α-. Ketol-based photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, thioxanthone-based light A polymerization initiator or the like can be used.

The amount of such a thermal polymerization initiator or photopolymerization initiator used can be a normal amount depending on the polymerization method, polymerization mode, etc., and is not particularly limited. For example, about 0.001 to 5 parts by weight of the polymerization initiator (typically about 0.01 to 2 parts by weight, for example, about 0.01 to 1 part by weight) is used with respect to 100 parts by weight of the monomer to be polymerized. Can be done.

For the above polymerization, various conventionally known chain transfer agents (which can also be grasped as a molecular weight adjusting agent or a degree of polymerization adjusting agent) can be used, if necessary. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and thioglycolic acid can be used. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of the non-sulfur chain transfer agent include anilins such as N, N-dimethylaniline and N, N-diethylaniline; terpenoids such as α-pinene and turpinolene; α-methylstyrene and α-methylstyrene dimer. Stylines such as; compounds having a benzidenyl group such as dibenzylidene acetone, cinnamyl alcohol, cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; 2,3-dimethyl-2-butene , 1,5-Cyclooctadiene and other olefins; alcohols such as phenol, benzyl alcohol and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like.
The chain transfer agent may be used alone or in combination of two or more. When a chain transfer agent is used, the amount used may be, for example, about 0.01 to 1 part by weight with respect to 100 parts by weight of the monomer component. The techniques disclosed herein may also be preferably practiced in embodiments that do not use chain transfer agents.

The molecular weight of the polymer obtained by appropriately adopting the above-mentioned various polymerization methods (for example, an acrylic polymer, typically an acrylic polymer) is not particularly limited and can be set in an appropriate range according to the required performance and the like. .. It is appropriate that the weight average molecular weight (Mw) of the above-mentioned polymer is about 10 × 10 ⁴ or more, for example, about 15 × ¹⁰⁴ or more, and a viewpoint of achieving both cohesive force and adhesive force in a well-balanced manner. Therefore, it is preferably more than 30 × 10 ⁴ . The above-mentioned polymer according to some embodiments is preferably 40 × 10 ⁴ or more (typically about 50 × 10 ⁴ or more, for example, about 55 × 10) from the viewpoint of obtaining good adhesion reliability even in a high temperature environment. It has Mw of ⁴ or more). The upper limit of Mw of the polymer may be approximately 500 × 10 ⁴ or less (for example, approximately 150 × ¹⁰⁴ or less). The above Mw may be approximately 75 × ¹⁰⁴ or less. Here, Mw means a value in terms of standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, the model name “HLC-8320GPC” (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) may be used. The same applies to the examples described later.

The pressure-sensitive adhesive layer according to some aspects has an A layer formed from the water-dispersible pressure-sensitive adhesive composition. A typical example of the water-dispersed pressure-sensitive adhesive composition is an emulsion-type pressure-sensitive adhesive composition. Emulsion-type pressure-sensitive adhesive compositions typically contain a polymer of monomeric components and, optionally, additives.

Emulsion polymerization of monomer components is usually performed in the presence of an emulsifier. The emulsifier for emulsion polymerization is not particularly limited, and known anionic emulsifiers, nonionic emulsifiers and the like can be used. The emulsifier may be used alone or in combination of two or more.

Non-limiting examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy. Examples thereof include sodium ethylenealkylphenyl ether sulfate and sodium polyoxyethylene alkyl sulfosuccinate. Non-limiting examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene polyoxypropylene block polymers and the like. An emulsifier having a reactive functional group (reactive emulsifier) may be used. Examples of the reactive emulsifier include a radically polymerizable emulsifier having a structure in which a radically polymerizable functional group such as a propenyl group or an allyl ether group is introduced into the above-mentioned anionic emulsifier or nonionic emulsifier.

The amount of the emulsifier used in the emulsion polymerization may be, for example, 0.2 parts by weight or more, 0.5 parts by weight or more, or 1.0 part by weight or more with respect to 100 parts by weight of the monomer component. It may be 5 parts by weight or more. Further, from the viewpoint of improving the peeling strength A2 after immersion in water, reducing the rate of decrease in peeling force after immersion in water, or improving the transparency of the pressure-sensitive adhesive layer (layer A), the amount of the emulsifier used is determined in some embodiments. It is suitable to be 10 parts by weight or less with respect to 100 parts by weight of the component, preferably 5 parts by weight or less, and may be 3 parts by weight or less. The emulsifier used in the emulsion polymerization here can also function as a water affinity agent for the A layer.

According to emulsion polymerization, a polymerization reaction solution in the form of an emulsion in which a polymer of a monomer component is dispersed in water can be obtained. The aqueous dispersion type pressure-sensitive adhesive composition used for forming the A layer can be preferably produced by using the above-mentioned polymerization reaction solution.

In some preferred embodiments, the pressure-sensitive adhesive layer may have an A layer formed from a solvent-based pressure-sensitive adhesive composition. The solvent-based pressure-sensitive adhesive composition typically contains a solution polymerization of the monomer components and, optionally, an additive. The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; 1,2- Select from halogenated alkanes such as dichloroethane; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butylmethyl ether; ketones such as methyl ethyl ketone; etc. Any one solvent or a mixed solvent of two or more can be used. By solution polymerization, a polymerization reaction solution in which the polymer of the monomer component is dissolved in the polymerization solvent can be obtained. The solvent-type pressure-sensitive adhesive composition used for forming the A layer can be preferably produced by using the above-mentioned polymerization reaction solution.

In some preferred embodiments, the pressure-sensitive adhesive layer may have an A layer formed from an active energy ray-curable pressure-sensitive adhesive composition. Here, the "active energy ray" as used herein refers to an energy ray having energy that can cause a chemical reaction such as a polymerization reaction, a cross-linking reaction, or decomposition of an initiator. Examples of active energy rays referred to here include light such as ultraviolet rays, visible rays and infrared rays, and radiation such as α rays, β rays, γ rays, electron beams, neutron rays and X-rays. A photocurable pressure-sensitive adhesive composition is mentioned as a preferable example of the active energy ray-curable pressure-sensitive adhesive composition. The photocurable pressure-sensitive adhesive composition has an advantage that even a thick pressure-sensitive adhesive layer can be easily formed. Of these, an ultraviolet curable pressure-sensitive adhesive composition is preferable.

The photocurable pressure-sensitive adhesive composition typically contains at least a portion of the monomer component of the composition (which may be part of the type of monomer or part of the amount). Included in the form of a polymer. The polymerization method for forming the above-mentioned polymer is not particularly limited, and various conventionally known polymerization methods can be appropriately adopted. For example, thermal polymerization such as solution polymerization, emulsion polymerization, bulk polymerization (typically performed in the presence of a thermal polymerization initiator); photopolymerization performed by irradiating light such as ultraviolet rays (typically). Radiation polymerization performed by irradiating radiation such as β-rays and γ-rays; which is performed in the presence of a photopolymerization initiator; and the like can be appropriately adopted. Of these, photopolymerization is preferable.

The photocurable pressure-sensitive adhesive composition according to some preferred embodiments contains a partial polymer of monomer components. Such a partial polymer is typically a mixture of a polymer derived from a monomer component and an unreacted monomer, and preferably exhibits a syrup-like (viscous liquid) form. Hereinafter, the partial polymer having such properties may be referred to as "monomer syrup" or simply "syrup". The polymerization method for partially polymerizing the monomer component is not particularly limited, and various polymerization methods as described above can be appropriately selected and used. From the viewpoint of efficiency and convenience, the photopolymerization method can be preferably adopted. According to photopolymerization, the polymerization conversion rate (monomer conversion) of the monomer component can be easily controlled by the polymerization conditions such as the irradiation amount of light (light amount).

The polymerization conversion rate of the monomer mixture in the above partial polymer is not particularly limited. The polymerization conversion rate can be, for example, about 70% by weight or less, and preferably about 60% by weight or less. From the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition containing the partial polymer, the polymerization conversion rate is preferably about 50% by weight or less, and is about 40% by weight or less (for example, about 35% by weight). The following) is preferable. The lower limit of the polymerization conversion rate is not particularly limited, but is typically about 1% by weight or more, and it is appropriate to make it about 5% by weight or more.

For the pressure-sensitive adhesive composition containing a partial polymer of the monomer component, for example, a monomer mixture containing the entire amount of the monomer component used for preparing the pressure-sensitive adhesive composition is partially polymerized by an appropriate polymerization method (for example, a photopolymerization method). Can be obtained by Further, the pressure-sensitive adhesive composition containing a partial polymer of the monomer component is a partial polymer or a complete polymer of a monomer mixture containing a part of the monomer components used in the preparation of the pressure-sensitive adhesive composition, and the remaining monomer. It may be a mixture with a component or a partial polymer thereof. In the present specification, the term "complete polymer" means that the polymerization conversion rate is more than 95% by weight.

The pressure-sensitive adhesive composition containing the partial polymer may contain other components (for example, a photopolymerization initiator, a polyfunctional monomer, a cross-linking agent, a water-affinitive agent, etc.) used as necessary. The method of blending such other components is not particularly limited, and may be contained in the monomer mixture in advance or added to the partial polymer, for example.

(Water affinity)
The pressure-sensitive adhesive composition A that can be used for the pressure-sensitive adhesive layer (layer A) in the technique disclosed herein may contain a water-affinitive agent, if desired. By containing a water-affinitive agent in the pressure-sensitive adhesive layer (layer A), it is possible to effectively reduce the peeling force by utilizing an aqueous liquid such as water. The reason is not particularly limited, but in general, the water-affinity agent tends to be unevenly distributed on the surface of the pressure-sensitive adhesive layer (A layer) due to having a hydrophilic region, whereby the pressure-sensitive adhesive layer (A layer) is easily distributed. It is considered that the action of efficiently increasing the water affinity of the surface is exhibited, and the peeling force is effectively reduced when the pressure-sensitive adhesive layer (layer A) comes into contact with water.

As the water-affinitive agent, one that is liquid at room temperature (about 25 ° C.) can be preferably used from the viewpoint of ease of preparation of the pressure-sensitive adhesive composition. The water affinity agent may be used alone or in combination of two or more.

In some embodiments, as the water affinity agent, at least one compound A selected from a surfactant and a compound having a polyoxyalkylene skeleton can be used. As the surfactant and the compound having a polyoxyalkylene skeleton, one or more of known surfactants and compounds having a polyoxyalkylene skeleton can be used without particular limitation. Needless to say, among the above-mentioned surfactants, there are compounds having a polyoxyalkylene skeleton, and vice versa.

As the surfactant that can be used as the compound A, known nonionic surfactants, anionic surfactants, cationic surfactants and the like can be used. Of these, nonionic surfactants are preferable. The surfactant may be used alone or in combination of two or more.

Examples of nonionic surfactants are polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, poly. Polyoxyethylene alkyl phenyl ethers such as oxyethylene nonylphenyl ether; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate; polyoxyethylene sorbitan monolaurate, polyoxyethylene Polyoxyethylene sorbitan such as sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate. Examples thereof include fatty acid esters; polyoxyethylene glyceryl ether fatty acid esters; polyoxyelene-polyoxypropylene block copolymers; and the like. These nonionic surfactants can be used alone or in combination of two or more.

Examples of anionic surfactants are alkylbenzene sulphates such as nonylbenzene sulfonate, dodecylbenzene sulfonate (eg sodium dodecylbenzene sulfonate); lauryl sulphate (eg sodium lauryl sulphate, ammonium lauryl sulphate),. Alkyl sulfate such as octadecyl sulfate; fatty acid salt; polyoxyethylene alkyl ether sulfate such as polyoxyethylene octadecyl ether sulfate, polyoxyethylene lauryl ether sulfate (for example, polyoxyethylene alkyl ether sulfate), polyoxy Polyoxyethylene alkyl phenyl ether sulfates such as ethylene lauryl phenyl ether sulfate (eg, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, etc.), polyoxyethylene styrenated phenyl ether sulfates, etc. Polyether sulfate; polyoxyethylene alkyl ether phosphate such as polyoxyethylene stearyl ether phosphate, polyoxyethylene lauryl ether phosphate, etc .; sodium salt, potassium salt, etc. of the above polyoxyethylene alkyl ether phosphate, etc. Polyoxyethylene alkyl ether phosphate ester salt; lauryl sulfosuccinate, polyoxyethylene lauryl sulfosuccinate (eg, sodium polyoxyethylene alkyl sulfosuccinate), sulfosuccinate; polyoxyethylene alkyl ether acetate; etc. Can be mentioned. When the anionic surfactant forms a salt, the salt may be, for example, a metal salt such as a sodium salt, a potassium salt, a calcium salt or a magnesium salt (preferably a monovalent metal salt), an ammonium salt, an amine salt or the like. Can be. The anionic surfactant may be used alone or in combination of two or more.

In some embodiments, for example, anionic surfactants having at least one of a -POH group, a -COH group and a -SOH group may be preferably used. Of these, a surfactant having a —POH group is preferable. Such surfactants typically contain a phosphoric acid ester structure, such as a monoester of phosphoric acid (ROP (= O) (OH) ₂ ; where R is a monovalent organic group), a diester. ((RO) ₂ P (= O) OH; where R is the same or different monovalent organic group), a mixture containing both monoesters and diesters, and the like. A suitable example of a surfactant having a -POH group is a polyoxyethylene alkyl ether phosphoric acid ester. The number of carbon atoms of the alkyl group in the polyoxyethylene alkyl ether phosphoric acid ester may be, for example, 6 to 20, 8 to 20, 10 to 20, 12 to 20, or 14 to 20.

Examples of the cationic surfactant include polyether amines such as polyoxyethylene laurylamine and polyoxyethylene stearylamine. The cationic surfactant may be used alone or in combination of two or more.

Examples of the compound having a polyoxyalkylene skeleton that can be used as compound A include polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); polyethers containing polyoxyethylene units, and polyoxypropylene units. Polyethers, compounds containing oxyethylene units and oxypropylene units (the sequence of these units may be random or block-like); derivatives thereof; etc. can be used. Further, among the above-mentioned surfactants, compounds having a polyoxyalkylene skeleton can also be used. These can be used alone or in combination of two or more. Among them, it is preferable to use a compound containing a polyoxyethylene skeleton (also referred to as a polyoxyethylene segment), and PEG is more preferable.

The molecular weight (chemical formula amount) of the compound having a polyoxyalkylene skeleton (for example, polyethylene glycol) is not particularly limited, and it is appropriate that the compound has a polyoxyalkylene skeleton, for example, less than 1000, and is about 600 or less (for example, from the viewpoint of adhesive composition preparability). 500 or less) is preferable. The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (for example, polyethylene glycol) is not particularly limited, and a compound having a molecular weight of about 100 or more (for example, about 200 or more, further about 300 or more) is preferably used.

Other examples of water-affinitive agents include water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid. The water-soluble polymer may be used alone or in combination of two or more. In the technique disclosed herein, as the water affinity agent, one kind or two or more kinds of compound A may be used, or one kind or two or more kinds of water-soluble polymers may be used, and these may be used in combination. You may.

The HLB of the water-affinitive agent is not particularly limited, for example, 3 or more, about 6 or more is appropriate, and 8 or more (for example, 9 or more) can be used. In some preferred embodiments, the water affinity has an HLB of 10 or greater. As a result, water peelability tends to be preferably exhibited. The HLB is more preferably 11 or more, still more preferably 12 or more, and particularly preferably 13 or more (for example, 14 or more). By including a water affinity agent (typically a surfactant) having an HLB in the above range in the A layer, water exfoliation property can be exhibited more effectively. The upper limit of the HLB is 20 or less, for example, 18 or less, 16 or less, or 15 or less.

The HLB in the present specification is Hydrophilic-Lipophile Balance by Griffin, which is a value indicating the degree of affinity of the surfactant with water or oil, and the ratio of hydrophilicity to lipophilicity is between 0 and 20. It is expressed by the numerical value of. The definition of HLB is W. C. Griffin: J. Soc. Cosmetic Chemists, 1,311 (1949), Koshimin Takahashi, Yoshiro Namba, Motoo Koike, Masao Kobayashi, "Surfactant Handbook", 3rd edition, published by Engineering Books, November 25, 1972, p179- As described in 182 and the like. The water-affinitive agent having the HLB can be selected based on the common general knowledge of those skilled in the art by referring to the above-mentioned references as necessary.

It is preferable that such a water-affinitive agent is contained in the A layer in a free form. As the water-affinitive agent, one that is liquid at room temperature (about 25 ° C.) is preferably used from the viewpoint of the adhesive composition preparability.

The layer A containing the water-affinitive agent is typically formed from the pressure-sensitive adhesive composition A containing the water-affinitive agent. The pressure-sensitive adhesive composition A may be any of the above-mentioned water-dispersed pressure-sensitive adhesive composition, solvent-type pressure-sensitive adhesive composition, active energy ray-curable pressure-sensitive adhesive composition, hot-melt type pressure-sensitive adhesive composition, and the like. In some preferred embodiments, the A layer containing the water affinity agent may be a pressure-sensitive adhesive layer formed from a photocurable or solvent-type pressure-sensitive adhesive composition A. In such a layer A, the effect of adding a water affinity agent can be preferably exhibited. The A layer may have photocurability.

The content of the water affinity agent in the A layer is not particularly limited, and can be set so that the effect of using the water affinity agent is appropriately exhibited. In some embodiments, the content of the water affinity agent may be, for example, 0.001 part by weight or more per 100 parts by weight of the monomer component constituting the polymer (for example, acrylic polymer) contained in the layer A. It is suitable that the content is 0.01 parts by weight or more, 0.03 parts by weight or more, 0.07 parts by weight or more, or 0.1 parts by weight or more. In some preferred embodiments, the content of the water affinity may be, for example, 0.2 parts by weight or more with respect to 100 parts by weight of the monomer component, and 0.5 parts by weight or more from the viewpoint of obtaining a higher effect. It may be 1.0 part by weight or more, or 1.5 parts by weight or more. Further, from the viewpoint of suppressing excessive water diffusion of the A layer into the bulk, in some embodiments, the amount of the water affinity agent used may be, for example, 20 parts by weight or less with respect to 100 parts by weight of the monomer component. It is suitable to be 10 parts by weight or less, preferably 5 parts by weight or less, and may be 3 parts by weight or less. It is preferable that the content of the water-affinitive agent is not too large from the viewpoint of improving the peel strength A2 after immersion in water, reducing the rate of decrease in peeling force after immersion in water, or improving the transparency of the pressure-sensitive adhesive layer (layer A). For example, in some embodiments, the content of the water affinity with respect to 100 parts by weight of the monomer component may be less than 2 parts by weight, less than 1 part by weight, less than 0.7 parts by weight, or 0.3 parts by weight. It may be less than 0.2 parts by weight. A water affinity having an HLB of 10 or more tends to exhibit good water exfoliation properties even when used in a small amount.

(Polyfunctional monomer)
A polyfunctional monomer can be used for the pressure-sensitive adhesive composition A (and thus the pressure-sensitive adhesive layer (layer A)), if necessary. The polyfunctional monomer may serve for purposes such as adjusting cohesive force. The polyfunctional monomer forms a crosslinked structure having appropriate flexibility by reacting the ethylenically unsaturated group with light (for example, ultraviolet rays) irradiation at the time of forming the pressure-sensitive adhesive layer or after being attached to the adherend. obtain. Therefore, in the present specification, the "polyfunctional monomer" can be paraphrased as a cross-linking agent. For example, a polyfunctional monomer may be preferably used in a pressure-sensitive adhesive layer formed from a photocurable pressure-sensitive adhesive composition. As the polyfunctional monomer, a compound having two or more ethylenically unsaturated groups can be used. The polyfunctional monomer may be used alone or in combination of two or more.

Examples of the ethylenically unsaturated group contained in the polyfunctional monomer include, but are not limited to, an acryloyl group, a methacryloyl group, a vinyl group and an allylic group. Preferred ethylenically unsaturated groups from the viewpoint of photoreactivity include acryloyl group and methacryloyl group. Of these, the acryloyl group is preferable.

As the polyfunctional monomer, a compound having 2 to 10 ethylenically unsaturated groups in the molecule is preferable, a compound having 2 to 8 ethylenically unsaturated groups in the molecule is more preferable, and 2 to 2 to 8 in the molecule. Compounds with 6 ethylenically unsaturated groups are even more preferred. In some embodiments, the polyfunctional monomer comprises a compound having no more than 4 (specifically 2-4, eg, 2 or 3, preferably 2) ethylenically unsaturated groups in the molecule. Can be used. By using a polyfunctional monomer in which the number of such ethylenically unsaturated groups is limited, it is easy to obtain a pressure-sensitive adhesive layer having both extensibility and strength.

Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and penta. Elythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol Di (meth) acrylate, trimethylol propanetri (meth) acrylate, tetramethylol methanetri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinyl benzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl diol Examples thereof include (meth) acrylate and hexyldiol di (meth) acrylate. Of these, trimethylolpropane tri (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate are preferable, and 1,6-hexanediol diacrylate is more preferable.

The amount of the polyfunctional monomer used varies depending on its molecular weight, the number of functional groups, etc., but for example, a monomer component (typically, an acrylic polymer or the polymerization) that forms a polymer contained in the pressure-sensitive adhesive layer (A layer). It is appropriate that the range is about 0.01 parts by weight to 3.0 parts by weight with respect to 100 parts by weight (monomer component of the product). In some embodiments, the amount of the polyfunctional monomer used relative to 100 parts by weight of the monomer component may be, for example, 0.02 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more, and the like. It may be 1.0 part by weight or more or 2.0 parts by weight or more. As the amount of the polyfunctional monomer used increases, a higher cohesive force tends to be obtained. On the other hand, from the viewpoint of avoiding deterioration of the adhesiveness between the pressure-sensitive adhesive layer and the adjacent layer due to excessive improvement in cohesive force, the amount of the polyfunctional monomer used with respect to 100 parts by weight of the monomer component is, for example, 10 parts by weight or less. It may be 5.0 parts by weight or less, or 3.0 parts by weight or less. In some embodiments, the amount of the polyfunctional monomer used with respect to 100 parts by weight of the monomer component is preferably, for example, 1.0 part by weight or less, preferably 0.5 part by weight or less, and more preferably 0. It is 3 parts by weight or less, and may be 0.2 parts by weight or less.

(Crosslinking agent)
The pressure-sensitive adhesive composition A disclosed herein contains a cross-linking agent, if necessary, mainly for the purpose of cross-linking in the pressure-sensitive adhesive layer (layer A) or cross-linking between the pressure-sensitive adhesive layer and its adjacent surface. be able to. The cross-linking agent is typically contained in the pressure-sensitive adhesive layer (layer A) in the form after the cross-linking reaction. The pressure-sensitive adhesive layer (layer A) formed from the pressure-sensitive adhesive composition A containing a cross-linking agent typically contains a polymer cross-linked by the cross-linking agent (for example, an acrylic polymer). For example, the pressure-sensitive adhesive layer (layer A) can be a pressure-sensitive adhesive layer (layer A) containing an acrylic polymer crosslinked by a cross-linking agent. By using a cross-linking agent, the cohesive force of the pressure-sensitive adhesive layer (layer A) can be appropriately adjusted.

The type of the cross-linking agent is not particularly limited, and is selected from the conventionally known cross-linking agents so that the cross-linking agent exhibits an appropriate cross-linking function in the pressure-sensitive adhesive layer, for example, depending on the composition of the pressure-sensitive adhesive composition. be able to. Examples of the cross-linking agent that can be used include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, an aziridine-based cross-linking agent, a carbodiimide-based cross-linking agent, a melamine-based cross-linking agent, a urea-based cross-linking agent, a metal alkoxide-based cross-linking agent, and a metal. Examples thereof include a chelate-based cross-linking agent, a metal salt-based cross-linking agent, a hydrazine-based cross-linking agent, and an amine-based cross-linking agent. These can be used alone or in combination of two or more. In the water-dispersible pressure-sensitive adhesive composition, it is preferable to use a cross-linking agent that can be dissolved or dispersed in water.

The content of the cross-linking agent (when two or more kinds of cross-linking agents are contained, the total amount thereof) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits a well-balanced adhesive property such as adhesive force and cohesive force, the content of the cross-linking agent is a monomer component (for example, acrylic) that forms a polymer contained in the pressure-sensitive adhesive layer (A layer). It is appropriate that the amount is about 5 parts by weight or less, preferably about 0.001 to 5 parts by weight, and about 0.001 to 5 parts by weight with respect to 100 parts by weight of the system polymer or the monomer component of the polymer. It is more preferably 4 parts by weight, and further preferably about 0.001 to 3 parts by weight. Alternatively, the pressure-sensitive adhesive composition A containing no cross-linking agent as described above may be used. When a photocurable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition A disclosed herein, the pressure-sensitive adhesive composition may be substantially free of a cross-linking agent such as an isocyanate-based cross-linking agent. Here, the fact that the pressure-sensitive adhesive composition does not substantially contain a cross-linking agent (typically an isocyanate-based cross-linking agent) means that the amount of the cross-linking agent with respect to 100 parts by weight of the above-mentioned monomer component is less than 0.05 parts by weight (for example, 0. It means that it is less than 01 parts by weight).

A cross-linking catalyst may be used to allow the cross-linking reaction to proceed more effectively. Examples of the cross-linking catalyst include metal-based cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, butyl tin oxide, and dioctyl tin dilaurate. Of these, tin-based cross-linking catalysts such as dioctyltin dilaurate are preferable. The amount of the cross-linking catalyst used is not particularly limited. The amount of the cross-linking catalyst used is, for example, about 0.0001 parts by weight or more and about 0.001 parts by weight or more with respect to 100 parts by weight of the monomer component (for example, the monomer component of the acrylic polymer) contained in the pressure-sensitive adhesive composition A. , About 0.005 parts by weight or more, about 1 part by weight or less, about 0.1 parts by weight or less, about 0.05 parts by weight or less, and the like.

The pressure-sensitive adhesive composition A used for forming the pressure-sensitive adhesive layer (layer A) can optionally contain a compound that causes keto-enol tautomerization as a cross-linking retarder. For example, in the pressure-sensitive adhesive composition A containing an isocyanate-based cross-linking agent or the pressure-sensitive adhesive composition A that can be used by blending an isocyanate-based cross-linking agent, a compound that causes keto-enol telecommunication can be preferably used. Thereby, the effect of extending the pot life of the pressure-sensitive adhesive composition can be exhibited. The compounds that cause keto-enol tautomerism can be used alone or in combination of two or more. The amount of the compound that causes keto-enol remutability is 100 parts by weight based on 100 parts by weight of the monomer component (for example, the acrylic polymer or the monomer component of the polymer) forming the polymer in the pressure-sensitive adhesive layer (A layer). For example, it may be 0.1 parts by weight or more and 20 parts by weight or less, 0.5 parts by weight or more and 15 parts by weight or less is appropriate, and for example, 1 part by weight or more and 10 parts by weight or less can be used. It may be 1 part by weight or more and 5 parts by weight or less.

(Acrylic oligomer)
The pressure-sensitive adhesive layer (layer A) disclosed herein may contain an acrylic oligomer from the viewpoint of improving cohesive force, improving adhesion to an intermediate layer, and improving adhesion to an adherend. can. The pressure-sensitive adhesive layer (layer A) containing the acrylic oligomer can be formed by using the pressure-sensitive adhesive composition A containing the acrylic oligomer. As the acrylic oligomer, those having a higher Tg than the Tg of the above-mentioned acrylic polymer (for example, acrylic polymer) can be preferably adopted.

The Tg of the acrylic oligomer is not particularly limited, and may be, for example, about 20 ° C. or higher and 300 ° C. or lower. The Tg may be, for example, about 30 ° C. or higher, about 40 ° C. or higher, about 60 ° C. or higher, about 80 ° C. or higher, or about 100 ° C. or higher. As the Tg of the acrylic oligomer increases, the effect of improving the cohesive force tends to increase in general. Further, from the viewpoint of anchoring property to the intermediate layer, shock absorption, etc., the Tg of the acrylic oligomer may be, for example, about 250 ° C. or lower, about 200 ° C. or lower, about 180 ° C. or lower, or about 150 ° C. or lower. But it may be. The Tg of the acrylic oligomer is a value calculated based on the Fox formula, like the Tg of the acrylic polymer described above.

The Mw of the acrylic oligomer is not particularly limited, and may be, for example, about 1000 or more, appropriately about 1500 or more, about 2000 or more, or about 3000 or more. Further, the Mw of the acrylic oligomer may be, for example, about 30,000 or less, and it is appropriate that it is about 10,000 or less, and it may be about 7,000 or less, or about 5,000 or less. When Mw is within the above range, the cohesiveness of the pressure-sensitive adhesive layer (layer A) and the effect of improving the adhesiveness are likely to be suitably exhibited. The Mw of the acrylic oligomer can be measured by GPC and obtained as a standard polystyrene-equivalent value. Specifically, for example, it can be measured by using TSKgelGMH-H (20) × 2 as a column on HPLC8020 manufactured by Tosoh Co., Ltd. under the condition of a flow rate of about 0.5 mL / min in a tetrahydrofuran solvent.

The monomer components constituting the acrylic oligomer include the above-mentioned various (meth) acrylic acid C _1-20 alkyl esters; the above-mentioned various alicyclic hydrocarbon group-containing (meth) acrylates; and the above-mentioned various aromatic hydrocarbons. Hydrocarbon-containing (meth) acrylates; (meth) acrylates obtained from terpene compound derivative alcohols; and other (meth) acrylate monomers can be mentioned. These can be used alone or in combination of two or more.

The acrylic oligomer is an alkyl (meth) acrylate in which an alkyl group has a branched structure such as isobutyl (meth) acrylate and t-butyl (meth) acrylate; an alicyclic hydrocarbon group-containing (meth) acrylate and an aromatic hydrocarbon. From the viewpoint of improving adhesiveness, it is preferable to contain an acrylic monomer having a relatively bulky structure as a monomer unit, such as a group-containing (meth) acrylate; Further, when ultraviolet rays are used when synthesizing an acrylic oligomer or when producing an adhesive layer (layer A), a monomer having a saturated hydrocarbon group at the ester terminal is less likely to cause polymerization inhibition. Preferably, for example, an alkyl (meth) acrylate in which the alkyl group has a branched structure or a saturated alicyclic hydrocarbon group-containing (meth) acrylate can be preferably used.

The ratio of the (meth) acrylate monomer to all the monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (for example, 80% by weight). And more, 90% by weight or more). In some preferred embodiments, the acrylic oligomer has a monomer composition consisting substantially only of one or more (meth) acrylate monomers. When the monomer component contains an alicyclic hydrocarbon group-containing (meth) acrylate and a (meth) acrylic acid C _1-20 alkyl ester, their weight ratios are not particularly limited. In some embodiments, the weight ratio of the alicyclic hydrocarbon group-containing (meth) acrylate / (meth) acrylic acid C _1-20 alkyl ester is, for example, 10/90 or higher, 20/80 or higher, or 30/70 or higher. It can also be 90/10 or less, 80/20 or less, or 70/30 or less.

As a constituent monomer component of the acrylic oligomer, a functional group-containing monomer can be used, if necessary, in addition to the above (meth) acrylate monomer. As the functional group-containing monomer, a monomer having a nitrogen atom-containing heterocycle such as N-vinyl-2-pyrrolidone and N-acryloylmorpholin; an amino group-containing monomer such as N, N-dimethylaminoethyl (meth) acrylate; N, Examples thereof include an amide group-containing monomer such as N-diethyl (meth) acrylamide; a carboxy group-containing monomer such as AA and MAA; and a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate. These functional group-containing monomers may be used alone or in combination of two or more. When a functional group-containing monomer is used, the ratio of the functional group-containing monomer to all the monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and also. For example, it can be 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may be one in which a functional group-containing monomer is not used.

Suitable acrylic oligomers include, for example, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), and the like. In addition to 1-adamantyl methacrylate (ADAM) and 1-adamantyl acrylate (ADA) homopolymers, DCPMA and MMA copolymers, DCPMA and IBXMA copolymers, and ADA and methylmethacrylate (MMA) copolymer weights. Combined, a polymer of CHMA and isobutyl methacrylate (IBMA), a polymer of CHMA and IBXMA, a polymer of CHMA and acryloylmorpholin (ACMO), a polymer of CHMA and diethylacrylamide (DEAA), Examples thereof include a copolymer of CHMA and AA.

Acrylic oligomers can be formed by polymerizing their constituent monomer components. The polymerization method and the polymerization mode are not particularly limited, and various conventionally known polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization and the like) can be adopted as appropriate. The types of polymerization initiators (for example, azo-based polymerization initiators) that can be used as needed are generally as exemplified with respect to the synthesis of acrylic polymers, and the amount of the polymerization initiator and the chain transfer agent arbitrarily used. Since the amount of (for example, mercaptans) is appropriately set based on common general knowledge so as to have a desired molecular weight, detailed description thereof will be omitted.

When the pressure-sensitive adhesive layer (A layer) or the pressure-sensitive adhesive composition A contains an acrylic oligomer, the content thereof is the monomer of the polymer (typically the acrylic polymer) contained in the pressure-sensitive adhesive layer (A). For example, it may be 0.01 parts by weight or more with respect to 100 parts by weight of the component, and may be 0.05 parts by weight or more from the viewpoint of obtaining a higher effect, and 0.1 parts by weight or more or 0.2 parts by weight. The above may be applied. Further, from the viewpoint of compatibility with the above polymer (typically an acrylic polymer), it is appropriate that the content of the acrylic oligomer with respect to 100 parts by weight of the monomer component is less than 50 parts by weight. It is preferably less than 30 parts by weight, more preferably 25 parts by weight or less, and may be, for example, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less.

(Adhesive-imparting resin)
The pressure-sensitive adhesive layer (layer A) may contain a pressure-sensitive adhesive resin. Examples of the tackifying resin include petroleum-based tackifier resins, terpene-based tackifier resins, phenol-based tackifier resins, ketone-based tackifier resins, and the like, which include rosin-based tackifier resins and rosin derivative tackifier resins. .. These can be used alone or in combination of two or more.

In some embodiments, as the tackifier resin, one or more selected from a rosin-based tackifier resin, a rosin derivative tackifier resin, and a terpene phenol resin can be preferably used. Of these, a rosin derivative tackifier resin is preferable, and preferred examples thereof include rosin esters such as stabilized rosin ester and polymerized rosin ester. The above-mentioned tackifier resin is preferably used, for example, as a solvent-type or water-dispersible type pressure-sensitive adhesive.

The softening point of the tackifying resin is not particularly limited. From the viewpoint of suppressing a decrease in the cohesive force of the pressure-sensitive adhesive layer (layer A), a pressure-sensitive adhesive resin having a softening point of 80 ° C. or higher can be preferably used. The softening point of the tackifier resin may be 90 ° C. or higher, 100 ° C. or higher, 110 ° C. or higher, or 120 ° C. or higher. A tackifier resin having a softening point of 130 ° C. or higher or 140 ° C. or higher may be used. Further, from the viewpoint of transparency, adhesion to the intermediate layer, adhesiveness to the adherend, and the like, a tackifier resin having a softening point of 200 ° C. or lower or 180 ° C. or lower can be preferably used. As the softening point of the tackifier resin referred to here, a nominal value described in a document, a catalog, or the like can be adopted. When there is no nominal value, the softening point of the tackifier resin can be measured based on the softening point test method (ring ball method) specified in JIS K5902 or JIS K2207.

The amount of the tackifier resin used may be 1 part by weight or more with respect to 100 parts by weight of the monomer component constituting the polymer contained in the pressure-sensitive adhesive layer (A layer) from the viewpoint of appropriately exerting the effect of use. It is suitable, and may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more. Further, from the viewpoint of achieving both adhesion and cohesiveness to the intermediate layer and the adherend in a well-balanced manner, the amount of the tackifier resin used for 100 parts by weight of the monomer component may be, for example, 70 parts by weight or less, and 50 parts by weight. It may be less than or equal to 40 parts by weight or less. Alternatively, the content of the tackifier resin in the pressure-sensitive adhesive layer (layer A) can be, for example, less than 10 parts by weight, or even less than 5 parts by weight, based on 100 parts by weight of the monomer component. The content of the tackifier resin may be less than 1 part by weight (for example, less than 0.5 parts by weight) or less than 0.1 parts by weight (0 parts by weight or more and less than 0.1 parts by weight). The pressure-sensitive adhesive layer (layer A) may be the layer A that does not substantially contain the tackifier resin.

(Silane coupling agent)
In some embodiments, the pressure-sensitive adhesive layer (layer A) can contain a silane coupling agent. According to the layer A containing a silane coupling agent, a structure having a low rate of decrease in peeling force after immersion in water and a high rate of decrease in peeling force after water immersion can be preferably realized. The silane coupling agent may be used alone or in combination of two or more.

Examples of the silane coupling agent include silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane; 3-chloro Propyltrimethoxysilane; (meth) acrylic group-containing silane coupling agents such as acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane; 3-isocyanoxide propyltriethoxysilane Examples thereof include silane coupling agents containing isocyanate groups. Among them, preferred examples include 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane.

The amount of the silane coupling agent used can be set so as to obtain the desired effect of use, and is not particularly limited. In some embodiments, the amount of the silane coupling agent used may be, for example, 0.001 part by weight or more with respect to 100 parts by weight of the monomer component constituting the polymer contained in the A layer, which has a higher effect. From the viewpoint of obtaining, it may be 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.015 parts by weight or more. Further, from the viewpoint of improving the adhesion to the intermediate layer, in some embodiments, the amount of the silane coupling agent used is, for example, 3 parts by weight or less with respect to 100 parts by weight of the monomer component constituting the A layer. It may be 1 part by weight or less, or 0.5 part by weight or less. Further, the technique disclosed herein can be carried out in an embodiment using the pressure-sensitive adhesive composition A which does not substantially contain a silane coupling agent. By limiting the use of the silane coupling agent or not using the silane coupling agent, it is possible to suppress an increase in the adhesive strength with time, and it is easy to obtain good water peelability.

(Photopolymerization initiator)
The pressure-sensitive adhesive composition A and the photocurable pressure-sensitive adhesive layer (layer A) disclosed herein are subjected to a photopolymerization initiator (also referred to as a photoreaction catalyst), if necessary, for the purpose of improving or imparting photocurability. .) Can be contained. Examples of the photopolymerization initiator include a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, and a benzoin ether-based photopolymerization initiator, as in the case of the photopolymerization initiator exemplified as those that can be used for synthesizing acrylic polymers. Acylphosphine oxide-based photopolymerization initiator, α-ketol-based photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator , Benzophenone-based photopolymerization initiator, thioxanthone-based photopolymerization initiator, and the like can be used. As the photopolymerization initiator, one type may be used alone or two or more types may be used in combination as appropriate.

The content of the photopolymerization initiator in the pressure-sensitive adhesive layer (layer A) is not particularly limited, and can be set so as to appropriately exert the desired effect. In some embodiments, the content of the photopolymerization initiator is, for example, approximately 0.005 parts by weight with respect to 100 parts by weight of the monomer component of the polymer (typically an acrylic polymer) contained in the pressure-sensitive adhesive layer. It can be as above, 0.01 parts by weight or more is appropriate, 0.05 parts by weight or more is preferable, 0.10 parts by weight or more may be used, and 0.15 parts by weight or more may be used. It may be 0.20 part by weight or more. By increasing the content of the photopolymerization initiator, the photocurability of the pressure-sensitive adhesive layer (layer A) is improved. Further, the content of the photopolymerization initiator with respect to 100 parts by weight of the monomer component is preferably 5 parts by weight or less, preferably 2 parts by weight or less, and may be 1 part by weight or less. It may be 7 parts by weight or less, or 0.5 parts by weight or less. Not too much content of the photopolymerization initiator can be advantageous from the viewpoint of improving the storage stability (for example, stability against photodegradation) of the structure (for example, double-sided pressure-sensitive adhesive sheet).

The pressure-sensitive adhesive layer (layer A) containing the photopolymerization initiator can be typically formed by using the pressure-sensitive adhesive composition A (for example, a solvent-type pressure-sensitive adhesive composition) containing the photopolymerization initiator. .. The pressure-sensitive adhesive composition containing the photopolymerization initiator can be prepared, for example, by mixing other components used in the composition with the photopolymerization initiator. In addition, when preparing a pressure-sensitive adhesive composition using a polymer (typically an acrylic polymer) synthesized (photopolymerized) in the presence of a photopolymerization initiator, when synthesizing the above-mentioned polymer. The residue (unreacted product) of the photopolymerization initiator used in the above may be used as a part or all of the photopolymerization initiator contained in the pressure-sensitive adhesive layer (layer A). The same applies to the case where an acrylic oligomer synthesized as necessary in the presence of a photopolymerization initiator is used. From the viewpoint of ease of production control, the pressure-sensitive adhesive layer (layer A) disclosed here is a pressure-sensitive adhesive composition prepared by newly adding the above-mentioned amount of the photopolymerization initiator to other constituent components. Can be preferably formed using.

(Other ingredients)
The pressure-sensitive adhesive composition A used for forming the pressure-sensitive adhesive layer (layer A) may contain an acid or a base (ammonia water or the like) used for the purpose of pH adjustment or the like, if necessary. Other optional components that may be contained in the composition include viscosity modifiers (eg, thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, anti-aging agents. Various additives that are common in the field of pressure-sensitive adhesive compositions such as, etc. are exemplified. As for such various additives, conventionally known additives can be used by a conventional method and do not particularly characterize the present invention, and therefore detailed description thereof will be omitted.

(2) Layer B The pressure-sensitive adhesive layer disclosed here (including the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer; the same shall apply hereinafter unless otherwise specified) is the surface of the pressure-sensitive adhesive layer on at least the intermediate layer side. In addition to the A layer constituting the above layer, the B layer arranged on the back surface side of the A layer may be further included. According to the configuration including the A layer and the B layer as described above, for example, the bulk property (for example, water resistance, cohesiveness, heat resistance) of the pressure-sensitive adhesive layer is imparted to the A layer by the B layer while giving good water peelability to the A layer. Etc.) can be adjusted. Therefore, according to the pressure-sensitive adhesive layer having the structure including the A layer and the B layer, it is easy to obtain a structure having good water peelability and excellent water resistance and reliability. For example, a structure having a low rate of decrease in peeling force after immersion in water and a high rate of decrease in water peeling force can be preferably realized. Further, for example, a pressure-sensitive adhesive layer having both strong adhesiveness and good water peelability at a high level can be preferably realized.

The B layer may be arranged in direct contact with the back surface of the A layer, or may be arranged via another layer between the B layer and the back surface of the A layer. In some embodiments, a pressure-sensitive adhesive layer having a structure in which the A layer and the B layer are directly in contact with each other (that is, without interposing another layer) may be preferably adopted.

The B layer is known as, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a polyester adhesive, a urethane adhesive, a polyether adhesive, a polyamide adhesive, a fluorine adhesive and the like. It may be a pressure-sensitive adhesive layer composed of one type or two or more types of pressure-sensitive adhesives selected from various pressure-sensitive adhesives. From the viewpoint of transparency, weather resistance, and the like, an acrylic pressure-sensitive adhesive may be preferably used as the constituent material of the B layer in some embodiments. The acrylic pressure-sensitive adhesive constituting the B layer can be selected from those exemplified as the acrylic pressure-sensitive adhesive that can be used for the A layer, for example, so as to exhibit desired characteristics in combination with the A layer. For example, layer B may be substantially free of water-affinitives. Here, the fact that the B layer does not substantially contain the water affinity means that the amount of the water affinity with respect to 100 parts by weight of the monomer component of the polymer contained in the B layer is less than 0.1 parts by weight (for example, 0.05 parts by weight). Less than, and even less than 0.01 parts by weight). The B layer may have a single-layer structure composed of one layer, or may have a multi-layer structure including two or more layers having different compositions.

In some embodiments, the monomer component constituting the polymer (for example, an acrylic polymer) contained in the B layer is an alkyl C _1-20 (meth) acrylate in a proportion of 40% by weight or more of the total amount of the monomer component. May contain esters. The ratio of the C _1-20 (meth) acrylic acid alkyl ester to the entire monomer component of the B layer may be, for example, 98% by weight or less, and even if it is 95% by weight or less from the viewpoint of improving the cohesiveness of the B layer. It may be 85% by weight or less, 70% by weight or less, or 60% by weight or less.
The monomer component constituting the B layer may contain a copolymerizable monomer together with the (meth) acrylic acid alkyl ester. The copolymerizable monomer can be appropriately selected from those exemplified as the copolymerizable monomer that can be used for the A layer. The amount of the copolymerizable monomer used may be, for example, 5% by weight or more, 15% by weight or more, 30% by weight or more, or 40% by weight or more of all the monomer components constituting the B layer.

In some embodiments, the ratio of the carboxy group-containing monomer to the monomer components constituting the B layer may be, for example, 2% by weight or less, 1% by weight or less, or 0.5% by weight or less. It is not necessary to substantially use the carboxy group-containing monomer as the monomer component constituting the B layer. Here, the fact that the carboxy group-containing monomer is not substantially used means that the carboxy group-containing monomer is not used at least intentionally. A pressure-sensitive adhesive layer having a B layer having such a composition is preferable because it tends to have high water resistance and reliability.

As a preferred example of the pressure-sensitive adhesive layer including the A layer and the B layer, the gel fraction of the B layer is higher than the gel fraction of the A layer, and the swelling degree of the B layer is lower than the swelling degree of the A layer. Examples include a pressure-sensitive adhesive layer that satisfies one or both. According to such a configuration, it is easy to obtain a pressure-sensitive adhesive layer having a low rate of decrease in peeling force after immersion in water and a high rate of decrease in peeling force.

In some embodiments, the layer B may be a layer formed from a photocurable pressure-sensitive adhesive composition or a solvent-based pressure-sensitive adhesive composition. According to the B layer formed from such a composition, it is easy to obtain a pressure-sensitive adhesive layer having high water resistance and reliability. For example, a combination of an A layer formed from a water-dispersed pressure-sensitive adhesive composition and a B layer formed from a photocurable pressure-sensitive adhesive composition, or an A layer formed from a water-dispersed pressure-sensitive adhesive composition and a solvent. In combination with the B layer formed from the mold pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer having a low rate of decrease in peeling force after immersion in water and a high rate of decrease in peeling force after water can be preferably realized. In some embodiments, from the viewpoint of improving water resistance, the B layer which does not substantially contain a water affinity agent can be preferably adopted.

(3) Other Adhesive Layer The structure disclosed here may have another adhesive layer in addition to the above-mentioned A layer and B layer. Specifically, in a configuration in which only one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer constituting the structure disclosed herein has an A layer, the other pressure-sensitive adhesive layer (two or more layers). When having the multi-layer structure of, each layer) may correspond to the above-mentioned other pressure-sensitive adhesive layer. For example, in the embodiment in which the first pressure-sensitive adhesive layer has the A layer, the second pressure-sensitive adhesive layer can be the other pressure-sensitive adhesive layer. The other adhesive layers are, for example, acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluoroadhesives. It may be a pressure-sensitive adhesive layer composed of one kind or two or more kinds of pressure-sensitive adhesives selected from various known pressure-sensitive adhesives such as. From the viewpoint of transparency, weather resistance, and the like, an acrylic pressure-sensitive adhesive may be preferably adopted as a constituent material of the other pressure-sensitive adhesive layer in some embodiments.

The acrylic pressure-sensitive adhesive constituting the other pressure-sensitive adhesive layer (for example, the second pressure-sensitive adhesive layer) has characteristics desired as another pressure-sensitive adhesive layer from those exemplified as the acrylic pressure-sensitive adhesive that can be used for the A layer, for example. Can be selected so that For example, the other pressure-sensitive adhesive layer may be substantially free of water-affinitives. Here, the fact that the other pressure-sensitive adhesive layer does not substantially contain the water-affinitive agent means that the amount of the water-affinitive agent with respect to 100 parts by weight of the monomer component of the polymer contained in the other pressure-sensitive adhesive layer is less than 0.1 part by weight ( For example, less than 0.05 parts by weight, and even less than 0.01 parts by weight). Alternatively, when the other pressure-sensitive adhesive layer contains a water-affinitive agent, its content C2 is preferably less than the content C1 of the water-affinitive agent in the A layer, and the ratio (C2 / C1) is, for example, less than 1. , 0.5 or less, or 0.1 or less (for example, 0.01 or less). Further, in some embodiments, the other pressure-sensitive adhesive layer may be a layer formed from a photocurable pressure-sensitive adhesive composition or a solvent-type pressure-sensitive adhesive composition. Further, the other pressure-sensitive adhesive layer may have a single-layer structure composed of one layer, or may have a multi-layer structure including two or more layers having different compositions. For other matters of the above-mentioned other pressure-sensitive adhesive layer, the same structure as the above-mentioned pressure-sensitive adhesive layer can be adopted, or an appropriate structure can be adopted according to the application and purpose based on known or commonly used techniques and common general technical knowledge. Since it can be adopted, detailed description is omitted here.

(4) Common matters concerning the pressure-sensitive adhesive layer The pressure-sensitive adhesive layer may be a cured layer of the pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer can be formed by applying (for example, applying) the pressure-sensitive adhesive composition to an appropriate surface and then appropriately applying a curing treatment. When performing two or more types of curing treatments (drying, crosslinking, polymerization, etc.), these can be performed simultaneously or in multiple stages. In a pressure-sensitive adhesive composition using a partial polymer (acrylic polymer syrup) of a monomer component, a final copolymerization reaction is typically performed as the above-mentioned curing treatment. That is, the partial polymer is subjected to a further copolymerization reaction to form a complete polymer. For example, in the case of a photocurable pressure-sensitive adhesive composition, light irradiation is performed. If necessary, curing treatment such as crosslinking and drying may be carried out. For example, when it is necessary to dry with a photocurable pressure-sensitive adhesive composition, it is preferable to perform photo-curing after drying. In the pressure-sensitive adhesive composition using a complete polymer, typically, as the above-mentioned curing treatment, treatments such as drying (heat drying) and cross-linking are carried out as necessary. The pressure-sensitive adhesive layer having a multi-layer structure of two or more layers can be produced by laminating the pressure-sensitive adhesive layers formed in advance. Alternatively, the pressure-sensitive adhesive composition may be applied on the first pressure-sensitive adhesive layer formed in advance, and the pressure-sensitive adhesive composition may be cured to form the second pressure-sensitive adhesive layer.

The pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. For example, as a method of providing the pressure-sensitive adhesive layer on the intermediate layer, a direct method of directly applying the pressure-sensitive adhesive composition to the intermediate layer to form the pressure-sensitive adhesive layer may be used, and the pressure-sensitive adhesive layer formed on the peeling surface may be used. You may use a transfer method of transferring to an intermediate layer.

The thickness of the pressure-sensitive adhesive layer (for example, each pressure-sensitive adhesive layer of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) is not particularly limited, and may be, for example, about 3 μm to 1000 μm. From the viewpoint of making the pressure-sensitive adhesive layer adhere to the intermediate layer or the adherend to enhance water resistance reliability, in some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 5 μm or more, 10 μm or more, or 20 μm. It may be 30 μm or more, 50 μm or more, 50 μm or more, 70 μm or more, 100 μm or more, or 120 μm or more. Further, from the viewpoint of preventing the generation of adhesive residue due to the cohesive failure of the pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer may be, for example, 500 μm or less, 300 μm or less, or 200 μm or less in some embodiments. , 170 μm or less may be used. In some other preferred embodiments, the thickness of the pressure-sensitive adhesive layer is 130 μm or less, 90 μm or less, 60 μm or less, or 40 μm or less. The thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer arranged on each surface of the intermediate layer may be the same or different.

In some preferred embodiments, the pressure-sensitive adhesive layer (one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) is composed of an A layer. In other words, the pressure-sensitive adhesive layer may have a single-layer structure of only the A layer, which does not include the B layer. According to the technique disclosed herein, excellent water exfoliation property is realized by forming a hydrophilic surface on the intermediate layer, so that the purpose is to achieve both water exfoliation property and other properties (for example, water resistance reliability). It is not necessary to make the pressure-sensitive adhesive layer a multi-layer structure. That is, the desired characteristics can be realized without relying on the B layer. This is advantageous from the viewpoint of the production efficiency of the pressure-sensitive adhesive layer. In the pressure-sensitive adhesive layer composed of the A layer, the thickness of the pressure-sensitive adhesive layer means the thickness of the A layer.

As the pressure-sensitive adhesive layer becomes thicker, it tends to be difficult to achieve both water peelability and water resistance reliability in general. From this point of view, in an embodiment in which the thickness of the pressure-sensitive adhesive layer (one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) is, for example, more than 50 μm, the pressure-sensitive adhesive layer is the A layer and the B layer. A configuration including and can be preferably adopted. According to the pressure-sensitive adhesive layer having such a structure, even if the pressure-sensitive adhesive layer is thickened, it is easy to obtain a pressure-sensitive adhesive layer having both water peelability and water resistance reliability at a high level.

In the embodiment in which the pressure-sensitive adhesive layer includes the A layer and the B layer, the thickness of the A layer may be, for example, 1 μm or more, 2 μm or more, 4 μm or more, 5 μm or more, or 10 μm or more. It may be 15 μm or more. The thickness of the layer A may be, for example, 50 μm or less, 45 μm or less, 35 μm or less, or 25 μm or less. In particular, in the embodiment provided with the A layer formed from the water-dispersed pressure-sensitive adhesive composition portion or in the embodiment in which the A layer contains a water-affinitive agent, the fact that the thickness of the A layer is not too large indicates that the water resistance of the pressure-sensitive adhesive layer is reliable. Is preferable from the viewpoint of improving the transparency of the pressure-sensitive adhesive layer and improving the transparency of the pressure-sensitive adhesive layer.

In the embodiment in which the pressure-sensitive adhesive layer includes the A layer and the B layer, the thickness of the B layer may be, for example, 5 μm or more, or 10 μm or more. From the viewpoint of better exerting the effect of providing the B layer on the back side of the A layer, the thickness of the B layer may be, for example, 20 μm or more, 30 μm or more, or 50 μm or more in some embodiments. It may be 70 μm or more, or 100 μm or more.

In an embodiment in which the pressure-sensitive adhesive layer (one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) includes an A layer and a B layer, the thickness of the A layer in the total thickness of the pressure-sensitive adhesive layer. For example, may be 90% or less, preferably 70% or less, 50% or less, 30% or less, 20% or less, and 15% or less. Further, from the viewpoint of easy formation of the A layer and water peelability, in some embodiments, the thickness of the entire pressure-sensitive adhesive layer (one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer). The thickness of the A layer may be, for example, 3% or more, 5% or more, 7% or more, or 10% or more.

<Subject>
Includes adherends (first and second adherends) that are the objects of adhesion of the structures disclosed herein (eg, double-sided adhesive sheets) or that can be components of structures (eg, joints). Unless otherwise specified, the same applies hereinafter.) The types are not particularly limited, and for example, in various portable devices (portable devices), automobiles, home appliances, etc., fixing, joining, molding, decoration, protection, support, etc. with an adhesive, etc. Examples include various components and articles to be used. The adherend may be a member or article that needs to be recycled, repaired or replaced. The material of the adherend (at least the material constituting the surface (bonded surface)) is glass such as an alkaline glass plate or non-alkali glass; a metal material such as a resin film, stainless steel (SUS) or aluminum; acrylic. It may be a resin material such as a resin, an ABS resin, a polycarbonate resin, a polystyrene resin, a transparent polyimide resin, or the like. The adherend may be a painted surface with a paint such as acrylic, polyester, alkyd, melamine, urethane, acid-epoxy crosslinked, or a composite of these (for example, acrylic melamine or alkyd melamine), or zinc. It may have a plated surface such as a plated steel plate.

The adherend according to some aspects is, for example, an optical member. Here, the optical member is a member having optical characteristics (for example, polarization property, light refraction property, light scattering property, light reflection property, light transmission property, light absorption property, light diffusivity property, turning property, visibility, etc.). To say. The optical member is not particularly limited as long as it has optical characteristics, but is used, for example, as a member constituting a device (optical device) such as a display device (image display device) or an input device, or a member thereof. Examples thereof include polarizing plates, wavelength plates, retardation plates, optical compensation films, brightness improving films, light guide plates, reflective films, antireflection films, hard coat (HC) films, shock absorbing films, antifouling films, and the like. Photochromic film, dimming film, transparent conductive film (ITO film), design film, decorative film, surface protection plate, prism, lens, color filter, transparent substrate, and members in which these are laminated (collectively referred to as these). It may be referred to as a “functional film”). The above-mentioned "plate" and "film" shall include a plate-like, a film-like, a sheet-like form, respectively, and for example, the "polarizing film" shall include a "polarizing plate", a "polarizing sheet" and the like.

Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), electronic paper, and the like, and in particular, an expensive display device such as a foldable display device and an in-vehicle display device. The techniques disclosed herein are preferably applied when the components are included. Further, examples of the input device include a touch panel and the like.

The optical member is not particularly limited, and examples thereof include a member made of glass, acrylic resin, polycarbonate, polyethylene terephthalate, a metal thin film, or the like (for example, a sheet-shaped, film-shaped, or plate-shaped member). The "optical member" in this specification also includes a member (design film, decorative film, surface protective film, etc.) that plays a role of decoration and protection while maintaining the visibility of the display device and the input device.

In some preferred embodiments, the adherend is a polarizing film (polarizing film layer). The polarizing film may include a polarizing element and a transparent protective film arranged on at least one surface (preferably both sides) of the polarizing element. The polarizing element is not particularly limited, and for example, a hydrophilic polymer film on which a dichroic substance such as iodine or a dichroic dye is adsorbed and uniaxially stretched is used. Examples of the hydrophilic polymer film include a PVA-based film, a partially formalized PVA-based film, and an ethylene-vinyl acetate copolymer-based partially saponified film. As the polarizing element, a polyene-based oriented film such as a dehydrated product of PVA or a dehydrochlorinated product of polyvinyl chloride can also be used. Of these, a PVA-based film and a polarizing element made of a dichroic substance such as iodine are preferable.

As a material constituting the transparent protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. is preferably used. Specific examples of such thermoplastic resins include cellulose resins such as TAC, polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, and cycloolefin resins. Examples thereof include resins (typically norbornene-based resins), polyarylate resins, polystyrene resins, PVA resins, and mixtures of two or more of these. In some embodiments, the polarizing film has, for example, a configuration in which the polarizing film is sandwiched between two triacetyl cellulose (TAC) films. In some other preferred embodiments, a transparent protective film made of a thermoplastic resin such as TAC is placed on one surface of the polarizing element, and a cycloolefin resin (typically a norbornene resin) is placed on the other surface. ) Or, a configuration in which a transparent protective film made of (meth) acrylic resin is arranged can be adopted. In still another preferred embodiment, a transparent protective film made of a thermoplastic resin such as TAC is placed on one surface of the polarizing element, and the transparent protective film is prepared as a (meth) acrylic or urethane-based film on the other surface. Thermosetting resins such as acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can be used. These transparent protective films can be laminated on the polarizing element via an adhesive such as PVA. The transparent protective film may contain one or more of any suitable additives, depending on the intended purpose.

Further, a surface treatment layer may be provided on the back surface of the polarizing film. The surface treatment layer can be provided on the above-mentioned transparent protective film used for the polarizing film, or can be separately provided on the polarizing film as a separate body from the transparent protective film.

A preferred example of the surface treatment layer is a hard coat layer. As the material for forming the hard coat layer, for example, a thermoplastic resin or a material that is cured by heat or radiation can be used. Examples of the material used include thermosetting resins, ultraviolet curable resins, and radiation curable resins such as electron beam curable resins. Among them, the ultraviolet curable resin is preferable. The ultraviolet curable resin is excellent in processability because the cured resin layer can be efficiently formed by the curing treatment by ultraviolet irradiation. As the curable resin, one or more of polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, epoxy-based, melamine-based and the like can be used, and these may be monomers, oligomers, polymers and the like. It can be in the form of inclusion. A radiation-curable resin (typically an ultraviolet-curable resin) is particularly preferable because it does not require heat (which can cause damage to the base material) and is excellent in processing speed.

Other examples of the surface treatment layer include an antiglare treatment layer and an antireflection layer for the purpose of improving visibility. An antiglare treatment layer or an antireflection layer may be provided on the hard coat layer. The antireflection layer may have a multi-layer structure including a plurality of layers. Other examples of the surface treatment layer include a sticking prevention layer and the like. When the polarizing film disclosed herein is carried out in an embodiment including a surface treatment layer, the surface treatment layer can be impregnated with a conductive agent to impart conductivity.

In the embodiment in which the adherend is a polarizing film, the thickness of the polarizing film (in the case of being composed of a plurality of layers, the total thickness thereof) is not particularly limited, and is, for example, about 1 μm or more, and about 10 μm or more. Alternatively, about 20 μm or more is appropriate. For example, when a transparent protective film is provided, the thickness of the polarizing film is preferably about 30 μm or more, more preferably about 50 μm or more, still more preferably about 70 μm or more, from the viewpoint of protection and the like. The upper limit of the polarizing film is not particularly limited, and is, for example, about 1 mm or less, and about 500 μm or less or about 300 μm or less is appropriate. From the viewpoint of optical characteristics and thinning, the thickness is preferably about 150 μm or less, more preferably about 120 μm or less, still more preferably about 100 μm or less.

In another preferred embodiment, the adherend is a member constituting an electronic device. Electronic device components are often separated from the main body of the electronic device, which is the adherend, for repair, replacement, product inspection, etc., and the advantage of using the structure disclosed here (for example, double-sided adhesive sheet) is used. Is big. Further, the structure disclosed herein (for example, a double-sided adhesive sheet) includes a structure (for example, double-sided adhesive) for fixing a battery (including a primary battery and a secondary battery, for example, a polymer battery) to an electronic device (main body). It is particularly preferably used as a sheet). Batteries are usually placed in places that need to be removed when repairing, replacing, or inspecting components (including batteries) of electronic devices. Therefore, the adhesive for fixing the battery often needs to be removed. By applying the structure disclosed here (for example, a double-sided adhesive sheet) to such a usage mode, the function of fixing the battery well is exhibited, and when removing the battery after the usage period, the battery is removed. The main body of the electronic device and the battery can be separated by using water peeling, and the battery can be easily removed. According to the technique disclosed herein, the battery can be separated from the adherend (typically, the main body of the electronic device) to which the battery is joined while suppressing the deformation of the battery as the adherend. In such an embodiment, one of the first and second adherends is the main body of the electronic device (for example, the housing of the electronic device), and the other adherend is a member constituting the electronic device. Can be. For example, one of the first adherend and the second adherend is an electronic device main body (for example, a housing of an electronic device), and the other adherend is a battery. The structure (joint) in such an embodiment may be an electronic device in which a member (for example, a battery) is fixed by, for example, a double-sided adhesive sheet.

In the adherends (first adherend and second adherend) used in the technique disclosed herein, the surface (coverage) to which the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer or second pressure-sensitive adhesive layer) is attached. The adhesive surface) may be a hydrophilic surface or a non-hydrophilic surface (eg, a hydrophobic surface). According to the technique disclosed herein, two adherends can be separated by utilizing water exfoliation regardless of the surface texture of the adherend. The water contact angle of the adherend surface (adhesive surface) is not particularly limited, and is, for example, more than 30 degrees. In some preferred embodiments, the adhered surface is a hydrophobic surface with a water contact angle of 40 degrees or greater. Such a hydrophobic adherend (an adherend having a hydrophobic surface having a water contact angle of 40 degrees or more) is usually difficult to peel off and remove the pressure-sensitive adhesive by water peeling, but the techniques disclosed herein. According to the above, it is possible to separate the hydrophobic adherend, which has been difficult in the past, by utilizing water peeling. The water contact angle of the hydrophobic surface may be 50 degrees or more (for example, more than 50 degrees) or 60 degrees or more (for example, 65 degrees or more). The upper limit of the water contact angle of the adherend surface (adhesion surface) is not particularly limited, and may be, for example, less than 115 degrees, may be less than 105 degrees, or may be less than 95 degrees. In some preferred embodiments, both the adhered surface of the first adherend and the adhered surface of the second adherend are hydrophobic surfaces having a water contact angle in the range described above. The water contact angles of the adhered surface of the first adherend and the adhered surface of the second adherend may be the same or different.

<Thickness of structure>
In an embodiment in which the structure disclosed herein is in the form of a double-sided pressure-sensitive adhesive sheet, the thickness of the double-sided pressure-sensitive adhesive sheet (including a first pressure-sensitive adhesive layer, an intermediate layer, and a second pressure-sensitive adhesive layer, but not a release liner). The size is not particularly limited, and may be 3 μm or more, may be 5 μm or more, 10 μm or more is appropriate, and is preferably 20 μm or more from the viewpoint of adhesion to the adherend such as step followability. It is preferably 30 μm or more. In some embodiments, the thickness of the double-sided pressure-sensitive adhesive sheet may be 50 μm or more, 50 μm or more, 70 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the double-sided adhesive sheet is, for example, 5 mm or less, may be 3 mm or less, or may be 1 mm or less. In some preferred embodiments, the thickness of the double-sided pressure-sensitive adhesive sheet is preferably 500 μm or less, preferably 300 μm or less, more preferably 200 μm or less (for example, 150 μm or less), and 120 μm or less (for example, 80 μm or less). ) May be. Reducing the thickness of the adhesive sheet is also advantageous in terms of thinning, miniaturization, weight reduction, resource saving, and the like.

<Peeling liner>
The release liner used for the structure (typically a double-sided pressure-sensitive adhesive sheet) disclosed herein is not particularly limited, and for example, a release liner in which the surface of a liner base material such as a resin film or paper is peeled off, or a release liner. A release liner made of a low-adhesive material such as a fluoropolymer (polytetrafluoroethylene or the like) or a polyolefin resin (polyethylene, polypropylene, etc.) can be used. For the peeling treatment, for example, a silicone-based or long-chain alkyl-based peeling treatment agent may be used. In some embodiments, the peeled resin film can be preferably used as the peeling liner.

<Adhesive sheet>
The pressure-sensitive adhesive sheets provided herein include the pressure-sensitive adhesive sheets used in the structures disclosed herein. Such an adhesive sheet is preferably used for joining two adherends scheduled to be separated. The pressure-sensitive adhesive sheet according to the first aspect includes a pressure-sensitive adhesive layer and is preferably used as the first pressure-sensitive adhesive sheet in a set described later. It can also be used as the second adhesive sheet of the above set. The pressure-sensitive adhesive sheet according to the first aspect includes a pressure-sensitive adhesive layer. This pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer having an A layer, a pressure-sensitive adhesive layer having an A layer and a B layer, or a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive other than the A layer. good. The pressure-sensitive adhesive layer preferably has an A layer. Since the details of these pressure-sensitive adhesive layers are as described above, overlapping description will be omitted here. Further, the pressure-sensitive adhesive sheet may optionally have a base material layer having a hydrophilic surface or a base material layer having no hydrophilic surface. When the pressure-sensitive adhesive sheet has an A layer and a base material layer having a hydrophilic surface, it is preferable that the A layer is arranged on the hydrophilic surface. For example, when the pressure-sensitive adhesive sheet is used as the second pressure-sensitive adhesive sheet of the set, the pressure-sensitive adhesive sheet comprises a base material layer and an adhesive layer provided on one surface of the base material layer, and the base material layer is provided. At least one of the surfaces is a hydrophilic surface. The pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface side of the base material layer. As the base material layer having a hydrophilic surface, the configuration described as the intermediate layer can be preferably adopted. As the base material layer having no hydrophilic surface, the configuration described as another layer (for example, the main layer) of the intermediate layer can be preferably adopted. Further, as the release liner that can be used to protect the adhesive surface of the adhesive sheet, the structure of the release liner used for the structure can be adopted.

Further, the pressure-sensitive adhesive sheet provided by the present specification includes the pressure-sensitive adhesive sheet according to the second aspect, which comprises a base material layer and a pressure-sensitive adhesive layer provided on one surface of the base material layer. Such an adhesive sheet is preferably used for joining two adherends scheduled to be separated. Further, the pressure-sensitive adhesive sheet is preferably used as the second pressure-sensitive adhesive sheet in the set described later. In the pressure-sensitive adhesive sheet according to the second aspect, the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer having an A layer, a pressure-sensitive adhesive layer having a layer A and a layer B, and a pressure-sensitive adhesive other than the layer A. It may be an adhesive layer. In some embodiments, the pressure-sensitive adhesive layer does not have an A layer. Since the details of these pressure-sensitive adhesive layers are as described above, overlapping description will be omitted here. Further, at least one surface of the base material layer is a hydrophilic surface. As the base material layer having a hydrophilic surface, the configuration described as the intermediate layer can be preferably adopted. When the pressure-sensitive adhesive sheet has an A layer, it is preferable that the A layer is arranged on the hydrophilic surface. Further, as the release liner that can be used to protect the adhesive surface of the adhesive sheet, the structure of the release liner used for the structure can be adopted.

In the above-mentioned pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer having the A-layer is formed on a surface of an alkaline glass plate produced by a float method as an adherend and having a contact angle of 5 to 10 degrees with respect to distilled water. After 1 day at room temperature after pasting the layer side, 20 μL of distilled water was dropped onto the adherend, and the distilled water was allowed to enter one end of the interface between the A layer and the adherend, and then JIS Z0237: 2009. 10.4.1 Method 1: Water peeling measured at a test temperature of 23 ° C, with a tensile speed of 300 mm / min and a peeling angle of 180 °, according to the 180 ° peeling adhesive force to the test plate. The A layer side is attached to the surface of the alkaline glass plate produced by the float method as an adherend with a force B1 [N / 10 mm] and a contact angle of 5 to 10 degrees with respect to distilled water, and the room temperature is 1 From the adhesive strength B0 [N / 10 mm] after a day, the water separation reduction rate calculated by the following formula: (1- (B1 / B0)) × 100; is typically 40% or more, 70%. It is appropriate that the above is the case. The pressure-sensitive adhesive sheet satisfying this characteristic can be subjected to water exfoliation using an aqueous liquid such as water on the surface of the A layer. In some preferred embodiments, the rate of decrease in water peeling power may be, for example, 75% or more, 85% or more, 90% or more, 95% or more, or 97% or more. The rate of decrease in water peeling force is 100% or less in principle, and typically less than 100%.

(Peeling strength B0)
The peel strength B0 for the adherend is not particularly limited, but is preferably 2.0 N / 10 mm or more. Here, the peel strength B0 is a tensile strength at a temperature of 23 ° C. using an alkaline glass plate (an alkaline glass plate produced by a float method having a surface having a contact angle with distilled water of 5 to 10 degrees) as an adherend. The peel strength (normal peel strength) measured under the conditions of a speed of 300 mm / min and a peel angle of 180 degrees. It can also be said that the pressure-sensitive adhesive sheet having the peel strength B0 is adhered to the adherend with a peel strength B0 of a predetermined value or more. Thereby, the adhesive sheet can be stably adhered to the adherend. In some embodiments, the peel strength B0 may be, for example, 2.5N / 10mm or more, may be 3.0N / 10mm or more, or may be 3.5N / 10mm or more, from the viewpoint of adhesiveness to the adherend. It may be 4.0 N / 10 mm or more, 4.5 N / 10 mm or more, or 5.0 N / 10 mm or more. In some other embodiments, the peel strength B0 may be, for example, 6.0 N / 10 mm or more, 7.0 N / 10 mm or more, 8.0 N / 10 mm or more, 9.0 N / 10 mm or more. It may be 10.0 N / 10 mm or more, or 11.0 N / 10 mm or more. The upper limit of the peel strength B0 is not particularly limited, and may be, for example, 30 N / 10 mm or less. The peel strength B0 may be 20 N / 10 mm or less, or 15 N / 10 mm or less (for example, 12 N / 10 mm or less). In some embodiments, the peel strength B0 may be less than 10N / 10mm or less than 8N / 10mm.

(Water peeling force B1)
The pressure-sensitive adhesive sheet disclosed herein uses an alkaline glass plate (an alkaline glass plate manufactured by a float method having a surface having a contact angle with distilled water of 5 to 10 degrees) as an adherend. 20 μL of distilled water is supplied between the adhesive layer and the pressure-sensitive adhesive layer, and the distilled water is allowed to enter one end of the interface between the pressure-sensitive adhesive layer and the adherend, and then 10.4.1 of JIS Z0237: 2009. Method 1: Water peeling force measured according to the 180 ° peeling adhesive force to the test plate, specifically, at a test temperature of 23 ° C, using a tensile tester at a tensile speed of 300 mm / min and a peeling angle of 180 °. B1 [N / 10 mm] may be limited to a predetermined value or less. According to the configuration in which the water peeling force B1 is limited, the pressure-sensitive adhesive layer can be easily peeled off by water peeling using an aqueous liquid such as water. Although not particularly limited, the water peeling force B1 may be, for example, 3.5 N / 10 mm or less, 2.5 N / 10 mm or less, 1.6 N / 10 mm or less, or 1.2 N / 10 mm. It may be less than or equal to, and may be 1.0 N / 10 mm or less. According to the adhesive sheet having a low water peeling force B1, the load applied to the adherend at the time of water peeling can be reduced. The water peeling force B1 can also be preferably carried out in an embodiment of, for example, 0.75 N / 10 mm or less, 0.50 N / 10 mm or less, 0.25 N / 10 mm or less, or 0.15 N / 10 mm or less. The lower limit of the water peeling force B1 is not particularly limited, and may be substantially 0N / 10mm or more than 0N / 10mm.
From the viewpoint of reworkability and the like, it is preferable that the pressure-sensitive adhesive layer can be peeled off from the adherend without leaving the pressure-sensitive adhesive on the adherend in the measurement of the water peeling force B1. That is, it is preferable that the adhesive layer is excellent in non-glue residue property in peeling from the adherend. The presence or absence of the adhesive remaining on the adherend can be grasped, for example, by visually observing the adherend after the pressure-sensitive adhesive layer is peeled off.

(Rate of decrease in peeling force after immersion in water)
The pressure-sensitive adhesive sheet disclosed herein can be easily peeled off using an aqueous liquid such as water as described above, and the pressure-sensitive adhesive sheet is immersed in water for 30 minutes and then pulled out of the water to wipe off the adhered water. After soaking in water, the peel strength B2 [N / 10 mm] measured under the same conditions as the measurement condition of the peel strength B0 is the formula:
Rate of decrease in peeling force after immersion in water [%] = (1- (B2 / B0)) × 100
It is preferable to satisfy the peeling force reduction rate of 30% or less after immersion in water. That is, the formula:
(1- (B2 / B0)) × 100 ≦ 30 [%]
It is preferable to satisfy; This equation means the following equation: B2 ≧ 0.7B0 ;. The pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive satisfying the above-mentioned rate of decrease in peeling force after immersion in water (30% or less) is excellent in water resistance and reliability. From the viewpoint of obtaining higher water resistance reliability, the rate of decrease in peeling force after immersion in water is preferably, for example, 20% or less, more preferably 10% or less, and may be 7% or less. The lower limit of the rate of decrease in peeling force after immersion in water is typically 0% or more. In the above adhesive sheet, the difference between the water peeling power reduction rate [%] and the water peeling power reduction rate [%] is, for example, 45% or more, 55% or more, 70% or more, or 80% or more, or It can be preferably carried out in an embodiment of 90% or more.

The peeling strength B0, the water peeling force B1 and the peeling strength B2 after immersion in water are float methods having a surface having a contact angle of 5 to 10 degrees with respect to distilled water instead of an intermediate layer as an adherend to be peeled off. Other than using the alkaline glass plate produced in the above, the measurement is carried out basically in the same manner as the method for measuring the peel strength A0, the water peeling force A1 and the peeling strength A2 after immersion in water described in Examples described later. Specifically, the pressure-sensitive adhesive sheet is cut into a size of 20 mm in width and 100 mm in length to prepare a test piece, and the pressure-sensitive adhesive layer (layer A) of the test piece is placed on the alkaline glass plate as an adherend in an amount of 2 kg. The rubber roller is reciprocated once and crimped. This is autoclaved (50 ° C, 0.5 MPa, 15 minutes). Then, the peel strength B0, the water peeling force B1, and the peeling strength B2 after immersion in water are measured by the same method as the measurement of the peel strength A0, the water peeling force A1, and the peeling strength A2 after immersion in water.

In the above measurement, as the adherend, an alkaline glass plate produced by the float method and having a contact angle with distilled water of 5 to 10 degrees on the surface to which the test pieces are bonded is used. As such an adherend, an alkaline glass plate manufactured by Matsunami Glass Ind. Co., Ltd. can be used, but the present invention is not limited to this, and an equivalent product of the alkaline glass plate manufactured by Matsunami Glass Ind. Co., Ltd. or other alkaline glass. It is also possible to use a board.

The contact angle of the alkaline glass plate is measured by the following method. That is, in a measurement atmosphere of 23 ° C. and 50% RH, a contact angle meter (manufactured by Kyowa Surface Science Co., Ltd., trade name "DMo-501 type", control box "DMC-2", control / analysis software "FAMAS (version)" 5.0.30) ”) is used to measure by the sessile drop method. The amount of distilled water dropped is 2 μL, and the contact angle is calculated by the Θ / 2 method from the image 5 seconds after dropping (implemented at N5).

<Structure (substructure)>
The structure provided herein includes the structure according to the first aspect, which has an adherend and a pressure-sensitive adhesive layer. In this structure, the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer having an A layer, a pressure-sensitive adhesive layer having a layer A and a layer B, and a pressure-sensitive adhesive composed of a pressure-sensitive adhesive other than the layer A. It may be a layer. The pressure-sensitive adhesive layer preferably has an A layer. The pressure-sensitive adhesive layer is typically attached to one surface of the adherend. Since the details of these pressure-sensitive adhesive layers are as described above, overlapping description will be omitted here. Further, as the adherend in the above-mentioned structure, the configuration described in the above-mentioned adherend can be preferably adopted. Further, the structure may optionally have a layer having a hydrophilic surface and a layer having no hydrophilic surface. When the structure has an A layer and a layer having a hydrophilic surface, it is preferable that the A layer is arranged on the hydrophilic surface. For example, when the above structure is used as the second structure of the structure set, the second structure is a pressure-sensitive adhesive layer provided on one surface of a layer having a hydrophilic surface and a layer having the hydrophilic surface. And prepare. Further, the pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface. As the layer having a hydrophilic surface, the configuration described as the intermediate layer can be preferably adopted. As the layer having no hydrophilic surface, the configuration described as another layer (for example, the main layer) of the intermediate layer can be preferably adopted. Further, as the release liner that can be used to protect the adhesive surface (adhesive layer surface) of the structure, the above-mentioned release liner configuration can be adopted.

Further, the structure provided by the present specification includes the structure according to the second aspect, which has an adherend, an adhesive layer, and a layer having a hydrophilic surface in this order. In this structure, at least one surface of the layer having a hydrophilic surface is a hydrophilic surface. In this structure, the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer having an A layer, a pressure-sensitive adhesive layer having a layer A and a layer B, and a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive other than the layer A. It may be. Since the details of these pressure-sensitive adhesive layers are as described above, overlapping description will be omitted here. As the layer having a hydrophilic surface, the configuration described as the intermediate layer can be preferably adopted. When the pressure-sensitive adhesive layer has an A layer, it is preferable that the A layer is arranged on the hydrophilic surface. Further, as the release liner that can be used to protect the adhesive surface (adhesive layer surface) of the structure, the above-mentioned release liner configuration can be adopted.

In the above structure, the structure including the pressure-sensitive adhesive layer having the A layer typically has a water exfoliation reduction rate of 40% or more calculated by the above formula: (1- (B1 / B0)) × 100 ;. It is appropriate that it is 70% or more. A structure satisfying this property can be subjected to water exfoliation using an aqueous liquid such as water on the surface of the layer A. In some preferred embodiments, the rate of decrease in water peeling power may be, for example, 75% or more, 85% or more, 90% or more, 95% or more, or 97% or more. The rate of decrease in water peeling force is 100% or less in principle, and typically less than 100%. Further, the structure including the pressure-sensitive adhesive layer having the A layer has a peel strength B0, a water peeling force B1 and a water peeling force B1 in the same range as the peeling strength B0, the water peeling force B1 and the rate of decrease in the peeling force after immersion in water. It may have a rate of decrease in peeling force after immersion. The peel strength B0, water peeling force B1 and the rate of decrease in the peeling force after immersion in the structure are the same as the peeling strength B0, the water peeling force B1 and the rate of decrease in the peeling force after immersion in the adhesive sheet, except that the structure is used as a test piece. It is obtained by the same method.

<Set>
The set provided herein includes a pressure-sensitive adhesive sheet set comprising a first pressure-sensitive adhesive sheet and a second pressure-sensitive adhesive sheet. As the first pressure-sensitive adhesive sheet and the second pressure-sensitive adhesive sheet used as the above-mentioned set (typically, the pressure-sensitive adhesive sheet set), the above-mentioned pressure-sensitive adhesive sheet can be adopted. By using the first pressure-sensitive adhesive sheet and the second pressure-sensitive adhesive sheet in combination, the structure of the structure disclosed herein can be obtained. The above set can be preferably used for joining two adherends scheduled to be separated. The above set can be preferably used in the method for separating the adherend and the method for separating and joining the adherend disclosed here.

Further, the set provided by the present specification includes a structure set including a first structure and a second structure. As the first structure and the second structure used as the above set (typically, the structure set), the above-mentioned structure can be adopted. By using the first structure and the second structure in combination, the structure of the structure disclosed herein can be obtained. The set can be a component of the junction of two adherends that are scheduled to be separated. The above set can be preferably used in the method for separating the adherend and the method for separating and joining the adherend disclosed here.

<Separation method>
The techniques disclosed herein also include a method of separating two joined adherends (first adherend and second adherend). In this method, the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order between the joined first adherend and the second adherend. Also, at least one surface of the intermediate layer is a hydrophilic surface. Further, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer. Then, this method includes a step of peeling the pressure-sensitive adhesive layer having the A layer from the intermediate layer. Specifically, in the state where the aqueous liquid is present at the interface between the intermediate layer and the pressure-sensitive adhesive layer in the peeling front of the pressure-sensitive adhesive layer from the intermediate layer, the water-based liquid follows the movement of the peeling front. The present invention comprises a water peeling step of peeling the pressure-sensitive adhesive layer from the intermediate layer while advancing the entry into the interface. According to the water peeling step, the pressure-sensitive adhesive layer can be peeled from the intermediate layer by effectively utilizing the aqueous liquid, and the two bonded bodies can be separated.

As the aqueous liquid, water or a mixed solvent containing water as a main component and containing a small amount of additives as necessary can be used. As the solvent other than water constituting the mixed solvent, a lower alcohol (for example, ethyl alcohol) or a lower ketone (for example, acetone) that can be uniformly mixed with water can be used. As the additive, a known surfactant or the like can be used. From the viewpoint of avoiding contamination of the adherend, an aqueous liquid containing substantially no additive may be preferably used in some embodiments. From the viewpoint of environmental hygiene, it is particularly preferable to use water as the aqueous liquid. The water is not particularly limited, and for example, distilled water, ion-exchanged water, tap water, or the like can be used in consideration of purity, availability, and the like required according to the intended use.

In some embodiments, the peeling method supplies an aqueous liquid onto the intermediate layer near the outer edge of the pressure-sensitive adhesive layer attached to the intermediate layer, as in the case of measuring the water peeling force A1, for example, and the aqueous liquid thereof. From the outer edge of the pressure-sensitive adhesive layer to the interface between the pressure-sensitive adhesive layer and the intermediate layer, without supplying new water (that is, only the aqueous liquid supplied onto the intermediate layer before the start of peeling). It can be preferably carried out in an embodiment in which the peeling of the pressure-sensitive adhesive layer is promoted. If the water that follows the movement of the peeling front and enters the interface between the adhesive layer and the intermediate layer is depleted in the middle of the water peeling step, it may be intermittent or intermittent after the start of the water peeling step. Additional water may be continuously supplied. For example, when the intermediate layer has water absorption, or when the aqueous liquid tends to remain on the surface or adhesive surface of the intermediate layer after peeling, an embodiment in which water is additionally supplied after the start of the water peeling step can be preferably adopted.

The amount of the aqueous liquid supplied before the start of peeling is not particularly limited as long as the amount of the aqueous liquid can be introduced into the interface between the pressure-sensitive adhesive layer and the intermediate layer from outside the sticking range of the pressure-sensitive adhesive layer. The amount of the aqueous liquid may be, for example, 5 μL or more, 10 μL or more is appropriate, and 20 μL or more may be used. Further, there is no particular limitation on the upper limit of the amount of the aqueous liquid. In some embodiments, from the viewpoint of improving workability, the amount of the aqueous liquid may be, for example, 10 mL or less, 5 mL or less, 1 mL or less, 0.5 mL or less, 0.1 mL or less. However, it may be 0.05 mL or less. By reducing the amount of the aqueous liquid, the operation of removing the aqueous liquid by drying, wiping, or the like after the pressure-sensitive adhesive layer is peeled off can be omitted or simplified.

The operation of allowing the aqueous liquid to enter the interface between the pressure-sensitive adhesive layer and the intermediate layer from the outer edge of the pressure-sensitive adhesive layer at the start of peeling is, for example, an operation of using a jig such as a cutter knife or a needle at the interface on the outer edge of the pressure-sensitive adhesive layer. Insert the tip, scratch the outer edge of the adhesive layer with a hook or claw to lift it, attach a strong adhesive tape or sucker to the back surface near the outer edge of the structure, and lift the edge of the adhesive layer. And so on. As the adhesive tape, for example, it is preferable to use a pickup tape as shown in FIGS. 7 and 8. By forcibly injecting the aqueous liquid into the interface from the outer edge of the pressure-sensitive adhesive layer in this way, it is possible to efficiently form a state in which the aqueous liquid exists at the interface between the intermediate layer and the pressure-sensitive adhesive layer. In addition, good water peeling property after creating a trigger for peeling by forcibly injecting an aqueous liquid into the interface and high water resistance reliability when such an operation is not performed are preferably compatible. Can be done. As another preferred embodiment, for example, as in the structure shown in FIG. 6, an embodiment in which the pressure-sensitive adhesive layer non-existent region is provided on the surface of the end portion of the intermediate layer can be mentioned. In such an embodiment, by supplying the aqueous liquid to the region where the pressure-sensitive adhesive layer does not exist on the surface of the intermediate layer (hydrophilic surface), the aqueous liquid wets and spreads on the hydrophilic surface, so that the interface between the pressure-sensitive adhesive layer and the intermediate layer is formed. The aqueous liquid can be easily and efficiently entered into the water.

The pressure-sensitive adhesive layer to be peeled off by the above-mentioned peeling method is preferably, for example, any of the pressure-sensitive adhesive layers disclosed herein. The peeling method is suitable as a peeling method for the pressure-sensitive adhesive layer from the intermediate layer in any of the structures disclosed herein.

The water peeling step according to some aspects can be preferably carried out in a mode in which the peeling front is moved at a speed of 10 mm / min or more. Moving the peeling front at a speed of 10 mm / min or more corresponds to peeling the pressure-sensitive adhesive layer at a tensile speed of 20 mm / min or more, for example, under the condition of a peeling angle of 180 degrees. The speed at which the peeling front is moved may be, for example, 50 mm / min or more, 150 mm / min or more, 300 mm / min or more, or 500 mm / min or more. According to the peeling method disclosed herein, by peeling the pressure-sensitive adhesive layer from the intermediate layer while advancing the invasion of the aqueous liquid into the interface, the peeling speed is good even at such a relatively high speed. Can exhibit excellent water peelability. The upper limit of the speed at which the peeling front is moved is not particularly limited. The speed at which the peel front is moved can be, for example, 1000 mm / min or less. Such water peeling can be smoothly carried out, for example, by using a pickup tape as shown in FIGS. 7 and 8 or by arranging an adhesive sheet extending portion as shown in FIG.

The peeling method disclosed herein is carried out, for example, in such a manner that the peeling area of the pressure-sensitive adhesive layer per 10 μL of the volume of the aqueous liquid (for example, water) used in the method is, for example, 50 cm ² or more, preferably 100 cm ² or more. can do.

<Joining method>
The adherend separated between the intermediate layer and the pressure-sensitive adhesive layer as described above can be rejoined with an adherend different from the separated adherend. That is, the technique disclosed herein includes a method of separating the joined first adherend and the second adherend and joining the third adherend to the second adherend. In this method, the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order between the joined first adherend and the second adherend. Also, at least one surface of the intermediate layer is a hydrophilic surface. Further, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer. In this method, the pressure-sensitive adhesive layer having the A layer is peeled off from the intermediate layer to separate the first adherend and the second adherend, and the third adherend is seconded by the pressure-sensitive adhesive sheet. Includes a step of joining to the adherend. According to this method, a third adherend different from the first adherend can be joined to the second adherend by using an adhesive sheet at the place where the first adherend was present. 2 In the adherend, the first adherend and the third adherend can be exchanged or replaced. The step of peeling the pressure-sensitive adhesive layer from the intermediate layer is as described in the above separation method. Further, the step of joining the third adherend with the adhesive sheet can be carried out by a known or conventional method using an appropriate sticking means such as a roller. As the pressure-sensitive adhesive sheet used for attaching the third adherend, a known or conventional pressure-sensitive adhesive sheet may be used, or the pressure-sensitive adhesive sheet disclosed herein may be used.

More specifically, after the pressure-sensitive adhesive layer having the A layer (for example, the first pressure-sensitive adhesive layer) is peeled off from the intermediate layer, the intermediate layer may remain in the second adherend. For example, on the surface of the second adherend (adhesive surface), the pressure-sensitive adhesive layer (for example, the second pressure-sensitive adhesive layer) having no A layer and the intermediate layer may remain in a laminated state. The third adherend is attached to the surface of the intermediate layer using an adhesive sheet. In this way, the third adherend different from the first adherend can be joined to the second adherend by using the adhesive sheet at the place where the first adherend was.

The pressure-sensitive adhesive sheet used for joining the third adherend to the second adherend preferably contains an adhesive layer having an A layer. As the pressure-sensitive adhesive sheet, the above-mentioned structure of the pressure-sensitive adhesive layer having the A layer is preferably adopted. By using the pressure-sensitive adhesive layer having the A layer for joining the third adherend, the third adherend is bonded to the second adherend, and then the third adherend is bonded at an appropriate timing. Water separation can be performed between the A layer of the agent layer and the intermediate layer to separate the third adherend and the second adherend. Further, it is possible to join the fourth adherend, which is different from the third adherend, to the second adherend by using the adhesive sheet at the place where the third adherend was. According to the above method, the adherends bonded to the second adherend (specifically, the first adherend, the third adherend, the fourth adherend, etc.) are repeatedly separated and joined. can do. Such an adherend (specifically, a first adherend, a third adherend, a fourth adherend, etc.) may be different parts or articles of the same type, or the same part. Or it may be an article. As a combination of such adherends, for example, a combination in which the first adherend is a used product (for example, a used battery) and the third adherend is a new product (for example, a battery), or a first cover. Examples thereof include a combination in which the body is a part before repair and the third adherend is the same part after repair. The above method is suitable for replacing the battery.

<Use>
Since the structure disclosed herein can separate two adherends by water exfoliation using an aqueous liquid such as water, parts and articles that are adherents can be recycled, repaired, or replaced. Taking advantage of these features, it is suitable for applications such as various portable devices (portable devices), automobiles, home appliances, etc., which may require recycling, repair, or replacement. The structure disclosed herein also includes, for example, a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), a display device (image display device) such as electronic paper, and an input device such as a touch panel. Etc. (optical equipment), particularly suitable for foldable display devices and in-vehicle display devices. These applications often include expensive components, and the advantages of applying the techniques disclosed herein are great.

In some preferred embodiments, the structures disclosed herein are, for example, mobile phones, smartphones, tablet computers, laptop computers, various wearable devices (eg, wristwear-type, clips that are worn on the wrist, such as watches. Modular type that is attached to a part of the body with a strap, eyewear type including glasses type (monocular type, binocular type, including head mount type), shirts, socks, hats, etc., for example in the form of accessories Clothes type to be attached, earwear type to be attached to the ear like earphones), digital camera, digital video camera, audio equipment (portable music player, IC recorder, etc.), computer (computer, etc.), portable game equipment, electronic dictionary, electronic notebook , For fixing protective panels (lenses) that protect display units, for fixing key module members, in portable electronic devices such as electronic books, in-vehicle information devices, portable radios, portable TVs, portable printers, portable scanners, and portable modems. For fixing antenna modules, fixing rim sheets, fixing decoration panels, fixing batteries, and fixing various other members (circuit boards, various panel members, buttons, lighting equipment members, internal camera members, heat dissipation materials, graphite sheets), It can be preferably applied to applications such as fixing logos (design characters) and display objects (including various marks) such as various designs. In addition, in this specification, "portable" means that it is not enough to be portable, but to have a level of portability that an individual (standard adult) can carry relatively easily. It shall mean.

The structure disclosed herein is suitable for use in an electronic device (typically a portable electronic device) for fixing a battery (including a primary battery and a secondary battery, for example, a polymer battery). Batteries are usually placed in places that need to be removed when repairing, replacing, or inspecting components (including batteries) of electronic devices. Therefore, the structure for fixing the battery (typically an adhesive sheet) often needs to be removed. By applying the above structure to this application, while demonstrating the function of fixing the battery well, when removing the battery after the period of use, the separation method by water peeling using tension is used. The removal can be done easily.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

<Evaluation method>
[Peeling strength A0]
A structure having a size of 20 mm in width and 100 mm in length is prepared as a test piece.
After the above test piece is autoclaved (50 ° C., 0.5 MPa, 15 minutes), a cutter knife is inserted into the interface between the intermediate layer and the pressure-sensitive adhesive layer under the same environment at 23 ° C. and 50% RH. One end of the pressure-sensitive adhesive layer in the longitudinal direction is peeled off from the intermediate layer, and a tensile tester (manufactured by Minebea, universal tensile compression tester, device name "tensile compression tester, TCM-1kNB") is used to achieve a tensile speed of 300 mm. / Minute, peel strength of the pressure-sensitive adhesive layer from the intermediate layer under the condition of peeling angle of 180 degrees (however, the peel strength until the transition to the water peeling force measurement described below, that is, until the distilled water is supplied to the peeling interface. ) Is measured. When the intermediate layer has a hydrophilic surface, the peel strength measurement is carried out on the adhesive surface between the pressure-sensitive adhesive layer and the hydrophilic surface of the intermediate layer. The measurement is performed three times, and the value obtained by converting the average value into a value per 10 mm width (unit: N / 10 mm) is defined as a peel strength A0 [N / 10 mm]. The peel strength A0 is also usually referred to as a peel strength. The peel strength is measured so that the peeling of the test piece attached to the adherend proceeds from the bottom to the top. As the tensile tester, an equivalent product of the universal tensile compression tester may be used.
In the measurement, if necessary, an appropriate backing material can be attached to the opposite surface (the surface opposite to the surface of the A layer) of the structure (for example, the double-sided adhesive sheet) to reinforce the test piece. As the backing material, for example, a PET film having a thickness of about 25 μm can be used. When the non-adhesive layer is arranged on the back surface of the adhesive layer, the backing with a PET film is unnecessary.
When a double-sided pressure-sensitive adhesive sheet containing a photocurable pressure-sensitive adhesive layer is used as the test piece, the test piece taken out from the autoclave is irradiated with light in an environment of 23 ° C. and 50% RH, and then the peeling strength is increased. To measure. The light irradiation conditions (wavelength, irradiation intensity, irradiation time, etc.) are appropriately set according to the composition, thickness, and the like of the pressure-sensitive adhesive layer. For example, after the autoclave treatment, the photocurable pressure-sensitive adhesive layer can be cured by irradiating ultraviolet rays with an integrated light amount of 3000 mJ / cm ² using a high-pressure mercury lamp (300 mW / cm ² ).

[Water peeling force A1]
In the measurement of the peeling strength A0, during the measurement of the peeling strength of the pressure-sensitive adhesive layer from the intermediate layer, 20 μL of distilled water is supplied to a portion (peeling interface) where the pressure-sensitive adhesive layer begins to separate from the intermediate layer, and the distillation thereof is performed. Measure the peel strength after water supply. Therefore, when the intermediate layer has a hydrophilic surface, the peel strength measurement is carried out on the adhesive surface between the pressure-sensitive adhesive layer and the hydrophilic surface of the intermediate layer. The measurement is performed for each peeling strength measurement (that is, three times), and the average value thereof is converted into a value per 10 mm width (unit: N / 10 mm) and used as the water peeling force A1 [N / 10 mm]. ..
The measurement conditions for the peel strength after the supply of distilled water shall be in accordance with JIS Z0237: 2009 10.4.1 Method 1: 180 ° peeling adhesive strength to the test plate. Specifically, the test temperature is 23 ° C., a tensile tester is used, and the tensile speed is 300 mm / min and the peeling angle is 180 degrees.
Here, the peel strength and the water peeling force are measured continuously for each test piece, but the peeling strength and the water peeling force are measured by different test pieces. May be good. For example, when it is difficult to prepare a test piece having a sufficient length for carrying out continuous measurement, an embodiment in which measurement is performed using different test pieces can be adopted. In that case, a cutter knife is inserted into the interface between the intermediate layer and the pressure-sensitive adhesive layer to peel off one end of the pressure-sensitive adhesive layer in the longitudinal direction from the intermediate layer, and distilled water is supplied to the peeling strength to measure the peeling strength.

[Peeling strength A2 after immersion in water]
A test piece is prepared by cutting the structure into a rectangular shape having a width of 10 mm and a length of 120 mm. This test piece is put into an autoclave and treated for 15 minutes under the conditions of a pressure of 5 atm and a temperature of 50 ° C.
The evaluation sample taken out from the autoclave is kept in an environment of 23 ° C. and 50% RH for 1 day, and then immersed in water at room temperature (23 ° C. to 25 ° C.) for 30 minutes. Ion-exchanged water or distilled water is used as the water. In water, the test piece is held horizontally with the adhesive layer side facing up. The distance (immersion depth) from the upper surface of the test piece to the water surface is 10 mm or more (for example, about 10 mm to 100 mm). Next, the test piece is pulled up from the water, the water adhering to the test piece is gently wiped off, and then a cutter knife is inserted into the interface between the pressure-sensitive adhesive layer and the intermediate layer to insert one end of the pressure-sensitive adhesive layer in the longitudinal direction. Peel off, in an environment of 23 ° C and 50% RH, according to JIS Z0237: 2009 "10.4.1 Method 1: 180 ° peeling adhesive force to the test plate", specifically, at a test temperature of 23 ° C. The peel strength of the pressure-sensitive adhesive layer from the intermediate layer is measured using a tensile tester under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees. When the intermediate layer has a hydrophilic surface, the peel strength measurement is carried out on the adhesive surface between the pressure-sensitive adhesive layer and the hydrophilic surface of the intermediate layer. The measured value is the peel strength A2 [N / 10 mm] after immersion in water. The time from pulling up the test piece from water to measuring the peel strength shall be within 10 minutes.

The measurement conditions for the peel strength after immersion in water are the same as the measurement conditions for the peel strength A0 except for the immersion in water. Further, as the tensile tester, a universal tensile compression tester (device name "tensile compression tester, TCM-1kNB" manufactured by Minebea Co., Ltd.) or an equivalent product thereof can be used. The peel strength is measured so that the peeling of the test piece attached to the adherend proceeds from the bottom to the top. In the measurement, if necessary, an appropriate backing material can be attached to the opposite surface (the surface opposite to the surface of the A layer) of the structure (for example, the double-sided adhesive sheet) to reinforce the test piece. As the backing material, for example, a PET film having a thickness of about 25 μm can be used.

[Measurement of film thickness]
The film thickness of silicon oxide is measured by the X-ray reflectivity method, and the X-ray reflectivity is measured with a powder X-ray diffractometer (manufactured by Rigaku Co., Ltd., device name "RINT-2000") under the following measurement conditions. , Calculated by analyzing the acquired measurement data with analysis software ("GXRR3" manufactured by Rigaku Corporation). The analysis conditions were as follows, and a two-layer model of a polymer film substrate and a silicon oxide film with a density of 2.3 g / cm ³ was adopted, and the film thickness and surface roughness of the silicon oxide film and the surface roughness of the substrate film were adopted. With the value as a variable, the minimum square fitting is performed and the thickness of the silicon oxide layer is analyzed.
(Measurement condition)
Light source: Cu-Kα ray (wavelength: 1.5418 Å), 40 kV, 40 mA
Optical system: Parallel beam optical system Divergence slit: 0.05 mm
Light receiving slit: 0.05 mm
Monochromatic / parallelization: Using multi-layer Goebel mirror Measurement mode: θ / 2θ Scan mode Measurement range (2θ): 0.3 to 1.5 °
(Analysis conditions)
Analysis method: Least square fitting Analysis range (2θ): 2θ = 0.3 to 1.5 °

[Measurement of water contact angle]
The water contact angle on the surface of the intermediate layer material is measured as follows. That is, in a measurement atmosphere of 23 ° C. and 50% RH, a contact angle meter (manufactured by Kyowa Surface Science Co., Ltd., trade name "DMo-501 type", control box "DMC-2", control / analysis software "FAMAS (version)" 5.0.30) ”) is used to measure by the sessile drop method. The amount of distilled water dropped is 2 μL, and the contact angle is calculated by the Θ / 2 method from the image 5 seconds after dropping (implemented at N5). The water contact angle on the surface of the adherend is also measured by the same method.

[Rate of decrease in water peeling power]
The formula: peel strength A0 [N / 10 mm] and water peel strength A1 [N / 10 mm]:
Water peeling power reduction rate [%] = (1- (A1 / A0)) × 100;
If the rate of decrease in water peeling force is 70% or more, it is evaluated as "○", and if it is less than 70%, it is evaluated as "x".

<Example 1>
(Preparation of intermediate layer material)
A silicon oxide film is formed from a Si metal target manufactured by Mitsui Kinzoku Co., Ltd. on a PET film (PET-A; manufactured by Mitsubishi Chemical Co., Ltd., trade name "LC-N50JBN", thickness 50 μm) by RF (Radio-Frequency) magnetron sputtering. A film was formed. Argon and oxygen were used as the sputter gas, and the oxygen / argon ratio was 5.3 vol%. By adjusting the film formation time under the above conditions, a silicon oxide film (hydrophilic layer) having a thickness of 2 nm was formed on the PET film (main layer) to obtain an intermediate layer material A1 having a hydrophilic surface. When the water contact angle of this intermediate layer material A1 was measured, the water contact angle of the hydrophilic surface was 20 degrees, and the water contact angle of the non-hydrophilic surface (hydrophobic surface) on the opposite surface was 67 degrees. there were.

(Preparation of adhesive B1)
100 parts of a monomer mixture containing n-butyl acrylate (BA), cyclohexyl acrylate (CHA), and 4-hydroxybutyl acrylate (4HBA) in a weight ratio of 70/13/18 as a photopolymerization initiator, trade name: Irgacure 651. Put it into a four-mouthed flask together with 0.1 part (manufactured by Ciba Specialty Chemicals) and 0.1 part of trade name: Irgacure 184 (manufactured by Ciba Specialty Chemicals). A monomer syrup containing a partial polymer of the above-mentioned monomer mixture was prepared by irradiating with ultraviolet rays until the temperature (5 rotors, 10 rpm, measurement temperature: 30 ° C. ° C.) reached about 15 Pa · s and photopolymerizing. In 100 parts of this monomer syrup, 9 parts of 2-hydroxyethyl acrylate (HEA) and 8 parts of 4HBA, 0.1 part of dipentaerythritol hexaacrylate (DPHA) as a polyfunctional monomer, and a nonionic surfactant (polyoxyethylene sorbitan mono). Laurate, HLB16.7, trade name: Leodor TW-L120, manufactured by Kao Co., Ltd.) 0.3 part was added and mixed uniformly to prepare an ultraviolet curable pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition obtained above is applied to a release film R1 (MRF # 38, manufactured by Mitsubishi Materials Corporation) having a thickness of 38 μm in which one side of the polyester film is a release surface, and one side of the polyester film is used as the release surface. A 25 μm-thick pressure-sensitive adhesive layer B1 was formed by covering with a 38 μm-thick release film R2 (MRE # 38 manufactured by Mitsubishi Materials Co., Ltd.) to block air and irradiating with ultraviolet rays to cure the film.

(Preparation of adhesive B2)
A pressure-sensitive adhesive layer B2 having a thickness of 25 μm was formed in the same manner as in the preparation of the pressure-sensitive adhesive layer B1 except that a nonionic surfactant was not used.

(Making a double-sided adhesive sheet)
The release liner covering one surface of the pressure-sensitive adhesive layer B1 obtained above was peeled off, and the exposed pressure-sensitive adhesive surface was pressure-bonded to the hydrophilic surface of the intermediate layer material A1 obtained above by reciprocating a 2 kg rubber roller twice. Further, the peeling liner covering one surface of the adhesive layer B2 obtained above is peeled off, and the exposed adhesive surface is reciprocated twice with a 2 kg rubber roller on the opposite surface (hydrophobic surface) of the intermediate layer material A1. It was crimped. In this way, a structure (double-sided pressure-sensitive adhesive sheet with a release liner) having the structure of the pressure-sensitive adhesive layer B1 / intermediate layer A1 / pressure-sensitive adhesive layer B2 whose both sides were covered with the release liner was obtained.

(Making a joint)
A PET film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness 50 μm, width 20 mm, length 150 mm) was prepared as the first adherend, and an acrylic plate (manufactured by Mitsubishi Chemical Infratec) was prepared as the second adherend. , Product name "Acrylite L", thickness 2 mm) was prepared. The water contact angle of the first adherend surface (adhesion surface) and the water contact angle of the second adherend surface (adhesion surface) were both 67 degrees. The structure (double-sided adhesive sheet with a release liner) obtained above is cut to a width of 20 mm and a length of 50 mm, the release liner covering the adhesive layer B1 is peeled off, and the exposed adhesive surface is the first adherend (PET film). I pasted it on. At the time of bonding, the ends of the structure (double-sided adhesive sheet) and the first adherend in the length direction were aligned. Next, the release liner covering the pressure-sensitive adhesive layer B2 was peeled off, and the exposed pressure-sensitive adhesive surface was attached to the second adherend (acrylic plate). A 2 kg rubber roller was reciprocated twice and pressure-bonded to the obtained laminate of the adherend and the adhesive sheet. In this way, a structure (bonded body) having a structure of a first adherend / adhesive layer B1 / intermediate layer A1 / adhesive layer B2 / second adherend was obtained.

<Comparative Example 1>
As the pressure-sensitive adhesive layer on the hydrophilic surface side of the intermediate layer material A1, the pressure-sensitive adhesive layer B2 was used instead of the pressure-sensitive adhesive layer B1. Other than that, in the same manner as in Example 1, a structure (double-sided pressure-sensitive adhesive sheet with a release liner) having a structure of a pressure-sensitive adhesive layer B2 / intermediate layer A1 / pressure-sensitive adhesive layer B2 whose both sides were covered with a release liner was obtained.
Further, the configuration of the first adherend / adhesive layer B2 / intermediate layer A1 / adhesive layer B2 / second adherend is configured in the same manner as in Example 1 except that the double-sided adhesive sheet with a release liner is used. A structure (bonded body) having was obtained.

<Comparative Example 2>
As the intermediate layer material, the intermediate layer material A2 (PET film; manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness 50 μm) was used instead of the intermediate layer material A1. Other than that, in the same manner as in Example 1, a structure (double-sided pressure-sensitive adhesive sheet with a release liner) having a structure of a pressure-sensitive adhesive layer B1 / intermediate layer A2 / pressure-sensitive adhesive layer B2 whose both sides were covered with a release liner was obtained.
Further, the configuration of the first adherend / adhesive layer B1 / intermediate layer A2 / adhesive layer B2 / second adherend is configured in the same manner as in Example 1 except that the double-sided adhesive sheet with a release liner is used. A structure (bonded body) having was obtained.

<Comparative Example 3>
As the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer B1 produced by the same method as in Example 1 was used. The pressure-sensitive adhesive layer B1 was cut into a width of 20 mm and a length of 50 mm, the release liner covering one surface of the pressure-sensitive adhesive layer B1 was peeled off, and the exposed pressure-sensitive adhesive surface was attached to the first adherend (PET film). At the time of bonding, the ends of the adhesive sheet and the first adherend in the length direction were aligned. Next, the release liner covering the other surface of the pressure-sensitive adhesive layer B1 was peeled off, and the exposed pressure-sensitive adhesive surface was attached to the second adherend (acrylic plate). A 2 kg rubber roller was reciprocated twice and pressure-bonded to the obtained laminate of the adherend and the pressure-sensitive adhesive layer. In this way, a structure having a structure of a first adherend / adhesive layer B1 / second adherend was obtained. As the first adherend and the second adherend, those of the same type as those used in Example 1 were used.

<Performance evaluation>
For the structures (joints) according to Examples 1 and Comparative Examples 1 and 2, the peel strength (normal peeling force) A0 [N / 10 mm] and the water peeling force A1 [N / 10 mm] were measured, and the water peeling force decreased. The rate [%] was evaluated. In addition, the fractured part was also observed in the measurement of each peeling force. Regarding the structure (bonded body) according to Comparative Example 3, the same method as the above-mentioned peeling strength (normal peeling force) A0 and water peeling force A1 is applied to the adhesive surface between the first adherend and the pressure-sensitive adhesive layer B1. Then, the normal peeling force [N / 10 mm] and the water peeling force [N / 10 mm] were measured, and the water peeling force reduction rate [%] was evaluated. The results are shown in Table 1. Table 1 also shows an outline of each example.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above.

1,2,3,4,5,6,7,8

Structure

1A, 2A, 3A, 4A One surface (adhesive surface)
1B, 2B, 3B, 4B The other surface (adhesive surface)
11 First adhesive layer (layer A)
11A adhesive surface 11B surface (hydrophilic surface side surface)
12,120 Second

adhesive layer

12A,

120A Adhesive surface

12B, 120B surface (intermediate layer side surface)
13 First adhesive layer (layer A)
13A Adhesive surface 20,200 Intermediate layer (base material layer)
20A, 200A One side (hydrophilic surface)
20B, 200B Opposite surface 22 Main layer 24 Hydrophilic layer 25 Adhesive layer

non-existent area

31, 32, 33

Release liner

51, 52, 53, 54 Structure (double-sided adhesive sheet with release liner)
60 1st adherend 70 2nd adherend 80 Pickup tape 90 Extension 110 1st adhesive layer 110A One surface (adhesive surface)
110B The other surface (intermediate layer side surface)
112 A layer 114 B layer 400 set 410 First adhesive sheet 411 Adhesive layer (A layer)
420 Second adhesive sheet 420A One side (hydrophilic surface)
420B The other side (adhesive side)
420 The other side 422 Adhesive layer 425 Base material layer 425A One side (hydrophilic surface)
425B The other surface (adhesive layer side surface)
427 Main layer 428 Hydrophilic layer 431,432,433 Release liner 451,452 Adhesive sheet with release liner 500 set 510 First structure 511 Adhesive layer (layer A)
512 Adhesive body 520 Second structure 520A One surface (hydrophilic surface)
521 Adhesive layer 522 Adhesive body 525 Layer 525A with a hydrophilic surface One side (hydrophilic surface)
525B The other surface (adhesive layer side surface)
527 Main layer 528 Hydrophilic layer

Claims

A structure including a first pressure-sensitive adhesive layer, an intermediate layer, and a second pressure-sensitive adhesive layer in this order.
At least one surface of the intermediate layer is a hydrophilic surface.
At least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer.
After supplying 20 μL of distilled water between the intermediate layer and the A layer and allowing the distilled water to enter one end of the interface between the A layer and the intermediate layer, JIS Z0237: 2009 10.4. 1. Method 1: Water peeling force A1 [N] measured at a test temperature of 23 ° C, with a tensile speed of 300 mm / min and a peeling angle of 180 °, according to the 180 ° peeling adhesive force to the test plate. / 10 mm] and the peel strength A0 [N / 10 mm] of the pressure-sensitive adhesive layer having the A layer with respect to the intermediate layer, water peeling calculated by the following formula: (1- (A1 / A0)) × 100 ;. A structure having a force reduction rate of 70% or more.
The structure according to claim 1, which is a double-sided adhesive sheet.
The structure according to claim 1 or 2, wherein the water contact angle of the hydrophilic surface of the intermediate layer is 30 degrees or less.
The structure according to any one of claims 1 to 3, wherein the hydrophilic surface of the intermediate layer has a region where the adhesive layer does not exist at the end of the intermediate layer.
The structure according to any one of claims 1 to 4, wherein the intermediate layer has a hydrophilic layer constituting the hydrophilic surface.
The structure according to claim 5, wherein the hydrophilic layer is an inorganic oxide-containing layer.
The structure according to any one of claims 1 to 6, wherein the layer A is a layer formed of a photocurable or solvent-type pressure-sensitive adhesive composition.
The structure according to any one of claims 1 to 7, wherein the layer A contains a water affinity agent.
The structure according to any one of claims 1 to 8, which is attached to a surface having a water contact angle of 40 degrees or more.
A release liner comprising the structure according to any one of claims 1 to 9 and at least one release liner that protects the adhesive surface of the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer. Double-sided adhesive sheet with.
The structure according to any one of claims 1 to 8, further comprising a first adherend that adheres to the first pressure-sensitive adhesive layer and a second adherend that adheres to the second pressure-sensitive adhesive layer. body.
Of the first adherend and the second adherend, the adherend that adheres to the pressure-sensitive adhesive layer having the A layer has a water contact angle of 40 degrees or more on the surface to which the pressure-sensitive adhesive layer adheres. The structure according to claim 11.
A method of separating the joined first adherend and the second adherend.
The first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order between the first adherend and the second adherend that have been joined.
At least one surface of the intermediate layer is a hydrophilic surface.
At least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer.
The method includes a step of peeling the pressure-sensitive adhesive layer having the A layer from the intermediate layer.
Here, in the step of peeling the pressure-sensitive adhesive layer from the intermediate layer, an aqueous liquid is present at the interface between the intermediate layer and the pressure-sensitive adhesive layer in the peeling front of the pressure-sensitive adhesive layer from the intermediate layer. A method, which is a water peeling step of peeling the pressure-sensitive adhesive layer from the intermediate layer while advancing the invasion of the aqueous liquid into the interface following the movement of the peeling front.
It is a method of separating the joined first adherend and the second adherend and joining the third adherend to the second adherend.
The first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer are arranged in this order between the first adherend and the second adherend that have been joined.
At least one surface of the intermediate layer is a hydrophilic surface.
At least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has an A layer arranged on the hydrophilic surface of the intermediate layer.
The method is
A step of peeling the pressure-sensitive adhesive layer having the A layer from the intermediate layer to separate the first adherend and the second adherend.
A step of joining the third adherend to the second adherend with an adhesive sheet,
Including
Here, in the step of peeling the pressure-sensitive adhesive layer from the intermediate layer, an aqueous liquid is present at the interface between the intermediate layer and the pressure-sensitive adhesive layer in the peeling front of the pressure-sensitive adhesive layer from the intermediate layer. A method, which is a water peeling step of peeling the pressure-sensitive adhesive layer from the intermediate layer while advancing the invasion of the aqueous liquid into the interface following the movement of the peeling front.
After the pressure-sensitive adhesive layer having the A layer is peeled off from the intermediate layer, the intermediate layer remains in the second adherend.
The pressure-sensitive adhesive sheet used for joining the third adherend to the second adherend includes an adhesive layer having an A layer, and is an alkaline glass plate produced by a float method as an adherend. The A layer side is attached to a surface having a contact angle of 5 to 10 degrees with respect to the distilled water, and after 1 day at room temperature, 20 μL of the distilled water is dropped onto the adherend, and the distilled water is applied to the A layer and the said. After entering one end of the interface with the adherend, JIS Z 0237: 2009 10.4.1 Method 1: 180 ° peeling off to the test plate According to the adhesive force, using a tensile tester at a test temperature of 23 ° C. The contact angle of the water peeling force B1 [N / 10 mm] measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees and the alkaline glass plate manufactured by the float method as an adherend to distilled water is 5. It is calculated by the following formula: (1- (B1 / B0)) × 100; from the adhesive strength B0 [N / 10 mm] one day after the A layer side is attached to the surface having a degree to 10 degrees. The method according to claim 14, wherein the rate of decrease in water peeling is 70% or more.
A set including a first adhesive sheet and a second adhesive sheet,
The first pressure-sensitive adhesive sheet contains a pressure-sensitive adhesive layer and contains a pressure-sensitive adhesive layer.
The second pressure-sensitive adhesive sheet comprises a base material layer and a pressure-sensitive adhesive layer provided on one surface of the base material layer, and at least one surface of the base material layer is a hydrophilic surface.
The pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet has an A layer to be attached to the hydrophilic surface, or the pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet has an A layer provided on the hydrophilic surface. Or, or both, a set.
An adhesive sheet used in the set according to claim 16.
A pressure-sensitive adhesive sheet comprising a base material layer and a pressure-sensitive adhesive layer provided on one surface of the base material layer, wherein at least one surface of the base material layer is a hydrophilic surface.
An adhesive sheet used in the set according to claim 16.
The pressure-sensitive adhesive sheet contains a pressure-sensitive adhesive layer having an A layer.
The layer A side was attached to a surface of an alkaline glass plate produced by the float method as an adherend having a contact angle of 5 to 10 degrees with respect to distilled water, and after 1 day at room temperature, 20 μL of distillation was performed on the adherend. After dropping water and allowing the distilled water to enter one end of the interface between the A layer and the adherend, JIS Z 0237: 2009 10.4.1 Method 1: 180 ° peeling adhesive force to the test plate. According to the above, a water peeling force B1 [N / 10 mm] measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees using a tensile tester at a test temperature of 23 ° C. and a float method as an adherend are used. The A layer side was attached to the surface of the alkaline glass plate having a contact angle of 5 to 10 degrees with respect to distilled water, and the adhesive strength was B0 [N / 10 mm] one day after room temperature. -(B1 / B0)) × 100; The pressure-sensitive adhesive sheet having a water peeling reduction rate of 70% or more.
A set including a first structure and a second structure,
The first structure has a first adherend and a first pressure-sensitive adhesive layer.
The second structure has a second adherend, a second pressure-sensitive adhesive layer, and a layer having a hydrophilic surface in this order.
The first pressure-sensitive adhesive layer has an A layer attached to the hydrophilic surface, the second pressure-sensitive adhesive layer has an A layer provided on the hydrophilic surface, or both. Is a set.
A structure used in the set according to claim 19.
A structure having an adherend, an adhesive layer, and a layer having a hydrophilic surface in this order.
A structure used in the set according to claim 19.
It has an adherend and an adhesive layer,
The pressure-sensitive adhesive layer has an A layer and has an A layer.
The layer A side was attached to a surface of an alkaline glass plate produced by the float method as an adherend having a contact angle of 5 to 10 degrees with respect to distilled water, and after 1 day at room temperature, 20 μL of distillation was performed on the adherend. After dropping water and allowing the distilled water to enter one end of the interface between the A layer and the adherend, JIS Z 0237: 2009 10.4.1 Method 1: 180 ° peeling adhesive force to the test plate. According to the above, a water peeling force B1 [N / 10 mm] measured under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees using a tensile tester at a test temperature of 23 ° C. and a float method as an adherend are used. The A layer side was attached to the surface of the alkaline glass plate having a contact angle of 5 to 10 degrees with respect to distilled water, and the adhesive strength was B0 [N / 10 mm] one day after room temperature. -(B1 / B0)) x 100; the structure having a water separation reduction rate of 70% or more.