Easily dismantlable adhesive sheet, laminated structure, and dismantling method

Abstract

This easily dismantlable adhesive sheet (100) comprises an adhesive layer (10) containing a moisture-cured product of a silyl group-containing resin and a terpene phenolic tackifying resin, wherein the silyl group-containing resin has a polyoxyalkylene structure in a main chain, has, in a portion of the main chain or a side chain, both bonds among a urethane bond and a urea bond or one bond among the urethane bond and the urea bond, and has hydrolyzable silyl groups represented by formula (1) at both ends of the main chain. (In formula (1), X1 and X2 are each independently a hydroxy group or an alkoxy group, R is a C1-C20 alkyl group, and * is a bonding position.)

Description

Easily dismantled adhesive sheet, laminated structure, and dismantling method

[0001] The present invention relates to an easily dismantlable pressure-sensitive adhesive sheet, a laminated structure, and a dismantling method.

[0002] Pressure-sensitive adhesive sheets are used in a variety of applications, including, for example, bonding various components that constitute products in fields such as office automation equipment, home appliances, automobiles, and construction.

[0003] In recent years, with the aim of building a recycling-oriented society, there has been a demand for the reuse of used products. Used products include composite members in which various components are bonded together, and when recycling used products, for example, separation of the composite members in the used products is required. When the composite member included in the used product has various components as adherends bonded together with an adhesive, it becomes difficult to separate the bonded adherends, making it difficult to easily dismantle the composite member. For this reason, for example, Patent Documents 1 and 2 propose pressure-sensitive adhesive tapes containing acrylic pressure-sensitive adhesive compositions that take into consideration the separability from the adherends.

[0004] Patent Document 1 discloses an acrylic pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive composition characterized by comprising an acrylic polymer (A), a (meth)acrylic polymer (B) having a weight-average molecular weight (Mw) of 1,000 or more and less than 30,000, and thermally expandable microspheres (C).

[0005] Patent Document 2 discloses an easily dismantlable adhesive tape having an adhesive layer made of an adhesive composition containing an acrylic polymer and an acid catalyst or an acid generator. In the adhesive composition described in Patent Document 2, the acrylic polymer contains, as monomer components, a (meth)acrylate having an alkyl group having 1 to 14 carbon atoms and a hydroxyl group-containing vinyl monomer, the content of the hydroxyl group-containing vinyl monomer being 10 mass% or more of the monomer components constituting the acrylic polymer, and the acrylic polymer is an acrylic random polymer having a mass average molecular weight of 100,000 or more.

[0006] JP 2011-231319 A JP 2014-080524 A

[0007] For example, a composite member having a pressure-sensitive adhesive layer formed using an acrylic pressure-sensitive adhesive composition may be able to be disassembled by heating by reducing the adhesive strength of the pressure-sensitive adhesive layer at high temperatures. However, when disassembling a composite member bonded with a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of such an acrylic pressure-sensitive adhesive composition, when the pressure-sensitive adhesive layer is separated from the adherend, cohesive failure of the pressure-sensitive adhesive layer may occur, resulting in adhesive residue on the adherend. For this reason, it may be difficult to disassemble a composite member bonded with a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive composition. On the other hand, while improving the crosslink density of the pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive composition can prevent adhesive residue from being left on the adherend, the adhesive strength at room temperature is likely to decrease. For this reason, further improvements have been required for pressure-sensitive adhesive sheets that can be easily separated from the adherend.

[0008] An object of the present invention is to provide an easily dismantled adhesive sheet that maintains its adhesive strength to an adherend at room temperature while reducing adhesive residue when separated from the adherend, a laminated structure using the easily dismantled adhesive sheet, and a method for dismantling the laminated structure.

[0009] [1] An easily dismantlable pressure-sensitive adhesive sheet, comprising a pressure-sensitive adhesive layer containing a moisture-cured product of a silyl group-containing resin and a terpene phenol-based tackifying resin, wherein the silyl group-containing resin has a polyoxyalkylene structure in its main chain, and has both a urethane bond and a urea bond, or has either the urethane bond or the urea bond, in a part of the main chain or in a side chain, and has hydrolyzable silyl groups represented by the following formula (1) at both ends of the main chain:

[0010]

[0011] (In the formula (1), X １ and X ２ are each independently a hydroxy group or an alkoxy group, R is an alkyl group having 1 to 20 carbon atoms, and * indicates the bonding position.

[0012] [2] The easily dismantlable pressure-sensitive adhesive sheet according to [1], wherein the content of the terpene phenol-based tackifier resin is 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

[0013] [3] The easily dismantlable pressure-sensitive adhesive sheet according to [1] or [2], wherein the pressure-sensitive adhesive layer further comprises an acrylic tackifier resin, and the content of the acrylic tackifier resin is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

[0014] [4] The easily dismantlable pressure-sensitive adhesive sheet according to [3], wherein the weight average molecular weight Mw of the acrylic tackifier resin is 300 or more and 10,000 or less.

[0015] [5] The easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [4], further comprising a release liner provided on at least one surface of the pressure-sensitive adhesive layer.

[0016] [6] The easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [5], comprising: a substrate; and the pressure-sensitive adhesive layer provided on at least one surface of the substrate.

[0017] [7] A laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [6], which is provided between the first adherend and the second adherend and is attached to the first adherend and the second adherend.

[0018] [8] A dismantling method for dismantling a laminated structure, comprising: a step of preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [5], which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; a step of bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then separating the first adherend and the second adherend from the easily dismantled pressure-sensitive adhesive sheet before the temperature drops to the atmospheric temperature of a dismantling work environment, wherein the easily dismantled pressure-sensitive adhesive sheet consists only of the pressure-sensitive adhesive layer.

[0019] [9] A dismantling method for dismantling a laminated structure, comprising: a step of preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [5], which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; a step of bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then, during the time until the temperature is lowered to the ambient temperature of the dismantling work environment, not separating one of the first adherend or the second adherend from the easily dismantled adhesive sheet, and separating the other of the first adherend or the second adherend that has not been separated from the easily dismantled adhesive sheet from the easily dismantled adhesive sheet, wherein the easily dismantled adhesive sheet consists of only the adhesive layer.

[0020]

[10] A dismantling method for dismantling a laminated structure, comprising: a step of preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [6], which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; a step of bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then separating the first adherend and the second adherend from the easily dismantled pressure-sensitive adhesive sheet before the temperature drops to the atmospheric temperature of a dismantling work environment, wherein the easily dismantled pressure-sensitive adhesive sheet comprises a substrate and the pressure-sensitive adhesive layers provided on both sides of the substrate.

[0021]

[11] A dismantling method for dismantling a laminated structure, comprising: a step of preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable pressure-sensitive adhesive sheet according to any one of [1] to [6], which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; a step of bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then separating one of the first adherend or the second adherend from the easily dismantled adhesive sheet, and separating the other of the first adherend or the second adherend that has not been separated from the easily dismantled adhesive sheet, from the easily dismantled adhesive sheet, during the time until the temperature of the laminated structure is reduced to the ambient temperature of the dismantling work environment, wherein the easily dismantled adhesive sheet comprises a substrate and the adhesive layers provided on both sides of the substrate.

[0022] According to one aspect of the present invention, there are provided an easily dismantled adhesive sheet that maintains its adhesive strength to an adherend at room temperature while reducing adhesive residue when separated from the adherend, a laminated structure using the easily dismantled adhesive sheet, and a method for dismantling the laminated structure.

[0023] FIG. 1 is a schematic cross-sectional view showing an example of the easily dismantlable pressure-sensitive adhesive sheet according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing another example of the easily dismantlable pressure-sensitive adhesive sheet according to the first embodiment. FIG. 3 is a schematic cross-sectional view showing another example of the easily dismantlable pressure-sensitive adhesive sheet according to the first embodiment. FIG. 4 is a schematic cross-sectional view showing an example of a laminate structure according to the second embodiment. FIG. 5 is a schematic cross-sectional view showing another example of the laminate structure according to the second embodiment. FIG. 6 is a schematic explanatory view showing an example of a method for dismantling a laminate structure according to a third embodiment. FIG. 7 is a schematic explanatory view showing an example of a method for dismantling a laminate structure according to the third embodiment. FIG. 8 is a schematic explanatory view showing an example of a method for dismantling a laminate structure according to the third embodiment. FIG. 9 is a schematic explanatory view showing an example of a method for dismantling a laminate structure according to the third embodiment. FIG. 10 is a schematic explanatory view showing another example of a method for dismantling a laminate structure according to the third embodiment. FIG. 11 is a schematic explanatory view showing another example of a method for dismantling a laminate structure according to the third embodiment.

[0024] An example of a preferred embodiment of the present invention will be described below.

[0025] [First embodiment] <Easily dismantlable adhesive sheet> The first embodiment is an easily dismantlable adhesive sheet (easily dismantlable adhesive sheet). The easily dismantlable adhesive sheet according to this embodiment comprises an adhesive layer containing a moisture-cured product of a silyl group-containing resin and a terpene phenol-based tackifier resin. The silyl group-containing resin has a polyoxyalkylene structure in its main chain, and has both a urethane bond and a urea bond in part of the main chain or in a side chain, or has either the urethane bond or the urea bond, and has hydrolyzable silyl groups represented by the following formula (1) at both ends of the main chain.

[0026]

[0027] (In the formula (1), X １ and X ２ are each independently a hydroxy group or an alkoxy group, R is an alkyl group having 1 to 20 carbon atoms, and * indicates the bonding position.

[0028] The adhesive layer of the easily dismantlable adhesive sheet according to this embodiment contains a moisture-cured product of a silyl group-containing resin. The moisture-cured product of the silyl group-containing resin is moisture-cured in advance. The easily dismantlable adhesive sheet according to this embodiment is used by attaching the adhesive layer to an adherend. "Pre-moisture-cured" refers to a state in which the silyl group-containing resin contained in the adhesive layer formed from an adhesive composition containing the silyl group-containing resin has already been moisture-cured in the easily dismantlable adhesive sheet according to this embodiment. Therefore, the adhesive layer in the easily dismantlable adhesive sheet according to this embodiment differs from an adhesive layer formed by coating an adherend with an adhesive composition before moisture curing. For example, an adhesive layer containing a silyl group-containing resin that has been moisture-cured in advance and an adhesive layer formed by coating an adherend with an adhesive composition before moisture curing have different storage moduli when measured under the same conditions for the adhesive layer before and after moisture curing. The storage modulus of the pressure-sensitive adhesive layer containing the silyl group-containing resin that has been moisture-cured in advance is, for example, 70,000 Pa or more at room temperature (for example, 23° C.).

[0029] By virtue of the above-described configuration, the easily dismantlable adhesive sheet according to this embodiment maintains its adhesive strength to an adherend at room temperature while suppressing adhesive residue when separated from the adherend. Specifically, the easily dismantlable adhesive sheet according to this embodiment exhibits high adhesive strength to the adherend at room temperature (e.g., 23°C). Here, room temperature refers to the temperature at which the laminate structure is not heated by a heating means or the like, and examples include a temperature range of about 15°C or higher and 30°C or lower. Furthermore, when the easily dismantlable adhesive sheet according to this embodiment is attached to an adherend and then heated from the adherend side to a high temperature (e.g., 80°C or higher), adhesive residue on the adherend is suppressed when the easily dismantlable adhesive sheet and the adherend are separated. Therefore, when adherends are bonded using the easily dismantlable adhesive sheet according to this embodiment, the adherend and the easily dismantlable adhesive sheet maintain high adhesive strength at room temperature, and when the adherend and the easily dismantlable adhesive sheet are separated between heating the adherend bonded using the easily dismantlable adhesive sheet according to this embodiment and cooling to the ambient temperature of the dismantling work environment, the occurrence of adhesive residue on the adherend is suppressed. Therefore, by using the easily dismantlable adhesive sheet according to this embodiment, it is easy to dismantle a laminated structure including adherends bonded by the easily dismantlable adhesive sheet according to this embodiment, and the adherends can be recovered without leaving any adhesive layer. As a result, composite members using the easily dismantlable adhesive sheet according to this embodiment can be easily reused.

[0030] In one aspect, the easily dismantlable pressure-sensitive adhesive sheet according to this embodiment may include a release liner provided on at least one surface of the pressure-sensitive adhesive layer.

[0031] In one aspect, the easily dismantlable pressure-sensitive adhesive sheet according to the present embodiment may include a substrate and the pressure-sensitive adhesive layer provided on at least one surface of the substrate.

[0032] The easily dismantlable pressure-sensitive adhesive sheet according to the present embodiment will be described below with reference to the drawings, in which some parts are shown enlarged or reduced in size for ease of explanation.

[0033] [First Aspect] A first aspect of the easily dismantlable adhesive sheet according to this embodiment is an easily dismantlable adhesive sheet consisting solely of the above-described adhesive layer. FIG. 1 shows a schematic cross-sectional view illustrating an example of an easily dismantlable adhesive sheet. As shown in FIG. 1, the easily dismantlable adhesive sheet 100 is composed solely of an adhesive layer 10. The adhesive layer 10 includes a moisture-cured product of a silyl group-containing resin as component (A) and a terpene phenol-based tackifier resin as component (B). The moisture-cured product of the silyl group-containing resin is formed by pre-curing the silyl group-containing resin through moisture. The silyl group-containing resin can be cured by reacting with moisture in the air, and can be moisture-cured with moisture in the air, for example, at room temperature or a temperature higher than room temperature. The adhesive layer 10 includes a first main surface 10A of the adhesive layer 10 and a second main surface 10B opposite the first main surface 10A. The main surface refers to the largest surface of the easily dismantlable adhesive sheet 100 and faces in the thickness direction. The thickness of the pressure-sensitive adhesive layer 10 corresponds to the distance between the first main surface 10A and the second main surface 10B of the pressure-sensitive adhesive layer 10. For convenience, the terms first main surface 10A and second main surface 10B are used to clarify the positional relationship between one side and the other side of the easily dismantlable pressure-sensitive adhesive sheet 100, but in some cases, the first main surface 10A and the second main surface 10B can be used interchangeably, and the first main surface 10A and the second main surface 10B can be used interchangeably. The same applies to the main surface in the following description.

[0034] (Silyl Group-Containing Resin) The silyl group-containing resin has the following elements (a), (b), and (c). Element (a): It has a polyoxyalkylene structure in the main chain. Element (b): It has both a urethane bond and a urea bond, or either the urethane bond or the urea bond, in part of the main chain or in a side chain. Element (c): It has hydrolyzable silyl groups represented by the formula (1) at both ends of the main chain.

[0035] The above element (b) corresponds to any one of the following elements (b-1), (b-2), (b-3), or (b-4). Element (b-1): Having both a urethane bond and a urea bond in a part of the main chain. Element (b-2): Having either the urethane bond or the urea bond in a part of the main chain. Element (b-3): Having both the urethane bond and the urea bond in a side chain. Element (b-4): Having either the urethane bond or the urea bond in a side chain.

[0036] The silyl group-containing resin having the elements (a), (b), and (c) is a silyl group-containing resin before moisture curing. When the silyl group-containing resin is moisture-cured, the hydrolyzable silyl groups represented by the formula (1) undergo hydrolysis and dehydration condensation. Therefore, in the moisture-cured product of the silyl group-containing resin, the hydrolyzable silyl groups represented by the formula (1) are almost not contained. In this specification, unless otherwise specified, when the term "silyl group-containing resin" is used, it refers to the silyl group-containing resin before moisture curing, and when the term "moisture-cured product of the silyl group-containing resin" or a similar term is used, it refers to the silyl group-containing resin after moisture curing.

[0037] In the formula (1), R is an alkyl group having 1 to 20 carbon atoms. From the viewpoint of reactivity in hydrolysis-dehydration-condensation, R in the formula (1) is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, even more preferably an alkyl group having 1 to 3 carbon atoms, and still more preferably an alkyl group having 1 to 2 carbon atoms.

[0038] In the formula (1), X １ and X ２ are each independently a hydroxy group or an alkoxy group. １ and X ２When at least one of the groups is an alkoxy group, the alkoxy group is preferably an alkoxy group having 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms, even more preferably an alkoxy group having 1 to 3 carbon atoms, and still more preferably an alkoxy group having 1 to 2 carbon atoms, from the viewpoint of reactivity in hydrolysis-dehydration condensation.

[0039] The silyl group-containing resin can be synthesized, for example, by using as raw materials a urethane prepolymer having an isocyanate group obtained by reacting a polyol with a polyvalent isocyanate compound, and a silylating agent having a hydrolyzable silyl group represented by the formula (1) and an active hydrogen group capable of reacting with an isocyanate group, mixing the urethane prepolymer and the silylating agent, and reacting them under predetermined conditions (e.g., 80°C for 1 hour) in a nitrogen atmosphere. The reaction can be carried out by detecting the absorption peak of the isocyanate group (2265 cm) measured by infrared spectroscopy (IR). －１ The silyl group-containing resin is cured by a crosslinking reaction via hydrolysis of the hydrolyzable silyl group represented by the formula (1) to form a three-dimensional network structure.

[0040] The synthesis of the silyl group-containing resin is not limited to the reaction between the urethane prepolymer and the silylating agent, but the silyl group-containing resin can also be synthesized, for example, by reacting a silylating agent having an isocyanate group with a polymer having an active hydrogen group.

[0041] The active hydrogen atoms in both the urethane bond and the urea bond, or either the urethane bond or the urea bond, which are introduced into a part of the main chain or into a side chain of the silyl group-containing resin, may be substituted with an organic group. Therefore, allophanate bonds are included in the category of urethane bonds, and biuret bonds are also included in the category of urea bonds.

[0042] From the viewpoint of strengthening the bonding strength to the adherend, the specific structure of the terminal portion of the silyl group-containing resin is preferably at least one structure selected from the group consisting of the following formulas (11), (12), (13), (14), (15), (16), and (17):

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050] (In the formulas (11), (12), (13), and (14), X １ and X ２ are each independently a hydroxy group or an alkoxy group, R is an alkyl group having 1 to 20 carbon atoms, and R Ａ and R Ｂ are each independently an alkyl group having 1 to 20 carbon atoms, * is a bonding position, and in the formulas (15) and (16), X １ and X ２ are each independently a hydroxy group or an alkoxy group, R is an alkyl group having 1 to 20 carbon atoms, * is a bonding position, and in the formula (17), X １ and X ２ are each independently a hydroxy group or an alkoxy group, R is an alkyl group having 1 to 20 carbon atoms, L is an alkylene group having 1 to 20 carbon atoms, and R Ｃ is an organic group having 1 to 20 carbon atoms, and * is a bonding position.

[0051] In the formula (17), R Ｃis preferably an alkyl group having 1 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, a heterocyclic group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms.

[0052] From the viewpoint of exhibiting high adhesive strength to an adherend and high elastic modulus at room temperature, the silyl group-containing resin is preferably a silyl group-containing resin that does not have a hydrolyzable silyl group represented by formula (1) in the side chain, but has hydrolyzable silyl groups represented by formula (1) only at both ends of the main chain. If the silyl group-containing resin does not have a hydrolyzable silyl group represented by formula (1) in the side chain, but has hydrolyzable silyl groups represented by formula (1) only at both ends of the main chain, the crosslink density between the silyl group-containing resins can be adjusted to an appropriate range, and the compatibility between the silyl group-containing resin and the tackifier resin can be more easily adjusted to a suitable range.

[0053] The silyl group-containing resin has a polyoxyalkylene structure in its main chain. If the silyl group-containing resin has a polyoxyalkylene structure in its main chain, the pressure-sensitive adhesive layer 10 can have appropriate flexibility and can further improve adhesive strength to an adherend. The polyoxyalkylene structure is not particularly limited, and examples include polyoxypropylene, polyoxyethylene, and combinations thereof. The polyoxyalkylene structure may be present not only in the main chain of the silyl group-containing resin, but also in the main chain and side chains.

[0054] The weight average molecular weight Mw of the silyl group-containing resin is preferably 10,000 (10,000) or more and preferably 200,000 (200,000) or less, from the viewpoint of ease of forming the pressure-sensitive adhesive layer 10 and from the viewpoint of having high adhesive strength to the adherend at room temperature. The weight average molecular weight Mw of the silyl group-containing resin may be 12,000 (12,000) or more, or may be 15,000 (15,000) or more. The weight average molecular weight Mw of the silyl group-containing resin may be 150,000 (150,000) or less, or may be 100,000 (100,000) or less. The weight average molecular weight Mw of the silyl group-containing resin can be measured under specified conditions using a known molecular weight measuring device such as gel permeation chromatography (GPC).

[0055] The easily dismantlable adhesive sheet according to this embodiment is thought to suppress adhesive residue on an adherend when the easily dismantlable adhesive sheet according to this embodiment is separated from the adherend due to the high cohesive strength of the silyl group-containing resin contained in the adhesive layer. From the viewpoint of suppressing adhesive residue when the easily dismantlable adhesive sheet according to this embodiment is separated from the adherend while maintaining adhesive strength to the adherend at room temperature, the content of the silyl group-containing resin is preferably 20% by mass or more and 90% by mass or less relative to the entire adhesive layer 10 (100% by mass). The content of the silyl group-containing resin is more preferably 25% by mass or more, and even more preferably 30% by mass or more, relative to the entire adhesive layer 10 (100% by mass). The content of the silyl group-containing resin is more preferably 80% by mass or less, and even more preferably 75% by mass or less, relative to the entire adhesive layer 10 (100% by mass).

[0056] (Terpene phenol-based tackifying resin) The pressure-sensitive adhesive layer 10 contains a terpene phenol-based tackifying resin. The terpene phenol-based tackifying resin has excellent compatibility with silyl group-containing resins. When the pressure-sensitive adhesive layer 10 contains a terpene phenol-based tackifying resin, the adhesive strength to an adherend at room temperature is improved. The terpene phenol-based tackifying resin is a copolymer of a terpene resin and phenol, and has a terpene-derived double bond and a phenol-derived aromatic ring double bond. The terpene phenol-based tackifying resin may be a fully hydrogenated terpene phenol-based tackifying resin or a partially hydrogenated terpene phenol-based tackifying resin.

[0057] The fully hydrogenated terpene phenolic tackifier resin is a tackifier resin obtained by substantially completely hydrogenating a terpene phenolic tackifier resin. The fully hydrogenated terpene phenolic tackifier resin refers to a tackifier resin in which both the terpene moiety and the phenol moiety have been completely or nearly completely hydrogenated. The partially hydrogenated terpene phenolic tackifier resin is a tackifier resin obtained by partially hydrogenating a terpene phenolic tackifier resin. The partially hydrogenated terpene phenolic tackifier resin refers to a tackifier resin in which both the terpene moiety and the phenol moiety have been partially hydrogenated without being completely or nearly completely hydrogenated. The method for hydrogenating the terpene phenolic tackifier resin is not particularly limited. From the viewpoint of improving adhesive strength to an adherend at room temperature, the hydrogenation ratio of the terpene phenolic tackifier resin may be, for example, 50 mol% or more, 65 mol% or more, 80 mol% or more, or 100 mol% or less, relative to 100 mol% of unsaturated bonds in the terpene phenolic resin. The terpene phenol resins may be used alone or in combination of two or more.

[0058] Whether the tackifying resin is a fully hydrogenated terpene phenol-based resin or a partially hydrogenated terpene phenol-based resin can be determined using an FT-IR spectrum obtained by a Fourier transform infrared spectrophotometer (FT-IR). Specifically, the FT-IR spectrum of about 2960 cm originating from the carbon-hydrogen bond stretching vibration of the methyl group can be determined. －１ When the height of the peak at 1625 cm is taken as 100, the peak at 1625 cm is due to the stretching vibration of the aromatic carbon-carbon double bond of the phenol moiety. －１ Above, 1575cm －１ This can be determined by the height of the following peaks:

[0059] The softening point of the terpene phenol-based tackifying resin is not particularly limited, and from the viewpoint of improving adhesive strength to an adherend at room temperature, it may be, for example, 110° C. or higher and 180° C. or lower. The softening point of the terpene phenol-based tackifying resin can be measured, for example, by filling a support ring with a sample, placing a ball of a certain weight in the center of the support ring in a water or glycerin bath, raising the bath temperature at a specified rate, and then measuring the temperature at which the sample sags due to the weight of the ball (ring and ball method).

[0060] From the viewpoint of improving adhesive strength to an adherend at room temperature, the content of the terpene phenol-based tackifying resin is preferably 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the silyl group-containing resin. The content of the terpene phenol-based tackifying resin is more preferably 30 parts by mass or more, even more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more per 100 parts by mass of the silyl group-containing resin. The content of the terpene phenol-based tackifying resin is more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

[0061] (Acrylic Tackifier Resin) The pressure-sensitive adhesive layer 10 contains a moisture-cured product of a silyl group-containing resin as component (A) and a terpene phenol-based tackifier resin as component (B), and may further contain an acrylic tackifier resin as component (C). When the pressure-sensitive adhesive layer 10 contains an acrylic tackifier resin, the adhesive strength to an adherend at room temperature is likely to be improved.

[0062] The acrylic tackifier resin is, for example, composed of a (meth)acrylic acid ester polymer. Examples of the (meth)acrylic acid ester polymer include polymers using a (meth)acrylic acid alkyl ester as a monomer, in which the alkyl group has 1 or more and 20 or less carbon atoms. The (meth)acrylic acid alkyl ester may have an alicyclic structure in the molecule. The (meth)acrylic acid ester polymer may be a homopolymer of a (meth)acrylic acid ester or a copolymer of a (meth)acrylic acid ester. The (meth)acrylic acid ester copolymer may be a copolymer of a (meth)acrylic acid ester monomer and another monomer. The acrylic tackifier resin may contain a functional group such as a carboxy group, but it does not have to contain a functional group such as a carboxy group, in order to facilitate disassembly of the laminated structure.

[0063] In this specification, "(meth)acrylic" means both acrylic and methacrylic, and the same applies to other similar terms.

[0064] Examples of acrylic acid alkyl ester monomers constituting the (meth)acrylic acid ester polymer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. One type of (meth)acrylic acid alkyl ester may be used alone, or two or more types may be used in combination.

[0065] When the (meth)acrylic acid ester polymer is a copolymer, examples of the other monomers constituting the (meth)acrylic acid ester polymer include a carboxyl group-containing vinyl monomer, a hydroxyl group-containing vinyl monomer, a vinyl ether monomer, a nitrogen-containing vinyl monomer, an aromatic vinyl monomer, and a vinyl ester monomer. One type of the other monomer may be used alone, or two or more types of the same type of monomer may be used in combination. Two or more types of different types of monomers may be used in combination.

[0066] Examples of carboxyl group-containing vinyl monomers include maleic (meth)acrylate, itaconic acid, monomethyl maleate, monomethyl citraconic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, mono(2-acryloyloxyethyl) succinate, and mono(2-methacryloyloxyethyl) succinate. Examples of hydroxyl group-containing vinyl monomers include hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of vinyl ether monomers include hydroxybutyl vinyl ether. Examples of nitrogen-containing vinyl monomers include monomethylaminoethyl (meth)acrylate, acrylamide, and acryloylmorpholine. Examples of aromatic vinyl monomers include olefins such as ethylene and propylene, as well as styrene. Examples of vinyl ester monomers include vinyl acetate.

[0067] The (meth)acrylic acid ester copolymer can be produced by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. The (meth)acrylic acid ester copolymer may be a (meth)acrylic acid ester oligomer from the viewpoint of improving adhesive strength to an adherend at room temperature.

[0068] The weight average molecular weight Mw of the acrylic tackifier resin is preferably 300 or more and 10,000 or less. The weight average molecular weight Mw of the acrylic tackifier resin is more preferably 500 or more, even more preferably 800 or more, and even more preferably 1,000 or more. The weight average molecular weight Mw of the acrylic tackifier resin is more preferably 8,000 or less, even more preferably 6,000 or less, and even more preferably 4,000 or less. The weight average molecular weight Mw of the acrylic tackifier resin can be measured under specified measurement conditions using a known molecular weight measuring device such as gel permeation chromatography (GPC).

[0069] The softening point of the acrylic tackifier resin is not particularly limited, and from the viewpoint of improving adhesive strength to an adherend at room temperature, it may be, for example, 120° C. or higher and 190° C. or lower. The softening point of the acrylic tackifier resin can be determined, for example, by the same measurement method as for the softening point of the terpene phenol tackifier resin described above.

[0070] From the viewpoint of improving adhesive strength to an adherend at room temperature, the content of the acrylic tackifier resin is preferably 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the silyl group-containing resin. The content of the acrylic tackifier resin is more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more per 100 parts by mass of the silyl group-containing resin. The content of the acrylic tackifier resin is preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

[0071] (Fluorine Catalyst) The pressure-sensitive adhesive layer 10 may contain a moisture-cured product of a silyl group-containing resin as component (A) and a terpene phenol-based tackifying resin as component (B), and may further contain a fluorine catalyst as component (D). The fluorine catalyst may be used as a fluorine catalyst solution in which a silane coupling agent is used as component (E) described below, or the fluorine catalyst alone may be used.

[0072] When the pressure-sensitive adhesive layer 10 contains a fluorine catalyst, it may contain a moisture-cured product of a silyl group-containing resin as the component (A), a terpene phenol-based tackifying resin as the component (B), and a fluorine catalyst dissolved product (a fluorine catalyst as the component (D) and a silane coupling agent as the component (E)) without containing an acrylic tackifying resin as the component (C). When the pressure-sensitive adhesive layer 10 contains a fluorine catalyst dissolved product, it may contain a moisture-cured product of a silyl group-containing resin as the component (A), a terpene phenol-based tackifying resin as the component (B), an acrylic tackifying resin as the component (C), and a fluorine catalyst dissolved product (a fluorine catalyst as the component (D) and a silane coupling agent as the component (E)).

[0073] The fluorine catalyst may be, for example, at least one selected from the group consisting of boron trifluoride and boron trifluoride complexes. From the viewpoint of ease of handling, the fluorine catalyst is preferably a boron trifluoride complex. Examples of boron trifluoride complexes include boron trifluoride amine complexes, boron trifluoride alcohol complexes, boron trifluoride ether complexes, boron trifluoride thiol complexes, boron trifluoride sulfide complexes, boron trifluoride carboxylic acid complexes, and boron trifluoride water complexes. From the viewpoint of excellent stability and excellent catalytic activity, the boron trifluoride complex is preferably a boron trifluoride amine complex. One type of boron trifluoride complex may be used alone, or two or more types may be used in combination. When a boron trifluoride complex is used as the fluorine catalyst, it becomes difficult to suppress the hydrolysis of the urethane bond and urea bond contained in the silyl group-containing resin, so that adhesive residue when separated from the adherend is suppressed and the adhesive strength to the adherend at room temperature is likely to be improved.Furthermore, adhesive residue when separated from the adherend is suppressed and the adhesive strength at high temperatures is likely to be improved.

[0074] The boron trifluoride amine complex is not particularly limited, and examples thereof include a boron trifluoride monoethylamine complex, a boron trifluoride diethylamine complex, a boron trifluoride isopropylamine complex, a boron trifluoride chlorophenylamine complex, a boron trifluoride-triallylamine complex, a boron trifluoride benzylamine complex, and a boron trifluoride aniline complex.

[0075] The content of the fluorine catalyst is preferably 0.001 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

[0076] (Silane Coupling Agent) The silane coupling agent is not particularly limited. The silane coupling agent may be, for example, an amino group-containing alkoxysilane. Examples of silane coupling agents that can be used include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. One type of silane coupling agent may be used alone, or two or more types may be used in combination. When the pressure-sensitive adhesive layer 10 contains a silane coupling agent, it becomes more effective as a cross-linking aid.

[0077] The content of the silane coupling agent is preferably 0.01 part by mass or more and 1 part by mass or less per 100 parts by mass of the silyl group-containing resin.

[0078] In addition to the above components, the pressure-sensitive adhesive layer 10 may further contain various additives, such as antioxidants, dehydrating agents (vinyl silane compounds, calcium oxide, etc.), fillers, conductive materials, thermally conductive materials, plasticizers, thixotropic agents (anhydrous silica, amide wax, etc.), diluents (isoparaffin, etc.), flame retardants (aluminum hydroxide, halogen-based, phosphorus-based, and silicone-based), silicone alkoxy oligomers, pigments, titanate coupling agents, aluminum coupling agents, and drying oils.

[0079] The pressure-sensitive adhesive layer 10 may be formed, for example, from a hot-melt pressure-sensitive adhesive composition. In this specification, a hot-melt pressure-sensitive adhesive composition refers to a type of pressure-sensitive adhesive composition that melts when heated and becomes spreadable and coatable, and that develops adhesiveness and cohesive strength when cooled. The pressure-sensitive adhesive layer 10 may be formed, for example, from a solvent-based pressure-sensitive adhesive composition.

[0080] The thickness of the pressure-sensitive adhesive layer 10 is preferably 1 μm or more and 500 μm or less. The thickness of the pressure-sensitive adhesive layer 10 is more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 20 μm or more. The thickness of the pressure-sensitive adhesive layer 10 is more preferably 300 μm or less, even more preferably 200 μm or less, and even more preferably 100 μm or less.

[0081] [Second Aspect] A second aspect of the easily dismantlable pressure-sensitive adhesive sheet according to the present embodiment comprises a release liner on one or both surfaces of the pressure-sensitive adhesive layer. As one aspect, the second aspect of the easily dismantlable pressure-sensitive adhesive sheet according to the present embodiment may comprise a release liner on both surfaces of the pressure-sensitive adhesive layer 10. Hereinafter, the aspect in which release liners are provided on both surfaces of the pressure-sensitive adhesive layer 10 will be described.

[0082] In the following explanation, differences from the above-described easily dismantlable adhesive sheet 100 will be mainly explained, and overlapping explanations will be omitted or simplified. The same components as those in the easily dismantlable adhesive sheet 100 will be assigned the same reference numerals, and explanations thereof will be omitted or simplified.

[0083]

[0033] Figure 2A shows a schematic cross-sectional view of another example of a dismantlable adhesive sheet, illustrating an example of a dismantlable adhesive sheet comprising a release liner. As shown in Figure 2A, dismantlable adhesive sheet 110 comprises release liners 20 (first release liner 21 and second release liner 22) on each of first main surface 10A and second main surface 10B of adhesive layer 10 shown in Figure 1, with adhesive layer 10 sandwiched between two release liners 20. That is, dismantlable adhesive sheet 110 comprises first release liner 21, adhesive layer 10, and second release liner 22 laminated in this order in the thickness direction. Second main surface 21B of first release liner 21 and first main surface 22A of second release liner 22 are each release-treated surfaces. First major surface 10A of PSA layer 10 faces second major surface 21B of first release liner 21, and PSA layer 10 and first release liner 21 are in direct contact. Second major surface 10B of PSA layer 10 faces first major surface 22A of second release liner 22, and PSA layer 10 and second release liner 22 are in direct contact.

[0084] (Release Liners) The two release liners 20 are members for protecting the pressure-sensitive adhesive layer 10 until the easily dismantled adhesive sheet 110 is used. When the easily dismantled adhesive sheet 110 is used, the two release liners 20 are peeled from the pressure-sensitive adhesive layer 10 to expose the first main surface 10A and the second main surface 10B of the pressure-sensitive adhesive layer 10, and the sheet is used as the easily dismantled adhesive sheet 100. After the two release liners 20 are peeled, the first main surface 10A and the second main surface 10B of the pressure-sensitive adhesive layer 10 are each attached to an adherend (not shown). When the pressure-sensitive adhesive layer 10 contains the above-mentioned acrylic tackifier resin, lighter release force from the release liner 20 is more easily exhibited than when the pressure-sensitive adhesive layer 10 does not contain the above-mentioned acrylic tackifier resin, and therefore, when the easily dismantled adhesive sheet 110 is used, the release liner 20 is more easily peeled from the pressure-sensitive adhesive layer 10.

[0085] The release liner 20 is not particularly limited, and may be, for example, a member having releasability. For example, the release liner 20 may be a release material comprising a release substrate and a release agent layer formed by applying a release agent onto the release substrate. The release substrate refers to the substrate used for the release liner 20.

[0086] Examples of release substrates include paper substrates (such as high-quality paper, glassine paper, and clay-coated paper), laminated paper obtained by laminating a thermoplastic resin such as polyethylene to a paper substrate, and plastic films such as polyesters (such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate) and polyolefins (such as polypropylene and polyethylene). Examples of release agents include silicone-based, fluorine-based, and long-chain alkyl-based release agents.

[0087] The thickness of the release liner 20 is not particularly limited and may be, for example, 10 μm or more and 400 μm or less. When the release liner 20 has a release agent layer, the thickness of the release agent layer may be, for example, 0.01 μm or more and 5 μm or less.

[0088] The two release liners 20 (first release liner 21 and second release liner 22) provided on both sides of the pressure-sensitive adhesive layer 10 may be the same as or different from each other.

[0089] The easily dismantlable adhesive sheet 110 can be obtained, for example, by a manufacturing method including the following steps.

[0090] (Step P1A): A step of preparing a PSA composition comprising, as component (A1), a silyl group-containing resin (the above-mentioned silyl group-containing resin before becoming a moisture-cured product), and as component (B), a terpene phenol-based tackifier resin. (Step P2A): A step of applying the PSA composition prepared in step P1A to the surface of one release liner 20 (first release liner 21 or second release liner 22) to form a coating film of the PSA composition, thereby forming PSA layer 10 on the surface of one release liner 20. (Step P3A): A step of laminating the surface of the other release liner 20 (first release liner 21 or second release liner 22) toward PSA layer 10.

[0091] Step P1A is a step of preparing at least the silyl group-containing resin and the terpene phenol-based tackifier resin described in the first embodiment above, and mixing the silyl group-containing resin and the terpene phenol-based tackifier resin so that the content of each of the silyl group-containing resin and the terpene phenol-based tackifier resin in the PSA layer 10 is a predetermined amount, thereby preparing a PSA composition. Specific examples of the silyl group-containing resin and the terpene phenol-based tackifier resin are as described above. The PSA composition may optionally contain at least one component selected from the group consisting of, for example, an acrylic tackifier resin, a fluorine catalyst, a silane coupling agent, and various additives. Specific examples of these components are as described above. As described above, the PSA composition may be a hot-melt PSA composition or a solvent-based PSA composition.

[0092] Step P2A is a step of forming a PSA layer 10 on one of the release liners 20 by applying the PSA composition prepared in step P1A to the surface of one of the release liners 20. Specifically, the PSA composition is applied to the first main surface 22A of the second release liner 22 to form a coating film of the PSA composition. This forms the PSA layer 10 on the second release liner 22. At this time, the first main surface 22A of the second release liner 22 and the second main surface 10B of the PSA layer 10 are in contact. Step P2A is not limited to a step of applying the PSA composition to the first main surface 22A of the second release liner 22 to form a coating film of the PSA composition, but may also be a step of applying the PSA composition to the surface (second main surface 21B) of the first release liner 21 to form a coating film of the PSA composition to form the PSA layer 10 on the surface of the first release liner 21.

[0093] The method for applying the PSA composition to the first main surface 22A of the second release liner 22 is not particularly limited, and known application methods such as bar coating, knife coating, air knife coating, roll knife coating, roll coating, blade coating, die coating, gravure coating, lip coating, curtain coating, dip coating, and squeeze coating can be used.

[0094] Step P3A is a step of laminating a release liner 20 other than the release liner 20 used in step P2A onto the PSA layer 10 formed in step P2A. Specifically, the second major surface 21B of the first release liner 21 is laminated facing the first major surface 10A of the PSA layer 10. Step P3A is not limited to a step of laminating the second major surface 21B of the first release liner 21 facing the PSA layer 10, and a step of laminating the surface (first major surface 22A) of the second release liner 22 facing the PSA layer 10 may also be employed. Thereafter, the silyl group-containing resin contained in the PSA layer 10 is moisture-cured by leaving (curing) the resulting product for a predetermined period of time (e.g., 7 days) in an environment where the temperature is approximately 15°C or higher and 50°C or lower and the relative humidity is approximately 45% RH or higher and 85% RH or lower.

[0095] [Third Aspect] A third aspect of the easily dismantlable pressure-sensitive adhesive sheet according to the present embodiment is an easily dismantlable pressure-sensitive adhesive sheet comprising a substrate and the above-described pressure-sensitive adhesive layer on at least one surface of the substrate. As one aspect, the third aspect of the easily dismantlable pressure-sensitive adhesive sheet according to the present embodiment may comprise the pressure-sensitive adhesive layer 10 described in the first aspect on both surfaces of the substrate. Hereinafter, an aspect in which the above-described pressure-sensitive adhesive layer 10 is provided on both surfaces of the substrate will be described.

[0096] In the following explanation, differences from the above-described easily dismantlable adhesive sheet 100 and easily dismantlable adhesive sheet 110 will be mainly explained, and overlapping explanations will be omitted or simplified. The same components as those of the easily dismantlable adhesive sheet 100 and easily dismantlable adhesive sheet 110 will be assigned the same reference numerals, and explanations will be omitted or simplified.

[0097] As shown in Fig. 2B, the easily dismantlable adhesive sheet 120 includes a substrate 30 and two adhesive layers 10. The substrate 30 has a first main surface 30A and a second main surface 30B opposite the first main surface 30A. The first main surface 30A of the substrate 30 is the surface on which the first adhesive layer 11 is disposed, and the first main surface 30A of the substrate 30 faces the second main surface 11B of the first adhesive layer 11. The second main surface 30B of the substrate 30 is the surface on which the second adhesive layer 12 is disposed, and the second main surface 30B of the substrate 30 faces the first main surface 12A of the second adhesive layer 12. The first adhesive layer 11 is provided in contact with the substrate 30, and the second adhesive layer 12 is provided in contact with the substrate 30. That is, the easily dismantlable adhesive sheet 120 has a first pressure-sensitive adhesive layer 11, a substrate 30, and a second pressure-sensitive adhesive layer 12 provided in this order in the stacking direction. The first main surface 11A of the first pressure-sensitive adhesive layer 11 and the second main surface 12B of the second pressure-sensitive adhesive layer 12 are each exposed and are adhesive surfaces. The two pressure-sensitive adhesive layers 10 (the first pressure-sensitive adhesive layer 11 and the second pressure-sensitive adhesive layer 12) may be the same as or different from each other. As shown in FIG. 2B , the easily dismantlable adhesive sheet 120 has the substrate 30 and the two pressure-sensitive adhesive layers 10 in contact with each other, but is not limited thereto. An optional layer may be further provided between the substrate 30 and the two pressure-sensitive adhesive layers 10, or between the substrate 30 and one of the pressure-sensitive adhesive layers 10, as necessary.

[0098] Although not shown in Fig. 2B , in order to protect the adhesive surfaces of first pressure-sensitive adhesive layer 11 and second pressure-sensitive adhesive layer 12 until the easily dismantlable pressure-sensitive adhesive sheet 120 is used, release liners 20 shown in Fig. 2A may be attached to both first main surface 11A of first pressure-sensitive adhesive layer 11 and second main surface 12B of second pressure-sensitive adhesive layer 12. In this case, first release liner 21 is provided in contact with first pressure-sensitive adhesive layer 11, and second release liner 22 is provided in contact with second pressure-sensitive adhesive layer 12. Furthermore, either the first release liner 21 or the second release liner 22 may be used as the release liner 20, or both the first release liner 21 and the second release liner 22 may be used.

[0099] (Substrate) The substrate 30 is not particularly limited, and examples thereof include a plastic film. Examples of resins constituting the plastic film include polyolefins (polyethylene, polypropylene, etc.), polyesters (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.), polyimide, polyetherimide, polyether ketone, polyether ether ketone, polycarbonate, polymethyl methacrylate, triacetyl cellulose, polynorbornene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, vinyl chloride, polyurethane acrylate, polyether sulfone, and polyphenyl ether sulfone.

[0100] The thickness of the substrate 30 is not particularly limited and may be, for example, 5 μm or more and 500 μm or less. The thickness of the substrate 30 may be, for example, 10 μm or more, or 15 μm or more. The thickness of the substrate 30 may be, for example, 200 μm or less, or 100 μm or less.

[0101] The easily dismantlable adhesive sheet 120 can be obtained, for example, by a manufacturing method having the following steps. The easily dismantlable adhesive sheet 120 is preferably manufactured using a release liner not shown in Fig. 2B (e.g., release liner 20 shown in Fig. 2A). An example of a manufacturing method using both the first release liner 21 and the second release liner 22 shown in Fig. 2A is shown below.

[0102] (Step P1B): A step of preparing a PSA composition comprising a silyl group-containing resin as the component (A1) and a terpene phenol-based tackifying resin as the component (B). (Step P2B): A step of applying the PSA composition prepared in step P1B to the surface of one release liner 20 (first release liner 21 or second release liner 22) to form a coating film of the PSA composition, and forming one PSA layer 10 (first PSA layer 11 or second PSA layer 12) on the surface of one release liner 20. (Step P3B): A step of laminating a substrate 30 facing the PSA layer 10 formed on the surface of one release liner 20 (first release liner 21 or second release liner 22). (Step P4B): A step of applying the PSA composition prepared in step P1B to the surface of substrate 30 to form a coating film of the PSA composition, thereby forming the other PSA layer 10 (first PSA layer 11 or second PSA layer 12) on the surface of substrate 30. (Step P5B): A step of laminating the other release liner 20 (first release liner 21 or second release liner 22) toward the other PSA layer 10 formed on the surface of substrate 30.

[0103] Step P1B is the same as step P1A described above. Specifically, the process of forming the first pressure-sensitive adhesive layer 11 or the second pressure-sensitive adhesive layer 12 includes, as step P1B-1, a step of preparing a pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer 11, which comprises a silyl group-containing resin as the component (A1) and a terpene phenol-based tackifier resin as the component (B), and, as step P1B-2, a step of preparing a pressure-sensitive adhesive composition for forming the second pressure-sensitive adhesive layer 12, which comprises a silyl group-containing resin as the component (A1) and a terpene phenol-based tackifier resin as the component (B). The pressure-sensitive adhesive composition prepared in step P1B-1 and the pressure-sensitive adhesive composition prepared in step P1B-2 may be the same as or different from each other.

[0104]

[0047] Step P2B is the same as step P2A described above. Specifically, for example, when first PSA layer 11 is formed first, the step is to apply a PSA composition for forming first PSA layer 11 to the surface of first release liner 21 to form a coating film of the PSA composition for forming first PSA layer 11, and then form first PSA layer 11 on the surface of first release liner 21.

[0105] Step P3B is the same as step P3A described above, except that instead of laminating the other release liner 20 in step P3A, a substrate 30 is laminated.

[0106] Process P4B is the same as process P2B except that a coating film of a pressure-sensitive adhesive composition is formed on the substrate 30 to form a pressure-sensitive adhesive layer 10. If a first pressure-sensitive adhesive layer 11 is formed in process P2B, process P4B is a process of forming a second pressure-sensitive adhesive layer 12.

[0107] Step P5B is the same as step P3A described above.

[0108] Another manufacturing method can also be employed for the easily dismantlable adhesive sheet 120. In this manufacturing method, steps P1B and P2B are the same steps, but the steps P3B to P5B described above are different from the steps 3C and 4C described below.

[0109] (Step P3C): A step of applying the prepared PSA composition to the surface of the other release liner 20 (first release liner 21 or second release liner 22) to form a coating film of the PSA composition, and forming the other PSA layer 10 (first PSA layer 11 or second PSA layer 12) on the other release liner 20. (Step P4C): A step of laminating one PSA layer 10 (first PSA layer 11 or second PSA layer 12) formed in step P2B onto one surface of the substrate 30, and laminating the other PSA layer 10 (first PSA layer 11 or second PSA layer 12) formed in step P3C onto the other surface of the substrate 30.

[0110] The easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 can each be used to join components used in at least a part of a large product such as a home appliance, etc. The easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 according to this embodiment can also each be used to join components used in at least a part of a small product such as an electronic device, for example.

[0111] Although an example of the easily dismantlable adhesive sheet according to the present embodiment has been described above with reference to the drawings, the easily dismantlable adhesive sheet according to the present embodiment is not limited thereto. The easily dismantlable adhesive sheet according to the present embodiment may have various shapes as long as it has the above-described configuration. For example, the shape of the easily dismantlable adhesive sheet according to the present embodiment may be any shape suitable for the purpose, and may be, for example, rectangular, triangular, polygonal, circular, or elliptical. Furthermore, the release liner 20 is not limited to being provided on both sides of the adhesive layer 10, but may be provided on one side of the adhesive layer 10 depending on the purpose. Furthermore, the adhesive layer 10 is not limited to being provided on both sides of the substrate 30, but may be provided on one side of the substrate 30 depending on the purpose.

[0112] (Effects of the First Embodiment) This embodiment can achieve the following effects. (1A): The easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 each have a pressure-sensitive adhesive layer 10 containing a moisture-cured product of a silyl group-containing resin having a hydrolyzable silyl group of a specific structure and a terpene phenol-based tackifier resin, and therefore each maintains its adhesive strength to an adherend at room temperature. (2A): The easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 each have a pressure-sensitive adhesive layer 10 containing a moisture-cured product of a silyl group-containing resin having a hydrolyzable silyl group of a specific structure and a terpene phenol-based tackifier resin, and therefore when a laminate structure produced by adhering the easily dismantlable adhesive sheet 100 or the easily dismantlable adhesive sheet 120 to an adherend is dismantled, adhesive residue on the adherend is suppressed due to the cohesive force of the silyl group-containing resin. (3A): When the adhesive layer 10 of the easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 further comprises an acrylic tackifier resin, the adhesive strength at room temperature is improved. (4A): When the adhesive layer 10 of the easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 further comprises an acrylic tackifier resin, the adhesive strength at room temperature is improved.

[0113] [Second embodiment] <Laminate structure> The second embodiment is a laminate structure. The laminate structure according to the second embodiment comprises: a first adherend including at least one material selected from the group consisting of metal, glass, and resin; a second adherend that is composed of the same material as the first adherend or a different material from the first adherend and includes at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable pressure-sensitive adhesive sheet according to the first embodiment, which is provided between the first adherend and the second adherend and is attached to the first adherend and the second adherend.

[0114] Hereinafter, the laminated structure according to the present embodiment will be described with reference to the drawings. In the drawings, some parts are illustrated enlarged or reduced in size for ease of explanation.

[0115] In the following description, differences from the easily dismantlable adhesive sheets 100, 110, and 120 of the first embodiment will be mainly described, and overlapping descriptions will be omitted or simplified. The same components as those of the easily dismantlable adhesive sheets 100, 110, and 120 of the first embodiment will be assigned the same reference numerals, and descriptions thereof will be omitted or simplified.

[0116] [First Aspect] Figure 3A shows a schematic cross-sectional view of a laminate structure 200 as an example of this embodiment. The laminate structure 200 is an example of a first aspect of the laminate structure according to this embodiment. The laminate structure 200 uses the easily dismantlable adhesive sheet 100 described in the first aspect of the first embodiment, and the easily dismantlable adhesive sheet 100 consists only of a pressure-sensitive adhesive layer 10. The laminate structure 200 also has an aspect in which the easily dismantlable adhesive sheet 110 described in the second aspect of the first embodiment is used. In this case, the laminate structure 200 is produced, for example, by removing two release liners 20 from the easily dismantlable adhesive sheet 110 and attaching the pressure-sensitive adhesive layer 10 to two adherends 40. The order in which the pressure-sensitive adhesive layer 10 is attached to the two adherends 40 is not limited. For example, the pressure-sensitive adhesive layer 10 and two adherends 40 may be attached at the same time, or one adherend 40 and the other adherend 40 may be attached to the pressure-sensitive adhesive layer 10 sequentially.

[0117] 3A, the laminate structure 200 includes two adherends 40 (a first adherend 41 and a second adherend 42) and an easily dismantled adhesive sheet 100, with the first adherend 41, the easily dismantled adhesive sheet 100, and the second adherend 42 being laminated in this order in the lamination direction. In the laminate structure 200, the second main surface 41B of the first adherend 41 is attached to the first main surface 10A of the pressure-sensitive adhesive layer 10, and the first main surface 42A of the second adherend 42 is attached to the second main surface 10B of the pressure-sensitive adhesive layer 10, thereby bonding the two adherends 40 via the easily dismantled adhesive sheet 100.

[0118] (Adherend) The two adherends 40 (first adherend 41 and second adherend 42) each contain at least one material selected from the group consisting of metal, glass, and resin. The two adherends 40 may each be a composite material containing these materials. When the adherend 40 is a composite material, the adherend 40 may be, for example, glass with a metal vapor-deposited on it, a resin with a metal vapor-deposited on it, or glass with a resin vapor-deposited on it attached. The material of the metal adherend is not particularly limited, and examples thereof include metals such as aluminum. The metal is not limited to simple metals such as aluminum, but may also be alloys such as aluminum alloys and stainless steel. The material of the glass adherend is not particularly limited, and examples thereof include soda glass and borosilicate glass. The material of the resin adherend is not particularly limited, and examples thereof include various resins such as polyolefin (polypropylene, polyethylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polymethyl (meth)acrylate, urethane, melamine, etc. The resin may be a foamed resin.

[0119] The two adherends 40 may be made of the same material or different materials. When the two adherends 40 are different, for example, the first adherend 41 may contain glass and the second adherend 42 may contain metal. Alternatively, the first adherend 41 may contain glass and the second adherend 42 may contain resin. The shapes of the two adherends 40 are not particularly limited, and may be, for example, plate-like or block-like. The two adherends 40 may be made of the same shape and dimensions, or may be made of different shapes and dimensions. The adherend 40 may be made of a material, shape, and dimensions appropriate for the purpose.

[0120] The first adherend 41 may have a printed layer (not shown) on at least one of the first main surface 41A and the second main surface 41B. For example, the second main surface 41B of the first adherend 41 may have a printed layer, with the easily dismantled adhesive sheet 100 attached to the printed layer. Alternatively, the second main surface 41B of the first adherend 41 may have a metal vapor deposition layer (not shown), with the metal vapor deposition layer having a printed layer, with the easily dismantled adhesive sheet 100 attached to the printed layer. When a printed layer is provided, it may be formed by a printing method such as offset printing, gravure printing, flexographic printing, or screen printing. Furthermore, at least one of the first main surface 41A and the second main surface 41B may be coated with a paint (not shown). Like the first adherend 41, the second adherend 42 may also have a printed layer (not shown), a metal vapor deposition layer (not shown), or a paint (not shown).

[0121] 3B shows a schematic cross-sectional view of a laminated structure 220 as another example of this embodiment. The laminated structure 220 is an example of a second aspect of the laminated structure according to this embodiment. The laminated structure 220 uses the easily dismantlable pressure-sensitive adhesive sheet 120 described in the third aspect of the first embodiment, and includes a substrate 30 and pressure-sensitive adhesive layers 10 provided on both sides of the substrate 30.

[0122] The laminated structure 220 has the same configuration as the laminated structure 200, except that the easily dismantlable adhesive sheet 100 of the laminated structure 200 is changed to an easily dismantlable adhesive sheet 120. Specific examples of the easily dismantlable adhesive sheet 120 are as described in the third aspect of the first embodiment. As shown in Fig. 3B , the laminated structure 220 includes two adherends 40 (a first adherend 41 and a second adherend 42) and the easily dismantlable adhesive sheet 120, and has a structure in which the first adherend 41, the easily dismantlable adhesive sheet 120, and the second adherend 42 are laminated in this order. In the easily dismantlable adhesive sheet 120, the adhesive layer 10 is provided on both sides of the substrate 30, so that the second main surface 41B of the first adherend 41 is attached to the first main surface 11A of the first adhesive layer 11 provided on the easily dismantlable adhesive sheet 120, and the first main surface 42A of the second adherend 42 is attached to the second main surface 12B of the second adhesive layer 12 in the easily dismantlable adhesive sheet 120. In this way, the two adherends 40 are joined via the easily dismantlable adhesive sheet 120.

[0123] The laminated structure 200 and the laminated structure 220 may each be at least a part of a large product such as a home appliance. The laminated structure 200 and the laminated structure 220 may each be at least a part of a small product such as an electronic device.

[0124] Although an example of the laminate structure according to the present embodiment has been described above with reference to the drawings, the laminate structure according to the present embodiment is not limited thereto. The laminate structure according to the present embodiment may have various configurations as long as it has the above-described configuration. For example, the laminate structure according to the present embodiment is not limited to a case in which the easily dismantled adhesive sheet is attached to the entire surfaces of the first and second adherends. Alternatively, the easily dismantled adhesive sheet may be attached to a portion of the first adherend, a portion of the second adherend, or a portion of the first and second adherends. Furthermore, the laminate structure according to the present embodiment may include a third adherend arranged in parallel with the first adherend, a fourth adherend arranged in parallel with the second adherend, or a third adherend arranged in parallel with the first adherend and a fourth adherend arranged in parallel with the second adherend. Each of these adherends may be bonded via the easily dismantled adhesive sheet according to the first embodiment by being attached with the easily dismantled adhesive sheet according to the first embodiment.

[0125] (Effects of the Second Embodiment) According to this embodiment, the following effects can be achieved. (1B): Because the easily dismantlable adhesive sheet 100 and the easily dismantlable adhesive sheet 120 include the pressure-sensitive adhesive layer 10 described in the first embodiment, the adhesive strength is maintained at room temperature to each of the two adherends 40 (the first adherend 41 and the second adherend 42). Therefore, the laminate structure 200 or the laminate structure 220 produced by attaching the easily dismantlable adhesive sheet 100 or the easily dismantlable adhesive sheet 120 to the two adherends 40 is firmly bonded at room temperature.

[0126] [Third Embodiment] <Dismantling Method> The third embodiment is a dismantling method for dismantling a laminated structure. A first aspect of the dismantling method according to the third embodiment includes the steps of: preparing the laminated structure described in the second embodiment (step S1); bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend included in the laminated structure, and heating the laminated structure from the first adherend or the second adherend side while the heating means is in contact with the first adherend or the second adherend; and separating the first adherend and the second adherend from the easily dismantlable adhesive sheet after heating the laminated structure from the first adherend or the second adherend side and before the temperature of the laminated structure is reduced to the ambient temperature of the dismantling work environment (step S3A), wherein the easily dismantlable adhesive sheet consists of only the adhesive layer.

[0127] In a second aspect of the dismantling method according to the third embodiment, steps S1 and S2 are the same as those in the first aspect, but step S3A differs in the following respect: after the laminate structure is heated from the side of the first adherend or the second adherend, one of the first adherend or the second adherend is not separated from the easily dismantled adhesive sheet, and the other of the first adherend or the second adherend that has not been separated from the easily dismantled adhesive sheet is separated from the easily dismantled adhesive sheet (step S3B) during the time until the temperature is reduced to the atmospheric temperature of the dismantling work environment.

[0128] In a third aspect of the dismantling method according to the third embodiment, steps S1, S2, and S3A in the first aspect are the same as those in the first aspect, but the third aspect differs in that the easily dismantlable adhesive sheet comprises a substrate and the adhesive layers provided on both sides of the substrate.

[0129] In a fourth aspect of the dismantling method according to the third embodiment, steps S1, S2, and S3B in the second aspect are the same as those in the second aspect, but the fourth aspect differs in that the easily dismantlable adhesive sheet comprises a substrate and the adhesive layers provided on both sides of the substrate.

[0130] Hereinafter, the method for dismantling a laminated structure according to this embodiment will be described with reference to the drawings. In the drawings, some parts are illustrated enlarged or reduced in size for ease of explanation.

[0131] In the following explanation, differences from the laminated structures 200 and 220 according to the second embodiment will be mainly explained, and overlapping explanations will be omitted or simplified. The same components as those of the laminated structures 200 and 220 according to the second embodiment will be assigned the same reference numerals, and explanations will be omitted or simplified. Furthermore, overlapping explanations of the disassembly method according to this embodiment will be omitted or simplified.

[0132] 4A, 4B, 4C, 4D, and 4E are schematic explanatory diagrams illustrating an example of a method for dismantling a laminated structure according to this embodiment. Specifically, the schematic explanatory diagrams shown in 4A to 4E are diagrams outlining an example of a first embodiment and a second embodiment of the dismantling method according to this embodiment.

[0133] (Step S1) Step S1 is a step of preparing the laminated structure described in the second embodiment. In Fig. 4A, the laminated structure 200 described in the first aspect of the second embodiment is prepared as the laminated structure to be disassembled. Specific examples of the laminated structure 200 are as described above.

[0134] (Step S2) Step S2 is a step of heating the laminate structure prepared in step S1. In FIG. 4B, a hot plate 50 is used as a heating means for heating the laminate structure 200. As shown in FIG. 4B, the heating surface 50A of the hot plate 50 is in contact with the surface (second main surface 42B) of the second adherend 42 provided on the laminate structure 200. Then, with the heating surface 50A of the hot plate 50 in contact with the second main surface 42B of the second adherend 42, the laminate structure 200 is heated from the second adherend 42 side. 4B shows the laminate structure 200 being heated from the second adherend 42 side with the heating surface 50A of the hot plate 50 in contact with the second main surface 42B of the second adherend 42 in the laminate structure 200. However, this is not limited thereto, and the laminate structure 200 may also be heated from the first adherend 41 side with the heating surface 50A of the hot plate 50 in contact with the first main surface 41A of the first adherend 41 in the laminate structure 200. From the viewpoint of dismantling workability, it is preferable to heat the laminate structure 200 from one side of the two adherends 40. Note that, in step S2, if the laminate structure 200 is heated from the first adherend 41 side instead of from the second adherend 42 side, then in step S3A or step S3B after step S2, the second adherend 42 is replaced with the first adherend 41.

[0135] The heating conditions for heating the laminate structure 200 are not particularly limited. The heating conditions for heating the laminate structure 200 depend on the material of the adherend, but may be heating conditions that allow at least the second adherend 42 and the easily dismantlable adhesive sheet 100 to be separated. The temperature of the hot plate 50 when heating the laminate structure 200 is not particularly limited, and may be, for example, 80°C or higher, 90°C or higher, 100°C or higher, or 110°C or higher. The upper limit of the temperature of the hot plate 50 when heating the laminate structure 200 is not particularly limited, and may be within a temperature range that allows at least the second adherend 42 and the easily dismantlable adhesive sheet 100 to be separated, and allows the laminate structure 200 to be dismantled. The time for heating the laminate structure 200 is not particularly limited, and may be, for example, 5 seconds or more, 10 seconds or more, 30 seconds or more, or 1 minute or more. The time for heating the laminated structure 200 is not particularly limited, and may be, for example, 1 hour or less, 30 minutes or less, 10 minutes or less, or 5 minutes or less.

[0136] 4B, a hot plate 50 is used as the heating means for heating the laminated structure 200, but the heating means is not particularly limited as long as it is a heating means that can heat the laminated structure 200 by contacting it. In addition to the hot plate 50, various types of contact heating devices such as a surface heater, a heat block, and a hot roll can be used as the heating means. From the viewpoint of ease of dismantling work, it is preferable to use the hot plate 50 as the heating means.

[0137] (Step S3A) Step S3A is a step of separating the two adherends 40 (first adherend 41 and second adherend 42) from the easily dismantled adhesive sheet 100 after the laminated structure 200 has been heated in step S2 and before the temperature drops to the atmospheric temperature of the dismantling work environment, thereby dismantling the laminated structure 200. For example, depending on the form of the laminated structure 200, the two adherends 40 can be separated from the easily dismantled adhesive sheet 100 at the same time. However, from the viewpoint of ease of dismantling the laminated structure 200, it is preferable that the two adherends 40 are separated from the easily dismantled adhesive sheet 100 sequentially. Specifically, after separating one adherend 40 from the easily dismantled adhesive sheet 100, the other adherend 40 from the easily dismantled adhesive sheet 100 is separated.

[0138] As shown in FIG. 4C , after heating of the laminated structure 200 from the second adherend 42 side is completed, the hot plate 50 is separated from the second adherend 42. Next, after the hot plate 50 is separated, as shown in FIG. 4D , the second adherend 42, the easily dismantled adhesive sheet 100, and the first adherend 41 are sequentially separated by a step (step S3A-1) of separating the second adherend 42, which was in contact with the hot plate 50, from the easily dismantled adhesive sheet 100, as shown in FIG. 4E , and a step (step S3A-2) of separating the first adherend 41, which was not in contact with the hot plate 50, from the easily dismantled adhesive sheet 100. Through these steps, the laminated structure 200 is dismantled. The separation means for separating the two adherends 40 and the easily dismantled adhesive sheet 100 can be a separation means such as a peeling tool (not shown). The separation tool is not particularly limited as long as it can separate the adherends 40 and the easily dismantlable adhesive sheet 100. Furthermore, without being limited thereto, the separation of the two adherends 40 and the easily dismantlable adhesive sheet 100 may be performed by peeling them off by hand without using a peeling tool. When the laminated structure 200 is dismantled in the state shown in Fig. 4E, this is a diagram illustrating an example of a first aspect of the dismantling method according to the present embodiment.

[0139] After the laminate structure 200 is heated and the hot plate 50 is separated from the laminate structure 200, the temperature of the heated laminate structure 200 decreases over time. The two adherends 40 and the easily dismantled adhesive sheet 100 are separated before the temperature drops to the ambient temperature of the dismantling work environment. The ambient temperature of the dismantling work environment is not particularly limited, and may be, for example, 40°C. From the viewpoint of easily dismantling the laminate structure 200, it is preferable to separate the two adherends 40 and the easily dismantled adhesive sheet 100 while the temperature of the heated laminate structure 200 has only slightly decreased. The temperature at which the two adherends 40 and the easily dismantled adhesive sheet 100 are separated is preferably higher than 40°C, for example, as the temperature of the second adherend 42 with which the hot plate 50 was in contact, and may be 60°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, or 110°C or higher.

[0140] The laminated structure 200 can be separated into the first adherend 41, the easily dismantled pressure-sensitive adhesive sheet 100, and the second adherend 42 by both the step S3A-1 and the step S3A-2. Because the laminated structure 200 is configured to include the easily dismantled pressure-sensitive adhesive sheet 100 consisting only of the pressure-sensitive adhesive layer 10, the adherend 40 and the pressure-sensitive adhesive layer 10 tend to be separated more easily in step S3A-1 than in step S3A-2.

[0141] (Step S3B) Step S3B differs from the above-described step S3A in that the first adherend 41 is not separated from the easily dismantled adhesive sheet 100, but is left on the easily dismantled adhesive sheet 100. That is, step S3B completes the dismantling of the laminated structure 200 in the state shown in Fig. 4D. Other specific examples are as described in step S3A. When the dismantling of the laminated structure 200 is completed in the state shown in Fig. 4D, this is a diagram illustrating an example of the second aspect of the dismantling method according to this embodiment.

[0142] 5A, 5B, 5C, and 5D are schematic explanatory views illustrating another example of the method for dismantling a laminated structure according to this embodiment. Specifically, FIGS. 5A to 5D are explanatory views illustrating an example of the third and fourth aspects of the dismantling method according to this embodiment.

[0143] In Figures 5A, 5B, 5C, and 5D, the laminate structure 220 described in the third aspect of the second embodiment is disassembled instead of the laminate structure 200 shown in Figures 4A, 4B, 4D, and 4E, respectively. Figure 5A illustrates the aforementioned step S1, in which the laminate structure 220 is prepared as the target for disassembly. Specific examples of the laminate structure 220 are as described above. Figure 5B illustrates the aforementioned step S2, which is the same as described in Figure 4B, except that the laminate structure 220 is heated by the hot plate 50. Figures 5C and 5D illustrate the aforementioned step S3A, in which the two adherends 40 included in the laminate structure 220 are separated from the easily dismantled adhesive sheet 120. As described in Figures 4D and 4E, the second adherend 42, the easily dismantled adhesive sheet 120, and the first adherend 41 are sequentially separated by steps similar to the aforementioned steps S3A-1 and S3A-2. 5D, the disassembly of the laminated structure 220 is completed in the state shown in Fig. 5C, which is a diagram illustrating an example of a fourth aspect of the disassembly method according to the present embodiment, in which the first adherend 41 included in the laminated structure 220 is left on the easily dismantled adhesive sheet 120, and the second adherend 42 is separated from the easily dismantled adhesive sheet 120, as described in step S3B.

[0144] As described above, the laminate structure 220 can be separated into the first adherend 41, the easily dismantled pressure-sensitive adhesive sheet 120, and the second adherend 42 by steps similar to both of the steps S3A-1 and S3A-2. By including the easily dismantled pressure-sensitive adhesive sheet 120 having the substrate 30, the laminate structure 220 is less likely to break because the substrate 30 supports the pressure-sensitive adhesive layer 10 (the first pressure-sensitive adhesive layer 11 and the second pressure-sensitive adhesive layer 12). That is, in step S3A-1, the second pressure-sensitive adhesive layer 12 of the laminate structure 220 is more easily separated from the second adherend 42 than when the pressure-sensitive adhesive layer 10 of the laminate structure 200 is separated from the second adherend 42, and in step S3A-2, the first pressure-sensitive adhesive layer 11 of the laminate structure 220 is more easily separated from the first adherend 41 than when the pressure-sensitive adhesive layer 10 of the laminate structure 200 is separated from the first adherend 41. For this reason, the laminate structure 220 including the easily dismantlable pressure-sensitive adhesive sheet 120 having the substrate 30 tends to be more easily dismantlable than the laminate structure 200.

[0145] The dismantling method for the laminated structure 200 and the laminated structure 220 according to the present embodiment can each be applied to the dismantling of components used in at least a part of a large product such as a home appliance, etc. The dismantling method for the laminated structure 200 and the laminated structure 220 according to the present embodiment can also each be applied to the dismantling of components used in at least a part of a small product such as an electronic device, etc.

[0146] Although an example of a method for dismantling a laminate structure according to the present embodiment has been described above with reference to the drawings, the method for dismantling a laminate structure according to the present embodiment is not limited thereto. The method for dismantling a laminate structure according to the present embodiment may employ various forms as long as it has the above-described configuration. For example, the heating of the laminate structure is not limited to heating from only one adherend side and separating the heated adherend from the easily dismantled adhesive sheet. It is also possible to heat the laminate structure from one adherend side and separate the heated adherend from the easily dismantled adhesive sheet, and then separately heat the other adherend side that has not been separated and separate the separately heated adherend from the easily dismantled adhesive sheet. However, in the method for dismantling a laminate structure according to the present embodiment, the laminate structure is not heated from both adherend sides at the same time before separating the adherend from the easily dismantled adhesive sheet.

[0147] (Action and Effect of Third Embodiment) According to this embodiment, the following action and effect can be achieved. (1C): The laminate structure 200 or laminate structure 220 produced using the easily dismantled adhesive sheet 100 or the easily dismantled adhesive sheet 120 includes the pressure-sensitive adhesive layer 10 described in the first embodiment. Therefore, when the laminate structure 200 or the laminate structure 220 is dismantled, adhesive residue on the two adherends 40 (the first adherend 41 and the second adherend 42) is suppressed after separating the easily dismantled adhesive sheet 100 or the easily dismantled adhesive sheet 120 from the two adherends 40. (2C): When the laminate structure 200 or the laminate structure 220 is dismantled, adhesive residue on the separated adherend 40 is suppressed even when only one of the two adherends 40 (the first adherend 41 or the second adherend 42) is separated. (3C): The laminated structure 220 has the easily dismantlable adhesive sheet 120 including the substrate 30, and therefore the substrate 30 supports the adhesive layer 10, making it difficult for the adhesive layer 10 to break and making it easy to separate the adhesive layer 10 from the adherend 40. Therefore, compared to dismantling a laminated structure 200 having an easily dismantlable adhesive sheet 100 that does not include the substrate 30 and is composed only of the adhesive layer 10, the laminated structure 220 is more easily dismantled and easier to reuse.

[0148] [Modifications of the Embodiments] The present invention is not limited to the above-described embodiments, and includes modifications and improvements within the scope of achieving the object of the present invention.

[0149] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0150] [Preparation of Pressure-Sensitive Adhesive Sheets] Pressure-sensitive adhesive sheets for each Example and Comparative Example were prepared according to the following procedure. In the following Examples and Comparative Examples, parts by mass are parts by mass converted into solid content unless otherwise specified.

[0151] Example 1 (a1) Synthesis of Silyl Group-Containing Resin A reaction vessel was charged with 206 parts by mass of N-aminoethyl-γ-aminopropylmethyldimethoxysilane and 172 parts by mass of methyl acrylate, and the mixture was reacted under a nitrogen atmosphere while stirring and mixing under heating conditions of 80°C for 10 hours to obtain a silylating agent.

[0152] Into another reaction vessel were charged 1,000 parts by mass of polyoxypropylene diol (PMLS4015, molecular weight 15,000, manufactured by AGC Corporation), 24.6 parts by mass of isophorone diisocyanate (NCO / OH ratio = 1.7), and 0.05 parts by mass of dibutyltin dilaurate, and the mixture was reacted at 85°C for 7 hours while stirring and mixing under a nitrogen atmosphere, thereby obtaining a urethane prepolymer in which the main chain was mainly composed of polyoxypropylene and in which urethane bonds had been introduced into the main chain.

[0153] To 1,000 parts by mass of the urethane prepolymer obtained above, 42.1 parts by mass of the silylating agent obtained above was added, and the mixture was stirred and mixed under a nitrogen atmosphere while reacting at 80°C for 1 hour to obtain a silyl group-containing resin. －１ The progress of the reaction was confirmed by the disappearance of the silyl group. The obtained silyl group-containing resin had two methoxy groups as hydrolyzable silyl groups at both ends of the main chain, the main chain was mainly polyoxypropylene, and a urethane bond was introduced into the main chain. The structure of the terminal portion of the silyl group-containing resin having a hydrolyzable silyl group is represented by the following formula (11A). * in the following formula (11A) indicates the bonding position.

[0154]

[0155] (a2) Preparation of Pressure-Sensitive Adhesive Composition A fluorine catalyst solution was prepared by dissolving 1 part by mass of boron trifluoride monoethylamine complex (containing 59% by mass of boron trifluoride) in 9 parts by mass of 3-aminopropyltrimethoxysilane (KBM903, manufactured by Shin-Etsu Chemical Co., Ltd.). 100 parts by mass of the silyl group-containing resin obtained above and 42 parts by mass of a terpene phenol-based tackifying resin (YS Polystar T-130, manufactured by Yasuhara Chemical Co., Ltd., softening point 130°C) were mixed and stirred until nearly uniform, and then 1 part by mass of the fluorine catalyst solution prepared above was mixed with this mixture and stirred until nearly uniform, thereby preparing a pressure-sensitive adhesive composition.

[0156] (a3) Preparation of Easily Dismantlable Adhesive Sheet The adhesive composition prepared above was melt-coated on the release-treated surface of a first release liner and the release-treated surface of a second release liner using a hot melt coater, forming a 50 μm thick first adhesive layer on the release-treated surface of the first release liner to obtain a release liner with a first adhesive layer, and forming a 50 μm thick second adhesive layer on the release-treated surface of the second release liner to obtain a release liner with a second adhesive layer. Then, using the release liner with the first adhesive layer, a polyethylene terephthalate (PET) film (Lumirror T60, manufactured by Toray Industries, Inc., thickness 50 μm) was bonded as a substrate to the adhesive surface of the first adhesive layer formed on the first release liner. This produced a single-sided adhesive sheet with a release liner and substrate, in which the first release liner, first adhesive layer, and substrate were laminated in that order. The adhesive surface of the release liner with the second adhesive layer was bonded to the side of the substrate not having the first adhesive layer in the obtained single-sided PSA sheet with a release liner and a substrate, thereby laminating a 50 μm-thick second adhesive layer and the first release liner in this order on the side of the substrate not having the first adhesive layer. This resulted in a double-sided PSA sheet with a release liner and a substrate sandwiched between two release liners. The obtained double-sided PSA sheet with a release liner and a substrate was aged for 7 days under conditions of 40°C and 80% RH to produce a double-sided PSA sheet as an easily dismantlable PSA sheet in which the first release liner, first PSA layer (thickness: 50 μm), PET film (substrate), second PSA layer (thickness: 50 μm), and second release liner were laminated in this order. The silyl group-containing resins contained in the two PSA layers of the obtained double-sided PSA sheet had been moisture-cured in advance.

[0157] Example 2 A double-sided PSA sheet serving as an easily dismantlable PSA sheet was produced in the same manner as in Example 1, except that in the preparation of the (a2) PSA composition in Example 1, the mixture was changed to a mixture obtained by mixing 100 parts by mass of a silyl group-containing resin, 42 parts by mass of a terpene phenol-based tackifying resin (Yasuhara Chemical Co., Ltd., YS Polystar T-130), and 48 parts by mass of an acrylic tackifying resin (Seiko PMC Corporation, Hi-Loss ATF-2377, weight average molecular weight Mw: 3200, softening point 135°C), and stirring until a nearly uniform state was achieved.

[0158] Comparative Example 1 (b1) Preparation of Pressure-Sensitive Adhesive Composition An acrylic resin was obtained by polymerizing 90 parts by mass of butyl acrylate, 1 part by mass of vinyl acetate, and 9 parts by mass of acrylic acid. The weight-average molecular weight Mw, measured using gel permeation chromatography (GPC) (GPC measurement) in terms of standard polystyrene, was 500,000 (500,000). 100 parts by mass of the obtained acrylic resin and 0.05 parts by mass of an epoxy crosslinker (TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.) were mixed and diluted with toluene (solvent) to prepare a pressure-sensitive adhesive composition.

[0159] (b2) Preparation of adhesive sheet A double-sided adhesive sheet was obtained in the same manner as in Example 1, except that in the preparation of (a3) ​​easily dismantled adhesive sheet in Example 1, an adhesive composition prepared from the above (b1) adhesive composition was applied to the release-treated surface of the first release liner using a knife coater so that the thickness after drying would be 20 μm to form an adhesive layer.

[0160] Comparative Example 2 A double-sided PSA sheet was obtained in the same manner as in Comparative Example 1, except that in the preparation of the PSA composition (b1) of Comparative Example 1, the amount of epoxy-based crosslinking agent was changed to 0.25 parts by mass.

[0161] [Evaluation of Pressure-Sensitive Adhesive Sheets] Measurements and evaluations of the pressure-sensitive adhesive sheets produced in the above examples and comparative examples were carried out by the methods described below.

[0162] [Room Temperature Adhesion Strength] Measurements were made in accordance with the test method of JIS Z0237:2022, which involves peeling a sheet at an angle of 180° from a stainless steel test plate to measure adhesion strength. Specifically, the single-sided PSA sheet with release liner and substrate prepared in each Example and Comparative Example, before the PSA layer of the release liner with a second PSA layer was attached to the substrate, was cured for 7 days under conditions of 40°C and 80% RH to prepare a sample for room temperature adhesion testing. This sample was cut to a width of 25 mm, and the first release liner was peeled from the cut sample to expose the first PSA layer. The adhesive surface of the first PSA layer was attached to a SUS304 stainless steel plate (SUS304 steel plate) and pressed back and forth once with a roller having a mass of 2000 g. After leaving the sample to stand for 20 minutes in an environment of 23°C and 50% RH, the sample was peeled off from the SUS304 steel plate at an angle of 180° to the SUS304 steel plate at a peeling speed of 300 mm / min in the same environment, and the room temperature adhesive strength was measured.

[0163] [High-Temperature Adhesion Strength] Using the same procedure as for the room-temperature adhesive strength test, the single-sided PSA sheet described above was cured for 7 days under conditions of 40°C and 80% RH to prepare a sample for the high-temperature adhesive strength test. This sample was cut to a width of 25 mm, and the first release liner was peeled off from the cut sample to expose the first PSA layer. The adhesive surface of the first PSA layer was attached to a SUS304 steel plate and pressed back and forth once with a 2000 g roller. The sample was then left to stand in an environment of 100°C for 20 minutes, and then peeled off the sample from the SUS304 steel plate at an angle of 180° relative to the SUS304 steel plate at a peeling speed of 300 mm / min in the same environment to measure the high-temperature adhesive strength.

[0164] [Ease of Disassembly] The double-sided PSA sheets prepared in each Example and Comparative Example were cut to 7 cm x 5 cm, one release liner (first release liner) was peeled off, and the adhesive surface of one of the PSA layers (first PSA layer) was attached to a 7 cm x 14 cm x 3 mm glass plate. Subsequently, the other release liner (second release liner) was peeled off, and another glass plate was attached to the adhesive surface of the other PSA layer (second PSA layer) to prepare a laminated structure. The prepared laminated structure was used as a sample for the ease of disassembly test. The obtained sample was left to stand for 24 hours under conditions of 23°C and 50% RH, and then placed on a hot plate heated to 120°C and heated for 2 minutes. Thereafter, the glass plate attached to the PSA layer on the side that had contacted the hot plate was manually peeled off, and then the PSA layer was manually peeled off from the glass plate that had not contacted the hot plate. The ease of disassembly was evaluated according to the following evaluation criteria. <Evaluation Criteria> A: The glass can be easily peeled off the double-sided pressure-sensitive adhesive sheet by hand. F: The glass cannot be peeled off the double-sided pressure-sensitive adhesive sheet by hand.

[0165] [Adhesive Residue] After the evaluation of ease of dismantling, the surface of the glass plate that had been in contact with the hot plate, on which the double-sided PSA sheet had been attached (attached surface), was visually inspected for remaining adhesive layer, and adhesive residue was evaluated according to the following evaluation criteria. <Evaluation criteria> A: No adhesive remained on the attached surface of the glass plate, and no adhesive residue occurred. F: Adhesive remained on the attached surface of the glass plate, and adhesive residue occurred.

[0166]

[0167] When the double-sided PSA sheet of Comparative Example 1 was used, the room temperature adhesive strength was equivalent to that of Example 1, but the high temperature adhesive strength was higher than that of the double-sided PSA sheets of each Example. In a dismantling ease test of a laminated structure produced by bonding two glass plates using the double-sided PSA sheet of Comparative Example 1, cohesive failure occurred in the PSA layer attached to the glass plate, resulting in adhesive residue on the glass plate.

[0168] The high-temperature adhesive strength of Comparative Example 2 was almost the same as that of Examples 1 and 2. In a dismantling test of a laminated structure produced by bonding two glass plates using the double-sided PSA sheet of Comparative Example 2, peeling was possible at the interface between the adhesive layer of the double-sided PSA sheet and the glass plates, and no adhesive residue was left on the glass plates. However, the room-temperature adhesive strength obtained when the double-sided PSA sheet of Comparative Example 2 was used was lower than that of Examples 1 and 2.

[0169] In contrast, when the double-sided PSA sheet of Example 1 or Example 2 was used as the easily dismantlable PSA sheet, excellent adhesive strength was achieved at room temperature. Furthermore, in an ease of dismantling test of a laminate structure produced by bonding two glass plates using the double-sided PSA sheet of Example 1 or Example 2, peeling was possible at the interface between the adhesive layer of the double-sided PSA sheet and the glass plate, and no adhesive residue was left on the glass plate. Therefore, it can be seen that the double-sided PSA sheets of each Example, which have an adhesive layer containing a moisture-cured product of a silyl group-containing resin having a hydrolyzable silyl group with a specific structure and a terpene phenol-based tackifier resin, maintain adhesive strength at room temperature while suppressing adhesive residue when dismantling a laminate structure including the easily dismantlable PSA sheet, compared to the PSA sheets of each Comparative Example, which have an acrylic PSA layer.

[0170] From the above results, it was confirmed that the easily dismantlable pressure-sensitive adhesive sheets of each Example maintained their adhesive strength to the adherend at room temperature, while suppressing adhesive residue when separated from the adherend.

[0171] 10...adhesive layer, 10A...first main surface (adhesive layer), 10B...second main surface (adhesive layer), 11...first adhesive layer, 11B...second main surface (first adhesive layer), 12...second adhesive layer, 12A...first main surface (second adhesive layer), 21...first release liner, 21B...second main surface (first release liner), 22...second release liner, 22A...first main surface (second release liner), 30...substrate, 30A...second One main surface (substrate), 30B... second main surface (substrate), 41... first adherend, 41A... first main surface (first adherend), 41B... second main surface (first adherend), 42... second adherend, 42A... first main surface (second adherend), 42B... second main surface (second adherend), 50... hot plate (an example of heating means), 50A... heating surface, 100, 110, 120... easily dismantlable adhesive sheet, 200, 220... laminated structure.

Claims

1. An easily dismantlable pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a moisture-cured product of a silyl group-containing resin and a terpene phenol-based tackifying resin, wherein the silyl group-containing resin has a polyoxyalkylene structure in its main chain, and has both a urethane bond and a urea bond, or has either the urethane bond or the urea bond, in part of the main chain or in a side chain, and has hydrolyzable silyl groups represented by the following formula (1) at both ends of the main chain: (In the formula (1), X １ and X ２ are each independently a hydroxy group or an alkoxy group, R is an alkyl group having 1 to 20 carbon atoms, and * indicates the bonding position.

2. An easily dismantlable adhesive sheet according to claim 1, wherein the content of the terpene phenol-based tackifying resin is 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

3. An easily dismantlable adhesive sheet according to claim 1 or 2, wherein the adhesive layer further comprises an acrylic tackifier resin, and the content of the acrylic tackifier resin is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the silyl group-containing resin.

4. The easily dismantlable adhesive sheet according to claim 3, wherein the weight average molecular weight Mw of the acrylic tackifier resin is 300 or more and 10,000 or less.

5. An easily dismantlable adhesive sheet according to claim 1 or 2, comprising a release liner provided on at least one surface of the adhesive layer.

6. An easily dismantlable adhesive sheet according to claim 1 or 2, comprising: a substrate; and the adhesive layer provided on at least one surface of the substrate.

7. A laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and which comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable adhesive sheet according to claim 1 or 2 which is provided between the first adherend and the second adherend and is attached to the first adherend and the second adherend.

8. A dismantling method for dismantling a laminated structure, comprising the steps of: preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable adhesive sheet according to claim 1 or claim 2 which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then separating the first adherend and the second adherend from the easily dismantled pressure-sensitive adhesive sheet before the temperature drops to the atmospheric temperature of a dismantling work environment, wherein the easily dismantled pressure-sensitive adhesive sheet consists only of the pressure-sensitive adhesive layer.

9. A dismantling method for dismantling a laminated structure, comprising the steps of: preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable adhesive sheet according to claim 1 or claim 2 which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then, during the time until the temperature is lowered to the ambient temperature of the dismantling work environment, not separating one of the first adherend or the second adherend from the easily dismantled adhesive sheet, and separating the other of the first adherend or the second adherend that has not been separated from the easily dismantled adhesive sheet from the easily dismantled adhesive sheet, wherein the easily dismantled adhesive sheet consists of only the adhesive layer.

10. A dismantling method for dismantling a laminated structure, comprising the steps of: preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable adhesive sheet according to claim 1 or claim 2 which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then separating the first adherend and the second adherend from the easily dismantled pressure-sensitive adhesive sheet before the temperature drops to the atmospheric temperature of a dismantling work environment, wherein the easily dismantled pressure-sensitive adhesive sheet comprises a substrate and the pressure-sensitive adhesive layers provided on both sides of the substrate.

11. A dismantling method for dismantling a laminated structure, comprising the steps of: preparing a laminated structure comprising: a first adherend comprising at least one material selected from the group consisting of metal, glass, and resin; a second adherend which is composed of the same material as the first adherend or a different material from the first adherend and comprises at least one material selected from the group consisting of metal, glass, and resin; and the easily dismantlable adhesive sheet according to claim 1 or claim 2 which is provided between the first adherend and the second adherend and attached to the first adherend and the second adherend; bringing a heating means for heating the laminated structure into contact with a surface of the first adherend or the second adherend, and heating the laminated structure from the side of the first adherend or the second adherend while the heating means is in contact with the first adherend or the second adherend; a step of heating the laminated structure from the side of the first adherend or the second adherend, and then separating one of the first adherend or the second adherend from the easily dismantled adhesive sheet, and separating the other of the first adherend or the second adherend that has not been separated from the easily dismantled adhesive sheet, from the easily dismantled adhesive sheet, during the time until the temperature of the laminated structure is reduced to the ambient temperature of the dismantling work environment, wherein the easily dismantled adhesive sheet comprises a substrate and the adhesive layers provided on both sides of the substrate.

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