Adhesive sheet

Abstract

Provided is an adhesive sheet having an adhesive layer. The adhesive layer includes a polymer, a polyfunctional monomer, and a thermal polymerization initiator. In addition, the release force reduction rate (S150-5) after heating at 150 DEG C for 5 minutes and the release force reduction rate (S180-120) after heating at 180 DEG C for 120 minutes of the adhesive sheet are both 50% or more.

Description

Technical Field

[0001] The present invention relates to adhesive sheets.

[0002] This application claims priority based on Japanese Patent Application No. 2023-011970, filed on January 30, 2023, the entire contents of which are incorporated herein by reference. Background Art

[0003] Generally, adhesives (also called pressure-sensitive adhesives. The same applies hereinafter) have the following properties: they are in a soft solid (viscoelastic) state in a temperature range near room temperature and are easily adhered to an adherend by pressure. In view of the excellent operability of pasting to an adherend, adhesives are widely used in various fields in the form of adhesive sheets with a support having an adhesive layer on a support, or in the form of adhesive sheets without a support. Among such adhesives, there are adhesives that are used by adhering to an adherend and are removed from the adherend after the purpose of the adhesion is completed. As prior art documents disclosing such prior art, Patent Documents 1 to 4 can be cited. Patent Documents 1 to 4 disclose thermosetting adhesives.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-29105

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-204617

[0008] Patent Document 3: Japanese Patent Application Publication No. 2019-56101

[0009] Patent Document 4: Japanese Patent Application Publication No. 1998-209087

[0010] Non-patent literature

[0011] Non-Patent Literature 1: Simone Napolitano, 'Irreversible adsorption of polymer melts and nanoconfinement effects', SoftMatter, 2020, 16, pp. 5348-5365

[0012] Non-Patent Document 2: Ben O'Shaughnessy and Dimitrios Vavylonis, 'No n-Equilibrium in Adsorbed Polymer Layers', J. Phys.: Condens. Matter, 17, 2005, pp. R63-99 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] For adhesives used for peeling and removing from adherends, it is required to have good adhesion during the adhesion to the adherend and to be able to be easily peeled from the adherend after the adhesion purpose is completed. For example, for adhesives suitable for adherends to be treated by heat, it is expected to have easy peelability that allows easy peeling from the adherend after being heated in a state of being adhered to the adherend. However, if adherends such as glass, metal, and resin are heated at high temperatures while being adhered to the adhesive, there is a risk of adverse conditions such as the adhesive being adsorbed on the surface of the adherend, thereby increasing the peeling force (heavy peeling), reducing the peeling property, or generating residual adhesive. In this regard, see the various polymers described in non-patent documents 1 to 2 that have adsorption force by heating. For example, in the case of thermosetting adhesives such as those described in patent documents 1 to 4, it is difficult to make the curing of the adhesive during high-temperature heating appear before the adsorption of the adhesive to the adherend, and the reduction in peeling force and the suppression of the increase in peeling force based on the curing of the adhesive cannot be obtained, and stable easy peelability cannot be obtained after high-temperature heating.

[0015] Based on this background, the inventors of this application focused on thermosetting adhesives and conducted research and development based on a design concept different from the past. As a result, they successfully obtained an adhesive that is easy to peel (heat-peelable) even after being attached to an adherend and heated at a high temperature. The above-mentioned heat-peelable property is usually easy to peel even after a heat treatment in which the peeling force increases, so it can also be called heat-resistant peelable. Such adhesive sheets with heat-peelable and heat-resistant peelable properties are expected to be used in various applications due to their usefulness. However, in various applications, the scenes and methods of use of the adhesive sheets are different, and not only the adherends are different, but also the applied heating treatment conditions (temperature, time, etc.) may also be different. For example, if the heating treatment temperature for easy peeling is 180°C and about 1 hour, then due to the limitations of the use scene, adherend, etc., there may also be a situation where a shorter heating time is applied at a lower heating temperature. Under such heat treatment conditions with limited heating temperature and heating time, even an adhesive that exhibits sufficient peelability by heating at 180°C for 1 hour may not exhibit sufficient heat peelability, resulting in residual adhesive residue and contamination of the adherend during peeling.

[0016] The present invention has been made in view of the above circumstances, and provides a heat-peelable adhesive sheet that can cope with a wide range of heat treatment conditions, including those with limited heating temperature and heating time.

[0017] Means for solving problems

[0018] According to the present invention, there is provided an adhesive sheet having an adhesive layer. The adhesive layer comprises a polymer, a multifunctional monomer and a thermal polymerization initiator. In addition, the peeling force reduction rate S of the adhesive sheet after heating is 150-5 And the peeling force reduction rate after heating S 180-120 Here, the above peeling force reduction rate after heating S 150-5 By formula: S 150-5 [%] = (1-(N 150-5 / N0))×100 to obtain (where N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 150-5 The peeling force (N) after heating at 150°C for 5 minutes was measured at 23°C and 50% RH. 150-5 [N / 20mm]. ). In addition, the above peeling force reduction rate S after heating 180-120 By formula: S 180-120 [%] = (1-(N 180-120 / N0))×100 to obtain (where N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 180-120 The peeling force (N) after heating at 180°C for 120 minutes on a glass plate was measured at 23°C and 50% RH. 180-120 [N / 20mm]. The adhesive sheet satisfying the above-described configuration and characteristics exhibits sufficiently reduced peel force after heating, regardless of whether the heat treatment conditions are 150°C for approximately 5 minutes or 180°C for approximately 2 hours. Therefore, it can be used as a heat-peelable adhesive sheet that can cope with a wide range of heating conditions, including those with limited heating temperature and heating time. Such adhesive sheets are less restricted in their heating conditions and therefore have a wide range of applications, making them useful.

[0019] In some embodiments, the adhesive sheet has a peel force N0 to a glass plate of 2.0 N / 20 mm or greater. An adhesive sheet having such a peel force N0 exhibits good adhesion to an adherend and can be easily peeled from the adherend by heat treatment under predetermined conditions.

[0020] In some preferred embodiments, the thermal polymerization initiator comprises a peroxide-based polymerization initiator. By using a peroxide-based initiator as the thermal polymerization initiator, even when heat treatment is performed with limited heating temperature and heating time, in other words, under a wide range of heat treatment conditions, heat-peelability can be ideally exhibited.

[0021] In some preferred embodiments, the crosslinking agent content in the adhesive layer is 0.9 parts by weight or less relative to 100 parts by weight of the polymer. By omitting the crosslinking agent from the adhesive layer, or limiting the amount of crosslinking agent in the adhesive layer to a specified amount or less, heat-peelability can be achieved even with heat treatments limited to a specified temperature and time, in other words, under a wide range of heat treatment conditions.

[0022] In some preferred embodiments, the peeling force reduction rate S of the adhesive sheet after heating is 130-5 Here, the peeling force reduction rate after heating S 130-5 By formula: S 130-5 [%] = (1-(N 130-5 / N0))×100 to obtain (where N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 130-5 The peeling force (N) after heating at 130°C for 5 minutes was measured at 23°C and 50% RH. 130-5 [N / 20mm]. ) A pressure-sensitive adhesive sheet satisfying the above-mentioned characteristics can exhibit heat-peelability even when subjected to a heat treatment with further restrictions on the heating temperature and heating time, in other words, under a wider range of heat treatment conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] [ Figure 1 ] is a cross-sectional view schematically showing an example of a form of an adhesive sheet. DETAILED DESCRIPTION

[0024] The following describes preferred embodiments of the present invention. Except for matters specifically mentioned in this specification, matters necessary for implementing the present invention can be understood by those skilled in the art based on the teachings regarding the implementation of the invention described in this specification and the common technical knowledge at the time of filing the application. The present invention can be implemented based on the disclosure in this specification and the common technical knowledge in the field.

[0025] It should be noted that in the following drawings, components and parts that perform the same function may be described with the same reference numerals, and repeated descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are schematic for the purpose of clearly explaining the present invention and do not necessarily accurately represent the dimensions or reduction ratios of the actual product provided.

[0026] In this specification, the "base polymer" of an adhesive refers to the main component of the rubbery polymer contained in the adhesive. This rubbery polymer is a polymer that exhibits rubber elasticity in a temperature range near room temperature. Furthermore, in this specification, the term "main component," unless otherwise specified, refers to a component contained in an amount exceeding 50% by weight.

[0027] In this specification, the term "acrylic polymer" refers to a polymer comprising monomer units derived from a monomer having at least one (meth)acryloyl group in one molecule. The term "acrylic polymer" is defined as a polymer comprising monomer units derived from an acrylic monomer.

[0028] In addition, in this specification, the so-called "acrylic monomer" refers to a monomer having at least one (meth)acryloyl group in one molecule. Here, the so-called "(meth)acryloyl group" is a general term for both acryloyl and methacryloyl groups. Therefore, the concept of acrylic monomers mentioned here can include both monomers having an acryloyl group (acrylic monomers) and monomers having a methacryloyl group (methacrylic monomers). Similarly, in this specification, the so-called "(meth)acrylic acid" is a general term for both acrylic acid and methacrylic acid, and the so-called "(meth)acrylate" is a general term for both acrylate and methacrylate. The same applies to other similar terms.

[0029] In this specification, "weight" can be replaced by "mass." For example, "weight %" can be replaced by "mass %" and "parts by weight" can be replaced by "parts by mass."

[0030] <Adhesive Sheet>

[0031] The adhesive sheet disclosed herein comprises an adhesive layer and is constituted. The adhesive sheet can be an adhesive sheet with a substrate having the form of the above-mentioned adhesive layer on one or both sides of a non-peelable substrate (supporting substrate), or an adhesive sheet without a substrate such as the form in which the above-mentioned adhesive layer is retained in a release liner (that is, an adhesive sheet without a non-peelable substrate. Typically, the adhesive sheet is formed by an adhesive layer). In the concept of the adhesive sheet mentioned herein, materials referred to as adhesive tapes, adhesive labels, adhesive films, etc. can be included. The adhesive sheet disclosed herein can be in roll form or in monolithic form. Alternatively, it can be an adhesive sheet further processed into a form of various shapes.

[0032] The cross-sectional structure of the adhesive sheet is shown in Figure 1 .like Figure 1 As shown, the adhesive sheet 1 has an adhesive surface 1A, which is a single-sided adhesive sheet having an adhesive layer 20 on the surface 10A on one side of a sheet-like substrate layer (support substrate) 10. The adhesive sheet 1 is used in such a way that the surface 20A of the adhesive layer 20 serving as its adhesive surface 1A is pasted on an adherend. The back surface 10B of the substrate layer 10 (the surface on the opposite side to the surface 10A on one side) is also the back surface 1B of the adhesive sheet 1 and constitutes the outer surface of the adhesive sheet 1. The adhesive sheet 1 before use (i.e., before adhering to an adherend) can be a form of an adhesive sheet 50 with a release liner protected by a release liner 30 in which the adhesive surface 1A is at least protected by the release liner 30 on the adhesive layer 20 side. Alternatively, the surface (back surface) 10B on the other side of the substrate layer 10 can be a release surface, and the adhesive layer 20 can be wound into a roll so that the adhesive layer 20 is in contact with the back surface so that its surface (adhesive surface 1A) is protected.

[0033] <Properties of Adhesive Sheet>

[0034] (Peel force reduction rate after heating)

[0035] The peel strength reduction rate S150 of the adhesive sheet disclosed herein after heating at 150°C for 5 minutes -5 And the peeling force reduction rate S after heating at 180℃ for 120 minutes 180-120 The adhesive sheet that meets the above characteristics can have the heat peelability that can cope with a wide range of heat treatment conditions including those with limited heating temperature and heating time. In some preferred embodiments, the peel force reduction rate S after heating is 150-5 It can be 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 98% or more. In some preferred embodiments, the peeling force reduction rate S after heating is 180-120It can be 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 98% or more. The greater the peeling force reduction rate after heating, the better the heat peeling property and heat-resistant peeling property. 150-5 and peel force reduction rate S 180-120 The upper limit is 100% or less (for example, less than 100%), and may be 99% or less.

[0036] In some embodiments, the peel strength reduction rate S of the adhesive sheet after heating at 140°C for 5 minutes is 140-5 Preferably, it is 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 98% or more. In some preferred embodiments, the peeling force reduction rate S of the adhesive sheet after heating at 130°C for 5 minutes is 130-5 The peeling force reduction rate S of the adhesive sheet after heating at 120°C for 5 minutes is 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 98% or more. 120-5 It can be 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, or 90% or more. 140-5 , and then the peeling force reduction rate after heating S 130-5 , and then the peeling force reduction rate after heating S 120-5 The adhesive sheet with a peeling strength of 50% or more has heat-peelable properties and heat-resistant peelable properties under heating treatment conditions corresponding to the corresponding heating temperature and heating time. Even when the heating temperature and heating time are further restricted, in other words, under a wider range of heating treatment conditions, it can still have heat-peelable properties and heat-resistant peelable properties. In addition, the greater the peeling strength reduction rate after heating, the better the peeling strength and heat-resistant peelable properties can be achieved. 120-5 、S 130-5 and S 140-5 The upper limit is 100% or less (for example, less than 100%), and may be 99% or less.

[0037] In addition, the peel strength reduction rate S of the adhesive sheet disclosed herein after heating at 160° C. for 5 minutes is 160-5 , Peel force reduction rate (S) after heating at 170°C for 5 minutes 170-5 , Peel force reduction rate (S) after heating at 180°C for 5 minutes 180-5 , Peel force reduction rate after heating at 180℃ for 60 minutes (S) 180-60Each may be 50% or more (for example, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, and further 98% or more). 160-5 、S 170-5 、S 180-5 and S 180-60 The upper limit is 100% or less (for example, less than 100%), and may be 99% or less.

[0038] The above peeling force reduction rate S after each heating T-m The peeling force N0 [N / 20 mm] before heating and the peeling force N0 [N / 20 mm] after heating can be used to determine the peeling force N0 [N / 20 mm] before heating. T-m Substitute [N / 20mm] into the following formula to obtain the value.

[0039] S T-m [%] = (1-(N T-m / N0))×100

[0040] In the above formula, N represents the peeling force after heating. T-m The symbol "t" indicates the heat treatment conditions (heating temperature and heating time) before measuring the peel strength. T is the heating temperature [°C], and m is the heating time [minutes]. In addition, the symbol "S" indicates the rate of decrease in peel strength after heating. T-m In the equation, T and m refer to the peeling force after heating (N). T-m T and m correspond to the heating temperature T [°C] and heating time m [minutes] respectively. For example, the peeling force reduction rate S after heating at 150°C for 5 minutes is 150-5 By formula: S 150-5 [%] = (1-(N 150-5 / N0))×100. In addition, the peeling force reduction rate S after heating at 180°C for 120 minutes 180-120 By formula: S 180-120 [%] = (1-(N 180-120 / N0))×100. In addition, the peeling force reduction rate S after heating at 130°C for 5 minutes 130-5 By formula: S 130-5 [%] = (1-(N 130-5 / N0))×100. For other peeling force reduction rates after heating S T-m , is also obtained using the same method.

[0041] The above-mentioned reduction rates of the peeling forces after heating (therefore, the peeling force before heating N0, the peeling forces after heating and their relative relationship described later) can be achieved and adjusted by the polymer (monomer composition, etc.) contained in the adhesive layer, the type of multifunctional monomer and thermal polymerization initiator, the selection of the amount used, their combination, and the presence or absence of the use of a cross-linking agent, the selection of the type and amount used, etc.

[0042] (Peel force N0 before heating)

[0043] Although not particularly limited, in some embodiments, the peeling force N0 of the adhesive sheet to the glass plate before heating is preferably 0.5 N / 20 mm or more, and may be 1.0 N / 20 mm or more (e.g., greater than 1.0 N / 20 mm), or 1.5 N / 20 mm or more. In some preferred embodiments, the peeling force N0 is 2.0 N / 20 mm or more, 2.5 N / 20 mm or more, 3.0 N / 20 mm or more, 3.5 N / 20 mm or more, 4.0 N / 20 mm or more, or 4.5 N / 20 mm or more. The adhesive sheet having the peeling force N0 has good adhesion during adhesion to the adherend, and can be easily peeled from the adherend by heating under specified conditions. In some other embodiments, from the perspective of achieving higher adhesion to various adherends, the peel force N0 can be 5.0 N / 20 mm or more, 8.0 N / 20 mm or more, 10.0 N / 20 mm or more, or 12 N / 20 mm or more (e.g., 13 N / 20 mm or more). The upper limit of the peel force N0 is appropriately set according to the required adhesion and is therefore not limited to a specific range. For example, it can be approximately 30 N / 20 mm or less, approximately 20 N / 20 mm or less, approximately 10 N / 20 mm or less, or approximately 5 N / 20 mm or less. Specifically, the peel force N0 refers to the peel strength against a glass plate measured at a peel angle of 180 degrees and a speed of 300 mm / min under an environment of 23°C and 50% RH. More specifically, the peel force N0 is measured by the method described in the examples below.

[0044] (Peel strength after heating)

[0045] Although not particularly limited, in some embodiments, the peel strength (N) of the adhesive sheet after heating at 150°C for 5 minutes to a glass plate measured at 23°C and 50% RH is 150-5 It is appropriate to be less than 2.0N / 20mm, and preferably less than 1.0N / 20mm. 150-5 The adhesive sheet can be made to have heat-resistance and heat-resistance after heat treatment, and can be made to ideally meet the above-mentioned peeling force reduction rate S after heating. 150-5 In some preferred embodiments, the peeling force N after heating is preferably 150-5Less than 1.0N / 20mm, can be 0.5N / 20mm or less, can be 0.3N / 20mm or less, can be 0.2N / 20mm or less, and can also be 0.1N / 20mm or less. Peeling force after heating N 150-5 The lower limit value may be 0.0 N / 20 mm, or may be 0.01 N / 20 mm or more (eg, 0.1 N / 20 mm or more).

[0046] Although not particularly limited, in some embodiments, the peel strength (N) of the adhesive sheet after heating to a glass plate measured at 23°C and 50% RH after heating at 180°C for 120 minutes is 180-120 It is appropriate to be less than 2.0N / 20mm, and preferably less than 1.0N / 20mm. 180-120 The adhesive sheet can be made to have heat-resistance and heat-resistance after heat treatment, and can be made to ideally meet the above-mentioned peeling force reduction rate S after heating. 180-120 In some preferred embodiments, the peeling force N after heating is preferably 0.05mm / s, from the viewpoint of improving the peeling property obtained by heating at 180°C for 120 minutes. 180-120 Less than 1.0N / 20mm, can be 0.5N / 20mm or less, can be 0.3N / 20mm or less, can be 0.2N / 20mm or less, and can also be 0.1N / 20mm or less. Peeling force after heating N 180-120 The lower limit value may be 0.0 N / 20 mm, or may be 0.01 N / 20 mm or more (eg, 0.1 N / 20 mm or more).

[0047] In some embodiments, the peeling force (N) of the adhesive sheet after heating at 140°C for 5 minutes to a glass plate measured at 23°C and 50% RH is 140-5 It is preferably less than 2.0 N / 20 mm, more preferably less than 1.0 N / 20 mm (e.g., less than 1.0 N / 20 mm), can be less than 0.5 N / 20 mm, can be less than 0.3 N / 20 mm, can be less than 0.2 N / 20 mm, and can be less than 0.1 N / 20 mm. In some preferred embodiments, the peeling force N of the adhesive sheet after heating at 130° C. for 5 minutes to the glass plate is measured at 23° C. and 50% RH. 130-5Less than 2.0 N / 20 mm, more preferably 1.0 N / 20 mm or less (e.g., less than 1.0 N / 20 mm), can be 0.5 N / 20 mm or less, can be 0.3 N / 20 mm or less, can be 0.2 N / 20 mm or less, and can be 0.1 N / 20 mm or less. In a more preferred embodiment, the peeling force N of the adhesive sheet after heating at 120° C. for 5 minutes to a glass plate measured at 23° C. and 50% RH is: 120-5 Less than 2.0 N / 20 mm, more preferably less than 1.0 N / 20 mm (for example, less than 1.0 N / 20 mm), and may be less than 0.5 N / 20 mm. 140-5 , and then N 130-5 、N 120-5 The adhesive sheet can be made to have heat-resistant peelability and heat-resistant peelability under the corresponding heating temperature and heating time, and ideally meet the above-mentioned peel force reduction rate S after heating. 140-5 , and then S 130-5 、S 120-5 Adhesive sheet. Peel force after heating N 120-5 , and then N 130-5 、N 140-5 The lower limit value may be 0.0 N / 20 mm, or may be 0.01 N / 20 mm or more (eg, 0.1 N / 20 mm or more).

[0048] The peel strength N of the adhesive sheet disclosed herein after heating at 160° C. for 5 minutes to a glass plate measured at 23° C. and 50% RH is 160-5 , after heating at 170 ° C for 5 minutes, the peeling force on the glass plate was measured at 23 ° C and 50% RH. 170-5 , after heating at 180℃ for 5 minutes, the peeling force after heating to the glass plate was measured at 23℃ and 50% RH (N) 180-5 , the peeling force after heating to the glass plate measured at 23°C and 50% RH after heating at 180°C for 60 minutes (N) 180-60 Each may be less than 2.0 N / 20 mm, may be less than 1.0 N / 20 mm (e.g., less than 1.0 N / 20 mm), may be less than 0.5 N / 20 mm, may be less than 0.3 N / 20 mm, may be less than 0.2 N / 20 mm, or may be less than 0.1 N / 20 mm. Peel force after heating N 160-5 、N 170-5 、N 180-5 and N 180-60 The lower limit value may be 0.0 N / 20 mm, or may be 0.01 N / 20 mm or more (eg, 0.1 N / 20 mm or more).

[0049] The peeling force after heating is N T-m Specifically, it refers to the peel strength against the glass plate measured at a peeling angle of 180 degrees and a speed of 300 mm / min in an environment of 23°C and 50% RH after being heated at a temperature of T°C and a heating time of m minutes while being attached to an adherend. T-m More specifically, it is measured by the method described in the Examples below.

[0050] As will be understood from the description of the peeling method described below, the above-mentioned peel force reduction rate after heating and peel force after heating represent the characteristics of the PSA sheet disclosed herein and do not limit the usage of the PSA sheet.

[0051] <Adhesive Layer>

[0052] (polymer)

[0053] In the technology disclosed herein, the type of adhesive is not particularly limited. The adhesive layer may comprise one or more polymers in various rubber-like polymers such as acrylic polymers, rubber polymers (such as natural rubber, synthetic rubber, mixtures thereof, etc.), polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers that can be used in the field of adhesives. The above polymers are used as base polymers in the adhesive and can function as structural polymers of the molding adhesive. From the viewpoints of adhesive performance, cost, etc., it is preferred to adopt an adhesive comprising an acrylic polymer or a rubber polymer as the base polymer. Among them, it is preferred to use an adhesive (acrylic adhesive) having excellent heat resistance as the base polymer.

[0054] The following description will focus mainly on acrylic pressure-sensitive adhesives and pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive, ie, an acrylic pressure-sensitive adhesive layer. However, the pressure-sensitive adhesive layer disclosed herein is not intended to be limited to acrylic pressure-sensitive adhesive layers.

[0055] (Acrylic polymer)

[0056] In some embodiments, an acrylic polymer is used in which more than 50% by weight of the monomer components constituting the polymer are acrylic monomers. The proportion of acrylic monomers in the above-mentioned monomer components is suitably 60% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, further preferably 85% by weight or more, and for example, 90% by weight or more. The upper limit of the proportion of acrylic monomers in the monomer components constituting the acrylic polymer is 100% by weight. From the perspective of obtaining the effect of using non-acrylic monomers, the proportion of the above-mentioned acrylic monomers can be, for example, 98% by weight or less, 95% by weight or less, or 92% by weight or less. The acrylic monomers can be used alone or in combination of two or more.

[0057] In some preferred embodiments, the monomer component includes an alkoxy-containing (meth)acrylate. Acrylic polymers containing an alkoxy-containing (meth)acrylate as a monomer component tend to be more compatible with, for example, the polyfunctional monomers described below. Alkoxy-containing (meth)acrylates can be used alone or in combination of two or more.

[0058] Examples of (meth)acrylates containing an alkoxy group include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate; and alkoxy (poly)alkylene glycol (meth)acrylates such as methoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, ethoxydipropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, and ethoxypolypropylene glycol (meth)acrylate. The like can be cited. Among them, alkoxyalkyl (meth)acrylates are preferred, and among them, alkoxyalkyl (meth)acrylates having an alkoxy group having 1 to 4 carbon atoms (eg, 1, 2, or 3 carbon atoms) are more preferred, and methoxyethyl (meth)acrylate is particularly preferred.

[0059] The content of the alkoxy-containing (meth)acrylate in the monomer components constituting the acrylic polymer is not particularly limited. From the perspective of effectively obtaining the effects brought about by the use of the alkoxy-containing (meth)acrylate, the content of the alkoxy-containing (meth)acrylate in the above-mentioned monomer components is generally about 1% by weight or more, for example, it can be 10% by weight or more, it can be 30% by weight or more, or it can be 50% by weight or more. In some embodiments, from the perspective of adhesive properties such as adhesion and compatibility with multifunctional monomers, the content of the alkoxy-containing (meth)acrylate in the above-mentioned monomer components is, for example, greater than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more. The upper limit of the content of the alkoxy-containing (meth)acrylate in the above-mentioned monomer component is 100 weight % or less. For example, from the perspective of obtaining the effects of other copolymerizable monomers such as monomers containing functional groups, in some embodiments, it is advantageous for the content of the alkoxy-containing (meth)acrylate to be approximately 99 weight % or less, and may be 95 weight % or less, 93 weight % or less, or 90 weight % or less.

[0060] In some other embodiments, the monomer component constituting the acrylic polymer may be a component containing a linear alkyl (meth)acrylate having a linear or branched alkyl group with 1 to 20 carbon atoms at the ester terminal. Hereinafter, a linear alkyl (meth)acrylate having an alkyl group with X to Y carbon atoms at the ester terminal may be referred to as “C X-Y Alkyl (meth) acrylate". It should be noted that in this specification, the so-called "chain" is used to include linear and branched. The above-mentioned chain alkyl (meth) acrylate can be used alone or in combination of two or more.

[0061] As C 1-20Specific non-limiting examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, Nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, and the like.

[0062] Among these, it is preferred to use at least C 4-20 Alkyl (meth) acrylate, more preferably at least C 4-18 In some embodiments, as C 1-20 Alkyl (meth) acrylate, preferably C 4-8 Among them, it is more preferable to use C 4-8 Alkyl acrylate. C 4-8 Alkyl (meth)acrylate can be used alone or in combination of two or more. 4-8 The use of alkyl (meth)acrylates tends to easily obtain good adhesive properties (adhesive strength, etc.). For example, as the above-mentioned monomer components, acrylic polymers containing one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) are preferred, and acrylic polymers containing at least 2EHA are particularly preferred. 1-20 In some other aspects of alkyl (meth) acrylate, C 7-12 Alkyl (meth) acrylate. C 7-12 Alkyl (meth)acrylate can be used alone or in combination of two or more. 7-12 Alkyl (meth) acrylate, preferably C 7-10 Alkyl acrylate, more preferably C 7-9 Alkyl acrylate, more preferably C8 alkyl acrylate.

[0063] When using C 4-20 In the form of alkyl (meth)acrylate, C 4-20Alkyl (meth) acrylate (preferably C 4-8 Alkyl (meth) acrylate or C 7-12 Alkyl (meth) acrylate, more preferably C 7-10 Alkyl acrylate, more preferably C 7-9 Alkyl acrylate, particularly preferably C8 alkyl acrylate. Unless otherwise specified, the following is the same. 1-20 The proportion of alkyl (meth)acrylate is not particularly limited. In some embodiments, it is preferably 10% by weight or more, more preferably 20% by weight or more, and may be 25% by weight or more. In other embodiments, C 4-20 Alkyl (meth) acrylate in the above C 1-20 The proportion of the alkyl (meth)acrylate may be 50% by weight or more, 70% by weight or more, or 90% by weight or more (e.g., 95% by weight or more). 4-20 Alkyl (meth) acrylate in the above C 1-20 The upper limit of the proportion of the alkyl (meth)acrylate is 100 wt %. In some embodiments, it may be 80 wt % or less, 60 wt % or less, less than 50 wt %, or 30 wt % or less.

[0064] In some embodiments, the monomer components include C 1-3 Alkyl (meth) acrylate as C 1-20 Alkyl (meth) acrylate. C 1-3 Alkyl (meth)acrylate can be used alone or in combination of two or more. 1-3 Acrylic polymers with alkyl (meth)acrylate as a monomer component can easily produce adhesives with good adhesive properties (adhesive strength, etc.) and cohesive strength. 1-3 In some forms of alkyl (meth) acrylate, C 1-2 Alkyl (meth) acrylate. As C 1-3 A suitable example of the alkyl (meth)acrylate is methyl acrylate (MA).

[0065] When using C 1-3 In the form of alkyl (meth)acrylate, C 1-3 Alkyl (meth) acrylate (preferably C 1-2 Alkyl (meth) acrylate, more preferably MA. Unless otherwise specified, the following is the same. 1-20The proportion of the alkyl (meth)acrylate is not particularly limited, and in some embodiments, for example, 10% by weight or more is appropriate, more preferably 30% by weight or more, 50% by weight or more, or 70% by weight or more. 1-3 Alkyl (meth) acrylate in the above C 1-20 The upper limit of the proportion of the alkyl (meth)acrylate is 100 wt %. In some embodiments, it may be 90 wt % or less, 75 wt % or less, less than 50 wt %, or 30 wt % or less.

[0066] C in the monomer components constituting the acrylic polymer 1-20 The content of alkyl (meth) acrylate is not particularly limited. 1-20 Considering the effect of using alkyl (meth)acrylate, C 1-20 The content of the alkyl (meth)acrylate is generally about 1% by weight or more, for example, 10% by weight or more, 30% by weight or more, or 50% by weight or more. In some embodiments, from the perspective of adhesive properties such as adhesive strength, the C 1-20 The content of the alkyl (meth)acrylate is, for example, greater than 50% by weight, preferably greater than 60% by weight, more preferably greater than 70% by weight, further preferably greater than 80% by weight, and may be greater than 85% by weight. 1-20 The upper limit of the content of the alkyl (meth)acrylate is 100 wt % or less. For example, from the perspective of obtaining the effect of other copolymerizable monomers such as monomers containing functional groups, in some embodiments, the C 1-20 The content of alkyl (meth)acrylate is advantageously about 99 wt % or less, and can be 95 wt % or less, 93 wt % or less, or 90 wt % or less. In other embodiments, the above C 1-20 The content of the alkyl (meth)acrylate may be approximately 70% by weight or less, 50% by weight or less (e.g., less than 50% by weight), 30% by weight or less, 10% by weight or less, 1% by weight or less, or 0.1% by weight or less. The above monomer components may also be substantially free of C 1-20 Although not particularly limited, C 1-20 The amount of alkyl (meth)acrylate is limited, or substantially no C 1-20 The monomer composition of the alkyl (meth)acrylate can be adopted when it contains an alkoxy group-containing (meth)acrylate (typically, when it contains it as a main component). 1-20The content of alkyl (meth) acrylate can range from 1-20 The above C included in the alkyl (meth) acrylate 4-20 Alkyl (meth) acrylate, C 4-18 Alkyl (meth) acrylate, C 4-8 Alkyl (meth) acrylate, C 4-8 Alkyl acrylate, C 7-12 Alkyl (meth) acrylate, C 7-10 Alkyl acrylate, C 7-9 Alkyl acrylate, C8 alkyl acrylate, BA, 2EHA, C 1-3 Alkyl (meth) acrylate, C 1-2 The range of each content of alkyl (meth)acrylate and MA.

[0067] In some embodiments, the monomer components constituting the acrylic polymer preferably include other monomers other than the above-mentioned alkoxyalkyl (meth) acrylate and chain alkyl (meth) acrylate. Such other monomers may be monomers (co-polymerizable monomers) that can copolymerize with alkoxyalkyl (meth) acrylate and chain alkyl (meth) acrylate. As the above-mentioned other monomers, monomers having polar groups (e.g., carboxyl groups, hydroxyl groups, rings containing nitrogen atoms, etc.) can be preferably used. Monomers having polar groups can help introduce crosslinking points into the acrylic polymer and improve the cohesive force of the adhesive. The other monomers can be used alone or in combination of two or more.

[0068] Specific non-limiting examples of other monomers include the following monomers.

[0069] Carboxyl group-containing monomers: for example, acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like.

[0070] Monomers containing anhydride groups: for example, maleic anhydride, itaconic anhydride.

[0071] Hydroxyl group-containing monomers: for example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0072] Monomers containing sulfonic acid groups or phosphoric acid groups: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloyl phosphate, etc.

[0073] Epoxy group-containing monomers: for example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl (meth)acrylate ether, allyl glycidyl ether, and glycidyl (meth)acrylate ether.

[0074] Monomers containing cyano groups: for example, acrylonitrile, methacrylonitrile, etc.

[0075] Isocyanate group-containing monomers: for example, 2-isocyanateethyl (meth)acrylate, etc.

[0076] Monomers containing amide groups: for example, (meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(tert-butyl)(meth)acrylamide and the like N,N-dialkyl(meth)acrylamide; N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, N-n-butyl(meth)acrylamide and the like N-monoalkyl(meth)acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having hydroxyl groups and amide groups, for example, N-(2-hydroxyethyl)(meth)acrylamide , N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide and other N-hydroxyalkyl(meth)acrylamide; monomers having alkoxy groups and amide groups, for example, N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide and other N-alkoxyalkyl(meth)acrylamide; and N,N-dimethylaminopropyl(meth)acrylamide, alkoxydiacetone(meth)acrylamide, vinylformamide, vinylacetamide, etc.

[0077] Monomers containing amino groups: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate.

[0078] Monomers having a ring containing a nitrogen atom: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylmorpholine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc. (for example, lactams such as N-vinyl-2-caprolactam).

[0079] Monomers having a succinimide skeleton include, for example, N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyhexamethylenesuccinimide.

[0080] Maleimides: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.

[0081] Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide and the like.

[0082] Aminoalkyl (meth)acrylates: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate.

[0083] Alkoxysilyl group-containing monomers: for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane.

[0084] Vinyl esters: for example, vinyl acetate, vinyl propionate, etc.

[0085] Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

[0086] Aromatic vinyl compounds: for example, styrene, α-methylstyrene, vinyltoluene, etc.

[0087] Olefins: for example, ethylene, butadiene, isoprene, isobutylene, etc.

[0088] (Meth)acrylates having an alicyclic hydrocarbon group: for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate, and the like.

[0089] (Meth)acrylates having an aromatic hydrocarbon group: for example, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and the like.

[0090] In addition, there are (meth)acrylates containing heterocycles such as tetrahydrofurfuryl (meth)acrylate, (meth)acrylates containing halogen atoms such as (meth)acrylates containing vinyl chloride or fluorine atoms, (meth)acrylates containing silicon atoms such as silicone (meth)acrylate, and (meth)acrylates obtained from terpene compound derivative alcohols.

[0091] When using such other monomers, its usage amount is not particularly limited, and it is appropriate to be set as more than 0.01 % by weight of the overall monomer component. From the viewpoint of better giving play to the use effect of other monomers, the usage amount of other monomers can be set as more than 0.1 % by weight of the overall monomer component, can be set as more than 0.5 % by weight. In addition, from the viewpoint of easily obtaining the balanced property of adhesion, it is appropriate to be set as less than 50 % by weight of the overall monomer component, preferably set as less than 40 % by weight.

[0092] In some embodiments, the monomer components constituting the acrylic polymer may include monomers having nitrogen atoms. By using monomers having nitrogen atoms, the cohesive force of the adhesive is increased, and the adhesive force can be ideally increased. Monomers having nitrogen atoms can be used alone or in combination of two or more. As a suitable example of a monomer having a nitrogen atom, a monomer having a ring containing a nitrogen atom can be cited. As monomers having a nitrogen atom and monomers having a ring containing a nitrogen atom, the monomers exemplified above can be used, for example, N-vinyl cyclic amide represented by the general formula (1) can be used:

[0093] [Chemical Formula 1]

[0094]

[0095] Here, in the general formula (1), R 1 is a divalent organic group, specifically -(CH2) n-. n is an integer from 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone (NVP) can be preferably used. Other suitable examples of monomers having nitrogen atoms include: N,N-dialkyl(meth)acrylamides such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; N-monoalkyl(meth)acrylamides such as N-isopropyl(meth)acrylamide; N-hydroxyalkyl(meth)acrylamides such as N-(2-hydroxyethyl)acrylamide (HEAA); N-acryloylmorpholine (ACMO); alkoxydiacetone(meth)acrylamide; vinylformamide, vinylacetamide; and the like. Among them, NVP, HEAA, and ACMO are more preferred.

[0096] The amount of monomers with nitrogen atoms (preferably monomers with rings containing nitrogen atoms) used is not particularly limited, for example, it can be more than 1% by weight of the overall monomer composition, or it can be more than 3% by weight. In some embodiments, the amount of monomers with nitrogen atoms in the above-mentioned monomer composition is preferably more than 5% by weight, more preferably more than 7% by weight, and further preferably more than 9% by weight. In some other embodiments, the amount of monomers with nitrogen atoms in the above-mentioned monomer composition can be more than 10% by weight, can be more than 12% by weight, or can be more than 15% by weight. The more the amount of monomers with nitrogen atoms is used, the more the cohesive force of the adhesive tends to be improved. In addition, it is appropriate to set the amount of monomers with nitrogen atoms to, for example, less than 40% by weight of the overall monomer composition, and it can be set to less than 35% by weight, can be set to less than 30% by weight, or can be set to less than 25% by weight. In some embodiments, the amount of monomers with nitrogen atoms can be set to, for example, less than 20% by weight of the overall monomer composition, can be set to less than 15% by weight, or can be set to less than 12% by weight.

[0097] In some embodiments, the monomer component may include a monomer containing a hydroxyl group. By using a monomer containing a hydroxyl group, the cohesion and crosslinking density of the adhesive can be adjusted, and the bonding strength can be improved. As a monomer containing a hydroxyl group, the monomers exemplified above can be used, for example, 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA) can be preferably used. The monomer containing a hydroxyl group can be used alone or in combination of two or more.

[0098] The amount used when using a monomer containing a hydroxyl group is not particularly limited, and for example, it can be more than 0.01% by weight of the entire monomer component, can be more than 0.1% by weight, and can also be more than 0.5% by weight. In some preferred embodiments, the amount of the monomer containing a hydroxyl group is more than 1% by weight of the entire monomer component, more preferably more than 2% by weight, further preferably more than 3% by weight, for example, it can be more than 5% by weight. In addition, in some embodiments, it is appropriate to set the amount of the monomer containing a hydroxyl group to, for example, less than 40% by weight of the entire monomer component, preferably less than 30% by weight, more preferably less than 20% by weight, further preferably less than 10% by weight, and can also be less than 7% by weight.

[0099] In some preferred embodiments, as monomer components of acrylic polymers, as monomers having polar groups (monomers containing polar groups), monomers having nitrogen atoms (e.g., monomers containing amide groups such as (meth)acrylamide, monomers containing rings containing nitrogen atoms such as NVP) and monomers containing hydroxyl groups (e.g., HEA, 4HBA) are used in combination. This allows for well-balanced adhesion and cohesion. In the embodiment where monomers having nitrogen atoms and monomers containing hydroxyl groups are used in combination, the amount of monomers having nitrogen atoms is A N The amount of monomer containing hydroxyl group A OH The weight ratio (A N / A OH ) is not particularly limited, and can be, for example, 0.1 or more, 0.5 or more, 1.0 or more, 1.2 or more, 1.5 or more, or 1.8 or more. N / A OH ) For example, it can be less than 10, less than 5, less than 3, or less than 2.5.

[0100] In some embodiments, the monomer component includes a monomer containing a carboxyl group. Suitable examples of monomers containing a carboxyl group include acrylic acid (AA) and methacrylic acid (MAA). Monomers containing a carboxyl group can be used alone or in combination of two or more. For example, AA and MAA can also be used in combination.

[0101] The usage amount of the monomer containing carboxyl can be, for example, more than 0.01 % by weight of the overall monomer composition, can be more than 0.05 % by weight, can be more than 0.1 % by weight, can be more than 0.3 % by weight, or can be more than 0.5 % by weight. In some ways, the usage amount of the monomer containing carboxyl can be more than 1 % by weight of the overall monomer composition, can be more than 3 % by weight, can be more than 6 % by weight, or can be more than 8 % by weight. The more the usage amount of the monomer containing carboxyl is, the more the cohesive force of the adhesive is improved. The ratio of the above-mentioned monomer containing carboxyl can be, for example, less than 20 % by weight, can be less than 15 % by weight, can be less than 10 % by weight, can be less than 5 % by weight, can be less than 3 % by weight, can be less than 2 % by weight, or can be less than 1 % by weight (for example, less than 1 % by weight).

[0102] In addition, when using an acrylic polymer with an ethylenically unsaturated group as a polymer, as other monomers, it is preferred to use a monomer with a functional group (functional group A) that can react with the functional group (functional group B) of the compound with an ethylenically unsaturated group as described later. In this way, the type of other monomers is determined according to the type of the above-mentioned compound. As other monomers with functional group A, for example, preferably a monomer containing a carboxyl group, a monomer containing an epoxy group, a monomer containing a hydroxyl group, a monomer containing an isocyanate group, and particularly preferably a monomer containing a hydroxyl group. By using a monomer containing a hydroxyl group as other monomers, the acrylic polymer has a hydroxyl group. In contrast, as a compound with an ethylenically unsaturated group, for example, by using a monomer containing an isocyanate group, the hydroxyl group of the above-mentioned acrylic polymer reacts with the isocyanate group of the above-mentioned compound, and the ethylenically unsaturated group derived from the above-mentioned compound is introduced into the acrylic polymer.

[0103] Furthermore, when other monomers are used for the purpose of reacting with a compound having an ethylenically unsaturated group, from the perspective of adhesive properties such as thermosetting properties and cohesive strength of the adhesive, the amount of the other monomer (preferably a hydroxyl group-containing monomer) is suitably about 1% by weight or more of the total monomer components, preferably about 5% by weight or more, more preferably about 10% by weight or more, and may be about 12% by weight or more. Furthermore, from the perspective of maintaining good adhesive properties such as adhesion, the amount of the other monomer is suitably about 40% by weight or less of the total monomer components, preferably about 30% by weight or less, more preferably about 25% by weight or less, and may be about 20% by weight or less (e.g., 15% by weight or less).

[0104] In the acrylic polymer, as other monomer components, a polyfunctional monomer having a polymerizable functional group (typically a free radical polymerizable functional group) having an unsaturated double bond, such as at least two (meth)acryloyl groups and vinyl groups, can be included. As a monomer component, by using a polyfunctional monomer, the cohesive force of the adhesive can be improved. The polyfunctional monomer can be used as a cross-linking agent. There is no particular limitation on the polyfunctional monomer. For example, one suitable substance among the substances exemplified as the polyfunctional monomer contained in the adhesive layer described later can be used alone or in combination of two or more.

[0105] The usage amount of multifunctional monomer is not particularly limited, and can be suitably set in a manner to achieve the purpose of use of the multifunctional monomer. The usage amount of multifunctional monomer can be set to less than about 3 wt % of the above-mentioned monomer component, preferably less than about 2 wt %, more preferably less than about 1 wt % (e.g., less than about 0.5 wt %). The lower limit of the usage amount in the case of using multifunctional monomer is greater than 0 wt %, and is not particularly limited. Typically, by setting the usage amount of multifunctional monomer to more than about 0.001 wt % (e.g., more than about 0.01 wt %) of the monomer component, the use effect of the multifunctional monomer can be suitably exerted.

[0106] The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthetic methods for acrylic polymers, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization, can be appropriately adopted. For example, solution polymerization can be preferably adopted. As a monomer supply method when performing solution polymerization, a one-time feeding method in which all monomer raw materials are supplied at once, a continuous supply (dropping) method, a batch supply (dropping) method, etc. can be appropriately adopted. The polymerization temperature can be appropriately selected according to the types of monomers and solvents used, the type of polymerization initiator, etc., and can be set to, for example, about 20°C to 170°C (typically about 40°C to 140°C).

[0107] The solvent (polymerization solvent) used in solution polymerization can be appropriately selected from conventionally known organic solvents. For example, any one solvent selected from aromatic compounds such as toluene (typically aromatic hydrocarbons); acetates such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropyl alcohol (e.g., monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; or a mixture of two or more solvents can be used.

[0108] The initiator used in the polymerization can be appropriately selected from conventionally known polymerization initiators depending on the type of polymerization method. For example, although not particularly limited, azo-based polymerization initiators, peroxide-based polymerization initiators, redox-based polymerization initiators based on a combination of a peroxide and a reducing agent, and substituted ethane-based polymerization initiators can be used. As the polymerization initiator, for example, one or more of the substances exemplified as thermal polymerization initiators added to the adhesive layer described below can be selected and used.

[0109] The amount of the polymerization initiator used is not particularly limited and can be a typical amount depending on the polymerization method, polymerization mode, etc. For example, about 0.001 to 5 parts by weight (typically about 0.01 to 2 parts by weight, for example, about 0.01 to 1 part by weight) of the polymerization initiator can be used per 100 parts by weight of all monomer components to be polymerized.

[0110] The molecular weight of the polymer (for example, an acrylic polymer) is not particularly limited and can be set within an appropriate range depending on the required performance, etc. The weight average molecular weight (Mw) of the above polymer is approximately 1×10 4 The above is appropriate, for example, it can be about 10×10 4 By using a polymer having an Mw greater than a predetermined value, cohesion and adhesion can be achieved in a well-balanced manner. In some embodiments, the Mw may be 20×10 4 Above, it can be 30×10 4 Above, it can be about 40×10 4 Above, it can be about 50×10 4 For example, it can be about 55×10 4 The upper limit of the Mw of the above polymer is not particularly limited, and can be, for example, approximately 1000×10 4 Below, it can also be about 100×10 4 Here, Mw refers to a value obtained by gel permeation chromatography (GPC) in terms of standard polystyrene. As a GPC apparatus, for example, the model "HLC-8320GPC" (chromatographic column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) can be used.

[0111] (Polymer having ethylenically unsaturated groups)

[0112] In some embodiments, as a polymer, a polymer having ethylenically unsaturated groups such as acryloyl, methacryloyl, vinyl, and allyl groups can be used. According to the adhesive comprising a polymer having ethylenically unsaturated groups, in addition to the thermal curing brought about by the multifunctional monomers described later, by reacting the ethylenically unsaturated groups possessed by the polymer during heating, the adhesive is thermally cured, and more excellent heat-peelable properties can be obtained. In addition, according to the adhesive comprising a polymer having ethylenically unsaturated groups, the desired heat-peelable properties, heat-resistant peelable properties, and peel force reduction rate after heating can be achieved by using a smaller amount of multifunctional monomers. As a polymer having ethylenically unsaturated groups, for example, a polymer having ethylenically unsaturated groups in a side chain can be used. As a monomer component of a polymer having ethylenically unsaturated groups, one or more of the monomer components exemplified as the monomer components of the above-mentioned polymer can be used within the range of the above-mentioned content.

[0113] The amount of the ethylenically unsaturated group in the polymer with ethylenically unsaturated groups is not particularly limited. From the viewpoints of thermosetting properties, it is appropriate to be set to 0.01mmol (hereinafter, also referred to as mmol / g) or more relative to every 1g of polymer, and can be more than 0.1mmol / g or more than 0.5mmol / g. In addition, it is appropriate to set the amount of the ethylenically unsaturated group in the above-mentioned polymer to be less than 10.0mmol / g, can be less than 5.0mmol / g, can be less than 3.0mmol / g, can be less than 2.5mmol / g or less than 2.0mmol / g.

[0114] The amount of the ethylenically unsaturated group in the polymer can be measured by the following method when the ethylenically unsaturated group is a (meth)acryloyl group, for example.

[0115] First, 0.25 mg of the polymer to be measured was dissolved in 50 mL of THF (tetrahydrofuran), and 15 mL of methanol was added to obtain a solution. Next, 10 mL of 4N sodium hydroxide aqueous solution was added to the solution to obtain a mixed solution. The mixed solution was then stirred at 40°C for 2 hours. Furthermore, 10.2 mL of 4N methanesulfonic acid solution was added to the mixed solution and stirred. To this solution, 5 mL of desalted water was added, followed by 2 mL of methanol to prepare the measurement solution.

[0116] The (meth)acrylic acid content in the measurement solution was measured by HPLC (High Performance Liquid Chromatography) (absolute standard curve method), and the ethylenically unsaturated group content was calculated.

[0117] (HPLC measurement conditions)

[0118] Chromatographic column: Synergi 4μ Polar-RP 80A (4.6 mm × 250 mm) manufactured by Phenomenex

[0119] Column temperature: 40°C

[0120] Flow rate: 1.0 mL / min

[0121] Detector wavelength: 210nm

[0122] Eluent: THF (for HPLC) 55 / buffer (containing 0.2% phosphoric acid, 0.2% triethylamine) 45

[0123] Aqueous solution injection volume: 5μL

[0124] As a method for measuring the content of ethylenically unsaturated groups other than (meth)acryloyl groups, there is exemplified the method of measuring the bromine value in accordance with JIS K2605:1996. In this measurement method, the content of ethylenically unsaturated groups other than (meth)acryloyl groups can be determined by converting the number of grams of bromine (Br2) added to 100 g of the polymer being measured into the number of moles of bromine (Br2) added to 1 g of the polymer.

[0125] The method for introducing ethylenically unsaturated groups into polymers is not particularly limited. For example, it is possible to preferably adopt a method in which a compound having a functional group (functional group B) and an ethylenically unsaturated group that can react with the functional group (functional group A) introduced into the acrylic polymer by copolymerization and reacts in a manner such that the ethylenically unsaturated group does not disappear (typically a condensation reaction or an addition reaction). Examples of combinations of functional group A and functional group B include a combination of a carboxyl group and an epoxy group, a combination of a carboxyl group and an aziridine group, a combination of a hydroxyl group and an isocyanate group, etc. Among them, from the viewpoint of reaction tracking, a combination of a hydroxyl group and an isocyanate group is preferred. From the viewpoints of polymer design, it is particularly preferred that the acrylic polymer has a hydroxyl group and the above-mentioned compound has an isocyanate group.

[0126] As described above, the compound having an ethylenically unsaturated group may have a functional group B that can react with the functional group A. Suitable examples of such compounds include the isocyanate-containing monomers (isocyanate-containing compounds) exemplified as other monomers that can be used for the polymerization of acrylic polymers. Among them, 2-(meth)acryloyloxyethyl isocyanate is more preferred. By reacting the isocyanate group of the isocyanate-containing compound having an ethylenically unsaturated group with the hydroxyl group of the acrylic polymer to form a bond (specifically, a urethane bond), an acrylic polymer having an ethylenically unsaturated group can be obtained.

[0127] The amount of the compound having an ethylenically unsaturated group (e.g., an isocyanate group-containing monomer) added is not particularly limited. From the perspective of reactivity with the functional group A (e.g., a hydroxyl group) in the polymer, the amount of the compound having an ethylenically unsaturated group (e.g., an isocyanate group-containing monomer) added can be 1:1 to 2:1 molar amount of the functional group A (M A ) and the molar ratio of functional group B (isocyanate group) (M B ) molar ratio (M A / M B ) is set so as to be in the range of about 0.5 to 2 (for example, 1 to 1.5).

[0128] In the method of using a polymer with an ethylenically unsaturated group as a polymer, the content of the polymer with an ethylenically unsaturated group in the adhesive layer is not particularly limited. In some methods, it is appropriate that the usage amount of the polymer with an ethylenically unsaturated group is set to about 10% by weight or more of the polymer (specifically, the base polymer) contained in the adhesive layer as a whole, and can be about 50% by weight or more (for example, greater than 50% by weight), can be 70% by weight or more, can be 90% by weight or more, can be 95% by weight or more, and can also be 99 to 100% by weight. In some methods, the base polymer contained in the adhesive layer can be substantially composed of a polymer with an ethylenically unsaturated group.

[0129] In addition, in some embodiments, as a polymer, a polymer that does not substantially have ethylenically unsaturated groups such as acryloyl, methacryloyl, vinyl, and allyl groups can be used (the amount of ethylenically unsaturated groups is less than 0.01 mmol / g). It is appropriate that the amount of such a polymer used is about 10% by weight or more of the polymer (specifically, the base polymer) contained in the adhesive layer as a whole, and can be about 50% by weight or more (for example, greater than 50% by weight), can be 70% by weight or more, can be 90% by weight or more, can be 95% by weight or more, or can be 99-100% by weight. In some embodiments, the base polymer contained in the adhesive layer can be substantially composed of a polymer that does not substantially have ethylenically unsaturated groups.

[0130] (Multifunctional monomer)

[0131] In addition to the above-mentioned polymer, the adhesive layer also contains a multifunctional monomer. By including a multifunctional monomer in the adhesive layer, the multifunctional monomer is included in the adhesive (layer) in a pre-reaction (unreacted) state. Thus, after the adhesive is formed, the multifunctional monomer contained in the adhesive reacts with the thermal polymerization initiator described later during the heat treatment under specified conditions, reducing the adhesive force and achieving easy peeling when heated. By including a multifunctional monomer, a thermosetting adhesive having heat-resistant and easy peeling properties can be formed even after heat treatment. More specifically, usually, when being attached to an adherend, for example, when heated at a high temperature, the adhesive will be adsorbed on the surface of the adherend. Therefore, the adhesive force of the adhesive to the adherend is enhanced, and heavy peeling can occur. According to the technology disclosed herein, by including a multifunctional monomer together with the thermal polymerization initiator in the adhesive, the reaction (free radical polymerization reaction) of the multifunctional monomer and the thermal polymerization initiator is rapidly carried out during heating, and the adhesive can be cured before the adhesive is adsorbed to the adherend. Thus, the adhesive force to the adherend can be reduced. Furthermore, even after further heating, the adhesive strength to the adherend does not increase but remains within a specified range, thereby enabling the adhesive to exhibit excellent heat-peelability. It should be noted that the technology disclosed herein is not limited to the above-described considerations. The multifunctional monomers can be used alone or in combination of two or more.

[0132] It should be noted that, in this specification, the so-called multifunctional monomer refers to a polymerizable compound having two or more ethylenically unsaturated groups in one molecule, and also includes substances called oligomers. The above-mentioned ethylenically unsaturated group functions as a polymerizable functional group (typically a free radical polymerizable functional group). Examples of the ethylenically unsaturated groups possessed by the multifunctional monomer include acryloyl, methacryloyl, vinyl and allyl groups, but are not limited to these. Suitable examples of ethylenically unsaturated groups include acryloyl and methacryloyl. Among them, acryloyl is preferred. Hereinafter, compounds having two or more acryloyl and / or methacryloyl groups are sometimes referred to as multifunctional acrylic monomers. In addition, compounds having two or more vinyl groups are sometimes referred to as multifunctional vinyl monomers.

[0133] It is appropriate that the number of ethylenically unsaturated groups contained in one molecule of a multifunctional monomer is 3 or more, preferably 4 or more, more preferably 5 or more, and also 6 or more. The more ethylenically unsaturated groups a multifunctional monomer has, the better the curing property is during heating, and the easier it is to obtain a tendency to be easily peeled off by heating. In addition, by using a multifunctional monomer with more ethylenically unsaturated groups (functional groups), it is possible to obtain easily peeled off by heating with a relatively small amount of use. This also reduces the amount of released gas from the multifunctional monomer, which is advantageous. The upper limit of the number of ethylenically unsaturated groups in one molecule of a multifunctional monomer is not limited to a specific range, for example, it can be less than 50, can be less than 40, can be less than 30, can be less than 20, or can be less than 15. In some embodiments, the number of ethylenically unsaturated groups in one molecule of a multifunctional monomer can be, for example, less than 10, can be less than 8, or can be less than 6. The polyfunctional monomer having the above number of ethylenically unsaturated groups tends to easily achieve both good adhesiveness and heat-peelability, and also tends to be excellent in storage stability.

[0134] As the multifunctional monomer, various multifunctional acrylate monomers and multifunctional vinyl monomers having two or more ethylenically unsaturated groups can be used. Among these, multifunctional acrylate monomers are preferably used. Although not particularly limited, multifunctional acrylate monomers tend to exhibit desired properties through good compatibility when used in combination with acrylic polymers. Each of the multifunctional acrylate monomers and the multifunctional vinyl monomers can be used alone or in combination of two or more.

[0135] Examples of the polyfunctional monomer include 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl (meth)acrylate, alkylene oxide-modified bisphenol A di(meth)acrylate, alkylene oxide-modified neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, vinyl (meth)acrylate, diethylene glycol di(meth)acrylate, and the like. Bifunctional monomers such as alkenylbenzene; trifunctional monomers such as trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxy tri(meth)acrylate, glycerol propoxy triacrylate, tetramethylolmethane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate; quadrifunctional monomers such as pentaerythritol alkoxy tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate; pentafunctional monomers such as sorbitol penta(meth)acrylate and dipentaerythritol penta(meth)acrylate; hexafunctional monomers such as dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, alkylene oxide-modified hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate; and epoxy acrylates, polyester acrylates, and urethane acrylates having two or more functional groups. Among these, preferred examples include 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. Among these, dipentaerythritol hexa(meth)acrylate is particularly preferred.

[0136] Although not particularly limited, it is appropriate to use a multifunctional monomer with a molecular weight of 100 or more as the multifunctional monomer. In some preferred embodiments, the molecular weight of the multifunctional monomer can be, for example, 150 or more, 250 or more, 300 or more, 350 or more, 400 or more, 450 or more, or 500 or more. In addition, the molecular weight of the multifunctional monomer is generally about 100,000 or less, for example, about 10,000 or less (for example, less than 10,000) is appropriate, preferably 5,000 or less (for example, less than 5,000), 1,500 or less, 1,000 or less (for example, less than 1,000), 800 or less, or 600 or less. The use of a multifunctional monomer with a molecular weight within the above range is advantageous, for example, in terms of the preparation and coating properties of the adhesive composition. It should be noted that the above molecular weight is the manufacturer's nominal value or the molecular weight calculated based on the molecular structure. For a polyfunctional monomer having a molecular weight greater than or equal to a predetermined value, the value of the weight average molecular weight (Mw) in terms of standard polystyrene obtained by GPC may be employed.

[0137] In some preferred embodiments, as a multifunctional monomer, a multifunctional monomer having a weight loss rate of 1% or less (specifically, 1.0% or less) when reaching 180°C in TGA (thermogravimetric analysis) under a heating condition of 10°C / minute can be used. By using a heat-resistant multifunctional monomer having the above-mentioned 180°C heating weight loss rate of 1% or less (hereinafter also referred to as a "heat-resistant multifunctional monomer"), the adhesive layer has heat-resistant peelability based on the use of the multifunctional monomer, and the generation of released gas during heating is suppressed. By using the above-mentioned heat-resistant multifunctional monomer, it is possible to achieve both heat-resistant peelability and reduced released gas. From the viewpoint of reduced released gas, in some preferred embodiments, the 180°C heating weight loss rate of the heat-resistant multifunctional monomer is 0.9% or less, more preferably 0.8% or less, further preferably 0.7% or less, particularly preferably 0.6% or less, and may also be 0.5% or less. The lower limit of the weight loss rate of the heat-resistant multifunctional monomer when heated to 180°C is theoretically 0%, but in practice it can be 0.1% or more, 0.2% or more, or 0.3% or more. As the heat-resistant multifunctional monomer, trimethylolpropane triacrylate (TMPTA, weight loss rate of 1% when heated to 180°C) and dipentaerythritol hexaacrylate (DPHA, weight loss rate of 0.5% when heated to 180°C) are preferably used. The heat-resistant multifunctional monomers can be used alone or in combination of two or more.

[0138] Specifically, the 180°C heating weight loss rate of the polyfunctional monomer can be measured using a differential thermal analyzer (manufactured by TA Instruments, trade name "Discovery TGA") under measurement conditions of a temperature increase of 10°C / min, an air atmosphere, and a flow rate of 25 mL / min.

[0139] The content of the heat-resistant multifunctional monomer in the adhesive layer is not particularly limited. In some embodiments, relative to 100 parts by weight of the polymer (specifically, the base polymer. Suitably an acrylic polymer) contained in the adhesive layer, it can be about 1 part by weight or more, can be 5 parts by weight or more, and preferably 10 parts by weight or more. The appropriate amount of the heat-resistant multifunctional monomer may vary according to its molecular weight, number of functional groups, etc. In some preferred embodiments, from the viewpoint of easy peelability upon heating, the amount of the heat-resistant multifunctional monomer relative to 100 parts by weight of the above-mentioned polymer is 20 parts by weight or more, 30 parts by weight or more is appropriate, can be 40 parts by weight or more, can be 50 parts by weight or more, can be 60 parts by weight or more, can be 70 parts by weight or more, can be 80 parts by weight or more, can be 90 parts by weight or more, or can be 100 parts by weight or more. The upper limit of the content of the heat-resistant multifunctional monomer in the adhesive layer is not particularly limited and can be set in a manner to achieve the desired adhesive properties. In some embodiments, from the viewpoint of compatibility with the polymer (specifically, the base polymer, such as an acrylic polymer), it is appropriate to set the amount of the heat-resistant multifunctional monomer relative to 100 parts by weight of the above-mentioned polymer to be approximately 200 parts by weight or less, preferably 160 parts by weight or less, more preferably 150 parts by weight or less, further preferably 140 parts by weight or less, and can be 120 parts by weight or less, 90 parts by weight or less, or 70 parts by weight or less. In some other embodiments, the amount of the heat-resistant multifunctional monomer relative to 100 parts by weight of the above-mentioned polymer can also be approximately 50 parts by weight or less (e.g., less than 50 parts by weight). The amount of the heat-resistant multifunctional monomer limited in this manner can be preferably adopted in the method of using a polymer having an ethylenically unsaturated group.

[0140] The content of the multifunctional monomer in the adhesive layer is not particularly limited. In some embodiments, relative to 100 parts by weight of the polymer (specifically, the base polymer. Suitably an acrylic polymer) contained in the adhesive layer, it can be about 1 part by weight or more, can be 5 parts by weight or more, and preferably 10 parts by weight or more. The appropriate amount of the multifunctional monomer can be different according to its molecular weight, number of functional groups, etc. In some preferred embodiments, from the viewpoint of easy peeling by heating, the amount of the multifunctional monomer relative to 100 parts by weight of the above-mentioned polymer is more than 20 parts by weight, and it is appropriate to be more than 30 parts by weight, can be more than 40 parts by weight, can be more than 50 parts by weight, can be more than 60 parts by weight, can be more than 70 parts by weight, can be more than 80 parts by weight, can be more than 90 parts by weight, or can be more than 100 parts by weight. By making the adhesive layer include a sufficient amount of multifunctional monomer, so that when heated, the multifunctional monomer contained in the adhesive layer reacts rapidly, and the adhesive layer is thermally cured, thereby being able to achieve easy peeling by heating. The upper limit of the content of the multifunctional monomer in the adhesive layer is not particularly limited and can be set in a manner to achieve desired adhesive properties. In some embodiments, from the viewpoint of compatibility with a polymer (specifically, a base polymer. For example, an acrylic polymer), it is appropriate to set the amount of the multifunctional monomer relative to 100 parts by weight of the above-mentioned polymer to be approximately 200 parts by weight or less, preferably 160 parts by weight or less, more preferably 150 parts by weight or less, further preferably 140 parts by weight or less, and can be 120 parts by weight or less, can be 90 parts by weight or less, and can also be 70 parts by weight or less. In some other embodiments, the amount of the multifunctional monomer relative to 100 parts by weight of the above-mentioned polymer can also be approximately 50 parts by weight or less (for example, less than 50 parts by weight). The amount of the multifunctional monomer limited in this way can preferably be adopted in the manner of using a polymer with an ethylenically unsaturated group.

[0141] (Thermal polymerization initiator)

[0142] The adhesive layer contains, in addition to the aforementioned polymer and multifunctional monomer, a thermal polymerization initiator. Here, the term "thermal polymerization initiator" refers to a polymerization initiator that generates free radicals upon heating. By including a thermal polymerization initiator in the adhesive layer, the thermal polymerization initiator reacts with the multifunctional monomer during heat treatment under specified conditions, reducing the adhesive strength and achieving heat-resistant peelability. The inclusion of a thermal polymerization initiator allows for a thermosetting adhesive that exhibits heat-resistant, easy peelability even after heat treatment.

[0143] As a thermal polymerization initiator, a material that satisfies the desired reduction rate of peel force after heating can be selected and used, such as a peroxide-based polymerization initiator, an azo-based polymerization initiator, a redox-based polymerization initiator based on a combination of a peroxide and a reducing agent, a substituted ethane-based polymerization initiator, or any other suitable one or more of various thermal polymerization initiators. Of these, peroxide-based polymerization initiators are preferred. By using a peroxide-based initiator as a thermal polymerization initiator, even when using heat treatments with limited heating temperature and heating time (specifically, heat treatments below 180°C, more specifically, heat treatments between 120°C and 170°C), in other words, under a wide range of heat treatment conditions, it is easy to achieve heat-peelable properties and heat-resistant peelable properties, making it possible to ideally achieve the desired reduction rate of peel force after heating. One reason for this is believed to be the high initiation efficiency of peroxide-based polymerization initiators (particularly organic peroxide-based polymerization initiators). In addition, peroxide-based polymerization initiators are cracked by the -OO- possessed by the compound and generate free radicals (-O·), but the cleavage reaction is reversible, so it is believed that when the free radical does not collide with the ethylenically unsaturated group of a multifunctional monomer or polymer, the rebonding of -OO- will occur. When the heating temperature is low, even if a free radical is generated, due to its low mobility, the frequency of the above-mentioned rebonding also becomes higher. The initiator formed by this rebonding can undergo a cleavage reaction again within a specified heating time, and collides with multifunctional monomers and the like to react. Therefore, it is believed that even if the heating temperature and heating time are subjected to a limited heat treatment, if a peroxide-based polymerization initiator is used, thermal curing of the adhesive layer is also carried out, and heating easy peeling and heat-resistant easy peeling properties can be obtained. It should be noted that the technology disclosed herein is not limited to the above-mentioned investigation.

[0144] As peroxide-based polymerization initiator, for example, any polymerization initiator in organic peroxides such as diacyl peroxide, peroxyester, peroxydicarbonate, monoperoxycarbonate, peroxyketal, dialkyl peroxide, hydroperoxide, ketone peroxide, or hydrogen peroxide can be used. Wherein, preferably organic peroxide is used. As the suitable example of peroxide-based polymerization initiator, benzoyl peroxide-based compounds (typically dibenzoyl peroxide (BPO)) with a benzoyl group that can have a substituent can be enumerated. Peroxide-based polymerization initiator can be used alone or in combination of two or more.

[0145] Specific examples of peroxide-based polymerization initiators include BPO, 1,1-di(tert-hexylperoxy)cyclohexane, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 4,4-bis(tert-butylperoxy)butyl valerate, cumene hydroperoxide, 2,5-dimethyl-2,5-dihydroperoxyhexane , 1,3-bis(tert-butylperoxy)m-isopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, diisopropylbenzene hydroperoxide, tert-butylcumyl peroxide, didecanoyl peroxide, dilauroyl peroxide, 2,4-dichlorobenzoyl peroxide, di(4-tert-butylcyclohexyl) peroxydicarbonate, tert-butyl perbenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butyl hydroperoxide, di-tert-butyl peroxide, etc.

[0146] When the adhesive layer includes a peroxide-based polymerization initiator, the content of the peroxide-based polymerization initiator in the adhesive layer is not particularly limited. In some embodiments, it is appropriate to set it to more than 0.1 weight part relative to 100 weight parts of the polymer (specifically, the base polymer. For example, an acrylic polymer) contained in the adhesive layer, preferably more than 0.2 weight part, more preferably more than 0.3 weight part, further preferably more than 0.4 weight part, and also more than 0.5 weight part. The more the content of the peroxide-based polymerization initiator, the higher the collision frequency of the peroxide-based polymerization initiator and the ethylenically unsaturated group of the multifunctional monomer, etc., and the easier it is to carry out the curing reaction. In addition, in some embodiments, the amount of the peroxide-based polymerization initiator relative to 100 weight parts of the above-mentioned polymer can be, for example, less than about 10 weight parts, or less than about 5 weight parts. In some preferred embodiments, the amount of the peroxide-based polymerization initiator per 100 parts by weight of the polymer is suitably 3 parts by weight or less (less than 3 parts by weight), preferably 2.5 parts by weight or less, more preferably 2.0 parts by weight or less, further preferably 1.5 parts by weight or less, particularly preferably less than 1.2 parts by weight (e.g., 1.1 parts by weight or less), and can be 1.0 parts by weight or less (e.g., less than 1.0 parts by weight), 0.9 parts by weight or less, 0.8 parts by weight or less, 0.7 parts by weight or less, or 0.6 parts by weight or less. By ensuring that the total amount of the peroxide-based polymerization initiator is within the specified range, it is possible to achieve adhesive properties such as adhesive strength and storage stability while ideally achieving an adhesive having high-efficiency thermosetting properties and heat-peelable properties.

[0147] The content of the peroxide-based polymerization initiator in the adhesive layer can also be determined based on its relative relationship to the multifunctional monomer. In some embodiments, from the perspective of the collision frequency with the ethylenically unsaturated groups of the multifunctional monomer, the amount of the peroxide-based polymerization initiator relative to 100 parts by weight of the multifunctional monomer is appropriately set to 0.1 parts by weight or more, preferably 0.2 parts by weight or more, more preferably 0.3 parts by weight or more, further preferably 0.4 parts by weight or more, and may also be 0.5 parts by weight or more. In some embodiments, the amount of the peroxide-based polymerization initiator relative to 100 parts by weight of the multifunctional monomer can be, for example, less than 10 parts by weight, or less than approximately 5 parts by weight. In some preferred embodiments, the amount of the peroxide-based polymerization initiator relative to 100 parts by weight of the above-mentioned multifunctional monomer is appropriately 3 parts by weight or less (less than 3 parts by weight), preferably 2.5 parts by weight or less, more preferably 2.0 parts by weight or less, further preferably 1.5 parts by weight or less, particularly preferably less than 1.2 parts by weight (e.g., 1.1 parts by weight or less), and can be 1.0 parts by weight or less (e.g., less than 1.0 parts by weight), 0.9 parts by weight or less, 0.8 parts by weight or less, 0.7 parts by weight or less, or 0.6 parts by weight or less. Although not particularly limited, in embodiments using a polymer having substantially no ethylenically unsaturated groups as the polymer, it is preferable to adopt a relative relationship of the amount of the peroxide-based polymerization initiator relative to the amount of the above-mentioned multifunctional monomer.

[0148] In some embodiments, the adhesive layer may include only a peroxide-based polymerization initiator as a thermal polymerization initiator, or may include a peroxide-based polymerization initiator and a thermal polymerization initiator different from the peroxide-based polymerization initiator (a non-peroxide-based polymerization initiator). In embodiments using only a peroxide-based polymerization initiator, the effects of using the peroxide-based polymerization initiator can be maximized. The high initiation efficiency of peroxide-based polymerization initiators (specifically, organic peroxide-based polymerization initiators) leads to the following tendencies: for example, even when the amount of multifunctional monomer used is relatively small, thermal curing is sufficient. Furthermore, even when using a heat treatment with limited heating temperature and heating time, it is easy to achieve ideal heat-peelability. In embodiments using both a peroxide-based polymerization initiator and a non-peroxide-based polymerization initiator, the effects and characteristics of the non-peroxide-based polymerization initiator can be utilized. In some embodiments, it is appropriate that the proportion of the peroxide-based polymerization initiator contained in the adhesive layer to the total thermal polymerization initiator is set to about 10% by weight or more. From the perspective of effectively exerting the effect of the peroxide-based polymerization initiator, it is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 50% by weight or more (for example, greater than 50% by weight), and can be 55% by weight or more, or can be 60% by weight or more. In some preferred embodiments, the proportion of the peroxide-based polymerization initiator to the total thermal polymerization initiator is, for example, about 65% by weight or more, can be 75% by weight or more, can be 85% by weight or more, can be 95% by weight or more, or can be 99% by weight or more. In addition, the upper limit of the proportion of the peroxide-based polymerization initiator to the total thermal polymerization initiator is 100% by weight. In some embodiments, for example, it can be 90% by weight or less, can be 80% by weight or less, can be 70% by weight or less, or can be 60% by weight or less.

[0149] Non-peroxide polymerization initiators used as thermal polymerization initiators with peroxide-based polymerization initiators include, for example, azo-based polymerization initiators, redox-based polymerization initiators based on combinations of peroxides and reducing agents, and substituted ethane-based polymerization initiators. Specifically, examples include persulfates such as potassium persulfate and ammonium persulfate; azo compounds such as 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(2,4,4-trimethylpentane); substituted ethane-based initiators such as phenyl-substituted ethane; and redox-based initiators based on combinations of peroxides and reducing agents such as combinations of persulfates and sodium bisulfite, and combinations of peroxides and sodium ascorbate. These non-peroxide-based polymerization initiators can be used alone or in combination of two or more.

[0150] Although not particularly limited, in some embodiments, as a thermal polymerization initiator, a thermal polymerization initiator with a 10-hour half-life temperature of, for example, 50°C or more can be preferably used. Here, the so-called 10-hour half-life temperature of the polymerization initiator refers to the temperature at which the concentration of the initiator becomes half after 10 hours, and is used as an indicator of the decomposition rate of the polymerization initiator and the thermal decomposition property (free radical generation property) at a specified temperature. In this specification, the 10-hour half-life temperature of the thermal polymerization initiator is the nominal value recorded in the manufacturer's catalog, etc. In the case where there is no manufacturer's nominal value, the value measured using an appropriate solvent (such as toluene) can be used. Although it is believed that the thermal decomposition property of the thermal polymerization initiator in the adhesive is different from the thermal decomposition property in the solvent, the thermal polymerization initiator with a high 10-hour half-life temperature has a tendency to have excellent heat resistance and storage stability. From this point of view, the 10-hour half-life temperature of the thermal polymerization initiator can be above 55°C, above 60°C, above 65°C, or above 70°C. The upper limit of the 10-hour half-life temperature of the thermal polymerization initiator is, for example, 150° C. or lower, and preferably 120° C. or lower. In some embodiments, from the perspective of reactivity under heat treatment conditions where the heating temperature is limited, the 10-hour half-life temperature of the thermal polymerization initiator is preferably about 100° C. or lower (e.g., lower than 100° C.), and may be 95° C. or lower, 90° C. or lower, 85° C. or lower, or 80° C. or lower.

[0151] The amount of thermal polymerization initiator contained in the adhesive layer (the total content of the two or more when more than two types are included) is not particularly limited. In some embodiments, it is appropriate to set it to 0.1 parts by weight or more relative to 100 parts by weight of the polymer (specifically, the base polymer. For example, an acrylic polymer) contained in the adhesive layer, preferably 0.2 parts by weight or more, more preferably 0.3 parts by weight or more, further preferably 0.4 parts by weight or more, and also 0.5 parts by weight or more. The more the content of thermal polymerization initiator, the higher the frequency of collision between the thermal polymerization initiator and the ethylenically unsaturated groups of the multifunctional monomer, etc., and the easier it is to carry out the curing reaction. In addition, in some embodiments, the content of thermal polymerization initiator relative to 100 parts by weight of the above-mentioned polymer can be, for example, less than 10 parts by weight, or less than about 5 parts by weight. In some preferred embodiments, the amount of the peroxide-based polymerization initiator per 100 parts by weight of the polymer is suitably 3 parts by weight or less (less than 3 parts by weight), preferably 2.5 parts by weight or less, more preferably 2.0 parts by weight or less, further preferably 1.5 parts by weight or less, particularly preferably less than 1.2 parts by weight (e.g., 1.1 parts by weight or less), and can be 1.0 parts by weight or less (e.g., less than 1.0 parts by weight), 0.9 parts by weight or less, 0.8 parts by weight or less, 0.7 parts by weight or less, or 0.6 parts by weight or less. By ensuring that the content of the thermal polymerization initiator is within the specified range, it is possible to achieve adhesive properties such as adhesive strength and storage stability while ideally achieving an adhesive having high-efficiency thermosetting properties and heat-removable properties.

[0152] The content of the thermal polymerization initiator in the adhesive layer can also be determined by its relative relationship with the multifunctional monomer. In some embodiments, from the perspective of the collision frequency with the ethylenically unsaturated groups of the multifunctional monomer, it is appropriate to set the amount of the thermal polymerization initiator to be 0.1 parts by weight or more relative to 100 parts by weight of the multifunctional monomer, preferably 0.2 parts by weight or more, more preferably 0.3 parts by weight or more, further preferably 0.4 parts by weight or more, and also 0.5 parts by weight or more. In some embodiments, the amount of the thermal polymerization initiator relative to 100 parts by weight of the multifunctional monomer can be, for example, about 10 parts by weight or less, or about 5 parts by weight or less. In some preferred embodiments, the amount of the thermal polymerization initiator relative to 100 parts by weight of the above-mentioned multifunctional monomer is appropriately 3 parts by weight or less (less than 3 parts by weight), preferably 2.5 parts by weight or less, more preferably 2.0 parts by weight or less, further preferably 1.5 parts by weight or less, particularly preferably less than 1.2 parts by weight (e.g., 1.1 parts by weight or less), can be 1.0 parts by weight or less (e.g., less than 1.0 parts by weight), can be 0.9 parts by weight or less, can be 0.8 parts by weight or less, can be 0.7 parts by weight or less, and can also be 0.6 parts by weight or less. Although not particularly limited, in the embodiment of using a polymer having substantially no ethylenically unsaturated groups as the polymer, the relative relationship of the amount of the thermal polymerization initiator relative to the amount of the above-mentioned multifunctional monomer can be preferably adopted.

[0153] Although not particularly limited, in some preferred embodiments, from the viewpoint of effectively exerting the reduction in peel force caused by heating and achieving the desired peel force reduction rate after heating, the total proportion of the above-mentioned polymer (specifically, a base polymer, such as an acrylic polymer), a multifunctional monomer (such as a multifunctional acrylic monomer) and a thermal polymerization initiator (preferably a peroxide polymerization initiator) in the entire adhesive layer is appropriately 50 weight % or more (for example, greater than 50 weight % and less than 100 weight %), preferably 70 weight % or more, more preferably 80 weight % or more, further preferably 90 weight % or more, can be 95 weight % or more, can be 98 weight % or more, and can also be 99 weight % or more (for example, 99 to 100 weight %).

[0154] (cross-linking agent)

[0155] In the adhesive composition for forming the adhesive layer, a crosslinking agent can be contained as needed, mainly for the purpose of crosslinking within the adhesive layer or crosslinking the adhesive layer with its adjacent surface. The crosslinking agent is typically contained in the adhesive layer in the form after the crosslinking reaction. By using a crosslinking agent, the cohesive force of the adhesive layer can be appropriately adjusted.

[0156] The kind of cross-linking agent is not particularly limited, and can be selected from among the cross-linking agents known in the past, for example, according to the composition of adhesive, in adhesive layer, bring into play the mode of suitable cross-linking function with this cross-linking agent.As spendable cross-linking agent, can exemplify isocyanate cross-linking agent, epoxy cross-linking agent, oxazoline cross-linking agent, aziridine cross-linking agent, carbodiimide cross-linking agent, melamine cross-linking agent, urea cross-linking agent, metal alkoxide cross-linking agent, metal chelate cross-linking agent, metal salt cross-linking agent, hydrazine cross-linking agent, amine cross-linking agent etc..They can be used alone or in combination of two or more.From the viewpoint of realizing adhesiveness and cohesion well simultaneously from balanced property, preferably isocyanate cross-linking agent, epoxy cross-linking agent, oxazoline cross-linking agent, aziridine cross-linking agent, carbodiimide cross-linking agent, particularly preferably isocyanate cross-linking agent.

[0157] As the isocyanate crosslinking agent, a polyfunctional isocyanate compound having two or more functional groups can be used. Examples thereof include aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate. Examples of commercially available products include isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name “Coronate L”), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name “Coronate HL”), isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name “Coronate HX”), and trimethylolpropane / xylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., trade name “Takenate D-110N”).

[0158] As epoxy crosslinking agents, those having two or more epoxy groups per molecule can be used without particular limitation. Epoxy crosslinking agents having 3 to 5 epoxy groups per molecule are preferred. Specific examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi Gas Chemical, "EPICLON CR-5L" manufactured by DIC, "Denacol EX-512" manufactured by Nagase Chemtex, and "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd.

[0159] As the oxazoline-based crosslinking agent, any oxazoline-based crosslinking agent having one or more oxazoline groups in one molecule can be used without particular limitation.

[0160] Examples of the aziridine-based crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl)propionate] and trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)].

[0161] As the carbodiimide-based crosslinking agent, a low-molecular compound or a high-molecular compound having two or more carbodiimide groups can be used.

[0162] In some embodiments, an isocyanate cross-linking agent is used as a cross-linking agent. By using an isocyanate cross-linking agent, it is easy to form an adhesive that exerts adhesive properties such as adhesion and cohesion in a well-balanced manner and has good heat-resistance. An isocyanate cross-linking agent can be used alone or in combination of two or more. Although not particularly limited, the amount used when using an isocyanate cross-linking agent is preferably less than 1 part by weight relative to 100 parts by weight of the polymer (specifically, a base polymer. For example, an acrylic polymer) contained in the adhesive layer. It is believed that by limiting the amount of isocyanate cross-linking agent used, the cross-linking density is appropriately suppressed. At this cross-linking density, during heat treatment, multifunctional monomers and the like frequently collide with thermal polymerization initiators and are thermally cured, showing heat-resistance and heat-resistant stripping properties, thereby achieving the desired reduction rate of peeling force after heating. It should be noted that the technology disclosed herein is not limited to the above-mentioned investigations. From the above viewpoint, in some preferred embodiments, the usage amount of the isocyanate cross-linking agent relative to 100 parts by weight of the above-mentioned polymer is 0.9 parts by weight or less, can be 0.8 parts by weight or less, can be 0.7 parts by weight or less, can be 0.6 parts by weight or less, can be 0.5 parts by weight or less, can be 0.4 parts by weight or less, can be 0.3 parts by weight or less, can be 0.2 parts by weight or less, and can also be 0.1 parts by weight or less. By limiting the usage amount of the isocyanate cross-linking agent, there is a tendency to easily obtain high bonding strength. In addition, the usage amount of the isocyanate cross-linking agent relative to 100 parts by weight of the above-mentioned polymer can be, for example, set to 0.01 parts by weight or more, in some preferred embodiments, can be 0.05 parts by weight or more, can be 0.1 parts by weight or more, can be 0.3 parts by weight or more, and can also be 0.5 parts by weight or more. By appropriately setting the usage amount of the isocyanate cross-linking agent within the above-mentioned range, it is possible to ideally achieve the effect brought about by the technology disclosed herein, and ideally obtain an adhesive that can well-balance the bonding properties such as bonding strength and cohesion.

[0163] About the usage amount when using a cross-linking agent (being their total amount when using more than two cross-linking agents), from the viewpoint of realizing a well-balanced adhesive that gives play to the adhesive properties such as bonding force and cohesion, relative to 100 weight parts of the polymer (specifically base polymer. For example, acrylic acid-based polymer) contained in the adhesive layer, it is an amount more than 0 weight part, for example, it can be set to more than 0.001 weight part, and it can also be set to more than 0.01 weight part. In some preferred embodiments, the usage amount of the cross-linking agent relative to 100 weight parts of the above-mentioned polymer can be more than 0.05 weight part, can be more than 0.1 weight part, can be more than 0.3 weight part, and it can also be more than 0.5 weight part. In addition, the upper limit of the usage amount of the cross-linking agent can be different according to the cross-linking agent type used, and is therefore not limited to a specific scope, but from the viewpoint of realizing good heat-resistant peelability, the manifestation of heat-resistant peelability, and then the desired peeling force reduction rate after heating, it is preferably limited to below the specified amount. It is believed that by limiting the usage amount of the cross-linking agent, the cross-linking density is appropriately suppressed. Under this cross-linking density, when heat treated, the multifunctional monomer etc. frequently collides with the thermal polymerization initiator and is thermally cured, showing heat-resistant easy peelability and heat-resistant easy peelability, and then achieving the desired peeling force reduction rate after heating. It should be noted that the technology disclosed herein is not limited to the above-mentioned investigation. For example, relative to 100 parts by weight of the above-mentioned polymer, it is appropriate that the usage amount of the cross-linking agent is set to be less than 10 parts by weight. In some ways, it is preferably less than 5 parts by weight, or less than 3 parts by weight. In some ways, relative to 100 parts by weight of the above-mentioned polymer, it is appropriate that the usage amount of the cross-linking agent is set to be less than 1 part by weight, preferably less than 0.9 parts by weight, can be less than 0.8 parts by weight, can be less than 0.7 parts by weight, can be less than 0.6 parts by weight, can be less than 0.5 parts by weight, can be less than 0.4 parts by weight, can be less than 0.3 parts by weight, can be less than 0.2 parts by weight, or can be less than 0.1 parts by weight. By limiting the usage amount of the cross-linking agent, there is a tendency to easily obtain high bonding strength.

[0164] In order to carry out the cross-linking reaction more effectively, a cross-linking catalyst can be used. As a cross-linking catalyst, metal cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, triacetylacetonate iron, butyl tin oxide, and dioctyltin dilaurate are exemplified. The amount of the cross-linking catalyst used is not particularly limited. The amount of the cross-linking catalyst used can be set to, for example, about 0.0001 parts by weight or more, about 0.001 parts by weight or more, or about 0.005 parts by weight or more relative to 100 parts by weight of the polymer (specifically, the base polymer. For example, an acrylic polymer) contained in the adhesive layer. In addition, it can be set to about 1 part by weight or less, about 0.1 part by weight or less, or about 0.05 part by weight or less.

[0165] The adhesive composition used to form the adhesive layer may, if desired, contain a compound that undergoes keto-enol tautomerism as a crosslinking retardant. For example, in an adhesive composition containing an isocyanate crosslinking agent or an adhesive composition that can be used in combination with an isocyanate crosslinking agent, a compound that undergoes keto-enol tautomerism is preferably used. This can extend the pot life of the adhesive composition.

[0166] Various β-dicarbonyl compounds can be used as compounds that produce keto-enol tautomerism. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetic esters such as methyl acetoacetate and ethyl acetoacetate; propionylacetic esters such as ethyl propionylacetate; isobutyrylacetic esters such as ethyl isobutyrylacetate; and malonic esters such as methyl malonate and ethyl malonate. Suitable compounds include acetylacetone and acetoacetic esters. Compounds that produce keto-enol tautomerism can be used alone or in combination of two or more.

[0167] The amount of the compound that produces keto-enol tautomerism used can be, for example, 0.1 parts by weight to 20 parts by weight relative to 100 parts by weight of the polymer (specifically, the base polymer, for example, an acrylic polymer) contained in the adhesive layer, and it is appropriate to set it to 0.5 parts by weight to 15 parts by weight. For example, it can be set to 1 part by weight to 10 parts by weight, or it can be set to 1 part by weight to 5 parts by weight.

[0168] (monofunctional monomer)

[0169] In addition, the adhesive layer may also contain one or more monofunctional monomers containing one ethylenically unsaturated group in one molecule, as desired. Monofunctional monomers can be used within the scope of the effect brought about by the technology disclosed herein. As monofunctional monomers, known monofunctional acrylate monomers and vinyl monomers can be used. Although not particularly limited, it is appropriate for the content of the monofunctional monomer in the adhesive layer to be less than about 100 parts by weight (0 parts by weight and less than 100 parts by weight) relative to 100 parts by weight of the multifunctional monomer. For example, less than 100 parts by weight) can be less than 50 parts by weight, less than 30 parts by weight, less than 10 parts by weight, or less than 1 part by weight. The technology disclosed herein can be implemented in a manner such that the adhesive layer does not substantially contain monofunctional monomers.

[0170] (Other ingredients)

[0171] The adhesive layer may contain various additives commonly used in the adhesive field, such as adhesion-imparting agents, silane coupling agents, release force modifiers (surfactants, etc.), viscosity modifiers (e.g., tackifiers), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, and anti-aging agents, as needed. For such various additives, conventionally known additives can be used by conventional methods, and since they do not particularly characterize the present invention, detailed descriptions are omitted.

[0172] It should be noted that the technology disclosed herein can achieve desired adhesive properties such as adhesion without using an adhesion-imparting agent. In some embodiments, the content of the adhesion-imparting agent in the adhesive layer can be, for example, less than 10 parts by weight, and further can be less than 5 parts by weight relative to 100 parts by weight of the polymer (specifically, a base polymer, such as an acrylic polymer) contained in the adhesive layer. The content of the above-mentioned adhesion-imparting agent can be less than 1 part by weight (for example, less than 0.5 parts by weight), or less than 0.1 parts by weight (more than 0 parts by weight and less than 0.1 parts by weight). The adhesive layer can be a substance that does not contain an adhesion-imparting agent.

[0173] (Form of Adhesive Composition)

[0174] Although not particularly limited, the technology disclosed herein can be preferably implemented using a solvent-based adhesive composition. The above-mentioned solvent-based adhesive composition is an adhesive composition in the form of an adhesive-forming component contained in an organic solvent. The solvent-based adhesive composition typically contains a solution polymer of a monomer component, a multifunctional monomer and a thermal polymerization initiator, and optionally other additives. In the form of a solvent-based adhesive (layer), the effect brought about by the technology disclosed herein can be effectively exerted. The solvent contained in the solvent-based adhesive composition can be appropriately selected from conventionally known organic solvents. For example, any one solvent selected from the following, or a mixed solvent of two or more, can be used, namely: aromatic compounds such as toluene (typically aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; and the like.

[0175] (Formation of Adhesive Layer)

[0176] Adhesive layer disclosed herein can be formed by known methods in the past. After adhesive composition is given (such as applied) to suitable surface, by suitably implementing curing treatment, adhesive can be formed with the form of stratiform (adhesive layer). The curing means (such as drying, crosslinking, polymerization, cooling etc.) of adhesive composition can only be applicable to 1 kind, also can be applicable to 2 kinds or more simultaneously or in multiple stages. In the case of solvent-based adhesive composition, typically, said composition can be made to dry (preferably further crosslinked) and form adhesive.

[0177] For example, under the situation of the two-sided adhesive sheet of no base material, can adopt following method: after giving adhesive composition to the surface (peeling surface) with peelability, by making this adhesive composition solidify and on this surface, form adhesive layer.Under the situation of the adhesive sheet with base material, can adopt by this base material directly giving (typically coating) adhesive composition and making it solidify and form the method (direct method) of adhesive layer.In addition, also can adopt by giving adhesive composition to the surface (peeling surface) with peelability and making it solidify and on this surface, form adhesive layer, and this adhesive layer is transferred to the method (transfer method) of base material.As above-mentioned peeling surface, can utilize the surface of release liner, through peeling the base material back side etc. of processing.It should be noted that, adhesive layer disclosed here typically forms continuously, but is not limited to such form, for example, can also be formed as the adhesive layer of the regular or random pattern such as dot-shaped, strip.

[0178] The adhesive composition can be applied using a known or customary coating machine such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a die coater, a rod coater, an air knife coater, or a spray coater. Alternatively, the adhesive composition can be applied by impregnation or curtain coating.

[0179] From the viewpoints of promoting the cross-linking reaction and improving the manufacturing efficiency, the drying of the adhesive composition is preferably carried out under heating. The drying temperature is not particularly limited, and can be set to about 40 to 100°C, and is generally preferably set to about 60 to 80°C. For example, the heating temperature of the drying at the above temperature (for example, about 1 to 10 minutes, more specifically about 3 to 7 minutes) is low, and sometimes the volatilization of the solvent is also in progress. In the adhesive composition containing a multifunctional monomer and a thermal polymerization initiator, the reaction of the multifunctional monomer and the deactivation of the thermal polymerization initiator are negligible. In addition, after the adhesive composition is dried, aging can be further performed for the purpose of adjusting the component transfer in the adhesive layer, carrying out the cross-linking reaction, and relaxing the strain that may exist in the substrate and the adhesive layer.

[0180] (thickness)

[0181] The thickness of the adhesive layer is not particularly limited. The thickness of the adhesive layer is generally 1 μm or more, may be 2 μm or more, or may be 3 μm or more. There is a tendency that the greater the thickness of the adhesive layer, the higher the adhesion to the adherend. In some preferred embodiments, the thickness of the adhesive layer is 5 μm or more, may be 7 μm or more, or may be 9 μm or more. It is appropriate to set the upper limit of the thickness of the adhesive layer to be about 200 μm or less, for example, 100 μm or less (for example, less than 100 μm), or 50 μm or less. By limiting the thickness of the adhesive layer to a specified range, the generation of residual adhesive caused by cohesive failure is prevented, and there is a tendency to easily obtain easy peelability. In addition, a thin adhesive layer is advantageous in terms of thinning the adhesive sheet, and there is a tendency that the followability to the adherend is also excellent. In some preferred embodiments, the thickness of the adhesive layer is 40 μm or less, may be 30 μm or less (for example, less than 30 μm), may be 20 μm or less, or may be 15 μm or less.

[0182] <Base Material Layer>

[0183] The adhesive sheet disclosed herein may include a substrate layer. As a substrate (layer) supporting (lining) the adhesive layer, various sheet-like substrates can be used. As the above-mentioned substrate, resin film, paper, cloth, rubber sheet, foam sheet, metal foil, their composites, etc. can be used. As examples of resin films, polyolefin films such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymers can be mentioned; polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); vinyl chloride resin film; vinyl acetate resin film; polyamide resin film; fluororesin film; cellophane; etc. As other examples of resin films, resin films formed of one or more engineering plastics (which may be super engineering plastics) such as polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyetheretherketone resin, polyarylate resin, polyamideimide resin, and polyimide resin can be mentioned. The use of engineering plastics is preferred from the viewpoint of heat resistance. Examples of paper include Japanese paper, kraft paper, glassine, woodfree paper, synthetic paper, and coated paper. Examples of cloth include woven or non-woven fabrics obtained by spinning various fibrous materials singly or in blends. Examples of the above-mentioned fibrous materials include cotton, staple fiber, Manila hemp, pulp, rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber, and polyolefin fiber. Examples of rubber sheets include natural rubber sheets and butyl rubber sheets. Examples of foam sheets include foamed polyurethane sheets and foamed polychloroprene rubber sheets. Examples of metal foils include aluminum foil and copper foil.

[0184] In some preferred embodiments, a resin film having a specified rigidity (strength) and excellent processability and operability is used as a substrate (layer). Among them, a polyester film is preferably used as the resin film substrate. It should be noted that in this specification, the so-called "resin film" is typically a non-porous film, typically refers to a resin film that does not substantially contain bubbles (no voids). Therefore, the above-mentioned resin film is a concept that is different from foam film and non-woven fabric. The density of the resin film that can be used as a substrate can be about 0.85 to 1.50 g / cm 3 (e.g. 0.90 g / cm 3 ~1.20g / cm 3 , typically 0.92 g / cm 3 ~1.05g / cm 3 The resin film may be a single-layer structure or a multi-layer structure with two or more layers (eg, a three-layer structure).

[0185] The base layer (e.g., resin film) may be mixed with known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, and antiblocking agents as needed. The amount of the additives is not particularly limited and can be appropriately set according to the intended use.

[0186] The method for producing the resin film is not particularly limited, and for example, conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting, and calendar roll molding can be appropriately adopted.

[0187] The substrate layer may be substantially composed of a resin film. Alternatively, the substrate layer may include an auxiliary layer in addition to the resin film. Examples of the auxiliary layer include optical property adjustment layers (e.g., coloring layers, antireflection layers), printed layers for imparting a desired appearance, laminate layers, antistatic layers, primer layers, release layers, and other surface treatment layers.

[0188] The thickness of the substrate layer is not particularly limited and can be appropriately selected according to the purpose, and can generally be 1 to 500 μm. From the viewpoints of processability, usability, operability, etc., it is appropriate that the thickness of the substrate layer is more than 2 μm (for example, more than 3 μm, typically more than 5 μm), can be about 7 μm or more, or can be more than 10 μm. In addition, it is appropriate that the thickness of the substrate layer is about 200 μm or less. From the viewpoint of lightweight and thin thickness, it is preferably about 100 μm or less, more preferably about 50 μm or less, can be 30 μm or less, can be 20 μm or less, or can be 15 μm or less. When the thickness of the substrate layer becomes smaller, there is a tendency for the softness of the adhesive sheet and the followability of the surface shape of the adherend to be improved.

[0189] The adhesive layer side surface of the substrate layer can be subjected to corona treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, coating of primer (primer) and other known surface treatments as needed. Such surface treatment can be used to improve the adhesion of the substrate layer and the adhesive layer. In other words, it can be used to improve the anchoring property of the adhesive layer to the substrate layer. The composition of the primer is not particularly limited and can be appropriately selected from known substances. The thickness of the primer layer is not particularly limited, and for example, about 0.01 μm to 1 μm is appropriate, preferably about 0.1 μm to 1 μm. In addition, the back of the substrate layer can be subjected to surface treatments such as the above-mentioned various surface treatments, antistatic treatment, etc.

[0190] <Total Thickness>

[0191] The total thickness of the adhesive sheet disclosed herein (which may include an adhesive layer and a substrate layer, but does not contain a release liner) is not particularly limited, and it is appropriate to set it in the range of about 5 to 1000 μm. From the viewpoints of adhesive properties, usability, etc., the total thickness of the adhesive sheet can be 10 μm or more, 15 μm or more, or 20 μm or more. In some embodiments, the total thickness of the adhesive sheet can be 30 μm or more, 40 μm or more, or 50 μm or more. In addition, from the viewpoint of lightweight and thin thickness, in some embodiments, the total thickness of the adhesive sheet is 500 μm or less, or 300 μm or less. In some preferred embodiments, the total thickness of the adhesive sheet is 100 μm or less (for example, less than 100 μm), more preferably 80 μm or less, or 70 μm or less. Reducing the thickness of the adhesive sheet is also advantageous in terms of filmization, miniaturization, lightweighting, and resource saving.

[0192] <Release liner>

[0193] The release liner used in the adhesive sheet disclosed herein is not particularly limited. For example, release liners having a release-treated surface of a backing substrate such as a resin film or paper, or release liners formed from low-adhesion materials such as fluorine-based polymers (polytetrafluoroethylene, etc.) or polyolefin-based resins (polyethylene, polypropylene, etc.) can be used. For example, silicone-based or long-chain alkyl-based release agents can be used. In some embodiments, a release liner using a release-treated resin film is preferably used.

[0194] <Peeling method>

[0195] According to this specification, a method for peeling an adhesive sheet adhered to an adherend from the adherend is provided. The peeling method includes the steps of: heating the adherend to which the adhesive sheet is adhered at a temperature exceeding 100°C, and then peeling the adhesive sheet from the adherend. The adhesive sheet disclosed herein exhibits heat-peelability (heat-resistant peelability) and can exhibit heat-peelability even when subjected to heat treatments with limited heating temperature and heating time. Therefore, even after exposure to heat exceeding 100°C, the adhesive sheet can be easily peeled from the adherend.

[0196] In some embodiments, the temperature for heat treatment of an adherend to which the adhesive sheet is attached can be approximately 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, or 170°C or higher. The upper limit of the heat treatment temperature varies depending on the purpose of the heat treatment, the heat resistance of the adherend, and other factors, but is generally approximately 260°C or lower, 250°C or lower, 230°C or lower, 200°C or lower, or 180°C or lower. In some preferred embodiments, the heat treatment temperature can be lower than 180°C, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, or 120°C or lower. The adhesive sheet disclosed herein can exhibit heat-peelable properties even when subjected to heat treatment at a limited temperature, as described above. The time of the heat treatment is not particularly limited and may be within 10 hours, within 5 hours, or within 3 hours. However, from the perspective of the efficiency of the heating process, in some preferred embodiments, it may be within 1 hour, within 30 minutes, within 15 minutes, within 10 minutes, or within 5 minutes. The adhesive sheet disclosed herein is cured by the above-mentioned short-time heat treatment, and can exhibit heat-resistance. In addition, the time of the heat treatment may be more than 1 minute, more than 3 minutes, more than 5 minutes, more than 7 minutes, or more than 9 minutes. In some embodiments, the time of the heat treatment may be more than 10 minutes, more than 30 minutes, more than 60 minutes, more than 1 hour, more than 3 hours, more than 4 hours, or more than 5 hours. The adhesive sheet disclosed herein is cured by the heat treatment based on the above-mentioned heating temperature, and the peeling force is reduced. Even if the heated state continues for a long time, the rise in peeling force (heavy peeling) will not occur or will be suppressed. Therefore, heat-resistance (heat-resistant peeling) can be maintained even after a long period of heat treatment. There is no particular upper limit to the heating treatment time, but from the perspective of heating process efficiency, it can be within 10 hours, within 5 hours, or within 3 hours. As described above, the adhesive sheet disclosed herein can cope with a wide range of heating treatment conditions, including those with limited heating temperature and heating time. Therefore, it has few restrictions on heating treatment conditions, a wide range of applications, and is useful.

[0197] <Purpose>

[0198] The use of the adhesive sheet disclosed herein is not particularly limited. The adhesive sheet disclosed herein has heat-peelable properties that can cope with a wide range of heat treatment conditions including heat treatment conditions with limited heating temperature and heating time. Therefore, it can be used as an adhesive sheet for various uses that require heat-peelable properties, such as uses that utilize such heating to peel off from an adherend. For example, when attached to an adherend, it can be preferably used for uses that are exposed to heating exceeding 100°C (for example, about 120°C or more and 260°C or less). As such uses, for example, masking uses, temporary fixing uses, and protective uses that require heat resistance for the adhesive sheet can be cited. In addition, for example, it can also be preferably used as a process material that is fixed to an adherend and peeled off in the manufacturing process of electronic equipment and electronic components. In addition, as a suitable use of the adhesive sheet disclosed herein, semiconductor element manufacturing uses can be cited. For example, in semiconductor wafer processing (typically silicon wafer processing), it can be preferably used as a wafer fixing sheet that fixes the wafer to a fixing plate. In addition, the adhesive sheet disclosed herein can also be preferably used as a protective sheet for protecting the wafer during the above-mentioned wafer processing. In particular, when manufacturing semiconductor elements, they are exposed to heating during the processing steps, etc., so it is preferred to use an adhesive sheet with heat-resistant and easy-to-peel properties. In addition, the adhesive sheet disclosed herein can also be applied to optical uses requiring heat resistance. More specifically, for example, as an optical adhesive sheet for use in bonding optical components (optical component bonding), for manufacturing purposes of products (optical products) using the above-mentioned optical components, the adhesive sheet disclosed herein can be used. It should be noted that the above-mentioned optical component refers to a component with optical properties (for example, polarization, light refraction, light scattering, light reflectivity, light transmittance, light absorption, light diffraction, optical rotation, visual recognition, etc.).

[0199] The type of material for pasting (adherend material) disclosed herein is not particularly limited. The adhesive sheet disclosed herein can be used for fixing and protecting various components and materials. Examples of adherend materials include: glasses such as alkaline glass and alkali-free glass; metal materials such as stainless steel (SUS) and aluminum; ceramic materials such as alumina and silica; resin materials such as polyester resins such as PET, acrylic resins, ABS resins, polycarbonate resins, polystyrene resins, and transparent polyimide resins; and so on. Suitable examples of adherend materials include glass materials such as alkaline glass, semiconductor wafers, etc. The above-mentioned glass material can be, for example, a glass plate having a surface partially provided with a transparent conductive film (such as ITO (indium tin oxide) film) and an FPC (flexible circuit board) that can be used for tablet personal computers, mobile phones, organic LEDs (light emitting diodes), etc.

[0200] The matters disclosed in this specification include the following.

[0201] [1] An adhesive sheet having an adhesive layer,

[0202] The adhesive layer comprises a polymer, a multifunctional monomer and a thermal polymerization initiator.

[0203] Peel force reduction rate after heating S 150-5 And the peeling force reduction rate after heating S 180-120 All of them are above 50%, among which,

[0204] The above peeling force reduction rate after heating S 150-5 Calculated by the following formula:

[0205] S 150-5 [%] = (1-(N 150-5 / N0))×100

[0206] (In the above formula, N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 150-5 The peeling force (N) after heating at 150°C for 5 minutes was measured at 23°C and 50% RH. 150-5 [N / 20mm].)

[0207] The above peeling force reduction rate after heating S 180-120 Calculated by the following formula:

[0208] S 180-120 [%] = (1-(N 180-120 / N0))×100

[0209] (In the above formula, N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 180-120 The peeling force (N) after heating at 180°C for 120 minutes on a glass plate was measured at 23°C and 50% RH. 180-120 [N / 20mm].)

[0210] [2] The adhesive sheet according to [1] above, wherein the peeling force N0 to the glass plate is 2.0 N / 20 mm or more.

[0211] [3] The adhesive sheet according to [1] or [2] above, wherein the thermal polymerization initiator comprises a peroxide-based polymerization initiator.

[0212] [4] The adhesive sheet according to any one of [1] to [3] above, wherein the content of the crosslinking agent in the adhesive layer is 0.9 parts by weight or less based on 100 parts by weight of the polymer.

[0213] [5] The adhesive sheet according to any one of [1] to [4] above, wherein the peel strength reduction rate after heating S 130-5 More than 50%, of which

[0214] The above peeling force reduction rate after heating S 130-5 Calculated by the following formula:

[0215] S 130-5 [%] = (1-(N 130-5 / N0))×100

[0216] (In the above formula, N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 130-5 The peeling force (N) after heating at 130°C for 5 minutes was measured at 23°C and 50% RH. 130-5 [N / 20mm].)

[0217] [6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the polymer comprises an acrylic polymer.

[0218] [7] The pressure-sensitive adhesive sheet according to any one of [1] to [6] above, wherein the polyfunctional monomer comprises a polyfunctional acrylate monomer.

[0219] [8] A peeling method for peeling the adhesive sheet according to any one of [1] to [7] above, which is attached to an adherend, comprising:

[0220] A step of heat-treating the adherend to which the pressure-sensitive adhesive sheet is attached at a temperature higher than 100° C. and then peeling the pressure-sensitive adhesive sheet from the adherend.

[0221] Example

[0222] Hereinafter, some embodiments of the present invention will be described, but it is not intended that the present invention be limited to the contents shown in these embodiments. It should be noted that, unless otherwise specified, in the following description, "parts" and "%" are based on weight.

[0223] <Evaluation Method>

[0224] (Peel force N0 before heating)

[0225] The adhesive sheet is cut into a size of 20mm in width and 100mm in length. Under the environment of 23°C and 50%RH, a 2kg roller is reciprocated once and the adhesive surface of the adhesive sheet is pressed and applied to an alkaline glass plate (made by Songlang Glass Industry Co., Ltd., with a thickness of 1.35mm and a blue plate edge grinding product) as an adherend. Under the same environment, the alkaline glass plate with the above-mentioned adhesive sheet is left to stand for 6 hours and used as an evaluation sample. The above-mentioned evaluation sample is set in a tensile testing machine under the environment of 23°C and 50%RH, and the peel strength (peeling force N0 before heating) [N / 20mm width] when the adhesive sheet is peeled from the adherend is measured under the conditions of a peeling angle of 180 degrees and a speed of 300mm / minute. As a tensile testing machine, the product name "EZ-S 500N" made by Shimadzu Corporation or its equivalent can be used. In addition, when the evaluation object is a two-sided adhesive sheet, the non-measurement surface is lined with a PET film to implement the measurement.

[0226] (Peel strength after heating)

[0227] Using an adhesive sheet, an evaluation sample is prepared by the method described in the measurement of the peeling force N0 before heating. The obtained evaluation sample is heated in an oven set to each temperature (heating temperature T) of 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C for each time (heating time m) of 5 minutes, 60 minutes or 120 minutes, taken out of the oven, and allowed to stand for 30 minutes in an environment of 23°C and 50% RH. Then, the above-mentioned evaluation sample is placed in a tensile testing machine under the same environment, and the peeling strength (peeling force N0 after heating) when the adhesive sheet is peeled off from the adherend at a peeling angle of 180 degrees and a speed of 300 mm / min is measured. T-m ) [N / 20mm width]. Regarding the adherend, tensile testing machine, and other matters, the measurement of the peeling force N0 before heating is the same. It should be noted that the symbol N representing the peeling force after heating is T-m , T and m are the heating temperature T [°C] and heating time m [minutes] in the heat treatment performed before measuring the peel strength. For example, the peel strength after heating at 120°C for 5 minutes is expressed as N 120-5 .

[0228] (Peel force reduction rate after heating)

[0229] The peeling force N0 [N / 20mm] before heating and the peeling force N0 [N / 20mm] after heating are T-m [N / 20mm] is substituted into the following formula to calculate the peeling force reduction rate S after heating. T-m [%].

[0230] S T-m [%] = (1-(NT-m / N0))×100

[0231] It should be noted that the symbol S represents the rate of reduction in peeling force after heating. T-m In the equation, T and m refer to the peeling force reduction rate after heating N. T-m T and m correspond to the heating temperature T [°C] and heating time m [minutes] respectively. For example, the peeling force after heating N is measured after heating at 120°C for 5 minutes. 120-5 The peel force reduction rate after heating relative to the peel force N0 is expressed as S 120-5 .

[0232] <Example 1>

[0233] (Preparation of Adhesive Composition)

[0234] Into a reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer, and a stirrer, 85 parts of methoxyethyl acrylate (MEA), 10 parts of N-vinyl-2-pyrrolidone (NVP), 5 parts of 4-hydroxybutyl acrylate (4HBA), and 0.5 parts of acrylic acid (AA) as monomer components, 300 parts of ethyl acetate as a polymerization solvent, and 0.2 parts of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were added, and a polymerization reaction (solution polymerization) was carried out at 61°C for 6 hours under a nitrogen atmosphere to obtain a solution containing acrylic polymer A.

[0235] To the solution of the acrylic polymer A, 100 parts of dipentaerythritol hexaacrylate (DPHA) as a multifunctional monomer, 0.1 part of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E"), and 0.5 part of benzoyl peroxide (manufactured by NOF Corporation, product name "NYPER BW", 10-hour half-life temperature: approximately 73°C) as a thermal polymerization initiator were added based on 100 parts of the acrylic polymer A, and the mixture was uniformly mixed to prepare the solvent-based adhesive composition of this example.

[0236] (Production of Adhesive Sheet)

[0237] The adhesive composition obtained in the above manner was applied to the release surface of a commercially available PET release liner and dried at 80°C for 5 minutes to form a 10 μm thick adhesive layer. A 50 μm thick PET film was laminated to this adhesive layer to produce the adhesive sheet (single-sided adhesive sheet with a substrate) involved in this example. The adhesive surface of the adhesive sheet was protected by a release liner.

[0238] <Examples 2 to 5 and Comparative Examples 1 to 4>

[0239] The amount of cross-linking agent, the type and amount of thermal polymerization initiator were changed as shown in Tables 1 to 2. In addition, the adhesive composition involved in each example was prepared by the same method as in Example 1, and the single-sided adhesive sheet with a substrate involved in each example was prepared using the obtained adhesive composition in the same manner as in Example 1. In Table 1, AIBN represents 2,2′-azobisisobutyronitrile (10-hour half-life temperature: 65° C.), VAm-110 represents an azo polymerization initiator manufactured by FUJIFILM Wako Pure Chemical Corporation (product name “VAm-110”, 2,2′-azobis(N-butyl-2-methylpropionamide), 10-hour half-life temperature: 110° C.), and VR-110 represents an azo polymerization initiator manufactured by FUJIFILM Wako Pure Chemical Corporation (product name “VR-110”, 2,2′-azobis(2,4,4-trimethylpentane), 10-hour half-life temperature: 110° C.).

[0240] <Example 6>

[0241] A solution containing acrylic polymer B was obtained by the same method as for preparing acrylic polymer A, except that the monomer components were changed to 25 parts of 2-ethylhexyl acrylate (2EHA), 65 parts of methyl acrylate (MA), and 10 parts of AA. A solvent-based PSA composition was prepared in the same manner as in Example 4, except that the solution of acrylic polymer B was used instead of the solution of acrylic polymer A. The resulting PSA composition was used to produce the single-sided PSA sheet with a substrate according to this example.

[0242] <Example 7>

[0243] A reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer, and a stirrer was charged with 100 parts of MEA, 25 parts of acryloylmorpholine (ACMO), 22 parts of hydroxyethyl acrylate (HEA), and 65 parts of toluene as a polymerization solvent. 0.2 parts of benzoyl peroxide was added as a thermal polymerization initiator, and a polymerization reaction (solution polymerization) was carried out at 61°C under a nitrogen atmosphere for 6 hours to obtain a solution containing acrylic polymer C. 24 parts of methacryloyloxyethyl isocyanate (MOI) was added to this solution of acrylic polymer C, and an addition reaction was carried out at 50°C in an air stream for 48 hours to obtain a solution of acrylic polymer C having a methacryloyl group at the end of the side chain.

[0244] To the solution of the acrylic polymer C, 50 parts of DPHA as a multifunctional monomer, 0.5 parts of the isocyanate crosslinking agent, and 0.5 parts of the benzoyl peroxide as a thermal polymerization initiator were added relative to 100 parts of the acrylic polymer C, and the mixture was uniformly mixed to prepare the solvent-based adhesive composition involved in this example.

[0245] Using the obtained PSA composition, the same procedure as in Example 1 was carried out to produce a substrate-less double-sided PSA sheet according to this example.

[0246] The summary and evaluation results of each example are shown in Tables 1 and 2.

[0247] [Table 1]

[0248] Table 1

[0249]

[0250] [Table 2]

[0251] Table 2

[0252]

[0253] As shown in Tables 1 and 2, the peel strength reduction rate S of the adhesive sheets according to Examples 1 to 7 after heating at 150° C. for 5 minutes was 150-5 And the peeling force reduction rate S after heating at 180℃ for 120 minutes 180-120 More specifically, the peeling force reduction rate S 150-5 、S 180 - 120 The peeling force reduction rate after heating was 50% or more in the entire range of heating temperature from 120°C to 180°C. On the other hand, in Comparative Examples 1 to 4, the peeling force reduction rate S after heating at 180°C for 120 minutes was 98% or more. 180-120 More than 50%, but after heating at 150 ° C for 5 minutes, the peeling force increases and the peeling force reduction rate S 150-5 The result of the peeling force increasing was also confirmed when the peeling force was heated to 180°C (see the peeling force reduction rate S 180-5 ).

[0254] While the specific examples of the present invention have been described in detail above, these are merely examples and do not limit the claims. The technology described in the claims includes various modifications and variations of the specific examples described above.

[0255] Description of Reference Numerals

[0256] 1 Adhesive sheet

[0257] 1A bonding surface

[0258] 1B Back

[0259] 10 base material layer

[0260] 10A side surface

[0261] 10B The other side

[0262] 20 Adhesive layer

[0263] 20A bonding surface

[0264] 30 Release liner

[0265] 50 Adhesive sheet with release liner

Claims

1. An adhesive sheet having an adhesive layer, The adhesive layer comprises a polymer, a multifunctional monomer and a thermal polymerization initiator, Peel force reduction rate after heating S 150-5 And the peeling force reduction rate after heating S 180-120 All of them are above 50%, among which, The peeling force reduction rate after heating S 150-5 Calculated by the following formula: S 150-5 [%]=(1-(N 150-5 / N0))×100 In the above formula, N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 150-5 The peeling force (N) after heating at 150°C for 5 minutes was measured at 23°C and 50% RH. 150-5 [N / 20mm]; The peeling force reduction rate after heating S 180-120 Calculated by the following formula: S 180-120 [%]=(1-(N 180-120 / N0))×100 In the above formula, N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 180-120 The peeling force (N) after heating at 180°C for 120 minutes on a glass plate was measured at 23°C and 50% RH. 180-120 [N / 20mm].

2. The adhesive sheet according to claim 1, wherein The peeling force N0 on the glass plate is greater than or equal to 2.0 N / 20 mm.

3. The adhesive sheet according to claim 1 or 2, wherein The thermal polymerization initiator includes a peroxide-based polymerization initiator.

4. The adhesive sheet according to claim 1 or 2, wherein The content of the cross-linking agent in the adhesive layer is 0.9 parts by weight or less based on 100 parts by weight of the polymer.

5. The adhesive sheet according to claim 1 or 2, wherein Peel force reduction rate after heating S 130-5 More than 50%, of which The peeling force reduction rate after heating S 130-5 Calculated by the following formula: S 130-5 [%]=(1-(N 130-5 / N0))×100 In the above formula, N0 is the peeling force N0 [N / 20mm] on the glass plate measured at 23°C and 50% RH, N 130-5 The peeling force (N) after heating at 130°C for 5 minutes on a glass plate was measured at 23°C and 50% RH. 130-5 [N / 20mm].

Images