Adhesive composition, adhesive sheet, optical member, and display device

Abstract

To provide an adhesive composition by which an adhesive layer having excellent high-temperature durability and reworkability can be formed.SOLUTION: An adhesive composition contains: (meth)acrylic copolymer (A) which contains a monomer unit having a carboxyl group by 0.5 to 3.0 mass% for the entire structural units, and has Mw by 500,000 to 1,200,000; a polyisocyanate-based compound (B); a silane compound (C) having a mercapto group and an alkoxysilyl group; and a silane compound (D) which has an amino group and does not have an alkoxysilyl group, where the content of the compound (B) is 0.1 to 0.6 pts.mass for the copolymer (A) 100 pts.mass, and in the case where the number of moles of a mercapto group in the compound (C) is Pmmol, the number of moles of an amino group in the compound (D) is Qmmol, and the number of moles of a carboxyl group in the copolymer (A) is Rmmol, a functional group ratio obtained by formula (X) is 2.5×10-4 or more and less than 3.5×10-3. Functional group ratio=P×(Q / R)...(X)SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an adhesive composition, an adhesive sheet, an optical member, and a display device.

Background Art

[0002] A liquid crystal display device generally includes a liquid crystal cell in which a liquid crystal layer is sandwiched between two support substrates, and optical films such as a polarizing plate, a retardation film, and a brightness enhancement film. When manufacturing a liquid crystal display device by laminating the liquid crystal cell and the optical films, and the optical films with each other, these members are bonded via an adhesive layer formed by an adhesive composition. In liquid crystal display devices, (meth)acrylic-based adhesive compositions are widely used from the viewpoint of ensuring visibility.

[0003] For example, Patent Document 1 discloses an acrylic copolymer (A) having a weight average molecular weight of 400,000 or more and less than 900,000 containing 1% by weight or more and 4% by weight or less of a carboxyl group-containing monomer as a copolymer component, and a carboxyl group-containing monomer of 0.1% by weight or more and 4% by weight or less and a hydroxyl group-containing monomer of 0.05% by weight or more and 5% by weight or less as copolymer components. An acrylic copolymer (B) having a weight average molecular weight of 400,000 or more and less than 900,000, and an isocyanate compound (C) added in an amount of 5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of a mixture of the acrylic copolymer (A) and the acrylic copolymer (B). An adhesive composition is disclosed. Further, Patent Document 2 discloses a monomer component containing 10 to 30% by mass of an alkyl (meth)acrylate (a1) having a glass transition temperature of the homopolymer of 0°C or higher, and 0.1 to 5% by mass of a crosslinkable functional group-containing monomer (a2) containing a hydroxyl group-containing monomer and a carboxyl group-containing monomer. The monomer component is copolymerized to obtain a (meth)acrylic copolymer (A) having a weight average molecular weight of 600,000 or less measured by gel permeation chromatography and a glass transition temperature of -80 to 0°C, and an isocyanate-based crosslinking agent (B). The crosslinking agent (B) is contained in an amount of 10 to 40 parts by mass with respect to 100 parts by mass of the copolymer (A). A pressure-sensitive adhesive composition for a polarizing plate used for forming an adhesive layer in direct contact with a polarizer is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Optical films such as polarizing plates are usually composed of a plurality of members with different shrinkage rates, so dimensional changes are likely to occur due to changes in temperature and / or humidity. For this reason, when an adherend with an optical film bonded via an adhesive layer is placed in a high-temperature environment (for example, a high-temperature and low-humidity environment), the optical film shrinks, and problems such as wrinkles occurring in the adhesive layer and / or the optical film, and the adhesive layer peeling off from the adherend may occur. In addition, when an adherend with an optical film bonded via an adhesive layer is placed in a high-temperature environment, volatile components such as moisture remaining in the optical film volatilize, and foaming may occur at the interface between the adhesive layer and the optical film and / or the adherend. Therefore, it is required that the adhesive composition used for the optical film can form an adhesive layer (so-called adhesive layer with excellent high-temperature durability) that can suppress the above-mentioned foaming, wrinkles, and peeling that can occur in a high-temperature environment.

[0006] By the way, when bonding a polarizing plate to a liquid crystal cell, generally, a polarizing plate with an adhesive layer is used. When bonding a polarizing plate to a liquid crystal cell, if foreign matter gets caught between the adhesive layer provided on the polarizing plate and the liquid crystal cell, or if misalignment occurs due to an error in the bonding position, the polarizing plate with the adhesive layer is peeled off from the liquid crystal cell and re-bonded. Since the liquid crystal cell after peeling is reused, the adhesive layer is required to have a property (so-called reworkability) that can be easily peeled off without damaging the liquid crystal cell or leaving glue residue on the bonding surface with the liquid crystal cell when peeling from the liquid crystal cell. In addition, the above-mentioned peeling operation is not always performed immediately after bonding, and may be performed after a long period has elapsed since bonding. Therefore, the adhesive layer is required to have excellent reworkability that can be easily peeled off without problems even after a long period has elapsed since the bonding of the polarizing plate to the liquid crystal cell. In recent years, with the increase in the size of optical displays, the area of optical films such as polarizing plates has become larger, so it has become more difficult to peel the optical film from the display, and there is a tendency for the adhesive layer to be required to have more excellent reworkability than before.

[0007] In order to improve the reworkability of the pressure-sensitive adhesive layer, it is necessary to reduce the wettability of the interface between the pressure-sensitive adhesive layer and the adherend (hereinafter also referred to as the "interface of the pressure-sensitive adhesive layer"). However, reducing the wettability of the interface of the pressure-sensitive adhesive layer has the trade-off effect of making the pressure-sensitive adhesive layer less durable against stress caused by the contraction of the optical film in a high-temperature environment, which makes it more likely to cause problems such as peeling of the pressure-sensitive adhesive layer from the adherend. In recent years, with the background of increasing concern about the environment, there is a demand for a reduction in the amount of organic solvent used. When the content of the organic solvent in the adhesive composition is reduced, the viscosity of the adhesive composition increases, and the coating property is impaired. In order to reduce the content of the organic solvent in the adhesive composition without increasing the viscosity of the adhesive composition, it is considered to reduce the weight average molecular weight of the base resin used in the adhesive composition. When the weight average molecular weight of the base resin is low, there is no need to use a large amount of organic solvent to adjust the viscosity of the adhesive composition. However, when the weight average molecular weight of the base resin is reduced, the cohesive force of the adhesive layer formed may be insufficient, and the high temperature durability may be reduced.

[0008] As described above, in a pressure-sensitive adhesive composition using a base resin with a low weight-average molecular weight in order to reduce the amount of organic solvent used, it has traditionally been difficult to form a pressure-sensitive adhesive layer that combines high levels of high-temperature durability and reworkability.

[0009] In contrast, the pressure-sensitive adhesive compositions described in Patent Document 1 (JP 2011-178903 A) and Patent Document 2 (WO 2016 / 072197 A) both use a base resin with a low weight-average molecular weight, but use a large amount of crosslinking agent to achieve excellent high-temperature durability, which is thought to result in high adhesive strength of the pressure-sensitive adhesive layer and poor reworkability.

[0010] The present disclosure has been made in consideration of the above-mentioned circumstances. An object of one embodiment of the present disclosure is to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having excellent high-temperature durability and reworkability. Another problem to be solved by other embodiments of the present disclosure is to provide a pressure-sensitive adhesive sheet, an optical member, and a display device each including a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition described above.

Means for Solving the Problem

[0011] Specific means for solving the problem include the following aspects. <1> A (meth)acrylic copolymer (A) containing a structural unit derived from a monomer having a carboxy group in a proportion of 0.5% by mass or more and 3.0% by mass or less based on all the structural units and having a weight average molecular weight in the range of 500,000 or more and 1,200,000 or less, a polyisocyanate compound (B), a silane compound (C) having a mercapto group and an alkoxysilyl group, a silane compound (D) having an amino group and not having an alkoxysilyl group, and containing, wherein the content of the polyisocyanate compound (B) is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the (meth)acrylic copolymer (A), when the number of moles of the mercapto group in the silane compound (C) is P mmol, the number of moles of the amino group in the silane compound (D) is Q mmol, and the number of moles of the carboxy group in the (meth)acrylic copolymer (A) is R mmol, the functional group ratio obtained by the following formula (X) is 2.5×10 -4 or more and less than 3.5×10 -3 A pressure-sensitive adhesive composition in the range. Functional group ratio = P×(Q / R) ··· (X) <2> The pressure-sensitive adhesive composition according to <1>, wherein the silane compound (C) has a siloxane bond. <3> The pressure-sensitive adhesive composition according to <1> or <2>, wherein the content of the silane compound (C) is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the (meth)acrylic copolymer (A). <4> The pressure-sensitive adhesive composition according to any one of <1> to <3>, wherein the (meth)acrylic copolymer (A) further contains a structural unit derived from a monomer having a hydroxyl group. <5> The pressure-sensitive adhesive composition according to any one of <1> to <4>, further comprising an alicyclic epoxy compound having two or more functional groups. <6> A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition according to any one of <1> to <5>. <7> An optical film, and A pressure-sensitive adhesive layer provided on at least one side of the optical film and formed of the pressure-sensitive adhesive composition according to any one of <1> to <5>, and A pressure-sensitive adhesive sheet comprising the same. <8> The pressure-sensitive adhesive sheet according to <7>, wherein the optical film is a polarizing plate. <9> A glass substrate, and A pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition according to any one of <1> to <5>, and An optical film, and An optical member comprising the same in this order. <10> A display device comprising the optical member according to <9>.

Advantages of the Invention

[0012] According to one embodiment of the present disclosure, there is provided a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in high-temperature durability and reworkability. According to another embodiment of the present disclosure, there are provided a pressure-sensitive adhesive sheet, an optical member, and a display device each including a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition.

Modes for Carrying Out the Invention

[0013] Hereinafter, the pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, optical member, and display device of the present disclosure will be described in detail. The description of the requirements described below may be based on typical embodiments of the present disclosure, but the present disclosure is not limited to such embodiments, and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0014] In the present disclosure, a numerical range indicated using "~" means a range including the numerical values described before and after "~" as a lower limit value and an upper limit value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

[0015] In the present disclosure, the combination of two or more preferred embodiments is a more preferred embodiment.

[0016] In the present disclosure, the amount of each component in the pressure-sensitive adhesive composition means the total amount of the plurality of substances present in the pressure-sensitive adhesive composition, unless otherwise specified, when there are a plurality of substances corresponding to each component in the pressure-sensitive adhesive composition.

[0017] In the present disclosure, "solid content" means components other than the solvent contained in the composition, unless otherwise specified. In the present disclosure, "solvent" means water and / or an organic solvent.

[0018] In the present disclosure, "(meth)acrylic monomer" means a monomer having a (meth)acryloyl group. In the present disclosure, "(meth)acrylic copolymer" means a copolymer containing structural units derived from (meth)acrylic monomers and having a proportion of structural units derived from (meth)acrylic monomers of 50% by mass or more.

[0019] In the present disclosure, "(meth)acrylic" is a term encompassing both "acrylic" and "methacrylic", "(meth)acrylate" is a term encompassing both "acrylate" and "methacrylate", and "(meth)acryloyl" is a term encompassing both "acryloyl" and "methacryloyl".

[0020] In the present disclosure, "n-" means normal, "i-" means iso, "s-" means secondary, and "t-" means tertiary.

[0021] In the present disclosure, “mass %” and “weight %” are synonymous, and “parts by mass” and “parts by weight” are synonymous.

[0022] In the present disclosure, “monomer” and “monomeric unit” are synonymous, and “polymer,” “polymerized product,” and “copolymer” are synonymous.

[0023] In the present disclosure, the term “step” includes not only an independent step but also a step that cannot be clearly distinguished from other steps, provided that the intended purpose of the step is achieved.

[0024] [Adhesive Composition] The adhesive composition of the present disclosure contains a structural unit derived from a monomer having a carboxy group in a proportion of 0.5% by mass or more and 3.0% by mass or less based on all the structural units, and a (meth)acrylic copolymer (A) having a weight average molecular weight in the range of 500,000 or more and 1,200,000 or less, a polyisocyanate compound (B), a silane compound (C) having a mercapto group and an alkoxysilyl group, and a silane compound (D) having an amino group and not having an alkoxysilyl group. The content of the polyisocyanate compound (B) is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the (meth)acrylic copolymer (A). When the number of moles of the mercapto group in the silane compound (C) is P mmol, the number of moles of the amino group in the silane compound (D) is Q mmol, and the number of moles of the carboxy group in the (meth)acrylic copolymer (A) is R mmol, the functional group ratio obtained by the following formula (X) is in the range of 2.5×10 -4 or more and 3.5×10 -3 less than. Functional group ratio = P × (Q / R) ··· (X)

[0025] With the increasing interest in the environment in recent years, even in the field of adhesives, there is a demand to reduce the amount of organic solvents used. However, when the content of the organic solvent in the adhesive composition decreases, the viscosity of the adhesive composition increases, and the coatability is impaired. In order to reduce the content of the organic solvent in the adhesive composition without increasing the viscosity of the adhesive composition, it is conceivable to lower the weight average molecular weight of the base resin used in the adhesive composition. However, when the weight average molecular weight of the base resin is lowered, the cohesive force of the formed adhesive layer may be insufficient, and the high-temperature durability may decrease. On the other hand, the adhesive composition of the present disclosure can form an adhesive layer excellent in high-temperature durability while containing a (meth)acrylic copolymer having a relatively low weight average molecular weight as a base resin. Further, the adhesive layer formed by the adhesive composition of the present disclosure is also excellent in reworkability, which has been conventionally difficult to achieve in combination with high-temperature durability. Although the reason why the adhesive composition of the present disclosure can exhibit such effects is not clear, the present inventors presume as follows. However, the following presumption does not limit the adhesive composition of the present disclosure and is described as an example.

[0026] The (meth)acrylic copolymer (A) contained in the adhesive composition of the present disclosure contains a structural unit derived from a monomer having a carboxy group in a specific range ratio. The carboxy group of the (meth)acrylic copolymer (A) can contribute to the crosslinking reaction between the polyisocyanate compound (B) contained in the adhesive composition of the present disclosure in a specific range ratio and the (meth)acrylic copolymer (A), thereby enhancing the cohesive force of the adhesive layer. Further, the carboxy group of the (meth)acrylic copolymer (A) can enhance the interaction at the interface between the adhesive layer and the adherend. When the cohesive force of the adhesive layer increases and the interaction at the interface between the adhesive layer and the adherend increases, the high-temperature durability of the adhesive layer improves. However, when the interaction at the interface between the adhesive layer and the adherend is too strong, the reworkability decreases.

[0027] As a method for improving reworkability, a method of using a silane compound can be mentioned. Generally, a silane compound can exhibit an effect of improving reworkability by moderately reducing the adhesion between the adhesive layer and the adherend (for example, glass). However, if the silane compound is excessively unevenly distributed at the interface between the adhesive layer and the adherend, the adhesion between the adhesive layer and the adherend will be excessively reduced, and the adhesive layer will not be able to withstand the stress generated by the shrinkage of the polarizing plate in a high-temperature environment, and problems such as peeling may occur. In the process of intensive studies, the inventors of the present invention have found a method of using two types of silane compounds having specific functional groups that interact with the carboxyl groups of the (meth)acrylic copolymer (A) as a method for preventing the silane compound from being excessively unevenly distributed at the interface between the adhesive layer and the adherend.

[0028] The adhesive composition of the present disclosure contains a silane compound (C) having a mercapto group and an alkoxysilyl group, and a silane compound (D) having an amino group and not having an alkoxysilyl group. The mercapto group of the silane compound (C) is considered to be moderately unevenly distributed at the interface between the adhesive layer and the adherend by interacting with the carboxyl group of the (meth)acrylic copolymer (A). In addition, the alkoxysilyl group of the silane compound (C) is considered to improve the adhesion between the adhesive layer and the adherend by reacting with the silanol group on the glass surface in a high-temperature environment, and to suppress the decrease in high-temperature durability due to the uneven distribution of the silane compound (C). On the other hand, since the amino group of the silane compound (D) is a basic functional group, it is considered to interact relatively strongly with the carboxyl group, which is an acidic functional group of the (meth)acrylic copolymer (A). That is, the amino group of the silane compound (D) has a stronger interaction with the carboxyl group of the (meth)acrylic copolymer (A) than the mercapto group of the silane compound (C). The silane compound (D) moderately reduces the adhesion between the adhesive layer and the adherend and improves the reworkability of the adhesive layer, while not being excessively unevenly distributed at the interface between the adhesive layer and the adherend, so it is considered not to interfere with the effect of the silane compound (C) in suppressing the decrease in high-temperature durability. The pressure-sensitive adhesive composition of the present disclosure is designed by focusing on the interaction of functional groups as described above. In the pressure-sensitive adhesive composition of the present disclosure, as constituent components, a (meth)acrylic copolymer (A) containing a structural unit derived from a monomer having a carboxy group in a specific range ratio, a polyisocyanate compound (B) in a specific range ratio with respect to the (meth)acrylic copolymer (A), a silane compound (C) having a mercapto group and an alkoxysilyl group, and a silane compound (D) having an amino group and not having an alkoxysilyl group are selected, and the functional group ratio of the mercapto group in the silane compound (C), the amino group in the silane compound (D), and the carboxy group in the (meth)acrylic copolymer (A) is adjusted. Thereby, the formed pressure-sensitive adhesive layer has an appropriately increased cohesive force, and the balance of the interaction between the carboxy group of the (meth)acrylic copolymer (A), the mercapto group and the alkoxysilyl group of the silane compound (C), and the amino group of the silane compound (D) becomes good, so that the adhesion to the adherend becomes appropriate. Therefore, although it contains a (meth)acrylic copolymer (A) having a relatively low weight average molecular weight, it is presumed to be excellent in high-temperature durability and reworkability.

[0029] In the present disclosure, the "(meth)acrylic copolymer (A) containing a structural unit derived from a monomer having a carboxy group in a ratio of 0.5% by mass or more and 3.0% by mass or less with respect to all structural units and having a weight average molecular weight in the range of 500,000 or more and 1,200,000 or less)" is also referred to as "specific (meth)acrylic copolymer (A)". Further, in the present disclosure, the "silane compound (C) having a mercapto group and an alkoxysilyl group" is also referred to as "specific silane compound (C)". Further, in the present disclosure, the "silane compound (D) having an amino group and not having an alkoxysilyl group" is also referred to as "specific silane compound (D)". Further, in the present disclosure, the "functional group ratio obtained by formula (X)" is also referred to as "functional group ratio (X)".

[0030] 〔Specific (meth)acrylic copolymer (A)〕 The pressure-sensitive adhesive composition of the present disclosure contains a structural unit derived from a monomer having a carboxy group in a proportion of 0.5% by mass or more and 3.0% by mass or less based on all the structural units, and contains a (meth)acrylic copolymer (A) having a weight average molecular weight in the range of 500,000 or more and 1,200,000 or less (i.e., a specific (meth)acrylic copolymer (A)). The pressure-sensitive adhesive composition of the present disclosure may contain only one kind of the specific (meth)acrylic copolymer (A), or may contain two or more kinds thereof.

[0031] <Structural unit derived from a monomer having a carboxy group> The specific (meth)acrylic copolymer (A) contains a structural unit derived from a monomer having a carboxy group in a proportion of 0.5% by mass or more and 3.0% by mass or less based on all the structural units. In the present disclosure, the "structural unit derived from a monomer having a carboxy group" means a structural unit formed by addition polymerization of a monomer having a carboxy group.

[0032] The type of the monomer having a carboxy group is not particularly limited. Examples of the monomer having a carboxy group include monomers having at least one carboxy group and an ethylenically unsaturated group in one molecule. The ethylenically unsaturated group is not particularly limited, and examples thereof include a vinyl group, an allyl group, a vinylphenyl group, a (meth)acrylamide group, and a (meth)acryloyl group. As the ethylenically unsaturated group, a (meth)acryloyl group is preferable.

[0033] Specific examples of the monomer having a carboxy group include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, ω-carboxy-polycaprolactone mono(meth)acrylate [for example, ω-carboxy-polycaprolactone (n≈2) monoacrylate], and succinic acid derivatives (for example, 2-acryloyloxyethyl-succinic acid). As the monomer having a carboxy group, (meth)acrylic acid is preferable, and acrylic acid is more preferable.

[0034] The specific (meth)acrylic copolymer (A) may contain only one type of structural unit derived from a monomer having a carboxy group, or may contain two or more types.

[0035] The content of the structural unit derived from the monomer having a carboxy group in the specific (meth)acrylic copolymer (A) is 0.5% by mass or more and 3.0% by mass or less based on all the structural units of the specific (meth)acrylic copolymer (A). When the content of the structural unit derived from the monomer having a carboxy group in the specific (meth)acrylic copolymer (A) is 0.5% by mass or more based on all the structural units of the specific (meth)acrylic copolymer (A), the formed pressure-sensitive adhesive layer tends to exhibit excellent high-temperature durability. This is presumably because the cohesive force of the pressure-sensitive adhesive layer is sufficiently increased, and the interaction at the interface between the pressure-sensitive adhesive layer and the adherend (for example, glass) is sufficiently enhanced. The content of the structural unit derived from the monomer having a carboxy group in the specific (meth)acrylic copolymer (A) is preferably 1.0% by mass or more, more preferably 1.5% by mass or more based on all the structural units of the specific (meth)acrylic copolymer (A). When the content of the structural unit derived from the monomer having a carboxy group in the specific (meth)acrylic copolymer (A) is 3.0% by mass or less based on all the structural units of the specific (meth)acrylic copolymer (A), the formed pressure-sensitive adhesive layer tends to exhibit excellent reworkability. This is presumably because the interaction at the interface between the pressure-sensitive adhesive layer and the adherend does not become excessively strong. The content of the structural unit derived from the monomer having a carboxy group in the specific (meth)acrylic copolymer (A) is preferably 2.5% by mass or less, more preferably 2.0% by mass or less based on all the structural units of the specific (meth)acrylic copolymer (A). In one aspect, the content rate of the structural unit derived from the monomer having a carboxy group in the specific (meth)acrylic copolymer (A) may be in the range of 0.5% by mass or more and 2.5% by mass or less, may be in the range of 0.5% by mass or more and 2.0% by mass or less, may be in the range of 1.0% by mass or more and 3.0% by mass or less, may be in the range of 1.0% by mass or more and 2.5% by mass or less, may be in the range of 1.0% by mass or more and 2.0% by mass or less, or may be in the range of 1.5% by mass or more and 2.5% by mass or less, based on all the structural units of the specific (meth)acrylic copolymer (A).

[0036] <Structural unit derived from a monomer having a hydroxyl group> The specific (meth)acrylic copolymer (A) preferably further contains a structural unit derived from a monomer having a hydroxyl group. When the specific (meth)acrylic copolymer (A) further contains a structural unit derived from a monomer having a hydroxyl group, the high-temperature durability of the formed pressure-sensitive adhesive layer tends to be improved. In the present disclosure, the "structural unit derived from a monomer having a hydroxyl group" means a structural unit formed by the addition polymerization of a monomer having a hydroxyl group.

[0037] The type of the monomer having a hydroxyl group is not particularly limited. Examples of the monomer having a hydroxyl group include monomers having at least one hydroxyl group and an ethylenically unsaturated group in one molecule. The ethylenically unsaturated group is not particularly limited, and examples thereof include a vinyl group, an allyl group, a vinylphenyl group, a (meth)acrylamide group, and a (meth)acryloyl group. As the ethylenically unsaturated group, a (meth)acryloyl group is preferable.

[0038] Specific examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, 3-methyl-3-hydroxybutyl (meth)acrylate, 1,1-dimethyl-3-hydroxybutyl (meth)acrylate, 1,3-dimethyl-3-hydroxybutyl (meth)acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth)acrylate, 2-ethyl-3-hydroxyhexyl (meth)acrylate, N-hydroxyethyl (meth)acrylamide, glycerin mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and poly(ethylene glycol-propylene glycol) mono(meth)acrylate. As the monomer having a hydroxyl group, hydroxyalkyl (meth)acrylate is preferable, hydroxyalkyl (meth)acrylate having a hydroxyalkyl group having 2 to 4 carbon atoms is more preferable, 2-hydroxyethyl acrylate and / or 4-hydroxybutyl acrylate is still more preferable, and 2-hydroxyethyl acrylate is particularly preferable.

[0039] When the specific (meth)acrylic copolymer (A) contains a structural unit derived from a monomer having a hydroxyl group, it may contain only one kind or two or more kinds of structural units derived from the monomer having a hydroxyl group.

[0040] When the specific (meth)acrylic copolymer (A) contains a structural unit derived from a monomer having a hydroxyl group, the content of the structural unit derived from the monomer having a hydroxyl group is not particularly limited. The content rate of the structural unit derived from the monomer having a hydroxyl group in the specific (meth)acrylic copolymer (A) is preferably, for example, 0.5 mass% or more, more preferably 1.0 mass% or more, still more preferably 1.5 mass% or more, and particularly preferably 2.0 mass% or more with respect to all the structural units of the specific (meth)acrylic copolymer (A). The upper limit of the content rate of the structural unit derived from the monomer having a hydroxyl group in the specific (meth)acrylic copolymer (A) may be, for example, 4.0 mass% or less with respect to all the structural units of the specific (meth)acrylic copolymer (A). In one aspect, the content rate of the structural unit derived from the monomer having a hydroxyl group in the specific (meth)acrylic copolymer (A) may be in the range of 0.5 mass% or more and 4.0 mass% or less, may be in the range of 1.0 mass% or more and 4.0 mass% or less, may be in the range of 1.5 mass% or more and 4.0 mass% or less, or may be in the range of 2.0 mass% or more and 4.0 mass% or less with respect to all the structural units of the specific (meth)acrylic copolymer (A).

[0041] <Structural unit derived from (meth)acrylic acid alkyl ester monomer> The specific (meth)acrylic copolymer (A) preferably contains a structural unit derived from a (meth)acrylic acid alkyl ester monomer. In the present disclosure, the "structural unit derived from a (meth)acrylic acid alkyl ester monomer" means a structural unit formed by the addition polymerization of a (meth)acrylic acid alkyl ester monomer. In addition, the “alkyl (meth)acrylate monomer” in the present disclosure does not include monomers corresponding to monomers having a carboxy group and monomers corresponding to monomers having a hydroxy group. That is, the “alkyl (meth)acrylate monomer” in the present disclosure refers to an alkyl (meth)acrylate monomer having no hydroxy group and / or carboxy group. In the present disclosure, for example, an alkyl (meth)acrylate monomer having a carboxy group is classified as the monomer having the carboxy group described above, and an alkyl (meth)acrylate monomer having a hydroxy group is classified as the monomer having the hydroxy group described above.

[0042] The type of the alkyl (meth)acrylate monomer is not particularly limited. The alkyl (meth)acrylate monomer may be an alkyl acrylate monomer or an alkyl methacrylate monomer. The alkyl group of the alkyl (meth)acrylate monomer may be unsubstituted or may have a substituent (excluding a carboxy group and a hydroxy group), but is preferably unsubstituted. The alkyl group of the alkyl (meth)acrylate monomer may be linear, branched, or cyclic. The number of carbon atoms of the alkyl group of the alkyl (meth)acrylate monomer is preferably, for example, 1 to 18, more preferably 1 to 12, still more preferably 1 to 8, and particularly preferably 1 to 4.

[0043] Specific examples of the (meth)acrylic acid alkyl ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, i-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, i-nonyl (meth)acrylate, n-decyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. As the (meth)acrylic acid alkyl ester monomer, at least one selected from the group consisting of n-butyl acrylate, methyl acrylate, and methyl methacrylate is preferable.

[0044] When the specific (meth)acrylic copolymer (A) contains a structural unit derived from a (meth)acrylic acid alkyl ester monomer, it may contain only one kind of the structural unit derived from the (meth)acrylic acid alkyl ester monomer, or may contain two or more kinds.

[0045] When the specific (meth)acrylic copolymer (A) contains a structural unit derived from a (meth)acrylic acid alkyl ester monomer, the content of the structural unit derived from the (meth)acrylic acid alkyl ester monomer is not particularly limited. For example, it is preferably 50% by mass or more, more preferably in the range of 50% by mass or more and 99.5% by mass or less, still more preferably in the range of 60% by mass or more and 99.0% by mass or less, and particularly preferably in the range of 70% by mass or more and 98.5% by mass or less with respect to all the structural units of the specific (meth)acrylic copolymer (A). Here, the content ratio of the structural unit derived from the (meth)acrylic acid alkyl ester monomer in the specific (meth)acrylic copolymer (A) being 50% by mass or more based on all the structural units of the specific (meth)acrylic copolymer (A) means that the structural unit derived from the (meth)acrylic acid alkyl ester monomer is included as the main component of the structural units of the specific (meth)acrylic copolymer (A).

[0046] <Structural units derived from other monomers> The specific (meth)acrylic copolymer (A) may contain structural units derived from a monomer having a carboxy group, a monomer having a hydroxy group, and a monomer not corresponding to any of the (meth)acrylic acid alkyl ester monomers (so-called other monomers). In the present disclosure, "structural units derived from other monomers" means structural units formed by the addition polymerization of other monomers.

[0047] Examples of the structural units derived from other monomers include structural units derived from (meth)acrylates having an aromatic ring typified by benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; structural units derived from alkoxyalkyl (meth)acrylates typified by methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; structural units derived from aromatic monovinyls typified by styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and vinyltoluene; structural units derived from vinyl cyanides typified by acrylonitrile and methacrylonitrile; structural units derived from vinyl esters typified by vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate; and the like.

[0048] The specific (meth)acrylic copolymer (A) preferably contains, as a structural unit derived from other monomers, a structural unit derived from a (meth)acrylate having an aromatic ring, more preferably contains a structural unit derived from phenoxyethyl (meth)acrylate, and still more preferably contains a structural unit derived from phenoxyethyl acrylate, from the viewpoint of suppressing white spots. Here, "white spots" refers to, for example, a phenomenon in which light leakage occurs in a liquid crystal display device and it becomes white.

[0049] When the specific (meth)acrylic copolymer (A) contains a structural unit derived from other monomers, it may contain only one kind of the structural unit derived from other monomers, or may contain two or more kinds.

[0050] When the specific (meth)acrylic copolymer (A) contains a structural unit derived from other monomers, the content of the structural unit derived from other monomers can be appropriately set within a range that does not impair the effects of the pressure-sensitive adhesive composition of the present disclosure.

[0051] <<Weight-average molecular weight of the specific (meth)acrylic copolymer (A)>> The weight-average molecular weight (also referred to as "Mw") of the specific (meth)acrylic copolymer (A) is in the range of 500,000 or more and 1,200,000 or less, preferably in the range of 600,000 or more and 1,200,000 or less, more preferably in the range of 700,000 or more and 1,200,000 or less, and still more preferably in the range of 800,000 or more and 1,200,000 or less. When the weight-average molecular weight of the specific (meth)acrylic copolymer (A) is 500,000 or more, the formed pressure-sensitive adhesive layer tends to exhibit excellent high-temperature durability. This is presumably because the cohesive force of the pressure-sensitive adhesive layer is sufficiently increased. When the weight-average molecular weight of the specific (meth)acrylic copolymer (A) is 1,200,000 or less, the amount of the organic solvent for dilution used to adjust the pressure-sensitive adhesive composition to the viscosity required for coating can be sufficiently reduced. This is presumably because the viscosity of the solution of the specific (meth)acrylic copolymer (A) blended when preparing the pressure-sensitive adhesive composition becomes low.

[0052] The weight average molecular weight of the specific (meth)acrylic copolymer (A) is a value measured by the following method. Specifically, it is measured according to the following (1) to (3). (1) A solution of the specific (meth)acrylic copolymer (A) is applied to a release paper and dried at 100 °C for 1 minute to obtain a film-like specific (meth)acrylic copolymer (A). (2) Using the film-like specific (meth)acrylic copolymer (A) obtained in (1) above and tetrahydrofuran, a sample solution with a solid content concentration of 0.2 mass% is obtained. Here, the "solid content concentration" means the mass ratio of the specific (meth)acrylic copolymer (A) in the sample solution. (3) The weight average molecular weight of the specific (meth)acrylic copolymer (A) is determined as a standard polystyrene equivalent value by gel permeation chromatography (GPC) under the following conditions.

[0053] ~Conditions~ Measuring device: High-speed GPC [Model number: HLC-8420 GPC, manufactured by Tosoh Corporation] Detector: Differential refractometer (RI) [incorporated in HLC-8420, manufactured by Tosoh Corporation] Column: TSKgel GMH XL [manufactured by Tosoh Corporation] Two are used Column temperature: 40 °C Eluent: Tetrahydrofuran Injection volume of the sample solution: 100 μL Flow rate: 0.8 mL / min

[0054] The weight average molecular weight of the specific (meth)acrylic copolymer (A) can be adjusted to a desired value by adjusting the polymerization temperature, polymerization time, amount of organic solvent used, type of polymerization initiator, amount of polymerization initiator used, etc. when polymerizing the monomers.

[0055] <<Content ratio of the specific (meth)acrylic copolymer (A)>> The content rate of the specific (meth)acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present disclosure is not particularly limited. For example, it is preferably 50.0% by mass to 99.8% by mass, more preferably 60.0% by mass to 99.6% by mass, and still more preferably 70.0% by mass to 99.4% by mass with respect to the total solid content in the pressure-sensitive adhesive composition.

[0056] In the present disclosure, the "total solid content in the pressure-sensitive adhesive composition" means the total mass of the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition does not contain a solvent, and means the mass of the residue obtained by removing the solvent from the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition contains a solvent.

[0057] 〔Method for producing the specific (meth)acrylic copolymer (A)〕 The method for producing the specific (meth)acrylic copolymer (A) is not particularly limited. The specific (meth)acrylic copolymer (A) can be produced, for example, by polymerizing the aforementioned monomers by a known polymerization method typified by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. As the polymerization method, the solution polymerization method is preferable in terms of relatively simple treatment steps and the ability to perform the process in a short time when preparing the pressure-sensitive adhesive composition of the present disclosure after production.

[0058] In the solution polymerization method, generally, a predetermined organic solvent, monomer, polymerization initiator, and a chain transfer agent used as necessary are charged into a polymerization tank, and, for example, heated and reacted with stirring for several hours at the reflux temperature of the organic solvent. In this case, at least a part of the organic solvent, monomer, polymerization initiator, and the chain transfer agent used as necessary may be sequentially added. Further, the reaction may be carried out in a nitrogen stream.

[0059] Examples of the organic solvent used during the polymerization reaction include aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, alicyclic hydrocarbon compounds, ester compounds, ketone compounds, glycol ether compounds, and alcohol compounds. Examples of the organic solvents used during the polymerization reaction include, more specifically, aromatic hydrocarbon compounds typified by benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha; aliphatic or alicyclic hydrocarbon compounds typified by n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and turpentine oil; ester compounds typified by methyl acetate, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate; ketone compounds typified by acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, and methylcyclohexanone; glycol ether compounds typified by ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; and alcohol compounds typified by methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t-butyl alcohol.

[0060] In the production of the specific (meth)acrylic copolymer (A), it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction, such as an aromatic hydrocarbon compound, an ester compound, or a ketone compound. In particular, from the viewpoints of the solubility of the specific (meth)acrylic copolymer (A) and the ease of the polymerization reaction, it is preferable to use methyl acetate and / or ethyl acetate.

[0061] During the polymerization reaction, only one type of organic solvent may be used, or two or more types may be used.

[0062] Examples of the polymerization initiator include organic peroxides and azo compounds used in a normal solution polymerization method. Specific examples of the organic peroxide include t-butyl peroxy-2-ethylhexanoate, t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-amylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)butane, and 2,2-bis(4,4-di-t-octylperoxycyclohexyl)butane. Specific examples of the azo compound include 2,2'-azobisisobutyronitrile [AIBN], 2,2'-azobis(2,4-dimethylvaleronitrile) [ABVN], 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), and dimethyl 2,2'-azobis(isobutyrate).

[0063] During the polymerization reaction, only one type of polymerization initiator may be used, or two or more types may be used.

[0064] The amount of the polymerization initiator used is not particularly limited and can be appropriately set, for example, according to the molecular weight of the target specific (meth)acrylic copolymer (A).

[0065] When producing the specific (meth)acrylic copolymer (A), a chain transfer agent may be used as needed. Examples of the chain transfer agent include cyanoacetic acid, C1-C8 alkyl ester compounds of cyanoacetic acid, bromoacetic acid, C1-C8 alkyl ester compounds of bromoacetic acid, α-methylstyrene, anthracene, phenanthrene, fluorene, and aromatic compounds represented by 9-phenylfluorene, aromatic nitro compounds represented by p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, and p-nitrotoluene, benzoquinone derivatives represented by benzoquinone and 2,3,5,6-tetramethyl-p-benzoquinone, borane derivatives represented by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, and halogenated hydrocarbon compounds represented by 3-chloro-1-propene, aldehyde compounds represented by chloral and furfuraldehyde, C1-C18 alkyl mercaptan compounds, aromatic mercaptan compounds represented by thiophenol and toluene mercaptan, mercaptoacetic acid, C1-C10 alkyl ester compounds of mercaptoacetic acid, C1-C12 hydroxyalkyl mercaptan compounds, and terpene compounds represented by pinene and terpinolene.

[0066] When a chain transfer agent is used in the production of the specific (meth)acrylic copolymer (A), the amount of the chain transfer agent used is not particularly limited and can be appropriately set, for example, according to the molecular weight of the target specific (meth)acrylic copolymer (A).

[0067] The polymerization temperature is not particularly limited and can be appropriately set, for example, according to the molecular weight of the target specific (meth)acrylic copolymer (A).

[0068] [Polyisocyanate compound (B)] The pressure-sensitive adhesive composition of the present disclosure contains a polyisocyanate compound (B), and the content of the polyisocyanate compound (B) is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A). In the present disclosure, the polyisocyanate compound (B) functions as a crosslinking agent.

[0069] Examples of the polyisocyanate compound (B) include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, and aromatic polyisocyanate compounds. The "aliphatic polyisocyanate compound" includes, for example, aliphatic polyisocyanate compounds, multimers of aliphatic polyisocyanate compounds, adducts of aliphatic polyisocyanate compounds and polyol compounds [e.g., trimethylolpropane (TMP); the same shall apply hereinafter], and biuret compounds of aliphatic polyisocyanate compounds. Specific examples of the aliphatic polyisocyanate compound include hexamethylene diisocyanate (HMDI), pentamethylene diisocyanate (PDI), tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. The "alicyclic polyisocyanate compound" includes, for example, alicyclic polyisocyanate compounds, multimers of alicyclic polyisocyanate compounds, adducts of alicyclic polyisocyanate compounds and polyol compounds, and biuret compounds of alicyclic polyisocyanate compounds. Specific examples of the alicyclic polyisocyanate compound include isophorone diisocyanate (IPDI), hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate. The "aromatic polyisocyanate compound" includes, for example, aromatic polyisocyanate compounds, multimers of aromatic polyisocyanate compounds, adducts of aromatic polyisocyanate compounds and polyol compounds, and biuret compounds of aromatic polyisocyanate compounds. Specific examples of the aromatic polyisocyanate compound include toluene diisocyanate (TDI), xylylene diisocyanate (XDI), and 4,4'-diphenylmethane diisocyanate.

[0070] As the polyisocyanate compound (B), an aromatic polyisocyanate compound is preferable, and at least one selected from the group consisting of tolylene diisocyanate compounds and xylylene diisocyanate compounds is more preferable. The "tolylene diisocyanate compound" includes, for example, TDI, a multimer of TDI, an adduct of TDI and a polyol compound, and a biuret of TDI. As the tolylene diisocyanate compound, an adduct of TDI and TMP is preferable. The "xylylene diisocyanate compound" includes, for example, XDI, a multimer of XDI, an adduct of XDI and a polyol compound, and a biuret of XDI. As the xylylene diisocyanate compound, an adduct of XDI and TMP is preferable.

[0071] As the polyisocyanate compound (B), commercially available products can be used. Examples of commercially available polyisocyanate compounds (B) include "Coronate (registered trademark) HX", "Coronate (registered trademark) HL-S", "Coronate (registered trademark) L", "Coronate (registered trademark) L-45E", "Coronate (registered trademark) 2031", "Coronate (registered trademark) 2037", "Coronate (registered trademark) 2234", "Coronate (registered trademark) 2785", "Aquaneate (registered trademark) 200", and "Aquaneate (registered trademark) 210" [manufactured by Toray Industries, Inc.]; "Sumidule (registered trademark) N3300", "Desmodule (registered trademark) N3400", and "Sumidule (registered trademark) N75" [manufactured by Sumika Covestro Urethane Co., Ltd.]; "Duranate (registered trademark) D201", "Duranate (registered trademark) E405-70B", "Duranate (registered trademark) E405-80T", "Duranate (registered trademark) AE700-100", "Duranate (registered trademark) 24A-100", "Duranate (registered trademark) TSA-100", and "Duranate (registered trademark) TSE-100" [manufactured by Asahi Kasei Corporation]; and "Takenate (registered trademark) D-110N", "Takenate (registered trademark) D-101E", "Takenate (registered trademark) D-120N", "Takenate (registered trademark) D-140N", "Takenate (registered trademark) M-631N", and "MT-Orester (registered trademark) NP1200" [manufactured by Mitsui Chemicals, Inc.].

[0072] The pressure-sensitive adhesive composition of the present disclosure may contain only one type of polyisocyanate compound (B) or may contain two or more types.

[0073] The content of the polyisocyanate compound (B) in the pressure-sensitive adhesive composition of the present disclosure is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A). When the content of the polyisocyanate compound (B) in the pressure-sensitive adhesive composition of the present disclosure is within the above range with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A), the formed pressure-sensitive adhesive layer tends to exhibit excellent high-temperature durability. This is presumably because the pressure-sensitive adhesive layer is neither too soft nor too hard and has an appropriate hardness. The content of the polyisocyanate compound (B) in the pressure-sensitive adhesive composition of the present disclosure is preferably 0.15 parts by mass or more, more preferably 0.2 parts by mass or more, with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A). Further, the content of the polyisocyanate compound (B) in the pressure-sensitive adhesive composition of the present disclosure is preferably 0.5 parts by mass or less, more preferably 0.3 parts by mass or less, with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A). In one aspect, the content of the polyisocyanate compound (B) in the pressure-sensitive adhesive composition of the present disclosure may be in the range of 0.1 parts by mass or more and 0.5 parts by mass or less, may be in the range of 0.1 parts by mass or more and 0.3 parts by mass or less, may be in the range of 0.15 parts by mass or more and 0.5 parts by mass or less, may be in the range of 0.2 parts by mass or more and 0.5 parts by mass or less, or may be in the range of 0.2 parts by mass or more and 0.3 parts by mass or less, with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A).

[0074] [Epoxy compounds having two or more functional groups] The pressure-sensitive adhesive composition of the present disclosure preferably further contains a compound having two or more epoxy groups in one molecule (so-called epoxy compounds having two or more functional groups). In the present disclosure, the epoxy compound having two or more functional groups functions as a crosslinking agent. When the pressure-sensitive adhesive composition of the present disclosure further contains an epoxy compound having two or more functional groups, the high-temperature durability of the formed pressure-sensitive adhesive layer tends to be improved.

[0075] Examples of the epoxy compound having two or more functional groups include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6 - hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcin diglycidyl ether, 2,2 - dibromoneopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris(glycidyl)isocyanurate, tris(glycidoxyethyl)isocyanurate, 1,3 - bis(N,N - glycidylaminomethyl)cyclohexane, and N,N,N’,N’ - tetraglycidyl - 1,3 - benzenedimethanamine.

[0076] As the epoxy compound having two or more functional groups, for example, from the viewpoint of compatibility with a specific (meth)acrylic copolymer, an alicyclic epoxy compound is preferable. When the compatibility between the specific (meth)acrylic copolymer and the epoxy compound having two or more functional groups is enhanced, the high - temperature durability of the pressure - sensitive adhesive layer formed by the pressure - sensitive adhesive composition of the present disclosure can be further improved.

[0077] Further, as the epoxy compound having two or more functional groups, an alicyclic epoxy compound having an ester bond in the molecule or an alicyclic epoxy compound having a siloxane bond in the molecule is more preferable. As the alicyclic epoxy compound having an ester bond in the molecule, an alicyclic epoxy compound represented by the following formula (I) is preferable.

[0078] [Chemical formula]

[0079] In formula (I), R represents a divalent organic linking group having an ester bond.

[0080] The divalent organic linking group having an ester bond is not particularly limited. For example, in addition to the ester bond, a group in which one or more ester bonds and one or more divalent hydrocarbon groups are linked can be mentioned. Examples of the divalent hydrocarbon group that links to the ester bond include a linear or branched alkylene group having 1 to 18 carbon atoms, and a divalent alicyclic hydrocarbon group.

[0081] The number of atoms of the divalent organic linking group represented by R in formula (I) is not particularly limited, but for example, it is preferably 3 or more, more preferably 3 to 200, still more preferably 3 to 100, and particularly preferably 3 to 30. In the present disclosure, the "number of atoms of the organic linking group" means the number of atoms in the main chain of the organic linking group. The "number of atoms in the main chain" refers to the number of atoms in the atomic chain that links two alicyclic epoxy groups in formula (I), and does not include the number of atoms of the substituent. For example, when the main chain in the organic linking group contains a "cyclohexane ring", the number of atoms in the cyclohexane ring part is counted as "6".

[0082] As the alicyclic epoxy compound represented by formula (I), a compound represented by the following formula (II) is preferable.

[0083] [Chemical formula]

[0084] In formula (II), n represents an integer of 0 to 5, preferably an integer of 0 to 4, more preferably an integer of 0 to 3, and particularly preferably 0 or 1.

[0085] As the epoxy compound having two or more functional groups, commercially available products can be used. Examples of commercially available products of the epoxy compound having two or more functional groups include "Celloxide 2021P" and "Celloxide 2081" [both manufactured by Daicel Corporation], which are commercially available products of alicyclic epoxy compounds having an ester bond in the molecule, and "X-40-2669", "X-40-2678", and "KR-470" [both manufactured by Shin-Etsu Chemical Co., Ltd.], which are commercially available products of alicyclic epoxy compounds having a siloxane bond in the molecule. Further, examples of commercially available products of the epoxy compound having two or more functional groups include "TETRAD (registered trademark)-X" and "TETRAD (registered trademark)-C" [both manufactured by Mitsubishi Gas Chemical Company, Inc.], and "Denacol (registered trademark) EX-201" and "Denacol (registered trademark) EX-931" [both manufactured by Nagase ChemteX Corporation].

[0086] When the pressure-sensitive adhesive composition of the present disclosure contains an epoxy compound having two or more functional groups, it may contain only one kind of the epoxy compound having two or more functional groups, or may contain two or more kinds.

[0087] When the pressure-sensitive adhesive composition of the present disclosure contains an epoxy compound having two or more functional groups, the content of the epoxy compound having two or more functional groups is not particularly limited. For example, it is preferably in the range of 0.05 parts by mass or more and 0.5 parts by mass or less, more preferably in the range of 0.1 parts by mass or more and 0.4 parts by mass or less, and still more preferably in the range of 0.15 parts by mass or more and 0.3 parts by mass or less with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A).

[0088] 〔Specific silane compound (C)〕 The pressure-sensitive adhesive composition of the present disclosure contains a silane compound (C) having a mercapto group and an alkoxysilyl group [that is, a specific silane compound (C)]. In the pressure-sensitive adhesive composition of the present disclosure, the specific silane compound (C) can contribute to the improvement of the high-temperature durability of the formed pressure-sensitive adhesive layer.

[0089] The number of mercapto groups in the specific silane compound (C) may be 1 or more, and may also be 2 or more.

[0090] The mercapto group equivalent of the specific silane compound (C) is not particularly limited. For example, from the viewpoint of the strength of the interaction between the silane compound (C) and the (meth)acrylic copolymer, it is preferably 300 g / eq to 1000 g / eq, and more preferably 400 g / eq to 800 g / eq. In the present disclosure, the mercapto group equivalent of the specific silane compound (C) is a value measured by a titration method using a potassium iodide solution and a sodium thiosulfate solution.

[0091] The type of alkoxysilyl group in the specific silane compound (C) is not particularly limited. The alkoxysilyl group in the specific silane compound (C) is preferably an alkoxysilyl group having 1 to 3 carbon atoms in the alkoxy group, and more preferably an alkoxysilyl group having 1 to 2 carbon atoms in the alkoxy group, from the viewpoint of reactivity with the silanol group on the glass surface. Specific examples of the alkoxysilyl group include a methoxysilyl group and an ethoxysilyl group.

[0092] The number of alkoxysilyl groups in the specific silane compound (C) may be 1 or more, and may also be 2 or more.

[0093] The specific silane compound (C) preferably has a siloxane bond (-Si-O-Si-). When the specific silane compound (C) has a siloxane bond, the wettability at the interface between the adhesive and the glass is moderately reduced, and the reworkability tends to be improved.

[0094] Examples of the specific silane compound (C) having no siloxane bond include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, and mercaptomethyltrimethoxysilane. Examples of the specific silane compound (C) having a siloxane bond include, for example, an alkoxy oligomer type mercapto group-containing silane coupling agent (so-called mercapto group-containing oligomer type silane coupling agent) having a polysiloxane structure in the main chain.

[0095] As the specific silane compound (C), commercially available products can be used. Examples of commercially available products of the specific silane compound (C) having no siloxane structure include "KBM-802", "KBM-803", and "×-12-1307" [manufactured by Shin-Etsu Chemical Co., Ltd.], and "Z-6062" [manufactured by Dow Corning Toray Co., Ltd.]. Examples of commercially available products of the specific silane compound (C) having a siloxane bond include "X-41-1805" and "X-41-1810" [manufactured by Shin-Etsu Chemical Co., Ltd.].

[0096] The pressure-sensitive adhesive composition of the present disclosure may contain only one kind of the specific silane compound (C), or may contain two or more kinds.

[0097] The content of the specific silane compound (C) in the pressure-sensitive adhesive composition of the present disclosure is not particularly limited as long as the functional group ratio (X) described later is in the range of 2.5×10 -4 or more and 3.5×10 -3 less than. For example, it is preferably in the range of 0.1 part by mass or more and 0.6 part by mass or less, more preferably in the range of 0.15 part by mass or more and 0.5 part by mass or less, and still more preferably in the range of 0.2 part by mass or more and 0.4 part by mass or less with respect to 100 parts by mass of the specific (meth)acrylic copolymer (A).

[0098] 〔Specific silane compound (D)〕 The pressure-sensitive adhesive composition of the present disclosure contains a silane compound (D) having an amino group and not having an alkoxysilyl group (that is, a specific silane compound (D)). In the pressure-sensitive adhesive composition of the present disclosure, the specific silane compound (D) can contribute to the improvement of the reworkability of the formed pressure-sensitive adhesive layer.

[0099] The number of amino groups in the specific silane compound (D) may be 1 or more, and may also be 2 or more. The amino group in the specific silane compound (D) is preferably an amino group derived from a monoamine or an amino group derived from a diamine. For example, from the viewpoint of further improving the high-temperature durability of the formed adhesive layer, it is more preferably an amino group derived from a diamine.

[0100] The amino group equivalent of the specific silane compound (D) is not particularly limited. For example, from the viewpoint of the strength of the interaction between the silane compound (C) and the (meth)acrylic copolymer, it is preferably 1000 g / eq to 8000 g / eq, and more preferably 5000 g / eq to 7000 g / eq. In the present disclosure, the amino group equivalent of the specific silane compound (D) is a value measured by a titration method using an aqueous hydrochloric acid solution.

[0101] Examples of the specific silane compound (D) include a side-chain amino-modified polydimethylsiloxane compound having an amino group in the side chain of the polydimethylsiloxane skeleton, and a both-end amino-modified polydimethylsiloxane compound having amino groups at both ends of the polydimethylsiloxane skeleton.

[0102] As the specific silane compound (D), commercially available products can be used. Examples of commercially available products of the specific silane compound (D) include "X-12-161B", "KF-859", "KF-869", "KF-880", "KF-8004", and "KF-8008" [manufactured by Shin-Etsu Chemical Co., Ltd.].

[0103] The adhesive composition of the present disclosure may contain only one kind of the specific silane compound (D), or may contain two or more kinds.

[0104] The content of the specific silane compound (D) in the adhesive composition of the present disclosure is such that the functional group ratio (X) described later is 2.5×10 -4 or more and 3.5×10 -3If the content is within the range of less than, it is not particularly limited. For example, it is preferably in the range of 0.01 parts by mass or more and 0.7 parts by mass or less, more preferably in the range of 0.05 parts by mass or more and 0.5 parts by mass or less, and even more preferably in the range of 0.1 parts by mass or more and 0.3 parts by mass or less, based on 100 parts by mass of the specific (meth)acrylic copolymer (A).

[0105] <<Functional group ratio>> In the pressure-sensitive adhesive composition of the present disclosure, when the number of moles of the mercapto group in the specific silane compound (C) is P mmol, the number of moles of the amino group in the specific silane compound (D) is Q mmol, and the number of moles of the carboxy group in the specific (meth)acrylic copolymer (A) is R mmol, the functional group ratio [i.e., functional group ratio (X)] obtained by the following formula (X) is 2.5×10 -4 or more and 3.5×10 -3 less than the range. Functional group ratio = P×(Q / R)···(X)

[0106] When the functional group ratio (X) is 2.5×10 -4 or more, the formed pressure-sensitive adhesive layer tends to exhibit excellent reworkability. The functional group ratio (X) is preferably 3.5×10 -4 or more, more preferably 4.5×10 -4 or more, even more preferably 5.5×10 -4 or more, and particularly preferably 6.5×10 -4 or more. When the functional group ratio (X) is 3.5×10 -3 less than, the formed pressure-sensitive adhesive layer tends to exhibit excellent high-temperature durability. The functional group ratio (X) is preferably 2.5×10 -3 or less, more preferably 1.5×10 -3 or less, even more preferably 1.0×10 -3 or less, and particularly preferably 0.5×10 -3 or less. In one aspect, the functional group ratio (X) is 3.5×10 -4 or more and 2.5×10-3 It may also be in the following range, 4.5×10 -4 or more and 1.5×10 -3 It may also be in the following range, 5.5×10 -4 or more and 0.5×10 -3 It may also be in the following range, 6.5×10 -4 or more and 9.5×10 -4 It may be in the following range.

[0107] The number of moles P [unit: mmol] of the mercapto group in the specific silane compound (C) is determined by the following formula (x1). The number of moles P [unit: mmol] of the mercapto group in the specific silane compound (C) = [the amount of the specific silane compound (C) compounded [unit: g]] / [the mercapto group equivalent of the specific silane compound (C) [unit: g / eq]] × 1000 ··· (x1)

[0108] Note that the mercapto group equivalent of the specific silane compound (C) in formula (x1) is determined by the following formula (x1-1). The mercapto group equivalent of the specific silane compound (C) [unit: g / eq] = [the molecular weight of the specific silane compound (C) [unit: g / mol]] / [the number of mercapto groups in one molecule of the specific silane compound (C)] ··· (x1-1)

[0109] The number of moles Q [unit: mmol] of the amino group in the specific silane compound (D) is determined by the following formula (x2). The number of moles Q [unit: mmol] of the amino group in the specific silane compound (D) = [the amount of the specific silane compound (D) compounded [unit: g]] / [the amino group equivalent of the specific silane compound (D) [unit: g / eq]] × 1000 ··· (x2)

[0110] The amino group equivalent of the specific silane compound (D) in formula (x2) is determined by the following formula (x2-1). The amino group equivalent of the specific silane compound (D) [unit: g / eq] =[Molecular weight of the specific silane compound (D) [unit: g / mol]] / [Number of amino groups in one molecule of the specific silane compound (D)] ··· (x2-1)

[0111] The number of moles R [unit: mmol] of carboxyl groups in the specific (meth)acrylic copolymer (A) is determined by the following formula (x3). Note that the molecular weight of the structural unit derived from acrylic acid, which is a monomer having a carboxyl group, is 72.06 g / mol. The number of moles R [unit: mmol] of carboxyl groups in the specific (meth)acrylic copolymer (A) =[Content of the structural unit derived from the monomer having a carboxyl group in the specific (meth)acrylic copolymer (A) [unit: mass%]] / 100 × [Amount of the specific (meth)acrylic copolymer (A) [unit: g]] / [Molecular weight of the structural unit derived from the monomer having a carboxyl group [unit: g / mol]] × [Number of carboxyl groups in the structural unit derived from the monomer having a carboxyl group] × 1000 ··· (x3)

[0112] 〔Organic solvent〕 The pressure-sensitive adhesive composition of the present disclosure may contain an organic solvent. When the pressure-sensitive adhesive composition of the present disclosure contains an organic solvent, the coatability can be improved. Examples of the organic solvent include the same ones as those used in the polymerization reaction of the aforementioned specific (meth)acrylic copolymer (A).

[0113] When the pressure-sensitive adhesive composition of the present disclosure contains an organic solvent, it may contain only one kind of organic solvent or two or more kinds of organic solvents.

[0114] When the pressure-sensitive adhesive composition of the present disclosure contains an organic solvent, the content of the organic solvent is not particularly limited and can be appropriately set according to the purpose.

[0115] 〔Other components〕 The pressure-sensitive adhesive composition of the present disclosure may contain components other than the aforementioned components (so-called other components) as necessary, as long as the effects are not impaired. Examples of other components include polymers other than the specific (meth)acrylic copolymer (A), compounds that can function as crosslinking agents other than polyisocyanate compounds and bifunctional or higher epoxy compounds, crosslinking catalysts, antioxidants, colorants (e.g., dyes and pigments), light stabilizers (e.g., ultraviolet absorbers), antistatic agents, and other various additives.

[0116] When the pressure-sensitive adhesive composition of the present disclosure contains other components, the content of the other components can be appropriately set within a range that does not impair the effects of the pressure-sensitive adhesive composition of the present disclosure.

[0117] [[Use of the Pressure-Sensitive Adhesive Composition]] The use of the pressure-sensitive adhesive composition of the present disclosure is not particularly limited. Since the pressure-sensitive adhesive composition of the present disclosure can form a pressure-sensitive adhesive layer excellent in high-temperature durability and reworkability, it is suitable as, for example, a pressure-sensitive adhesive composition used for an optical film (i.e., a pressure-sensitive adhesive composition for an optical film). The pressure-sensitive adhesive composition of the present disclosure is particularly suitable as a pressure-sensitive adhesive composition used for a polarizing plate among optical films (i.e., a pressure-sensitive adhesive composition for a polarizing plate). Specific uses of the pressure-sensitive adhesive composition of the present disclosure include uses such as bonding a polarizing plate to a glass substrate of a liquid crystal cell and bonding optical films to each other.

[0118] [Adhesive Sheet] The adhesive sheet of the present disclosure includes an adhesive layer formed of the adhesive composition of the present disclosure. The adhesive sheet of the present disclosure includes the sheet-shaped adhesive layer itself formed of the adhesive composition of the present disclosure. The adhesive layer included in the adhesive sheet of the present disclosure contains a cured product of the adhesive composition of the present disclosure. The cured product includes, for example, a crosslinked product of the specific (meth)acrylic copolymer (A) crosslinked and cured with the polyisocyanate compound (B). Since the pressure-sensitive adhesive sheet of the present disclosure includes a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present disclosure described above, in a high-temperature environment (for example, a high-temperature and low-humidity environment), problems caused by shrinkage of the optical film, specifically, wrinkles in the pressure-sensitive adhesive layer and the optical film, and peeling of the pressure-sensitive adhesive layer from the adherend are less likely to occur. Further, since the pressure-sensitive adhesive sheet of the present disclosure includes a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present disclosure described above, foaming is less likely to occur at the interface between the pressure-sensitive adhesive layer and the optical film and / or the adherend in a high-temperature environment (for example, a high-temperature and low-humidity environment). Further, since the pressure-sensitive adhesive sheet of the present disclosure includes a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present disclosure described above, it has excellent reworkability.

[0119] The thickness of the pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet of the present disclosure is not particularly limited. Generally, the thickness of the pressure-sensitive adhesive layer is from 1 μm to 100 μm, preferably from 5 μm to 50 μm, and more preferably from 10 μm to 30 μm.

[0120] In the present disclosure, the "thickness of the pressure-sensitive adhesive layer" means the average thickness of the pressure-sensitive adhesive layer. The average thickness of the pressure-sensitive adhesive layer is a value obtained by the following method. The thicknesses at 10 randomly selected locations in the thickness direction of the pressure-sensitive adhesive layer are measured using a film thickness meter. The arithmetic mean value of the measured values is obtained, and the obtained value is taken as the average thickness of the pressure-sensitive adhesive layer.

[0121] The pressure-sensitive adhesive sheet of the present disclosure may be a substrate-free type pressure-sensitive adhesive sheet having no substrate, or may be a substrate-type pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one or both sides of the substrate. When the pressure-sensitive adhesive sheet of the present disclosure is a substrate-free type pressure-sensitive adhesive sheet having no substrate, or a substrate-type pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one side of the substrate, in the pressure-sensitive adhesive sheet of the present disclosure, the exposed surface of the pressure-sensitive adhesive layer may be protected by a release sheet. Generally, the release sheet protects the surface of the pressure-sensitive adhesive layer until the pressure-sensitive adhesive sheet is put into practical use, and is peeled off during use.

[0122] The release sheet is not particularly limited as long as it can be easily peeled off from the adhesive layer. Examples of the release sheet include a resin film, paper, synthetic paper, and a composite sheet formed by laminating two or more of these materials, which are surface-treated (so-called easy-release treatment) with a release treatment agent on one or both sides. In the present disclosure, a release sheet in which one or both sides of a resin film are surface-treated (so-called easy-release treatment) with a release treatment agent is also referred to as a "release film". Examples of the release treatment agent include silicone-based release treatment agents (e.g., silicone), wax-based release treatment agents (e.g., paraffin wax), and fluorine-based release treatment agents (e.g., fluorine-based resin). Examples of the resin film include polyester films typified by polyethylene terephthalate (PET) films. Examples of the paper include high-quality paper and coated paper. The thickness of the release sheet is not particularly limited and is generally 20 μm to 180 μm.

[0123] When the pressure-sensitive adhesive sheet of the present disclosure includes a base material, the base material is not particularly limited as long as an adhesive layer can be formed thereon. Examples of the base material include films containing resins such as polyolefin-based resins [e.g., polyethylene (PE) and polypropylene (PP)], polyester-based resins [e.g., polyethylene terephthalate (PET)], acetate-based resins (e.g., triacetyl cellulose), polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyurethane-based resins, (meth)acrylic-based resins, vinyl chloride-based resins, ABS (Acrylonitrile Butadiene Styrene) resins, and fluorine-based resins.

[0124] From the viewpoint of improving the adhesion between the base material and the adhesive layer, surface treatment (so-called easy-adhesion treatment) such as corona discharge treatment and plasma discharge treatment may be performed on the surface of the base material on the side where the adhesive layer is provided.

[0125] The base material may contain various additives such as plasticizers, colorants (e.g., dyes and pigments), heat stabilizers, light stabilizers, antistatic agents, flame retardants, antioxidants, fillers, and the like. The base material may be patterned in part or in whole.

[0126] When the pressure-sensitive adhesive sheet of the present disclosure includes a base material, the base material is preferably an optical film. In this case, as an aspect of the pressure-sensitive adhesive sheet of the present disclosure, an aspect including an optical film and an adhesive layer provided on at least one surface of the optical film and formed of the adhesive composition of the present disclosure is preferable.

[0127] The type of the optical film is not particularly limited. Specific examples of the optical film include a polarizing plate, an AG (Anti-Glare) polarizing plate, a wavelength plate (e.g., a 1 / 2 wavelength plate and a 1 / 4 wavelength plate), a retardation film including the above wavelength plate, a viewing angle compensation film, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an antireflection film, a prism sheet, a lens sheet, a diffusion plate, and a transparent conductive film.

[0128] As the optical film, a polarizing plate (so-called polarizing film) is preferable. The polarizing plate is composed of at least a polarizer, and may be a single polarizer or a laminate of a polarizer and a protective film. That is, the polarizing plate may have a single-layer structure of only a polarizer, a two-layer structure having a protective film on one surface of the polarizer, or a three-layer structure having protective films on both surfaces of the polarizer.

[0129] Examples of the layer structure aspect when the pressure-sensitive adhesive sheet of the present disclosure includes a base material and the base material is a polarizing plate include aspects such as an adhesive layer / polarizing plate [protective film / polarizer / protective film], an adhesive layer / polarizing plate [retardation film / polarizer / protective film], and an adhesive layer / polarizing plate [retardation film / protective film / polarizer / protective film].

[0130] As the protective film, for example, films containing resins such as triacetyl cellulose (TAC), polycyclic olefin (COP), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA) are used. As the polarizer, for example, a stretched film of polyvinyl alcohol (PVA) impregnated with iodine is used. As the retardation film, for example, films containing resins such as polycyclic olefin (COP) are used.

[0131] The thickness of the base material is not particularly limited, but generally it is 10 μm to 500 μm, preferably 10 μm to 300 μm, more preferably 10 μm to 200 μm, and even more preferably 10 μm to 130 μm.

[0132] In the present disclosure, the "thickness of the base material" means the average thickness of the base material. The average thickness of the base material is a value obtained by the following method. The thicknesses of 10 randomly selected locations in the thickness direction of the base material are measured using a film thickness gauge. The arithmetic mean value of the measured values is obtained, and the obtained value is taken as the average thickness of the base material.

[0133] [Method for producing an adhesive sheet] The method for producing the adhesive sheet of the present disclosure is not particularly limited. The adhesive sheet of the present disclosure can be produced by a known method. As a method for producing the adhesive sheet of the present disclosure, for example, the following methods can be mentioned.

[0134] When the adhesive sheet of the present disclosure is a non-base material type adhesive sheet, first, the adhesive composition of the present disclosure is applied to the easily peelable treatment surface of the release sheet to form a coating film on the release sheet. Next, the formed coating film is dried to form an adhesive film on the release sheet. Next, the exposed surface of the formed adhesive film is overlapped and bonded to the easily peelable treatment surface of a separately prepared release sheet, and then curing is performed to produce the adhesive sheet of the present disclosure having a laminated structure of release sheet / adhesive layer / release sheet.

[0135] When the pressure-sensitive adhesive sheet of the present disclosure is a substrate-type pressure-sensitive adhesive sheet, first, by applying the pressure-sensitive adhesive composition of the present disclosure to one surface of the substrate (preferably, the easily adherable treated surface), a coating film is formed on the substrate. Next, by drying the formed coating film, a pressure-sensitive adhesive film is formed on the substrate. Next, after overlapping and bonding the exposed surface of the formed pressure-sensitive adhesive film to the easily peelable treated surface of the release sheet, curing is performed, whereby the pressure-sensitive adhesive sheet of the present disclosure having a laminate structure of substrate / pressure-sensitive adhesive layer / release sheet can be produced.

[0136] When the pressure-sensitive adhesive sheet of the present disclosure is a substrate-type pressure-sensitive adhesive sheet, as another method, for example, the following method can also be mentioned. By applying the pressure-sensitive adhesive composition of the present disclosure to the easily peelable treated surface of the release sheet, a coating film is formed on the release sheet. Next, by drying the formed coating film, a pressure-sensitive adhesive film is formed on the release sheet. Next, after overlapping and bonding the exposed surface of the formed pressure-sensitive adhesive film to one surface of the substrate (preferably, the easily adherable treated surface), curing is performed, whereby the pressure-sensitive adhesive sheet of the present disclosure having a laminate structure of substrate / pressure-sensitive adhesive layer / release sheet can be produced.

[0137] The coating method of the pressure-sensitive adhesive composition is not particularly limited. Examples of the coating method of the pressure-sensitive adhesive composition include known methods using a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a knife coater, a spray coater, a bar coater, an applicator, etc. The coating amount of the pressure-sensitive adhesive composition is not particularly limited and is appropriately set according to, for example, the thickness of the pressure-sensitive adhesive layer to be formed.

[0138] The drying method of the coating film is not particularly limited. Examples of the drying method of the coating film include methods such as natural drying, heat drying, hot air drying, and vacuum drying. The drying temperature and drying time of the coating film are not particularly limited and are appropriately set according to the thickness of the coating film, the amount of the organic solvent in the coating film, etc. As an example of the drying conditions, there are conditions where air at 60°C to 130°C is blown at a wind speed of 3 m / s to 5 m / s for 30 seconds to 300 seconds using a hot air circulation dryer for drying.

[0139] As a curing method, for example, there is a method of leaving it to stand for 2 days to 7 days in an environment with an ambient temperature of 20°C to 35°C and a relative humidity of 45% to 55%.

[0140] [Optical member] The optical member of the present disclosure includes a glass substrate, an adhesive layer formed by the adhesive composition of the present disclosure described above, and an optical film, in this order. Since the optical member of the present disclosure includes an adhesive layer formed by the adhesive composition of the present disclosure described above, in a high-temperature environment (for example, a high-temperature and low-humidity environment), problems caused by shrinkage of the optical film, specifically, wrinkles in the adhesive layer and the optical film, and peeling of the adhesive layer from the glass substrate are less likely to occur. Further, since the optical member of the present disclosure includes an adhesive layer formed by the adhesive composition of the present disclosure described above, foaming is less likely to occur at the interface between the adhesive layer and the optical film and / or the glass substrate in a high-temperature environment (for example, a high-temperature and low-humidity environment).

[0141] The thickness of the glass substrate is not particularly limited, and generally is 0.3 mm to 0.7 mm, and preferably is 0.3 mm to 0.5 mm.

[0142] Examples of the glass substrate include a soda glass plate, a non-alkali glass plate, and a glass plate with an ITO (Indium Tin Oxide) film.

[0143] The adhesive layer and the optical film in the optical member of the present disclosure are synonymous with the adhesive layer and the optical film in the adhesive sheet of the present disclosure, and the preferred embodiments are also the same, so the description is omitted here.

[0144] The optical member of the present disclosure can be suitably used, for example, as a member of a display device. Examples of the display device include, for example, a liquid crystal display and an organic EL (Electro-Luminescence) display.

[0145] The manufacturing method of the optical member of the present disclosure is not particularly limited. The optical member of the present disclosure can be manufactured, for example, by using an optical film as a base material, producing the pressure-sensitive adhesive sheet of the present disclosure by the method described above, and then bonding the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and a glass substrate.

[0146] [Display device] The display device of the present disclosure includes the optical member of the present disclosure described above. Since the display device of the present disclosure includes the optical member of the present disclosure, even when placed in a high-temperature environment (for example, a high-temperature and low-humidity environment), foaming hardly occurs at the interface between the pressure-sensitive adhesive layer and the optical film and / or the glass substrate, peeling hardly occurs between the pressure-sensitive adhesive layer and the glass substrate, and wrinkles hardly occur in the pressure-sensitive adhesive layer and / or the optical film.

[0147] Specific examples of the display device are as described above.

Example

[0148] Hereinafter, the pressure-sensitive adhesive composition of the present disclosure will be described more specifically with reference to examples. The present disclosure is not limited to the following examples as long as the gist thereof is not exceeded.

[0149] [Production of (meth)acrylic copolymer (A)] [Production Example A-1] Into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, 78.7 parts by mass of n-butyl acrylate [n-BA; an alkyl acrylate monomer], 18.0 parts by mass of phenoxyethyl acrylate [PHEA; an acrylate having an aromatic ring], 0.5 parts by mass of acrylic acid [AA; a monomer having a carboxy group], 2.8 parts by mass of 2-hydroxyethyl acrylate [2HEA; a monomer having a hydroxyl group], 133.3 parts by mass of ethyl acetate [an organic solvent], and 20.0 parts by mass of methyl acetate [an organic solvent] were put and mixed to obtain a mixture. Then, the inside of the reactor was purged with nitrogen. Next, after heating the mixture in the reactor to 70 °C while stirring, 0.01 part by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) [ABVN; a polymerization initiator] and 60.0 parts by mass of methyl acetate were sequentially added to the mixture in the reactor. After completion of the addition, it was held for 6 hours to cause a polymerization reaction to obtain a polymerization reaction product. The obtained polymerization reaction product was diluted with ethyl acetate to a solid content concentration of 25.0% by mass and then cooled to obtain a solution of the (meth)acrylic copolymer A-1.

[0150] As used herein, the "solid content concentration" means the mass ratio of the (meth)acrylic copolymer A-1 in the solution of the (meth)acrylic copolymer A-1. The same applies to the solutions of the (meth)acrylic copolymers A-2 to A-15 produced below.

[0151] 〔Production Examples A-2 and A-13 to A-15〕 In Production Examples A-2 and A-13 to A-15, the same operations as in Production Example A-1 were carried out except that the monomer composition of the (meth)acrylic copolymer (A) was changed to the monomer composition shown in Table 1, and solutions of the (meth)acrylic copolymers A-2 and A-13 to A-15 having a solid content concentration of 25.0% by mass were obtained.

[0152] 〔Production Examples A-3 to A-12〕 In Production Examples A-3 to A-12, the monomer composition of the (meth)acrylic copolymer (A) was changed to the monomer composition shown in Table 1, and at least one of the amount of the organic solvent used and the amount of the polymerization initiator used was adjusted so that the weight average molecular weight of the (meth)acrylic copolymer (A) was adjusted to the weight average molecular weight shown in Table 1. Otherwise, the same operations as in Production Example A-1 were carried out to obtain solutions of (meth)acrylic copolymers A-3 to A-12 having a solid content concentration of 25.0% by mass.

[0153] The monomer compositions [unit: mass%] and weight average molecular weights (denoted as "Mw") of the (meth)acrylic copolymers A-1 to A-15 are shown in Table 1.

[0154] The weight average molecular weights of the (meth)acrylic copolymers A-1 to A-15 were measured by the same method as the method for measuring the weight average molecular weight of the specific (meth)acrylic copolymer (A) described above.

[0155] Among the (meth)acrylic copolymers A-1 to A-15, the (meth)acrylic copolymers A-1 to A-10 and A-12 correspond to the specific (meth)acrylic copolymer (A) in the present disclosure.

[0156]

Table 1

[0157] Details of each monomer described in Table 1 are as shown below. <(Meth)acrylic acid alkyl ester monomer> 「n-BA」: n-butyl acrylate 「MA」: methyl acrylate 「MMA」: methyl methacrylate <Monomer having a carboxy group> 「AA」: acrylic acid (molecular weight: 72.06) <Monomer having a hydroxy group> 「2HEA」: 2-hydroxyethyl acrylate <Other monomers (monomers having an aromatic ring)> 「PHEA」: Phenoxyethyl acrylate

[0158] In Table 1, the "-" described in the monomer composition column means that the monomer corresponding to that column is not used.

[0159] [Preparation of Adhesive Composition] [Example 1] 400.00 parts by mass of a solution of (meth)acrylic copolymer A-1 (100 parts by mass as solids), 0.56 parts by mass of Takenate D-101E [trade name, adduct of tolylene diisocyanate (TDI) and trimethylolpropane (TMP), solid content concentration: 45% by mass, manufactured by Mitsui Chemicals, Inc.] as the polyisocyanate compound (B) (0.25 parts by mass as solids), 0.30 parts by mass of X-41-1810 [trade name, silane compound having a methyl group, a mercapto group, and a siloxane bond, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.] as the silane compound (C) (0.30 parts by mass as solids), 0.15 parts by mass of KF-859 [trade name, silane compound having an amino group and no alkoxysilyl group, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.] as the silane compound (D) (0.15 parts by mass as solids), and an appropriate amount of ethyl acetate [organic solvent] were thoroughly mixed to obtain the adhesive composition of Example 1.

[0160] [Examples 2 to 20] In Examples 2 to 20, the same operations as in Example 1 were performed except that the composition of the adhesive composition was changed to the composition shown in Table 2, and the adhesive compositions of Examples 2 to 20 were obtained.

[0161] [Examples 21 to 28] In Examples 21 to 28, the same operations as in Example 1 were performed except that the composition of the adhesive composition was changed to the composition shown in Table 3, and the adhesive compositions of Examples 21 to 28 were obtained.

[0162] [Comparative Examples 1 to 15] In Comparative Examples 1 to 15, the same operations as in Example 1 were carried out except that the composition of the pressure-sensitive adhesive composition was changed to the composition shown in Table 4, and each pressure-sensitive adhesive composition of Comparative Examples 1 to 15 was obtained.

[0163] The compositions of each pressure-sensitive adhesive composition of Examples 1 to 28 and Comparative Examples 1 to 15, and the number of moles of carboxyl groups [unit: mmol] in the (meth)acrylic copolymer (A), the number of moles of mercapto groups [unit: mmol] in the silane compound (C), the number of moles of amino groups [unit: mmol] in the silane compound (D), and the functional group ratio in each pressure-sensitive adhesive composition of Examples 1 to 28 and Comparative Examples 1 to 15 are shown in Tables 2 to 4.

[0164] The number of moles of carboxyl groups [unit: mmol] in the (meth)acrylic copolymer (A), the number of moles of mercapto groups [unit: mmol] in the silane compound (C), the number of moles of amino groups [unit: mmol] in the silane compound (D), and the functional group ratio were determined by the same methods as the number of moles of carboxyl groups R [unit: mmol] in the specific (meth)acrylic copolymer (A), the number of moles of mercapto groups P [unit: mmol] in the specific silane compound (C), the number of moles of amino groups Q [unit: mmol] in the specific silane compound (D), and the method for obtaining the functional group ratio (X) described above, that is, by Formula (x1), Formula (x2), Formula (x3), and Formula (X).

[0165] In Tables 2 to 4, "the number of moles of carboxyl groups in the (meth)acrylic copolymer (A)" is described as "the number of moles of carboxyl groups in (A)", "the number of moles of mercapto groups in the silane compound (C)" is described as "the number of moles of mercapto groups in (C)", and "the number of moles of amino groups in the silane compound (D)" is described as "the number of moles of amino groups in (D)".

[0166]

Table 2

[0167]

Table 3

[0168]

Table 4

[0169] The details of the components described in Tables 2 to 4 are as shown below.

[0170] <Polyisocyanate-based compound> "Takenate D-101E" [trade name, adduct of tolylene diisocyanate (TDI) and trimethylolpropane (TMP), solid content concentration: 45% by mass, manufactured by Mitsui Chemicals, Inc.] "Takenate D-110N" [trade name, adduct of xylylene diisocyanate (XDI) and trimethylolpropane (TMP), solid content concentration: 75% by mass, manufactured by Mitsui Chemicals, Inc.] The above "Takenate" is a registered trademark.

[0171] <Epoxy-based compound having two or more functional groups> "Celoxide 2021P" [trade name, chemical name: 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, an alicyclic epoxy-based compound having an ester bond in the molecule represented by formula (II), solid content concentration: 100% by mass, manufactured by Daicel Corporation] "X-40-2669" [trade name, alicyclic epoxy group-containing linear siloxane difunctional oligomer (so-called alicyclic epoxy-based compound having a siloxane bond in the molecule), solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.]

[0172] <Silane compound (C)> "X-41-1810" [trade name, silane-based compound having a methyl group, a mercapto group, and a siloxane bond, mercapto group equivalent: 450 g / eq, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.]] "X-41-1805" [trade name, silane-based compound having a methyl group, a mercapto group, and a siloxane bond, mercapto group equivalent: 800 g / eq, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.]] 「X-12-1307」[Trade name, silane compound having a mercapto group, mercapto group equivalent: 168 g / eq, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.] The above "X-41-1810", "X-41-1805", and "X-12-1307" all correspond to the specific silane compound (C) in the present disclosure.

[0173] <Silane compound (D)> 「KF-859」[Trade name, silane compound having an amino group and no alkoxysilyl group, amino group equivalent: 6000 g / eq, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.] 「KF-880」[Trade name, silane compound having an amino group and no alkoxysilyl group, amino group equivalent: 1800 g / eq, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.] 「KF-8004」[Trade name, silane compound having an amino group and no alkoxysilyl group, amino group equivalent: 1500 g / eq, solid content concentration: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.] The above "KF-859", "KF-880", and "KF-8004" all correspond to the specific silane compound (D) in the present disclosure.

[0174] <Other silane compounds> 「SH-8400」[Trade name, side-chain polyether-modified silicone oil, solid content concentration: 100% by mass, manufactured by Dow Corning Toray Co., Ltd.] 「KBM-403」[Trade name, chemical name: 3-glycidoxypropyltrimethoxysilane, solid content concentration: 100% by mass, manufactured by Dow Corning Toray Co., Ltd.]

[0175] In Tables 2 to 4, the numerical values described in the column of "blending amount" are all values in terms of solid content. In Tables 2 to 4, the "-" described in the column of the composition of the adhesive composition means that the component corresponding to that column is not blended. In Tables 2 to 4, the "-" described in the columns of "number of moles of carboxy groups in (A)", "number of moles of mercapto groups in (C)", "number of moles of amino groups in (D)", and "functional group ratio" means that there is no corresponding one.

[0176] [Preparation of Polarizing Plate with Adhesive Layer] The pressure-sensitive adhesive composition prepared above was applied to the easily peelable surface of a release film [type: MRF, thickness: 38 μm, manufactured by Mitsubishi Chemical Corporation] that had been surface-treated with a silicone-based release treatment agent (so-called easy-peeling treatment) to form a coating film. The coating amount of the pressure-sensitive adhesive composition was set to an amount such that the thickness of the pressure-sensitive adhesive film described later would be 20 μm. Next, the formed coating film was dried by blowing air at 100 °C at a wind speed of 3 m / s for 60 seconds using a hot air circulation dryer to form a pressure-sensitive adhesive film with a thickness of 20 μm on the release film. Next, the exposed surface of the formed pressure-sensitive adhesive film and one surface of a polarizing plate (thickness: 100 μm) having a structure of a triacetyl cellulose (TAC) layer / polyvinyl alcohol (PVA) layer containing a polarizer / TAC layer were overlapped and bonded together. Next, the laminate obtained by the bonding was allowed to stand in an environment of an ambient temperature of 23 °C and 50% RH for 7 days (so-called curing period) to cure the pressure-sensitive adhesive film. In the above manner, a polarizing plate with an adhesive layer having a structure of a release film / pressure-sensitive adhesive layer / polarizing plate (TAC layer / PVA layer / TAC layer) was prepared.

[0177] [Evaluation] 1. High-temperature durability (1) Preparation of evaluation sample The polarizing plate with an adhesive layer prepared above was cut so that the long side would be 0° with respect to the absorption axis of the polarizing plate to prepare a test piece having a size of 130 mm (short side) × 230 mm (long side). Next, the release film of the test piece was peeled off. After overlapping the surface of the pressure-sensitive adhesive layer exposed by the peeling and one surface of a glass plate [type: soda glass, manufactured by Matsunami Glass Industry Co., Ltd.] so that they were in contact, they were pressure-bonded using a laminator to bond the test piece and the glass plate together. In the above manner, an evaluation sample having a structure of a glass plate / pressure-sensitive adhesive layer / polarizing plate (TAC layer / PVA layer / TAC layer) was prepared.

[0178] (2) Evaluation test The evaluation sample prepared above was autoclaved at a treatment temperature of 50°C and a treatment pressure of 5 kg / cm 2 for 20 minutes, and then left standing for 24 hours in an environment with an ambient temperature of 23°C and 50% RH. The evaluation sample after standing for 24 hours was left standing for 500 hours in an environment with an ambient temperature of 95°C and 10% RH (so-called high-temperature and low-humidity environment). The state of the evaluation sample after standing for 500 hours was visually observed, and the evaluation was performed according to the following evaluation criteria. The evaluation results are shown in Tables 5 and 6. In the following evaluation criteria, "A", "B", and "C" are practical levels, and "A" is the most preferable.

[0179] - Evaluation criteria - A: No foaming, wrinkles, or peeling were observed in the evaluation sample. B: At least one of foaming, wrinkles, and peeling was slightly observed in the evaluation sample, but it was at a level without practical problems. C: At least one of foaming, wrinkles, and peeling was observed in the evaluation sample, but it was at an acceptable level in practice. D: At least one of foaming, wrinkles, and peeling was significantly observed in the evaluation sample, and it was at an unacceptable level in practice.

[0180] 2. Reworkability (1) Preparation of evaluation sample The polarizing plate with an adhesive layer prepared above was cut to prepare a test piece with a size of 25 mm (short side) × 75 mm (long side). Next, the release film of the test piece was peeled off. After overlapping the surface of the adhesive layer exposed by peeling and one surface of a glass plate [type: soda glass, manufactured by Matsunami Glass Industry Co., Ltd.] so that they were in contact, they were pressure-bonded using a laminator to bond the test piece and the glass plate. As described above, an evaluation sample having a structure of glass plate / adhesive layer / polarizing plate (TAC layer / PVA layer / TAC layer) was prepared.

[0181] (2) Evaluation Test The evaluation sample prepared above was autoclaved at a treatment temperature of 50°C and a treatment pressure of 5 kg / cm 2 for 20 minutes under the conditions, and then left standing for 1 day in an environment with an ambient temperature of 23°C and 50% RH. The evaluation sample left standing for this 1 day is designated as "Evaluation Sample X". Also, as another system, the evaluation sample prepared above was autoclaved at a treatment temperature of 50°C and a treatment pressure of 5 kg / cm 2 for 20 minutes under the conditions, and then left standing for 15 days in an environment with an ambient temperature of 23°C and 50% RH. The evaluation sample left standing for this 15 days is designated as "Evaluation Sample Y". Regarding Evaluation Sample X and Evaluation Sample Y, the adhesive strength (unit: N / 25 mm) when the test piece [composition: adhesive layer / polarizing plate (TAC layer / PVA layer / TAC layer)] was peeled off from the glass plate at 180° in the long side (75 mm) direction was measured using a single-column type material testing machine (model number: STA-1225) manufactured by A&D Company, Limited as the measuring device under the conditions of an ambient temperature of 23°C, 50% RH, and a peeling speed of 0.3 m / min. From the adhesive strength of Evaluation Sample X (so-called, initial adhesive strength) and the adhesive strength of Evaluation Sample Y (so-called, adhesive strength over time), the change amount of the adhesive strength (unit: N / 25 mm) before and after standing of the evaluation sample was obtained by the following formula. Change amount of adhesive strength = (adhesive strength of Evaluation Sample Y) - (adhesive strength of Evaluation Sample X) And the evaluation was carried out according to the following evaluation criteria. The adhesive strength of Evaluation Sample X, the adhesive strength of Evaluation Sample Y, the change amount of the adhesive strength, and the evaluation results are shown in Table 5 and Table 6. In the following evaluation criteria, "A", "B", and "C" are practical levels, and it is most preferable to be "A".

[0182] - Evaluation Criteria - A: The change amount of the adhesive strength was less than 2.0 N / 25 mm. B: The change amount of the adhesive strength was 2.0 N / 25 mm or more and less than 3.0 N / 25 mm. C: The change amount of the adhesive strength was 3.0 N / 25 mm or more and less than 4.0 N / 25 mm. D: The change amount of the adhesive force was 4.0 N / 25 mm or more and / or the adhesive force over time exceeded 12.0 N / 25 mm.

[0183]

Table 5

[0184]

Table 6

[0185] In Table 6, “Measurement impossible ※” means that the adhesive layer was too soft, and the adhesive layer was destroyed during peeling, making it impossible to measure the adhesive force and evaluate the reworkability.

[0186] As shown in Table 5, it was confirmed that the adhesive layers formed from the adhesive compositions of Examples 1 to 28 were excellent in high-temperature durability and reworkability. On the other hand, as shown in Table 6, it was confirmed that at least one of the high-temperature durability and reworkability of the adhesive layers formed from the adhesive compositions of Comparative Examples 1 to 15 was inferior to that of the adhesive layers formed from the adhesive compositions of the Examples.

Claims

1. A (meth)acrylic copolymer (A) containing a structural unit derived from a monomer having a carboxy group in a proportion of 0.5% by mass or more and 3.0% by mass or less based on all the structural units, and having a weight average molecular weight in the range of 500,000 or more and 1,200,000 or less, a polyisocyanate compound (B), a silane compound (C) having a mercapto group and an alkoxysilyl group, a silane compound (D) having an amino group and not having an alkoxysilyl group, and containing, wherein the content of the polyisocyanate compound (B) is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the (meth)acrylic copolymer (A), When the number of moles of the mercapto group in the silane compound (C) is P mmol, the number of moles of the amino group in the silane compound (D) is Q mmol, and the number of moles of the carboxy group in the (meth)acrylic copolymer (A) is R mmol, the functional group ratio determined by the following formula (X) is 2.5×10 －４ or more and less than 3.5×10 －３ The pressure-sensitive adhesive composition is in the range. functional group ratio = P × (Q / R) ··· (X)

2. The pressure-sensitive adhesive composition according to claim 1, wherein the silane compound (C) has a siloxane bond.

3. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the silane compound (C) is in the range of 0.1 part by mass or more and 0.6 part by mass or less with respect to 100 parts by mass of the (meth)acrylic copolymer (A).

4. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic copolymer (A) further contains a structural unit derived from a monomer having a hydroxyl group.

5. The pressure-sensitive adhesive composition according to claim 1, further containing a polyfunctional alicyclic epoxy compound.

6. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 5.

7. An optical film, and a pressure-sensitive adhesive layer provided on at least one side of the optical film and formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 5, and comprising a pressure-sensitive adhesive sheet.

8. The pressure-sensitive adhesive sheet according to claim 7, wherein the optical film is a polarizing plate.

9. A glass substrate, a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 5, and an optical film, and an optical member provided in this order.

10. A display device comprising the optical member according to claim 9.

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