Adhesive sheet, adhesive sheet for a tape-shaped release film, laminate for image display device, image display device, adhesive sheet for organic light emitting diode display device

Abstract

Provided is an adhesive sheet that has sufficient impact resistance and transparency and excellent ultraviolet absorbency up to the vicinity of the visible light region (for example, wavelength 405 nm). An adhesive sheet comprising a resin component (A) having a structural unit derived from a (meth)acrylate-based monomer and an ultraviolet absorber (B), and satisfying the following requirements [I] and [II]. [I] The aforementioned ultraviolet absorber (B) comprises an ultraviolet absorber (B-1) having an absorption maximum at a wavelength of 300 to 360 nm and an ultraviolet absorber (B-2) other than the aforementioned (B-1) having an absorption maximum at a wavelength of 350 to 420 nm. [II] The content ratio of the ultraviolet absorber (B-1) to the ultraviolet absorber (B-2) contained in the aforementioned adhesive sheet is 30:70 to 70:30 by mass ratio.

Description

Technical Field

[0001] This invention relates to adhesive sheets and adhesive sheets with release films using the adhesive sheets, laminates for image display devices, image display devices, and adhesive sheets for organic light-emitting diode (OLED) display devices. More specifically, it relates to adhesive sheets having sufficient adhesion, impact resistance, and excellent ultraviolet absorption up to the vicinity of the visible light region, and adhesive sheets with release films using the adhesive sheets, laminates for image display devices, image display devices, and adhesive sheets for organic light-emitting diode (OLED) display devices. Background Technology

[0002] In recent years, driven by the demand for power-saving, lightweight, and thinner image display devices used in mobile electronic devices, image display devices using organic light-emitting diodes (OLEDs) and quantum dots (QDs) have been developed and widely adopted. To improve the visibility of these image display devices, resins such as adhesive sheets and adhesives are used to fill the gaps between the image display panel and optical components such as the protective panel and touch panel components located on its front side (viewable side), suppressing the reflection of incident light and emitted light from the displayed image at the air layer interface.

[0003] The aforementioned image display devices sometimes suffer from degradation of their constituent components due to incident ultraviolet (UV) radiation. Organic light-emitting diodes (OLEDs), in particular, are susceptible to UV degradation; therefore, it is important to protect OLEDs from UV radiation incident from outdoor sunlight. As a solution, it is known to incorporate UV absorbers into transparent adhesive sheets; for example, adhesive sheets containing UV absorbers are disclosed in Patent Documents 1 and 2.

[0004] On the other hand, mobile electronic devices are often exposed to the risk of damage from impacts such as drops due to their usage. In order to prevent components from being damaged by impacts from drops and to prevent components from peeling off from each other, the adhesive sheet itself is also required to be impact-resistant. For example, Patent Document 3 discloses an adhesive sheet that has a tanδ peak between -20 and 0°C and a tanδ peak value of 0.8 or higher.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2022-148857

[0008] Patent Document 2: Japanese Patent Application Publication No. 2021-185570

[0009] Patent Document 3: Japanese Patent Application Publication No. 2023-8631 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] Recently, with the trend towards thinner mobile electronic devices, in addition to protecting them from externally incident ultraviolet radiation, the adhesive sheet itself is required to have impact resistance to protect the internal components of the image display device from impacts from the external environment. While the technologies disclosed in Patent Documents 1 and 2 take into account ultraviolet absorption and the durability of the adhesive sheet, they do not consider the impact resistance of the adhesive. Furthermore, while the technology disclosed in Patent Document 3 takes into account the impact resistance of the adhesive, it does not consider protection against ultraviolet radiation.

[0012] Therefore, in this context, the present invention provides an adhesive sheet with sufficient transparency and excellent ultraviolet absorption up to the vicinity of the visible light region (e.g., wavelength 405 nm). Furthermore, an adhesive sheet with sufficient impact resistance is also provided.

[0013] Methods for solving problems

[0014] However, the inventors conducted repeated and in-depth research in view of the above situation and found that the aforementioned problems could be solved by combining two ultraviolet absorbers that have great absorption at a specific wavelength and setting their content ratio within a specific range.

[0015] That is, the present invention has the following aspects.

[0016] [1] An adhesive sheet comprising: a resin component (A) having structural units derived from (meth)acrylate monomers, and an ultraviolet absorber (B), and satisfying the following requirements [I] and [II].

[0017] [I] The aforementioned ultraviolet absorber (B) includes ultraviolet absorbers (B-1) that have maximum absorption at wavelengths of 300 to 360 nm and ultraviolet absorbers (B-2) other than the aforementioned (B-1) that have maximum absorption at wavelengths of 350 to 420 nm.

[0018] [II] The ratio of ultraviolet absorber (B-1) to ultraviolet absorber (B-2) in the aforementioned adhesive sheet is 30:70 to 70:30 by mass.

[0019] [2] The adhesive sheet according to [1] also satisfies the following requirement [III].

[0020] [III] The shear storage modulus at -20°C obtained by dynamic viscoelasticity determination in shear mode at a passing frequency of 1 Hz is less than 2.0 MPa, and the glass transition temperature obtained from the peak of the loss tangent (tanδ) is less than -20°C.

[0021] [3] The adhesive sheet according to [1] or [2], wherein the aforementioned ultraviolet absorber (B-2) has a pyrimidine structure.

[0022] [4] The adhesive sheet according to any one of [1] to [3], wherein the content of the aforementioned ultraviolet absorber (B) is 0.1 to 20% by mass relative to the adhesive sheet.

[0023] [5] The adhesive sheet according to any one of [1] to [4], wherein the aforementioned resin component (A) has a structural unit derived from the crosslinking agent (C).

[0024] [6] According to the adhesive sheet of [5], wherein the aforementioned crosslinking agent (C) comprises an acrylic crosslinking agent with a glass transition temperature (Tg) of -20°C or less as determined by the Fox formula.

[0025] [7] According to the adhesive sheet of [5] or [6], wherein the aforementioned crosslinking agent (C) comprises an acrylic crosslinking agent having 1 to 3 olefinic unsaturated groups in the molecule.

[0026] [8] The adhesive sheet according to any one of [5] to [7], wherein the aforementioned crosslinking agent (C) comprises an acrylic crosslinking agent having an oxonide structure.

[0027] [9] The adhesive sheet according to any one of [5] to [8], wherein the aforementioned crosslinking agent (C) comprises a multifunctional (meth)acrylate oligomer with a weight average molecular weight of 1000 or more.

[0028]

[10] The adhesive sheet according to any one of [5] to [9], wherein the aforementioned crosslinking agent (C) comprises urethane (meth) acrylate.

[0029]

[11] The adhesive sheet according to any one of [1] to

[10] , wherein the aforementioned adhesive sheet comprises a photoinitiator (D).

[0030]

[12] According to the adhesive sheet described in

[11] , wherein the aforementioned photoinitiator (D) is a hydrogen-abstracting photoinitiator.

[0031]

[13] The adhesive sheet according to any one of [1] to

[12] has a gel fraction of 5 to 80%.

[0032]

[14] An adhesive sheet with a release film, comprising a structure formed by laminating the adhesive sheet described in any one of [1] to

[13] with a release film.

[0033]

[15] A laminate for an image display device, comprising two optical components laminated together by means of an adhesive sheet as described in any one of [1] to

[13] .

[0034]

[16] An image display device comprising the image display device laminate described in

[15] .

[0035]

[17] An adhesive sheet for an organic light-emitting diode display device, comprising any one of [1] to

[13] .

[0036] Invention Effects

[0037] The adhesive sheet of the present invention has sufficient transparency and excellent ultraviolet absorption up to the vicinity of the visible light region (e.g., wavelength 405 nm), and thus excellent impact resistance. Therefore, it is suitable for use as an adhesive sheet for bonding optical components, especially for organic light-emitting diode (OLED) display devices. Detailed Implementation

[0038] Hereinafter, an example of an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiment described below.

[0039] It should be noted that in this invention, the concept of "thin film" includes sheets, films, and strips.

[0040] In addition, when referred to as "panel" as such as image display panel or protective panel, it includes sheet, sheet and film.

[0041] In this specification, when the terms are referred to as "x~y" (where x and y are arbitrary numbers), unless otherwise specified, they include the meaning of "more than x and less than y", and also include the meaning of "preferably greater than x" or "preferably less than y".

[0042] In addition, when it is recorded as "x or above" (where x is any number), unless otherwise specified, it includes the meaning of "preferably greater than x". When it is recorded as "y or below" (where y is any number), unless otherwise specified, it also includes the meaning of "preferably less than y".

[0043] Furthermore, in this specification, "x and / or y (x and y are arbitrary configurations)" refers to at least one of x and y, and specifically to the three possibilities of x only, y only, and x and y.

[0044] In addition, in this specification, "(meth)acrylic acid" means including acrylic acid and methacrylic acid, "(meth)acrylate" means including acrylate and methacrylate, and "(meth)acryloyl" means including acryloyl and methacryloyl.

[0045] In this specification, "(meth)acrylate polymer" refers to a resin obtained by polymerizing a polymeric component containing at least one (meth)acrylate monomer, having structural units derived from (meth)acrylate monomers.

[0046] <<Adhesive Sheet>>

[0047] An adhesive sheet according to one embodiment of the present invention (hereinafter referred to as "the adhesive sheet") comprises the resin component (A) described later and the ultraviolet absorber (B).

[0048] The physical properties of this adhesive sheet are described below.

[0049] <Physical properties of this adhesive sheet>

[0050] [Light transmittance]

[0051] The light transmittance of this adhesive sheet at a wavelength of 380 nm is typically less than 5%, preferably less than 3%, more preferably less than 2%, and particularly preferably less than 1%. Having such light transmittance, it tends to protect the components of the image display device from degradation caused by ultraviolet light.

[0052] Furthermore, the light transmittance of this adhesive sheet at a wavelength of 405 nm is typically less than 10%, preferably less than 8%, more preferably less than 7%, and particularly preferably less than 5%. With such light transmittance, even components of an image display device that are easily degraded by light tend to be reliably protected from the effects of incident light.

[0053] Furthermore, the light transmittance of this adhesive sheet at a wavelength of 430 nm is typically 70% or more, preferably 73% or more, and particularly preferably 75% or more. With such light transmittance, it tends to be suitable for applications requiring transparency, such as image display devices.

[0054] The transmittance of light at each of the aforementioned wavelengths was obtained by measuring it using a spectrophotometer.

[0055] [Shear storage modulus at -20℃ (G'(-20℃))]

[0056] The shear storage modulus (G'(-20℃)) of this adhesive sheet at -20℃, obtained by dynamic viscoelasticity measurement in shear mode at a frequency of 1 Hz, is preferably 2.0 MPa or less, more preferably 1.8 MPa or less, even more preferably 1.5 MPa or less, and particularly preferably 1.25 MPa or less. It should be noted that, from the viewpoint of maintaining shape, the lower limit of the shear storage modulus (G'(-20℃)) of this adhesive sheet is preferably 0.1 MPa.

[0057] By setting the shear storage modulus (G'(-20°C)) of this adhesive sheet to the aforementioned range, for example, when this adhesive sheet is bonded to a component sheet to form a laminate or an image display device component, it can improve the flexibility of the laminate or image display device component, especially at low temperatures, and can suppress the tendency of the component sheet or image display device component to crack due to impact.

[0058] When the impact speed is high, such as when an image display device with this adhesive sheet attached is dropped, or when an object falls onto the image display device, the viscoelastic properties of this adhesive sheet, based on the temperature-time conversion law of viscoelastic materials, exhibit characteristics in a lower temperature range. That is, the elastic behavior becomes relatively stronger, and the impact absorption performance decreases, thus the viscoelastic behavior at low temperatures becomes important.

[0059] [Shear storage modulus at 23℃ (G'(23℃))]

[0060] Furthermore, the shear storage modulus (G'(23°C)) of this adhesive sheet at 23°C, obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz, is preferably 0.25 MPa or less, more preferably 0.20 MPa or less, even more preferably 0.10 MPa or less, particularly preferably 0.09 MPa or less, most preferably 0.08 MPa or less, and especially preferably 0.07 MPa or less. It should be noted that, from the viewpoint of maintaining shape, the lower limit of the shear storage modulus (G'(23°C)) of this adhesive sheet is preferably 0.01 MPa.

[0061] When the shear storage modulus (G'(23℃)) of this adhesive sheet is within the aforementioned range, it tends to have excellent adhesion and flexibility.

[0062] The shear storage modulus at -20℃ (G'(-20℃)) and the shear storage modulus at 23℃ (G'(23℃)) were measured, for example, as follows.

[0063] After repeatedly stacking the adhesive sheet to adjust the thickness to 0.7~1.2mm (e.g. 0.8mm), a circular sample with a diameter of 8mm is punched out. For the obtained sample, dynamic viscoelasticity is measured using a rheometer under the following conditions: measuring fixture: 8mm diameter parallel plate; frequency: 1Hz; measuring temperature: -50~100℃; heating rate: 5℃ / min. The shear storage modulus (G') values ​​at -20℃ and 23℃ are read.

[0064] [Glass transition temperature (Tg)]

[0065] The glass transition temperature (Tg) defined by the maximum point of the loss tangent (tanδ) obtained by dynamic viscoelasticity measurement in shear mode at a frequency of 1 Hz is preferably below -20°C, more preferably below -23°C, further preferably below -26°C, and particularly preferably below -29°C. The lower limit is typically -70°C, preferably -60°C, and more preferably -50°C.

[0066] By keeping the glass transition temperature (Tg) of this adhesive sheet within the aforementioned range, the shear storage modulus (G'(-20℃)) of this adhesive sheet can be easily adjusted to below 2.0 MPa, thereby improving its impact resistance.

[0067] The aforementioned loss tangent (tanδ), expressed as loss modulus (G”) / shear storage modulus (G’), serves as an indicator of whether the adhesive sheet is relatively viscous. Here, a larger value of the loss tangent (Tanδ) of the adhesive sheet indicates that it is more viscous, while a smaller value indicates that it is more non-viscous, i.e., elastic.

[0068] Furthermore, the aforementioned storage modulus (G') is a parameter representing the elastic aspect of this adhesive sheet, which is a viscoelastic body, indicating its ability to store applied deformation energy and the like as elastic energy. On the other hand, the loss modulus (G”) is a parameter representing the viscous aspect of the viscoelastic body, indicating its ability to dissipate applied deformation energy and the like as energy due to internal friction within the adhesive sheet.

[0069] Therefore, when the impact speed is high, such as when an image display device with this adhesive sheet attached is dropped, or when an object falls onto the image display device, the viscoelastic properties of this adhesive sheet, based on the temperature-time conversion law of viscoelastic bodies, exhibit characteristics in a lower temperature range. Therefore, by placing the maximum point of the loss tangent (tanδ) on the lower temperature side, excellent impact resistance can be obtained.

[0070] The aforementioned glass transition temperature (Tg) can be obtained by reading the temperature at which the loss tangent (Tanδ) reaches its maximum, i.e., the peak temperature, from dynamic viscoelastic spectrum data in the shear mode obtained using the same method as the aforementioned shear storage modulus (G').

[0071] [Maximum value of the loss tangent (tanδ)]

[0072] The maximum value of the loss tangent (tanδ) of this adhesive sheet is preferably 1.5 or higher, more preferably 1.7 or higher, and particularly preferably 1.9 or higher. By setting the maximum value of the loss tangent (tanδ) to the aforementioned value or higher, there is a tendency to have high energy dissipation against applied impacts and to improve the impact resistance of the laminate or image display device component. In addition, combined with the effect of flexibility resulting from the aforementioned low shear storage modulus (G'(-20°C)), there is a tendency to further suppress impact-induced breakage of the component sheet or image display device component.

[0073] It should be noted that the maximum value of the loss tangent (tanδ) refers to the peak value in the tanδ curve, that is, the point with the maximum value among the inflection points where the differential changes from positive (+) to negative (-).

[0074] The maximum value of the aforementioned loss tangent (tanδ) is obtained by reading the peak value of the tanδ curve from the dynamic viscoelastic spectrum data under the shear mode obtained by the same method as the aforementioned shear storage modulus (G') determination, i.e. the inflection point where the differential changes from positive (+) to negative (-).

[0075] The maximum values ​​of the shear storage modulus at -20°C (G'(-20°C)), the shear storage modulus at 23°C (G'(23°C)), the glass transition temperature (Tg), and the loss tangent (tanδ) can be adjusted to the aforementioned ranges by adjusting the composition of the adhesive sheet [e.g., the monomer composition of the resin component (A) described later, the weight-average molecular weight, the type of crosslinking agent (C), etc.], or by adjusting the irradiation intensity and amount of active energy rays during the manufacturing of the adhesive sheet described later. However, this method is not the only limitation.

[0076] [Gel score]

[0077] The gel fraction of this adhesive sheet is preferably 5-80%, more preferably 7-70%, further preferably 9-65%, particularly preferably 10-60%, and most preferably 12-55%. By setting the gel fraction of this adhesive sheet to the aforementioned lower limit or above, it tends to be able to adequately maintain its shape. Furthermore, by setting the gel fraction to the aforementioned upper limit or below, it tends to have excellent flexibility.

[0078] The aforementioned gel fraction is a standard for the degree of crosslinking (degree of curing), which can be measured under the measurement conditions described in the examples described later.

[0079] The aforementioned gel fraction can be adjusted to the aforementioned range by adjusting the components constituting the adhesive sheet (e.g., the monomer composition, weight-average molecular weight, and type of crosslinking agent (C) constituting the resin component (A) described later), or by adjusting the irradiation intensity and amount of active energy rays during the manufacturing of the adhesive sheet described later. However, it is not limited to this method.

[0080] [Adhesive strength]

[0081] The adhesive sheet preferably exhibits an adhesion strength of 3 N / cm or more to soda-lime glass at a peel angle of 180° and a peel speed of 300 mm / min, more preferably 4 N / cm or more, and even more preferably 5 N / cm or more. By achieving an adhesion strength of 3 N / cm or more, the laminate for image display devices using this adhesive sheet exhibits excellent durability. Furthermore, the upper limit of the adhesion strength is typically 50 N / cm.

[0082] The aforementioned adhesive force can be measured under the test conditions described in the examples described later.

[0083] [thickness]

[0084] The thickness of this adhesive sheet is not particularly limited, but is typically 10~1000μm, preferably 12~500μm, more preferably 15~250μm, even more preferably 20~100μm, and particularly preferably 25~50μm.

[0085] When the lower limit of the thickness of this adhesive sheet is above the aforementioned value, there is a tendency for improved operability. Furthermore, when the upper limit of the thickness is below the aforementioned value, there is a tendency for the adhesive sheet to be made thinner.

[0086] As described above, this adhesive sheet contains a resin component (A) and an ultraviolet absorber (B).

[0087] As the aforementioned resin component (A), it has structural units derived from (meth)acrylate monomers, for example: resin component (A1) containing a (meth)acrylate polymer (P1) having structural units derived from (meth)acrylate monomers, and resin component (A2) formed from a slurry composition containing (meth)acrylate monomers.

[0088] This adhesive sheet can be obtained, for example, by the following methods: molding an adhesive composition containing a resin component (A1) of a (meth)acrylic polymer (P1) and an ultraviolet absorber (B) into a sheet, allowing it to crosslink and undergo a polymerization reaction to cure it, thereby producing an adhesive sheet (first method); or, coating a slurry composition, irradiating it with active energy rays, heating it, and curing the (meth)acrylic monomer contained in the slurry component to produce an adhesive sheet as a resin component (A2), etc.

[0089] The first and second methods are described in detail below.

[0090] <First Method>

[0091] In the first method, the adhesive sheet is obtained from an adhesive composition comprising a resin component (A1) and an ultraviolet absorber (B).

[0092] In addition, the aforementioned resin component (A1) contains a (meth)acrylate polymer (P1) having structural units derived from (meth)acrylate monomers.

[0093] The components contained in the aforementioned adhesive composition will be described below.

[0094] [(Meth)acrylic polymer (P1)]

[0095] As the (meth)acrylic polymer (P1) contained in the aforementioned adhesive composition, examples include, in addition to homopolymers of (meth)acrylic alkyl esters, copolymers obtained by polymerizing monomer components that can copolymerize with it.

[0096] The (meth)acrylic polymer (P1) is preferably a copolymer, and more preferably a copolymer in which an alkyl (meth)acrylic acid ester (a1) containing alkyl groups with 4 to 30 carbon atoms is used as a copolymer component.

[0097] As a more specific example of the aforementioned copolymer, one could cite as a copolymer of an alkyl (meth)acrylate (a1) containing 4 to 30 carbon atoms (hereinafter sometimes simply referred to as "(meth)acrylate (a1)") and a copolymerizable monomer component selected from any one or more of the following: a carboxyl-containing monomer (a2), a hydroxyl-containing monomer (a3), a nitrogen-containing monomer (a4), an epoxy-containing monomer (a5), a vinyl monomer (a6), an alkyl (meth)acrylate monomer (a7) containing 1 to 3 carbon atoms, an alicyclic monomer (a8), and other copolymerizable monomers (a9).

[0098] Among the aforementioned copolymeric monomers (a2) to (a9), carboxyl-containing monomers (a2), hydroxyl-containing monomers (a3), and nitrogen-containing monomers (a4) are particularly preferred.

[0099] Furthermore, it is particularly preferred that the product does not contain the aforementioned carboxyl-containing monomer (a2) but contains any one of the hydroxyl-containing monomer (a3) ​​or the nitrogen-containing monomer (a4). By containing any one of the hydroxyl-containing monomer (a3) ​​or the nitrogen-containing monomer (a4), it is possible to combine the corrosion resistance, adhesion, and resistance to damp heat whitening properties when the adhered material contains corrosive components such as metals. In addition, from the perspective of improving aggregation, it is particularly preferred that the product contains both the hydroxyl-containing monomer (a3) ​​and the nitrogen-containing monomer (a4).

[0100] [(Meth)acrylate (a1)]

[0101] The aforementioned alkyl methacrylate (a1) is usually represented by the following formula (1).

[0102] CH2=CH(R1)-COO(R2)…(1)

[0103] (In the formula, R1 represents a hydrogen atom or a methyl group, and R2 represents a straight-chain or branched alkyl group with 4 to 30 carbon atoms.)

[0104] Specific examples of (meth)acrylate alkyl esters (a1) include, for instance, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, hexadecyl (meth)acrylate, behenyl (meth)acrylate, and other straight-chain alkyl esters of (meth)acrylate; (meth)acrylate Branched alkyl esters of methacrylates, including sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, isoamyl acrylate, neopentyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate, isostearyl acrylate, isoeicosyl acrylate, butyloctyl acrylate, isomyristyl acrylate, isocetyl acrylate, hexyldecyl acrylate, isostearyl acrylate, octyldecyl acrylate, octyldodecyl acrylate, isobenzene acrylate, etc., can be used alone or in combination of two or more.

[0105] From the viewpoint of achieving softness, linear alkyl esters of (meth)acrylate are preferred. Furthermore, from the viewpoint of achieving a balance between adhesion and softness, linear alkyl esters of (meth)acrylate with 4 to 20 carbon atoms, more preferably 5 to 18, particularly 6 to 16, and especially 7 to 14, are preferred. Examples include n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, and lauryl (meth)acrylate.

[0106] Furthermore, among these, from the viewpoint of being able to effectively form a cross-linked structure when irradiated by light, branched alkyl esters of (meth)acrylate are preferred, wherein the number of carbon atoms of the alkyl group is preferably 4 to 20, further 5 to 18, particularly 6 to 16, especially 7 to 14. For example, sec-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isoamyl methacrylate, neopentyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, isononyl methacrylate, and isodecanyl methacrylate are preferred.

[0107] The proportion of the structural units derived from alkyl methacrylate (a1) relative to 100% by mass of the structural units of the (meth)acrylate polymer (P1) is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, further preferably 15 to 85% by mass, and particularly preferably 20 to 80% by mass. When the proportion of structural units derived from alkyl methacrylate (a1) is above the aforementioned lower limit, there is a tendency for excellent flexibility and excellent conformability to uneven surfaces when the adhered material has an uneven surface. Furthermore, when the proportion of structural units derived from alkyl methacrylate (a1) is below the aforementioned upper limit, the effects of the copolymer monomers described later are easily obtained, and there is a tendency for excellent adhesive strength and cohesive strength.

[0108] [Carboxyl-containing monomer (a2)]

[0109] When (meth)acrylic polymers (P1) have structural units derived from carboxyl-containing monomers (a2), they become reaction sites with the crosslinking agent (C) described later, and tend to improve the adhesive strength of the adhesive sheet.

[0110] Examples of the aforementioned carboxyl-containing monomers (a2) include: (meth)acrylic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, etc. They can be one type or a combination of two or more.

[0111] When the aforementioned (meth)acrylic polymer (P1) has a structural unit derived from a carboxyl-containing monomer (a2), its content relative to 100% by mass of the structural unit of the (meth)acrylic polymer (P1) is typically 0.1 to 15% by mass, preferably 0.3 to 13% by mass, more preferably 0.5 to 10% by mass, and particularly preferably 1 to 6% by mass.

[0112] [Hydroxy monomer (a3)]

[0113] In the case where the aforementioned (meth)acrylic polymer (P1) has structural units derived from hydroxyl-containing monomers (a3), it becomes a reaction site with the crosslinking agent (C) described later, resulting in improved adhesive strength of the adhesive sheet and a tendency to suppress damp heat whitening.

[0114] Examples of hydroxyl-containing monomers (a3) ​​mentioned above include 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 2-hydroxyethyl methacrylate modified with caprolactone, diethylene glycol methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, polytetramethylene glycol methacrylate, and polyoxyethylene methacrylate. (Methacrylates) containing oxyalkylene structures, such as propylene glycol (meth)acrylates; (meth)acrylates containing primary hydroxyl groups, such as 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid; (meth)acrylates containing secondary hydroxyl groups, such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; (meth)acrylates containing tertiary hydroxyl groups, such as 2,2-dimethyl-2-hydroxyethyl (meth)acrylate; and vinyl ethers such as 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether. These can be used alone or in combination of two or more.

[0115] Among the aforementioned hydroxyl-containing monomers (a3), hydroxyl-containing monomers having 1 to 10, more specifically 1 to 6, and especially 2 to 4 carbon atoms, are preferred, such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, etc., and (meth)acrylates containing primary hydroxyl groups are particularly preferred, such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate.

[0116] In the case where the aforementioned (meth)acrylic polymer (P1) has structural units derived from hydroxyl-containing monomers (a3), from the viewpoint of imparting cohesive strength and resistance to damp heat whitening, the content of the structural units is typically 3 to 30% by mass, preferably 5 to 25% by mass, and particularly preferably 7 to 20% by mass, relative to 100% by mass of the structural units of the (meth)acrylic polymer (P1).

[0117] [Nitrogen-containing monomer (a4)]

[0118] When the aforementioned (meth)acrylic acid polymer (P1) has structural units derived from the nitrogen-containing monomer (a4), the cohesive strength of the adhesive sheet is improved, and the tendency for wet-heat whitening is suppressed. Furthermore, as a reaction site with the crosslinking agent (C) described later, the adhesive strength of the adhesive sheet is improved, and the tendency for wet-heat whitening is suppressed. Additionally, the nitrogen-containing monomer (a4) promotes the hydrogen abstraction reaction of the hydrogen-abstracting photoinitiator described later.

[0119] Examples of nitrogen-containing monomers (a4) mentioned above include: amino-containing monomers, amide-containing monomers, isocyanate-containing monomers, and (meth)acrylonitrile. They can be one type or a combination of two or more types.

[0120] Examples of amino-containing monomers mentioned above include: primary amino (meth)acrylates such as aminomethyl methacrylate and aminoethyl methacrylate; secondary amino (meth)acrylates such as tert-butylaminoethyl methacrylate and tert-butylaminopropyl methacrylate; tert-amino (meth)acrylates such as ethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminopropyl methacrylate, dimethylaminopropylacrylamide, etc.; N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazolium, vinyloxazole, vinylmorpholine, (meth)acryloylmorpholine, N-vinylacetamides, N-vinylcaprolactam, etc.

[0121] Examples of amide-containing monomers include (meth)acrylamide; N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-n-butyl (meth)acrylamide, diacetone (meth)acrylamide, N,N'-methylenebis(meth)acrylamide, and other N-alkyl (meth)acrylamides; N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-ethylmethylacrylamide, N,N-diallyl (meth)acrylamide, and other N,N-dialkyl (meth)acrylamides; N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and other hydroxyalkyl (meth)acrylamides; N-methoxymethyl (meth)acrylamide, N-(n-butoxymethyl)(meth)acrylamide, and other alkoxyalkyl (meth)acrylamides; maleimide or its derivatives, etc.

[0122] Examples of the aforementioned isocyanate-containing monomers include 2-(meth)acryloyloxyethyl isocyanate and their epoxide adducts. The aforementioned isocyanate groups can be protected by end-capping agents such as methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, and diethyl malonate.

[0123] Among these nitrogen-containing monomers (a4), from the viewpoint of being able to effectively form cross-linked structures, nitrogen-containing monomers having tertiary nitrogen atoms are preferred, such as tertiary amino (meth)acrylates, N,N-dialkyl (meth)acrylamide, N-vinylpyrrolidone, acryloylmorpholine, etc. are particularly preferred.

[0124] In the case where the aforementioned (meth)acrylic polymer (P1) has structural units derived from nitrogen-containing monomers (a4), from the viewpoint of imparting cohesion and resistance to damp heat whitening, the content of the structural units is typically 0.1 to 15% by mass, preferably 0.5 to 13% by mass, particularly preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass, relative to 100% by mass of the (meth)acrylic polymer (P1).

[0125] [Epoxy-containing monomer (a5)]

[0126] Examples of the aforementioned epoxy-containing monomers (a5) include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexyl methyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. They may be one or a combination of two or more.

[0127] When the aforementioned (meth)acrylic polymer (P1) has structural units derived from epoxy monomers (a5), the content of such units relative to 100% by mass of the structural units of the (meth)acrylic polymer (P1) is typically 0.1 to 10% by mass, preferably 0.3 to 13% by mass, particularly preferably 0.5 to 10% by mass, and especially preferably 1 to 6% by mass.

[0128] [Vinyl monomer (a6)]

[0129] As the aforementioned vinyl monomer (a6), compounds containing vinyl groups within their molecules can be cited as examples. Examples of such compounds include vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl laurate, and vinyl stearate, as well as aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrene. They can be one or a combination of two or more.

[0130] When the aforementioned (meth)acrylic polymer (P1) has structural units derived from vinyl monomers (a6), its content relative to 100% by mass of the structural units of the (meth)acrylic polymer (P1) is typically 1 to 40% by mass, preferably 5 to 35% by mass, more preferably 8 to 30% by mass, particularly preferably 10 to 25% by mass, and particularly preferably 2 to 7% by mass.

[0131] [alkyl (meth)acrylate monomers with 1 to 3 carbon atoms (a7)]

[0132] Alkyl methacrylate monomers (a7) having 1 to 3 carbon atoms as the aforementioned alkyl group include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate. They may be one type or a combination of two or more.

[0133] When the (meth)acrylic polymer (P1) has a structural unit of an alkyl methacrylate monomer (a7) with 1 to 3 carbon atoms derived from an alkyl group, from the viewpoint of imparting cohesive force to the adhesive sheet, the content of the structural unit is typically 0.1 to 15% by mass, preferably 0.5 to 13% by mass, particularly preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass, relative to 100% by mass of the structural unit of the (meth)acrylic polymer (P1).

[0134] [Alicyclic monomer (a8)]

[0135] Examples of the aforementioned alicyclic monomers (a8) include cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, and adamantane (meth)acrylate. They can be one or a combination of two or more.

[0136] When the (meth)acrylic polymer (P1) has structural units derived from alicyclic monomers (a8), from the viewpoint of imparting cohesive force to the adhesive sheet, the content of the structural units of the (meth)acrylic polymer (P1) is typically 0.1 to 15% by mass, preferably 0.5 to 13% by mass, particularly preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass, relative to 100% by mass of the structural units of the (meth)acrylic polymer (P1).

[0137] [Other comonomers (a9)]

[0138] Other comonomers mentioned above (a9) include, for example, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, butoxypolypropylene glycol (meth)acrylate, methoxypolytetramethylene glycol (meth)acrylate, butoxypolytetramethylene glycol (meth)acrylate, methoxypolyoxyethylene polyoxypropylene glycol (meth)acrylate, butoxypolyoxyethylene polyoxypropylene glycol (meth)acrylate, etc., which have an alkoxyalkylene glycol backbone, such as (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyl diethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol-polypropylene glycol-(meth)acrylate, nonylphenol ethylene oxide plus... Aromatic (meth)acrylates such as meth acrylates, 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone and mixtures thereof, (meth)acrylates with a benzophenone structure, heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, and macromonomers, etc.

[0139] When the aforementioned (meth)acrylic polymer (P1) has structural units derived from other comonomers (a9), its content relative to 100% by mass of the structural units of the (meth)acrylic polymer (P1) is typically 1 to 30% by mass, preferably 3 to 20% by mass, and more preferably 5 to 15% by mass.

[0140] For the aforementioned (meth)acrylic polymer (P1), if the (meth)acrylic polymer (P1) is a homopolymer, it can be obtained by homopolymerizing an alkyl methacrylic monomer. Alternatively, if the (meth)acrylic polymer (P1) is a copolymer, it can be obtained by polymerizing a copolymeric component comprising an alkyl (meth)acrylic ester (a1) having 3 to 20 carbon atoms and the aforementioned copolymeric monomers (a2) to (a9) that can copolymerize therewith.

[0141] Examples of the aforementioned polymerization methods include known methods such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. Among these, solution polymerization is preferred from the viewpoint of being able to safely and stably manufacture acrylic polymers (P1) with any monomer composition.

[0142] In this way, an acrylic polymer (P1) can be obtained.

[0143] Furthermore, the aforementioned (meth)acrylic polymer (P1) can incorporate photoactive sites, such as polymeric carbon-carbon double bond groups, into its side chains. This improves the crosslinking efficiency of the adhesive composition, enabling it to crosslink in a shorter time and thus increasing productivity.

[0144] As a method for introducing polymerizable carbon-carbon double bond groups into the side chain of the aforementioned (meth)acrylic polymer (P1), examples include: preparing the aforementioned copolymer containing a carboxyl-containing monomer (a2), a hydroxyl-containing monomer (a3), and a nitrogen-containing monomer (a4), and then subjecting the compound having functional groups and polymerizable carbon-carbon double bond groups capable of reacting with these functional groups to a condensation or addition reaction while maintaining the activity of the polymerizable carbon-carbon double bond groups.

[0145] Examples of combinations of these functional groups include epoxy (glycidyl) and carboxyl, amino and carboxyl, amino and isocyanate, epoxy (glycidyl) and amino, hydroxyl and epoxy, and hydroxyl and isocyanate. Among these combinations of functional groups, the combination of hydroxyl and isocyanate is preferred for ease of reaction control, and the combination of copolymer having hydroxyl and the aforementioned compound having isocyanate is more preferred.

[0146] Examples of isocyanate compounds having polymerizable carbon-carbon double bond groups include the aforementioned 2-(meth)acryloyloxyethyl isocyanate and their epoxide adducts.

[0147] From the viewpoint of improving adhesion and stress relaxation, the content of compounds having functional groups capable of reacting with the aforementioned functional groups and polymerizable carbon-carbon double bond groups is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 1 part by mass or less, and particularly preferably 0.1 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer. It should be noted that the lower limit is usually 0 parts by mass.

[0148] From the viewpoint of obtaining an adhesive composition with high cohesive strength, the weight-average molecular weight (Mw) of the (meth)acrylic polymer (P1) is preferably 200,000 or more, more preferably 300,000 or more, and even more preferably 400,000 or more.

[0149] Furthermore, from the viewpoint of operability and uniform stirring, the upper limit of the weight-average molecular weight (Mw) of the (meth)acrylic polymer (P1) is preferably 1.5 million or less, more preferably 1.2 million or less, even more preferably 1.1 million or less, and particularly preferably 1 million or less.

[0150] It should be noted that the weight-average molecular weight of the (meth)acrylic polymer (P1) is a value converted from standard polystyrene determined by gel permeation chromatography (GPC).

[0151] The content of (meth)acrylic polymer (P1) in the adhesive composition (adhesive sheet) is generally 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0152] [UV absorber (B)]

[0153] The aforementioned adhesive composition, by containing an ultraviolet absorber (B), is able to protect optical components susceptible to ultraviolet degradation from light-induced degradation.

[0154] In this embodiment, the ultraviolet absorber (B) includes an ultraviolet absorber (B-1) that has a large absorption at wavelengths of 300 to 360 nm and an ultraviolet absorber (B-2) other than the aforementioned (B-1) that has a large absorption at wavelengths of 350 to 420 nm. The ultraviolet absorber (B) is particularly preferably composed of only the ultraviolet absorber (B-1) and the ultraviolet absorber (B-2).

[0155] By combining ultraviolet absorbers (B-1) and (B-2), ultraviolet absorber (B-1), which has extremely high absorption in the wavelength range of 300–360 nm, can adequately ensure the ultraviolet absorption function of the adhesive sheet, while ultraviolet absorber (B-2), which has extremely high absorption in the wavelength range of 350–420 nm, can adequately absorb light in areas that do not affect the light emission of the organic light-emitting diode (OLED) (e.g., the region below 430 nm). As a result, ultraviolet-induced degradation of the OLED can be suppressed.

[0156] [UV absorber (B-1)]

[0157] Examples of UV absorbers (B-1) mentioned above include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, triazine-based UV absorbers, salicylic acid-based UV absorbers, and cyanoacrylate-based UV absorbers. These UV absorbers (B-1) can be used alone or in combination of two or more.

[0158] Examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone, 2-hydroxy-4-methoxy-5-sulfonic acid trihydrate benzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4-methoxybenzophenone. 4,4'-Tetrahydroxybenzophenone, 2,2'-Dihydroxy-4,4'-Dimethoxybenzophenone, 2,2'-Dihydroxy-4,4'-Dimethoxy-5-sodium sulfonate benzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, etc.

[0159] Examples of benzotriazole-based ultraviolet absorbers include 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)phenylbenzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol], 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, and 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole. 5-Di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2,2'-methylenebis(4-cumyl-6-benzotriazolephenyl), 2,2'-p-phenylenebis(1,3-benzoxazin-4-one), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidemethyl)-5-methylphenyl]benzotriazole, etc.

[0160] Examples of triazine-based ultraviolet absorbers include 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-ethoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-propoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-butoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, and 2-(2-hydroxy-4-octoxyphenyl)-4,6-diphenyl-1,3,5-triazine. 5-Triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-benzyloxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-[1-octoxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-... [-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-tetrazyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethylhexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-octyloxy-2-hydroxypropoxy)-5-α-cumyl] [Phenyl]-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-nonoxy-2-hydroxypropoxy)-5-α-cumylphenyl]-triazine, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-decoxy-2-hydroxypropoxy)-5-α-cumylphenyl]-triazine, 2,4-bis[4-(2-ethylhexyloxy)-2-hydroxyphenyl]-6-(4-methoxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-acryloyloxyethoxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, etc.

[0161] Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

[0162] Examples of cyanoacrylate-based ultraviolet absorbers include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate.

[0163] Among these ultraviolet absorbers (B-1), from the viewpoint of effectively suppressing light reaching the components of the image display device, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and triazine-based ultraviolet absorbers are preferred. Furthermore, from the viewpoint of excellent resistance to yellowing, benzophenone-based ultraviolet absorbers and triazine-based ultraviolet absorbers are more preferred, and 2,4-bis[4-(2-ethylhexyloxy)-2-hydroxyphenyl]-6-(4-methoxyphenyl)-1,3,5-triazine is particularly preferred.

[0164] Commercially available ultraviolet absorbers (B-1) include, for example, "TinosorbS" manufactured by BASF Japan and "KEMISORB111" manufactured by CHEMIPRO KASEI.

[0165] [UV absorber (B-2)]

[0166] As the aforementioned ultraviolet absorber (B-2), any compound that has great absorption at wavelengths of 350 to 420 nm, preferably at wavelengths exceeding 360 nm but below 420 nm, is acceptable, and there are no particular limitations.

[0167] Examples of UV absorbers (B-2) mentioned above include methylimine-based UV absorbers, indole-based UV absorbers, cinnamic acid-based UV absorbers, pyrimidine-based UV absorbers, and porphyrin-based UV absorbers. These UV absorbers (B-2) can be used alone or in combination of two or more.

[0168] Examples of the aforementioned methylimine-based ultraviolet absorbers include indoaniline, acetophenone methylimine, pyrazoloazomethine, imidazoleazomethine, imidazoazomethine, and pyridone methylimine.

[0169] Examples of indole-based ultraviolet absorbers include 5-indoleol, 4-aminoindole, and 4-methoxyindole.

[0170] Examples of cinnamic acid-based ultraviolet absorbers include ethylhexyl methoxycinnamate, isopropyl methoxycinnamate, isoamyl methoxycinnamate, diisopropyl methylcinnamate, and glyceryl dimethoxycinnamate.

[0171] Examples of pyrimidine-based ultraviolet absorbers include 2((2-(dibutylamino)-4-epoxy-6-methyl-5-pyrimidinyl)methylene)propanedionitrile.

[0172] Examples of porphyrin-based ultraviolet absorbers include: magnesium meso-tetra(4-sulfonic phenyl)porphyrin tetrasodium salt, octaethylporphyrin magnesium, tetra-trimethylpyrrolidone magnesium, octaethylporphyrin, tetra(2,6-dichlorophenyl)porphyrin, tetra(o-aminophenyl)porphyrin, tetra-trimethylpyrrolidone, tetraphenylporphyrin, octaethylporphyrin zinc, tetra-trimethylpyrrolidone zinc, tetraphenylporphyrin zinc, and deprotonated tetraphenylporphyrin.

[0173] Among these ultraviolet absorbers (B-2), from the viewpoint of effectively suppressing light reaching the components of the image display device, it is preferable to have a pyrimidine structure, i.e., a pyrimidine-based ultraviolet absorber, and particularly preferably 2((2-(dibutylamino)-4-epoxy-6-methyl-5-pyrimidinyl)methylene)propanedionitrile.

[0174] Commercially available products that are the aforementioned ultraviolet absorbers (B-2) include, for example, "FDB-009" manufactured by Yamada Chemical Industry Co., Ltd., and "BONASORB UA3912" manufactured by Orient Chemical Industry Co Ltd.

[0175] From the viewpoint of ultraviolet absorption, the content of the aforementioned ultraviolet absorber (B) relative to the adhesive composition (adhesive sheet) is preferably 0.1 to 20% by mass, more preferably 0.2 to 10% by mass, even more preferably 0.4 to 8% by mass, and particularly preferably 0.6 to 5% by mass.

[0176] Furthermore, from the viewpoint of ultraviolet absorption, the content ratio of ultraviolet absorber (B-1) to ultraviolet absorber (B-2) is 30:70 to 70:30 by mass, preferably 40:60 to 60:40, and particularly preferably 45:55 to 55:45.

[0177] [Cross-linking agent (C)]

[0178] In order to adjust the maximum values ​​of shear storage modulus, glass transition temperature (Tg), and loss tangent (tanδ) at low temperatures, the aforementioned adhesive composition preferably contains a crosslinking agent (C).

[0179] Examples of crosslinking agents (C) mentioned above include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, carbodiimide-based crosslinking agents, hydrazine-based crosslinking agents, amine-based crosslinking agents, peroxide-based crosslinking agents, metal chelate-based crosslinking agents, metal alkoxide-based crosslinking agents, metal salt-based crosslinking agents, and acrylic crosslinking agents. It should be noted that one or more of these agents can be used in combination.

[0180] In the case where the aforementioned crosslinking agent (C) is a thermal crosslinking agent that reacts with heat, the thermal crosslinking agent becomes a resin component (A1) by undergoing a crosslinking reaction with the aforementioned (meth)acrylic polymer (P1).

[0181] In addition, when the crosslinking agent (C) is a photocrosslinking agent that reacts with light, the photocrosslinking agent becomes a polymer by crosslinking with the aforementioned (meth)acrylic polymer (P1), and becomes a resin component (A1) containing the polymer.

[0182] Therefore, when the adhesive composition contains a crosslinking agent (C), the adhesive sheet formed from the adhesive composition contains a resin component (A) having structural units derived from the crosslinking agent (C).

[0183] Considering factors such as anti-aging properties and ease of adjusting the degree of crosslinking, the aforementioned crosslinking agent (C) preferably uses a crosslinking agent that has the property of being cured by irradiation with active energy rays.

[0184] It should be noted that "crosslinking" includes not only cases where polymer chains are crosslinked via chemical bonds, but also cases where crosslinking agents are crosslinked with each other via chemical bonds, and cases where (pseudo) crosslinking occurs through non-covalent bonds generated by interactions such as hydrogen bonds, electrostatic interactions, and van der Waals forces within or between polymer chains.

[0185] From the viewpoint that the aforementioned crosslinking agent (C) can easily form a crosslinked structure by irradiation with active energy rays, a compound having an olefinic unsaturated group within the molecule is preferred, and (meth)acrylates are particularly preferred. That is, an acrylic crosslinking agent is preferred as the aforementioned crosslinking agent (C).

[0186] [Acrylic crosslinking agent]

[0187] The glass transition temperature of the aforementioned acrylic crosslinking agent, as determined by the Fox formula, is preferably below -20°C, more preferably below -30°C, further preferably below -35°C, and particularly preferably below -40°C. It should be noted that the lower limit of the glass transition temperature is typically -80°C.

[0188] By giving the acrylic crosslinking agent a glass transition temperature within the aforementioned range, there is a tendency to easily adjust the glass transition temperature of this adhesive sheet to below -20°C. Furthermore, by using the aforementioned acrylic crosslinking agent, there is a tendency to reduce the shear storage modulus at low temperatures (e.g., -20°C) and easily adjust it to the desired viscoelastic behavior.

[0189] Furthermore, from the viewpoint of adhesive properties, acrylic crosslinking agents typically have 1 to 20 olefinic unsaturated groups in their molecules, preferably 1 to 10, more preferably 1 to 6, and particularly preferably 1 to 3.

[0190] From the viewpoint of imparting excellent impact resistance, the aforementioned acrylic crosslinking agent preferably has an oxyalkylene structure.

[0191] Examples of acrylic crosslinking agents include monofunctional (meth)acrylate monomers, polyfunctional (meth)acrylate monomers, and polyfunctional (meth)acrylate oligomers. Among these, polyfunctional (meth)acrylate oligomers are preferred.

[0192] (Monofunctional (meth)acrylate monomer)

[0193] By including monofunctional (meth)acrylates in the adhesive composition, the molecular weight between crosslinking points during the curing of the adhesive composition can be increased, thus increasing the degree of freedom of molecular chain movement and making it easier to obtain adhesive sheets with excellent stress relaxation properties.

[0194] Examples of the aforementioned monofunctional (meth)acrylate monomers include, for example, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isododecyl (meth)acrylate, tetradecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and behenyl (meth)acrylate. Cyclopropyl methacrylate, cyclobutyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate, cyclononyl methacrylate, cyclodecyl methacrylate, isobornyl methacrylate, norbornyl methacrylate, adamantyl methacrylate, tricyclodecanediethanol acrylate, ethoxylated o-phenylphenol acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, methoxy polyethylene glycol (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, phenoxy diethylene glycol (Meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, 2-hydroxy-o-phenylphenol propyl acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl tetrahydrophthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate, (meth)benzyl acrylate, (meth)acrylic acid phenoxyethyl acrylate, phenoxyethylene glycol (meth)acrylate, (meth)acrylic acid 2-naphthyl acrylate, (meth)acrylic acid 9-anthrayl acrylate, (meth)acrylic acid 1-pyrene methyl ester, tricyclodecane Dimethylol monoacrylate monocarboxylic acid, dicyclopentyl acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, glycerol mono(meth)acrylate, pentaerythritol mono(meth)acrylate, diglycerol mono(meth)acrylate, bis(trimethylolpropane) mono(meth)acrylate, dipentaerythritol mono(meth)acrylate, ethoxylated trimethylolpropane mono(meth)acrylate, propoxylated trimethylolpropane mono(meth)acrylate, ethoxylated glycerol mono(meth)acrylate, propoxylated glycerol mono(meth)acrylateEthoxylated pentaerythritol mono(meth)acrylate, propoxylated pentaerythritol mono(meth)acrylate, ethoxylated bis(trimethylolpropane) mono(meth)acrylate, propoxylated bis(trimethylolpropane) mono(meth)acrylate, epoxy-modified diglycerol mono(meth)acrylate, and epoxy-modified dipentaerythritol mono(meth)acrylate, as well as monofunctional oligomers such as monofunctional urethane (meth)acrylates, monofunctional epoxy (meth)acrylates, and monofunctional polyester (meth)acrylates. They can be used alone or in combination of two or more.

[0195] (Multifunctional (meth)acrylate monomers)

[0196] Examples of the aforementioned multifunctional (meth)acrylate monomers include, for example, 1,4-butanediol di(meth)acrylate, glycerol di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerol glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecanediethanol di(meth)acrylate, bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl(meth)acrylate, ε-caprolactone-modified tri(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and propoxylated pentaerythritol tri(meth)acrylate. Ethoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, neopentyl glycol di(meth)acrylate of hydroxypentanoic acid, di(meth)acrylate of ε-caprolactone adduct of neopentyl glycol hydroxypentanoic acid, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, bis(trimethylolpropane tetra(meth)acrylate, etc.

[0197] From the viewpoint of imparting softness and moderate toughness to the adhesive sheet and improving adhesion, polyfunctional (meth)acrylates with an alkylene glycol backbone, such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate, are more preferred.

[0198] From the viewpoint of imparting appropriate flexibility to the adhesive sheet, the molecular weight of the aforementioned polyfunctional (meth)acrylate monomer is preferably 200 or more, more preferably 300 or more, further preferably 400 or more, and particularly preferably 500 or more. The upper limit of the molecular weight of the polyfunctional (meth)acrylate monomer is generally 3000 or less, preferably 2000 or less.

[0199] (Multifunctional (meth)acrylate oligomers)

[0200] Examples of the aforementioned multifunctional (meth)acrylate oligomers include polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, and polyether (meth)acrylates. Among these, from the viewpoint of imparting excellent impact resistance, those having an oxyalkylene structure are preferred, and from the viewpoint of imparting excellent adhesion and impact resistance, urethane (meth)acrylates are preferred.

[0201] The aforementioned urethane (meth)acrylate can be obtained by reacting a polyol, a polyisocyanate, and a hydroxyl-containing (meth)acrylate.

[0202] As for the aforementioned polyols, any compound having two or more hydroxyl groups is acceptable, such as aliphatic polyols, alicyclic polyols, polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic acid polyols, polysiloxane polyols, etc.

[0203] The aforementioned polyols may be used in combination of one or more types.

[0204] Examples of aliphatic polyols include: ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, pentaerythritol diacrylate, 1,9-nonanediol, 2-methyl-1,8-octanediol, and other aliphatic alcohols containing two hydroxyl groups; sugar alcohols such as xylitol and sorbitol; and aliphatic alcohols containing three or more hydroxyl groups such as glycerol, trimethylolpropane, and trimethylolethane.

[0205] Examples of alicyclic polyols include cyclohexanediol, cyclohexyldiethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecanediethanol.

[0206] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutane glycol, polypentamethylene glycol, polyhexamethylene glycol, and other polyether polyols containing alkylene structures, as well as random or block copolymers of these polyalkylene glycols.

[0207] Examples of polyester-based polyols include condensation polymers of polyols and polycarboxylic acids, ring-opening polymers of cyclic esters (lactones), and reactants obtained from polyols, polycarboxylic acids, and cyclic esters.

[0208] Examples of the aforementioned polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene glycol, 1,3-tetramethylene glycol, 2-methyl-1,3-trimethylene glycol, 1,5-pentamethylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, 3-methyl-1,5-pentamethylene glycol, 2,4-diethyl-1,5-pentamethylene glycol, glycerol, trimethylolpropane, trimethylolethane, cyclohexanediols (1,4-cyclohexanediol, etc.), bisphenols (bisphenol A, etc.), and sugar alcohols (xylitol, sorbitol, etc.).

[0209] Examples of the aforementioned polycarboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, and dodecanoic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, terephthalic acid, and trimellitic acid.

[0210] Examples of the aforementioned cyclic esters include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

[0211] Examples of polycarbonate-based polyols include, for example, reactants of polyols with phosgene, and ring-opening polymers of cyclic carbonates (alkylene carbonates, etc.).

[0212] Examples of the aforementioned polyols include the polyols exemplified in the description of the aforementioned polyester polyols, and examples of the aforementioned alkylene carbonates include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0213] It should be noted that polycarbonate-based polyols are compounds that have carbonate bonds in the molecule and hydroxyl groups at the end; they can have both carbonate bonds and ester bonds.

[0214] Examples of polyolefin polyols include those that have homopolymers or copolymers of ethylene, propylene, butene, etc., as a saturated hydrocarbon backbone and have hydroxyl groups at their molecular ends.

[0215] Examples of polybutadiene-based polyols include those with butadiene copolymers as the hydrocarbon backbone and hydroxyl groups at the molecular ends.

[0216] The aforementioned polybutadiene polyols can also be hydrogenated polybutadiene polyols in which all or part of the olefinic unsaturated groups contained in their structure have been hydrogenated.

[0217] Examples of polyisoprene-based polyols include those with isoprene copolymers as the hydrocarbon backbone and hydroxyl groups at the molecular ends.

[0218] The aforementioned polyisoprene polyols can also be hydrogenated polyisoprene polyols in which all or part of the olefinic unsaturated groups contained in their structure have been hydrogenated.

[0219] Examples of (meth)acrylic polyols include those having at least two hydroxyl groups in the molecule of a polymer or copolymer of alkyl methacrylates. Examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate.

[0220] Examples of polysiloxane-based polyols include dimethyl polysiloxane polyol and methylphenyl polysiloxane polyol.

[0221] From the viewpoint of obtaining excellent impact resistance, polyether-based polyols are preferred, with polyethylene glycol, polypropylene glycol, and polytetramethylene glycol being the most preferred.

[0222] As for the aforementioned polyisocyanates, any compound having two or more isocyanate groups is acceptable. Examples include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, phenylenediamine diisocyanate, tetramethylphenylenediamine diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic polyisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated phenylenediamine diisocyanate, isophorone diisocyanate, and norbornene diisocyanate; or trimer or polymeric compounds of these polyisocyanates; urea-formate type polyisocyanates; biuret type polyisocyanates; and water-dispersible polyisocyanates.

[0223] The aforementioned polyisocyanates may be used in combination of one or more.

[0224] Among these, from the perspective of stability during the carbamate reaction, diisocyanates are preferred, and more preferably aliphatic diisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, as well as alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated phenylmethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis(isocyanate methyl)cyclohexane. From the perspective of low curing shrinkage, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated phenylmethylene diisocyanate, and norbornene diisocyanate are even more preferred. From the perspective of excellent reactivity and versatility, hydrogenated diphenylmethane diisocyanate, hydrogenated phenylmethylene diisocyanate, and isophorone diisocyanate are particularly preferred.

[0225] The aforementioned hydroxyl-containing (meth)acrylates are compounds having hydroxyl and (meth)acryloyl groups, preferably having 1 to 5 hydroxyl groups, and particularly preferably 1.

[0226] Examples of hydroxyl-containing (meth)acrylates include, for instance, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethylacryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol mono(meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate. Hydroxyl methacrylates containing one methacryloyl group, such as dimethyl cyclohexyl mono(meth)acrylate and hydroxycaprolactone (meth)acrylate; hydroxyl methacrylates containing two methacryloyl groups, such as glycerol di(meth)acrylate and 2-hydroxy-3-acryloyloxypropyl methacrylate; hydroxyl methacrylates containing three or more methacryloyl groups, such as pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified dipentaerythritol penta(meth)acrylate.

[0227] They can be used in one type or in combination of two or more types.

[0228] Preferably, hydroxyl-containing (meth)acrylates containing two or fewer (meth)acryloyl groups are preferred, more preferably compounds containing one (meth)acryloyl group such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, dimethyl cyclohexyl mono(meth)acrylate, and hydroxycaprolactone (meth)acrylate, and particularly preferably hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

[0229] Among the aforementioned urethane (meth)acrylates obtained by reacting polyols, polyisocyanates, and hydroxyl-containing (meth)acrylates, from the viewpoint of low glass transition temperature, improved loss tangent (Tanδ), and excellent impact resistance, polyfunctional urethane (meth)acrylates with an oxyalkylene structure are preferred, more preferably polyfunctional urethane (meth)acrylates with a polypropylene glycol backbone, and even more preferably polyfunctional urethane (meth)acrylates obtained by reacting 2-hydroxyethyl acrylate, isophorone diisocyanate, and polypropylene glycol diacrylate.

[0230] From the perspective of obtaining an adhesive sheet with moderate flexibility, the weight-average molecular weight of the aforementioned polyfunctional (meth)acrylate oligomer is preferably 1000 or more, more preferably 3000 or more, further preferably 5000 or more, particularly preferably 8000 or more, and particularly preferably 10000 or more. It should be noted that the upper limit of this molecular weight is usually 100000, and preferably 50000.

[0231] The content of the crosslinking agent (C) is typically 1 to 50 parts by mass relative to 100 parts by mass of the aforementioned (meth)acrylic polymer (P1), preferably 2 to 40 parts by mass, more preferably 3 to 35 parts by mass, and particularly preferably 5 to 30 parts by mass. By keeping the content of the crosslinking agent (C) within the aforementioned range, there is a tendency to reduce the shear storage modulus at low temperatures, increase the maximum value of the loss tangent (tanδ), and adjust to the desired viscoelasticity.

[0232] Furthermore, the adhesive sheet preferably contains 1 to 50% by mass of structural units derived from the crosslinking agent (C), more preferably 2 to 40% by mass, even more preferably 3 to 35% by mass, and particularly preferably 5 to 30% by mass. By setting the structural units derived from the crosslinking agent (C) within the aforementioned range, there is a tendency to reduce the shear storage modulus at low temperatures, increase the maximum value of the loss tangent (tanδ), and adjust to the desired viscoelasticity.

[0233] [Photoinitiator (D)]

[0234] The aforementioned adhesive composition preferably further contains a photoinitiator (D).

[0235] The aforementioned photoinitiator (D) is a compound that generates free radicals through active energy rays. Examples include compounds that generate active free radicals when irradiated with ultraviolet light, visible light, or more specifically, light with wavelengths of 200 to 780 nm. From the viewpoint of photoreactivity, photoinitiators with absorption at wavelengths of 405 nm or higher are preferred, and photoinitiators with a molar absorptivity of 30 (L / mol·cm) or higher at a wavelength of 405 nm are particularly preferred.

[0236] One photoinitiator (D) may be used or two or more may be used in combination.

[0237] The aforementioned photoinitiators (D) are broadly classified into two categories based on their free radical generation mechanisms. More specifically, they are roughly divided into cleavage-type photoinitiators, which can generate free radicals by breaking down the single bonds of the photoinitiator itself, and hydrogen-abstraction-type photoinitiators, which can generate free radicals by abstracting hydrogen from the hydrogen donor in the system through the excited photoinitiator.

[0238] The aforementioned photoinitiator (D) can be any of the cleavage-type photoinitiators and hydrogen-abstraction-type photoinitiators, and in particular, from the viewpoint of having high photosensitivity, cleavage-type photoinitiators are preferred.

[0239] On the other hand, hydrogen-abstracting photoinitiators are preferred in that they do not generate photodecomposition products like those of pyrolysis photoinitiators. Furthermore, hydrogen-abstracting photoinitiators also undergo hydrogen abstraction reactions from the (meth)acrylic polymer (P1), allowing the (meth)acrylic polymer (P1) to enter the cross-linked structure; therefore, they are also preferred from the viewpoint of easily forming a cross-linked structure with many cross-linking points.

[0240] The aforementioned hydrogen-abstracting photoinitiators can be broadly classified into intermolecular hydrogen-abstracting photoinitiators that abstract hydrogen from other molecules and intramolecular hydrogen-abstracting photoinitiators that also induce hydrogen-abstracting reactions within the same molecule.

[0241] Examples of specific hydrogen-abstracting photoinitiators mentioned above include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, methyl 2-benzoylbenzoate, 4-[(4-methylphenyl)thio]benzophenone, 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, and 4-methacryloyloxybenzophenone. Intermolecular hydrogen-abstracting photoinitiators include methyl benzoate, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, and 4-methacryloyloxyethoxy-4'-bromobenzophenone; and intramolecular hydrogen-abstracting photoinitiators include methyl benzoylformate, 2-(2-oxo-2-phenyl-acetoxy-ethoxy)ethyl oxyphenylacetate, 2-(2-hydroxy-ethoxy)ethyl oxyphenylacetate, and dimethyl 2,2'-(thiobis(4,1-phenylene))bis(2-octanoic acid ester).

[0242] Among them, the preferred absorbers are methyl benzoylformate, 2-(2-oxo-2-phenyl-acetoxy-ethoxy)ethyl ester, 2-(2-hydroxy-ethoxy)ethyl ester, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, and dimethyl 2,2'-(thiobis(4,1-phenylene))bis(2-octanoic acid ester).

[0243] In addition, intramolecular hydrogen-abstracting photoinitiators such as methyl benzoylcarbamate, 2-(2-oxo-2-phenyl-acetoxy-ethoxy)ethyl oxyphenylacetate, 2-(2-hydroxy-ethoxy)ethyl oxyphenylacetate, and dimethyl 2,2'-(thiobis(4,1-phenylene))bis(2-octanoic acid ester) are preferred in that they are not only hydrogen donors in the system, but also serve as the starting point for free radical generation.

[0244] Examples of pyrolysis-type photoinitiators include benzoylacetyl ketal photoinitiators such as 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propanoyl)benzyl}phenyl]-2-methyl-propane-1-one, α-hydroxyacetophenone-based photoinitiators such as oligomeric (2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), and 2-benzyl-2-dimethylacetophenone. α-aminoacetophenone photoinitiators such as methylamino-1-(4-morpholinophenyl)butane-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide, and their derivatives.

[0245] Among these, α-aminoacetophenone-based initiators such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, as well as phosphine oxide-based initiators such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide are preferred from the perspective of decomposition and decolorization after the photoreaction.

[0246] When the aforementioned adhesive composition (adhesive sheet) contains a photoinitiator (D), its content relative to 100 parts by weight of the (meth)acrylic polymer (P1) is typically 0.1 to 5 parts by weight, preferably 0.2 to 4 parts by weight, and particularly preferably 0.3 to 3 parts by weight. If the content of the photoinitiator (D) is within this range, there is a tendency for a good crosslinking reaction to occur.

[0247] [Other ingredients]

[0248] The aforementioned adhesive composition may contain, as needed, various additives such as silane coupling agents, plasticizers, tackifying resins, antioxidants, light stabilizers, metal passivators, anti-aging agents, hygroscopic agents, rust inhibitors, and inorganic particles as "other ingredients" without impairing the effects of the present invention.

[0249] In addition, depending on the needs, reaction catalysts such as tertiary amine compounds, quaternary ammonium compounds, and tin lauryl compounds may also be included.

[0250] They can be used individually or in combination of two or more.

[0251] [Silane coupling agent]

[0252] The aforementioned silane coupling agent is an organosilicon compound containing one or more reactive functional groups and one or more alkoxy groups bonded to silicon atoms in its structure. Examples of the aforementioned reactive functional groups include epoxy, (meth)acryloyl, mercapto, hydroxyl, carboxyl, amino, amide, and isocyanate groups. Among these, epoxy and mercapto groups are preferred from the perspective of balancing durability.

[0253] From the viewpoint of durability and storage stability, alkoxy groups containing 1 to 8 carbon atoms are preferred as the aforementioned alkoxy groups bonded to silicon atoms, and methoxy and ethoxy groups are particularly preferred. It should be noted that silane coupling agents may also have reactive functional groups and organic substituents other than the alkoxy group bonded to silicon atoms, such as alkyl or phenyl groups.

[0254] Specific examples of silane coupling agents include monomeric epoxy-containing silane coupling agents of silane compounds such as 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. These coupling agents are formed by the partial hydrolysis and condensation of the aforementioned silane compounds, or by the reaction of the aforementioned silane compounds with methyltriethoxysilane, ethyltriethoxysilane, or methyl... Oligomeric epoxy-containing silane coupling agents are silane compounds co-condensed with alkyl silane compounds such as trimethoxysilane and ethyltrimethoxysilane; monomeric mercaptosilane coupling agents are silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, and 3-mercaptopropylmethyldimethoxysilane, which are formed by hydrolysis and polycondensation of a portion of the aforementioned silane compounds, or by reacting the aforementioned silane compounds with methyltriethoxysilane, ethyltriethoxysilane, and methyltriethoxysilane. Oligomeric mercaptosilane coupling agents containing thiol groups, formed by the co-condensation of alkyl silane compounds such as methyltrimethoxysilane and ethyltrimethoxysilane; silane coupling agents containing (meth)acryloyl groups, such as 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, and 3-acryloyloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane... Amino-containing silane coupling agents include methoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; isocyanate-containing silane coupling agents include 3-isocyanate-propyltriethoxysilane; and vinyl-containing silane coupling agents include vinyltrimethoxysilane and vinyltriethoxysilane.

[0255] They can be used individually or in combination of two or more.

[0256] From the perspective of excellent durability, epoxy-containing silane coupling agents and mercapto-containing silane coupling agents are preferred, with epoxy-containing silane coupling agents being particularly preferred.

[0257] When the aforementioned adhesive composition (adhesive sheet) contains a silane coupling agent, its content is typically 0.005 to 10 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer (P1), preferably 0.01 to 5 parts by weight, and particularly preferably 0.05 to 1 part by weight. When the content of this silane coupling agent is above the aforementioned lower limit, there is a tendency for improved durability; when it is below the aforementioned upper limit, there is a tendency for improved durability.

[0258] [Plasticizer]

[0259] To impart flexibility to the adhesive sheet, the aforementioned adhesive composition may contain a plasticizer.

[0260] As for the aforementioned plasticizer, there is no particular limitation, for example, substances selected from the group consisting of polyisobutylene, polyisoprene, polybutadiene, amorphous polyolefins and their copolymers, organosilicon, polyacrylates, oligomeric polyurethanes, ethylene-propylene copolymers, and any combination or mixture thereof.

[0261] The preferred plasticizer is polyisobutylene.

[0262] Examples of polyisobutylene include, for instance, substances selected from the OPPANOLB series, particularly those commercially available from BASF under the trade name OPPANOL.

[0263] From an environmental protection perspective, the lower the volatile organic compound (VOC) value of the aforementioned plasticizer, the better; typically less than 1000 ppm, preferably less than 800 ppm, more preferably less than 600 ppm, and particularly preferably 400 ppm. It should be noted that the aforementioned VOC value can be determined by thermogravimetric analysis.

[0264] When the aforementioned adhesive composition (adhesive sheet) contains a plasticizer, its content is not particularly limited, and is typically 0.1 to 20 parts by weight, preferably 0.5 to 15 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer (P1).

[0265] [Tackifier]

[0266] To improve the adhesion of this adhesive sheet, the aforementioned adhesive composition may contain a tackifier.

[0267] Examples of the aforementioned tackifiers include: terpene resins such as polyterpenes (e.g., α-pinene resins, β-pinene resins, and limonene resins), aromatic modified polyterpene resins (e.g., phenol-modified polyterpene resins), coumarone-indene resins, C5 hydrocarbon resins, C9 hydrocarbon resins, C5 / C9 hydrocarbon resins, and dicyclopentadiene resins, as well as rosin-based resins such as modified rosin, hydrogenated rosin, polymerized rosin, and rosin esters.

[0268] When the aforementioned adhesive composition (adhesive sheet) contains a tackifier, its content is not particularly limited, and is typically 0.1 to 20 parts by weight, preferably 0.5 to 15 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer (P1).

[0269] Rust Inhibitor

[0270] To prevent corrosion when the adhered material contains corrosive parts such as metal wiring, the aforementioned adhesive composition may contain a rust inhibitor.

[0271] Examples of rust inhibitors mentioned above include triazoles and benzotriazoles.

[0272] When the aforementioned adhesive composition (adhesive sheet) contains a rust inhibitor, its content is typically 0.01 to 5 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer (P1), preferably 0.1 to 3 parts by weight.

[0273] [Method for manufacturing this adhesive sheet based on the first method]

[0274] Next, the manufacturing method of this adhesive sheet based on the first method will be described.

[0275] However, the following description is an example of a method for manufacturing this adhesive sheet, and this adhesive sheet is not limited to adhesive sheets manufactured by this method.

[0276] In the manufacture of this adhesive sheet, the above-mentioned adhesive composition is prepared, the adhesive composition is shaped into a sheet, cured by irradiation with active energy rays, and appropriate processing is carried out as needed to manufacture this adhesive sheet.

[0277] Alternatively, in the fabrication of this adhesive sheet, the adhesive composition for forming the adhesive sheet can be prepared in the same manner as described above, applied to a component of an image display device, and cured to form the adhesive sheet. However, this method is not the only option.

[0278] When preparing the adhesive composition for forming this adhesive sheet, the aforementioned components can be mixed using a propeller mixer or a mixing machine (e.g., a single-screw extruder, a twin-screw extruder, a planetary mixer, a twin-screw mixer, a pressure kneader, etc.).

[0279] It should be noted that when mixing various components, various additives such as silane coupling agents and antioxidants can be pre-mixed with (meth)acrylic polymer (P1) and then supplied to the mixer or kneader, or all materials can be pre-melted and mixed before supplying, or a masterbatch can be made by pre-concentrating the additives in (meth)acrylic polymer (P1) and then supplied.

[0280] Known methods can be used to form the adhesive composition into a sheet, such as wet lamination, dry lamination, extrusion casting using a T-die, extrusion lamination, calendering, blow molding, injection molding, and liquid injection curing. Among these, wet lamination, extrusion casting, and extrusion lamination are preferred when manufacturing sheets.

[0281] In addition, the adhesive composition can be cured by irradiation with active energy rays. The adhesive sheet can be manufactured by irradiating a molded body of the adhesive composition, such as a sheet, with active energy rays. It should be noted that, in addition to irradiation with active energy rays, heating can also be used to further cure the adhesive composition.

[0282] There are no particular limitations on the irradiation energy, irradiation time, irradiation method, etc. of the aforementioned active energy rays, as long as they can activate the photoinitiator (D) and cause the monomer components to polymerize.

[0283] Examples of active energy rays used in the aforementioned active energy irradiation include far-ultraviolet, ultraviolet, near-ultraviolet, infrared, visible light, X-rays, alpha rays, beta rays, gamma rays, electron beams, proton rays, neutron rays, and other ionizing radiation. From the viewpoint of suppressing damage to the components of the image display device and facilitating reaction control, ultraviolet or visible light is preferred. Furthermore, considering factors such as curing speed, ease of obtaining the irradiation device, and cost, curing using ultraviolet or visible light irradiation is advantageous.

[0284] From the viewpoint of preventing curing obstacles caused by ultraviolet absorbers, curing is preferably performed using visible light, such as active energy rays at 405 nm.

[0285] Examples of light sources that emit light in the 150-450nm wavelength range include high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, electrodeless discharge lamps, and LEDs.

[0286] From a curing perspective, the preferred irradiation dose (cumulative light intensity) is 10~6000 mJ / cm². 2 More preferably 50~5500mJ / cm 2 Further optimization of 100~5000mJ / cm 2 200~4000mJ / cm² is particularly preferred. 2 Especially preferred is 300~3000mJ / cm 2 Furthermore, when active energy rays are irradiated from both sides of the adhesive sheet, the irradiation amount of the aforementioned active energy rays is the sum of the cumulative energy on one side and the cumulative energy on the other side.

[0287] This adhesive sheet can also be cured by active energy rays. "The adhesive sheet is cured by active energy rays" means that the adhesive sheet has the property of being cured by active energy rays; in other words, it means that the adhesive sheet leaves room for curing by active energy rays.

[0288] That is, the adhesive sheet can be an adhesive sheet that has been cured (hereinafter also referred to as "one-time curing") to a state that leaves room for the adhesive composition to be cured by active energy rays, or it can be an adhesive sheet in which the adhesive composition has been pre-crosslinked with a thermal crosslinking agent (one-time curing) and can be cured by active energy rays.

[0289] When this adhesive sheet is cured once, it can be cured by heat or by active energy rays. From the viewpoint of easily controlling the gel fraction within a specified range, the adhesive sheet cured once by irradiation with active energy rays is preferred.

[0290] When this adhesive sheet has the property of being curable by active energy rays, that is, when it is an adhesive sheet that allows for curing by active energy rays, and when this adhesive sheet is cured once by active energy rays, for example, the cumulative irradiation dose at a wavelength of 405 nm is typically set to 10~5000 mJ / cm. 2 The optimal value is set at 50~4000mJ / cm. 2 A more preferred setting is 100~3000mJ / cm 2 Further optimization is set at 200~2500mJ / cm 2 The optimal value is set at 300~2000mJ / cm². 2 That's fine. If the irradiation dose is within the aforementioned range, there is a tendency to adjust the degree of curing while allowing for some curing leeway.

[0291] Alternatively, as another embodiment of the manufacturing method of this adhesive sheet, the adhesive composition can be dissolved in a suitable solvent and various coating methods can be used.

[0292] For example, the adhesive composition can be dissolved in a solvent, coated onto a release film, dried, and cured by irradiation with active energy rays to form the adhesive sheet. Alternatively, the release film can be laminated as needed. In this case, it can be coated onto the release film, dried, cured by irradiation with active energy rays, and then laminated on top. Alternatively, it can be coated onto the release film, dried, laminated, and then cured by irradiation with active energy rays to form the adhesive sheet.

[0293] As the solvent, there are no particular limitations on any solvent that dissolves the adhesive composition. Examples include ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic solvents such as toluene and xylene; and alcohol solvents such as methanol, ethanol, and propanol. These solvents can be used alone or in combination of two or more. Among these, considering solubility, drying properties, and price, ethyl acetate, acetone, methyl ethyl ketone, and toluene are preferred, with ethyl acetate being particularly preferred.

[0294] Regarding the solvent content, considering drying properties, it is preferably 600 parts by weight or less, more preferably 500 parts by weight or less, even more preferably 400 parts by weight or less, and particularly preferably 300 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer (P1). On the other hand, it is preferably 1 part by weight or more, more preferably 50 parts by weight or more, even more preferably 100 parts by weight or more, and particularly preferably 150 parts by weight or more.

[0295] As for coating methods, conventional methods such as roller coating, die coating, gravure coating, comma coating, screen printing, and bar coating can be used.

[0296] Examples of drying methods include drying with a dryer, drying with heated rollers, and drying by blowing hot air onto the film. Among these, a dryer is preferred for its ability to dry evenly and easily. These methods can be used individually or in combination of two or more.

[0297] The drying temperature is typically 40~150°C, more preferably 45~140°C, even more preferably 50~130°C, and particularly preferably 55~120°C. Within the aforementioned temperature range, thermal deformation of the release film can be suppressed, and the solvent can be removed efficiently and safely.

[0298] The drying time is typically 1 to 30 minutes, more preferably 3 to 25 minutes, and even more preferably 5 to 20 minutes. Within the aforementioned time range, the solvent can be effectively and sufficiently removed.

[0299] The solvent content in the aforementioned dried adhesive composition is preferably 1% by mass or less, more preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less, and most preferably 0% by mass.

[0300] In addition, the adhesive sheet may be a single-layer sheet containing only an adhesive layer formed by an adhesive composition, or it may be a multi-layer sheet having multiple adhesive layers formed by an adhesive composition stacked on top of each other.

[0301] <Adhesive sheet with release film>

[0302] This adhesive sheet can also be provided as an adhesive sheet with a release film (adhesive sheet laminate) by laminating a release film on one or both sides of an adhesive layer (this adhesive sheet) formed by an adhesive composition.

[0303] When release films are provided on both sides of the adhesive sheet, it is preferable to construct a laminate consisting of a light release film with relatively low peel strength and a heavy release film with relatively high peel strength.

[0304] When using an adhesive sheet with release films on both sides, firstly, one release film (light peel film) is peeled off to expose one side of the adhesive sheet, and then it is bonded to a component of the image display device (designated as the first component). Then, the other side of the adhesive sheet, exposed by peeling off the other release film (heavy peel film), is bonded to a component of the flexible image display device (designated as the second component).

[0305] As the release film, a known release film may be appropriately used.

[0306] As a material for the release film, materials such as release papers or release agents made by coating polyester film, polyolefin film, polycarbonate film, polystyrene film, acrylic film, cellulose triacetate film, and fluoropolymer film with a release agent such as silicone resin can be appropriately selected. Among these, polyester film is preferred from the viewpoint of excellent transparency, mechanical strength, heat resistance, and flexibility, and polyethylene terephthalate (PET) film, especially biaxially stretched PET film, is even more preferred. A release film in which a release layer formed by curing a silicone-based release agent with silicone resin as the main component is provided on the aforementioned substrate can also be used.

[0307] There is no particular limitation on the thickness of the release film. However, from the viewpoint of processability and operability, it is preferably 10 to 250 μm, more preferably 25 to 200 μm, and even more preferably 35 to 190 μm.

[0308] <Second Method>

[0309] In the second method, the adhesive sheet is obtained from a slurry composition containing slurry components and ultraviolet absorber (B).

[0310] The components contained in the aforementioned slurry composition are described below.

[0311] [Slurry Composition]

[0312] The aforementioned slurry composition preferably includes a monomer component, which includes: alkyl (meth)acrylate (a1); and a copolymerizable monomer selected from one or more of the following: carboxyl-containing monomer (a2), hydroxyl-containing monomer (a3), nitrogen-containing monomer (a4), epoxy-containing monomer (a5), vinyl monomer (a6), alkyl (meth)acrylate monomer (a7) with 1 to 3 carbon atoms in the alkyl group, alicyclic monomer (a8), and other copolymerizable monomers (a9).

[0313] Among the aforementioned copolymeric monomers (a2) to (a9), carboxyl-containing monomers (a2), hydroxyl-containing monomers (a3), and nitrogen-containing monomers (a4) are particularly preferred.

[0314] Furthermore, it is particularly preferred that the product does not contain the aforementioned carboxyl-containing monomer (a2) but contains any one of the hydroxyl-containing monomer (a3) ​​or the nitrogen-containing monomer (a4). By containing any one of the hydroxyl-containing monomer (a3) ​​or the nitrogen-containing monomer (a4), it is possible to combine the corrosion resistance, adhesion, and resistance to damp heat whitening properties when the adhered material contains corrosive components such as metals. In addition, from the perspective of improving aggregation, it is particularly preferred that the product contains both the hydroxyl-containing monomer (a3) ​​and the nitrogen-containing monomer (a4).

[0315] Furthermore, the aforementioned slurry composition can be composed of the (meth)acrylic polymer (P1) and monomer components as described in the first method. In one example, such a slurry composition can be formed by the so-called partial polymerization of monomer components, or it can be prepared by adding monomer components to a polymer formed by the complete polymerization or partial polymerization of the monomer components constituting the (meth)acrylic polymer (P1). That is, if the specified polymerizing components are partially polymerized, a portion of the monomers polymerizes to form a polymer, and a portion of the monomers remain, thereby forming a slurry composition. In another example, the slurry composition can also be prepared by adding monomer components to a polymer formed by partial or complete polymerization.

[0316] [(Meth)acrylate (a1)]

[0317] As for the aforementioned alkyl methacrylate (a1), the alkyl methacrylate (a1) described in the first method described above can be listed, and the preferred monomers are also the same as those of the alkyl methacrylate (a1) described in the first method described above.

[0318] From the perspective of achieving flexibility, the content of the aforementioned alkyl methacrylate (a1) relative to the slurry composition (adhesive sheet) is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, even more preferably 15 to 85% by mass, and particularly preferably 20 to 80% by mass. When the content of structural units derived from alkyl methacrylate (a1) is above the aforementioned lower limit, the foaming resistance of the peripheral ends during bonding is excellent, and when it is below the upper limit, other physical properties such as adhesion can be taken into account, which is preferred from this perspective.

[0319] [Carboxyl-containing monomer (a2)]

[0320] As the aforementioned carboxyl-containing monomer (a2), the carboxyl-containing monomer (a2) described in the first method described above can be listed, and the preferred types of monomers are the same as those of the carboxyl-containing monomer (a2) described in the first method described above.

[0321] When the slurry composition contains a carboxyl-containing monomer (a2), its content is typically 0.1 to 15% by mass relative to the slurry composition, preferably 0.3 to 13% by mass, more preferably 0.5 to 10% by mass, and particularly preferably 1 to 6% by mass.

[0322] [Hydroxy monomer (a3)]

[0323] As for the aforementioned hydroxyl-containing monomer (a3), the hydroxyl-containing monomer (a3) ​​described in the first method described above can be listed, and the preferred types of monomers are the same as those of the hydroxyl-containing monomer (a3) ​​described in the first method described above.

[0324] When the slurry composition contains a hydroxyl-containing monomer (a3), its content is typically 3 to 30% by mass relative to the slurry composition, preferably 5 to 25% by mass, and particularly preferably 7 to 20% by mass.

[0325] [Nitrogen-containing monomer (a4)]

[0326] As for the aforementioned nitrogen-containing monomer (a4), the nitrogen-containing monomer (a4) described in the first method described above can be listed, and the preferred types of monomers are also the same as those of the nitrogen-containing monomer (a4) described in the first method described above.

[0327] When the slurry composition contains a nitrogen-containing monomer (a4), its content is typically 0.1 to 15% by mass relative to the slurry composition, preferably 0.5 to 13% by mass, particularly preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass.

[0328] The aforementioned slurry composition may contain the copolymeric monomers (a5) to (a9) described in the first method. The types of these preferred monomers are the same as those described in the first method.

[0329] Furthermore, the content of these copolymeric monomers (a5) to (a9), i.e., the mass ratio relative to the slurry composition, is the same as the mass ratio relative to the structural unit 100% of the (meth)acrylic polymer (P1) described in the first method above.

[0330] [UV absorber (B)]

[0331] The aforementioned ultraviolet absorber (B) includes an ultraviolet absorber (B-1) with maximum absorption at wavelengths of 300 to 360 nm and an ultraviolet absorber (B-2) other than the aforementioned (B-1) with maximum absorption at wavelengths of 350 to 420 nm. The ultraviolet absorber (B) is particularly preferably composed of only ultraviolet absorber (B-1) and ultraviolet absorber (B-2).

[0332] The preferred compounds and physical properties of the aforementioned ultraviolet absorbers (B-1) and (B-2) are the same as those described in the first method above.

[0333] From the viewpoint of ultraviolet absorption, the content of the aforementioned ultraviolet absorber (B) relative to the slurry composition (adhesive sheet) is preferably 0.1 to 20% by mass, more preferably 0.2 to 10% by mass, even more preferably 0.4 to 8% by mass, and particularly preferably 0.6 to 5% by mass.

[0334] Furthermore, from the viewpoint of ultraviolet absorption, the content ratio of ultraviolet absorber (B-1) to ultraviolet absorber (B-2) is 30:70 to 70:30 by mass, preferably 40:60 to 60:40, and particularly preferably 45:55 to 55:45.

[0335] Furthermore, the slurry composition preferably includes the crosslinking agent (C) and photoinitiator (D) described in the first method above. In addition, it may also include other components such as the silane coupling agent described in the first method above.

[0336] [Cross-linking agent (C)]

[0337] When the aforementioned slurry composition contains a crosslinking agent (C), the crosslinking agent (C) becomes a resin component (A2) through a crosslinking reaction with the aforementioned slurry components. That is, when the slurry components contain a crosslinking agent (C), the resulting resin component (A2) has structural units derived from the crosslinking agent (C).

[0338] When using the aforementioned crosslinking agent (C), the preferred compound, physical properties, etc., are the same as those of the crosslinking agent (C) described in the first method above.

[0339] Furthermore, the preferred content of the crosslinking agent (C) relative to the slurry composition (adhesive sheet) is typically 0.1 to 30% by mass, preferably 1 to 25% by mass, and particularly preferably 5 to 20% by mass. By keeping the content of the crosslinking agent (C) within the aforementioned range, there is a tendency to reduce the shear storage modulus at low temperatures, increase the maximum value of the loss tangent (tanδ), and adjust to the desired viscoelasticity.

[0340] [Photoinitiator (D)]

[0341] As for the aforementioned photoinitiator, there is no particular limitation as long as it is the photoinitiator described in the first method. From the viewpoint of effectively carrying out the polymerization reaction, it is preferable to include a pyrolysis-type photoinitiator. Among the aforementioned pyrolysis-type photoinitiators, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide are particularly preferred.

[0342] Furthermore, from the viewpoint of effectively forming a cross-linked structure, it is preferable to include a hydrogen-abstracting photoinitiator, and particularly preferred are benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, and 4-(meth)acryloyloxybenzophenone.

[0343] The aforementioned photoinitiator may include two or more selected from the group consisting of cleavage-type photoinitiators and / or hydrogen-abstraction-type photoinitiators.

[0344] When using the aforementioned photoinitiator (D), its content relative to the slurry composition (adhesive sheet) is typically 0.1 to 10% by mass, preferably 0.5 to 6% by mass, and more preferably 1 to 4% by mass. If the content of the photoinitiator (D) is within this range, there is a tendency for a good crosslinking reaction to occur.

[0345] [Other ingredients]

[0346] Other components may be the same as those described in the first method above.

[0347] When using a silane coupling agent, its content relative to the slurry composition (adhesive sheet) is typically 0.005 to 5% by mass, preferably 0.01 to 3% by mass, and more preferably 0.05 to 1% by mass. If the content is within the aforementioned range, there is a tendency for improved adhesion and durability.

[0348] [Method for manufacturing this adhesive sheet based on the second method]

[0349] Next, the manufacturing method of this adhesive sheet based on the second method will be described.

[0350] However, the following description is an example of a method for manufacturing this adhesive sheet, and this adhesive sheet is not limited to adhesive sheets manufactured by this method.

[0351] In the fabrication of this adhesive sheet, the aforementioned slurry composition is prepared, and the slurry composition is prepolymerized by irradiating it with active energy rays. Subsequently, the slurry composition, with the addition of photoinitiator (D), crosslinking agent (C), and other components as needed, is coated onto a release film or similar material using various coating methods. Then, the slurry composition and crosslinking agent (C) are irradiated and heated with active energy rays to cure, thus producing a resin component (A2). This process is then used to fabricate the adhesive sheet.

[0352] The aforementioned crosslinking agent (C) and other components can be added to the slurry composition from the beginning, or they can be added to the slurry composition after prepolymerization. Therefore, in the fabrication of this adhesive sheet, prepolymerization and curing can be performed in a single step.

[0353] In another embodiment of the manufacturing method of this adhesive sheet, the aforementioned composition can be dissolved in a solvent, coated onto a release film and dried, and then prepolymerized and cured by irradiation with active energy rays, thereby producing the adhesive sheet.

[0354] In the manufacturing method of this adhesive sheet, the release film, active energy rays, solvent, mixing method, coating method, drying conditions, etc., can be described according to the description of the first method above.

[0355] The adhesive sheet obtained by this second method can be a single-layer sheet having only an adhesive layer containing a slurry composition, or a multi-layer sheet having multiple adhesive layers containing a slurry composition and other adhesive layers stacked together.

[0356] Alternatively, this adhesive sheet may also be provided as an adhesive sheet with a release film, which is formed by laminating a release film on one or both sides of an adhesive layer containing a slurry composition.

[0357] [Preferred Uses of This Adhesive Sheet]

[0358] This adhesive sheet is suitable for bonding optical components. Specifically, it is suitable for bonding components that constitute a display, especially components used in the manufacture of displays, and is particularly suitable as an adhesive sheet for organic light-emitting diode (OLED) display devices.

[0359] Specifically, it is used as an adhesive sheet for attaching an image display panel to a protective panel, a touch panel, or other components of an image display device disposed on its front side (viewable side), or to components constituting such image display device components.

[0360] It should be noted that the same components as those described later can be used for the components constituting the image display device.

[0361] <Laminator for Image Display Devices>

[0362] An example of an embodiment of the present invention is an image display device laminate (hereinafter, sometimes referred to as "this image display device laminate") which is an image display device laminate having two optical components laminated together by means of this adhesive sheet.

[0363] In the components of the laminate for this image display device, the adhesive sheet is as described above. The components other than the adhesive sheet will be described below.

[0364] <Optical Components>

[0365] Examples of optical components constituting the laminated body of this image display device include components for flat panel image display devices and components for flexible image display devices. Examples of such components include flexible displays such as liquid crystal displays and organic electroluminescent (EL) displays, cover lenses (cover films), polarizing plates, polarizing elements, phase retardation films, blocking films, viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, semi-transmissive reflective films, electrode films, transparent conductive films, metal mesh films, and touch sensor films. Any one of these components or a combination of two of them can be used. Examples include combinations of flexible displays with other optical components, and combinations of cover lenses with other optical components.

[0366] It should be noted that the aforementioned flexible image display device components refer to bendable components, specifically components used in image display devices with curved surfaces, and components capable of repeated bending. Particularly preferred are components capable of being fixed into a curved shape with a radius of curvature of 25 mm or more, and especially components capable of withstanding bending forces with a radius of curvature of less than 25 mm, more preferably less than 3 mm.

[0367] In the above configuration, components constituting optical elements include resin sheets or glass, etc.

[0368] Examples of materials that can be used for the resin sheet include polyester resin, cyclic olefin resin, cellulose triacetate resin, polymethyl methacrylate resin, polyurethane, epoxy resin, polyimide resin, and aromatic polyamide resin. These can be one type of resin or two or more types of resin. Preferably, the resin sheet contains at least one resin selected from the group consisting of polyester resin, cyclic olefin resin, cellulose triacetate resin, polymethyl methacrylate resin, epoxy resin, polyimide resin, aromatic polyamide resin, and polyurethane resin as the main component.

[0369] Here, "main component" refers to the component that accounts for the largest mass percentage among the components constituting the optical component. Specifically, it accounts for 50% or more by mass of the resin composition (resin sheet) forming the optical component, more preferably 55% or more by mass, and particularly preferably 60% or more by mass.

[0370] [Manufacturing Method of the Laminated Body for This Image Display Device]

[0371] There are no particular limitations on the manufacturing method of the laminate for this image display device. As mentioned above, for example, an adhesive composition can be applied to an optical component to form an adhesive sheet, or an adhesive sheet with a release film can be pre-formed and then bonded to the optical component.

[0372] <Image display device>

[0373] An example of an image display device (hereinafter sometimes referred to as "this image display device") according to an embodiment of the present invention is an image display device assembled with an image display device laminate, wherein the image display device laminate has a configuration in which two optical components are bonded together by means of an adhesive sheet. For example, by laminating an image display device laminate having a configuration in which two optical components are bonded together by means of an adhesive sheet onto other optical components, this image display device having the laminate can be formed.

[0374] [Example]

[0375] The present invention will be described in more detail below with examples, but the present invention is not limited to the following examples as long as it does not depart from its spirit.

[0376] It should be noted that in the example, "parts" and "%" refer to the quality standard.

[0377] First, the details of the composition of the adhesive composition prepared in the examples will be described.

[0378] [(Meth)acrylic polymer (P1)]

[0379] An acrylic copolymer (weight average molecular weight: approximately 460,000) formed by random copolymerization of 64 parts 2-ethylhexyl acrylate, 19 parts methyl acrylate, and 17 parts hydroxyethyl acrylate.

[0380] [UV absorber (B)]

[0381] • UV absorber (B-1): 2,4-bis[4-(2-ethylhexyloxy)-2-hydroxyphenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (maximum absorption wavelength: 346nm, manufactured by BASF Japan as "Tinosorb S")

[0382] • Ultraviolet absorber (B-2): 2((2-(dibutylamino)-4-epoxy-6-methyl-5-pyrimidinyl)methylene)propanedionitrile (maximum absorption wavelength: 402nm, half-width at half maximum: 43nm, manufactured by Yamada Chemical Industry Co., Ltd., "FDB-009")

[0383] [Cross-linking agent (C)]

[0384] • Crosslinking agent (C-1): A urethane acrylate formed from 2-hydroxyethyl acrylate, isophorone diisocyanate and propylene glycol (DAICEL-ALLNEX "KRM9465", glass transition temperature (Tg): -45℃, number of olefinic unsaturated groups: 2, weight average molecular weight: 10000).

[0385] • Crosslinking agent (C-2): Pentaerythritol tri(tetra)acrylate (NK EsterATMM3L manufactured by Shin-Nakamura Chemical Co., Ltd., number of olefinic unsaturated groups: 3~4, weight average molecular weight: 298~352)

[0386] [Photoinitiator (D)]

[0387] • Photoinitiator (D-1): Ethyl (2,4,6-trimethylbenzoyl)phenylphosphonite (molar absorptivity at 405 nm: 81 L / mol·cm, IGM's "Omnirad TPO-L")

[0388] • Photoinitiator (D-2): Dimethyl 2,2'-(thiobis(4,1-phenylene))bis(2-octoacetate) (Molar absorptivity at 405 nm: 329 L / mol·cm)

[0389] <Example 1>

[0390] A binder composition is prepared by uniformly mixing 100 parts of (meth)acrylic polymer (P1), 0.4 parts of ultraviolet absorber (B-1), 0.4 parts of ultraviolet absorber (B-2), 20 parts of crosslinking agent (C-1), and 2 parts of photoinitiator (D-1).

[0391] Next, a sheet is formed on a 100μm thick release film (polyethylene terephthalate (PET) film manufactured by Mitsubishi Chemical Corporation) that has undergone silicone release treatment, with the aforementioned adhesive composition having a thickness of 100μm.

[0392] Then, a 75 μm thick release film (PET film manufactured by Mitsubishi Chemical Corporation) that has undergone silicone release treatment is laminated onto the sheet-like adhesive composition to form a laminate, thereby obtaining an adhesive composition sheet with a release film consisting of a release film / adhesive composition layer / release film.

[0393] Next, using a high-pressure mercury lamp through the release film, the adhesive composition is illuminated from the surface of the release film with a cumulative light intensity of approximately 1500 mJ / cm at a wavelength of 365 nm. 2 The method of ultraviolet irradiation was used (the measured value at 405nm was 1.1J / cm). 2 This process yields an adhesive sheet with a release film laminated on both the front and back sides.

[0394] <Examples 2 and 3, Comparative Examples 1-3>

[0395] Except for changing to the formulation shown in Table 1 below, adhesive sheets with release films of Examples 2, 3, and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1.

[0396] The adhesive sheets with release films obtained in the examples and comparative examples were measured and evaluated as follows. The results are shown in Table 1 below.

[0397] <Light transmittance>

[0398] For the adhesive sheets with release films prepared in the examples and comparative examples, one release film is peeled off, and the exposed adhesive surface is rolled onto soda-lime glass (82mm × 53mm × 0.5mm thickness). Next, the remaining release film is peeled off, and the sheets are rolled onto soda-lime glass (82mm × 53mm × 0.5mm thickness). Then, an autoclave treatment (60°C, gauge pressure 0.2MPa, 20 minutes) is performed for final bonding to prepare an evaluation laminate.

[0399] For the aforementioned evaluation laminates, the light transmittance (%) at wavelengths of 250–800 nm was measured using a spectrophotometer (Hitachi High Technology Co., Ltd. “U-4100”). The light transmittance at 380 nm, 405 nm, and 430 nm was read from the obtained spectrophotometer.

[0400] <Shear storage modulus (G'), loss tangent (Tanδ), glass transition temperature (Tg)>

[0401] Remove the release film from each adhesive sheet with a release film prepared in the examples and comparative examples, and stack multiple layers of adhesive sheets to form a laminate with a thickness of about 0.8 mm.

[0402] A cylinder with a diameter of 8 mm was punched from the obtained laminate of adhesive sheet and used as a sample.

[0403] For this sample, the temperature dispersion of dynamic viscoelasticity was measured using a viscoelasticity measuring apparatus (TA Instruments, DHR20) under the following measurement conditions.

[0404] The maximum values ​​of shear storage modulus (G'), loss tangent (Tanδ), and peak temperature of loss tangent (tanδ) as glass transition temperature (Tg) at -20℃ and 23℃ were obtained from the obtained dynamic viscoelastic temperature dispersion data.

[0405] (Measurement conditions)

[0406] ·Measurement fixture: Φ8mm parallel plate

[0407] • Deformation: 0.1%

[0408] • Frequency: 1Hz

[0409] • Measurement temperature: -50~100℃

[0410] • Heating rate: 5℃ / minute

[0411] <Gel fraction>

[0412] The release film was peeled off from each adhesive sheet with a release film prepared in the Examples and Comparative Examples, and approximately 0.1 g of adhesive sheet material was taken from the adhesive sheet. The taken adhesive sheet material was wrapped in a pre-made bag-shaped SUS mesh (#150) of mass (X), and the bag was sealed to prepare a sample, and the mass (Y) of the sample was measured. The aforementioned sample was kept in ethyl acetate at 23°C in the dark for 24 hours, and then the aforementioned sample was taken out and heated at 70°C for 4.5 hours to evaporate the ethyl acetate, and the mass (Z) of the dried sample was measured. The gel fraction (X0) before light irradiation was calculated from each measured mass using the following formula.

[0413] Gel fraction (%) = [(ZX) / (YX)] × 100

[0414] <Adhesion>

[0415] A polyethylene terephthalate film (Cosmoshine A4300, manufactured by Toyobo Co., Ltd.) serving as the substrate film was manually rolled onto the adhesive surface of an adhesive sheet made from each of the adhesive sheets with release films prepared in the examples and comparative examples, after removing one release film. This was then cut into 10mm wide strips, and the adhesive surface exposed by peeling off the remaining release film was manually rolled onto a soda-lime glass plate to create a laminate composed of glass / adhesive sheet / substrate film.

[0416] The aforementioned laminate was subjected to autoclaving (60°C, gauge pressure 0.2 MPa, 20 minutes) for final bonding to prepare a glass adhesion evaluation sample. The substrate film was stretched and peeled off at a peeling speed of 300 mm / min at a 180° angle to the glass plate. The tensile strength was measured using a force sensor, and the 180° peel strength (N / cm) of the adhesive sheet to the glass surface was measured.

[0417] [Table 1]

[0418]

[0419] As can be seen from the results in Table 1 above, the adhesive sheet of the embodiment exhibits excellent transparency and ultraviolet absorption characteristics. Furthermore, due to its excellent viscoelastic properties, the image display device equipped with this adhesive sheet demonstrates excellent impact resistance.

[0420] On the other hand, the adhesive sheet of Comparative Example 1 does not contain UV absorber (B) and cannot achieve the specified UV absorption properties.

[0421] Furthermore, the adhesive sheet of Comparative Example 2 has high light transmittance and low ultraviolet absorption at a wavelength of 405nm because the ratio of ultraviolet absorber (B-1) to (B-2) is outside the specified range.

[0422] In addition, the adhesive sheet of Comparative Example 3 contains only ultraviolet absorber (B-1), so it has high light transmittance at wavelengths of 380 nm and 405 nm and low ultraviolet absorption.

[0423] The foregoing embodiments illustrate specific aspects of the invention, but these embodiments are merely illustrative and not intended to be limiting. Various modifications that will be apparent to those skilled in the art are included within the scope of this invention.

[0424] Industrial availability

[0425] This adhesive sheet has excellent impact resistance and transparency, and excellent ultraviolet absorption up to the vicinity of the visible light region. Therefore, it is useful as an adhesive sheet for bonding optical components, especially for organic light-emitting diode (OLED) display devices.

Claims

1. An adhesive sheet comprising: a resin component A having structural units derived from (meth)acrylate monomers, and an ultraviolet absorber B, and satisfying the following requirements [I] and [II], [I] The ultraviolet absorber B includes ultraviolet absorber B-1, which has maximum absorption at wavelengths of 300-360 nm, and ultraviolet absorber B-2, which has maximum absorption at wavelengths of 350-420 nm, excluding B-1. [II] The ratio of ultraviolet absorber B-1 to ultraviolet absorber B-2 contained in the adhesive sheet is 30:70 to 70:30 by mass.

2. The adhesive sheet according to claim 1, further satisfies the following requirement [III], [III] The shear storage modulus at -20℃ obtained by dynamic viscoelasticity measurement of the adhesive sheet in shear mode with a passing frequency of 1Hz is less than 2.0MPa, and the glass transition temperature obtained from the peak of the loss tangent, i.e. tanδ, is less than -20℃.

3. The adhesive sheet according to claim 1, wherein, The ultraviolet absorber B-2 has a pyrimidine structure.

4. The adhesive sheet according to claim 1, wherein, The content of the ultraviolet absorber B is 0.1 to 20% by mass relative to the adhesive sheet.

5. The adhesive sheet according to claim 1, wherein, The resin component A has structural units derived from the crosslinking agent C.

6. The adhesive sheet according to claim 5, wherein, The crosslinking agent C comprises an acrylic crosslinking agent with a glass transition temperature (Tg) below -20°C as determined by the Fox formula.

7. The adhesive sheet according to claim 5, wherein, The crosslinking agent C is an acrylic crosslinking agent having 1 to 3 olefinic unsaturated groups in the molecule.

8. The adhesive sheet according to claim 5, wherein, The crosslinking agent C comprises an acrylic crosslinking agent having an oxyalkylene structure.

9. The adhesive sheet according to claim 5, wherein, The crosslinking agent C comprises a multifunctional (meth)acrylate oligomer with a weight-average molecular weight of 1000 or more.

10. The adhesive sheet according to claim 5, wherein, The crosslinking agent C comprises urethane (meth) acrylate.

11. The adhesive sheet according to claim 1, wherein, The adhesive sheet contains photoinitiator D.

12. The adhesive sheet according to claim 11, wherein, The photoinitiator D is a hydrogen-abstracting photoinitiator.

13. The adhesive sheet according to claim 1, wherein the gel fraction is 5-80%.

14. An adhesive sheet with a release film, comprising the configuration of an adhesive sheet and a release film laminated as described in any one of claims 1 to 13.

15. A laminate for an image display device, comprising two optical components laminated together by means of an adhesive sheet according to any one of claims 1 to 13.

16. An image display device comprising the image display device laminate of claim 15.

17. An adhesive sheet for an organic light-emitting diode display device, comprising the adhesive sheet according to any one of claims 1 to 13.

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