Laminate for constituting image display device, method for manufacturing same, and image display device constituent member with release film

Abstract

Provided is a laminate for constituting an image display device, the laminate having excellent bonding reliability when performing bonding to an image display device constituent member having a three-dimensional curved surface shape, such as a spherical shape and a four-sided edge display.　The laminate for constituting an image display device comprises: an image display device constituent member having a three-dimensional curved surface shape; an adhesive sheet, and another image display device constituent member, wherein the adhesive sheet satisfies the requirements (1) to (4). (1) The deformation amount in a creep test under conditions of 25°C, 10 kPa, and 10 seconds is 23% or more. (2) The nanoindenter elastic modulus of the adhesive sheet surface is 2 MPa or more after irradiated with active energy rays at a wavelength of 365 nm using a high-pressure mercury lamp such that an integrated light intensity is 3000 mJ / cm2. (3) The adhesion strength to glass in a 180° peel test is 10 N / cm or more. (4) The tack count in a ball tack test is 3 or less.

Description

Laminate for image display device components and method for manufacturing the same, and image display device component with release film

[0001] The present invention relates to a laminate for an image display device, a method for manufacturing the same, and an image display device component with a release film.

[0002] In recent years, in order to improve the visibility of image display devices, the gap between the image display panel, such as a liquid crystal display (LCD), plasma display (PDP), or electroluminescent display (ELD), and the protective panel or touch panel component placed on its front side (viewing side) has been filled with a resin such as adhesive or glue to suppress reflection of incident light and light emitted from the displayed image at the air layer interface.

[0003] For example, Patent Document 1 discloses a method for manufacturing a laminate for an image display device, which has a configuration in which an image display device component is laminated on at least one side of a transparent double-sided adhesive sheet. This method involves first crosslinking an adhesive sheet with ultraviolet light, then bonding it to an image display device component, and finally irradiating the adhesive sheet with ultraviolet light through the image display device component to perform secondary curing. Patent Document 2 also discloses a pressure-sensitive adhesive sheet containing a (meth)acrylic copolymer having ultraviolet crosslinkable portions, which is useful for displays and touch panels.

[0004] Patent No. 4971529 Patent No. 6062740

[0005] In recent years, there has been a growing demand for high design quality in image display devices. The shape of the front surface protection panel is changing from flat to designs with gently curved edges and corners, or designs where the entire display area is curved. Furthermore, development is progressing on four-sided edge displays, where all four edges of the screen are curved, and curved displays, where the entire screen is curved or spherical. To enhance their design appeal, there is a need for the development of displays with smaller radii of curvature (larger curves). The adhesive sheets described in Patent Documents 1 and 2 were studied in a laminated configuration using conventional flat image display device components, and the reliability of adhesion to curved components, particularly four-sided edge displays, was not considered.

[0006] In image display devices with such curved surfaces, a flexible optical film (such as a polarizing plate) and an image display cell are bonded to a rigid cover window with a curved surface. This causes the optical film and image display cell to conform to the curved shape of the cover window, thus maintaining the curved shape. In the curved portion, the curvature is smaller on the inner side (center of curvature) than on the outer side, resulting in mechanical strain at the bonding interface. In particular, the corners of spherical displays and four-sided edge displays have a three-dimensional curved shape, leading to significant strain and problems such as delamination and wrinkling at the bonding interface. Furthermore, using a soft adhesive sheet to prevent the aforementioned wrinkling can result in pressure marks from the backing material degrading the appearance. Additionally, when an image display device component with a curved shape is laminated with other image display device components via an adhesive sheet, rebound bubbles can form over time due to the repulsive force of the image display device components.

[0007] Therefore, against this background, the present invention provides a laminate for image display device components that exhibits excellent bonding reliability when bonded to image display device components having at least a portion of a three-dimensional curved shape, such as spherical displays or four-sided edge displays.

[0008] However, in view of these circumstances, the inventors have conducted extensive research and have found that the above problems can be solved by setting the deformation amount, nanoindenter modulus, adhesive strength, and tack of the adhesive sheet used in a laminate for image display device components, which comprises at least a portion of which has a three-dimensional curved surface shape, to a specific range.

[0009] That is, the present invention has the following aspects: [1] A laminate for an image display device comprising an image display device component having a three-dimensional curved surface shape, an adhesive sheet, and other image display device components, wherein the image display device component having a three-dimensional curved surface shape is laminated with the other image display device components via the adhesive sheet, and the adhesive sheet satisfies the following (1) to (4): (1) The amount of deformation in a creep test under the conditions of 25°C, 10 kPa, and 10 seconds is 23% or more. (2) The integrated light amount of active energy rays with a wavelength of 365 nm using a high-pressure mercury lamp is 3000 mJ / cm ２The nanoindenter elastic modulus of the adhesive sheet surface after irradiation is 2 MPa or more. (3) The adhesion strength to glass in the 180° peel test is 10 N / cm or more. (4) The tack in the ball tack test is 3 or less. [2] The laminate for constructing an image display device according to [1], wherein the adhesive sheet is formed from a resin composition containing a (meth)acrylic copolymer (A). [3] The laminate for constructing an image display device according to [2], wherein the (meth)acrylic copolymer (A) is polymerized from a copolymer component containing 40% by mass or more of a branched alkyl (meth)acrylate monomer. [4] The laminate for constructing an image display device according to [2] or [3], wherein the (meth)acrylic copolymer (A) is polymerized from a copolymer component containing an amide group-containing monomer and a long-chain alkyl group-containing alkyl (meth)acrylate monomer having 10 or more carbon atoms. [5] The laminate for constructing an image display device according to any one of [2] to [4], wherein the resin composition contains a hydrogen abstraction type photopolymerization initiator. [6] The laminate for an image display device according to any one of [2] to [5], wherein the resin composition contains a glycidyl group-containing silane coupling agent. [7] The laminate for an image display device according to any one of [1] to [6], wherein the adhesive sheet contains a polymer of (meth)acryloyloxybenzophenone. [8] The laminate for an image display device according to any one of [1] to [7], wherein the adhesive sheet has a multilayer structure of at least two layers. [9] The laminate for an image display device according to any one of [1] to [8], wherein the gel fraction of the adhesive sheet is 75% or more.

[10] The adhesive sheet is exposed to an active energy ray with a wavelength of 365 nm, with an integrated light intensity of 3000 mJ / cm². ２[1] to [9] A laminate for an image display device, wherein the difference between the gel fraction when cured by irradiation and the gel fraction before irradiation with the active energy ray is 10% or more.

[11] A laminate for an image display device, wherein the image display device component having a three-dimensional curved shape has a curved shape with a radius of curvature of 10 mm or less.

[12] A laminate for an image display device, wherein the image display device component having a three-dimensional curved shape has a stepped portion with a height difference of 5 μm or more on the surface in contact with the adhesive sheet.

[13] A method for manufacturing a laminate for an image display device, wherein the laminate for an image display device, wherein the laminate for an image display device, wherein the laminate for an image display device, wherein the laminate for an image display device, wherein the laminate for an image display device, wherein the laminate for an image display device, wherein the laminate for an image display device, wherein the gel fraction when cured by irradiation and the gel fraction before irradiation with the active energy ray is 10% or more. Step 2: Step of peeling the first release film from the adhesive sheet with double-sided release film and bonding it to the image display device component having a three-dimensional curved shape to obtain an image display device component with a second release film. Step 3: Step of peeling the second release film from the image display device component with a second release film and bonding it to the other image display device component. Step 4: Step of irradiating the image display device component having a three-dimensional curved shape and / or the other image display device component with active energy rays to obtain a laminate for image display device components.

[14] An image display device component with a release film comprising an image display device component having a three-dimensional curved shape, an adhesive sheet, and a release film, wherein the release film, the adhesive sheet, and the image display device component having a three-dimensional curved shape are laminated in this order, and the adhesive sheet satisfies the following (1) to (4). (1) The deformation in the creep test under the conditions of 25°C, 10 kPa, and 10 seconds is 23% or more. (2) Using a high-pressure mercury lamp, the integrated light intensity of the active energy rays with a wavelength of 365 nm is 3000 mJ / cm². ２The nanoindenter modulus of the adhesive sheet surface after irradiation is 2 MPa or higher. (3) The adhesion strength to glass in the 180° peel test is 10 N / cm or higher. (4) The tack in the ball tack test is 3 or less.

[0010] The laminate for image display device components of the present invention exhibits excellent bonding reliability when bonded to image display device components having at least a portion of a three-dimensional curved surface shape, and can be suitably used for spherical displays and four-sided edge displays.

[0011] This is a schematic cross-sectional view showing a curved portion of a laminate for an image display device according to one embodiment of the present invention.

[0012] The following describes specific embodiments for carrying out the present invention, but the present invention is not limited to these.

[0013] In this specification, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate. In this specification, "sheet" is not specifically distinguished from "film" or "tape," but is used to include these as well. In this specification, "x and / or y (where x and y are any combination)" means at least one of x and y, and can mean x only, y only, or x and y. In this specification, when "X to Y" (where X and Y are any numbers) is used, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." In this specification, when "greater than or equal to X" (where X is any number) or "less than or equal to Y" (where Y is any number) is used, it also includes the meaning of "preferably greater than X" or "preferably less than Y." In this specification, for numerical ranges described in stages, the upper or lower limit of one stage of the numerical range may be arbitrarily combined with the upper or lower limit of another stage of the numerical range. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this specification, preferred combinations are more preferred. In this specification, room temperature, ambient temperature, and various physical and characteristic values ​​shall be at 23°C unless otherwise specified. When describing measurement methods, etc., based on standards in this specification, unless otherwise specified, the standards shall be those in effect as of the filing date of this application (or the priority date, if applicable). If the standard has been abolished by that date, the standards in effect as of the date of abolition shall be used.

[0014] An image display device component laminate according to one embodiment of the present invention (hereinafter sometimes referred to as "this laminate") is an image display device component laminate comprising an image display device component having a three-dimensional curved shape, an adhesive sheet, and other image display device components. For example, in Figure 1, this laminate 10 comprises an image display device component 11 having a three-dimensional curved shape in at least a part thereof, an adhesive sheet 20, and other image display device components 12. The image display device component having a three-dimensional curved shape is laminated with the other image display device components via the adhesive sheet, and the adhesive sheet is characterized in that it satisfies the following (1) to (4). (1) The amount of deformation in a creep test under the conditions of 25°C, 10 kPa, and 10 seconds is 23% or more. (2) The integrated light amount of active energy rays with a wavelength of 365 nm using a high-pressure mercury lamp is 3000 mJ / cm ２ The nanoindenter modulus of the adhesive sheet surface after irradiation is 2 MPa or higher. (3) The adhesion strength to glass in the 180° peel test is 10 N / cm or higher. (4) The tack in the ball tack test is 3 or less.

[0015] The laminate, for example, has a laminated structure as shown in Figure 1 as one preferred embodiment, in which an image display device component 11 having a three-dimensional curved shape is laminated in close contact with another image display device component 12 via an adhesive sheet 20. Specifically, the adhesive sheet 20 has a three-layer multilayer structure consisting of an outermost layer (adhesive layer) 21, an intermediate layer 22, and an innermost layer (adhesive layer) 23, and is interposed between the component 11 and the component 12 to firmly bond them together.

[0016] Furthermore, an image display device component with a release film according to one embodiment of the present invention (hereinafter sometimes referred to as "this component") comprises an image display device component having a three-dimensional curved surface shape, an adhesive sheet, and a release film. In this component, the release film, the adhesive sheet, and the image display device component having a three-dimensional curved surface shape are laminated in this order, and the adhesive sheet is characterized in that it satisfies the physical properties of (1) to (4) described above. Also, since the release film and the adhesive sheet are laminated along the curved surface shape of the image display device component, the release film and the adhesive sheet (hereinafter sometimes referred to as "this adhesive sheet") are also usually curved (have a curved surface shape). The following describes each component constituting this laminate and this component.

[0017] <Adhesive Sheet> This adhesive sheet is formed from a resin composition (hereinafter sometimes simply referred to as "resin composition") that mainly contains (meth)acrylic copolymer (A). The term "main component" means that the resin composition contains 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more of (meth)acrylic copolymer (A) based on the entire resin composition.

[0018] The layer structure of this adhesive sheet is not particularly limited and may be a single layer or a multi-layer structure of two or more layers. However, from the viewpoint of bonding reliability, a multi-layer structure of two or more layers is preferred, more preferably a multi-layer structure of two or more layers with the surface layer and back layer being (meth)acrylic adhesive layers, even more preferably a multi-layer structure of three or more layers with the outermost surface layer and the outermost surface layer being (meth)acrylic adhesive layers, and particularly preferably a three-layer structure [outermost layer (adhesive layer) / intermediate layer / innermost layer (adhesive layer)] having the outermost surface layer and the innermost surface layer being the (meth)acrylic adhesive layers, and further having an intermediate layer formed from a resin composition mainly containing (meth)acrylic resin. In the example shown in Figure 1, the adhesive sheet 20 has a three-layer multi-layer structure consisting of an outermost layer (adhesive layer) 21, an intermediate layer 22, and an innermost layer (adhesive layer) 23. The adhesive sheet 20 is interposed between an image display device component 11 having a three-dimensional curved shape and another image display device component 12, and laminates and holds them together. Furthermore, in cases where the sheet has three or more layers, with the outermost and innermost layers being (meth)acrylic adhesive layers, it is preferable that the intermediate layer is also formed from the aforementioned resin composition. Because this adhesive sheet has a (meth)acrylic adhesive layer, it may also be referred to as a "(meth)acrylic adhesive sheet".

[0019] Each layer of this adhesive sheet may be formed from the same resin composition, or from different resin compositions. Furthermore, if the adhesive sheet has three or more layers, it is preferable that the outermost layer and the innermost layer are formed from the same resin composition.

[0020] The thickness of this adhesive sheet is preferably 50 to 1000 μm, more preferably 60 to 500 μm, and even more preferably 75 to 300 μm. When the sheet thickness is above the lower limit, it tends to have excellent step absorption properties, and when it is below the upper limit, it tends to have excellent adhesion reliability to curved members having curved portions.

[0021] Furthermore, when the adhesive sheet consists of at least three layers, the sum of the thicknesses of the outermost and innermost layers is preferably 30-95%, more preferably 35-90%, and even more preferably 40-85% of the total thickness. By setting the thicknesses of the outermost and innermost layers within the above range, the adhesive sheet becomes less likely to be crushed when pressure is applied to it when bonded to a curved member having a curved portion, and tends to exhibit superior bonding reliability such as adhesiveness and step absorption.

[0022] The Asker hardness of the adhesive sheet is preferably 30 or higher, more preferably 35 or higher, even more preferably 40 or higher, and particularly preferably 45 or higher. The upper limit is usually 100 or lower, preferably 80 or lower. Generally, when two image display device components are bonded together via an adhesive sheet to form an image display device component laminate, and then the laminate is used to create an image display device, localized stress is applied to the image display device component laminate, which can cause indentations on the adhesive sheet and impair the appearance and visibility of the image display device. By setting the Asker hardness to a value equal to or higher than the above, the image display device component laminate tends to have excellent resistance to indentations.

[0023] The Asker hardness is measured by stacking adhesive sheets so that the total thickness of the adhesive sheets is in the range of 5 to 7 mm, and then pressing the tip of the Asker C2L hardness tester vertically downwards at a speed of 3 mm / min from a height of 10 mm with a load of 1 kg.

[0024] As stated above, the Asker hardness of this adhesive sheet is the value obtained when the adhesive sheet is laminated so that the total thickness of the adhesive sheet is in the range of 5 to 7 mm. This is because, in order to accurately measure the Asker hardness of this adhesive sheet, it is necessary to avoid the measurement results being affected by the measurement stage due to insufficient thickness of the adhesive sheet. Therefore, when measuring the Asker hardness, it is necessary to adjust the adhesive sheet to a certain thickness range before measurement. By measuring the Asker hardness after adjusting the adhesive sheet to the above range in advance, the Asker hardness of this adhesive sheet can be accurately determined.

[0025] From the viewpoint of improving bonding reliability, it is preferable that this adhesive sheet has photocurability, meaning it hardens when irradiated with active energy rays such as ultraviolet light.

[0026] When this adhesive sheet has active energy ray curability, the gel fraction before curing (after pre-curing, as described later) is preferably 0% or more, more preferably 40% or more, even more preferably 60% or more, and particularly preferably 65% ​​or more. When the gel fraction is 10% or more, the adhesive sheet does not undergo cohesive failure over time when bonded to a curved member, and tends to exhibit excellent curved surface adhesion. On the other hand, from the viewpoint of step-following ability, the gel fraction is preferably 70% or less, and more preferably 60% or less.

[0027] Furthermore, this adhesive sheet has active energy ray curing properties, and when exposed to active energy rays with a wavelength of 365 nm, the integrated light intensity is 3000 mJ / cm². ２ When cured by irradiation, it is preferable that the gel fraction increases compared to before irradiation with active energy rays (before curing). The gel fraction after curing is preferably 70% or more, more preferably 73% or more, and even more preferably 75% or more. The upper limit is usually 100%.

[0028] When the gel fraction after curing is within the above range, it tends to provide shape stability to the adhesive sheet and durability when used as an image display device. Furthermore, it is preferable that the gel fraction after curing is 5% or more higher than the gel fraction before curing, more preferably 10% or more higher, even more preferably 15% or more higher, and particularly preferably 20% or more higher. There is no particular upper limit, but it is usually preferable to be 100% or less and 95% or less. When the difference in gel fraction before and after curing is within the above range, it tends to provide step-following ability and durability when used as an image display device.

[0029] The gel fraction is determined by the following method: Measure the mass of the adhesive sheet (mass before immersion), wrap it in a bag-like structure using SUS mesh (#200), immerse it in ethyl acetate, and store it in the dark at 23°C for 24 hours. Then, remove the package, heat it at 70°C for 4.5 hours to evaporate the attached ethyl acetate, measure the remaining mass of the adhesive sheet (mass after immersion), and calculate the gel fraction using the following formula: Gel fraction (%) = [(mass after immersion) / (mass before immersion)] × 100

[0030] This adhesive sheet exhibits excellent reliability in bonding to image display device components having at least a portion of a curved shape, by specifying (1) deformation amount in creep tests, (2) nanoindenter modulus, (3) adhesive strength, and (4) tack within a particular range, and can be suitably used for spherical displays and four-sided edge displays. Furthermore, this adhesive sheet has resistance to indentations and can suppress wrinkles and air bubbles that tend to occur in curved areas when bonding to image display device components with curved shapes.

[0031] (1: Deformation in creep test) The deformation of this adhesive sheet in a creep test under the conditions of 25°C, 10 kPa, and 10 seconds is 23% or more, preferably 25% or more, and more preferably 27% or more. There is no particular upper limit, but it is usually 80%, and from the viewpoint of bonding reliability, it is preferable to be 70% or less. The creep test can be measured, for example, by the method described in the examples below.

[0032] (2: Nanoindenter elastic modulus) This adhesive sheet is tested using a high-pressure mercury lamp to obtain active energy rays with a wavelength of 365 nm, with an integrated light intensity of 3000 mJ / cm². ２ The nanoindenter modulus of the adhesive sheet surface after irradiation is 2 MPa or higher, preferably 2.5 MPa or higher, more preferably 2.8 MPa or higher, and even more preferably 3.0 MPa or higher. There is no particular upper limit, but it is usually 20 MPa or lower, and preferably 15 MPa or lower. The nanoindenter modulus can be measured, for example, by the method described in the examples below.

[0033] (3: Adhesive strength) The present pressure-sensitive adhesive sheet generally has an adhesive strength to glass of 10 N / cm or more in a 180° peel test, preferably 10.5 N / cm or more, and more preferably 11 N / cm or more. Although there is no particular upper limit, it is generally 50 N / cm.

[0034] Further, when the present pressure-sensitive adhesive sheet has active energy ray curability, the adhesive strength after irradiation with an active energy ray (after curing) is generally 10 N / cm or more, preferably 10.5 N / cm or more, and more preferably 11 N / cm or more. Although there is no particular upper limit, it is generally 50 N / cm.

[0035] The adhesive strength is measured by the following method. A polyethylene terephthalate film with a thickness of 100 μm ("Diafoil T100" manufactured by Mitsubishi Chemical Corporation) is bonded to one surface of the pressure-sensitive adhesive sheet, and the other surface is roll-pressed against soda-lime glass to obtain a bonded article. Thereafter, the above-mentioned bonded article is cured at a temperature of 40°C for 3 hours, and then finally attached to obtain a sample. The peel force (N / cm) to glass when this sample is peeled off at a peel angle of 180° and a peel speed of 60 mm / min under an environment of a temperature of 23°C and a humidity of 50% RH is measured.

[0036] Further, for the adhesive strength after curing, the finally attached sample is irradiated with ultraviolet rays from the polyethylene terephthalate film surface such that the integrated light intensity at 365 nm is 2000 mJ / cm ２ , and then cured for 12 hours under an environment of a temperature of 23°C and a humidity of 50% RH, and the resulting product may be used as a sample.

[0037] (4: Tack) The present pressure-sensitive adhesive sheet has a tack of 3 or less in a ball tack test. For the measurement of nanoindenter elastic modulus, for example, measurement can be performed by the method described in the Examples mentioned later.

[0038] As a control method to set the above-mentioned (1) deformation amount in creep test, (2) nanoindenter modulus, (3) adhesive strength, and (4) tack within a specific range, an adhesive sheet with the desired physical properties of (1) to (4) can be manufactured by controlling the degree of crosslinking, modification of the adhesive layer surface, content of copolymer monomer components, and other aspects of the manufacturing method. Furthermore, by simultaneously satisfying these specific parameters of (1) to (4), a synergistic effect can be achieved that solves the conflicting problems of "wrinkle resistance," "indentation resistance (FPC mark resistance)," and "rebound bubble resistance," which have been difficult to achieve simultaneously with conventional adhesive sheets, particularly in three-dimensional curved shapes, especially in designs where the four sides and corners of the screen are curved (such as four-sided edge displays).

[0039] The adhesive sheet is preferably an optically transparent adhesive sheet. Here, "optically transparent" means that the total light transmittance is 80% or more, preferably 85% or more, and more preferably 90% or more. The upper limit is 100%.

[0040] As described above, this adhesive sheet is formed from a resin composition containing a (meth)acrylic copolymer (A). The individual components included in the resin composition are described below.

[0041] [(meth)acrylic copolymer (A)] Examples of the (meth)acrylic copolymer (A) include a copolymer of an alkyl (meth)acrylate monomer having 4 to 18 carbon atoms in the alkyl group which is the copolymer component, and a monomer component that can copolymerize with it. Furthermore, the resin composition may contain only one type of (meth)acrylic copolymer (A), or two or more types.

[0042] Examples of alkyl (meth)acrylate monomers having 4 to 18 carbon atoms in the alkyl group include linear alkyl (meth)acrylates such as n-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, and Examples include branched alkyl (meth)acrylates such as sopentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, and isostearyl (meth)acrylate; alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used individually or in combination of two or more. Among these, alkyl ester monomers having a branched structure are preferred, more preferably branched alkyl (meth)acrylates, alicyclic (meth)acrylates, and even more preferably 2-ethylhexyl (meth)acrylate and isobornyl (meth)acrylate, with the alkyl group having 6 to 14 carbon atoms.

[0043] The content of alkyl (meth)acrylates having 4 to 18 carbon atoms in the alkyl group is usually 30 to 90% by mass, preferably 35 to 88% by mass, more preferably 40 to 86% by mass, and even more preferably 55 to 85% by mass, in the total monomer components of the copolymer. In particular, it is preferable to contain 40% by mass or more of branched alkyl (meth)acrylate monomers in the total monomer components of the copolymer, more preferably 45% by mass or more, and even more preferably 50% by mass or more. By containing branched alkyl (meth)acrylate monomers in a proportion above the lower limit, the adhesive sheet can be given appropriate flexibility and stress relaxation properties. On the other hand, there is no particular upper limit, but it is preferable to be 90% by mass or less.

[0044] Examples of copolymerizable monomer components include copolymers with monomer components containing one or more monomers selected from carboxyl group-containing (meth)acrylate monomers, hydroxyl group-containing (meth)acrylate monomers, nitrogen atom-containing monomers, epoxy group-containing (meth)acrylate monomers, vinyl monomers, alkyl (meth)acrylate monomers having 1 to 3 carbon atoms in the alkyl group, and other copolymerizable monomers.

[0045] In particular, the (meth)acrylic copolymer (A) contained in the resin composition that forms the surface and back layers of the adhesive sheet (or the outermost and innermost layers if the adhesive sheet has three or more layers) preferably contains at least one copolymerizable monomer component selected from the group consisting of carboxyl group-containing (meth)acrylate monomers, hydroxyl group-containing (meth)acrylate monomers, vinyl monomers, and alkyl (meth)acrylate monomers having 1 to 3 carbon atoms in the alkyl group.

[0046] Furthermore, the (meth)acrylic copolymer (A) contained in the resin composition forming the intermediate layer when the adhesive sheet has three or more layers preferably contains at least one selected from the group consisting of carboxyl group-containing (meth)acrylate monomers, hydroxyl group-containing (meth)acrylate monomers, nitrogen atom-containing monomers, vinyl monomers, and alkyl (meth)acrylate monomers having 1 to 3 carbon atoms in the alkyl group, as a copolymerizable monomer component, and more preferably contains at least one selected from the group consisting of nitrogen atom-containing monomers and alkyl (meth)acrylate monomers having 1 to 3 carbon atoms in the alkyl group.

[0047] Examples of the carboxyl group-containing (meth)acrylate monomer include (meth)acrylic acid and (meth)acrylic acid dimers. These may be used individually or in combination of two or more. Among these, (meth)acrylic acid is preferred.

[0048] The content of the carboxyl group-containing (meth)acrylate monomer is typically 10% by mass or less, preferably 8% by mass or less, and more preferably 6% by mass or less, in the total monomer components of the copolymer. The lower limit is typically 0% by mass.

[0049] Examples of the hydroxyl group-containing (meth)acrylate monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol polypropylene glycol mono(meth)acrylate, polyethylene glycol polybutylene glycol mono(meth)acrylate, polypropylene glycol polybutylene glycol mono(meth)acrylate, hydroxyphenyl (meth)acrylate, and the like. These may be used individually or in combination of two or more. Among these, 2-hydroxyethyl (meth)acrylate is preferred.

[0050] The content of the hydroxyl group-containing monomer is typically 30% by mass or less, preferably 25% by mass or less, and more preferably 20% by mass or less, in the total monomer components of the copolymer. The lower limit is typically 0% by mass.

[0051] Examples of nitrogen atom-containing monomers include aminoalkyl (meth)acrylates such as aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and aminoisopropyl (meth)acrylate; amino group-containing (meth)acrylate monomers such as N-alkylaminoalkyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate; amide group-containing (meth)acrylate monomers such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylolpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and diacetone (meth)acrylamide; and amide group-containing monomers such as maleic acid amide and maleimide. These may be used individually or in combination of two or more. Among these, amide group-containing (meth)acrylate monomers are preferred, and (meth)acrylamide is more preferred.

[0052] The nitrogen atom-containing monomer content is typically 20% by mass or less, preferably 10% by mass or less, and more preferably 7% by mass or less, in the total monomer components of the copolymer. The lower limit is typically 0% by mass.

[0053] Examples of the epoxy group-containing (meth)acrylate monomers include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. These may be used individually or in combination of two or more.

[0054] The content of the epoxy group-containing monomer is usually 20% by mass or less, preferably 10% by mass or less, in the total monomer components of the copolymer. The lower limit is usually 0% by mass.

[0055] Examples of vinyl monomers include compounds having a vinyl group in their molecule. Such compounds include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes; and polyalkylene glycol di(meth)acrylates. These may be used individually or in combination of two or more. Among these, vinyl acetate is preferred.

[0056] The content of the vinyl monomer is typically 40% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less, in the total monomer components of the copolymer. The lower limit is typically 0% by mass.

[0057] Examples of alkyl (meth)acrylate monomers having 1 to 3 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, and the like. These may be used individually or in combination of two or more. Methyl (meth)acrylate is preferred among these.

[0058] The content of alkyl (meth)acrylate monomers having 1 to 3 carbon atoms in the alkyl group is usually 40% by mass or less, preferably 35% by mass or less, and more preferably 25% by mass or less, in the total monomer components of the copolymer. The lower limit is usually 0% by mass.

[0059] Examples of the aforementioned other copolymerizable monomers include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, heterocyclic basic monomers such as vinylpyrrolidone, vinylpyridine, and vinylcarbazole, and macromonomers. These may be used individually or in combination of two or more.

[0060] The content of the aforementioned other copolymerizable monomers is usually 10% by mass or less, preferably 5% by mass or less, in the total monomer components of the copolymer. The lower limit is usually 0% by mass.

[0061] In this embodiment, a (meth)acrylic copolymer (A) obtained by copolymerizing the various monomer components may be used, and the copolymerization method may be carried out according to conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.

[0062] Furthermore, one particularly preferred embodiment of the (meth)acrylic copolymer (A) is one obtained by polymerizing a copolymer component containing an amide group-containing monomer and a long-chain alkyl group-containing (meth)acrylate alkyl ester monomer having 10 or more carbon atoms. By using this specific combination, the reliability of adhesion to three-dimensional curved surfaces is effectively improved.

[0063] Examples of the amide group-containing monomers include (meth)acrylate monomers having an amide group and vinyl monomers containing an amide group. For example, examples include amide group-containing (meth)acrylate monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and diacetone(meth)acrylamide, as well as amide group-containing monomers such as maleic acid amide and maleimide. These can be used individually or in combination of two or more, but among them, amide group-containing (meth)acrylate monomers are preferred, and N,N-dimethyl(meth)acrylamide is more preferred.

[0064] The content of the amide group-containing monomer is typically 1 to 30% by mass, preferably 5 to 25% by mass, and more preferably 10 to 20% by mass, in the total monomer components of the copolymer (A). By including the amide group-containing monomer within the above range, appropriate cohesive force and polarity can be imparted to the adhesive sheet, further improving the reliability of adhesion to members having a three-dimensional curved shape.

[0065] The aforementioned long-chain alkyl group-containing alkyl (meth)acrylate monomer has an alkyl group with 10 or more carbon atoms, preferably 10 to 18 carbon atoms. Examples include linear alkyl (meth)acrylates such as decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate, and branched alkyl (meth)acrylates such as isodecyl (meth)acrylate and isostearyl (meth)acrylate. These can be used individually or in combination of two or more, but among them, stearyl (meth)acrylate, lauryl (meth)acrylate, or mixtures thereof (e.g., stearyl lauryl methacrylate) are preferably used.

[0066] The content of the long-chain alkyl group-containing (meth)acrylate alkyl ester monomer is typically 0.01 to 10% by mass, preferably 0.05 to 5% by mass, and more preferably 0.1 to 2% by mass, in the total monomer components of the copolymer. By including a small amount of the long-chain alkyl group-containing (meth)acrylate alkyl ester monomer, the stress relaxation properties of the adhesive can be finely adjusted, and the generation of rebound bubbles, particularly in three-dimensional curved surfaces such as corners, tends to be effectively suppressed.

[0067] The weight-average molecular weight of the (meth)acrylic copolymer (A) is typically 50,000 to 1,500,000, preferably 70,000 to 1,300,000, and more preferably 100,000 to 1,200,000. The weight-average molecular weight of the (meth)acrylic copolymer (A) contained in the resin composition forming the surface and back layers (or the outermost and innermost layers if the adhesive sheet has three or more layers) of the adhesive sheet is typically 200,000 to 1,500,000, preferably 300,000 to 1,000,000, and more preferably 300,000 to 700,000. If the adhesive sheet has three or more layers, the weight-average molecular weight of the (meth)acrylic copolymer (A) contained in the resin composition forming the intermediate layer is typically 50,000 to 1,000,000, preferably 100,000 to 800,000, and more preferably 200,000 to 600,000.

[0068] The weight-average molecular weight is measured by the following method: A (meth)acrylic copolymer (A) is dissolved in tetrahydrofuran (THF) and used as the sample. The molecular weight distribution curve is measured using a gel permeation chromatography (GPC) analyzer (Tosoh Corporation "HLC-8320GPC") under the following conditions to determine the weight-average molecular weight (Mw): Guard column: TSKguardcolumnHXL Separation column: TSKgelGMHXL (4 columns) Temperature: 40°C Injection volume: 100 μL Polystyrene equivalent Solvent: THF Flow rate: 1.0 mL / min

[0069] The glass transition temperature (Tg) of the above (meth)acrylic copolymer (A) is preferably -50 to 30°C, more preferably -40 to 10°C, and even more preferably -30 to 5°C. When the glass transition temperature is below the upper limit, it tends to retain tack well, and when it is above the lower limit, it tends to have excellent bonding reliability.

[0070] The glass transition temperature mentioned above was determined by performing dynamic viscoelasticity measurements using a rheometer, reading the temperature at which Tanδ reached its maximum value from the resulting Tanδ spectrum, and defining it as the glass transition temperature (Tg).

[0071] From the viewpoint of adhesive strength, the resin composition forming this adhesive sheet preferably includes, in addition to the (meth)acrylic copolymer (A), a photopolymerization initiator (B) and a crosslinking agent (C).

[0072] [Photopolymerization initiator (B)] Any currently known photopolymerization initiator (B) can be used as appropriate, and among them, a photopolymerization initiator that is sensitive to ultraviolet light with a wavelength of 380 nm or less is preferred from the viewpoint of ease of controlling the crosslinking reaction.

[0073] Photopolymerization initiators (B) can be broadly classified into two types based on their radical generation mechanism: cleavage-type photopolymerization initiators, which can generate radicals by cleaving and decomposing the single bonds of the photopolymerization initiator itself; and hydrogen abstraction-type photopolymerization initiators, which can form an excited complex with a hydrogen donor in the system after being photoexcited, and transfer hydrogen from the hydrogen donor.

[0074] The aforementioned cleavage-type photopolymerization initiator decomposes into a different compound when radicals are generated by light irradiation, and once excited, it loses its function as a reaction initiator. Therefore, it does not remain as an active species in the adhesive sheet after the crosslinking reaction is completed, and there is no possibility of causing unexpected photodegradation of the adhesive sheet, which is preferable.

[0075] On the other hand, hydrogen abstraction type photopolymerization initiators are useful because, unlike cleavage type photopolymerization initiators, they do not produce decomposition products during radical generation reactions caused by irradiation with active energy rays such as ultraviolet light. Therefore, they are less likely to become volatile components after the reaction is complete, thus reducing damage to the substrate.

[0076] Examples of the cleavage-type photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, and oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl) Examples include propanone, methyl phenylglyoxylate, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and their derivatives. These may be used individually or in combination of two or more. Methyl phenylglyoxylate is preferred among them.

[0077] Examples of the hydrogen abstraction type photopolymerization initiators include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 2-methyl benzoylbenzoate, methyl benzoylformate, 4-methacryloyloxybenzophenone, bis(2-phenyl-2-oxoacetic acid)oxybisethylene, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, and their derivatives. These may be used individually or in combination of two or more. Among these, (meth)acryloyloxybenzophenone is preferred, and more preferably 4-methacryloyloxybenzophenone, 4-methylbenzophenone, and 2,4,6-trimethylbenzophenone. In other words, it is preferable that the adhesive sheet contains a polymer of (meth)acryloyloxybenzophenone.

[0078] The photopolymerization initiator (B) is not limited to the substances listed above. Furthermore, the photopolymerization initiator (B) may be either a cleavage-type photopolymerization initiator or a hydrogen abstraction-type photopolymerization initiator, or both may be used in combination.

[0079] The content of the photopolymerization initiator (B) is not particularly limited, but is usually 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass, and more preferably 0.3 to 3 parts by mass, per 100 parts by mass of the (meth)acrylic copolymer (A). By setting the content of the photopolymerization initiator (B) within the above range, an appropriate reaction sensitivity to active energy rays can be obtained.

[0080] [Crosslinking agent (C)] The crosslinking agent (C) is preferably a crosslinking agent having at least double bond crosslinking, and examples include a crosslinking agent having at least one crosslinkable functional group selected from (meth)acryloyl group, epoxy group, isocyanate group, carboxyl group, hydroxyl group, carbodiimide group, oxazoline group, aziridine group, vinyl group, amino group, imino group, and amide group. These may be one or a combination of two or more. Furthermore, the crosslinking agent (C) also includes embodiments in which the crosslinking agent (C) is chemically bonded to the (meth)acrylic copolymer (A).

[0081] Among these, crosslinking agents having (meth)acryloyl groups are preferred, and more preferably polyfunctional (meth)acrylates. Here, polyfunctional refers to having two or more crosslinkable functional groups. If necessary, it may have three or more, or four or more crosslinkable functional groups. Furthermore, the above crosslinkable functional groups may be protected with deprotectable protecting groups.

[0082] Examples of the above polyfunctional (meth)acrylates include 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, and bisphenol A polypropoxy di(meth)acrylate. (T) Acrylate, Bisphenol F Polyethoxydi(meth)acrylate, Ethylene Glycol Di(meth)acrylate, Neopentyl Glycol Di(meth)acrylate, Trimethylolpropane Trioxyethyl(meth)acrylate, ε-Caprolactone Modified Tris(2-Hydroxyethyl) Isocyanurate Tri(meth)acrylate, Pentaerythritol Tri(meth)acrylate, Propoxylated Pentaerythritol Tri(meth)acrylate, Ethoxylated Pentaerythritol Tri(meth)acrylate, Pentaerythritol Teto La(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, tris(acryloxyethyl) isocyanurate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol In addition to UV-curable polyfunctional (meth)acrylic monomers such as litol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, neopentyl glycol hydroxybivalate di(meth)acrylate, di(meth)acrylate of the ε-caprolactone adduct of neopentyl glycol hydroxybivalate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate, as well as polyester (meth)acrylate,Examples of polyfunctional (meth)acrylic oligomers include epoxy (meth)acrylate, urethane (meth)acrylate, and polyether (meth)acrylate. These may be used individually or in combination of two or more. Among these, UV-curable polyfunctional (meth)acrylic monomers are preferred, and propoxylated pentaerythritol tri(meth)acrylate is particularly preferred.

[0083] Furthermore, if the adhesive sheet has a layer structure of three or more layers, the crosslinking agent (C) is preferably included in the resin composition that forms the intermediate layer.

[0084] The content of the crosslinking agent (C) is preferably 0.5 to 50 parts by mass, more preferably 1 to 40 parts by mass, and even more preferably 5 to 30 parts by mass, per 100 parts by mass of the (meth)acrylic copolymer (A).

[0085] [Silane coupling agent (D)] Furthermore, it is preferable to incorporate a silane coupling agent (D) into the resin composition in order to improve adhesion to the components of the image display device, and especially to glass. In particular, it is preferable that the silane coupling agent (D) is included in the resin composition that forms the (meth)acrylic adhesive layer that comes into contact with the components of the image display device.

[0086] Examples of the silane coupling agent (D) include compounds having hydrolyzable functional groups such as vinyl groups, acryloxy groups, methacryloxy groups, amino groups, glycidyl groups, etc., as well as alkoxy groups. Among these, glycidyl group-containing silane coupling agents are preferred.

[0087] Examples of the silane coupling agent (D) include N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane. These may be used individually or in combination of two or more. Among these, 3-glycidoxypropyltriethoxysilane and 3-glycidoxypropyltrimethoxysilane are preferred because they exhibit good adhesion to image display device components and less discoloration such as yellowing.

[0088] The content of the silane coupling agent (D) is preferably 0.01 to 5 parts by mass, and more preferably 0.2 to 3.0 parts by mass, per 100 parts by mass of the (meth)acrylic copolymer (A).

[0089] Furthermore, coupling agents such as organic titanate compounds can also be effectively utilized, similar to silane coupling agents (D).

[0090] [Other Additives] In addition to the components listed above, the resin composition may contain other additives. Examples of these other additives include various additives such as light stabilizers, ultraviolet absorbers, metal deactivators, antioxidants, antistatic agents, hygroscopic agents, foaming agents, defoaming agents, inorganic particles, viscosity modifiers, tackifying resins, photosensitizers, and fluorescent agents, as well as reaction catalysts (tertiary amine compounds, quaternary ammonium compounds, tin laurate compounds, etc.). These may be used individually or in combination of two or more. Furthermore, other known components commonly used in resin compositions may be included as appropriate.

[0091] The above resin composition is obtained by mixing a (meth)acrylic copolymer (A), preferably a photopolymerization initiator (B), a crosslinking agent (C), a silane coupling agent (D), a metal corrosion inhibitor (E) if necessary, and other additives. The mixing method is not particularly limited, and the mixing order of each component is also not particularly limited. Furthermore, a heat treatment step may be included in the production of the resin composition, in which case it is desirable to mix each component of the resin composition beforehand before performing the heat treatment. In the above mixing, a masterbatch made by concentrating various mixed components may be used.

[0092] Furthermore, as mentioned above, the mixing method is not particularly limited, and for example, a universal kneader, planetary mixer, Banbury mixer, kneader, gate mixer, pressure kneader, three-roll mixer, two-roll mixer, etc., can be used. When mixing the components of the resin composition, a solvent may be used as needed, or it may be mixed as a solvent-free system. By making the resin composition solvent-free, no solvent remains, and the advantages of improved heat resistance and light resistance can be obtained.

[0093] [Release Film] Examples of materials for the release film used in this embodiment include films made from material resins such as polyester resin, polyolefin resin, polycarbonate resin, polystyrene resin, acrylic resin, triacetylcellulose resin, and fluororesin. Films coated with silicone resin for release treatment, or release paper, can also be appropriately selected and used. Among these, polyester resin and polyolefin resin are preferred, more preferably release-treated polyester resin or polyolefin resin, and even more preferably release-treated polyethylene terephthalate. Furthermore, the material resin of the release film may be used alone or in combination of two or more types.

[0094] [Method for Manufacturing Adhesive Sheets] The method for manufacturing the adhesive sheets described below is not limited to this method. Preferably, the adhesive sheets are manufactured as double-sided adhesive sheets with release films, wherein the release film described above is provided on at least one side of the adhesive sheet by the following steps. The pre-curing described below may be omitted.

[0095] First, a resin composition is heated and melted (hot melt), coated onto a release film, sandwiched between another release film, and heated to produce a single-layer adhesive sheet with double-sided release film. By preparing the required number of layers of this single-layer adhesive sheet with double-sided release film, peeling off the release film, and laminating the adhesive sheets, an adhesive sheet with double-sided release film having a multi-layer structure of two or more layers can be obtained. Note that the adhesive sheet with double-sided release film only needs to have the aforementioned release film on at least one side, preferably one side, of the final adhesive sheet, and the release film on the other side can be any known general release film.

[0096] It is preferable to pre-cur the resulting adhesive sheet with double-sided release film by crosslinking it with active energy rays so that it retains potential active energy ray reactivity, in other words, so that it retains active energy ray reactivity. When pre-curing, active energy rays can be irradiated through the release film to crosslink each layer with active energy rays, and the gel fraction can be set to the aforementioned range. In this case, it is possible to adjust the degree of active energy ray crosslinking (gel fraction) by controlling the amount of active energy ray irradiation, but as mentioned above, it is also possible to adjust the degree of active energy ray crosslinking (gel fraction) by partially blocking the active energy rays by irradiating with ultraviolet light through the release film.

[0097] Examples of the aforementioned active energy rays include ionizing radiation such as alpha rays, beta rays, neutron rays, and electron beams, as well as ultraviolet rays and visible light. Among these, ultraviolet rays are preferred from the viewpoint of suppressing damage to the components of the image display device and controlling the reaction.

[0098] Furthermore, in addition to the methods described above, adhesive sheets with double-sided release films having a multi-layer structure of two or more layers can also be manufactured by, for example, coating a resin composition onto a release film to form an adhesive sheet, and then coating another resin composition onto the formed adhesive sheet to form yet another adhesive sheet.

[0099] <Image display device components having a three-dimensional curved shape> In this embodiment, it is preferable that the image display device components used are at least a part of which have a three-dimensional curved shape. Here, a three-dimensional curved shape means a shape in which the cross-sectional shape of any surface that includes the normal to the surface is a curve. For example, a spherical curved surface is a three-dimensional curved surface in which the cross-section of the surface that includes the normal (a straight line in the radial direction) is a circular arc. Also, in the case of a display device (edge ​​display) in which the edges of a rectangle are curved downwards, if two adjacent edges are curved downwards, the corner portion where these two edges intersect has a three-dimensional curved shape. For example, in a four-sided edge display in which the entire periphery (all four sides) of a rectangular screen in plan view is curved, the four corner portions have a three-dimensional curved shape. Furthermore, in the edge display, the central part of the rectangular edge has a curved cross-section perpendicular to the edge, but a straight cross-section parallel to the edge, resulting in a "two-dimensional" curved shape at the center of the edge.

[0100] Examples of the image display device components include surface protection panels. Examples of surface protection panels include those made of materials such as thin glass or plastic, and referred to as "cover films," which are located on the outermost layer of the laminate for the image display device component to protect against external impacts. Furthermore, the curved surface component having a curved shape may have an integrated touch panel function, such as a touch-on-lens (TOL) type or an over-glass solution (OGS) type.

[0101] The radius of curvature of the image display device component is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less, from the viewpoint of fully utilizing the advantages of the present invention. The lower limit is usually 1 mm.

[0102] Furthermore, the curved member having the curved shape preferably has a stepped portion with a height difference of 5 μm or more, and more preferably has a stepped portion with a height difference of 7 μm or more, from the viewpoint of fully utilizing the advantages of the present invention. The upper limit is usually 50 μm. The image display device components are often printed for decorative or light-shielding purposes, and the thickness of this printing forms the stepped portion. Because this adhesive sheet has excellent step-following properties, it can be bonded without creating gaps even if such stepped portions are present. Furthermore, from the viewpoint of step-following properties, it is more preferable that this adhesive sheet has a multi-layer structure of two or more layers.

[0103] The thickness of the image display device component is typically 100 to 2000 μm, preferably 150 to 1500 μm, and more preferably 200 to 1000 μm.

[0104] <Image display device component with release film> An image display device component with a release film according to one embodiment of the present invention comprises the image display device component having a three-dimensional curved surface shape, the adhesive sheet, and the release film, and it is preferable that the release film, the adhesive sheet, and the image display device component having a three-dimensional curved surface shape are laminated in this order. As mentioned above, the adhesive sheet is usually manufactured as a double-sided adhesive sheet with a release film equipped with the release film. The manufacturing method of the image display device component with a release film of this embodiment will be described below.

[0105] The image display device component with release film of this embodiment is manufactured by the following steps 1 and 2. Step 1: A step of preparing the image display device component having a three-dimensional curved shape and an adhesive sheet with double-sided release film having a first release film and a second release film on both sides. Step 2: A step of peeling the first release film from the adhesive sheet with double-sided release film and attaching it to the image display device component having a three-dimensional curved shape to obtain an image display device component with a second release film.

[0106] Step 1 is a step of preparing an image display device component having at least a portion of a three-dimensional curved surface shape, and an adhesive sheet with double-sided release films having a first release film and a second release film on both sides.

[0107] Next, step 2 is the step of peeling the first release film from the adhesive sheet with double-sided release film and attaching it to an image display device component having at least a portion of a three-dimensional curved surface shape to obtain an image display device component with a second release film.

[0108] When peeling the first release film from the adhesive sheet with double-sided release film, it is sufficient to leave a second release film on the adhesive sheet having a 180° peeling force of 0.07 to 0.20 N / cm at a tensile speed of 300 mm / min.

[0109] Furthermore, there are no particular restrictions on the bonding method. Examples include atmospheric bonding using presses or rolls, vacuum bonding, and autoclave processing. These methods may be used individually or in combination of two or more.

[0110] The image display device component with release film obtained in this manner has excellent storage stability and bonding reliability, as the release film does not lift away from the adhesive sheet during storage.

[0111] <Laminate for Image Display Device> Furthermore, a laminate for an image display device can be obtained by performing the following steps 3 and 4 in this order using the image display device component with the release film. Step 3: A step of peeling the release film off the image display device component with the release film and bonding it to another image display device component. Step 4: A step of curing the adhesive sheet by irradiating it with active energy rays through an image display device component and / or other image display device components, at least a part of which has a three-dimensional curved shape, to obtain a laminate for an image display device.

[0112] In other words, the laminate for the image display device can be manufactured by having the following steps 1 to 4 in this order. Step 1: A step of preparing the image display device component having a three-dimensional curved surface shape and an adhesive sheet with double-sided release films having a first release film and a second release film on both sides. Step 2: A step of peeling the first release film from the adhesive sheet with double-sided release films and bonding it to the image display device component having a three-dimensional curved surface shape to obtain an image display device component with a second release film. Step 3: A step of peeling the second release film from the image display device component with a second release film and bonding it to the other image display device component. Step 4: A step of irradiating the image display device component having a three-dimensional curved surface shape and / or the other image display device component with active energy rays to obtain a laminate for the image display device.

[0113] As described above, steps 1 and 2 are as explained previously, so steps 3 and 4 will be explained below.

[0114] Step 3 is the step of peeling the second release film off the second release film attached to the image display device component and attaching it to another image display device component.

[0115] Other image display device components include, for example, glass, touch sensors, image display panels, polarizing films, phase difference films, and polyester resin films. These components for the image display device may be used individually or in combination of two or more types. Among these, polyester resin films are preferred in this embodiment.

[0116] Furthermore, there are no particular restrictions on the bonding method, and the method described in step 2 above can be used.

[0117] Step 4 is a step of curing the adhesive sheet by irradiating it with active energy rays through an image display device component having a three-dimensional curved shape and / or other image display device components to obtain an image display device component laminate.

[0118] Examples of the active energy rays include ionizing radiation such as alpha rays, beta rays, neutron rays, and electron beams, as well as ultraviolet rays and visible light. Among these, ultraviolet rays are preferred from the viewpoint of suppressing damage to the components of the image display device and controlling the reaction. Furthermore, the gel fraction of the adhesive sheet after curing is preferably within the range described above.

[0119] The laminate for image display device components obtained in this manner exhibits excellent curved surface bonding properties because, when the laminate consists of image display device components having curved portions, no air bubbles are generated, and no wrinkles are generated during bonding.

[0120] The present invention will be further described by the following embodiments. However, the present invention is not limited to the embodiments shown below.

[0121] First, we will describe the details of the raw materials used in the adhesive resin compositions prepared in the examples.

[0122] <(Meth)acrylic Copolymer (A)> ・(Meth)acrylic copolymer (A-1): Acrylic copolymer consisting of methyl acrylate (46% by mass) / 2-ethylhexyl acrylate (46% by mass) / N-vinylpyrrolidone (8% by mass) (weight average molecular weight: 230,000, Tg: 0°C) ・(Meth)acrylic copolymer (A-2): Acrylic copolymer consisting of methyl acrylate (19% by mass) / 2-ethylhexyl acrylate (64% by mass) / 2-hydroxyethyl acrylate (14% by mass) (weight average molecular weight: 460,000, Tg: -25°C) ・(Meth)acrylic copolymer (A-3): Acrylic copolymer consisting of 2-ethylhexyl acrylate (60% by mass) / butyl acrylate (15% by mass) / ethyl methacrylate (5% by mass) / 2-hydroxyethyl acrylate (20% by mass) (weight average molecular weight: 770,000, Tg: -28°C) - (Meth)acrylic copolymer (A-4): Acrylic copolymer consisting of methyl acrylate (14% by mass) / 2-ethylhexyl acrylate (46% by mass) / ethyl methacrylate (26% by mass) / 2-hydroxyethyl acrylate (14% by mass) (weight-average molecular weight: 240,000, Tg: -9°C) - (Meth)acrylic copolymer (A-5): Acrylic copolymer consisting of methyl acrylate (6% by mass) / methyl methacrylate (13% by mass) / 2-ethylhexyl acrylate (63.5% by mass) / N,N-dimethylacrylamide (17% by mass) / stearyl lauryl methacrylate (0.5% by mass) (weight-average molecular weight: 350,000, Tg: -5°C)

[0123] <Photopolymerization Initiators (B)> ・Photopolymerization Initiator (B-1): A mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (IGM's "Esacre TZT") ・Photopolymerization Initiator (B-2): 4-methacryloyloxybenzophenone (Shinryosha's "MBP") ・Photopolymerization Initiator (B-3): Methylbenzoyl formate (IGM's "Omnirad MBF")

[0124] <Crosslinking Agent (C)> ・Crosslinking agent (C-1): Polypropylene glycol #400 diacrylate ("NK Ester APG-400" manufactured by Shin Nakamura Chemical Co., Ltd.) ・Crosslinking agent (C-2): Monofunctional urethane acrylate containing an oxypropylene structure ("LD-301" manufactured by AGC Inc., weight-average molecular weight: approximately 10,000, Tg: -62°C) ・Crosslinking agent (C-3): Bifunctional urethane acrylate containing an oxypropylene structure ("Excelate SUA-008" manufactured by Asia Industries Co., Ltd.)

[0125] <Silane coupling agent (D)> ・Silane coupling agent (D-1): 3-Glycidoxypropyltrimethoxysilane

[0126] [Example 1] An acrylic polymer composition was prepared by uniformly mixing 100 parts by mass of (meth)acrylic copolymer (A-1), 0.83 parts by mass of photopolymerization initiator (B-1), 1.66 parts by mass of photopolymerization initiator (B-2), 1.5 parts by mass of crosslinking agent (C-1), and 0.2 parts by mass of silane coupling agent (D-1). Next, the acrylic polymer composition was spread into a sheet with a thickness of 63 μm on a silicone-release-treated release film 1 (Mitsubishi Chemical's PET film "Diafoil MRQ50") with a thickness of 50 μm. Furthermore, a silicone-release-treated release film 2 (Mitsubishi Chemical's PET film "Diafoil MRV75 (V03)") with a thickness of 75 μm was laminated on the sheet of acrylic polymer composition. This was made into a surface adhesive sheet (S-1), and two sheets were prepared, one for the surface and one for the back layer. Similarly, 100 parts by mass of (meth)acrylic copolymer (A-2), 3 parts by mass of photopolymerization initiator (B-1), and 25 parts by mass of crosslinking agent (C-2) were uniformly mixed to prepare an acrylic polymer composition. The acrylic polymer composition was unfolded into a sheet with a thickness of 24 μm. A release film 2 (PET film manufactured by Mitsubishi Chemical Corporation) with a thickness of 75 μm and treated with silicone release was laminated onto the sheet of acrylic polymer composition. This was designated as the adhesive sheet for the intermediate layer (S-2). First, the release film 2 of the first surface adhesive sheet (S-1) was removed and attached to the sheet-like acrylic polymer composition of the intermediate layer adhesive sheet (S-2). Next, the release film 2 of the second surface adhesive sheet (S-1) was removed, and the release film 2 of the intermediate layer adhesive sheet (S-2) was removed. The release surfaces of both sheets were then bonded together, creating adhesive sheets with an acrylic polymer composition layer thickness of 150 μm in the order of (S-1) / (S-2) / (S-1). Subsequently, using a high-pressure mercury lamp, the integrated light intensity at a wavelength of 365 nm was set to 1040 mJ / cm² from both surfaces of the sheet-like acrylic polymer composition. ２ By irradiating with active energy rays, an adhesive sheet with (double-sided) release film, consisting of a release film / adhesive sheet / release film, was obtained as in Example 1.

[0127] [Examples 2 to 4] A pressure-sensitive adhesive sheet with a release film was produced in the same manner as in Example 1, except that the layer structure was changed as shown in Table 1 below.

[0128] <Example 5> 100 parts by mass of a (meth)acrylic copolymer (A-4), 0.3 parts by mass of a photopolymerization initiator (B-2), 0.7 parts by mass of a photopolymerization initiator (B-3), and 0.2 parts by mass of a silane coupling agent (D-1) were uniformly mixed to prepare an acrylic polymer composition. Next, the acrylic polymer composition was spread in a sheet form on a 100 µm-thick release film subjected to silicone release treatment (a PET film manufactured by Mitsubishi Chemical Corporation) such that the thickness of the acrylic polymer composition became 150 µm. Further, a 75 µm-thick release film subjected to silicone release treatment (a PET film manufactured by Mitsubishi Chemical Corporation) was laminated on the sheet-shaped acrylic polymer composition. Thereafter, using a high-pressure mercury lamp, the accumulated light intensity at a wavelength of 365 nm was 2000 mJ / cm ２ , active energy rays were irradiated to both surfaces of the sheet-shaped acrylic polymer composition via the release films, to obtain the (double-sided) pressure-sensitive adhesive sheet with release films of Example 5, which is composed of release film / pressure-sensitive adhesive sheet / release film.

[0129] <Examples 6 to 10, Comparative Examples 1 and 2> A pressure-sensitive adhesive sheet with a release film was produced in the same manner as in Example 5, except that the blending amount of each component and the accumulated light intensity were changed as shown in Tables 2 and 4 below.

[0130] <Examples 11 to 13> A pressure-sensitive adhesive sheet with a release film was produced in the same manner as in Example 1, except that the blending amount of each component, the thickness (layer structure) of each layer, and the accumulated light intensity were changed as shown in Table 3 below.

[0131]

[0132]

[0133]

[0134]

[0135] [Physical Property Measurement and Evaluation] The adhesive sheets with release films prepared in the above examples and comparative examples were subjected to the following various measurements and evaluations. The results are shown in Table 5 below.

[0136] <Creep Test> The release film was removed from one side of the adhesive sheets with release film prepared in the examples and comparative examples, and the sheets were repeatedly laminated using a hand roller to adjust the thickness to approximately 0.8 to 1.0 mm. Samples were then punched out in a circular shape with a diameter of 8 mm. The obtained samples were placed on a rheometer (DHR-2, manufactured by T.A. Instruments), and the strain (amount of deformation in the creep test) (%) after 10 seconds was measured under the following conditions: measuring jig: 8 mm diameter parallel plate, temperature: 25°C, pressure: 10 kPa.

[0137] <Nanoindenter Test> For the adhesive sheets with release films prepared in the examples and comparative examples, a high-pressure mercury lamp was used to apply active energy rays with a wavelength of 365 nm, and the integrated light intensity was 3000 mJ / cm². ２After irradiation, the adhesive sheet with release film was removed from one side and bonded to the glass surface using a hand roller. Then, the release film on the other side was removed, and the following measurements were performed on the exposed adhesive surface. Using a nanoindenter device, a probe (indenter) was pressed vertically into the exposed surface of the adhesive sheet under the following conditions, and the nanoindenter modulus (storage modulus) was determined in nanoDMA mode, a nanoscale dynamic viscoelasticity evaluation method using the nanoindentation method. The nanoindentation method is a method for calculating mechanical quantities such as the modulus of elasticity from data obtained by continuously measuring load and displacement (load-displacement curve). [Equipment and Measurement Conditions] Equipment: Bruker nanoindenter "TI980" [Test Conditions] ・Measurement mode: nanoDMA (frequency sweep test) ・Indentation depth: 2800-3200 nm ・Set load: Load that brings the indentation depth within the above range ・Control mode: Open Loop ・Measurement locations: 3 (any location in the center of a 15 mm x 15 mm cut adhesive sheet) ・Measurement point spacing: 400-500 μm ・Measurement frequency: 100 Hz ・Measurement temperature: 20-25 °C ・Indenter: Diamond flat-end indenter (Part Number: TI-0084, tip diameter: 98.66 μm (measured by equipment manufacturer), cone angle: 61.53° (measured by equipment manufacturer)) ・The indenter was pressed in for 10 seconds, held for 30 seconds, and then the frequency sweep test was performed.[Test Parameters] ・Motor Settle Time: 0.0 sec ・Piezo Settle Time: 0.0 sec ・Pre-Load: 2.0 uN ・Drift Monitor Time: 0 sec ・Drift Analysis Time: 0 sec ・Drift Settle Time: 1 sec ・Begin Load Amplitude: Value obtained by dividing the set load by 20 ・Reference Frequency: 105 Hz [Analysis Method] ・Analysis software attached to the device: Tribo Scan Ver. In section 10.2.0.2, the Area Function of the flat-end indenter was calculated using the diameter of the tip of the flat-end indenter, and the measurement data was analyzed. Since the contact area of ​​a flat-end indenter with a large base diameter can be considered to be the area of ​​the indenter tip (circular in the case of a flat-end indenter) regardless of the contact depth, the Area Function is 7.6410 × 10. ９ nm ２ This was set as a fixed value. • Method of specifying the zero point: The point where the measurement begins in the load-displacement curve obtained under the above conditions was set as the zero point. • To calculate the storage modulus, the analysis application TriboIQ Indentation Explorer, Version: 1.0.0.2 (created by the equipment manufacturer), which is built into OriginPro 2019b (data analysis software from OriginLab), was used to calculate the storage modulus (E') obtained from measurements at three locations. １、 E' ２、 E' ３ The average value (E') ａｖ ) was calculated. Furthermore, when analyzed with the aforementioned analysis application, multiple storage moduli (E') were found for each frequency. ｉ The storage modulus (E') of each measurement position is output. １、 E' ２、 E' ３ ) are, respectively, E' ｉ The average value was used.

[0138] <Adhesion Test> For the adhesive sheets with release films prepared in the examples and comparative examples, one side of the release film was peeled off, a 100 μm thick PET film was roll-laminated to it, and the other side of the release film was peeled off and roll-laminated to soda-lime glass. After curing at 40°C for 3 hours, the adhesion strength was measured at a temperature of 23°C, a peeling angle of 180°, and a peeling speed of 60 mm / min. At this time, if the adhesive did not peel off at the interface between the adhesive and the glass, but peeled off while undergoing cohesive failure, "CF" was written next to the numerical value.

[0139] <Tack Test> For the adhesive sheets with release films prepared in the examples and comparative examples, the release film was removed at the time of measurement. In accordance with JIS Z0237, the adhesive sheet, which was 25 μm thick and 100 mm long, was placed on an inclined plate at a 30° angle in an atmosphere of 23°C and 50% RH, with the PET film substrate in contact with the inclined plate, and the tack was measured by placing a ball on the upper edge of the inclined plate.

[0140] <Gel Fraction> [Gel fraction before UV curing: precure] The release film was peeled off from the adhesive sheets with release film prepared in the examples and comparative examples, and a piece of adhesive sheet weighing approximately 0.1 g was taken. The taken piece of adhesive sheet was wrapped in a pre-formed bag-shaped SUS mesh (#150) of mass (X), the opening of the bag was closed to form a sample, and the mass (Y) of the sample was measured. The sample was immersed in ethyl acetate and stored in the dark at a temperature of 23°C for 24 hours. After that, the sample was removed, heated at a temperature of 70°C for 4.5 hours to evaporate the ethyl acetate, and the mass (Z) of the dried sample was measured. The gel fraction was calculated from each measured mass using the following formula: Gel fraction (%) = [(Z - X) / (Y - X)] × 100

[0141] [Gel fraction after UV curing: postcure] The adhesive sheets with release films prepared in the examples and comparative examples were subjected to UV curing using a high-pressure mercury lamp with an integrated light intensity of 3000 mJ / cm² at 365 nm. ２ To achieve this, the adhesive sheet was irradiated with ultraviolet light through a release film to cure it. The gel fraction after curing with active energy rays was determined for the cured adhesive sheet using the same procedure as described above for evaluating the gel fraction.

[0142] <Indentation Resistance> One side of the release film was peeled off from the double-sided release film adhesive sheets prepared in the examples and comparative examples, and roll-laminated to soda-lime glass. The other side of the release film was then peeled off, and a 50 μm copper foil was roll-laminated to it, and autoclaving (60°C, gauge pressure 0.2 MPa, 20 minutes) was performed. Next, a 500 g load from a 10 mm diameter iron ball was applied to the copper foil surface for 10 seconds. After that, indentation resistance was evaluated by visual observation according to the following evaluation criteria. [Evaluation Criteria] A (Excellent): No indentations (dents or distortions) were observed at all in the pressed area. B (Good): Indentations were not visible to the naked eye, or were only slightly observed in some areas. C (Fair): Indentations were visible to the naked eye, but were at a practically acceptable level. D (Poor): The uneven shape was clearly visible.

[0143] <Wrinkles during lamination> One side of the release film was peeled off from the double-sided release film-attached adhesive sheets prepared in the examples and comparative examples, and a PET film with a thickness of 75 μm was laminated to it. The other side of the release film was then peeled off, and a cover glass (a component of an image display device with a three-dimensional curved shape: radius of curvature 5 mm, height difference 15 μm) used in the Mate 60 Pro (manufactured by Huawei) was laminated using a vacuum laminating machine under the following conditions, and the wrinkles during lamination were evaluated according to the following evaluation criteria. - Indentation stress: 320 kg - Indentation time: 3 seconds - Autoclave pressure: 0.6 MPa - Autoclave temperature: 45 °C - Autoclave time: 15 minutes [Evaluation criteria] A (Excellent): No wrinkles were observed in the adhesive sheet. B (Good): Slight wrinkles were observed in some parts of the adhesive sheet. C (Fair): Wrinkles were observed in the adhesive sheet, but at a level that was practically acceptable. D (Poor): Wrinkles were clearly visible on the adhesive sheet.

[0144] <Rebound bubbles during lamination> One side of the release film was peeled off from the double-sided release film adhesive sheets prepared in the examples and comparative examples, and a 75 μm thick PET film was laminated to it. The other side of the release film was then peeled off, and a cover glass (a component of an image display device with a three-dimensional curved shape) used in the Mate 60 Pro (manufactured by Huawei) was laminated using a vacuum laminating machine under the following conditions, and bubbles during lamination were evaluated according to the following evaluation criteria. - Indentation stress: 320 kg - Indentation time: 3 seconds - Autoclave pressure: 0.6 MPa - Autoclave temperature: 45 °C - Autoclave time: 15 minutes [Evaluation criteria] AA (Outstanding): No bubbles were observed at all, and extremely high lamination reliability was shown even in three-dimensional curved areas (corners, etc.). A (Excellent): No bubbles were observed at all, and good lamination reliability was shown. B (Good): No bubbles were observed. C (Fair): A small amount of air bubbles were observed on the curved surface, but it was at a level that was acceptable for practical use. D (Poor): Clear air bubbles were observed on the curved surface.

[0145]

[0146] The adhesive sheets of Examples 1 to 13 exhibited excellent curved surface bonding properties because, as a result of having physical properties such as adhesive strength with the bonding member and deformation amount in creep tests being within an appropriate range, no air bubbles were generated when the laminate for image display device components, which consisted of three-dimensional curved surface components, were formed, and no wrinkles were generated during bonding. Furthermore, the adhesive sheets of Examples 1 to 4 and Examples 11 to 13, in particular, exhibited excellent bonding reliability due to their multi-layer structure of two or more layers. On the other hand, the laminate for image display device components using Comparative Example 1 exhibited poor curved surface bonding properties because the deformation amount in the creep test was less than 23%, resulting in wrinkles in the bonding member. Moreover, the laminate for image display device components using Comparative Example 2 exhibited poor indentation resistance due to its low nanoindenter modulus and adhesive strength of less than 10 N / cm, resulting in air bubbles in the bonding member and poor curved surface bonding properties.

[0147] While the above embodiments illustrate specific forms of the present invention, these embodiments are merely illustrative and should not be interpreted restrictively. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0148] The adhesive sheet of the present invention offers excellent adhesion reliability to image display devices having at least a portion of a three-dimensional curved surface shape, and can be suitably used for spherical displays and four-sided edge displays.

[0149] 10: Laminate for image display device configuration 11: Image display device component having a three-dimensional curved surface shape 12: Other image display device component 20: Adhesive sheet 21: Outermost layer (adhesive layer) 22: Intermediate layer 23: Innermost layer (adhesive layer)

Claims

1. A laminate for an image display device comprising an image display device component having a three-dimensional curved shape, an adhesive sheet, and other image display device components, wherein the image display device component having a three-dimensional curved shape is laminated with the other image display device components via the adhesive sheet, and the adhesive sheet satisfies the following (1) to (4): (1) The amount of deformation in a creep test under the conditions of 25°C, 10 kPa, and 10 seconds is 23% or more. (2) The integrated light amount of active energy rays with a wavelength of 365 nm using a high-pressure mercury lamp is 3000 mJ / cm ２ The nanoindenter modulus of the adhesive sheet surface after irradiation is 2 MPa or higher. (3) The adhesion strength to glass in the 180° peel test is 10 N / cm or higher. (4) The tack in the ball tack test is 3 or less.

2. The laminate for image display device according to claim 1, wherein the adhesive sheet is formed from a resin composition containing a (meth)acrylic copolymer (A).

3. The laminate for image display device according to claim 2, wherein the (meth)acrylic copolymer (A) is obtained by polymerizing a copolymer component containing 40% by mass or more of a branched alkyl ester monomer (meth)acrylate.

4. The laminate for image display device according to claim 2, wherein the (meth)acrylic copolymer (A) is obtained by polymerizing a copolymer component containing an amide group-containing monomer and a long-chain alkyl group-containing (meth)acrylate alkyl ester monomer having 10 or more carbon atoms.

5. The laminate for image display device according to claim 2, wherein the resin composition contains a hydrogen abstraction type photopolymerization initiator.

6. The laminate for image display device according to claim 2, wherein the resin composition contains a glycidyl group-containing silane coupling agent.

7. The laminate for image display device according to claim 1, wherein the adhesive sheet contains a polymer of (meth)acryloyloxybenzophenone.

8. The laminate for image display device configuration according to claim 1, wherein the adhesive sheet has a multilayer structure of at least two layers.

9. The laminate for image display device according to claim 1, wherein the gel fraction of the adhesive sheet is 75% or more.

10. Apply an active energy ray with a wavelength of 365 nm to the adhesive sheet, accumulating to a total light intensity of 3000 mJ / cm². ２ The laminate for an image display device according to claim 1, wherein the difference between the gel fraction when cured by irradiation and the gel fraction before irradiation with the active energy ray is 10% or more.

11. The laminate for image display device configuration according to claim 1, wherein the image display device component having a three-dimensional curved surface shape has a curved surface shape with a radius of curvature of 10 mm or less.

12. The laminate for image display device configuration according to claim 1, wherein the image display device component having a three-dimensional curved surface shape has a stepped portion with a height difference of 5 μm or more on the surface in contact with the adhesive sheet.

13. A method for manufacturing a laminate for an image display device according to claim 1, comprising the following steps 1 to 4 in this order: Step 1: A step of preparing an image display device component having a three-dimensional curved shape and an adhesive sheet with double-sided release films having a first release film and a second release film on both sides. Step 2: A step of peeling the first release film from the adhesive sheet with double-sided release films and bonding it to the image display device component having a three-dimensional curved shape to obtain an image display device component with a second release film. Step 3: A step of peeling the second release film from the image display device component with a second release film and bonding it to the other image display device component. Step 4: A step of irradiating the image display device component having a three-dimensional curved shape and / or the other image display device component with active energy rays to obtain a laminate for an image display device.

14. An image display device component with a release film, comprising an image display device component having a three-dimensional curved surface shape, an adhesive sheet, and a release film, wherein the release film, the adhesive sheet, and the image display device component having a three-dimensional curved surface shape are laminated in this order, and the adhesive sheet satisfies the following (1) to (4): (1) The amount of deformation in a creep test under the conditions of 25°C, 10 kPa, and 10 seconds is 23% or more. (2) The integrated light amount of active energy rays with a wavelength of 365 nm using a high-pressure mercury lamp is 3000 mJ / cm ２ The nanoindenter modulus of the adhesive sheet surface after irradiation is 2 MPa or higher. (3) The adhesion strength to glass in the 180° peel test is 10 N / cm or higher. (4) The tack in the ball tack test is 3 or less.

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