Optical laminate and image display device

Abstract

To provide an optical laminate which comprises an adhesive sheet and an optical film and is suitable for use in organic EL display devices (OLEDs).SOLUTION: An optical laminate provided herein comprises an adhesive sheet and an optical film. The optical laminate includes a layer (A) containing an ultraviolet absorbent and has a transmittance of 5% or less for light of 380 nm-wavelength. The optical laminate consists of two or more layers (A).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical laminate and an image display device. [Background technology]

[0002] In recent years, image display devices, such as electroluminescence (EL) display devices and liquid crystal display devices, have rapidly become popular. These image display devices typically have a laminated structure including an image-forming layer, such as an EL light-emitting layer or a liquid crystal layer, and an optical laminate including an optical film and an adhesive sheet. The adhesive sheet is mainly used to bond between films included in the optical laminate, or to bond between the image-forming layer and the optical laminate. Examples of optical films include polarizers, polarizer protective films, and retardation films. Patent Document 1 discloses an example of an optical laminate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-031214 Summary of the Invention [Problem to be solved by the invention]

[0004] In organic electroluminescent display devices (hereinafter referred to as OLED), which are a type of EL display device, the organic EL light-emitting layer is easily deteriorated by ultraviolet rays contained in external light. Furthermore, as their use in mobile devices such as smartphones and smartwatches becomes more widespread, optical laminates for OLEDs are being required to be even thinner. Patent Document 1 does not take this into consideration.

[0005] An object of the present invention is to provide a pressure-sensitive adhesive composition suitable for use in OLEDs. [Means for solving the problem]

[0006] The present invention provides An optical laminate comprising a pressure-sensitive adhesive sheet and an optical film, The optical laminate is A layer A containing an ultraviolet absorber, and It has a transmittance of 5% or less for light with a wavelength of 380 nm, The number of layers A included in the optical laminate is 2 or more. optical laminate, to provide.

[0007] In another aspect, the present invention provides a method for producing a composition comprising: An image forming layer and an optical laminate bonded to the image forming layer, an image display device, wherein the optical laminate is the optical laminate of the present invention; to provide. [Effects of the Invention]

[0008] The optical laminate of the present invention suppresses the transmission of ultraviolet light with wavelengths of 380 nm or less, thereby reducing the amount of ultraviolet light that reaches the organic EL light-emitting layer. Furthermore, while the ability to suppress the transmission of ultraviolet light is usually reduced in thinner optical laminates, the optical laminate of the present invention, which includes two or more layers A containing an ultraviolet absorber, can ensure ultraviolet absorption ability by distributing it among the respective layers A, thereby meeting the demand for even thinner structures. Therefore, the optical laminate of the present invention is suitable for use in OLEDs. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. [Figure 3] FIG. 3 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. [Figure 4] FIG. 4 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. [Figure 5] FIG. 5 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. [Figure 6] FIG. 6 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. [Figure 7] FIG. 7 is a cross-sectional view schematically showing an example of an image display device of the present invention. [Figure 8] FIG. 8 is a cross-sectional view schematically showing an example of an image display device of the present invention. [Figure 9] FIG. 9 is a cross-sectional view schematically showing an example of an image display device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, but is not limited to the following embodiments.

[0011] In this specification, "(meth)acrylic" means acrylic and methacrylic, and "(meth)acrylate" means acrylate and methacrylate.

[0012] [Optical laminate] The optical laminate of this embodiment includes a pressure-sensitive adhesive sheet and an optical film. The optical laminate of this embodiment also includes a layer A containing an ultraviolet absorber, and the number of layers A included in the optical laminate is two or more. The layer A may be included in the pressure-sensitive adhesive sheet or the optical film. The layer A may also be included in an additional member included in the optical laminate in addition to the pressure-sensitive adhesive sheet and the optical film. Examples of the additional member include a protective layer such as a hard coat layer, and a functional layer such as a conductive primer layer.

[0013] The optical laminate of this embodiment has a transmittance of 5% or less, expressed as a transmittance for light with a wavelength of 380 nm (hereinafter referred to as T380). T380 may be 4% or less, or even 3.5% or less. T380 is the transmittance in the lamination direction of the optical laminate. The lower limit of T380 is, for example, 0.01% or more.

[0014] An example of the optical laminate of this embodiment is shown in FIG. 1. The optical laminate 10 (10A) in FIG. 1 includes an adhesive sheet 1 (first adhesive sheet 1A) and an optical film 2. The adhesive sheet 1 and the optical film 2 are bonded to each other. The optical laminate 10A can be used as an optical film with an adhesive sheet that can be attached to an object (for example, an image forming layer of an image display device) via the adhesive sheet 1. In the optical laminate 10A, for example, both the adhesive sheet 1 and the optical film 2 include a layer A containing an ultraviolet absorber. In this case, if the adhesive sheet 1 is a single layer, the adhesive sheet 1 itself is layer A. Furthermore, if the optical film 2 is a single layer, the optical film 2 itself is layer A.

[0015] Examples of the optical film 2 include a polarizer, a polarizer protective film, a retardation layer, a shatterproof film, and a transparent resin film. However, the optical film 2 is not limited to the above examples. The optical laminate 10A may include two or more optical films 2.

[0016] A polarizer is typically a polyvinyl alcohol (PVA) film in which iodine has been oriented by stretching, such as in-air stretching (dry stretching) or stretching in boric acid water. A retardation layer is a retardation control layer that has birefringence in the in-plane direction and / or the thickness direction. Examples of retardation layers include retardation films, typically formed from stretched resin films, and retardation coating layers, typically formed from a layer (retardation liquid crystal layer) formed by orienting and fixing a liquid crystal material.

[0017] In the optical laminate 10A, ultraviolet absorption ability is dispersed in two or more layers A, for example, the pressure-sensitive adhesive sheet 1 and the optical film 2. In other words, the amount of ultraviolet absorber required to ensure a T380 of 5% or less for the optical laminate 10A is dispersed across multiple components. Therefore, the optical laminate 10A is suitable for reducing the amount of ultraviolet absorber incorporated into each component while still maintaining the required ultraviolet absorption ability. Reducing the amount of ultraviolet absorber incorporated can, for example, suppress aggregation or precipitation of the ultraviolet absorber, or plasticization of layers due to the incorporation of a large amount, and can contribute to suppressing deterioration in the properties of each component (typically, adhesive properties and optical properties) due to these phenomena.

[0018] Another example of the optical laminate of the present embodiment is shown in Fig. 2. The optical laminate 10B in Fig. 2 has a laminated structure in which a first pressure-sensitive adhesive sheet 1A, a polarizer protective film 2B, a polarizer 2A, and a polarizer protective film 2B are laminated in this order. The polarizer 2A and a pair of polarizer protective films 2B sandwiching the polarizer 2A constitute a polarizing plate 3. The polarizer 2A and the polarizer protective film 2B can be bonded by a known method. In the optical laminate 10B, for example, at least two members selected from the first pressure-sensitive adhesive sheet 1A, the polarizer protective film 2B, the polarizer 2A, and the polarizer protective film 2B may each contain layer A, and each of the pair of polarizer protective films 2B may also contain layer A.

[0019] Another example of the optical laminate of this embodiment is shown in FIG. 3. The optical laminate 10C in FIG. 3 has a layered structure in which a first pressure-sensitive adhesive sheet 1A, a retardation layer 2C, a second pressure-sensitive adhesive sheet 1B, a polarizer 2A, and a polarizer protective film 2B are laminated in this order. The first pressure-sensitive adhesive sheet 1A can function as a pressure-sensitive adhesive sheet for attaching the optical laminate 10C. The second pressure-sensitive adhesive sheet 1B can function as an interlayer pressure-sensitive adhesive sheet that bonds the retardation layer 2C and the polarizer protective film 2B (polarizing plate 3). In the optical laminate 10C, for example, at least two members selected from the first pressure-sensitive adhesive sheet 1A, the retardation layer 2C, the second pressure-sensitive adhesive sheet 1B, the polarizer 2A, and the polarizer protective film 2B may each contain layer A, and the second pressure-sensitive adhesive sheet 1B and the polarizer protective film 2B may each contain layer A. The retardation layer 2C may be selected and arranged so that a laminate of the retardation layer 2C, the second pressure-sensitive adhesive sheet 1B, the polarizer 2A, and the polarizer protective film 2B functions as a circular polarizer.

[0020] Another example of the optical laminate of this embodiment is shown in Fig. 4. The optical laminate 10D of Fig. 4 has a layered structure in which a first pressure-sensitive adhesive sheet 1A, a retardation layer 2C, a second pressure-sensitive adhesive sheet 1B, a polarizer protective film 2B, a polarizer 2A, and a polarizer protective film 2B are laminated in this order. In the optical laminate 10D, for example, at least two members selected from the first pressure-sensitive adhesive sheet 1A, the retardation layer 2C, the second pressure-sensitive adhesive sheet 1B, the polarizer protective film 2B, the polarizer 2A, and the polarizer protective film 2B include layer A. Each of the pair of polarizer protective film 2B and retardation layer 2C may include layer A. In other words, the number of layers A included in the optical laminate of this embodiment may be three or more.

[0021] Another example of the optical laminate of this embodiment is shown in FIG. 5. The optical laminate 10E in FIG. 5 includes an optical film 2, which is a polarizer 2A, a polarizer protective film 2B, and a retardation layer 2C; a first pressure-sensitive adhesive sheet 1A and a second pressure-sensitive adhesive sheet 1B, which are pressure-sensitive adhesive sheets 1; and a protective layer 4, which is an additional component. The optical laminate 10E has a layered structure including the first pressure-sensitive adhesive sheet 1A, the retardation layer 2C, the second pressure-sensitive adhesive sheet 1B, the polarizer 2A, the polarizer protective film 2B, and the protective layer 4. In this layered structure, the first pressure-sensitive adhesive sheet 1A, the retardation layer 2C, the second pressure-sensitive adhesive sheet 1B, the polarizer 2A, the polarizer protective film 2B, and the protective layer 4 are layered in this order. In the optical laminate 10E, for example, at least two components selected from the first pressure-sensitive adhesive sheet 1A, the retardation layer 2C, the second pressure-sensitive adhesive sheet 1B, the polarizer 2A, the polarizer protective film 2B, and the protective layer 4 include layer A. The polarizer protective film 2B may include layer A. The polarizer protective film 2B and the second pressure-sensitive adhesive sheet 1B may each include layer A. The protective layer 4 and the polarizer protective film 2B may each include layer A. The protective layer 4, the polarizer protective film 2B, and the second pressure-sensitive adhesive sheet 1B may each include layer A. The protective layer 4, the polarizer protective film 2B, and the first pressure-sensitive adhesive sheet 1A may each include layer A. The protective layer 4 is, for example, a hard coat layer. When the hard coat layer includes layer A, reducing the amount of ultraviolet absorber added can contribute to, for example, suppressing a decrease in the hardness of the hard coat layer.

[0022] When the optical laminate 10 includes a first pressure-sensitive adhesive sheet 1A and a second pressure-sensitive adhesive sheet 1B (for example, optical laminates 10C, 10D, and 10E), the second pressure-sensitive adhesive sheet 1B may include layer A, or only the second pressure-sensitive adhesive sheet 1B may include layer A. A touch panel is sometimes incorporated into an OLED, typically in the case of an OLED in a smartphone or smartwatch. The touch panel is disposed, for example, between the image-forming layer and the optical laminate 10 (on-cell, etc.), and typically includes a conductive layer that is susceptible to corrosion, such as a metal layer. An embodiment in which the second pressure-sensitive adhesive sheet 1B, which is physically separated from the touch panel, includes layer A is suitable for suppressing corrosion of the touch panel by an ultraviolet absorber.

[0023] Layer A contains an ultraviolet absorber. The ultraviolet absorber's maximum absorption wavelength in its absorption spectrum may be 320 nm to 380 nm, 330 nm to 375 nm, 335 nm to 370 nm, or even 340 nm to 370 nm. Furthermore, the ultraviolet absorber may have an absorbance of 0.1 or greater, or even 0.2 or greater, across the wavelength range of 320 nm to 370 nm in an absorption spectrum normalized to a maximum value of 1. These ultraviolet absorbers are particularly suitable for suppressing ultraviolet degradation of OLEDs. Note that ultraviolet light with wavelengths of 320 nm or less is contained in less ambient light than ultraviolet light with wavelengths of 320 nm or greater, and more of it can be absorbed by layers located closer to the ambient light (the viewing side) than the organic EL light-emitting layer. Therefore, there is relatively little need to consider OLED degradation due to ambient light. The absorption spectrum can be evaluated, for example, by spectrophotometrically measuring a solution in which the ultraviolet absorber is dissolved in a solvent such as isopropyl alcohol at a concentration of 0.001 wt %.

[0024] Examples of ultraviolet absorbers include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Each ultraviolet absorber is a compound having a triazine skeleton, a benzotriazole skeleton, a benzophenone skeleton, an oxybenzophenone skeleton, a salicylic acid ester structure, and a cyanoacrylate structure, respectively. The ultraviolet absorber is preferably a triazine-based or benzotriazole-based, more preferably a triazine-based. The triazine-based ultraviolet absorber may have at least one, preferably two, more preferably three hydroxyphenyl groups and / or alkoxy (methoxy, ethoxy, propoxy, etc.) phenyl groups in one molecule. The triazine-based ultraviolet absorber may also have at least one, preferably two, hydroxyphenyl groups in one molecule. These ultraviolet absorbers, especially those having three hydroxyphenyl groups and / or alkoxyphenyl groups in one molecule, are particularly suitable for suppressing ultraviolet degradation of OLEDs, since they exhibit little variation in absorbance in the wavelength range of 320 nm or more and 370 nm or less.

[0025] Examples of triazine-based ultraviolet absorbers include 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN 460, manufactured by BASF), reaction products of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (TINUVIN400, manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl) The compounds are 2-(4,6-diphenyl-1,3,5-triazine and (2-ethylhexyl)glycidic acid ester reaction product (TINUVIN 405, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (TINUVIN 1577, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADK STAB LA46, manufactured by ADEKA), and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN 479, manufactured by BASF).

[0026] Examples of benzotriazole-based ultraviolet absorbers include 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), ester compound of benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 branched and linear alkyl) (TINUVIN 384-2, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 900, manufactured by BASF), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (TINUVIN 1130, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN P, manufactured by BASF), 2(2H-benzotriazol-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN234, manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN326, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN328, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol ( TINUVIN 329, manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate with polyethylene glycol 300 (TINUVIN 213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.).

[0027] Layer A may contain one or more ultraviolet absorbers.

[0028] The amount of ultraviolet absorber in Layer A is, for example, less than 20 parts by weight, and may be 15 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, or even 6 parts by weight or less, relative to 100 parts by weight of the main component of Layer A (for Layer A contained in the pressure-sensitive adhesive sheet 1, for example, the (meth)acrylic polymer (A) described below). The lower limit of the amount is, for example, 0.1 parts by weight or more. In this specification, the term "main component" refers to the component with the highest content. The content of the main component is, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 75% by weight or more, or even 80% by weight or more.

[0029] The optical laminate 10 is 9×10 11 The optical laminate may include a layer B having a surface resistivity of Ω / □ or less. The layer B may be included in a pressure-sensitive adhesive sheet or an optical film. The layer B may also be included in a further member provided in the optical laminate in addition to the pressure-sensitive adhesive sheet and the optical film. When the member including the layer B is a single layer, the member itself is the layer B.

[0030] In a typical example, an OLED incorporating a touch panel may emit unintended light when a finger touches the display portion of the OLED to operate the device. According to the inventors' investigations, this light emission is primarily due to static electricity generated by contact. Layer B, which has a surface resistivity of a predetermined value or less, can contribute to suppressing this charging. From this perspective, the optical laminate 10 including Layer B is particularly suitable for use in OLEDs.

[0031] Layer A and layer B may be the same layer. In other words, the optical laminate 10 contains an ultraviolet absorber and 11 It may have a layer having a surface resistivity of Ω / □ or less. This layer may be included in the pressure-sensitive adhesive sheet 1. Layer A and Layer B may be different layers.

[0032] When the optical laminate 10 includes multiple pressure-sensitive adhesive sheets 1, one pressure-sensitive adhesive sheet 1 selected from the multiple pressure-sensitive adhesive sheets 1 may include layer B, or two or more pressure-sensitive adhesive sheets 1 may include layer B. For example, when the optical laminate 10 includes a first pressure-sensitive adhesive sheet 1A and a second pressure-sensitive adhesive sheet 1B as in the optical laminates 10D and 10E shown in FIGS. 4 and 5, at least one selected from the first pressure-sensitive adhesive sheet 1A and the second pressure-sensitive adhesive sheet 1B may include layer B, or the second pressure-sensitive adhesive sheet 1B may include layer B, or only the second pressure-sensitive adhesive sheet 1B may include layer B. A surface resistivity of a predetermined value or less can be achieved, for example, by including at least one selected from an antistatic agent and a conductive polymer. Meanwhile, a touch panel may be incorporated into an OLED. An embodiment in which the second pressure-sensitive adhesive sheet 1B, which is physically separated from the touch panel, includes layer B is suitable for suppressing corrosion of the touch panel caused by the antistatic agent or the conductive polymer.

[0033] When optical laminate 10E in FIG. 5 includes layer B, protective layer 4 and polarizer protective film 2B may include layer A, or second pressure-sensitive adhesive sheet 1B may include layer A.

[0034] The surface resistivity of layer B is 9 x 10 11 Ω / □ or less, 7×10 11 Ω / □ or less, 5×10 11 Ω / □ or less, 3×10 11 Ω / □ or less, 1×10 11 Ω / □ or less, 9×10 10 Ω / □ or less, 5×10 10 Ω / □ or less, 3×10 10 Ω / □ or less, 1×10 10 Ω / □ or less, 9×10 9 Ω / □ or less, 5×10 9 Ω / □ or less, 3×10 9 Ω / □ or less, 2×10 9 Ω / □ or less, even 1×10 9 The lower limit of the surface resistivity may be, for example, 1×10 4 The surface resistivity of Layer B within the above range can contribute to, for example, more reliable operation of the touch panel.

[0035] The surface resistivity of Layer B can be evaluated, for example, by a high resistance resistivity meter (for example, Hiresta series manufactured by Mitsubishi Chemical Analytech).

[0036] Layer B contains, for example, at least one selected from an antistatic agent and a conductive polymer. An example of the antistatic agent is an ionic compound such as a salt. The ionic compound may be an ionic liquid that is liquid at room temperature (25°C). Compared to, for example, conductive fine particles, ionic compounds usually have higher compatibility with the main component of Layer B (e.g., the (meth)acrylic polymer (A) in Layer B contained in the pressure-sensitive adhesive sheet 1), and are suitable for forming Layer B with excellent optical transparency. Layer B may be substantially free of conductive fine particles. In this specification, "Layer B is substantially free of a certain component" means that the content of that component is 0.5 parts by weight or less, preferably 0.1 parts by weight or less, more preferably 0.05 parts by weight or less, and even more preferably 0.01 parts by weight or less, based on 100 parts by weight of the content of the main component of Layer B.

[0037] Examples of cations constituting the ionic compound include metal ions and onium ions. Examples of metal ions include alkali metal ions and alkaline earth metal ions. Examples of alkali metal ions include lithium ions, sodium ions, and potassium ions, and may also include lithium ions. Examples of alkaline earth metal ions include magnesium ions and calcium ions. However, the metal ions are not limited to the above examples.

[0038] Examples of onium ions are ions in which at least one atom selected from nitrogen, phosphorus, and sulfur atoms is positively charged. The onium ion may be an organic ion, and in this case, it may be an ion of a cyclic organic compound or an ion of a chain organic compound. The cyclic organic compound may be aromatic or non-aromatic, such as an aliphatic one. Examples of onium ions include quaternary ammonium ions such as N-ethyl-N,N-dimethyl-N-(2-methoxyethyl)ammonium ion, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium ion, N-ethyl-N,N-dimethyl-N-propylammonium ion, N-methyl-N,N,N-trioctylammonium ion, N,N,N-trimethyl-N-propylammonium ion, tetrabutylammonium ion, tetramethylammonium ion, tetrahexylammonium ion, and N-methyl-N,N,N-tributylammonium ion. pyridinium ions such as N-alkylpyridinium ions substituted with an alkyl group having 4 to 16 carbon atoms; imidazolium ions such as 1,3-alkylmethylimidazolium ions substituted with an alkyl group having 2 to 10 carbon atoms (e.g., ethyl group) and 1,2-dimethyl-3-alkylimidazolium ions substituted with an alkyl group having 2 to 10 carbon atoms; phosphonium ions, pyrrolidinium ions, pyridazinium ions, pyrimidinium ions, pyrazinium ions, pyrazolium ions, thiazolium ions, oxazolium ions, triazolium ions, and piperidinium ions. However, the onium ions are not limited to the above examples.

[0039] Examples of anions that make up ionic compounds are fluoride, chloride, bromide, iodide, perchlorate (ClO4 - ), hydroxide (OH - ), carbonate (CO3 2- ), nitrate (NO3 - ), sulfonates (SO4 - ), methyl benzenesulfonate (CH3(C6H4)SO3 - ), p-toluenesulfonate (CH3C6H4SO3 -), carboxybenzenesulfonate (COOH(C6H4)SO3 - ), trifluoromethanesulfonate (CF3SO2 - ), benzoate (C6H5COO - ), acetate (CH3COO - ), trifluoroacetate (CF3COO - ), tetrafluoroborate (BF4 - ), tetrabenzyl borate (B(C6H5)4 - ), hexafluorophosphate (PF6 - ), trispentafluoroethyl trifluorophosphate (P(C2F5)3F3 - ), bisfluorosulfonylimide (N(SO2F)2 - ), bistrifluoromethanesulfonylimide (N(SO2CF3)2 - ), bispentafluoroethanesulfonylimide (N(SOC2F5)2 - ), bispentafluoroethanecarbonyl imide (N(COC2F5)2 - ), bisperfluorobutanesulfonylimide (N(SO2C4F9)2 - ), bisperfluorobutanecarbonyl imide (N(COC4F9)2 - ), Tristrifluoromethanesulfonylmethide (C(SO2CF3)3 - ) and tristrifluoromethanecarbonyl methide (C(SO2CF3)3 - However, the anion is not limited to the above examples.

[0040] The antistatic agent may contain an anion containing a sulfur atom. An example of an anion containing a sulfur atom is bisfluorosulfonylimide (N(SO2F)2 - ) and bistrifluoromethanesulfonylimide (N(SO2CF3)2 - )

[0041] The antistatic agent may be an organic salt, a lithium salt, or a lithium organic salt containing a lithium ion and an organic ion as a cation and an anion, respectively.

[0042] Specific examples of the antistatic agent (B) are 1-ethyl-3-methylimidazolium bisfluorosulfonylimide, lithium bis(trifluoromethane)sulfonimide (LiTFSi), ethylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (EMPTFSi), and tributylmethylammonium bis(trifluoromethanesulfonyl)imide (TBMATFSi).

[0043] The antistatic agent does not have to contain a phosphorus atom. According to the investigations of the present inventors, an antistatic agent containing a phosphorus atom tends to corrode the touch panel (the conductive layer of the touch panel).

[0044] Layer B may contain one or more antistatic agents.

[0045] Examples of the conductive polymer include polythiophene, polyaniline, polypyrrole, polyquinoxaline, polyacetylene, polyphenylene vinylene, polynaphthalene, and derivatives thereof. The conductive polymer is preferably polythiophene, polyaniline, or a derivative thereof, more preferably a polythiophene derivative.

[0046] The conductive polymer may have a hydrophilic functional group, examples of which include a sulfone group, an amino group, an amide group, an imino group, a hydroxyl group, a mercapto group, a hydrazino group, a carboxyl group, a sulfate ester group, a phosphate ester group, and salts thereof (e.g., quaternary ammonium salt groups).

[0047] From the viewpoint of electrical conductivity and chemical stability, the conductive polymer is preferably poly(3,4-disubstituted thiophene). Examples of poly(3,4-disubstituted thiophene) are poly(3,4-alkylenedioxythiophene) and poly(3,4-dialkoxythiophene), and preferably poly(3,4-alkylenedioxythiophene). Poly(3,4-alkylenedioxythiophene) has, for example, a structural unit represented by the following formula (I):

[0048] [ka]

[0049] R in formula (I) 1 is, for example, an alkylene group having 1 to 4 carbon atoms. The alkylene group may be linear or branched. Examples of the alkylene group include a methylene group, a 1,2-ethylene group, a 1,3-propylene group, a 1,4-butylene group, a 1-methyl-1,2-ethylene group, a 1-ethyl-1,2-ethylene group, a 1-methyl-1,3-propylene group, and a 2-methyl-1,3-propylene group, preferably a methylene group, a 1,2-ethylene group, or a 1,3-propylene group, more preferably a 1,2-ethylene group. The conductive polymer may be poly(3,4-ethylenedioxythiophene) (PEDOT).

[0050] An example of the dopant is a polyanion. When the conductive polymer is polythiophene (or a derivative thereof), the polyanion can form an ion pair with the polythiophene (or a derivative thereof). The polyanion is not particularly limited, and examples thereof include carboxylic acid polymers such as polyacrylic acid, polymaleic acid, and polymethacrylic acid; and sulfonic acid polymers such as polystyrene sulfonic acid, polyvinyl sulfonic acid, and polyisoprene sulfonic acid. The polyanion may be a copolymer of vinyl carboxylic acid or vinyl sulfonic acid with other monomers. Examples of other monomers include (meth)acrylate compounds; and aromatic vinyl compounds such as styrene and vinyl naphthalene. The polyanion is preferably polystyrene sulfonic acid (PSS). An example of a conductive polymer that is a complex with a dopant is a complex of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT / PSS).

[0051] Layer B may contain one or more conductive polymers. Layer B may be substantially free of conductive polymers.

[0052] The total amount of at least one selected from the group consisting of an antistatic agent and a conductive polymer in Layer B is, for example, less than 25 parts by weight, and may be 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, or even 9 parts by weight or less, relative to 100 parts by weight of the main component of Layer B (for example, the (meth)acrylic polymer (A) described below in the case of Layer B contained in Pressure-Sensitive Adhesive Sheet 1). The lower limit of the amount is, for example, 0.005 parts by weight or more.

[0053] [Adhesive sheet 1] The pressure-sensitive adhesive sheet 1 is, for example, a sheet formed from a pressure-sensitive adhesive composition (I) containing a (meth)acrylic polymer (A) as a main component. The pressure-sensitive adhesive sheet 1 formed from the pressure-sensitive adhesive composition (I) contains, for example, a cured product of the (meth)acrylic polymer (A). However, the pressure-sensitive adhesive sheet 1 is not limited to the above examples.

[0054] [Adhesive composition (I)] <(Meth)acrylic polymer (A)> The pressure-sensitive adhesive composition (I) contains a (meth)acrylic polymer (A) as a main component, in other words, the pressure-sensitive adhesive composition (I) is an acrylic pressure-sensitive adhesive composition.

[0055] The (meth)acrylic polymer (A) preferably has a structural unit derived from a (meth)acrylic monomer (A1) having an alkyl group of 1 to 30 carbon atoms on its side chain. The (meth)acrylic polymer (A) may have the above structural unit as a main unit. The alkyl group may be linear or branched. The (meth)acrylic polymer (A) may have one or more structural units derived from the (meth)acrylic monomer (A1). Examples of the (meth)acrylic monomer (A1) include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, and isoheptyl (meth)acrylate. acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, n-decyl(meth)acrylate, isodecyl(meth)acrylate, n-dodecyl(meth)acrylate (lauryl(meth)acrylate), n-tridecyl(meth)acrylate, and n-tetradecyl(meth)acrylate. In this specification, the term "main unit" refers to a unit that accounts for, for example, 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more of all the structural units contained in the polymer.

[0056] The (meth)acrylic polymer (A) may have a structural unit derived from a (meth)acrylic monomer (A1) having a long-chain alkyl group on the side chain. An example of the monomer (A1) is n-dodecyl (meth)acrylate (lauryl (meth)acrylate). In this specification, the term "long-chain alkyl group" refers to an alkyl group having 6 to 30 carbon atoms.

[0057] The (meth)acrylic polymer (A) may have a structural unit derived from a (meth)acrylic monomer (A1) which, when made into a homopolymer, has a glass transition temperature (Tg) in the range of −70 to −20° C. An example of the monomer (A1) is n-butyl acrylate.

[0058] The (meth)acrylic polymer (A) may contain a structural unit other than the structural unit derived from the (meth)acrylic monomer (A1). The structural unit is derived from a monomer (A2) copolymerizable with the (meth)acrylic monomer (A1). The (meth)acrylic polymer (A) may contain one or more types of such structural units.

[0059] An example of the monomer (A2) is an aromatic ring-containing monomer. The aromatic ring-containing monomer may be an aromatic ring-containing (meth)acrylic monomer. Examples of the aromatic ring-containing monomer include phenyl(meth)acrylate, phenoxyethyl(meth)acrylate, benzyl(meth)acrylate, phenoxydiethylene glycol(meth)acrylate, ethylene oxide-modified nonylphenol(meth)acrylate, hydroxyethylated β-naphthol(meth)acrylate, and biphenyl(meth)acrylate. The content of the structural unit derived from the aromatic ring-containing monomer in the (meth)acrylic polymer (A) is, for example, 0 to 50% by weight, or may be 1 to 30% by weight, 5 to 25% by weight, 8 to 20% by weight, 10 to 19% by weight, or even 13 to 18% by weight, or even 0% by weight (i.e., no such structural unit is contained).

[0060] Another example of the monomer (A2) is a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be a hydroxyl group-containing (meth)acrylic monomer. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, as well as (4-hydroxymethylcyclohexyl)-methyl acrylate. The content of structural units derived from hydroxyl group-containing monomers in the (meth)acrylic polymer (A) may be 5% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.5% by weight or less, or even 0.1% by weight or less, or even 0% by weight (i.e., no such structural units are included).

[0061] Another example of the monomer (A2) is a (meth)acrylate represented by the following chemical formula (1): 2 is an alkyl group. The alkyl group may be linear or branched. R 2 is preferably a linear alkyl group. 2 Examples of n are a methyl group and an ethyl group. In formula (1), n ​​is an integer of 1 to 15.

[0062] [ka]

[0063] Examples of the (meth)acrylate represented by formula (1) are 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and methoxytriethylene glycol (meth)acrylate. The structural unit derived from the (meth)acrylate represented by formula (1) can contribute to reducing the surface resistivity of the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (I). The (meth)acrylic polymer (A) may have the structural unit derived from the (meth)acrylate represented by formula (1) as a main unit.

[0064] Monomer (A2) may be a carboxyl group-containing monomer, an amino group-containing monomer, or an amide group-containing monomer. Examples of the carboxyl group-containing monomer are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the amino group-containing monomer are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of the amide group-containing monomer include acrylamide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0065] Monomer (A2) may be a polyfunctional monomer. Examples of polyfunctional monomers include polyfunctional acrylates such as hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. The polyfunctional acrylate is preferably 1,6-hexanediol diacrylate or dipentaerythritol hexa(meth)acrylate.

[0066] The total content of structural units derived from carboxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, and polyfunctional monomers in the (meth)acrylic polymer (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 8% by weight or less. When the (meth)acrylic polymer (A) contains these structural units, the total content may be, for example, 0.01% by weight or more, 1% by weight or more, 2% by weight or more, or even 3% by weight or more. The (meth)acrylic polymer (A) does not necessarily have to contain structural units derived from polyfunctional monomers.

[0067] Examples of the other monomer (A2) include epoxy group-containing monomers such as glycidyl (meth)acrylate and methyl glycidyl (meth)acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphoric acid group-containing monomers; (meth)acrylic acid esters having an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyltoluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ether; and vinyl chloride.

[0068] The total content of the structural units derived from the other monomers (A2) in the (meth)acrylic polymer (A) is, for example, 30% by weight or less, may be 10% by weight or less, and is preferably 0% by weight (not including such structural units).

[0069] The (meth)acrylic polymer (A) can be formed by polymerizing one or more of the above-mentioned monomers by a known method. A monomer and a partial polymer of the monomer may also be polymerized. The polymerization can be carried out, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint of being able to form a pressure-sensitive adhesive sheet with excellent optical transparency, solution polymerization and active energy ray polymerization are preferred. The polymerization is preferably carried out while avoiding contact between the monomer and / or the partial polymer and oxygen. For this purpose, for example, polymerization can be carried out in an inert gas atmosphere such as nitrogen, or polymerization in a state where oxygen is blocked by a resin film or the like. The (meth)acrylic polymer (A) formed may be in any form, such as a random copolymer, a block copolymer, or a graft copolymer.

[0070] The polymerization system for forming the (meth)acrylic polymer (A) may contain one or more polymerization initiators. The type of polymerization initiator can be selected depending on the polymerization reaction, and may be, for example, a thermal polymerization initiator or a photopolymerization initiator.

[0071] Examples of solvents used in solution polymerization include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

[0072] Examples of polymerization initiators used in solution polymerization include azo polymerization initiators, peroxide polymerization initiators, and redox polymerization initiators. Examples of peroxide polymerization initiators include dibenzoyl peroxide and t-butyl permaleate. Among these, the azo polymerization initiators disclosed in JP-A-2002-69411 are preferred. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight, or may be 0.1 to 0.3 parts by weight, per 100 parts by weight of the total amount of monomers.

[0073] The active energy rays used in the active energy ray polymerization include, for example, ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, as well as ultraviolet rays. The active energy ray is preferably ultraviolet rays. Polymerization by irradiation with ultraviolet rays is also called photopolymerization. The polymerization system for the active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions for the active energy polymerization are not limited as long as a (meth)acrylic polymer (A) is formed.

[0074] Examples of the photopolymerization initiator include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator, although the photopolymerization initiator is not limited to the above examples.

[0075] Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisole methyl ether. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. An example of a photoactive oxime-based photopolymerization initiator is 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. An example of a benzoin-based photopolymerization initiator is benzoin. An example of a benzyl-based photopolymerization initiator is benzil. An example of a benzophenone-based photopolymerization initiator is benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, or α-hydroxycyclohexyl phenyl ketone. An example of a ketal-based photopolymerization initiator is benzil dimethyl ketal. An example of a thioxanthone-based photopolymerization initiator is thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, or dodecylthioxanthone.

[0076] The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, and may be 0.05 to 0.5 parts by weight, relative to 100 parts by weight of the total amount of the monomers.

[0077] The weight average molecular weight (Mw) of the (meth)acrylic polymer (A) is, for example, 1,000,000 to 2,800,000, and from the viewpoint of the durability and heat resistance of the PSA sheet, may be 1,200,000 or more, or even 1,400,000 or more. The weight average molecular weight (Mw) of the polymer and oligomer in this specification is a value (polystyrene equivalent) based on measurement by GPC (gel permeation chromatography).

[0078] The content of the (meth)acrylic polymer (A) in the pressure-sensitive adhesive composition (I) is, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, or even 80% by weight or more, in terms of solid content. The upper limit of the content is, for example, 99% by weight or less, 97% by weight or less, 95% by weight or less, 93% by weight or less, or even 90% by weight or less.

[0079] <Additives> The pressure-sensitive adhesive composition (I) may contain other additives. Examples of additives include crosslinking agents, silane coupling agents, colorants such as pigments and dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework improvers, softeners, antioxidants, antiaging agents, light stabilizers, polymerization inhibitors, inorganic fillers, organic fillers, powders such as metal powders, particles, and foil-like materials. The additives can be blended in an amount of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 1 part by weight or less, per 100 parts by weight of the (meth)acrylic polymer (A).

[0080] Examples of the crosslinking agent include an organic crosslinking agent and a polyfunctional metal chelate. Examples of the organic crosslinking agent include an isocyanate crosslinking agent, a peroxide crosslinking agent, an epoxy crosslinking agent, and an imine crosslinking agent. The organic crosslinking agent and the polyfunctional metal chelate can be used for both solvent-based and active energy ray-curable pressure-sensitive adhesive compositions. When the pressure-sensitive adhesive composition (I) is a solvent-based pressure-sensitive adhesive composition, the crosslinking agent is preferably a peroxide crosslinking agent or an isocyanate crosslinking agent. A peroxide crosslinking agent and an isocyanate crosslinking agent may be used in combination.

[0081] When the pressure-sensitive adhesive composition (I) contains a crosslinking agent, the amount of the crosslinking agent added is, for example, 0.01 to 10 parts by weight, or may be 0.1 to 5 parts by weight, or even 0.1 to 3 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer (A).

[0082] When the pressure-sensitive adhesive composition (I) contains a silane coupling agent, the blending amount thereof is, for example, 0.01 to 5 parts by weight or less, and may be 3 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or even 0.05 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer (A). The pressure-sensitive adhesive composition (I) does not necessarily contain a silane coupling agent.

[0083] The pressure-sensitive adhesive composition (I) may be substantially free of a color-forming compound having a maximum absorption wavelength exceeding 380 nm in its absorption spectrum. The maximum absorption wavelength of the color-forming compound may be 385 nm or more, 390 nm or more, 395 nm or more, 400 nm or more, 410 nm or more, or even 420 nm or more. Being substantially free of a color-forming compound having a maximum absorption wavelength in the visible light may contribute to improving the color-forming performance of the OLED. The absorption spectrum of the color-forming compound can be evaluated in the same manner as the absorption spectrum of an ultraviolet absorber. In this specification, "substantially free" of the pressure-sensitive adhesive composition (I) means that the content is 0.5 parts by weight or less, preferably 0.1 parts by weight or less, more preferably 0.05 parts by weight or less, and even more preferably 0.01 parts by weight or less, per 100 parts by weight of the (meth)acrylic polymer (A).

[0084] The type of the pressure-sensitive adhesive composition (I) may be, for example, an emulsion type, a solvent type (solution type), an active energy ray curable type (photocurable type), or a hot melt type. From the viewpoint of forming a pressure-sensitive adhesive sheet 1 having more uniform properties and durability, the pressure-sensitive adhesive composition (I) may be a solvent type. Photocurable pressure-sensitive adhesive compositions containing an ultraviolet absorber tend to exhibit variations in properties (e.g., peel strength) between the side on which the active energy ray is incident and the opposite side during photocuring. The solvent-type pressure-sensitive adhesive composition (I) may not contain a photocurable agent such as an ultraviolet curable agent.

[0085] When a pressure-sensitive adhesive sheet 1 is formed from the pressure-sensitive adhesive composition (I), the ratio a / b of the peel strength a of one main surface of the formed pressure-sensitive adhesive sheet 1 to the peel strength b of the other main surface is, for example, 0.5 to 2, and may be 0.67 to 1.5, 0.75 to 1.33, or even 0.91 to 1.1. In this case, the pressure-sensitive adhesive composition (I) may be a solvent-based adhesive. The peel strength (of the main surface) of the pressure-sensitive adhesive sheet may be, for example, the 180° peel strength evaluated by the test method specified in Method 1, Section 10.3 of Japanese Industrial Standards (JIS) Z0237:2009. Note that a glass plate may be used as the test plate instead of a stainless steel plate when performing this test method.

[0086] The pressure-sensitive adhesive sheet 1 can be formed from the pressure-sensitive adhesive composition (I) as follows.

[0087] In the case of the solvent-curable type, for example, the pressure-sensitive adhesive composition (I) or a mixture of the pressure-sensitive adhesive composition (I) and a solvent is applied to a substrate film to form a coating film, and the formed coating film is dried to form the pressure-sensitive adhesive sheet 1. The pressure-sensitive adhesive composition (I) is thermally cured by the heat generated during drying. In the case of the active energy ray-curable type (photocurable type), for example, a mixture of monomer(s) that will become the (meth)acrylic polymer (A) upon polymerization, and optionally a partially polymerized product of the monomer(s), a polymerization initiator, additives, a solvent, etc., is applied to a substrate film, and the substrate film is then irradiated with active energy rays to form the pressure-sensitive adhesive sheet 1. The solvent may be removed by drying before irradiating with active energy rays. The substrate film may be a film (separator film) whose coated surface has been subjected to a release treatment.

[0088] The pressure-sensitive adhesive sheet 1 formed on the base film can be transferred to any member. The base film may also be an optical film, in which case an optical laminate containing the pressure-sensitive adhesive sheet 1 and the optical film is obtained.

[0089] The coating onto the substrate film can be carried out by a known method, such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, or extrusion coating using a die coater.

[0090] For the solvent-curable type, the drying temperature after application is, for example, 40 to 200°C. The drying temperature may be 160°C or less, 150°C or less, 130°C or less, 120°C or less, or even 100°C or less. The drying time may be, for example, 5 seconds to 20 minutes, 5 seconds to 10 minutes, or even 10 seconds to 5 minutes. For the active energy ray-curable type, the drying temperature and drying time when drying is performed after application may be within the above ranges.

[0091] The composition or mixture to be applied to the substrate film preferably has a viscosity suitable for handling and coating. For this reason, in the case of an active energy ray curable type, the mixture to be applied preferably contains a partial polymer of the monomer(s).

[0092] In one example of the separator film, the coated surface is subjected to a release treatment using a silicone compound.

[0093] The thickness of the pressure-sensitive adhesive sheet 1 is, for example, 1 to 200 μm, and may be 1 to 150 μm, 5 to 100 μm, 8 to 50 μm, 10 to 30 μm, or even 10 to 25 μm.

[0094] The pressure-sensitive adhesive sheet 1 may have a substantially uniform cured state in the thickness direction. A substantially uniform cured state in the thickness direction is particularly suitable for use in OLEDs. A substantially uniform cured state can be confirmed, for example, by the peel force a on one main surface of the pressure-sensitive adhesive sheet 1 being substantially equal to the peel force b on the other main surface. The ratio a / b of the peel force a to the peel force b may be, for example, 0.5 or more and 2 or less, 0.67 or more and 1.5 or less, 0.75 or more and 1.33 or less, or even 0.91 or more and 1.1 or less.

[0095] The pressure-sensitive adhesive sheet 1 in the optical laminate 10 may be a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition. As described above, a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition can have a substantially uniform cured state in the thickness direction. This can contribute to the stability of the OLED, for example.

[0096] In the optical laminate 10 including Layer B, the pressure-sensitive adhesive sheet 1 may be a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition and may also include Layer B. A pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition is suitable for dispersing an antistatic agent or a conductive polymer more uniformly.

[0097] In the optical laminate 10E including Layer B, the first pressure-sensitive adhesive sheet 1A may be a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition. In addition, in the optical laminate 10E including Layer B, the second pressure-sensitive adhesive sheet 10B may be a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition and may also include Layer B.

[0098] [Optical film 2] A known optical film can be used as the optical film 2. The optical film 2 including Layer A can be formed, for example, by blending a known optical film with an ultraviolet absorber. The optical film 2 including Layer B can be formed, for example, by blending a known optical film with at least one selected from an antistatic agent and a conductive polymer.

[0099] The thickness of the optical film 2 is, for example, 1 to 200 μm, and may be 30 to 150 μm, or even 40 to 130 μm.

[0100] [Protective layer 4] The protective layer 4 is, for example, a hard coat layer. A known protective layer and hard coat layer that can be provided in an optical laminate can be used for the protective layer 4 and hard coat layer, respectively. The protective layer 4 including Layer A can be formed, for example, by blending an ultraviolet absorber into a known protective layer. The protective layer 4 including Layer B can be formed, for example, by blending an antistatic agent into a known protective layer 4.

[0101] The thickness of the protective layer 4 is, for example, 1 to 100 μm, and may be 1 to 75 μm, or even 1 to 50 μm.

[0102] The thickness of the optical laminate 10 is, for example, 5 to 225 μm. The upper limit of the thickness may be 200 μm or less, 170 μm or less, or even 130 μm or less.

[0103] [Other aspects] Another example of the optical laminate of the present embodiment is shown in Fig. 6. The optical laminate 10F in Fig. 6 has the same structure as the optical laminate 10E in Fig. 5, except that it further includes a separator 11 bonded to the first pressure-sensitive adhesive sheet 1A.

[0104] The separator 11 is typically a resin film. Examples of resins constituting the separator 11 include polyesters such as polyethylene terephthalate (PET), polyolefins such as polyethylene and polypropylene, polycarbonate, acrylic, polystyrene, polyamide, and polyimide. The surface of the separator 11 that comes into contact with the pressure-sensitive adhesive sheet 1A may be subjected to a release treatment. The release treatment is, for example, a treatment using a silicone compound. However, the separator 11 is not limited to the above example. The separator 11 is peeled off when the optical laminate 10F is used, for example, when it is attached to an image-forming layer.

[0105] The optical laminate of this embodiment can be distributed and stored, for example, as a rolled body obtained by rolling up a strip-shaped optical laminate, or as a sheet-shaped optical laminate.

[0106] The optical laminate of this embodiment is typically used in an image display device. An example of the image display device is an OLED. However, the use of the optical laminate is not limited to the above example.

[0107] [Image display device] An example of an image display device according to this embodiment is shown in FIG. 7. The image display device 21 (21A) in FIG. 7 has a laminated structure in which a substrate 12, an image-forming layer 13, a first pressure-sensitive adhesive sheet 1A, a retardation layer 2C, a second pressure-sensitive adhesive sheet 1B, a polarizer 2A, a polarizer protective film 2B, and a protective layer 4 are laminated in this order. The image display device 21A includes an optical laminate 10 (the optical laminate 10E in FIG. 5). The optical laminate 10E is bonded to the image-forming layer 13 via the first pressure-sensitive adhesive sheet 1A. The image-forming layer 13 and the substrate 12 may have the same configurations as the image-forming layer and the substrate of a known image display device, respectively. The image-forming layer 13 is, for example, an organic electroluminescent (EL) light-emitting layer. The substrate 12 is typically a resin film. Examples of materials constituting the substrate 12 are the same as the examples of materials constituting the separator 11 described above. Any pressure-sensitive adhesive or adhesive can be used to bond the image-forming layer 13 and the substrate 12. A pressure-sensitive adhesive sheet 1 may also be used for bonding.

[0108] The image display device of this embodiment has a 9×10 11 An additional layer C having a surface resistivity of Ω / □ or less may be provided. The additional layer C can contribute, for example, to suppressing unintended light emission in the OLED. The layer C may be located between the substrate 12 and the image-forming layer 13, or on the opposite side of the substrate 12 from the image-forming layer 13. The surface resistivity of the layer C can be in the range exemplified in the description of the layer B.

[0109] Another example of the image display device of this embodiment is shown in FIG. 8. The image display device 21B of FIG. 8 includes a backside treatment layer 14, a substrate 12, an undercoat layer 15, a lower adhesive sheet 16, an image-forming layer 13, and an optical laminate 10E. In the image display device 21B, at least one layer selected from the backside treatment layer 14, the undercoat layer 15, and the lower adhesive sheet 16 may include Layer C. According to the studies of the present inventors, Layer C included in the undercoat layer 15 and Layer C included in the lower adhesive sheet 16 in particular can contribute to suppressing unintended light emission in the OLED. From this perspective, the image display device 21 of this embodiment includes, in this order, the substrate 12, the undercoat layer 15, the lower adhesive sheet 16, the image-forming layer 13, and the optical laminate 10, and at least one layer selected from the undercoat layer 15 and the lower adhesive sheet 16 may include Layer C.

[0110] Layer C contains, for example, at least one selected from an antistatic agent and a conductive polymer. Examples of the type and amount of the antistatic agent are as described above in the description of Layer B.

[0111] A known back surface treatment layer that can be provided in an image display device can be used as the back surface treatment layer 14. The back surface treatment layer 14 including Layer C can be formed, for example, by blending at least one selected from an antistatic agent and a conductive polymer into a known back surface treatment layer.

[0112] A known undercoat layer that can be provided in an image display device can be applied to the undercoat layer 15. The undercoat layer 15 including Layer C can be formed, for example, by blending at least one selected from an antistatic agent and a conductive polymer into a known undercoat layer.

[0113] A known adhesive sheet that can be provided in an image display device can be used for the lower adhesive sheet 16. The lower adhesive sheet 16 including layer C can be formed, for example, by blending at least one selected from an antistatic agent and a conductive polymer into a known adhesive sheet. The lower adhesive sheet 16 may be the adhesive sheet 1.

[0114] Another example of the image display device of this embodiment is shown in FIG. 9. The image display device 21C of FIG. 9 has the same configuration as the image display device 21B of FIG. 8, except that a touch panel 17 and a protective layer 18 are provided between the image forming layer 13 and the optical laminate 10E, in this order from the image forming layer 13 side. Known layers that can be provided in an image display device can be applied to the touch panel 17 and the protective layer 18. The touch panel 17 typically includes a conductive layer such as a metal layer. The protective layer 18 is typically a resin layer such as an acrylic resin layer. Depending on its configuration, the optical laminate 10E is suitable for suppressing corrosion of the touch panel 17.

[0115] In the image display device of this embodiment, the optical laminate 10 including the layer A is usually located closer to the outside light side (visible side) than the image forming layer 13.

[0116] The image display device 21 may be an OLED. The image display device 21 may be for a mobile device such as a smartphone, a smart watch, etc. However, the type of the image display device 21 is not limited to the above examples.

[0117] The image display device of this embodiment can have any configuration as long as it includes the optical laminate of this embodiment. [Example]

[0118] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0119] The correspondence between the abbreviations or names shown in the following explanation and the compounds is as follows: BA: n-butyl acrylate AA: acrylic acid HBA: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate NVP: N-vinylpyrrolidone PEA: Phenoxyethyl acrylate MEA: methoxyethyl acrylate MMA: Methyl methacrylate EHA: 2-ethylhexyl acrylate ACMO: acryloylmorpholine AIBN: 2,2'-azobisisobutyronitrile LiTFSi: Lithium bis(trifluoromethanesulfonyl)imide AS110: 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (Dai-ichi Kogyo Seiyaku, Elexcel AS-110) CIL312: Ionic liquid antistatic agent (CIL-312, manufactured by Nippon Carlit) TSS: UV absorber; 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (BASF Japan, Tinosorb S) C / L: Trimethylolpropane / tolylene diisocyanate trimer adduct (isocyanate-based crosslinking agent; Tosoh, Coronate L) D110: Trimethylolpropane / tolylene diisocyanate trimer adduct (isocyanate-based crosslinking agent; Mitsui Chemicals, Takenate D110) D160N: Trimethylolpropane / hexamethylene diisocyanate trimer adduct (isocyanate-based crosslinking agent; Mitsui Chemicals, Takenate D160N) BMT: Peroxide-based crosslinking agent (NOF, Niper BMT40SV) X411810: Silane coupling agent (Shin-Etsu Chemical Co., Ltd., X-41-1810) X411056: Silane coupling agent (Shin-Etsu Chemical Co., Ltd., X-41-1056) KBM403: Silane coupling agent (Shin-Etsu Chemical Co., Ltd., KBM-403) X249591: Silane coupling agent (Shin-Etsu Chemical Co., Ltd., X24-9591F) A100: Silane coupling agent (Shin-Etsu Chemical Co., Ltd., A-100) SAT10: Rework improver (Kaneka, Silyl SAT10) Irganox: Antioxidant (BASF Japan, Irganox 1010)

[0120] [Preparation of (meth)acrylic polymer (A)] (Synthesis Example 1) A four-neck flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser was charged with 99.0 parts by weight of BA and 1.0 parts by weight of HBA. Next, 0.1 parts by weight of AIBN as a polymerization initiator was added to 100 parts by weight of the BA and HBA mixture. Nitrogen gas was introduced with gentle stirring to replace the atmosphere in the flask with nitrogen. The liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was allowed to proceed for 7 hours. Next, ethyl acetate was added to the resulting reaction solution to adjust the solids concentration to 12% by weight, yielding a solution of (meth)acrylic polymer (A-1).

[0121] (Synthesis Examples 2 to 8) Solutions of (meth)acrylic polymers (A-2) to (A-8) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of the monomers used and the amounts charged were as shown in Table 1 below.

[0122] The monomers used in Synthesis Examples 1 to 8 and the amounts charged are summarized in Table 1 below.

[0123] [Table 1]

[0124] [Preparation of Pressure-Sensitive Adhesive Composition and Pressure-Sensitive Adhesive Sheet] (Manufacturing Examples 1 to 19) As shown in Table 2 below, solvent-based pressure-sensitive adhesive compositions (Production Examples 1 to 19) were obtained by mixing 100 parts by weight of the solid content of the (meth)acrylic polymer (A) with a crosslinker, and, if necessary, an ultraviolet absorber (UVA), an antistatic agent (AS), and additives. Tinosorb S (triazine-based) used as the UVA had two hydroxyphenyl groups and one alkoxyphenyl group per molecule and had an absorbance of 0.55 or more in the maximum absorption wavelength range around 346 nm.

[0125] [Table 2]

[0126] Each of the pressure-sensitive adhesive compositions of Production Examples 1 to 19 was applied using a fountain coater to the release surface of a 38 μm-thick PET film (Mitsubishi Chemical Polyester Film, MRF38), a separator film with a silicone-treated release surface, and then dried for 2 minutes in an air-circulating thermostatic oven set at 155°C to form 20 μm-thick pressure-sensitive adhesive sheets (Production Examples 21 to 39). Next, an additional separator film was bonded to the exposed surface of the formed pressure-sensitive adhesive sheet to obtain a pressure-sensitive adhesive sheet sandwiched between a pair of separator films. The additional separator film was bonded so that the release surface of the additional film was in contact with the pressure-sensitive adhesive sheet. The peel strengths a and b of both main surfaces of each of the produced pressure-sensitive adhesive sheets were evaluated using the method described above, and all had a peel strength ratio a / b close to 1.

[0127] <Evaluation of adhesive sheets> The surface resistivity of the PSA sheets produced in each production example was evaluated as follows: One separator film was peeled off and the sheet was left to stand indoors (temperature 25±5°C, relative humidity 50±10%) for 1 minute, and then the surface resistivity of the exposed surface was measured using a high-resistance resistivity meter (Hiresta MCP-HT450, manufactured by Mitsubishi Chemical Analytech).

[0128] For the pressure-sensitive adhesive sheets of Production Examples 21 to 39, the surface resistivity and whether or not they correspond to Layer A and / or Layer B are shown in Table 3 below.

[0129] [Table 3]

[0130] [Production or preparation of optical film] <Preparation of Polarizer 2A> A long polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000", thickness 30 μm) was uniaxially stretched in the longitudinal direction (total stretching ratio 5.9 times) using a roll stretching machine. At the same time, the resin film was subjected to the following treatments in order: swelling, dyeing, crosslinking, washing, and drying. A 12 μm-thick polarizer was produced. In the swelling treatment, the resin film was stretched 2.2 times while being treated with pure water at 20°C. In the dyeing treatment, the resin film was stretched 1.4 times while being treated with an aqueous solution at 30°C containing iodine and potassium iodide in a weight ratio of 1:7. The iodine concentration in the aqueous solution was adjusted so that the single transmittance of the produced polarizer would be 45.0%. A two-stage crosslinking treatment was used. In the first stage of the crosslinking treatment, the resin film was stretched 1.2 times while being treated with an aqueous solution at 40°C containing boric acid and potassium iodide. The aqueous solution used in the first crosslinking treatment had a boric acid content of 5.0 wt % and a potassium iodide content of 3.0 wt %. In the second crosslinking treatment, the resin film was stretched 1.6 times while being treated with a 65°C aqueous solution containing dissolved boric acid and potassium iodide. The aqueous solution used in the second crosslinking treatment had a boric acid content of 4.3 wt % and a potassium iodide content of 5.0 wt %. A potassium iodide aqueous solution at 20°C was used for the washing treatment. The potassium iodide content of the aqueous solution used for the washing treatment was 2.6 wt %. The drying treatment was carried out at 70°C for 5 minutes.

[0131] <Polarizer protective film 2B> A triacetyl cellulose (TAC) film (manufactured by Konica Minolta, product name "KC2UA", thickness 25 μm) was prepared as the polarizer protective film 2 B. This film contained an ultraviolet absorber.

[0132] <Retardation layer 2C> As the retardation layer 2C, a retardation layer 2CA containing no ultraviolet absorbent and a retardation layer 2CB containing an ultraviolet absorbent were prepared. (Retardation film 2CA) - Fabrication of the first retardation layer - 26.2 parts by weight of isosorbide (ISB), 100.5 parts by weight of 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), 10.7 parts by weight of 1,4-cyclohexanedimethanol (1,4-CHDM), 105.1 parts by weight of diphenyl carbonate (DPC), and 0.591 parts by weight of cesium carbonate (0.2 wt % aqueous solution) as a catalyst were charged into a reaction vessel and dissolved under a nitrogen atmosphere (approximately 15 minutes). The heat transfer temperature in the reaction vessel was set to 150°C, and stirring was performed as necessary. Next, the pressure inside the reaction vessel was reduced to 13.3 kPa, and the heat transfer temperature was increased to 190°C over 1 hour. Phenol evolved as the heat transfer temperature increased was removed from the reaction vessel (the same applies below). Next, the temperature inside the reaction vessel was maintained at 190°C for 15 minutes, after which the pressure inside the reaction vessel was changed to 6.67 kPa and the heat transfer medium temperature was increased to 230°C over 15 minutes. When the stirring torque of the reactor's agitator increased, the heat transfer medium temperature was increased to 250°C over 8 minutes, and the pressure inside the reaction vessel was further reduced to 0.200 kPa or less. After reaching the predetermined stirring torque, the reaction was terminated, and the resulting reaction product was extruded into water and pelletized. In this way, a polycarbonate resin with a composition of BHEPF / ISB / 1,4-CHDM = 47.4 mol% / 37.1 mol% / 15.5 mol% was obtained. The glass transition temperature of the resulting polycarbonate resin was 136.6°C and the reduced viscosity was 0.395 dL / g.

[0133] The prepared polycarbonate resin pellets were vacuum dried at 80°C for 5 hours, and then a long resin film with a thickness of 120 μm was obtained using a film-forming device equipped with a single-screw extruder (manufactured by Isuzu Chemical Engineering, screw diameter 25 mm, cylinder temperature setting 220°C), a T-die (width 200 mm, temperature setting 220°C), a chill roll (temperature setting 120-130°C), and a winder. Next, the obtained resin film was stretched in the width direction using a tenter stretching machine at a stretching temperature of 137-139°C and a stretch ratio of 2.5 times to obtain a first retardation layer.

[0134] - Fabrication of the second retardation layer - A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer (weight average molecular weight 5000) represented by the following chemical formula (II) (wherein 65 and 35 represent the mol% of each structural unit), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, trade name "Paliocolor LC242"), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name "Irgacure 907") in 200 parts by weight of cyclopentanone. Next, the prepared liquid crystal coating solution was applied to the surface of a norbornene-based resin film (manufactured by Nippon Zeon, trade name "Zeonex"), which is a substrate film, using a bar coater, and then heated and dried at 80 ° C for 4 minutes to align the liquid crystal contained in the coating film. Next, the coating film was cured by irradiation with ultraviolet light, and a liquid crystal solidified layer (thickness 0.58 μm) serving as a second retardation layer was formed on the substrate film. The in-plane retardation Re of the liquid crystal solidified layer for light with a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction was -71 nm (nx=1.5326, ny=1.5326, nz=1.6550), and the liquid crystal solidified layer exhibited refractive index characteristics of nz>nx=ny.

[0135] [ka]

[0136] - Fabrication of retardation layer 2CA - One surface of the first retardation layer prepared above was attached to the liquid crystal solidified layer of the second retardation layer via an adhesive to prepare a retardation layer 2CA.

[0137] (Retardation layer 2CB) As the retardation layer 2CB, QLAA218 (consisting of two liquid-phase solidified layers) manufactured by Fujifilm was prepared.

[0138] <Hard coat layer> As the hard coat layers, a hard coat layer 4A containing no ultraviolet absorbent, hard coat layers 4B and 4C containing an ultraviolet absorbent, and a hard coat layer 4D containing an ultraviolet absorbent and an antistatic agent were prepared.

[0139] (Hard coat layer 4A) As the hard coat layer 4B, HC3 manufactured by Toppan TOMOEGAWA Optical Products was prepared.

[0140] (Hard coat layer 4B) As the hard coat layer 4B, HC9 manufactured by Toppan TOMOEGAWA Optical Products was prepared.

[0141] (Hard coat layer 4C) As the hard coat layer 4C, a layer having the same structure as the hard coat layer 4B except that the amount of the ultraviolet absorber added was 0.75 times was prepared.

[0142] (Hard coat layer 4D) Four parts by weight of Irgacure 184 (a photopolymerization initiator manufactured by BASF Japan) was added to a mixed solvent of methyl isobutyl ketone (MIBK) and isopropanol (IPA) and stirred to form a solution (solids content: 25% by weight). To the resulting solution, pentaerythritol triacrylate (PETA) and HRAG acrylic (25) MIBK (a thermoplastic resin manufactured by DNP Fine Chemicals) were added as resin components in a weight ratio of 70:30. Furthermore, 0.2 parts by weight of a leveling agent (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., 10-301(TL)) was added per 100 parts by weight of the resin components and stirred. Next, 100 g of bright dispersion (DNP Fine Chemicals, conductive fine particle dispersion, average particle size 4.6 μm, solid content 25 wt%) was added to 12 kg of the hard coat composition to be formed and stirred, and then 6 parts by weight of ultraviolet absorber (BASF Japan, TINUVI477) was added to 100 parts by weight of the resin component and stirred to obtain a hard coat composition with a solid content of 25 wt%. Next, the coating film of the obtained composition was dried at 80°C for 1 minute, and then ultraviolet light (dose 300 mJ / cm) was applied using a high-pressure mercury lamp. 2 The surface resistivity of the hard coat layer 4D was measured using a high-resistance resistivity meter (Hiresta MCP-HT450, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and was found to be 1×10 9 It was Ω / □.

[0143] [Preparation of optical laminate] The optical laminate 10E shown in FIG. 5 was produced using the combination of layers shown in Table 4 below. The polarizer 2A and the polarizer protective film 2B were bonded together using a polyvinyl alcohol-based adhesive. The other layers were bonded to each other by lamination. The polarizer 2A and the retardation layer C2 were bonded together so that the angle formed between the slow axis of the retardation layer C2 (the slow axis of the first retardation layer in the retardation layer C2A) and the absorption axis of the polarizer 2A was 45 degrees counterclockwise when viewed from the retardation layer side. The laminate of the polarizer protective film 2B, polarizer 2A, (interlayer) pressure-sensitive adhesive sheet 1B, and retardation layer C2 functioned as a circular polarizer.

[0144] [Table 4]

[0145] 4 (except that a hard coat layer was further disposed on the uppermost polarizer protective film 2B) was produced using the combination of layers shown in Table 5. The layers were bonded together in the same manner as in Samples 1 to 29.

[0146] [Table 5]

[0147] <Evaluation of optical laminate> The produced optical laminates were evaluated as follows.

[0148] (Transmittance of light with a wavelength of 380 nm (T380)) The optical laminate was bonded to the surface of a glass plate via the first adhesive sheet, and the T380 in the thickness direction of the optical laminate was evaluated using an ultraviolet-visible spectrophotometer (LPF-200, manufactured by Otsuka Electronics Co., Ltd.). In the evaluation of T380, correction was performed using the transmittance of the glass plate (thickness direction) for light with a wavelength of 380 nm, which had been measured in advance, as a baseline.

[0149] (Presence or absence of UV absorber precipitation) The optical laminate (5 cm × 5 cm) was bonded to the surface of a glass plate via a first adhesive sheet and left for 1000 hours in an atmosphere at a temperature of 20°C and a relative humidity of 98%. After leaving it, an optical microscope was used to check whether crystals of the ultraviolet absorber (typically needle-shaped crystals) had precipitated within the plane or at the edges of the layer containing the ultraviolet absorber.

[0150] (UV resistance of OLED) A laminate of an organic EL light-emitting layer, an aluminum layer (0.4 μm thick), and an acrylic resin protective layer (2 μm thick) was prepared. The optical laminate was then bonded onto the acrylic resin protective layer via a first adhesive sheet, and a cover glass (Corning Gorilla Glass (0.7t)) was then laminated to produce an OLED for evaluation (a rectangular display area measuring 70 mm long x 160 mm wide). A xenon arc test was performed on the produced OLED, and the presence or absence of deterioration in the white display brightness of the OLED before and after the test was visually confirmed. UV light was irradiated from the cover glass side, which was the outermost surface. Cases where no deterioration in display brightness was observed before and after the test were rated A (good), and cases where deterioration was observed were rated D (unacceptable). The xenon arc test was performed using a tabletop xenon arc lamp accelerated lightfastness tester (ATLAS, SUNTEST XLS+) with a UV exposure of 95,400 kJ / m 2 It was carried out at.

[0151] (Static charge suppression ability) While the OLED display was displayed in black, the edge of the hard coat layer at the top surface was rubbed with a brass rod (cylindrical, 7-8 mm in diameter) for 8 hours. The brass rod was rotated repeatedly around the edge of the hard coat layer at a speed of 100 mm / s and a force of 100 gf. After 8 hours, the OLED display was visually inspected. A (Excellent) was assigned to cases where no green light was observed; B (Good) was assigned to cases where green light was observed but the total area of ​​the light-emitting areas was less than 5% of the display area; C (Fair) was assigned to cases where green light was observed but the total area of ​​the light-emitting areas was between 5% and 20% of the display area; and D (Unacceptable) was assigned to cases where green light was observed and the total area of ​​the light-emitting areas was 20% or more of the display area.

[0152] (Corrosion prevention performance) The above-prepared OLED for evaluation (however, the size was changed to 30mm x 30mm) was left in a heated and humidified atmosphere at a temperature of 60°C and a relative humidity of 95% for 336 hours. Next, the OLED was returned to an atmosphere at a temperature of 25°C and a relative humidity of 50%, and then placed on top of a lit backlight. The state of corrosion of the aluminum layer corresponding to the touch panel was visually confirmed, and the corrosion prevention performance of the adhesive sheet was evaluated. A (Excellent): No corrosion is observed. B (Good): Corrosion is observed, but it does not penetrate the aluminum layer. C (Fair): Corrosion is observed that penetrates the aluminum layer, but the maximum diameter of the corroded area is less than 1 mm. D (Unacceptable): Corrosion is observed that penetrates the aluminum layer, and the maximum diameter of the corroded area is 1 mm or more.

[0153] (Humidity durability of optical properties) The optical laminate (5 cm × 5 cm) was bonded to the surface of a glass plate via a first adhesive sheet and left in an atmosphere at 65°C and 95% relative humidity for 300 hours. Before and after each time point, the polarization degree in the thickness direction was evaluated using an ultraviolet-visible spectrophotometer (Otsuka Electronics, LPF-200). A decrease in polarization degree (based on the pre-exposure level) of less than 1% before and after exposure was rated as A (excellent), a decrease of 1% or more but less than 3% was rated as B (good), a decrease of 3% or more but less than 5% was rated as C (passable), and a decrease of 5% or more was rated as D (unacceptable).

[0154] The evaluation results of each optical laminate are shown in Table 6 below.

[0155] [Table 6]

[0156] [Verification of Layer C] In the OLED, the rear surface treatment layer 14, the undercoat layer 15, and the lower adhesive sheet 16 (see FIG. 8) are arranged on the opposite side of the optical laminate side (viewing side) with respect to the organic EL light-emitting layer. 11 The effect of including Layer C having a surface resistivity of Ω / □ or less was examined.

[0157] Surface resistivity is 1×10 13 A PET substrate 12 (manufactured by Mitsubishi Chemical Industries, Ltd., PET substrate thickness: 75 μm, backside treatment layer thickness: 25 nm) was prepared, having a backside treatment layer 14 with a resistivity of Ω / □ formed on one main surface. Next, a bottom film was prepared on the other main surface of the prepared PET substrate 12, with a primer layer 15A (thickness: 25 nm) containing no antistatic agent formed thereon, and a bottom film on which a primer layer 15B (thickness: 25 nm) containing an antistatic agent formed thereon. The surface resistivities of the exposed surfaces of the primer layers 15A and 15B of each prepared bottom film were measured using a high-resistance resistivity meter (manufactured by Mitsubishi Chemical Analytech, Hiresta MCP-HT450), and were found to be above the measurement limit and 1×10, respectively. 5 The resistivity was Ω / □. The primer layer 15B corresponded to layer C.

[0158] Separately, as the lower adhesive sheet 16, an adhesive sheet 16A containing no antistatic agent and an adhesive sheet 16B containing an antistatic agent were prepared on the primer layer of the bottom film. The adhesive sheets 16A and 16B were prepared as follows. The amount of antistatic agent blended in the adhesive sheet 16B was 0.2 wt %. The surface resistivities of the prepared adhesive sheets 16A and 16B were measured using a high resistance resistivity meter (Mitsubishi Chemical Analytech, Hiresta MCP-HT450), and were found to be above the measurement limit and 1×10, respectively. 11 The adhesive sheet 16B was equivalent to layer C.

[0159] Using the bottom film (including the back surface treatment layer 14, substrate 12, and primer layers 15A and 15B), lower adhesive sheet 16, and optical laminate 10 (samples Nos. 2, 3, 9, 21, 22, and 23) prepared above, the bottom film, lower adhesive sheet 16, organic EL light-emitting layer, aluminum layer (0.4 μm thick), acrylic resin protective layer (2 μm thick), optical laminate 10, and the cover glass were bonded together to prepare an OLED for evaluation (a rectangular display area measuring 70 mm long and 160 mm wide). The optical laminate 10 was bonded to the acrylic resin protective layer via a first adhesive sheet. Table 7 below shows the combinations of primer layer, lower adhesive sheet 16, and optical laminate 10 for each of the prepared OLEDs (samples Nos. 41 to 57).

[0160] [Table 7]

[0161] The fabricated OLED for evaluation was evaluated for its charge suppression ability, corrosion prevention ability, and humidity durability of its optical properties by the above-mentioned methods. The evaluation results are shown in Table 8 below.

[0162] [Table 8] [Industrial Applicability]

[0163] The optical stacks of the present invention are suitable for use in OLEDs. [Explanation of symbols]

[0164] 1 adhesive sheet 1A First adhesive sheet 1B Second adhesive sheet 2 Optical Film 2A polarizer 2B Polarizer Protection Film 2C retardation layer 4. Protective layer (hard coat layer) 10, 10A, 10B, 10C, 10D, 10E Optical laminate 12 substrate 13 Image cambium 15. Undercoat Image display device 20, 20A, 20B, 20C

Claims

1. An optical laminate comprising a pressure-sensitive adhesive sheet and an optical film, The optical laminate is A layer A containing an ultraviolet absorber, and has a transmittance of 5% or less for light with a wavelength of 380 nm, The number of layers A included in the optical laminate is 2 or more, the optical laminate has a laminate structure including a first pressure-sensitive adhesive sheet, a retardation layer, a second pressure-sensitive adhesive sheet, a polarizer, a polarizer protective film, and a protective layer; In the laminated structure, the first pressure-sensitive adhesive sheet, the retardation layer, the second pressure-sensitive adhesive sheet, the polarizer, the polarizer protective film, and the protective layer are arranged in this order. Optical laminate. However, this does not include optical laminates containing a layer containing a dye compound whose absorption spectrum has a maximum absorption wavelength in the wavelength region of 380 to 430 nm.

2. The optical laminate according to claim 1 , wherein the number of layers A included in the optical laminate is three or more.

3. The optical laminate according to claim 1 or 2, wherein the ultraviolet absorber has a maximum absorption wavelength in its absorption spectrum of 320 nm or more and 380 nm or less.

4. The optical laminate according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive sheet is a sheet formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer as a main component.

5. The optical laminate according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive sheet is a sheet formed from a solvent-based pressure-sensitive adhesive composition.

6. 9 x 10 11 The optical laminate according to any one of claims 1 to 5, comprising a layer B having a surface resistivity of Ω / □ or less.

7. The optical laminate according to claim 6 , wherein the layer A and the layer B are different layers.

8. The optical laminate according to claim 6 or 7, wherein Layer B contains at least one selected from the group consisting of an antistatic agent and a conductive polymer.

9. The optical laminate according to claim 1 , wherein the polarizer protective film comprises the layer A.

10. The optical laminate according to claim 1 or 9, wherein the second pressure-sensitive adhesive sheet comprises the layer A.

11. The optical laminate according to claim 6 , wherein the protective layer and the polarizer protective film comprise the layer A.

12. The optical laminate according to claim 6 or 11, wherein the second pressure-sensitive adhesive sheet comprises the layer A.

13. The optical laminate according to claim 6 , wherein at least one selected from the first pressure-sensitive adhesive sheet and the second pressure-sensitive adhesive sheet includes the layer B.

14. The optical laminate according to claim 6 , wherein only the second pressure-sensitive adhesive sheet includes the layer B.

15. The optical laminate according to any one of claims 6 and 11 to 14, wherein the first pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition.

16. The optical laminate according to any one of claims 6 and 11 to 15, wherein the second pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet formed from a solvent-based pressure-sensitive adhesive composition and includes the layer B.

17. The optical laminate according to any one of claims 1 to 16, which is for use in an organic electroluminescence display device.

18. An image forming layer and an optical laminate bonded to the image forming layer, An image display device, wherein the optical laminate is the optical laminate according to any one of claims 1 to 17.

19. On the opposite side of the optical laminate with respect to the image forming layer, 11 19. An image display device according to claim 18, comprising a further layer C having a surface resistivity of Ω / □ or less.

20. An optical laminate comprising: an image forming layer; and an optical laminate bonded to the image forming layer, a further layer C having a surface resistivity of 9×10 11 Ω / □ or less is provided on the side opposite to the optical laminate with respect to the image forming layer; The optical laminate A pressure-sensitive adhesive sheet and an optical film, A layer A containing an ultraviolet absorber, and has a transmittance of 5% or less for light with a wavelength of 380 nm, The number of layers A included in the optical laminate is 2 or more. Image display device. However, the optical laminate does not include an optical laminate including a layer containing a dye compound whose absorption spectrum has a maximum absorption wavelength in the wavelength range of 380 to 430 nm.

21. a substrate, an undercoat layer, a lower pressure-sensitive adhesive sheet, the image-forming layer, and the optical laminate in this order; 21. The image display device according to claim 19, wherein at least one selected from the undercoat layer and the lower adhesive sheet includes the layer C.

22. The image display device according to any one of claims 18 to 21, wherein the image display device is an organic electroluminescence display device.

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