Optical laminate and method for manufacturing optical laminate

Abstract

Provided is an optical laminate in which the occurrence of interference unevenness is sufficiently suppressed. The optical laminate is obtained by laminating at least a first optical layer and a second optical layer via an adhesive layer, the first optical layer being a liquid crystal phase difference layer, and the adhesive layer being a cured product layer of an adhesive composition containing at least a cationically polymerizable component, a cationic polymerization initiator, and metal oxide particles. The surface of the first optical layer, which is opposite to the surface on the adhesive layer side, is provided with surface irregularities shown below. Surface irregularity: sum (D1 + D2) of height D1 at the apex of the highest convex section with respect to the average line obtained by line measurement of surface irregularity of the surface opposite to the adhesive layer-side surface of the first optical layer and depth D2 of the lower one of two concave sections adjacent to the highest convex section The size of the fluctuations is 100 nm or less.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical laminate and a method for manufacturing an optical laminate. The optical laminate can form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, a PDP, or the like. BACKGROUND

[0002] In order to improve the visual recognition of a display screen of an image display device caused by reflection of external light, reflection of a background, or the like, an image display device provided with a circularly polarizing plate on the visible side of a display panel is known.

[0003] For example, in Patent Document 1 described below, a polarizing plate composite is described, in which a linear polarizing plate, a 1 / 2 wavelength layer, a first adhesive layer in which a curable energy ray-curable adhesive is cured, and a 1 / 4 wavelength layer are sequentially provided, in which the angle formed by the fast axis of the 1 / 2 wavelength layer and the transmission axis of the linear polarizing plate is 10° or more and 20° or less, and the absolute value of the difference between the refractive index of the first adhesive layer at a wavelength of 589 nm and the refractive index of the 1 / 2 wavelength layer in the fast axis direction at a wavelength of 589 nm is less than 0.05.

[0004] In addition, in Patent Document 2 described below, a polarizing plate with a phase difference layer is described, which sequentially includes a polarizer, a first phase difference layer, and a second phase difference layer, the polarizer and the first phase difference layer are attached via a first adhesive layer, the first phase difference layer and the second phase difference layer are attached via a second adhesive layer, the thickness of the first phase difference layer and the second phase difference layer is 5 μm or less, the average refractive index of the second adhesive layer is 1.55 or more, and the difference between the average refractive index of the first phase difference layer and the average refractive index of the second phase difference layer is less than 0.08.

[0005] In addition, in Patent Document 3 described below, an optical laminate is described, which sequentially includes a first optical layer, a first adhesive layer in which a curable energy ray-curable adhesive is cured, and a second optical layer, the first optical layer is a liquid crystal layer in which the surface on the first adhesive layer side is formed of a liquid crystal compound, the curable energy ray-curable adhesive contains a curable component and a cationic polymerization initiator, in the curable component, when the total amount is set to 100 parts by mass, 10 to 90 parts by mass of a multifunctional aromatic epoxy compound having a viscosity of 30 Pa-s or less at a temperature of 25°C is contained, an alicyclic epoxy compound or a monofunctional epoxy compound is optionally contained, the content of the alicyclic epoxy compound is less than 25 parts by mass, and the content of the monofunctional epoxy compound is less than 20 parts by mass, and the refractive index of the first adhesive layer at a wavelength of 589 nm is 1.53 or more.

[0006] In addition, in Patent Document 4 described below, for the purpose of providing a living energy ray-curable resin composition and a cured product which realize a balance of various properties necessary for an optical sheet or the like which can be used for optical use, a living energy ray-curable resin composition is described which contains metal oxide nanoparticles (A), a (meth)acrylic acid phenoxybenzyl ester (B), and a difunctional (meth)acrylic acid ester having a (poly)alkylene glycol structure (C).

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2020-52365

[0010] Patent Document 2: Japanese Patent Application Publication No. 2018-17996

[0011] Patent Document 3: Japanese Patent Application Publication No. 2020-56988

[0012] Patent Document 4: Japanese Patent Application Publication No. 2017-128688 SUMMARY

[0013] Problems to be Solved by the Invention

[0014] The present inventors conducted intensive studies, and as a result, it was ascertained that in the technologies described in Patent Documents 1 and 2 described above, there is room for further improvement in order to stably increase the refractive index of the interlayer adhesive of the optical laminate. In addition, it was ascertained that in the technology described in Patent Document 3 described above, there is room for further improvement in view of the adverse situation of unevenness of interference of the optical laminate.

[0015] Note that the technology described in Patent Document 4 described above relates to a living energy ray-curable resin composition for manufacturing a lens sheet, and does not at all envisage the use of bonding at least two optical films. Furthermore, the adhesive composition is applied to the optical film in a film thickness that is quite thin, and therefore, in the case of containing metal oxide particles, it is required to be excellent in liquid stability, but in the technology described in Patent Document 3 described above, such a problem is not studied, and of course, there is no description or suggestion of a means for solving the problem.

[0016] The present invention was developed in view of the actual situation described above, and aims to provide an optical laminate in which the occurrence of unevenness of interference is sufficiently suppressed.

[0017] Method for Solving the Problem

[0018] The above problems can be solved by the following solution. That is, the present application relates to an optical laminate (1) in which at least a first optical layer and a second optical layer are laminated via an adhesive layer, the first optical layer is a liquid crystal-based phase difference layer, the adhesive layer is a cured product layer of an adhesive composition containing at least a cationically polymerizable component, a cationic polymerization initiator, and metal oxide particles, and a surface of the first optical layer opposite to the surface on the side of the adhesive layer has surface unevenness described below.

[0019] (Surface unevenness)

[0020] The magnitude of the undulation represented by the sum (D1+D2) of the height D1 at the apex of the highest convex portion with respect to an average line described below and the depth D2 of the lower of the two concave portions adjacent to the highest convex portion is 100 nm or less, and the average line is an average line obtained as a result of line measurement of the surface unevenness of the surface of the first optical layer opposite to the surface on the side of the adhesive layer.

[0021] In the optical laminate (1) described above, it is preferable that the optical laminate (2) be one in which the adhesive composition further contains a radical polymerizable compound.

[0022] In the optical laminate (1) or (2) described above, it is preferable that the optical laminate (3) be one in which the refractive index of the adhesive layer is 1.54 or more.

[0023] In any one of the optical laminates (1) to (3) described above, it is preferable that the optical laminate (4) be one in which, in the adhesive composition, the content of the metal oxide particles is 5 to 50 mass% when the total amount of the composition is taken as 100 mass%.

[0024] In the optical laminates (1) to (4) described above, it is preferable that the optical laminate (5) be one in which the adhesive composition further contains a (meth)acrylate containing an aromatic ring skeleton.

[0025] In the optical laminate (5) described above, it is preferable that the optical laminate (6) be one in which the (meth)acrylate containing an aromatic ring skeleton contains at least one selected from the group consisting of a (meth)acrylate having a polycyclic aromatic ring skeleton and a (meth)acrylate having two or more aromatic rings.

[0026] In the optical laminate (5) described above, it is preferable that the optical laminate (7) be one in which the (meth)acrylate containing an aromatic ring skeleton is phenoxybenzyl (meth)acrylate.

[0027] In any one of the above optical laminates (1) to (7), the optical laminate (8) is preferred, wherein the above adhesive composition contains at least one selected from the group consisting of alicyclic epoxy compounds, aromatic epoxy compounds, aromatic oxetane compounds, and difunctional oxetane compounds as the above cationically polymerizable component.

[0028] In any one of the above optical laminates (1) to (8), the optical laminate (9) is preferred, wherein the above adhesive composition contains at least one selected from the group consisting of zinc oxide, zirconium oxide, and titanium oxide as the above metal oxide particles.

[0029] In any one of the above optical laminates (1) to (9), the optical laminate (10) is preferred, wherein the average particle diameter of the above metal oxide particles is 100 nm or less.

[0030] In any one of the above optical laminates (1) to (10), the optical laminate (11) is preferred, wherein the thickness of the above adhesive layer is 0.3 to 3.0 μm.

[0031] Further, the present application relates to a method for producing an optical laminate (11) which is an optical laminate in which at least a first optical layer and a second optical layer are laminated via an adhesive layer, the method comprising: a coating step of coating an adhesive composition on one or both of a bonding surface of the above first optical layer and a bonding surface of the above second optical layer; a bonding step of bonding the above first optical layer and the above second optical layer; and a bonding step of at least curing the above adhesive composition by irradiating active energy rays from the side of the above first optical layer or the side of the above second optical layer, and bonding the above first optical layer and the above second optical layer via the above adhesive layer formed by the curing, the above first optical layer being a liquid crystal-based phase difference layer, and the above adhesive layer being a cured product layer of an adhesive composition containing at least a cationically polymerizable component, a cationic polymerization initiator, and metal oxide particles.

[0032] In the above method for producing an optical laminate (11), the method for producing an optical laminate (12) is preferred, wherein the viscosity of the above adhesive composition at 25°C is 100 [mPa-s] or less.

[0033] Effects of the Invention

[0034] In an optical laminate, particularly an optical laminate having a liquid crystal-based phase difference layer, it is particularly important to suppress occurrence of interference unevenness. In order to suppress occurrence of interference unevenness of an optical laminate, the present inventors have made intensive studies on the generation state of surface irregularities of an adhesive layer constituting the optical laminate. As a result, it has been found that particularly a liquid crystal-based phase difference layer which is fragile and has poor shape retention is likely to generate the same irregularities on its surface in a manner following the irregularities generated on the surface of the adhesive layer, thereby easily causing interference unevenness of the optical laminate. Further, as a result of intensive studies by the present inventors, it has been found that by forming an adhesive layer constituting an optical laminate from a cured product layer of a specific adhesive composition, and designing the surface irregularities of the surface of a liquid crystal-based phase difference layer (a surface opposite to the surface of the adhesive layer) to be within a specific range, interference unevenness of the optical laminate can be sufficiently suppressed.

[0035] Specifically, by forming an adhesive layer from a cured product layer of an adhesive composition containing at least a cationic polymerizable component, a cationic polymerization initiator, and metal oxide particles when a first optical layer which is a liquid crystal-based phase difference layer is laminated with a second optical layer, and designing the surface irregularities of the surface of the first optical layer opposite to the surface of the adhesive layer as described below, interference unevenness of the optical laminate can be sufficiently suppressed.

[0036] (Surface irregularities)

[0037] The optical laminate is designed so as to have surface irregularities in which the magnitude of the undulation represented by the sum (D1+D2) of the height D1 at the apex of the highest protrusion and the depth D2 of the lower of the two depressions adjacent to the highest protrusion with respect to the average line obtained as a result of line measurement of the surface irregularities of the surface of the first optical layer opposite to the surface of the adhesive layer is 100 nm or less. The method for measuring the surface irregularities in the present invention is described later.

[0038] In the present application, the reason why the unevenness of interference of the optical laminate can be sufficiently suppressed is not clear, but it can be presumed as follows. The metal oxide particles contained in the adhesive composition for forming the adhesive layer are less likely to be deformed and expand due to thermal changes than the resin components for adhesives in the past. Therefore, when the adhesive composition is applied to the first optical layer and / or the second optical layer, the application streaks of the adhesive composition are less likely to occur, and the shrinkage of the adhesive composition after application is also less likely to occur. As a result, when the adhesive composition applied to the phase difference layer (first optical layer) of the liquid crystal type, which is particularly fragile and has poor shape retention, is cured to form a cured product layer (adhesive layer), the generation of surface unevenness of the adhesive layer can be suppressed, and based on this, the change in surface unevenness of the surface (the surface opposite to the surface of the adhesive layer side) of the phase difference layer of the liquid crystal type can be sufficiently reduced, whereby the unevenness of interference of the optical laminate can be sufficiently suppressed.

[0039] Note that, in the optical laminate of the present application, the adhesive layer is formed of a cationic adhesive composition containing a cationic polymerizable component, a cationic polymerization initiator, and metal oxide particles, but as the polymerizable component, only the cationic polymerizable component can be used, or a "cationic / free radical hybrid type" in which the cationic polymerizable component and a free radical polymerizable compound are used in combination can be used.

[0040] When manufacturing the optical laminate of the present application, if the viscosity of the adhesive composition for forming the adhesive layer is reduced, specifically, if the viscosity of the adhesive composition at 25°C is designed to be 100 [mPa-s] or less, the generation of application streaks can be further suppressed when the adhesive composition is applied to the first optical layer and / or the second optical layer. As a result, when the cured product layer (adhesive layer) is formed, the generation of surface unevenness of the adhesive layer can be suppressed, and thus the change in surface unevenness of the surface (the surface opposite to the surface of the adhesive layer side) of the phase difference layer of the liquid crystal type can be further reduced, whereby the unevenness of interference of the optical laminate can be further sufficiently suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is an example of the optical laminate of the present application.

[0042] Figure 2 is an enlarged schematic view when measuring the surface unevenness of the surface of the first optical layer opposite to the surface of the adhesive layer side.

[0043] SYMBOL EXPLANATION

[0044] 1 first optical layer

[0045] 2 second optical layer

[0046] 3 adhesive layer

[0047] 4 transparent protective film

[0048] 5 polarizer

[0049] 6 adhesive layer

[0050] 7 organic light emitting diode layer

[0051] 10 optical stack

[0052] B average line obtained as a result of line measurement of surface irregularities of the surface of the first optical layer 1 opposite to the surface of the adhesive layer side

[0053] D1 height at the apex of the highest protrusion

[0054] D2 depth of the lower of the two depressions adjacent to the highest protrusion DETAILED DESCRIPTION

[0055] Figure 1 An example of the optical stack of the present application is shown in FIG. 1. Figure 1 In the optical stack 10 shown, the first optical layer 1 and the second optical layer 2 are laminated together via the adhesive layer 3 which is a cured product layer of an adhesive composition. In order to form the adhesive layer 3, in the adhesive composition used in the present application, metal oxide particles are stably dispersed, and as a result, the refractive index of the cured product layer thereof is high. Therefore, in the case where, for example, a phase difference layer, preferably a phase difference layer of the liquid crystal type, is used as the first optical layer 1 and the second optical layer 2, the refractive index difference between the first optical layer 1 and the adhesive layer 3 can be reduced, and likewise, the refractive index difference between the second optical layer 2 and the adhesive layer 3 can be reduced, and therefore, interference unevenness in the optical stack can be suppressed, and visual recognition can be improved. Further, as described above, by forming the adhesive layer 3 which constitutes the optical stack 10 from the cured product layer of the specific adhesive composition, the surface irregularities of the surface of the phase difference layer of the liquid crystal type (first optical layer 1) (surface opposite to the surface of the adhesive layer 3 side) are designed to be within a specific range, and therefore, interference unevenness of the optical stack 10 can be sufficiently suppressed.

[0056] The optical stack of the present application is an optical stack in which at least a first optical layer and a second optical layer are laminated via an adhesive layer which is a cured product layer of an adhesive composition, and can further have any optical film or the like. Figure 1 The optical stack 10 shown has a polarizer 5 on the second optical layer 2 (visible side), and further has a transparent protective film 4. Note that, between the second optical layer 2 and the polarizer 5, and between the polarizer 5 and the transparent protective film 4, an adhesive layer or an adhesive layer (in the case of the optical stack 10 shown, an adhesive layer) is generally provided. Figure 1The adhesive layer is not particularly limited and can be the same as the cured product layer of the adhesive composition used in the present application, i.e., the adhesive layer 3, or can be a cured product layer of an adhesive composition known to those skilled in the art. In the case of an adhesive layer, it can also be an adhesive layer known to those skilled in the art. In addition, Figure 1 The optical laminate 10 shown has an organic light emitting diode layer 7 under the first optical layer 1 (the display device side) via an adhesive layer 6.

[0057] The optical laminate of the present application is obtained by laminating at least a first optical layer and a second optical layer via an adhesive layer. The adhesive layer is formed from a cured product layer of an adhesive composition containing at least a cationically polymerizable component, a cationic polymerization initiator, and metal oxide particles. Hereinafter, the adhesive composition used as a raw material for the adhesive layer will be described.

[0058] < Metal oxide particles >

[0059] The adhesive composition used in the present application contains metal oxide particles. As the metal oxide particles, for example, there can be mentioned silicon oxide, zirconium oxide, titanium oxide, zinc oxide, antimony pentoxide, tin oxide, aluminum oxide, indium oxide, indium tin oxide, iron oxide, cerium oxide, yttrium oxide, manganese oxide, holmium oxide, copper oxide, bismuth oxide, cobalt oxide, tricobalt tetroxide, triiron tetroxide, magnesium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, tantalum pentoxide, niobium pentoxide, iridium oxide, rhodium oxide, ruthenium oxide, and composite oxides obtained by combining them, and the like. Among these, zinc oxide, zirconium oxide, and titanium oxide are preferred, and zirconium oxide is particularly preferred. Note that the metal oxide particles used in the present application can be composed only of the above-mentioned metal oxides, or can contain other components, but it is preferred that the metal oxide as a component in the particles accounts for the largest weight. The shape of the metal oxide particles can be any of a spherical shape, an ellipsoidal shape, a cubic shape, a rectangular shape, or a conical shape, and the like. Note that in the present application, as the metal oxide particles, metal oxide particles subjected to surface treatment by a method known to those skilled in the art can be used.

[0060] The average particle diameter of the metal oxide particles used is preferably 1 to 150 nm, more preferably 1 to 100 nm, and particularly preferably 1 to 50 nm, from the viewpoint of improving the stability of the metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer. In the present application, the average particle diameter of the metal oxide particles can be calculated by magnification observation using a transmission electron microscope (TEM), a field emission transmission electron microscope (FE-TEM), a field emission scanning electron microscope (FE-SEM), or the like, randomly selecting, for example, 1000 particles, measuring the maximum length thereof, and calculating the arithmetic mean thereof.

[0061] The average particle diameter of the metal oxide particles incorporated in the adhesive composition can also be calculated by a dynamic light scattering method or a laser diffraction method. In the case of calculation by a dynamic light scattering method or a laser diffraction method, the average particle diameter refers to the particle diameter at the cumulative value of 50% in the particle size distribution calculated by a laser diffraction / scattering method.

[0062] The amount of the metal oxide particles used is preferably 5 to 50% by mass, and more preferably 8 to 40% by mass, based on the total amount of the composition, from the viewpoint of improving the stability of the metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer.

[0063] <Curable Component>

[0064] The adhesive composition used in the present application contains a curable component. In the present application, the curable component is preferably a curable component that is curable by active energy rays. As the curable component that is curable by active energy rays, there are a curable component that is curable by cationic polymerization (a cationically polymerizable component) and a curable component that is curable by radical polymerization (a radically polymerizable compound). In the present application, active energy rays having a wavelength range of 10 nm or more and less than 380 nm are referred to as ultraviolet rays, and active energy rays having a wavelength range of 380 nm to 800 nm are referred to as visible light.

[0065] The adhesive composition used in the present application contains at least a cationically polymerizable component. As the cationically polymerizable component (cationically polymerizable compound), it can be classified into a monofunctional cationically polymerizable compound having one cationically polymerizable functional group in the molecule, and a multifunctional cationically polymerizable compound having two or more cationically polymerizable functional groups in the molecule. The monofunctional cationically polymerizable compound has a low liquid viscosity, and therefore, by containing the monofunctional cationically polymerizable compound in the adhesive composition, the liquid viscosity can be reduced. In addition, the monofunctional cationically polymerizable compound has a functional group that can exhibit various functions in many cases, and by containing the monofunctional cationically polymerizable compound in the adhesive composition, the adhesive composition and / or the cured product of the adhesive composition can exhibit various functions. The multifunctional cationically polymerizable compound allows the cured product of the adhesive composition to be three-dimensionally crosslinked, and therefore, it is preferable to contain the multifunctional cationically polymerizable compound in the adhesive composition. In terms of the ratio of the monofunctional cationically polymerizable compound to the multifunctional cationically polymerizable compound, it is preferable to mix the multifunctional cationically polymerizable compound in a range of 10 mass% to 1000 mass% with respect to 100 mass% of the monofunctional cationically polymerizable compound. As the cationically polymerizable functional group, an epoxy group, an oxetanyl group, and a vinyl ether group can be given.

[0066] As the compound having an epoxy group, an aliphatic epoxy compound, an alicyclic epoxy compound, and an aromatic epoxy compound can be given, and since the adhesive composition of the present application is excellent in curability and adhesiveness, it is particularly preferable to contain an alicyclic epoxy compound. As the alicyclic epoxy compound, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, a caprolactone-modified product, a trimethylcaprolactone-modified product, a pentalactone-modified product, and the like of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate can be given, and specifically, CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, CELLOXIDE 2085 (all of which are manufactured by Daicel Chemical Industries, Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, R-6110 (all of which are manufactured by Dow Chemical Japan Co., Ltd.), and the like can be given. The compound having an oxetanyl group (oxetane compound) is preferable because it has an effect of improving the curability of the adhesive composition or reducing the liquid viscosity of the composition, and in particular, an aromatic oxetane compound or a difunctional oxetane compound is more preferable.

[0067] As the oxetane compound, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanylmethoxymethyl]benzene, 3-ethyl-3-(phenoxy- methyl)oxetane, di[(3-ethyl-3-oxetanylmethyl]ether, 3-ethyl-3-(2- ethylhexyloxymethyl)oxetane, novolak oxetane, and the like can be given, and ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211, ARON OXETANE OXT-221, ARON OXETANE OXT-212 (all of which are manufactured by Toagosei Co., Ltd.), and the like are commercially available. The compound having a vinyl ether group is preferable to be contained because it has an effect of improving the curability of the cationic polymerizable adhesive composition, or reducing the liquid viscosity of the composition.

[0068] As the compound having a vinyl ether group, 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol-type tetra- vinyl ether, and the like can be given.

[0069] The adhesive composition used in the present application contains at least one compound selected from the group consisting of the compounds having an epoxy group, the compounds having an oxetanyl group (oxetane compounds), and the compounds having a vinyl ether group, which are described above as the curable component, and thus a photo cationic polymerization initiator can be combined. The photo cationic polymerization initiator generates cationic species or Lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, thereby initiating the polymerization of the epoxy group and the oxetanyl group. As the photo cationic polymerization initiator, a photo acid generator described later can be appropriately used. In the case where the cationic polymerizable adhesive composition is used as a visible light curable type, a photo cationic polymerization initiator having high sensitivity to light of 380 nm or more is particularly preferably used, but the photo cationic polymerization initiator is a compound that generally exhibits a large absorption in the wavelength region of around 300 nm or shorter than 300 nm, and thus, by combining a photosensitizer that exhibits a large absorption in the wavelength region longer than that, specifically, in the wavelength region longer than 380 nm, the light in the vicinity of the wavelength can be sensed, and the generation of cationic species or acid from the photo cationic polymerization initiator can be promoted. As the photosensitizer, for example, anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox-type compounds, azo and diazo compounds, halogen compounds, photoreducible pigments, and the like can be cited, and two or more kinds thereof can be used in mixture. In particular, anthracene compounds are excellent in photosensitizing effect, and thus are preferred, and specifically, Anthracure UVS-1331, Anthracure UVS-1221 (manufactured by Kawaski Kasei Co., Ltd.) can be cited. The content of the photosensitizer is preferably 0.1 to 5 mass%, and more preferably 0.5 to 3 mass%.

[0070] In the optical laminate of the present application, the adhesive layer is formed of a cationic adhesive composition containing a cationic polymerizable component, a cationic polymerization initiator, and metal oxide particles, but as the polymerizable component, only the cationic polymerizable component can be used, or a "cationic / radical hybrid type" in which the cationic polymerizable component and a radical polymerizable compound are used in combination can be used. However, it should be noted that even in the "cationic / radical hybrid type", from the viewpoint of sufficiently suppressing unevenness of interference of the optical laminate, when the total amount in the composition is assumed to be 100 mass%, the content of the cationic polymerizable component is preferably 5 to 99 mass%, and more preferably 20 to 95 mass%.

[0071] In the case where the adhesive composition used in the present application is of the "cationic / radical hybrid type", a monofunctional radically polymerizable compound can be contained as a curable component. As the monofunctional radically polymerizable compound, various (meth)acrylic acid derivatives having a (meth)acryloyloxy group can be exemplified. Specifically, for example, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid n-propyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid 2-methyl-2-nitropropyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid sec-butyl ester, (meth)acrylic acid t-butyl ester, (meth)acrylic acid n-pentyl ester, (meth)acrylic acid t-pentyl ester, (meth)acrylic acid 3-pentyl ester, (meth)acrylic acid 2,2-dimethylbutyl ester, (meth)acrylic acid n-hexyl ester, (meth)acrylic acid hexadecyl ester, (meth)acrylic acid n-octyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid 4-methyl-2-propylpentyl ester, (meth)acrylic acid n-octadecyl ester, and the like (alkyl (meth)acrylate having 1 to 20 carbon atoms) can be exemplified.

[0072] In addition, as the above (meth)acrylic acid derivatives, for example, (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid cyclopentyl ester, and the like (cycloalkyl (meth)acrylate); (meth)acrylic acid benzyl ester, and the like (aralkyl (meth)acrylate); (meth)acrylic acid 2-isobornyl ester, (meth)acrylic acid 2-norbornylmethyl ester, (meth)acrylic acid 2-norbornylmethyl ester, (meth)acrylic acid 5-norbornen-2-ylmethyl ester, (meth)acrylic acid 3-methyl-2-norbornylmethyl ester, (meth)acrylic acid dicyclopentenyl ester, (meth)acrylic acid dicyclopentenoxyethyl ester, (meth)acrylic acid dicyclopentyl ester, and the like (polycyclic (meth)acrylate); (meth)acrylic acid 2-methoxyethyl ester, (meth)acrylic acid 2-ethoxyethyl ester, (meth)acrylic acid 2-methoxymethoxyethyl ester, (meth)acrylic acid 3-methoxybutyl ester, (meth)acrylic acid ethylcarbitol ester, (meth)acrylic acid phenoxyethyl ester, (meth)acrylic acid alkylphenoxy polyethylene glycol ester, and the like (alkoxy- or phenoxy-containing (meth)acrylate); and the like can be exemplified. Among these, since the adhesion to various protective films is excellent, dicyclopentenoxyethyl acrylate and phenoxyethyl acrylate are preferred.

[0073] In addition, as the above (meth)acrylic acid derivative, mention can be made of (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid 3-hydroxypropyl ester, (meth)acrylic acid 2-hydroxybutyl ester, (meth)acrylic acid 4-hydroxybutyl ester, (meth)acrylic acid 6-hydroxyhexyl ester, (meth)acrylic acid 8-hydroxyoctyl ester, (meth)acrylic acid 10-hydroxydecyl ester, (meth)acrylic acid 12-hydroxylauryl ester and the like (meth)acrylic acid hydroxyalkyl esters, [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, (meth)acrylic acid 2-hydroxy-3-phenoxypropyl ester and the like hydroxyl group-containing (meth)acrylates; glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether and the like epoxy group-containing (meth)acrylates; (meth)acrylic acid 2,2,2-trifluoroethyl ester, (meth)acrylic acid 2,2,2-trifluoroethyl ethyl ester, (meth)acrylic acid tetrafluoropropyl ester, (meth)acrylic acid hexafluoropropyl ester, (meth)acrylic acid octafluoropentyl ester, (meth)acrylic acid heptadecafluorodecyl ester, (meth)acrylic acid 3-chloro-2-hydroxypropyl ester and the like halogen-containing (meth)acrylates; dimethylaminoethyl (meth)acrylate and the like alkylaminoalkyl (meth)acrylates; 3-oxetanyl methyl (meth)acrylate, 3-methyloxetanyl methyl (meth)acrylate, 3-ethyloxetanyl methyl (meth)acrylate, 3-butyloxetanyl methyl (meth)acrylate, 3-hexyloxetanyl methyl (meth)acrylate and the like oxetanyl (meth)acrylates; tetrahydrofurfuryl (meth)acrylate, butyrolactone (meth)acrylate and the like (meth)acrylates having a heterocycle, hydroxypivalic acid neopentyl glycol (meth)acrylic acid adduct, p-phenylphenol (meth)acrylate and the like. Among these, 2-hydroxy-3-phenoxypropyl acrylate is preferred because of excellent adhesion to various protective films.

[0074] In the case where the adhesive composition used in the present application is of the "cationic / radical hybrid type", when a hydroxyl group-containing (meth)acrylate is contained in the adhesive composition in addition to the metal oxide particles, the adhesive force of the adhesive layer is further improved, and thus is preferred. From the viewpoint of improving the adhesive force of the adhesive layer, when the total amount in the composition is taken as 100% by mass, the blending amount of the hydroxyl group-containing (meth)acrylate is preferably 3 to 15% by mass.

[0075] In addition, as the monofunctional radical polymerizable compound, mention can be made of carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.

[0076] In addition, examples of monofunctional free radical polymerizable compounds include: N-vinylpyrrolidone, N-vinyl-ε-caprolactam, methylvinylpyrrolidone, and other lactam vinyl monomers; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazolium, and vinylpyrrole. Vinyl monomers containing nitrogen-containing heterocycles, such as azoles and vinylmorpholine.

[0077] Furthermore, as a monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. A radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acryloyl group at the end or in the molecule, and having an active methylene group. Examples of active methylene groups include acetoacetyl, alkoxymalonyl, or cyanoacetyl. The preferred active methylene group is acetoacetyl. Specific examples of free radical polymerizable compounds containing an active methylene group include: 2-acetylacetoxyethyl methacrylate, 2-acetylacetoxypropyl methacrylate, 2-acetylacetoxy-1-methylethyl methacrylate, and other acetylacetoxyalkyl methacrylates; 2-ethoxymalonyl ethyl methacrylate, 2-cyanoacetoxyethyl methacrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetylacetoxymethylbenzyl)acrylamide, N-(2-acetylacetylaminoethyl)acrylamide, etc. The preferred free radical polymerizable compound containing an active methylene group is an acetylacetoxyalkyl methacrylate.

[0078] When the adhesive composition used in this invention is a "cationic / radical mixture", it may contain a multifunctional free radical polymerizable compound as a curing agent. Examples of polyfunctional free radical polymerizable compounds include: N,N'-methylenebis(meth)acrylamide, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, cyclic trimethylolpropane formal(meth)acrylate, and dimethylolpropane formal(meth)acrylate. alkanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, EO-modified diglycerol tetra(meth)acrylate, and the like, esterification products of (meth)acrylic acid and polyhydric alcohol, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. As specific examples, ARONIX M-220 (manufactured by Toagosei Co., Ltd.), LIGHT ACRYLATE 1,9ND-A (manufactured by Gohsen Co., Ltd.), LIGHT ACRYLATE DGE-4A (manufactured by Gohsen Co., Ltd.), LIGHT ACRYLATE DCP-A (manufactured by Gohsen Co., Ltd.), SR-531 (manufactured by Sartomer Co.), CD-536 (manufactured by Sartomer Co.), and the like are preferable. In addition, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, various (meth)acrylate-based monomers, and the like can be cited as needed. Note that, the polyfunctional (meth)acrylamide derivative is preferable to be contained in the adhesive composition because it not only has a fast polymerization rate and excellent productivity, but also has excellent crosslinkability in the case where the adhesive composition is made into a cured product.

[0079] For example, in the case where a polarizer and a transparent protective film are used as the optical layer, from the viewpoint of balancing the adhesiveness to the polarizer and various transparent protective films, and the optical durability in a severe environment, the radical polymerizable compound is preferably used in combination of a monofunctional radical polymerizable compound and a multifunctional radical polymerizable compound.

[0080] <(Meth)acrylate containing an aromatic ring skeleton>

[0081] The adhesive composition used in the present application is preferred when it contains a (meth)acrylate containing an aromatic ring skeleton in addition to the metal oxide particles. From the viewpoint of more stably increasing the refractive index of the adhesive layer, in the present application, as the (meth)acrylate containing an aromatic ring skeleton, it is preferred to use a (meth)acrylate containing at least one selected from the group consisting of a (meth)acrylate having a polycyclic aromatic ring skeleton and a (meth)acrylate having two or more aromatic rings. As the (meth)acrylate containing an aromatic ring skeleton, for example, there can be mentioned: benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, oxirane-modified o-phenylphenol (meth)acrylate, a reaction product of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene with (meth)acrylic acid, and the like. Of these, it is more preferred to use phenoxybenzyl (meth)acrylate and phenoxyethyl (meth)acrylate, and it is particularly preferred to use phenoxybenzyl (meth)acrylate. Phenoxybenzyl (meth)acrylate is a compound having a structure represented by the following formula (A):

[0082] [Chemical Formula 1]

[0083]

[0084] In the above formula (A), X represents a single bond that becomes a part of an adjacent bonding group, or represents a structure that repeatedly has an oxirane, an oxetane, an oxetane, or an epoxystyrene structure. R represents a hydrogen atom or a methyl group. The adhesive composition used in the present application preferably contains phenoxybenzyl (meth)acrylate as an ortho- or meta-substituted compound represented by the following formula (A-1):

[0085] [Chemical Formula 2]

[0086] .

[0087] From the viewpoint of increasing the refractive index of the adhesive layer, when the total amount in the composition is taken as 100% by mass, the compounding amount of the (meth)acrylate containing an aromatic ring skeleton, particularly phenoxybenzyl (meth)acrylate, used is preferably 5 to 50% by mass.

[0088] In the case where the adhesive composition used in the present application contains at least one selected from the group consisting of isocyanurate compounds and polysiloxane compounds, the metal oxide particles are stably dispersed, and thus it is preferred.

[0089] From the viewpoint of effectively suppressing the generation of application streaks when the adhesive composition is applied to the first optical layer and / or the second optical layer, and further from the viewpoint of achieving thinness of the adhesive layer and the optical layer stack, it is preferable that the viscosity of the composition at 25°C be 100 [mPa-s] or less, and more preferably 60 [mPa-s] or less.

[0090] <Flowing agent>

[0091] The adhesive composition used in the present application preferably contains a polysiloxane compound as a flowing agent. By containing a polysiloxane compound in the composition, metal oxide particles are stably dispersed, thereby making the liquid stability of the adhesive composition excellent. Further, by containing metal oxide particles and a polysiloxane compound in the composition, the generation of shrinkage holes and bubbles at the time of application to an optical film can be suppressed.

[0092] <Polysiloxane compound>

[0093] The polysiloxane compound is a compound having a polysiloxane skeleton such as polydimethylsiloxane. In the present application, a modified polysiloxane compound having a reactive group is particularly preferable. As the reactive group possessed by the modified polysiloxane compound, a polymerizable functional group can be mentioned, and specifically, for example, a radical polymerizable functional group having an olefinic double bond such as a (meth)acryloyl group, a vinyl group, an allyl group, an epoxy group such as a glycidyl group, an oxetanyl group, a vinyl ether group, a cyclic ether group, a cyclic sulfide group, a lactone group, and a cationic polymerizable functional group can be mentioned. From the viewpoint of reactivity in the adhesive composition, a modified polysiloxane compound having a double bond as a reactive group is preferable, and a modified polysiloxane compound having a (meth)acryloyl group is more preferable. As for the amount of the polysiloxane compound to be compounded in the adhesive composition, when the total amount in the composition is taken as 100 mass%, 0.05 to 1.0 mass% is preferable.

[0094] In the case where a curable component is used as the active energy ray-curable component, the adhesive composition used in the present application can be used as an active energy ray-curable adhesive composition. For the above active energy ray-curable adhesive composition, in the case where an active energy ray such as an electron beam is used, the active energy ray-curable adhesive composition does not necessarily contain a photopolymerization initiator, but in the case where the adhesive composition used in the present application is of the "cationic / radical hybrid type" and the active energy ray is ultraviolet light or visible light, it is preferable to contain a photopolymerization initiator.

[0095] The photopolymerization initiator can be appropriately selected according to the active energy ray. In the case of curing by ultraviolet rays or visible light, a photopolymerization initiator that is cleaved by ultraviolet rays or visible light is used. As the above photopolymerization initiator, for example, benzoin, benzophenone, benzoylbenzoic acid, a benzophenone compound such as 3,3'-dimethyl-4-methoxybenzophenone, an aromatic ketone compound such as 4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone, a-hydroxy-a,a'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, a-hydroxycyclohexyl phenyl ketone, an acetophenone compound such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropane-l-one, a benzoin ether compound such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin methyl ether, an aromatic ketal compound such as benzil dimethyl ketal, an aromatic sulfonyl chloride compound such as 2-naphthalenesulfonyl chloride, a photoactive oxime compound such as l-phenyl-l,l-propanedione-2-(O-ethoxycarbonyl) oxime, a thioxanthone compound such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, camphorquinone, a haloketone, an acyloxyphosphine, an acylphosphonate, and the like can be exemplified.

[0096] When the total amount in the composition is taken as 100% by mass, the blending amount of the above photopolymerization initiator is preferably 0.5 to 5% by mass, and more preferably 1 to 4% by mass.

[0097] In addition, in the case of using the active energy ray-curable adhesive composition of the visible light-curable type, it is particularly preferable to use a photopolymerization initiator that has high sensitivity to light of 380 nm or more. The photopolymerization initiator that has high sensitivity to light of 380 nm or more will be described later.

[0098] As the above photopolymerization initiator, it is preferable to use alone a compound represented by the following general formula (3), or to use in combination a compound represented by the general formula (3) and a photopolymerization initiator that has high sensitivity to light of 380 nm or more, which will be described later.

[0099] [Chemical Formula 3]

[0100]

[0101] (In the formula, R 7 and R 8 represent -H, -CH2CH3, -iPr, or Cl, R 7 and R 8(thiophthalimide) and the like. Among them, 2-ethylthioxanthone is particularly preferable. When a compound represented by General Formula (3) is used, the adhesiveness is excellent compared to the case where a photopolymerization initiator having high sensitivity to light of 380 nm or more is used alone. Among the compounds represented by General Formula (3), R 7 and R 8 is diethylthioxanthone. As to the blending amount of the compound represented by General Formula (3) in the active energy ray-curable adhesive composition, when the total amount in the composition is taken as 100% by mass, it is preferably from 0.1 to 5% by mass, and more preferably from 0.3 to 3% by mass.

[0102] In addition, a polymerization initiation aid is preferably added as needed. As the polymerization initiation aid, triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid methyl ester, 4-dimethylaminobenzoic acid ethyl ester, 4-dimethylaminobenzoic acid isoamyl ester, and the like can be given, and 4-dimethylaminobenzoic acid ethyl ester is particularly preferable. When a polymerization initiation aid is used, the amount added is preferably from 0.1 to 2% by mass, and more preferably from 0.3 to 1% by mass, when the total amount in the composition is taken as 100% by mass.

[0103] In addition, a known photopolymerization initiator can be used in combination as needed. Since the optical functional layer and the substrate film have UV absorption ability and do not transmit light of 380 nm or less, as the photopolymerization initiator, a photopolymerization initiator having high sensitivity to light of 380 nm or more is preferably used. Specific examples include 2-methyl-l-(4-methylthiophenyl)-2-morpholinopropan-l-one, 2-benzyl-2-dimethylamino-l-(4-morpholinophenyl)-l-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-l-[4-(4-morpholinyl)phenyl]-l-butanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(η5-2,4-cyclopentadien-l-yl)bis(2,6-difluoro-3-(lH-pyrrol-l-yl)phenyl)titanium, and the like.

[0104] The optical laminate of the present application is an optical laminate in which at least a first optical layer and a second optical layer are laminated via an adhesive layer, wherein the adhesive layer is a cured product layer of the above-described adhesive composition.

[0105] The adhesive composition used in the present application contains metal oxide particles, but in the case where at least one selected from an isocyanurate compound and a polysiloxane compound is further contained, the metal oxide particles are stably dispersed, and thus the viscosity of the composition can be suppressed to a low level. Thereby, the adhesive composition can be thinly applied to the optical film, and thus the thickness of the adhesive layer can be reduced.

[0106] The thickness of the adhesive layer of the optical laminate of the present application is preferably 0.1 to 5 μm, more preferably 0.3 to 3.0 μm.

[0107] In the present application, as the first optical layer and the second optical layer constituting the optical laminate, there can be mentioned a phase difference layer, a polarizer, a transparent protective film, and the like.

[0108] As the phase difference layer, there can be mentioned a birefringent film obtained by subjecting a high molecular raw material to unidirectional or bidirectional stretching treatment, an oriented film of a liquid crystal polymer, a material obtained by using a film-supported liquid crystal polymer as an oriented layer, and the like. The thickness of the phase difference layer is not particularly limited, and is usually about 1 to 150 μm.

[0109] As the phase difference layer, a phase difference layer of a reverse wavelength dispersion type satisfying the following formulae (1) to (3) can be used:

[0110] 0.70 < Re

[450] / Re

[550] < 0.97 (1)

[0111] 1.5 x 10 -3 < Δn < 6 x 10 -3 (2)

[0112] 1.13 < NZ < 1.50 (3)

[0113] (In the formulae, Re

[450] and Re

[550] are the phase difference values in the plane of the phase difference layer measured at 23°C using light of wavelengths 450 nm and 550 nm, respectively, Δn is nx-ny when nx and ny are the refractive indices in the slow axis direction and the fast axis direction of the phase difference layer, respectively, and NZ is the ratio of the thickness-directional birefringence nx-nz to the in-plane birefringence nx-ny when nz is the refractive index in the thickness direction of the phase difference layer).

[0114] In the formation of the phase difference layer, it is preferable to use a liquid crystalline compound, and a solution containing the liquid crystalline compound can be coated using, for example, a wire bar, a slot coater, a comma coater, a gravure coater, a slit die, or the like. At this time, the coated liquid crystalline solution can be naturally dried, or can be heated and dried. Note that the liquid crystalline solution is preferably coated in a state of an isotropic phase at a concentration lower than the isotropic phase-liquid crystal phase transition concentration. In this case, it can be stably oriented by rubbing treatment, photo-orientation, or the like.

[0115] In the present application, the polarizer is not particularly limited, and various polarizers can be used. As the polarizer, for example, a film obtained by adsorbing iodine to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formaldehyde-treated polyvinyl alcohol-based film, an ethylene-vinyl acetate copolymer-based partially saponified film, and the like, and performing unidirectional stretching can be given. As the thickness of the polarizer, for example, 3 to 20 μm can be given.

[0116] However, it should be noted that, in the present application, from the viewpoint of improving the heating durability in a severe environment at a high temperature, as the polarizer, a thin polarizer having a thickness of 3 μm or more and 15 μm or less is preferably used. In particular, 12 μm or less, further preferably 10 μm or less, and particularly preferably 8 μm or less is preferable. Such a thin polarizer has a small thickness unevenness, is excellent in visual recognition, and has a small dimensional change, and thus is excellent in durability to thermal shock.

[0117] The polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and performing unidirectional stretching can be produced, for example, by dyeing by immersing the polyvinyl alcohol in an aqueous solution of iodine and stretching to 3 to 7 times the initial length. If necessary, it can be immersed in an aqueous solution of potassium iodide, etc., optionally containing boric acid, zinc sulfate, zinc chloride, etc. In addition, if necessary, the polyvinyl alcohol-based film can be immersed in water to perform water washing before dyeing. By water washing the polyvinyl alcohol-based film, not only dirt and an anti-blocking agent on the surface of the polyvinyl alcohol-based film can be cleaned, but also an uneven effect such as dyeing unevenness can be prevented by swelling the polyvinyl alcohol-based film. The stretching can be performed after dyeing with iodine, can be performed while dyeing, or can be performed after dyeing with iodine. The stretching can be performed in an aqueous solution of boric acid, potassium iodide, etc., or in a water bath.

[0118] From the viewpoint of stretching stability and reliability of humidification, it is preferable that the polarizer contain boric acid. In addition, from the viewpoint of suppressing the occurrence of a through crack, the content of boric acid contained in the polarizer is preferably 22% by mass or less, and further preferably 20% by mass or less, relative to the total amount of the polarizer. From the viewpoint of stretching stability and reliability of humidification, the content of boric acid is preferably 10% by mass or more, and further preferably 12% by mass or more, relative to the total amount of the polarizer.

[0119] As a representative thin polarizer, a thin polarizer described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014 / 077599, International Publication No. 2014 / 077636, or the like, or a thin polarizer obtained by a production method described in these documents can be given.

[0120] As the above thin polarizing film, in a production method including a process of stretching in a state of a laminate and a process of dyeing, from the viewpoint of being able to stretch to a high magnification so as to improve the polarizing performance, a thin polarizing film obtained by a production method including a process of stretching in an aqueous boric acid solution is preferred, and particularly a thin polarizing film obtained by a production method including a process of stretching in an aqueous boric acid solution and a process of dyeing, and a process of stretching in a gaseous atmosphere before the process of stretching in an aqueous boric acid solution is particularly preferred. These thin polarizing films can be obtained by a production method including a process of stretching a polyvinyl alcohol-based resin layer (hereinafter, also referred to as a PVA-based resin layer) and a resin substrate for stretching in a state of a laminate and a process of dyeing. If this production method is used, even if the PVA-based resin layer is thin, the PVA-based resin layer can be stretched by being supported by the resin substrate for stretching without causing a defect such as breakage due to stretching.

[0121] As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like can be used. As specific examples of such a thermoplastic resin, there can be mentioned a cellulose resin such as a cellulose triacetate resin film, a polyester resin, a polyether sulfone resin, a polysulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin, a (meth)acrylic resin, a cyclic polyolefin resin (norbornene-based resin), a polyarylate resin, a polystyrene resin, a polyvinyl alcohol resin, and a mixture thereof. One or more arbitrary appropriate additives can be contained in the transparent protective film. As the additives, for example, there can be mentioned an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloration preventive agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a colorant, and the like. The content of the above-described thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, further preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. In the case where the content of the above-described thermoplastic resin in the transparent protective film is 50% by weight or less, there is a risk that the high transparency and the like originally possessed by the thermoplastic resin cannot be sufficiently exhibited.

[0122] In addition, as a material forming the transparent protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferred, and particularly, a material having a moisture permeability of 150 g / m 2 / 24h or less is more preferred, a material having a moisture permeability of 140 g / m 2 / 24h or less is further preferred, and a material having a moisture permeability of 120 g / m 2 / 24h or less is particularly preferred.

[0123] A hard coat layer, an antireflection layer, an anti-sticking layer, a diffusion layer, or an antiglare layer, or the like, can be provided on the side of the transparent protective film that is not bonded to the polarizer. Note that the hard coat layer, the antireflection layer, the anti-sticking layer, the diffusion layer, the antiglare layer, or the like, can be provided as a layer other than the transparent protective film.

[0124] The thickness of the transparent protective film can be appropriately determined, and is generally about 1 to 500 μm, preferably about 1 to 300 μm, more preferably about 5 to 200 μm, further preferably about 10 to 200 μm, and still further preferably about 20 to 80 μm, from the viewpoints of strength, handling properties, thinness, and the like.

[0125] As the transparent protective film, a phase difference layer having a front surface phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more can be used. The front surface phase difference is generally controlled to a range of 40 to 200 nm, and the thickness direction phase difference is generally controlled to a range of 80 to 300 nm. When a phase difference layer is used as the transparent protective film, the phase difference layer also functions as the transparent protective film, and thus thinness can be achieved.

[0126] The optical laminate of the present application can be manufactured, for example, by the following manufacturing method.

[0127] The method is a manufacturing method of an optical laminate in which at least a first optical layer and a second optical layer are laminated via an adhesive layer, and the method includes:

[0128] a coating step of coating an adhesive composition on one or both of a bonding surface of the first optical layer and a bonding surface of the second optical layer;

[0129] a bonding step of bonding the first optical layer and the second optical layer,

[0130] an adhesive step of curing the adhesive composition by irradiating active energy rays from the side of the first optical layer or the side of the second optical layer, and bonding the first optical layer and the second optical layer via the adhesive layer formed by the curing,

[0131] the first optical layer is a liquid crystal-based phase difference layer,

[0132] the adhesive layer is a cured product layer of an adhesive composition containing at least a cationically polymerizable component, a cationic polymerization initiator, and metal oxide particles.

[0133] In the above coating step, as a method of applying the adhesive composition to one or both of the bonding surface of the first optical layer and the bonding surface of the second optical layer, any appropriate method can be selected depending on the viscosity of the composition and the target thickness, for example, a reverse coater, a gravure coater (direct, reverse, or offset), a bar reverse coater, a roll coater, a die coater, a wire bar coater, a rod coater, or the like can be used.

[0134] Note that, for the first optical layer and / or the second optical layer, a surface modification treatment can also be performed before the coating step. In particular, in the case where a polarizer is used as the optical film, it is preferable to perform a surface modification treatment on the polarizer. As the surface modification treatment, a treatment such as corona treatment, plasma treatment, ITRO treatment, or the like can be used, and corona treatment is particularly preferable. By performing corona treatment, reactive functional groups such as carbonyl groups and amino groups are generated on the surface of the polarizer, thereby improving the adhesion to the adhesive layer. In addition, foreign matter on the surface can be removed or the unevenness of the surface can be reduced by the ashing effect, thereby producing an optical laminate having excellent appearance characteristics.

[0135] The first optical layer and the second optical layer are bonded to each other (bonding step) using a roll laminator or the like via the adhesive composition applied as described above.

[0136] After the first optical layer and the second optical layer are bonded to each other, active energy rays (electron beams, ultraviolet rays, visible light, or the like) are irradiated to cure the adhesive composition and form an adhesive layer. The active energy rays (electron beams, ultraviolet rays, visible light, or the like) can be irradiated from any appropriate direction with respect to the irradiation direction.

[0137] In the case of irradiation of electron beams, the irradiation conditions are not particularly limited as long as the adhesive composition described above can be cured, and any appropriate conditions can be used. For example, the acceleration voltage of electron beam irradiation is preferably 5 kV to 300 kV, and further preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, there is a risk that the electron beams cannot reach the adhesive and the curing is insufficient, and if the acceleration voltage is greater than 300 kV, there is a risk that the penetration force is too strong and the first optical layer and the second optical layer are damaged. The irradiation dose is 5 to 100 kGy, and further preferably 10 to 75 kGy. If the irradiation dose is less than 5 kGy, the curing of the adhesive is insufficient, and if it is greater than 100 kGy, the first optical layer and the second optical layer are damaged, the mechanical strength is reduced, yellowing occurs, and the given optical characteristics cannot be obtained.

[0138] The electron beam irradiation is usually performed in a non-reactive gas, but can also be performed in the atmosphere or under conditions where a small amount of oxygen is introduced, as needed. Although depending on the materials of the first optical layer and the second optical layer, by appropriately introducing oxygen, oxygen inhibition can be intentionally caused in the first optical layer and the second optical layer where the electron beam is initially irradiated, thereby preventing damage to the first optical layer and the second optical layer, and the electron beam can be effectively irradiated only to the adhesive.

[0139] In the case of manufacturing the optical layer stack of the present application, as the active energy ray, it is preferable to use an active energy ray including visible light in the wavelength range of 380 nm to 450 nm, particularly an active energy ray in which the amount of irradiation of visible light in the wavelength range of 380 nm to 450 nm is the largest. In the case of using ultraviolet rays, visible light, when a transparent protective film (ultraviolet non-transmissive transparent protective film) endowed with ultraviolet absorption ability is used as the optical film, light of a wavelength shorter than about 380 nm is absorbed, and thus light of a wavelength shorter than 380 nm does not reach the curable resin composition and does not contribute to the polymerization reaction thereof. Further, light of a wavelength shorter than 380 nm absorbed by the first optical layer and the second optical layer is converted into heat, and the first optical layer or the second optical layer itself heats up, which becomes a cause of curling / folding and the like of the optical layer stack. Therefore, in the present application, in the case of using ultraviolet rays, visible light, it is preferable to use a device that does not emit light of a wavelength shorter than 380 nm as the active energy ray generating device, and more specifically, it is preferable that the ratio of the cumulative illuminance in the wavelength range of 380 nm to 440 nm to the cumulative illuminance in the wavelength range of 250 nm to 370 nm be 100:0 to 100:50, and more preferably 100:0 to 100:40. In the case of manufacturing the optical layer stack of the present application, as the active energy ray, it is preferable to use a metal halide lamp in which gallium is enclosed, or an LED light source that emits light in the wavelength range of 380 nm to 440 nm. Alternatively, a light source including ultraviolet rays and visible light such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, an incandescent lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a gallium lamp, an excimer laser, or sunlight can be used, and a band-pass filter can be used to block ultraviolet rays of a wavelength shorter than 380 nm. In order to improve the adhesive properties of the adhesive layer between the first optical layer and the second optical layer while preventing curling of the optical layer stack, it is preferable to use an active energy ray obtained using a metal halide lamp in which gallium is enclosed and with the aid of a band-pass filter that blocks light of a wavelength shorter than 380 nm, or an active energy ray of a wavelength of 405 nm obtained using an LED light source.

[0140] In the case of manufacturing the optical laminate of the present application using a continuous production line, the line speed is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and further preferably 10 to 100 m / min, although it depends on the curing time of the adhesive composition. In the case where the line speed is too small, productivity is poor, or the damage to the first optical layer and the second optical layer is too large, and an optical laminate that can withstand durability tests and the like cannot be produced. In the case where the line speed is too large, the curing of the adhesive composition becomes insufficient, and the desired adhesiveness cannot be obtained.

[0141] An adhesive layer for bonding to other members such as a liquid crystal cell can also be provided on the optical laminate of the present application. The adhesive forming the adhesive layer is not particularly limited, and an adhesive in which, for example, an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, or the like is used as a base polymer can be appropriately selected. An adhesive such as an acrylic adhesive, which is excellent in optical transparency and exhibits moderate wetting properties, cohesiveness, adhesiveness, and the like, and is excellent in weather resistance, heat resistance, and the like, can be particularly preferably used.

[0142] The adhesive layer can be provided on one or both surfaces of the optical laminate of the present application in the form of a stacked layer of layers having different compositions or kinds. In the case of being provided on both surfaces, adhesive layers having different compositions, kinds, thicknesses, and the like can be formed on the front and back surfaces of the optical laminate of the present application. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use, the bonding force, and the like, and is usually 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

[0143] With respect to the exposed surface of the adhesive layer, a separator can be temporarily bonded to cover it for the purpose of preventing contamination and the like until it is actually used. Thus, contact with the adhesive layer in the usual handling state can be prevented. As the separator, a conventional separator such as a separator obtained by coating a suitable thin layer such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, mesh, foamed sheet, metal foil, a laminate thereof, or the like with a suitable release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based release agent, as needed, can be used, provided that the thickness conditions described above are satisfied.

[0144] The optical laminate of the present application can be preferably used for formation of various devices such as liquid crystal display devices, and the like. The formation of the liquid crystal display device can be performed in the conventional manner. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell with a polarizing film or an optical laminate, and a constituent member such as an illumination system as needed, and incorporating a driving circuit, and the like, and in the present application, except for the use of the polarizing film or the optical laminate of the present application, there is no particular limitation, and it can be performed in the conventional manner. As to the liquid crystal cell, any type of liquid crystal cell such as a TN type, an STN type, a pi type, and the like can be used.

[0145] An appropriate liquid crystal display device such as a liquid crystal display device in which the optical laminate is disposed on one side or both sides of the liquid crystal cell, a liquid crystal display device in which a backlight or a reflection plate is used in the illumination system, and the like can be formed. In this case, the optical laminate of the present application can be disposed on one side or both sides of the liquid crystal cell. In the case where the optical laminates are disposed on both sides, they can be the same or different. Further, at the time of formation of the liquid crystal display device, one layer or two or more layers of an appropriate member such as a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, and the like can be disposed at an appropriate position.

[0146] Examples

[0147] Examples of the present application are described below, but the embodiments of the present application are not limited to these.

[0148] (Preparation of the adhesive composition)

[0149] Each component shown below was mixed in accordance with the compounding table described in Table 1 and stirred at 25°C for 1 hour, to obtain the adhesive composition used in Examples 1 to 8 and Comparative Examples 1 to 4. The values in the table represent % by weight when the total amount of the composition is taken as 100% by mass.

[0150] Each material constituting the adhesive composition is shown below.

[0151] (i) Cationically polymerizable component

[0152] • Aromatic epoxy compound (4,4'-dihydroxydiphenyl sulfone diglycidyl ether): Trade name "YDCN-4", manufactured by Tohto Kasei Co., Ltd.

[0153] • Difunctional oxetane compound (3-ethyl-3-(phenoxymethyl)oxetane): Trade name "OXT-221", manufactured by Toagosei Co., Ltd.

[0154] • Aliphatic epoxy compound (1,6-hexanediol diglycidyl ether): Trade name "EX-212L", manufactured by Nagase Chemtex Corporation

[0155] • Aromatic epoxy compound (1) (bisphenol A type epoxy resin): trade name "jER828", manufactured by Mitsubishi Chemical Corporation

[0156] • Aromatic epoxy compound (2) (biphenyl epoxy resin): trade name "EX-142-IM", manufactured by Nagase Chemtex Corporation

[0157] • Aromatic oxetane compound (xylyleneglycol bisoxetane): trade name "OXT-121", manufactured by Tsukishima Kika K.K.

[0158] • Aromatic epoxy compound (3) (p-tert-butylphenyl glycidyl ether): trade name "EX-146", manufactured by Nagase Chemtex Corporation

[0159] (ii) Free radical polymerizable compound

[0160] • Aromatic acrylate (phenoxybenzyl acrylate): trade name "LIGHT ACRYLATE POB-A", manufactured by Kyoeisha Chemical Co., Ltd.

[0161] • Hydroxyl group-containing (meth)acrylate (4-hydroxybutyl acrylate): trade name "4HBA", manufactured by Mitsubishi Chemical Corporation

[0162] • Aliphatic difunctional acrylate (1.9-nonanediol diacrylate): trade name "LIGHT ACRYLATE 1.9ND-A", manufactured by Kyoeisha Chemical Co., Ltd.

[0163] • Acryloyl morpholine: trade name "ACMO", manufactured by KJ Chemicals, Inc.

[0164] • Difunctional acrylate (tripropylene glycol diacrylate): trade name "ARONIX M-220", manufactured by Tsukishima Kika K.K.

[0165] (iii) Metal oxide particles

[0166] • Zirconium oxide dispersion 1: phenoxybenzyl acrylate dispersion of zirconium oxide having an average particle diameter of 20 nm (particle concentration 50% by weight)

[0167] • Zirconium oxide dispersion 2: phenyl glycidyl ether dispersion of zirconium oxide having an average particle diameter of 20 nm (particle concentration 30.3% by weight)

[0168] (iv) Other compounding agents

[0169] • Photoinitiator (1-hydroxycyclohexyl phenyl ketone): trade name "Omnirad 184", manufactured by IGM Resins B.V.

[0170] • Photoacid generator ((4-methylphenyl)[4-(2-methylpropyl)phenyl] iodonium Hexafluorophosphate (1-) 75% solution in propylene carbonate): trade name "Omnicat 250", manufactured by IGM Resins B.V.

[0171] • Photosensitizer (diethylthioxanthone): trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.

[0172] Note that the above zirconia dispersion 1 and zirconia dispersion 2 were manufactured by the following methods.

[0173] (Synthesis of dispersant A)

[0174] Tributylstannyl phenol 415 g (1 mol) and potassium hydroxide 1 g (0.018 mol) were added to an autoclave and mixed uniformly. To this reaction system, ethylene oxide (EO) 352 g (8 mol) was added dropwise at 130°C. After the dropwise addition of ethylene oxide was completed, the pressure was maintained at 0.1 MPa at 130°C for 1 hour for maturation, and an EO 8-mole adduct of tributylstannyl phenol was obtained.

[0175] The above tributylstannyl phenol EO 8-mole adduct 767 g (1 mol) and sodium monochloroacetate 152 g (1.3 mol) were added to a reactor and stirred to become uniform. Next, after the reaction system was added with sodium hydroxide 52 g at 60°C, the temperature was raised to 80°C, and maturation was performed for 3 hours. After maturation, the temperature was cooled to 50°C, and 98% sulfuric acid 117 g (1.2 mol) was added dropwise at the same temperature, and a white suspension solution was thus obtained. The white suspension solution was washed with distilled water, and the solvent was removed by distillation under reduced pressure, and dispersant A was obtained.

[0176] (Preparation of zirconia dispersion 1)

[0177] To 100 parts of a methyl ethyl ketone dispersion of zirconium oxide (manufactured by Nichigo, grade name "OZ-S40K-AC", average particle diameter (D50) based on dynamic light scattering method: 20 nm, zirconium oxide solid content: 30%), 1.5 parts of dispersant A and 28.5 parts of phenyl methacrylate (manufactured by Gohsenol, trade name "LIGHT ACRYLATE POB-A"; hereinafter referred to as "POB-A") were added and mixed. Next, the solvent was removed by distillation under reduced pressure using a rotary evaporator, thereby obtaining a zirconium oxide dispersion 1 as a monomer dispersion of zirconium oxide. The zirconium oxide dispersion 1 contained zirconium oxide / dispersant A / POB-A in a weight ratio of 50 / 2.5 / 47.5.

[0178] (Preparation of zirconium oxide dispersion 2)

[0179] To 100 parts of a methyl ethyl ketone dispersion of zirconium oxide (manufactured by Nichigo, grade name "OZ-S40K-AC", average particle diameter (D50) based on dynamic light scattering method: 20 nm, zirconium oxide solid content: 30%), 1.5 parts of dispersant A and 67.5 parts of phenyl glycidyl ether (manufactured by Nagase Chemtex, trade name "EX-142-IM") were added and mixed. Next, the solvent was removed by distillation under reduced pressure using a rotary evaporator, thereby obtaining a zirconium oxide dispersion 2 as a monomer dispersion of zirconium oxide. The zirconium oxide dispersion 2 contained zirconium oxide / dispersant A / EX-142-IM in a weight ratio of 30.3 / 1.5 / 68.2.

[0180] The following shows each material constituting the optical laminate.

[0181] <Manufacture of polarizer>

[0182] A stretched laminate was produced by performing auxiliary stretching in a gas atmosphere at a stretching temperature of 130°C on a laminate in which a 9 μm-thick PVA layer was formed on an amorphous PET substrate, next, a colored laminate was produced by performing dyeing on the stretched laminate, further, an optical film laminate containing a 5 μm-thick PVA layer stretched integrally with the amorphous PET substrate in such a manner that the total stretching ratio reached 5.94 times was produced by performing stretching on the colored laminate in a boric acid aqueous solution at a stretching temperature of 65°C. By such two-step stretching, the PVA molecules of the PVA layer formed on the amorphous PET substrate were highly oriented, and an optical film laminate containing a 5 μm-thick PVA layer constituting a thin polarizer in which iodine adsorbed by dyeing was highly oriented in one direction in the form of a polyiodide complex was obtained.

[0183] <Transparent protective film>

[0184] "TAC"; triacetyl cellulose (TAC) film (trade name "TJ25UL", thickness 25 μm, manufactured by FUJIFILM Corporation)

[0185] <Light-polymerizable liquid crystal composition>

[0186] A light-polymerizable liquid crystal compound (Paliocolor LC242 manufactured by BASF) which exhibits a nematic liquid crystal phase was dissolved in cyclopentanone to prepare a solution having a solid content concentration of 30% by weight. A surfactant (BYK-360 manufactured by BYK) and a photopolymerization initiator (Omnirad 907 manufactured by IGM Resins) were added to the solution to prepare a liquid crystal composition solution. The amounts of the surfactant and the photopolymerization initiator were set to 0.01 parts by weight and 3 parts by weight, respectively, with respect to 100 parts by weight of the light-polymerizable liquid crystal compound.

[0187] <λ / 2 phase difference layer>

[0188] A biaxially stretched norbornene-based film (ZEONOR Film manufactured by ZEON Corporation, thickness: 33 μm, front surface retardation: 135 nm) was used as a substrate, and the above-described liquid crystal composition was applied to the substrate by means of a wire bar coater in such a manner that the phase difference reached λ / 2, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, photopolymerization was performed by irradiation of ultraviolet rays having a cumulative light quantity of 400 mJ / cm 2 to obtain a laminate provided with a uniformly oriented liquid crystal layer.

[0189] <λ / 4 phase difference layer>

[0190] A biaxially stretched norbornene-based film (ZEONOR Film manufactured by ZEON Corporation, thickness: 33 μm, front surface retardation: 135 nm) was used as a substrate, and the above-described liquid crystal composition was applied to the substrate by means of a wire bar coater in such a manner that the phase difference reached λ / 4, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, photopolymerization was performed by irradiation of ultraviolet rays having a cumulative light quantity of 400 mJ / cm 2 to obtain a laminate provided with a uniformly oriented liquid crystal layer.

[0191] <Adhesive layer>

[0192] In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introducing tube, and a condenser, a monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged. Further, with respect to 100 parts by weight of the monomer mixture (solid content), 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate, and nitrogen gas replacement was performed while slowly stirring. Then, the liquid temperature in the flask was maintained at about 55°C to perform a polymerization reaction for 7 hours. Then, a solution of the (meth)acrylic polymer Al having a weight average molecular weight of 1.6 million and a solid content concentration of 30% was prepared by adding ethyl acetate to the obtained reaction solution. With respect to 100 parts by weight of the solid content of the obtained (meth)acrylic polymer Al solution, 0.1 parts by weight of Takenate D110N (trimethylolpropane phenyl dimethyl diisocyanate, manufactured by Mitsui Chemicals, Inc.) as an isocyanate crosslinking agent, 0.3 parts by weight of benzoyl peroxide (trade name: NYPER BMT, manufactured by NOF Corporation) as a peroxide crosslinking agent, and 0.08 parts by weight of KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent were mixed to prepare an acrylic adhesive composition. The acrylic adhesive composition was uniformly applied to the surface of a polyethylene terephthalate film (release liner) having a thickness of 38 μm, which was treated with a silicone-based release agent, using a spray coater, dried in an air-circulating constant temperature oven at 155°C for 2 minutes, and an adhesive layer 1 having a thickness of 7 μm was formed on the surface of the substrate.

[0193] < Polarizing film (1) >

[0194] The laminated optical film adhesive composition of Comparative Example 3 was applied to the surface of the PVA layer of the polarizer subjected to corona treatment at a treatment density of 50 W-min / m 2 using a corona treatment machine (treatment density: 50 W-min / m 2The corona-treated surfaces of the TAC film were then bonded together (lamination linear speed of 15 m / min). It should be noted that the coating thickness was measured using a spectroscopic interferometer (Ocean Optics: spectrometer "USB2000+", light source "HL-2000", fiber "OCF-103995"). Then, a visible light irradiation device (Heraeus Light HAMMER10 Mark III, valve: V-valve, peak illuminance: 1600 mW / cm²) was used. 2 Cumulative radiation dose 1000 mJ / cm 2 The irradiance and cumulative irradiation of the active energy rays were measured using Power Puck 2 (EIT Corporation, UVV measurement value). The active energy rays were irradiated from the TAC film side to cure the adhesive composition for the laminated optical film, thereby producing a polarizing film (1) formed by laminating an amorphous PET substrate, a polarizer, and a TAC film through the cured layer of the adhesive composition for the laminated optical film. The thickness of the cured layer of the adhesive composition for the laminated optical film was 1 μm.

[0195] <Polarizing film (2)>

[0196] Next, the amorphous PET substrate of the polarizing film (1) was peeled off, and the polarizing mirror surface of the peeled surface was treated with a corona treatment machine at a density of 50 W·min / m. 2 Corona treatment. Using a rolling mill, a release liner with an adhesive layer 1 was transferred to a corona-treated polarizing mirror surface to create an optical laminate (1) with an adhesive layer. The mirror was treated with the same corona treatment machine at a density of 50 W·min / m² using a rolling mill. 2 A polarizing film (2) consisting of a λ / 2 retardation film, a uniformly oriented liquid crystal layer after corona treatment, was bonded to the adhesive layer on the peel surface of the optical laminate (1) after the adhesive layer was peeled off, such that the slow axis of the λ / 2 retardation film was in a 15° relationship with the transmission axis of the polarizer. The bonding linear speed was 15 m / min.

[0197] (Example of optical laminate manufacturing)

[0198] The biaxially stretched norbornene film of the polarization film (2) was peeled off, and the λ / 2 phase difference film surface of the peeled surface was treated with a corona treatment machine at a density of 50 W·min / m 2The λ / 2 retardation film surface to which the adhesive composition of Examples 1 to 8 and Comparative Examples 1 to 3 described in Table 1 was applied was laminated to the uniform oriented liquid crystal layer surface of the λ / 4 retardation film subjected to the corona treatment at a line speed of 15 m / min using a roll laminator. Note that the application thickness was measured by a spectrometer (Ocean Optics Co., Ltd.: spectrometer "USB2000+", light source "HL-2000", fiber "OCF-103995"). 2 The λ / 2 retardation film surface to which the adhesive composition of Examples 1 to 8 and Comparative Examples 1 to 3 described in Table 1 was applied was laminated to the uniform oriented liquid crystal layer surface of the λ / 4 retardation film subjected to the corona treatment at a line speed of 15 m / min using a roll laminator. Note that the application thickness was measured by a spectrometer (Ocean Optics Co., Ltd.: spectrometer "USB2000+", light source "HL-2000", fiber "OCF-103995"). 2 2 The λ / 2 retardation film surface to which the adhesive composition of Examples 1 to 8 and Comparative Examples 1 to 3 described in Table 1 was applied was laminated to the uniform oriented liquid crystal layer surface of the λ / 4 retardation film subjected to the corona treatment at a line speed of 15 m / min using a roll laminator. Note that the application thickness was measured by a spectrometer (Ocean Optics Co., Ltd.: spectrometer "USB2000+", light source "HL-2000", fiber "OCF-103995").

[0199] Details of each evaluation method are described below.

[0200] <Adhesive composition liquid viscosity>

[0201] The viscosity of the adhesive composition used in Examples 1 to 8 and Comparative Examples 1 to 4 was measured using a viscometer TVE22LT manufactured by Toyo Seiki Co., Ltd.

[0202] <Refractive index measurement of adhesive layer (cured product layer)>

[0203] ​A cured product layer (monomer film) of the adhesive composition used in Examples 1 to 8 and Comparative Examples 1 to 4 was obtained by applying the adhesive composition (thickness 100 μm) used in Examples 1 to 8 and Comparative Examples 1 to 4 to a cyclic olefin polymer film (COP film), attaching the same COP film to the applied surface, and irradiating the above visible light with a active energy ray irradiation device. The refractive index in the plane and the refractive index in the thickness direction of the obtained cured product layer were measured respectively using a prism coupler SPA-4000 (manufactured by Sairon Technology), and the average value thereof was used as the average refractive index of the adhesive layer. The measurement temperature was set to 23°C, and the measurement wavelength was set to 594 nm.

[0204] <Shrinkage of the cured adhesive composition>

[0205] The shrinkage of the cured adhesive composition was measured using a resin shrinkage measuring device CUSTRON EU201C (manufactured by AcroEdge) by a laser displacement meter, and the shrinkage was calculated by the method described in Japanese Patent Application Laid-Open No. 2013-104869.

[0206] <Surface unevenness of the surface of the first optical layer (surface opposite to the surface of the adhesive layer side)>

[0207] A piece of the laminated optical film having a size of 10 cm x 5 cm was cut out, and a biaxially-stretched norbornene-based film attached to a λ / 4 retardation film of the laminated optical film was peeled off. The surface (λ / 4 retardation film surface) after the biaxially-stretched norbornene-based film was peeled off was scanned in a direction perpendicular to the direction of conveyance of the film at the time of applying the adhesive to the surface of the λ / 2 retardation film when the laminated optical film was manufactured, and the surface unevenness of the λ / 4 retardation film was measured. Specifically, as shown in FIG. 6, the height D1 at the apex of the highest convex portion with respect to the average line B obtained by linearly measuring the surface unevenness of the surface of the first optical layer 1 opposite to the surface of the adhesive layer side (λ / 4 retardation film surface), and the magnitude of the undulation represented by the sum (D1+D2) of the depth D2 of the lower of the two concave portions adjacent to the highest convex portion and the height D1 at the apex of the highest convex portion were measured. Figure 2

[0208] Note that the measurement of the surface unevenness was performed under the following conditions.

[0209] Measurement device: VertScan (registered trademark) (manufactured by Hikari System Co., Ltd., Model R5500G)

[0210] <Interference unevenness of the optical laminate including a polarizing film>

[0211] ​The polarizer composites of the examples and comparative examples were attached to aluminum reflectors using an acrylic adhesive (film thickness 25 μm) and evaluated by visual observation under a three-wavelength fluorescent lamp, based on the following criteria. The evaluation results are shown in Table 3.

[0212] ◎: No visual interference was detected

[0213] ○: Visually detected a small amount of interference unevenness, but it was permissible.

[0214] ×: Uneven interference was strongly visually identified.

[0215]

[0216] According to the results in Table 1, in the optical laminates of Comparative Examples 1-4, the surface roughness (undulation size) of the surface of the first optical layer opposite to the adhesive layer side is large to the extent exceeding 100 nm, thus the interference inhomogeneity of the optical laminate worsens. On the other hand, it can be seen that in the optical laminates of Examples 1-8, the surface roughness (undulation size) of the surface of the first optical layer opposite to the adhesive layer side is suppressed to below 100 nm, thus the interference inhomogeneity of the optical laminate can be sufficiently suppressed.

Claims

1. An optical laminate, wherein at least a first optical layer and a second optical layer are laminated via an adhesive layer. The first optical layer is a phase retardation layer of liquid crystal. The adhesive layer is a cured layer of an adhesive composition containing at least a cationic polymerizable component, a cationic polymerization initiator, and metal oxide particles. The surface of the first optical layer opposite to the adhesive layer side has the following surface irregularities. Surface unevenness: The magnitude of the undulation, expressed as the sum (D1+D2) of the height D1 at the apex of the highest convex portion relative to the average line described below and the depth D2 of the lower of the two concave portions adjacent to the highest convex portion, is less than 100 nm. The average line is the result of measuring the surface undulation of the surface opposite to the adhesive layer side of the first optical layer.

2. The optical laminate according to claim 1, wherein, The adhesive composition further contains a free radical polymerizable compound.

3. The optical laminate according to claim 1, wherein, The refractive index of the adhesive layer is 1.54 or higher.

4. The optical laminate according to claim 1, wherein, In the adhesive composition, when the total amount of the composition is set to 100% by mass, the content of the metal oxide particles is 5-50% by mass.

5. The optical laminate according to claim 1, wherein, The adhesive composition further contains (meth)acrylates comprising an aromatic ring backbone.

6. The optical laminate according to claim 5, wherein, The (meth)acrylate containing an aromatic ring skeleton contains at least one selected from (meth)acrylates having a polycyclic aromatic ring skeleton and (meth)acrylates having two or more aromatic rings.

7. The optical laminate according to claim 5, wherein, The (meth)acrylate containing an aromatic ring skeleton is phenoxybenzyl (meth)acrylate.

8. The optical laminate according to claim 1, wherein, The adhesive composition contains at least one selected from alicyclic epoxy compounds, aromatic epoxy compounds, aromatic oxobutane compounds, and difunctional oxobutane compounds as the cationic polymerizable component.

9. The optical laminate according to claim 1, wherein, The adhesive composition contains at least one selected from zinc oxide, zirconium oxide and titanium oxide as the metal oxide particles.

10. The optical laminate according to claim 1, wherein, The average particle size of the metal oxide particles is less than 100 nm.

11. The optical laminate according to claim 1, wherein, The thickness of the adhesive layer is 0.3~3.0μm.

12. A method for manufacturing an optical laminate, wherein the optical laminate is formed by stacking at least a first optical layer and a second optical layer via an adhesive layer. The method includes: Coating process: Apply an adhesive composition to one or both of the bonding surfaces of the first optical layer and the second optical layer; Bonding process: bonding the first optical layer and the second optical layer together; and Bonding process: The adhesive composition is cured by irradiating it with active energy rays from either the first optical layer side or the second optical layer side, and the first optical layer and the second optical layer are bonded together via the adhesive layer formed by the curing. The first optical layer is a phase retardation layer of liquid crystal. The adhesive layer is a cured layer of an adhesive composition containing at least a cationic polymerizable component, a cationic polymerization initiator, and metal oxide particles.

13. The method for manufacturing an optical laminate according to claim 12, wherein, The adhesive composition has a viscosity of less than 100 [mPa·s] at 25°C.

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