Optical laminate, polarizing plate and image display device

Abstract

To provide an optical laminate which can suppress degradation of adhesion and change of transmission image sharpness after a light resistance test.SOLUTION: An optical laminate has a first resin layer and a second resin layer on a base material, wherein the first resin layer has an area α1 and an area α2 surrounding the α1 independent of each other, the second resin layer has an area β1 and an area β2 surrounding the area β1 independent of each other, and satisfies the following conditions 1 and 2. 1. θa1 indicating an average inclination angle on the surface on the resin layer side of the base material, and θa2 indicating an average inclination angle on the surface on the second resin layer side of the first resin layer have a relation of θa2<θa1. 2. Pa1 indicating an arithmetic average height on the surface on the resin layer side of the base material and Pa2 indicating an arithmetic average height on the surface of the second resin layer side of the first resin layer have a relation of Pa2<Pa1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an optical laminate, a polarizing plate, and an image display device. [Background technology]

[0002] BACKGROUND ART An optical laminate is sometimes placed on the surface of an image display device such as a monitor of a television, notebook PC, or desktop PC in order to impart antifouling properties, antireflection properties, antiglare properties, and the like.

[0003] The optical laminate has a basic structure having an optical functional layer on a substrate. The optical laminate is often used as a surface member of an image display device or the like, and therefore is frequently exposed to contact with human fingers, objects, etc. Therefore, it is preferable that the optical laminate has a good pencil hardness.

[0004] In order to improve the pencil hardness of the optical laminate, a cured product of a curable resin composition is preferably used as the binder resin for the optical functional layer. A cured product of a curable resin composition can easily improve the pencil hardness of an optical laminate, but tends to have poor adhesion to a substrate. Patent Documents 1 and 2 propose optical laminates that use a cured product of a curable resin composition as a binder resin for an optical functional layer and have good adhesion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-234163 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-188772 Summary of the Invention [Problem to be solved by the invention]

[0006] The optical laminates of Patent Documents 1 and 2 have good initial adhesion. However, the optical laminates of Patent Documents 1 and 2 may experience a decrease in adhesion over time or a change in optical properties. Specifically, when a light resistance test by ultraviolet irradiation was performed on the optical laminates of Patent Documents 1 and 2, the adhesion may have decreased or the transmission image sharpness may have changed.

[0007] An object of the present disclosure is to provide an optical laminate capable of suppressing a decrease in adhesion and a change in transmission image sharpness after a light resistance test, as well as a polarizing plate and an image display device using the same. [Means for Solving the Problems]

[0008] The present disclosure provides the following optical laminates, polarizing plates, and image display devices of [1] to [3]. [1] An optical laminate having a resin layer on a substrate, The resin layer has, from the substrate side, a first resin layer and a second resin layer, The first resin layer has a region α1 independent of each other and a region α2 surrounding the region α1, and the resin contained in the region α1 is different from the resin contained in the region α2. The second resin layer has a region β1 independent of each other and a region β2 surrounding the region β1, and the resin contained in the region β1 is different from the resin contained in the region β2. An optical laminate that satisfies the following Condition 1 or Condition 2. [Condition 1] θa1 indicating the average inclination angle of the surface of the substrate on the resin layer side and θa2 indicating the average inclination angle of the surface of the first resin layer on the second resin layer side have a relationship of θa2 < θa1. [Condition 2] Pa1 indicating the arithmetic mean height of the surface of the substrate on the resin layer side and Pa2 indicating the arithmetic mean height of the surface of the first resin layer on the second resin layer side have a relationship of Pa2 < Pa1. [2] A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical laminate described in [1]. [3] An image display device having the optical laminate according to [1] above on a display element. [Effects of the Invention]

[0009] The optical laminate, polarizing plate, and image display device of the present disclosure can suppress a decrease in adhesion and a change in transmitted image clarity after a light resistance test. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment of an optical laminate of the present disclosure. [Figure 2] 10 is a diagram illustrating a method for calculating the position of a region α1 in the thickness direction of a first resin layer. FIG. [Figure 3] 1 is a cross-sectional view illustrating an embodiment of an image display device according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described. [Optical laminate] The optical laminate of the present disclosure has a resin layer on a substrate, the resin layer has, from the base material side, a first resin layer and a second resin layer, the first resin layer has a region α1 that is independent of each other and a region α2 that surrounds the region α1, and a resin contained in the region α1 is different from a resin contained in the region α2, the second resin layer has a region β1 that is independent of each other and a region β2 that surrounds the region β1, and a resin contained in the region β1 is different from a resin contained in the region β2, It satisfies the following condition 1 or condition 2. <Condition 1> The relationship is θa2 < θa1, where θa1 represents the average inclination angle of the surface of the base material on the resin layer side, and θa2 represents the average inclination angle of the surface of the first resin layer on the second resin layer side. <Condition 2> The relationship is Pa2 < Pa1, where Pa1 represents the arithmetic mean height of the surface of the base material on the resin layer side, and Pa2 represents the arithmetic mean height of the surface of the first resin layer on the second resin layer side.

[0012] FIG. 1 is a cross-sectional view showing an embodiment of the optical laminate 100 of the present disclosure. The optical laminate 100 of FIG. 1 has a resin layer 20 on a base material 10. Further, the resin layer 20 of FIG. 1 has a first resin layer 21 and a second resin layer 22 from the base material 10 side. In addition, the first resin layer 21 of FIG. 1 has regions α1 independent of each other and a region α2 surrounding the region α1. Further, the second resin layer 22 of FIG. 1 has regions β1 independent of each other and a region β2 surrounding the region β1. In this specification, a structure having regions n1 independent of each other and a region n2 surrounding the region n1, such as the first resin layer and the second resin layer of FIG. 1, may be referred to as a "sea-island structure". Note that FIG. 1 is a schematic cross-sectional view. That is, the scales of each layer constituting the optical laminate 100, the scales of each material, and the scales of the surface irregularities are schematized for easy illustration and are different from the actual scales. The same applies to the figures other than FIG. 1, which are also different from the actual scales.

[0013] <Base material> The substrate preferably has good light transmittance, smoothness, heat resistance, and mechanical strength. Examples of such substrates include resin substrates containing resins such as polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, acrylic resin, polycarbonate, polyurethane, and amorphous olefin (cycloolefin polymer: COP). The resin substrate may be a laminate of two or more resin substrates. The resin substrate is preferably subjected to a stretching treatment in order to improve mechanical strength and dimensional stability.

[0014] Among resin substrates, acrylic resin substrates are preferred because they have low hygroscopicity and therefore good dimensional stability, and low optical anisotropy and therefore good visibility. Furthermore, by using a resin layer coating liquid with a predetermined composition and drying conditions, the acrylic resin substrate satisfies condition 1 or 2 and can easily form the first and second resin layers into a sea-island structure. Because acrylic resin substrates are hard and brittle, it is difficult to achieve good adhesion when another layer is formed on the acrylic resin substrate. In particular, when a hard resin layer, such as a resin layer containing a cured product of a curable resin composition, is formed on the acrylic resin substrate, the adhesion between the substrate and the resin layer is likely to be insufficient. The optical laminate of the present disclosure satisfies condition 1 or condition 2, even when a resin layer containing a cured product of a curable resin composition is formed on the acrylic resin substrate, and the resin layer has a sea-island structure, which makes it possible to suppress a decrease in adhesion and to easily suppress a change in image clarity. In this specification, the acrylic resin means an acrylic resin and / or a methacrylic resin.

[0015] The acrylic resin contained in the acrylic resin substrate is not particularly limited, but is preferably, for example, one obtained by polymerizing one or more (meth)acrylic acid alkyl esters in combination, and more specifically, one obtained using methyl (meth)acrylate. Examples of acrylic resins include those described in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005-146084. Examples of acrylic resins that may be used include those having a ring structure, such as an acrylic resin having a lactone ring structure or an acrylic resin having an imide ring structure.

[0016] The acrylic resin preferably has a glass transition point (Tg) of 100°C or higher and 150°C or lower, more preferably 105°C or higher and 135°C or lower, and even more preferably 110°C or higher and 130°C or lower. When the glass transition point of the acrylic resin is 100°C or higher, it is possible to easily prevent the acrylic resin substrate from excessively dissolving when the resin layer is formed.When the glass transition point of the acrylic resin is 150°C or lower, it is possible to easily control the degree of dissolution of the acrylic resin substrate when the resin layer is formed.

[0017] The acrylic resin substrate may contain a resin other than acrylic resin, but the proportion of acrylic resin relative to all resins constituting the acrylic resin substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0018] The acrylic resin substrate can be produced, for example, by melt-extruding pellets made of humidity-conditioned acrylic resin, stretching the pellets in the machine direction while cooling them, and then stretching them in the transverse direction. In the melt extrusion step, a single screw, twin screws, or two or more screws can be used, and the rotation direction, rotation speed, and melt temperature of the screw can be set arbitrarily. Stretching is preferably carried out so that the film has a desired thickness after stretching. The stretching ratio is not limited, but is preferably 1.2 times or more and 4.5 times or less. The temperature and humidity during stretching can be determined as desired. A conventional stretching method may be used.

[0019] The resin, such as an acrylic resin, contained in the resin substrate preferably has a weight-average molecular weight of 10,000 or more and 500,000 or less, and more preferably 50,000 or more and 300,000 or less. By setting the weight-average molecular weight of the resin within the above range, condition 1, condition 2, and the above-mentioned sea-island structure can be easily controlled.

[0020] The average thickness of the substrate is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 35 μm or more. By making the average thickness of the substrate 10 μm or more, the handleability of the optical laminate can be improved. The average thickness of the substrate is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. By setting the average thickness of the substrate to 100 μm or less, the bending resistance of the optical laminate can be more easily improved.

[0021] The average thickness of the substrate mentioned above refers to the average thickness of the substrate when the optical laminate is completed. As will be described later, the average thickness of the substrate when the optical laminate is completed may be reduced from the initial average thickness of the substrate due to partial dissolution of the substrate by the resin layer coating liquid. For this reason, it is preferable that the initial average thickness of the substrate is greater than the average thickness of the substrate when the optical laminate is completed. The difference between the initial average thickness of the substrate and the average thickness of the substrate when the optical laminate is completed cannot be generalized because it varies depending on the thickness of the resin layer, the composition of the resin layer coating liquid, the drying conditions of the coating liquid, etc., but is preferably 0.1 μm to 10 μm, more preferably 1 μm to 5 μm.

[0022] The average thickness of the substrate can be calculated by, for example, selecting 20 arbitrary points in a cross-sectional photograph of the optical laminate taken with a scanning transmission electron microscope (STEM) and averaging the results. The acceleration voltage of the STEM is preferably 10 kV to 30 kV, and the magnification of the STEM is preferably 1000x to 7000x. In order to measure the average thickness of the substrate, the thickness of the first resin layer, the thickness of the second resin layer, the position of region α1 in the thickness direction of the first resin layer, the position of the first particle in the thickness direction of the resin layer, θa1, θa2, Pa1, Pa2, etc., it is necessary to prepare a measurement sample in which the cross section of the optical laminate is exposed. The sample can be prepared, for example, by the following steps (A1) to (A2). Note that if the interface is difficult to see due to insufficient contrast, the sample may be stained with osmium tetroxide, ruthenium tetroxide, phosphotungstic acid, or the like as a pretreatment.

[0023] (A1) The optical laminate is cut to a desired size to prepare a cut sample, and then the cut sample is embedded in a resin to prepare an embedded sample. The size of the cut sample is, for example, a strip of 10 mm length x 3 mm width. The resin used for embedding is preferably an epoxy resin. An embedded sample can be obtained, for example, by placing a cut sample in a silicon embedding plate, pouring in embedding resin, hardening the embedding resin, and then removing the cut sample and the embedding resin from the silicon embedding plate. In the case of the epoxy resin manufactured by Struers, as exemplified below, the aforementioned hardening step is preferably carried out by leaving it at room temperature for 12 hours. The embedded sample is in the shape of a block. The silicone embedding plate may be, for example, one manufactured by Dosaka EM Co., Ltd. The silicone embedding plate is also sometimes called a silicone capsule. The epoxy resin used for embedding may be, for example, a 10:1.2 mixture of "Epofix" (trade name) manufactured by Struers and "Epofix Hardener" (trade name) manufactured by the same company.

[0024] (A2) The block-shaped embedded sample is cut vertically to expose the cross section of the optical laminate, thereby preparing a measurement sample. A thin slice cut from the block-shaped embedded sample is used as the measurement sample (the conditions for the measurement sample will be described later). The embedded sample is preferably cut so as to pass through the center of the cut sample. The embedded sample is preferably cut with a diamond knife. An example of an apparatus for cutting an embedded sample is the Ultramicrotome EM UC7 manufactured by Leica Microsystems. When cutting an embedded sample, it is preferable to first roughly cut it (coarse trimming) and then finally precisely trim it under the conditions of "SPEED: 1.00 mm / s" and "FEED: 70 nm." Among the slices cut from the block-shaped embedded sample as described above, slices that are free of defects such as holes and have a uniform thickness of 60 nm to 100 nm can be used as samples for measuring the average thickness of the substrate, the thickness of the first resin layer, the thickness of the second resin layer, the position of region α1 in the thickness direction of the first resin layer, the position of the first particle in the thickness direction of the resin layer, θa1, θa2, Pa1, Pa2, the particle diameter of the first particle, and the particle diameter of the inorganic microparticles.

[0025] In this specification, unless otherwise specified, the atmosphere in which various measurements and evaluations, and sampling for the measurements and evaluations are carried out is a temperature of 23±5°C and a relative humidity of 40% to 65%. Furthermore, before carrying out the measurements, evaluations, and sampling, the optical laminate to be measured is exposed to the above atmosphere for 30 minutes or more.

[0026] The substrate may contain additives such as antioxidants, UV absorbers, light stabilizers, and plasticizers. To improve adhesion, the surface of the substrate may be subjected to a physical or chemical treatment such as corona discharge treatment, or an easy-adhesion layer may be formed.

[0027] <Resin layer> The resin layer must have, from the substrate side, a first resin layer and a second resin layer. By having the first resin layer and the second resin layer as the resin layer, it is possible to improve adhesion and easily suppress a decrease in pencil hardness.

[0028] When the resin layer is a single layer, it is difficult to improve the flex resistance or pencil hardness of the optical laminate. For example, when the resin layer is a single layer with high hardness, it is difficult to improve the flex resistance of the optical laminate. Also, when the resin layer is a single layer with low hardness, it is difficult to improve the pencil hardness of the optical laminate.

[0029] The first and second resin layers can be formed, for example, by applying a resin layer coating liquid containing a resin component and a solvent onto a substrate, drying the coating liquid, and optionally curing the coating liquid. The resin layer coating liquid may further contain first particles, inorganic fine particles, and additives, as required. In the above-mentioned method, for example, the resin layer coating liquid dissolves a part of the substrate, and a first resin layer is formed by a region containing a small amount of the resin component of the resin layer coating liquid, mainly composed of the resin component eluted from the substrate.Furthermore, the content of the resin component eluted from the substrate is small, and a second resin layer can be formed by a region mainly composed of the resin component of the resin layer coating liquid.That is, in the above-mentioned method, the first resin layer and the second resin layer can be formed by a single application using one resin layer coating liquid.Furthermore, since the second resin layer formed by the above-mentioned method contains a small amount of the resin component eluted from the substrate, it is easy to achieve good pencil hardness. In the above-mentioned method, it is essential that the resin layer coating liquid has a predetermined composition and is dried under predetermined conditions. The predetermined composition and the predetermined drying conditions will be described later. The method for applying the resin layer coating liquid onto the substrate is not particularly limited, and examples thereof include general-purpose coating methods such as spin coating, dipping, spraying, die coating, bar coating, gravure coating, roll coating, meniscus coating, flexographic printing, screen printing, and bead coating. When curing the resin layer coating liquid, it is preferable to irradiate it with ionizing radiation such as ultraviolet light and electron beams. Specific examples of ultraviolet light sources include ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, and metal halide lamps. The wavelength of the ultraviolet light is preferably in the range of 190 nm to 380 nm. Specific examples of electron beam sources include various electron beam accelerators such as Cockcroft-Waldt type, Van de Graaf type, resonant transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type.

[0030] The first resin layer has an independent region α1 and a region α2 surrounding the region α1, and the resin contained in the region α1 must be different from the resin contained in the region α2. Furthermore, the second resin layer has an independent region β1 and a region β2 surrounding the region β1, and the resin contained in the region β1 must be different from the resin contained in the region β2. When the first resin layer has the region α1 and the region α2, and the second resin layer has the region β1 and the region β2, it becomes easier to improve the adhesion after the light resistance test.

[0031] The resin contained in region α1 and the resin contained in region α2 being different means that at least one of the resin composition and molecular weight is different. The resin contained in region α1 and the resin contained in region α2 preferably have different resin compositions. Examples of resin compositions that are different include when region α1 and region α2 contain different types of resin, or when region α1 and region α2 contain the same type of resin but with different resin mixing ratios. The resin contained in region β1 and the resin contained in region β2 are different from each other in terms of at least one of the composition and molecular weight of the resin. The resin contained in region β1 and the resin contained in region β2 preferably have different resin compositions. Examples of resin compositions that are different include when region β1 and region β2 contain different types of resin, or when region β1 and region β2 contain the same type of resin but in different resin mixing ratios.

[0032] In this specification, the resins in the regions α1, α2, β1, and β2 refer to so-called binder resins. Therefore, particles such as the first particles described below do not refer to the resins in the regions α1, α2, β1, and β2.

[0033] If the proportion of region α1 is high, the hardness is likely to be insufficient, and if the proportion of region α2 is high, the adhesion is likely to deteriorate. Therefore, the area ratio of region α1 to region α2 is preferably 1:99 to 10:90, and more preferably 2:98 to 5:95. If the proportion of region β1 is high, the hardness is likely to be insufficient, and if the proportion of region β2 is high, the adhesion is likely to deteriorate. Therefore, the area ratio of region β1 to region β2 is preferably 5:95 to 50:50, and more preferably 10:90 to 40:60. The above area ratio can be calculated from a cross-sectional photograph of the optical laminate taken with a scanning transmission electron microscope (STEM). To increase the reliability of the numerical value, multiple cross-sectional photographs are taken, and the total number of regions α1 or β1 is set to 50 or more, and then the area ratio is calculated.

[0034] In the first resin layer and the second resin layer, it is preferable that the resin contained in region α1 is substantially the same as the resin contained in region β2, and it is also preferable that the resin contained in region α2 is substantially the same as the resin contained in region β1. This configuration makes it easier to improve adhesion after a light resistance test. The reason why this configuration makes it easier to improve adhesion after a light resistance test is thought to be that the affinity between the first resin layer and the second resin layer is increased, making it less likely that the adhesion at the interface between the first resin layer and the second resin layer will decrease, even in harsh environments such as light resistance tests.

[0035] In order to facilitate the configuration of the first resin layer to have the region α1 and the region α2, and in order to facilitate the configuration of the second resin layer to have the region β1 and the region β2, it is preferable to reduce the compatibility between the components contained in the coating liquid for the resin layer, or to reduce the compatibility between the components contained in the coating liquid for the resin layer and the components dissolved from the substrate. It is believed that by lowering the compatibility as described above, the following phenomena (1) to (4) make it easier to form the configurations of the first resin layer and the second resin layer of the present disclosure. (1) When the resin layer coating liquid is applied to the substrate, a part of the substrate dissolves. (2) The region containing the resin component eluted from the substrate as the main component and a small amount of the resin component of the coating liquid for the resin layer becomes the first resin layer, and the region containing a small amount of the resin component eluted from the substrate and containing the resin component of the coating liquid for the resin layer as the main component becomes the second resin layer. (3) Due to the low compatibility, in the above (2), the resin component of the coating liquid for the resin layer contained in small amounts in the first resin layer forms region α1, and the resin component eluted from the substrate forms region α2. (4) Due to the low compatibility, during the above (2), the resin component dissolved from the substrate contained in a small amount in the second resin layer forms region β1, and the resin component of the coating liquid for the resin layer forms region β2.

[0036] When the region closer to the substrate than the center of the thickness direction of the first resin layer is defined as the first region, and the region closer to the second resin layer than the center of the thickness direction of the first resin layer is defined as the second region, it is preferable that 70% or more of the region α1 exists in the second region. By having the above-mentioned configuration, it is easier to improve adhesion after a light resistance test.

[0037] The proportion of the regions α1 present in the second region is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more, on a number basis.

[0038] In this specification, the position where the region α1 exists in the thickness direction of the first resin layer is determined by the following methods (1) to (5). (1) A cross-sectional photograph of the optical laminate is taken using a scanning transmission electron microscope (STEM). The acceleration voltage of the STEM is preferably 10 kV to 30 kV, and the magnification of the STEM is preferably 1000 times to 7000 times. (2) Based on the cross-sectional photograph, the average elevation X1 of the ridgeline on the surface of the first resin layer facing the substrate and the average elevation X2 of the ridgeline on the surface of the first resin layer facing the second resin layer are calculated (see symbols X1 and X2 in Figure 2). (3) The midpoint between the elevations X1 and X2 is defined as the center M in the thickness direction of the first resin layer (see symbol M in FIG. 2). (4) Based on the cross-sectional photograph, count the number of regions α1 present in the first region on the substrate side of the center of the first resin layer in the thickness direction and the number of regions α1 present in the second region on the second resin layer side of the center of the first resin layer in the thickness direction. For regions α1 present in both the first region and the second region across the center of the first resin layer in the thickness direction, allocate the number to the first region and the second region according to the area proportion of region α1. For example, for a region α1 whose area proportion in the first region is 40% and whose area proportion in the second region is 60%, allocate 0.4 to the first region and 0.6 to the second region. (5) To increase the reliability of the numerical values, multiple cross-sectional photographs are taken, the total number of regions α1 is set to 50 or more, and the number-based proportion of regions α1 present in the first and second regions is calculated.

[0039] The thickness of the entire resin layer (in other words, the total thickness of the first resin layer and the second resin layer) is preferably 4.0 μm or more, more preferably 5.0 μm or more, and even more preferably 6.0 μm or more, and the upper limit is preferably 15.0 μm or less, more preferably 12.0 μm or less, and even more preferably 10.0 μm or less. The average thickness t1 of the first resin layer is preferably 3.0 μm or more, more preferably 4.0 μm or more, and even more preferably 4.5 μm or more, and is preferably 10.0 μm or less, more preferably 8.0 μm or less, and even more preferably 7.0 μm or less. By setting t1 to 3.0 μm or more, it is possible to easily improve adhesion and flex resistance, and by setting t1 to 10.0 μm or less, it is possible to easily suppress a decrease in pencil hardness. The average thickness t2 of the second resin layer is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1.0 μm or more, and is preferably 4.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.7 μm or less. By setting t2 to 0.3 μm or more, it is possible to easily improve pencil hardness, and by setting t2 to 4.0 μm or less, it is possible to easily suppress a decrease in flex resistance.

[0040] In order to easily prevent a decrease in adhesion and flex resistance, t1 / t2 is preferably 1.5 or more, more preferably 1.8 or more, and even more preferably 2.0 or more. In addition, in order to easily improve pencil hardness, t1 / t2 is preferably 10.0 or less, more preferably 5.0 or less, and even more preferably 3.0 or less.

[0041] The average thickness of the first resin layer and the average thickness of the second resin layer can be calculated by, for example, selecting 20 arbitrary points in a cross-sectional photograph of the optical laminate taken with a scanning transmission electron microscope (STEM) and averaging the thicknesses. The acceleration voltage of the STEM is preferably 10 kV to 30 kV, and the magnification of the STEM is preferably 1000x to 7000x.

[0042] <Resin component> The resin layer preferably contains a cured product of a curable resin composition as a resin component. When the resin layer contains a cured product of a curable resin composition, the pencil hardness of the optical laminate can be easily improved.

[0043] The proportion of the curable resin composition to the total amount of resin components in the coating liquid for the resin layer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 100% by mass.

[0044] Examples of the cured product of the curable resin composition include a cured product of a thermosetting resin composition and a cured product of an ionizing radiation curable resin composition. Among these, a cured product of an ionizing radiation curable resin composition is preferred, because it is easy to increase the pencil hardness and is easy to dissolve a substrate in the uncured composition state.

[0045] The thermosetting resin composition is a composition that contains at least a thermosetting resin and is a resin composition that is cured by heating. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, silicone resins, etc. In the thermosetting resin composition, a curing agent is added to the curable resin as needed.

[0046] The ionizing radiation-curable resin composition is a composition containing a compound having an ionizing radiation-curable functional group (hereinafter also referred to as "ionizing radiation-curable compound"). Examples of the ionizing radiation-curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups. As the ionizing radiation-curable compound, a compound having an ethylenically unsaturated bond group is preferred. Ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Usually, ultraviolet rays or electron beams are used, but other types of radiation such as electromagnetic waves (e.g., X-rays and gamma rays), and charged particle beams (e.g., alpha rays and ion beams) can also be used. In this specification, the term "(meth)acryloyl group" refers to an acryloyl group or a methcroyl group, and the term "(meth)acrylate" refers to an acrylate or a methacrylate.

[0047] The ionizing radiation-curable compound may be a monofunctional ionizing radiation-curable compound having one ionizing radiation-curable functional group or a polyfunctional ionizing radiation-curable compound having two or more ionizing radiation-curable functional groups. The ionizing radiation-curable compound may be either a monomer or an oligomer. Monofunctional ionizing radiation-curable monomers tend to have good compatibility with other resin components, making it difficult to form a sea-island structure in the first resin layer and the second resin layer. When using a monofunctional ionizing radiation-curable monomer, the aforementioned characteristics should be taken into consideration. In order to dissolve a portion of the substrate, form a sea-island structure in the first and second resin layers, increase pencil hardness, and facilitate suppression of cure shrinkage, it is preferable to use a mixture of the following (a) to (c) as the ionizing radiation-curable compound. The following (a) to (c) are preferably compounds having an ethylenically unsaturated bond group as the ionizing radiation-curable functional group, and more preferably (meth)acrylate-based compounds. As the (meth)acrylate-based compound, compounds in which part of the molecular skeleton has been modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like can also be used. (a) Difunctional ionizing radiation-curable monomer (b) Tri- or higher functional ionizing radiation curable monomer (c) Polyfunctional ionizing radiation-curable oligomer

[0048] By including the difunctional ionizing radiation-curable monomer (a) as the ionizing radiation-curable compound, it is possible to make it easier to dissolve a portion of the substrate, thereby making it easier to increase θa1 or Pa1. However, if the amount of the difunctional ionizing radiation-curable monomer (a) is too large, the substrate may be dissolved excessively, which may reduce the strength of the substrate or the pencil hardness of the optical laminate. By including the trifunctional or higher ionizing radiation-curable monomer (b) as the ionizing radiation-curable compound, the pencil hardness of the optical laminate can be easily improved. However, if the amount of the trifunctional or higher ionizing radiation-curable monomer (b) is too large, the hardness of the resin layer may become too high, which may reduce the flex resistance of the optical laminate. By including the polyfunctional ionizing radiation-curable oligomer (c) as the ionizing radiation-curable compound, it is possible to easily suppress cure shrinkage while maintaining the pencil hardness of the optical laminate. However, if the amount of the polyfunctional ionizing radiation-curable oligomer (c) is too large, the pencil hardness of the optical laminate may decrease.

[0049] The amount of the difunctional ionizing radiation-curable monomer (a) relative to the total amount of the ionizing radiation-curable compounds is preferably 10% by mass or more and 40% by mass or less, more preferably 13% by mass or more and 30% by mass or less, and even more preferably 15% by mass or more and 25% by mass or less. The amount of the tri- or higher functional ionizing radiation-curable monomer (b) relative to the total amount of the ionizing radiation-curable compound is preferably 25% by mass or more and 55% by mass or less, more preferably 30% by mass or more and 50% by mass or less, and even more preferably 35% by mass or more and 45% by mass or less. The amount of (c) the polyfunctional ionizing radiation-curable oligomer relative to the total amount of the ionizing radiation-curable compounds is preferably 25% by mass or more and 55% by mass or less, more preferably 30% by mass or more and 50% by mass or less, and even more preferably 35% by mass or more and 45% by mass or less.

[0050] Examples of the (a) difunctional ionizing radiation curable monomer include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexanediol diacrylate.

[0051] Examples of the trifunctional or higher ionizing radiation-curable monomer (b) include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate. The number of functional groups in the tri- or higher functional ionizing radiation-curable monomer (b) is preferably 3 or more and 5 or less, more preferably 3 or more and 4 or less, and even more preferably 3, in order to increase the pencil hardness while suppressing cure shrinkage.

[0052] Examples of the polyfunctional ionizing radiation-curable oligomer (c) include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Urethane (meth)acrylates can be obtained, for example, by reacting a polyhydric alcohol and an organic diisocyanate with a hydroxy (meth)acrylate. Preferred epoxy (meth)acrylates are (meth)acrylates obtained by reacting a tri- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with (meth)acrylic acid; (meth)acrylates obtained by reacting a di- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a polybasic acid and (meth)acrylic acid; and (meth)acrylates obtained by reacting a di- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a phenol and (meth)acrylic acid.

[0053] The number of functional groups in the polyfunctional ionizing radiation-curable oligomer (c) is preferably 4 or more and 8 or less, more preferably 5 or more and 7 or less, and even more preferably 6, in order to suppress cure shrinkage while maintaining pencil hardness. The weight average molecular weight of the polyfunctional ionizing radiation-curable oligomer (c) is preferably 1000 to 5000, more preferably 1100 to 3500, and even more preferably 1200 to 2000, in order to suppress cure shrinkage while maintaining pencil hardness. In this specification, the weight average molecular weight is an average molecular weight measured by GPC analysis and converted into standard polystyrene.

[0054] When the ionizing radiation curable compound is an ultraviolet ray curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. The photopolymerization initiator may be one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzil dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones, and the like. The photopolymerization accelerator can reduce polymerization inhibition caused by air during curing and increase the curing rate, and examples thereof include one or more selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc.

[0055] "The First Particle" To facilitate good antiglare properties, the resin layer preferably contains first particles having an average particle size of 0.5 μm or more. To facilitate even better antiglare properties, it is more preferable that the second resin layer contains the first particles.

[0056] To facilitate better antiglare properties, it is preferable that 70% or more of the first particles are present on the second resin layer side, preferably 80% or more, and more preferably 90% or more, based on the number of the first particles.

[0057] The positions of the first particles in the thickness direction of the resin layer can be determined, for example, from a cross-sectional photograph of the optical laminate taken with a scanning transmission electron microscope (STEM). The above-mentioned number-based ratio can be calculated from the cross-sectional photograph. To improve the reliability of the numerical value, it is preferable to take multiple cross-sectional photographs and calculate the above-mentioned number-based ratio after setting the total number of first particles to 50 or more. For first particles present in both the first and second resin layers, the number of first particles is allocated to each layer according to the area ratio of each layer. For example, for first particles present in the first resin layer at an area ratio of 40% and the second resin layer at an area ratio of 60%, 0.4 particles are allocated to the first resin layer and 0.6 particles are allocated to the second resin layer. The acceleration voltage of the STEM is preferably 10 kV or more and 30 kV or less, and the magnification of the STEM is preferably 1000 times or more and 7000 times or less.

[0058] Examples of the first particles include organic particles formed from one or more resins such as polymethyl methacrylate, polyacrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluorine-based resin, and polyester-based resin; and inorganic particles formed from one or more inorganic materials such as silica, alumina, zirconia, and titania. Among these, organic particles are preferred because they have excellent dispersion stability and a relatively small specific gravity, making it easy to position the first particles in the second resin layer.

[0059] The content of the first particles is preferably at least 0.5 parts by mass, more preferably at least 1.0 parts by mass, and even more preferably at least 1.3 parts by mass, relative to 100 parts by mass of the resin component of the coating liquid for the resin layer, and is preferably at most 10.0 parts by mass, more preferably at most 5.0 parts by mass, and even more preferably at most 3.0 parts by mass. By setting the content of the first particles to 0.5 parts by mass or more, it is possible to easily improve antiglare properties, and by setting the content of the first particles to 10.0 parts by mass or less, it is possible to easily suppress a decrease in flex resistance.

[0060] The average particle size of the first particles is preferably 0.8 μm or more, and more preferably 1.0 μm or more, in order to facilitate good antiglare properties. The average particle size of the first particles is preferably 3.0 μm or less, more preferably 2.7 μm or less, and even more preferably 2.5 μm or less, in order to easily suppress a decrease in flex resistance.

[0061] The average particle size of the first particles can be calculated, for example, by the following steps (B1) to (B3). (B1) A transmission observation image of the optical laminate is taken using an optical microscope, preferably at a magnification of 500 times or more and 2000 times or less. (B2) Randomly extract 10 particles from the observed image and calculate the particle diameter of each particle. The particle diameter is measured as the distance between two parallel lines that maximizes the distance between the two lines when the cross section of the particle is sandwiched between the two lines. (B3) The same procedure is carried out five times on a separate observation image of the same sample, and the value obtained from the number average of the particle diameters of a total of 50 particles is regarded as the average particle diameter of the particles. However, when the first particles cannot be optically observed, the average particle size of the first particles is calculated according to the following (B4) to (B6). (B4) A section is prepared from the optical laminate using a microtome, the section being a cross section passing through the center of the first particle. The thickness of the section is preferably 60 nm to 100 nm. A plurality of sections are prepared consecutively for each first particle, and the section at which the particle diameter calculated in step (B5) is maximum can be selected as the section being a cross section passing through the center of the first particle. (B5) The obtained slice is observed under a scanning transmission electron microscope (STEM) to calculate the particle size. The method for calculating the particle size is the same as in (B2). The magnification is preferably 5,000 times or more and 20,000 times or less. (B6) The steps (B4) to (B5) are carried out on 20 particles, and the value obtained from the number average of the particle diameters of the 20 particles is set as the average particle diameter of the first particles.

[0062] With respect to D1, which indicates the average particle diameter of the first particles, and t2, which indicates the average thickness of the second resin layer, t2-D1 is preferably -0.5 μm or more and 2.0 μm or less. When t2-D1 is -0.5 μm or more, the first particles can easily impart an uneven shape to the surface of the optical laminate, making it easier to improve antiglare properties. t2-D1 is more preferably 0 μm or more, and even more preferably 0.1 μm or more. When t2-D1 is 2.0 μm or less, the first particles are less likely to protrude from the surface of the second resin layer, which makes it easier to improve scratch resistance. t2-D1 is more preferably 1.5 μm or less, and even more preferably 0.8 μm or less.

[0063] 《Inorganic fine particles》 The resin layer may contain inorganic fine particles. By including inorganic fine particles with a relatively high specific gravity in the resin layer, the first particles are less likely to sink below the resin layer, making it easier to position the first particles in the second resin layer. In addition, the inorganic fine particles can improve the dispersibility of the first particles and make it easier to suppress a decrease in flex resistance. In this specification, inorganic fine particles refer to inorganic particles having an average primary particle diameter of 200 nm or less. The average particle size of the inorganic fine particles is preferably 1 nm or more and 200 nm or less, more preferably 2 nm or more and 100 nm or less, and even more preferably 5 nm or more and 50 nm or less.

[0064] The average particle size of the inorganic fine particles can be calculated by the following steps (C1) to (C3). (C1) The cross section of the optical laminate is imaged by a TEM or STEM. The acceleration voltage of the TEM or STEM is preferably 10 kV or more and 30 kV or less, and the magnification is preferably 50,000 times or more and 300,000 times or less. (C2) Randomly extract 10 inorganic microparticles from the observed image, and calculate the particle diameter of each inorganic microparticle. The particle diameter is measured as the distance between two parallel lines that maximizes the distance between the two lines when the cross section of the inorganic microparticle is sandwiched between the two lines. (C3) The same procedure is repeated five times on separate observation images of the same sample, and the value obtained from the number average of the particle diameters of a total of 50 particles is regarded as the average particle diameter of the inorganic fine particles.

[0065] Examples of inorganic fine particles include fine particles made of silica, alumina, zirconia, titania, etc. Among these, silica is preferred because it is easy to suppress the generation of internal haze.

[0066] The content of inorganic fine particles is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, relative to 100 parts by mass of the resin component of the coating liquid for the resin layer, and the upper limit is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.0 parts by mass or less. By setting the content of inorganic fine particles to 0.1 parts by mass or more, the first particles can be easily positioned in the second resin layer, and by setting the content of inorganic fine particles to 5.0 parts by mass or less, the first particles can be prevented from excessively floating above the resin layer, which makes it easier to prevent a decrease in flex resistance.

[0067] Additives The coating liquid for the resin layer may contain additives such as a leveling agent, a refractive index adjuster, an antistatic agent, an antifouling agent, an ultraviolet absorber, a light stabilizer, an antioxidant, a viscosity adjuster, and a thermal polymerization initiator, as necessary.

[0068] "solvent" The resin layer coating liquid preferably contains a solvent. It is preferable to select a solvent that can dissolve the substrate. The more easily a solvent that dissolves the substrate is used as the solvent, the more likely it is that the values ​​of θa1 and Pa1 will be large. However, if the substrate is dissolved too much, the strength of the substrate will decrease, so it is preferable to select an appropriate solvent depending on the type of substrate. It is also preferable to select a solvent taking into consideration not only the solubility of the substrate but also the evaporation rate specific to the solvent. The evaporation rate of the solvent can also be controlled by the drying conditions. For example, increasing the drying temperature increases the evaporation rate of the solvent. In addition, increasing the drying air speed increases the evaporation rate of the solvent. If the solvent dries slowly, the base material dissolves more rapidly, which tends to increase θa1 and Pa1. If the solvent dries slowly and the drying temperature is high, the resin components move more vigorously between the first and second resin layers, which tends to increase θa2 and Pa2. From the above, it is preferable to select a solvent taking into consideration the solubility of the base material, evaporation rate, and drying conditions.

[0069] Examples of the solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as dioxane and tetrahydrofuran; aliphatic hydrocarbons such as hexane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated carbons such as dichloromethane and dichloroethane; esters such as methyl acetate, ethyl acetate, and butyl acetate; alcohols such as isopropanol, butanol, and cyclohexanol; cellosolves such as methyl cellosolve and ethyl cellosolve; glycol ethers such as propylene glycol monomethyl ether acetate; cellosolve acetates; sulfoxides such as dimethyl sulfoxide; and amides such as dimethylformamide and dimethylacetamide. The solvent may be used alone or in combination.

[0070] Acrylic resin substrates are easily dissolved in solvents, and therefore, when an acrylic resin substrate is used as the substrate, it is preferable that the substrate contains a solvent that has an inherently fast evaporation rate. In this specification, a solvent with a fast evaporation rate means a solvent with an evaporation rate of 100 or more, where the evaporation rate of butyl acetate is taken as 100. In addition, in this specification, a solvent with a slow evaporation rate means a solvent with an evaporation rate of less than 100, where the evaporation rate of butyl acetate is taken as 100.

[0071] The evaporation rate of the solvent having a high evaporation rate is more preferably 120 or more and 450 or less, and even more preferably 140 or more and 400 or less. Examples of solvents with a fast evaporation rate include isopropyl alcohol (evaporation rate 150), methyl isobutyl ketone (evaporation rate 160), toluene (evaporation rate 200), and methyl ethyl ketone (evaporation rate 370). The solvent with a high evaporation rate preferably accounts for 75% by mass or more and 85% by mass or less of the total amount of solvent.

[0072] Furthermore, to facilitate the formation of a sea-island structure in the first resin layer and the second resin layer, it is preferable that the solvent contains a solvent that has an inherently slow evaporation rate, high polarity, and a large molecular weight. A solvent having the above-mentioned properties increases the viscosity of the coating liquid, making the coating liquid more likely to gel. Therefore, a solvent having the above-mentioned properties can easily reduce the compatibility of the coating liquid, making it easier to form a sea-island structure. Examples of solvents having the above-mentioned properties include cyclohexanone and diacetone alcohol. The solvent having a slow evaporation rate, high polarity and large molecular weight preferably accounts for 15% by mass or more and 25% by mass or less of the total amount of solvent.

[0073] Drying conditions When forming a resin layer from the resin layer coating liquid, it is preferable to control the drying conditions. Furthermore, in the optical laminate of the present disclosure, it is preferable to dry the resin layer coating liquid in two stages. Specifically, it is preferable to reduce the drying air velocity in the first drying stage and increase the drying air velocity in the second drying stage. During the first drying stage, a first resin layer can be formed from a region containing the resin component eluted from the substrate as the main component and a small amount of the resin component of the resin layer coating liquid, and a second resin layer can be formed from a region containing a small amount of the resin component eluted from the substrate and a large amount of the resin component of the resin layer coating liquid. Furthermore, by increasing the drying temperature in the first stage, the resin component can be easily migrated, which can facilitate the formation of a sea-island structure. Furthermore, by carrying out the second stage drying, it is possible to prevent the base material from being dissolved excessively, which makes it easier to prevent θa1 and Pa1 from becoming too large.

[0074] Furthermore, it is preferable to control the drying time in the first and second drying stages. A longer drying time for drying the resin layer coating liquid means a longer time until the resin component of the resin layer coating liquid is irradiated with ionizing radiation. In other words, a longer drying time for drying the resin layer coating liquid means that the resin component of the resin layer coating liquid remains uncured and fluid for a longer period of time. Therefore, if the drying time for drying the resin layer coating liquid is longer, the movement of the resin component between the first and second resin layers becomes more intense, which tends to increase θa2 and Pa2, making it difficult to satisfy Conditions 1 and 2.

[0075] The drying conditions can be controlled by the drying temperature and the air speed inside the dryer. The preferred ranges of the drying temperature and air speed cannot be generalized because they differ depending on the composition of the coating liquid for the resin layer, but the following conditions are preferred. <First stage drying> The drying temperature is preferably 75° C. or higher and 95° C. or lower, the drying air speed is preferably 1 m / s or higher and 10 m / s or lower, and the drying time is preferably 20 seconds or higher and 40 seconds or lower. <Second stage drying> The drying temperature is preferably 75°C or higher and 95°C or lower, the drying wind speed is preferably 15 m / s or higher and 30 m / s or lower, and the drying time is preferably 20 seconds or longer and 40 seconds or shorter.

[0076] In order to dissolve a part of the base material with the coating liquid for the resin layer and to easily mix the components eluted from the base material and the coating liquid for the resin layer, it is preferable to perform the irradiation of ionizing radiation after drying the coating liquid.

[0077] <Other layer> The optical laminate may have a layer other than the base material and the resin layer. Examples of the other layer include an antireflection layer, an antifouling layer, and an antistatic layer.

[0078] <Condition 1, Condition 2> The optical laminate of the present disclosure needs to satisfy the following Condition 1 or Condition 2. The optical laminate of the present disclosure only needs to satisfy at least one of Condition 1 and Condition 2, but it is preferable to satisfy both. <Condition 1> There is a relationship of θa2 < θa1 between θa1 indicating the average inclination angle of the surface of the base material on the resin layer side and θa2 indicating the average inclination angle of the surface of the first resin layer on the second resin layer side. <Condition 2> There is a relationship of Pa2 < Pa1 between Pa1 indicating the arithmetic mean height of the surface of the base material on the resin layer side and Pa2 indicating the arithmetic mean height of the surface of the first resin layer on the second resin layer side.

[0079] -Condition 1- When the relationship of θa2 < θa1 is not satisfied, it is difficult to improve the initial adhesion due to the small θa1, or it is difficult to suppress the change in the transmission image sharpness after the light resistance test due to the large θa2. The reason why the transparency image sharpness changes before and after the light resistance test is considered to be that the refractive index difference at the interface between the first resin layer and the second resin layer changes before and after the light resistance test. In the optical laminate of the present disclosure, there is not only an interface between the first resin layer and the second resin layer, but also an interface between the base material and the first resin layer. The base material (especially an acrylic resin base material) is relatively difficult to be modified by the light resistance test. On the other hand, the resin component of the coating liquid for the resin layer is relatively easy to be modified by the light resistance test. Therefore, the second resin layer with a small content of the resin component of the base material is likely to have a refractive index change before and after the light resistance test. On the other hand, the base material and the first resin layer containing a large amount of the resin component of the base material are less likely to have a refractive index change before and after the light resistance test. Therefore, when θa2 is large and the relationship θa2 < θa1 is not satisfied, it is considered difficult to suppress the change in the transparency image sharpness after the light resistance test.

[0080] -Condition 2- When the relationship Pa2 < Pa1 is not satisfied, due to Pa1 being small, it is difficult to achieve good initial adhesion, or due to Pa2 being large, it is difficult to suppress the change in the transparency image sharpness after the light resistance test. The reason why it is difficult to suppress the change in the transparency image sharpness after the light resistance test when the relationship Pa2 < Pa1 is not satisfied due to Pa2 being large is considered to be the same as the reason in Condition 1.

[0081] For θa1, in order to easily achieve good initial adhesion, it is preferably 5.0 degrees or more, more preferably 8.0 degrees or more, and still more preferably 10.0 degrees or more. For θa1, in order to easily achieve good pencil hardness, it is preferably 20.0 degrees or less, more preferably 18.0 degrees or less, and still more preferably 17.0 degrees or less.

[0082] For θa2, in order to easily suppress the change in the transparency image sharpness after the light resistance test, it is preferably 10.0 degrees or less, more preferably 8.0 degrees or less, still more preferably 6.0 degrees or less, and even more preferably 4.0 degrees or less. For θa2, in order to easily achieve good adhesion, it is preferably more than 0 degrees, more preferably 1.0 degrees or more, and still more preferably 2.0 degrees or more.

[0083] In order to facilitate good initial adhesion, Pa1 is preferably 0.05 μm or more, more preferably 0.07 μm or more, and even more preferably 0.10 μm or more.In order to facilitate good pencil hardness, Pa1 is preferably 0.25 μm or less, more preferably 0.23 μm or less, and even more preferably 0.20 μm or less.

[0084] Pa2 is preferably 0.15 μm or less, more preferably 0.13 μm or less, even more preferably 0.10 μm or less, and even more preferably 0.06 μm or less, in order to easily suppress changes in transmitted image clarity after a lightfastness test. In order to facilitate good adhesion, Pa2 is preferably 0.02 μm or more, more preferably 0.04 μm or more, and even more preferably 0.05 μm or more.

[0085] θa1 and θa2, as well as Pa1 and Pa2, can be measured, for example, as follows. (1) A cross-sectional photograph of the optical laminate is taken using a scanning transmission electron microscope (STEM). The acceleration voltage of the STEM is preferably 10 kV to 30 kV, and the magnification of the STEM is preferably 5,000 times to 10,000 times. (2) From the image of the cross-sectional photograph, the ridge line of the interface between the substrate and the resin layer and the ridge line of the interface between the first resin layer and the second resin layer are obtained, and height data is acquired. Specifically, this is done as follows. The interface between the substrate and the resin layer corresponds to the surface of the substrate facing the resin layer. The interface between the first resin layer and the second resin layer corresponds to the surface of the first resin layer facing the second resin layer. (a) The captured images were displayed using ImageJ (version 1.52a), an open-source, public domain image processing software. (b) The length per pixel is calculated from the scale displayed in the image. (c) Select “FreeHand Selections” and create an ROI that includes the interface. Adjust the Brightness to create a clear color difference at the interface. (d) Process-Smooth twice. (e) Set Image-Type to 8bit. (f) Select “Straight” to draw a line along the interface. (g) Install and run ABSnake, an ImageJ plugin. Set “Gradient threshold” to 10 and Draw color to Red. Leave other settings as default. (h) Visually check that the interface can be traced in red. If it is not, start again from (f). (i) Run Image-Adjust-Color Threshold. Set the threshold to separate Red from everything else. Specifically, set Color space to RGB, check "Pass" for "Red," "Green," and "Blue," set the upper and lower limits of the Red range to the maximum value (255), and set the upper and lower limits of the "Green" and "Blue" ranges to the minimum value (0). (j) Execute Process-Binary-Make Binary to binarize the trace line portion of the interface and the portion other than the trace line. (k) Save the binarized data as “Text Image” using File-Save As. (l) From the binarized data, the interface is converted into a sequence of height data points. (3) From the sequence of height data points, calculate the average slope angle and arithmetic mean height using the following procedure. (m) The center line of the height data is found using quadratic regression with the least squares method, and by subtracting it from the height data, the center line is converted to 0, with the upward direction being positive and the downward direction being negative. The direction of the center line is the x-axis, and the direction perpendicular to it (height direction) is the y-axis. (n) Using the length per pixel calculated in (b), convert the height data into length. (o) A Gaussian low-pass filter with a cutoff wavelength of 0.5 μm is applied. (p)tan -1 ((y i+1 -y i-1 ) / 2Δx)[y iis the height at the i-th point in the height data point sequence, and Δx is the distance in the x-axis direction between adjacent points], and then θa1 and θa2 are calculated by calculating the arithmetic mean of the absolute values ​​of the inclination angles at each point. (q) The arithmetic mean heights Pa1 and Pa2 are calculated by calculating the arithmetic mean of the absolute values ​​of the heights at each point.

[0086] In this specification, θa1 and θa2, and Pa1 and Pa2 mean the average values ​​of the measurements of 20 samples. In order to set θa1 and θa2, and Pa1 and Pa2 within the above ranges, as described above, it is important to dissolve a portion of the substrate in the coating liquid for the resin layer, to appropriately prepare the composition of the coating liquid for the resin layer, and to set the drying conditions of the coating liquid for the resin layer within appropriate ranges.

[0087] <Optical properties, surface shape> The optical laminate preferably has a total light transmittance according to JIS K7361-1:1997 of 70% or more, more preferably 80% or more, and even more preferably 85% or more. When measuring the total light transmittance and the haze described later, the light incident surface is the substrate side.

[0088] The optical laminate preferably has a haze of 0.5% or more, more preferably 1.0% or more, and even more preferably 1.5% or more according to JIS K7136:2000. By making the haze 0.5% or more, it is possible to easily improve antiglare properties. Furthermore, in order to easily prevent a decrease in image resolution, the optical laminate preferably has a haze of 20% or less, more preferably 10% or less, and even more preferably 5% or less.

[0089] In order to facilitate good antiglare properties, the optical laminate preferably has an arithmetic mean roughness Ra of 0.03 μm or more, more preferably 0.05 μm or more, on the surface on the resin layer side, as measured by JIS B0601:2001. Furthermore, in order to facilitate suppressing a decrease in image resolution, the optical laminate preferably has an Ra of 0.12 μm or less, more preferably 0.10 μm or less, on the surface on the resin layer side. Ra refers to the value at a cutoff value of 0.8 mm.

[0090] <Size, shape, etc.> The optical laminate may be in the form of a sheet cut to a predetermined size, or in the form of a roll obtained by winding a long sheet into a roll. The size of the sheet is not particularly limited, but the maximum diameter is approximately 2 inches to 500 inches. The "maximum diameter" refers to the maximum length when any two points on the optical laminate are connected. For example, if the optical laminate is rectangular, the diagonal of the rectangle is the maximum diameter. If the optical laminate is circular, the diameter of the circle is the maximum diameter. The width and length of the roll are not particularly limited, but generally, the width is about 500 mm or more and 3000 mm or less, and the length is about 500 m or more and 5000 m or less. The optical laminate in the form of a roll can be cut into sheets according to the size of an image display device or the like. When cutting, it is preferable to remove the end of the roll, which has unstable physical properties. The shape of the sheet is not particularly limited, and may be, for example, a polygon such as a triangle, a rectangle, or a pentagon, or may be a circle or a random, indeterminate shape. More specifically, when the optical laminate is rectangular, the aspect ratio is not particularly limited as long as it does not cause any problems as a display screen. Examples include width:height = 1:1, 4:3, 16:10, 16:9, 2:1, 5:4, 11:8, etc.

[0091] [Polarizing plate] The polarizing plate of the present disclosure has a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, and at least one of the first transparent protective plate and the second transparent protective plate is the optical laminate of the present disclosure described above.

[0092] A polarizing plate is used to impart anti-reflection properties by combining a polarizing plate with a λ / 4 retardation plate, for example. In this case, the λ / 4 retardation plate is disposed on the display element of the image display device, and the polarizing plate is disposed closer to the viewer than the λ / 4 retardation plate. When a polarizing plate is used for a liquid crystal display device, the polarizing plate is used to provide a liquid crystal shutter function. In this case, the liquid crystal display device is arranged in the order of a lower polarizing plate, a liquid crystal display element, and an upper polarizing plate, and the absorption axis of the polarizer of the lower polarizing plate and the absorption axis of the polarizer of the upper polarizing plate are arranged perpendicular to each other. In this configuration, it is preferable to use the polarizing plate of the present disclosure as the upper polarizing plate.

[0093] <Transparent protection plate> In the polarizing plate of the present disclosure, at least one of the first transparent protective plate and the second transparent protective plate is the optical laminate of the present disclosure described above. In a preferred embodiment, of the first transparent protective plate and the second transparent protective plate, the transparent protective plate on the light exit side is the optical laminate of the present disclosure described above. The optical laminate is preferably arranged so that the surface of the optical laminate facing the substrate faces the polarizer.

[0094] When one of the first transparent protective plate and the second transparent protective plate is the optical laminate of the present disclosure, the other transparent protective plate is not particularly limited, but is preferably an optically isotropic transparent protective plate. In this specification, optical isotropy refers to an in-plane retardation of 20 nm or less, preferably 10 nm or less, and more preferably 5 nm or less. Acrylic films and triacetyl cellulose (TAC) films are easily imparted with optical isotropy.

[0095] <Polarizer> Examples of polarizers include sheet-type polarizers such as polyvinyl alcohol films, polyvinyl formal films, polyvinyl acetal films, and saponified ethylene-vinyl acetate copolymer films dyed with iodine or the like, and stretched, wire-grid polarizers made of a large number of parallel-arranged metal wires, coated polarizers coated with lyotropic liquid crystals or dichroic guest-host materials, and multilayer thin-film polarizers. These polarizers may be reflective polarizers that have the function of reflecting polarized light components that are not transmitted.

[0096] <Size, shape, etc.> Examples of the size and shape of the polarizing plate of the present disclosure include the above-described embodiments of the size and shape of the optical laminate of the present disclosure.

[0097] [Image display device] The image display device of the present disclosure has the above-described optical laminate of the present disclosure on a display element.

[0098] Fig. 3 is a cross-sectional view showing an embodiment of an image display device 500 of the present disclosure. The image display device 500 of Fig. 3 has the optical laminate 100 of the present disclosure on a display element 200. In the image display device, the optical laminate is preferably arranged so that the substrate side faces the display element side.

[0099] Examples of the display element include a liquid crystal display element, an EL display element (organic EL display element, inorganic EL display element), a plasma display element, a display element using QD (Quantum Dot), an LED display element such as a mini LED or a micro LED display element, etc. These display elements may have a touch panel function inside the display element. The liquid crystal display mode of the liquid crystal display element includes the IPS mode, VA mode, multi-domain mode, OCB mode, STN mode, TSTN mode, etc. When the display element is a liquid crystal display element, a backlight is required. The backlight is disposed on the side opposite to the side where the optical laminate of the liquid crystal display element is disposed.

[0100] The image display device according to the present disclosure may be an image display device with a touch panel, which has a touch panel between a display element and the optical laminate. In this case, it is preferable that the optical laminate is disposed on the outermost surface of the image display device with a touch panel, and that the substrate side of the optical laminate is disposed so as to face the display element side.

[0101] The size of the image display device is not particularly limited, but it is preferable that the maximum diameter of the effective display area is 2 inches or more and 500 inches or less. The effective display area of ​​an image display device is the area in which an image can be displayed. For example, if the image display device has a housing that surrounds the display element, the area inside the housing is the effective image area. The maximum diameter of the effective image area is the maximum distance between any two points within the effective image area. For example, if the effective image area is rectangular, the maximum diameter is the diagonal of the rectangle. If the effective image area is circular, the maximum diameter is the diameter of the circle. [Example]

[0102] Next, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to these examples. Note that "parts" and "%" are based on mass unless otherwise specified.

[0103] 1. Measurement and Evaluation The optical laminates of the examples and comparative examples were measured and evaluated as follows. The atmosphere during each measurement and evaluation was a temperature of 23±5°C and a relative humidity of 40% to 65%. Before each measurement and evaluation, the target sample was exposed to the atmosphere for 30 minutes or more before measurement and evaluation. The results are shown in Table 2.

[0104] 1-1. Presence or absence of region α1 and region β1, and the proportion of region α1 present in the second region Samples were prepared in accordance with the description in the specification, exposing the cross sections of the optical laminates of the examples and comparative examples. The presence or absence of regions α1 and β1 was confirmed from cross-sectional photographs of the samples taken with a scanning transmission electron microscope. Furthermore, the area ratios of regions α1 and α2, and regions β1 and β2 were calculated. The presence of an independent region α1 in the first resin layer 21, the fact that the resin contained in region α1 is different from the resin contained in region α2, the presence of an independent region β1 in the second resin layer 22, and the fact that the resin contained in region β1 is different from the resin contained in region β2 can be determined from the difference in brightness in the photographs. Furthermore, the proportion of the regions α present in the second region based on the number was calculated. In calculating the proportion, a plurality of cross-sectional photographs were taken until the total number of regions α exceeded 50.

[0105] 1-2. θa1 and θa2, and Pa1 and Pa2 Samples were prepared in accordance with the description in the present specification, each of which had an exposed cross section of the optical laminate of each of the examples and comparative examples. θa1 and θa2, as well as Pa1 and Pa2, were calculated from cross-sectional photographs of the samples taken with a scanning transmission electron microscope in accordance with the description in the present specification.

[0106] 1-3. Average thickness of the first resin layer and the second resin layer Samples were prepared according to the description in the specification, with the cross sections of the optical laminates of the examples and comparative examples exposed. Twenty randomly selected locations were selected from the cross-sectional photographs of the samples taken with a scanning transmission electron microscope, and the average thicknesses t1 of the first resin layer and t2 of the second resin layer were calculated from the average values.

[0107] 1-4. Total light transmittance (Tt) and haze (Hz) The optical laminates of the examples and comparative examples were cut into 10 cm squares. The cutting locations were selected randomly after visually checking for any abnormalities such as dust or scratches. Using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory), the total light transmittance of each sample according to JIS K7361-1:1997 and the haze according to JIS K7136:2000 were measured. To allow the light source to stabilize, the device was powered on and then left on for at least 15 minutes, and calibration was performed without placing anything in the entrance opening (where the measurement sample was placed), after which the measurement sample was placed in the entrance opening and measured. The light incident surface was set on the substrate side.

[0108] 1-5. Adhesion The adhesion of the optical laminates of the Examples and Comparative Examples was evaluated by the following method. Furthermore, the adhesion of the optical laminates of the Examples and Comparative Examples was evaluated after the following light resistance test was carried out. The evaluation sample was cross-cut into a grid of 100 squares, 10 vertically and 10 horizontally. The cut intervals were 1 mm. When cutting, the cutter blade was inserted from the second resin layer side and cross-cut so that the cutter blade reached the top of the substrate. An adhesive tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") was attached to the surface of the cross-cut sample, and a peel test was performed in accordance with the cross-cut method specified in JIS K 5600-5-6: 1999. From the results of the peel test, the adhesion was evaluated according to the following evaluation criteria. <Evaluation criteria> A: Less than 5% of the cross-cut area is peeled off in the grid pattern. B: Cross-cut area where peeling can be confirmed in the grid pattern is 5% or more but less than 15%. C: The cross-cut area where peeling can be confirmed in the grid pattern is 15% or more.

[0109] <Light resistance test> UV carbon arc lamp light resistance and weather resistance tester conforming to JIS B7751 (product name "FAL-AU·B" manufactured by Suga Test Instruments Co., Ltd., light source: UV carbon arc lamp, irradiance: 500 W / m 2 The optical laminates of the examples and comparative examples were placed in a black panel (black panel temperature: 63° C.) with the resin layer side facing the light source, and a test was carried out for 200 hours.

[0110] 1-6.Transmitted image clarity (JIS K7374:2007 transmitted image clarity) The transmitted image clarity of the optical laminates of the examples and comparative examples was measured. The light incident surface was the substrate side. The measuring device used was an image clarity measuring instrument (product name: ICM-1T) manufactured by Suga Test Instruments Co., Ltd. The total transmitted image clarity for the four optical comb widths is shown in Table 2 (unit: "%)." The four comb widths used were 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. Furthermore, the optical laminates of the examples and comparative examples after the light resistance test were measured for transmitted image clarity in the same manner as above. The total transmitted image clarity for the widths of the four optical combs is shown in Table 2 (unit: "%)." The difference in transmitted image clarity before and after the lightfastness test is shown in Table 2 (unit: "%). A difference of 10.0% or less is the acceptable level, and even within the acceptable level, a difference of 5.0% or less is more preferable.

[0111] 1-7. Anti-glare properties A black plate (Kuraray Co., Ltd., product name "Comoglass DFA2CG 502K (black) series," total light transmittance 0%, thickness 2 mm, refractive index 1.49) was attached to the substrate side of the optical laminate of each of the examples and comparative examples via a 25 μm-thick transparent adhesive layer (Panac Corporation, product name "Panaclean PD-S1," refractive index 1.49) to prepare samples (sample size: 20 cm length x 30 cm width). The samples were visually evaluated by 20 subjects in a bright room environment (illuminance on the first main surface of the sample was 500 lux to 1000 lux; lighting: Hf32 type straight-tube three-wavelength daylight fluorescent lamp) from a linear distance of 50 cm above the center of the first main surface to determine whether the antiglare properties were sufficient to prevent the observer from being bothered by their own reflection, according to the following criteria. The lighting position during evaluation was 2 m vertically above the horizontal table. The subjects were healthy individuals in their 30s with visual acuity of 0.7 or better. A: More than 14 people answered "good" B: 7 to 13 people answered "good" C: 6 or fewer people answered good

[0112] 2. Preparation of optical laminates [Example 1] (Base material manufacturing) A copolymer of methyl methacrylate and methyl acrylate was kneaded at 260°C using a twin-screw extruder to obtain a pellet-shaped composition (glass transition temperature: 134°C). The obtained pellet-shaped composition was melt-extruded using a T-die (T-die temperature: 260°C) and discharged onto a cooling roll at 130°C. Next, it was sequentially biaxially stretched in the machine direction and transverse direction at a stretching ratio of 1.5 times at a stretching temperature of 145°C. After cooling, an acrylic resin substrate with a thickness of 40 μm was obtained. (Formation of resin layer) The resin layer coating solution of Example 1 in Table 1 was applied to the acrylic resin substrate in an amount of 6.0 g / m by a Mayer bar coating method. 2 After coating in a coating amount of 1000 ppm, the coating solution was dried for 30 seconds with hot air at a temperature of 90°C at a wind speed of 5 m / s to perform the first stage of drying. The coating solution was then dried for 30 seconds with hot air at a temperature of 90°C at a wind speed of 20 m / s to perform the second stage of drying. Next, the coating solution was dried in a nitrogen atmosphere with an oxygen concentration of 200 ppm or less, with an integrated light intensity of 100 mJ / cm. 2 The ionizing radiation curable resin composition of the resin layer coating liquid was cured by irradiating with ultraviolet light so that the coating liquid became a first resin layer and a second resin layer, thereby obtaining the optical laminate of Example 1. In this specification, the coating amount means the coating amount after drying.

[0113] [Examples 2 to 4], [Comparative Examples 1 to 3] The optical laminates of Examples 2 to 4 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1, except that the composition of the coating liquid for the resin layer, the amount of coating liquid for the resin layer, and the drying conditions for the coating liquid for the resin layer were changed to the compositions, etc. listed in Table 1.

[0114] [Table 1]

[0115] In Table 1, the hexafunctional urethane acrylate oligomer represents a urethane acrylate oligomer manufactured by Mitsubishi Chemical Corporation (product name: Shikoh UV-7600B, weight average molecular weight: 1400), the difunctional acrylate monomer represents tetraethylene glycol diacrylate, the trifunctional acrylate monomer represents pentaerythritol triacrylate, the monofunctional acrylate monomer represents 4-hydroxybutyl acrylate, and the photopolymerization initiator represents the product name "Omnirad 184" manufactured by IGM Resins BV.

[0116] [Table 2]

[0117] From the results in Table 2, it can be confirmed that the optical laminates of the examples can suppress the decrease in adhesion and the change in transmitted image clarity after the light resistance test. On the other hand, in the optical laminate of Comparative Example 1, the first resin layer does not have region α1. Therefore, the optical laminate of Comparative Example 1 was unable to improve the affinity between the first resin layer and the second resin layer, resulting in reduced adhesion after a light resistance test. In Comparative Example 1, it is believed that the coating liquid for the resin layer contains a monofunctional monomer, which provides good compatibility, making it difficult to form a sea-island structure, and therefore preventing the formation of region α1. The optical laminate of Comparative Example 2 had large θa1 and Pa1, and did not satisfy either Condition 1 or Condition 2. For this reason, the optical laminate of Comparative Example 2 exhibited significant fluctuations in transmitted image clarity after the light resistance test. The reason that Comparative Example 2 did not satisfy Conditions 1 and 2 is thought to be that the long drying time caused the resin component to move violently between the first resin layer and the second resin layer, resulting in large θa2 and Pa2. The optical laminate of Comparative Example 3 has small θa1 and Pa1 and does not satisfy either condition 1 or condition 2. Therefore, the optical laminate of Comparative Example 3 was unable to achieve good adhesion after the light resistance test. The optical laminate of Comparative Example 3 also did not have sufficient adhesion before the light resistance test. The reason that Comparative Example 3 does not satisfy conditions 1 and 2 is thought to be because the coating liquid for the resin layer does not contain a bifunctional monomer. [Explanation of symbols]

[0118] 10: Base material 20: Resin layer 21: First resin layer 22: Second resin layer 100: Optical laminate 200: Display element 500: Image display device

Claims

1. An optical laminate having a resin layer on a substrate, the resin layer has, from the substrate side, a first resin layer and a second resin layer, the first resin layer is composed of a region α1 and a region α2, the region α1 is dispersed in the region α2 so as to be independent of each other, and a resin contained in the region α1 is different from a resin contained in the region α2, the second resin layer is composed of a region β1 and a region β2, the region β1 is dispersed in the region β2 so as to be independent of each other, and a resin contained in the region β1 is different from a resin contained in the region β2, An optical laminate satisfying the following condition 1 or condition 2. <Condition 1> θa1, which indicates the average inclination angle of the surface of the base material on the resin layer side, and θa2, which indicates the average inclination angle of the surface of the first resin layer on the second resin layer side, have a relationship of θa2<θa1. <Condition 2> Pa1, which indicates the arithmetic mean height of the surface of the base material on the resin layer side, and Pa2, which indicates the arithmetic mean height of the surface of the first resin layer on the second resin layer side, satisfy the relationship Pa2<Pa1.

2. The optical laminate according to claim 1, wherein the angle θa1 is 5.0 degrees or more and 20.0 degrees or less.

3. The optical laminate according to claim 1 or 2, wherein the θa2 is 10.0 degrees or less.

4. The optical laminate according to claim 1, wherein the Pa1 is 0.05 μm or more and 0.25 μm or less.

5. The optical laminate according to claim 1 or 2, wherein Pa2 is 0.15 μm or less.

6. The optical laminate according to any one of claims 1 to 5, wherein when the region on the substrate side from the center of the thickness direction of the first resin layer is defined as a first region, and the region on the second resin layer side from the center of the thickness direction of the first resin layer is defined as a second region, 70% or more of the region α1 is present in the second region.

7. The resin contained in the region α1 and the resin contained in the region β2 are the same, and the resin contained in the region α2 and the resin contained in the region β1 are the same. An optical laminate according to any one of claims 1 to 6.

8. The optical laminate according to any one of claims 1 to 7, wherein the resin layer contains first particles having an average particle size of 0.5 µm or more.

9. The optical laminate according to claim 8 , wherein the second resin layer contains the first particles.

10. The optical laminate according to claim 8 or 9, wherein the first particles are organic particles.

11. The optical laminate according to any one of claims 1 to 10, wherein the substrate is an acrylic resin substrate.

12. The optical laminate according to any one of claims 1 to 11, wherein the resin layer comprises a cured product of a curable resin composition.

13. A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical laminate according to any one of claims 1 to 12.

14. An image display device having the optical laminate according to any one of claims 1 to 12 on a display element.

Images