Optical laminate and image display device using the optical laminate

Abstract

To provide an optical laminate that includes a liquid crystal alignment cured layer and can suppress specific display unevenness when applied to an image display device. 【Solution means】The optical laminate according to an embodiment of the present invention has a polarizing plate including a polarizer and a retardation layer. The retardation layer includes, in order from the polarizer side, a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer laminated to the first liquid crystal alignment cured layer via an adhesive layer. The retardation layer as a whole has a circular polarization function or an elliptical polarization function and has a relationship of Re(450) < Re(550) < Re(650). The refractive index n of the first liquid crystal alignment cured layer LC1 , the refractive index n of the second liquid crystal alignment cured layer LC2 , and the refractive index n of the adhesive layer AD , and the thickness T of the adhesive layer AD and the thickness variation TV AD satisfy the following formula (1): |{(n LC1 + n LC2 ) / 2 - n AD}| × (TV AD / T AD ) × 1000 ≦ 3.0 ···(1)

Description

[Technical Field]

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

[0002] In recent years, image display devices, such as liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays and inorganic EL displays), have become rapidly widespread. Image display devices often utilize optical laminates containing phase difference films (e.g., anti-reflective films integrating polarizers and phase difference films). In recent years, with the increasing demand for thinner image display devices, there has also been a growing demand for thinner optical laminates. To achieve this, thinning of the phase difference layer (phase difference film), which contributes significantly to the thickness, is progressing. A typical example of a thin phase difference film is a film in which liquid crystal compounds are oriented and their orientation is fixed (hereinafter referred to as a liquid crystal film). Because liquid crystal compounds have significantly greater birefringence (Δn) than resins, the thickness required to obtain the desired in-plane phase difference for a liquid crystal film can be significantly reduced compared to a stretched resin film. However, image display devices using optical laminates including liquid crystal films may exhibit display inconsistencies (specifically, a phenomenon in which thin lines of particularly prominent pink color are visible in the direction of the polarizer's absorption axis) depending on the viewing environment. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-222282 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention has been made to solve the above-described conventional problems, and its main object is to provide an optical laminate that includes a liquid crystal alignment cured layer and can suppress specific display unevenness when applied to an image display device.

Means for Solving the Problems

[0005] [1] The optical laminate according to an embodiment of the present invention has a polarizing plate including a polarizer and a retardation layer; the retardation layer includes, in order from the polarizing plate side, a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer laminated to the first liquid crystal alignment cured layer via an adhesive layer; the retardation layer has, as a whole, a circular polarization function or an elliptical polarization function and has a relationship of Re(450) < Re(550) < Re(650); the refractive index n LC1 of the first liquid crystal alignment cured layer, the refractive index n LC2 of the second liquid crystal alignment cured layer, and the refractive index n AD of the adhesive layer, and the thickness T AD and thickness variation TV AD of the adhesive layer satisfy the following formula (1): |{(n LC1 + n LC2 ) / 2 - n AD}| × (TV AD / T AD ) × 1000 ≤ 3.0 ···(1) [2] In the above [1], the adhesive layer is composed of an adhesive. [3] In the above [2], the thickness T AD of the adhesive layer is 4 μm or more. [4] In the above [1], the adhesive layer is composed of an adhesive. [5] In any one of the above [1] to [4], the refractive index n AD of the adhesive layer is 1.54 or more. [6] In any one of the above [1] to [5], the thickness of the first liquid crystal alignment cured layer is 1.7 μm or less. [7] According to another aspect of the present invention, an image display device is provided. The image display device includes the optical laminate of the above [1] to [6].

Effects of the Invention

[0006] According to embodiments of the present invention, an optical laminate can be realized that includes a liquid crystal alignment solidification layer and can suppress specific display irregularities when applied to an image display device. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments.

[0009] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference of a film measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference of a film measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated using the formula: Re=(nx-ny)×d, where d(nm) is the thickness of the film. (3) Phase difference in the thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction of the film measured with light of wavelength λnm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction of the film measured with light of wavelength 550nm at 23°C. Rth(λ) can be calculated using the formula: Rth = (nx - nz) × d, where d (nm) is the thickness of the film. (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, unless otherwise specified, the angle includes angles in both clockwise and counterclockwise directions.

[0010] A. Optical laminate FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The illustrated optical laminate 100 has a polarizing plate 10 and a retardation layer 20. The polarizing plate 10 and the retardation layer 20 are laminated via any suitable adhesive layer (e.g., an adhesive layer, a pressure-sensitive adhesive layer: not shown). The polarizing plate 10 typically includes a polarizer 11 and protective layers 12 and 13 disposed on both sides of the polarizer 11. Depending on the purpose, at least one of the protective layers 12 and 13 may be omitted. Therefore, the polarizing plate may be a so-called double-protection polarizing plate, a so-called single-protection polarizing plate, or may be composed of only a polarizer.

[0011] The retardation layer 20 includes, in order from the polarizing plate 10 side, a first liquid crystal alignment cured layer 21 and a second liquid crystal alignment cured layer 22 laminated to the first liquid crystal alignment cured layer 21 via an adhesive layer 25. By using the liquid crystal alignment cured layer as the retardation layer, a desired in-plane retardation can be realized with a thickness significantly thinner than that of a stretched film of a resin film. As a result, significant thinning of the optical laminate can be achieved. The retardation layer 20 as a whole (as a laminate of the first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22) has a circular polarization function or an elliptical polarization function and has a relationship of Re(450) < Re(550) < Re(650). In one embodiment, the retardation layer as a whole may have an Nz coefficient of, for example, 0.30 to 0.70. In this specification, the "liquid crystal alignment cured layer" refers to a layer in which a liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. The "liquid crystal alignment cured layer" is a concept that includes an alignment cured layer obtained by curing a liquid crystal monomer.

[0012] In an embodiment of the present invention, the refractive index n of the first liquid crystal alignment cured layer LC1 and the refractive index n of the second liquid crystal alignment cured layerLC2 , and the refractive index n of the adhesive layer AD , and also, the thickness T of the adhesive layer AD and thickness variations TV AD The following equation (1) is satisfied. The left-hand side of equation (1) is sometimes referred to as the display uniformity parameter. Furthermore, in this specification, the "refractive index" of the liquid crystal alignment solidification layer refers to the refractive index in the transmission axis direction of the polarizer unless otherwise specified. Since the adhesive layer is substantially optically isotropic, the refractive index n AD It is also isotropic. |{(n LC1 +n LC2 ) / 2-n AD}|×(TV AD / T AD ) × 1000 ≤ 3.0 ···(1) The display unevenness parameter is preferably 2.5 or less, more preferably 2.0 or less, even more preferably 1.8 or less, particularly preferably 1.2 or less, and especially preferably 0.7 or less. A smaller display unevenness parameter (absolute value) is preferable, and may be, for example, 0.0.

[0013] While considering further thinning of an optical laminate containing a liquid crystal alignment solidification layer as a phase difference layer, the inventors discovered a new problem: image display devices using an optical laminate containing a liquid crystal alignment solidification layer as a phase difference layer may exhibit certain display irregularities depending on the viewing environment. Specifically, they found that under reflection from a three-wavelength light source, a thin line with a particularly prominent pink color in the direction of the polarizer's absorption axis can be seen throughout (sometimes referred to as linear irregularity). Furthermore, the inventors diligently investigated ways to suppress such linear irregularities and found that they can be suppressed by suppressing interference within the optical laminate. In addition, the inventors found that, rather than individually adjusting the refractive index, thickness, etc., of each layer constituting the optical laminate to suppress interference, linear irregularities can be comprehensively suppressed in a specific configuration of the optical laminate according to the purpose and / or constituent materials, etc., by setting the above-mentioned display irregularity parameters to below a predetermined value, thus completing the present invention. In other words, the effects of the embodiments of the present invention solve newly identified problems when considering further thinning of optical laminates including a liquid crystal alignment solidification layer as a phase difference layer, and represent an unexpectedly excellent effect. Needless to say, the embodiments of the present invention can suppress display unevenness that has been recognized conventionally.

[0014] As the adhesive layer 25, any suitable configuration can be adopted, as long as the effects according to the embodiment of the present invention can be obtained (specifically, as long as the above-mentioned display unevenness parameter can be kept below a predetermined value). For example, the adhesive layer may be composed of an adhesive or an adhesive. When the adhesive layer is composed of an adhesive, the thickness can be increased, making it easy to adjust the display unevenness parameter to a desired value. In this case, the thickness T of the adhesive layer AD This can be, for example, 4 μm or more, or for example, 5 μm or more. When the adhesive layer is composed of an adhesive, it may be possible to adjust the display uniformity parameter to a desired value with a very thin thickness. Regardless of whether the adhesive layer is an adhesive layer or a tack layer, the refractive index n of the adhesive layer ADPreferably, the refractive index of the adhesive layer is 1.54 or higher. If the refractive index of the adhesive layer is within this range, it is easy to adjust the display unevenness parameter to a predetermined value or lower.

[0015] In the optical laminate, the total thickness from the first liquid crystal alignment solidification layer to the second liquid crystal alignment solidification layer is preferably 20 μm or less, and more preferably 3 μm to 10 μm. According to the embodiment of the present invention, the problem of linear unevenness newly discovered in optical laminates containing very thin liquid crystal alignment solidification layers can be solved. If the total thickness from the first liquid crystal alignment solidification layer to the second liquid crystal alignment solidification layer is within the above range, the total thickness from the polarizing plate to the second liquid crystal alignment solidification layer (the substantial total thickness of the optical laminate, excluding the thickness of the adhesive for bonding to the image display panel) can be, for example, 100 μm or less, or for example, 30 μm to 80 μm.

[0016] In practical terms, the optical laminate has an adhesive layer (not shown) as the outermost layer on the second liquid crystal alignment solidification layer side (image display panel side), and is designed to be attachable to an image display panel. In this case, it is preferable that a release liner is temporarily attached to the surface of the adhesive layer until the optical laminate is put into use. By temporarily attaching the release liner, the adhesive layer is protected and roll formation of the optical laminate becomes possible.

[0017] The components of the optical laminate will be explained in detail below.

[0018] B. Polarizing plate B-1.Polarizer The polarizer 11 is typically composed of a polyvinyl alcohol (PVA) resin film containing a dichroic substance (e.g., iodine). Examples of PVA resins include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and partially saponified ethylene-vinyl acetate copolymer.

[0019] The PVA resin preferably includes an acetoacetyl-modified PVA resin. With such a configuration, a polarizer with the desired mechanical strength can be obtained. The amount of acetoacetyl-modified PVA resin is preferably 5% to 20% by weight, and more preferably 8% to 12% by weight, when the total PVA resin is considered to be 100% by weight. A polarizer with even better mechanical strength can be obtained when the amount is within this range.

[0020] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as halide). Examples of iodide include potassium iodide, sodium iodide, and lithium iodide. The halide content in the polarizer is preferably 5 to 20 parts by weight, and more preferably 10 to 15 parts by weight, per 100 parts by weight of PVA resin. In the manufacturing method described later, the halide can be incorporated into the coating solution that forms the PVA resin layer, which is a precursor of the polarizer, and finally introduced into the polarizer. By introducing a halide into the polarizer, the orientation of PVA molecules in the polarizer can be increased, making it possible to realize a polarizer with excellent optical properties (typically, a combination of high polarization degree and high single-element transmittance).

[0021] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is preferably 41.0% to 46.0%, more preferably 42.0% to 45.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher. According to embodiments of the present invention, even if the transmittance of the polarizer is within the above range, the degree of polarization can be maintained within this range.

[0022] The thickness of the polarizer is, for example, 12 μm or less, preferably 10 μm or less, more preferably 1 μm to 8 μm, and even more preferably 3 μm to 7 μm. By combining such a thin polarizer with a liquid crystal alignment solidification layer, significant thinning of the optical laminate becomes possible. Furthermore, if the thickness of the polarizer is within the above range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0023] Polarizers can be manufactured by any suitable method. For example, the resin film forming the polarizer may be a single layer resin film or a laminate of two or more layers.

[0024] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with dichroic substances such as iodine or dichroic dyes and stretched, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA-based film with iodine and uniaxially stretching it are used because they have excellent optical properties.

[0025] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA film may be subjected to swelling, crosslinking, washing, drying, etc. For example, immersing the PVA film in water and washing it before dyeing can not only clean dirt and anti-blocking agents from the surface of the PVA film, but also swell the PVA film to prevent uneven dyeing.

[0026] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. As a result, the optical properties of the polarizer obtained through processing steps in which the laminate is immersed in liquid, such as dyeing and water-based stretching, can be improved. Furthermore, by shrinking the laminate in the width direction through the drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0027] B-2.Protective layer The protective layers 12 and 13 are composed of any suitable resin film. Typical materials for the resin film include cellulosic resins such as triacetylcellulose (TAC), cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. Typical examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are incorporated herein by reference. From the viewpoint of ease of shaping, cellulose resins are preferred, and TAC is more preferred. From the viewpoint of obtaining polarizing plates with low moisture permeability and excellent durability, cycloolefin resins and (meth)acrylic resins are preferred.

[0028] The optical laminate is typically positioned on the viewing side of the image display device, and the protective layer 12 is typically positioned on the viewing side. Therefore, the protective layer 12 may be surface-treated as needed. Examples of surface treatments include hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating. Furthermore / or, the protective layer 12 may be treated as needed to improve visibility when viewed through polarized sunglasses (typically by providing (elliptic) polarization functionality or providing ultra-high phase difference). By applying such treatment, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the optical laminate can be suitably applied to image display devices that may be used outdoors.

[0029] In one embodiment, the protective layer 13 is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm.

[0030] The thickness of protective layers 12 and 13 is preferably 10 μm to 80 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 35 μm, respectively. If protective layer 12 is surface-treated, the thickness of protective layer 12 includes the thickness of the surface treatment layer.

[0031] C. Retardation layer As described above, the retardation layer 20 includes a first liquid crystal alignment cured layer 21 and a second liquid crystal alignment cured layer 22 in this order from the polarizer side. Further, as described above, the retardation layer 20 as a whole (as a laminate of the first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22) has a circular polarization function or an elliptical polarization function, and has a relationship of Re(450) < Re(550) < Re(650). Regarding the description of the retardation layer in this section, simply referring to the "retardation layer" means describing the entire retardation layer, and simply referring to the "liquid crystal alignment cured layer" means collectively describing the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer.

[0032] For the retardation layer 20, Re(550) is preferably 100 nm to 200 nm, more preferably 110 nm to 180 nm, still more preferably 120 nm to 170 nm, and particularly preferably 130 nm to 150 nm. If Re(550) of the retardation layer is within such a range, the retardation layer can exhibit a good circular polarization function or elliptical polarization function in combination with a polarizer.

[0033] The retardation layer 20 has a relationship of Re(450) < Re(550) < Re(650). That is, the retardation layer 20 preferably exhibits an inverse dispersion wavelength dependence in which the retardation value increases according to the wavelength of the measurement light. With such a configuration, a good antireflection function can be realized in a very wide wavelength band. Re(450) / Re(550) is, for example, more than 0.5 and less than 1.0, preferably 0.7 to 0.95, more preferably 0.75 to 0.92, and still more preferably 0.8 to 0.9. Re(650) / Re(550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 to 1.1.

[0034] In one embodiment, the phase difference layer 20 may have an Nz coefficient of, for example, 0.30 to 0.70 as described above. Therefore, the phase difference layer 20 exhibits refractive index characteristics nx>nz>ny. With such a configuration, reflections in oblique directions can be effectively prevented, and the anti-reflective function can be widened to a wider viewing angle. The Nz coefficient is preferably 0.35 to 0.65, more preferably 0.40 to 0.60, and even more preferably 0.45 to 0.55.

[0035] Examples of liquid crystal compounds used in the liquid crystal alignment solidification layer include liquid crystal polymers and liquid crystal monomers. Preferably, the liquid crystal compound is polymerizable (i.e., a liquid crystal monomer). If the liquid crystal compound is polymerizable, the orientation state of the liquid crystal compound can be fixed by polymerizing it after orientation. Here, the polymer formed by polymerization is non-liquid crystallized. Therefore, the formed liquid crystal alignment solidification layer does not undergo transitions to liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which is characteristic of liquid crystal compounds. As a result, the liquid crystal alignment solidification layer becomes an extremely stable phase difference layer that is unaffected by temperature changes.

[0036] In one embodiment, the liquid crystal alignment solidification layer can be formed using a composition containing a polymerizable liquid crystal compound (a polymerizable liquid crystal compound, i.e., a liquid crystal monomer). In this specification, a polymerizable liquid crystal compound included in the composition means a compound that has a polymerizable group and is liquid crystal. A polymerizable group means a group that participates in the polymerization reaction, and is preferably a photopolymerizable group. Here, a photopolymerizable group means a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator. As liquid crystal monomers, for example, polymerizable mesogenic compounds described in JP 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767.

[0037] The mechanism by which the liquid crystalline properties of a liquid crystal compound are exhibited may be thermotropic or lyotropic. Furthermore, the liquid crystal phase may be composed of either a nematic or smectic liquid crystal. From the viewpoint of ease of manufacture, a thermotropic nematic liquid crystal is preferred.

[0038] The temperature range in which liquid crystal monomers exhibit liquid crystalline properties varies depending on the type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

[0039] The birefringence Δn of the liquid crystal alignment solidification layer is preferably 0.06 or higher, more preferably 0.08 or higher, even more preferably 0.09 or higher, and particularly preferably 0.10 or higher. The upper limit of Δn may be, for example, 0.13 or 0.12. When Δn is within this range, the desired in-plane phase difference can be achieved with a very thin thickness. As a result, the liquid crystal alignment solidification layer and the optical laminate can be made even thinner, which can ultimately contribute to a significant reduction in the thickness of the image display device.

[0040] The liquid crystal alignment solidification layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measurement light, or it may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with the wavelength of the measurement light, or it may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes with the wavelength of the measurement light.

[0041] The first liquid crystal alignment solidification layer 21 can typically function as a λ / 2 plate, and the second liquid crystal alignment solidification layer 22 can typically function as a λ / 4 plate. Specifically, the Re(550) of the first liquid crystal alignment solidification layer is preferably 150 nm to 300 nm, more preferably 200 nm to 270 nm, and even more preferably 220 nm to 260 nm; the Re(550) of the second liquid crystal alignment solidification layer is preferably 100 nm to 200 nm, more preferably 110 nm to 160 nm, and even more preferably 120 nm to 140 nm. The thickness of the first liquid crystal alignment solidification layer can be adjusted to obtain a desired in-plane phase difference of the λ / 2 plate. In one embodiment, the thickness of the first liquid crystal alignment solidification layer may be, for example, 2.0 μm to 4.0 μm. In another embodiment, the thickness of the first liquid crystal alignment solidification layer is preferably 1.7 μm or less, more preferably 1.6 μm or less, and even more preferably 1.5 μm or less. In this case, the thickness of the first liquid crystal alignment solidification layer may be, for example, 1.3 μm or more. Thus, according to the embodiment of the present invention, linear unevenness can be suppressed while making the thickness of the first liquid crystal alignment solidification layer thinner than in the conventional method. The thickness of the second liquid crystal alignment solidification layer can be adjusted so that a desired in-plane phase difference of the λ / 4 plate is obtained. Specifically, its thickness may be, for example, 0.8 μm to 2.5 μm. The angle between the slow axis of the first liquid crystal alignment solidification layer and the transmission axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 14° to 16°; the angle between the slow axis of the second liquid crystal alignment solidification layer and the transmission axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 74° to 76°. Furthermore, the arrangement order of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be reversed, and the angle between the slow axis of the first liquid crystal alignment solidification layer and the transmission axis of the polarizer, and the angle between the slow axis of the second liquid crystal alignment solidification layer and the transmission axis of the polarizer may be reversed.

[0042] The refractive index of the liquid crystal alignment solidification layer may vary depending on the composition forming the liquid crystal alignment solidification layer (essentially, the type of liquid crystal compound, the type, number, combination, and amount of additives). The refractive index of the first liquid crystal alignment solidification layer is n LC1 and the refractive index n of the second liquid crystal alignment solidification layerLC2 These may be the same, or they may be different from each other (refractive index n of the first liquid crystal alignment solidification layer). LC1 The refractive index n of the second liquid crystal alignment solidification layer may be larger. LC2 (It may be larger than this.) The refractive index n of the first liquid crystal alignment solidification layer LC1 The refractive index n of the second liquid crystal alignment solidification layer is preferably 1.55 to 1.75, and more preferably 1.60 to 1.70. LC2 The refractive index n of the first liquid crystal alignment solidification layer is preferably 1.45 to 1.65, and more preferably 1.50 to 1.60. LC1 and the refractive index n of the second liquid crystal alignment solidification layer LC2 The opposite may also be true. The refractive index n of the first liquid crystal alignment solidification layer. LC1 and the refractive index n of the second liquid crystal alignment solidification layer LC2 The absolute value of the difference can be, for example, 0.00 to 0.20. The refractive index of the liquid crystal alignment solidification layer typically corresponds to the composition of the composition used to form the liquid crystal alignment solidification layer in order to obtain the desired optical properties. As a result, linear unevenness may occur, but according to the embodiment of the present invention, linear unevenness can be suppressed by setting the display unevenness parameter to a predetermined value or less.

[0043] A side-chain type thermotropic liquid crystal polymer may be introduced into the first liquid crystal alignment solidification layer and / or the second liquid crystal alignment solidification layer (substantially, the liquid crystal composition forming them). Introducing a side-chain type thermotropic liquid crystal polymer can cause the liquid crystal monomers to undergo homeotropic alignment (vertical alignment). As a result, the nz of the first liquid crystal alignment solidification layer and / or the second liquid crystal alignment solidification layer can be increased, and consequently, the Nz coefficient of the first liquid crystal alignment solidification layer and / or the second liquid crystal alignment solidification layer can be set to the desired range described above. Finally, the Nz coefficient of the phase difference layer can be set to the desired range described above without providing the positive C plate described later.

[0044] Typical side-chain thermotropic liquid crystal polymers include copolymers having monomer units containing thermotropic liquid crystal fragment side chains and monomer units containing non-liquivalent fragment side chains. The presence of thermotropic liquid crystal fragments in the side chains of the polymer allows the side-chain liquid crystal polymer to be oriented when the liquid crystal composition is heated to a predetermined temperature. Furthermore, the presence of non-liquivalent fragments in the side chains of the side-chain polymer allows the non-liquivalent fragments to interact with photopolymerizable liquid crystal monomers, potentially causing the photopolymerizable liquid crystal monomers to undergo homeotropic orientation.

[0045] As the side-chain type thermotropic liquid crystal polymer, a copolymer having a liquid crystalline monomer unit represented by general formula (I) and a non-liquid crystalline monomer unit represented by general formula (II) is preferably used. [ka] [ka]

[0046] In equation (I), R 1 R is a hydrogen atom or a methyl group, 2 X is a cyano group, a fluoro group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 is -CO2- or -OCO-. a is an integer between 1 and 6, and b and c are independently either 1 or 2.

[0047] In equation (II), R 3 R is a hydrogen atom or a methyl group, 4 This is an alkyl group having 7 to 22 carbon atoms, a fluoroalkyl group having 1 to 22 carbon atoms, or a group represented by the following general formula (III). [ka]

[0048] In equation (III), R5 is an alkyl group having 1 to 5 carbon atoms, and d is an integer from 1 to 6.

[0049] The ratio of liquid crystalline monomer units to non-liquid crystalline monomer units in a side-chain type liquid crystal monomer can be appropriately set depending on the purpose. The ratio (molar ratio) of non-liquid crystalline monomers to the total of liquid crystalline monomer units is preferably 0.05 to 0.8, more preferably 0.1 to 0.6, and even more preferably 0.15 to 0.5. With such a configuration, a liquid crystal orientation solidified layer exhibiting the desired refractive index characteristics (Nz coefficient) can be obtained.

[0050] The ratio of liquid crystal monomers to side-chain liquid crystal polymers in a liquid crystal composition can be appropriately set depending on the purpose. When the content of side-chain liquid crystal polymers is high, the Nz coefficient tends to be low; when the content of liquid crystal monomers is high, the Nz coefficient tends to be low. The content of liquid crystal monomers is preferably 1.2 to 20 times, more preferably 1.3 to 10 times, even more preferably 1.4 to 9 times, and particularly preferably 1.5 to 8 times, relative to the content of side-chain liquid crystal polymers. With such a configuration, a liquid crystal orientation solidified layer exhibiting the desired refractive index characteristics (Nz coefficient) can be obtained.

[0051] Details of a method for forming a side-chain liquid crystal polymer and a liquid crystal alignment solidified layer having an Nz coefficient of less than 1.0 are described in Japanese Patent No. 6769921. The contents of that patent are incorporated herein by reference.

[0052] The phase difference layer 20 may further include a positive C plate. The positive C plate exhibits a refractive index characteristic where nz > nx = ny. The phase difference Rth(550) in the thickness direction of the positive C plate is preferably -20 nm to -300 nm, more preferably -30 nm to -250 nm, even more preferably -40 nm to -200 nm, and particularly preferably -50 nm to -150 nm. Here, "nx = ny" includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the positive C plate may be less than 10 nm.

[0053] Positive C plates can be formed, for example, using a composition containing the above-mentioned side-chain type liquid crystal polymer. A specific example of a method for forming a positive C plate is the method described in sections

[0020] to

[0028] of Japanese Patent Application Publication No. 2002-333642. In this case, the thickness of the positive C plate is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0054] D. Adhesive layer D-1.Overview Any suitable configuration can be adopted for the adhesive layer 25, as long as the display unevenness parameter can be kept below a predetermined value. Specifically, as described above, the adhesive layer may be composed of a tack or an adhesive. Regardless of whether the adhesive layer is an adhesive layer or a tack layer, the refractive index n of the adhesive layer AD n may be, for example, 1.45 or higher, or for example, 1.50 or higher, or for example, 1.52 or higher. AD The refractive index n of the adhesive layer is preferably 1.54 or higher, more preferably 1.55 or higher, even more preferably 1.57 or higher, and particularly preferably 1.60 or higher. AD This could be, for example, 1.63 or less.

[0055] If the adhesive layer is an adhesive layer, then the thickness T of the adhesive layer ADFor example, it is 3 μm or more, preferably 4 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. On the other hand, the thickness T of the adhesive layer AD This can be, for example, 30 μm or less. If the adhesive layer is an adhesive layer, the thickness T of the adhesive layer. AD The thickness is preferably 0.5 μm to 2.0 μm, and more preferably 0.8 μm to 1.2 μm. (Adhesive layer thickness variation TV) AD The thickness is preferably 0.20 μm or less, more preferably 0.18 μm or less, and even more preferably 0.16 μm or less. On the other hand, the thickness variation of the adhesive layer TV AD This can be, for example, 0.03 μm or more. By adjusting the refractive index and thickness of the adhesive layer in combination, the display uniformity parameter can be adjusted to an appropriate range to match the configuration of the liquid crystal alignment solidification layer. Considering the relationship between thickness and thickness variation, the adhesive layer can preferably be an adhesive layer. This is because increasing the thickness can reduce the effect of thickness variation.

[0056] The adhesive and bonding agents that make up the bonding layer are described below.

[0057] D-2. Adhesive Any suitable configuration can be used as the adhesive, as long as it satisfies the above-mentioned properties. Specific examples of adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and blending ratio of monomers forming the base polymer of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., an adhesive with desired properties according to the purpose can be prepared. The base polymer of the adhesive may be used alone or in combination of two or more types. From the viewpoint of transparency, processability, and durability, acrylic adhesives (acrylic adhesive compositions) are preferred. Typically, acrylic adhesive compositions mainly contain (meth)acrylic polymer as the base polymer. (Meth)acrylic polymer may be contained in the adhesive composition in a proportion of, for example, 50% or more by weight, preferably 70% or more by weight, and more preferably 90% or more by weight, of the solid content of the adhesive composition. (Meth)acrylate refers to acrylate and / or methacrylate.

[0058] The (meth)acrylic polymer preferably contains an aromatic ring-containing monomer (m1) as a monomer component. As the monomer (m1), a compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule may be used. As the monomer (m1), such a compound may be used alone or in combination of two or more.

[0059] Examples of ethylenically unsaturated groups include (meth)acryloyl groups, vinyl groups, and (meth)allyl groups. From the viewpoint of polymerization reactivity, (meth)acryloyl groups are preferred, and from the viewpoint of flexibility and tackiness, acryloyl groups are more preferred. From the viewpoint of suppressing a decrease in the flexibility of the adhesive, a compound in which the number of ethylenically unsaturated groups in one molecule is 1 (i.e., a monofunctional monomer) is preferably used as the monomer (m1).

[0060] The number of aromatic rings contained in one molecule of the compound used as monomer (m1) may be 1 or 2 or more. There is no particular upper limit to the number of aromatic rings contained in monomer (m1), and it may be, for example, 16 or less. In some embodiments, from the viewpoint of ease of preparation of the (meth)acrylic polymer and transparency of the adhesive, the number of aromatic rings may be, for example, 12 or less, preferably 8 or less, more preferably 6 or less, may be 5 or less, may be 4 or less, may be 3 or less, or may be 2 or less.

[0061] The aromatic ring of the compound used as monomer (m1) may be a carbon ring such as a benzene ring (which may be a benzene ring that constitutes part of a biphenyl or fluorene structure); a fused ring of a naphthalene ring, indene ring, azulene ring, anthracene ring, or phenanthrene ring; or a heteroring such as a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, isoxazole ring, thiazole ring, or thiophene ring. The heteroatoms included as ring constituent atoms in the above heteroring may be one or more selected from the group consisting of nitrogen, sulfur, and oxygen. In some embodiments, the heteroatoms constituting the heteroring may be nitrogen and sulfur, or both. Monomer (m1) may have a structure in which one or more carbon rings and one or more heterorings are fused, such as a dinaphthothiophene structure.

[0062] The aromatic ring (preferably a carbocyclic ring) may have one or more substituents on its ring constituent atoms, or it may not have substituents. If substituents are present, examples of substituents include alkyl groups, alkoxy groups, aryloxy groups, hydroxyl groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, etc.), hydroxyalkyl groups, hydroxyalkyloxy groups, and glycidyloxy groups. In substituents containing carbon atoms, the number of carbon atoms in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be, for example, 1 or 2. In some embodiments, the aromatic ring may have no substituents on its ring constituent atoms, or it may be an aromatic ring having one or more substituents selected from the group consisting of alkyl groups, alkoxy groups, and halogen atoms (e.g., bromine atoms). Note that when an aromatic ring of a monomer (m1) is said to have substituents on its ring constituent atoms, it means that the aromatic ring has substituents other than substituents having an ethylenically unsaturated group.

[0063] The aromatic ring and the ethylenically unsaturated group may be directly bonded or bonded via a linking group. The linking group may be a group containing one or more structures selected from, for example, alkylene groups, oxyalkylene groups, poly(oxyalkylene) groups, phenyl groups, alkylphenyl groups, alkoxyphenyl groups, groups in which one or more hydrogen atoms are substituted with hydroxyl groups (e.g., hydroxyalkylene groups), oxy groups (-O- groups), thiooxy groups (-S- groups), etc. In some embodiments, aromatic ring-containing monomers in which the aromatic ring and the ethylenically unsaturated group are directly bonded or bonded via a linking group selected from the group consisting of alkylene groups, oxyalkylene groups, and poly(oxyalkylene) groups may be preferably used. The number of carbon atoms in the alkylene group and oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, and may be, for example, 1 or 2. The number of repeating oxyalkylene units in the poly(oxyalkylene) group may be, for example, 2 to 3.

[0064] Examples of compounds that can be preferably used as monomers (m1) include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds. Aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds can each be used individually or in combination of two or more. One or more aromatic ring-containing (meth)acrylates may be used in combination with one or more aromatic ring-containing vinyl compounds.

[0065] The monomer (m1) content in the monomer component constituting the (meth)acrylic polymer can be set, for example, to realize an adhesive layer that achieves both a desired refractive index and adhesive properties (e.g., peel strength, flexibility, etc.) and / or optical properties (e.g., total light transmittance, haze value, etc.). In some embodiments, the monomer (m1) content in the monomer component may be, for example, 30% by weight or more, preferably 50% by weight or more, may be 60% by weight or more, or 70% by weight or more. From the viewpoint of easily obtaining a higher refractive index, in some embodiments, the monomer (m1) content may be, for example, more than 70% by weight, may be 75% by weight or more, may be 80% by weight or more, may be 85% by weight or more, may be 90% by weight or more, or may be 95% by weight or more. The upper limit of the monomer (m1) content in the monomer component is 100% by weight. From the viewpoint of achieving a good balance between high refractive index and adhesive properties and / or optical properties, it is advantageous to have a monomer (m1) content of less than 100% by weight, for example, preferably about 99% by weight or less, more preferably 98% by weight or less, and may also be 97% by weight or less, or 96% by weight or less. In some embodiments, the monomer (m1) content may be 93% by weight or less, 90% by weight or less, 80% by weight or less, or 75% by weight or less. In some embodiments where adhesive properties and / or optical properties are given more importance, the monomer (m1) content in the monomer component may be 70% by weight or less, 60% by weight or less, or 45% by weight or less.

[0066] In some embodiments, monomers (m1) having two or more aromatic rings (preferably carbocyclic rings) in one molecule can be preferably used because they easily provide a high refractive index effect. Examples of monomers having two or more aromatic rings in one molecule (hereinafter also referred to as "multiple aromatic ring-containing monomers") include monomers having a structure in which two or more non-condensed aromatic rings are linked via linking groups, monomers having a structure in which two or more non-condensed aromatic rings are chemically bonded directly (i.e., without other atoms), monomers having a condensed aromatic ring structure, monomers having a fluorene structure, monomers having a dinaphthothiophene structure, monomers having a dibenzothiophene structure, and the like. Multiple aromatic ring-containing monomers may be used alone or in combination of two or more types.

[0067] Linking groups include, for example, oxy groups (-O-), thiooxy groups (-S-), and oxyalkylene groups (e.g., -O-(CH2)). n - group, where n is 1 to 3, preferably 1), thiooxyalkylene group (e.g., -S-(CH2) n - group, where n is 1 to 3, preferably 1), linear alkylene group (i.e., -(CH2) n -Groups (where n is 1 to 6, preferably 1 to 3), oxyalkylene groups, thiooxyalkylene groups, and linear alkylene groups in which the alkylene group is partially halogenated or fully halogenated. From the viewpoint of the flexibility of the adhesive, preferred examples of linking groups include oxy groups, thiooxy groups, oxyalkylene groups, and linear alkylene groups. Specific examples of monomers having a structure in which two or more non-condensed aromatic rings are linked via linking groups include phenoxybenzyl(meth)acrylate (e.g., m-phenoxybenzyl(meth)acrylate), thiophenoxybenzyl(meth)acrylate, and benzylbenzyl(meth)acrylate.

[0068] Monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded may include, for example, biphenyl structure-containing (meth)acrylates, triphenyl structure-containing (meth)acrylates, and vinyl group-containing biphenyls. Specific examples include o-phenylphenol (meth)acrylate and biphenylmethyl (meth)acrylate.

[0069] Examples of monomers having a condensed aromatic ring structure include naphthalene ring-containing (meth)acrylate, anthracene ring-containing (meth)acrylate, vinyl group-containing naphthalene, and vinyl group-containing anthracene. Specific examples include 1-naphthylmethyl (meth)acrylate (also known as 1-naphthalenemethyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, and 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate.

[0070] Specific examples of monomers having a fluorene structure include 9,9-bis(4-hydroxyphenyl)fluorene(meth)acrylate and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene(meth)acrylate. Note that monomers having a fluorene structure include a structural portion in which two benzene rings are directly chemically bonded, and therefore are included in the concept of monomers having a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

[0071] Examples of monomers having a dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, and (meth)allyl group-containing dinaphthothiophene. A specific example is (meth)acryloyloxymethyl dinaphthothiophene (for example, CH2CH(R) at the 5th or 6th position of the dinaphthothiophene ring). 1 A compound with a structure in which C(O)OCH2- is bonded. Here, R 1 (These are a hydrogen atom or a methyl group.) (meth)acryloyloxyethyl dinaphthothiophene (for example, CH2CH(R) at the 5th or 6th position of the dinaphthothiophene ring) 1)C(O)OCH(CH3)- or CH2CH(R 1 A compound with a structure in which C(O)OCH2CH2- is bonded. Here, R 1 The group is a hydrogen atom or a methyl group. Examples include vinyl dinaphthothiophene (for example, a compound in which a vinyl group is bonded to the 5th or 6th position of the naphthothiophene ring) and (meth)allyloxydinaphthothiophene. Monomers having a dinaphthothiophene structure are also included in the concept of monomers having a condensed aromatic ring structure by including a naphthalene structure or by having a structure in which a thiophene ring and two naphthalene structures are condensed.

[0072] Examples of monomers containing a dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene and vinyl group-containing dibenzothiophene. Since monomers containing a dibenzothiophene structure have a structure in which a thiophene ring and two benzene rings are condensed, they are included in the concept of monomers containing a condensed aromatic ring structure. Neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

[0073] A monomer having one aromatic ring (preferably a carbon ring) in one molecule may be used as the monomer (m1). Monomers having one aromatic ring in one molecule can be useful, for example, for improving the flexibility of the adhesive, adjusting its adhesive properties, and improving its transparency. In some embodiments, monomers having one aromatic ring in one molecule are preferably used in combination with monomers containing multiple aromatic rings from the viewpoint of improving the refractive index of the adhesive.

[0074] Examples of monomers having one aromatic ring in one molecule include carbon aromatic ring-containing (meth)acrylates such as benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxybutyl (meth)acrylate, cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and chlorobenzyl (meth)acrylate; 2-(4,6-dibromo-2-s-butylphenoxy)ethyl (meth)acrylate, 2-(4,6-dibromo-2-isopropylphenoxy)ethyl (meth)acrylate, 6 Examples include bromine-substituted aromatic ring-containing (meth)acrylates such as -(4,6-dibromo-2-s-butylphenoxy)hexyl (meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl (meth)acrylate, 2,6-dibromo-4-nonylphenyl acrylate, and 2,6-dibromo-4-dodecylphenyl acrylate; carbon aromatic ring-containing vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and tert-butylstyrene; and compounds having vinyl substituents on heteroaromatic rings such as N-vinylpyridine, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, and N-vinyloxazole.

[0075] As the monomer (m1), a monomer having a structure in which an oxyethylene chain is interposed between the ethylenically unsaturated group and the aromatic ring in the various aromatic ring-containing monomers described above may be used. A monomer in which an oxyethylene chain is interposed between the ethylenically unsaturated group and the aromatic ring in this way can be understood as an ethoxylated product of the original monomer. The number of repeating oxyethylene units (-CH2CH2O-) in the oxyethylene chain is typically 1 to 4, preferably 1 to 3, more preferably 1 to 2, for example, 1. Specific examples of ethoxylated aromatic ring-containing monomers include ethoxylated o-phenylphenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, ethoxylated cresol (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxydiethylene glycol di(meth)acrylate.

[0076] The content of multiple aromatic ring-containing monomers in monomer (m1) is not particularly limited and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In some embodiments, from the viewpoint of making it easier to realize an adhesive with a higher refractive index, the content of multiple aromatic ring-containing monomers in monomer (m1) may be, for example, 50% by weight or more, preferably 70% by weight or more, may be 85% by weight or more, may be 90% by weight or more, or may be 95% by weight or more. Substantially 100% by weight of monomer (m1) may be multiple aromatic ring-containing monomers. That is, only one or two or more multiple aromatic ring-containing monomers may be used as monomer (m1). Also, in some embodiments, for example, considering the balance between high refractive index and adhesive properties and / or optical properties, the content of multiple aromatic ring-containing monomers in monomer (m1) may be less than 100% by weight, may be 98% by weight or less, may be 90% by weight or less, may be 80% by weight or less, or may be 65% by weight or less. In some embodiments, considering the adhesive properties and / or optical properties, the content of the multiple aromatic ring-containing monomer in monomer (m1) may be 70% by weight or less, 50% by weight or less, 25% by weight or less, or 10% by weight or less. Embodiments of the present invention may also be implemented even if the content of the multiple aromatic ring-containing monomer in monomer (m1) is less than 5% by weight. The multiple aromatic ring-containing monomer may not be used at all.

[0077] The content of multiple aromatic ring-containing monomers in the monomer component constituting the (meth)acrylic polymer is not particularly limited and can be set to realize an adhesive layer that achieves both a desired refractive index and adhesive properties (e.g., peel strength, flexibility, etc.) and / or optical properties (e.g., total light transmittance, haze value, etc.). The content of multiple aromatic ring-containing monomers in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In some embodiments, from the viewpoint of making it easier to realize an adhesive with a higher refractive index, the content of multiple aromatic ring-containing monomers in the monomer component may be, for example, more than 35% by weight, preferably more than 50% by weight, may be more than 70% by weight, may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, or may be 95% by weight or more. The content of multiple aromatic ring-containing monomers in the monomer component may be 100% by weight, but from the viewpoint of achieving a good balance between high refractive index and adhesive properties and / or optical properties, it is advantageous to have less than 100% by weight, preferably about 99% by weight or less, more preferably 98% by weight or less, and may also be 96% by weight or less, 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, or 75% by weight or less. In some embodiments, considering the adhesive properties and / or optical properties, the content of multiple aromatic ring-containing monomers in the monomer component may be 70% by weight or less, 50% by weight or less, 25% by weight or less, 15% by weight or less, or 5% by weight or less. Embodiments of the present invention may also be implemented even if the content of multiple aromatic ring-containing monomers in the monomer component is less than 3% by weight.

[0078] A high refractive index monomer may preferably be used as at least a part of the monomer (m1). Here, "high refractive index monomer" refers to a monomer whose refractive index is, for example, about 1.510 or higher, preferably about 1.530 or higher, and more preferably about 1.550 or higher. There is no particular upper limit to the refractive index of the high refractive index monomer, but from the viewpoint of ease of preparation of the adhesive composition and ease of compatibility with flexibility suitable for an adhesive, it may be, for example, 3.000 or less, 2.500 or less, 2.000 or less, 1.900 or less, 1.800 or less, or 1.700 or less. The high refractive index monomer may be used alone or in combination of two or more types. The refractive index of a monomer can be measured, for example, using an Abbe refractometer under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. An ATAGO model "DR-M4" or equivalent can be used as the Abbe refractometer. If the manufacturer provides a nominal refractive index value at 25°C, that nominal value can be used.

[0079] As high refractive index monomers, compounds with the appropriate refractive index can be appropriately selected from among the compounds included in the concept of aromatic ring-containing monomers (m1) (for example, the compounds and groups of compounds exemplified above). Specific examples include m-phenoxybenzyl acrylate (refractive index: 1.566, homopolymer Tg: -35°C), 1-naphthylmethyl acrylate (refractive index: 1.595, homopolymer Tg: 31°C), ethoxylated o-phenylphenol acrylate (number of oxyethylene unit repetitions: 1, refractive index: 1.578), benzyl acrylate (refractive index (nD20): 1.519, homopolymer Tg: 6°C), phenoxyethyl acrylate (refractive index (nD20): 1.517, homopolymer Tg: 2°C), and phenoxydiethylene glycol acrylate (refractive index: 1.51 Examples include 0 (homopolymer Tg: -35℃), 6-acryloyloxymethyl dinaphthothiophene (6MDNTA, refractive index: 1.75), 6-methacryloyloxymethyl dinaphthothiophene (6MDNTMA, refractive index: 1.726), 5-acryloyloxyethyl dinaphthothiophene (5EDNTA, refractive index: 1.786), 6-acryloyloxyethyl dinaphthothiophene (6EDNTA, refractive index: 1.722), 6-vinyl dinaphthothiophene (6VDNT, refractive index: 1.802), and 5-vinyl dinaphthothiophene (abbreviation: 5VDNT, refractive index: 1.793).

[0080] The content of high refractive index monomers (i.e., aromatic ring-containing monomers having a refractive index of about 1.510 or higher, preferably about 1.530 or higher, more preferably about 1.550 or higher) in monomer (m1) is not particularly limited and may be, for example, 5% by weight or more, 25% by weight or more, 35% by weight or more, or 40% by weight or more. In some embodiments, from the viewpoint of easily obtaining a higher refractive index, the content of high refractive index monomers in monomer (m1) may be, for example, 50% by weight or more, preferably 70% by weight or more, may be 85% by weight or more, may be 90% by weight or more, or may be 95% by weight or more. Substantially 100% by weight of monomer (m1) may be high refractive index monomers. Furthermore, in some embodiments, for example, from the viewpoint of achieving a good balance between high refractive index and adhesive properties and / or optical properties, the content of high refractive index monomer in monomer (m1) may be less than 100% by weight, 98% by weight or less, 90% by weight or less, 80% by weight or less, or 65% by weight or less. In some embodiments, considering adhesive properties and / or optical properties, the content of high refractive index monomer in monomer (m1) may be 70% by weight or less, 50% by weight or less, 25% by weight or less, 15% by weight or less, or 10% by weight or less. Embodiments of the present invention may be implemented even if the content of high refractive index monomer in monomer (m1) is less than 5% by weight. High refractive index monomer may not be used at all.

[0081] (Meth)acrylic polymers may contain monomers copolymerizable with aromatic ring-containing monomers (m1) (copolymer monomers) as monomer components. Examples of copolymer monomers include aliphatic alkyl (meth)acrylates, alicyclic alkyl (meth)acrylates, carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers. The type, number, combination, and content of copolymer monomers in the monomer component can be appropriately determined depending on the purpose.

[0082] Acrylic adhesives (acrylic adhesive compositions) may contain refractive index improvers depending on the purpose. In this specification, a refractive index improver refers to a material that can increase the refractive index of the adhesive layer when used. Preferably, a material with a higher refractive index than the refractive index of the adhesive layer containing the refractive index improver may be used as the refractive index improver. Furthermore, preferably, a material with a higher refractive index than the base polymer (e.g., an acrylic polymer) of the adhesive layer containing the refractive index improver may be used as the refractive index improver. By appropriately using a refractive index improver, a higher refractive index and practical adhesive performance can be suitably achieved. In some embodiments, the refractive index improver is preferably an organic material. The organic material used as a refractive index improver may be a polymer or a nonpolymer. It may also have polymerizable functional groups or not. The refractive index improver may be used alone or in combination of two or more types.

[0083] Refractive index improvers (for example, additives described later (H RO The refractive index of the refractive index improver can be set to an appropriate range in relation to the refractive index of the base polymer, and is not limited to a specific range. The refractive index of the refractive index improver can be selected from a range that is, for example, greater than 1.55, greater than 1.56, or greater than 1.57, and is higher than the refractive index of the base polymer. From the viewpoint of increasing the refractive index of the adhesive, in some embodiments, the refractive index of the refractive index improver is advantageous to be 1.58 or higher, preferably 1.60 or higher, more preferably 1.63 or higher, and may also be 1.65 or higher, 1.70 or higher, or 1.75 or higher. With a refractive index improver with a higher refractive index, the desired refractive index can be achieved even with the use of a smaller amount of refractive index improver. This is preferable from the viewpoint of suppressing a decrease in adhesive properties and optical properties. There is no particular upper limit to the refractive index of the refractive index improver, but from the viewpoint of compatibility within the adhesive and ease of achieving both a high refractive index and flexibility suitable for the adhesive, for example it may be 3.000 or less, 2.500 or less, 2.000 or less, 1.950 or less, 1.900 or less, or 1.850 or less.

[0084] In some embodiments, a refractive index improver (for example, an additive (H) described later) is used. RO The difference between the refractive index nb of the polymer and the refractive index na of the base polymer, i.e., nb-na (hereinafter also referred to as "ΔnA"), is set to be greater than 0. In some embodiments, ΔnA is, for example, 0.02 or more, may be 0.05 or more, may be 0.07 or more, may be 0.10 or more, may be 0.15 or more, may be 0.20 or more, or may be 0.25 or more. By selecting the base polymer and refractive index improver so that ΔnA is greater, the refractive index improvement effect due to the use of the refractive index improver tends to increase. Furthermore, from the viewpoint of compatibility within the adhesive layer and transparency of the adhesive layer, in some embodiments, ΔnA may be, for example, 0.70 or less, may be 0.60 or less, may be 0.50 or less, may be 0.40 or less, or may be 0.35 or less.

[0085] In some embodiments, a refractive index improver (for example, an additive (H) described later) is used. RO The difference between the refractive index nb of the material and the refractive index nT of the adhesive layer containing the refractive index improver, i.e., nb-nT (hereinafter also referred to as "ΔnB"), is set to be greater than 0. In some embodiments, ΔnB is, for example, 0.02 or more, may be 0.05 or more, may be 0.07 or more, may be 0.10 or more, may be 0.15 or more, may be 0.20 or more, or may be 0.25 or more. By selecting the composition of the adhesive layer and the refractive index improver so that ΔnB is greater, the refractive index improvement effect due to the use of the refractive index improver tends to increase. Also, from the viewpoint of compatibility within the adhesive layer and transparency of the adhesive layer, in some embodiments, ΔnB may be, for example, 0.70 or less, may be 0.60 or less, may be 0.50 or less, may be 0.40 or less, or may be 0.35 or less.

[0086] The amount of refractive index improver used per 100 parts by weight of base polymer (the total amount if multiple types of refractive index improvers are used) can be appropriately set according to the purpose. From the viewpoint of increasing the refractive index of the adhesive, the amount of refractive index improver used per 100 parts by weight of base polymer can be, for example, 1 part by weight or more, 3 parts by weight or more is advantageous, 5 parts by weight or more is preferable, 7 parts by weight or more is also acceptable, 10 parts by weight or more is also acceptable, 15 parts by weight or more is also acceptable, and 20 parts by weight or more is also acceptable. Furthermore, in some embodiments, the amount of refractive index improver used per 100 parts by weight of base polymer can be, for example, 80 parts by weight or less, and from the viewpoint of achieving a good balance between increasing the refractive index of the adhesive and suppressing the deterioration of adhesive properties and optical properties, it is advantageous to set it to 60 parts by weight or less, and it is preferable to set it to 45 parts by weight or less. In some embodiments where greater emphasis is placed on adhesive properties and optical properties, the amount of refractive index improver used per 100 parts by weight of the base polymer may be, for example, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 3 parts by weight or less. Embodiments of the present invention may be implemented with an amount of refractive index improver of less than 1 part by weight per 100 parts by weight of the base polymer in the adhesive layer, or even without substantially using any refractive index improver. Here, substantially not using means at least not using it intentionally.

[0087] (additives (H RO )) In some embodiments, an organic material with a higher refractive index than the base polymer may be preferably used as the refractive index improver. Hereinafter, such an organic material will be referred to as an additive (H RO It is sometimes written as "H RO " indicates that it is an organic material with a high refractive index. It consists of a base polymer (e.g., an acrylic polymer, preferably an acrylic polymer (A)) and an additive (H ROBy using a combination of ), an adhesive can be realized that more favorably balances refractive index and adhesive properties (peel strength, flexibility, etc.) and / or optical properties (total light transmittance, haze value, etc.). Additive (H RO The organic material used as an additive (H) may be a polymer or a nonpolymer. It may also have polymerizable functional groups or not. RO ) may be used alone, or two or more types may be used in combination.

[0088] Additives (H RO The refractive index of ) can be measured, like that of the monomer, using, for example, an Abbe refractometer, under conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. If the manufacturer or other source provides a nominal refractive index value at 25°C, that nominal value can be used.

[0089] Additives (H RO The molecular weight of the organic material used as an additive (H) can be appropriately selected depending on the purpose. RO The molecular weight of the additive (H) can be selected from a range of, for example, 30,000 or less. RO The additive (H) is preferably a polymer or nonpolymer with a lower molecular weight than the base polymer. From the viewpoint of achieving a good balance between the effect of increasing the refractive index and other properties (e.g., flexibility suitable for adhesives, optical properties such as haze), in some embodiments, the additive (H) RO The molecular weight of the additive (H) is preferably less than 10,000, more preferably less than 5,000, more preferably less than 3,000 (e.g., less than 1,000), and may also be less than 800, less than 600, less than 500, or less than 400. RO The fact that the molecular weight of the additive (H) is not too large can be advantageous from the viewpoint of improving compatibility within the adhesive layer. RO The molecular weight of the additive (H) may be, for example, 130 or more, or 150 or more. In some embodiments, the additive (H) RO The molecular weight of the additive (H ROFrom the viewpoint of increasing the refractive index of ), it is preferably 170 or higher, more preferably 200 or higher, and may also be 230 or higher, 250 or higher, 270 or higher, 500 or higher, 1000 or higher, and 2000 or higher. In some embodiments, a polymer with a molecular weight of about 1000 to 10000 (for example, 1000 or more and less than 5000) is used as an additive (H RO It can be used as ). Additives (H RO For nonpolymers or polymers with a low degree of polymerization (e.g., 2-5 mers), the molecular weight can be calculated based on the chemical structure, or measured using matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF-MS). RO If the polymer has a higher degree of polymerization, the weight-average molecular weight (Mw) based on GPC performed under appropriate conditions can be used. If the manufacturer provides a nominal molecular weight, that nominal value can be used.

[0090] Additives (H RO Examples of organic materials that could be options for this include organic compounds having an aromatic ring and organic compounds having a heterocycle (which may be an aromatic ring or a non-aromatic heterocycle).

[0091] Additives (H RO The aromatic ring of an organic compound having an aromatic ring used as a monomer (hereinafter also referred to as an "aromatic ring-containing compound") can be selected from those similar to the aromatic ring of the compound used as a monomer (m1).

[0092] The aromatic ring may have one or more substituents on its ring constituent atoms, or it may not have substituents. If substituents are present, examples of substituents include alkyl groups, alkoxy groups, aryloxy groups, hydroxyl groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, etc.), hydroxyalkyl groups, hydroxyalkyloxy groups, glycidyloxy groups, etc. In substituents containing carbon atoms, the number of carbon atoms in the substituent is, for example, 1 to 10, advantageously 1 to 6, preferably 1 to 4, more preferably 1 to 3, and may be, for example, 1 or 2. In some embodiments, the aromatic ring may have no substituents on its ring constituent atoms, or it may be an aromatic ring having one or more substituents selected from the group consisting of alkyl groups, alkoxy groups, and halogen atoms (e.g., bromine atoms).

[0093] Additives (H RO Examples of aromatic ring-containing compounds that can be used as additives include: compounds that can be used as monomers (m1); oligomers containing compounds that can be used as monomers (m1) as monomer units; and compounds obtained by replacing a compound that can be used as monomer (m1) with a group having an ethylenically unsaturated group (which may be a substituent bonded to a ring constituent atom) or a group that does not have a hydrogen atom or an ethylenically unsaturated group (for example, a hydroxyl group, an amino group, a halogen atom, an alkyl group, an alkoxy group, a hydroxyalkyl group, a hydroxyalkyloxy group, a glycidyloxy group, etc.). RONon-limiting specific examples of aromatic ring-containing compounds that can be used as ) include aromatic ring-containing monomers such as benzyl acrylate, m-phenoxybenzyl acrylate, 2-(o-phenylphenoxy)ethyl acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, monomers having the fluorene structure described above, monomers having a dinaphthothiophene structure, and monomers having a dibenzothiophene structure; and aromatic ring-containing compounds that do not have an ethylenically unsaturated group, such as 3-phenoxybenzyl alcohol, dinaphthothiophene and its derivatives (for example, compounds in which one or more substituents selected from a hydroxyl group, methanol group, diethanol group, glycidyl group, etc. are bonded to the dinaphthothiophene ring, one or more of which are 1 or more of which are bonded). Furthermore, the aromatic ring-containing compound may be an oligomer containing such aromatic ring-containing monomers as monomer units (preferably an oligomer with a molecular weight of about 5000 or less, more preferably about 1000 or less; for example, a low polymer of about 2 to 5 units). The oligomer may be, for example: a homopolymer of aromatic ring-containing monomers; a copolymer of one or more aromatic ring-containing monomers; a copolymer of one or more aromatic ring-containing monomers and other monomers; etc. As the other monomers, one or more monomers without aromatic rings may be used.

[0094] In some embodiments, additive (H ROAs such, organic compounds having two or more aromatic rings in one molecule (hereinafter also referred to as "aromatic ring-containing compounds") can be preferably used because they easily provide a high refractive index effect. Aromatic ring-containing compounds may or may not have polymerizable functional groups such as ethylenically unsaturated groups. Furthermore, aromatic ring-containing compounds may be polymers or nonpolymers. The polymer may be an oligomer containing aromatic ring-containing monomers as monomer units (preferably an oligomer with a molecular weight of about 5000 or less, more preferably about 1000 or less; for example, a low polymer of about 2 to 5-mers). The oligomer may be, for example: a homopolymer of aromatic ring-containing monomers; a copolymer of one or more aromatic ring-containing monomers; or a copolymer of one or more aromatic ring-containing monomers and other monomers. The other monomers may be aromatic ring-containing monomers that do not fall under the category of aromatic ring-containing monomers, monomers that do not have aromatic rings, or combinations thereof.

[0095] Non-limiting examples of compounds containing multiple aromatic rings include compounds having a structure in which two or more non-condensed aromatic rings are linked via linking groups, compounds having a structure in which two or more non-condensed aromatic rings are chemically bonded directly (i.e., without the involvement of other atoms), compounds having a condensed aromatic ring structure, compounds having a fluorene structure, compounds having a dinaphthothiophene structure, and compounds having a dibenzothiophene structure. Compounds containing multiple aromatic rings may be used individually or in combination of two or more types.

[0096] Specific examples of compounds having a fluorene structure include the monomers having a fluorene structure as described above, as well as oligomers which are homopolymers or copolymers of such monomers, and 9,9-bisphenylfluorene and its derivatives, such as 9,9-bis(4-hydroxyphenyl)fluorene (refractive index: 1.68), 9,9-bis(4-aminophenyl)fluorene (refractive index: 1.73), 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (refractive index: 1.68), and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (refractive index: 1.65).

[0097] Specific examples of compounds having a dinaphthothiophene structure include monomers having the dinaphthothiophene structure as described above, oligomers which are homopolymers or copolymers of such monomers, as well as hydroxyalkyl dinaphthothiophenes such as dinaphthothiophene (refractive index: 1.808); 6-hydroxymethyl dinaphthothiophene (refractive index: 1.766); dihydroxydinaphthothiophenes such as 2,12-dihydroxydinaphthothiophene (refractive index: 1.750); and 2,12-di Examples of dinaphthothiophenes and their derivatives include dihydroxyalkyl oxydinaphthothiophenes such as hydroxyethyloxydinaphthothiophene (refractive index: 1.677); diglycidyloxydinaphthothiophenes such as 2,12-diglycidyloxydinaphthothiophene (refractive index: 1.723); and dinaphthothiophenes having two or more ethylenically unsaturated groups, such as 2,12-diallyloxydinaphthothiophene (abbreviation: 2,12-DAODNT, refractive index: 1.729).

[0098] Specific examples of compounds having a dibenzothiophene structure include the monomers having the dibenzothiophene structure described above, as well as oligomers which are homopolymers or copolymers of such monomers, and dibenzothiophene (refractive index: 1.607), 4-dimethyldibenzothiophene (refractive index: 1.617), and 4,6-dimethyldibenzothiophene (refractive index: 1.617).

[0099] Additives (H ROExamples of heterocyclic organic compounds (hereinafter also referred to as heterocyclic organic compounds) that can be options include thioepoxy compounds and compounds having triazine rings. An example of a thioepoxy compound is bis(2,3-epithiopropyl) disulfide and its polymer (refractive index 1.74) described in Japanese Patent Publication No. 3712653. An example of a triazine ring compound is a compound having at least one triazine ring (for example, 3 to 40, preferably 5 to 20) in one molecule. Since triazine rings are aromatic, compounds having triazine rings are also included in the above-mentioned aromatic ring-containing compounds, and compounds having multiple triazine rings are also included in the above-mentioned aromatic ring-multiple-containing compounds.

[0100] In some embodiments, additive (H RO As the additive (H), compounds that do not have ethylenically unsaturated groups can be preferably used. This suppresses deterioration of the adhesive composition due to heat and light (progression of gelation and decrease in leveling properties due to increased viscosity), and improves storage stability. Additives that do not have ethylenically unsaturated groups (H RO ) adopting the additive (H RO Adhesive sheets having an adhesive layer containing ) and laminates containing said adhesive sheets are preferable from the viewpoint of suppressing dimensional changes and deformations (warping, undulation, etc.) and the occurrence of optical distortion caused by the reaction of ethylenically unsaturated groups.

[0101] Acrylic adhesive compositions may preferably contain a silane coupling agent and / or a crosslinking agent. Examples of silane coupling agents include epoxy group-containing silane coupling agents. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Furthermore, acrylic adhesive compositions may contain additives. Specific examples of additives include antioxidants, conductive agents, colorants, pigments and other powders, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulate matter, and foil-like materials. In addition, a redox system with a reducing agent may be used within a controllable range. The type, number, combination, and content of silane coupling agents, crosslinking agents, and / or additives can be appropriately set according to the purpose.

[0102] D-3. Adhesive Adhesives can also employ any suitable configuration as long as they satisfy the above-mentioned properties. Typically, adhesives (adhesive compositions) may contain (meth)acrylates containing an aromatic ring skeleton and metal oxide particles. Each of these can be briefly described below. Note that other components that may be included in the adhesive (e.g., curing components, adhesives) can be of well-known composition, so specific explanations will be omitted.

[0103] In the embodiments of the present invention, an adhesive layer having a desired refractive index can be formed by the adhesive composition containing a (meth)acrylate having an aromatic ring skeleton. It is preferable to use a (meth)acrylate having an aromatic ring skeleton that contains at least one selected from the group consisting of (meth)acrylates having a polycyclic aromatic ring skeleton and (meth)acrylates having two or more aromatic rings. Examples of such (meth)acrylates include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 1-naphthalenemethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, ethylene oxide-modified orthophenylphenol (meth)acrylate, and a reaction product of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene and (meth)acrylic acid. Among these, the use of phenoxybenzyl (meth)acrylate and phenoxyethyl (meth)acrylate is more preferred, and the use of phenoxybenzyl (meth)acrylate is particularly preferred. The amount of (meth)acrylate having an aromatic ring skeleton is preferably 20% to 90% by mass, and more preferably 30% to 80% by mass, when the total amount of the adhesive composition is 100% by mass.

[0104] Examples of metal oxide particles include silicon oxide, zirconium oxide, titanium oxide, zinc oxide, antimony pentoxide, tin oxide, aluminum oxide, indium oxide, indium tin oxide, ferric oxide, cerium oxide, yttrium oxide, manganese oxide, holomium oxide, copper oxide, bismuth oxide, cobalt oxide, cobalt trioxide, iron trioxide, magnesium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, eurobium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, tantalum pentoxide, niobium pentoxide, iridium oxide, rhodium oxide, ruthenium oxide, and composite oxides formed by combining these. Among these, zirconium oxide and titanium oxide are preferred, with zirconium oxide being particularly preferred. The metal oxide particles may consist solely of the metal oxides listed above, or they may contain other components, but it is preferable that metal oxides constitute the largest weight component of the particles. The shape of the metal oxide particles can be any shape, such as spherical, ellipsoidal, cuboidal, rectangular prism, or pyramidal. Furthermore, metal oxide particles that have been surface-treated by any appropriate method may be used.

[0105] From the viewpoint of improving the stability of metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer, the average particle diameter of the metal oxide particles is preferably 1 nm to 150 nm, and more preferably 1 nm to 50 nm. The average particle diameter of the metal oxide particles can be derived, for example, by the following method: the particles are observed under magnification using a transmission electron microscope (TEM), field emission transmission electron microscope (FE-TEM), and field emission scanning electron microscope (FE-SEM), for example, 1000 particles are randomly selected, their maximum lengths are measured, and the arithmetic mean is calculated.

[0106] From the viewpoint of improving the stability of metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer, the amount of metal oxide particles blended is preferably 10% to 50% by mass, and more preferably 15% to 40% by mass, when the total amount of the adhesive composition is 100% by mass.

[0107] The adhesive composition may further contain hydroxyl group-containing (meth)acrylate. With such a configuration, the adhesive strength of the adhesive layer can be further improved. The amount of hydroxyl group-containing (meth)acrylate is preferably 1% to 30% by mass, and more preferably 3% to 20% by mass, when the total amount of the adhesive composition is 100% by mass.

[0108] E. Image display device The optical laminates described in sections A to D above can be applied to image display devices. Therefore, embodiments of the present invention also include image display devices using such optical laminates. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the optical laminate described in sections A to D above on its viewing side. [Examples]

[0109] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are based on weight.

[0110] (1) Refractive index (1-1) Adhesive layer The adhesive layers formed in the examples and comparative examples were measured using an Abbe refractometer (ATAGO, product name "DR-M2 / 1550"). The measurement wavelength was 589 nm and the measurement temperature was 25°C. (1-2) Adhesive layer and liquid crystal alignment solidification layer The adhesives used in the examples and comparative examples were applied to a cycloolefin polymer film (COP film) (thickness: 100 μm), and the same COP film was laminated on the coated surface. Then, visible light was irradiated using an active energy ray irradiation device to obtain a cured product layer (single film). For the obtained cured product layer, the in-plane refractive index and the refractive index in the thickness direction were measured using a prism coupler (manufactured by Sirion Technologies, product name "SPA-4000"), and the average value of these was taken as the average refractive index of the adhesive layer. The measurement wavelength was 594 nm, and the measurement temperature was 23°C. Furthermore, for the liquid crystal alignment cured layer, the refractive index in the transmission axis direction was determined as follows. The in-plane retardation Re(550) and the retardation in the thickness direction Rth(550) were measured using Axoscan (manufactured by Axometrics). nx, ny, and nz were calculated from the following simultaneous equations. Re(550)=(nx - ny)×d Nz = Rth(550) / Re(550)=(nx - nz) / (nx - ny) Furthermore, in the equation of the ellipse (x 2 / a 2 )+(y 2 / b 2 ) = 1, a was taken as nx, b was taken as ny, x and y were taken as the refractive indices in the x direction and y direction at an angle θ on the ellipse, and a simultaneous equation was solved from y = tanθ and the above nx and ny to calculate the refractive index in the slow axis direction.

[0111] (2) Thickness It was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., "MCPD9800").

[0112] (3) Thickness variation Regarding the laminate of the first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer in the optical laminate obtained in the examples and comparative examples, thickness mapping measurement was performed at a 1 mm pitch in a range of 10 cm × 10 cm using "USB4H09646" manufactured by Ocean Optics. The thickness difference at the location where the difference in thickness between three adjacent points was the largest was taken as the thickness variation.

[0113] (4) Linear unevenness A standard acrylic adhesive was placed on the second liquid crystal alignment solidification layer side of the optical laminates obtained in the examples and comparative examples, and the laminates were bonded to a V3 reflector (manufactured by NEODIS) via the acrylic adhesive to obtain test samples. The obtained test samples were observed visually under a three-wavelength fluorescent lamp and evaluated according to the following criteria. 1: No linear irregularities were observed. 2: Slight linear unevenness was observed. 3: Linear irregularities were observed, but they were at a level that was practically acceptable. 4: Linear irregularities were observed to an extent that is practically unacceptable. 5: Linear unevenness was prominent.

[0114] [Manufacturing Example 1: Preparation of Adhesive 1 for Laminating Polarizing Plate and Phase Difference Layer] 10 parts of hydroxyethyl acrylamide (product name "HEAA", manufactured by KJ Chemicals), 4 parts of 2-acetoacetoxyethyl methacrylate (product name "AAEM", manufactured by Mitsubishi Chemicals), 60 parts of acryloylmorpholine (product name "ACMO", manufactured by KJ Chemicals), 11 parts of tripropylene glycol diacrylate (product name "Aronics M-220", 1 part of 4-vinylphenylboronic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), manufactured by Toagosei Co., Ltd.), 10 parts of acrylic oligomer (product name "ARUFON UP-1190", manufactured by Toagosei Co., Ltd.), 1 part of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819", manufactured by IGM Resins BV), 1 part of 1-hydroxycyclohexyl phenyl ketone (product name "Omnirad 184", manufactured by IGM Resins Two parts of BV Co., Ltd. and one part of diethylthioxanthone (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) were stirred at 50°C for 1 hour to prepare adhesive 1.

[0115] [Manufacturing Example 2: Preparation of Adhesive A1 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] A monomer mixture containing 91 parts butyl acrylate, 6 parts acryloyl morpholine, 2.7 parts acrylic acid, and 0.3 parts 4-hydroxybutyl acrylate was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts 2,2'-azobisisobutyronitrile was added to 100 parts of this monomer mixture as a polymerization initiator along with 100 parts ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 8 hours while maintaining the temperature of the liquid in the flask at around 55°C to prepare a solution of acrylic polymer A1 with a weight-average molecular weight (Mw) of 2.7 million. Adhesive A1 was prepared by blending 0.1 parts of an isocyanate crosslinking agent (trimethylolpropane / tolylene diisocyanate adduct: manufactured by Tosoh Corporation, trade name "Coronate L"), 0.3 parts of a peroxide crosslinking agent (benzoyl peroxide: manufactured by Nippon Oil & Fats Co., Ltd., trade name "Nipper BMT"), and 0.2 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") with 100 parts of the solid content of an acrylic polymer A1 solution. The polymer concentration of adhesive A1 was adjusted to 5%.

[0116] [Manufacturing Example 3: Preparation of Adhesive A2 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] Adhesive A2 was obtained in the same manner as in Manufacturing Example 2, except that the polymer concentration was adjusted to 6%.

[0117] [Manufacturing Example 4: Preparation of Adhesive A3 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] Adhesive A3 was obtained in the same manner as in Manufacturing Example 2, except that the polymer concentration was adjusted to 7%.

[0118] [Manufacturing Example 5: Preparation of Adhesive A4 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] Adhesive A4 was obtained in the same manner as in Manufacturing Example 2, except that the polymer concentration was adjusted to 8%.

[0119] [Manufacturing Example 6: Preparation of Adhesive B for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] A monomer mixture containing 94.9 parts butyl acrylate, 5 parts acrylic acid, and 0.1 parts 2-hydroxyethyl acrylate was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts 2,2'-azobisisobutyronitrile was added to 100 parts of this monomer mixture as a polymerization initiator along with 100 parts ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 8 hours while maintaining the temperature of the liquid in the flask at around 55°C to prepare a solution of acrylic polymer B with a weight-average molecular weight (Mw) of 2.2 million. Adhesive B was obtained by blending 0.6 parts of an isocyanate crosslinking agent (trimethylolpropane / tolylene diisocyanate adduct: manufactured by Tosoh Corporation, trade name "Coronate L"), 0.2 parts of a peroxide crosslinking agent (benzoyl peroxide: manufactured by Nippon Oil & Fats Co., Ltd., trade name "Nipper BMT"), and 0.2 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") with 100 parts of the solid content of acrylic polymer B solution.

[0120] [Manufacturing Example 7: Preparation of Adhesive C1 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] A monomer mixture containing 19 parts butyl acrylate, 80 parts benzyl acrylate, and 1 part 4-hydroxybutyl acrylate was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts 2,2'-azobisisobutyronitrile was added to 100 parts of this monomer mixture as a polymerization initiator along with 100 parts ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 6 hours while maintaining the temperature of the liquid in the flask at around 60°C to prepare a solution of acrylic polymer C1 with a weight-average molecular weight (Mw) of 1.9 million. Adhesive C1 was obtained by blending 0.1 parts of an isocyanate crosslinking agent (trimethylolpropane / tolylene diisocyanate adduct: manufactured by Mitsui Chemicals, trade name "D101E") and 0.3 parts of a peroxide crosslinking agent (benzoyl peroxide: manufactured by Nippon Oil & Fats Co., Ltd., trade name "Nipper BMT") with 100 parts of the solid content of an acrylic polymer C1 solution.

[0121] [Manufacturing Example 8: Preparation of Adhesive C2 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] A solution of acrylic polymer C2 with a weight-average molecular weight (Mw) of 650,000 was prepared in the same manner as in Production Example 7, except that a monomer mixture containing 30 parts butyl acrylate, 69 parts m-phenoxybenzyl acrylate, and 1 part 4-hydroxybutyl acrylate was used. Adhesive C2 was obtained in the same manner as in Production Example 7, except that acrylic polymer C2 was used.

[0122] [Manufacturing Example 9: Preparation of Adhesive C3 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] A solution of acrylic polymer C3 with a weight-average molecular weight (Mw) of 650,000 was prepared in the same manner as in Production Example 7, except that a monomer mixture containing 19 parts butyl acrylate, 80 parts m-phenoxybenzyl acrylate, and 1 part 4-hydroxybutyl acrylate was used. Adhesive C3 was obtained in the same manner as in Production Example 7, except that acrylic polymer C3 was used.

[0123] [Manufacturing Example 10: Preparation of Adhesive C4 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] A solution of acrylic polymer C4 with a weight-average molecular weight (Mw) of 650,000 was prepared in the same manner as in Production Example 7, except that a monomer mixture containing 6 parts butyl acrylate, 93 parts m-phenoxybenzyl acrylate, and 1 part 4-hydroxybutyl acrylate was used. Adhesive C4 was obtained in the same manner as in Production Example 7, except that acrylic polymer C4 was used.

[0124] [Manufacturing Example 11: Preparation of Adhesive C5 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] To 100 parts of the solids content of the acrylic polymer C4 from Production Example 10, 0.1 parts of an isocyanate crosslinking agent (trimethylolpropane / tolylene diisocyanate adduct: manufactured by Mitsui Chemicals, trade name "D101E"), 0.3 parts of a peroxide crosslinking agent (benzoyl peroxide: manufactured by Nippon Oil & Fats Co., Ltd., trade name "Nipper BMT"), and 10 parts of a refractive index improver (6-acryloyloxymethyldinaphthothiophene: manufactured by Sugai Chemical Industry Co., Ltd., trade name "6MDNTA") were added to obtain adhesive C5.

[0125] [Manufacturing Example 12: Preparation of Adhesive D1 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] (Preparation of dispersant) 415 g (1 mol) of tristyrenated phenol and 1 g (0.018 mol) of potassium hydroxide were charged into an autoclave and mixed uniformly. Under conditions of 130°C, 352 g (8 mol) of ethylene oxide (EO) was added dropwise to the reaction system. After the addition of ethylene oxide was complete, the system was aged for 1 hour at 130°C while maintaining a pressure of 0.1 MPa to obtain an 8-mol EO adduct of tristyrenated phenol. 767 g (1 mol) of the obtained 8-mol EO adduct of tristyrenated phenol and 152 g (1.3 mol) of sodium monochloroacetate were placed in a reactor and stirred until homogenized. Next, under conditions of 60°C, 52 g of sodium hydroxide was added, and the temperature was raised to 80°C and aged for 3 hours. After aging, the system was cooled to 50°C, and 117 g (1.2 mol) of 98% sulfuric acid was added dropwise at the same temperature to obtain a white suspension. This white suspension was washed with distilled water, and the solvent was removed under reduced pressure to obtain a dispersant. (Preparation of zirconia dispersion) To 100 parts of a methanol dispersion of zirconium oxide (manufactured by Sakai Chemical Industry Co., Ltd., grade name "SZR-CM", average particle size (D50) based on dynamic light scattering method: 8 nm, zirconium oxide solid content concentration: 30%), 1.5 parts of the dispersant obtained above and 28.5 parts of m-phenoxybenzyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate POB-A"; hereinafter referred to as "POB-A") were added and mixed. Next, the solvent was removed under reduced pressure using a rotary evaporator to obtain a zirconia dispersion, which is a monomer dispersion of zirconium oxide. This zirconia dispersion contains zirconium oxide / dispersant / POB-A in a weight ratio of 50 / 2.5 / 47.5. (Preparation of adhesive D1) Adhesive D1 was prepared by stirring 35 parts of zirconia dispersion, 40 parts of "POB-A", 10 parts of 4-hydroxybutyl acrylate, 10 parts of tripropylene glycol diacrylate (trade name "Aronics M-220", manufactured by Toagosei Co., Ltd.), 1 part of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad 819", manufactured by IGM Resins BV), 2 parts of 1-hydroxycyclohexyl phenyl ketone (trade name "Omnirad 184", manufactured by IGM Resins BV), and 2 parts of diethylthioxanthone (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) at 50°C for 1 hour.

[0126] [Manufacturing Example 13: Preparation of Adhesive D2 for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] Adhesive D2 was prepared by stirring 55 parts of zirconia dispersion, 25 parts of "POB-A", 10 parts of 4-hydroxybutyl acrylate, 10 parts of "Aronics M-220", 1 part of "Omnirad 819", 2 parts of "Omnirad 184", and 2 parts of "KAYACURE DETX-S" at 50°C for 1 hour.

[0127] [Manufacturing Example 14: Preparation of Adhesive E for Laminating the First Liquid Crystal Alignment Solidification Layer and the Second Liquid Crystal Alignment Solidification Layer] Adhesive E was prepared by stirring 60 parts of Ogusol EA-F5710 (manufactured by Osaka Gas Chemical Co., Ltd.), 10 parts of Praxel FA1DDM (manufactured by Daicel Corporation), 20 parts of acryloylmorpholine (trade name "ACMO", manufactured by KJ Chemicals Co., Ltd.), 5 parts of ARFON UP-1190 (manufactured by Toagosei Co., Ltd.), 1 part of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad 819", manufactured by IGM Resins BV Co., Ltd.), 2 parts of 1-hydroxycyclohexyl phenyl ketone (trade name "Omnirad 184", manufactured by IGM Resins BV Co., Ltd.), and 2 parts of diethylthioxanthone (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) at 50°C for 1 hour.

[0128] [Example 1] 1. Fabrication of polarizing plates 1-1. Fabrication of a polarizer As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and one side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a 13 μm thick PVA-based resin layer, thereby creating a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the polarizers were immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizers obtained would be the desired value (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the material was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on a resin substrate, and a polarizing plate having a resin substrate / polarizer configuration was obtained. The transmittance Ts of the polarizer alone was 43.3%.

[0129] 1-2. Fabrication of polarizing plates An HC-COP film was bonded to the surface of the obtained polarizer (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. The HC-COP film is a film in which an HC layer (4 μm thick) is formed on a cycloolefin resin (COP) film (25 μm thick), and it was bonded so that the COP film was on the polarizer side. The COP film had a Re(550) of 135 nm. Next, the resin substrate was peeled off, and a triacetylcellulose (TAC) film (25 μm thick) was bonded to the peeled surface via an ultraviolet-curing adhesive. In this way, a polarizer having the structure of HC layer / COP film (protective layer) / polarizer / TAC film (protective layer) was obtained.

[0130] 2. Fabrication of the phase difference layer A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF's "Paliocolor LC242," chemical formula below) was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by weight. A surfactant (BYK-361N, BYC-Chemie) and a photopolymerization initiator (Omnirad907, IGM Resins) were added to this solution to prepare a liquid crystal composition solution. The amounts of surfactant and polymerization initiator added were 0.01 parts by weight and 3 parts by weight, respectively, per 100 parts by weight of the photopolymerizable liquid crystal compound. A biaxially oriented norbornene film (Zeonor Film, 33 μm thick, Re(550) = 135 nm) was prepared as a substrate. The above liquid crystal composition was coated onto this substrate using a bar coater so that Re(550) was 240 nm, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the integrated light intensity was 400 mJ / cm² under a nitrogen atmosphere. 2 Photocuring was performed by irradiating with ultraviolet light to obtain a laminate having a substrate / first liquid crystal orientation solidified layer configuration. The first liquid crystal orientation solidified layer was homogeneously oriented and had a thickness of 1.7 μm. A laminate of substrate / second liquid crystal orientation solidified layer (homogeneously oriented, thickness 0.92 μm, Re(550)=130 nm) was obtained in the same manner as above, except that the coating thickness was changed. [ka]

[0131] 3. Fabrication of optical stacks After bonding a first liquid crystal alignment cured layer to the TAC film surface of a polarizing plate through the adhesive 1 (thickness: 1 μm) of Production Example 1, the substrate was peeled off. Next, a second liquid crystal alignment cured layer was bonded to the surface of the first liquid crystal alignment cured layer through the adhesive A3 (thickness: 5 μm) of Production Example 4, and the substrate was peeled off to obtain an optical laminate having a structure of polarizing plate / first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer. In the optical laminate, the angle formed by the transmission axis of the polarizer of the polarizing plate and the slow axis of the first liquid crystal alignment cured layer was 15°, and the angle formed by the transmission axis of the polarizer of the polarizing plate and the slow axis of the second liquid crystal alignment cured layer was 75°. The average refractive index of each of the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer was 1.59, and the refractive index n LC1 of the first liquid crystal alignment cured layer in the direction of the transmission axis of the polarizer was 1.66, and the refractive index n LC2 of the second liquid crystal alignment cured layer was 1.56. Further, the refractive index n AD of the adhesive layer was 1.47, and the thickness variation TV AD was 0.1 μm. As a result, the display unevenness parameter was 2.8. The obtained optical laminate was subjected to the above-described "linear unevenness" evaluation. The results are shown in Table 1. In Table 1, the "refractive index difference from the LC layer" means the difference between the average of the refractive index n LC1 of the first liquid crystal alignment cured layer and the refractive index n LC2 of the second liquid crystal alignment cured layer in the direction of the transmission axis of the polarizer and the refractive index n AD of the adhesive layer.

[0132] [Examples 2 to 11 and Comparative Examples 1 to 3] An optical laminate was obtained in the same manner as in Example 1 except that the configuration of the adhesive layer was changed as shown in Table 1. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0133]

Table 1

Industrial Applicability

[0134] The optical laminate according to the embodiment of the present invention can be suitably used in image display devices (typically liquid crystal display devices and organic EL display devices). [Explanation of Symbols]

[0135] 10 Polarizing plates 11 Polarizer 12 Protective layer 13 Protective layer 20 Retardation layer 21. First liquid crystal alignment solidification layer 22 Second liquid crystal alignment solidification layer 25 Adhesive layer 100 Optical laminate

Claims

1. It comprises a polarizing plate containing a polarizer and a phase difference layer, The phase difference layer includes, in order from the polarizing plate side, a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer laminated to the first liquid crystal alignment solidification layer via an adhesive layer. The adhesive layer is composed of an adhesive, The phase difference layer, as a whole, in combination with the polarizer, has a circular polarization function or an elliptical polarization function, and has the relationship Re(450) < Re(550) < Re(650), The refractive index n of the first liquid crystal alignment solidification layer ＬＣ１ , the refractive index n of the second liquid crystal alignment solidification layer ＬＣ２ , and the refractive index n of the adhesive layer ＡＤ , and the thickness T of the adhesive layer ＡＤ and thickness variation TV ＡＤ However, an optical laminate that satisfies the following equation (1): |{(n ＬＣ１ +n ＬＣ２ ) / 2-n ＡＤ }|×(TV ＡＤ / T ＡＤ )×1000≦3.0 ・・・(1) Here, the refractive indices of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer are, respectively, the refractive indices in the direction of the transmission axis of the polarizer.

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

3. The optical laminate according to claim 1, wherein the thickness of the first liquid crystal alignment solidification layer is 1.7 μm or less.

4. An image display device comprising an optical laminate according to any one of claims 1 to 3.

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