Optical laminates and image display devices

Abstract

To provide an optical laminate having through holes and capable of suppressing the occurrence of cracks in the phase difference layer even in high-temperature and high-humidity environments. [Solution] An optical laminate according to an embodiment of the present invention comprises a protective layer, a polarizer, and a phase difference layer in this order. The optical laminate has through holes. The fracture stress in the slow phase axis direction of the phase difference layer when the optical laminate is placed in an environment of 85°C and 85% humidity for 120 hours is σ b , and the internal stress of the optical stack in the slow axis direction σ i When this is the case, the relationship in equation (1) below is satisfied. σ i / σ b <1.15 ···(1)

Description

Technical Field

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

Background Art

[0002] In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) have been rapidly spreading. In general, for these image display devices, an optical laminate (for example, a polarizing plate with a retardation layer) in which a polarizing plate and a retardation layer are integrated is widely used for the purposes of optical compensation, external light reflection prevention, and the like.

[0003] With the diversification of the usage environments of image display devices, the optical laminate is also required to have durability in a high-temperature and high-humidity environment. Further, in order to be applied to an image display device, the optical laminate may be subjected to a special-shaped processing such as a through hole. When the optical laminate is subjected to a special-shaped processing, cracks may occur in the retardation layer in the vicinity of the special-shaped processed portion.

Prior Art Documents

Patent Documents

[0007] According to embodiments of the present invention, it is possible to realize an optical laminate having through holes and capable of suppressing the occurrence of cracks in the phase difference layer even in high temperature and high humidity environments, and an image display device equipped with this optical laminate. [Brief explanation of the drawing]

[0008] [Figure 1A] This is a schematic plan view of an optical laminate according to one embodiment of the present invention. [Figure 1B] Figure 1A is a schematic cross-sectional view of the optical laminate along line BB. [Figure 2A] This figure shows the simulation results of the internal stress distribution of the optical laminate in the slow phase axis direction of the phase difference layer in Example 1. [Figure 2B] This figure shows the simulation results of the internal stress distribution of the optical laminate in the slow phase axis direction of the phase difference layer in Comparative Example 1. [Modes for carrying out the invention]

[0009] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the embodiments in order to clarify the explanation, but these are merely examples and do not limit the interpretation of the present invention. In this specification, "A and / or B" means any one of "A", "B", or "A and B".

[0010] (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 retardation of the film measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation of the film measured with light of wavelength 550 nm at 23°C. Re(λ) can be obtained by the formula: Re = (nx - ny) × d, where d (nm) is the thickness of the film. (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction of the film measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction of the film measured with light of wavelength 550 nm at 23°C. Rth(λ) can be obtained by 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 the clockwise and counterclockwise directions. Therefore, for example, "45°" includes ±45°. (6) Substantially orthogonal or parallel The expression "substantially orthogonal" includes the case where the angle formed by two directions is 90° ± 5°, and the expression "substantially parallel" includes the case where the angle formed by two directions is 0° ± 5°.

[0011] A. Optical laminate The optical laminate according to an embodiment of the present invention includes a protective layer, a polarizer, and a retardation layer in this order. The optical laminate according to an embodiment of the present invention satisfies the following relationship of formula (1) when the breaking stress in the slow axis direction of the retardation layer is σ b , and the internal stress of the optical laminate in the slow axis direction is σi : σ i / σ b <1.15 ···(1) By having such a configuration, the occurrence of cracks in the phase difference layer can be suppressed even when an optical laminate with through holes is placed in a high-temperature, high-humidity environment.

[0012] Fracture stress σ b Internal stress σ i The ratio (σ i / σ b ) may preferably be 1.00 or less, more preferably 0.85 or less, even more preferably 0.60 or less, and particularly preferably 0.30 or less. i / σ b The lower limit could be, for example, 0.10.

[0013] In this specification, "breaking stress" refers to the stress at which a substance (material) breaks, as measured by a tensile test in accordance with JIS K7161:2014. b This value represents the fracture stress in the slow phase axis direction of the phase difference layer when the optical laminate is bonded to a glass plate via an adhesive layer and left standing for 120 hours in an environment of 85°C and 85% humidity. Specific details of the measurement method and conditions will be described in the Examples section below. In this specification, "internal stress σ i "The internal stress σ" is the stress acting on the optical laminate in the slow phase axis direction of the phase difference layer when the optical laminate is bonded to a glass plate via an adhesive layer and left standing for 120 hours in an environment of 85°C and 85% humidity, and is calculated based on simulations. i The deformation and tensile modulus of the optical laminate are measured under conditions of 85°C and 85% humidity, and these results are used to calculate the value through simulation. Details of the simulation method, measurement method, and measurement conditions will be described in the subsequent section on examples.

[0014] Internal stress σ of the optical laminate in the slow axis direction of the phase difference layer i This is the fracture stress σ in the slow phase axis direction of the phase difference layer. b As long as equation (1) is satisfied in relation to σ, any appropriate internal stress σ iThe optical laminate may have internal stress σ i For example, the internal stress σ of the optical laminate is 80 MPa or less. i The internal stress σ of the optical laminate is preferably 70 MPa or less, more preferably 60 MPa or less, even more preferably 25 MPa or less, and particularly preferably 10 MPa or less. i The lower limit may be, for example, 5 MPa. Within this range, the effect of the optical laminate according to the embodiment of the present invention becomes more pronounced.

[0015] Fracture stress σ in the slow phase axis direction of the phase difference layer b This refers to the internal stress σ of the optical laminate in the slow axis direction of the phase difference layer. i As long as equation (1) is satisfied in relation to σ, any appropriate fracture stress σ b It may have the fracture stress σ of the above phase difference layer. b The pressure is, for example, 30 MPa or more, preferably 40 MPa or more, more preferably 50 MPa or more, even more preferably 60 MPa or more, and particularly preferably 70 MPa or more. The fracture stress σ in the direction of the slow axis of the phase difference layer. b The upper limit may be, for example, 150 MPa. Within this range, the effect of the optical laminate according to the embodiment of the present invention becomes more pronounced.

[0016] Figure 1A is a schematic plan view of an optical laminate according to one embodiment of the present invention, and Figure 1B is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 100 has a polarizing plate 10 and a phase difference layer 20 in that order. The polarizing plate 10 has a polarizer 11 and a protective layer 12 positioned on the opposite side of the polarizer 11 from the side where the phase difference layer 20 is located. The polarizer 11 and the protective layer 12 are typically bonded together via an adhesive layer (not shown). Note that the optical laminate according to the embodiment of the present invention is not limited to the configuration shown in Figures 1A and 1B. Specifically, the polarizing plate 10 may have a protective layer (sometimes referred to as an inner protective layer; not shown) separate from the protective layer 12.

[0017] In one embodiment, the optical laminate 100 further comprises a hard coat layer 13 on the side of the protective layer 12 opposite to the polarizer 11. The hard coat layer 13 may typically be located on the outermost layer on the viewing side of the optical laminate.

[0018] The polarizing plate 10 and the phase difference layer 20 are typically bonded together via an adhesive layer (not shown). The phase difference layer 20, when combined with the polarizing plate 10, can typically have a circular polarization function or an elliptic polarization function. In one embodiment, the optical laminate 100 may further include a reinforcing layer 21 on at least one surface of the phase difference layer 20. The reinforcing layer 21 is a layer that reinforces the phase difference layer. The reinforcing layer may preferably be a hard coat layer.

[0019] The optical laminate 100 has through holes 40, as shown in Figures 1A and 1B. As mentioned above, Figure 1A is a schematic plan view of the optical laminate 100. Figure 1B is a schematic cross-sectional view of the optical laminate 100 along line BB. The through holes can be formed at any position. Any suitable shape can be adopted for the through holes. The preferred position, shape, and formation method of the through holes will be described in detail in Section F.

[0020] The reason why the optical laminate according to the above embodiment of the present invention exhibits the above remarkable effects is not entirely clear, but the following mechanism can be inferred. However, this mechanism is merely a conjecture and does not limit the present invention, nor does it restrict the present invention by this mechanism.

[0021] When optical laminates and image display devices using optical laminates are placed in a high-temperature, high-humidity environment (e.g., 85°C and 85% humidity), layers made of resin material in the optical laminate (e.g., protective layer, polarizer, phase difference layer, etc.) may shrink and / or expand due to heating and humidification. Furthermore, when optical laminates are applied to image display devices, the phase difference layer is typically bonded to the image display panel of the image display device via an adhesive layer. Since the phase difference layer can be firmly fixed by the adhesive layer, when placed in a high-temperature, high-humidity environment, a force acts to cause thermal contraction inward in the in-plane direction. As a result, stress (internal stress such as tensile stress) may be generated as a counteracting force. Moreover, near the through-holes of optical laminates having through-holes, the phase difference layer is more prone to shrinkage due to the effects of heat in the slow phase axis direction, which corresponds to its stretching direction, while cracks such as fissures are more likely to occur in the fast phase axis direction, which is perpendicular to the slow phase axis near the through-holes of the phase difference layer. Furthermore, due to the effects of moisture caused by high humidity, moisture can easily penetrate from the edges of the processed area. This penetration of moisture can relax the orientation of molecules in the phase difference layer, making it easier for cracks to form near the edges of the processed area. In contrast, in the embodiment of the present invention, in an optical laminate having through holes, the fracture stress σ in the slow phase axis direction of the phase difference layer b and the internal stress σ in the slow phase axis direction of the optical stack i By ensuring that the relationship in equation (1) above is satisfied, the influence of stress in the slow phase axis direction near the through-hole can be mitigated. As a result, it is inferred that, according to the optical laminate according to the embodiment of the present invention, cracks in the fast phase axis direction near the through-hole of the phase difference layer can be suppressed.

[0022] An optical laminate typically has a rectangular shape in plan view, with a pair of opposing long sides and a pair of opposing short sides. In an optical laminate according to an embodiment of the present invention, the long sides of the rectangle and the slow axis of the phase difference layer are substantially orthogonal or parallel, and the long sides of the rectangle and the absorption axis of the polarizer intersect without being substantially orthogonal. "Intersect without being substantially orthogonal" means that the angle between the two directions is neither substantially orthogonal nor substantially parallel. More specifically, the expression "intersect without being substantially orthogonal" includes cases where the angle between the two directions is greater than 3° and less than 87°, and greater than 93° and less than 177°, preferably 5° or more and 85° or less, or 95° or more and 175° or less. In one embodiment, the longer side of the rectangle and the slow axis of the phase difference layer are substantially parallel, and the angle between the longer side of the rectangle and the absorption axis of the polarizer may be 40° or more and 50° or less, preferably 42° or more and 48° or less, and more preferably 43° or more and 46° or less. Also, when the longer side of the rectangle and the slow axis of the phase difference layer are substantially parallel, the angle may be 130° or more and 140° or less, preferably 132° or more and 138° or less, and more preferably 133° or more and 137° or less. With such a configuration, the effects of the embodiment of the present invention can be particularly pronounced. In another embodiment, the longer side of the rectangle and the slow axis of the phase difference layer are substantially orthogonal, and the angle between the longer side of the rectangle and the absorption axis of the polarizer may be 40° or more and 50° or less, preferably 42° or more and 48° or less, and more preferably 43° or more and 46° or less. Also, when the longer side of the rectangle and the slow axis of the phase difference layer are substantially orthogonal, the angle may be 130° or more and 140° or less, preferably 132° or more and 138° or less, and more preferably 133° or more and 137° or less. With such a configuration, the effects of the embodiment of the present invention can be more clearly expressed.

[0023] The optical laminate may be in the form of a single sheet or a long sheet. In this specification, "long sheet" means an elongated shape in which the length is sufficiently longer than the width, and for example, includes an elongated shape in which the length is 10 times or more, preferably 20 times or more, than the width. The long sheet optical laminate can be wound into a roll. The long sheet optical laminate can be manufactured, for example, by a so-called roll-to-roll process. The single sheet optical laminate may be manufactured by cutting the long sheet optical laminate to a predetermined size (typically a size corresponding to an image display device), or by bonding together each component (each layer) that has been cut to the predetermined size.

[0024] In practical terms, the optical laminate 100 has an adhesive layer 30 as shown in the illustrated example and can be attached to image display panels such as organic EL panels and liquid crystal panels. A release liner (not shown) may be temporarily attached to the surface of the optical laminate 100 on the side with the adhesive layer 30. The release liner can protect the adhesive layer 30 until the optical laminate 100 is put into use. The presence of a release liner allows the long optical laminate to be easily wound into a roll.

[0025] The following describes the components of the optical laminate. 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.

[0026] 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.

[0027] 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).

[0028] 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.

[0029] 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 using such a thin polarizer, it is possible to significantly reduce the thickness of the optical laminate. Furthermore, if the thickness of the polarizer is within the above range, curling during heating can be suppressed well, and good appearance durability during heating can be obtained.

[0030] Polarizers can be manufactured by any suitable method. For example, the resin film forming the polarizer may be a single layer of resin film or a laminate of two or more layers.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] B-2.Protective layer The protective layer may be formed from any suitable resin film that can be used, for example, as a protective layer for a polarizer. Specific examples of resins that are the main components of the resin film include cellulosic resins such as triacetylcellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, cycloolefin resins (COP) such as polynorbornene, polyolefin resins, (meth)acrylic resins, acetate resins, and the like. From the viewpoint of moisture permeability, the protective layer may preferably be a TAC film, a polycarbonate resin film, or a COP resin film.

[0035] The moisture permeability of the protective layer is preferably 1100 g / m². 2 It may be less than 24 hours. If the protective layer is a cellulose resin film, the moisture permeability of the protective layer is preferably 1050 g / m². 2 • 24 hours or less, more preferably 500 g / m² 2 It may be less than 24 hours. If the protective layer is a polycarbonate resin film, the moisture permeability of the protective layer is preferably 300 g / m². 2 • 24 hours or less, more preferably 200 g / m² 2 It may be less than 24 hours. If the protective layer is a cycloolefin resin film, the moisture permeability of the protective layer is preferably 100 g / m². 2 • Less than 24 hours, more preferably 50 g / m² 2It may be less than 24 hours. When the moisture permeability of the protective layer is within this range, the penetration of moisture into the entire optical laminate, including the phase difference layer, can be suppressed. As a result, shrinkage changes in the phase difference layer in the optical laminate can be particularly suppressed. This can particularly suppress the occurrence of cracks in the phase difference layer of optical laminates having through holes. The lower limit of the moisture permeability of the protective layer is, for example, 1 g / m 2 It can be 24hr. The moisture permeability is measured in accordance with JIS Z0208. The specific measurement method is described in the examples below.

[0036] The thickness of the protective layer is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm. If a surface treatment described later is applied (i.e., if a surface treatment layer is present), the thickness of the protective layer includes the thickness of the surface treatment layer.

[0037] In one embodiment, the protective layer 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.

[0038] The protective layer may be treated as needed to improve visibility when viewed through polarized sunglasses (typically by providing (elliptic) polarization or ultra-high phase difference). By applying such treatment, excellent visibility can be achieved even when viewing the display screen through polarized lenses such as polarized sunglasses. Therefore, optical laminates can be suitably applied to image display devices that may be used outdoors.

[0039] In the embodiment of the present invention, the optical laminate is typically positioned on the viewing side of an image display device, and the protective layer is positioned on the viewing side. Therefore, the protective layer may be subjected to surface treatments such as hard coat (HC) treatment, anti-reflective treatment, anti-sticking treatment, and anti-glare treatment, as needed.

[0040] B-3. ​​Hard coat layer An optical laminate according to one embodiment further comprises a hard coat layer. In the illustrated example, the optical laminate 100 comprises a hard coat layer 13, a protective layer 12, a polarizer 11, and a phase difference layer 20 in this order. The hard coat layer 13 may be provided on the side of the protective layer 12 opposite to the polarizer 11. Having a hard coat layer can reduce the moisture permeability of the polarizer (substantially the protective layer portion). Therefore, having a hard coat layer can suppress moisture transmission throughout the entire optical laminate. As a result, in an optical laminate having through holes, the effect of cracks near the through holes can be more effectively reduced.

[0041] A hard coat layer can typically be formed by coating the protective layer (substrate film) with a hard coat layer-forming material and curing the coating layer. That is, the hard coat layer can be, for example, a cured layer of any suitable hard coat layer-forming material. The hard coat layer-forming material typically includes a curable compound as a layer-forming component. Examples of curing mechanisms for curable compounds include thermosetting and photocuring. Examples of curable compounds include monomers, oligomers, and prepolymers. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. Examples of polyfunctional monomers or oligomers include acrylic resins such as monomers or oligomers having two or more (meth)acryloyl groups, urethane resins such as urethane (meth)acrylate or urethane (meth)acrylate oligomers, epoxy resins such as epoxy monomers or oligomers, and silicone resins such as silicone monomers or oligomers. The hard coat layer-forming material may also be, for example, a polyester resin or an amide resin.

[0042] A hard coat layer can be formed, for example, by applying a hard coat layer-forming composition to one side of a protective layer and performing a curing treatment. Examples of curing treatments include irradiation with active energy rays such as ultraviolet light, and heat treatment. If the curable compound is thermosetting, the heating temperature is, for example, 60°C to 140°C, preferably 60°C to 100°C. If the curable compound is photocurable, the curing treatment is typically performed by ultraviolet light irradiation. The integrated light intensity of the ultraviolet irradiation is, for example, 100 mJ / cm². 2 ~400 mJ / cm 2 This method may involve a combination of ultraviolet irradiation and heating. Furthermore, after forming the hard coat layer, surface treatments such as corona treatment or plasma treatment may be applied to the hard coat layer.

[0043] The hard coat layer forming material described above may contain any suitable additives. Examples of additives include polymerization initiators, leveling agents, blocking inhibitors, dispersion stabilizers, thixotropes, antioxidants, UV absorbers, defoamers, thickeners, dispersants, surfactants, catalysts, fillers, lubricants, and antistatic agents. The type, combination, and content of additives can be appropriately determined according to the purpose and desired properties.

[0044] The hard coat layer may be formed by applying a surface treatment to the protective layer. In this case, a portion of the protective layer may become the hard coat layer as a surface treatment layer. The surface treatment layer may be a part of the protective layer, and may differ in its functional aspects. Examples of surface treatments include hard coat treatment, anti-reflective treatment, anti-sticking treatment, and anti-glare treatment. Therefore, the surface treatment layer may include, for example, a hard coat layer, an anti-glare layer, an antistatic layer, an anti-reflective layer, etc. The surface treatment may also be a combination of hard coat treatment and other surface treatments.

[0045] The scratch hardness (pencil method) of the hard coat layer is, for example, F or higher, more preferably H or higher, and even more preferably 2H or higher. The scratch hardness can be measured in accordance with JIS K5600.

[0046] The thickness of the hard coat layer is, for example, 1 μm to 30 μm, preferably 3 μm to 15 μm, and more preferably 5 μm to 12 μm. Such a thickness can contribute well by lowering the moisture permeability of the protective layer. On the other hand, the thickness of the hard coat layer is preferably 7 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. Such a thickness can satisfy the above moisture permeability well, and for example, discoloration can be suppressed.

[0047] C. Retardation layer The phase difference layer may have any suitable optical and / or mechanical properties depending on the purpose. As described above, the phase difference layer is the internal stress σ of the optical laminate. i The fracture stress σ that satisfies equation (1) in relation to σ b It may have the following: That is, the fracture stress σ of the phase difference layer. b The appropriate fracture stress σ is given insofar as equation (1) is satisfied. b It may have the fracture stress σ of the phase difference layer. b For example, the pressure is 30 MPa or higher, preferably 40 MPa or higher, more preferably 50 MPa or higher, even more preferably 60 MPa or higher, and particularly preferably 70 MPa or higher.

[0048] As described above, the phase difference layer has a slow phase axis. In one embodiment, the phase difference layer is arranged in a rectangular optical laminate in plan view such that the angle it makes with the long side of the rectangle in the direction of the slow phase axis is an arbitrary appropriate angle. Specifically, in an optical laminate having a rectangular shape in plan view, in one embodiment, the long side of the rectangle and the slow phase axis of the phase difference layer may be substantially parallel. In this case, the angle between the long side of the rectangle and the absorption axis of the polarizer may be preferably 40° or more and 50° or less, more preferably 42° or more and 48° or less, and even more preferably 43° or more and 46° or less. Also, when the long side of the rectangle and the slow phase axis of the phase difference layer are substantially parallel, the angle between the long side of the rectangle and the absorption axis of the polarizer may be preferably 130° or more and 140° or less, more preferably 132° or more and 138° or less, and even more preferably 133° or more and 137° or less. Such a configuration can exhibit particularly excellent crack resistance.

[0049] In another embodiment, the long side of the rectangle and the slow axis of the retardation layer may be substantially orthogonal. In this case, the angle formed by the long side of the rectangle and the absorption axis of the polarizer may preferably be 40° or more and 50° or less, more preferably 42° or more and 48° or less, and even more preferably 43° or more and 46° or less. Further, when the long side of the rectangle and the slow axis of the retardation layer are substantially orthogonal, the angle formed by the long side of the rectangle and the absorption axis of the polarizer may preferably be 130° or more and 140° or less, more preferably 132° or more and 138° or less, and even more preferably 133° or more and 137° or less. In this case, the long side of the rectangle and the slow axis of the retardation layer may be substantially parallel. Even in such a configuration, better crack resistance can be exhibited.

[0050] The retardation layer may be a single layer as shown in the figure, or may have a laminated structure of two or more layers. When the retardation layer is a single layer, the retardation layer can typically function as a λ / 4 plate. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 17 nm, and even more preferably 120 nm to 160 nm. The retardation layer typically exhibits a refractive index characteristic of nx > ny = nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Specifically, ny > nz or ny < nz may occur. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 〖1.3〗. By satisfying such a relationship, when the optical laminate is applied to an image display device, an optical laminate having a very excellent reflected hue can be obtained.

[0051] When the retardation layer is a single layer, the retardation layer preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. In this case, Re(450) / Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be realized.

[0052] The angle between the slow axis of the phase difference layer and the absorption axis of the polarizer can be any appropriate angle, as long as it does not hinder the effects of the present invention. The angle between the slow axis of the phase difference layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. If the angle is within this range, by making the phase difference layer a λ / 4 plate as described above, an optical laminate with excellent anti-reflective properties can be obtained.

[0053] The phase difference layer can be composed of any suitable material, as long as it possesses the characteristics described above. Specifically, the phase difference layer may be a resin film (stretched resin film) or an orientation-solidified layer of a liquid crystal compound (liquid crystal orientation-solidified layer). Preferably, the phase difference layer is composed of a resin film (stretched resin film). In this case, the thickness of the phase difference layer is preferably 10 μm or more and 70 μm or less, and more preferably 20 μm or more and 60 μm or less.

[0054] Any suitable resin film can be used, as long as it possesses the above-mentioned characteristics. Typical examples of resins constituting the resin film include polycarbonate resins or polyester carbonate resins (hereinafter sometimes simply referred to as polycarbonate resins).

[0055] Any suitable polycarbonate resin can be used as the polycarbonate resin, as long as it has the desired fracture stress. For example, the polycarbonate resin includes structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanol, di, tri, or polyethylene glycols, and alkylene glycols or spiroglycols.

[0056] Preferably, the polycarbonate resin comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, structural units derived from alicyclic dimethanol, and / or structural units derived from di, tri, or polyethylene glycol; more preferably, it comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from di, tri, or polyethylene glycol.

[0057] The polycarbonate resin may optionally contain structural units derived from other dihydroxy compounds. The phase difference layer can be formed by stretching a film composed of the polycarbonate resin described above under any suitable stretching conditions. Details of the polycarbonate resin and the method for forming the phase difference layer are described, for example, in Japanese Patent Publication Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, 2015-212818, 2017-54093, and 2018-60014. The descriptions in these publications are incorporated herein by reference.

[0058] The phase difference layer may further have another phase difference layer (for convenience, the former phase difference layer will be referred to as the "first phase difference layer," and the latter phase difference layer (another phase layer) as the "second phase difference layer"). The second phase difference layer may be, for example, a so-called positive C plate whose refractive index characteristics exhibit the relationship nz > nx = ny. By using a positive C plate as the second phase difference layer, reflections in oblique directions can be effectively prevented, and the anti-reflective function can be widened to a wider viewing angle.

[0059] The phase difference Rth(550) in the thickness direction of the second phase difference layer is preferably -50nm to -300nm, more preferably -70nm to -250nm, even more preferably -90nm to -200nm, and particularly preferably -100nm to -180nm. 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 second phase difference layer may be less than 10nm.

[0060] The second phase difference layer can be formed from any suitable material. Preferably, the second phase difference layer consists of a film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the phase difference layer are those described in paragraphs

[0020] to

[0028] of Japanese Patent Application Publication No. 2002-333642. In this case, the thickness of the second phase difference layer 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.

[0061] D. Reinforcement layer In one embodiment, the optical laminate may further comprise a reinforcing layer that reinforces the phase difference layer. The reinforcing layer may be located on at least one side of the phase difference layer. Preferably, the reinforcing layer may be located on the side of the phase difference layer opposite to the polarizer. Specifically, the reinforcing layer may be located, for example, between the phase difference layer and the adhesive layer. In the illustrated example, in the optical laminate 100, the reinforcing layer 21 is located on the side of the phase difference layer 20 opposite to the polarizer 10 (i.e., on the adhesive layer 30 side). The reinforcing layer can improve the fracture stress of the phase difference layer (substantially the laminate of the phase difference layer and the reinforcing layer). As a result, the crack resistance of the optical laminate can be further improved. When an optical laminate includes a reinforcing layer, the fracture stress σ of the laminate between the phase difference layer and the reinforcing layer b The pressure is preferably 50 MPa or higher, more preferably 60 MPa or higher, and even more preferably 70 MPa or higher. The fracture stress σ of the laminate of the phase difference layer and the reinforcing layer. bThe upper limit may be, for example, 165 MPa. Furthermore, if a reinforcing layer is provided to reinforce the phase difference layer, the "fracture stress σ b This represents the fracture stress of the laminate consisting of a phase difference layer and a reinforcing layer.

[0062] The reinforcing layer may typically be a hard coat layer. The reinforcing layer may be composed of any suitable resin material, as long as it does not hinder the effects according to the embodiments of the present invention. When the reinforcing layer is a hard coat layer, it may have the same configuration as the hard coat layer described in section B of the polarizing plate above. Therefore, when the reinforcing layer is a hard coat layer, the configuration of the hard coat layer is as described in section B-3 above.

[0063] E. Adhesive layer The adhesive layer can be composed of any suitable adhesive. Specific examples 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 resin of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., an adhesive with desired properties for a specific purpose can be prepared. The base resin of the adhesive may be used alone or in combination of two or more types. The base resin is preferably an acrylic resin (specifically, the adhesive layer is preferably composed of an acrylic adhesive).

[0064] The thickness of the adhesive layer can be any appropriate thickness. Preferably, the thickness of the adhesive layer may be 10 μm or more, more preferably 12 μm or more, and even more preferably 15 μm or more. On the other hand, preferably, the thickness of the adhesive layer may be 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0065] F.Through hole As described above, the optical laminate according to the embodiment of the present invention has through holes. The shape of the through-hole in plan view can be any suitable shape. For example, the shape of the through-hole in plan view can be circular, elliptical, rectangular, or polygonal. The number of through-holes can be any suitable number, as long as it does not hinder the effects of the present invention. For example, there may be one through-hole, or two or more, for example, 2 to 6, or for example, 2 to 4, or for example, 2 to 3 through-holes.

[0066] Through-holes can be formed at any suitable location in the optical laminate. For example, through-holes can be formed near the ends of the long and / or short sides in a plan view of the optical laminate. For example, through-holes can be formed near the ends of the long and / or short sides, and approximately in the center of the long and / or short sides.

[0067] When the plan view shape of the optical laminate is rectangular, the distance from the shorter side of the rectangular phase difference layer to the center of the through hole in the plan view is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. With such a configuration, the internal stress σ in the slow phase axis direction is iThe effects of the present invention can be particularly reduced. Therefore, the effects of the embodiments of the present invention can be more clearly manifested. For example, when the optical laminate is applied to an image display device having a screen size of about 5 to 15 inches (e.g., a tablet device, a portable device such as a smartphone), if it is within the above range, even if the through hole is provided near the short side, the occurrence of cracks in the phase difference layer when placed in a high temperature and high humidity environment can be suppressed. In this specification, "the distance from the short side of the rectangle of the phase difference layer in a plan view to the center of the through hole" is the shortest distance between the short side of the rectangle and the center of the through hole in a rectangular phase difference layer in a plan view. Specifically, for example, in the example shown in Figure 1A, when the slow phase axis is substantially parallel to the long side, the distance is the length at which the distance a between one of the short sides of the outer perimeter of the rectangle and the center of the through hole is shortest. The direction of distance a is only required to be substantially parallel to the slow phase axis. Therefore, when the slow phase axis is substantially perpendicular to the long side, the distance is the length at which the distance between one of the short sides of the outer perimeter of the rectangle and the center of the through hole is shortest. When the lagging axis intersects the longer side but is not substantially perpendicular to it, the distance is the length at which the distance between one of the longer or shorter sides of the rectangle's perimeter and the center of the through-hole is shortest.

[0068] In one embodiment, when the plan view shape of the optical laminate is rectangular, the length of one pair of long sides may be 10 mm or more and 400 mm or less, and the length of one pair of short sides may be 5 mm or more and 300 mm or less. In this case, it is preferable that the distance from the short side of the rectangular phase difference layer in plan view to the center of the through hole is 6 mm or less. When the plan view shape of the optical laminate is rectangular, the ratio of the long side to the short side may be, for example, 1:1 or more, preferably 1.2 or more, preferably 1.5 or more, preferably 1.8 or more, and preferably 2.0 or more. The upper limit of the ratio of the long side to the short side may be, for example, 5 times the length of the long side. Note that when the optical laminate is rectangular in plan view, the lengths of all four sides may be equal (the plan view rectangle may be a square or a rhombus). In these cases as well, as long as the through hole is formed at the shortest distance from the outer periphery (any of the four sides) as described above, the same can be defined regardless of the distinction between long and short sides.

[0069] In one embodiment, the optical laminate may have processed parts other than through holes, provided that it has through holes. The processed parts other than through holes may have any suitable shape. For example, the processed parts other than through holes may be irregularly shaped. An irregularly shaped part may be, for example, a machined part that becomes a recess when viewed from above. Typical examples of recesses include a shape approximating a boat shape, a V-shaped notch, and a U-shaped notch.

[0070] G. Image display device The optical laminates described in sections A to F 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 F above on its viewing side. [Examples]

[0071] 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. In the following examples, the axis angle is defined with reference to the direction of the long side of the rectangular optical laminate. When the direction of the long side and the slow axis are substantially parallel, the axis angle of the slow axis (slow axis angle) is approximately 0°, and when the direction of the long side and the slow axis are substantially perpendicular, the slow axis angle is approximately 90°.

[0072] (1) Thickness The measurement was taken using an interferometric film thickness gauge (Otsuka Electronics Co., Ltd., "MCPD9800"). (2) Refractive index, in-plane phase difference The phase difference values ​​of the phase difference layers used in the examples, comparative examples, and reference examples were automatically measured using the KOBRA-WPR instrument manufactured by Oji Instruments. The measurement wavelengths were 448.1 nm, 498.7 nm, 545.6 nm, 587.4 nm, and 628.8 nm, and the measurement temperature was 23°C. Furthermore, the average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive indices nx, ny, and nz were calculated from the obtained phase difference values. Based on nx, the lagging axis of the phase difference layer was confirmed. (3) Moisture permeability (Moisture permeability of the base film) For the protective layer (essentially the base film) used in the fabrication of the optical laminates in the examples, comparative examples, and reference examples, the area per 1 m² is as follows: 2 A test sample was prepared and subjected to a 1 m² area test in an atmosphere of 40°C and 92% RH, in accordance with the JIS Z0208 water vapor permeability test (cup method). 2 The amount of water vapor (g) passing through the test sample over 24 hours was measured. (4) Fracture stress σ b The phase difference layers (phase difference film and laminate of phase difference film and reinforcing layer) used in the fabrication of the optical laminates in the examples, comparative examples, and reference examples were cut into 1 cm wide x 14 cm long sections to prepare test samples. A tensile test was performed on these test samples using a "Triple Autograph AGS-5kNX plus with constant temperature chamber" (manufactured by Shimadzu Corporation) at a temperature of 85°C and 85% humidity, with a tensile speed of 10 mm / min, a chuck distance of 100 mm, and room temperature (23°C). The stress in the slow phase axis direction (breaking stress σ) at which the test sample of the phase difference layer broke was determined. b ) was sought. (5) Internal stress σ i (5-1) Measurement of deformation under high temperature and high humidity conditions (temperature 85°C and humidity 85%) Test samples were prepared by cutting the optical laminates of the examples, comparative examples, and reference examples into 4 mm wide x 16 mm long sections. The test samples were subjected to thermomechanical analysis using a "TMA4000SA" thermomechanical analyzer (manufactured by NETZSCH Japan) according to JIS K7197. First, they were placed at 25°C and 55% humidity for 30 minutes, then the temperature was increased to 85°C and 55% humidity for 30 minutes. Next, the humidity was further increased to 85°C and 85% humidity, and the samples were left in this environment for 900 minutes. After 900 minutes, the humidity was decreased to 85°C and 55% humidity for 30 minutes, and then the temperature was decreased to 25°C and 55% humidity for 30 minutes. The heating and cooling rates were 0.5°C / min, and the humidity increasing and decreasing rates were 5% / min. In this manner, the deformation of the test samples at each temperature was measured. Furthermore, a positive (plus) value was used when the film dimensions increased (expanded) as the temperature rose, and a negative (minus) value was used when the film dimensions decreased (shrinked) as the temperature rose. (5-2) Tensile modulus Test samples were prepared by cutting the optical laminates of the examples, comparative examples, and reference examples into 1 cm wide x 14 cm long sections. Tensile tests were performed on the test samples using a "Triple Autograph AGS-5kNX plus with constant temperature chamber" (manufactured by Shimadzu Corporation) in accordance with JIS K7127, at a temperature of 85°C and a humidity of 85%. The tensile modulus was calculated from the linear regression of the resulting stress-strain curves. The tensile tests were performed by clamping each 20 mm end of the optical laminate test sample in the chucks of a universal tensile testing machine, with a chuck distance of 10 mm and a tensile speed of 10 mm / min. (5-3) Simulation Using Hexagon's nonlinear finite element analysis software (Marc), the internal stress of the optical laminate was simulated and analyzed under conditions of 85°C and 85% humidity, using the measurement results of the thermal expansion coefficient and tensile modulus of the optical laminate obtained in (5-1) and (5-2) above. The analysis was performed using nonlinear finite analysis. Of the obtained results, the stress in the slow axis direction of the phase difference layer was defined as the internal stress σ. i It is defined as follows, and Table 1 shows "Sim stress σ i This will be shown in the " " column. (6) Evaluation test (crack resistance) Ten evaluation samples were prepared for each of the examples, comparative examples, and reference examples, each consisting of an optical laminate with the processed portion (through-hole or U-notch) formed on it, bonded to a glass plate. The dimensions of the test samples were 160 mm on the long side and 76 mm on the short side in a plan view. The distance of the through-holes from the slow-phase axis direction of the phase difference layer is shown in Table 1. Ten test samples were left standing for 120 hours in an environment of 85°C and 85% humidity. After 120 hours, the test samples were removed and observed with an optical microscope. Cracks near the through-holes in the test samples were evaluated according to the following criteria. 1 (Good): No cracks were observed in any of the 10 samples near the through-hole. 2 (Acceptable): At least one sample showed a crack with a vertical length of 300 μm or less near the through-hole. 3 (Unacceptable): At least one sample had a crack with a vertical length exceeding 300 μm near the through-hole.

[0073] [Manufacturing Example 1-1: Production of Polycarbonate (PC) Resin Film] 37.5 parts by mass of isosorbide (ISB), 91.5 parts by mass of 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), 8.4 parts by mass of polyethylene glycol (PEG) with an average molecular weight of 400, 105.7 parts by mass of diphenyl carbonate (DPC), and 0.594 parts by mass of cesium carbonate (0.2% by mass aqueous solution) as a catalyst were each added to a reaction vessel. As the first step of the reaction, under a nitrogen atmosphere, the temperature of the heat transfer medium in the reaction vessel was raised to 150°C, and the raw materials were dissolved while stirring as needed (for about 15 minutes). Next, the pressure inside the reaction vessel was increased from atmospheric pressure to 13.3 kPa, and the temperature of the heat transfer medium inside the reaction vessel was raised to 190°C over one hour while the generated phenol was removed from the reaction vessel. After maintaining the reaction vessel temperature at 190°C for 15 minutes, the second step involved increasing the pressure inside the reaction vessel to 6.67 kPa and raising the heat transfer medium temperature to 230°C over 15 minutes to remove the generated phenol. As the stirring torque of the stirrer increased, the temperature was raised to 250°C over 8 minutes, and the pressure inside the reaction vessel was reduced to below 0.200 kPa to further remove the generated phenol. After reaching the predetermined stirring torque, the reaction was terminated, and the resulting reactants were pushed into water. Pelletization was then performed to obtain a polycarbonate resin (PC resin) containing structural units derived from dihydroxy compounds in a ratio of BHEPF / ISB / PEG = 42.9 mol% / 52.8 mol% / 4.3 mol%. This PC resin was molded into a film to produce a PC film. The moisture permeability of the PC resin film was 120 g / m². 2 The duration was 24 hours. Note that "PC" in Table 1 refers to the PC-based resin film mentioned above.

[0074] [Manufacturing Example 1-2: Preparation of TAC resin film] A commercially available triacetylcellulose (TAC) film (product name "TJ25UL" manufactured by Fujifilm Corporation, 25 μm thick) was used as the protective layer (base film). The moisture permeability of the base film (TAC film) was 1040 / m². 2 It was 24 hours.

[0075] [Manufacturing Example 1-3: Fabrication of COP-based resin film] A commercially available cycloolefin (COP) film (manufactured by Zeon Corporation, product name "ZF12", thickness 25 μm) was used as the protective layer (base film). The moisture permeability of the base film (COP film) was 5 / m². 2 It was 24 hours.

[0076] [Manufacturing Example 2: Preparation of Materials for Hard Coat Layer Formation] 50 parts by weight of UV-curable acrylate resin (manufactured by DIC Corporation, trade name "Luxidia 17-806", solids content 80%) was prepared. 3 parts by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name "OMNIRAD907") and 0.05 parts by weight of a leveling agent (manufactured by DIC Corporation, trade name "GRANDIC PC4100", solids content 10%) were mixed per 100 parts by weight of the resin solids content to obtain a mixture. The obtained mixture was diluted with a mixed solvent of isopropyl alcohol (IPA) and cyclopentanone (CPN) in a weight ratio of 65:35 to achieve a solids content concentration of 36%. This prepared a hard coat layer forming material (hereinafter referred to as HC layer forming material 1).

[0077] [Manufacturing Example 3: Polarizer Fabrication] 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 long laminate having a resin substrate / polarizer configuration was obtained. The transmittance Ts of the polarizer alone was 43.0%. The polarizer had an absorption axis at a 135° angle to the longitudinal direction. The longitudinal direction of the polarizer coincides with the direction of the long side of the rectangular section cut from the optical laminate described later.

[0078] [Manufacturing Example 4-1: Fabrication of Phase Difference Film] A batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C was used to prepare the reactor. The mixture contained 29.60 parts by weight (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by weight (0.200 mol) of isosorbide (ISB), 42.28 parts by weight (0.139 mol) of spiroglycol (SPG), 63.77 parts by weight (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10⁻¹⁶ calcium acetate monohydrate as a catalyst. -2 Weight part (6.78×10 -5A mol (mol) was added. After purging the reactor with reduced pressure using nitrogen, the reactor was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the pressure to maintain this temperature, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was led to a reflux condenser at 100°C, the monomer components contained in small amounts in the phenol vapor were returned to the reactor, and the uncondensed phenol vapor was led to a condenser at 45°C for recovery. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and then the oligomerized reaction mixture in the first reactor was transferred to the second reactor. Next, heating and depressurization were started in the second reactor, and the internal temperature was raised to 240°C and the pressure to 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was reached. Once the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and 0.7 parts by mass of PMMA was melt-kneaded with 100 parts by weight of the generated polyester carbonate resin. The mixture was then extruded into water, and the strands were cut to obtain pellets. The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours. Then, a long resin film with a thickness of 105 μm was produced using a film-making apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120~130°C), and a winding machine. The obtained elongated resin film was stretched 2.8 times in the width direction at 138°C while adjusting to obtain a predetermined phase difference, to obtain a phase difference film R1 with a thickness of 37 μm. The Re(550) of the obtained phase difference film R1 was 147 nm, and the Re(450) / Re(550) was 0.86. In the elongated phase difference film R1, the length direction and the slow phase axis of the phase difference film R1 were substantially parallel (i.e., the angle between the length direction and the slow phase axis direction was 0°). The fabricated phase difference film R1 was used to evaluate the fracture stress described in (4) above. Fracture stress σ b This is shown in Table 1.

[0079] [Manufacturing Example 4-2: Fabrication of Phase Difference Film] A phase difference film was prepared in the same manner as in Production Example 4-1, except that the thickness of the film before stretching was 135 μm and the thickness of the film after stretching was 47 μm. Specifically, the polyester carbonate resin (pellets) obtained in Production Example 4-1 was vacuum dried at 80°C for 5 hours, and then a long resin film with a thickness of 135 μm was prepared using a film-making apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120~130°C), and a winding machine. The obtained elongated resin film was stretched in the width direction at a stretching temperature of 143°C and a stretching ratio of 2.8 times to obtain a phase difference film R2 with a thickness of 47 μm. The Re(550) of the obtained phase difference film R2 was 147 nm, and the Re(450) / Re(550) ratio was 0.86. In the elongated phase difference film R2, the length direction and the slow phase axis of the phase difference film R2 were substantially orthogonal (i.e., the angle between the length direction and the slow phase axis direction was 90°). The fabricated phase difference film was used to evaluate the fracture stress described in (4) above. Fracture stress σ b This is shown in Table 1.

[0080] [Manufacturing Example 5: Fabrication of a laminate with a reinforcing layer (a laminate of a phase difference film and a reinforcing layer)] The hard coat layer forming material (HC layer forming material 1) prepared in Manufacturing Example 2 was applied to one surface of the phase difference film R1 manufactured in Manufacturing Example 4-1, and then the hard coat layer forming material was cured. This created a reinforcing layer on the phase difference film, and a laminate R3 of the phase difference film and the reinforcing layer was obtained. The laminate R3 was subjected to the evaluation of the fracture stress in (4) above. The fracture stress of the obtained laminate R3 was defined as the fracture stress σ in the slow phase axis direction. b This is shown in Table 1.

[0081] [Example 1] (Fabrication of polarizing plates) The surface of the TAC resin film (thickness 25 μm) from manufacturing example 1-2 was coated with HC layer forming material 1, and then the HC layer forming material was cured. This resulted in a laminate of an HC layer and a protective layer (TAC film). The thickness of the HC layer was 6 μm. Next, the HC layer / protective layer (TAC film) laminate of the laminate from Manufacturing Example 3 was bonded to the polarizer surface (the side opposite to the resin substrate) via a UV-curing adhesive (1 μm thick), with the TAC film facing the polarizer side. Specifically, the UV-curing adhesive was applied to a total thickness of 1.0 μm and bonded using a roll press. After that, UV light was irradiated from the protective layer side to cure the adhesive. Then, the resin substrate was peeled off to obtain a polarizing plate having the configuration of HC layer / protective layer / adhesive layer / polarizer. (Fabrication of optical stacks) The phase difference film R1 obtained in Manufacturing Example 4-1 was bonded to the polarizer surface of the obtained long polarizer plate via an ultraviolet-curable adhesive (thickness 1 μm) such that the longitudinal direction of the polarizer plate and the slow phase axis of the phase difference layer were substantially parallel (the angle between them was approximately 0°). In this way, a laminate having the configuration of polarizer plate (HC layer / protective layer / polarizer) / adhesive layer / phase difference layer (phase difference film R1) was obtained. Bonding and debonding were performed by a roll-to-roll process. Next, an acrylic adhesive layer (20 μm thick) with a release liner on one surface side was placed on the phase difference layer side. In this way, an optical laminate having the configuration of HC layer / protective layer / polarizer / adhesive layer / phase difference layer (phase difference film R1) / adhesive layer / release liner was obtained. The acrylic adhesive layer described above was prepared by applying an acrylic adhesive composition, prepared using the following acrylic polymers, to the substrate. <Preparation of acrylic adhesive composition and creation of adhesive layer> In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of n-butyl acrylate (BA) were added and mixed. Next, to 100 parts by weight of the above mixture (monomer mixture), 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator along with ethyl acetate, and the mixture was gently stirred while introducing nitrogen gas to purge the mixture with nitrogen. The mixture was then stirred for 7 hours while maintaining the temperature of the liquid in the flask at around 55°C. The monomer concentration during stirring was adjusted to 40% by weight. Subsequently, ethyl acetate was added to the resulting reaction solution to adjust the solid content concentration to 30%. This yielded a solution of acrylic polymer. The POB-A used was a commercially available monomer (manufactured by Kyoeisha Chemical, purity 94%) that was further purified by adsorption. To 100 parts by weight of the solids content of the above acrylic polymer, 0.3 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / xylylene diisocyanate trimer adduct, manufactured by Mitsui Chemicals, Takenate D-110N) was added, and ethyl acetate was added as a diluent so that the total solids content was 15% by weight. The mixture was then mixed and stirred. In this way, an acrylic adhesive composition was prepared. Next, the solution of the above acrylic adhesive composition was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Films, thickness: 38 μm) so that the thickness of the adhesive layer after drying would be 20 μm. The mixture was dried at 150°C for 3 minutes to form an adhesive layer. Next, the optical laminate was cut to dimensions of 160 mm on the long side and 76 mm on the short side, and through holes with a diameter of 2.6 mm were formed at positions 38 mm from both long sides in a plan view and 4.2 mm from one of the short sides in a plan view. This created an evaluation sample with through holes, and the release liner was peeled off from the adhesive layer and used for the evaluation described in (5) above. Figure 2A shows an example of the stress distribution obtained by simulation in Example 1. The roughly circular shape near the center of the figure is the through hole. It can be seen that in the vicinity of the through hole, the internal stress is greater in the direction of the leading phase axis than in other directions. The distance from the processed part (center of the through hole) to the short side in the slow phase axis direction of the phase difference layer is shown in Table 1. Furthermore, the evaluation sample having the above-mentioned through-hole was bonded to a glass plate of the same dimensions (long side 160 mm, short side 76 mm) and subjected to the evaluation described in (6) above. The results are shown in Table 1.

[0082] [Examples 2-4, 7 and Comparative Examples 1-2] (Fabrication of polarizing plates) A long polarizing plate was manufactured in the same manner as in Example 1, except that the protective layer (base film) was changed to the film shown in the "Protective Layer (Base Film)" column of Table 1 (the one from the corresponding manufacturing example). (Fabrication of optical stacks) The optical laminate was fabricated in the same manner, except that the long polarizing plate prepared as described above was used, the longitudinal direction of the polarizing plate and the slow axis of the phase difference layer were made substantially orthogonal (the angle between them is approximately 90°), and the phase difference film was changed to the film shown in Table 1. Next, an evaluation sample with a through hole was prepared in the same manner as in Example 1. The distance from the machined portion (center of the through hole) to the short side in the slow phase axis direction of the phase difference layer is shown in Table 1. Then, as in Example 1, it was subjected to evaluation of (5) and (6) above. The results are shown in Table 1. As in Example 1, Figure 2B shows an example of the stress distribution obtained by simulation for Comparative Example 1.

[0083] [Examples 5 and 6] (Fabrication of polarizing plates) A long polarizing plate was manufactured in the same manner as in Example 1, except that the protective layer (base film) was changed to the film shown in the "Protective Layer (Base Film)" column of Table 1 (the one from the corresponding manufacturing example). (Fabrication of optical stacks) The optical laminate was fabricated in the same manner as described above, except that the long polarizing plate prepared as described above was used, the angle between the long direction of the polarizing plate and the slow axis of the phase difference layer (the angle between the long side and the slow axis of the phase difference layer was set to the angle shown in Table 1), and the laminate with the reinforcing layer from Manufacturing Example 5 (a laminate of phase difference film and reinforcing layer) was used instead of the phase difference film. In detail, the phase difference film side of laminate R3 obtained in Manufacturing Example 5 was bonded to the polarizer surface of a long polarizing plate via an ultraviolet-curing adhesive (thickness 1 μm) such that the longitudinal direction of the polarizing plate and the slow phase axis of the phase difference layer were substantially orthogonal (the angle between them was approximately 90°). In this way, a laminate having the configuration of polarizing plate (HC layer / protective layer / polarizer) / adhesive layer / phase difference layer (phase difference film / reinforcement layer) was obtained. Bonding and debonding were performed by a roll-to-roll process. The angle between the longitudinal direction of the polarizing plate and the absorption axis of the polarizer was set to 135°. Next, the acrylic adhesive layer (20 μm thick) described above was placed on the reinforcing layer side of the phase difference layer. In this way, an optical laminate having the configuration of HC layer / protective layer / polarizer / adhesive layer / phase difference film / reinforcing layer / adhesive layer / release liner was obtained. Next, an evaluation sample with a through hole was prepared in the same manner as in Example 1. The distance from the machined portion (center of the through hole) to the short side in the slow phase axis direction of the phase difference layer is shown in Table 1. Then, as in Example 1, it was subjected to evaluations (5) and (6) above. The results are shown in Table 1.

[0084] [Reference example 1] (Fabrication of polarizing plates) A long polarizing plate was fabricated in the same manner as in Example 1. (Fabrication of optical stacks) Next, an optical laminate was fabricated in the same manner as in Example 1, except that the angle of the slow axis was changed to the angle shown in Table 1, using the polarizing plate prepared above. The obtained optical laminate was cut to dimensions of 160 mm on the long side and 76 mm on the short side, and processed into a U-notch shape to form a processed section (irregularly shaped processed section). The U-notch was formed at the position of 36.87 mm on the long side of the rectangular shape in plan view. This was used as the evaluation sample. The evaluation sample was subjected to the same evaluation as in (5) and (6) above. The results are shown in Table 1.

[0085] [Table 1]

[0086] [evaluation] As is clear from Table 1, according to the embodiment of the present invention, the fracture stress σ in the lagging axis direction of the phase difference layer b and the internal stress σ of the optical stack in the slow phase axis direction i Equation (1): σ i / σ b By satisfying the relationship <1.15, it was shown that even with through holes, cracks in high-temperature and high-humidity environments are significantly suppressed, resulting in excellent crack resistance. Reference Example 1 is an experimental example shown as a reference for crack resistance when the processed part is not a through hole but a deformed shape (U-notch processing). [Industrial applicability]

[0087] 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]

[0088] 10 Polarizing plates 11 Polarizer 12 Protective layer 13. Hard Court Layer 20 Retardation layer 21 Reinforcement layer 30 Adhesive layer 40 Through holes 100 Optical laminate

Claims

1. An optical laminate comprising a protective layer, a polarizer, and a phase difference layer in this order, The optical laminate has through holes, When the optical laminate is placed in an environment with a temperature of 85°C and a humidity of 85% for 120 hours, the fracture stress in the slow axis direction of the phase difference layer is σ ｂ , and the internal stress of the optical laminate in the slow axis direction σ ｉ An optical laminate that satisfies the relationship in equation (1) below. s ｉ / s ｂ <1.15・・・(1)

2. The optical laminate according to claim 1, further comprising a hard coat layer on the side of the protective layer opposite to the polarizer.

3. The optical laminate according to claim 1 or 2, further comprising a reinforcing layer that reinforces the phase difference layer on at least one surface of the phase difference layer.

4. The optical laminate according to claim 3, wherein the reinforcing layer is a hard coat layer.

5. The moisture permeability of the protective layer is 1100 g / m². ２ The optical laminate according to claim 1, wherein the aging period is 24 hours or less.

6. The planar shape of the optical laminate is rectangular. The longer side of the rectangle and the slow axis of the phase difference layer are substantially parallel or perpendicular to each other. The angle between the longer side of the rectangle and the absorption axis of the polarizer is 130° or more and 140° or less, or 40° or more and 50° or less. The optical laminate according to claim 1.

7. The planar shape of the optical laminate is rectangular. The optical laminate according to claim 1, wherein the distance from the shorter side of the rectangle to the center of the through hole in a plan view is 10 mm or less.

8. An image display device comprising an optical laminate according to claim 1 or 2.

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