Optical laminate and image display apparatus

Abstract

The present invention provides an optical laminate capable of achieving thinness, which, when applied to an image display device, can improve visibility through an optical member having a polarizing action. An optical laminate according to an embodiment of the present invention comprises a first phase difference film, a polarizer, and a second phase difference film in that order. The first phase difference film comprises an orientation solidification layer of a liquid crystal compound. The in-plane phase difference Re (450) of the first phase difference film is 100 nm or more and 130 nm or less. The Re (450) / Re (550) of the first phase difference film is greater than 1.

Description

Technology Field

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

[0002] Conventionally, image display devices represented by liquid crystal displays and electroluminescence (EL) displays (e.g., organic EL displays, inorganic EL displays) are rapidly becoming widespread. When a viewer views such an image display device through polarized sunglasses, the screen of the image display device may appear colored depending on the viewer's viewing angle, and there is a risk that the visibility of the displayed image may be reduced.

[0003] To solve this problem, it is proposed to place an optical laminate equipped with a phase difference film and a polarizer on the viewing side of an image display panel in an image display device (e.g., see Patent Document 1). Prior art literature

[0004] Japanese Patent Publication No. 2024-124169 The problem to be solved

[0005] Recently, as the applications of image display devices have expanded, there are cases where further thinning of optical laminates is required. However, in the optical laminate described in Patent Document 1, it is difficult to provide visibility to the image display device through an optical member having a polarizing effect while achieving thinning.

[0006] The main objective of the present invention is to provide an optical laminate capable of achieving thinness, which, when applied to an image display device, can improve visibility through an optical member having a polarizing effect. means of solving the problem

[0007] [1] An optical laminate according to an embodiment of the present invention comprises a first phase difference film, a polarizer, and a second phase difference film in that order. The first phase difference film comprises an orientation solidification layer of a liquid crystal compound. The in-plane phase difference Re (450) of the first phase difference film is 100 nm or more and 130 nm or less. The Re (450) / Re (550) of the first phase difference film is greater than 1.

[0008] [2] In the optical laminate described in [1] above, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the polarizer in the second phase difference film in the stacking direction of the optical laminate may be less than 15 μm.

[0009] [3] In the optical laminate described in [1] above, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the polarizer in the second phase difference film in the stacking direction of the optical laminate may be less than 10 μm.

[0010] [4] The optical laminate described in any one of [1] to [3] above may further comprise an adhesive layer. The adhesive layer is located on the opposite side of the polarizer with respect to the second phase difference film.

[0011] [5] In the optical laminate described in [4] above, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the second phase difference film in the adhesive layer in the stacking direction of the optical laminate may be less than 35 μm.

[0012] [6] In the optical laminate described in [4] above, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the second phase difference film in the adhesive layer in the stacking direction of the optical laminate may be less than 25 μm.

[0013] [7] In the optical laminate described in any one of [1] to [6] above, the Re(450) / Re(550) in the first phase difference film may be 1.05 or more and 1.5 or less.

[0014] [8] In the optical laminate described in any one of [1] to [7] above, the angle formed by the ground axis direction of the first phase difference film and the absorption axis direction of the polarizer may be 35° to 55°.

[0015] [9] In the optical laminate described in any one of [1] to [8] above, the second phase difference film may function as a λ / 4 plate.

[0016]

[10] In any one of [1] to [9] above, the thickness of the second phase difference film may be greater than the thickness of the first phase difference film.

[0017]

[11] In the optical laminate described in any one of [1] to

[10] above, the second phase difference film may include an orientation solidification layer of a liquid crystal compound. The Re(450) / Re(550) in the second phase difference film may be 1 or less.

[0018]

[12] In the optical laminate described in any one of [1] to

[11] above, the thickness of the first phase difference film may be 0.5 μm or more and 2.0 μm or less.

[0019]

[13] The optical laminate described in any one of [1] to

[12] above may further comprise a first adhesive layer. The first adhesive layer laminates the first phase difference film and the polarizer. The thickness of the first adhesive layer may be less than 0.5 μm.

[0020]

[14] The optical laminate described in

[13] above may have the first adhesive layer as the first adhesive layer.

[0021]

[15] The optical laminate described in any one of [1] to

[14] above may further have a second adhesive layer. The second adhesive layer laminates the polarizer and the second phase difference film. The thickness of the second adhesive layer may be less than 0.5 μm.

[0022]

[16] In the optical laminate described in

[15] above, the second adhesive layer may be a second adhesive layer.

[0023]

[17] In the optical laminate described in

[16] above, the second adhesive layer may include a cured product of a water-based adhesive containing an organosilicon compound.

[0024]

[18] In the optical laminate described in

[17] above, the organosilicon compound may include an amino-based silane coupling agent.

[0025]

[19] In the optical laminate described in

[17] or

[18] above, the organosilicon compound may include an epoxy-based silane coupling agent.

[0026]

[20] An image display device according to another aspect of the present invention has an optical laminate described in any one of [1] to

[19] .

[0027]

[21] In the image display device described in

[20] above, the first phase difference film may be positioned on the viewing side with respect to the polarizer. Effects of the invention

[0028] According to an embodiment of the present invention, an optical laminate capable of achieving thinness can be realized, which, when applied to an image display device, can improve visibility through an optical member having a polarization action. Brief explanation of the drawing

[0029] FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. Specific details for implementing the invention

[0030] Representative embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. Furthermore, in order to make the explanation clearer, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to actual embodiments; however, this is merely an example and does not limit the interpretation of the present invention.

[0031] (Definition of Terms and Symbols)

[0032] The definitions of terms and symbols in this specification are as follows.

[0033] (1) Refractive index (nx, ny, nz)

[0034] 'nx' is the refractive index in the direction where the refractive index in the plane is maximum (i.e., the ground axis direction), 'ny' is the refractive index in the direction perpendicular to the ground axis in the plane (i.e., the true axis direction), and 'nz' is the refractive index in the thickness direction.

[0035] ellipse (x 2 / a 2 )+(y 2 / b 2 At )=1, let a be nx and b be ny, and let x and y be the refractive indices in the x-direction and y-direction at the angle θ of the ellipse, solve the system of equations from y=x(tanθ) and the above nx and ny, and the 'refractive index in the direction of the transmission axis' is √(x 2 +y 2 It can be obtained by ).

[0036] The 'average refractive index' can be calculated by (nx+ny+nz) / 3.

[0037] (2) In-plane phase difference (Re)

[0038] 'Re(λ)' is the in-plane phase difference measured with light of wavelength λnm at 23°C. For example, 'Re(550)' is the in-plane phase difference measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated by the formula: Re(λ)=(nx-ny)×d, where the thickness of the layer (film) is d(nm).

[0039] (3) Phase difference in the thickness direction (Rth)

[0040] 'Rth(λ)' is the phase difference in the thickness direction measured with light of wavelength λnm at 23°C. For example, 'Rth(550)' is the phase difference in the thickness direction measured with light of wavelength 550nm at 23°C. Rth(λ) can be calculated by the formula: Rth(λ)=(nx-nz)×d, where the thickness of the layer (film) is d(nm).

[0041] (4) Nz coefficient

[0042] The Nz coefficient can be calculated using the formula Nz = Rth / Re.

[0043] (5) Angle

[0044] When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Accordingly, for example, '45°' means ±45°.

[0045] (6) substantially parallel or orthogonal

[0046] The expressions 'substantially parallel' and 'approximately parallel' include cases where the angle between the two directions is within 0°±3°. Also, the expressions 'substantially orthogonal' and 'approximately orthogonal' include cases where the angle between the two directions is 90°±3°.

[0047] A. Overview of Optical Laminates

[0048] FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0049] In one embodiment, the optical laminate (100) comprises a first phase difference film (1), a polarizer (3), and a second phase difference film (2) in this order.

[0050] The polarizer (3) has a transmission axis that transmits polarized light vibrating in a specific direction and an absorption axis that is orthogonal to the transmission axis. In the following, the direction in which the transmission axis extends is referred to as the transmission axis direction, and the direction in which the absorption axis extends is referred to as the absorption axis direction.

[0051] The first phase difference film (1) includes an orientation solidification layer of a liquid crystal compound (hereinafter referred to as a liquid crystal orientation solidification layer). In this specification, "an orientation solidification layer of a liquid crystal compound" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and its orientation state is fixed. Furthermore, the "orientation solidification layer" is a concept that includes an orientation cured layer obtained by curing a liquid crystal monomer as described below.

[0052] The first phase difference film (1) has an in-plane phase difference. The in-plane phase difference Re (450) of the first phase difference film (1) is 100 nm or more and 130 nm or less.

[0053] The first phase difference film (1) typically exhibits positive wavelength dispersion characteristics in which in-plane birefringence decreases with the wavelength of the measurement light. Re (450) / Re (550) in the first phase difference film (1) exceeds 1.

[0054] According to this configuration, since the first phase difference film includes a liquid crystal alignment solidification layer, the difference between nx and ny of the first phase difference film can be made significantly larger compared to a non-liquid crystal material. Therefore, the thickness of the phase difference film having a desired phase difference can be significantly reduced, and as a result, the optical laminate can be made thinner.

[0055] In addition, in the first phase difference film, the in-plane phase difference Re (450) is 100 nm or more and 130 nm or less, and since Re (450) / Re (550) is greater than 1, when the optical laminate is applied to an image display device, the visibility of the image display device can be improved through an optical member having a polarizing effect (hereinafter referred to as a polarizing member).

[0056] Therefore, while promoting the thinning of the optical laminate, visibility through a polarizing member can be improved in an image display device equipped with an optical laminate.

[0057] The refractive index of the first phase difference film (1) preferably exhibits the relationship nx > ny ≥ nz.

[0058] The first phase difference film (1) functions, typically as a λ / 4 plate. According to this configuration, in an image display device equipped with an optical laminate, visibility through a polarizing member can be reliably improved.

[0059] The in-plane phase difference Re (450) of the first phase difference film (1) is preferably 105 nm or more, and more preferably 110 nm or more. Meanwhile, the in-plane phase difference Re (450) of the first phase difference film (1) is preferably 125 nm or less, and preferably 120 nm or less.

[0060] The in-plane phase difference Re (550) of the first phase difference film (1) is, for example, 85 nm or more, preferably 90 nm or more, and more preferably 95 nm or more. Meanwhile, the in-plane phase difference Re (550) of the first phase difference film (1) is, for example, 120 nm or less, and preferably 115 nm or less.

[0061] In the first phase difference film (1), the ratio of the in-plane phase difference Re (450) to the in-plane phase difference Re (550) (Re (450) / Re (550)) is preferably 1.01 or higher, and more preferably 1.05 or higher. Meanwhile, Re (450) / Re (550) is, for example, 1.20 or lower, also, for example, 1.50 or lower, and also, for example, 1.15 or lower.

[0062] If the in-plane phase difference and / or Re(450) / Re(550) in the first phase difference film is within this range, the visibility through the polarizing member in the image display device having the optical laminate can be more stably improved.

[0063] The angle formed by the ground axis direction of the first phase difference film (1) and the absorption axis direction of the polarizer (3) is, for example, 30° to 60°, preferably 35° to 55°, more preferably 40° to 50°, and even more preferably 43° to 47°.

[0064] According to this configuration, visibility through a polarizing element in an image display device can be further improved more stably.

[0065] The first phase difference film (1) may have a single-layer structure of a liquid crystal alignment solidification layer, or a laminated structure including a liquid crystal alignment solidification layer.

[0066] In one embodiment, the first phase difference film (1) has a single-layer structure of a liquid crystal alignment solidification layer. According to this configuration, the thinning of the optical laminate can be stably achieved.

[0067] The thickness of the first phase difference film (1) is arbitrarily and appropriately adjusted so that a desired phase difference is obtained.

[0068] The thickness of the first phase difference film (1) is, for example, 10 μm or less, preferably 5.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.0 μm or less. Meanwhile, the thickness of the first phase difference film (1) is, for example, 0.1 μm or more, preferably 0.5 μm or more, and even more preferably 0.8 μm or more.

[0069] The refractive index of the first phase difference film (1) in the transmission axis direction is, for example, 1.45 or higher, and preferably 1.50 or higher. Meanwhile, the refractive index of the first phase difference film (1) in the transmission axis direction is, for example, 1.70 or lower, preferably less than 1.60, and more preferably 1.58 or lower.

[0070] In addition, the refractive index is measured, for example, by a thin-film waveguide (prism coupler) using light of wavelength 594 nm.

[0071] The polarizer (3) is located between the first phase difference film (1) and the second phase difference film (2) in the stacking direction of the optical laminate (100).

[0072] The thickness of the polarizer (3) is, for example, 1 μm to 80 μm, preferably 1 μm to 15 μm, more preferably 1 μm to 12 μm, and even more preferably 3 μm to 8 μm.

[0073] If the polarizer has this thickness, further thinning of the optical laminate can be achieved.

[0074] In one embodiment, the polarizer (3) is attached to the first phase difference film (1) via the first adhesive layer (4). In other words, the optical laminate (100) further comprises the first adhesive layer (4). In the illustrated example, the first adhesive layer (4) is in contact with the polarizer (3) and the first phase difference film (1).

[0075] The thickness of the first adhesive layer (4) is, for example, 2.0 μm or less, preferably 1.20 μm or less, more preferably 0.80 μm or less, even more preferably less than 0.50 μm, even more preferably 0.12 μm or less, particularly preferably 0.05 μm or less, and most preferably 0.04 μm or less.

[0076] If the first phase difference film includes a liquid crystal alignment solidification layer, it can be thinned compared to the case where the first phase difference film is composed of a non-liquid crystal material (typically a resin), and also, because the refractive index is relatively large, light reflection and interference are likely to occur at the interface between the first phase difference film and the adjacent layer.

[0077] However, in one embodiment, since the thickness of the first adhesive layer is adjusted to be below this upper limit, the first adhesive layer can be made sufficiently thin with respect to the wavelength of visible light. Therefore, even if the first adhesive layer and the first phase difference film are adjacent to each other, external light (visible light) is reflected at the interface between the first adhesive layer and the first phase difference film, and interference of said reflected light can be suppressed. As a result, in an image display device equipped with an optical laminate, black display can be suppressed from having colored interference stains.

[0078] Meanwhile, the thickness of the first adhesive layer (4) is, for example, 0.001 μm or more, preferably 0.005 μm or more, and more preferably 0.01 μm or more.

[0079] If the thickness of the first adhesive layer is greater than or equal to this lower limit, the adhesive strength of the first adhesive layer can be improved, and layers adjacent to the first adhesive layer (typically a polarizer and a first phase difference film) can be stably laminated.

[0080] The refractive index of the first adhesive layer (4) in the transmission axis direction is, for example, 1.40 or higher, preferably 1.43 or higher, and more preferably 1.45 or higher. Meanwhile, the refractive index of the first adhesive layer (4) in the transmission axis direction is, for example, 1.70 or lower, and preferably 1.60 or lower.

[0081] The absolute value of the difference between the refractive index of the first adhesive layer (4) and the refractive index of the first phase difference film (1) in the transmission axis direction is, for example, 0.30 or less, preferably 0.20 or less, more preferably 0.10 or less, and even more preferably 0.08 or less. Meanwhile, the lower limit of the absolute value of the difference between the refractive index of the first adhesive layer (4) and the refractive index of the first phase difference film (1) in the transmission axis direction is typically 0.

[0082] If the difference in refractive index between the first adhesive layer and the first phase difference film is within this range, even if the first adhesive layer and the first phase difference film are adjacent to each other, light (visible light) incident on the optical laminate can be reliably suppressed from being reflected at the interface between the first adhesive layer and the first phase difference film.

[0083] The first adhesive layer (4) may be an adhesive layer composed of an adhesive, or an adhesive layer composed of a pressure-sensitive adhesive.

[0084] In one embodiment, the first adhesive layer (4) is a first adhesive layer (41) composed of an adhesive (more specifically, a cured product of the adhesive).

[0085] In the adhesive layer, unevenness in curing and / or thickness may occur due to curing shrinkage of the adhesive, coating stains, coating clumping, drying stains, etc. In this case, unevenness in the optical path length of the optical laminate may occur due to the unevenness in the adhesive layer, and as a result, there is a risk of interference stains occurring in an image display device equipped with the optical laminate.

[0086] In this regard, according to one embodiment, since the thickness of the first adhesive layer (41) is within the above-mentioned range, the degree of curing shrinkage of the adhesive, coating stains, coating clumping, drying stains, etc., can be sufficiently reduced, and the occurrence of bending and / or thickness non-uniformity in the first adhesive layer can be significantly suppressed. Accordingly, non-uniformity of the optical path length in the optical laminate can be reduced, and interference stains in the image display device can be suppressed more stably.

[0087] The second phase difference film (2) is located on the opposite side of the first phase difference film (1) with respect to the polarizer (3).

[0088] The second phase difference film (2) typically has an in-plane phase difference. In this case, the refractive index of the second phase difference film (2) exhibits a relationship such as nx > ny, and preferably exhibits a relationship such as nx > ny ≥ nz.

[0089] In one embodiment, the second phase difference film (2) functions as λ / 4. According to this configuration, the optical laminate can be imparted anti-reflection properties.

[0090] The in-plane phase difference Re (550) of the second phase difference film (2) is, for example, 90 nm to 160 nm, and preferably 100 nm to 150 nm.

[0091] The second phase difference film (2) may exhibit inverse wavelength dispersion characteristics in which the in-plane birefringence increases with the wavelength of the measurement light, positive wavelength dispersion characteristics in which the in-plane birefringence decreases with the wavelength of the measurement light, or flat wavelength dispersion characteristics in which the in-plane birefringence hardly changes with the wavelength of the measurement light.

[0092] In one embodiment, the second phase difference film (2) exhibits inverse wavelength dispersion characteristics.

[0093] Re(450) / Re(550) in the second phase difference film (2) is, for example, 1 or less, preferably less than 0.9, and more preferably 0.85 or less. Meanwhile, Re(450) / Re(550) in the second phase difference film (2) is, for example, 0.7 or more, and preferably 0.75 or more.

[0094] If Re(450) / Re(550) in the second phase difference film is within this range, it can function as a λ / n plate regardless of the wavelength of the measurement light. For example, if it is a λ / n plate, it functions as a λ / n plate at any wavelength, so good anti-reflection properties can be provided at any wavelength.

[0095] The second phase difference film (2) may have a single-layer structure or a laminated structure.

[0096] The second phase difference film (2) typically comprises a stretched film prepared by stretching a film composed of a transparent resin and / or a liquid crystal alignment solidification layer.

[0097] In one embodiment, the second phase difference film (2) includes a liquid crystal alignment solidification layer. More specifically, the second phase difference film (2) has a laminated structure including a plurality of liquid crystal alignment solidification layers. In the illustrated example, the second phase difference film (2) has a first liquid crystal alignment solidification layer (21), an adhesive layer (23), and a second liquid crystal alignment solidification layer (22) in this order.

[0098] The thickness of the second phase difference film (2) is arbitrarily and appropriately adjusted so that a desired phase difference is obtained.

[0099] In one embodiment, the thickness of the second phase difference film (2) is greater than the thickness of the first phase difference film (1).

[0100] The thickness of the second phase difference film (2) is, for example, 1.5 times or more than the thickness of the first phase difference film (1), and preferably 2 times or more. Meanwhile, the thickness of the second phase difference film (2) is, for example, 6 times or less than the thickness of the first phase difference film (1), and preferably 4 times or less.

[0101] The thickness of the second phase difference film (2) is, for example, 0.5㎛ to 20㎛, preferably 1.0㎛ to 10㎛, and more preferably 2.0㎛ to 5.0㎛.

[0102] If the second phase difference film has such a thickness, the thinning of the optical laminate can be reliably achieved, while simultaneously providing the optical laminate with sufficient handling properties, namely self-support and process fluidity. In addition, since the center of gravity of the polarizer can be raised in the stacking direction of the optical laminate, damage to the image display device can be reduced even if the polarizer expands and contracts during durability testing.

[0103] In one embodiment, the second phase difference film (2) is attached to the polarizer (3) via the second adhesive layer (5). In other words, the optical laminate (100) further comprises the second adhesive layer (5). In the illustrated example, the second adhesive layer (5) is in contact with the polarizer (3) and the first liquid crystal alignment solidification layer (21).

[0104] The thickness of the second adhesive layer (5) is, for example, 2.0 μm or less, preferably 1.2 μm or less, more preferably 0.8 μm or less, even more preferably less than 0.5 μm, even more preferably 0.12 μm or less, particularly preferably 0.05 μm or less, and most preferably 0.04 μm or less.

[0105] If the thickness of the second adhesive layer is below this upper limit, the second adhesive layer can be made sufficiently thin with respect to the wavelength of visible light. Therefore, even if the second phase difference film includes a liquid crystal alignment solidification layer, light interference in the optical laminate can be sufficiently suppressed. As a result, the occurrence of interference stains in an image display device equipped with an optical laminate can be reliably suppressed.

[0106] Meanwhile, the thickness of the second adhesive layer (5) is, for example, 0.001 μm or more, preferably 0.005 μm or more, and more preferably 0.01 μm or more.

[0107] If the thickness of the second adhesive layer is greater than or equal to this lower limit, the adhesive strength of the second adhesive layer can be improved, and layers adjacent to the second adhesive layer (typically a polarizer and a second phase difference film) can be stably laminated.

[0108] The range of the refractive index of the second adhesive layer (5) in the transmission axis direction is, for example, the same as the range of the refractive index of the first adhesive layer (4) mentioned above. In addition, the range of the absolute value of the difference between the refractive index of the second adhesive layer (5) in the transmission axis direction and the refractive index of the second phase difference film (2) (typically the first liquid crystal alignment solidification layer (21)) is, for example, the same as the range of the absolute value of the difference between the refractive index of the first adhesive layer (4) mentioned above and the refractive index of the first phase difference film (1).

[0109] If the difference in refractive index between the second adhesive layer and the second phase difference film is within this range, even if the second adhesive layer and the second phase difference film are adjacent to each other, light (visible light) incident on the optical laminate can be reliably suppressed from being reflected at the interface between the second adhesive layer and the second phase difference film.

[0110] The second adhesive layer (5) may be an adhesive layer composed of an adhesive, or an adhesive layer composed of a pressure-sensitive adhesive.

[0111] In one embodiment, the second adhesive layer (5) is a second adhesive layer (51) composed of an adhesive (more specifically, a cured product of the adhesive). In one embodiment, since the thickness of the second adhesive layer (51) is within the above-mentioned range, the degree of curing shrinkage of the adhesive, coating stains, coating clumping, drying stains, etc., can be sufficiently reduced, and the occurrence of bending and / or thickness non-uniformity in the second adhesive layer can be significantly suppressed. Accordingly, non-uniformity of the optical path length in the optical laminate can be reduced, and interference stains in the image display device can be suppressed more stably.

[0112] In one embodiment, the optical laminate (100) further comprises an adhesive layer (6). The adhesive layer (6) is located on the side opposite to the polarizer (3) with respect to the second phase difference film (2). In the illustrated example, the adhesive layer (6) is laminated on the surface opposite to the first liquid crystal alignment solidification layer (21) in the second liquid crystal alignment solidification layer (22).

[0113] According to this configuration, the optical laminate can be bonded to any suitable substrate (typically an image display panel) equipped with an image display device by means of an adhesive layer (6).

[0114] The thickness of the adhesive layer (6) is, for example, 3 μm or more, preferably 5 μm or more, and preferably 10 μm or more. Meanwhile, the thickness of the adhesive layer (6) is, for example, 50 μm or less, preferably 30 μm or less, and more preferably 20 μm or less.

[0115] In the stacking direction of the optical laminate (100), the dimension from the surface opposite to the polarizer (3) in the first phase difference film (1) to the surface opposite to the polarizer (3) in the second phase difference film (2) is, for example, 20 μm or less, preferably less than 15 μm, more preferably 12 μm or less, even more preferably less than 10 μm, and even more preferably 9.5 μm or less.

[0116] According to this configuration, the thinning of the optical laminate can be reliably achieved.

[0117] In addition, in the stacking direction of the optical laminate (100), the dimension from the surface opposite to the polarizer (3) in the first phase difference film (1) to the surface opposite to the second phase difference film (2) in the adhesive layer (6) is, for example, 40 μm or less, preferably less than 35 μm, more preferably 30 μm or less, even more preferably less than 25 μm, and even more preferably 24.5 μm or less.

[0118] According to this configuration, the thinning of the optical laminate can be achieved more stably.

[0119] B. Details of the optical laminate

[0120] Next, with reference to FIG. 1, details of an optical laminate according to one embodiment will be described.

[0121] As shown in FIG. 1, in one embodiment, the optical laminate (100) comprises a first phase difference film (1), a first adhesive layer (41), a polarizer (3), a second adhesive layer (51), and a second phase difference film (2) in this order.

[0122] B-1. First phase difference film

[0123] In one embodiment, the first phase difference film (1) has a single-layer structure of a liquid crystal alignment solidification layer.

[0124] In this first phase difference film (1), rod-shaped liquid crystal compounds are oriented in a state arranged in a predetermined direction of the first phase difference film (1) (homogeneous orientation).

[0125] Examples of liquid crystal compounds include, for instance, liquid crystal compounds in which the liquid crystal phase is the nematic phase (nematic liquid crystals). Examples of such liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. Liquid crystal polymers and liquid crystal monomers may each be used individually or in combination.

[0126] The mechanism of liquid crystallization of a liquid crystal compound may be lyotropic or thermotropic.

[0127] When a liquid crystal compound includes a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. By polymerizing or crosslinking (i.e., curing) the liquid crystal monomer, the orientation state of the liquid crystal monomer can be fixed. After orienting the liquid crystal monomer, for example, by polymerizing or crosslinking the liquid crystal monomers together, the orientation state can be fixed. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by crosslinking, and these are non-liquid crystals. Therefore, the formed liquid crystal orientation solidified layer does not undergo a transition to a liquid crystal phase, glass phase, or crystalline phase due to temperature changes characteristic of, for example, liquid crystal compounds. As a result, the first phase difference film can have extremely excellent stability that is not affected by temperature changes.

[0128] Any suitable liquid crystal monomer may be used. Examples of liquid crystal monomers include polymerizable mesogen compounds described in Japanese Patent Application Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445, etc.

[0129] Specific examples of such polymerizable mesogen compounds include BASF’s trade name LC242, Merck’s trade name E7, and Wacker-Chem’s trade name LC-Sillicon-CC3767.

[0130] A liquid crystal alignment solidification layer can be formed by performing any suitable alignment treatment on any suitable coating substrate, then coating the surface with a coating solution containing a liquid crystal compound to orient the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the orientation state.

[0131] Orientation treatments include, for example, mechanical orientation, physical orientation, and chemical orientation.

[0132] Specific examples of liquid crystal compounds and details of a method for forming an orientation solidification layer are described in Japanese Patent Publication No. 2006-163343. The description in said publication is incorporated herein by reference.

[0133] The birefringence Δn of the first phase difference film (1) (liquid crystal alignment solidification layer) is, for example, 0.06 or higher, preferably 0.08 or higher, more preferably 0.09 or higher, and even more preferably 0.10 or higher. Meanwhile, the upper limit of the birefringence Δn of the first phase difference film (1) (liquid crystal alignment solidification layer) is, for example, 0.13, and also, for example, 0.12. If Δn is within this range, a desired in-plane phase difference can be realized with a very thin thickness.

[0134] B-2. Polarizer

[0135] Any suitable polarizer is used as the polarizer (3). The polarizer may be composed of, for example, a single layer of resin film, or may be obtained using a laminate of two or more layers.

[0136] Specific examples of a polarizer composed of a single-layer resin film include a hydrophilic polymer film, such as a polyvinyl alcohol (PVA)-based resin film, a partially formalized PVA-based resin film, or a partially saponified ethylene-vinyl acetate copolymer-based film, to which a dyeing treatment with a dichroic substance such as iodine or a dichroic dye and a stretching treatment have been performed, and a polyene-based oriented film, such as a dehydrated PVA or a dehydrochlorinated polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA-based resin film with iodine and uniaxially stretching it is used, as it has excellent optical properties.

[0137] 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 applied and formed on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer applied and formed on the resin substrate can be manufactured by, for example, applying a PVA-based resin solution to a resin substrate and drying it to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In one embodiment, a polyvinyl alcohol-based resin layer comprising a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes stretching the laminate by immersing it in an aqueous boric acid solution. Additionally, the stretching may further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in an aqueous boric acid solution, if necessary. Furthermore, in one embodiment, preferably, the laminate is subjected to a drying shrinkage treatment that shrinks by 2% or more in the width direction by heating while conveying in the longitudinal direction. Typically, the manufacturing method of the present embodiment includes performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate in this order. By introducing assisted stretching, it becomes possible to increase the crystallinity of the PVA even when PVA is applied over a thermoplastic resin, thereby enabling the achievement of high optical properties. Additionally, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in orientation or dissolution of the PVA can be prevented when immersed in water during subsequent dyeing or stretching processes, thereby enabling the achievement of high optical properties.Furthermore, when the PVA-based resin layer is immersed in a liquid, the disturbance of the orientation of polyvinyl alcohol molecules and the deterioration of orientation can be suppressed compared to the case where the PVA-based resin layer does not contain halogens. This allows for the improvement of the optical properties of a polarizer obtained through processing steps in which the laminate is immersed in a liquid, such as dyeing and underwater stretching. Additionally, optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment. The obtained 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 the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer according to the purpose may be laminated onto the peeled surface for use. Details of such a method for manufacturing a polarizer are described, for example, in Japanese Patent Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0138] The above iodine dyeing is performed, for example, by immersing a PVA-based resin film in an aqueous iodine solution. The stretching ratio of the above uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. In addition, dyeing may be performed after stretching. If necessary, swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc., are performed on the PVA-based resin film. For example, by immersing the PVA-based resin film in water and washing it before dyeing, not only can contamination or anti-blocking agents on the surface of the PVA-based resin film be washed, but the PVA-based resin film can also be swollen to suppress dye stains.

[0139] The polarizer (3) typically exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single-body transmittance of the polarizer (3) is, for example, 41.5% or more, preferably 43.0% or more, and more preferably 44.5% or more. Meanwhile, the upper limit of the single-body transmittance of the polarizer (3) is typically 46.0%.

[0140] The polarization degree of the polarizer (3) is, for example, 97.0% or more, preferably 99.0% or more, and more preferably 99.9% or more.

[0141] The average refractive index of the polarizer (3) is, for example, 1.40 to 1.65, preferably 1.45 to 1.60, and more preferably 1.50 to 1.60.

[0142] B-3. ​​Second phase difference film

[0143] In one embodiment, the second phase difference film (2) comprises a first liquid crystal alignment solidification layer (21), an adhesive layer (23), and a second liquid crystal alignment solidification layer (22).

[0144] B-3-1. First liquid crystal alignment solidification layer

[0145] The first liquid crystal alignment solidification layer (21) may have an in-plane phase difference or a thickness direction phase difference. The first liquid crystal alignment solidification layer (21) may function as a λ / 4 plate, or as a λ / 2 plate, λ / 5 plate, λ / 6 plate, or C-plate.

[0146] In one embodiment, the first liquid crystal alignment solidification layer (21) has an in-plane phase difference. In this case, the refractive index of the first liquid crystal alignment solidification layer (21) preferably exhibits the relationship nx > ny ≥ nz.

[0147] In another embodiment, the first liquid crystal alignment solidification layer (21) has a phase difference in the thickness direction and substantially has no in-plane phase difference. In this case, the refractive index of the first liquid crystal alignment solidification layer (21) exhibits a relationship such as nx=ny, and preferably an nz > nx=ny relationship. Furthermore, in this specification, 'nx=ny' includes not only cases where nx and ny are completely identical, but also cases where they are substantially identical. Accordingly, within a range that does not impair the effects of the present invention, there may be cases where nx > ny or nx < ny.

[0148] The refractive index of the first liquid crystal alignment solidification layer (21) in the transmission axis direction is, for example, 1.45 or higher, and also, for example, 1.50 or higher, and also, for example, 1.55 or higher, and also, for example, exceeds 1.60, and also, for example, 1.61 or higher. Meanwhile, the upper limit of the refractive index of the first liquid crystal alignment solidification layer (21) in the transmission axis direction is, for example, 1.70.

[0149] The thickness of the first liquid crystal alignment solidification layer (21) is arbitrarily and appropriately adjusted so that a desired phase difference is obtained.

[0150] The thickness of the first liquid crystal alignment solidification layer (21) is, for example, 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 2 μm or less. Meanwhile, the lower limit of the thickness of the first liquid crystal alignment solidification layer (21) is typically 1 μm.

[0151] The liquid crystal compound included in the first liquid crystal alignment solidification layer (21) is described in the same way as the liquid crystal compound provided by the first phase difference film (1). Accordingly, the description of the liquid crystal compound included in the first liquid crystal alignment solidification layer (21) is appropriately omitted.

[0152] B-3-2. Second liquid crystal alignment solidification layer

[0153] The second liquid crystal alignment solidification layer (22) is located on the side opposite to the polarizer (3) with respect to the first liquid crystal alignment solidification layer (21) in the stacking direction of the optical laminate (100). In one embodiment, the second liquid crystal alignment solidification layer (22) is attached to the first liquid crystal alignment solidification layer (21) via an adhesive layer (23).

[0154] The second liquid crystal alignment solidification layer (22) may have an in-plane phase difference or a thickness direction phase difference. The second liquid crystal alignment solidification layer (22) may function as a λ / 4 plate, or as a λ / 2 plate, λ / 5 plate, λ / 6 plate, or C-plate.

[0155] The second liquid crystal alignment solidification layer (22) is described in the same way as the first liquid crystal alignment solidification layer (21) described above. Therefore, a detailed description of the second liquid crystal alignment solidification layer (22) is appropriately omitted.

[0156] The refractive index of the second liquid crystal alignment solidification layer (22) may have a relationship of nx > ny or a relationship of nx = ny.

[0157] In one embodiment, the refractive indices of the first liquid crystal alignment solidification layer (21) and the second liquid crystal alignment solidification layer (22) respectively exhibit a relationship of nx > ny. According to this configuration, wavelength dispersion characteristics better than those of the second phase difference film can be achieved. Additionally, viewing angle characteristics, that is, optical characteristics for any azimuth angle and polar angle, can also be improved.

[0158] The respective ranges of phase difference, refractive index, and thickness in the second liquid crystal alignment solidification layer (22) are, for example, the same as the respective ranges of phase difference, refractive index, and thickness in the first liquid crystal alignment solidification layer (21) described above.

[0159] B-3-3. Combination of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer

[0160] In one embodiment, the first liquid crystal alignment solidification layer (21) functions as a λ / 2 plate, and the second liquid crystal alignment solidification layer (22) functions as a λ / 4 plate. Additionally, the first liquid crystal alignment solidification layer (21) may function as a λ / 4 plate, and the second liquid crystal alignment solidification layer (22) may function as a λ / 2 plate. When the combination of two phase difference films is a λ / 2 plate and a λ / 4 plate, it may be referred to as the first combination.

[0161] According to this configuration, the wavelength dispersion characteristics of the second phase difference film, which has a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer, can be made close to ideal inverse wavelength dispersion characteristics. Accordingly, excellent anti-reflection characteristics can be imparted to the optical laminate.

[0162] In the first combination, the in-plane phase difference Re (550) of the liquid crystal alignment solidification layer functioning as a λ / 4 plate is, for example, 90 nm to 180 nm, preferably 100 nm to 160 nm, and more preferably 110 nm to 150 nm.

[0163] In the first combination, the in-plane phase difference Re (550) of the liquid crystal alignment solidification layer functioning as a λ / 2 plate is, for example, 200 nm to 300 nm, preferably 220 nm to 290 nm, and more preferably 230 nm to 280 nm.

[0164] In the first combination, the angle formed by the absorption axis direction of the polarizer (3) and the ground axis direction of the first liquid crystal alignment solidification layer (21) is, for example, 10° to 20°, preferably 12° to 18°, and more preferably 14° to 16°.

[0165] In addition, in the first combination, the angle formed by the absorption axis direction of the polarizer (3) and the ground axis direction of the second liquid crystal alignment solidification layer (22) is, for example, 70° to 80°, preferably 72° to 78°, and more preferably 74° to 76°.

[0166] In addition, in the first combination, the range of the angle formed by the absorption axis direction of the polarizer and the ground axis direction of the first liquid crystal alignment solidification layer, and the range of the angle formed by the absorption axis direction of the polarizer and the ground axis direction of the second liquid crystal alignment solidification layer may be reversed.

[0167] With this configuration, the wavelength dispersion characteristics of the second phase difference film, which has a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer, can be made closer to ideal inverse wavelength dispersion characteristics. Accordingly, excellent anti-reflection characteristics can be reliably imparted to the optical laminate.

[0168] The first liquid crystal alignment solidification layer (21) may function as a λ / 4 plate, and the second liquid crystal alignment solidification layer (22) may function as a C-plate (i.e., nx=ny). Additionally, the first liquid crystal alignment solidification layer (21) may function as a C-plate, and the second liquid crystal alignment solidification layer (22) may function as a λ / 4 plate. When the combination of two phase difference films is a λ / 4 plate and a C-plate, it is sometimes referred to as the second combination. Even with such a configuration, excellent anti-reflection properties can be imparted to the optical laminate.

[0169] However, the first combination described above is more preferable than the second combination. If the combination of two phase difference films is a λ / 2 plate and a λ / 4 plate, interference stains in an image display device equipped with an optical laminate can be reliably reduced.

[0170] In the second combination, the in-plane phase difference Re (550) of the liquid crystal alignment solidification layer functioning as a λ / 4 plate is, for example, 90 nm to 190 nm, preferably 100 nm to 170 nm, and more preferably 110 nm to 160 nm.

[0171] In the second combination, the range of the phase difference Rth (550) in the thickness direction of the liquid crystal alignment solidification layer functioning as a C-plate is, for example, -200 nm or more and 200 nm or less, preferably -200 nm or more and less than 0 nm, and more preferably -140 nm or more and -100 nm or less.

[0172] In the second combination, the angle formed by the ground axis direction of the liquid crystal alignment solidification layer functioning as a λ / 4 plate and the absorption axis direction of the polarizer (3) is arbitrarily and appropriately adjusted.

[0173] Even with this configuration, excellent anti-reflection properties can be reliably imparted to the optical laminate.

[0174] B-3-4. Adhesive layer

[0175] The adhesive layer (23) is located between the first liquid crystal alignment solidification layer (21) and the second liquid crystal alignment solidification layer (22) in the stacking direction of the optical laminate (100), and bonds the first liquid crystal alignment solidification layer (21) and the second liquid crystal alignment solidification layer (22). The adhesive layer (23) is in contact with each of the first liquid crystal alignment solidification layer (21) and the second liquid crystal alignment solidification layer (22).

[0176] In one embodiment, the contact surface with the adhesive layer (23) in the first liquid crystal alignment solidification layer (21) and / or the contact surface with the adhesive layer (23) in the second liquid crystal alignment solidification layer (22) is an activated surface in which an activation treatment is performed. According to this configuration, polar groups such as hydroxyl groups can be introduced to the surface of the liquid crystal alignment solidification layer, and as a result, the adhesion between the liquid crystal alignment solidification layer and the adhesive layer can be improved.

[0177] Examples of activation treatments include corona treatment, plasma treatment, saponification treatment, and low-pressure UV treatment. Activation treatments can be performed alone or in combination.

[0178] The adhesive layer (23) is described, for example, in the same way as the first adhesive layer (4) described above. Therefore, the description of the adhesive layer (23) is appropriately omitted.

[0179] The thickness range of the adhesive layer (23) is, for example, the same as the thickness range of the first adhesive layer (4) mentioned above.

[0180] The range of the refractive index of the adhesive layer (23) in the direction of the transmission axis is, for example, the same as the range of the refractive index of the first adhesive layer (4) mentioned above. In addition, the range of the absolute value of the difference between the refractive index of the adhesive layer (23) in the direction of the transmission axis and the refractive index of the liquid crystal alignment solidification layer (first liquid crystal alignment solidification layer (21) or second liquid crystal alignment solidification layer (22)) is, for example, the same as the range of the absolute value of the difference between the refractive index of the first adhesive layer (4) mentioned above and the refractive index of the first phase difference film (1).

[0181] The adhesive layer (23) may be an adhesive layer composed of adhesive or an adhesive layer composed of adhesive.

[0182] In one embodiment, the adhesive layer (23) is an adhesive layer (231) composed of an adhesive (more specifically, a cured product of the adhesive). The adhesive layer (231) provided by the second phase difference film (2) is described in the same way as the first adhesive layer (41) and the second adhesive layer (51), respectively. Accordingly, a detailed description of the adhesive layer (231) is omitted.

[0183] B-4. First adhesive layer and second adhesive layer

[0184] The first adhesive layer (41) (the first adhesive layer (4)) is located between the first phase difference film (1) and the polarizer (3) in the stacking direction of the optical laminate (100), and laminates the first phase difference film (1) and the polarizer (3).

[0185] The second adhesive layer (51) (the second adhesive layer (5)) is located between the polarizer (3) and the second phase difference film (2) in the stacking direction of the optical laminate (100) and laminates the polarizer (3) and the second phase difference film (2). In the illustrated example, the second adhesive layer (51) laminates the polarizer (3) and the first liquid crystal alignment solidification layer (21).

[0186] The first adhesive layer (41) and the second adhesive layer (51) are described in the same way, except for their arrangement in the optical laminate (100). Additionally, below, when the first adhesive layer (41) and the second adhesive layer (51) are not distinguished from each other, they may simply be referred to as adhesive layers.

[0187] The first adhesive layer (41) and / or the second adhesive layer (51) comprises a cured product of any suitable adhesive.

[0188] Examples of adhesives include curing adhesives such as water-based adhesives, thermosetting adhesives, moisture-curing adhesives, and ultraviolet-curing adhesives (UV adhesives), and preferably, water-based adhesives and UV adhesives.

[0189] The adhesive can be used alone or in combination.

[0190] In one embodiment, the first adhesive layer (41) and / or the second adhesive layer (51) comprises a cured product of a water-based adhesive. If the adhesive layer comprises a cured product of a water-based adhesive, the thickness of the adhesive layer can be stably adjusted to the above-mentioned range, thereby sufficiently suppressing the occurrence of interference stains in the optical laminate.

[0191] Water-based adhesives before curing typically contain a curing component and a solvent containing water.

[0192] The curing component can be dissolved and / or dispersed in a solvent, typically.

[0193] The curing component can be cured by any suitable chemical reaction. Examples of curing components include a combination of polyvinyl alcohol (PVA) and a crosslinking agent, and an organic silane compound. The curing component may be used alone or in combination.

[0194] A water-based adhesive containing PVA and a crosslinking agent as curing components may be referred to as a PVA-containing water-based adhesive below.

[0195] A crosslinking agent can crosslink PVA to cure water-based adhesives. Examples of crosslinking agents include melamine resins such as methylolmelamine; alkylenediamines; isocyanates; epoxy compounds; and aldehydes. Crosslinking agents can be used alone or in combination.

[0196] The content ratio of the crosslinking agent in the water-based adhesive is, for example, 10 to 50 parts by mass per 100 parts by mass of PVA, and preferably 20 to 40 parts by mass.

[0197] The PVA-containing water-based adhesive may further include a metal compound colloid in addition to PVA and a crosslinking agent.

[0198] Metal compound colloids consist of fine particles of a metal compound dispersed in a solvent; they are electrostatically stabilized due to the mutual repulsion of homogeneous charges of the fine particles and can maintain permanent stability.

[0199] Examples of metal compounds include metal oxides such as alumina, silica, zirconia, and titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; and minerals such as cerite, talc, clay, and kaolin. Metal compounds may be used alone or in combination.

[0200] The average particle size of the fine particles forming the metal compound colloid is arbitrarily and appropriately adjusted. The average particle size of the fine particles is, for example, 1 nm to 100 nm, and preferably 1 nm to 50 nm. If the average particle size of the fine particles is within this range, the fine particles can be uniformly dispersed within the adhesive layer.

[0201] The content ratio of metal compound colloids in water-based adhesives is arbitrarily and appropriately adjusted.

[0202] A water-based adhesive containing an organic silane compound as a curing component may be referred to as an organic silane-containing water-based adhesive below.

[0203] Organic silane compounds typically possess alkoxysilyl groups and / or silanol groups (hydroxysilyl groups). If an organic silane compound possesses alkoxysilyl groups and / or silanol groups, it can cure water-based adhesives through a dehydration condensation reaction.

[0204] As an organic silane compound, examples include silane coupling agents having an alkoxysilyl group and / or a silanol group and an organic functional group.

[0205] Examples of organic functional groups possessed by the silane coupling agent include amino groups, epoxy groups, and methoxy groups. The silane coupling agent may have one type of organic functional group or a combination of two or more types of organic functional groups. If the silane coupling agent possesses such organic functional groups, the adhesive strength of the adhesive layer can be improved.

[0206] These silane coupling agents can be used alone or in combination.

[0207] In one embodiment, the organosilicon compound comprises an amino-based silane coupling agent containing an amino group and / or an epoxy-based silane coupling agent containing an epoxy group. According to this composition, the adhesion strength of the adhesive layer can be improved and the adhesive layer can be made thinner.

[0208] Amino-based silane coupling agents have any suitable structure having an amino group, an alkoxysilyl group and / or a silanol group.

[0209] As an amino-based silane coupling agent, for example, N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and hydrochloride salts thereof Can be lifted.

[0210] Any suitable commercially available product can be used as an amino-based silane coupling agent.

[0211] Examples of commercially available amino-based silane coupling agents include KBM-602, KBM-603, KBM-903, KBE-603, KBE-903, X-12-972F (all manufactured by Shin-Etsu Chemical Co., Ltd.), Z-6011, Z-6020, Z-6026, Z-6032, Z-6094, Z-6610 (all manufactured by Toray Dow Corning Co., Ltd.), A-1100, A-1110, A-1120, A-2120, Y-9669 (all manufactured by Momentive Performance Materials Co., Ltd.).

[0212] Epoxy-based silane coupling agents have any suitable structure having an epoxy group, an alkoxysilyl group, and / or a silanol group.

[0213] Examples of epoxy-based silane coupling agents include 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0214] Any suitable commercially available product can be used as an epoxy-based silane coupling agent.

[0215] Examples of commercially available epoxy-based silane coupling agents include KBM-303, KBM-402, KBM-403, KBE-402, KBE-403, KR-516, X-12-981S (all manufactured by Shin-Etsu Chemical Co., Ltd.), SH6040, Z-6040, Z-6042, Z-6043, Z-6044 (all manufactured by Toray Dow Corning Co., Ltd.), and A-186, A-187, A-1871 (all manufactured by Momentive Performance Materials Co., Ltd.).

[0216] When the organosilicon compound includes an amino-based silane coupling agent and an epoxy-based silane coupling agent, the amino group of the amino-based silane coupling agent and the epoxy group of the epoxy-based silane coupling agent can react. Therefore, the water-based adhesive can be stably cured, and further thinning of the adhesive layer can be achieved.

[0217] The molar ratio of the amino-based silane coupling agent to the epoxy-based silane coupling agent (amino-based silane coupling agent:epoxy-based silane coupling agent) is, for example, 8:92 to 60:40, and preferably 10:90 to 55:45.

[0218] If the molar ratio of the amino-based silane coupling agent and the epoxy-based silane coupling agent is within this range, the adhesive layer can be thinned more stably.

[0219] The content ratio of the curing component in the water-based adhesive is, for example, less than 50 mass%, preferably 40 mass% or less, more preferably 30 mass% or less, even more preferably 20 mass% or less, even more preferably 10 mass% or less, particularly preferably 5 mass% or less, and most preferably 2 mass% or less.

[0220] Meanwhile, the content ratio of the curing component in the water-based adhesive is, for example, 0.01 mass% or more, preferably 0.1 mass% or more, more preferably 0.3 mass% or more, even more preferably 0.4 mass% or more, and even more preferably 0.5 mass% or more.

[0221] The solvent of the water-based adhesive contains water as described above.

[0222] The solvent may include an organic solvent in addition to water.

[0223] Examples of organic solvents include esters, ketones, cyclic ethers, aliphatic or alicyclic hydrocarbons, aromatic hydrocarbons, aliphatic or alicyclic alcohols, glycol ethers, and glycol ether acetates.

[0224] Organic solvents can be used alone or in combination.

[0225] The water content in the solvent of the water-based adhesive is, for example, 50 mass% or more, preferably 80 mass% or more, and more preferably 95 mass% or more. Meanwhile, the upper limit of the water content in the solvent is typically 100 mass%.

[0226] In one embodiment, the solvent of the water-based adhesive substantially does not contain an organic solvent. In other words, the water content in the solvent is, for example, 98 mass% or more and 100 mass% or less.

[0227] If the water content ratio in the solvent of the water-based adhesive is within this range, the solvent can be smoothly evaporated when the water-based adhesive is applied and dried, thereby enabling stable thinning of the adhesive layer. In addition, since water causes minimal damage to the polarizer and phase difference film, an optical laminate of excellent quality can be stably manufactured.

[0228] The solvent content ratio in water-based adhesives is arbitrarily and appropriately adjusted according to the content ratio of the curing component.

[0229] Water-based adhesives contain any suitable additives as needed.

[0230] Examples of additives include amino compounds, epoxy compounds, binder resins, surfactants, plasticizers, adhesion promoters, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, titanium coupling agents, inorganic or organic fillers, metal powders, granular materials, and foil-like materials.

[0231] Additives may be used alone or in combination.

[0232] Among the additives, surfactants are preferably included.

[0233] The content ratio of the additive is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, and particularly preferably 0.5 parts by mass or less, with respect to 1 part by mass of the curing component. Meanwhile, the lower limit of the content ratio of the additive is, typically, 0 parts by mass with respect to 1 part by mass of the curing component.

[0234] In one embodiment, each of the first adhesive layer (41) and the second adhesive layer (51) comprises a cured product of the above-described water-based adhesive. According to this configuration, each of the first adhesive layer and the second adhesive layer can be sufficiently thinned, and as a result, non-uniformity of the optical path length in the optical laminate can be significantly suppressed.

[0235] In this case, the cured product of the water-based adhesive included in the first adhesive layer (41) and the cured product of the water-based adhesive included in the second adhesive layer (51) may be the same or different from each other.

[0236] In one embodiment, the cured product of the water-based adhesive included in the first adhesive layer (41) and the cured product of the water-based adhesive included in the second adhesive layer (51) are the same. Thus, the refractive index of the first adhesive layer (41) in the transmission axis direction and the refractive index of the second adhesive layer (51) in the transmission axis direction can be adjusted to be substantially the same.

[0237] In addition, the adhesive layer (231) provided by the second phase difference film (2) may include a cured product of the above-mentioned water-based adhesive. By doing so, the second phase difference film can be made thin.

[0238] In addition, these adhesive layers (first adhesive layer (41), second adhesive layer (51) and / or adhesive layer (231)) do not substantially contain the aforementioned solvent because the solvent volatilizes during the formation process. The solvent content ratio in the adhesive layer is, for example, 0.05 mass% or less, and preferably 0.01 mass% or less.

[0239] B-5. Adhesive layer

[0240] In one embodiment, the optical laminate (100) has an adhesive layer (6). In the illustrated example, the adhesive layer (6) is laminated on the surface opposite to the first liquid crystal alignment solidification layer (21) in the second liquid crystal alignment solidification layer (22).

[0241] The adhesive layer (6) is composed of any suitable adhesive.

[0242] Examples of adhesives include (mat)acrylic adhesives, urethane adhesives, and silicone adhesives.

[0243] The adhesive can be used alone or in combination.

[0244] Among adhesives, (meth)acrylic adhesives are preferably used.

[0245] B-6. Release Liner

[0246] The optical laminate (100) may further be provided with a release liner (7). The release liner (7) is attached to the surface opposite to the second phase difference film (2) in the adhesive layer (6). Typically, the release liner (7) is attached to the adhesive layer (6) until the optical laminate is attached to the substrate, and is peeled off from the adhesive layer (6) when the optical laminate is attached.

[0247] The peel liner (7) comprises any suitable resin material. Examples of resin materials include polyethylene terephthalate (PET), polyethylene, and polypropylene.

[0248] Resin materials can be used alone or in combination.

[0249] In one embodiment, a release treatment layer is provided on the contact surface with the adhesive layer (6) in the peel liner (7).

[0250] The release treatment layer typically includes a release agent.

[0251] Examples of release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents, preferably silicone-based release agents, and more preferably vinyl group-containing addition-type silicones.

[0252] Release agents can be used alone or in combination.

[0253] The thickness of the release treatment layer is, for example, 50 nm to 400 nm.

[0254] B-7. Other Optical Films

[0255] The optical laminate (100) may have other optical films in addition to the first phase difference film (1), polarizer (3), and second phase difference film (2).

[0256] Other optical films may include, for example, protective films, ultraviolet light transmission suppression films, and infrared light transmission suppression films. Other optical films may have a single-layer structure comprising these alone, or a laminated structure in which two or more of these are laminated.

[0257] Other optical films are attached to the surface opposite to the polarizer (3) in the first phase difference film (1), for example, by interposing any suitable adhesive layer or adhesive layer.

[0258] C. Method for manufacturing an optical laminate

[0259] Next, a method for manufacturing an optical laminate (100) according to one embodiment will be described.

[0260] In one embodiment, a method for manufacturing an optical laminate comprises a process of laminating a first phase difference film (1) and a polarizer (3) (a first lamination process) and a process of laminating a polarizer (3) and a second phase difference film (2) (a second lamination process). In one embodiment, a method for manufacturing an optical laminate comprises the first lamination process and the second lamination process in this order.

[0261] C-1. First bonding process

[0262] In one embodiment, first, the above-described first phase difference film (1) and polarizer (3) are prepared. Each of the first phase difference film (1) and polarizer (3) preferably has a long, narrow shape.

[0263] In addition, when the first phase difference film (1) includes a liquid crystal alignment solidification layer, the liquid crystal alignment solidification layer is prepared in a state supported on a coated substrate. In addition, the polarizer (3) is typically prepared in a state supported on a resin substrate.

[0264] Next, the first phase difference film (1) and the polarizer (3) are bonded together by any suitable means.

[0265] In one embodiment, the first phase difference film (1) and the polarizer (3) are laminated by roll-to-roll.

[0266] More specifically, the adhesive described above is applied to the surface of the first phase difference film (1) and / or the surface of the polarizer (3) by any suitable method.

[0267] Examples of methods for applying adhesive include dip coating, curtain coating, spray coating, bar coating, rod coating, roll coating, die coating, and gravure coating, and preferably, gravure coating.

[0268] Next, the first phase difference film (1) and the polarizer (3) are overlapped with a film of adhesive in between. Then, the adhesive is cured by an appropriate method according to the adhesive.

[0269] For example, if the adhesive includes a water-based adhesive, the adhesive film is heated and dried.

[0270] The heating temperature is, for example, 35°C to 120°C. The heating time is, for example, 30 seconds to 10 minutes. At this time, the solvent contained in the coating film volatilizes, and the curing component contained in the coating film is cured. Thus, a first adhesive layer (41) containing a cured product of a water-based adhesive is formed, and the first phase difference film (1) and the polarizer (3) are bonded together by the adhesive layer (41).

[0271] Additionally, if the first phase difference film (1) includes a liquid crystal alignment solidification layer, the coated substrate is peeled off and removed from the liquid crystal alignment solidification layer as needed. Additionally, if the polarizer (3) is supported on the resin substrate, the resin substrate is peeled off and removed from the polarizer (3) as needed.

[0272] Thus, an intermediate laminate having a laminated structure of a first phase difference film (1) / first adhesive layer (41) / polarizer (3) is prepared.

[0273] C-2. Second bonding process

[0274] In addition, the above-mentioned second optical film (2) is prepared. The second phase difference film (2) preferably has a long shape.

[0275] Next, the intermediate laminate prepared in the first lamination process described above and the second phase difference film (2) are laminated by any suitable means.

[0276] In one embodiment, an intermediate laminate and a second optical film (2) are laminated by roll-to-roll.

[0277] More specifically, the adhesive described above is applied to the surface of the polarizer (3) in the intermediate laminate and / or to the surface of the polarizing plate (3) by any suitable method. As a method of applying the adhesive, for example, an application method similar to the first bonding process described above may be cited.

[0278] Next, the intermediate laminate and the second phase difference film (2) are overlapped with a film of adhesive in between. Then, the adhesive is cured by a method suitable for the adhesive.

[0279] For example, if the adhesive includes a water-based adhesive, the adhesive film is heated and dried in the same manner as above. At this time, the solvent contained in the film volatilizes, and the curing component contained in the film is also cured. Thus, a second adhesive layer (51) containing the cured product of the water-based adhesive is formed, and the polarizer (3) and the second optical film (2) are laminated by the second adhesive layer (51).

[0280] By the above, an optical laminate (100) having a laminated structure of a first optical film (1) / first adhesive layer (41) / polarizer (3) / second adhesive layer (51) / second phase difference film (2) is prepared.

[0281] Afterwards, if necessary, the adhesive described above may be applied by any suitable method to the surface opposite to the polarizer (3) in the second phase difference film (2) to form an adhesive layer (6).

[0282] D. Image display device

[0283] The optical laminates described in paragraphs A to C above can be applied to any suitable image display device. Accordingly, one embodiment of the present invention also includes an image display device using such an optical laminate. Examples of image display devices include liquid crystal display devices and organic EL display devices, and preferably, organic EL display devices.

[0284] An image display device according to an embodiment of the present invention comprises an image display panel and the optical laminate (100) described above.

[0285] An image display panel typically includes an image display cell.

[0286] The optical laminate (100) is positioned on the viewing side of the image display panel. The optical laminate (100) is typically attached to the image display panel by an adhesive layer (6). In the image display device, the first phase difference film (1) is located on the viewing side with respect to the polarizer (3), that is, on the side opposite to the image display panel, and the second phase difference film (2) is located between the polarizer (3) and the image display panel.

[0287] The optical laminate (100) has any suitable shape according to the image display device to which it is applied. The size of the optical laminate (100) is also arbitrarily and appropriately adjusted.

[0288] In this image display device, since the first phase difference film of the optical laminate has the above-mentioned in-plane phase difference Re (450) and Re (450) / Re (550), visibility through a polarizing member (typically polarizing sunglasses) is excellent. In addition, since the optical laminate (100) is thin, the image display device can be miniaturized.

[0289] [Example]

[0290] The present invention will be specifically described below by way of examples, but the present invention is not limited by these examples. In addition, the method for measuring each characteristic is as follows.

[0291] (1) Measurement of phase difference

[0292] The phase difference of the phase difference film (liquid crystal alignment solidification layer) used in the examples and comparative examples was automatically measured using an Axoscan (manufactured by Axometrics). The measurement wavelength was 450 nm or 550 nm, and the measurement temperature was 25℃. The results are shown in Tables 1 and 2.

[0293] (2) Measurement of the thickness of the adhesive layer

[0294] The cross-sections of the optical laminates obtained in the examples and comparative examples were observed using a transmission electron microscope (TEM) by a freezing ultrathin sectioning method including heavy metal staining, using a Hitachi device named 'HT7820'. The acceleration voltage during measurement was set to 100 kV.

[0295] Thus, the thickness of the adhesive layer (adhesive layer) provided by the optical laminate was measured. The results are shown in Tables 1 and 2.

[0296] (3) Evaluation of sunglasses (visibility)

[0297] An organic EL display device (manufactured by Samsung, product number 'Galaxy A41') was disassembled to obtain an organic EL panel. An optical laminate obtained in the example and comparative example was attached to the organic EL panel by an adhesive layer to produce a test sample.

[0298] Next, a white image was displayed on an organic EL panel, and the color when the image was observed through polarized sunglasses was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0299] ○(Excellent): No noticeable discoloration was observed.

[0300] △ (Good): Slight discoloration was observed.

[0301] × (Defective): Clear discoloration was observed.

[0302] (4) Interference stain evaluation

[0303] An organic EL display device (manufactured by Samsung, Galaxy A41) was disassembled, and a cover glass and a polarizer were removed from the organic EL display device. Then, the optical laminates obtained in the examples and comparative examples were laminated to an organic EL panel using an adhesive layer to produce a sample.

[0304] Next, the obtained samples were placed under a fluorescent light, the organic EL panel was turned off, the samples were observed visually, and interference stains were evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0305] ○ (Excellent): No interference stains are visible.

[0306] △ (Possible): Interference stains are visible within a practically acceptable range.

[0307] (5) Overall evaluation

[0308] The optical laminates obtained in the examples and comparative examples were comprehensively evaluated according to the following criteria in terms of the sunglasses evaluation, the interference stain evaluation, and thickness. The results are shown in Tables 1 and 2.

[0309] Level 1: Sunglasses evaluation ○, interference stain evaluation ○, thickness 35㎛ or less.

[0310] Level 2: Sunglasses evaluation △, interference stain evaluation ○, thickness 35㎛ or less.

[0311] Level 3: Sunglasses evaluation ○, interference stain evaluation △, thickness 35㎛ or less.

[0312] Level 4: Sunglasses evaluation △, interference stain evaluation △, thickness 35㎛ or less.

[0313] Level 5: Sunglasses evaluation ×, interference stain evaluation △, thickness 35㎛ or less.

[0314] Level 6: Thickness exceeds 35㎛.

[0315] Preparation of Adhesives

[0316] <<Preparation Example 1>>

[0317] An aqueous solution of a silane coupling agent was prepared by adding an amino-based silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd., product name 'KBM-603') and an epoxy-based silane coupling agent (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd., product name 'KBM-403') to water.

[0318] In the aqueous solution of the silane coupling agent, the mass ratio of the amino-based silane coupling agent to the epoxy-based silane coupling agent was 1:1 (molar ratio 51.5:48.5), and the total concentration of the amino-based silane coupling agent and the epoxy-based silane coupling agent was 1.0 mass%.

[0319] After that, a water-based adhesive was prepared by adding 0.2 parts by mass of a surfactant (manufactured by Nisshin Kagaku Co., Ltd., product name 'EXP4200') to 100 parts by mass of an aqueous solution of a silane coupling agent.

[0320] <<Preparation Example 2>>

[0321] 25 parts by mass of acryloylmorpholine (product name 'ACMO', manufactured by KJ Chemicals), 10 parts by mass of ε-caprolactone 1 molar modified 2-hydroxyethyl acrylate (product name 'PLACCEL FA1DDM', manufactured by Daicel Chemicals), 10 parts by mass of lauryl acrylate (product name 'Light Acrylate L-A', manufactured by Kyoei Chemicals), 20 parts by mass of isostearyl acrylate (product name 'ISTA', manufactured by Osaka Yuki Chemicals), 15 parts by mass of 1,9-nonanediol diacrylate (product name 'Light Acrylate 1.9ND-A', manufactured by Kyoei Chemicals), 15 parts by mass of acrylic oligomer (product name 'ARUFON UP-1190', manufactured by Doa Gosei Chemicals), A UV-curing adhesive was prepared by stirring 1 part by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name 'Omnirad 819', manufactured by IGM Resins BV), 2 parts by mass of 1-hydroxycyclohexylphenyl ketone (product name 'Omnirad 184', manufactured by IGM Resins BV), and 2 parts by mass of diethylthioxantone (product name 'KAYACURE DETX-S', manufactured by Nippon Kayaku Co., Ltd.) at 50°C for 1 hour.

[0322] Preparation of Phase Difference Film

[0323] <<Preparation Example 3>>

[0324] 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 mass%.

[0325]

[0326] A liquid crystal coating solution was prepared by adding a surfactant (manufactured by Big Chem, 'BYK-361N') and a photopolymerization initiator (manufactured by IGM Resins, 'Omnirad 907') to this solution. The amount of surfactant added was 0.01 parts by mass per 100 parts by mass of the photopolymerizable liquid crystal compound. In addition, the amount of the polymerization initiator added was 3 parts by mass per 100 parts by mass of the photopolymerizable liquid crystal compound.

[0327] In addition, as a coating substrate, the surface of a polyethylene terephthalate (PET) film (thickness 38 μm) having a long shape was rubbed using a rubbing cloth and an orientation treatment was performed. The direction of the orientation treatment was set so that when laminated to a polarizer, it is at a 45° angle from the viewing side with respect to the absorption axis direction of the polarizer.

[0328] Next, the above-mentioned liquid crystal coating solution was coated onto the orientation treatment surface using a bar coater, and the liquid crystal compound was oriented by heating and drying at 100°C for 3 minutes. After cooling the liquid crystal layer thus formed to room temperature (25°C), an integrated light intensity of 400 mJ / cm² was applied under a nitrogen atmosphere. 2 The liquid crystal layer was cured by irradiating it with ultraviolet light. As a result, a liquid crystal alignment solidification layer was formed on a coated substrate. The liquid crystal alignment solidification layer had an elongated shape. The thickness of the liquid crystal alignment solidification layer was 1 μm.

[0329] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (450) was 90 nm, and the in-plane phase difference Re (550) was 83 nm.

[0330] <<Preparation Example 4>>

[0331] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 3, except that the coating thickness was slightly adjusted using a bar coater.

[0332] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (450) was 100 nm, and the in-plane phase difference Re (550) was 93 nm.

[0333] <<Preparation Example 5>>

[0334] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 3, except that the coating thickness was slightly adjusted using a bar coater.

[0335] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (450) was 110 nm, and the in-plane phase difference Re (550) was 102 nm.

[0336] <<Preparation Example 6>>

[0337] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 3, except that the coating thickness was slightly adjusted using a bar coater.

[0338] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (450) was 120 nm, and the in-plane phase difference Re (550) was 111 nm.

[0339] <<Preparation Example 7>>

[0340] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 3, except that the coating thickness was slightly adjusted using a bar coater.

[0341] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (450) was 130 nm, and the in-plane phase difference Re (550) was 120 nm.

[0342] <<Preparation Example 8>>

[0343] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 3, except that the coating thickness was slightly adjusted using a bar coater.

[0344] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (450) was 140 nm, and the in-plane phase difference Re (550) was 130 nm.

[0345] <<Preparation Example 9>>

[0346] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 3, except that the direction of the alignment treatment was changed to a 15° direction when viewed from the viewing side with respect to the absorption axis direction of the polarizer, and the coating thickness was changed. The thickness of the liquid crystal alignment solidification layer was 2 μm.

[0347] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (550) was 240 nm.

[0348] <<Preparation Example 10>>

[0349] A liquid crystal alignment solidification layer was formed on a coated substrate in the same manner as in Preparation Example 7, except that the direction of the alignment treatment was changed to a 75° direction when viewed from the viewing side with respect to the absorption axis direction of the polarizer. The thickness of the liquid crystal alignment solidification layer was 1 μm.

[0350] The liquid crystal alignment solidification layer had a refractive index of nx > ny = nz. In the liquid crystal alignment solidification layer, the in-plane phase difference Re (550) was 120 nm.

[0351] <<Preparation Example 11>>

[0352] As a first phase difference film, a stretched film containing COP (manufactured by Nippon Zeon, ZD12) was prepared. The stretched film had a refractive index of nx > ny > nz. The angle formed by the long axis direction and the ground axis direction of the stretched film was 45°. In the stretched film, the in-plane phase difference Re (450) was 100 nm, and the in-plane phase difference Re (550) was 100 nm.

[0353] <<Preparation Example 12>>

[0354] As a first phase difference film, a stretched film containing COP (manufactured by Zeon, Japan, ZD12) was prepared. The stretched film had a refractive index of nx > ny > nz. The angle formed by the long axis direction and the ground axis direction of the stretched film was 45°. In the stretched film, the in-plane phase difference Re (450) was 140 nm, and the in-plane phase difference Re (550) was 140 nm.

[0355] Preparation of the second phase difference film

[0356] <<Preparation Example 13>>

[0357] The liquid crystal alignment solidification layer obtained in Preparation Example 9 was adopted as the first liquid crystal alignment solidification layer, and the liquid crystal alignment solidification layer obtained in Preparation Example 10 was adopted as the second liquid crystal alignment solidification layer.

[0358] The surface of the first liquid crystal alignment solidification layer obtained in Preparation Example 9 and the surface of the second liquid crystal alignment solidification layer obtained in Preparation Example 10, respectively, are treated using a corona treatment device at a treatment density of 50 W·min / m² 2 It treated COVID-19.

[0359] Next, a water-based adhesive obtained in Preparation Example 1 was applied to the corona treated surface of the first liquid crystal alignment solidification layer using an MCD coater (manufactured by Fuji Kikai Co., Ltd., cell shape: honeycomb, gravure roll line count: 1000 / inch, rotation speed 130% / line speed) to form a coating film on the first liquid crystal alignment solidification layer.

[0360] In addition, in the same manner as above, the water-based adhesive obtained in Preparation Example 1 was applied to the corona-treated surface of the second liquid crystal alignment solidification layer.

[0361] After that, the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer were laminated using a lamination roller. More specifically, the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer were passed through the lamination roller so that the coating film on the first liquid crystal alignment solidification layer and the coating film on the second liquid crystal alignment solidification layer came into contact with each other. The line speed of each of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer was 15 m / min. At this time, the angle formed by the ground axis direction of the first liquid crystal alignment solidification layer and the ground axis direction of the second liquid crystal alignment solidification layer was 60°.

[0362] After that, the coating film was heated and dried at 60°C for 10 minutes, and the water-based adhesive was cured to form an adhesive layer.

[0363] Next, the coating substrate was peeled off and removed from each of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer.

[0364] Thus, a second phase difference film having a laminated structure of a first liquid crystal alignment solidification layer / adhesive layer / second liquid crystal alignment solidification layer was prepared.

[0365] Preparation of Polarizers

[0366] <<Preparation Example 14>>

[0367] As a thermoplastic resin substrate, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) which is long in shape and has a Tg of about 75°C was used, and corona treatment was performed on one side of the film.

[0368] A PVA aqueous solution (coating solution) was prepared by adding 13 parts by mass of potassium iodide to 100 parts by mass of a PVA-based resin mixed in a 9:1 ratio of polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Kosei Kagaku Kogyo Co., Ltd., trade name 'Gosepamer') and dissolving the mixture in water.

[0369] A PVA-based resin layer with a thickness of 13 μm was formed on a thermoplastic resin substrate by applying the above PVA aqueous solution to the corona-treated surface of the thermoplastic resin substrate and drying it at 60°C.

[0370] The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (long direction) in an oven at 130°C (air-assisted stretching treatment).

[0371] Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) (insolubilization treatment).

[0372] Next, the laminate was immersed for 60 seconds in a dyeing bath at a liquid temperature of 30°C (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a mass ratio of 1:7 with respect to 100 parts by mass of water), while adjusting the concentration so that the final obtained elemental transmittance (Ts) of the polarizer becomes a desired value (dyeing treatment).

[0373] Next, the laminate was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) (crosslinking treatment).

[0374] Afterwards, the laminate was immersed in an aqueous boric acid solution (boric acid concentration 4 mass%, potassium iodide concentration 5 mass%) at a liquid temperature of 70°C, and uniaxial stretching was performed in the longitudinal direction (longer direction) between rolls of different circumferential speeds such that the total stretching ratio was 5.5 times (underwater stretching treatment).

[0375] Afterwards, the laminate was immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with 100 parts by mass of water) (cleaning treatment).

[0376] Afterwards, the laminate was dried in an oven maintained at approximately 90°C and brought into contact with a heated roller made of SUS maintained at a surface temperature of approximately 75°C (drying shrinkage treatment).

[0377] In this way, a polarizer was formed on a thermoplastic resin substrate. The thickness of the polarizer was approximately 5.0 μm.

[0378] [Example 1]

[0379] The liquid crystal alignment solidification layer obtained in Preparation Example 4 was used as the first phase difference film, and the UV-curing adhesive obtained in Preparation Example 2 was used to attach it to the polarizer obtained in Preparation Example 14.

[0380] More specifically, the UV-curable adhesive obtained in Preparation Example 2 was applied to the surface opposite to the thermoplastic resin substrate in the polarizer using an MCD coater (manufactured by Fujiki Kai Co., Ltd., cell shape: honeycomb, gravure roll line count: 1000 / inch, rotation speed 130% / unit line speed) to form a coating film on the polarizer. In addition, the UV-curable adhesive obtained in Preparation Example 2 was applied to the surface of the first phase difference film in the same manner as above.

[0381] After that, the polarizer and the first phase difference film were laminated so that the angle formed by the absorption axis direction of the polarizer and the ground axis direction of the first phase difference film was 45°.

[0382] Next, ultraviolet rays were irradiated onto a coating film containing an ultraviolet-curing adhesive to cure the ultraviolet-curing adhesive, thereby forming a first adhesive layer as a first adhesive layer.

[0383] After that, the coating substrate was peeled off and removed from the first phase difference film (liquid crystal alignment solidification layer), and the thermoplastic resin substrate was peeled off and removed from the polarizer.

[0384] Thus, an intermediate laminate having a laminated structure of a first phase difference film (liquid crystal alignment solidification layer) / first adhesive layer / polarizer was manufactured.

[0385] Next, the above-mentioned intermediate laminate, the second phase difference film obtained in Preparation Example 13, and the water-based adhesive obtained in Preparation Example 1 were laminated together.

[0386] More specifically, an aqueous adhesive obtained in Preparation Example 1 was applied to the surface opposite to the first phase difference film in the polarizer using an MCD coater (manufactured by Fuji Kikai Co., Ltd., cell shape: honeycomb, gravure roll line count: 1000 / inch, rotation speed 130% / unit line speed) to form a coating film on the polarizer. In addition, the aqueous adhesive obtained in Preparation Example 1 was applied to the surface opposite to the second liquid crystal alignment solidification layer in the first liquid crystal alignment solidification layer in the same manner as above.

[0387] After that, the polarizer and the second phase difference film were laminated such that the angle formed between the absorption axis direction of the polarizer and the ground axis direction of the first liquid crystal alignment solidification layer was 15°, and the angle formed between the absorption axis direction of the polarizer and the ground axis direction of the second liquid crystal alignment solidification layer was 75°.

[0388] Next, the coating film was heated and dried at 60°C for 10 minutes, and the water-based adhesive was cured to form a second adhesive layer as a second adhesive layer.

[0389] After that, a (mat)acrylic adhesive was applied to the surface opposite to the second adhesive layer in the second liquid crystal alignment solidification layer to form an adhesive layer. The thickness of the adhesive layer was 15 μm.

[0390] Based on the above, an optical laminate having a laminated structure of a first phase difference film (liquid crystal alignment solidification layer) / first adhesive layer / polarizer / second adhesive layer / second phase difference film / adhesive layer was manufactured.

[0391] The thickness of the optical laminate is shown in Table 1.

[0392] [Example 2]

[0393] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Example 5 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0394] [Example 3]

[0395] An optical laminate was manufactured in the same manner as Example 1, except that the liquid crystal alignment solidification layer obtained in Example 6 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0396] [Example 4]

[0397] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Example 7 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0398] [Examples 5~8]

[0399] An optical laminate was prepared in the same manner as Examples 1 to 4, except that the UV-curing adhesive constituting the first adhesive layer was changed to the water-based adhesive obtained in Preparation Example 1, and the coating film containing the water-based adhesive was heated and dried at 60°C for 10 minutes to cure the water-based adhesive.

[0400] [Comparative Example 1]

[0401] An optical laminate was manufactured in the same manner as in Example 1, except that the stretched film obtained in Example 11 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0402] [Comparative Example 2]

[0403] An optical laminate was manufactured in the same manner as in Example 1, except that the stretched film obtained in Example 12 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0404] [Comparative Example 3]

[0405] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Example 3 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0406] [Comparative Example 4]

[0407] An optical laminate was manufactured in the same manner as Example 1, except that the liquid crystal alignment solidification layer obtained in Example 8 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Example 4.

[0408] [Table 1]

[0409]

[0410] [Table 2]

[0411]

[0412] [evaluation]

[0413] As is evident from Tables 1 and 2, if the first phase difference film includes an orientation solidification layer of a liquid crystal compound, and the in-plane phase difference Re (450) of the first phase difference film is 100 nm or more and 130 nm or less, and if Re (450) / Re (550) in the first phase difference film exceeds 1, it can be seen that the optical laminate can be thinned and visibility through polarized sunglasses can be improved when the optical laminate is applied to an image display device. Industrial applicability

[0414] An optical laminate manufactured according to an embodiment of the present invention can be suitably used in an image display device (typically, a liquid crystal display device, an organic EL display device). Explanation of the symbols

[0415] 1: First phase difference film 2: Second phase difference film 21: First liquid crystal alignment solidification layer 22: Second liquid crystal alignment solidification layer 3: Polarizer 4: First adhesive layer 41: First adhesive layer 5: Second adhesive layer 51: Second adhesive layer 6: Adhesive layer 100: Optical laminate

Claims

Claim 1 An optical laminate comprising a first phase difference film, a polarizer, and a second phase difference film in this order, wherein the first phase difference film comprises an orientation solidification layer of a liquid crystal compound, the in-plane phase difference Re (450) of the first phase difference film is 100 nm or more and 130 nm or less, and the Re (450) / Re (550) in the first phase difference film is greater than 1. Claim 2 An optical laminate according to claim 1, wherein, in the stacking direction of the optical laminate, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the polarizer in the second phase difference film is less than 15 μm. Claim 3 An optical laminate according to claim 1, wherein, in the stacking direction of the optical laminate, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the polarizer in the second phase difference film is less than 10 μm. Claim 4 An optical laminate according to claim 1, further comprising an adhesive layer located on the opposite side of the polarizer with respect to the second phase difference film. Claim 5 An optical laminate according to claim 4, wherein, in the lamination direction of the optical laminate, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the second phase difference film in the adhesive layer is less than 35 μm. Claim 6 An optical laminate according to claim 4, wherein, in the lamination direction of the optical laminate, the dimension from the surface opposite to the polarizer in the first phase difference film to the surface opposite to the second phase difference film in the adhesive layer is less than 25 μm. Claim 7 An optical laminate according to claim 1, wherein Re(450) / Re(550) in the first phase difference film is 1.05 or more and 1.5 or less. Claim 8 An optical laminate according to claim 1, wherein the angle formed by the ground axis direction of the first phase difference film and the absorption axis direction of the polarizer is 35° to 55°. Claim 9 An optical laminate according to claim 1, wherein the second phase difference film functions as a λ / 4 plate. Claim 10 An optical laminate according to claim 1, wherein the thickness of the second phase difference film is greater than the thickness of the first phase difference film. Claim 11 An optical laminate according to claim 1, wherein the second phase difference film comprises an orientation solidification layer of a liquid crystal compound, and Re(450) / Re(550) in the second phase difference film is 1 or less. Claim 12 An optical laminate according to claim 1, wherein the thickness of the first phase difference film is 0.5 μm or more and 2.0 μm or less. Claim 13 An optical laminate according to claim 1, further comprising a first adhesive layer that laminates the first phase difference film and the polarizer, wherein the thickness of the first adhesive layer is less than 0.5 μm. Claim 14 In paragraph 13, the optical laminate, wherein the first adhesive layer is the first adhesive layer. Claim 15 An optical laminate according to claim 13, further comprising a second adhesive layer that laminates the polarizer and the second phase difference film, wherein the thickness of the second adhesive layer is less than 0.5 μm. Claim 16 In item 15, the optical laminate, wherein the second adhesive layer is the second adhesive layer. Claim 17 An optical laminate according to claim 16, wherein the second adhesive layer comprises a cured product of a water-based adhesive containing an organosilicon compound. Claim 18 In claim 17, the above organosilicon compound comprises an amino-based silane coupling agent, an optical laminate. Claim 19 In claim 17, the above organosilicon compound comprises an epoxy-based silane coupling agent, an optical laminate. Claim 20 An image display device having an optical laminate as described in any one of claims 1 to 19. Claim 21 In claim 20, the first phase difference film is positioned on the visible side with respect to the polarizer, in an image display device.

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