Optical laminates and image display devices

Abstract

To provide an optical laminate that can be made thinner and, when applied to an image display device, can improve visibility through an optical component having a polarizing effect. [Solution] 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 this order. The first phase difference film contains 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

Technical Field

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

Background Art

[0002] Conventionally, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) have been rapidly spreading. When such an image display device is viewed by a viewer through polarized sunglasses, depending on the viewing angle of the viewer, the screen of the image display device may become colored and the visibility of the displayed image may decrease. In order to solve such problems, it has been proposed to dispose an optical laminate including a retardation film and a polarizer on the viewing side of an image display panel in an image display device (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, the uses of image display devices have been expanding, and there are cases where further thinning of the optical laminate is required. However, in the optical laminate described in Patent Document 1, it is difficult to impart visibility through an optical member having a polarization effect to an image display device while achieving thinning. The main object of the present invention is to provide an optical laminate that can be thinned and that can improve visibility through an optical member having a polarization effect when applied to an image display device.

Means for Solving the Problems

[0005] [1] An optical laminate according to an embodiment of the present invention comprises, in this order, a first phase difference film, a polarizer, and a second phase difference film. The first phase difference film contains an orientation solidified 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 ratio Re(450) / Re(550) in the first phase difference film is greater than 1. [2] In the optical laminate described in [1] above, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the second phase difference film opposite to the polarizer in the lamination direction of the optical laminate may be less than 15 μm. [3] In the optical laminate described in [1] above, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the second phase difference film opposite to the polarizer in the lamination direction of the optical laminate may be less than 10 μm. [4] The optical laminate described in any of [1] to [3] above may further comprise an adhesive layer, the adhesive layer located on the opposite side of the polarizer from the second phase difference film. [5] In the optical laminate described in [4] above, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the adhesive layer opposite to the second phase difference film in the lamination direction of the optical laminate may be less than 35 μm. [6] In the optical laminate described in [4] above, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the adhesive layer opposite to the second phase difference film in the lamination direction of the optical laminate may be less than 25 μm. [7] In the optical laminate described in any 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. [8] In the optical laminate described in any of [1] to [7] above, the angle between the slow phase axis direction of the first phase difference film and the absorption axis direction of the polarizer may be 35° to 55°. [9] In the optical laminate described in any of [1] to [8] above, the second phase difference film may function as a λ / 4 plate.

[10] In the optical laminate described in any 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.

[11] In the optical laminate described in any 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) ratio in the second phase difference film may be 1 or less.

[12] In the optical laminate described in any 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.

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

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

[14] The optical laminate described in

[13] above may also have the first adhesive layer being the first adhesive layer.

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

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

[16] In the optical laminate described in

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

[17] In the optical laminate described in

[16] above, the second adhesive layer may contain a cured product of an aqueous adhesive containing an organosilicon compound.

[18] In the optical laminate described in

[17] above, the organosilicon compound may contain an amino silane coupling agent.

[19] In the optical laminate described in

[17] or

[18] above, the organosilicon compound may contain an epoxy silane coupling agent.

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

[19] above.

[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]

[0006] According to embodiments of the present invention, it is possible to realize an optical laminate that can be made thinner and, when applied to an image display device, can improve visibility through an optical element having a polarizing effect. [Brief explanation of the drawing]

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

[0008] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the embodiments; however, these are merely examples and do not limit the interpretation of the present invention.

[0009] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), and "nz" is the refractive index in the thickness direction. Equation of an ellipse (x 2 / a 2 )+(y 2 / b 2) = 1, let a be nx, b be ny, x and y be the refractive indices in the x - direction and y - direction at the angle θ on the ellipse. Solve the simultaneous equations from y = x(tanθ), nx, and ny. The "refractive index in the transmission axis direction" is √(x 2 + y 2 )). The "average refractive index" is obtained by (nx + ny + nz) / 3. (2) In - plane retardation (Re) "Re(λ)" is the in - plane retardation measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in - plane retardation measured with light of wavelength 550 nm at 23°C. When the thickness of the layer (film) is d (nm), Re(λ) is obtained by the formula: Re(λ)=(nx - ny)×d. (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 550 nm at 23°C. When the thickness of the layer (film) is d (nm), Rth(λ) is obtained by the formula: Rth(λ)=(nx - nz)×d. (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, the angle includes both clockwise and counter - clockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°. (6) Substantially parallel or orthogonal The expressions "substantially parallel" and "substantially parallel" include the case where the angle formed by two directions is within 0°±3°. Also, the expressions "substantially orthogonal" and "substantially orthogonal" include the case where the angle formed by two directions is 90°±3°.

[0010] A. Overview of the optical laminate Figure 1 is a schematic cross - sectional view of an optical laminate according to one embodiment of the present invention. 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. The polarizer 3 has a transmission axis that transmits polarized light vibrating in a specific direction, and an absorption axis that is perpendicular to the transmission axis. In the following, the direction in which the transmission axis extends may be referred to as the transmission axis direction, and the direction in which the absorption axis extends may be referred to as the absorption axis direction. The first phase difference film 1 contains an orientation-solidified layer of liquid crystal compounds (hereinafter sometimes referred to as the liquid crystal orientation-solidified layer). In this specification, the "orientation-solidified layer of liquid crystal compounds" refers to a layer in which liquid crystal compounds are oriented in a predetermined direction within the layer, and this orientation state is fixed. The "orientation-solidified layer" is a concept that includes orientation-cured layers obtained by curing liquid crystal monomers, as described later. 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 between 100 nm and 130 nm. The first phase difference film 1 typically exhibits positive wavelength dispersion characteristics, where the in-plane birefringence decreases with the wavelength of the measured light. Re(450) / Re(550) in the first phase difference film 1 is greater than 1. With this configuration, since the first phase difference film includes a liquid crystal alignment solidification layer, the difference between nx and ny in the first phase difference film can be made significantly larger compared to non-liquid crystal materials. Therefore, the thickness of the phase difference film having the desired phase difference can be significantly reduced, and as a result, the optical laminate can be made thinner. Furthermore, in the first phase difference film, the in-plane phase difference Re(450) is between 100 nm and 130 nm, and Re(450) / Re(550) exceeds 1. Therefore, when the optical laminate is applied to an image display device, the visibility of the image display device can be improved through an optical component having a polarizing effect (hereinafter sometimes referred to as a polarizing component). Therefore, while making the optical laminate thinner, it is possible to improve the visibility through the polarizing member in an image display device equipped with an optical laminate.

[0011] The refractive index of the first phase difference film 1 preferably exhibits the relationship nx > ny ≥ nz. The first phase difference film 1 typically functions as a λ / 4 plate. With this configuration, the visibility through the polarizing member can be stably improved in an image display device equipped with an optical laminate.

[0012] 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. On the other hand, the in-plane phase difference Re(450) of the first phase difference film 1 is preferably 125 nm or less, and more preferably 120 nm or less. 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. On the other hand, 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. 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 more, and more preferably 1.05 or more. On the other hand, Re(450) / Re(550) is, for example, 1.20 or less, or for example 1.50 or less, or for example 1.15 or less. When the in-plane phase difference and / or Re(450) / Re(550) in the first phase difference film are within this range, the visibility through the polarizing member can be more stably improved in an image display device equipped with an optical laminate.

[0013] The angle between the slow phase 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°. With this configuration, the visibility of the image display device via the polarizing member can be improved even more stably.

[0014] The first phase difference film 1 may have a single-layer structure of liquid crystal alignment solidification layer, or it may have a laminated structure including liquid crystal alignment solidification layer. In one embodiment, the first phase difference film 1 has a single-layer structure of a liquid crystal alignment solidification layer. With this configuration, the thinning of the optical laminate can be stably achieved.

[0015] The thickness of the first phase difference film 1 is arbitrarily and appropriately adjusted so that the desired phase difference is obtained. 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. On the other hand, 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.

[0016] The refractive index of the first phase difference film 1 in the transmission axis direction is, for example, 1.45 or higher, preferably 1.50 or higher. On the other hand, 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. The refractive index is measured, for example, by thin-film waveguide methods (prism couplers) using light with a wavelength of 594 nm.

[0017] 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.

[0018] 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. Having polarizers of this thickness makes it possible to further reduce the thickness of optical laminates.

[0019] In one embodiment, the polarizer 3 is attached to the first phase difference film 1 via a 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.

[0020] 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, particularly preferably 0.12 μm or less, especially preferably 0.05 μm or less, and most preferably 0.04 μm or less. When the first phase difference film includes a liquid crystal alignment solidification layer, it can be made thinner and has a relatively large refractive index compared to when the first phase difference film is composed of a non-liquid crystal material (typically resin). As a result, light reflection and interference are more likely to occur at the interface between the first phase difference film and the adjacent layer. However, in one embodiment, the thickness of the first adhesive layer is adjusted to be below this upper limit, so that 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, it is possible to suppress the reflection of ambient light (visible light) at the interface between the first adhesive layer and the first phase difference film, and interference of the reflected light. As a result, it is possible to suppress the occurrence of interference unevenness that causes black displays to become colored in an image display device equipped with an optical laminate. On the other hand, 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. If the thickness of the first adhesive layer is above this lower limit, the adhesive strength of the first adhesive layer can be improved, and layers adjacent to the first adhesive layer (typically polarizers and first phase difference films) can be stably bonded together.

[0021] 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. On the other hand, 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. 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. On the other hand, 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. When the refractive index difference 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, the reflection of light (visible light) incident on the optical laminate at the interface between the first adhesive layer and the first phase difference film can be stably suppressed.

[0022] The first adhesive layer 4 may be an adhesive layer composed of an adhesive, or it may be an adhesive layer composed of a tackant. 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). In the adhesive layer, curing shrinkage, uneven coating, coating repellency, and uneven drying can cause waviness and / or thickness variations in the adhesive layer. In this case, the waviness and / or thickness variations in the adhesive layer can cause variations in the optical path length of the optical laminate, which may result in interference variations in the image display device equipped with the optical laminate. In this regard, according to one embodiment, since the thickness of the first adhesive layer 41 is within the above-described range, the degree of curing shrinkage of the adhesive, coating unevenness, coating repellency, and drying unevenness can be sufficiently reduced, and the occurrence of waviness and / or thickness unevenness in the first adhesive layer can be significantly suppressed. As a result, the unevenness of the optical path length in the optical laminate can be reduced, and interference unevenness in the image display device can be suppressed more stably.

[0023] The second phase difference film 2 is located on the opposite side of the polarizer 3 from the first phase difference film 1. 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 satisfies, for example, the relationship nx > ny, and preferably nx > ny ≥ nz.

[0024] In one embodiment, the second phase difference film 2 functions as a λ / 4 plate. With this configuration, anti-reflective properties can be imparted to the optical laminate. 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.

[0025] 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, or it may exhibit positive wavelength dispersion characteristics in which the in-plane birefringence decreases with the wavelength of the measurement light, or it may exhibit flat wavelength dispersion characteristics in which the in-plane birefringence hardly changes with the wavelength of the measurement light. In one embodiment, the second phase difference film 2 exhibits inverse wavelength dispersion characteristics. In the second phase difference film 2, Re(450) / Re(550) is, for example, 1 or less, preferably less than 0.9, and more preferably 0.85 or less. On the other hand, in the second phase difference film 2, Re(450) / Re(550) is, for example, 0.7 or more, and preferably 0.75 or more. If the Re(450) / Re(550) ratio 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 / 4 plate, it will function as a λ / 4 plate at any wavelength, thus providing good anti-reflective properties at any wavelength.

[0026] The second phase difference film 2 may have a single-layer structure or a laminated structure. The second phase difference film 2 typically includes a stretched film prepared by stretching a film composed of a transparent resin, and / or a liquid crystal alignment solidification layer. 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 comprises a first liquid crystal alignment solidification layer 21, an adhesive layer 23, and a second liquid crystal alignment solidification layer 22 in this order.

[0027] The thickness of the second phase difference film 2 is adjusted arbitrarily and appropriately so that the desired phase difference is obtained. In one embodiment, the thickness of the second phase difference film 2 is greater than the thickness of the first phase difference film 1. The thickness of the second phase difference film 2 is, for example, 1.5 times or more, preferably 2 times or more, the thickness of the first phase difference film 1. On the other hand, the thickness of the second phase difference film 2 is, for example, 6 times or less, preferably 4 times or less, the thickness of the first phase difference film 1. The thickness of the second phase difference film 2 is, for example, 0.5 μm to 20 μm, preferably 1.0 μm to 10 μm, and more preferably 2.0 μm to 5.0 μm. Having such a thickness in the second phase difference film allows for stable thinning of the optical laminate and provides the optical laminate with sufficient handling properties, i.e., self-supporting and process fluidity. Furthermore, 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.

[0028] In one embodiment, the second phase difference film 2 is attached to the polarizer 3 via a 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.

[0029] 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, particularly preferably 0.12 μm or less, especially preferably 0.05 μm or less, and most preferably 0.04 μm or less. 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 contains a liquid crystal alignment solidification layer, light interference in the optical laminate can be sufficiently suppressed. As a result, interference unevenness can be stably suppressed in an image display device equipped with an optical laminate. On the other hand, 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. If the thickness of the second adhesive layer is above this lower limit, the adhesive strength of the second adhesive layer can be improved, and layers adjacent to the second adhesive layer (typically polarizers and second phase difference films) can be stably bonded together.

[0030] The range of refractive index of the second adhesive layer 5 in the transmission axis direction is, for example, the same as the range of refractive index of the first adhesive layer 4 described above. Also, the range of absolute value of the difference between the refractive index of the second adhesive layer 5 and the refractive index of the second phase difference film 2 (typically the first liquid crystal alignment solidification layer 21) in the transmission axis direction is, for example, the same as the range of 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 described above. When the refractive index difference 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, the reflection of light (visible light) incident on the optical laminate at the interface between the second adhesive layer and the second phase difference film can be stably suppressed.

[0031] The second adhesive layer 5 may be an adhesive layer composed of an adhesive, or it may be an adhesive layer composed of a tackant. 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 range described above, the degree of curing shrinkage of the adhesive, coating unevenness, coating repellency, and drying unevenness can be sufficiently reduced, and the occurrence of waviness and / or thickness unevenness in the second adhesive layer can be significantly suppressed. As a result, unevenness in the optical path length in the optical laminate can be reduced, and interference unevenness in the image display device can be suppressed more stably.

[0032] In one embodiment, the optical laminate 100 further comprises an adhesive layer 6. The adhesive layer 6 is located on the opposite side of the polarizer 3 from the second phase difference film 2. In the illustrated example, the adhesive layer 6 is laminated on the surface of the second liquid crystal alignment solidification layer 22 opposite to the first liquid crystal alignment solidification layer 21. With this configuration, the optical laminate can be attached to any suitable substrate (typically an image display panel) of the image display device by the adhesive layer 6.

[0033] 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. On the other hand, 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.

[0034] In the stacking direction of such an optical laminate 100, the distance from the surface of the first phase difference film 1 opposite to the polarizer 3 to the surface of the second phase difference film 2 opposite to the polarizer 3 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 particularly preferably 9.5 μm or less. This configuration allows for stable thinning of the optical laminate.

[0035] Furthermore, in the stacking direction of the optical laminate 100, the distance from the surface of the first phase difference film 1 opposite to the polarizer 3 to the surface of the adhesive layer 6 opposite to the second phase difference film 2 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 particularly preferably 24.5 μm or less. This configuration allows for more stable thinning of the optical laminate.

[0036] B. Details of the optical laminate Next, with reference to Figure 1, the details of an optical laminate according to one embodiment will be described. As shown in Figure 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.

[0037] B-1. First phase difference film In one embodiment, the first phase difference film 1 has a single-layer structure of a liquid crystal alignment solidification layer. In such a first phase difference film 1, the rod-shaped liquid crystal compounds are oriented in a state where they are aligned in a predetermined direction on the first phase difference film 1 (homogeneous orientation). Examples of liquid crystal compounds include liquid crystal compounds in which the liquid crystal phase is a 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 be used individually or in combination. The mechanism by which liquid crystalline properties are expressed in liquid crystal compounds may be lyotropic or thermotropic.

[0038] When a liquid crystal compound contains a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. The orientation state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After oriented the liquid crystal monomer, the orientation state can be fixed by polymerizing or crosslinking the liquid crystal monomers together, for example. Here, polymerization forms a polymer and crosslinking forms a three-dimensional network structure, but these are non-liquid crystal. Therefore, the formed liquid crystal orientation solidified layer does not undergo transitions to liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which is characteristic of liquid crystal compounds. As a result, the first phase difference film can have extremely excellent stability that is not affected by temperature changes.

[0039] Any suitable liquid crystal monomer can be used. Examples of liquid crystal monomers include polymerizable mesogenic compounds described in Japanese Patent Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445. Specific examples of such polymerizable mesogenic compounds include BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767.

[0040] A liquid crystal alignment solidification layer can be formed by applying an appropriate orientation treatment to any suitable coated substrate, then applying a coating liquid containing a liquid crystal compound to the surface to orient the liquid crystal compound in a direction corresponding to the orientation treatment, and fixing that orientation state. Orientation treatments include, for example, mechanical orientation treatments, physical orientation treatments, and chemical orientation treatments. Specific examples of liquid crystal compounds and details of the method for forming the orientation solidified layer are described in Japanese Patent Publication No. 2006-163343. The description in said publication is incorporated herein by reference.

[0041] The birefringence Δn of the first phase difference film 1 (liquid crystal alignment solidification layer) is, for example, 0.06 or more, preferably 0.08 or more, more preferably 0.09 or more, and even more preferably 0.10 or more. On the other hand, 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, the desired in-plane phase difference can be achieved with a very thin thickness.

[0042] B-2.Polarizer Any suitable polarizer can be used as polarizer 3. The polarizer may be composed of, for example, a single layer of resin film, or it may be obtained using a laminate of two or more layers.

[0043] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) resin films, partially formalized PVA resin films, and partially saponified ethylene-vinyl acetate copolymer films, which have been subjected to dyeing and stretching treatments with dichroic substances such as iodine or dichroic dyes, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA resin film with iodine and uniaxially stretching are used because they have excellent optical properties.

[0044] Specific examples of polarizers obtained using laminates include polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. Polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In one embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may further include, if necessary, air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in one embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. This makes it possible to improve the optical properties of polarizers obtained through processing steps that involve immersing the laminate in liquid, such as dyeing and water-based stretching treatments. Furthermore, by shrinking the laminate in the width direction through the drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer may be laminated onto the peeled surface according to the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0045] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA resin film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA resin film may be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA resin film in water and washing it before dyeing, not only can dirt and blocking inhibitors on the surface of the PVA resin film be washed away, but the PVA resin film can also be swollen to suppress uneven dyeing.

[0046] Polarizer 3 typically exhibits absorption dichroism at wavelengths between 380 nm and 780 nm. The transmittance of polarizer 3 is, for example, 41.5% or more, preferably 43.0% or more, and more preferably 44.5% or more. On the other hand, the upper limit of the transmittance of polarizer 3 is typically 46.0%. The polarization degree of polarizer 3 is, for example, 97.0% or higher, preferably 99.0% or higher, and more preferably 99.9% or higher.

[0047] 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.

[0048] B-3. ​​Second phase difference film In one embodiment, the second phase difference film 2 includes a first liquid crystal alignment solidification layer 21, an adhesive layer 23, and a second liquid crystal alignment solidification layer 22.

[0049] B-3-1. First Liquid Crystal Alignment and固化 layer The first liquid crystal alignment and固化 layer 21 may have an in-plane retardation and may also have a retardation in the thickness direction. The first liquid crystal alignment and固化 layer 21 may function as a λ / 4 plate, or may function as a λ / 2 plate, λ / 5 plate, λ / 6 plate, or C-Plate.

[0050] In one embodiment, the first liquid crystal alignment and固化 layer 21 has an in-plane retardation. In this case, the refractive indices of the first liquid crystal alignment and固化 layer 21 preferably exhibit the relationship nx > ny ≧ nz.

[0051] In another embodiment, the first liquid crystal alignment and固化 layer 21 has a retardation in the thickness direction and substantially no in-plane retardation. In this case, the refractive indices of the first liquid crystal alignment and固化 layer 21 exhibit, for example, the relationship nx = ny, and preferably the relationship nz > nx = ny. Note that in this specification, "nx = ny" includes not only the case where nx and ny are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, nx > ny or nx < ny may occur.

[0052] The refractive index of the first liquid crystal alignment and固化 layer 21 in the transmission axis direction is, for example, 1.45 or more, also for example 1.50 or more, also for example 1.55 or more, also for example exceeding 1.60, and also for example 1.61 or more. On the other hand, the upper limit of the refractive index of the first liquid crystal alignment and固化 layer 21 in the transmission axis direction is typically 1.70.

[0053] The thickness of the first liquid crystal alignment and固化 layer 21 is arbitrarily and appropriately adjusted so as to obtain a desired retardation. The thickness of the first liquid crystal alignment and固化 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. On the other hand, the lower limit of the thickness of the first liquid crystal alignment and固化 layer 21 is typically 1 μm.

[0054] The liquid crystal compound contained in the first liquid crystal alignment solidification layer 21 will be described in the same way as the liquid crystal compound contained in the first phase difference film 1. Therefore, the description of the liquid crystal compound contained in the first liquid crystal alignment solidification layer 21 will be omitted as appropriate.

[0055] B-3-2. Second liquid crystal alignment solidification layer The second liquid crystal alignment solidification layer 22 is located on the opposite side of the polarizer 3 from 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.

[0056] The second liquid crystal alignment solidification layer 22 may have an in-plane phase difference or a phase difference in the thickness direction. 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.

[0057] The second liquid crystal alignment solidification layer 22 will be described in the same manner as the first liquid crystal alignment solidification layer 21 described above. Therefore, a detailed explanation of the second liquid crystal alignment solidification layer 22 will be omitted as appropriate. The refractive index of the second liquid crystal alignment solidification layer 22 may be given by the relationship nx > ny, or by the relationship nx = ny. In one embodiment, the refractive indices of the first liquid crystal alignment solidification layer 21 and the second liquid crystal alignment solidification layer 22 are in the relationship nx > ny. With such a configuration, it is possible to have wavelength dispersion characteristics that are better than those of the second phase difference film. Furthermore, the viewing angle characteristics, i.e., the optical characteristics for any azimuthal angle and polar angle, can also be improved. The ranges of phase difference, refractive index, and thickness in the second liquid crystal alignment solidification layer 22 are, for example, the same as the ranges of phase difference, refractive index, and thickness in the first liquid crystal alignment solidification layer 21 described above.

[0058] B-3-3. Combination of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer 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. Alternatively, 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. The combination of the two phase difference films, where one is a λ / 2 plate and the other is a λ / 4 plate, may be referred to as the first combination. With this configuration, the wavelength dispersion characteristics of the second phase difference film, which comprises a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer, can be brought closer to ideal inverse wavelength dispersion characteristics. As a result, excellent anti-reflective properties can be imparted to the optical laminate.

[0059] 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. 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.

[0060] In the first combination, the angle between the absorption axis direction of the polarizer 3 and the slow phase 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°. Furthermore, in the first combination, the angle between the absorption axis direction of the polarizer 3 and the slow phase 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°. In the first combination, the range of angles between the absorption axis direction of the polarizer and the slow axis direction of the first liquid crystal alignment solidification layer may be reversed from the range of angles between the absorption axis direction of the polarizer and the slow axis direction of the second liquid crystal alignment solidification layer. With this configuration, the wavelength dispersion characteristics of the second phase difference film, which comprises a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer, can be brought closer to ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflective properties can be stably imparted to the optical laminate.

[0061] 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). Alternatively, 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 the two phase difference films is a λ / 4 plate and a C-Plate, this is sometimes referred to as the second combination. Even with such a configuration, excellent anti-reflective properties can be imparted to the optical laminate. However, the first combination described above is preferable to the second combination. When the combination of the two phase difference films is a λ / 2 plate and a λ / 4 plate, interference unevenness in an image display device equipped with an optical laminate can be stably reduced.

[0062] 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. In the second combination, the range of the phase difference Rth(550) in the thickness direction of the liquid crystal alignment solidification layer that functions 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. In the second combination, the angle between the slow axis direction of the liquid crystal alignment solidification layer, which functions as a λ / 4 plate, and the absorption axis direction of the polarizer 3 is arbitrarily and appropriately adjusted. This configuration also makes it possible to stably impart excellent anti-reflective properties to the optical laminate.

[0063] B-3-4.Adhesive layer 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 together. The adhesive layer 23 is in contact with both the first liquid crystal alignment solidification layer 21 and the second liquid crystal alignment solidification layer 22. In one embodiment, the contact surface of the first liquid crystal alignment solidification layer 21 with the adhesive layer 23, and / or the contact surface of the second liquid crystal alignment solidification layer 22 with the adhesive layer 23, is an activated surface that has undergone an activation treatment. With 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. Examples of activation treatments include corona treatment, plasma treatment, saponification treatment, and low-pressure UV treatment. These activation treatments can be performed individually or in combination.

[0064] 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 will be omitted as appropriate. The thickness range of the adhesive layer 23 is, for example, the same as the thickness range of the first adhesive layer 4 described above. The range of refractive index of the adhesive layer 23 in the transmission axis direction is, for example, the same as the range of refractive index of the first adhesive layer 4 described above. Also, the range of the absolute difference between the refractive index of the adhesive layer 23 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) in the transmission axis direction is, for example, the same as the range of the absolute difference between the refractive index of the first adhesive layer 4 and the refractive index of the first phase difference film 1 described above.

[0065] The adhesive layer 23 may be an adhesive layer composed of an adhesive, or an adhesive layer composed of a tack agent. In one embodiment, the adhesive layer 23 is an adhesive layer 231 composed of an adhesive (more specifically, a cured adhesive). The adhesive layer 231 of 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. Therefore, a detailed description of the adhesive layer 231 is omitted.

[0066] B-4. First adhesive layer and second adhesive layer The first adhesive layer 41 (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 bonds the first phase difference film 1 and the polarizer 3 together. The second adhesive layer 51 (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 bonds the polarizer 3 and the second phase difference film 2 together. In the illustrated example, the second adhesive layer 51 bonds the polarizer 3 and the first liquid crystal alignment solidification layer 21 together. The first adhesive layer 41 and the second adhesive layer 51 are described similarly, except for their arrangement in the optical laminate 100. In the following, 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 the adhesive layer.

[0067] The first adhesive layer 41 and / or the second adhesive layer 51 contain a cured product of any suitable adhesive. Examples of adhesives include water-based adhesives, thermosetting adhesives, moisture-curing adhesives, and ultraviolet-curing adhesives (UV adhesives), with water-based adhesives and UV adhesives being preferred. Adhesives can be used alone or in combination.

[0068] In one embodiment, the first adhesive layer 41 and / or the second adhesive layer 51 contain a cured product of a water-based adhesive. When the adhesive layer contains a cured product of a water-based adhesive, the thickness of the adhesive layer can be stably adjusted to the above range, and interference unevenness in the optical laminate can be sufficiently suppressed.

[0069] Water-based adhesives, before curing, typically contain a curing component and a solvent that includes water.

[0070] The curing components are typically soluble and / or dispersible in a solvent. The curing components can be cured by any suitable chemical reaction. Examples of curing components include combinations of polyvinyl alcohol (PVA) and crosslinking agents, and organosilane compounds. The curing components can be used alone or in combination.

[0071] Water-based adhesives containing PVA and a crosslinking agent as curing components may be referred to as PVA-containing water-based adhesives below. Crosslinking agents can crosslink PVA to cure water-based adhesives. Examples of crosslinking agents include melamine resins such as methylolmelamine; alkylenediamines; isocyanates; epoxys; and aldehydes. Crosslinking agents can be used alone or in combination. The proportion of the crosslinking agent in the water-based adhesive is, for example, 10 to 50 parts by mass, preferably 20 to 40 parts by mass, per 100 parts by mass of PVA.

[0072] PVA-containing water-based adhesives may further contain metal compound colloids in addition to PVA and crosslinking agents. Metal compound colloids consist of fine particles of a metal compound dispersed in a solvent. They can be electrostatically stabilized due to the mutual repulsion of like charges among the fine particles, and thus can possess permanent stability.

[0073] 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 celite, talc, clay, and kaolin. These metal compounds can be used individually or in combination.

[0074] The average particle size of the fine particles forming the metal compound colloid can be arbitrarily and appropriately adjusted. The average particle size of the fine particles is, for example, 1 nm to 100 nm, preferably 1 nm to 50 nm. When the average particle size of the fine particles is within this range, the fine particles can be uniformly dispersed in the adhesive layer. The proportion of metal compound colloids in water-based adhesives can be adjusted arbitrarily and appropriately.

[0075] Water-based adhesives containing organic silane compounds as a curing component may be referred to as organic silane-containing water-based adhesives below. Organosilane compounds typically contain an alkoxysilyl group and / or a silanol group (hydroxysilyl group). When an organosilane compound contains an alkoxysilyl group and / or a silanol group, it can cure water-based adhesives through a dehydration condensation reaction.

[0076] Examples of organosilane compounds include silane coupling agents having an alkoxysilyl group and / or a silanol group and an organic functional group. Examples of organic functional groups that silane coupling agents may possess include amino groups, epoxy groups, and methoxy groups. A silane coupling agent may have one organic functional group or a combination of two or more organic functional groups. Having such organic functional groups in a silane coupling agent can improve the adhesive strength of the adhesive layer. These silane coupling agents can be used individually or in combination.

[0077] 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. Such a configuration can improve the adhesion strength of the adhesive layer and allow the adhesive layer to be made thinner.

[0078] The amino-based silane coupling agent has any suitable structure having an amino group and an alkoxysilyl group and / or a silanol group. Examples of amino silane coupling agents include 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 their hydrochloride salts.

[0079] Any suitable commercially available amino silane coupling agent can be used. Examples of commercially available amino 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.), and A-1100, A-1110, A-1120, A-2120, Y-9669 (all manufactured by Momentive Performance Materials).

[0080] The epoxy-based silane coupling agent has any suitable structure comprising an epoxy group and an alkoxysilyl group and / or a silanol group. Examples of epoxy 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.

[0081] Any suitable commercially available epoxy silane coupling agent can be used. Examples of commercially available epoxy 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.).

[0082] When the organosilicon compound contains both an amino-based silane coupling agent and an epoxy-based silane coupling agent, the amino group of the amino-based silane coupling agent can react with the epoxy group of the epoxy-based silane coupling agent. This allows for stable curing of the water-based adhesive and enables further thinning of the adhesive layer. 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. If the molar ratio of the amino-based silane coupling agent to the epoxy-based silane coupling agent is within this range, the adhesive layer can be made thinner and more stable.

[0083] The content of the curing component in the water-based adhesive is, for example, less than 50% by mass, preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, particularly preferably 10% by mass or less, especially preferably 5% by mass or less, and most preferably 2% by mass or less. On the other hand, the content of the curing component in the water-based adhesive is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.4% by mass or more, and particularly preferably 0.5% by mass or more.

[0084] As mentioned above, the solvent in water-based adhesives contains water. The solvent may include an organic solvent in addition to water. 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. Organic solvents can be used alone or in combination.

[0085] The water content in the solvent of the water-based adhesive is, for example, 50% by mass or more, preferably 80% by mass or more, and more preferably 95% by mass or more. On the other hand, the upper limit of the water content in the solvent is typically 100% by mass. In one embodiment, the solvent of the aqueous adhesive is substantially free of organic solvents. In other words, the water content in the solvent is, for example, 98% by mass or more and 100% by mass or less. When the water content in the solvent of a water-based adhesive is within this range, the solvent can be smoothly evaporated when the water-based adhesive is applied and dried, enabling stable thinning of the adhesive layer. Furthermore, since water causes little damage to the polarizer and phase difference film, optical laminates with excellent quality can be manufactured stably.

[0086] The solvent content in water-based adhesives is adjusted arbitrarily and appropriately according to the curing component content. Water-based adhesives contain any appropriate additives as needed. Examples of additives include amino compounds, epoxy compounds, binder resins, surfactants, plasticizers, tackifiers, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, titanium coupling agents, inorganic or organic fillers, metal powders, particulate matter, and foil-like materials. The additives can be used individually or in combination. Among the additives, surfactants are preferred.

[0087] 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, particularly preferably 1 part by mass or less, and especially preferably 0.5 parts by mass or less, per 1 part by mass of the hardening component. On the other hand, the lower limit of the content ratio of the additive is typically 0 parts by mass per 1 part by mass of the hardening component.

[0088] In one embodiment, each of the first adhesive layer 41 and the second adhesive layer 51 contains the cured product of the water-based adhesive described above. With this configuration, each of the first adhesive layer and the second adhesive layer can be made sufficiently thin, and as a result, unevenness in the optical path length in the optical laminate can be significantly suppressed. In this case, the cured product of the water-based adhesive contained in the first adhesive layer 41 and the cured product of the water-based adhesive contained in the second adhesive layer 51 may be the same as or different from each other. In one embodiment, the cured product of the water-based adhesive contained in the first adhesive layer 41 and the cured product of the water-based adhesive contained in the second adhesive layer 51 are identical to each other. This allows the refractive index of the first adhesive layer 41 in the direction of transmission axis to be adjusted to be substantially the same as the refractive index of the second adhesive layer 51 in the direction of transmission axis. Furthermore, the adhesive layer 231 of the second phase difference film 2 may also contain the cured product of the water-based adhesive described above. This makes it possible to make the second phase difference film thinner.

[0089] Furthermore, these adhesive layers (first adhesive layer 41, second adhesive layer 51, and / or adhesive layer 231) substantially do not contain the solvent mentioned above because the solvent volatilizes during the formation process. The solvent content in the adhesive layers is, for example, 0.05% by mass or less, and preferably 0.01% by mass or less.

[0090] B-5.Adhesive layer In one embodiment, the optical laminate 100 includes an adhesive layer 6. In the illustrated example, the adhesive layer 6 is laminated on the surface of the second liquid crystal alignment solidification layer 22 opposite to the first liquid crystal alignment solidification layer 21. The adhesive layer 6 is composed of any suitable adhesive. Examples of adhesives include (meth)acrylic adhesives, urethane adhesives, and silicone adhesives. The adhesives can be used alone or in combination. Among adhesives, (meth)acrylic adhesives are preferred.

[0091] B-6. Peel-off liner The optical laminate 100 may further include a release liner 7. The release liner 7 is attached to the surface of the adhesive layer 6 opposite to the second phase difference film 2. Typically, the release liner 7 is temporarily 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.

[0092] The release liner 7 contains any suitable resin material. Examples of resin materials include polyethylene terephthalate (PET), polyethylene, and polypropylene. Resin materials can be used alone or in combination.

[0093] In one embodiment, a release treatment layer is provided on the contact surface of the release liner 7 with the adhesive layer 6. The release layer typically contains a release agent. Examples of release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents, with silicone-based release agents being preferred, and vinyl group-containing addition-type silicones being even more preferred. Release agents can be used alone or in combination. The thickness of the release layer is, for example, 50 nm to 400 nm.

[0094] B-7. Other Optical Films The optical laminate 100 may include other optical films in addition to the first phase difference film 1, the polarizer 3, and the second phase difference film 2. Other optical films include, for example, protective films, ultraviolet light transmission suppression films, and infrared light transmission suppression films. These other optical films may have a single-layer structure containing these films individually, or they may have a laminated structure in which two or more of these films are laminated together. Other optical films are attached, for example, to the surface of the first phase difference film 1 opposite to the polarizer 3 via any suitable adhesive or bonding layer.

[0095] C. Method for manufacturing optical laminates Next, a method for manufacturing the optical laminate 100 according to one embodiment will be described. In one embodiment, the method for manufacturing an optical laminate includes a step of bonding a first phase difference film 1 and a polarizer 3 (first bonding step), and a step of bonding the polarizer 3 and a second phase difference film 2 (second bonding step). In one embodiment, the method for manufacturing an optical laminate includes the first bonding step and the second bonding step in this order.

[0096] C-1. First lamination process In one embodiment, first, the first phase difference film 1 and polarizer 3 described above are prepared. The first phase difference film 1 and polarizer 3 each preferably have an elongated shape. Furthermore, if 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 the coated substrate. In addition, the polarizer 3 is typically prepared in a state supported on a resin substrate.

[0097] Next, the first phase difference film 1 and the polarizer 3 are bonded together by any suitable means. In one embodiment, the first phase difference film 1 and the polarizer 3 are bonded together by a roll-to-roll method. 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. Examples of adhesive application methods include dip coating, curtain coating, spray coating, bar coating, rod coating, roll coating, die coating, and gravure coating, with gravure coating being preferred.

[0098] Next, the first phase difference film 1 and the polarizer 3 are placed on top of each other, sandwiching the adhesive coating. After that, the adhesive is cured using an appropriate method depending on the adhesive. For example, if the adhesive contains a water-based adhesive, the adhesive coating is heated and dried. The heating temperature is, for example, 35°C to 120°C. The heating time is, for example, 30 seconds to 10 minutes. During this time, the solvent contained in the coating film volatilizes and the curing components contained in the coating film harden. As a result, a first adhesive layer 41 containing the cured product of the water-based adhesive is formed, and the first phase difference film 1 and the polarizer 3 are bonded together by the adhesive layer 41. Furthermore, 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 necessary. In addition, if the polarizer 3 is supported by a resin substrate, the resin substrate is peeled off and removed from the polarizer 3 as necessary. As described above, an intermediate laminate having a laminated structure of a first phase difference film 1 / first adhesive layer 41 / polarizer 3 is prepared.

[0099] C-2.Second lamination process Furthermore, the second optical film 2 described above is prepared. The second phase difference film 2 preferably has a long shape. Next, the intermediate laminate prepared in the first bonding step described above and the second phase difference film 2 are bonded together by any suitable means. In one embodiment, the intermediate laminate and the second optical film 2 are bonded together by a roll-to-roll method. More specifically, the adhesive described above is applied to the surface of the polarizer 3 in the intermediate laminate and / or the surface of the polarizing plate 3 by any suitable method. An example of the adhesive application method is the same as that used in the first bonding step described above.

[0100] Next, the intermediate laminate and the second phase difference film 2 are stacked so as to sandwich the adhesive coating. After that, the adhesive is cured using an appropriate method depending on the adhesive. For example, if the adhesive includes a water-based adhesive, the adhesive coating is heated and dried in the same manner as described above. At this time, the solvent contained in the coating evaporates and the curing component contained in the coating hardens. As a result, 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 bonded together by the second adhesive layer 51.

[0101] As described 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. Subsequently, if necessary, the adhesive described above may be applied to the surface of the second phase difference film 2 opposite to the polarizer 3 by any suitable method to form an adhesive layer 6.

[0102] D. Image display device The optical laminates described in sections A to C above can be applied to any suitable image display device. Therefore, 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 displays and organic EL displays, and preferably organic EL displays. An image display device according to an embodiment of the present invention comprises an image display panel and the optical laminate 100 described above. An image display panel typically includes an image display cell. The optical laminate 100 is positioned on the viewing side of the image display panel. Typically, the optical laminate 100 is 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 of the polarizer 3, i.e., opposite to the image display panel, and the second phase difference film 2 is located between the polarizer 3 and the image display panel. The optical laminate 100 has any suitable shape depending on the image display device to which it is applied. The size of the optical laminate 100 can be adjusted arbitrarily and appropriately. In such an image display device, the first phase difference film of the optical laminate has the in-plane phase differences Re(450) and Re(450) / Re(550) described above, resulting in excellent visibility through a polarizing member (typically polarized sunglasses). Furthermore, since the optical laminate 100 is made thinner, the image display device can be miniaturized. [Examples]

[0103] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows.

[0104] (1) Measurement of phase difference The phase difference of the phase difference films (liquid crystal alignment solidification layers) used in the examples and comparative examples was automatically measured using Axoscan (manufactured by Axometrics). The measurement wavelength was 450 nm or 550 nm, and the measurement temperature was 25°C. The results are shown in Tables 1 and 2.

[0105] (2) Measurement of the thickness of the adhesive layer Cross-sections of the optical laminates obtained in the examples and comparative examples were observed using a transmission electron microscope (TEM) with a Hitachi HT7820 instrument by the freeze-ultrathin sectioning method including heavy metal staining. The acceleration voltage during measurement was 100kV. This allowed us to measure the thickness of the adhesive layer (bonding layer) of the optical laminate. The results are shown in Tables 1 and 2.

[0106] (3) Sunglasses evaluation (visibility) An organic EL display device (manufactured by Samsung, product number "Galaxy A41") was disassembled and the organic EL panel was removed. The optical laminates obtained in the examples and comparative examples were attached to the organic EL panel using an adhesive layer to prepare test samples. Next, a white image was displayed on the OLED panel, and the color rendering when the image was observed through polarized sunglasses was evaluated according to the following criteria. The results are shown in Tables 1 and 2. ○ (Excellent): No noticeable discoloration was observed. △ (Good): Slight discoloration was observed. × (Defective): Obvious discoloration was observed.

[0107] (4) Interference unevenness evaluation An organic EL display device (Samsung Galaxy A41) was disassembled, and the cover glass and polarizing plate were removed from the organic EL display device. Then, the optical laminates obtained in the examples and comparative examples were bonded to the organic EL panel with an adhesive layer to prepare samples. Next, the obtained samples were placed under fluorescent lighting, and with the organic EL panel turned off, the samples were visually observed and interference uniformity was evaluated according to the following criteria. The results are shown in Tables 1 and 2. ○ (Excellent): No interference unevenness is visible. △ (Acceptable): Interference unevenness is visible within a practically acceptable range.

[0108] (5) Overall evaluation The optical laminates obtained in the examples and comparative examples were comprehensively evaluated based on the following criteria, considering the sunglasses evaluation, interference uniformity evaluation, and thickness described above. The results are shown in Tables 1 and 2. Level 1: Sunglasses evaluation: ○, Interference uniformity evaluation: ○, Thickness: 35μm or less. Level 2: Sunglasses evaluation is △, interference uniformity evaluation is ○, thickness is 35μm or less. Level 3: Sunglasses evaluation: ○, Interference uniformity evaluation: △, Thickness: 35μm or less. Level 4: Sunglasses evaluation: △, Interference uniformity evaluation: △, Thickness: 35μm or less. Level 5: Sunglasses evaluation: ×, Interference uniformity evaluation: △, Thickness: 35μm or less. Level 6: Thickness exceeds 35 μm.

[0109] <Preparation of adhesive> <<Preparation Example 1>> An aqueous solution of silane coupling agents was prepared by adding an amino-based silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-603") and an epoxy-based silane coupling agent (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") to water. 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 and epoxy-based silane coupling agents was 1.0% by mass. Subsequently, 0.2 parts by mass of a surfactant (manufactured by Nisshin Chemical Co., Ltd., trade name "EXP4200") was added to 100 parts by mass of an aqueous solution of the silane coupling agent to prepare an aqueous adhesive.

[0110] <<Preparation Example 2>> Acryloyl morpholine (trade name "ACMO", manufactured by KJ Chemicals) 25 parts by mass, ε-caprolactone 1mol modified 2-hydroxyethyl acrylate (trade name "PLACCEL FA1DDM", manufactured by Daicel Chemicals) 10 parts by mass, lauryl acrylate (trade name "Light Acrylate LA", manufactured by Kyoeisha) 10 parts by mass, isostearyl acrylate (trade name "ISTA", manufactured by Osaka Organic Chemical Industry Co., Ltd.) 20 parts by mass, 1,9-nonanediol diacrylate (trade name "Light Acrylate 1.9ND-A", manufactured by Kyoeisha Chemicals) 15 parts by mass, acrylic oligomer (trade name "ARUFON UP-1190", manufactured by Toagosei Co., Ltd.) 15 parts by mass, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad 819", manufactured by IGM Resins) A UV-curing adhesive was prepared by stirring 1 part by mass of (manufactured by BV), 2 parts by mass of 1-hydroxycyclohexyl phenyl ketone (trade name "Omnirad 184", manufactured by IGM Resins BV), and 2 parts by mass of diethylthioxanthone (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) at 50°C for 1 hour.

[0111] <Preparation of Phase Contrast Film> <<Preparation Example 3>> A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF's "Paliocolor LC242," chemical formula below) was dissolved in cyclopentanone to prepare a solution with a solid content of 30% by mass. [ka] A surfactant (BYK-360, manufactured by BY-Chemie) and a photopolymerization initiator (Omnirad907, manufactured by IGM Resins) were added to this solution to prepare a liquid crystal coating solution. The amount of surfactant added was 0.01 parts by mass per 100 parts by mass of the photopolymerizable liquid crystal compound. The amount of polymerization initiator added was 3 parts by mass per 100 parts by mass of the photopolymerizable liquid crystal compound. Furthermore, as a coating substrate, the surface of a long polyethylene terephthalate (PET) film (38 μm thick) was rubbed using a rubbing cloth and subjected to orientation treatment. The direction of the orientation treatment was set so that when bonded to the polarizer, it was at a 45° angle to the absorption axis of the polarizer when viewed from the viewing side. Next, the liquid crystal coating solution described above was applied to the orientation-treated surface using a bar coater, and the liquid crystal compound was oriented by heating and drying at 100°C for 3 minutes. The liquid crystal layer thus formed was cooled to room temperature (25°C), and then exposed to a nitrogen atmosphere with an integrated light intensity of 400 mJ / cm². 2 The liquid crystal layer was cured by irradiation with ultraviolet light. This formed a liquid crystal alignment solidification layer on the coated substrate. The liquid crystal alignment solidification layer was elongated. The thickness of the liquid crystal alignment solidification layer was 1 μm. 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.

[0112] <<Preparation Example 4>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 3, except for a slight adjustment of the coating thickness using a bar coater. 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.

[0113] <<Preparation Example 5>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 3, except that the coating thickness applied by the bar coater was slightly adjusted. 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.

[0114] <<Preparation Example 6>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 3, except for a slight adjustment of the coating thickness using a bar coater. 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.

[0115] <<Preparation Example 7>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 3, except for a slight adjustment of the coating thickness using a bar coater. 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.

[0116] <<Preparation Example 8>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 3, except for a slight adjustment of the coating thickness using a bar coater. 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.

[0117] <<Preparation Example 9>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 3, except that the direction of the orientation treatment was changed to 15° relative to the absorption axis axis of the polarizer when viewed from the viewing side, and the coating thickness was changed. The thickness of the liquid crystal alignment solidification layer was 2 μm. 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.

[0118] <<Preparation Example 10>> A liquid crystal alignment solidification layer was formed on the coated substrate in the same manner as in Preparation Example 7, except that the direction of the orientation treatment was changed to a 75° direction relative to the absorption axis axis of the polarizer when viewed from the viewing side. The thickness of the liquid crystal alignment solidification layer was 1 μm. 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.

[0119] <<Preparation Example 11>> As the first phase difference film, a stretched film containing COP (ZD12, manufactured by Nippon Zeon Co., Ltd.) was prepared. The stretched film had a refractive index of nx>ny>nz. The angle between the longitudinal direction and the slow 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.

[0120] <<Preparation Example 12>> As the first phase difference film, a stretched film containing COP (ZD12, manufactured by Zeon Corporation) was prepared. The stretched film had a refractive index of nx>ny>nz. The angle between the longitudinal direction and the slow 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.

[0121] <Preparation of the second phase difference film> <<Preparation Example 13>> 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. The surface of the first liquid crystal alignment solidified layer obtained in Preparation Example 9 and the surface of the second liquid crystal alignment solidified layer obtained in Preparation Example 10 were each treated with a corona treatment machine at a treatment density of 50 W·min / m². 2 We dealt with the coronavirus. Next, the 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 Machinery Co., Ltd., cell shape: honeycomb, gravure roll line count: 1000 lines / inch, rotation speed 130% / line speed) to form a coating film on the first liquid crystal alignment solidification layer. Furthermore, in the same manner as described above, the aqueous adhesive obtained in Preparation Example 1 was applied to the corona-treated surface of the second liquid crystal alignment solidification layer. Subsequently, the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer were bonded together using a lamination roll machine. More specifically, the first and second liquid crystal alignment solidified layers were passed through the lamination roll machine so that the coating on the first and second liquid crystal alignment solidified layers came into contact with each other. The line speeds for the first and second liquid crystal alignment solidified layers were 15 m / min. At this time, the angle between the slow axis direction of the first liquid crystal alignment solidified layer and the slow axis direction of the second liquid crystal alignment solidified layer was 60°. Subsequently, the coating film was heated and dried at 60°C for 10 minutes to cure the water-based adhesive and form an adhesive layer. Next, the coated substrate was peeled off and removed from both the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer. This resulted in the preparation of 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.

[0122] <Preparation of polarizers> <<Preparation Example 14>> As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and one side of the film was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by mass of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, with 13 parts by mass of potassium iodide. A 13 μm thick PVA-based resin layer was formed on the 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. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) (insolubilization treatment). Next, the laminate was immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a mass ratio of 1:7 with 100 parts by mass of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizer obtained would be the desired value (staining treatment). Next, the laminate was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by mass, potassium iodide concentration 5% by mass) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with 100 parts by mass of water) (washing treatment). Subsequently, the laminate was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this manner, a polarizer was formed on a thermoplastic resin substrate. The thickness of the polarizer was approximately 5.0 μm.

[0123] [Example 1] The liquid crystal alignment solidification layer obtained in Preparation Example 4 was used as the first phase difference film and was attached to the polarizer obtained in Preparation Example 14 using the ultraviolet-curable adhesive obtained in Preparation Example 2. More specifically, the UV-curable adhesive obtained in Preparation Example 2 was applied to the surface of the polarizer opposite to the thermoplastic resin substrate using an MCD coater (manufactured by Fuji Machinery Co., Ltd., cell shape: honeycomb, gravure roll line count: 1000 lines / inch, rotation speed 130% / line speed) to form a coating film on the polarizer. Similarly, 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 described above. Subsequently, the polarizer and the first phase difference film were bonded together such that the angle between the absorption axis of the polarizer and the slow phase axis of the first phase difference film was 45°. Next, the coating film containing the UV-curable adhesive was irradiated with ultraviolet light to cure the UV-curable adhesive and form a first adhesive layer as the first adhesive layer. Subsequently, the coated 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. This resulted in the production of an intermediate laminate having a laminated structure of a first phase difference film (liquid crystal alignment solidification layer), a first adhesive layer, and a polarizer.

[0124] Next, the intermediate laminate described above was bonded together with the second phase difference film obtained in Preparation Example 13 using the water-based adhesive obtained in Preparation Example 1. More specifically, the aqueous adhesive obtained in Preparation Example 1 was applied to the surface of the polarizer opposite to the first phase difference film using an MCD coater (manufactured by Fuji Machinery Co., Ltd., cell shape: honeycomb, gravure roll line count: 1000 lines / inch, rotation speed 130% / line speed) to form a coating on the polarizer. Similarly, the aqueous adhesive obtained in Preparation Example 1 was applied to the surface of the first liquid crystal alignment solidification layer opposite to the second liquid crystal alignment solidification layer. Subsequently, the polarizer and the second phase difference film were bonded together such that the angle between the absorption axis direction of the polarizer and the slow phase axis direction of the first liquid crystal alignment solidification layer was 15°, and the angle between the absorption axis direction of the polarizer and the slow phase axis direction of the second liquid crystal alignment solidification layer was 75°. Next, the coating film was heated and dried at 60°C for 10 minutes to cure the water-based adhesive and form a second adhesive layer as the second bonding layer. Subsequently, a (meth)acrylic adhesive was applied to the surface of the second liquid crystal alignment solidification layer opposite to the second adhesive layer to form an adhesive layer. The thickness of the adhesive layer was 15 μm.

[0125] 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. Table 1 shows the thickness of the optical laminate.

[0126] [Example 2] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Preparation Example 5 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0127] [Example 3] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Preparation Example 6 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0128] [Example 4] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Preparation Example 7 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0129] [Examples 5-8] An optical laminate was manufactured in the same manner as in 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.

[0130] [Comparative Example 1] An optical laminate was manufactured in the same manner as in Example 1, except that the stretched film obtained in Preparation Example 11 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0131] [Comparative Example 2] An optical laminate was manufactured in the same manner as in Example 1, except that the stretched film obtained in Preparation Example 12 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0132] [Comparative Example 3] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Preparation Example 3 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0133] [Comparative Example 4] An optical laminate was manufactured in the same manner as in Example 1, except that the liquid crystal alignment solidification layer obtained in Preparation Example 8 was used as the first phase difference film instead of the liquid crystal alignment solidification layer obtained in Preparation Example 4.

[0134] [Table 1]

[0135] [Table 2]

[0136] [evaluation] As is clear from Tables 1 and 2, when the first phase difference film includes an orientation solidification layer of liquid crystal compound, the in-plane phase difference Re(450) of the first phase difference film is between 100 nm and 130 nm, and the ratio of Re(450) / Re(550) in the first phase difference film exceeds 1, the optical laminate can be made thinner, and when the optical laminate is applied to an image display device, the visibility through polarized sunglasses can be improved. [Industrial applicability]

[0137] The optical laminate manufactured according to the embodiments of the present invention can be suitably used in image display devices (typically liquid crystal display devices and organic EL display devices). [Explanation of symbols]

[0138] 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

1. The device comprises a first phase difference film, a polarizer, and a second phase difference film in this order. The first phase difference film includes 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. An optical laminate in which Re(450) / Re(550) in the first phase difference film exceeds 1.

2. The optical laminate according to claim 1, wherein, in the stacking direction of the optical laminate, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the second phase difference film opposite to the polarizer is less than 15 μm.

3. The optical laminate according to claim 1, wherein, in the stacking direction of the optical laminate, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the second phase difference film opposite to the polarizer is less than 10 μm.

4. The optical laminate according to claim 1, further comprising an adhesive layer located on the opposite side of the polarizer to the second phase difference film.

5. The optical laminate according to claim 4, wherein, in the lamination direction of the optical laminate, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the adhesive layer opposite to the second phase difference film is less than 35 μm.

6. The optical laminate according to claim 4, wherein, in the stacking direction of the optical laminate, the distance from the surface of the first phase difference film opposite to the polarizer to the surface of the adhesive layer opposite to the second phase difference film is less than 25 μm.

7. The optical laminate according to claim 1, wherein the Re(450) / Re(550) ratio in the first phase difference film is 1.05 or more and 1.5 or less.

8. The optical laminate according to claim 1, wherein the angle between the slow phase axis direction of the first phase difference film and the absorption axis direction of the polarizer is 35° to 55°.

9. The optical laminate according to claim 1, wherein the second phase difference film functions as a λ / 4 plate.

10. The 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.

11. The second phase difference film includes an orientation solidification layer of liquid crystal compound, The optical laminate according to claim 1, wherein Re(450) / Re(550) in the second phase difference film is 1 or less.

12. The 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.

13. The first phase difference film and the polarizer are further bonded together by a first adhesive layer, The optical laminate according to claim 1, wherein the thickness of the first adhesive layer is less than 0.5 μm.

14. The optical laminate according to claim 13, wherein the first adhesive layer is a first adhesive layer.

15. The polarizer and the second phase difference film are further bonded together by a second adhesive layer, The optical laminate according to claim 13, wherein the thickness of the second adhesive layer is less than 0.5 μm.

16. The optical laminate according to claim 15, wherein the second adhesive layer is a second adhesive layer.

17. The optical laminate according to claim 16, wherein the second adhesive layer comprises a cured product of an aqueous adhesive containing an organosilicon compound.

18. The optical laminate according to claim 17, wherein the organosilicon compound comprises an amino-based silane coupling agent.

19. The optical laminate according to claim 17, wherein the organosilicon compound comprises an epoxy-based silane coupling agent.

20. An image display device comprising an optical laminate according to any one of claims 1 to 19.

21. The image display device according to claim 20, wherein the first phase difference film is positioned on the viewing side with respect to the polarizer.

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