Optical laminate and image display device

Abstract

Provided are an optical laminate and an image display device, the optical laminate being capable of achieving thinness and improving visual recognition through an optical member having a polarizing function when applied to an image display device. An optical laminate of an embodiment of the present application sequentially includes a first phase difference film, a polarizer, and a second phase difference film. The first phase difference film includes an alignment fixed layer of a liquid crystal compound. An in-plane phase difference Re(450) of the first phase difference film is 100 nm or more and 130 nm or less. Re(450) / Re(550) of the first phase difference film exceeds 1.

Description

Technical Field

[0001] This invention relates to optical laminates and image display devices. Background Technology

[0002] Previously, image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (such as organic EL displays and inorganic EL displays), have become rapidly popular. If a viewer looks at such an image display device through polarized sunglasses, the color of the image on the display device may be affected depending on the viewer's viewing angle, and the visual recognizability of the displayed image may be reduced.

[0003] To address this problem, an optical laminate comprising a phase difference film and a polarizer is proposed to be disposed on the visible side of the image display panel in an image display device (for example, see Patent Document 1).

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2024-124169 Summary of the Invention

[0005] The problem that the invention aims to solve In recent years, the applications of image display devices have expanded, sometimes requiring further thinning of optical laminates. However, in the optical laminate described in Patent Document 1, it is difficult to achieve thinning and to impart visual recognizability to the image display device through optical components that have a polarizing effect.

[0006] The main objective of this invention is to provide an optical laminate that can be made thin and, when applied to an image display device, can improve visual recognition over optical components that have a polarizing effect.

[0007] Methods for solving problems [1] The optical laminate of the embodiment of the present invention sequentially comprises a first retardation film, a polarizer, and a second retardation film. The first retardation film includes an alignment fixing layer of a liquid crystal compound. The in-plane phase difference Re(450) of the first retardation film is 100 nm or more and 130 nm or less. The Re(450) / Re(550) of the first retardation film exceeds 1.

[0008] [2] In the optical laminate described in [1] above, the dimension 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 stacking direction of the optical laminate can be less than 15 μm.

[0009] [3] In the optical laminate described in [1] above, the dimension 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 stacking direction of the optical laminate can be less than 10 μm.

[0010] [4] The optical laminate described in any one of [1] to [3] above may further include an adhesive layer. The adhesive layer is located on the opposite side of the polarizer relative to the second retardation film.

[0011] [5] In the optical laminate described above [4], the dimension 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 can be less than 35 μm.

[0012] [6] In the optical laminate described above [4], the dimension 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 stacking direction of the optical laminate can be less than 25 μm.

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

[0014] [8] In any of the optical laminates described in [1] to [7] above, the angle between the slow axis direction of the first phase difference film and the absorption axis direction of the polarizer can be 35° to 55°.

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

[0016]

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

[0017]

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

[10] above, the second retardation film may include an alignment fixing layer of a liquid crystal compound. The Re(450) / Re(550) of the second retardation film may be 1 or less.

[0018]

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

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

[0019]

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

[12] above may further include a first adhesive layer. The first adhesive layer adheres the first retardation film to the polarizer. The thickness of the first adhesive layer may be less than 0.5 μm.

[0020]

[14] In the optical laminate described in

[13] above, the first adhesive layer may be a first adhesive layer.

[0021]

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

[14] above may further include a second adhesive layer. The second adhesive layer adheres the polarizer to the second retardation film. The thickness of the second adhesive layer may be less than 0.5 μm.

[0022]

[16] In the optical laminate described in

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

[0023]

[17] In the optical laminate described in

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

[0024]

[18] In the optical laminate described above

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

[0025]

[19] In the optical laminate described in

[17] or

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

[0026]

[20] Another aspect of the present invention relates to an image display device comprising any one of the optical laminates described in any one of [1] to

[19] .

[0027]

[21] In the image display device described above

[20] , the first phase difference film is disposed on the visible side relative to the polarizer.

[0028] Invention Effects According to embodiments of the present invention, an optical laminate can be realized that is thinner and, when applied to an image display device, can improve visual recognition over optical components that have a polarizing effect. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0030] [Explanation of reference numerals in the attached figures] 1 First phase difference film 2 Second phase difference film 21 First liquid crystal alignment fixing layer 22 Second liquid crystal alignment fixing layer 3. Polarizer 4 First adhesive layer 41 First adhesive layer 5 Second adhesive layer 51 Second adhesive layer 6 Adhesive layer 100 optical laminates Detailed Implementation

[0031] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, in order to make the description clearer, the accompanying drawings sometimes schematically show the width, thickness, shape, etc. of various parts compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

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

[0033] (1) Refractive index (nx, ny, nz) “nx” is the refractive index in the direction where the refractive index is greatest in the plane (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0034] In the elliptic formula (x) 2 / a 2 )+(y 2 / b 2 In equation ()=1, let a be nx, b be ny, and x and y be the refractive indices in the x and y directions along the angle θ on the ellipse. Solve the simultaneous equations using y=x(tanθ) and the aforementioned nx and ny. The refractive index along the transmission axis is obtained by √(x... 2 +y 2 Find the answer.

[0035] The "average refractive index" is obtained by (nx + ny + nz) / 3.

[0036] (2) In-plane phase difference (Re) “Re(λ)” is the in-plane phase difference measured at 23°C using light with a wavelength of λnm. For example, “Re(550)” is the in-plane phase difference measured at 23°C using light with a wavelength of 550nm. Re(λ) is calculated using the formula: Re(λ) = (nx - ny) × d when the thickness of the layer (film) is set to d (nm).

[0037] (3) Phase difference in the thickness direction (Rth) “Rth(λ)” is the phase difference in the thickness direction measured at 23°C using light with a wavelength of λnm. For example, “Rth(550)” is the phase difference in the thickness direction measured at 23°C using light with a wavelength of 550nm. Rth(λ) is calculated using the formula: Rth(λ) = (nx - nz) × d when the thickness of the layer (film) is set to d (nm).

[0038] (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.

[0039] (5) Angle When referring to angles in this specification, the angle includes both clockwise and counterclockwise relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0040] (6) In fact, they are parallel or orthogonal The expressions "substantially parallel" and "approximately parallel" include cases where the angle between the two directions is within 0° ± 3°. Conversely, the expressions "substantially orthogonal" and "approximately orthogonal" include cases where the angle between the two directions is 90° ± 3°.

[0041] A. Overview of Optical Laminates Figure 1 This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0042] In one embodiment, the optical laminate 100 sequentially includes a first phase difference film 1, a polarizer 3, and a second phase difference film 2.

[0043] The polarizer 3 has a transmission axis that transmits polarized light vibrating in a specific direction and an absorption axis orthogonal to the transmission axis. Hereinafter, the direction of extension of the transmission axis will sometimes be referred to as the transmission axis direction, and the direction of extension of the absorption axis will be referred to as the absorption axis direction.

[0044] The first retardation film 1 includes an alignment-fixing layer of a liquid crystal compound (hereinafter, sometimes referred to as a liquid crystal alignment-fixing layer). In this specification, "alignment-fixing layer of a liquid crystal compound" means a layer in which the liquid crystal compound is aligned in a predetermined direction and its alignment state is fixed. It should be noted that "alignment-fixing layer" includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers as described later.

[0045] 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 greater than 100 nm and less than 130 nm.

[0046] The first retardation film 1 typically exhibits a positive wavelength dispersion characteristic where in-plane birefringence decreases with respect to the wavelength of the measured light. The Re(450) / Re(550) ratio in the first retardation film 1 exceeds 1.

[0047] With this configuration, since the first retardation film includes a liquid crystal alignment fixing layer, the difference between nx and ny of the first retardation film can be significantly increased compared to non-liquid crystal materials. Therefore, the thickness of the retardation film with the desired phase difference can be significantly reduced, resulting in the thinning of the optical laminate.

[0048] In addition, in the first phase difference film, the in-plane phase difference Re(450) is 100nm or more and 130nm or less, and Re(450) / Re(550) exceeds 1. Therefore, when the optical laminate is applied to an image display device, the visual recognition of the image display device with an optical component (hereinafter sometimes referred to as a polarizing component) having a polarizing effect can be improved.

[0049] Therefore, in image display devices that incorporate optical laminates while achieving a thinner profile, visual recognition across the polarizing element can be improved.

[0050] The refractive index of the first phase difference film 1 preferably exhibits the relationship nx>ny≥nz.

[0051] The first phase retardation film 1 typically functions as a λ / 4 plate. With this configuration, in an image display device equipped with an optical laminate, visual recognition across the polarizing element can be stably improved.

[0052] The in-plane phase difference Re(450) of the first phase retardation film 1 is preferably 105 nm or more, more preferably 110 nm or more. On the other hand, the in-plane phase difference Re(450) of the first phase retardation film 1 is preferably 125 nm or less, more preferably 120 nm or less.

[0053] The in-plane phase difference Re(550) of the first phase retardation 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 retardation film 1 is, for example, 120 nm or less, preferably 115 nm or less.

[0054] 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, more preferably 1.05 or more. On the other hand, Re(450) / Re(550) is, for example, 1.20 or less, or 1.50 or less, or 1.15 or less.

[0055] When the in-plane phase difference and / or Re(450) / Re(550) in the first phase difference film are in such a range, the visual recognition of the polarizing member can be improved more stably in an image display device equipped with an optical stack.

[0056] The angle between the slow axis direction of the first phase difference film 1 and the absorption axis direction of the polarizer 3 is, for example, 30°~60°, preferably 35°~55°, more preferably 40°~50°, and even more preferably 43°~47°.

[0057] With this configuration, visual recognition through the polarizing element can be further and more stably improved in image display devices.

[0058] The first phase difference film 1 can have a single-layer structure with a liquid crystal alignment fixing layer, or it can have a stacked structure including a liquid crystal alignment fixing layer.

[0059] In one embodiment, the first retardation film 1 has a single-layer structure with a liquid crystal alignment fixing layer. With this configuration, the thinning of the optical laminate can be stably achieved.

[0060] The thickness of the first phase difference film 1 can be arbitrarily and appropriately adjusted in order to obtain the desired phase difference.

[0061] The thickness of the first retardation 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 retardation 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.

[0062] The refractive index of the first retardation film 1 in the transmission axis direction is, for example, 1.45 or more, preferably 1.50 or more. On the other hand, the refractive index of the first retardation film 1 in the transmission axis direction is, for example, 1.70 or less, preferably less than 1.60, and more preferably 1.58 or less.

[0063] It should be noted that the refractive index is determined, for example, by using a thin-film waveguide method (prism coupler) with a wavelength of 594 nm.

[0064] 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.

[0065] The thickness of the polarizer 3 is, for example, 1μm to 80μm, preferably 1μm to 15μm, more preferably 1μm to 12μm, and even more preferably 3μm to 8μm.

[0066] If the polarizer has such a thickness, further thinning of the optical laminate can be achieved.

[0067] In one embodiment, the polarizer 3 is bonded to the first retardation film 1 via the first adhesive layer 4. In other words, the optical laminate 100 also includes the first adhesive layer 4. In the example shown, the first adhesive layer 4 is in contact with both the polarizer 3 and the first retardation film 1.

[0068] 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, especially preferably 0.12 μm or less, particularly preferably 0.05 μm or less, and most preferably 0.04 μm or less.

[0069] If the first retardation film includes a liquid crystal alignment fixing layer, it can be made thinner and thicker than when the first retardation film is made of a non-liquid crystal material (represented by resin), and has a larger refractive index. Therefore, light reflection and interference are more likely to occur at the interface between the first retardation film and its adjacent layers.

[0070] However, in one embodiment, the thickness of the first adhesive layer is adjusted to be below such an upper limit, thus making the first adhesive layer sufficiently thin relative to the wavelength of visible light. Therefore, even if the first adhesive layer and the first retardation film are adjacent to each other, it is possible to suppress the reflection of external light (visible light) at the interface between the first adhesive layer and the first retardation film, and the interference caused by the reflected light. As a result, in an image display device equipped with an optical laminate, interference unevenness that produces black display coloring can be suppressed.

[0071] 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.

[0072] When the thickness of the first adhesive layer is above such a lower limit, the adhesive force of the first adhesive layer can be improved, and the layers adjacent to the first adhesive layer (representatively polarizer and first phase difference film) can be stably bonded.

[0073] The refractive index of the first adhesive layer 4 in the transmission axis direction is, for example, 1.40 or more, preferably 1.43 or more, and more preferably 1.45 or more. On the other hand, the refractive index of the first adhesive layer 4 in the transmission axis direction is, for example, 1.70 or less, preferably 1.60 or less.

[0074] The absolute value of the difference between the refractive index of the first adhesive layer 4 and the refractive index of the first retardation 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 retardation film 1 in the transmission axis direction is typically 0.

[0075] When the refractive index difference between the first adhesive layer and the first retardation film is within such a range, even if the first adhesive layer and the first retardation 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 retardation film can be stably suppressed.

[0076] The first adhesive layer 4 can be an adhesive layer composed of adhesive or an adhesive layer composed of adhesive.

[0077] In one embodiment, the first adhesive layer 4 is a first adhesive layer 41 consisting of an adhesive (more specifically, a cured adhesive).

[0078] In the adhesive layer, due to curing shrinkage, uneven application, coating depressions, uneven drying, etc., ripples and / or uneven thickness may sometimes occur in the adhesive layer. In this case, due to the undulations and / or uneven thickness of the adhesive layer, uneven optical path lengths may occur in the optical laminate, resulting in interference unevenness in image display devices equipped with optical laminates.

[0079] In this regard, according to one embodiment, the thickness of the first adhesive layer 41 is within the aforementioned range, thus sufficiently reducing the degree of adhesive curing shrinkage, uneven application, application depressions, uneven drying, etc., and significantly suppressing the generation of undulations and / or thickness unevenness in the first adhesive layer. Therefore, it is possible to reduce the unevenness of optical path length in the optical laminate and more stably suppress interference unevenness in the image display device.

[0080] The second phase difference film 2 is located on the opposite side of the first phase difference film 1 relative to the polarizer 3.

[0081] Typically, the second retardation film 2 has an in-plane phase difference. In this case, the refractive index of the second retardation film 2 exhibits, for example, a relationship of nx > ny, and preferably a relationship of nx > ny ≥ nz.

[0082] In one embodiment, the second retardation film 2 functions as a λ / 4 plate. This configuration imparts anti-reflective properties to the optical laminate.

[0083] The in-plane phase difference Re(550) of the second phase difference film 2 is, for example, 90nm~160nm, preferably 100nm~150nm.

[0084] The second phase difference film 2 can show the inverse wavelength dispersion characteristics of in-plane birefringence that increase with the wavelength of the measured light, the positive wavelength dispersion characteristics of in-plane birefringence that decrease with the wavelength of the measured light, and the flat wavelength dispersion characteristics of in-plane birefringence that hardly change with the wavelength of the measured light.

[0085] In one embodiment, the second phase difference film 2 exhibits inverse wavelength dispersion characteristics.

[0086] The Re(450) / Re(550) ratio in the second phase retardation film 2 is, for example, 1 or less, preferably less than 0.9, and more preferably 0.85 or less. On the other hand, the Re(450) / Re(550) ratio in the second phase retardation film 2 is, for example, 0.7 or more, preferably 0.75 or more.

[0087] When the Re(450) / Re(550) ratio in the second phase retardation film is in such a 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 functions as a λ / 4 plate at any wavelength, thus providing good anti-reflection properties at any wavelength.

[0088] The second phase difference film 2 can have a single-layer structure or a stacked structure.

[0089] The second phase difference film 2 typically includes a stretch film modulated by stretching a film made of transparent resin, and / or a liquid crystal alignment fixing layer.

[0090] In one embodiment, the second retardation film 2 includes a liquid crystal alignment fixing layer. More specifically, the second retardation film 2 has a stacked structure comprising multiple liquid crystal alignment fixing layers. In the example shown, the second retardation film 2 sequentially includes a first liquid crystal alignment fixing layer 21, an adhesive layer 23, and a second liquid crystal alignment fixing layer 22.

[0091] The thickness of the second phase difference film 2 can be arbitrarily and appropriately adjusted in order to obtain the desired phase difference.

[0092] In one embodiment, the thickness of the second phase retardation film 2 is greater than the thickness of the first phase retardation film 1.

[0093] The thickness of the second phase retardation film 2 is, for example, 1.5 times or more, preferably 2 times or more, relative to the thickness of the first phase retardation film 1. On the other hand, the thickness of the second phase retardation film 2 is, for example, 6 times or less, preferably 4 times or less, relative to the thickness of the first phase retardation film 1.

[0094] 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.

[0095] When the second retardation film has such a thickness, it is possible to stably achieve thinning of the optical laminate and to impart sufficient operability, i.e., self-sufficiency / process flowability, to the optical laminate. In addition, the center of gravity of the polarizer can be raised in the lamination direction of the optical laminate, so even if the polarizer expands or contracts during durability testing, damage to the image display device can be reduced.

[0096] In one embodiment, the second retardation film 2 is bonded to the polarizer 3 via a second adhesive layer 5. In other words, the optical laminate 100 also includes a second adhesive layer 5. In the example shown, the second adhesive layer 5 is in contact with the polarizer 3 and the first liquid crystal alignment fixing layer 21.

[0097] 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.

[0098] When the thickness of the second adhesive layer is below this upper limit, the second adhesive layer can be sufficiently thinned relative to the wavelength of visible light. Therefore, even if the second retardation film includes a liquid crystal alignment fixing layer, interference of light in the optical stack can be sufficiently suppressed. As a result, interference inhomogeneity can be stably suppressed in an image display device equipped with an optical stack.

[0099] 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.

[0100] When the thickness of the second adhesive layer is above such a lower limit, the adhesive force of the second adhesive layer can be improved, and the layers adjacent to the second adhesive layer (representatively polarizers and second phase difference films) can be stably bonded.

[0101] The range of the refractive index of the second adhesive layer 5 in the transmission axis direction is, for example, the same as the range of the refractive index of the first adhesive layer 4 described above. Furthermore, the range of the absolute value of the difference between the refractive index of the second adhesive layer 5 in the transmission axis direction and the refractive index of the second retardation film 2 (typically the first liquid crystal alignment fixing layer 21) is, for example, the same as the range of the absolute value of the difference between the refractive index of the first adhesive layer 4 and the refractive index of the first retardation film 1 described above.

[0102] When the refractive index difference between the second adhesive layer and the second retardation film is within such a range, even if the second adhesive layer and the second retardation 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 retardation film can be stably suppressed.

[0103] The second adhesive layer 5 can be an adhesive layer composed of adhesive or an adhesive layer composed of adhesive.

[0104] In one embodiment, the second adhesive layer 5 is a second adhesive layer 51 composed of an adhesive (more specifically, a cured adhesive). In one embodiment, the thickness of the second adhesive layer 51 is within the range described above, thus sufficiently reducing the degree of adhesive curing shrinkage, uneven application, application depressions, uneven drying, etc., and significantly suppressing the generation of undulations and / or thickness unevenness in the second adhesive layer. Therefore, it is possible to reduce the unevenness of optical path length in the optical laminate and more stably suppress interference unevenness in the image display device.

[0105] In one embodiment, the optical laminate 100 further includes an adhesive layer 6. The adhesive layer 6 is located on the side opposite to the polarizer 3 relative to the second retardation film 2. In the example shown, the adhesive layer 6 is laminated on the surface of the second liquid crystal alignment fixing layer 22 opposite to the first liquid crystal alignment fixing layer 21.

[0106] With this configuration, the optical laminate can be bonded to any suitable substrate (typically an image display panel) of the image display device using the adhesive layer 6.

[0107] The thickness of the adhesive layer 6 is, for example, 3 μm or more, preferably 5 μm or more, and more 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.

[0108] In the stacking direction of such an optical laminate 100, the dimension from the surface of the first retardation film 1 opposite to the polarizer 3 to the surface of the second retardation film 2 opposite to the polarizer 3 is, for example, 20 μm or less, preferably less than 15 μm, more preferably less than 12 μm, even more preferably less than 10 μm, and especially preferably less than 9.5 μm.

[0109] With this configuration, the thinning of optical laminates can be stably achieved.

[0110] Furthermore, in the stacking direction of the optical laminate 100, the dimension 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 less than 30 μm, even more preferably less than 25 μm, and especially preferably less than 24.5 μm.

[0111] This configuration allows for a more stable and thinner optical laminate.

[0112] B. Details of the optical laminate Next, refer to Figure 1 The details of an optical laminate according to one embodiment will be described.

[0113] like Figure 1 As shown, in one embodiment, the optical laminate 100 sequentially comprises a first phase retardation film 1, a first adhesive layer 41, a polarizer 3, a second adhesive layer 51, and a second phase retardation film 2.

[0114] B-1. First phase difference film In one embodiment, the first phase difference film 1 has a single-layer structure with a liquid crystal alignment fixing layer.

[0115] In such a first phase reversal film 1, the rod-shaped liquid crystal compounds are oriented (uniformly oriented) in a state of being arranged along a predetermined direction of the first phase reversal film 1.

[0116] Examples of liquid crystal compounds include those 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 can be used individually or in combination.

[0117] The liquid crystal properties of liquid crystal compounds can be expressed by either lyotropic or thermotropic mechanisms.

[0118] When the liquid crystal compound contains liquid crystal monomers, these monomers are preferably polymerizable or crosslinkable monomers. By polymerizing or crosslinking the liquid crystal monomers (i.e., curing), the orientation state of the liquid crystal monomers can be fixed. After aligning the liquid crystal monomers, for example, if the liquid crystal monomers are polymerized or crosslinked with each other, the aforementioned orientation state can be fixed. Here, polymers are formed through polymerization, and three-dimensional network structures are formed through crosslinking, but these are non-liquid crystals. Therefore, the formed liquid crystal alignment-fixed layer does not undergo, for example, the transformation to a liquid crystal phase, glassy phase, or crystalline phase caused by temperature changes characteristic of liquid crystal compounds. As a result, the first retardation film can possess extremely excellent stability unaffected by temperature changes.

[0119] Any suitable liquid crystal monomer can be used. Examples of liquid crystal monomers include polymerizable mesocrystalline compounds described in Japanese Patent Application Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445.

[0120] Specific examples of such polymeric mesocrystalline compounds include BASF's LC242, Merck's E7, and Wacker-Chem's LC-Sillicon-CC3767.

[0121] A liquid crystal alignment fixing layer can be formed by applying an appropriate alignment treatment to any suitable coating substrate, coating the surface with a coating liquid containing a liquid crystal compound, and aligning the liquid crystal compound in a direction corresponding to the above alignment treatment, thereby fixing the alignment state.

[0122] Examples of orientation treatments include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment.

[0123] Specific examples of liquid crystal compounds and detailed methods for forming alignment fixing layers are described in Japanese Patent Application Publication No. 2006-163343. The contents of that publication are incorporated herein by reference.

[0124] The birefringence Δn of the first phase retardation film 1 (liquid crystal alignment fixing 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 retardation film 1 (liquid crystal alignment fixing layer) is, for example, 0.13, or for example, 0.12. If Δn is in such a range, the desired in-plane phase difference can be achieved with a very thin thickness.

[0125] B-2. Polarizer As the polarizer 3, any suitable polarizer can be used. For example, the polarizer can be made of a single layer of resin film, or it can be obtained by using a laminate of two or more layers.

[0126] Specific examples of polarizers composed of single-layer resin films include polarizers obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (PVA)-based resin films, partially formalized PVA-based resin films, and partially saponified ethylene-vinyl acetate copolymer-based films using dichroic substances such as iodine and dichroic dyes; and polyene-based oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. From the perspective of superior optical properties, polarizers obtained by dyeing PVA-based resin films with iodine and then uniaxially stretching them are preferred.

[0127] Specific examples of polarizers obtained using laminates include those using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or those using a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, as follows: a PVA-based resin solution is coated onto a resin substrate, dried to form a PVA-based resin layer on the resin substrate, resulting in a laminate of the resin substrate and the PVA-based resin layer; the laminate is then stretched and dyed to make the PVA-based resin layer a polarizer. In one embodiment, a polyvinyl alcohol (PVA) resin layer comprising a halide and a polyvinyl alcohol resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, the laminate may be subjected to air stretching at a high temperature (e.g., above 95°C) before further stretching in the aqueous boric acid solution, as needed. Furthermore, in one embodiment, the laminate is preferably subjected to a drying shrinkage treatment that causes it to shrink by 2% or more in the width direction while being heated and conveyed along its length. Typically, the manufacturing method of this embodiment includes sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing assisted stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, resulting in high optical properties. Additionally, by simultaneously improving the orientation of PVA beforehand, problems such as reduced orientation and dissolution of PVA can be prevented when immersed in water during subsequent dyeing and stretching processes, further achieving high optical properties. Moreover, when the PVA-based resin layer is immersed in a liquid, compared to cases where the PVA-based resin layer does not contain halides, the disorder of polyvinyl alcohol molecule orientation and the reduction of orientation can be suppressed. Therefore, the optical properties of the polarizer obtained by immersing the laminate in a liquid through dyeing and underwater stretching treatments can be improved. Furthermore, the drying shrinkage treatment shrinks the laminate in the width direction, thereby improving optical properties. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface for use. Detailed descriptions of such a polarizer manufacturing method are provided, 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.

[0128] The aforementioned dyeing using iodine is performed, for example, by immersing the PVA-based resin film in an aqueous iodine solution. The stretching ratio for the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. Depending on the needs, the PVA-based resin film may undergo swelling treatment, crosslinking treatment, cleaning treatment, drying treatment, etc. For example, by immersing the PVA-based resin film in water for washing before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based resin film be cleaned, but the PVA-based resin film can also swell to suppress uneven dyeing.

[0129] The polarizer 3 typically exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The transmittance of a single unit of the 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 a single unit of the polarizer 3 is typically 46.0%.

[0130] The polarization degree of the polarizer 3 is, for example, 97.0% or more, preferably 99.0% or more, and more preferably 99.9% or more.

[0131] 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.

[0132] B-3. ​​Second phase difference film In one embodiment, the second phase difference film 2 includes a first liquid crystal alignment fixing layer 21, an adhesive layer 23, and a second liquid crystal alignment fixing layer 22.

[0133] B-3-1. First liquid crystal alignment fixing layer The first liquid crystal alignment fixing layer 21 can have an in-plane phase difference or a phase difference in the thickness direction. The first liquid crystal alignment fixing layer 21 can function as a λ / 4 plate, or as a λ / 2 plate, λ / 5 plate, λ / 6 plate, or C-Plate.

[0134] In one embodiment, the first liquid crystal alignment fixing layer 21 has an in-plane phase difference. In this case, the refractive index of the first liquid crystal alignment fixing layer 21 preferably exhibits the relationship nx>ny≥nz.

[0135] In another embodiment, the first liquid crystal alignment fixing layer 21 has a phase difference in the thickness direction, but substantially no in-plane phase difference. In this case, the refractive index of the first liquid crystal alignment fixing layer 21 exhibits, for example, a relationship of nx=ny, preferably a relationship of nz>nx=ny. It should be noted 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, without impairing the effects of the present invention, sometimes nx>ny or nx <ny。

[0136] The refractive index of the first liquid crystal alignment fixing layer 21 in the transmission axis direction is, for example, 1.45 or more, or 1.50 or more, or 1.55 or more, or more than 1.60, or 1.61 or more. On the other hand, the upper limit of the refractive index of the first liquid crystal alignment fixing layer 21 in the transmission axis direction is typically 1.70.

[0137] The thickness of the first liquid crystal alignment fixing layer 21 can be arbitrarily and appropriately adjusted to obtain the desired phase difference.

[0138] The thickness of the first liquid crystal alignment fixing 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 fixing layer 21 is typically 1 μm.

[0139] The liquid crystal compound contained in the first liquid crystal alignment fixing layer 21 will be described in the same manner as the liquid crystal compound contained in the first retardation film 1. Therefore, the description of the liquid crystal compound contained in the first liquid crystal alignment fixing layer 21 will be omitted as appropriate.

[0140] B-3-2. Second liquid crystal alignment fixing layer The second liquid crystal alignment fixing layer 22 is located on the opposite side of the polarizer 3 relative to the first liquid crystal alignment fixing layer 21 in the stacking direction of the optical laminate 100. In one embodiment, the second liquid crystal alignment fixing layer 22 is bonded to the first liquid crystal alignment fixing layer 21 via an adhesive layer 23.

[0141] The second liquid crystal alignment fixing layer 22 can have an in-plane phase difference or a phase difference in the thickness direction. The second liquid crystal alignment fixing layer 22 can function as a λ / 4 plate, or as a λ / 2 plate, λ / 5 plate, λ / 6 plate, or C-Plate.

[0142] The second liquid crystal alignment fixing layer 22 will be described in the same manner as the first liquid crystal alignment fixing layer 21 described above. Therefore, a detailed description of the second liquid crystal alignment fixing layer 22 will be omitted as appropriate.

[0143] The refractive index of the second liquid crystal alignment fixing layer 22 can show a relationship of nx>ny or nx=ny.

[0144] In one embodiment, the refractive indices of the first liquid crystal alignment fixing layer 21 and the second liquid crystal alignment fixing layer 22 exhibit a relationship of nx > ny. With this configuration, excellent wavelength dispersion characteristics can be achieved, exceeding those of the second retardation film. Furthermore, viewing angle characteristics, i.e., optical characteristics relative to any azimuth or polar angle, can also be improved.

[0145] The ranges of phase difference, refractive index, and thickness in the second liquid crystal alignment fixing layer 22 are, for example, the same as the ranges of phase difference, refractive index, and thickness in the first liquid crystal alignment fixing layer 21 described above.

[0146] B-3-3. Combination of the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer In one embodiment, the first liquid crystal alignment fixing layer 21 functions as a λ / 2 plate, and the second liquid crystal alignment fixing layer 22 functions as a λ / 4 plate. It should be noted that the first liquid crystal alignment fixing layer 21 can function as a λ / 4 plate, and the second liquid crystal alignment fixing layer 22 can function as a λ / 2 plate. Sometimes, the combination of two phase retardation films as a λ / 2 plate and a λ / 4 plate is referred to as the first combination.

[0147] With this configuration, the wavelength dispersion characteristics of the second retardation film, which includes a first liquid crystal alignment fixing layer and a second liquid crystal alignment fixing layer, can approach the ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflective properties can be imparted to the optical laminate.

[0148] In the first combination, the in-plane phase difference Re(550) of the liquid crystal alignment fixing layer that functions as the λ / 4 plate is, for example, 90nm~180nm, preferably 100nm~160nm, and more preferably 110nm~150nm.

[0149] In the first combination, the in-plane phase difference Re(550) of the liquid crystal alignment fixing layer that functions as the λ / 2 plate is, for example, 200nm~300nm, preferably 220nm~290nm, and more preferably 230nm~280nm.

[0150] In the first combination, the angle between the absorption axis direction of the polarizer 3 and the slow axis direction of the first liquid crystal alignment fixing layer 21 is, for example, 10°~20°, preferably 12°~18°, and more preferably 14°~16°.

[0151] In addition, in the first combination, the angle between the absorption axis direction of the polarizer 3 and the slow axis direction of the second liquid crystal alignment fixing layer 22 is, for example, 70°~80°, preferably 72°~78°, and more preferably 74°~76°.

[0152] It should be noted that, in the first combination, the range of the angle between the absorption axis direction of the polarizer and the slow axis direction of the first liquid crystal alignment fixing layer and the range of the angle between the absorption axis direction of the polarizer and the slow axis direction of the second liquid crystal alignment fixing layer can be opposite.

[0153] With this configuration, the wavelength dispersion characteristics of the second retardation film, which has a first liquid crystal alignment fixing layer and a second liquid crystal alignment fixing layer, can be made closer to the ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflection properties can be stably imparted to the optical laminate.

[0154] The first liquid crystal alignment fixing layer 21 can function as a λ / 4 plate, and the second liquid crystal alignment fixing layer 22 can function as a C-plate (i.e., nx = ny). It should be noted that the first liquid crystal alignment fixing layer 21 can function as a C-plate, and the second liquid crystal alignment fixing layer 22 can function as a λ / 4 plate. Sometimes, the combination of the two retardation films as a λ / 4 plate and a C-plate is called a second combination. With this configuration, excellent anti-reflective properties can also be imparted to the optical laminate.

[0155] However, the first combination described above is better than the second combination. If the combination of the two phase retardation films is a λ / 2 plate and a λ / 4 plate, then interference inhomogeneity in an image display device equipped with an optical stack can be stably reduced.

[0156] In the second combination, the in-plane phase difference Re(550) of the liquid crystal alignment fixing layer that functions as the λ / 4 plate is, for example, 90nm~190nm, preferably 100nm~170nm, and more preferably 110nm~160nm.

[0157] In the second combination, the phase difference Rth(550) in the thickness direction of the liquid crystal alignment fixing layer that functions as C-Plate is, for example, -200nm or more and 200nm or less, preferably -200nm or more and less than 0nm, and more preferably -140nm or more and -100nm or less.

[0158] In the second combination, the angle between the slow axis direction of the liquid crystal alignment fixing layer, which functions as the λ / 4 plate, and the absorption axis direction of the polarizer 3 can be adjusted arbitrarily and appropriately.

[0159] This configuration also allows for the stable imparting of excellent anti-reflective properties to the optical laminate.

[0160] B-3-4. Adhesive layer The adhesive layer 23 is located between the first liquid crystal alignment fixing layer 21 and the second liquid crystal alignment fixing layer 22 in the stacking direction of the optical laminate 100, bonding the first liquid crystal alignment fixing layer 21 and the second liquid crystal alignment fixing layer 22 together. The adhesive layer 23 is in contact with both the first liquid crystal alignment fixing layer 21 and the second liquid crystal alignment fixing layer 22.

[0161] In one embodiment, the contact surfaces of the first liquid crystal alignment fixing layer 21 with the adhesive layer 23 and / or the contact surfaces of the second liquid crystal alignment fixing layer 22 with the adhesive layer 23 are activated surfaces that have undergone activation treatment. With this configuration, polar groups such as hydroxyl groups can be introduced onto the surface of the liquid crystal alignment fixing layer, resulting in improved adhesion between the liquid crystal alignment fixing layer and the adhesive layer.

[0162] Examples of activation treatments include corona treatment, plasma treatment, saponification treatment, and low-pressure UV treatment. Activation treatments can be carried out alone or in combination.

[0163] Adhesive layer 23 will be described in the same manner as the first adhesive layer 4 described above. Therefore, the description of adhesive layer 23 will be omitted as appropriate.

[0164] 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.

[0165] The range of the refractive index of the adhesive layer 23 in the transmission axis direction is, for example, the same as the range of the refractive index of the first adhesive layer 4 described above. Furthermore, the range of the absolute value of the difference between the refractive index of the adhesive layer 23 in the transmission axis direction and the refractive index of the liquid crystal alignment fixing layer (first liquid crystal alignment fixing layer 21 or second liquid crystal alignment fixing layer 22) is, for example, the same as the range of the absolute value of the difference between the refractive index of the first adhesive layer 4 and the refractive index of the first retardation film 1 described above.

[0166] The adhesive layer 23 can be an adhesive layer made of adhesive or an adhesive layer made of adhesive.

[0167] 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 will be described in the same manner as the first adhesive layer 41 and the second adhesive layer 51. Therefore, a detailed description of the adhesive layer 231 is omitted.

[0168] 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 the first phase difference film 1 and the polarizer 3 are bonded together.

[0169] The second adhesive layer 51 (second adhesive layer 5) is located between the polarizer 3 and the second retardation film 2 in the stacking direction of the optical laminate 100, bonding the polarizer 3 and the second retardation film 2. In the example shown, the second adhesive layer 51 bonds the polarizer 3 to the first liquid crystal alignment fixing layer 21.

[0170] The first adhesive layer 41 and the second adhesive layer 51 will be described similarly, except for their arrangement in the optical laminate 100. It should be noted that, hereinafter, without distinguishing between the first adhesive layer 41 and the second adhesive layer 51, they will sometimes be referred to simply as adhesive layers.

[0171] The first adhesive layer 41 and / or the second adhesive layer 51 contain cured products of any suitable adhesive.

[0172] 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.

[0173] Adhesives can be used alone or in combination.

[0174] In one embodiment, the first adhesive layer 41 and / or the second adhesive layer 51 comprise a cured product of an aqueous adhesive. If the adhesive layer comprises a cured product of an aqueous adhesive, the thickness of the adhesive layer can be stably adjusted to the range described above, and the generation of interference inhomogeneities in the optical laminate can be sufficiently suppressed.

[0175] Water-based adhesives before curing typically contain curing components and solvents containing water.

[0176] Typically, the cured components can be dissolved and / or dispersed in a solvent.

[0177] The curing component can be cured through any suitable chemical reaction. Examples of curing components include combinations of polyvinyl alcohol (PVA) and crosslinking agents, and organosilane compounds. The curing component can be used alone or in combination.

[0178] The following is sometimes referred to as water-based adhesive containing PVA and crosslinking agents as curing components.

[0179] Crosslinking agents can crosslink PVA, thereby curing water-based adhesives. Examples of crosslinking agents include melamine resins such as hydroxymethyl melamine; alkylene diamines; isocyanates; epoxy resins; and aldehydes. Crosslinking agents can be used alone or in combination.

[0180] The crosslinking agent in the water-based adhesive contains, for example, 10 to 50 parts by weight of PVA 100 parts by weight, preferably 20 to 40 parts by weight.

[0181] In addition to PVA and crosslinking agents, water-based adhesives containing PVA may further contain metal compound colloids.

[0182] Metal compound colloids are colloids in which metal compound particles are dispersed in a solvent. They are electrostatically stabilized due to the mutual repulsion of like charges among the particles, and thus can maintain stability for a long time.

[0183] Examples of metal compounds include metal oxides such as aluminum oxide, silicon oxide, zirconium oxide, and titanium oxide; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; and minerals such as diatomaceous earth, talc, clay, and kaolin. Metal compounds can be used alone or in combination.

[0184] The average particle size of the microparticles forming the metal compound colloid can be adjusted arbitrarily and appropriately. The average particle size is, for example, 1 nm to 100 nm, preferably 1 nm to 50 nm. When the average particle size is within this range, the microparticles can be uniformly dispersed in the adhesive layer.

[0185] The proportion of metal compound colloids in water-based adhesives can be adjusted arbitrarily and appropriately.

[0186] Hereinafter, aqueous adhesives containing organosilane compounds as curing components are sometimes referred to as aqueous adhesives containing organosilanes.

[0187] Organosilane compounds typically have alkoxysilyl and / or silanol groups (hydroxysilyl). If an organosilane compound has alkoxysilyl and / or silanol groups, it can cure aqueous adhesives through a dehydration condensation reaction.

[0188] Examples of organosilane compounds include silane coupling agents having alkoxysilyl and / or silanol groups and organic functional groups.

[0189] Examples of organic functional groups that can be found in silane coupling agents include amino, epoxy, and methoxy groups. Silane coupling agents can have one type of organic functional group or a combination of two or more. If a silane coupling agent possesses such organic functional groups, the adhesive strength of the adhesive layer can be improved.

[0190] These silane coupling agents can be used alone or in combination.

[0191] 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. With this configuration, the adhesive strength of the adhesive layer can be improved, and the adhesive layer can be made thinner.

[0192] Amino-based silane coupling agents have any suitable structure comprising amino and alkoxysilyl groups and / or silanol groups.

[0193] Examples of amino-based silane coupling agents include, for example, N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and their hydrochlorides.

[0194] As an amino-based silane coupling agent, any suitable commercially available product can be used.

[0195] Commercially available amino-based silane coupling agents include, for example, 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 Dow Corning Toray Co., Ltd.), A-1100, A-1110, A-1120, A-2120, and Y-9669 (all manufactured by Momentive Performance Materials Co., Ltd.).

[0196] Epoxy silane coupling agents have any suitable structure containing epoxy and alkoxysilyl groups and / or silanol groups.

[0197] Examples of epoxy-based silane coupling agents include 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, and 3-epoxypropoxypropyltriethoxysilane.

[0198] As an epoxy silane coupling agent, any suitable commercially available product can be used.

[0199] Commercially available epoxy silane coupling agents include, for example, 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 Dow Corning Toray Co., Ltd.), A-186, A-187, and A-1871 (all manufactured by Momentive Performance Materials Co., Ltd.).

[0200] When organosilicon compounds contain both amino-based and epoxy-based silane coupling agents, the amino groups of the amino-based silane coupling agent can react with the epoxy groups of the epoxy-based silane coupling agent. Therefore, water-based adhesives can be stably cured, and further thinning of the adhesive layer is possible.

[0201] The molar ratio of amino-based silane coupling agent to epoxy-based silane coupling agent (amino-based silane coupling agent: epoxy-based silane coupling agent) is, for example, 8:92 to 60:40, preferably 10:90 to 55:45.

[0202] If the molar ratio of amino-based silane coupling agent to epoxy-based silane coupling agent is within this range, the adhesive layer can be made to be thinner and more stable.

[0203] The curing component in the water-based adhesive contains, for example, less than 50% by mass, preferably less than 40% by mass, more preferably less than 30% by mass, even more preferably less than 20% by mass, particularly preferably less than 10% by mass, especially preferably less than 5% by mass, and most preferably less than 2% by mass.

[0204] 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.

[0205] As mentioned above, the solvent in water-based adhesives contains water.

[0206] In addition to water, solvents can also include organic solvents.

[0207] 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.

[0208] Organic solvents can be used alone or in combination.

[0209] 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.

[0210] In one embodiment, the solvent of the water-based adhesive substantially does not contain 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.

[0211] When the water content in the solvent of a water-based adhesive is within a certain range, the solvent can evaporate smoothly during the coating and drying process, enabling stable thinning of the adhesive layer. Furthermore, water causes minimal damage to the polarizer and retardation film, thus allowing for the stable manufacture of optical laminates with excellent quality.

[0212] The solvent content in water-based adhesives can be adjusted arbitrarily and appropriately according to the content of the curing components.

[0213] Water-based adhesives may contain any appropriate additives as needed.

[0214] Examples of additives include amino compounds, epoxy compounds, adhesive resins, surfactants, plasticizers, tackifiers, low molecular weight polymers, polymerizable monomers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, titanium coupling agents, inorganic or organic fillers, metal powders, granules, and foils.

[0215] Added materials can be used alone or in combination.

[0216] Among the added materials, surfactants are preferred.

[0217] The proportion of the additive material relative to 1 part by mass of the cured component 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. On the other hand, the lower limit of the proportion of the additive material relative to 1 part by mass of the cured component is typically 0 parts by mass.

[0218] In one embodiment, the first adhesive layer 41 and the second adhesive layer 51 each comprise a cured product of the aforementioned aqueous adhesive. With this configuration, the first and second adhesive layers can be sufficiently thin, resulting in significant suppression of uneven optical path lengths in the optical laminate.

[0219] In this case, the cured aqueous adhesive contained in the first adhesive layer 41 and the cured aqueous adhesive contained in the second adhesive layer 51 may be the same as each other or different from each other.

[0220] In one embodiment, the cured aqueous adhesive contained in the first adhesive layer 41 is identical to the cured aqueous adhesive contained in the second adhesive layer 51. This allows the refractive index of the first adhesive layer 41 in the transmission axis direction and the refractive index of the second adhesive layer 51 in the transmission axis direction to be substantially the same.

[0221] Furthermore, the adhesive layer 231 of the second phase retardation film 2 may also contain a cured product of the aforementioned aqueous adhesive. This allows for the thinning of the second phase retardation film.

[0222] It should be noted that the solvents in these adhesive layers (first adhesive layer 41, second adhesive layer 51, and / or adhesive layer 231) evaporate during the formation process, and therefore do not substantially contain the aforementioned solvents. The solvent content in the adhesive layers is, for example, 0.05% by mass or less, preferably 0.01% by mass or less.

[0223] B-5. Adhesive layer In one embodiment, the optical laminate 100 includes an adhesive layer 6. In the example shown, the adhesive layer 6 is laminated on the surface of the second liquid crystal alignment fixing layer 22 opposite to the first liquid crystal alignment fixing layer 21.

[0224] The adhesive layer 6 is composed of any suitable adhesive.

[0225] Examples of adhesives include (meth)acrylic adhesives, urethane adhesives, and silicone adhesives.

[0226] Adhesives can be used alone or in combination.

[0227] Among adhesives, (meth)acrylic adhesives are preferably listed.

[0228] B-6. Stripping the liner The optical laminate 100 may further include a release liner 7. The release liner 7 is adhered to the surface of the adhesive layer 6 opposite to the second retardation film 2. Typically, the release liner 7 is temporarily adhered to the adhesive layer 6 before the optical laminate is adhered to the substrate, and is peeled off from the adhesive layer 6 when the optical laminate is adhered.

[0229] The release liner 7 comprises any suitable resin material. Examples of resin materials include polyethylene terephthalate (PET), polyethylene, and polypropylene.

[0230] Resin materials can be used alone or in combination.

[0231] In one embodiment, a release treatment layer is provided on the contact surface of the release liner 7 with the adhesive layer 6.

[0232] The release layer typically contains a release agent.

[0233] Examples of release agents include silicone-based release agents, fluorinated release agents, and long-chain alkyl acrylate release agents. Silicone-based release agents are preferred, and addition-type silicones containing vinyl groups are even more preferred.

[0234] Release agents can be used alone or in combination.

[0235] The thickness of the release layer is, for example, 50nm~400nm.

[0236] B-7. Other optical films In addition to the first phase difference film 1, the polarizer 3 and the second phase difference film 2, the optical laminate 100 may also have other optical films.

[0237] Other optical films include, for example, protective films, ultraviolet light transmission suppression films, and infrared light transmission suppression films. Other optical films can have a single-layer structure containing them individually, or they can have a stacked structure in which two or more of them are stacked.

[0238] Other optical films, for example, are adhered to the surface of the first phase difference film 1 on the side opposite to the polarizer 3 via any suitable adhesive layer or bonding agent layer.

[0239] C. Manufacturing method of optical laminates Next, a method for manufacturing an optical laminate 100 according to one embodiment will be described.

[0240] In one embodiment, the method for manufacturing an optical laminate includes a step of bonding a first retardation film 1 to a polarizer 3 (a first bonding step) and a step of bonding the polarizer 3 to a second retardation film 2 (a second bonding step). In one embodiment, the method for manufacturing an optical laminate sequentially includes a first bonding step and a second bonding step.

[0241] C-1. First bonding process In one embodiment, firstly, the first phase difference film 1 and the polarizer 3 described above are prepared. The first phase difference film 1 and the polarizer 3 are preferably elongated strips.

[0242] Furthermore, when the first retardation film 1 includes a liquid crystal alignment fixing layer, a liquid crystal alignment fixing layer is prepared to be supported on a coating substrate. Furthermore, the polarizer 3 is typically prepared to be supported on a resin substrate.

[0243] Next, the first phase difference film 1 is bonded to the polarizer 3 using any appropriate means.

[0244] In one embodiment, the first phase difference film 1 is bonded to the polarizer 3 using roll-to-roll bonding.

[0245] More specifically, the adhesive is applied to the surface of the first phase difference film 1 and / or the surface of the polarizer 3 by any suitable method.

[0246] Examples of coating methods for adhesives include dip coating, curtain coating, spray coating, bar coating, rod coating, roller coating, mold coating, and gravure coating, with gravure coating being a preferred method.

[0247] Next, the first phase difference film 1 and the polarizer 3 are overlapped in a manner that sandwiches an adhesive coating. Then, the adhesive is cured using an appropriate method corresponding to the adhesive.

[0248] For example, in the case where the adhesive contains a water-based adhesive, the coating of the adhesive is heated to dry it.

[0249] 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 evaporates, and the curing components contained in the coating cure. Thus, a first adhesive layer 41 containing a water-based adhesive is formed, and the first phase difference film 1 and the polarizer 3 are bonded together through the adhesive layer 41.

[0250] Furthermore, if the first phase difference film 1 includes a liquid crystal alignment fixing layer, the coating substrate can be peeled off from the liquid crystal alignment fixing layer as needed. Similarly, if the polarizer 3 is supported on a resin substrate, the resin substrate can be peeled off from the polarizer 3 as needed.

[0251] Through the above operations, an intermediate laminate with a stacked structure of a first phase difference film 1 / first adhesive layer 41 / polarizer 3 is modulated.

[0252] C-2. Second bonding process In addition, the second optical film 2 described above is prepared. The second phase difference film 2 is preferably elongated.

[0253] Next, the intermediate laminate prepared in the first bonding process is bonded to the second phase difference film 2 using any appropriate means.

[0254] In one embodiment, the intermediate laminate is bonded to the second optical film 2 by roller-to-roll bonding.

[0255] More specifically, the adhesive is applied to the surface of the polarizer 3 and / or the surface of the polarizer 3 in the intermediate laminate using any suitable method. For example, the same application method as the first bonding step described above can be used as an adhesive application method.

[0256] Next, the intermediate laminate and the second phase difference film 2 are overlapped in such a way that they are coated with adhesive. Then, the adhesive is cured using an appropriate method corresponding to the adhesive.

[0257] For example, when the adhesive contains 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 cures. Thus, a second adhesive layer 51 containing the cured water-based adhesive is formed, and the polarizer 3 and the second optical film 2 are bonded together through the second adhesive layer 51.

[0258] Through the above operations, an optical laminate 100 with a stacked structure of a first optical film 1 / first adhesive layer 41 / polarizer 3 / second adhesive layer 51 / second phase difference film 2 is modulated.

[0259] Then, as needed, the adhesive described above can be applied to the surface of the second phase difference film 2 on the side opposite to the polarizer 3 by any appropriate method to form an adhesive layer 6.

[0260] D. Image display device The optical laminates described in items A through 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, with organic EL displays being a preferred example.

[0261] The image display device according to an embodiment of the present invention includes an image display panel and the optical laminate 100 described above.

[0262] An image display panel typically includes image display units.

[0263] An optical laminate 100 is disposed on the visible side of an image display panel. The optical laminate 100 is typically bonded to the image display panel via an adhesive layer 6. In the image display device, a first retardation film 1 is located opposite the polarizer 3 on the visible side, i.e., the opposite side of the image display panel, and a second retardation film 2 is located between the polarizer 3 and the image display panel.

[0264] The optical stack 100 has any suitable shape corresponding to the image display device to which it is applied. The size of the optical stack 100 can be adjusted arbitrarily and appropriately.

[0265] In such an image display device, the first retardation film of the optical stack has the aforementioned in-plane phase differences Re(450) and Re(450) / Re(550), thus providing excellent visual recognition even when viewed through a polarizing element (typically polarized sunglasses). Furthermore, since the optical stack 100 is made thin, miniaturization of the image display device is possible.

[0266] Example The present invention will now be specifically described through examples, but the present invention is not limited to these examples. Furthermore, the methods for measuring each characteristic are described below.

[0267] (1) Measurement of phase difference The phase difference of the phase difference film (liquid crystal alignment fixing layer) used in the examples and comparative examples was automatically measured using an Axoscan (manufactured by Axometrics). The measurement wavelength was 450 nm or 550 nm, and the measurement temperature was 25 °C. The results are shown in Tables 1 and 2.

[0268] (2) Determination of adhesive layer thickness Using a Hitachi HT7820 instrument, the cross-sections of the optical laminates obtained in the examples and comparative examples were observed by transmission electron microscopy (TEM) via cryo-ultrath sectioning with heavy metal staining. The accelerating voltage during the measurements was set to 100 kV.

[0269] Therefore, the thickness of the adhesive layer (adhesive layer) in the optical laminate was measured. The results are shown in Tables 1 and 2.

[0270] (3) Sunglasses evaluation (visual recognition) The 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 adhered to the organic EL panel using an adhesive layer to create test samples.

[0271] Next, a white image was displayed on the organic EL panel, and the coloration of the image when viewed through polarized sunglasses was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0272] 〇 (Excellent): No obvious coloration was observed.

[0273] △(Good): Slight staining was observed.

[0274] × (Poor): Obvious staining was observed.

[0275] (4) Evaluation of Interference Inequality The organic EL display device (Samsung Galaxy A41) was disassembled, and the glass cover and polarizer 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 using an adhesive layer to create a sample.

[0276] Next, the obtained sample was placed under a fluorescent lamp, and the organic EL panel was set to off-light state. The sample was then visually observed, and the interference inhomogeneity was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0277] 〇 (Excellent): No interference inhomogeneity was observed.

[0278] △(Pass): Uneven interference is observed within the practically permissible range.

[0279] (5) Comprehensive evaluation For the optical laminates obtained in the embodiments and comparative examples, a comprehensive evaluation was conducted based on the following criteria, taking into account the above-mentioned evaluation of sunglasses, the above-mentioned evaluation of interference non-uniformity, and thickness. The results are shown in Tables 1 and 2.

[0280] Level 1: Sunglasses are rated as zero, interference inhomogeneity is rated as zero, and thickness is less than 35μm.

[0281] Level 2: Sunglasses are rated △, interference non-uniformity is rated 0, and thickness is less than 35μm.

[0282] Level 3: Sunglasses are rated as 0, interference inhomogeneity is rated as △, and thickness is below 35μm.

[0283] Level 4: Sunglasses are rated △, interference inhomogeneity is rated △, and thickness is less than 35μm.

[0284] Level 5: Sunglasses are rated ×, interference inhomogeneity is rated △, and thickness is less than 35μm.

[0285] Level 6: Thickness exceeds 35μm.

[0286] <Adhesive Preparation> <<Modulation Example 1>> An aqueous solution of silane coupling agent was prepared by adding an amino-based silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Industry Co., Ltd., product name "KBM-603") and an epoxy-based silane coupling agent (3-epoxypropoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Industry Co., Ltd., product name "KBM-403") to water.

[0287] In the aqueous solution of silane coupling agent, the mass ratio of amino-based silane coupling agent to epoxy-based silane coupling agent is 1:1 (molar ratio 51.5:48.5), and the total concentration of amino-based silane coupling agent and epoxy-based silane coupling agent is 1.0 by mass.

[0288] Then, 0.2 parts by mass of surfactant (manufactured by Nissin Chemical Co., Ltd., trade name "EXP4200") were added to 100 parts by mass of the aqueous solution of silane coupling agent to prepare a water-based adhesive.

[0289] <<Modulation Example 2>> The following ingredients were prepared: 25 parts by weight of acrylamide morpholine (trade name "ACMO", manufactured by KJ Chemicals); 10 parts by weight of ε-caprolactone-modified 2-hydroxyethyl acrylate (trade name "PLACEL FA1DDM", manufactured by Daicel Chemicals); 10 parts by weight of lauryl acrylate (trade name "LIGHT ACRYLATE LA", manufactured by Kyoeisha); 20 parts by weight of isostearyl acrylate (trade name "ISTA", manufactured by Osaka Organic Chemical Industry Co., Ltd.); 15 parts by weight of 1,9-nonanediol diacrylate (trade name "LIGHTACRYLATE 1.9ND-A", manufactured by Kyoeisha Chemicals); 15 parts by weight of acrylic oligomer (trade name "ARUFON UP-1190", manufactured by Toa Synthetic Co., Ltd.); and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad 819", manufactured by IGM Resins). 1 part by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Omnirad 184", manufactured by IGM Resins BV) and 2 parts by weight of diethylthioxanone (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) were stirred at 50°C for 1 hour to prepare a UV-curable adhesive.

[0290] <Modulation of the phase retardation film> <<Modulation Example 3>> A photopolymerizable liquid crystal compound (Paliocolor LC242, manufactured by BASF, chemical formula below) that displays a nematic liquid crystal phase was dissolved in cyclopentanone to prepare a solution with a solid content concentration of 30% by mass.

[0291] [Chemical Formula 1] A surfactant (BYK-Chemie, "BYK-361N") and a photopolymerization initiator (IGM Resins, "Omnirad 907") were added to the solution to prepare a liquid crystal coating solution. The amount of surfactant added was 0.01 parts by mass relative to 100 parts by mass of the photopolymerizable liquid crystal compound. Additionally, the amount of the polymerization initiator added was 3 parts by mass relative to 100 parts by mass of the photopolymerizable liquid crystal compound.

[0292] Additionally, as the coating substrate, an alignment treatment was performed by rubbing the surface of a strip-shaped polyethylene terephthalate (PET) film (38 μm thick) with a rubbing cloth. The orientation treatment direction was set to 45° relative to the absorption axis direction of the polarizer when viewed from the visible side when attached to the polarizer.

[0293] Next, the liquid crystal coating solution was applied to the oriented surface using a bar coater, and then heated and dried at 100°C for 3 minutes to orient the liquid crystal compound. After cooling the thus formed liquid crystal layer to room temperature (25°C), it was irradiated under a nitrogen atmosphere with a cumulative light intensity of 400 mJ / cm². 2 Ultraviolet light is used to cure the liquid crystal layer. This forms a liquid crystal alignment fixing layer on the coating substrate. The liquid crystal alignment fixing layer is elongated and has a thickness of 1 μm.

[0294] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(450) is 90 nm and the in-plane phase difference Re(550) is 83 nm.

[0295] <<Modulation Example 4>> Except for slightly adjusting the coating thickness using a bar coater, a liquid crystal alignment fixing layer is formed on the coating substrate in the same manner as in Modulation Example 3.

[0296] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(450) is 100 nm and the in-plane phase difference Re(550) is 93 nm.

[0297] <<Modulation Example 5>> Except for slightly adjusting the coating thickness using a bar coater, a liquid crystal alignment fixing layer is formed on the coating substrate in the same manner as in Modulation Example 3.

[0298] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(450) is 110 nm and the in-plane phase difference Re(550) is 102 nm.

[0299] <<Modulation Example 6>> Except for slightly adjusting the coating thickness using a bar coater, a liquid crystal alignment fixing layer is formed on the coating substrate in the same manner as in Modulation Example 3.

[0300] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(450) is 120 nm and the in-plane phase difference Re(550) is 111 nm.

[0301] <<Modulation Example 7>> Except for slightly adjusting the coating thickness using a bar coater, a liquid crystal alignment fixing layer is formed on the coating substrate in the same manner as in Modulation Example 3.

[0302] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(450) is 130 nm and the in-plane phase difference Re(550) is 120 nm.

[0303] <<Modulation Example 8>> Except for slightly adjusting the coating thickness using a bar coater, a liquid crystal alignment fixing layer is formed on the coating substrate in the same manner as in Modulation Example 3.

[0304] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(450) is 140 nm and the in-plane phase difference Re(550) is 130 nm.

[0305] <<Modulation Example 9>> The orientation process was changed to a 15° angle relative to the absorption axis of the polarizer when viewed from the visible side, and the coating thickness was also changed. However, similar to Modulation Example 3, a liquid crystal alignment fixing layer was formed on the coating substrate. The thickness of the liquid crystal alignment fixing layer was 2 μm.

[0306] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(550) is 240 nm.

[0307] <<Modulation Example 10>> The orientation process was changed to a 75° angle relative to the absorption axis of the polarizer when viewed from the visible side. Otherwise, a liquid crystal alignment fixing layer was formed on the coating substrate, similar to Modulation Example 7. The thickness of the liquid crystal alignment fixing layer was 1 μm.

[0308] The liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. In the liquid crystal alignment fixing layer, the in-plane phase difference Re(550) is 120 nm.

[0309] <<Modulation Example 11>> As the first phase retardation film, a stretched film containing COP (manufactured by Zeon Corporation, Japan, ZD12) is prepared. The stretched film has a refractive index of nx>ny>nz. The angle between the length direction of the stretched film and the slow axis direction is 45°. In the stretched film, the in-plane phase retardation Re(450) is 100 nm, and the in-plane phase retardation Re(550) is 100 nm.

[0310] <<Modulation Example 12>> As the first phase retardation film, a stretched film containing COP (manufactured by Zeon Corporation, Japan, ZD12) is prepared. The stretched film has a refractive index of nx>ny>nz. The angle between the length direction of the stretched film and the slow axis direction is 45°. In the stretched film, the in-plane phase retardation Re(450) is 140 nm, and the in-plane phase retardation Re(550) is 140 nm.

[0311] <Modulation of the second phase difference film> <<Modulation Example 13>> The liquid crystal alignment fixing layer obtained in Modulation Example 9 is used as the first liquid crystal alignment fixing layer, and the liquid crystal alignment fixing layer obtained in Modulation Example 10 is used as the second liquid crystal alignment fixing layer.

[0312] A corona treatment machine was used to treat a density of 50 W·min / m³. 2 The surfaces of the first liquid crystal alignment fixing layer obtained in Modulation Example 9 and the second liquid crystal alignment fixing layer obtained in Modulation Example 10 were subjected to corona treatment.

[0313] Next, using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd., cell shape: honeycomb, gravure roller line count: 1000 lines / inch, rotation speed 130% / pair of line speed), the aqueous adhesive obtained in Modulation Example 1 was coated on the corona-treated surface of the first liquid crystal alignment fixing layer to form a coating film on the first liquid crystal alignment fixing layer.

[0314] In addition, similarly to the above, the aqueous adhesive obtained in Modulation Example 1 was coated on the corona-treated surface of the second liquid crystal alignment fixing layer.

[0315] Then, a bonding roller machine is used to bond the first liquid crystal alignment layer and the second liquid crystal alignment layer. More specifically, the first liquid crystal alignment layer and the second liquid crystal alignment layer are passed through the bonding roller machine such that the coatings on the first liquid crystal alignment layer and the coatings on the second liquid crystal alignment layer are in contact with each other. The linear speed of each of the first and second liquid crystal alignment layers is 15 m / min. At this time, the angle between the slow axis direction of the first liquid crystal alignment layer and the slow axis direction of the second liquid crystal alignment layer is 60°.

[0316] Then, heat and dry the coating at 60°C for 10 minutes to cure the water-based adhesive and form an adhesive layer.

[0317] Next, the coated substrate is peeled off from the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer, respectively.

[0318] Thus, a second phase reversal film with a stacked structure of a first liquid crystal alignment fixing layer / adhesive layer / second liquid crystal alignment fixing layer is modulated.

[0319] <Modulation of the polarizer> <<Modulation Example 14>> As a thermoplastic resin substrate, a strip-shaped amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) with a Tg of about 75 °C was used, and one side of the film was subjected to corona treatment.

[0320] A PVA aqueous solution (coating solution) was prepared by adding 13 parts by mass of potassium iodide to 100 parts by mass of a PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a 9:1 ratio.

[0321] The above-mentioned PVA aqueous solution was coated on the corona-treated surface of a thermoplastic resin substrate and dried at 60°C, thereby forming a PVA-based resin layer with a thickness of 13 μm on the thermoplastic resin substrate.

[0322] The resulting laminate was stretched uniaxially in the longitudinal direction (length direction) to 2.4 times its original size in an oven at 130°C (air-assisted stretching treatment).

[0323] Next, the laminate was immersed in an insoluble bath (an aqueous solution of boric acid prepared by mixing 4 parts by mass with 100 parts by mass of water) at a liquid temperature of 40°C for 30 seconds (insoluble treatment).

[0324] Next, the laminate was immersed in a staining bath at 30°C (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a 1:7 mass ratio relative to 100 parts by mass of water) for 60 seconds while adjusting the concentration so that the final polarizer's monomer transmittance (Ts) was the desired value (staining treatment).

[0325] Next, the laminate was immersed in a crosslinking bath at 40°C (an aqueous solution of boric acid prepared by mixing 100 parts by mass of water with 3 parts by mass of potassium iodide and 5 parts by mass of boric acid) for 30 seconds (crosslinking treatment).

[0326] Then, the laminate is 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, while being uniaxially stretched (underwater stretching treatment) in the longitudinal direction (length direction) between rollers with different circumferential speeds, with a total stretching ratio of 5.5 times.

[0327] Then, the laminate was immersed in a cleaning bath at 20°C (an aqueous solution of 100 parts by mass of water and 4 parts by mass of potassium iodide) (cleaning treatment).

[0328] Then, the laminate is dried in an oven at approximately 90°C while being brought into contact with heated rollers made of SUS at a surface temperature of approximately 75°C (drying shrinkage treatment).

[0329] In this way, a polarizer is formed on a thermoplastic resin substrate. The thickness of the polarizer is approximately 5.0 μm.

[0330] [Example 1] The liquid crystal alignment fixing layer obtained in Modulation Example 4 was used as the first phase difference film and was adhered to the polarizer obtained in Modulation Example 14 using the ultraviolet-curable adhesive obtained in Modulation Example 2.

[0331] More specifically, on the surface of the polarizer opposite to the thermoplastic resin substrate, the UV-curable adhesive obtained in Preparation Example 2 was coated using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd., cell shape: honeycomb, gravure roller line count: 1000 lines / inch, speed 130% / pair line speed) to form a coating film on the polarizer. Additionally, the UV-curable adhesive obtained in Preparation Example 2 was coated on the surface of the first phase difference film in the same manner as described above.

[0332] Then, the polarizer and the first phase difference film are bonded together at an angle of 45° between the absorption axis of the polarizer and the slow axis of the first phase difference film.

[0333] Next, the coating containing the UV-curable adhesive is irradiated with ultraviolet light to cure the UV-curable adhesive, forming a first adhesive layer as the first adhesive layer.

[0334] Then, the coated substrate is peeled off from the first phase difference film (liquid crystal alignment fixing layer), and the thermoplastic resin substrate is peeled off from the polarizer.

[0335] Thus, an intermediate laminate with a stacked structure of a first phase difference film (liquid crystal alignment fixing layer) / first adhesive layer / polarizer is manufactured.

[0336] Next, the intermediate laminate, the second phase difference film obtained in modulation example 13, and the aqueous adhesive obtained in modulation example 1 are bonded together.

[0337] More specifically, using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd., cell shape: honeycomb, gravure roller line count: 1000 lines / inch, rotation speed 130% / pair of linear speed), the aqueous adhesive obtained in Modulation Example 1 is coated on the surface of the polarizer opposite to the first phase difference film, forming a coating film on the polarizer. Similarly, the aqueous adhesive obtained in Modulation Example 1 is coated on the surface of the first liquid crystal alignment fixing layer opposite to the second liquid crystal alignment fixing layer, as described above.

[0338] Then, the polarizer is bonded to the second phase difference film in such a way that the angle between the absorption axis direction of the polarizer and the slow axis direction of the first liquid crystal alignment fixing layer is 15° and the angle between the absorption axis direction of the polarizer and the slow axis direction of the second liquid crystal alignment fixing layer is 75°.

[0339] Next, the coating is heated and dried at 60°C for 10 minutes to cure the water-based adhesive, forming a second adhesive layer as the second adhesive layer.

[0340] Then, a (meth)acrylic adhesive is applied to the surface of the second liquid crystal alignment fixing layer opposite to the second adhesive layer to form an adhesive layer. The thickness of the adhesive layer is 15 μm.

[0341] Through the above operations, an optical laminate with a stacked structure of a first phase retardation film (liquid crystal alignment fixing layer) / first adhesive layer / polarizer / second adhesive layer / second phase retardation film / adhesive layer is manufactured.

[0342] The thickness of the optical laminate is shown in Table 1.

[0343] [Example 2] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the liquid crystal alignment fixing layer obtained in Modulation Example 5 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0344] [Example 3] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the liquid crystal alignment fixing layer obtained in Modulation Example 6 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0345] [Example 4] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the liquid crystal alignment fixing layer obtained in Modulation Example 7 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0346] [Examples 5-8] The UV-curable adhesive constituting the first adhesive layer was changed to the water-based adhesive obtained in Preparation Example 1. The coating containing the water-based adhesive was heated and dried at 60°C for 10 minutes to cure the water-based adhesive. Otherwise, the optical laminate was manufactured in the same manner as in Examples 1 to 4.

[0347] [Comparative Example 1] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the stretching film obtained in Modulation Example 11 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0348] [Comparative Example 2] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the stretching film obtained in Modulation Example 12 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0349] [Comparative Example 3] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the liquid crystal alignment fixing layer obtained in Modulation Example 3 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0350] [Comparative Example 4] Instead of the liquid crystal alignment fixing layer obtained in Modulation Example 4, the liquid crystal alignment fixing layer obtained in Modulation Example 8 is used as the first phase difference film. Otherwise, the optical laminate is manufactured in the same manner as in Example 1.

[0351] [Table 1] [Table 2] [evaluate] As shown in Tables 1 and 2, the first phase retardation film contains an orientation fixing layer of liquid crystal compound. The in-plane phase difference Re(450) of the first phase retardation film is greater than 100nm and less than 130nm. When Re(450) / Re(550) in the first phase retardation film exceeds 1, the optical laminate can be made thinner. When the optical laminate is applied to an image display device, the visual recognition of the polarized sunglasses can be improved.

[0352] Industrial availability The optical laminate manufactured by means of embodiments of the present invention can be suitably used in image display devices (such as liquid crystal display devices and organic EL display devices).

Claims

1. An optical laminate, comprising, in sequence, a first retardation film, a polarizer, and a second retardation film. The first phase retardation film includes an alignment fixing layer of a liquid crystal compound. The in-plane phase difference Re(450) of the first phase difference film is greater than 100 nm and less than 130 nm. The Re(450) / Re(550) of 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 dimension from the surface of the first retardation film opposite to the polarizer to the surface of the second retardation 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 dimension from the surface of the first retardation film opposite to the polarizer to the surface of the second retardation 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 relative to the second retardation film.

5. The optical laminate according to claim 4, wherein, In the stacking direction of the optical laminate, the dimension from the surface of the first retardation film opposite to the polarizer to the surface of the adhesive layer opposite to the second retardation film is less than 35 μm.

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

7. The optical laminate according to claim 1, wherein, The Re(450) / Re(550) of the first phase difference film is greater than 1.05 and less than 1.

5.

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

11. The optical laminate according to claim 1, wherein, The second phase retardation film includes an alignment fixing layer of the liquid crystal compound. The Re(450) / Re(550) of the second phase difference film is less than 1.

12. The optical laminate according to claim 1, wherein, The thickness of the first phase difference film is greater than 0.5 μm and less than 2.0 μm.

13. The optical laminate according to claim 1, further comprising a first adhesive layer for bonding the first retardation film to the polarizer. 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 optical laminate according to claim 13, further comprising a second adhesive layer for bonding the polarizer to the second retardation film. 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 contains an amino-based silane coupling agent.

19. The optical laminate according to claim 17, wherein, The organosilicon compound contains an epoxy silane coupling agent.

20. An image display device comprising the 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 disposed on the visible side relative to the polarizer.

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