Optical laminate and image display device

Abstract

An optical laminate is provided that enables an image display device with excellent visual confirmability via optical components having polarizing effects, and that suppresses the generation and / or propagation of cracks. An embodiment of the optical laminate of the present invention sequentially comprises a first retardation film, a polarizer, and a second retardation film. The in-plane phase difference Re(550) of the first retardation film is 80 nm or more and 160 nm or less. The average linear expansion coefficient of the first retardation film at -40°C to 85°C is 4.5 × 10⁻⁶. ‑5 / ℃ below.

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 (e.g., organic EL displays and inorganic EL displays), have become rapidly popular. If an observer uses polarized sunglasses to view such an image display device, depending on the observer's viewing angle, the transmission axis of the polarized sunglasses may sometimes be orthogonal to the transmission axis of the polarizer in the image display device. In this case, the image on the display device may appear black, and the displayed image may not be visually verifiable.

[0003] To address this problem, an optical laminate comprising a phase difference film and a polarizer is proposed to be disposed on the visual confirmation 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 However, regarding the image display device with an optical laminate described in Patent Document 1, there is a problem that cracks may occur in the optical laminate depending on the usage environment.

[0006] The main objective of this invention is to provide an image display device that enables excellent visual confirmation via optical components with polarizing properties, and an optical laminate that can suppress the generation and / or propagation of cracks.

[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 in-plane phase difference Re(550) of the first retardation film is 80 nm or more and 160 nm or less. The average linear expansion coefficient of the first retardation film at -40°C to 85°C is 4.5 × 10⁻⁶. -5 / ℃ below.

[0008] [2] According to the optical laminate described in [1] above, the angle between the slow axis direction of the first phase difference film and the absorption axis direction of the polarizer can also be 35° to 55°.

[0009] [3] The optical laminate described in [1] or [2] above may also have a through hole. The through hole extends through the optical laminate along the lamination direction.

[0010] [4] According to the optical laminate described in [3] above, the diameter of the through hole may also be less than 6 mm.

[0011] [5] The optical laminate according to any one of [1] to [4] above, wherein the first phase difference film may also contain a cellulose resin.

[0012] [6] In any one of the above [1] to [5], the distance from the surface of the first phase difference film side of the polarizer to the surface of the second phase difference film opposite to the polarizer in the stacking direction of the optical laminate may be less than the thickness of the first phase difference film.

[0013] [7] In any one of the above [1] to [6], the distance from the surface of the first phase difference film side of the polarizer to the surface of the second phase difference film opposite to the polarizer in the stacking direction of the optical laminate can also be 5 μm to 15 μm.

[0014] [8] In the optical laminate according to any one of [1] to [7] above, the thickness of the first retardation film may also exceed 20 μm. In addition, the thickness of the second retardation film may be less than 10 μm.

[0015] [9] The optical laminate according to any one of [1] to [8] above, wherein the second phase difference film may also be attached to the polarizer via an adhesive layer.

[0016]

[10] The optical laminate according to any one of [1] to [9] above, wherein the second phase difference film can also function as a λ / 4 plate.

[0017]

[11] The optical laminate according to any one of [1] to

[10] above, wherein the second phase difference film may also include an orientation fixing layer of liquid crystal compound.

[0018]

[12] Another aspect of the image display device of the present invention includes the optical laminate described in any one of [1] to

[11] above. In this image display device, the first phase difference film may also be disposed on the visual confirmation side relative to the polarizer.

[0019] Invention Effects According to embodiments of the present invention, an image display device with excellent visual confirmability can be realized through an optical component having a polarizing effect, and the generation and / or propagation of cracks can be suppressed. Attached Figure Description

[0020] Figure 1 This is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0021] Figure 2 This is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention.

[0022] Figure 3 yes Figure 1 A schematic plan view of the optical laminate.

[0023] Figure 4 yes Figure 1 A schematic cross-sectional view of the first phase difference film of the optical laminate.

[0024] Figure 5 yes Figure 1 A schematic cross-sectional view of the second phase difference film in the optical laminate.

[0025] Explanation of symbols 1. First phase difference film 11 Substrate 12 First liquid crystal alignment fixing layer 2. Second phase difference film 22 Second liquid crystal alignment fixing layer 23 Third liquid crystal alignment fixing layer 3. Polarizer 4. Protective layer 5 Adhesive layer 100 optical laminates Detailed Implementation

[0026] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments. In addition, in order to make the description clearer, the width, thickness, shape, etc. of each part are sometimes schematically shown in the accompanying drawings compared with the embodiments, but these are just examples and do not limit the interpretation of the present invention.

[0027] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows.

[0028] (1) Refractive index (nx, ny, nz) “nx” is the refractive index in the direction where the refractive index in the plane becomes the largest (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.

[0029] (2) In-plane phase difference (Re) “Re(λ)” is the in-plane phase difference measured at 23°C using light with a wavelength of λ nm. For example, “Re(550)” is the in-plane phase difference measured at 23°C using light with a wavelength of 550 nm. When the thickness of the layer (film) is set to d (nm), Re(λ) is obtained by the formula: Re(λ) = (nx - ny) × d.

[0030] (3) Phase difference in the thickness direction (Rth) “Rth(λ)” is the phase difference in the thickness direction measured by light with a wavelength of λ nm at 23°C. For example, “Rth(550)” is the phase difference in the thickness direction measured by light with a wavelength of 550 nm at 23°C. When the thickness of the layer (film) is set to d (nm), Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d.

[0031] (4) Nz coefficient The Nz coefficient is obtained by Nz=Rth / Re.

[0032] (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°.

[0033] 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.

[0034] 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.

[0035] The in-plane phase difference Re(550) of the first phase retardation film 1 is greater than 80 nm and less than 160 nm. The first phase retardation film 1 typically functions as a λ / 4 plate.

[0036] The average linear expansion rate of the first phase difference film 1 at temperatures ranging from -40℃ to 85℃ is 4.5 × 10⁻⁶. -5 / ℃ below.

[0037] The inventors have studied the miniaturization and / or thinning of image display devices, and as a result, have directly addressed the new challenge of cracks of a size that were previously hidden by the bezel of image display devices reaching the display screen of the image display device.

[0038] Therefore, the inventors conducted in-depth research on the generation and propagation of cracks in optical laminates and found that if the average linear expansion rate (hereinafter, sometimes referred to as CTE) of the phase difference film in the optical laminate is adjusted to a specified range, the generation and / or propagation of cracks in the optical laminate can be suppressed.

[0039] More specifically, the average linear expansion rate of the first phase difference film at -40℃ to 85℃ is 4.5 × 10⁻⁶. -5 The temperature is below 85°C, so even when the image display device with the optical laminate is used in various environments (especially in the temperature range of -40°C to 85°C), the generation and / or propagation of cracks in the optical laminate can be significantly suppressed. Therefore, even when miniaturizing the image display device, cracks generated in the optical laminate can be prevented from reaching the display screen of the image display device.

[0040] Furthermore, since the in-plane phase difference Re(550) of the first phase difference film is 80 nm or more and 160 nm or less, the visual confirmation of the image display device via the optical component with polarizing effect (hereinafter, sometimes referred to as the polarizing component) can also be sufficiently ensured.

[0041] Therefore, if an optical laminate of one embodiment is applied to an image display device, an image display device with excellent visual verifiability via a polarizing member can be realized, and the generation and / or propagation of cracks in the optical laminate can be suppressed regardless of the usage environment of the image display device.

[0042] The first phase retardation film 1 is located on the opposite side of the polarizer 3 as the second phase retardation film 2. The first phase retardation film 1 typically functions as a protective layer for the polarizer 3.

[0043] In one embodiment, the first phase difference film 1 is positioned on the visual confirmation side relative to the polarizer 3 when the optical laminate 100 is applied in an image display device.

[0044] The CTE of the first phase retardation film 1 is preferably 4.2 × 10⁻⁶. -5 Below / ℃, more preferably 4.0×10 -5 Below / ℃, more preferably 3.8×10 -5 / ℃ below.

[0045] If the first phase retardation film has such a CTE, the generation and / or propagation of cracks in the optical laminate can be stably suppressed.

[0046] On the other hand, the CTE of the first phase retardation film 1 is, for example, 1.0 × 10⁻⁶. -5 / ℃ or above, and for example, 2.0×10 -5 / ℃ or above, and for example, 3.0×10-5 / ℃ or above.

[0047] It should be noted that the mean linear expansion coefficient (CTE) is measured, for example, according to JIS K 7197. More specifically, the mean linear expansion coefficient (CTE) is calculated using the maximum and minimum values ​​of the dimension in a specified direction during a cycle of (1) cooling from 25°C to -40°C, (2) heating from -40°C to 85°C, (3) cooling from 85°C to -40°C, (4) heating from -40°C to 85°C, (5) cooling from 85°C to -40°C, (6) heating from -40°C to 85°C, and (7) cooling from 85°C to 25°C.

[0048] It should be noted that in the case of films where molecules are oriented or stretched, such as retardation films or polarizers, the average linear expansion rate sometimes differs depending on the in-plane orientation. In such cases, refer to the value of the orientation where the average linear expansion rate is greatest. Most stretched films have the smallest stretching orientation and the largest orientation orthogonal to the stretching direction. However, by adjusting the stretching conditions, or more specifically, adjusting the heat setting conditions or easing conditions, the in-plane orientation difference can be minimized.

[0049] The refractive index of the first phase retardation film 1 exhibits, for example, a relationship of nx > ny ≥ nz, preferably a relationship of nx > ny > nz. It should be noted that "ny = nz" includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Therefore, without impairing the effects of the invention, it may sometimes be expressed as ny > nz or ny <nz。

[0050] The in-plane phase difference Re (550) of the first phase difference film 1 is preferably 145 nm or less, more preferably 130 nm or less, even more preferably 120 nm or less, and especially preferably 110 nm or less.

[0051] If the Re(550) of the first phase difference film is below such an upper limit, then the desired coloring can be stably displayed in an image display device equipped with an optical stack.

[0052] On the other hand, the in-plane phase difference Re (550) of the first phase difference film 1 is preferably 90 nm or more.

[0053] If the Re(550) of the first phase difference film is above such a lower limit, then in an image display device equipped with an optical laminate, the visual confirmation via the polarizing member can be stably improved.

[0054] The phase difference Rth (550) in the thickness direction of the first phase difference film 1 is, for example, 90 nm to 200 nm, preferably 100 nm to 150 nm.

[0055] The Nz coefficient of the first phase difference film 1 is, for example, 0.9 to 1.5, preferably 1.1 to 1.4.

[0056] The first phase difference film 1 can exhibit inverse wavelength dispersion characteristics where in-plane birefringence increases in proportion to the wavelength of the measurement light, positive wavelength dispersion characteristics where in-plane birefringence decreases in proportion to the wavelength of the measurement light, or flat wavelength dispersion characteristics where in-plane birefringence hardly changes according to the wavelength of the measurement light.

[0057] The thickness of the first phase difference film 1 is, for example, 15 μm or more, preferably more than 20 μm, more preferably 23 μm or more, and even more preferably 28 μm or more.

[0058] If the thickness of the first phase difference film is above such a lower limit, then the first phase difference film can stably function as a protective layer for the polarizer.

[0059] On the other hand, the thickness of the first phase difference film 1 is, for example, 80 μm or less, preferably 60 μm or less, and more preferably 40 μm or less.

[0060] If the thickness of the first phase difference film is below such an upper limit, then the optical laminate can be made thinner.

[0061] 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° to 60°, preferably 35° to 55°, more preferably 40° to 50°, and even more preferably 43° to 47°.

[0062] With this configuration, visual confirmation via the polarizing member can be improved more stably in image display devices equipped with optical laminates.

[0063] The polarizer 3 is located between the first phase difference film 1 and the second phase difference film 2 in the stacking direction (hereinafter sometimes simply referred to as the stacking direction) of the optical stack 100.

[0064] The polarizer 3 has a first surface 3a on the side of the first phase difference film 1 and a second surface 3b on the side of the second phase difference film 2 in the stacking direction. The first surface 3a and the second surface 3b are separated from each other in the stacking direction.

[0065] The average linear expansion coefficient (CTE) of polarizer 3 at temperatures ranging from -40℃ to 85℃ is, for example, 20 × 10⁻⁶. -5 Below / ℃, preferably 10×10 -5 / ℃ or below. On the other hand, the CTE of polarizer 3 is, for example, 0.1 × 10 -5 / ℃ or above, and for example, 0.5×10 -5 / ℃ or above.

[0066] The absolute value of the difference between the CTE of the first phase retardation film 1 and the CTE of the polarizer 3 is, for example, 5 × 10⁻⁶. -5 Below / ℃, preferably 4×10 -5 / ℃ below.

[0067] If the polarizer's CTE is within such a range, the initiation and / or propagation of cracks in the optical laminate can be stably suppressed.

[0068] The polarizer 3 is, in a sense, thinner than the first phase difference film 1.

[0069] The thickness of the polarizer 3 is, for example, 1 μm to 80 μm, preferably 1 μm to 15 μm, more preferably 1 μm to 12 μm, and even more preferably 3 μm to 7 μm.

[0070] If the polarizer has such a thickness, then the thinning of optical laminates can be steadily pursued.

[0071] In the example shown, the polarizer 3 is attached to the first retardation film 1 via an adhesive layer 61. Hereinafter, the adhesive layer that holds the polarizer 3 to the first retardation film 1 will sometimes be referred to as the first adhesive layer 61.

[0072] The first adhesive layer 61 is in contact with the first surface 3a of the polarizer 3. The first adhesive layer 61 can be an adhesive layer or a bonding agent layer.

[0073] In one embodiment, the first adhesive layer 61 is an adhesive layer. In other words, the first adhesive layer 61 comprises a cured product of any suitable adhesive.

[0074] Examples of adhesives include water-based adhesives; thermosetting adhesives; moisture-curing adhesives; and ultraviolet-curing adhesives (UV adhesives), among other active energy ray-curing adhesives. Active energy ray-curing adhesives are preferred.

[0075] Adhesives can be used alone or in combination.

[0076] The thickness of the first adhesive layer 61 is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 2 μm or less. On the other hand, the lower limit of the thickness of the first adhesive layer 61 is typically 0.01 μm.

[0077] The second retardation film 2 is located on the opposite side of the first retardation film 1 relative to the polarizer 3. In one embodiment, the second retardation film 2 is disposed on the opposite side (i.e., the panel side) relative to the visual confirmation side when the optical laminate 100 is applied in the image display device.

[0078] The second phase difference film 2 has a first surface 2a on the side of the polarizer 3 and a second surface 2b on the opposite side of the polarizer 3 in the stacking direction. The first surface 2a and the second surface 2b are separated from each other in the stacking direction.

[0079] The second phase retardation film 2 can have an in-plane phase retardation or a phase retardation in the thickness direction. The second phase retardation film 2 can function as a λ / 4 plate, or as a λ / 2 plate, λ / 3 plate, λ / 5 plate, or C-Plate.

[0080] The second phase difference film 2 can be a single-layer film or a double-layer film.

[0081] The second phase difference film 2 preferably has an in-plane phase difference.

[0082] The in-plane phase difference Re(550) of the second phase retardation film 2 is, for example, 100 nm to 300 nm. The Nz coefficient of the second phase retardation film 2 is, for example, 0.9 to 1.5, preferably 0.9 to 1.3.

[0083] In one embodiment, the second retardation film 2 functions as a λ / 4 plate. If the second retardation film functions as a λ / 4 plate, excellent anti-reflective properties can be imparted to the image display device equipped with the optical stack.

[0084] When the second phase difference film 2 functions as a λ / 4 plate, the in-plane phase difference Re (550) of the second phase difference film 2 is preferably 100nm to 190nm, more preferably 110nm to 170nm, and even more preferably 130nm to 160nm.

[0085] The second phase difference film 2 with in-plane phase difference can exhibit inverse wavelength dispersion characteristics where in-plane birefringence increases in proportion to the wavelength of the measurement light, positive wavelength dispersion characteristics where in-plane birefringence decreases in proportion to the wavelength of the measurement light, or flat wavelength dispersion characteristics where in-plane birefringence hardly changes according to the wavelength of the measurement light.

[0086] The average linear expansion coefficient (CTE) of the second phase difference film 2 at temperatures ranging from -40℃ to 85℃ is, for example, 15 × 10⁻⁶. -5 Below / ℃, preferably 12×10 -5 / ℃ or below. On the other hand, the CTE of the second phase retardation film 2 is, for example, 2×10. -5 / ℃ or above, and for example, 5×10 -5 / ℃ or above.

[0087] The absolute value of the difference between the CTE of the first phase retardation film 1 and the CTE of the second phase retardation film 2 is, for example, 10 × 10. -5 Below / ℃, preferably 8×10 -5 / ℃ below.

[0088] If the CTE of the second phase retardation film is in such a range, the generation and / or propagation of cracks in the optical laminate can be suppressed more stably.

[0089] The second phase retardation film 2 is, in a sense, thinner than the first phase retardation film 1.

[0090] The thickness of the second retardation film 2 is, for example, 15 μm or less, preferably less than 10 μm, and more preferably 5 μm or less. On the other hand, the lower limit of the thickness of the second retardation film 2 is typically 1 μm.

[0091] If the second phase retardation film has such a thickness, the optical laminate can be further thinned.

[0092] In the example shown, the second retardation film 2 is attached to the polarizer 3 via an adhesive layer 62. Hereinafter, the adhesive layer that bonds the second retardation film 2 to the polarizer 3 will sometimes be referred to as the second adhesive layer 62. The second adhesive layer 62 is in contact with the second surface 3b of the polarizer 3 and the first surface 2a of the second retardation film 2, respectively.

[0093] The second adhesive layer 62 is described in the same manner as the first adhesive layer 61 described above. Therefore, a detailed description of the second adhesive layer 62 is omitted.

[0094] In one embodiment, the optical laminate 100 does not have an optical film (optical layer) thicker than the first retardation film 1. With this configuration, the optical laminate can be stably thinned.

[0095] Examples of optical films include polarizers, phase retardation films, polarizer protective films, phase retardation protective films, image display device protective films, ultraviolet light transmission suppression films, and infrared light transmission suppression films.

[0096] In the stacking direction, the distance from the first surface 3a of the polarizer 3 to the second surface 2b of the second phase difference film 2 can be greater than or less than the thickness of the first phase difference film 1.

[0097] In one embodiment, the distance from the first surface 3a of the polarizer 3 to the second surface 2b of the second retardation film 2 in the stacking direction is less than the thickness of the first retardation film 1. With this configuration, the thinning of the optical laminate can be achieved more stably.

[0098] The distance from the first surface 3a of the polarizer 3 to the second surface 2b of the second phase difference film 2 in the stacking direction is, for example, 5 μm to 25 μm, preferably 6 μm to 20 μm, and more preferably 7 μm to 15 μm.

[0099] In one embodiment, the optical laminate 100 further includes an adhesive layer 5. The adhesive layer 5 is located on the opposite side of the polarizer 3 relative to the second retardation film 2.

[0100] With this configuration, the optical laminate can be attached to any suitable substrate (typically an image display panel) of the image display device via an adhesive layer.

[0101] The optical laminate 100 may further include a release liner 7. The release liner 7 is attached to the surface of the adhesive layer 5 opposite to the second retardation film 2. Typically, the release liner 7 is temporarily attached to the adhesive layer 5 until the optical laminate is attached to the substrate, and is peeled off from the adhesive layer 5 during the attachment of the optical laminate.

[0102] exist Figure 1 In the optical laminate 100 shown, the second retardation film 2 is attached to the polarizer 3 via the second adhesive layer 62. However, the configuration of the optical laminate is not limited to this.

[0103] like Figure 2 As shown, the optical laminate 100 may further include a protective layer 4. The protective layer 4 is located between the polarizer 3 and the second retardation film 2 in the lamination direction.

[0104] Based on this configuration, the protective layer can stably protect the polarizer. On the other hand, from the perspective of thinner design, Figure 1 The optical laminate shown is 100 times the Figure 2 The optical laminate 100 shown is preferred.

[0105] In the example shown, the protective layer 4 is attached to the polarizer 3 via adhesive layer 63, and the second phase difference film 2 is attached to the protective layer 4 via adhesive layer 64. Hereinafter, the adhesive layer that bonds the polarizer 3 to the protective layer 4 will sometimes be referred to as the third adhesive layer 63, and the adhesive layer that bonds the protective layer 4 to the second phase difference film 2 will sometimes be referred to as the fourth adhesive layer 64.

[0106] The third adhesive layer 63 and the fourth adhesive layer 64 are each described in the same manner as the first adhesive layer 61 described above. Therefore, detailed descriptions of the third adhesive layer 63 and the fourth adhesive layer 64 are omitted.

[0107] like Figure 3 As shown, the optical laminate 100 has any suitable shape when viewed from the lamination direction.

[0108] The shape of the optical laminate 100 as viewed from the stacking direction can include, for example, a polygonal shape such as a rectangle, a circular shape, an elliptical shape, and other irregular shapes, with a rectangular shape being preferred. In the example shown, the optical laminate 100 has a rectangular shape when viewed from the stacking direction.

[0109] The dimensions of the optical laminate 100 can be arbitrarily and appropriately adjusted.

[0110] When the optical laminate 100 has a rectangular shape when viewed from the stacking direction, the length direction (long side direction) dimension of the optical laminate 100 is, for example, 100mm to 400mm, and the width direction (short side direction) dimension of the optical laminate 100 is typically 50mm to 300mm.

[0111] In one embodiment, the optical laminate 100 includes a shaped portion 10. The shaped portion 10 typically includes a portion that has an arc shape when viewed from the lamination direction.

[0112] In this specification, "irregularly shaped processing section" refers to a part that has been processed into a special shape that is different from the general shape (e.g., a rectangle, a chamfered corner).

[0113] Cracks tend to propagate from the periphery of the irregularly shaped processing section. However, according to one embodiment, since the CTE of the first retardation film of the optical laminate is adjusted to the range described above, the generation and / or propagation of cracks can be sufficiently suppressed even if the optical laminate has an irregularly shaped processing section.

[0114] As for irregularly shaped processing parts 10, examples include through holes, V-shaped notches, U-shaped notches, and other recesses.

[0115] The optical laminate 100 may have one type of irregular processing part or two or more types of irregular processing parts.

[0116] In the example shown, the optical laminate 100 has a through hole 10a as a shaped processing part. The through hole 10a penetrates the optical laminate 100 along the lamination direction. When viewed from the lamination direction, the through hole 10a can be disposed in the central part of the optical laminate 100, or it can be disposed at a position closer to the end than the central part.

[0117] The through-hole 10a is typically used as an effective opening for mounting a camera, sensor, physical switch, etc., within the surface of an image display device. The closer the through-hole is to the end of the optical laminate 100 compared to its center, the less likely it is to compromise the usability of the image display device. Conversely, the closer the through-hole 10a is to the center of the optical laminate 100 compared to its end, the less likely it is to compromise its usability. To improve industrial usability, it is preferable that the user can position the through-hole 10a at any location. On the other hand, the closer the through-hole 10a is to the center, the greater the stress concentration within the surface, thus increasing the likelihood of crack generation and / or propagation. To improve industrial usability, it is preferable that crack generation and / or propagation do not occur even if the through-hole 10a is positioned in the central portion. The distance between the center of the through-hole 10a and the end of the optical laminate 100 is preferably 5 mm or more, more preferably 8 mm or more, further preferably 10 mm or more, and particularly preferably 12 mm or more. The distance between the center of the through hole 10a and the center of the optical laminate 100 is preferably 100 mm or less, more preferably 50 mm or less, even more preferably 30 mm or less, and particularly preferably 10 mm or less. When the optical laminate 100 is rectangular or has an irregularly shaped processing part, the distance from the end closest to the through hole 10a among all ends of the optical laminate 100 is set as the distance from the end of the optical laminate 100.

[0118] The through hole 10a has any suitable shape when viewed from the stacking direction. Examples of the shapes of the through hole 10a when viewed from the stacking direction include polygonal shapes such as rectangles, circles, and ellipses, with circles being the most preferred.

[0119] The diameter of the through hole 10a is, for example, 8 mm or less, preferably 6 mm or less. On the other hand, the lower limit of the diameter of the through hole 10a is typically 1 mm.

[0120] Even with through holes of such diameter, optical laminates can stably suppress crack initiation and / or propagation.

[0121] B. Details of the optical laminate Next, refer to Figures 1-5 The details of an optical laminate according to one embodiment will be described.

[0122] like Figure 1 As shown, in one embodiment, the optical laminate 100 sequentially comprises the first retardation film 1, the first adhesive layer 61, the polarizer 3, the second adhesive layer 62, the second retardation film 2, the adhesive layer 5, and the release liner 7.

[0123] B-1. First phase difference film The first phase difference film 1 has any suitable configuration.

[0124] The first retardation membrane typically comprises a cellulose-based resin. If the first retardation membrane comprises a cellulose-based resin, the CTE of the first retardation membrane can be stably adjusted to the range described above.

[0125] Examples of cellulose-based resins include triacetyl cellulose (TAC) and diacetyl cellulose, with triacetyl cellulose (TAC) being the most preferred.

[0126] Cellulose resins can be used alone or in combination.

[0127] The first phase difference film 1 can have a single-layer structure or a stacked structure.

[0128] In one embodiment, the first phase difference film 1 has a single-layer structure.

[0129] The first phase difference film 1, which has a single-layer structure, is typically composed of a stretched film having the aforementioned in-plane phase difference. The stretched film is prepared by stretching a cellulose-based resin film (preferably a TAC film).

[0130] A surface treatment layer is provided on the surface of the first retardation film 1, which has a single-layer structure, as needed. Examples of surface treatment layers include hard coatings, anti-reflective layers, anti-adhesion layers, and anti-glare treatment layers. The surface treatment layer is preferably provided on the surface of the first retardation film 1 opposite to the polarizer 3.

[0131] like Figure 4 As shown in the diagram, in another embodiment, the first phase difference film 1 has a stacked structure.

[0132] The first phase difference film 1 having a stacked structure typically includes a substrate 11 and an alignment fixing layer 12 of a liquid crystal compound.

[0133] In this specification, the term "alignment-fixing layer of liquid crystal compound" refers to a layer in which the liquid crystal compound is oriented in a specified direction and its orientation 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 below.

[0134] Hereinafter, the alignment fixing layer of the liquid crystal compound provided in the first phase difference film 1 is sometimes referred to as the first liquid crystal alignment fixing layer 12.

[0135] The substrate 11 can be located on the opposite side of the polarizer 3 relative to the first liquid crystal alignment fixing layer 12, or it can be located between the first liquid crystal alignment fixing layer 12 and the polarizer 3 (see reference). Figure 1 ).

[0136] When the substrate 11 is located on the opposite side of the polarizer 3 relative to the first liquid crystal alignment fixing layer 12, the first liquid crystal alignment fixing layer 12 is attached to the polarizer 3 via the first adhesive layer 61 (see reference). Figure 1 ).

[0137] With the substrate 11 located between the first liquid crystal alignment fixing layer 12 and the polarizer 3, the substrate 11 is attached to the polarizer 3 via the first adhesive layer 61 (see reference). Figure 1 ).

[0138] The substrate 11 is typically composed of a cellulose-based resin film (preferably a TAC film).

[0139] In one embodiment, the substrate 11 is substantially optically isotropic.

[0140] The in-plane phase difference Re(550) of the substrate 11 is, for example, 10 nm or less, preferably 8 nm or less, and more preferably 5 nm or less. On the other hand, the lower limit of the in-plane phase difference Re(550) of the substrate 11 is typically 0 nm.

[0141] The thickness of the substrate 11 is, for example, 10 μm to 50 μm, preferably 20 μm to 30 μm.

[0142] The surface treatment layer described above is provided on the surface of the substrate 11 as needed. Preferably, the surface treatment layer is provided on the surface of the substrate 11 opposite to the first liquid crystal alignment fixing layer 12.

[0143] The first liquid crystal alignment fixing layer 12 is supported by the substrate 11.

[0144] In the first liquid crystal alignment fixing layer 12, typically, the rod-shaped liquid crystal compound is aligned (plane alignment) in a state where it is arranged along the slow axis direction of the first retardation film 1.

[0145] 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.

[0146] The liquid crystal properties of liquid crystal compounds can be manifested by either lyotropic or thermotropic mechanisms.

[0147] When the liquid crystal compound contains liquid crystal monomers, these monomers are preferably polymerizable or crosslinkable monomers. The orientation state of the liquid crystal monomers can be fixed by polymerizing or crosslinking them (i.e., curing). After aligning the liquid crystal monomers, for example, if the monomers are polymerized or crosslinked together, the aforementioned orientation state can be fixed. Here, polymers are formed through polymerization, and three-dimensional mesh structures are formed through crosslinking, but these are non-liquid crystals. Therefore, the formed first liquid crystal alignment-fixed layer, for example, does not cause the temperature-induced phase transition to liquid crystal phase, glass phase, or crystalline phase characteristic of liquid crystal compounds. As a result, the first retardation film can possess extremely excellent stability unaffected by temperature changes.

[0148] Any suitable monomer can be used as the liquid crystal monomer. 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.

[0149] Specific examples of such polymeric mesocrystalline compounds include BASF's LC242, Merck's E7, and Wacker-Chem's LC-Sillicon-CC3767.

[0150] The alignment fixing layer of the liquid crystal compound can be formed by performing any suitable alignment treatment on the surface of any suitable coating substrate, coating the surface with a coating liquid containing the liquid crystal compound, so that the liquid crystal compound is aligned in a direction corresponding to the above-mentioned alignment treatment, and fixing the alignment state.

[0151] As an orientation treatment, examples include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment.

[0152] Specific examples of liquid crystal compounds and detailed methods for forming the alignment fixing layer are described in Japanese Patent Application Publication No. 2006-163343. The contents of that publication are incorporated herein by reference.

[0153] The range of the in-plane phase difference Re (550) of the first liquid crystal alignment fixing layer 12 is, for example, the same as the range of the in-plane phase difference Re (550) of the first phase difference film 1 described above.

[0154] The thickness of the first liquid crystal alignment fixing layer 12 is arbitrarily and appropriately adjusted to obtain the desired in-plane phase difference. The thickness of the first liquid crystal alignment fixing layer 12 is, for example, 5 μm or less, preferably 3 μm or less, and more preferably 2 μm or less. On the other hand, the lower limit of the thickness of the first liquid crystal alignment fixing layer 12 is typically 0.5 μm.

[0155] If the first liquid crystal alignment fixing layer has such a thickness, the optical laminate can be further thinned.

[0156] In the example shown, the first liquid crystal alignment fixing layer 12 is attached to the substrate 11 via an adhesive layer 13. In other words, the first retardation film 1 in the example shown sequentially comprises a substrate 11, an adhesive layer 13, and a first liquid crystal alignment fixing layer 12.

[0157] The adhesive layer 13 can be either an adhesive layer or a bonding agent layer. In the example shown in the figure, the adhesive layer 13 is an adhesive layer 13a.

[0158] The adhesive layer 13a is composed of any suitable adhesive.

[0159] Examples of adhesives include water-based adhesives; thermosetting adhesives; moisture-curing adhesives; and UV-curing adhesives (UV adhesives), which are active energy ray-curing adhesives.

[0160] Adhesives can be used alone or in combination.

[0161] In one embodiment, the adhesive layer 13a is formed by solidifying and / or curing a water-based adhesive. In other words, the adhesive layer 13a comprises a solidified and / or cured form of the water-based adhesive. With this configuration, a thinner adhesive layer can be achieved.

[0162] Water-based adhesives can have any suitable composition. Before solidification (curing), water-based adhesives are typically liquid at room temperature (25°C).

[0163] In one embodiment, the aqueous adhesive comprises a polyvinyl alcohol (PVA)-based resin. This PVA-based resin preferably contains acetyl groups. If the PVA-based resin of the aqueous adhesive contains acetyl groups, the adhesion between the first liquid crystal alignment fixing layer and the adhesive layer can be improved.

[0164] The average degree of saponification of PVA-based resins containing acetyl groups is, for example, 85 mol% or more, preferably 90 mol% or more. On the other hand, the average degree of saponification of PVA-based resins containing acetyl groups is, for example, 100 mol% or less.

[0165] It should be noted that the average degree of saponification is determined, for example, by NMR or according to JIS K 6726.

[0166] The degree of acetylation of the PVA-based resin containing acetylacetyl groups is, for example, 0.1 mol% or more, preferably 1 mol% or more, and more preferably 2 mol% or more. On the other hand, the degree of acetylacetylation of the PVA-based resin containing acetylacetyl groups is, for example, 40 mol% or less, preferably 20 mol% or less, and more preferably 7 mol% or less.

[0167] It should be noted that the degree of acetylation is calculated, for example, from a spectrum measured by NMR.

[0168] The average degree of polymerization of the PVA-based resin in the water-based adhesive is, for example, 100 or more, preferably 1000 or more. On the other hand, the average degree of polymerization of the PVA-based resin in the water-based adhesive is, for example, 5000 or less, preferably 4000 or less, and more preferably 2000 or less.

[0169] Water-based adhesives can also contain any suitable additives. Examples of additives include crosslinking agents, refractive index modifiers, UV absorbers, antioxidants, and leveling agents.

[0170] Additives can be used alone or in combination.

[0171] In one embodiment, the aqueous adhesive, in addition to the aforementioned PVA-based resin, also includes a crosslinking agent as an additive. The crosslinking agent crosslinks the aforementioned PVA-based resin, thereby curing the aqueous adhesive. Examples of crosslinking agents include melamine resins such as hydroxymethyl melamine; alkylene diamines; isocyanates; epoxy resins; and aldehydes.

[0172] Crosslinking agents can be used alone or in combination.

[0173] The crosslinking agent in the water-based adhesive contains, for example, 10 to 50 parts by weight of PVA resin per 100 parts by weight, preferably 20 to 40 parts by weight.

[0174] The thickness of such adhesive layer 13 is, for example, 1 μm or less, preferably 0.5 μm or less, more preferably 0.20 μm or less, even more preferably 0.15 μm or less, and especially preferably 0.10 μm or less.

[0175] On the other hand, the lower limit of the thickness of the adhesive layer 13 is typically 0.01 μm.

[0176] The first liquid crystal alignment fixing layer 12 may also be formed directly on the substrate 11 without the adhesive layer 13. Alternatively, the first liquid crystal alignment fixing layer 12 may be laminated on the substrate 11 via an alignment layer for aligning the liquid crystal.

[0177] B-2. Polarizer like Figure 1 As shown, the polarizer 3 can have any suitable configuration. For example, the polarizer can be made of a single layer of resin film, or it can be a polarizer obtained by using two or more layers of laminate.

[0178] 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 or dichroic dyes; and polyene-based oriented films such as dehydrated PVA products or 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.

[0179] 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 laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by coating a PVA-based resin solution onto a resin substrate and drying it to form a PVA-based resin layer on the resin substrate, thus obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizer from the PVA-based resin layer. In one embodiment, a polyvinyl alcohol-based resin layer comprising a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may, if necessary, further include air stretching of the laminate at a high temperature (e.g., above 95°C) prior to stretching in the aqueous boric acid solution. Furthermore, in one embodiment, the laminate is subjected to a drying shrinkage treatment that causes it to shrink by more than 2% in the width direction while being heated and conveyed along the length direction. 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. Furthermore, by simultaneously improving the orientation of PVA beforehand, problems such as decreased orientation and dissolution of PVA can be prevented when immersed in water during subsequent dyeing and stretching processes, thus achieving high optical properties. Moreover, when the PVA-based resin layer is immersed in a liquid, compared to when 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 through processing steps such as dyeing and underwater stretching in which the laminate is immersed in a liquid can be improved. Furthermore, by utilizing the drying shrinkage treatment to shrink the laminate along the width direction, optical properties can be improved. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can also 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.

[0180] Detailed descriptions of the manufacturing method of such a polarizer 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.

[0181] 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 simultaneously with dyeing. Alternatively, dyeing can be performed after stretching. Depending on the needs, the PVA-based resin film may undergo swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based resin film in water for washing before dyeing, not only can stains and anti-blocking agents on the surface of the PVA-based resin film be washed away, but the PVA-based resin film can also swell, thus suppressing uneven dyeing.

[0182] The polarizer 3 typically exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The transmittance of the polarizer 3 is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer 3 is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher.

[0183] B-3. ​​Second phase difference film The second phase difference film 2 has any suitable configuration.

[0184] The second phase difference film 2 typically includes a stretched film prepared by stretching a resin film, and / or an orientation fixing layer of a liquid crystal compound.

[0185] In one embodiment, the second retardation film 2 comprises an alignment fixing layer of a liquid crystal compound.

[0186] If the second retardation film includes an alignment fixing layer of a liquid crystal compound, the difference between nx and ny in the second retardation film can be significantly increased compared to non-liquid crystal materials, thus significantly reducing the thickness of the retardation film with the desired in-plane retardation. As a result, the optical laminate can be further thinned.

[0187] The second phase difference film 2 may have one or more liquid crystal compound alignment fixing layers.

[0188] like Figure 5 As shown, in one embodiment, the second retardation film 2 includes two alignment fixing layers of liquid crystal compounds. Hereinafter, the two alignment fixing layers of liquid crystal compounds included in the second retardation film 2 are sometimes referred to as the second liquid crystal alignment fixing layer 22 and the third liquid crystal alignment fixing layer 23.

[0189] The second liquid crystal alignment layer 22 and the third liquid crystal alignment layer 23 are each described in the same manner as the first liquid crystal alignment layer 12. Therefore, detailed descriptions of the second liquid crystal alignment layer 22 and the third liquid crystal alignment layer 23 are appropriately omitted.

[0190] The second liquid crystal alignment fixing layer 22 is located between the polarizer 3 and the third liquid crystal alignment fixing layer 23 (see reference). Figure 1 Therefore, the second liquid crystal alignment fixing layer 22 is typically attached to the polarizer 3 via the second adhesive layer 62.

[0191] The third liquid crystal alignment fixing layer 23 is located on the opposite side of the polarizer 3 relative to the second liquid crystal alignment fixing layer 22 (see reference). Figure 1 ).

[0192] The second liquid crystal alignment fixing layer 22 typically functions as a λ / 2 plate. The third liquid crystal alignment fixing layer 23 typically functions as a λ / 4 plate.

[0193] With this configuration, the wavelength dispersion characteristics of the second retardation film 2 can be made close to the ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflection properties can be imparted to the optical laminate.

[0194] It should be noted that the second liquid crystal alignment fixing layer 22 can also function as a λ / 4 plate, and the third liquid crystal alignment fixing layer 23 can function as a λ / 2 plate.

[0195] 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, 10° to 20°, preferably 12° to 18°, and more preferably 14° to 16°.

[0196] Furthermore, the angle between the absorption axis direction of the polarizer 3 and the slow axis direction of the third liquid crystal alignment fixing layer 23 is, for example, 70° to 80°, preferably 72° to 78°, and more preferably 74° to 76°.

[0197] With this configuration, the wavelength dispersion characteristics of the second phase retardation film 2 can be made closer to the ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflection properties can be stably imparted to the optical laminate.

[0198] It should be noted that 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 and the range of the angle between the absorption axis direction of the polarizer and the slow axis direction of the third liquid crystal alignment fixing layer can also be opposite.

[0199] In the example shown, the second liquid crystal alignment fixing layer 22 and the third liquid crystal alignment fixing layer 23 are bonded together by an adhesive layer 24. The adhesive layer 24 is described in the same manner as the first adhesive layer 61 described above. Therefore, a detailed description of the adhesive layer 24 is omitted.

[0200] B-4. Adhesive layer like Figure 1As shown, the adhesive layer 5 is typically disposed on the second surface 2b of the second phase reversal film 2. In one embodiment, the adhesive layer 5 is disposed on the surface of the third liquid crystal alignment fixing layer 23 opposite to the second liquid crystal alignment fixing layer 22 (see Figure 1). Figure 5 ).

[0201] The adhesive layer 5 is made of any suitable adhesive.

[0202] Examples of adhesives include (meth)acrylic adhesives, urethane adhesives, and silicone adhesives. It should be noted that "(meth)acrylic" refers to acrylic and / or methacrylic adhesives.

[0203] Adhesives can be used alone or in combination.

[0204] Among adhesives, (meth)acrylic adhesives are preferred.

[0205] The thickness of the adhesive layer 5 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 5 is, for example, 50 μm or less, and more preferably 30 μm or less.

[0206] B-5. Stripping the liner The release liner 7 comprises any suitable resin material. Examples of resin materials include polyethylene terephthalate (PET), polyethylene, and polypropylene.

[0207] Resin materials can be used alone or in combination.

[0208] In one embodiment, a release treatment layer is provided on the contact surface of the release liner 7 with the adhesive layer 5.

[0209] The release treatment layer typically includes a release agent.

[0210] 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 vinyl addition-type silicones are even more preferred.

[0211] Release agents can be used alone or in combination.

[0212] The thickness of the release layer is, for example, 50nm to 400nm.

[0213] B-6. Protective layer like Figure 2 As shown, the optical laminate 100 may further include a protective layer 4.

[0214] The protective layer 4 contains any suitable transparent resin.

[0215] Examples of transparent resins include cyclic olefin (COP) resins such as polynorbornene; polyester resins such as polyethylene terephthalate (PET); cellulose resins such as triacetyl cellulose (TAC); polycarbonate (PC) resins; (meth)acrylic acid resins; polyvinyl alcohol resins; polyamide resins; polyimide resins; polyethersulfone resins; polysulfone resins; polystyrene resins; polyolefin resins; and acetate resins. Additionally, thermosetting or UV-curing resins such as (meth)acrylic acid, urethane, (meth)acrylate urethane, epoxy, and silicone resins can also be used. Furthermore, glassy polymers such as siloxane polymers can also be used. Furthermore, polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As a material for the protective layer, a resin composition can be used, for example, a thermoplastic resin containing substituted or unsubstituted imide groups on the side chains and a thermoplastic resin containing substituted or unsubstituted phenyl and nitrile groups on the side chains. Examples include resin compositions having alternating copolymers of isobutylene and N-methylmaleimide and acrylonitrile-styrene copolymers. The polymer film can be, for example, an extruded product of the above-described resin composition.

[0216] The materials for the protective layer can be used alone or in combination.

[0217] The thickness of the protective layer 4 is, for example, 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and even more preferably 5 μm to 150 μm.

[0218] B-7. Irregular Shape Processing Department like Figure 3 As shown, in one embodiment, the optical laminate 100 has the aforementioned irregularly shaped processing section 10.

[0219] The irregularly shaped processing section 10 is formed by any suitable processing method.

[0220] As processing methods, cutting processing and thermal cutting processing can be listed, with thermal cutting processing being a preferred example.

[0221] Specific examples of thermal cutting processes include laser processing, plasma processing, and gas cutting processes.

[0222] In one embodiment, the irregularly shaped processing section 10 is formed by laser processing.

[0223] The peak wavelength of the laser used in laser processing is, for example, 1500 nm or less, preferably 1000 nm or less, more preferably 900 nm or less, and even more preferably 680 nm or less. On the other hand, the wavelength of the laser is, for example, 100 nm or more, preferably 220 nm or more.

[0224] If the laser has such a peak wavelength, it is possible to improve the smoothness of the end face of the irregularly shaped part in the optical laminate, and as a result, the propagation of cracks from the end face of the irregularly shaped part can be stably suppressed.

[0225] The laser irradiation conditions are arbitrarily and appropriately adjusted.

[0226] The frequency of the laser is, for example, 1 kHz to 300 kHz, preferably 20 kHz to 100 kHz.

[0227] The processing speed using lasers is, for example, 1 mm / s to 1000 mm / s, preferably 10 mm / s to 100 mm / s.

[0228] C. Image display device The optical laminates described in items A and B 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.

[0229] The image display device according to an embodiment of the present invention includes an image display panel and the optical stack 100 described above. The image display panel typically includes image display units. The optical stack 100 is disposed on the visually verifiable side of the image display panel. In the optical stack 100, the first retardation film 1 is located relative to the polarizer 3 on the visually verifiable side, i.e., the side opposite to the image display panel.

[0230] In such an image display device, since the first phase difference film of the optical laminate has the aforementioned in-plane phase difference and the aforementioned CTE, the visual confirmability via the polarizing member (typically polarized sunglasses) is excellent, and the generation and / or propagation of cracks in the optical laminate can be suppressed regardless of the usage environment of the image display device.

[0231] Furthermore, the image display device may also include a camera unit. In this case, the optical laminate 100 preferably includes a shaped processing unit 10. When the optical laminate 100 is applied to the image display device, the shaped processing unit 10 is typically arranged opposite to the camera unit.

[0232] Example The present invention will now be specifically described through examples, but the present invention is not limited to these examples. It should be noted that the methods for measuring each characteristic are as follows.

[0233] (1) Measurement of phase difference The in-plane phase difference between the first and second phase retardation films used in the examples and comparative examples was automatically measured using a KOBRA-WPR meter manufactured by Oji. The measurement wavelength was 550 nm, and the measurement temperature was 25 °C.

[0234] (2) Determination of mean linear expansion rate Using a TMA analysis apparatus (manufactured by Hitachi High-Tech Science Co., Ltd., TMA7100E), the dimensional changes of the first phase difference film obtained in the preparation example and the protective layers used in the examples and comparative examples were measured under the following conditions.

[0235] More specifically, the sample of the first phase difference film or protective layer is placed in the TMA analysis device and the sample is run in a cycle of (1) cooling from 25°C to -40°C, (2) heating from -40°C to 85°C, (3) cooling from 85°C to -40°C, (4) heating from -40°C to 85°C, (5) cooling from 85°C to -40°C, (6) heating from -40°C to 85°C, and (7) cooling from 85°C to 25°C, and the maximum and minimum values ​​of the sample length are measured.

[0236] The obtained value is substituted into equation (A) below to calculate the dimensional change rate. Then, the obtained dimensional change rate is substituted into equation (B) below to calculate the average linear expansion rate ( / ℃) of the first phase difference film and the protective layer respectively. The results are shown in Table 1.

[0237] It should be noted that in the case of films where molecules are oriented or stretched, such as retardation films or polarizers, the average linear expansion rate sometimes differs depending on the in-plane orientation. In such cases, refer to the value of the orientation where the average linear expansion rate becomes the largest.

[0238] <Measurement Conditions> Ambient humidity: 50%RH Low temperature side: -40℃ High-temperature side temperature: 85℃ Heating rate: 5℃ / min Dimensional change rate = (ΔL / L) × 100··· (A) ΔL: Dimensional change during measurement (length of the largest sample during the cycle - length of the smallest sample during the cycle) L: Length of the sample at 25℃ Average linear expansion rate ( / ℃) = (Rate of dimensional change / ΔT) / 100··· (B) ΔT: Temperature change (temperature on the high-temperature side - temperature on the low-temperature side) (3) Sunglasses evaluation (visual confirmation) The organic EL display device (manufactured by Samsung, product number "Galaxy A41") was disassembled to remove the organic EL panel. Test samples were prepared by attaching the optical laminates obtained in the examples and comparative examples to the organic EL panel using an adhesive layer.

[0239] Next, a white image was displayed on the organic EL panel, and the color rendering when the image was viewed through polarized sunglasses was evaluated according to the following criteria. The results are shown in Table 1.

[0240] Good: Able to be visually confirmed from all orientations.

[0241] Problem: Angles that cannot be visually confirmed.

[0242] (4) Crack evaluation Test samples were prepared by attaching the optical laminates obtained in the examples and comparative examples to a glass plate using an adhesive layer.

[0243] Next, the test sample was subjected to a thermal shock test that would be repeated 300 times, consisting of holding it at -40°C for 30 minutes and then at 85°C for 30 minutes.

[0244] The formation of cracks near the through-holes in the optical laminate was then evaluated according to the following criteria. The results are shown in Table 1.

[0245] Excellent: No cracks larger than 50μm are generated.

[0246] Good: Cracks larger than 50 μm were generated, but no cracks larger than 200 μm were generated.

[0247] Defect: Cracks larger than 200μm are present.

[0248] <Preparation of the first phase difference film> <<Preparation Example 1>> A liquid crystal composition (coating solution) was prepared by dissolving 10 parts by mass of a polymerizable liquid crystal (manufactured by BASF: trade name "Paliocolor LC242", denoted by the following formula) exhibiting a nematic liquid crystal phase and 3 parts by mass of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "Irgacure 907") in 40 parts by mass of toluene.

[0249] [Chemical Formula 1] The surface of a polyethylene terephthalate (PET) film (38 μm thick), which serves as the coating substrate, is rubbed with a friction cloth to perform an orientation treatment. The orientation treatment direction is set so that when it is attached to the polarizer (described later), it is at a 45° angle relative to the absorption axis of the polarizer when viewed from the visual confirmation side.

[0250] The liquid crystal coating liquid was applied to the orientation-treated surface using a bar coater, and the liquid crystal compound was oriented by heating and drying at 90°C for 2 minutes.

[0251] The liquid crystal layer formed in this manner was irradiated with a metal halide lamp at a concentration of 1 mJ / cm². 2 The liquid crystal layer is cured by light, thereby forming a first liquid crystal alignment fixing layer on the PET film. The thickness of the first liquid crystal alignment fixing layer is 1 μm.

[0252] The first liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. The in-plane phase difference Re(550) of the first liquid crystal alignment fixing layer is 100 nm. That is, the first liquid crystal alignment fixing layer can function as a λ / 4 plate.

[0253] In addition, a triacetyl cellulose (TAC) membrane (manufactured by Fujifilm, trade name: TJ25UL, thickness: 25μm) was prepared as the substrate. The in-plane phase difference Re(550) of this substrate was 0nm.

[0254] In addition, a water-based adhesive is prepared by dissolving and / or dispersing polyvinyl alcohol resin containing acetylacetyl groups (average degree of polymerization: 1,200, degree of saponification: 98.5 mol%, degree of acetylacetylation: 5 mol%) and hydroxymethyl melamine in water at a mass ratio of 3:1.

[0255] Next, the liquid crystal alignment fixing layer was attached to the TAC film using an aqueous adhesive and dried at 60°C for 5 minutes. This cured the aqueous adhesive, forming an aqueous adhesive layer containing the cured aqueous adhesive. The thickness of the aqueous adhesive layer was 0.1 μm.

[0256] Then, the PET film is peeled off from the liquid crystal alignment fixing layer.

[0257] Through the above, a first phase difference film with a stacked structure of a first liquid crystal alignment fixing layer / aqueous adhesive layer / substrate (TAC film) is prepared.

[0258] The in-plane phase difference Re(550) of the first phase difference film in Example 1 is 100 nm.

[0259] <<Preparation Example 2>> The in-plane phase difference Re (550) of the first liquid crystal alignment fixing layer was changed to 140 nm. Otherwise, the same procedure as in Preparation Example 1 was followed to prepare a first phase difference film having a stacked structure of first liquid crystal alignment fixing layer / adhesive layer / substrate (TAC film).

[0260] <<Preparation Example 3>> As the first phase difference membrane, a triacetyl cellulose (TAC) membrane (manufactured by Konica Minolta, trade name: KC2UGR-HC, thickness: 36 μm) with an in-plane phase difference Re (550) was prepared. The first phase difference membrane of Preparation Example 3 has a hard coating with a thickness of 5 μm on a monolayer structure of a stretched membrane containing TAC.

[0261] Furthermore, the first phase difference film of Example 3 has a refractive index of nx>ny>nz and an in-plane phase difference Re (550) of 103 nm.

[0262] <<Preparation Example 4>> As the first phase difference film, a cyclic olefin (COP) resin film (manufactured by ZEON Corporation, Japan, trade name: ZD12, thickness: 25 μm) with an in-plane phase difference Re (550) was prepared. The first phase difference film of Preparation Example 4 has a monolayer structure of a stretched film containing COP.

[0263] The first phase difference film of Example 4 has a refractive index of nx>ny>nz and an in-plane phase difference Re (550) of 99 nm.

[0264] <Preparation of the polarizer> <<Preparation Example 5>> 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.

[0265] 13 parts by mass of potassium iodide were added to 100 parts by mass of a PVA-based resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1. The resulting substance was dissolved in water to prepare a PVA aqueous solution (coating solution).

[0266] By coating the above-mentioned PVA aqueous solution onto the corona-treated surface of a thermoplastic resin substrate and drying it at 60°C, a PVA-based resin layer with a thickness of 13 μm is formed on the thermoplastic resin substrate.

[0267] The resulting laminate was stretched uniaxially to 2.4 times its original length in an oven at 130°C.

[0268] 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.

[0269] 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 weight ratio of 1:7 relative to 100 parts by weight of water) for 60 seconds while adjusting the concentration so that the final polarizer's monomer transmittance (Ts) becomes the desired value.

[0270] Next, the laminate was immersed in a crosslinking bath at 40°C (an aqueous solution of boric acid prepared by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) for 30 seconds.

[0271] Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, while being uniaxially stretched between rollers with different circumferential speeds along the longitudinal direction (length direction) with a total stretching ratio of 5.5.

[0272] The laminate was then immersed in a washing bath at 20°C (an aqueous solution of 4 parts by mass of potassium iodide in addition to 100 parts by mass of water).

[0273] The laminate is then dried in an oven at approximately 90°C while being brought into contact with SUS heating rollers at a surface temperature of approximately 75°C.

[0274] By operating in this way, a polarizer with a thickness of about 5 μm is formed on a thermoplastic resin substrate.

[0275] The polarizer, when viewed from the thickness direction, has the same shape and size as the first phase difference film in Preparation Example 1.

[0276] <Preparation of the second phase retardation film> <<Preparation Example 6>> The coating thickness was changed, and the alignment direction was changed to a 15° angle relative to the absorption axis of the polarizer when viewed from the visual confirmation side. Otherwise, the same procedure as in Preparation Example 1 was followed to form a second liquid crystal alignment fixing layer (λ / 2 plate) on the PET film. The in-plane phase difference Re(550) of the second liquid crystal alignment fixing layer is 270 nm. That is, this second liquid crystal alignment fixing layer can function as a λ / 2 plate. The thickness of the second liquid crystal alignment fixing layer is 2 μm.

[0277] Furthermore, the orientation processing direction was changed so that it was 75° relative to the absorption axis of the polarizer when viewed from the visual confirmation side. Otherwise, the same procedure as in Preparation Example 2 was followed to form a third liquid crystal alignment fixing layer (λ / 4 plate) on the PET film. The in-plane phase difference Re(550) of the third liquid crystal alignment fixing layer is 140 nm. That is, this third liquid crystal alignment fixing layer can function as a λ / 4 plate.

[0278] Next, the second liquid crystal alignment fixing layer and the third liquid crystal alignment fixing layer are bonded together using a UV-curable adhesive. Then, the UV-curable adhesive is irradiated with ultraviolet light to cure it. This forms a UV adhesive layer containing the cured UV-curable adhesive. The thickness of the UV adhesive layer is 1 μm.

[0279] Next, the PET film (coating substrate) is peeled off from the second liquid crystal alignment fixing layer.

[0280] Thus, a second phase difference film is prepared having a laminated structure of a second liquid crystal alignment fixing layer (λ / 2 plate) / UV adhesive layer / third liquid crystal alignment fixing layer (λ / 4 plate) / PET film (coating substrate).

[0281] The second phase retardation film, when viewed from the thickness direction, has the same shape and size as the first phase retardation film in Preparation Example 1.

[0282] [Example 1] The first liquid crystal alignment fixing layer of the first phase difference film obtained in Preparation Example 1 was bonded to the polarizer obtained in Preparation Example 5 using a UV-curable adhesive. Then, the UV-curable adhesive was irradiated with ultraviolet light to cure it, forming a UV adhesive layer containing the cured UV adhesive. The thickness of the UV adhesive layer was 1 μm.

[0283] Thus, a polarizer with a laminated structure of substrate / water-based adhesive layer / first liquid crystal alignment fixing layer / UV adhesive layer / polarizer / thermoplastic resin substrate is prepared.

[0284] In the polarizer, the angle between the absorption axis of the polarizer and the slow axis of the first liquid crystal alignment fixing layer is 45°.

[0285] Next, the thermoplastic resin substrate is peeled off from the polarizer.

[0286] Next, the polarizer of the polarizer was bonded to the second liquid crystal alignment fixing layer of the second phase retardation film obtained in Preparation Example 6 using a UV-curable adhesive. Then, the UV-curable adhesive was irradiated with ultraviolet light to cure it, forming a UV adhesive layer containing the cured UV adhesive. The thickness of the UV adhesive layer was 1 μm.

[0287] Next, the PET film (coating substrate) is peeled off from the third liquid crystal alignment fixing layer.

[0288] Subsequently, an (meth)acrylic adhesive is applied to the surface of the second phase difference film opposite to the polarizer, and more specifically to the surface of the third liquid crystal alignment fixing layer opposite to the second liquid crystal alignment fixing layer, to form an adhesive layer with a thickness of 15 μm.

[0289] Thus, an optical laminate with a stacked structure of substrate / water-based adhesive layer / first liquid crystal alignment fixing layer / UV adhesive layer / polarizer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer was prepared. The total thickness of the optical laminate is shown in Table 1.

[0290] In the optical laminate, the angle between the absorption axis of the polarizer and the slow axis of the second liquid crystal alignment fixing layer is 15°, and the angle between the absorption axis of the polarizer and the slow axis of the third liquid crystal alignment fixing layer is 75°.

[0291] Next, the optical laminate is cut in a roughly rectangular shape when viewed from the thickness direction, and a through hole is formed in the central part of the optical laminate, extending through the laminate along the lamination direction. At room temperature (25°C) and atmospheric pressure (0.1 MPa), the length of the optical laminate is 155 mm, and the width is 77 mm. The slow axis of the first retardation film is parallel to the length direction, and the absorption axis of the polarizer is at 45° relative to the length direction.

[0292] More specifically, a through-hole is formed in the polarizer using a laser processing apparatus (manufactured by Takei Electric Industries, trade name: TLSM-301) under the following processing conditions. The center of the through-hole substantially coincides with the center of the face of the optical laminate. The through-hole has a roughly circular shape when viewed from the lamination direction of the optical laminate. The diameter of the through-hole is 4 mm.

[0293] <Processing Conditions> Laser wavelength: 355nm Output power: 0.6W Processing speed: 38mm / s Frequency: 60000Hz The number of scans is set to the optimal value corresponding to the optical laminate.

[0294] [Example 2] The substrate of the first phase difference film obtained in Preparation Example 2 was bonded to the polarizer obtained in Preparation Example 5 using an ultraviolet-curable adhesive. Otherwise, the optical laminate was prepared in the same manner as in Example 1.

[0295] The optical laminate prepared in Example 2 has a laminated structure of a first liquid crystal alignment fixing layer / aqueous adhesive layer / substrate / UV adhesive layer / polarizer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer.

[0296] [Example 3] The first phase difference film obtained in Preparation Example 1 was replaced with the first phase difference film obtained in Preparation Example 3. Otherwise, the optical laminate was prepared in the same manner as in Example 1.

[0297] The optical laminate prepared in Example 3 has a laminated structure of hard coating / TAC film with in-plane phase difference Re (550) / UV adhesive layer / polarizer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer.

[0298] [Example 4] After bonding the first liquid crystal alignment fixing layer of the first phase difference film obtained in Preparation Example 1 to the polarizer obtained in Preparation Example 5 in the same manner as in Example 1, the thermoplastic resin substrate is peeled off from the polarizer and removed.

[0299] Next, a TAC film (manufactured by Fujifilm, trade name: TJ25UL, thickness: 25μm, Re(550): 0nm) as a protective layer is attached to the surface of the polarizer opposite to the first phase difference film using a UV-curable adhesive. Then, the coating is irradiated with ultraviolet light to cure the UV-curable adhesive, forming a UV adhesive layer containing the cured UV adhesive. The thickness of the UV adhesive layer is 1μm.

[0300] Thus, a polarizer with a stacked structure of substrate / water-based adhesive layer / first liquid crystal alignment fixing layer / UV adhesive layer / polarizer / UV adhesive layer / protective layer is prepared.

[0301] Next, the protective layer of the polarizer and the second liquid crystal alignment fixing layer of the second phase difference film obtained in Preparation Example 6 were bonded together in the same manner as in Example 1, and then the PET film was peeled off from the third liquid crystal alignment fixing layer.

[0302] Subsequently, an acrylic adhesive layer is formed on the surface of the second phase difference film opposite to the polarizer, in the same manner as in Example 1.

[0303] Thus, an optical laminate with a stacked structure of substrate / water-based adhesive layer / first liquid crystal alignment fixing layer / UV adhesive layer / polarizer / UV adhesive layer / protective layer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer is prepared.

[0304] The average linear expansion ratio (CTE) of the protective layer is shown in Table 1.

[0305] [Example 5] The TAC film used as the protective layer was replaced with a cyclic olefin (COP) resin film (manufactured by ZEON Corporation of Japan, trade name: ZF14, thickness: 13 μm, Re (550): 0 nm). Otherwise, the optical laminate was prepared in the same manner as in Example 4.

[0306] [Comparative Example 1] The first phase retardation film obtained in Preparation Example 1 was replaced with the first phase retardation film obtained in Preparation Example 4. Otherwise, the optical laminate was prepared in the same manner as in Example 1.

[0307] The optical laminate prepared in Comparative Example 1 has a laminated structure of COP-based resin film / UV adhesive layer / polarizer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer with an in-plane phase difference Re (550).

[0308] [Comparative Example 2] The first phase difference film obtained in Preparation Example 1 was replaced with a cyclic olefin (COP) resin film (manufactured by ZEON Corporation of Japan, trade name: ZF14, thickness: 23 μm, Re (550): 0 nm) as the protective layer. Otherwise, the optical laminate was prepared in the same manner as in Example 1.

[0309] The optical laminate prepared in Comparative Example 2 has a laminated structure of COP-based resin film / UV adhesive layer / polarizer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer without in-plane phase difference Re (550).

[0310] [Comparative Example 3] The first phase difference film obtained in Preparation Example 1 was changed to the first phase difference film obtained in Preparation Example 4, and the protective layer was changed to a cyclic olefin (COP) resin film (manufactured by ZEON Corporation of Japan, trade name: ZF14, thickness: 23 μm, Re (550): 0 nm). Otherwise, the optical laminate was prepared in the same manner as in Example 5.

[0311] The optical laminate prepared in Comparative Example 3 is an optical laminate with a COP-based resin film / UV adhesive layer / polarizer / UV adhesive layer / protective layer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer having an in-plane phase difference Re (550).

[0312] [Comparative Example 4] The first phase difference film obtained in Preparation Example 1 was replaced with a TAC film (manufactured by Fujifilm, trade name: TJ25UL, thickness: 25μm, Re(550): 0nm) as a protective layer. Otherwise, the optical laminate was prepared in the same manner as in Example 1.

[0313] The optical laminate prepared in Comparative Example 4 has a laminated structure of TAC film / UV adhesive layer / polarizer / UV adhesive layer / second liquid crystal alignment fixing layer / UV adhesive layer / third liquid crystal alignment fixing layer / acrylic adhesive layer without in-plane phase difference Re (550).

[0314] [evaluate] As shown in Table 1, it is known that if the in-plane phase difference Re(550) of the first retardation film of the optical laminate is 80 nm or more and 160 nm or less, and the average linear expansion coefficient of the first retardation film is 4.5 × 10⁻⁶, then... -5 When the temperature is below a certain level, the application of optical laminates to image display devices can improve visual confirmation via polarized sunglasses and suppress the generation of cracks during thermal shock tests.

[0315] Industrial availability The optical laminate manufactured by means of embodiments of the present invention can be suitably used in image display devices (typically 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 in-plane phase difference Re(550) of the first phase difference film is greater than 80 nm and less than 160 nm. The average linear expansion coefficient of the first phase difference film at temperatures ranging from -40℃ to 85℃ is 4.5 × 10⁻⁶. -5 / ℃ below.

2. 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° to 55°.

3. The optical laminate according to claim 1, having a through hole extending along the lamination direction of the optical laminate.

4. The optical laminate according to claim 3, wherein, The diameter of the through hole is less than 6 mm.

5. The optical laminate according to claim 1, wherein, The first phase difference film comprises a cellulose-based resin.

6. The optical laminate according to claim 1, wherein, In the stacking direction of the optical laminate, the distance from the surface of the polarizer on the side of the first retardation film to the surface of the second retardation film on the opposite side of the polarizer is less than the thickness of the first retardation film.

7. The optical laminate according to claim 1, wherein, In the stacking direction of the optical laminate, the distance from the surface of the first retardation film side of the polarizer to the surface of the second retardation film opposite to the polarizer is 5 μm to 15 μm.

8. The optical laminate according to claim 7, wherein, The thickness of the first phase retardation film exceeds 20 μm. The thickness of the second phase difference film is less than 10 μm.

9. The optical laminate according to claim 1, wherein, The second phase difference film is attached to the polarizer via an adhesive layer.

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

11. The optical laminate according to claim 1, wherein, The second phase difference film includes an alignment fixing layer of a liquid crystal compound.

12. An image display device comprising the optical laminate according to any one of claims 1 to 11, The first phase difference film is positioned on the visual confirmation side relative to the polarizer.

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