Optical laminate and display device

Abstract

[Technical Problem to be Solved]: The objective of this invention is to provide an optical laminate that exhibits good anti-mapping performance even when used in an image display device with an optical laminate containing an additional functional retardation film, and whose retardation film does not crack even after being stored for one month at a temperature of 23°C and a relative humidity of 55% following a heat durability test. ;;【Technical Means for Solving the Problem】;The solution of the present invention is an optical laminate, which sequentially comprises a retardation film, a polarizing element, and an antireflective film. The retardation film has a tensile modulus of 3000 MPa or less at 23°C, and the polarizing element has a moisture content that is greater than or equal to the equilibrium moisture content at 20°C and 20% relative humidity, and less than or equal to the equilibrium moisture content at 20°C and 48% relative humidity; and satisfies at least one of the following conditions (i) and (ii):;;(i)The antireflective film has a moisture permeability of 300 g / m²·day or less at 40°C and 90% relative humidity, and (ii)A protective film with a moisture permeability of 300 g / m²·day or less at 40°C and 90% relative humidity is provided between the polarizing element and the antireflective film.

Description

Technical Field

[0001] This invention relates to optical laminates, display devices, and methods for manufacturing optical laminates. Prior Technology

[0002] Liquid crystal displays (LCDs) are not only used in LCD televisions, but also widely in portable applications such as personal computers and mobile phones, as well as in-vehicle applications such as car navigation systems. Typically, an LCD device has liquid crystal panel components on both sides of a liquid crystal cell, with polarizing plates bonded together using pressure-sensitive adhesive. These liquid crystal panel components control the light from a backlight component to display the image. In addition, organic EL displays, like LCDs, have recently begun to be widely used in portable applications such as televisions and mobile phones, as well as in-vehicle applications such as car navigation systems. In both LCD and OLED displays, retardation films are used to provide functions such as widened viewing angles and anti-reflective properties against external light.

[0003] As mentioned above, polarizing plates are increasingly being installed in vehicles as components of liquid crystal displays or organic EL displays. Compared to polarizing plates used in portable applications such as televisions or mobile phones, polarizing plates used in automotive image display devices are exposed to high-temperature environments more frequently, thus requiring those with less change in characteristics at higher temperatures (high-temperature durability).

[0004] On the other hand, when in-vehicle display devices are used for purposes such as vehicle navigation, touch panel functionality is required. In recent years, the ratio of on-cell and in-cell touch panels has been gradually increasing. In this application, since the polarizing plate on the viewing side is located on the outermost side, in addition to the aforementioned durability, anti-mapping functionality is also required.

[0005] Japanese Patent Application Publication No. 2011-081219 (Patent Document 1) discloses an anti-glare hard coating film for the purpose of preventing external light reflection, which uses an anti-reflective layer composed of multiple layers by sputtering to be deposited on an anti-glare layer (Example 1, etc.).

[0006] In Patent Document 2, a polarizing plate containing a retardation film using a cyclic olefin resin for the purpose of expanding the viewing angle is described. Further, in Patent Document 3, a polarizing plate containing a retardation film using a cyclic olefin resin as a λ / 4 plate for the purpose of preventing reflection of external light is described.

[0007] This polarizing plate has good visibility after being laminated on a display device and does not crack (break) after a heat durability test (performed at 105°C for 500 hours). However, when stored in an environment of temperature 23°C and relative humidity 55% for about 1 month, cracks sometimes occur in the retardation film.

[0008] [Prior Art Documents]

[0009] [Patent Documents] <00000�0> [[ID=㔶]]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-081219

[0012] [Patent Document 2] Japanese Patent No. 5383594 [[ID=2」]]

[0013] [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-194483 Summary of the Invention Problems to be Solved by the Invention

[0014] An object of the present invention is to solve the above problems and provide an optical laminate which has good anti-reflection function even when using an optical laminate including a retardation film with additional functions in an image display device, and in which the retardation film does not crack even when stored in an environment of temperature 23°C and relative humidity 55% for 1 month after a heat durability test. Means for Solving the Problems <00000q7

[0015] ' The present invention provides the following optical laminate, display device, and method for manufacturing an optical laminate.

[0016] [1] An optical laminate having a retardation film, a polarizing element, and an antireflection film in this order.

[0017] The aforementioned phase retardation film has a tensile modulus (also known as tensile elastic modulus) of less than 3000 MPa at 23°C.

[0018] The aforementioned polarizing element has a moisture content that is above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity; and

[0019] At least one of the following requirements (i) and (ii) must be satisfied:

[0020] (i) The aforementioned antireflective film has a moisture permeability of less than 300 g / m² / day at a temperature of 40°C and a relative humidity of 90%.

[0021] (ii) Between the aforementioned polarizing element and the aforementioned antireflective film, there is a protective film with a moisture permeability of less than 300 g / m2.day at a temperature of 40°C and a relative humidity of 90%.

[0022] [2] An optical laminate, comprising, in sequence, a phase retardation film, a polarizing element, and an anti-reflection film.

[0023] The aforementioned phase retardation film has a tensile modulus of less than 3000 MPa at 23°C.

[0024] The aforementioned optical laminate has a moisture content that is above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity; and

[0025] At least one of the following requirements (i) and (ii) must be satisfied:

[0026] (i) The aforementioned antireflective film has a moisture permeability of less than 300 g / m² / day at a temperature of 40°C and a relative humidity of 90%.

[0027] (ii) Between the aforementioned polarizing element and the aforementioned antireflective film, there is a protective film with a moisture permeability of less than 300 g / m2.day at a temperature of 40°C and a relative humidity of 90%.

[0028] [3] An optical stack as described in [1] or [2], wherein a protective film is provided between the aforementioned polarizing element and the aforementioned antireflective film.

[0029] [4] An optical stack as described in any one of [1] to [3], wherein the aforementioned phase difference film is composed of a cyclic olefin resin.

[0030] [5] An optical stack as described in any one of [1] to [4], wherein the in-plane phase difference of the aforementioned phase difference film at a wavelength of 550 nm is 80 nm or more.

[0031] [6] An optical laminate as described in any one of [1] to [5], wherein the aforementioned antireflective film comprises a substrate film and an antireflective layer disposed on the surface of the aforementioned substrate film.

[0032] The aforementioned anti-reflective layer is composed of multiple thin films with different refractive indices.

[0033] [7] The optical stack as described in [6], wherein the aforementioned antireflective layer system comprises a thin film mainly composed of silicon dioxide (SiO2).

[0034] [8] An optical stack as described in [6] or [7], wherein the aforementioned antireflective layer comprises a thin film mainly composed of niobium pentoxide (Nb2O5) or titanium dioxide (TiO2).

[0035] [9] An optical stack as described in any one of [6] to [8], wherein the thickness of the aforementioned antireflective layer is 100 nm to 350 nm.

[0036]

[10] An optical laminate as described in any one of [6] to [9], wherein the aforementioned antireflective film further comprises a hard coating disposed between the aforementioned substrate film and the aforementioned antireflective layer.

[0037]

[11] A display device comprising: a display unit and an optical laminate as described in any one of [1] to

[10] ;

[0038] The aforementioned optical laminate is deposited on the viewing side surface of the aforementioned display unit in an orientation arranged from the display unit side in the order of the aforementioned polarizing element and the aforementioned anti-reflective film.

[0039]

[12] A method for manufacturing an optical laminate as described in [1] comprises:

[0040] A moisture content adjustment step of adjusting so that the moisture content of the aforementioned polarizing element is above the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

[0041]

[13] A method for manufacturing an optical laminate as described in [2], comprising:

[0042] A moisture content adjustment step of adjusting so that the moisture content of the aforementioned optical laminate is above the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%. Advantages of the Invention

[0043] According to the present invention, an optical laminate can be provided, which has good anti-moiré function even when an optical laminate including a retardation film with added functions is used in an image display device, and after a heat durability test, even when stored for 1 month in an environment of a temperature of 23°C and a relative humidity of 55%, the retardation film does not crack. Brief Explanation of Drawings

[0044]

[0045] FIG. 1 is an example of a schematic cross-sectional view showing the layer structure of an optical laminate. Embodiments

[0046] [Optical Laminate]

[0047] The optical laminate of the embodiment of the present invention sequentially has a retardation film, a polarizing element, and an antireflection film. The antireflection film is disposed on the viewing-side surface of the polarizing element. The retardation film is disposed on the surface of the polarizing element opposite to the viewing-side surface. The optical laminate may have a protective film (hereinafter also referred to as "first protective film") laminated on the surface of the polarizing element on the antireflection film side, and may also have a protective film (hereinafter also referred to as "second protective film") laminated on the surface of the polarizing element opposite to the antireflection film side. In this specification, the first protective film is set as the protective film laminated between the polarizing element and the antireflection film, and the second protective film is set as the protective film laminated between the polarizing element and the retardation film. In addition, in this specification, the polarizing plate includes the polarizing element, and when there is a first protective film and / or a second protective film laminated on the polarizing element, it means the laminate including these.

[0048] Figure 1 is a schematic cross-sectional view showing an example of the layer structure of the optical laminate of this embodiment. The optical laminate 100 includes a phase retardation film 30, a polarizing element 10, and an anti-reflection film 20, and further includes a first protective film 11 deposited on the surface of the anti-reflection film 20 side of the polarizing element 10.

[0049] The optical laminate of this embodiment has at least one of the features described in (a) and (b).

[0050] (a) The moisture content of the polarizing element is above the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

[0051] (b) The moisture content of the optical laminate is above the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

[0052] Regarding (a) above, the moisture content of the polarizing element is preferably above the equilibrium moisture content at 20°C and 30% relative humidity, and below the equilibrium moisture content at 20°C and 45% relative humidity. More preferably, the moisture content of the polarizing element is above the equilibrium moisture content at 20°C and 30% relative humidity, and below the equilibrium moisture content at 20°C and 40% relative humidity.

[0053] Regarding (b) above, the moisture content of the optical laminate is preferably above the equilibrium moisture content at 20°C and 30% relative humidity, and below the equilibrium moisture content at 20°C and 45% relative humidity. More preferably, the moisture content of the optical laminate is above the equilibrium moisture content at 20°C and 30% relative humidity, and below the equilibrium moisture content at 20°C and 40% relative humidity.

[0054] The optical stacking system satisfies at least one of the following requirements (i) and (ii).

[0055] (i) The moisture permeability of the antireflective film is below 300 g / m2.day at a temperature of 40°C and a relative humidity of 90%.

[0056] (ii) Between the polarizing element and the anti-reflective film, there is a protective film with a moisture permeability of less than 300 g / m2.day at a temperature of 40°C and a relative humidity of 90%.

[0057] Those who meet the above requirement (ii) are the same as those who meet the following requirement (iia).

[0058] (iia) has a first protective film deposited on the surface of the anti-reflective film side of the polarizing element, and a moisture permeability of less than 300 g / m2.day at a temperature of 40°C and a relative humidity of 90%.

[0059] The optical laminate of this embodiment, by ensuring that the moisture content of the polarizing element is within the aforementioned range and satisfying at least one of the aforementioned requirements (i) and (ii), exhibits no cracking (rupture) in the retardation film after a heat durability test (500 hours at 105°C), and even after storage in an environment with a temperature of 23°C and a relative humidity of 55% for approximately one month, it can suppress the occurrence of cracking in the retardation film. While the detailed mechanism remains unclear, it is conceivable that by setting the moisture permeability of the antireflective film or the first protective film to a predetermined range, the movement of moisture towards the polarizing element can be suppressed, thereby inhibiting dimensional changes during storage. Therefore, it is conceivable that it can suppress the occurrence of cracking in the retardation film.

[0060] <Polarizing element>

[0061] The polarizing element can be formed by adsorbing and aligning a dichroic dye onto a layer containing a polyvinyl alcohol (PVA) resin (also referred to as a "PVA resin layer" in this specification). Examples of such polarizing elements include: those formed by using a PVA resin film and dyeing the PVA resin film with a dichroic dye, followed by uniaxial stretching; or those formed by coating a substrate film with a coating solution containing a PVA resin, dyeing the PVA resin layer of the coating layer of the laminated film with a dichroic dye, and then uniaxially stretching the laminated film.

[0062] Polarizing elements are formed from PVA-based resins obtained by saponifying polyvinyl acetate-based resins. Polyvinyl acetate-based resins include not only homopolymers of vinyl acetate, but also copolymers of vinyl acetate and other monomers that can be copolymerized with it. Other monomers that can be copolymerized include, for example, unsaturated carboxylic acids, olefins such as ethylene, vinyl ethers, and unsaturated sulfonic acids.

[0063] The saponification degree of the PVA-based resin is preferably 85 mol% or higher, more preferably 90 mol% or higher, and even more preferably 99 mol% to 100 mol%. The degree of polymerization of the PVA-based resin is 1000 to 10000, preferably 1500 to 5000. This PVA-based resin can be modified, for example, to aldehyde-modified polyethylene formaldehyde, polyethylene acetal, polyethylene butyral, etc.

[0064] The thickness of the polarizing element in this embodiment is preferably 5 to 50 μm, more preferably 5 to 30 μm, and even more preferably 8 to 25 μm. By making the thickness of the polarizing element less than 50 μm, the effect of polyolefination of PVA resin on the reduction of optical properties can be suppressed under high temperature conditions. In addition, by making the thickness of the polarizing element more than 5 μm, it is easy to form a structure that achieves the desired optical properties.

[0065] The transmittance of the luminous factor correction element of the polarizing element is preferably 38.8% to 44.8%, more preferably 40.4% to 43.2%, and even more preferably 40.7% to 43.0%. When the transmittance of the luminous factor correction element exceeds 44.8%, the degradation of optical properties such as red-coloring may increase under high-temperature environments. When the transmittance of the luminous factor correction element is less than 38.8%, polyene formation is more likely to occur under high-temperature environments, and the degradation of optical properties may increase.

[0066] The transmittance of a luminescence factor-corrected monomer can be obtained by measuring the Y value after luminescence factor correction using a 2-degree field of view (C light source) as specified in JIS Z8701-1982. The transmittance of a luminescence factor-corrected monomer can be easily measured, for example, using a spectrophotometer (model: V7100) manufactured by Japan Spectrophotometer Co., Ltd.

[0067] (Feature(a))

[0068] In the case of characteristic (a), the moisture content of the polarizing element is above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity. More preferably, it is above the equilibrium moisture content at 20°C and 30% relative humidity, and below the equilibrium moisture content at 20°C and 45% relative humidity. Even more preferably, it is below the equilibrium moisture content at 20°C and 42% relative humidity, and even more preferably, it is below the equilibrium moisture content at 20°C and 40% relative humidity. Most preferably, it is below the equilibrium moisture content at 20°C and 38% relative humidity. Below the equilibrium moisture content at 20°C and 20% relative humidity, the polarizing element's processability decreases and it becomes prone to breakage. By achieving an equilibrium moisture content below 20°C and 48% relative humidity, an optical laminate with excellent damp heat durability and high temperature durability can be provided. This can be inferred to be because when the water content of the polarizing element is high, the polyolefination of the PVA-based resin contained in the polarizing element is easier to carry out. The aforementioned water content of the polarizing element refers to the water content of the polarizing element in the optical laminate.

[0069] Methods to confirm whether the moisture content of a polarizing element is above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity, can include: storing the polarizing element in an environment adjusted to the aforementioned temperature and relative humidity range for a certain period of time and confirming that its mass has not changed; or calculating the equilibrium moisture content of the polarizing element in an environment adjusted to the aforementioned temperature and relative humidity range in advance and comparing the moisture content of the polarizing element with the pre-calculated equilibrium moisture content. If the polarizing element is stored for a certain period of time and its mass does not change, it can be considered that the moisture content in the storage environment has reached equilibrium.

[0070] There are no particular limitations on the method for manufacturing a polarizing element with a moisture content of ≥ equilibrium moisture content at 20°C and 20% relative humidity and ≤ equilibrium moisture content at 20°C and 48% relative humidity. Examples include: storing the polarizing element in an environment adjusted to the above temperature and relative humidity range for 10 minutes to 3 hours, or performing heat treatment at 30°C to 90°C.

[0071] Other preferred methods for manufacturing polarizing elements with the aforementioned moisture content include: depositing a protective film onto at least one side of the polarizing element in an environment adjusted to the aforementioned temperature and relative humidity range; storing the polarizing element-based composite material for 10 minutes to 120 hours; or subjecting it to heat treatment at 30°C to 90°C. Also included is the method of, during the manufacture of an image display device, storing an image display panel with an optical composite material deposited in the image display unit in an environment adjusted to the aforementioned temperature and relative humidity range for 10 minutes to 3 hours; or subjecting it to heat treatment at 30°C to 90°C.

[0072] The optimal moisture content of the polarizing element is achieved during the material preparation stage used to construct the optical stack, either as a standalone polarizing element or a stack of polarizing elements and a protective film. This moisture content is adjusted to achieve the aforementioned numerical range. When adjusting the moisture content after constructing the optical stack, excessive curling can occur, sometimes leading to defects during bonding to the image display unit. By using a polarizing element with the aforementioned moisture content adjusted during the material preparation stage before constructing the optical stack, it is easy to construct an optical stack with a polarizing element whose moisture content meets the aforementioned numerical range. When the optical stack is bonded to the image display unit, the moisture content of the polarizing element within the optical stack can also be adjusted to achieve the aforementioned numerical range. In this case, since the optical stack is bonded to the image display unit, curling is less likely to occur.

[0073] (Feature (b))

[0074] In the case of characteristic (b), the moisture content of the optical laminate is above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity. More preferably, it is above the equilibrium moisture content at 20°C and 30% relative humidity, and below the equilibrium moisture content at 20°C and 45% relative humidity. Even more preferably, it is below the equilibrium moisture content at 20°C and 42% relative humidity, and even more preferably, it is below the equilibrium moisture content at 20°C and 40% relative humidity. Most preferably, it is below the equilibrium moisture content at 20°C and 38% relative humidity. When the moisture content of the optical laminate is lower than the equilibrium moisture content at 20°C and 20% relative humidity, the processability of the optical laminate decreases and it is prone to breakage. When the moisture content of the optical laminate is higher than the equilibrium moisture content at 20°C and 48% relative humidity, the transmittance of the polarizing element tends to decrease. This can be inferred to be because the polyolefination of PVA-based resins is easier to carry out when the water content of the optical laminate is high.

[0075] Methods for confirming whether the moisture content of an optical laminate is above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity, include: storing the optical laminate in an environment adjusted to the aforementioned temperature and relative humidity range for a certain period of time and confirming that its mass has not changed; or calculating the equilibrium moisture content of the optical laminate in an environment adjusted to the aforementioned temperature and relative humidity range in advance and comparing the moisture content of the optical laminate with the pre-calculated equilibrium moisture content. When the optical laminate is stored for a certain period of time and its mass does not change, it can be considered that the moisture content in the storage environment has reached equilibrium.

[0076] There are no particular limitations on the method for manufacturing an optical laminate with a moisture content of ≥ equilibrium moisture content at 20°C and 20% relative humidity and ≤ equilibrium moisture content at 20°C and 48% relative humidity. Examples include: storing the optical laminate in an environment adjusted to the above temperature and relative humidity range for 10 minutes to 3 hours, or performing heat treatment at 30°C to 90°C.

[0077] Alternatively, during the manufacture of an image display device, an image display panel in which an optical laminate has been deposited in the image display unit may be kept for 10 minutes to 3 hours in an environment adjusted to the above-mentioned temperature and relative humidity range, or a method of heat treatment may be performed at 30°C to 90°C.

[0078] (Manufacturing method of polarizing element)

[0079] There are no particular limitations on the manufacturing method of polarizing elements. Typical methods include: a method of producing a pre-wound polyvinyl alcohol resin film by rolling it out, stretching, dyeing, cross-linking, etc. (hereinafter referred to as "manufacturing method 1"); or a method that includes the steps of coating a coating liquid containing polyvinyl alcohol resin onto a substrate film to form a polyvinyl alcohol resin layer belonging to the coating layer and stretching the resulting laminate (hereinafter referred to as "manufacturing method 2").

[0080] Manufacturing method 1 can be manufactured by the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of dyeing the polyvinyl alcohol-based resin film with a dichroic pigment such as iodine to adsorb the dichroic pigment; a step of treating the polyvinyl alcohol-based resin film adsorbed with a boric acid aqueous solution; and a step of washing with water after treatment with a boric acid aqueous solution.

[0081] The swelling step involves immersing the polyvinyl alcohol (PVA) resin film in a swelling bath. This process removes dirt and anti-caking agents from the surface of the PVA resin film. Furthermore, swelling the PVA resin film helps to suppress uneven dyeing. The swelling bath typically uses a water-based medium, such as water, distilled water, or pure water. Surfactants and alcohols can be appropriately added to the swelling bath using common methods.

[0082] The temperature of the swelling bath is preferably 10 to 60°C, more preferably 15 to 45°C, and even more preferably 18 to 30°C. Furthermore, the immersion time in the swelling bath cannot be uniformly determined because the degree of swelling of the polyvinyl alcohol-based resin film is affected by the temperature of the swelling bath; however, it is preferably 5 to 300 seconds, more preferably 10 to 200 seconds, and even more preferably 20 to 100 seconds. The swelling step may be performed only once or multiple times as needed.

[0083] The dyeing step involves immersing a polyvinyl alcohol (PVA) resin film in a dyeing bath (iodine solution), which allows dichroic substances such as iodine or dichroic dyes to adsorb and align with the PVA resin film. The iodine solution is preferably an aqueous iodine solution containing iodine and iodides as dissolving agents. Examples of iodides include: potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide is preferred from the viewpoint of controlling the potassium content in the polarizing element.

[0084] In the staining bath, the concentration of iodine is preferably 0.01 to 1% by weight, more preferably 0.02 to 0.5% by weight. In the staining bath, the concentration of iodide is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, and even more preferably 0.1 to 3% by weight.

[0085] The temperature of the dyeing bath is preferably 10 to 50°C, more preferably 15 to 45°C, and even more preferably 18 to 30°C. Furthermore, the immersion time in the dyeing bath cannot be uniformly determined because the degree of dyeing of the polyvinyl alcohol-based resin film is affected by the temperature of the dyeing bath; however, it is preferably 10 to 300 seconds, more preferably 20 to 240 seconds. The dyeing step can be performed only once or multiple times as needed.

[0086] The crosslinking step involves immersing the dyed polyvinyl alcohol (PVA) resin film in a treatment bath (crosslinking bath) containing boron compounds. The boron compounds crosslink the PVA resin film, allowing iodine or dye molecules to adsorb onto the crosslinked structure. Examples of boron compounds include boric acid, borates, and borax. The crosslinking bath is generally an aqueous solution, but can also be a mixture of a water-miscible organic solvent and water. Furthermore, from the perspective of controlling the potassium content in the polarizing element, the crosslinking bath preferably contains potassium iodide.

[0087] In the crosslinking bath, the concentration of the boron compound is preferably 1 to 15% by weight, more preferably 1.5 to 10% by weight, and even more preferably 2 to 5% by weight. Furthermore, when potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably 1 to 15% by weight, more preferably 1.5 to 10% by weight, and even more preferably 2 to 5% by weight.

[0088] The temperature of the crosslinking bath is preferably 20 to 70°C, more preferably 30 to 60°C. Furthermore, the immersion time in the crosslinking bath cannot be uniformly determined because the degree of crosslinking of the polyvinyl alcohol-based resin film is affected by the temperature of the crosslinking bath; however, it is preferably 5 to 300 seconds, more preferably 10 to 200 seconds. The crosslinking step can be performed only once or multiple times as needed.

[0089] The stretching step is a process of stretching a polyvinyl alcohol (PVA) resin film by a predetermined ratio in at least one direction. Generally, this involves uniaxially stretching the PVA resin film in the transport direction (long side direction). There are no particular limitations on the stretching method; both wet stretching and dry stretching methods can be used. The stretching step can be performed only once or multiple times as needed. The stretching step can be performed at any stage in the manufacturing of polarizing elements.

[0090] In the wet stretching method, the treatment bath (stretching bath) can typically be water, or a mixture of water and an organic solvent miscible with water. From the viewpoint of controlling the potassium content in the polarizing element, the stretching bath preferably contains potassium iodide. When potassium iodide is used in the stretching bath, the concentration of potassium iodide in the stretching bath is preferably 1 to 15% by weight, more preferably 2 to 10% by weight, and even more preferably 3 to 6% by weight. Furthermore, from the viewpoint of suppressing film breakage during stretching, the treatment bath (stretching bath) may contain boron compounds. In this case, the concentration of boron compounds in the stretching bath is preferably 1 to 15% by weight, more preferably 1.5 to 10% by weight, and even more preferably 2 to 5% by weight.

[0091] The temperature of the stretching bath is preferably 25 to 80°C, more preferably 40 to 75°C, and even more preferably 50 to 70°C. Furthermore, the immersion time in the stretching bath cannot be uniformly determined because the degree of stretching of the polyvinyl alcohol-based resin film is affected by the temperature of the stretching bath; however, it is preferably 10 to 800 seconds, more preferably 30 to 500 seconds. The stretching treatment in the wet stretching method can be carried out in conjunction with any one or more of the following steps: swelling step, dyeing step, crosslinking step, and washing step.

[0092] Examples of dry stretching methods include: inter-roll stretching, heated roll stretching, and compression stretching. Dry stretching can be performed in conjunction with a drying step.

[0093] The total elongation ratio (cumulative elongation ratio) applied to the polyvinyl alcohol resin film can be appropriately set according to the purpose, preferably 2 to 7 times, more preferably 3 to 6.8 times, and even more preferably 3.5 to 6.5 times.

[0094] The cleaning step involves immersing the polyvinyl alcohol (PVA) resin film in a cleaning bath to remove impurities remaining on the surface of the PVA resin film. The cleaning bath typically uses a water-based medium, such as water, distilled water, or pure water. Furthermore, from the viewpoint of controlling the potassium content in the polarizing element, it is preferable to use potassium iodide in the cleaning bath. In this case, the concentration of potassium iodide in the cleaning bath is preferably 1 to 10% by weight, more preferably 1.5 to 4% by weight, and even more preferably 1.8 to 3.8% by weight.

[0095] The temperature of the washing bath is preferably 5 to 50°C, more preferably 10 to 40°C, and even more preferably 15 to 30°C. Furthermore, the soaking time in the washing bath cannot be uniformly determined because the degree of cleaning of the polyvinyl alcohol resin film is affected by the temperature of the washing bath; however, it is preferably 1 to 100 seconds, more preferably 2 to 50 seconds, and even more preferably 3 to 20 seconds. The washing step may be performed only once or multiple times as needed.

[0096] The drying step is the process of drying the polyvinyl alcohol resin film cleaned in the washing step to obtain the polarizing element. Drying can be carried out by any suitable method, such as natural drying, air drying, or heat drying.

[0097] Manufacturing method 2 can be performed by the following steps: coating a coating solution containing the above-mentioned polyvinyl alcohol resin onto a substrate film; uniaxially stretching the obtained laminated film; dyeing the polyvinyl alcohol resin layer of the uniaxially stretched laminated film with a dichroic dye, thereby adsorbing the dichroic dye to form a polarizing element; treating the film adsorbed with a boric acid aqueous solution; and washing with water after treatment with the boric acid aqueous solution. The substrate film used to form the polarizing element can also be used as a protective layer for the polarizing element. The substrate film can also be peeled off from the polarizing element as needed.

[0098] (Phase difference film)

[0099] Phase retardation film system: A tensile modulus of 3000 MPa or less at 23°C. According to the present invention, even if the optical laminate has a phase retardation film with this tensile modulus, cracking can be prevented. The lower limit of the tensile modulus at 23°C is not particularly limited, and can be, for example, 1000 MPa or more. The material of this phase retardation film can be, for example, composed of olefin-based resins. Olefin-based resins refer to resins derived from alicyclic olefins such as ethylene and propylene, or norbornene or its substitutes (hereinafter collectively referred to as norbornene monomers). Olefin-based resins can be copolymers using two or more monomers.

[0100] Among these, olefin-based resins are suitable for use: cyclic olefin resins that mainly contain constituent units derived from alicyclic olefins. Typical examples of alicyclic olefins constituting cyclic olefin resins include norbornene monomers. Norbornene is a compound in which one carbon-carbon bond of norbornene becomes a double bond, and according to IUPAC nomenclature, it is named bicyclo[2,2,1]hept-2-ene. Examples of substituted norbornene derivatives include 3-substituted derivatives, 4-substituted derivatives, and 4,5-disubstituted derivatives when the double bond position of norbornene is 1,2-position, and further examples include dicyclopentadiene or dimethylbridged octahydronaphthalene.

[0101] Cyclic olefin resins may or may not contain a norbornene ring in their constituent units. Norbornene monomers forming cyclic olefin resins without a norbornene ring in their constituent units are, for example, five-membered rings formed through ring-opening; representative examples include norbornene, dicyclopentadiene, 1- or 4-methylnorbornene, and 4-phenylnorbornene. When the cyclic olefin resin is a copolymer, the arrangement of the molecules is not particularly limited and can be random copolymers, block copolymers, or graft copolymers.

[0102] More specific examples of cyclic olefin resins include: ring-opening polymers of norcamphene monomers, ring-opening copolymers of norcamphene monomers and other monomers, polymeric modifications thereof involving maleic acid addition or cyclopentadiene addition, and such hydrogenated polymers or copolymers; addition polymers of norcamphene monomers, and addition copolymers of norcamphene monomers and other monomers. Other monomers used in the formation of copolymers include α-olefins, cycloalkenes, and non-conjugated dienes. Furthermore, cyclic olefin resins can be copolymers using one or more norcamphene monomers and other alicyclic olefins.

[0103] In the specific examples above, cyclic olefin resins are suitable for use with: resins obtained by hydrogenating ring-opening polymers or ring-opening copolymers using norbornene monomers. This cyclic olefin resin, by being configured as a pre-stretched film, and by attaching a shrinkable film with a predetermined shrinkage rate thereto and then heating to shrink it, can impart a phase difference film with high uniformity and a large phase difference value.

[0104] Commercially available cyclic olefin resins using this nobornene monomer, when referred to by trade name, include: "Zeonex" and "Zeonor" sold by Zeon Japan Co., Ltd.; and "Arton" sold by JSR Co., Ltd. Films or extended films of these cyclic olefin resins are also commercially available, for example, when referred to by trade name, include: "Zeonor Film" from Optes Co., Ltd.; "Arton Film" from JSR Co., Ltd.; and "Esushina" from Sekisui Chemicals Co., Ltd.

[0105] Furthermore, the phase retardation film used in this invention can also be a film composed of a mixed resin containing two or more olefin resins, or a film composed of a mixed resin of an olefin resin and other thermoplastic resins. For example, a mixed resin containing two or more olefin resins can include the mixture of the aforementioned cyclic olefin resin and chain aliphatic olefin resin. When using a mixed resin of an olefin resin and other thermoplastic resins, the other thermoplastic resins can be appropriately selected according to the purpose. Specific examples include: polyvinyl chloride resins, cellulose resins, polystyrene resins, acrylonitrile / butadiene / styrene copolymer resins, acrylonitrile / styrene copolymer resins, (meth)acrylic resins, polyvinyl acetate resins, polyvinyl chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyphenylene sulfide resins, polyurethane resins, polyether ether ketone resins, polyarylate resins, liquid crystal resins, polyamide-imide resins, polyamide-imide resins, and polytetrafluoroethylene resins, etc. These thermoplastic resins can be used alone or in combination of two or more. Furthermore, the above-mentioned thermoplastic resins can be used after undergoing any appropriate polymer modification. Examples of polymer modification include copolymerization, crosslinking, molecular end modification, and stereoregularity imparting, etc.

[0106] When using a mixture of olefin-based resins and other thermoplastic resins, the content of the other thermoplastic resins relative to the total resin is typically 50% by weight or less, preferably 40% by weight or less. By setting the content of the other thermoplastic resins within this range, the absolute value of the photoelasticity coefficient is smaller, resulting in a phase retardation film exhibiting good wavelength dispersion characteristics and excellent durability, mechanical strength, and transparency.

[0107] This olefin-based resin can be used to form a membrane by solution casting or melt extrusion. When the membrane is composed of two or more mixed resins, the membrane forming method is not particularly limited. For example, the following methods can be used: mixing the resin components with the solvent in a predetermined ratio, and then using the resulting homogeneous solution to form a membrane by casting; and mixing the resin components in a predetermined ratio by melt extrusion to form a membrane.

[0108] The aforementioned phase retardation film may contain residual solvents, stabilizers, plasticizers, anti-aging agents, antistatic agents, and ultraviolet absorbers, etc., as needed, without compromising the purpose of this invention. Other components may also be included as needed. Furthermore, a leveling agent may be included to reduce surface roughness.

[0109] The in-plane phase difference value of the retardation film used in this invention is preferably above 80 nm at a wavelength of 550 nm. The in-plane phase difference value at 550 nm can be, for example, below 300 nm or below 200 nm. With such a high phase difference value, after a heat durability test, even if stored in an environment at 23°C and 55% relative humidity for one month, the retardation film will not crack. Generally speaking, the higher the phase difference value, the more uniform the molecular alignment of the retardation film, and the easier it is to crack under external force.

[0110] The aforementioned phase difference film can be obtained by performing commonly known longitudinal uniaxial stretching or stretching transverse uniaxial stretching, synchronous biaxial stretching, successive biaxial stretching, etc. In addition to appropriately adjusting the stretching ratio and stretching speed in order to obtain the desired delay value, various temperatures and modes such as preheating temperature, stretching temperature, heat setting temperature, and cooling temperature during stretching can also be appropriately selected.

[0111] There is no particular limitation on the thickness of the phase retardation film, but it is preferably in the range of 15 to 80 μm, more preferably in the range of 18 to 45 μm, and most preferably in the range of 20 to 30 μm. When the thickness of the norcamphene-based resin film is less than 15 μm, it is difficult to process the film, and there is a tendency to make it difficult to show the predetermined phase retardation value. On the other hand, when the thickness of the norcamphene-based resin film exceeds 80 μm, the processability deteriorates, and there may be a decrease in transparency or an increase in the weight of the obtained polarizing plate.

[0112] (Other functional layers)

[0113] The polarizing plate of the present invention may also have other functional layers such as an antistatic layer or a second retardation layer. For example, in the case of use in an IPS-mode liquid crystal display device, a positive C-plate is sometimes used as the second retardation layer. The positive C-plate may be deposited between the polarizing element and the retardation film, or deposited on the side of the retardation film opposite to the polarizing element side.

[0114] Anti-reflective coating

[0115] The antireflective film system has an antireflective function that reduces the reflectivity of light incident from the viewing side surface of the optical laminate. To prevent reduced contrast caused by the reflection of external light, the optical laminate system has an antireflective film. To meet the above requirement (i), the antireflective film can be an antireflective film with a permeability of 300 g / m².day or less, preferably 100 g / m².day or less, at a temperature of 40% and a relative humidity of 90%. The permeability of the antireflective film is set to a value measured according to the method described in the embodiments below. By using this antireflective film with low permeability, damp heat durability and high temperature durability can be improved. The permeability of the antireflective film can be adjusted by the material and thickness of the antireflective layer, the material and thickness of the substrate film, etc. The permeability of the antireflective film at a temperature of 40% and a relative humidity of 90% is typically 1 g / m².day or more.

[0116] The anti-reflective film may be configured, for example, to have an anti-reflective layer on one side of the substrate film. There are no particular limitations on the substrate film; it may be made of the same material as the protective film described later.

[0117] The anti-reflective film can be any known anti-reflective film or a commercially available anti-reflective film, such as those listed below.

[0118] (a) Antireflective films using the principle of a so-called moth-eye structure, consisting of a raised pattern with a period controlled below the visible light wavelength (as described in Japanese Patent Application Publication Nos. 2010-122599, 2001-517319, 2004-205990, 2004-287238, 2001-27505, 2002-286906, and Japanese International Publication No. 2006 / 059686). Commercially available products may use, for example, Mosmite (registered trademark, manufactured by Mitsubishi Chemical Corporation).

[0119] (b) An anti-reflective film composed of a finely textured pattern that performs optical functions (anti-reflective films described in Japanese Patent Application Publication No. 2004-59822, Japanese Patent Publication No. 5-46064, Japanese Patent Publication No. 6-85103, etc.).

[0120] (c) An anti-reflective film formed by a pattern of numerous tiny bumps and depressions spaced at intervals below the wavelength of light (anti-reflective films described in Japanese Patent Application Publication No. 2001-264520, Japanese Patent Application Publication No. Hei 9-80205, etc.).

[0121] (d) Antireflective coatings of single or multiple layers with adjusted refractive index (as described in Japanese Patent Application Publication Nos. 2000-187102, 2004-345333, etc.). Commercially available products may use, for example, MTAR or MTAGAR (manufactured by Bikan Co., Ltd.).

[0122] The thickness of the anti-reflective coating is, for example, between 10 μm and 100 μm.

[0123] Antireflective films are best suited as thin films with strictly controlled thickness and refractive index, or as antireflective layers consisting of two or more layers. In this specification, "thin film" refers to a film with a thickness of 1 μm or less. The antireflective layer can be configured to utilize the interference effect of light to cancel out the phases of incident and reflected light after phase inversion, thus exhibiting antireflective function. The wavelength region of visible light exhibiting antireflective function is, for example, 380 to 780 nm, especially the wavelength region with high luminous factor in the range of 450 to 650 nm. Preferably, the antireflective layer is designed to minimize the reflectivity at its center wavelength of 550 nm. The thickness of the antireflective layer is preferably 100 nm to 350 nm, more preferably 150 nm to 300 nm.

[0124] In the design of antireflective layers based on the interference effect of light, methods to enhance the interference effect include increasing the refractive index difference between the antireflective layer and the anti-glare hard coating (described later). Generally, in multilayer antireflective layers constructed with 2 to 15 thin films (thin films with strictly controlled thickness and refractive index), forming multiple layers with different refractive indices at a predetermined thickness can increase the freedom of optical design of the antireflective layer and further enhance the antireflective effect. The spectral reflectance characteristics can also achieve uniformity (flatness) in the visible light region. Since the thin film requires high thickness accuracy, the formation of each layer is generally carried out by dry methods such as vacuum evaporation, sputtering, and CVD. Since the transmittance is set within a predetermined range, sputtering is preferred. Furthermore, by using an antireflective film with each layer formed by sputtering, an optically robust laminate with high scratch resistance can be constructed.

[0125] Anti-reflective layers are suitable for being formed by alternating layers of low-refractive-index and high-refractive-index layers. High-refractive-index layers or low-refractive-index layers may not have the same refractive index, but it is better to form them with the same refractive index using the same material, which is preferable from the perspective of reducing material and film formation costs.

[0126] Materials constituting the low-refractive-index layer (or materials that are the main components of the low-refractive-index layer) can be listed as follows: silicon dioxide (SiO2), silicon oxynitride (SiON), gallium oxide (Ga2O3), aluminum oxide (Al2O3), lanthanum oxide (La2O3), lanthanum fluoride (LaF3), magnesium fluoride (MgF2), sodium aluminum fluoride (Na3AlF6), etc. Among them, silicon dioxide (SiO2) is the best in terms of low refractive index, non-absorption in the visible light region, and high film strength.

[0127] Materials constituting a high refractive index layer (or materials that are the main components of a high refractive index layer) can be listed as follows: niobium pentoxide (Nb₂O₅), titanium dioxide (TiO₂), zirconium dioxide (ZrO₂), tantalum pentoxide (Ta₂O₅), silicon oxynitride (SiON), silicon nitride (Si₃N₄), and niobium silicon oxide (SiNbO). Among these, niobium pentoxide (Nb₂O₅) or titanium dioxide (TiO₂) are preferred due to their high refractive index and high film strength. Furthermore, niobium pentoxide (Nb₂O₅) is the best material because it is not absorbed in the visible light region.

[0128] Regardless of the compound, the refractive index can be altered to some extent by controlling the ratio of constituent elements that deviates from the stoichiometric composition ratio, or by controlling the film density during film formation. The materials constituting the low-reflectivity layer and the high-reflectivity layer are not limited to the aforementioned compounds, as long as they meet the above-mentioned refractive index conditions. Furthermore, unavoidable impurities may also be present.

[0129] An antireflective film may have a hard coating layer between the substrate film and the antireflective layer. By providing a hard coating layer, the mechanical properties of the antireflective layer, such as hardness or modulus of elasticity, can be improved. The hard coating layer is preferably characterized by high surface hardness and excellent scratch resistance. For example, the hard coating layer can be formed by coating the substrate film with a solution containing a curable resin.

[0130] Examples of curable resins include: thermosetting resins, UV-curing resins, and electron beam curing resins. Types of curable resins include: polyester resins, acrylic resins, ethyl carbamate resins, ethyl carbamate acrylate resins, amide resins, polysiloxane resins, silicone resins, epoxy resins, melamine resins, oxycarbonate resins, and various other resins. One or more of these curable resins can be appropriately selected for use.

[0131] Among these, acrylic resins, ethyl aminocarbamate resins, and epoxy resins are preferred due to their high hardness, UV curability, and excellent manufacturability, with ethyl aminocarbamate resins being the most preferred. UV-curable resins contain UV-curable monomers, oligomers, polymers, etc. Suitable UV-curable resins include those with UV-polymerizable functional groups, such as those containing two or more of these functional groups, particularly acrylic monomers or oligomers containing three to six of these functional groups.

[0132] To ensure the anti-glare and anti-flicker properties of the anti-reflective film, the hard coating layer applied to the surface of the substrate film preferably possesses anti-glare properties. Examples of anti-glare hard coating layers include those in which microparticles are dispersed within the aforementioned curable resin matrix. The microparticles dispersed in the resin matrix can be any transparent material, such as microparticles of various metal oxides (e.g., silicon dioxide, aluminum oxide, titanium dioxide, zirconium oxide, calcium oxide, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc.); glass microparticles; cross-linked or uncross-linked organic microparticles composed of various transparent polymers such as polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate, etc.; or polysiloxane microparticles. There are no particular restrictions on the use of such microparticles. One or more types of these microparticles can be appropriately selected. Preferably, microparticles with a refractive index higher than that of the matrix resin, such as styrene beads (refractive index 1.59) or other organic microparticles with a refractive index of 1.5 or higher. The average particle size of the microparticles is preferably 1 to 10 μm, more preferably 2 to 5 μm. There is no particular limitation on the ratio of microparticles, but it is preferably 6 to 20 parts by weight relative to 100 parts by weight of the matrix resin.

[0133] A hard coating can be formed, for example, by coating a substrate film with a solution containing a curing resin. Preferably, the solution used to form the hard coating contains an ultraviolet polymerization initiator. To form an anti-glare hard coating containing microparticles, it is preferable to coat a transparent film with a solution containing the aforementioned microparticles in addition to the curing resin. The solution may contain additives such as leveling agents, thixotropic anti-tack agents, and antistatic agents. In the formation of the anti-glare hard coating, by containing thixotropic anti-tack agents (such as silica or mica with a particle size of less than 0.1 μm) in the solution, a fine textured surface formed by protruding particles can be easily formed on the surface of the hard coating.

[0134] The thickness of the hard coating is not particularly limited, but to achieve high hardness, it is preferably 0.5 μm or more, more preferably 1 μm or more. Considering the ease of coating formation, the thickness of the hard coating is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less. In addition, in order to maintain high moisture permeability of the film substrate without hindering the release of moisture from the polarizing element to the outside, the thickness of the hard coating is preferably also within the above-mentioned range.

[0135] The arithmetic mean roughness Ra of the surface on the formation side of the antireflective layer of the substrate film is preferably 1.5 nm or less, more preferably 1.0 nm or less. The arithmetic mean roughness Ra can be 0.00 nm or more, or 0.05 nm or more. When a hard coating is formed on the substrate film, the arithmetic mean roughness of the hard coating becomes the arithmetic mean roughness of the surface on the formation side of the antireflective layer of the substrate film. The arithmetic mean roughness Ra is obtained using atomic force microscopy (AFM) from an observation image of 1 μm square.

[0136] As mentioned above, if a hard coating is formed by coating, the arithmetic mean roughness of the substrate film surface can be reduced. If the surface of the substrate film is smooth, the arithmetic mean roughness of the antireflective layer surface formed on it will also be smaller, thus tending to improve the scratch resistance of the antireflective film.

[0137] <Protective film>

[0138] There are no particular limitations on the protective film, but it is preferably made of a material with excellent transparency, mechanical strength, thermal stability, moisture shielding, and phase difference stability. The material of the protective film is not particularly limited, and examples include films made of methyl methacrylate resins, polyolefin resins, cyclic olefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile-butadiene-styrene resins, acrylonitrile-styrene resins, polyvinyl acetate resins, polyvinyl chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyurethane resins, polyether ether resins, polyarylate resins, polyamide-imide resins, and polyimide resins.

[0139] These resins can be used alone or in combination of two or more. Furthermore, these resins can also be used after being modified by any suitable polymer, such modification including, for example, copolymerization, crosslinking, molecular end modification, stereoregularity control, and mixing modification in cases involving reactions between different types of polymers.

[0140] Cellulose resins can be organic esters or mixed organic esters of cellulose in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are replaced by acetyl, propionic, and / or butyryl groups. Examples include those composed of cellulose acetate, propionate, butyrate, and mixed esters thereof. Among these, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, and cellulose acetate butyrate are preferred.

[0141] Without compromising transparency, these resins may be formulated with appropriate additives. Examples of additives include: antioxidants, UV absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, anti-caking agents, phase difference reducers, stabilizers, processing aids, plasticizers, impact-resistant additives, matting agents, antibacterial agents, and mildew inhibitors. Multiple additives may also be used in combination.

[0142] The thickness of the protective film is typically 1 to 100 μm, but from the viewpoint of strength or processability, it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and even more preferably 15 to 50 μm.

[0143] The protective film can also have other optical functions and can be formed on a multilayered structure. From an optical point of view, the protective film is preferably thin, but if it is too thin, the strength will decrease and the processability will deteriorate. The appropriate film thickness is 5 to 100 μm, preferably 10 to 80 μm, and even more preferably 15 to 70 μm.

[0144] When the polarizing element has a protective film on both sides, and when using a water-based adhesive such as PVA adhesive for bonding, in terms of moisture permeability, the protective film on at least one side is preferably either a cellulose ester membrane or a (meth)acrylic polymer membrane, with the cellulose ester membrane being more preferred.

[0145] The first protective film and the second protective film may be the same or different. The first and second protective films may have a surface treatment layer (coating layer) such as an antistatic layer on their outer surfaces (the side opposite to the polarizing element). The thickness of the first and second protective films includes the thickness of the surface treatment layer.

[0146] To meet the above requirement (ii), the first protective film may be a protective film with a permeability of 300 g / m².day or less at a temperature of 40°C and a relative humidity of 90%. The permeability of the protective film can be adjusted by means of materials, thickness, etc. Protective films with a permeability of 300 g / m².day or less at a temperature of 40°C and a relative humidity of 90% are suitable for use with cyclic olefin resin films, films with water vapor barrier layers laminated in a dry manner, etc.

[0147] On the other hand, when the antireflective film meets the above requirement (i) and the moisture permeability at a temperature of 40°C and a relative humidity of 90% is less than 100 g / m2.day, the moisture permeability of the second protective film at a temperature of 40°C and a relative humidity of 90% is preferably more than 200 g / m2.day.

[0148] When manufacturing optical laminates, as described later, after the second protective film is bonded to the polarizing element 10 using a water-based adhesive or other bonding agent (adhesive or mordant), a drying process is sometimes used to form a bonding layer, followed by the bonding of the first protective film. In this case, by setting the moisture permeability of the protective film deposited on the retardation film side of the polarizing element to the range described above, the moisture contained in the bonding agent can be easily removed by the drying process.

[0149] For purposes such as viewing angle compensation, at least one of the protective films can have a phase difference function. In this case, the film itself can have a phase difference function, can have a phase difference layer, or can be a combination of the two.

[0150] The film with phase difference function can also be formed by bonding other protective films attached to the polarizing element in between, in between an adhesive layer or a bonding agent layer.

[0151] <Adhesive Layer>

[0152] In optical laminates, bonding layers are used to bond the various layers together. Bonding layers can be exemplified as adhesive layers or adhesive layers.

[0153] (Adhesive layer)

[0154] The adhesive layer can be used, for example, in the bonding of the protective film to the polarizing element. Any suitable adhesive can be used to form the adhesive layer. Water-based adhesives, solvent-based adhesives, and active energy line curing adhesives can be used, with water-based adhesives being preferred.

[0155] The thickness of the adhesive coating can be set to any suitable value. For example, it can be set in a way that yields an adhesive layer of the desired thickness after curing or heating (drying). The thickness of the adhesive layer is preferably 0.01 μm to 7 μm, more preferably 0.01 μm to 5 μm, even more preferably 0.01 μm to 2 μm, and most preferably 0.01 μm to 1 μm.

[0156] (Water-based adhesive)

[0157] Any suitable water-based adhesive can be used. Preferably, a water-based adhesive containing PVA-based resin (PVA-based adhesive) is used. From an adhesion perspective, the average degree of polymerization of the PVA-based resin in the water-based adhesive is preferably 100 to 5500, more preferably 1000 to 4500. From an adhesion perspective, the average degree of saponification is preferably around 85 mol% to 100 mol%, more preferably 90 mol% to 100 mol.

[0158] The PVA-based resin contained in the aforementioned water-based adhesive is preferably one containing acetyl acetyl groups, because the PVA-based resin layer exhibits excellent adhesion and durability to the protective film. PVA-based resins containing acetyl acetyl groups can be obtained, for example, by reacting a PVA-based resin with diketene using any method. The degree of acetyl acetyl group modification in PVA-based resins containing acetyl acetyl groups is typically 0.1 mol% or more, preferably 0.1 mol% to 20 mol%.

[0159] The resin concentration of the above-mentioned water-based adhesive is preferably from 0.1% to 15% by mass, and more preferably from 0.5% to 10% by mass.

[0160] Water-based adhesives may also contain crosslinking agents. Commonly known crosslinking agents can be used. Examples include water-soluble epoxy compounds, dialdehydes, and isocyanates.

[0161] When the PVA resin is a PVA resin containing acetyl groups, the crosslinking agent is preferably any one of glyoxal, glyoxylate, or hydroxymethyl melamine, more preferably any one of glyoxal and glyoxylate, and most preferably glyoxal.

[0162] Aqueous adhesives may also contain organic solvents. In terms of miscibility with water, alcohols are preferred organic solvents, with methanol or ethanol being more preferred among alcohols. Some urea compounds have low solubility in water, but are sufficiently soluble in alcohols. In this case, dissolving the urea compound in alcohol to prepare an alcoholic solution, and then adding this alcoholic solution to the PVA aqueous solution to prepare the adhesive, is also a preferred approach.

[0163] The methanol concentration in the aqueous adhesive is preferably 10% by mass or more and 70% by mass, more preferably 15% by mass or more and 60% by mass, and even more preferably 20% by mass or more and 60% by mass. By making the methanol concentration 10% by mass or more, it is easier to suppress polyene formation under high-temperature conditions. In addition, by making the methanol content 70% by mass or less, color deterioration can be suppressed.

[0164] (Active Energy Line Curing Adhesive)

[0165] Active energy line curing adhesives are adhesives that cure by irradiation with active energy lines such as ultraviolet light. Examples include adhesives containing polymerizable compounds and photopolymerization initiators, adhesives containing photoreactive resins, and adhesive resins containing photoreactive crosslinking agents. Examples of polymerizable compounds include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable ethyl carbamate monomers, as well as oligomers derived from these monomers. Examples of photopolymerization initiators include compounds containing active species that generate neutral free radicals, anionic free radicals, and cationic free radicals when irradiated with active energy lines such as ultraviolet light.

[0166] (Adhesive layer)

[0167] An adhesive layer can be used, for example, in the bonding of an antireflective film to a first protective film.

[0168] The adhesive layer can be constructed using an adhesive composition primarily composed of resins such as (meth)acrylic resins, rubber resins, ethyl carbamate resins, ester resins, polysiloxane resins, and polyvinyl ether resins. Preferably, the adhesive composition uses (meth)acrylic resins, which offer excellent transparency, weather resistance, and heat resistance, as the base polymer. The adhesive composition can be either energy-curing or thermosetting. The thickness of the adhesive layer is typically 3 to 30 μm, preferably 3 to 25 μm.

[0169] The (meth)acrylic resin (base polymer) used in the adhesive composition is suitable as a polymer or copolymer with one or more (meth)acrylic esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. In the base polymer, it is preferable to copolymerize polar monomers. Examples of polar monomers include: (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate, which are monomers having carboxyl, hydroxyl, amide, amino, or epoxy groups.

[0170] The adhesive composition may contain only the aforementioned basic polymer, but usually also includes a crosslinking agent. Examples of crosslinking agents include: divalent or higher metal ions that form carboxylic acid metal salts with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; polyepoxide compounds or polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Polyisocyanate compounds are preferred.

[0171] The storage modulus of the adhesive layer is preferably 0.001 to 0.350 MPa, more preferably 0.001 to 0.200 MPa, even more preferably 0.001 to 0.180 MPa, and particularly preferably 0.010 to 0.170 MPa at a frequency of 1 Hz and a temperature of 23°C. The storage modulus of the adhesive layer can be determined according to the method described in the examples below.

[0172] The thickness of the adhesive layer is preferably 1 to 200 μm, more preferably 2 to 100 μm, even more preferably 2 to 80 μm, and particularly preferably 3 to 50 μm.

[0173] In this invention, as described above, by using sputtering to form the antireflective film of each layer, an optical laminate with high scratch resistance can be constructed.

[0174] In this case, by controlling the storage modulus of the adhesive layer used to bond the antireflective film to the first protective film and the thickness of the adhesive layer within the following ranges, an optical laminate with high indentation hardness, represented by pencil hardness, and with an antireflective layer that is not easily broken can be formed, which is therefore particularly desirable.

[0175] In particular, the storage modulus of the adhesive layer used to bond the first protective film and the antireflective film is preferably 0.050 to 0.170 MPa, more preferably 0.080 to 0.170 MPa, even more preferably 0.100 to 0.170 MPa, and especially preferably 0.120 to 0.160 MPa.

[0176] The thickness of the adhesive layer is preferably 3 to 30 μm, more preferably 3 to 20 μm, even more preferably 3 to 10 μm, and particularly preferably 3 to 8 μm.

[0177] [Manufacturing method of optical laminates]

[0178] The manufacturing method of the optical laminate of this embodiment includes a moisture content adjustment step. In the moisture content adjustment step, when manufacturing the optical laminate having characteristic (a), the moisture content of the polarizing element is adjusted to be above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity. The method for adjusting the moisture content of the polarizing element is as described above. In the moisture content adjustment step, when manufacturing the optical laminate having characteristic (b), the moisture content of the optical laminate is adjusted to be above the equilibrium moisture content at 20°C and 20% relative humidity, and below the equilibrium moisture content at 20°C and 48% relative humidity. The method for adjusting the moisture content of the optical laminate is as described above.

[0179] Other than the moisture content adjustment step, the steps may include: stacking polarizing elements and protective films to obtain a polarizing plate, stacking a polarizing plate and an anti-reflection film, stacking a polarizing plate and a phase retardation film, and other stacking steps for each layer. The moisture content adjustment step and the order of the stacking steps are not limited, and the moisture content adjustment step and the stacking steps can be performed simultaneously.

[0180] [Display device]

[0181] The aforementioned optical multilayer system can be used in various display devices such as liquid crystal displays or organic EL displays. Display devices using the optical multilayer of this embodiment exhibit excellent resistance to damp heat and high temperatures. Because of the excellent damp heat and high temperature resistance of display devices using the optical multilayer of this embodiment, they are suitable for use in automotive display devices.

[0182] The display device includes a display unit and an optical laminate deposited on the viewing side surface of the display unit. The optical laminate is deposited on the viewing side surface of the display unit in an orientation from the display unit side, arranged in the order of a retardation film, a polarizing element, and an anti-reflection film. The deposition of the display unit and the optical laminate uses, for example, the aforementioned adhesive layer.

[0183] <Display Unit>

[0184] Display units can include liquid crystal units (LCDs) or organic EL units (OLEDs). The liquid crystal unit can be any of the following: a reflective liquid crystal unit that uses external light, a transmissive liquid crystal unit that uses light from a light source such as a backlight, or a semi-transmissive / semi-reflective liquid crystal unit that uses both external light and light from a light source. When the liquid crystal unit uses light from a light source, the display device (liquid crystal display device) also has a polarizing plate on the side opposite to the viewing side of the display unit (liquid crystal unit), and further includes a light source. The polarizing plate on the light source side and the liquid crystal unit are preferably bonded together with a suitable adhesive layer. The driving method of the liquid crystal unit can be, for example, any type such as VA mode, IPS mode, TN mode, STN mode, or bent alignment (π type).

[0185] Organic EL units preferably use a method where a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially deposited on a transparent substrate to form a light-emitting body (organic electroluminescent body). The organic light-emitting layer is a stack of various organic thin films, and can be, for example, a stack of a hole injection layer composed of a triphenylamine derivative and a light-emitting layer composed of a fluorescent organic solid such as anthracene; or a stack of such a light-emitting layer and an electron injection layer composed of a perylene derivative; or a stack of a hole injection layer, a light-emitting layer, and an electron injection layer, etc.

[0186] [Example]

[0187] The present invention is specifically described below with reference to examples, but the invention is not limited to these examples. In the examples, parts or percentages of content or dosage are used, and unless otherwise specified, they are mass standards. The determination of each physical property in the following examples was performed by the following methods.

[0188] [Determination Method]

[0189] (1) Method for measuring film thickness:

[0190] The measurements were performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

[0191] (2) Moisture permeability of the antireflective film

[0192] According to Appendix B of JIS K7129:2008, the moisture permeability of the antireflective film was measured in an environment with a temperature of 40℃ and a relative humidity of 90%.

[0193] (3) Determination of the thickness of each layer of the anti-reflective layer

[0194] The measurements were performed using a reflective spectrophotometer FE3000 manufactured by Otsuka Electronics Co., Ltd.

[0195] (4) Tensile modulus at 23°C (measured according to JIS K 7161)

[0196] Test pieces with a width of 15 mm and a length of 150 mm, parallel to the slow axis and fast axis respectively, were cut from the membrane. The test pieces were then clamped at both ends along their long sides using the upper and lower clamps of a tension testing machine [Shimadzu Corporation AUTOGRAPH AG-1S testing machine (registered trademark)]. The test pieces were stretched at 50 mm / min at 23°C, and stress-strain curves were generated. Based on the stress-strain curves, the tensile modulus at 23°C in the directions parallel to the slow axis and fast axis was calculated. The larger of the calculated tensile modulus values ​​in the directions parallel to the slow axis and fast axis was designated as the tensile modulus value of this invention at 23°C.

[0197] (5) Storage Modulus

[0198] The storage modulus G' of the adhesive layer is determined according to the following (I) to (III).

[0199] (I) Take out two 25±1mg samples from the adhesive layer and shape them into approximately spherical shapes.

[0200] (II) The obtained approximately spherical sample is attached to the upper and lower surfaces of the type I fixture, and both surfaces are clamped by the type L fixture. The composition of the test sample is: type L fixture / adhesive layer / type I fixture / adhesive layer / type L fixture.

[0201] (III) The storage modulus G' of the sample prepared in this manner was determined using the dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement Control Co., Ltd., at a temperature of 23°C, a frequency of 1Hz, and an initial strain of 1N.

[0202] (A) Fabrication of polarizing elements

[0203] Preparation: A 75 μm thick polyvinyl alcohol (PVA) film composed of PVA with an average degree of polymerization of approximately 2,400 and a saponification degree of 99.9 mol% or higher was prepared. The PVA film was uniaxially stretched approximately 5 times using a dry method, and then immersed in pure water at 60°C for 1 minute while under tension. Next, the PVA film was immersed in an aqueous solution at 28°C with a weight ratio of iodine / potassium iodide / water of 0.05 / 5 / 100 for 60 seconds. Then, the PVA film was immersed in an aqueous solution at 72°C with a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 for 300 seconds. Finally, the PVA film was washed with pure water at 26°C for 20 seconds and dried at 65°C. This yielded a 28 μm thick polarizing element with iodine adsorption and alignment to PVA.

[0204] (B) Adhesive preparation

[0205] 50g of a modified PVA resin containing acetyl groups (manufactured by Mitsubishi Chemical Co., Ltd.: Gohsenx Z-410) was dissolved in 950g of pure water, heated at 90°C for 2 hours, and then cooled to room temperature to obtain PVA solution A.

[0206] The PVA-based adhesive was prepared by mixing the aforementioned PVA solution, maleic acid, glyoxal, and pure water in such a manner that the compounds were prepared to the following concentrations.

[0207]

[0208]

[0209] (C) Saponification of cellulose ester membranes

[0210] The prepared material is a commercially available cellulose ester membrane, TD40 (manufactured by FUJIFILM Co., Ltd.: membrane thickness 40μm). The membrane is immersed in a 1.5mol / L NaOH aqueous solution (saponification solution) maintained at 55°C for 2 minutes, followed by washing with water. Next, the membrane is immersed in a 0.05mol / L sulfuric acid aqueous solution at 25°C for 30 seconds, and then passed under running water for 30 seconds to neutralize the membrane. This process is repeated three times using an air knife to drain the water. Finally, the membrane is dried in a 70°C drying zone for 15 seconds, thus producing a saponified membrane.

[0211] The moisture permeability of the saponified membrane at 40°C and 90% relative humidity is 850 g / m².day.

[0212] (D) Fabrication of the stack of retardation film and retardation layer

[0213] The process follows paragraphs

[0106] to

[0109] of International Publication No. 2018 / 207798. A cyclic olefin polymer film (manufactured by JSR Corporation, trade name Arton Film) was uniaxially stretched to produce a cyclic olefin polymer film (tensile modulus at 23°C = 2742 MPa, in-plane phase difference Re = 110 nm at 550 nm, thickness phase difference Rth = 55 nm at 550 nm, film thickness 24 μm). A composition containing a rod-shaped liquid crystal compound was coated onto this cyclic olefin polymer film (phase difference film) to form a phase difference layer belonging to the positive C layer (in-plane phase difference Re = 0 nm at 550 nm, thickness phase difference Rth = -100 nm at 550 nm).

[0214] (E) Fabrication of optical laminates

[0215] (Fabrication of Polarizing Plate 1)

[0216] To ensure that the absorption axis of the polarizing element is parallel to the slow axis of the retardation film, a PVA-based adhesive is used to bond the aforementioned laminate of the retardation film and retardation layer, the polarizing element, and the saponified cellulose ester membrane (first protective film). In this case, the laminate of the retardation film and retardation layer (positive C layer) is bonded with the retardation layer (positive C layer) side facing the polarizing element side. The adhesion between the retardation film and the polarizing element, as well as the adhesion between the cellulose ester membrane and the polarizing element, is practically sufficient.

[0217] (Determination of equilibrium moisture content)

[0218] The polarizing plate 1 obtained above was stored for 72 hours at a temperature of 20°C and relative humidity of 30%, 35%, 40%, 45%, or 50%. The moisture content was measured using the Karl Fischer method after 66, 69, and 72 hours of storage. Regardless of the humidity conditions, the moisture content remained unchanged after 66, 69, and 72 hours. Therefore, the moisture content of polarizing plate 1 can be considered to be the same as the equilibrium moisture content of the storage environment. When the moisture content of the polarizing plate reaches equilibrium at a certain storage temperature, the moisture content of the polarizing elements in the polarizing plate is also the same, and can be considered to have reached equilibrium at that storage temperature. Furthermore, when the moisture content of the polarizing elements in the polarizing plate reaches equilibrium under a certain storage environment, the moisture content of the polarizing plate is also the same, and can be considered to have reached equilibrium under that storage environment.

[0219] The moisture content of the obtained polarizing plate 1 shortly after drying was determined by the Karl Fischer method and compared with the equilibrium moisture content. The moisture content of polarizing plate 1 was the same as that at a temperature of 20°C and a relative humidity of 40%. Polarizing plate 1 was further stored at a temperature of 20°C and a relative humidity of 40% for 72 hours.

[0220] (F) Fabrication of anti-reflective coating

[0221] (Preparation of anti-glare hard coating)

[0222] A solution containing 50 parts by weight of UV-curable ethyl carbamate acrylate monomers (refractive index 1.51), 50 parts by weight of UV-curable acrylate monomers (refractive index 1.51), 14 parts by weight of methyl methacrylate-styrene copolymer beads with an average particle size of 3.5 μm (refractive index 1.55), 5 parts by weight of benzophenone-based photopolymerization initiator, and 40% by weight of toluene solids was coated onto a 40 μm thick cellulose triacetate film (refractive index 1.49) and dried at 120°C for 5 minutes. Then, it was cured by UV irradiation to form an anti-glare hard coating with a surface texture of approximately 4 μm in thickness, thus creating an anti-glare hard coating film. The arithmetic mean roughness Ra of this anti-glare hard coating is 0.43 nm.

[0223] (Fabrication of antireflective film 1)

[0224] According to the embodiment disclosed in Japanese Patent Application Publication No. 2019-035969, the aforementioned anti-glare hard coating film is introduced into a roll-to-roll sputtering film forming apparatus. While the film is moving, it is subjected to impact treatment (by plasma treatment with Ar gas) on the anti-glare hard coating forming surface. Then, a 5 nm SiOx layer (x<2) serving as an adhesion enhancement layer is formed, and a 20 nm Nb2O5 layer, a 35 nm SiO2 layer, a 35 nm Nb2O5 layer, and a 100 nm SiO2 layer are sequentially formed on top of it to form a 4-layer anti-reflective layer with a thickness of 190 nm. A fluorinated resin serving as an anti-fouling layer is formed on the anti-reflective layer with a thickness of 5 nm to produce an anti-reflective film 1. The anti-reflective film 1 has a moisture permeability of 5 g / m2‧day at a temperature of 40°C and a relative humidity of 90%.

[0225] (Fabrication of antireflective films 2 and 3)

[0226] Referring to the embodiments disclosed in Japanese Patent Application Publication No. 2017-227898, the film-forming conditions were modified to produce antireflective films 2 and 3 with different moisture permeability than antireflective film 1. The moisture permeability of antireflective films 2 and 3 at a temperature of 40°C and a relative humidity of 90% are 10 g / m²·day and 60 g / m²·day, respectively.

[0227] (Fabrication of antireflective film 4)

[0228] Except for replacing the sputtering method with a coating method for the anti-reflective layer, and setting the anti-reflective layer structure as follows, the anti-reflective film 4 is manufactured in the same way as the anti-reflective film 1. The anti-reflective film 4 has a moisture permeability of 300 g / m2‧day at a temperature of 40°C and a relative humidity of 90%.

[0229] Referring to paragraph

[0105] of Japanese Patent Application Publication No. 2004-126220, the anti-reflective layer is formed into an anti-reflective layer consisting of the following three layers.

[0230] The first layer is the refractive index layer (refractive index: 1.63, film thickness: 67nm).

[0231] Second high-refractive-index layer (refractive index: 1.90, film thickness: 107 nm)

[0232] The third low-refractive-index layer (refractive index: 1.43, film thickness: 86 nm)

[0233] (G) Preparation of adhesive layer

[0234] Adhesive layer A: A commercially available sheet of acrylic adhesive with a release agent on both sides, consisting of 38μm PET. The adhesive layer is 5μm thick and has a storage modulus of 0.14MPa.

[0235] Adhesive layer B: A commercially available sheet of acrylic adhesive with a release agent on both sides, consisting of 38μm PET. The adhesive layer is 25μm thick and has a storage modulus of 0.06MPa.

[0236] [Example 1]

[0237] An adhesive layer A is bonded to the surface of the un-laminated antireflective layer of the aforementioned antireflective film 1. During the bonding of these materials, the bonding surfaces of each material are subjected to corona treatment.

[0238] An antireflective film 1 is laminated onto the surface of the cellulose ester film (first protective film) of the polarizing plate 1 as described above, with an adhesive layer A in between, and an adhesive layer B is laminated onto the area layer of the retardation film to form the optical laminate of Example 1. During the lamination of these materials, the lamination surfaces of each material are subjected to corona treatment. The resulting optical laminate is composed of layers of "antireflective film 1 / adhesive layer A / polarizing plate 1 / adhesive layer B / PET with release agent".

[0239] The resulting optical laminate was prepared by storing the polarizing plate for 72 hours under conditions identical to those used for 72-hour storage, ensuring that the moisture content of the polarizing plate was the same as that of the original optical laminate. The optical laminate was also stored for 72 hours, which is considered to indicate that equilibrium had been reached under this storage environment. The moisture content of the polarizing plate and polarizing element within the optical laminate was also considered to have reached equilibrium under this storage environment. Furthermore, when the moisture content of the polarizing plate or polarizing element within the optical laminate reaches equilibrium under a certain storage environment, the moisture content of the optical laminate is also considered to have reached equilibrium under that storage environment. Therefore, the moisture content of the optical laminate is the equilibrium moisture content at a temperature of 20°C and a relative humidity of 40%.

[0240] [Examples 2 to 4]

[0241] In the fabrication of the optical laminate in Example 1, except that the antireflective film 1 is replaced with antireflective films 2 to 4, the optical laminates of Examples 2 to 4 are fabricated in the same manner as in Example 1. Then, the polarizing plate is stored for another 72 hours under the same conditions as the 72-hour storage to adjust the moisture content of the optical laminate.

[0242] [Comparative Example 1]

[0243] The adhesive layer B is bonded to the phase retardation film surface of the polarizing plate 1 to fabricate the optical laminate of Comparative Example 1. During the bonding of these materials, the bonding surfaces of each material are subjected to corona treatment.

[0244] The resulting optical laminate consists of layers of "polarizing plate 1 / adhesive layer B / PET with release agent".

[0245] [Evaluate]

[0246] (Mapping)

[0247] The obtained optical laminate was cut into 200mm × 200mm pieces and bonded to a 300mm × 300mm thick alkali-free glass plate with an adhesive layer B in between. Adhesive layer B was then deposited onto a polarizing plate 1 and cut into 200mm × 200mm pieces so that the absorption axes of the polarizing plates were orthogonally polarized. The polarizing plate 1 was then bonded to the side of the alkali-free glass plate that was not bonded to the optical laminate, with the adhesive layer B in between, to create an evaluation sample.

[0248] To make the anti-reflective film the viewing side, the evaluation sample prepared above was placed on the observation stage and illuminated at an angle by a fluorescent lamp on the table. The reflection in the mirror direction relative to the illumination direction was evaluated using the following criteria. The evaluation results are presented in Table 1.

[0249] A: I didn't see any reflection of the fluorescent light at all.

[0250] B: Almost no reflection of fluorescent lights was visible.

[0251] C: I can see a slight reflection of the fluorescent light.

[0252] D: The reflection of the fluorescent light is clearly visible.

[0253] (Assessment of cracks)

[0254] The evaluation samples prepared above were stored at a heating environment of 105°C for 500 hours, and then cooled to 23°C (room temperature). They were then stored at 23°C and 55% relative humidity for 30 days (1 month), and the phase retardation film was visually inspected to check for cracking. Furthermore, the phase retardation film was visually inspected every 30 days to check for cracking. The results are presented in Table 1.

[0255] [Table 1]

[0256]

[0257] 10: Polarizing element

[0258] 11: First protective film

[0259] 20: Anti-reflective film

[0260] 30: Phase retardation film

[0261] 100: Optical laminate

Claims

1. An optical laminate comprising, in sequence, a retardation film, a polarizing element, and an antireflective film, wherein the retardation film has a tensile modulus of 3000 MPa or less at 23°C, the in-plane phase difference of the retardation film at a wavelength of 550 nm is 80 nm or more and 300 nm or less, the polarizing element has a water content of at least the equilibrium water content at 20°C and 20% relative humidity, and is less than the equilibrium water content at 20°C and 48% relative humidity, the antireflective film comprises a substrate film and an antireflective layer disposed on the surface of the substrate film, and the substrate film is composed of a cellulose-based resin; and satisfies at least one of the following requirements (i) and (ii): (i) the antireflective film has a moisture permeability of 300 g / m² at 40°C and 90% relative humidity. (ii) Between the aforementioned polarizing element and the aforementioned antireflective film, there is a protective film with a permeability of 300 g / m2 at a temperature of 40°C and a relative humidity of 90%.

2. An optical laminate comprising, in sequence, a retardation film, a polarizing element, and an antireflective film, wherein the retardation film has a tensile modulus of 3000 MPa or less at 23°C, the in-plane phase difference of the retardation film at a wavelength of 550 nm is 80 nm or more and 300 nm or less, the moisture content of the optical laminate is greater than or equal to the equilibrium moisture content at 20°C and 20% relative humidity, and less than or equal to the equilibrium moisture content at 20°C and 48% relative humidity, the antireflective film comprising a substrate film and an antireflective layer disposed on the surface of the substrate film, and the substrate film being composed of a cellulose-based resin; and satisfying at least one of the following requirements (i) and (ii): (i) the moisture permeability of the antireflective film at 40°C and 90% relative humidity is 300 g / m². (ii) Between the aforementioned polarizing element and the aforementioned antireflective film, there is a protective film with a permeability of 300 g / m2 at a temperature of 40°C and a relative humidity of 90%.

3. The optical laminate as claimed in claim 1 or 2, wherein a protective film is provided between the aforementioned polarizing element and the aforementioned antireflective film.

4. The optical laminate as claimed in claim 1 or 2, wherein the aforementioned retardation film is composed of a cyclic olefin resin.

5. An optical laminate as described in claim 1 or 2, wherein the aforementioned antireflective layer is composed of multiple thin films with different refractive indices.

6. The optical laminate as claimed in claim 5, wherein the aforementioned antireflective layer comprises a thin film primarily composed of silicon dioxide (SiO2).

7. The optical laminate of claim 5, wherein the aforementioned antireflective layer comprises a thin film mainly composed of niobium pentoxide (Nb2O5) or titanium dioxide (TiO2).

8. The optical stack as described in claim 5, wherein the thickness of the aforementioned antireflective layer is from 100 nm to 350 nm.

9. The optical laminate as claimed in claim 1 or 2, wherein the aforementioned antireflective film further comprises a hard coating disposed between the aforementioned substrate film and the aforementioned antireflective layer.

10. A display device comprising: a display unit and an optical laminate as described in any one of claims 1 to 9; wherein the optical laminate is deposited on the viewing side surface of the display unit in an orientation arranged from the display unit side in the order of the polarizing element and the antireflective film.

11. A method for manufacturing an optical laminate as described in claim 1, comprising: a moisture content adjustment step of adjusting the moisture content of the aforementioned polarizing element to a level above the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

12. A method for manufacturing an optical laminate as described in claim 2, comprising: a moisture content adjustment step of adjusting the moisture content of the aforementioned optical laminate to a level above the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

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