Optical laminate and display device

Abstract

To provide an optical laminate which has the excellent reflection preventive function and which prevents a crack from being generated in a retardation film even stored for one month in an environment where the temperature is 23°C and the relative humidity is 55% after a heat durability test in a case of using the optical laminate that includes the retardation film adding a function to an image display device.SOLUTION: There is provided an optical laminate having a retardation film, a polarizing element and a reflection preventive film in this order. The retardation film has the tensile modulus of elasticity equal to or less than 3000 MPa at 23°C. The polarizing element has the moisture content equal to or greater than the equilibrium moisture content of the temperature 20°C and the relative humidity 20% and equal to or less than the equilibrium moisture content of the temperature 20°C and the relative humidity 48%. The optical laminate satisfies at least one of the following requirement (i) and the following requirement (ii). (i) The reflection preventive film has the moisture vapor permeability of the temperature 40°C and the relative humidity 90% equal to or less than 300 g / m2 day. (ii) A protective film which has the moisture vapor permeability of the temperature 40°C and the relative humidity 90% equal to or less than 300 g / m2 day is provided between the polarizing element and the reflection preventive film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical laminate, a display device, and a method for producing an optical laminate. [Background technology]

[0002] Liquid crystal display devices (LCDs) are widely used not only in liquid crystal televisions, but also in personal computers, mobile devices such as mobile phones, and in-vehicle applications such as car navigation systems. Typically, liquid crystal display devices have a liquid crystal panel member in which polarizing plates are attached to both sides of a liquid crystal cell with an adhesive, and display is performed by controlling light from a backlight member with the liquid crystal panel member. In addition, organic electroluminescence (EL) display devices have also been widely used in recent years in mobile devices such as televisions and mobile phones, and in-vehicle applications such as car navigation systems, similar to liquid crystal display devices. In liquid crystal display devices and organic EL display devices, retardation films are used to provide functions such as widening the viewing angle and preventing reflection of external light.

[0003] As mentioned above, polarizing plates are increasingly being installed in vehicles as components of liquid crystal display devices and organic electroluminescence display devices. Polarizing plates used in vehicle-mounted image display devices are more often exposed to high-temperature environments than those used in other mobile applications such as televisions and mobile phones, and are therefore required to have small changes in properties at high temperatures (high-temperature durability).

[0004] On the other hand, in-vehicle display devices need to have a touch panel function when used for car navigation systems, etc. In recent years, the ratio of on-cell and in-cell touch panels has been increasing, and in these applications, the polarizing plate on the viewing side is placed on the outermost side, so in addition to the durability mentioned above, an anti-glare function is also required.

[0005] Japanese Patent Application Laid-Open No. 2011-081219 (Patent Document 1) discloses the use of an antiglare hard-coated film in which a multi-layered antireflection layer formed by a sputtering method is laminated on an antiglare layer for the purpose of preventing reflection of external light (Example 1, etc.).

[0006] Patent Document 2 describes a polarizing plate including a retardation film using a cyclic olefin resin for the purpose of expanding the viewing angle, while Patent Document 3 describes a polarizing plate including a retardation film using a cyclic olefin resin as a λ / 4 plate for the purpose of preventing reflection of external light.

[0007] Such polarizing plates have good visibility after being laminated to a display device, and even though no cracks were observed after a heat durability test (500 hours at 105°C), it was found that cracks may occur in the retardation film if the plate is stored in an environment of 23°C and 55% relative humidity for about one month. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-081219 A [Patent Document 2] Patent No. 5383594 [Patent Document 3] JP 2014-194483 A Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to solve the above problems, and to provide an optical laminate including a retardation film that adds a function to an image display device, which has a good anti-glare function, and which has no cracks on the retardation film even when stored for one month in an environment of 23°C and 55% relative humidity after a heat durability test. The object of the present invention is to provide an optical laminate in which no cracks occur. [Means for solving the problem]

[0010] The present invention provides the following optical laminate, display device, and method for producing the optical laminate. [1] An optical laminate having a retardation film, a polarizing element, and an antireflection film in this order, The retardation film has a tensile modulus of elasticity at 23° C. of 3000 MPa or less, The polarizing element has a moisture content equal to or greater than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or less than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%; The following requirement (i) and the following requirement (ii): (i) The anti-reflection film has a moisture permeability of 300 g / m at a temperature of 40° C. and a relative humidity of 90%. 2 ·day or less, (ii) Between the polarizing element and the antireflection film, the moisture permeability at a temperature of 40° C. and a relative humidity of 90% is 300 g / m 2 ·Having a protective film that is below day An optical laminate that satisfies at least one of the above. [2] An optical laminate having a retardation film, a polarizing element, and an antireflection film in this order, The retardation film has a tensile modulus of elasticity at 23° C. of 3000 MPa or less, The optical laminate has a moisture content equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%, The following requirement (i) and the following requirement (ii): (i) The anti-reflection film has a moisture permeability of 300 g / m at a temperature of 40° C. and a relative humidity of 90%. 2 ·day or less, (ii) Between the polarizing element and the antireflection film, the moisture permeability at a temperature of 40° C. and a relative humidity of 90% is 300 g / m 2 ·Having a protective film that is below day An optical laminate that satisfies at least one of the above. [3] The optical laminate according to [1] or [2], further comprising a protective film between the polarizing element and the antireflection film. [4] The polarizing plate according to any one of [1] to [3], wherein the retardation film is made of a cyclic olefin resin. [5] The polarizing plate according to any one of [1] to [4], wherein the retardation film has an in-plane retardation value of 80 nm or more at a wavelength of 550 nm. [6] The antireflection film includes a substrate film and an antireflection layer provided on a surface of the substrate film, The optical laminate according to any one of [1] to [5], wherein the antireflection layer is made of a plurality of thin films having different refractive indices. [7] The optical laminate described in [6], wherein the antireflection layer includes a thin film mainly composed of silicon dioxide (SiO2). [8] The optical laminate according to [6] or [7], wherein the antireflection layer comprises a thin film mainly composed of niobium pentoxide (Nb2O5) or titanium dioxide (TiO2). [9] The optical laminate according to any one of [6] to [8], wherein the antireflection layer has a thickness of 100 nm to 350 nm.

[10] The optical laminate according to any one of [6] to [9], wherein the antireflection film further has a hard coat layer provided between the base film and the antireflection layer.

[11] A display cell and the optical laminate according to any one of [1] to

[10] , A display device, wherein the optical laminate is laminated on a viewing side surface of the display cell in an orientation in which the polarizing element and the anti-reflection film are disposed in this order from the display cell side.

[12] A method for producing the optical laminate according to [1], A method for producing an optical laminate, comprising a moisture content adjusting step of adjusting the moisture content of the polarizing element so that it is equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

[13] A method for producing the optical laminate according to [2], A method for producing an optical laminate, comprising a moisture content adjusting step of adjusting the moisture content of the optical laminate to be equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%. Effect of the Invention

[0011] The present invention provides an optical laminate that has a good anti-glare function even when an optical laminate including a retardation film that adds a function to an image display device is used, and that does not cause cracks in the retardation film even when stored for one month in an environment at a temperature of 23°C and a relative humidity of 55% after a heat durability test. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is an example of a schematic cross-sectional view showing a layer structure of an optical laminate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Optical laminate] The optical laminate according to the embodiment of the present invention has a retardation film, a polarizing element, and an anti-reflection film in this order. The anti-reflection film is disposed on the viewing side surface of the polarizing element. The retardation film is disposed on the surface opposite to the viewing side surface of the polarizing element. The optical laminate may have a protective film (hereinafter also referred to as "first protective film") laminated on the anti-reflection film side surface of the polarizing element, or may have a protective film (hereinafter also referred to as "second protective film") laminated on the surface opposite to the anti-reflection film side of the polarizing element. In this specification, the first protective film is a protective film laminated between the polarizing element and the anti-reflection film, and the second protective film is a protective film laminated between the polarizing element and the retardation film. In addition, in this specification, the polarizing plate refers to a laminate including a polarizing element and, when the first protective film and / or the second protective film are attached to the polarizing element, the laminate also includes these.

[0014] 1 is a schematic cross-sectional view showing an example of the layer structure of the optical laminate according to the present embodiment. The optical laminate 100 includes a retardation film 30, a polarizing element 10, and an antireflection film 20, and further includes a first protective film 11 laminated on the surface of the polarizing element 10 on the antireflection film 20 side.

[0015] The optical laminate according to this embodiment has at least one of the following characteristics (a) and (b). (a) The moisture content of the polarizing element is equal to or greater than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and is equal to or less than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%. (b) The moisture content of the optical laminate is equal to or greater than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or less than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%. Regarding (a) above, the moisture content of the polarizing element is preferably equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 30% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 45%. The moisture content of the polarizing element is more preferably equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 30% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 40%. Regarding the above (b), the moisture content of the optical laminate is preferably equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 30%, and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 45%. The moisture content of the optical laminate is more preferably equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 30%, and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 40%.

[0016] The optical layered body satisfies at least one of the following requirement (i) and the following requirement (ii). (i) The anti-reflection film has a moisture permeability of 300 g / m at a temperature of 40°C and a relative humidity of 90%. 2 ·day or less. (ii) Between the polarizing element and the anti-reflection film, the moisture permeability is 300 g / m at a temperature of 40°C and a relative humidity of 90%. 2 ·Has a protective film which is less than 1 day. Satisfying the above requirement (ii) is equivalent to satisfying the following requirement (iia). (iia) A film laminated on the surface of the anti-reflection film side of a polarizing element, the moisture permeability of which is 300 g / m at a temperature of 40°C and a relative humidity of 90%. 2 ·Having a first protective film that is less than day.

[0017] In the optical laminate of this embodiment, the moisture content of the polarizing element is within the above range, and at least one of the requirements (i) and (ii) is satisfied, so that no cracks (cracks) occur in the retardation film after a heat durability test (105°C for 500 hours), and furthermore, even when stored for about one month in an environment at a temperature of 23°C and a relative humidity of 55%, the occurrence of cracks in the retardation film can be suppressed. Although the detailed mechanism is unclear, it is believed that this is because the moisture permeability of the antireflection film and the first protective film is set within a predetermined range, which suppresses moisture transfer to the polarizing element and suppresses dimensional changes during storage, thereby suppressing the occurrence of cracks in the retardation film.

[0018] <Polarizing element> The polarizing element may be a polarizing element formed by adsorbing and orienting a dichroic dye in a layer containing a polyvinyl alcohol (hereinafter also referred to as "PVA")-based resin (also referred to as a "PVA-based resin layer" in this specification). Examples of such polarizing elements include a polarizing element formed by using a PVA-based resin film, dyeing the PVA-based resin film with a dichroic dye, and uniaxially stretching the film, and a polarizing element formed by using a laminated film obtained by applying a coating liquid containing a PVA-based resin onto a base film, dyeing the PVA-based resin layer, which is the coating layer of the laminated film, with a dichroic dye, and uniaxially stretching the laminated film.

[0019] The polarizing element is made of a PVA resin obtained by saponifying a polyvinyl acetate resin. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers that can be copolymerized with it. Examples of other monomers that can be copolymerized include unsaturated carboxylic acids, olefins such as ethylene, vinyl ethers, and unsaturated sulfonic acids.

[0020] The saponification degree of the PVA resin is preferably about 85 mol% or more, more preferably about 90 mol% or more, and further preferably about 99 mol% to 100 mol%. The polymerization degree of the PVA resin is 1000 to 10000, preferably 1500 to 5000. The PVA resin may be modified, and may be, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc., modified with aldehydes.

[0021] The thickness of the polarizing element of this embodiment is preferably 5 to 50 μm, more preferably 5 to 30 μm, and even more preferably 8 to 25 μm. When the thickness of the polarizing element is 50 μm or less, the influence of polyenation of the PVA resin on the deterioration of optical properties in a high-temperature environment can be suppressed, and when the thickness of the polarizing element is 5 μm or more, it is easy to achieve a configuration that achieves desired optical properties.

[0022] The luminosity-corrected single transmittance of the polarizing element is preferably 38.8% to 44.8%, more preferably 40.4% to 43.2%, and further preferably 40.7% to 43.0%. If the luminosity-corrected single transmittance exceeds 44.8%, the optical properties deteriorate, such as red discoloration in a high-temperature environment. If the luminous efficiency corrected single transmittance is less than 38.8%, polyenation may easily proceed in a high temperature environment, resulting in significant deterioration of the optical properties.

[0023] The luminosity-corrected single transmittance can be determined by measuring the luminosity-corrected Y value using a 2-degree visual field (C light source) as specified in JIS Z8701-1982. The luminosity-corrected single transmittance can be easily measured using, for example, a spectrophotometer (model number: V7100) manufactured by JASCO Corporation.

[0024] (Feature (a)) When the polarizing element has the characteristic (a), the moisture content is equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%. It is preferably equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 30% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 45%. It is more preferably equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 42%, even more preferably equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 40%, and most preferably equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 38%. If the moisture content is lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20%, the polarizing element becomes less easy to handle and more likely to crack. By having the moisture content at or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%, an optical laminate having excellent wet heat durability and high temperature durability can be provided. It is presumed that if the moisture content of the polarizing element is high, the PVA resin contained in the polarizing element is more likely to be polyenated. The moisture content of the polarizing element is the moisture content of the polarizing element in the optical laminate.

[0025] Methods for checking whether the moisture content of a polarizing element is equal to or greater than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48% include storing the polarizing element for a certain period of time in an environment adjusted to the above temperature and relative humidity ranges and checking that there is no change in mass, or calculating in advance the equilibrium moisture content of the polarizing element in an environment adjusted to the above temperature and relative humidity ranges and comparing the moisture content of the polarizing element with the previously calculated equilibrium moisture content. If there is no change in mass after storing the polarizing element for a certain period of time, it can be considered that the moisture content has reached equilibrium in the storage environment.

[0026] Methods for producing a polarizing element having a moisture content equal to or greater than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48% include, but are not limited to, a method in which the polarizing element is stored in an environment adjusted to the above-mentioned temperature and relative humidity range for 10 minutes to 3 hours, or a method in which the polarizing element is heated at 30°C to 90°C.

[0027] Another preferred method for producing a polarizing element having the above moisture content includes a method in which a laminate having a protective film laminated on at least one surface of a polarizing element, or a laminate constructed using a polarizing element, is stored in an environment adjusted to the above temperature and relative humidity ranges for 10 minutes to 120 hours, or a method in which it is heat-treated at 30° C. to 90° C. In the production of an image display device, a method in which an image display panel having an optical laminate laminated on an image display cell is stored in an environment adjusted to the above temperature and relative humidity ranges for 10 minutes to 3 hours, or a method in which it is heat-treated at 30° C. to 90° C. is also included.

[0028] The moisture content of the polarizing element is preferably adjusted to the above numerical range at the material stage used to construct the optical laminate, which is a polarizing element alone or a laminate of a polarizing element and a protective film. If the moisture content is adjusted after the optical laminate is constructed, curling may become too large, which may lead to problems when the optical laminate is attached to an image display cell. By constructing the optical laminate using a polarizing element that is adjusted to have the above moisture content at the material stage before the optical laminate is constructed, an optical laminate including a polarizing element whose moisture content satisfies the above numerical range can be easily constructed. The moisture content of the polarizing element in the optical laminate may be adjusted to be within the above numerical range when the optical laminate is attached to the image display cell. In this case, the optical laminate is less likely to curl since it is attached to the image display cell.

[0029] (Feature (b)) In the case of having the characteristic (b), the moisture content of the optical laminate is equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%. It is preferably equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 30% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 45%. It is more preferably equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 42%, even more preferably equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 40%, and most preferably equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 38%. If the moisture content of the optical laminate is lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20%, the optical laminate is less easy to handle and more likely to crack. If the moisture content of the optical laminate is higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%, the transmittance of the polarizing element is more likely to decrease. It is presumed that if the moisture content of the optical laminate is high, the PVA resin is more likely to be polyenated.

[0030] As a method for checking whether the moisture content of the optical laminate is equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%, there are a method for storing the optical laminate for a certain period of time in an environment adjusted to the above temperature and relative humidity ranges and checking that there is no change in mass, or a method for calculating in advance the equilibrium moisture content of the optical laminate in an environment adjusted to the above temperature and relative humidity ranges and comparing the moisture content of the optical laminate with the previously calculated equilibrium moisture content. If there is no change in mass after storing the optical laminate for a certain period of time, it can be considered that the moisture content has reached equilibrium in the storage environment.

[0031] Methods for producing an optical laminate having a moisture content equal to or greater than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48% include, but are not limited to, a method of storing the optical laminate in an environment adjusted to the above-mentioned temperature and relative humidity ranges for 10 minutes to 3 hours, or a method of heat treating the optical laminate at 30°C to 90°C.

[0032] In the production of an image display device, an image display panel having an optical laminate laminated on an image display cell may be stored in an environment adjusted to the above-mentioned temperature and relative humidity ranges for 10 minutes to 3 hours, or may be heat-treated at 30°C to 90°C.

[0033] (Method of manufacturing polarizing element) The method for producing the polarizing element is not particularly limited, but typical methods include a method in which a polyvinyl alcohol-based resin film that has been previously wound into a roll is sent out and stretched, dyed, crosslinked, and the like to produce the polarizing element (hereinafter referred to as "production method 1"), and a method including a step of applying a coating liquid containing a polyvinyl alcohol-based resin onto a substrate film to form a polyvinyl alcohol-based resin layer as a coating layer, and stretching the resulting laminate (hereinafter referred to as "production method 2").

[0034] Manufacturing method 1 can be achieved through a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing the polyvinyl alcohol-based resin film with a dichroic dye such as iodine to adsorb the dichroic dye, a process of treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye with an aqueous boric acid solution, and a process of washing with water after the treatment with the aqueous boric acid solution.

[0035] The swelling step is a treatment step in which the polyvinyl alcohol-based resin film is immersed in a swelling bath, which can remove dirt and blocking agents from the surface of the polyvinyl alcohol-based resin film, and can suppress uneven dyeing by swelling the polyvinyl alcohol-based resin film. The swelling bath usually uses a medium mainly composed of water, such as water, distilled water, or pure water. The swelling bath may contain surfactants, alcohol, and the like, as appropriate, according to a conventional method.

[0036] The temperature of the swelling bath is preferably about 10 to 60° C., more preferably about 15 to 45° C., and even more preferably about 18 to 30° C. The immersion time in the swelling bath cannot be determined in general because the degree of swelling of the polyvinyl alcohol-based resin film is affected by the temperature of the swelling bath, but is preferably about 5 to 300 seconds, more preferably about 10 to 200 seconds, and even more preferably about 20 to 100 seconds. The swelling step may be carried out only once, or may be carried out multiple times as necessary.

[0037] The dyeing process is a treatment process in which the polyvinyl alcohol-based resin film is immersed in a dye bath (iodine solution), and iodine or a dichroic substance such as a dichroic dye can be adsorbed and oriented in the polyvinyl alcohol-based resin film. The iodine solution is usually preferably an aqueous iodine solution, and contains iodine and an iodide as a dissolving aid. 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.

[0038] In the dye bath, the iodine concentration is preferably about 0.01 to 1% by weight, more preferably about 0.02 to 0.5% by weight, and the iodide concentration is preferably about 0.01 to 10% by weight, more preferably about 0.05 to 5% by weight, and even more preferably about 0.1 to 3% by weight.

[0039] The temperature of the dye bath is preferably about 10 to 50° C., more preferably about 15 to 45° C., and even more preferably about 18 to 30° C. The immersion time in the dye bath cannot be determined in general because the degree of dyeing of the polyvinyl alcohol-based resin film is affected by the temperature of the dye bath, but is preferably about 10 to 300 seconds, and more preferably about 20 to 240 seconds. The dyeing process may be carried out only once, or may be carried out multiple times as necessary.

[0040] The crosslinking step is a treatment step in which the polyvinyl alcohol-based resin film dyed in the dyeing step is immersed in a treatment bath (crosslinking bath) containing a boron compound, and the polyvinyl alcohol-based resin film is crosslinked by the boron compound, so that iodine molecules or dye molecules can be adsorbed to the crosslinked structure. Examples of the boron compound include boric acid, borate salts, and borax. The crosslinking bath is generally an aqueous solution, but may also be, for example, a mixed solution of water and an organic solvent miscible with water. In addition, the crosslinking bath preferably contains potassium iodide from the viewpoint of controlling the content of potassium in the polarizing element.

[0041] In the crosslinking bath, the concentration of the boron compound is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and more preferably about 2 to 5% by weight. In addition, when potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and more preferably about 2 to 5% by weight.

[0042] The temperature of the crosslinking bath is preferably about 20 to 70° C., more preferably about 30 to 60° C. The immersion time in the crosslinking bath cannot be determined in general because the degree of crosslinking of the polyvinyl alcohol resin film is affected by the temperature of the crosslinking bath, but is preferably about 5 to 300 seconds, more preferably about 10 to 200 seconds. The crosslinking step may be carried out only once, or may be carried out multiple times as necessary.

[0043] The stretching process is a process for stretching the polyvinyl alcohol-based resin film at least in one direction to a predetermined ratio. The film is uniaxially stretched in the longitudinal direction (machine direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method can be used. The stretching step may be carried out only once, or may be carried out multiple times as necessary. The stretching step may be carried out at any stage in the production of the polarizing element.

[0044] The treatment bath (stretching bath) in the wet stretching method can usually use a solvent such as water or a mixed solution of water and an organic solvent miscible with water. The stretching bath preferably contains potassium iodide from the viewpoint of controlling the potassium content in the polarizing element. When potassium iodide is used in the stretching bath, the concentration of potassium iodide in the stretching bath is preferably about 1 to 15% by weight, more preferably about 2 to 10% by weight, and more preferably about 3 to 6% by weight. In addition, the treatment bath (stretching bath) can contain a boron compound from the viewpoint of suppressing film breakage during stretching, and in this case, the concentration of the boron compound in the stretching bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and more preferably about 2 to 5% by weight.

[0045] The temperature of the stretching bath is preferably about 25 to 80° C., more preferably about 40 to 75° C., and even more preferably about 50 to 70° C. The immersion time in the stretching bath cannot be determined in general because the degree of stretching of the polyvinyl alcohol-based resin film is affected by the temperature of the stretching bath, but is preferably about 10 to 800 seconds, and more preferably about 30 to 500 seconds. The stretching treatment in the wet stretching method may be performed together with one or more treatment steps of a swelling step, a dyeing step, a crosslinking step, and a washing step.

[0046] Examples of the dry stretching method include a roll-to-roll stretching method, a heated roll stretching method, a compression stretching method, etc. The dry stretching method may be carried out together with a drying step.

[0047] The total stretching ratio (cumulative stretching ratio) applied to the polyvinyl alcohol-based resin film can be appropriately set depending on the purpose, but is preferably about 2 to 7 times, more preferably about 3 to 6.8 times, and even more preferably about 3.5 to 6.5 times.

[0048] The cleaning step is a treatment step in which the polyvinyl alcohol-based resin film is immersed in a cleaning bath, and foreign matter remaining on the surface of the polyvinyl alcohol-based resin film can be removed. A medium containing water as a main component, such as water, distilled water, or pure water, is usually used as the cleaning bath. 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 about 1 to 10% by weight, more preferably about 1.5 to 4% by weight, and even more preferably about 1.8 to 3.8% by weight.

[0049] The temperature of the cleaning bath is preferably about 5 to 50° C., more preferably about 10 to 40° C., and even more preferably about 15 to 30° C. The immersion time in the cleaning bath cannot be determined in general because the degree of cleaning of the polyvinyl alcohol-based resin film is affected by the temperature of the cleaning bath, but is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and even more preferably about 3 to 20 seconds. The cleaning step may be carried out only once, or may be carried out multiple times as necessary.

[0050] The drying step is a step of drying the polyvinyl alcohol-based resin film washed in the washing step to obtain a polarizing element. The drying can be performed by any appropriate method, for example, natural drying, air drying, or heat drying.

[0051] The production method 2 includes a step of applying a coating liquid containing the polyvinyl alcohol resin onto a substrate film, a step of uniaxially stretching the obtained laminated film, and a step of applying a polyvinyl alcohol resin to the uniaxially stretched laminated film. The polarizing element can be manufactured by dyeing the vinyl alcohol-based resin layer with a dichroic dye, adsorbing the dichroic dye to form a polarizing element, treating the film with the adsorbed dichroic dye with an aqueous boric acid solution, and washing with water after the treatment with the aqueous boric acid solution. The substrate film used to form the polarizing element may be used as a protective layer for the polarizing element. If necessary, the substrate film may be peeled off from the polarizing element.

[0052] (Retardation film) The retardation film has a tensile modulus of 3000 MPa or less at 23°C. Even with a retardation film having such a tensile modulus, cracks can be prevented according to the present invention. The lower limit of the tensile modulus at 23°C is not particularly limited, but can be, for example, 1000 MPa or more. For example, an olefin resin can be used as the material for such a retardation film. The olefin resin is a resin consisting of structural units derived from chain aliphatic olefins such as ethylene and propylene, or alicyclic olefins such as norbornene and its substitutes (hereinafter, these are also collectively referred to as norbornene monomers). The olefin resin may be a copolymer using two or more monomers.

[0053] Among them, as the olefin resin, a cyclic olefin resin, which is a resin mainly containing a structural unit derived from an alicyclic olefin, is preferably used. A typical example of an alicyclic olefin constituting a cyclic olefin resin is a norbornene monomer. Norbornene is a compound in which one carbon-carbon bond of norbornane becomes a double bond, and is named bicyclo[2,2,1]hept-2-ene according to the IUPAC nomenclature system. Examples of norbornene substitutions include 3-substitutions, 4-substitutions, and 4,5-disubstitutions, with the double bond position of norbornene being the 1,2-position, and further include dicyclopentadiene and dimethanooctahydronaphthalene.

[0054] The cyclic olefin resin may or may not have a norbornane ring in its constituent unit. The norbornene monomer forming the cyclic olefin resin without a norbornane ring in its constituent unit is, for example, one that becomes a 5-membered ring by ring opening, typically, norbornene, dicyclopentadiene, 1- or 4-methylnorbornene, and 4-phenylnorbornene. When the cyclic olefin resin is a copolymer, the molecular arrangement is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer.

[0055] More specific examples of the cyclic olefin resin include ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers and other monomers, polymer modifications obtained by adding maleic acid or cyclopentadiene to these, and polymers or copolymers obtained by hydrogenating these; addition polymers of norbornene monomers, and addition copolymers of norbornene monomers and other monomers. Examples of other monomers in the case of copolymerization include α-olefins, cycloalkenes, and non-conjugated dienes. The cyclic olefin resin may also be a copolymer using one or more of norbornene monomers and other alicyclic olefins.

[0056] Among the above specific examples, the cyclic olefin resin is preferably a resin obtained by hydrogenating a ring-opening polymer or a ring-opening copolymer using a norbornene monomer. Such a cyclic olefin resin is made into a film-like material that has been subjected to a stretching treatment in advance, and a shrinkable film having a predetermined shrinkage rate is laminated thereon and heat-shrunk, thereby providing a retardation film having high uniformity and a large retardation value.

[0057] Commercially available cyclic olefin resins using such norbornene monomers include "ZEONEX" and "ZEONOR" sold by Zeon Corporation, and "ARTON" sold by JSR Corporation. Films of these cyclic olefin resins and their stretched films are also commercially available, for example, "ZEONOR Film" from Optes Corporation, "ARTON Film" from JSR Corporation, and "ESCINA" from Sekisui Chemical Co., Ltd.

[0058] In addition, the retardation film used in the present invention can be a film made of a mixed resin containing two or more kinds of olefin resins, or a film made of a mixed resin of an olefin resin and another thermoplastic resin. For example, the mixed resin containing two or more kinds of olefin resins can be a mixture of the above-mentioned cyclic olefin resin and a chain aliphatic olefin resin. When using a mixed resin of an olefin resin and another thermoplastic resin, the other thermoplastic resin is 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, polyvinylidene chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyarylate resins, liquid crystal resins, polyamideimide resins, polyimide resins, and polytetrafluoroethylene resins. These thermoplastic resins can be used alone or in combination of two or more. The thermoplastic resins can also be used after any suitable polymer modification. Examples of polymer modification include copolymerization, crosslinking, molecular end modification, and stereoregularity impartation.

[0059] When using a mixed resin of an olefin resin and another thermoplastic resin, the content of the other thermoplastic resin is usually about 50% by weight or less, preferably about 40% by weight or less, based on the total resin. By setting the content of the other thermoplastic resin within this range, a retardation film having a small absolute value of the photoelastic coefficient, good wavelength dispersion characteristics, and excellent durability, mechanical strength, and transparency can be obtained.

[0060] Such olefin resins can be formed into a film by casting from a solution, melt extrusion, etc. When forming a film from a mixed resin of two or more kinds, the film formation method is not particularly limited, and for example, a method of forming a film by casting using a homogeneous solution obtained by stirring and mixing the resin components with a solvent in a predetermined ratio, and a method of melt mixing the resin components in a predetermined ratio and forming a film by melt extrusion, etc. are adopted.

[0061] The retardation film may contain other components such as residual solvent, stabilizer, plasticizer, antioxidant, antistatic agent, and ultraviolet absorber, as necessary, within the scope of the present invention. In addition, the retardation film may contain a leveling agent to reduce surface roughness.

[0062] The retardation film used in the present invention is preferably applied to one having an in-plane retardation value of 80 nm or more at a wavelength of 550 nm. The in-plane retardation value at a wavelength of 550 nm may be, for example, 300 nm or less, or 200 nm or less. Even if it has such a high retardation value, the retardation film does not crack even if it is stored in an environment of a temperature of 23°C and a relative humidity of 55% for one month after a heat durability test. In general, the higher the retardation value, the more uniform the molecular orientation of the retardation film is, and the more likely it is to crack when subjected to external force.

[0063] The retardation film as described above can be obtained by known longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like. In addition to appropriately adjusting the stretching ratio and stretching speed so as to obtain a desired retardation value, various temperatures such as a preheating temperature, a stretching temperature, a heat setting temperature, and a cooling temperature during stretching, and their patterns may be appropriately selected.

[0064] The thickness of the retardation film is not particularly limited, but is preferably within the range of 15 to 80 μm, more preferably within the range of 18 to 45 μm, and most preferably within the range of 20 to 30 μm. If the thickness of the norbornene-based resin film is less than 15 μm, the film is difficult to handle and tends to be difficult to achieve a predetermined retardation value, while if the thickness of the norbornene-based resin film is more than 80 μm, the film may be poor in processability, may have a low transparency, or may have a large weight of the obtained polarizing plate.

[0065] (Other functional layers) The polarizing plate of the present invention may have other functional layers such as an antistatic layer or a second retardation layer. For example, when used in an IPS mode liquid crystal display device, a positive C plate may be used as the second retardation layer. The positive C plate may be laminated between the polarizing element and the retardation film, or may be laminated on the surface of the retardation film opposite to the polarizing element side.

[0066] <Anti-reflection film> The anti-reflection film has an anti-reflection function of reducing the reflectance of light incident on the viewing side surface of the optical laminate. The optical laminate has an anti-reflection film in order to prevent a decrease in contrast due to reflection of external light. In order to satisfy the above requirement (i), the anti-reflection film has a moisture permeability of 300 g / m at a temperature of 40% and a relative humidity of 90%. 2 ·day or less, preferably 100g / m 2 ·day or less can be used. The moisture permeability of the antireflective film is a value measured according to the method described in the Examples below. By using such an antireflective film with low moisture permeability, it is possible to improve the durability against moist heat and high temperatures. The moisture 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 moisture permeability of the antireflective film at a temperature of 40% and a relative humidity of 90% is usually 1 g / m 2 ·day or more.

[0067] The anti-reflection film may have an anti-reflection layer on one side of a substrate film. The substrate film is not particularly limited, but may be made of the same material as that used for the protective film described below.

[0068] As the anti-reflection film, a known anti-reflection film or a commercially available anti-reflection film can be used, and examples thereof include the following.

[0069] (a) An anti-reflection film using the principle of the so-called moth-eye structure, which is made of a concave-convex pattern whose period is controlled to be equal to or shorter than the wavelength of visible light (anti-reflection films described in JP 2010-122599 A, JP 2001-517319 A, JP 2004-205990 A, JP 2004-287238 A, JP 2001-27505 A, JP 2002-286906 A, WO 2006 / 059686, etc.). As a commercially available product, for example, Mosmite (registered trademark, manufactured by Mitsubishi Chemical Corporation) can be used. (b) Antireflection films consisting of fine concave-convex patterns that exhibit optical functions (antireflection films described in JP-A-2004-59822, JP-B-5-46064, JP-B-6-85103, etc.). (c) An anti-reflection film having an uneven pattern composed of countless minute unevenness with a pitch equal to or smaller than the wavelength of light (anti-reflection films described in JP-A-2001-264520, JP-A-9-80205, etc.). (d) Antireflection films having a single layer or multiple layers with an adjusted refractive index (antireflection films described in JP-A-2000-187102, JP-A-6-186401, JP-A-2004-345333, etc.). Commercially available products include, for example, MTAR and MTAGAR (manufactured by Mitate Co., Ltd.). The thickness of the antireflection film is, for example, not less than 10 μm and not more than 100 μm.

[0070] The anti-reflection film is preferably a thin film having a strictly controlled thickness and refractive index, or an anti-reflection layer having two or more thin films laminated thereon. In this specification, the term "thin film" refers to a film having a thickness of 1 μm or less. The anti-reflection layer can be configured to exhibit an anti-reflection function by canceling out the inverted phases of incident light and reflected light by utilizing the interference effect of light. The wavelength region of visible light that exhibits the anti-reflection function is, for example, 380 to 780 nm, and the wavelength region with particularly high visibility is the range of 450 to 650 nm, and it is preferable to design the anti-reflection layer so as to minimize the reflectance at 550 nm, which is the central wavelength. The thickness of the anti-reflection layer is preferably 100 nm to 350 nm, more preferably 150 nm to 300 nm.

[0071] In designing an antireflection layer based on the interference effect of light, a method for improving the interference effect is, for example, to increase the difference in refractive index between the antireflection layer and the antiglare hard coat layer described later. In general, in a multi-layer antireflection layer having a structure in which 2 to 15 thin films (thin films with strictly controlled thickness and refractive index) are laminated, the degree of freedom of the optical design of the antireflection layer is increased by forming multiple layers of components with different refractive indexes to a predetermined thickness, and the antireflection effect can be improved, and the spectral reflection characteristics can be made uniform (flat) in the visible light region. Since high thickness accuracy is required for the thin film, each layer is generally formed by a dry method such as vacuum deposition, sputtering, CVD, etc. In order to set the moisture permeability within a predetermined range, it is preferable to use sputtering. In addition, by using an antireflection film in which each layer is formed by sputtering, an optical laminate with high scratch resistance can be constructed.

[0072] The antireflection layer is preferably formed by alternately laminating low-refractive index layers and high-refractive index layers. The high-refractive index layers or the low-refractive index layers do not have to have the same refractive index, but it is preferable to use the same material and have the same refractive index from the viewpoint of reducing material costs and film formation costs.

[0073] Materials constituting the low refractive index layer (or materials that are the main components of the low refractive index layer) include 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 these, silicon dioxide (SiO2) is the most preferable due to its low refractive index, lack of absorption in the visible light range, and high film strength.

[0074] Materials constituting the high refractive index layer (or materials that are the main components of the high refractive index layer) include niobium pentoxide (Nb2O5), titanium dioxide (TiO2), zirconium dioxide (ZrO2), tantalum pentoxide (Ta2O5), silicon oxynitride (SiON), silicon nitride (Si3N4), and niobium silicon oxide (SiNbO), etc. Among these, niobium pentoxide (Nb2O5) or titanium dioxide (TiO2) are more preferable due to their high refractive index and high film strength, and niobium pentoxide (Nb2O5) is the most preferable due to its lack of absorption in the visible light range.

[0075] The composition ratio of each compound is controlled to be different from the stoichiometric ratio. The refractive index can be changed to some extent by controlling the film density. The materials constituting the low reflectance layer and the high reflectance layer are not limited to the above compounds as long as they satisfy the above-mentioned refractive index conditions. In addition, inevitable impurities may be included.

[0076] The anti-reflection film may have a hard coat layer between the substrate film and the anti-reflection layer. The hard coat layer can improve the mechanical properties of the anti-reflection layer, such as hardness and elastic modulus. The hard coat layer preferably has high surface hardness and excellent scratch resistance. The hard coat layer can be formed, for example, by applying a solution containing a curable resin onto the substrate film.

[0077] Examples of the curable resin include thermosetting resin, ultraviolet curing resin, electron beam curing resin, etc. Examples of the types of curable resin include various resins such as polyester resin, acrylic resin, urethane resin, acrylic urethane resin, amide resin, silicone resin, silicate resin, epoxy resin, melamine resin, oxetane resin, acrylic urethane resin, etc. These curable resins can be used alone or in combination as appropriate.

[0078] Among these, acrylic resins, acrylic urethane resins, and epoxy resins are preferred because they have high hardness, can be cured with ultraviolet light, and are excellent in productivity, and among these, acrylic urethane resins are preferred. UV-curable resins include UV-curable monomers, oligomers, polymers, etc. Preferred examples of UV-curable resins include those having a UV-polymerizable functional group, and among these, those containing an acrylic monomer or oligomer having two or more, particularly 3 to 6, functional groups as a component.

[0079] In order to provide the anti-reflection film with anti-glare and anti-glare properties, the hard coat layer provided on the surface of the substrate film preferably has anti-glare properties. Examples of the anti-glare hard coat layer include those in which fine particles are dispersed in the above-mentioned curable resin matrix. As the fine particles to be dispersed in the resin matrix, transparent ones such as various metal oxide fine particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide, glass fine particles, crosslinked or uncrosslinked organic fine particles made of various transparent polymers such as polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate, and silicone fine particles can be used without any particular limitation. These fine particles can be used by appropriately selecting one or more kinds. Among them, fine particles having a higher refractive index than the matrix resin are preferred, and for example, organic fine particles having a refractive index of 1.5 or more such as styrene beads (refractive index 1.59) are preferred. The average particle size of the fine particles is preferably 1 to 10 μm, more preferably 2 to 5 μm. The ratio of the fine particles is not particularly limited, but is preferably 6 to 20 parts by weight based on 100 parts by weight of the matrix resin.

[0080] The hard coat layer can be formed, for example, by applying a solution containing a curable resin onto a substrate film. The solution for forming the hard coat layer preferably contains an ultraviolet polymerization initiator. To form an antiglare hard coat layer containing fine particles, it is preferable to apply a solution containing the above-mentioned fine particles in addition to the curable resin onto a transparent film. The solution may contain additives such as a leveling agent, a thixotropic agent, and an antistatic agent. In forming the antiglare hard coat layer, a fine uneven structure due to protruding particles can be easily formed on the surface of the hard coat layer by adding a thixotropic agent (silica, mica, etc., having a particle diameter of 0.1 μm or less) to the solution.

[0081] The thickness of the hard coat layer is not particularly limited, but in order to achieve high hardness, it is preferably 0.5 μm. The thickness of the hard coat layer is preferably 1 μm or more, and more preferably 1 μm or more. Considering the ease of formation by coating, the thickness of the hard coat layer 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 so as not to prevent the release of moisture from the polarizing element to the outside, the thickness of the hard coat layer is preferably within the above range.

[0082] The arithmetic mean roughness Ra of the surface of the substrate film on which the antireflection layer is formed is preferably 1.5 nm or less, more preferably 1.0 nm or less. The arithmetic mean roughness Ra may be 0.00 nm or more, or may be 0.05 nm or more. When a hard coat layer is formed on the substrate film, the arithmetic mean roughness of the hard coat layer is the arithmetic mean roughness of the surface of the substrate film on which the antireflection layer is formed. The arithmetic mean roughness Ra is obtained from an observation image of 1 μm square using an atomic force microscope (AFM).

[0083] As described above, by forming a hard coat layer by coating, the arithmetic mean roughness of the surface of the substrate film can be reduced. If the surface of the substrate film is smooth, the arithmetic mean roughness of the surface of the antireflection layer formed thereon also becomes small, and the scratch resistance of the antireflection film tends to be improved.

[0084] <Protective film> The protective film is not particularly limited, but is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and phase difference value stability, etc. The material of the protective film is not particularly limited, but examples thereof 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, polyvinylidene chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins, and polyimide resins.

[0085] These resins can be used alone or in combination of two or more kinds. These resins can also be used after any suitable polymer modification, such as copolymerization, crosslinking, molecular end modification, stereoregularity control, and mixing including reactions between different polymers.

[0086] The cellulose-based resin may be an organic acid ester or mixed organic acid ester of cellulose in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are replaced with acetyl groups, propionyl groups, and / or butyryl groups. For example, cellulose acetate, propionate, butyrate, and mixed esters thereof may be used. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like are preferred.

[0087] These resins may contain appropriate additives as long as the transparency is not impaired. Examples of additives include antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, antiblocking agents, retardation reducing agents, stabilizers, processing aids, plasticizers, impact resistance aids, matting agents, antibacterial agents, and fungicides. A plurality of these additives may be used in combination.

[0088] The thickness of the protective film is usually 1 to 100 μm, but from the viewpoints of strength, ease of handling, etc., it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and more preferably 15 to 50 μm. It is more preferable that it is m.

[0089] The protective film may have other optical functions at the same time, and may be formed into a laminated structure in which a plurality of layers are laminated. The thickness of the protective film is preferably thin from the viewpoint of optical properties, but if it is too thin, the strength decreases and the processability becomes poor. The appropriate thickness is 5 to 100 μm, preferably 10 to 80 μm, and more preferably 15 to 70 μm.

[0090] In the case of a configuration having protective films on both sides of a polarizing element, when bonding is performed using a water-based adhesive such as a PVA adhesive, it is preferable that the protective film on at least one side be either a cellulose acylate film or a (meth)acrylic polymer film from the standpoint of moisture permeability, and of these, a cellulose acylate film is preferred.

[0091] The first protective film and the second protective film may be the same or different. The first protective film and the second protective film may have a surface treatment layer (coating layer) such as an antistatic layer on their outer surfaces (the surfaces opposite to the polarizing element). The thickness of the first protective film and the second protective film includes the thickness of the surface treatment layer.

[0092] In order to satisfy the above requirement (ii), the first protective film must have a moisture permeability of 300 g / m at a temperature of 40°C and a relative humidity of 90%. 2The moisture permeability of the protective film can be adjusted by the material, thickness, etc. The moisture permeability at a temperature of 40°C and a relative humidity of 90% is 300 g / m 2 As protective films with a shelf life of 1.0 days or less, cyclic olefin resin films, films laminated with a water vapor barrier layer by a dry method, etc. are preferably used.

[0093] On the other hand, the anti-reflection film satisfies the above requirement (i) and has a moisture permeability of 100 g / m at a temperature of 40° C. and a relative humidity of 90%. 2 ·days, the moisture permeability of the second protective film at a temperature of 40°C and a relative humidity of 90% is 200g / m 2 ·days or more is preferable. When manufacturing an optical laminate, as described below, the second protective film may be laminated to the polarizing element 10 using a laminating agent (adhesive or pressure sensitive adhesive) such as a water-based adhesive, and then a laminating layer may be formed by a drying process, and then the first protective film may be laminated. In this case, by setting the moisture permeability of the protective film laminated on the retardation film side of the polarizing element to the above range, moisture contained in the laminating agent can be easily removed by the drying process.

[0094] At least one of the protective films may have a retardation function for the purpose of compensating for viewing angle, etc. In that case, the film itself may have a retardation function, may have a separate retardation layer, or may have a combination of both. The film having a retardation function may be attached to the polarizing element via a pressure-sensitive adhesive layer or an adhesive layer via another protective film that is attached to the polarizing element.

[0095] <Laminating layer> In the optical laminate, a bonding layer is used to bond the layers together. Examples of the bonding layer include an adhesive layer and a pressure-sensitive adhesive layer.

[0096] (adhesive layer) The adhesive layer can be used, for example, to attach a protective film to a polarizing element. Any appropriate adhesive can be used as the adhesive constituting the adhesive layer. The adhesive can be a water-based adhesive, a solvent-based adhesive, an active energy ray curing adhesive, or the like, but a water-based adhesive is preferred.

[0097] The thickness of the adhesive when applied can be set to any suitable value. For example, it is set so that an adhesive layer having a desired thickness is obtained after curing or heating (drying). The thickness of the adhesive layer is preferably 0.01 μm or more and 7 μm or less, more preferably 0.01 μm or more and 5 μm or less, even more preferably 0.01 μm or more and 2 μm or less, and most preferably 0.01 μm or more and 1 μm or less.

[0098] (Water-based adhesive) Any suitable aqueous adhesive may be used as the aqueous adhesive. Among them, an aqueous adhesive containing a PVA resin (PVA adhesive) is preferably used. The average polymerization degree of the PVA resin contained in the aqueous adhesive is preferably about 100 to 5500, more preferably 1000 to 4500, from the viewpoint of adhesiveness. The average saponification degree is preferably about 85 mol% to 100 mol%, more preferably 90 mol% to 100 mol%, from the viewpoint of adhesiveness.

[0099] The PVA resin contained in the water-based adhesive preferably contains an acetoacetyl group, because it has excellent adhesion between the PVA resin layer and the protective film and excellent durability. The acetoacetyl group-containing PVA resin can be obtained, for example, by reacting a PVA resin with diketene by any method. The acetoacetyl group modification degree of the acetoacetyl group-containing PVA resin is typically 0.1 mol% or more, and preferably about 0.1 mol% to 20 mol%. The resin concentration of the above-mentioned water-based adhesive is preferably 0.1% by mass to 15% by mass, and more preferably 0.5% by mass to 10% by mass.

[0100] The water-based adhesive may contain a crosslinking agent. Any known crosslinking agent may be used as the crosslinking agent. Examples of such crosslinking agents include water-soluble epoxy compounds, dialdehydes, and isocyanates.

[0101] When the PVA-based resin is an acetoacetyl group-containing PVA-based resin, the crosslinking agent is preferably any one of glyoxal, glyoxylate, and methylolmelamine, more preferably any one of glyoxal and glyoxylate, and particularly preferably glyoxal.

[0102] The water-based adhesive may also contain an organic solvent. The organic solvent is preferably an alcohol in that it is miscible with water, and among alcohols, methanol or ethanol is more preferable. Some urea compounds have low solubility in water, but some have sufficient solubility in alcohol. In this case, one of the preferred embodiments is to dissolve the urea compound in alcohol to prepare an alcohol solution of the urea compound, and then add the alcohol solution of the urea compound to the aqueous PVA solution to prepare the adhesive.

[0103] The methanol concentration of the water-based adhesive is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 60% by mass or less. By making the methanol concentration 10% by mass or more, it becomes easier to suppress polyenation in a high-temperature environment. In addition, by making the methanol content 70% by mass or less, it is possible to suppress deterioration of the hue.

[0104] (Active energy ray curing adhesive) The active energy ray curable adhesive is an adhesive that is cured by irradiation with active energy rays such as ultraviolet rays, and examples thereof include an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, an adhesive containing a binder resin and a photoreactive crosslinking agent, etc. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and adhesives derived from these monomers. Examples of the photopolymerization initiator include compounds containing substances that generate active species such as neutral radicals, anion radicals, and cation radicals when irradiated with active energy rays such as ultraviolet rays.

[0105] (Adhesive layer) The pressure-sensitive adhesive layer can be used, for example, to attach an anti-reflection film to the first protective film.

[0106] The adhesive layer can be composed of an adhesive composition mainly composed of a resin such as a (meth)acrylic resin, a rubber resin, a urethane resin, an ester resin, a silicone resin, or a polyvinyl ether resin. Among them, an adhesive composition having a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance, etc., is preferable. The adhesive composition may be of an active energy ray curing type or a heat curing type. The thickness of the adhesive layer is usually 3 to 30 μm, and preferably 3 to 25 μm.

[0107] As the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition, for example, a polymer or copolymer containing one or more (meth)acrylic acid esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, is preferably used. It is preferable to copolymerize a polar monomer into the base polymer. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0108] The adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include divalent or higher metal ions that form a carboxylate metal salt with a carboxyl group; polyamine compounds that form an amide bond with a carboxyl group; polyepoxy compounds or polyols that form an ester bond with a carboxyl group; and polyisocyanate compounds that form an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferred.

[0109] The storage modulus of the pressure-sensitive adhesive layer is preferably 0.001 to 0.350 MPa, more preferably 0.001 to 0.200 MPa, still 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 pressure-sensitive adhesive layer can be measured according to the method described in the examples below.

[0110] The thickness of the pressure-sensitive adhesive layer is preferably from 1 to 200 μm, more preferably from 2 to 100 μm, further preferably from 2 to 80 μm, and particularly preferably from 3 to 50 μm.

[0111] As described above, in the present invention, by using an antireflection film in which each layer is formed by sputtering, an optical laminate having high scratch resistance can be formed. In this case, by controlling the storage modulus and thickness of the adhesive layer used to attach the antireflection film to the first protective film within the following ranges, an optical laminate having high indentation hardness, represented by pencil hardness, and an antireflection layer that is less likely to crack can be formed, which is particularly preferred.

[0112] In particular, the storage modulus of the pressure-sensitive adhesive layer for bonding the first protective film and the antireflection 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 particularly preferably 0.120 to 0.160 MPa. Preferred.

[0113] The thickness of the pressure-sensitive adhesive layer is preferably from 3 to 30 μm, more preferably from 3 to 20 μm, further preferably from 3 to 10 μm, and particularly preferably from 3 to 8 μm.

[0114] [Method of manufacturing optical laminate] The method for producing an optical laminate of this embodiment includes a moisture content adjusting step. In the moisture content adjusting step, when producing an optical laminate having the characteristic (a), the moisture content of the polarizing element is adjusted so that the moisture content of the polarizing element is equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%. The method for adjusting the moisture content of the polarizing element is as described above. In the moisture content adjusting step, when producing an optical laminate having the characteristic (b), the moisture content of the optical laminate is adjusted so that the moisture content of the optical laminate is equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%. The method for adjusting the moisture content of the optical laminate is as described above.

[0115] As a step other than the moisture content adjusting step, a lamination step of laminating each layer may be included, such as a step of laminating a polarizing element and a protective film to obtain a polarizing plate, a step of laminating a polarizing plate and an antireflection film, a step of laminating a polarizing plate and a retardation film, etc. The order of the moisture content adjusting step and each lamination step is not limited, and the moisture content adjusting step and the lamination step may be performed in parallel.

[0116] [Display device] The optical laminate can be used in various display devices such as liquid crystal display devices and organic EL display devices. A display device using the optical laminate of this embodiment can be excellent in wet heat durability and high temperature durability. Since the display device using the optical laminate of this embodiment has excellent wet heat durability and high temperature durability, it can be suitably used as a display device for vehicle mounting.

[0117] The display device includes a display cell and an optical laminate laminated on the viewing side surface of the display cell, and the optical laminate is laminated on the viewing side surface of the display cell in an orientation in which the retardation film, the polarizing element, and the antireflection film are arranged in this order from the display cell side. For example, the above-mentioned pressure-sensitive adhesive layer is used for laminating the display cell and the optical laminate.

[0118] <Display cell> Examples of the display cell include a liquid crystal cell and an organic EL cell. The liquid crystal cell may be a reflective liquid crystal cell that uses external light, a transmissive liquid crystal cell that uses light from a light source such as a backlight, or a semi-transmissive semi-reflective liquid crystal cell that uses both external light and light from a light source. When the liquid crystal cell uses light from a light source, the display device (liquid crystal display device) has a polarizing plate disposed on the opposite side to the viewing side of the display cell (liquid crystal cell), and further has a light source disposed thereon. The polarizing plate on the light source side and the liquid crystal cell are preferably bonded together via an appropriate adhesive layer. The driving method of the liquid crystal cell may be any type, such as VA mode, IPS mode, TN mode, STN mode, or bend orientation (π type).

[0119] As the organic EL cell, a light-emitting body (organic electroluminescence light-emitting body) is preferably formed by sequentially laminating a transparent electrode, an organic light-emitting layer, and a metal electrode on a transparent substrate. The organic light-emitting layer is a laminate of various organic thin films, and various layer configurations can be adopted, such as a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light-emitting layer made of a fluorescent organic solid such as anthracene, a laminate of these light-emitting layers and an electron injection layer made of a perylene derivative or the like, or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer. EXAMPLES

[0120] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and % representing the content or amount used are based on mass unless otherwise specified. In the following examples, each physical property was measured by the following method.

[0121] [Measurement method] (1) Film thickness measurement method The measurements were made using a digital micrometer, MH-15M, manufactured by Nikon Corporation.

[0122] (2) Moisture permeability of anti-reflective film In accordance with JIS K 7129:2008 Appendix B, the moisture permeability of the anti-reflection film was measured in an atmosphere of 40°C and 90% relative humidity.

[0123] (3) Measuring the thickness of each layer of the anti-reflection layer The thickness was measured using a reflection spectroscopic film thickness meter FE3000 manufactured by Otsuka Electronics Co., Ltd.

[0124] (4) Tensile modulus at 23°C (measured in accordance with JIS K 7161) A test piece having a width of 15 mm and a length of 150 mm was cut out from the film parallel to the slow axis and the fast axis. Then, the test piece was clamped at both ends in the long side direction with the upper and lower grips of a tensile tester (AUTOGRAPH (registered trademark) AG-1S tester manufactured by Shimadzu Corporation) so that the distance between the grips was 100 mm, and pulled at a pulling speed of 50 mm / min in an environment of 23°C, and a stress-strain curve was created, and the tensile modulus in the direction parallel to the slow axis and the fast axis at 23°C was calculated. The larger value of the tensile modulus in the direction parallel to the slow axis and the fast axis calculated in this way was taken as the value of the tensile modulus at 23°C in the present invention.

[0125] (5) Storage modulus The storage modulus G' of the pressure-sensitive adhesive layer was measured according to the following (I) to (III). (I) Two samples of 25±1 mg each are taken from the adhesive layer and each is molded into an approximately ball-like shape. (II) The obtained approximately ball-like samples are attached to the top and bottom surfaces of an I-shaped jig, and both the top and bottom are sandwiched between L-shaped jigs. The measurement sample is structured as follows: L-shaped jig / adhesive layer / I-shaped jig / adhesive layer / L-shaped jig. (III) The storage modulus G' of the sample thus prepared is measured using a dynamic measuring instrument manufactured by IT Measurement and Control Co., Ltd. The measurements were performed using a dynamic viscoelasticity measuring device "DVA-220" under the conditions of a temperature of 23°C, a frequency of 1 Hz, and an initial strain of 1 N.

[0126] (A) Preparation of polarizing element Polyvinyl alcohol with an average degree of polymerization of about 2,400 and a degree of saponification of 99.9 mol % or more A polyvinyl alcohol film having a thickness of 75 μm was prepared. This polyvinyl alcohol film was uniaxially stretched by about 5 times in a dry state, and further immersed in pure water at 60 ° C for 1 minute while maintaining a tension state. Then, the polyvinyl alcohol film was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5 / 100 at 28 ° C for 60 seconds. Then, the polyvinyl alcohol film was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the polyvinyl alcohol film was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C. In this way, a polarizing element having a thickness of 28 μm in which iodine was adsorbed and aligned in the polyvinyl alcohol was obtained.

[0127] (B) Preparation of adhesive 50 g of a modified PVA resin containing an acetoacetyl group (Mitsubishi Chemical Corporation: Gohsenex Z-410) was dissolved in 950 g of pure water, heated at 90° C. for 2 hours, and then cooled to room temperature to obtain a PVA solution.

[0128] The PVA solution, maleic acid, and glyoxal were added to the following concentrations of each compound. A PVA-based adhesive was prepared by mixing the above and pure water.

[0129] PVA concentration 3.0% by weight Maleic acid 0.01% by weight Glyoxal 0.15% by weight

[0130] (C) Saponification of cellulose acylate film A commercially available cellulose acylate film TD40 (manufactured by Fujifilm Corporation: film thickness 40 μm) was immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) kept at 55° C. for 2 minutes, and then the film was washed with water. Thereafter, the film was immersed in a 0.05 mol / L sulfuric acid aqueous solution at 25° C. for 30 seconds, and then passed through a water washing bath under running water for 30 seconds to neutralize the film. Then, the film was drained three times with an air knife to remove water, and then it was allowed to stay in a drying zone at 70° C. for 15 seconds and dried to produce a saponified film. The moisture permeability of the saponified film at a temperature of 40°C and a relative humidity of 90% is 850g / m 2 ·day.

[0131] (D) Preparation of a laminate of a retardation film and a retardation layer It was produced according to

[0106] to

[0109] of International Publication No. 2018 / 207798. An unstretched cycloolefin polymer film (manufactured by JSR Corporation, product name Arton Film) was uniaxially stretched to produce a cycloolefin polymer film (tensile modulus at 23 ° C. = 2742 MPa, in-plane retardation value Re = 110 nm at a wavelength of 550 nm, retardation value Rth = 55 nm in the thickness direction at a wavelength of 550 nm, film thickness 24 μm). A composition containing a rod-shaped liquid crystal compound was applied onto this cycloolefin polymer film (retardation film) to form a retardation layer (in-plane retardation value Re = 0 nm at a wavelength of 550 nm, retardation value Rth = -100 nm in the thickness direction at a wavelength of 550 nm) which is a positive C layer.

[0132] (E) Preparation of optical laminate (Preparation of Polarizing Plate 1) The laminate of the retardation film and the retardation layer prepared above, the polarizing element, and the saponified cellulose acylate film (first protective film) were bonded together using a PVA adhesive so that the absorption axis of the polarizing element and the slow axis of the retardation film were parallel to each other. At this time, the laminate of the retardation film and the retardation layer (positive C layer) was bonded so that the retardation layer (positive C layer) side was on the polarizing element side. The adhesive strength between the retardation film and the polarizing element and the adhesive strength between the cellulose acylate film and the polarizing element were sufficient for practical use.

[0133] (Measurement of equilibrium moisture content) The polarizing plate 1 obtained above was stored for 72 hours at a temperature of 20°C and a relative humidity of 30%, 35%, 40%, 45%, or 50%, and the moisture content was measured using the Karl Fischer method after 66, 69, and 72 hours of storage. The moisture content did not change after 66, 69, and 72 hours of storage under any humidity condition. Therefore, the moisture content of the polarizing plate 1 can be considered to be the same as the equilibrium moisture content in the storage environment. When the moisture content of the polarizing plate reaches equilibrium at a certain storage temperature, the moisture content of the polarizing element in the polarizing plate can also be considered to have reached equilibrium at that storage temperature. In addition, when the moisture content of the polarizing element in the polarizing plate reaches equilibrium in a certain storage environment, the moisture content of the polarizing plate can also be considered to have reached equilibrium in that storage environment.

[0134] The moisture content of the polarizing plate 1 obtained above immediately after drying was measured by the Karl Fischer method and compared with the above equilibrium moisture content. The moisture content of the polarizing plate 1 was equivalent to the moisture content at a temperature of 20°C and a relative humidity of 40%. Polarizing plate 1 was further stored for 72 hours under the conditions of a temperature of 20°C and a relative humidity of 40%. Ta.

[0135] (F) Preparation of anti-reflection film (Preparation of anti-glare hard coat film) A solution of 50 parts by weight of ultraviolet-curable urethane acrylate monomer (refractive index 1.51), 50 parts by weight of ultraviolet-curable acrylate monomer (refractive index 1.51), 14 parts by weight of methyl methacrylate-styrene copolymer beads (refractive index 1.55) with an average particle size of 3.5 μm, 5 parts by weight of benzophenone-based photopolymerization initiator, and toluene was mixed to obtain a solid content concentration of 40% by weight, which was applied onto a 40 μm-thick triacetyl cellulose film (refractive index 1.49) and dried at 120° C. for 5 minutes. Then, a curing process was performed by irradiating ultraviolet rays to form an antiglare hard coat layer with a thickness of about 4 μm having an uneven structure on the surface, and an antiglare hard coat film was produced. The arithmetic average roughness Ra of this antiglare hard coat layer was 0.43 nm.

[0136] (Preparation of anti-reflection film 1) According to the embodiment of JP2019-035969A, the above-mentioned antiglare hard-coated film was introduced into a roll-to-toll sputtering deposition apparatus, and while the film was running, bombardment treatment (plasma treatment with Ar gas) was performed on the antiglare hard-coated layer formation surface. Thereafter, a 5 nm SiOx layer (x<2) was formed as an adhesion improving layer, and a 20 nm Nb2O5 layer, a 35 nm SiO2 layer, a 35 nm Nb2O5 layer, and a 100 nm SiO2 layer were sequentially formed thereon to form a 4-layer antireflection layer having a thickness of 190 nm. A fluorine-based resin was formed as an antifouling layer on the antireflection layer to a thickness of 5 nm to produce antireflection film 1. The moisture permeability of antireflection film 1 at a temperature of 40°C and a relative humidity of 90% was 5 g / m 2 ·day.

[0137] (Preparation of anti-reflection films 2 and 3) The film formation conditions were changed with reference to the examples in JP 2017-227898 A, and antireflection films 2 and 3, which have different moisture permeabilities from antireflection film 1, were produced. The moisture permeabilities of antireflection films 2 and 3 at a temperature of 40° C. and a relative humidity of 90% were 10 g / m 2 day and 60g / m 2 ·day.

[0138] (Preparation of Anti-Reflection Film 4) Antireflection film 4 was produced in the same manner as antireflection film 1, except that the antireflection layer was formed by coating rather than sputtering, and the layer structure of the antireflection layer was as follows. The moisture permeability of antireflection film 4 at a temperature of 40°C and a relative humidity of 90% was 300 g / m 2 ·day.

[0139] The antireflection layer was formed with the following three-layer structure by referring to paragraph

[0105] of JP-A-2004-126220. 1st layer: Medium refractive index layer (refractive index: 1.63, thickness: 67 nm) 2nd layer: High refractive index layer (refractive index: 1.90, thickness: 107 nm) 3rd layer: Low refractive index layer (refractive index: 1.43, film thickness: 86 nm)

[0140] (G) Preparation of adhesive layer Adhesive layer A: A commercially available sheet-like acrylic adhesive layer with 38 μm PET film with release agent on both sides. The adhesive layer has a thickness of 5 μm and a storage modulus of 0.14 MPa. Adhesive layer B: A commercially available sheet-like acrylic adhesive layer with 38 μm PET film with release agent on both sides. The thickness of the adhesive layer is 25 μm, and the storage modulus is 0.06 MPa.

[0141] [Example 1] The pressure-sensitive adhesive layer A was attached to the surface of the antireflection film 1 prepared above, on which no antireflection layer was laminated. When these materials were attached to each other, a corona treatment was performed on the surface to be attached of each material.

[0142] An antireflection film 1 was laminated on the surface of the cellulose acylate film (first protective film) of the polarizing plate 1 prepared above via an adhesive layer A, and an adhesive layer B was laminated on the surface of the retardation film to prepare an optical laminate of Example 1. When these materials were laminated together, a corona treatment was performed on the lamination surface of each material. The obtained optical laminate had a layer structure of "antireflection film 1 / adhesive layer A / polarizing plate 1 / adhesive layer B / PET with release agent."

[0143] The moisture content of the obtained optical laminate was adjusted by storing it for 72 hours under the same conditions as those for storing the polarizing plate for 72 hours so that the moisture content of the optical laminate was equivalent to that of the polarizing plate used to construct the optical laminate. By storing the optical laminate for 72 hours, it can be considered that the moisture content of the polarizing plate and the polarizing element in the optical laminate has reached equilibrium in the storage environment, and the moisture content of the polarizing plate and the polarizing element in the optical laminate can also be considered to have reached equilibrium in the storage environment. In addition, when the moisture content of the polarizing plate or the polarizing element in the optical laminate reaches equilibrium in a certain storage environment, the moisture content of the optical laminate can also be considered to have reached equilibrium in the 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%.

[0144] [Examples 2 to 4] The optical laminates of Examples 2 to 4 were produced in the same manner as in Example 1, except that in the production of the optical laminate of Example 1, the antireflection films were changed to 2 to 4. Thereafter, the moisture content of the optical laminate was adjusted to be equivalent to that of the polarizing plate used by storing it for an additional 72 hours under the same conditions as those for storing the polarizing plate for 72 hours.

[0145] [Comparative Example 1] An adhesive layer B was attached to the retardation film surface of the polarizing plate 1 to prepare an optical laminate of Comparative Example 1. When these materials were attached to each other, a corona treatment was performed on the attachment surface of each material. The obtained optical laminate had a layer structure of "polarizing plate 1 / adhesive layer B / PET with release agent".

[0146] [evaluation] (Reflection) The obtained optical laminate was cut to a size of 200 mm × 200 mm, and was attached to an alkali-free glass having a thickness of 0.7 mm and a size of 300 mm × 300 mm via the adhesive layer B. The adhesive layer B was laminated on the polarizing plate 1, and the plate was cut to a size of 200 mm × 200 mm. The polarizing plate 1 was attached to the side of the alkali-free glass to which the optical laminate was not attached via the adhesive layer B so that the absorption axes of the polarizing plates were in a crossed Nicol state, thereby preparing an evaluation sample.

[0147] The evaluation sample prepared above was placed on an observation table with the anti-reflection film facing the viewing side, and a tabletop fluorescent lamp was irradiated from an angle. The reflection in the mirror direction relative to the irradiation direction was evaluated according to the following criteria. The evaluation results are shown in Table 1. A: There is no fluorescent light reflection at all. B: The fluorescent light reflection is barely visible. C: Fluorescent light reflections are slightly visible. D: The reflection of the fluorescent light is clearly visible.

[0148] (Crack evaluation) The evaluation sample prepared above was stored in a heating environment at 105°C for 500 hours, and then The film was cooled to 3°C (room temperature). It was then stored in an environment of 23°C and 55% relative humidity for 30 days (one month), and the retardation film was visually observed to check for the occurrence of cracks. Furthermore, the retardation film was visually observed in the same manner every 30 days for a total of 360 days to check for the presence or absence of cracks. The results are shown in Table 1.

[0149] [Table 1] [Explanation of symbols]

[0150] 10 polarizing element, 11 first protective film, 20 anti-reflection film, 30 retardation film, 100 optical laminate.

Claims

1. An optical laminate having a retardation film, a polarizing element, and an antireflection film in this order, The retardation film has a tensile modulus of elasticity at 23° C. of 3000 MPa or less, The polarizing element has a moisture content equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%, The following requirement (i) and the following requirement (ii): (i) The anti-reflection film has a moisture permeability of 300 g / m at a temperature of 40° C. and a relative humidity of 90%. ２ ・ Day or less, (ii) Between the polarizing element and the antireflection film, a moisture permeability of 300 g / m at a temperature of 40° C. and a relative humidity of 90% is ２ -Has a protective film that is less than day An optical laminate that satisfies at least one of the above.

2. An optical laminate having a retardation film, a polarizing element, and an antireflection film in this order, The retardation film has a tensile modulus of elasticity at 23° C. of 3000 MPa or less, The optical laminate has a moisture content equal to or higher than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20° C. and a relative humidity of 48%, The following requirement (i) and the following requirement (ii): (i) The anti-reflection film has a moisture permeability of 300 g / m at a temperature of 40° C. and a relative humidity of 90%. ２ ・ Day or less, (ii) Between the polarizing element and the antireflection film, a moisture permeability of 300 g / m at a temperature of 40° C. and a relative humidity of 90% is ２ -Has a protective film that is less than day An optical laminate that satisfies at least one of the above.

3. The optical laminate according to claim 1 , further comprising a protective film between the polarizing element and the antireflection film.

4. 4. The polarizing plate according to claim 1, wherein the retardation film is made of a cyclic olefin resin.

5. 5. The polarizing plate according to claim 1, wherein the retardation film has an in-plane retardation value of 80 nm or more at a wavelength of 550 nm.

6. The anti-reflection film includes a substrate film and an anti-reflection layer provided on a surface of the substrate film, The optical laminate according to any one of claims 1 to 5, wherein the antireflection layer is made of a plurality of thin films having different refractive indices.

7. The anti-reflection layer is made of silicon dioxide (SiO ２ The optical laminate according to claim 6, comprising a thin film mainly composed of

8. The anti-reflection layer is made of niobium pentoxide (Nb ２ O ５ ) or titanium dioxide (TiO ２ The optical laminate according to claim 6 or 7, comprising a thin film mainly composed of

9. The optical laminate according to any one of claims 6 to 8, wherein the antireflection layer has a thickness of 100 nm to 350 nm.

10. The anti-reflection film is a hard film provided between the base film and the anti-reflection layer. The optical laminate according to any one of claims 6 to 9, further comprising a hard coat layer.

11. A display cell and the optical laminate according to any one of claims 1 to 10, A display device, wherein the optical laminate is laminated on a viewing side surface of the display cell in an orientation in which the polarizing element and the anti-reflection film are disposed in this order from the display cell side.

12. A method for producing the optical laminate according to claim 1, A method for producing an optical laminate, comprising a moisture content adjusting step of adjusting the moisture content of the polarizing element so that it is equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

13. A method for producing the optical laminate according to claim 2, A method for producing an optical laminate, comprising a moisture content adjusting step of adjusting the moisture content of the optical laminate to be equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%.

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