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 manufacturing an optical laminate.

Background Art

[0002] Liquid crystal display devices (LCDs) are widely used not only in liquid crystal televisions but also in mobile devices such as personal computers and mobile phones, and in-vehicle applications such as car navigation systems. Usually, a liquid crystal display device has a liquid crystal panel member in which polarizing plates are bonded 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 EL display devices have also been widely used in recent years in the same applications as liquid crystal display devices, such as televisions, mobile devices such as mobile phones, and in-vehicle applications such as car navigation systems. In liquid crystal display devices and organic EL display devices, a retardation film is used to impart functions such as an enlarged viewing angle and prevention of external light reflection.

[0003] As described above, polarizing plates, as members of liquid crystal display devices and organic EL display devices, are increasingly being mounted in vehicles. A polarizing plate used in an in-vehicle image display device is often exposed to a high-temperature environment compared to other mobile applications such as televisions and mobile phones, and is required to have small characteristic changes at higher temperatures (high-temperature durability).

[0004] On the other hand, an in-vehicle display device requires a touch panel function when used in applications such as car navigation. In recent years, the ratio of on-cell and in-cell types has been increasing among touch panels. In this application, since the polarizing plate on the viewing side is arranged on the outermost side, in addition to the above durability, an anti-reflection function is also required.

[0005] Japanese Patent Application Laid-Open No. 2011-081219 (Patent Document 1) discloses the use of an antiglare hard coat film in which an antireflection layer having a multilayer structure 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. Patent Document 3 also describes a polarizing plate including a retardation film using a cyclic olefin resin as a λ / 4 plate for the purpose of preventing external light from reflecting.

[0007] Such a polarizing plate has good visibility after being laminated on a display device. Even if no cracks occur after a heat durability test (500 hours at 105°C), it has been found that cracks may occur in the retardation film when stored in an environment of 23°C and 55% relative humidity for about one month.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to solve the above problems, and to provide an optical laminate that has a good anti-reflection function even when using a retardation film that adds a function to an image display device, and does not cause cracks in the retardation film even when stored in an environment of 23°C and 55% relative humidity for one month after a heat durability test.

Means for Solving the Problems

[0010] The present invention provides the following optical laminate, display device, and method for manufacturing an optical laminate. [1] An optical laminate having a retardation film, a polarizing element, and an anti-reflection film in this order, The retardation film has a tensile elastic modulus of 3000 MPa or less at 23°C, The polarizing element has a moisture content that 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%, The following requirement (i) and the following requirement (ii): (i) The anti-reflection film has a moisture permeability of 300 g / m 2 ·day or less at a temperature of 40°C and a relative humidity of 90%, (ii) There is a protective film with a moisture permeability of 300 g / m 2 ·day or less between the polarizing element and the anti-reflection film at a temperature of 40°C and a relative humidity of 90%, An optical laminate that satisfies at least one of the above. [2] An optical laminate having a retardation film, a polarizing element, and an anti-reflection film in this order, The retardation film has a tensile elastic modulus of 3000 MPa or less at 23°C, The optical laminate has a moisture content that 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%, The following requirement (i) and the following requirement (ii): (i) The anti-reflection film has a moisture permeability of 300 g / m 2 ·day or less at a temperature of 40°C and a relative humidity of 90%, (ii) There is a protective film with a moisture permeability of 300 g / m 2 ·day or less between the polarizing element and the anti-reflection film at a temperature of 40°C and a relative humidity of 90%, An optical laminate that satisfies at least one of the above. [3] The optical laminate according to [1] or [2], having a protective film between the polarizing element and the anti-reflection 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 in-plane retardation value of the retardation film at a wavelength of 550 nm is 80 nm or more. [6] The antireflection film includes a base film and an antireflection layer provided on the surface of the base film, The antireflection layer is composed of a plurality of thin films having different refractive indices, and the optical laminate according to any one of [1] to [5]. [7] The antireflection layer includes a thin film mainly composed of silicon dioxide (SiO 2 ), and the optical laminate according to [6]. [8] The antireflection layer includes a thin film mainly composed of niobium pentoxide (Nb 2 O 5 ) or titanium dioxide (TiO 2 ), and the optical laminate according to [6] or [7]. [9] The antireflection layer has a thickness of 100 nm to 350 nm, and the optical laminate according to any one of [6] to [8].

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

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

[10] , wherein the optical laminate is laminated on the visual recognition side surface of the display cell in an order of the polarizing element and the antireflection film from the display cell side.

[12] A method for manufacturing the optical laminate according to [1], the method for manufacturing an optical laminate having a moisture content adjustment 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 manufacturing the optical laminate according to [2], the method for manufacturing an optical laminate having a moisture content adjustment step of adjusting the moisture content of the optical laminate 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%.

Advantages of the Invention

[0011] According to the present invention, even when an optical laminate including a retardation film having a function added to an image display device is used, an anti-reflection function is good, and no crack occurs in the retardation film even when stored in an environment of a temperature of 23°C and a relative humidity of 55% for one month after a heat durability test. An object is to provide an optical laminate.

Brief Description of Drawings

[0012]

Figure 1

Embodiments for Carrying Out the Invention

[0013] [Optical laminate] The optical laminate according to an 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 surface of the polarizing element on the anti-reflection film side, or a protective film (hereinafter, also referred to as "second protective film") laminated on the surface of the polarizing element opposite to the anti-reflection film side. In the present 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. Further, in the present specification, the polarizing plate includes the polarizing element, and when it has the first protective film and / or the second protective film laminated on the polarizing element, it refers to a laminate including these.

[0014] FIG. 1 is an example of a schematic cross-sectional view showing 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 anti-reflection film 20, and further includes a first protective film 11 laminated on the surface of the polarizing element 10 on the anti-reflection 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 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%. (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%. Regarding the above (a), 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%. More preferably, 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 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%. More preferably, 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 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 laminate satisfies at least one of the following requirement (i) and the following requirement (ii). (i) The moisture permeability of the anti-reflection film at a temperature of 40°C and a relative humidity of 90% is 300 g / m 2 ·day or less. (ii) There is a protective film with a moisture permeability of 300 g / m 2 ·day or less at a temperature of 40°C and a relative humidity of 90% between the polarizing element and the anti-reflection film. Satisfying the above requirement (ii) means the same thing as satisfying the following requirement (iia). (iia) It has a first protective film laminated on the surface of the polarizing element on the anti-reflection film side, with a moisture permeability of 300 g / m 2 ·day or less at a temperature of 40°C and a relative humidity of 90%.

[0017] In the optical laminate of this embodiment, the water content of the polarizing element is within the above range, and by satisfying at least one of the above requirements (i) and (ii), no cracks (fractures) occur in the retardation film after the heat endurance test (500 hours at 105°C), and furthermore, when stored in an environment of 23°C and 55% relative humidity for about one month, the occurrence of cracks in the retardation film can be suppressed. Although the detailed mechanism is unknown, it is considered that by setting the moisture permeability of the antireflection film and the first protective film within a predetermined range, the migration of moisture to the polarizing element is suppressed, and dimensional changes during storage can be suppressed, so the occurrence of cracks in the retardation film can be suppressed.

[0018] <Polarizing element> As the polarizing element, a polarizing element in which a dichroic dye is adsorbed and oriented on a layer containing a polyvinyl alcohol (hereinafter, also referred to as "PVA") - based resin (also referred to as "PVA - based resin layer" in this specification) can be used. As such a polarizing element, one formed by using a PVA - based resin film, dyeing this PVA - based resin film with a dichroic dye, and uniaxially stretching it, or a laminated film obtained by applying a coating solution containing a PVA - based resin on a base film can be used. The PVA - based resin layer, which is the coating layer of this laminated film, is dyed with a dichroic dye, and the laminated film is uniaxially stretched.

[0019] The polarizing element is formed from a PVA - based resin obtained by saponifying a polyvinyl acetate - based resin. Examples of the polyvinyl acetate - based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other copolymerizable monomers include unsaturated carboxylic acids, olefins such as ethylene, vinyl ethers, unsaturated sulfonic acids, and the like.

[0020] The saponification degree of the PVA-based resin is preferably about 85 mol% or more, more preferably about 90 mol% or more, and still more preferably about 99 mol% to 100 mol%. The degree of polymerization of the PVA-based resin is 1000 to 10000, preferably 1500 to 5000. This PVA-based resin may be modified, 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 still more preferably 8 to 25 μm. When the thickness of the polarizing element is 50 μm or less, the influence of the polyene formation of the PVA-based resin on the deterioration of optical properties under a high-temperature environment can be suppressed, and when the thickness of the polarizing element is 5 μm or more, it becomes easy to achieve a configuration for achieving desired optical properties.

[0022] The single transmittance of the visual sensitivity correction of the polarizing element is preferably 38.8% to 44.8%, more preferably 40.4% to 43.2%, and still more preferably 40.7% to 43.0%. When the single transmittance of the visual sensitivity correction exceeds 44.8%, the deterioration of optical properties such as red discoloration may increase under a high-temperature environment, and when the single transmittance of the visual sensitivity correction is less than 38.8%, polyene formation tends to proceed under a high-temperature environment and the deterioration of optical properties may increase.

[0023] The single transmittance of the visual sensitivity correction can be obtained by measuring the Y value after visual sensitivity correction with a 2-degree field of view (C light source) specified in JIS Z8701-1982. The single transmittance of the visual sensitivity correction can be easily measured, for example, with a spectrophotometer (model number: V7100) manufactured by JASCO Corporation.

[0024] (Feature (a)) When having the characteristic (a), 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%. Preferably, it is 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%. More preferably, it is equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 42%, still more preferably, it is equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 40%, and most preferably, it is equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 38%. When it is below the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, the handleability of the polarizing element deteriorates and it is prone to cracking. By being equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%, an optical laminate excellent in wet heat durability and high temperature durability can be provided. It is presumed that when the moisture content of the polarizing element is high, the polyene formation of the PVA-based resin contained in the polarizing element tends to proceed. The above moisture content of the polarizing element is the moisture content of the polarizing element in the optical laminate.

[0025] As a method for confirming whether 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%, there are a method of storing the polarizing element in an environment adjusted to the above temperature and relative humidity range for a certain period of time and confirming that there is no change in mass, or a method of calculating in advance the equilibrium moisture content of the polarizing element in an environment adjusted to the above temperature and relative humidity range and comparing the moisture content of the polarizing element with the pre-calculated equilibrium moisture content. When the polarizing element is stored for a certain period of time and there is no change in its mass, it can be considered that the moisture content has reached equilibrium in the storage environment.

[0026] The method for manufacturing a polarizing element having 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% is not particularly limited. For example, there are a method of storing the polarizing element in an environment adjusted to the above temperature and relative humidity range for 10 minutes or more and 3 hours or less, or a method of performing heat treatment at 30°C or higher and 90°C or lower.

[0027] As another preferred method for manufacturing a polarizing element having the above moisture content, a laminate in which a protective film is laminated on at least one side of the polarizing element, or a laminate formed using the polarizing element, is stored in an environment adjusted to the above temperature and relative humidity range for 10 minutes or more and 120 hours or less, or a method of heat treatment at 30°C or more and 90°C or less can be mentioned. When manufacturing an image display device, a method of storing an image display panel in which an optical laminate is laminated on an image display cell in an environment adjusted to the above temperature and relative humidity range for 10 minutes or more and 3 hours or less, or heat treatment at 30°C or more and 90°C or less can also be mentioned.

[0028] The moisture content of the polarizing element is preferably adjusted so that the moisture content is within the above numerical range at the material stage used to form the optical laminate, which is either the polarizing element alone or a laminate of the polarizing element and the protective film. When the moisture content is adjusted after forming the optical laminate, the curl may become too large, and problems may easily occur when bonding to the image display cell. By forming the optical laminate using a polarizing element adjusted to have the above moisture content at the material stage before forming the optical laminate, an optical laminate including a polarizing element whose moisture content satisfies the above numerical range can be easily formed. Even when the moisture content of the polarizing element in the optical laminate is adjusted so as to be within the above numerical range in a state where the optical laminate is bonded to the image display cell. In this case, since the optical laminate is bonded to the image display cell, curl is less likely to occur.

[0029] (Feature (b)) When it has the characteristic (b), the moisture content of the optical laminate is not less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, and not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%. Preferably, it is not less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30%, and not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 45%. More preferably, it is not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 42%, still more preferably, it is not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 40%, and most preferably, it is not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 38%. When 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 handleability of the optical laminate deteriorates and it becomes prone to cracking. When the moisture content of the optical laminate exceeds the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%, the transmittance of the polarizing element tends to decrease. It is presumed that this is because when the moisture content of the optical laminate is high, the polyene formation of the PVA-based resin tends to proceed.

[0030] As a method for confirming whether the moisture content of the optical laminate is within the range not less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48%, there are a method of storing the optical laminate in an environment adjusted to the above temperature and relative humidity range for a certain period of time and confirming that there is no change in mass, or a method of calculating in advance the equilibrium moisture content of the optical laminate in an environment adjusted to the above temperature and relative humidity range and comparing the moisture content of the optical laminate with the pre-calculated equilibrium moisture content. When the optical laminate is stored for a certain period of time and there is no change in its mass, it can be considered that the moisture content has reached equilibrium in the storage environment.

[0031] The method for manufacturing an optical laminate having a moisture content not less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20% and not more than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 48% is not particularly limited. For example, there are a method of storing the optical laminate in an environment adjusted to the above temperature and relative humidity range for 10 minutes or more and 3 hours or less, or a method of performing a heat treatment at 30°C or more and 90°C or less.

[0032] When manufacturing the image display device, there is also a method of storing an image display panel in which an optical laminate is laminated on an image display cell in an environment adjusted to the above temperature and relative humidity range for 10 minutes or more and 3 hours or less, or performing a heat treatment at 30°C or more and 90°C or less.

[0033] (Method for manufacturing a polarizing element) The method for manufacturing the polarizing element is not particularly limited, but a method of feeding out a polyvinyl alcohol-based resin film wound in a roll shape in advance and performing stretching, dyeing, crosslinking, etc. (hereinafter referred to as "manufacturing method 1"), or a method of applying a coating liquid containing a polyvinyl alcohol-based resin on a base film to form a polyvinyl alcohol-based resin layer as a coating layer, and then stretching the obtained laminate (hereinafter referred to as "manufacturing method 2") is typical.

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

[0035] The swelling process is a treatment process of immersing the polyvinyl alcohol-based resin film in a swelling bath, which can remove dirt and blocking agents on the surface of the polyvinyl alcohol-based resin film, and can suppress uneven dyeing by swelling the polyvinyl alcohol-based resin film. Usually, a medium mainly composed of water such as water, distilled water, or pure water is used as the swelling bath. Surfactants, alcohols, etc. may be appropriately added to the swelling bath 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. Also, the immersion time in the swelling bath cannot be determined unconditionally because the degree of swelling of the polyvinyl alcohol-based resin film is affected by the temperature of the swelling bath, but it 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 step is a treatment step of immersing the polyvinyl alcohol-based resin film in a dyeing bath (iodine solution), and a dichroic substance such as iodine or a dichroic dye can be adsorbed and oriented on the polyvinyl alcohol-based resin film. The iodine solution is usually preferably an aqueous iodine solution and contains iodine and an iodide as a dissolution aid. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, etc. Among these, potassium iodide is preferable from the viewpoint of controlling the potassium content in the polarizing element.

[0038] In the dyeing bath, the concentration of iodine is preferably about 0.01 to 1% by weight, more preferably about 0.02 to 0.5% by weight. In the dyeing bath, the concentration of the iodide 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 dyeing bath is preferably about 10 to 50 °C, more preferably about 15 to 45 °C, and even more preferably about 18 to 30 °C. Also, the immersion time in the dyeing bath cannot be determined unconditionally because the degree of dyeing of the polyvinyl alcohol-based resin film is affected by the temperature of the dyeing bath, but it 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 a plurality of times as necessary.

[0040] The crosslinking process is a treatment process in which the polyvinyl alcohol-based resin film dyed in the dyeing process 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 on the crosslinked structure. Examples of the boron compound include boric acid, borate, borax, etc. The crosslinking bath is generally an aqueous solution, but may be, for example, a mixed solution of an organic solvent miscible with water and water. Also, from the viewpoint of controlling the potassium content in the polarizing element, the crosslinking bath preferably contains potassium iodide.

[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 even more preferably about 2 to 5% by weight. Also, 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 even 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. Also, the immersion time in the crosslinking bath cannot be determined unconditionally because the degree of crosslinking of the polyvinyl alcohol-based resin film is affected by the temperature of the crosslinking bath, but it is preferably about 5 to 300 seconds, and more preferably about 10 to 200 seconds. The crosslinking process may be carried out only once, or may be carried out a plurality of times as necessary.

[0043] The stretching process is a processing step of stretching a polyvinyl alcohol-based resin film at a predetermined magnification in at least one direction. Generally, the polyvinyl alcohol-based resin film is uniaxially stretched in the conveying direction (longitudinal direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method can be adopted. The stretching process may be carried out only once, or may be carried out a plurality of times as necessary. The stretching process may be carried out at any stage in the manufacture of the polarizing element.

[0044] As the treatment bath (stretching bath) in the wet stretching method, usually, a solvent such as water or a mixed solution of a water-miscible organic solvent and water can be used. 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 even more preferably about 3 to 6% by weight. Further, the treatment bath (stretching bath) can contain a boron compound from the viewpoint of suppressing film breakage during stretching. 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 even 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. Also, the immersion time in the stretching bath cannot be determined unconditionally because the degree of stretching of the polyvinyl alcohol-based resin film is affected by the temperature of the stretching bath, but it is preferably about 10 to 800 seconds, and more preferably about 30 to 500 seconds. Incidentally, the stretching treatment in the wet stretching method may be carried out together with any one or more of the treatment steps of a swelling step, a dyeing step, a crosslinking step, and a washing step.

[0046] Examples of the dry stretching method include an in-roll stretching method, a heated roll stretching method, and a compression stretching method. Incidentally, the dry stretching method may be carried out together with a drying step.

[0047] The total draw ratio (cumulative draw ratio) applied to the polyvinyl alcohol-based resin film can be appropriately set according to the purpose, but it 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 washing step is a treatment step of immersing the polyvinyl alcohol-based resin film in a washing bath, and can remove foreign substances remaining on the surface of the polyvinyl alcohol-based resin film. Usually, a medium mainly composed of water such as water, distilled water, or pure water is used as the washing bath. Also, from the viewpoint of controlling the potassium content in the polarizing element, it is preferable to use potassium iodide in the washing bath. In this case, the concentration of potassium iodide in the washing 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 washing bath is preferably about 5 to 50°C, more preferably about 10 to 40°C, and even more preferably about 15 to 30°C. Also, the immersion time in the washing bath cannot be determined unconditionally because the degree of washing of the polyvinyl alcohol-based resin film is affected by the temperature of the washing bath, but it is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and even more preferably about 3 to 20 seconds. The washing step may be carried out only once, or may be carried out a plurality of 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. Drying is performed by any appropriate method, for example, natural drying, blow drying, or heat drying.

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

[0052] (Retardation film) As the retardation film, one having a tensile elastic modulus of 3000 MPa or less at 23°C is used. Even with such a retardation film having a tensile elastic modulus, according to the present invention, cracks can be prevented. The lower limit value of the tensile elastic modulus at 23°C is not particularly limited, but can be, for example, 1000 MPa or more. As the material of such a retardation film, for example, one made of an olefin-based resin can be used. The olefin-based resin is a resin composed of structural units derived from chain aliphatic olefins such as ethylene and propylene, or alicyclic olefins such as norbornene and its substituents (hereinafter, these are also collectively referred to as norbornene-based monomers). The olefin-based resin may be a copolymer using two or more kinds of 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. Typical examples of the alicyclic olefin constituting the cyclic olefin resin include norbornene-based monomers and the like. Norbornene is a compound in which one carbon-carbon bond of norbornane becomes a double bond, and according to the IUPAC nomenclature, it is named bicyclo[2,2,1]hept-2-ene. Examples of the substituent of norbornene include 3-substituted, 4-substituted, and 4,5-disubstituted products with the double bond position of norbornene being the 1,2-position, and further, dicyclopentadiene, dimethanooctahydronaphthalene, and the like can also be mentioned.

[0054] The cyclic olefin resin may or may not have a norbornane ring in its structural unit. Examples of the norbornene-based monomer that forms a cyclic olefin resin having no norbornane ring in its structural unit include, for example, those that become a 5-membered ring by ring opening, typically, norbornene, dicyclopentadiene, 1- or 4-methylnorbornene, and 4-phenylnorbornene, and the like. When the cyclic olefin resin is a copolymer, the molecular arrangement state thereof is not particularly limited, and it may be a random copolymer, a block copolymer, or a graft copolymer.

[0055] More specific examples of the cyclic olefin resin include, for example, ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers, polymer modified products obtained by adding maleic acid, cyclopentadiene, etc. to them, and polymers or copolymers obtained by hydrogenating these; addition polymers of norbornene-based monomers, and addition copolymers of norbornene-based monomers and other monomers, and the like. Examples of other monomers in the case of forming a copolymer include α-olefins, cycloalkenes, and non-conjugated dienes, and the like. Further, the cyclic olefin resin may be a copolymer using one or more of norbornene-based monomers and other alicyclic olefins.

[0056] Among the above specific examples, as the cyclic olefin resin, a resin obtained by hydrogenating a ring-opening polymer or ring-opening copolymer using a norbornene monomer is preferably used. Such a cyclic olefin resin is made into a film-like material that has been previously stretched, and a shrinkable film having a predetermined shrinkage rate is laminated thereto and heat-shrunk, whereby a retardation film having high uniformity and a large retardation value can be obtained.

[0057] Examples of commercially available products of cyclic olefin resins using such norbornene monomers include "Zeonex" and "Zeonor" sold by Nippon Zeon Co., Ltd. and "Arton" sold by JSR Corporation, all under their respective trade names. Films of these cyclic olefin resins and their stretched films are also commercially available. For example, "Zeonor Film" from Optes Co., Ltd., "Arton Film" from JSR Corporation, and "ESCINA" from Sekisui Chemical Co., Ltd., all under their respective trade names.

[0058] In addition, as the retardation film used in the present invention, 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 can also be used. For example, as the mixed resin containing two or more kinds of olefin resins, a mixture of the above-described cyclic olefin resin and the linear aliphatic olefin resin can be mentioned. 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, polyether sulfone resins, polyether ether ketone 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. In addition, the above thermoplastic resins can also be used after performing any appropriate polymer modification. Examples of polymer modification include copolymerization, crosslinking, molecular end modification, and imparting stereoregularity.

[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, showing good wavelength dispersion characteristics, and excellent in durability, mechanical strength, and transparency can be obtained.

[0060] Such olefin resins can be formed into films by methods such as casting from solution or melt extrusion. When forming a film from a mixture of two or more resins, the film-forming method is not particularly limited. For example, a method of producing a film by the casting method using a uniform solution obtained by stirring and mixing resin components with a solvent at a predetermined ratio, and a method of producing a film by melt-mixing resin components at a predetermined ratio and using the melt extrusion method are employed.

[0061] The above-mentioned retardation film may contain other components such as residual solvent, stabilizer, plasticizer, anti-aging agent, antistatic agent, and ultraviolet absorber, as long as the object of the present invention is not impaired. Further, a leveling agent may be contained to reduce the surface roughness.

[0062] The retardation film used in the present invention is preferably applied to those 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 in the case of having such a high retardation value, no cracks occur in the retardation film even when stored in an environment of a temperature of 23 ° C and a relative humidity of 55% for one month after the heat durability test. Generally, the higher the retardation value, the more uniform the molecular orientation of the retardation film, and there is a tendency that cracks are likely to occur against external force.

[0063] The above-mentioned retardation film can be obtained by known methods such as uniaxial stretching in the longitudinal direction, tenter uniaxial stretching, simultaneous biaxial stretching, and sequential biaxial stretching. In addition to appropriately adjusting the stretching ratio and stretching speed so as to obtain a desired retardation value, various temperatures such as preheating temperature, stretching temperature, heat setting temperature, and 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] As the antireflection film, for example, a film having an antireflection layer on one side of a base film can be used. The base film is not particularly limited, but a material equivalent to that used for the protective film described later can be used.

[0068] As the antireflection film, a known antireflection film or a commercially available antireflection film can be used, and for example, the following are exemplified.

[0069] (a) An antireflection film using the principle of a so-called moth-eye structure, which consists of an uneven pattern with a period of unevenness controlled to be equal to or less than the wavelength of visible light (the antireflection films described in JP-A-2010-122599, JP-T-2001-517319, JP-A-2004-205990, JP-A-2004-287238, JP-A-2001-27505, JP-A-2002-286906, WO2006 / 059686, etc.). As a commercial product, for example, Mossmite (registered trademark, manufactured by Mitsubishi Chemical Corporation) can be used. (b) An antireflection film consisting of a fine uneven pattern that exhibits an optical function (the antireflection films described in JP-A-2004-59822, JP-B-5-46064, JP-B-6-85103, etc.). (c) An antireflection film consisting of an uneven pattern composed of innumerable fine unevennesses with a pitch equal to or less than the wavelength of light (the antireflection films described in JP-A-2001-264520, JP-A-9-80205, etc.). (d) An antireflection film having a single layer or multiple layers of layers with adjusted refractive indices (the antireflection films described in JP-A-2000-187102, JP-A-6-186401, JP-A-2004-345333, etc.). As a commercial product, for example, MTAR and MTAGAR (manufactured by Mikansha Co., Ltd.) can be used. The thickness of the antireflection film is, for example, 10 μm or more and 100 μm or less.

[0070] As the antireflection film, those having a thin film with strictly controlled thickness and refractive index or an antireflection layer formed by laminating two or more thin films are preferred. In this specification, the thin film refers to a film with a thickness of 1 μm or less. The antireflection layer can be configured to exhibit an antireflection function by utilizing the interference effect of light to cancel out the reversed phases of the incident light and the reflected light with each other. The wavelength range of visible light for exhibiting the antireflection function is, for example, 380 to 780 nm, and particularly the wavelength range with high visual sensitivity is in the range of 450 to 650 nm. It is preferable to design the antireflection layer so as to minimize the reflectance at the central wavelength of 550 nm. The thickness of the antireflection layer is preferably 100 nm to 350 nm, and more preferably 150 nm to 300 nm.

[0071] In the design of the antireflection layer based on the interference effect of light, as a means for improving the interference effect, for example, there is a method of increasing the refractive index difference between the antireflection layer and the antiglare hard coat layer described later. Generally, in a multilayer antireflection layer having a structure in which 2 to 15 thin films (thin films with strictly controlled thickness and refractive index) are laminated, by forming a plurality of components with different refractive indices in a predetermined thickness, the degree of freedom in the optical design of the antireflection layer is increased, the antireflection effect can be further improved, and the spectral reflection characteristics can also be made uniform (flat) in the visible light region. Since high thickness accuracy is required for the thin film, generally, the formation of each layer is carried out by dry methods such as vacuum evaporation, sputtering, and CVD. Since the moisture permeability is set within a predetermined range, it is preferable to use sputtering. Further, by using an antireflection film in which each layer is formed by sputtering, an optical laminate with high scratch resistance can be configured.

[0072] As the antireflection layer, those in which a low refractive index layer and a high refractive index layer are alternately laminated are preferably used. The high refractive index layers or the low refractive index layers do not have to have the same refractive index, but it is preferable from the viewpoint of suppressing material costs, film formation costs, etc. to have the same refractive index with the same material.

[0073] As the material constituting the low refractive index layer (or the material serving as the main component of the low refractive index layer), silicon dioxide (SiO 2 ), silicon oxynitride (SiON), gallium oxide (Ga 2 O 3 ), aluminum oxide (Al 2 O 3 ), lanthanum oxide (La 2 O 3 ), lanthanum fluoride (LaF 3 ), magnesium fluoride (MgF 2 ), sodium aluminum fluoride (Na 3 AlF 6 ) and the like can be mentioned. Among them, silicon dioxide (SiO 2 ) is most preferable because of its low refractive index, no absorption in the visible light region, high film strength, etc.

[0074] As the material constituting the high refractive index layer (or the material serving as the main component of the high refractive index layer), niobium pentoxide (Nb 2 O 5 ), titanium dioxide (TiO 2 ), zirconium dioxide (ZrO 2 ), tantalum pentoxide (Ta 2 O 5 ), silicon oxynitride (SiON), silicon nitride (Si 3 N 4 ) and silicon niobium oxide (SiNbO) and the like can be mentioned. Among them, niobium pentoxide (Nb 2 O 5 ) or titanium dioxide (TiO 2 ) is more preferable, and niobium pentoxide (Nb 2 O 5 ) is most preferable because of its high refractive index, high film strength, and no absorption in the visible light region.

[0075] By controlling the composition ratio of the constituent elements to deviate from the stoichiometric ratio or controlling the film formation density for film formation of any compound, the refractive index can be changed to some extent. Note that 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 refractive index conditions. Also, unavoidable impurities may be included.

[0076] The antireflection film may include a hard coat layer between the base film and the antireflection layer. By providing the hard coat layer, the mechanical properties such as the hardness and elastic modulus of the antireflection layer can be improved. The hard coat layer preferably has a 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 base film.

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

[0078] Among these, acrylic resins, acrylic urethane resins, and epoxy resins are preferred because of their high hardness, ultraviolet curability, and excellent productivity. Among them, acrylic urethane resins are particularly preferred. Ultraviolet curable resins include ultraviolet curable monomers, oligomers, polymers, etc. Preferably used ultraviolet curable resins include, for example, those having ultraviolet polymerizable functional groups, and in particular, those containing acrylic monomers or oligomers having two or more, especially 3 to 6, of such functional groups as components.

[0079] In order to impart anti-glare properties and anti-glitter properties to the anti-reflection film, it is preferable that the hard coat layer provided on the surface of the base film 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, various metal oxide fine particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, antimony oxide, glass fine particles, polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate, etc. Cross-linked or uncrosslinked organic fine particles and silicone-based fine particles having transparency can be used without particular limitation. These fine particles can be appropriately selected and used singly or in combination of two or more. Among them, fine particles having a refractive index higher than that of the matrix resin are preferable, and for example, organic fine particles having a refractive index of 1.5 or more such as styrene beads (refractive index 1.59) are preferable. The average particle diameter of the fine particles is preferably 1 to 10 μm, more preferably 2 to 5 μm. The proportion of the fine particles is not particularly limited, but 6 to 20 parts by weight is preferable with respect to 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 on the base film. It is preferable that an ultraviolet polymerization initiator is blended in the solution for forming the hard coat layer. In order to form an anti-glare 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 on the transparent film. Additives such as a leveling agent, a thixotropic agent, and an antistatic agent may be contained in the solution. In the formation of the anti-glare hard coat layer, by containing a thixotropic agent (silica, mica, etc. having a particle diameter of 0.1 μm or less) in the solution, a fine concavo-convex structure due to protruding particles can be easily formed on the surface of the hard coat layer.

[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 or more, 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. Also, in order to maintain a 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 on the formation surface side of the antireflection layer of the base film 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 and may be 0.05 nm or more. When a hard coat layer is formed on the base film, the arithmetic mean roughness of the hard coat layer becomes the arithmetic mean roughness of the surface on the formation surface side of the antireflection layer of the base film. The arithmetic mean roughness Ra is determined from an observation image of 1 μm square using an atomic force microscope (AFM).

[0083] As described above, if the hard coat layer is formed by coating, the arithmetic mean roughness of the surface of the base film can be reduced. If the surface of the base 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 improve.

[0084] <Protective Film> The protective film is not particularly limited, but it is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and stability of retardation value, etc. The material of the protective film is not particularly limited, but for example, methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin, and polyimide resin, etc. Films made of these can be mentioned.

[0085] These resins can be used alone or in combination of two or more. Also, these resins can be used after performing any appropriate polymer modification. Examples of this polymer modification include copolymerization, crosslinking, molecular end modification, stereoregularity control, and modification such as mixing including cases involving reactions between different polymers.

[0086] The cellulose resin can be an organic acid ester or a mixed organic acid ester of cellulose in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are substituted with acetyl groups, propionyl groups, and / or butyryl groups. For example, those composed of cellulose acetate, cellulose propionate, cellulose butyrate, and their mixed esters can be mentioned. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, etc. are preferable.

[0087] These resins may be appropriately blended with additives as long as the transparency is not impaired. Examples of the 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, handleability, etc., it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and even more preferably 15 to 50 μm.

[0089] The protective film may simultaneously have other optical functions and may be formed into a laminated structure in which a plurality of layers are laminated. From the viewpoint of optical properties, a thinner protective film is preferable, but if it is too thin, the strength will decrease and the processability will deteriorate. An appropriate film 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 the polarizing element, when using an aqueous adhesive such as a PVA adhesive for bonding, at least one of the protective films on one side is preferably either a cellulose acylate film or a (meth)acrylic polymer film, and among them, a cellulose acylate film is preferable.

[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 be provided with a surface treatment layer (coating layer) such as an antistatic layer on their outer surfaces (the surfaces opposite to the polarizing element). Note that the thicknesses of the first protective film and the second protective film include the thickness of the surface treatment layer.

[0092] As the first protective film, in order to satisfy the above requirement (ii), the moisture permeability at a temperature of 40 °C and a relative humidity of 90% is 300 g / m 2·A protective film with a water vapor transmission rate of 300 g / m²·day or less can be used. The water vapor transmission rate of the protective film can be adjusted according to materials, thickness, etc. The water vapor transmission rate at a temperature of 40°C and a relative humidity of 90% is 300 g / m²·day or less. 2 ·As the protective film with a water vapor transmission rate of 300 g / m²·day or less, a cyclic olefin resin film, a film with a dry-process laminated water vapor barrier layer, etc. are preferably used.

[0093] On the other hand, when the anti-reflection film satisfies the above requirement (i) and has a water vapor transmission rate of 100 g / m²·day or less at a temperature of 40°C and a relative humidity of 90%, the water vapor transmission rate of the second protective film at a temperature of 40°C and a relative humidity of 90% is preferably 200 g / m²·day or more. 2 ·When the water vapor transmission rate of the anti-reflection film is 100 g / m²·day or less at a temperature of 40°C and a relative humidity of 90%, the water vapor transmission rate of the second protective film at a temperature of 40°C and a relative humidity of 90% is preferably 200 g / m²·day or more. 2 ·It is preferably 200 g / m²·day or more. When manufacturing the optical laminate, as described later, after laminating the second protective film on the polarizing element 10 using an adhesive (adhesive or pressure-sensitive adhesive) such as an aqueous adhesive, a bonding layer is formed by a drying process, and then the first protective film may be laminated. In this case, by setting the water vapor transmission rate of the protective film laminated on the retardation film side of the polarizing element within the above range, it is easy to remove the moisture contained in the adhesive by the drying process.

[0094] At least one of the protective films may have a retardation function for purposes such as viewing angle compensation. In that case, the film itself may have a retardation function, or it may separately have a retardation layer, or it may be a combination of both. Note that the film having a retardation function may be configured to be laminated via another protective film laminated on the polarizing element through an adhesive layer or an adhesive layer.

[0095] <Bonding layer> In the optical laminate, a bonding layer is used to bond each layer. Examples of the bonding layer include an adhesive layer or an adhesive layer.

[0096] (Adhesive layer) The adhesive layer can be used, for example, for attaching a protective film to a polarizing element. As the adhesive constituting the adhesive layer, any appropriate adhesive can be used. As the adhesive, an aqueous adhesive, a solvent-based adhesive, an active energy ray-curable adhesive, etc. can be used, but an aqueous adhesive is preferred.

[0097] The thickness at the time of applying the adhesive can be set to any appropriate value. For example, it is set so that an adhesive layer having a desired thickness can be 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, still 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] (Aqueous adhesive) As the aqueous adhesive, any appropriate aqueous adhesive can be adopted. Among them, an aqueous adhesive containing a PVA-based resin (PVA-based adhesive) is preferably used. From the viewpoint of adhesiveness, the average degree of polymerization of the PVA-based resin contained in the aqueous adhesive is preferably about 100 to 5500, more preferably 1000 to 4500. The average degree of saponification is preferably about 85 mol% to 100 mol% from the viewpoint of adhesiveness, and more preferably 90 mol% to 100 mol%.

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

[0100] A crosslinking agent can also be contained in the aqueous adhesive. Known crosslinking agents can be used as the crosslinking agent. For example, water-soluble epoxy compounds, dialdehydes, isocyanates, etc. can be mentioned.

[0101] When the PVA-based resin is an acetylacetonyl group-containing PVA-based resin, it is preferably any one of glyoxal, glyoxylate, and methylol melamine as the crosslinking agent, more preferably any one of glyoxal and glyoxylate, and particularly preferably glyoxal.

[0102] The aqueous adhesive can also contain an organic solvent. Alcohols are preferable as the organic solvent in terms of being miscible with water, and methanol or ethanol is more preferable among alcohols. Some of the urea-based compounds have low solubility in water but sufficient solubility in alcohol. In that case, it is also a preferred embodiment to dissolve the urea-based compound in alcohol, prepare an alcohol solution of the urea-based compound, and then add the alcohol solution of the urea-based compound to the PVA aqueous solution to prepare the adhesive.

[0103] The concentration of methanol in the aqueous 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. When the concentration of methanol is 10% by mass or more, polyene formation under a high-temperature environment is more easily suppressed. Also, when the content of methanol is 70% by mass or less, deterioration of the hue can be suppressed.

[0104] (Reactive energy ray curable adhesive) An active energy ray-curable adhesive is an adhesive that cures by irradiating active energy rays such as ultraviolet rays. Examples include adhesives containing a polymerizable compound and a photoinitiator, adhesives containing a photoreactive resin, adhesives containing a binder resin and a photoreactive crosslinking agent, and the like. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of the photoinitiator include compounds containing a substance that generates active species such as neutral radicals, anion radicals, and cation radicals upon irradiation with active energy rays such as ultraviolet rays.

[0105] (Adhesive layer) The adhesive layer can be used, for example, for bonding an antireflection film to a 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 based on a (meth)acrylic resin having excellent transparency, weather resistance, heat resistance, etc. as a base polymer is preferable. The adhesive composition may be of an active energy ray-curable type or a thermosetting type. The thickness of the adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.

[0107] As the (meth)acrylic resin (base polymer) used in the adhesive composition, for example, a polymer or copolymer having as a monomer one or more of (meth)acrylic esters 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 with 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, etc., 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 above base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include polyvalent metal ions that form a metal carboxylate with a carboxyl group; polyamine compounds that form an amide bond with a carboxyl group; polyepoxy compounds and 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 preferable.

[0109] The storage modulus of the 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 adhesive layer can be measured according to the method described in the examples below.

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

[0111] In the present invention, as described above, by using an antireflection film in which each layer is formed by sputtering, an optical laminate with high scratch resistance can be configured. In this case, by controlling the storage elastic modulus and the thickness of the adhesive layer used for laminating the antireflection film to the first protective film within the following ranges, it is possible to form an optical laminate with a high indentation hardness typified by pencil hardness and in which the antireflection layer is difficult to crack, which is particularly preferable.

[0112] In particular, the storage elastic modulus of the adhesive layer for laminating the first protective film and the antireflection film is preferably 0.050 to 0.170 MPa, more preferably 0.080 to 0.170 MPa, still more preferably 0.100 to 0.170 MPa, and particularly preferably 0.120 to 0.160 MPa.

[0113] The thickness of the adhesive layer is preferably 3 to 30 μm, more preferably 3 to 20 μm, still more preferably 3 to 10 μm, and particularly preferably 3 to 8 μm.

[0114] [Method for manufacturing an optical laminate] The method for manufacturing the optical laminate of the present embodiment includes a moisture content adjustment step. In the moisture content adjustment step, when manufacturing an optical laminate having feature (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 adjustment step, when manufacturing an optical laminate having feature (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 processes other than the moisture content adjustment process, there may be a lamination process of laminating a polarizing element and a protective film to obtain a polarizing plate, a lamination process of laminating the polarizing plate and an antireflection film, a lamination process of laminating the polarizing plate and a retardation film, etc. to laminate each layer. The order of the moisture content adjustment process and each lamination process is not limited, and the moisture content adjustment process and the lamination process may be performed in parallel.

[0116] [Display device] The above optical laminate can be used in various display devices such as liquid crystal display devices and organic EL display devices. The 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 is excellent in wet heat durability and high temperature durability, it can be suitably used as an in-vehicle display device.

[0117] The display device has a display cell and an optical laminate laminated on the viewing side surface of the display cell. The optical laminate is laminated on the viewing side surface of the display cell in the order of a retardation film, a polarizing element, and an antireflection film from the display cell side. For the lamination of the display cell and the optical laminate, for example, the above-mentioned adhesive layer is used.

[0118] <Display cell> Examples of the display cell include a liquid crystal cell and an organic EL cell. As the liquid crystal cell, any of 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, and a transflective liquid crystal cell that uses both external light and light from a light source may be used. When the liquid crystal cell uses light from a light source, a polarizing plate is also arranged on the side opposite to the viewing side of the display cell (liquid crystal display device), and a light source is further arranged. It is preferable that the polarizing plate on the light source side and the liquid crystal cell are bonded via an appropriate adhesive layer. As the driving method of the liquid crystal cell, for example, any type such as VA mode, IPS mode, TN mode, STN mode, or bend alignment (π type) can be used.

[0119] As an organic EL cell, for example, one formed by sequentially laminating a transparent electrode, an organic light-emitting layer, and a metal electrode on a transparent substrate to form a light-emitting body (organic electroluminescence light-emitting body) is preferably used. The organic light-emitting layer is a laminate of various organic thin films. For example, 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, etc., various layer configurations can be adopted.

Examples

[0120] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited by these examples. In the examples, parts and % representing content or usage amount are based on mass unless otherwise specified. In addition, the measurement of each physical property in the following examples was performed by the following methods.

[0121] [Measurement method] (1) Method for measuring film thickness It was measured using MH-15M, a digital micrometer manufactured by Nikon Corporation.

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

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

[0124] (4) Tensile modulus at 23°C (measured in accordance with JIS K 7161) Test pieces with a width of 15 mm and a length of 150 mm were cut out from the film parallel to the slow axis and the fast axis, respectively. Next, using the upper and lower grips of a tensile testing machine [AUTOGRAPH (registered trademark) AG-1S testing machine manufactured by Shimadzu Corporation], the two ends of the test piece in the long side direction were clamped so that the distance between the grips was 100 mm, and it was pulled at a tensile speed of 50 mm / min in an environment of 23°C to create a stress-strain curve, and the tensile elastic modulus in the directions parallel to the slow axis and the fast axis at 23°C was calculated. Among the tensile elastic moduli in the directions parallel to the slow axis and the fast axis thus calculated, the one with the larger value was taken as the value of the tensile elastic modulus at 23°C in the present invention.

[0125] (5) Storage elastic modulus The storage elastic modulus G' of the adhesive layer was measured according to the following (I) to (III). (I) Two samples of 25 ± 1 mg each were taken out from the adhesive layer and formed into approximately spherical shapes. (II) The obtained approximately spherical samples were attached to the upper and lower surfaces of an I-shaped jig and clamped with an L-shaped jig on both the upper and lower surfaces. The configuration of the measurement sample was L-shaped jig / adhesive layer / I-shaped jig / adhesive layer / L-shaped jig. (III) The storage elastic modulus G' of the sample thus prepared was measured using a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement Control Co., Ltd. under the conditions of a temperature of 23°C, a frequency of 1 Hz, and an initial strain of 1 N.

[0126] (A) Fabrication of polarizing element A polyvinyl alcohol film with a thickness of 75 μm made of polyvinyl alcohol having an average degree of polymerization of about 2,400 and a saponification degree of 99.9 mol% or more was prepared. This polyvinyl alcohol film was uniaxially stretched about 5 times by a dry method, and then immersed in pure water at 60 °C for 1 minute while maintaining the tension. 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. Thus, a polarizing element with a thickness of 28 μm in which iodine was adsorbed and oriented on the polyvinyl alcohol was obtained.

[0127] (B) Preparation of Adhesive 50 g of a modified PVA-based resin containing an acetoacetyl group (manufactured by Mitsubishi Chemical Corporation: Gosenex 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] A PVA-based adhesive was prepared by blending the PVA solution, maleic acid, glyoxal, and pure water so that each compound had the following concentration.

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

[0130] (C) Saponification of Cellulose Acetate Film A commercially available cellulose acetate film TD40 (manufactured by Fujifilm Corporation: film thickness 40 μm) was immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) maintained at 55 °C for 2 minutes, and then the film was washed with water. Then, it was immersed in a 0.05 mol / L sulfuric acid aqueous solution at 25 °C for 30 seconds, and further passed through a water bath under running water for 30 seconds to make the film in a neutral state. Then, water drainage by an air knife was repeated 3 times to remove water, and then it was retained in a drying zone at 70 °C for 15 seconds to be dried, and a saponified film was produced. The water vapor permeability of the saponified film at a temperature of 40 °C and a relative humidity of 90% was 850 g / m 2 ·day.

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

[0106] to

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

[0132] (E) Preparation of an optical laminate (Preparation of Polarizer 1) The laminate of the retardation film and the retardation layer, the polarizing element, and the saponified cellulose acylate film (first protective film) prepared above were bonded together using a PVA-based adhesive so that the absorption axis of the polarizing element and the slow axis of the retardation film were parallel. 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 faced the polarizing element side. The adhesiveness between the retardation film and the polarizing element and the adhesive force 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 at a temperature of 20°C under conditions of relative humidity of 30%, 35%, 40%, 45%, or 50% for 72 hours. The moisture content was measured using the Karl Fischer method at 66 hours, 69 hours, and 72 hours of storage. Under any of the humidity conditions, the value of the moisture content did not change at 66 hours, 69 hours, and 72 hours of storage. Therefore, it can be considered that the moisture content of the polarizing plate 1 is the same as the equilibrium moisture content of the storage environment. When the moisture content of the polarizing plate reaches equilibrium at a certain storage temperature, it can be considered that the moisture content of the polarizing element in the polarizing plate has also reached equilibrium at that storage temperature. Also, when the moisture content of the polarizing element in the polarizing plate reaches equilibrium in a certain storage environment, it can be considered that the moisture content of the polarizing plate has also reached equilibrium in that storage environment.

[0134] The moisture content of the polarizing plate 1 immediately after drying obtained above 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%. The polarizing plate 1 was further stored under the conditions of a temperature of 20°C and a relative humidity of 40% for 72 hours.

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

[0136] (Production of anti-reflection film 1) According to the examples of Japanese Patent Application Laid-Open No. 2019-035969, the above-mentioned antiglare hard coat film was introduced into a roll-to-roll sputtering film-forming apparatus, and while the film was being run, bombardment treatment (plasma treatment with Ar gas) was performed on the antiglare hard coat layer forming surface. Thereafter, a 5-nm SiOx layer (x < 2) was formed as an adhesion improvement layer, and on top of that, 20 nm of Nb 2 O 5 layer, 35 nm of SiO 2 layer, 35 nm of Nb 2 O 5 layer, and 100 nm of SiO 2 layer were successively formed to form an antireflection layer with a four-layer structure and a thickness of 190 nm. On the antireflection layer, a fluorine-based resin was formed as an antifouling layer to a thickness of 5 nm to produce an antireflection film 1. The water vapor permeability of the antireflection film 1 at a temperature of 40°C and a relative humidity of 90% was 5 g / m 2 ·day.

[0137] (Production of antireflection films 2 and 3) With reference to the examples of Japanese Patent Application Laid-Open No. 2017-227898, the film-forming conditions were changed to produce antireflection films 2 and 3 with different water vapor permeabilities from that of the antireflection film 1. The water vapor permeabilities of the antireflection films 2 and 3 at a temperature of 40°C and a relative humidity of 90% were 10 g / m 2 ·day and 60 g / m 2 ·day, respectively.

[0138] (Production of antireflection film 4) An antireflection film 4 was produced in the same manner as the antireflection film 1, except that the antireflection layer was changed from a sputtering method to a coating type, and the layer structure of the antireflection layer was as follows. The water vapor permeability of the 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 an antireflection layer having the following three-layer structure with reference to Japanese Patent Application Laid-Open No. 2004-126220, paragraph

[0105] . First layer Medium refractive index layer (refractive index: 1.63, film thickness: 67 nm) Second layer: High refractive index layer (refractive index: 1.90, film thickness: 107 nm) Third layer: Low refractive index layer (refractive index: 1.43, film thickness: 86 nm)

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

[0141] [Example 1] The adhesive layer A was laminated on the surface of the antireflection film 1 where the antireflection layer was not laminated. When laminating these materials, corona treatment was performed on the bonding surfaces of each material.

[0142] The antireflection film 1 was laminated on the surface of the cellulose acylate film (first protective film) of the polarizing plate 1 prepared above via the adhesive layer A, and the adhesive layer B was laminated on the surface of the retardation film to prepare the optical laminate of Example 1. When laminating these materials, corona treatment was performed on the bonding surfaces 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 a release agent".

[0143] For the obtained optical laminate, the water content of the optical laminate was adjusted by storing it for 72 hours under the same conditions as those under which the polarizing plate used to form it was stored for 72 hours, so that the water content of the optical laminate was equivalent to that of the polarizing plate. By storing the optical laminate for 72 hours, it can be considered that the optical laminate has reached equilibrium in its storage environment, and the water 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. Further, when the water content of the polarizing plate or the polarizing element in the optical laminate reaches equilibrium in a certain storage environment, the water content of the optical laminate can also be considered to have reached equilibrium in the storage environment. Therefore, the water content of the optical laminate is the equilibrium water content at a temperature of 20°C and a relative humidity of 40%.

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

[0145] [Comparative Example 1] An adhesive layer B was laminated on the retardation film surface of the polarizing plate 1 to produce the optical laminate of Comparative Example 1. In addition, when laminating these materials, corona treatment was performed on the laminating surfaces 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 into a size of 200 mm × 200 mm and laminated on non-alkali 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, cut into a size of 200 mm × 200 mm, and the polarizing plate 1 was laminated via the adhesive layer B on the side not laminated with the above non-alkali glass optical laminate so that the absorption axes of the polarizing plates were cross-nicol with each other, to produce an evaluation sample.

[0147] The evaluation sample prepared above was placed on the observation table so that the anti-reflection film was on the visual side, and a desktop fluorescent lamp was irradiated obliquely. With respect to the irradiation direction, the reflection in the mirror direction was evaluated according to the following criteria. The evaluation results are shown in Table 1. A: No reflection of the fluorescent lamp can be seen at all. B: Almost no reflection of the fluorescent lamp can be seen. C: A slight reflection of the fluorescent lamp can be seen. D: The reflection of the fluorescent lamp can be clearly seen.

[0148] (Evaluation of cracks) The evaluation sample prepared above was stored for 500 hours in a heating environment at a temperature of 105 °C and then cooled to 23 °C (room temperature). Then, it was stored in an environment at a temperature of 23 °C and a relative humidity of 55% for 30 days (one month), and the retardation film was visually observed to check for cracks. Furthermore, the retardation film was visually observed in the same way every 30 days until 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. A method for manufacturing an optical laminate having a retardation film, a polarizing element, and an antireflection film in this order, wherein the retardation film has a tensile elastic modulus at 23°C of 3000 MPa or less, the retardation film has a thickness of 18 to 45 μm, the polarizing element has a moisture content that 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%, satisfies at least one of the following requirements (i) and (ii): (i) The anti-reflection film has a moisture permeability of 10 g / m ２ ·day or less at a temperature of 40°C and a relative humidity of 90%. (ii) Between the polarizing element and the antireflection film, there is a protective film with a moisture permeability of 300 g / m ２ ·day or less at a temperature of 40 °C and a relative humidity of 90%, and has a moisture content adjustment step of adjusting the moisture content of the polarizing element so that it 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%, a method for manufacturing an optical laminate.

2. A method for manufacturing an optical laminate having a retardation film, a polarizing element, and an antireflection film in this order, wherein the retardation film has a tensile elastic modulus at 23°C of 3000 MPa or less, the retardation film has a thickness of 18 to 45 μm, the optical laminate has a moisture content that 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%, satisfies at least one of the following requirements (i) and (ii): (i) The anti-reflection film has a moisture permeability of 10 g / m ２ ·day or less at a temperature of 40°C and a relative humidity of 90%. (ii) Between the polarizing element and the antireflection film, there is a protective film with a moisture permeability of 300 g / m ２ ·day or less at a temperature of 40 °C and a relative humidity of 90%, and has a moisture content adjustment step of adjusting the moisture content of the optical laminate so that it 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%, a method for manufacturing an optical laminate.

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