JP7723779B2 - Optical laminate, image display device - Google Patents

Description

The present invention relates to an optical laminate and an image display device including the same.

In image display devices such as organic EL display devices, it is known that circular polarizers are used to improve anti-reflection performance in order to prevent a decrease in visibility due to reflection of external light (see, for example, Patent Document 1). A circular polarizer is an optical laminate that includes a polarizer and a retarder.

International Publication No. 2019/160033

Conventional circular polarizing plates have a problem in that their in-plane retardation characteristics change with continued use, especially at high temperatures. In-plane retardation characteristics refer to the retardation value at each wavelength and wavelength dispersion, and changes in these characteristics result in changes in the reflected hue. Furthermore, when a circular polarizing plate is attached to an image display panel, corrosion of the metal components of the image display panel has been observed for some reason. This problem is particularly likely to become more pronounced when the adhesive on the panel attachment surface contains an antistatic agent. Therefore, the present invention aims to provide an optical laminate including a polarizer and a retarder that suppresses changes in in-plane retardation characteristics over time and suppresses corrosion of the metal components of the attached image display panel. Another object of the present invention is to provide an image display device that includes this optical laminate.

The inventors' investigations have suggested that the cause of changes in the retardation characteristics of conventional circular polarizing plates is the migration of iodine contained in the polarizer or the antistatic agent contained in the adhesive layer to the retarder. Furthermore, the inventors' investigations have suggested that the cause of corrosion of metal components of image display panels when conventional circular polarizing plates are attached to the image display panel is the corrosion of the metal components caused by iodine contained in the polarizer or the antistatic agent contained in the adhesive layer. Based on these ideas, the inventors' investigations have led to the completion of the invention described below.

The present invention provides an optical laminate comprising, in this order, a first protective film, a polarizer, a second protective film, a retarder, and a pressure-sensitive adhesive layer, wherein the second protective film has a moisture permeability of 1200 g/( ^m2 ·day) or less, and the pressure-sensitive adhesive layer contains an antistatic agent, and the antistatic agent contains an ionic compound composed of an organic cation and an anion represented by the following formula (1):
(C _n F _2n+1 SO ₂ ) ₂ N ^- (1)
(In the formula, n is an integer from 0 to 5.)

This optical laminate can adequately prevent the iodine contained in the polarizer and the antistatic agent contained in the adhesive layer from migrating across layers within the optical laminate.

The optical stack may have one or more of the following characteristics:
The water vapor permeability coefficient of the retarder is 100 or less.
The retarder includes a first retardation layer, a pressure-sensitive adhesive layer, and a second retardation layer, and has a function as a λ/4 plate over the entire visible light range.
The adhesive layer is made of an active energy ray curable adhesive.
The second protective film is made of a cyclic polyolefin resin.
The thickness of the second protective film is 1 to 10 μm.
The first protective film has a moisture permeability of 100 g/(m ² ·day) or more.
- Ionic compounds include organic cations that contain nitrogen atoms.

The present invention also provides an image display device comprising the above-mentioned optical laminate and an image display panel to which the optical laminate is attached.

The present invention provides an optical laminate including a polarizer and a retarder, which can suppress changes in in-plane retardation characteristics over time and can suppress corrosion of metal members included in the image display panel to which it is attached. The present invention also provides an image display device including this optical laminate.

1 is a cross-sectional view of an optical laminate according to one embodiment of the present invention.

A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

<Optical laminate>
(1) Overview As shown in FIG. 1 , the optical laminate 1 of this embodiment is a circular polarizer including a linear polarizer 2, a phase shifter 4, and a pressure-sensitive adhesive layer 5 in this order. The term "circular polarizer" includes an elliptically polarizing plate. The optical laminate 1 can be used as an anti-reflection film in an image display device such as an organic electroluminescence (organic EL) display device. The linear polarizer 2 and the phase shifter 4 are laminated together via a pressure-sensitive adhesive layer 3 between the linear polarizer and the phase shifter.

The linear polarizer 2 comprises a first protective film 21, a polarizer 22, and a second protective film 23, in this order. An internal adhesive layer (not shown) is laminated between the first protective film 21 and the polarizer 22, and between the polarizer 22 and the second protective film 23. The internal adhesive layer is optional, and the first protective film 21 and the polarizer 22, and the polarizer 22 and the second protective film 23 may be in direct contact.

Each component is explained in detail below.

(2) Polarizer The polarizer 22 is an optical film (linear polarizer) that transmits linearly polarized light having a vibration plane perpendicular to the absorption axis when unpolarized light is incident on the polarizer 22. Specifically, the polarizer 22 is a polyvinyl alcohol-based resin film (hereinafter also referred to as a "PVA-based film") on which a dichroic dye is adsorbed and oriented.

The polyvinyl alcohol resin (hereinafter also referred to as "PVA resin") that constitutes the PVA film can be produced by saponifying a polyvinyl acetate resin. Polyvinyl acetate resins can be polyvinyl acetate, a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides containing an ammonium group. In this specification, "(meth)acrylic" refers to either acrylic or methacrylic. The "(meth)" in (meth)acrylate has the same meaning.

The degree of saponification of PVA-based resins is typically around 85 to 100 mol%, and preferably 98 mol% or higher. PVA-based resins may be modified; for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of PVA-based resins is typically around 1,000 to 10,000, and preferably around 1,500 to 5,000. The average degree of polymerization of PVA-based resins can be determined in accordance with JIS K 6726 (1994). If the average degree of polymerization is less than 1,000, it is difficult to achieve favorable polarizing performance, and if it exceeds 10,000, film processability may be poor.

Polarizers are typically manufactured through the following steps: uniaxially stretching a PVA-based film; dyeing the PVA-based film with a dichroic dye to allow the dichroic dye to adsorb; treating the dichroic dye-adsorbed PVA-based film with a boric acid aqueous solution to crosslink it; and washing the film with water after the crosslinking treatment with the boric acid aqueous solution (hereinafter referred to as boric acid treatment).

Uniaxial stretching of PVA-based films can be performed before, simultaneously with, or after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing, it can be performed before or during the boric acid treatment. Of course, uniaxial stretching can also be performed in multiple stages, as shown here. Uniaxial stretching can be performed by uniaxially stretching in the film transport direction between rolls with different peripheral speeds, uniaxially stretching in the film transport direction using heated rolls, or stretching in the width direction using a tenter. Uniaxial stretching can be performed by dry stretching in air, or by wet stretching in which the PVA-based film is swollen using a solvent such as water. The stretching ratio is typically around 3 to 8 times.

Dyeing a PVA-based film with a dichroic dye can be carried out, for example, by immersing the PVA-based film in an aqueous solution containing the dichroic dye. Specific examples of dichroic dyes that can be used include iodine and dichroic organic dyes. It is preferable to immerse the PVA-based film in water to swell it before dyeing.

When iodine is used as the dichroic dye, a dyeing method is typically used in which the PVA-based film is immersed in an aqueous solution containing iodine and potassium iodide. The iodine content in this aqueous solution is typically about 0.01 to 1 part by mass per 100 parts by mass of water, and the potassium iodide content is typically about 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is typically about 20 to 40°C. The immersion time in this aqueous solution (dyeing time) is typically about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic pigment, a dyeing method is typically used in which the PVA-based film is immersed in an aqueous solution containing a water-soluble dichroic organic dye. The content of the dichroic organic dye in this aqueous solution is typically about 0.0001 to 10 parts by mass, and preferably 0.001 to 1 part by mass, per 100 parts by mass of water. This aqueous dye solution may also contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dichroic organic dye aqueous solution used for dyeing is typically about 20 to 80°C. The immersion time in this aqueous solution (dyeing time) is typically about 10 to 1,800 seconds.

Boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed PVA film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is typically about 2 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The potassium iodide content in the boric acid-containing aqueous solution is typically about 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the boric acid-containing aqueous solution is typically about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is typically 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

After the boric acid treatment, the PVA-based film is typically washed with water. This can be done, for example, by immersing the boric acid-treated PVA-based film in water. The water temperature during the washing process is typically around 5 to 40°C. The immersion time is typically around 1 to 120 seconds.

After washing with water, the polarizer is dried to obtain it. The drying process can be carried out using a hot air dryer or far-infrared heater. The drying temperature is usually about 30 to 100°C, preferably 50 to 80°C. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. The drying process reduces the moisture content in the polarizer to a practical level. The moisture content is usually about 5 to 20% by mass, preferably 8 to 15% by mass, relative to the total mass of the polarizer. If the moisture content is 5% by mass or more, the polarizer has sufficient flexibility, making it less likely to be damaged or broken after drying. Furthermore, if the moisture content is 20% by mass or less, the polarizer has sufficient thermal stability.

In this way, a polarizer can be produced in which a dichroic dye is adsorbed and oriented in a PVA-based film.

The luminosity-corrected polarization degree Py of the polarizer is typically 95% or more, preferably 97% or more, more preferably 98% or more, even more preferably 98.7% or more, even more preferably 99.0% or more, and particularly preferably 99.4% or more, and may be 99.9% or more. The luminosity-corrected polarization degree Py of the polarizer may be 99.99% or less. The luminosity-corrected polarization degree Py can be calculated by using an integrating sphere spectrophotometer (JASCO Corporation's "V7100") to perform luminosity correction on the obtained polarization degree using a 2-degree visual field (illuminant C) according to "JIS Z 8701."

Increasing the luminosity-corrected polarization degree Py of the polarizer is advantageous in terms of improving the function of the optical laminate as an anti-reflection film and the durability of the optical laminate. If the luminosity-corrected polarization degree Py of the polarizer is less than 95%, it may not function as an anti-reflection film.

The thickness of the polarizer is 15 μm or less, preferably 13 μm or less, and more preferably 10 μm or less. A polarizer thickness within this range is advantageous for reducing the thickness of the optical laminate and can more effectively suppress the amount of change in retardation. The thickness of the polarizer is usually 2 μm or more, preferably 3 μm or more, and may be, for example, 5 μm or more.

(3) First Protective Film The first protective film 21 has a function of protecting the surface of the polarizer 22. The first protective film 21 may be laminated in direct contact with the surface of the polarizer 22, or may be laminated via a pressure-sensitive adhesive layer in the linear polarizer. The first protective film 21 may be subjected to a surface treatment (e.g., corona treatment) to improve adhesion to the polarizer 22, or may have a thin layer such as a primer layer (also referred to as an easy-adhesion layer) formed thereon.

The thickness T1 of the first protective film is usually 60 μm or less, but from the viewpoint of suppressing curling of the entire polarizing plate under a durable environment, it is preferably 50 μm or less, more preferably 40 μm or less, and preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more.

The first protective film may be, for example, a resin film having excellent transparency, mechanical strength, thermal stability, moisture blocking properties, isotropy, stretchability, etc. The resin film may be a thermoplastic resin film. Specific examples of such thermoplastic resins include:
cellulose ester resins such as triacetyl cellulose;
Polyester resins such as polyethylene terephthalate and polyethylene naphthalate;
Polyethersulfone resin;
Polysulfone-based resin;
Polycarbonate resin;
Polyamide resins such as nylon and aromatic polyamides;
Polyimide resin;
linear polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers;
Cyclic polyolefin resins having cyclo and norbornene structures (also called norbornene resins);
(Meth)acrylic resins such as polymethyl methacrylate;
Polyarylate resin;
Polystyrene-based resin;
Polyvinyl alcohol resin,
and mixtures thereof.
The protective film made of the above thermoplastic resin may be commercially available.

Examples of linear polyolefin resins include linear olefin homopolymers such as polyethylene resin (polyethylene resin, a homopolymer of ethylene, and copolymers primarily composed of ethylene) and polypropylene resin (polypropylene resin, a homopolymer of propylene, and copolymers primarily composed of propylene), as well as copolymers made of two or more linear olefins.

Cyclic polyolefin resin is a general term for resins polymerized using cyclic olefins as polymerization units. Examples include the resins described in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically random copolymers) of cyclic olefins with linear olefins such as ethylene and propylene, graft polymers modified with unsaturated carboxylic acids or their derivatives, and hydrogenated versions of these. Among these, norbornene resins using norbornene monomers such as norbornene or polycyclic norbornene monomers as the cyclic olefin are preferred.

Polyester-based resins are resins with ester bonds in the main chain, and are generally polycondensates of polycarboxylic acids or their derivatives with polyhydric alcohols. Examples of polycarboxylic acids or their derivatives include dicarboxylic acids or their derivatives, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. Examples of polyhydric alcohols include dihydric diols, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of a polyester-based resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Other examples include copolymers containing multiple types of polymerization units constituting these cellulose ester resins, and resins in which some of the hydroxyl groups have been modified with other substituents. Of these, cellulose triacetate (triacetyl cellulose) is particularly preferred.

(Meth)acrylic resins are resins whose main constituent monomer is a compound having a (meth)acryloyl group. Specific examples of (meth)acrylic resins include poly(meth)acrylic esters such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymers; methyl methacrylate-(meth)acrylic ester copolymers; methyl methacrylate-acrylic ester-(meth)acrylic acid copolymers; methyl (meth)acrylate-styrene copolymers (such as MS resins); and copolymers of methyl methacrylate and compounds having alicyclic hydrocarbon groups (such as methyl methacrylate-cyclohexyl methacrylate copolymers and methyl methacrylate-norbornyl (meth)acrylate copolymers). Preferably, polymers whose main component is a poly(meth)acrylic acid C1-C6 alkyl ester, such as polymethyl (meth)acrylate, are used. More preferably, methyl methacrylate resins whose main component is methyl methacrylate (50 to 100% by mass, preferably 70 to 100% by mass) are used.

Polycarbonate-based resins consist of polymers in which monomer units are bonded via carbonate groups. Polycarbonate-based resins may be modified polycarbonates, which are resins in which the polymer backbone has been modified, or copolymer polycarbonates.

The first protective film may be a stretched film containing the thermoplastic resin. Examples of stretching methods include uniaxial stretching and biaxial stretching. Stretching directions include the machine direction (MD) of the unstretched film, a direction perpendicular to the MD (TD), and a direction oblique to the MD. Biaxial stretching may be simultaneous biaxial stretching, in which the film is stretched in two directions simultaneously, or sequential biaxial stretching, in which the film is stretched in a predetermined direction and then stretched in the other direction. Stretching can be performed, for example, by stretching the film in the longitudinal direction (MD) using two or more pairs of nip rolls with a high peripheral speed on the outlet side, or by gripping both side edges of the unstretched film with chucks and spreading it in the direction perpendicular to the MD (TD). Adjusting the film thickness or the stretch ratio can control the retardation and wavelength dispersion. Wavelength dispersion can also be controlled by adding a wavelength dispersion adjuster to the resin.

The first protective film may contain any appropriate additives depending on the purpose. Examples of additives include hindered phenol-based, phosphorus-based, and sulfur-based antioxidants; stabilizers such as light stabilizers, UV absorbers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fiber and carbon fiber; near-infrared absorbers; flame retardants such as tris(dibromopropyl)phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic and inorganic fillers; resin modifiers; plasticizers; lubricants; and retardation reducers. The type, combination, and content of the additives contained may be appropriately determined depending on the purpose and desired properties.

In addition, a coating layer (surface treatment layer) can be provided on the outer surface of the first protective film to impart desired surface optical properties or other characteristics. Specific examples of surface treatment layers include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. The method for forming the surface treatment layer is not particularly limited, and known methods can be used. The surface treatment layer may be formed on one or both surfaces of the first protective film.

The hard coat layer has the function of increasing the surface hardness of the first protective film and is provided for purposes such as preventing surface scratches. The hard coat layer preferably has a pencil hardness of H or harder, as measured by the pencil hardness test specified in JIS K 5600-5-4:1999 "General Test Methods for Paints - Part 5: Mechanical Properties of Coatings - Section 4: Scratch Hardness (Pencil Method)" (measured by placing a protective film with a hard coat layer on a glass plate).

The material that forms the hard coat layer is generally cured by heat or light. Examples include organic hard coat materials such as organosilicon, melamine, epoxy, (meth)acrylic, and urethane (meth)acrylate, as well as inorganic hard coat materials such as silicon dioxide. Among these, urethane (meth)acrylate or polyfunctional (meth)acrylate hard coat materials are preferred due to their excellent adhesion to the protective film and superior productivity.

The hard coat layer can optionally contain various fillers to adjust the refractive index, improve the flexural modulus, stabilize the volume shrinkage rate, and further improve heat resistance, antistatic properties, antiglare properties, etc. The hard coat layer can also contain additives such as antioxidants, UV absorbers, light stabilizers, antistatic agents, leveling agents, and antifoaming agents.

The hard coat layer may contain additives to further improve its strength. There are no limitations on the additives, and examples include inorganic fine particles, organic fine particles, or mixtures of these. The thickness of the hard coat layer is preferably thicker to provide hardness, but if it is too thick, it may be prone to cracking when cut, so it may be 1 μm to 20 μm, or 2 μm to 10 μm. The thickness of the hard coat layer is preferably 3 μm to 7 μm.

The anti-glare layer is a layer with a finely textured surface, and is preferably formed using the hard coat material described above.

An anti-glare layer with a finely textured surface can be formed by, for example, 1) forming a coating film containing fine particles on a protective film and creating texture based on the fine particles, or 2) forming a coating film, which may or may not contain fine particles, on a protective film, and then pressing the film against a mold (such as a roll) with a textured surface to transfer the texture (also known as an embossing method).

Anti-reflection layers are layers that reduce the reflection of external light from the surface of a protective film for those viewing the film, and typically have a reflectance of 1.5% or less for visible light. Anti-reflection layers with such reflectance are typically made by laminating a high-refractive index layer with a high refractive index and a low-refractive index layer with a low refractive index, or by using the methods and materials described in JP 2021-6929 A. By adjusting the refractive index and thickness of each layer, the reflected light from each layer can be made to weaken each other, providing excellent anti-reflection functionality.

As will be described in detail later, an anti-reflection layer consisting of a high refractive index layer and a low refractive index layer is preferably produced using a coating composition capable of forming each of the high refractive index layer and the low refractive index layer, as this simplifies the process. Here, we will provide an example of a coating composition capable of forming each of the high refractive index layer and the low refractive index layer. Such a coating composition is liquid and contains an appropriate curable resin and, if necessary, additives. A coating composition capable of forming a high refractive index layer (a composition for forming a high refractive index layer) is prepared by dissolving, for example, a curable resin such as urethane acrylate and a photopolymerization initiator (photopolymerization initiator) such as an acetophenone-based, benzophenone-based, benzyl dimethyl ketal-based, α-hydroxyalkylphenone-based, α-aminoalkylphenone-based, or thioxanthone-based compound in a solvent such as methyl ethyl ketone or methyl isobutyl ketone. To improve coatability, a leveling agent, preferably a fluorine-based leveling agent, may also be added. Furthermore, coating compositions capable of forming low refractive index layers (compositions for forming low refractive index layers) include curable resins such as polyethylene glycol diacrylate and pentaerythritol (tri/tetra)acrylate, binder resins, and photopolymerization initiators (photopolymerization initiators) such as acetophenone, benzophenone, benzyl dimethyl ketal, α-hydroxyalkylphenone, α-aminoalkylphenone, and thioxanthone, dissolved in a solvent such as 1-methoxy-2-propyl acetate or methyl isobutyl ether, in which silica particles are dispersed. To improve coatability, a fluorine-based leveling agent may also be added. The coating compositions capable of forming the high refractive index layer and the low refractive index layer listed here are merely examples, and it is preferable to optimize the high refractive index layer-forming composition and the low refractive index layer-forming composition, respectively, depending on the properties of the antireflection layer to be formed.

The anti-reflection layer may, for example, include a low refractive index layer. It may also have a multi-layer structure that further includes a high refractive index layer and/or a medium refractive index layer between the protective film and the low refractive index layer.

The low refractive index layer can be formed by applying a coating liquid containing a cured product of the above-mentioned curable resin or a light-transmitting resin such as a metal alkoxide polymer, and inorganic particles, and then curing the coating layer as needed. Examples of inorganic particles include low refractive index particles such as LiF (refractive index 1.4), MgF (refractive index 1.4), 3NaF·AlF (refractive index 1.4), AlF (refractive index 1.4), and Na3AlF6 (refractive index 1.33), as well as hollow silica particles.

The antistatic layer is provided to impart conductivity to the surface of the first protective film and to suppress the effects of static electricity. To form the antistatic layer, for example, a method can be used in which a resin composition containing a conductive substance (antistatic agent) is applied to the first protective film. For example, an antistatic hard coat layer can be formed by adding an antistatic agent to the hard coat material used to form the hard coat layer described above.

Anti-fouling layers are provided to impart water repellency, oil repellency, sweat resistance, anti-fouling properties, etc. Suitable materials for forming anti-fouling layers are fluorine-containing organic compounds. Examples of fluorine-containing organic compounds include fluorocarbons, perfluorosilanes, and polymeric compounds thereof. Methods for forming anti-fouling layers include physical vapor deposition (typically vapor deposition or sputtering), chemical vapor deposition, and wet coating, depending on the material used. The average thickness of the anti-fouling layer is typically around 1 to 50 nm, and preferably 3 to 35 nm.

When the optical laminate is applied to an image display device, diffusion of dichroic dyes such as iodine in the polarizer 22 can lead to corrosion of metal components (electrodes, etc.) present near the optical laminate in the image display device. This is because the dichroic dyes such as iodine migrate to the metal components due to the diffusion. In order to prevent corrosion of the metal components, it is preferable to limit the amount of dichroic dye that migrates to the metal components.

The moisture permeability of the first protective film is preferably 100 g/(m ² ·day) or more. This moisture permeability is preferably 100 g/(m ² ·day) or more and 2000 g/(m ² ·day) or less, more preferably 200 g/(m ² ·day) or more and 1000 g/(m ² ·day) or less, and even more preferably 300 g/(m ² ·day) or more and 500 g/(m ² ·day) or less. When iodine contained in the polarizer moves between layers of the optical laminate 1, if the moisture permeability of the first protective film 21 is too low, the movement of iodine is too suppressed and tends to be biased toward the opposite direction (toward the retarder). Furthermore, if the moisture permeability of the first protective film 21 is too high, the polarizer tends to be more susceptible to moist heat degradation. Therefore, it is preferable that the moisture permeability of the first protective film is moderately high so that when iodine migrates toward the first protective film 21, the iodine passes through the first protective film 21 and diffuses out of the optical laminate 1.

(4) Second Protective Film The second protective film 23 has a function of protecting the surface of the polarizer 22. The second protective film 23 may be laminated in direct contact with the surface of the polarizer 22, or may be laminated via a pressure-sensitive adhesive layer in the linear polarizer. The second protective film 23 may be subjected to a surface treatment (e.g., corona treatment) to improve adhesion to the polarizer 22, or may have a thin layer such as a primer layer (also referred to as an easy-adhesion layer) formed thereon.

The moisture permeability of the second protective film 23 is 1200 g/(m ² ·day) or less. This moisture permeability is preferably 0.1 g/(m ² ·day) or more and 800 g/(m ² ·day) or less, more preferably 0.5 g/(m ² ·day) or more and 500 g/(m ² ·day) or less, even more preferably 1 g/(m ² ·day) or more and 100 g/(m ² ·day) or less, and particularly preferably 10 g/(m ² ·day) or more and 50 g/(m ² ·day) or less. When the moisture permeability of the second protective film 23 is within this range, iodine can be sufficiently prevented from migrating to the phase shifter side. Furthermore, a moisture permeability of the second protective film 23 of 10 g/(m ² ·day) or more is also preferable from the viewpoint of Δα, which will be described later. The moisture permeability of the second protective film 23 can be measured according to the description in the section [Examples].

The thickness T2 of the second protective film is, for example, 0.1 to 60 μm, preferably 0.2 to 30 μm. It is advantageous for this embodiment that the thickness T2 of the second protective film is appropriately thin. In other words, when the antistatic agent contained in the pressure-sensitive adhesive layer described below migrates between layers of the optical laminate 1, if the thickness of the second protective film 23 is too large, the migration of the antistatic agent is too suppressed, and migration tends to be biased toward the opposite direction (toward the image display panel). Therefore, from the perspective of suppressing corrosion of metal components, the thickness T2 of the second protective film is preferably 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 3 to 5 μm.

The second protective film may be, for example, a resin film that has excellent transparency, mechanical strength, thermal stability, moisture blocking properties, isotropy, stretchability, etc. The resin film may be a thermoplastic resin film. Specific examples of such thermoplastic resins are the same as those described for the first protective film. Protective films made of thermoplastic resins may be commercially available.

The thermoplastic resins constituting the thermoplastic resin film used as the second protective film and the thermoplastic resin layer described below are preferably cyclic polyolefin resins, polyester resins, polycarbonate resins, (meth)acrylic resins, and polystyrene resins, more preferably cyclic polyolefin resins, (meth)acrylic resins, and polystyrene resins, even more preferably cyclic polyolefin resins and (meth)acrylic resins, and even more preferably cyclic polyolefin resins.

The thermoplastic resin film used as the second protective film may be a film existing alone. In this case, the thermoplastic resin film is laminated on the polarizer 22, if necessary, via a pressure-sensitive adhesive layer within the linear polarizer. Alternatively, the second protective film may be a thermoplastic resin layer. For example, a composition containing a thermoplastic resin is applied to a support substrate, and if necessary, dried to obtain a thermoplastic resin layer with a support substrate. This is then attached to the polarizer 22, if necessary, via a pressure-sensitive adhesive layer within the linear polarizer. The support substrate is then peeled off and removed, thereby laminating a thermoplastic resin layer as the second protective film on the polarizer 22 (first method).

When the second protective film is a thermoplastic resin layer, it is also possible to form a thermoplastic resin layer by applying the above composition directly to the surface of the polarizer 22 and drying it as necessary (second method). However, when the composition contains a solvent, the first method is preferred because it is easier to stably form a thermoplastic resin layer with a sufficiently reduced solvent content.

The second protective film may be a cured resin layer containing a cured product of a curable resin. Examples of curable resins include thermosetting resins and active energy curable resins, such as (meth)acrylic resins, epoxy resins, oxetane resins, urethane resins, (meth)acrylic urethane resins, and melamine resins. A cured resin layer containing a cured product of a curable resin can be formed by applying a composition containing the curable resin to a support substrate, drying it as needed, and then applying heat or irradiating it with active energy rays such as visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, gamma rays, or electron beams. The resulting cured resin layer with support substrate is attached to the polarizer 22, if necessary, via an internal adhesive layer in the linear polarizing plate. The support substrate is then peeled off and removed, thereby laminating a cured resin layer as the second protective film on the polarizer 22.

From the viewpoint of moisture permeability or suppressing changes in retardation characteristics, the second protective film is preferably a thermoplastic resin film or thermoplastic resin layer made of a cyclic polyolefin resin, a thermoplastic resin film or thermoplastic resin layer made of a (meth)acrylic resin, a cured resin layer containing a cured product of a (meth)acrylic resin, or a thermoplastic resin film or thermoplastic resin layer made of a polystyrene resin. Taking into consideration the need to further suppress migration of the dichroic dye in the polarizer 22 to the metal member, the second protective film is more preferably a thermoplastic resin film or thermoplastic resin layer made of a cyclic polyolefin resin, or a thermoplastic resin film or thermoplastic resin layer made of a polystyrene resin.

The second protective film may contain any appropriate additive depending on the purpose. Specific examples of additives are the same as those described for the first protective film.

The second protective film preferably has no retardation properties or a small retardation value. Specifically, the in-plane retardation value of the second protective film at a wavelength of 550 nm is preferably 10 nm or less. The in-plane retardation value is 0 nm or more. Furthermore, the retardation value in the thickness direction of the second protective film at a wavelength of 550 nm is preferably -10 nm to +10 nm.

(5) Retarder The retarder 4 is an optical element exhibiting retardation in the in-plane or thickness direction, and preferably includes a retardation film. The retardation film is a film exhibiting retardation in the in-plane or thickness direction, and is a layer (cured layer) made of a polymer of a polymerizable liquid crystal compound, or a combination of such a layer and an alignment film. The retardation film includes, for example, a cured layer of a retardation film-forming composition containing a polymerizable liquid crystal compound.

When the retarder 4 includes a retardation film, the dichroic dye migrates to the metal member, making the metal member more susceptible to corrosion. However, according to the present invention, this corrosion can be effectively suppressed even when the retarder 4 includes a retardation film. Furthermore, including a retardation film in the retarder 4 is advantageous for reducing the thickness of the optical laminate, and including a retardation film in the retarder 4 is preferable in that the wavelength dispersion characteristics can be designed as desired.

The retarder 4 in the optical laminate 1 of this embodiment has two types of retardation films (hereinafter also referred to as "retardation layers"). That is, a first retardation layer 41 and a second retardation layer 43 are laminated with an internal retarder adhesive layer 42. Note that, in this specification, the retardation films included in the retarder 4 may be referred to as the "first retardation layer" and the "second retardation layer" in order of proximity to the linear polarizer 2. Possible configurations of the retarder 4 are described below.

(5-1) Retardation Film A retardation film is usually formed by applying a retardation film-forming composition onto an alignment film formed on a substrate, and polymerizing the polymerizable liquid crystal compound contained in the retardation film-forming composition. A retardation film is usually a film in which the polymerizable liquid crystal compound is cured in an aligned state. In order to generate a retardation in the viewing plane, the retardation film needs to be a cured film in which the polymerizable group is polymerized in a state in which the polymerizable liquid crystal compound is aligned horizontally relative to the substrate surface. In this case, if the polymerizable liquid crystal compound is a rod-shaped liquid crystal, a positive A plate may be used, and if the polymerizable liquid crystal compound is a discotic liquid crystal, a negative A plate may be used.

The retarder may include two or more retardation films with different optical anisotropy. To achieve high anti-reflection performance, it is sufficient to have λ/4 plate functionality (i.e., π/2 retardation functionality) across the entire visible light range. Specifically, a reverse wavelength dispersion λ/4 retardation layer is preferred, or a combination of two or more retardation films with different orientations is preferable. For example, a combination of a retardation film with λ/2 plate functionality (i.e., π retardation functionality) and a retardation film with λ/4 plate functionality (i.e., π/2 retardation functionality) may be used. Furthermore, from the perspective of compensating for anti-reflection functionality in oblique directions, it is preferable to further include a layer with anisotropy in the thickness direction (positive C plate). In particular, the effects of the present invention can be more pronounced when the retarder includes a reverse wavelength dispersion λ/4 retardation layer and a positive C plate. Furthermore, each retardation film may have a tilt orientation or may form a cholesteric orientation.

When combining two or more types of retardation films with different retarder orientations, they can be bonded via the retarder internal adhesive layer 42. From the viewpoint of suppressing corrosion of the metal members included in the image display panel to which the optical laminate is bonded, the retarder internal adhesive layer 42 is preferably an adhesive layer with low moisture permeability.

In the optical laminate 1, iodine contained in the polarizer 22 and an antistatic agent contained in the pressure-sensitive adhesive layer 5 described below can migrate between layers and transfer to the retarder. In this case, if the retardation film is made of a polymerizable liquid crystal compound, the retardation characteristics change (for example, increase) due to the influence of iodine and the antistatic agent. From this perspective, the water vapor permeability coefficient of the retarder is preferably 100 or less. This water vapor permeability coefficient is preferably 1 or more and 75 or less, more preferably 5 or more and 50 or less, and even more preferably 10 or more and 35 or less. Here, the "water vapor permeability coefficient" means a value expressed by the product of the moisture permeability (unit: g/( ^m2 ·day)) of the retarder at 65°C and the thickness (unit: mm). When iodine and the antistatic agent move between the layers of the optical laminate 1, if the water vapor permeability coefficient of the retarder 4 is too high, the movement of the iodine and the antistatic agent increases, and the degree of suppression of the change in retardation of the first retardation layer or the second retardation layer, which should suppress the change in retardation, and the effect of suppressing corrosion of the metal member tend to be reduced compared to the original suppression effect. Also, if the water vapor permeability coefficient is too low, the antistatic agent becomes excessively difficult to permeate, and the antistatic agent tends to move toward the metal member. Therefore, it is preferable that the water vapor permeability coefficient of the retarder is appropriately low.

The λ/4 function of the retarder over the entire visible light range preferably satisfies the optical characteristics shown in the following formula (1), where Re(λ) is the in-plane retardation value for light with a wavelength of λ nm, and preferably satisfies the optical characteristics shown in the following formulas (1), (2), and (3): The in-plane retardation value Re(λ) of the retarder is a value measured by laminating a linear polarizer and a retarder in this order using a retardation measuring device (KOBRA-WPR, manufactured by Oji Scientific Instruments Co., Ltd.).
100nm<Re(550)<160nm (1)
(In the formula, Re(550) represents the in-plane phase difference value (in-plane retardation) for light with a wavelength of 550 nm.)
Re(450)/Re(550)≦1.0 (2)
1.00≦Re(650)/Re(550) (3)
(In the formula, Re(450) represents the in-plane retardation value for light with a wavelength of 450 nm, Re(550) represents the in-plane retardation value for light with a wavelength of 550 nm, and Re(650) represents the in-plane retardation value for light with a wavelength of 650 nm.)

The wavelength dispersion α of the retarder is preferably within a predetermined range. Here, "wavelength dispersion α" refers to the ratio (Re(450)/Re(550)) of the in-plane retardation value Re(450) at a wavelength of 450 nm to the in-plane retardation value Re(550) at a wavelength of 550 nm. Because this improves the reverse wavelength dispersion and the optical properties of the optical laminate, the wavelength dispersion α is preferably 0.70 or greater, more preferably 0.78 or greater. For similar reasons, the wavelength dispersion α is preferably 0.92 or less, more preferably 0.90 or less, even more preferably 0.88 or less, and particularly preferably 0.87 or less. The "Re(450)/Re(550)" value can be adjusted as desired by adjusting the mixing ratio of the polymerizable liquid crystal compound, the stacking angle of the multiple retardation films, and the retardation values.

The in-plane retardation value of the retardation film can be adjusted by the thickness of the retardation film. Since the in-plane retardation value is determined by the following formula (4), a desired in-plane retardation value (Re(λ)) can be obtained by adjusting Δn(λ) and the thickness d. The thickness of the retardation film is preferably 0.5 μm to 5 μm, more preferably 1 μm to 3 μm. The thickness of the retardation film can be measured using an interference film thickness meter, a laser microscope, or a stylus film thickness meter. Note that Δn(λ) depends on the molecular structure of the polymerizable liquid crystal compound described below.
Re(λ)=d×Δn(λ) (4)
(In the formula, Re(λ) represents an in-plane retardation value at a wavelength of λ nm, d represents a thickness, and Δn(λ) represents a birefringence at a wavelength of λ nm.)

The positive C plate is not particularly limited as long as it has anisotropy in the thickness direction, but if it does not have tilt alignment or cholesteric alignment, it has the optical characteristics expressed by formula (5).
nx≒ny<nz (5)

The in-plane retardation value Re(550) of a positive C plate at a wavelength of 550 nm is typically in the range of 0 to 10 nm, and preferably in the range of 0 to 5 nm. Furthermore, the retardation value Rth(550) in the thickness direction at a wavelength of 550 nm is typically in the range of -170 nm to -10 nm, preferably -150 nm to -20 nm, and more preferably -100 nm to -40 nm. A thickness direction retardation value within this range can significantly improve anti-reflection properties from oblique directions.

The polymerizable liquid crystal compound contained in the retardation film-forming composition refers to a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group. Conventional polymerizable liquid crystal compounds can be used as the polymerizable liquid crystal compound. A photopolymerizable group refers to a group that can participate in a polymerization reaction in the presence of reactive species generated from a photopolymerization initiator, such as active radicals or acids. Examples of photopolymerizable groups include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, acryloyloxy groups, methacryloyloxy groups, oxiranyl groups, and oxetanyl groups. Among these, acryloyloxy groups, methacryloyloxy groups, vinyloxy groups, oxiranyl groups, and oxetanyl groups are preferred, with acryloyloxy groups being more preferred. The liquid crystal property may be either thermotropic or lyotropic, but thermotropic liquid crystals are preferred due to their ability to precisely control the film thickness. Furthermore, the phase order structure of the thermotropic liquid crystal may be either nematic or smectic. The polymerizable liquid crystal compounds may be rod-shaped or discotic. They may be used alone or in combination of two or more.

As the polymerizable liquid crystal compound, from the viewpoint of exhibiting reverse wavelength dispersion, a liquid crystal having a T-shaped or H-shaped mesogen structure which further has birefringence in a direction perpendicular to the molecular long axis direction is preferred, and from the viewpoint of obtaining stronger dispersion, a T-shaped liquid crystal is more preferred. Specific examples of the structure of the T-shaped liquid crystal include those represented by the following formula (I):

Examples of the compound include compounds represented by the following formula:

In formula (I), Ar represents a divalent aromatic group which may have a substituent. The divalent aromatic group preferably contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When the divalent group Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other via a divalent bonding group such as a single bond, -CO-O-, or -O-.
^G1 and ^G2 each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.
L ¹ , L ² , B ¹ and B ² each independently represent a single bond or a divalent linking group.
k and l each independently represent an integer of 0 to 3, and satisfy the relationship 1≦k+l, where, when 2≦k+l, B ¹ and B ² , and G ¹ and G ² may be the same or different from each other.
^E1 and ^E2 each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and _{a -CH2-} contained in the alkanediyl group may be substituted with -O-, -S- or -COO-, and when there are multiple -O-, -S- or -COO-, they are not adjacent to each other. ^P1 and ^P2 each independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

^G1 and ^G2 are each independently preferably a 1,4-phenylenediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group. Preferably, at least one of the multiple ^G1s and ^G2s is a divalent alicyclic hydrocarbon group, and more preferably, at least one of ^G1s and ^G2s bonded to ^L1 or ^L2 is a divalent alicyclic hydrocarbon group.

^L1 and ^L2 each independently represent preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC═OOR ^a8 -, -N═N-, -CR ^c ═CR ^d -, or -C≡C-, where R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. ^L1 and ^L2 are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or OCOR ^a6-1 -. Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. ^L1 and ^L2 are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, or OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 -, or R ^a15 OC═OOR ^a16 -. Here, R ^a9 to R ^a16 are each independently a single bond or an alkylene group having 1 to 4 carbon atoms. ^{B 1} and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or OCOR ^a14-1 -. Here, R ^a10-1 , R ^a12-1 and R ^a14-1 each independently represent a single bond, —CH ₂ — or —CH ₂ CH ₂ —. ^{B 1} and B ² each independently represent more preferably a single bond, —O—, —CH ₂ CH ₂ —, —COO—, —COOCH ₂ CH ₂ —, —OCO— or OCOCH ₂ CH ₂ —.

From the perspective of achieving reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and l=2. When k=2 and l=2, a symmetrical structure is obtained, which is preferable.

E ¹ and E ² each independently represent preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by ^P1 or ^P2 include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, with a benzene ring and a naphthalene ring being preferred. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferred, and a benzothiazole group is even more preferred. Furthermore, when Ar contains a nitrogen atom, it is preferred that the nitrogen atom have π electrons.

In formula (I), the total number Nπ of π electrons contained in the divalent aromatic group represented by _Ar is preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. Also, it is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

Suitable examples of the aromatic group represented by Ar include the following groups:

In formulae (Ar-1) to (Ar-23), * represents a linking moiety, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q ¹ , Q ² and Q ³ each independently represent -CR ^2' R ^3' -, -S-, -NH-, -NR ^2' -, -CO- or O-, and R ^2' and R ^3' each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group, or a halogen atom; m represents an integer of 0 to 6;

Examples of the aromatic hydrocarbon group for ^Y1 , ^Y2 , and ^Y3 include aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, with a phenyl group and a naphthyl group being preferred, and a phenyl group being more preferred. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms and containing at least one heteroatom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group, with a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group being preferred.

^Y1 , ^Y2 , and ^Y3 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z ⁰ , Z ¹ and Z ² are each preferably independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group or an alkoxy group having 1 to 12 carbon atoms, Z ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a cyano group.

Q ¹ , Q ² and Q ³ are preferably —NH—, —S—, —NR ^2′ — or —O—, and R ^2′ is preferably a hydrogen atom, with —S—, —O— and —NH— being particularly preferred.

Among the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.
In formulae (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ^0. Examples of the aromatic heterocyclic group include those described above as the aromatic heterocycle that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. Furthermore, Y ¹ may, together with the nitrogen atom to which it is bonded and Z ^0, be the aforementioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. Examples include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

Among polymerizable liquid crystal compounds, compounds with a maximum absorption wavelength of 300 to 400 nm are preferred. When a polymerizable liquid crystal composition contains a photopolymerization initiator, there is a risk of polymerization and gelation of the polymerizable liquid crystal compound progressing during long-term storage. However, if the polymerizable liquid crystal compound has a maximum absorption wavelength of 300 to 400 nm, even if it is exposed to UV light during storage, the generation of reactive species from the photopolymerization initiator and the progression of polymerization and gelation of the polymerizable liquid crystal compound due to these reactive species can be effectively suppressed. This is advantageous in terms of long-term stability of the polymerizable liquid crystal composition and can improve the alignment and film thickness uniformity of the resulting retardation film. The maximum absorption wavelength of the polymerizable liquid crystal compound can be measured using a UV-visible spectrophotometer in a solvent that can dissolve the polymerizable liquid crystal compound, such as chloroform.

Examples of the discotic polymerizable liquid crystal compound include a compound containing a group represented by formula (W) (hereinafter, also referred to as "polymerizable liquid crystal compound (W)").

[In formula (W), R ⁴⁰ represents the following formulae (W-1) to (W-5)]

[In formulas (W-1) to (W-5),
X ⁴⁰ and Z ⁴⁰ each independently represent an alkanediyl group having 1 to 12 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. Furthermore, —CH ₂ — constituting the alkanediyl group may be replaced with —O— or —CO—.
m2 represents an integer.

Examples of the rod-shaped polymerizable liquid crystal compound include compounds represented by formula (II), formula (III), formula (IV), formula (V), formula (VI) or formula (VII).
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (II)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (III)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (IV)
P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (V)
P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (VI)
P11-B11-E11-B12-A11-B13-A12-F11 (VII)
[In formulas (II) to (VII),
A11 to A14 each independently represent a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. A hydrogen atom contained in the divalent alicyclic hydrocarbon group and the divalent aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and a hydrogen atom contained in the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms may be substituted with a fluorine atom.
B11 and B17 each independently represent -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR ¹⁶ -, -NR ¹⁶ -CO-, -CO-, -CS-, or a single bond, and R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
B12 to B16 each independently represent -C≡C-, -CH=CH-, -CH ₂ -CH ₂ -, -O-, -S-, -C(=O)-, -C(=O)-O-, -O-C(=O)-, -O-C(=O)-O-, -CH=N-, -N=CH-, -N=N-, -C(=O)-NR ¹⁶ -, -NR ¹⁶ -C(=O)-, -OCH ₂ -, -OCF ₂ -, -CH ₂ O-, -CF ₂ O-, -CH=CH-C(=O)-O-, -O-C(=O)-CH=CH- or a single bond.
E11 and E12 each independently represent an alkanediyl group having 1 to 12 carbon atoms, a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom, and —CH ₂ — constituting the alkanediyl group may be replaced with —O— or —CO—.
F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxy group, a methylol group, a formyl group, a sulfo group (—SO ₃ H), a carboxy group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and —CH ₂ — constituting the alkyl group and alkoxy group may be replaced with —O—.
P11 and P12 each independently represent a polymerizable group.]

The content of the polymerizable liquid crystal compound in the retardation film-forming composition is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and even more preferably 90 to 95 parts by mass, relative to 100 parts by mass of the solid content of the retardation film-forming composition. A content of the polymerizable liquid crystal compound within the above range is advantageous from the perspective of the alignment of the resulting retardation film. In this specification, the solid content of the polymerizable liquid crystal composition refers to all components of the polymerizable liquid crystal composition excluding volatile components such as organic solvents.

(5-2) Composition for Forming Retardation Film As described above, the composition for forming a retardation film contains a polymerizable liquid crystal compound. The composition for forming a retardation film may further contain reactive additives such as a solvent, a leveling agent, a polymerization initiator, a photosensitizer, a polymerization inhibitor, a crosslinking agent, and an adhesive agent, and it is preferable that the composition contains a solvent and a leveling agent from the viewpoint of processability.

The retardation film-forming composition may contain a solvent. Polymerizable liquid crystal compounds generally have high viscosity, so dissolving the retardation film-forming composition in a solvent often makes it easier to apply, and as a result, makes it easier to form a retardation film. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound, and is preferably a solvent that is inactive to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of solvents include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, gamma-butyrolactone or propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination.

The solvent content is preferably 50 to 98% by mass relative to the total amount of the retardation film-forming composition. In other words, the solids content in the retardation film-forming composition is preferably 2 to 50% by mass, and more preferably 5 to 30% by mass. If the solids content is 50% by mass or less, the viscosity of the retardation film-forming composition will be low, which will result in a generally uniform thickness of the retardation film, making unevenness in the retardation film less likely to occur. Furthermore, the solids content can be determined taking into account the thickness of the retardation film to be produced.

The retardation film-forming composition may contain a leveling agent. A leveling agent is an additive that adjusts the fluidity of the composition and makes the film obtained by applying the composition flatter. Examples of leveling agents include organically modified silicone-based, polyacrylate-based, and perfluoroalkyl-based leveling agents. Of these, polyacrylate-based and perfluoroalkyl-based leveling agents are preferred for horizontal alignment, and organically modified silicone-based and perfluoroalkyl-based leveling agents are preferred for vertical alignment.

When the retardation film-forming composition contains a leveling agent, the content thereof is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal compound, and the resulting retardation film tends to be smoother. When the content of the leveling agent relative to the polymerizable liquid crystal compound exceeds the above range, unevenness tends to occur in the resulting retardation film. The retardation film-forming composition may contain two or more types of leveling agents.

The retardation film-forming composition may contain a polymerization initiator. A polymerization initiator is a compound that can initiate a polymerization reaction of a polymerizable liquid crystal compound or the like. As a polymerization initiator, a photopolymerization initiator that generates active radicals under the action of light is preferred, as it is not dependent on the phase state of the thermotropic liquid crystal.

The photopolymerization initiator can be any known photopolymerization initiator that can initiate the polymerization reaction of the polymerizable liquid crystal compound. Specific examples include photopolymerization initiators that can generate active radicals or acids when exposed to light, and among these, photopolymerization initiators that generate radicals when exposed to light are preferred. These photopolymerization initiators can be used alone or in combination of two or more types.

Known photopolymerization initiators can be used as the photopolymerization initiator. For example, photopolymerization initiators that generate active radicals include self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and azo compounds. Hydrogen-abstraction benzophenone compounds, alkylphenone compounds, benzoin ether compounds, benzil ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, and triazine compounds. Acid-generating photopolymerization initiators include iodonium salts and sulfonium salts. Self-cleaving photopolymerization initiators are preferred because they have excellent reaction efficiency at low temperatures, with acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds being particularly preferred.

The content of the polymerization initiator in the retardation film-forming composition can be adjusted appropriately depending on the type and amount of the polymerizable liquid crystal compound, but is typically 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, polymerization can be carried out without disturbing the alignment of the polymerizable liquid crystal compound.

The retardation film-forming composition may contain a sensitizer. The sensitizer is preferably a photosensitizer. Examples of such sensitizers include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy group-containing anthracenes (e.g., dibutoxyanthracene, etc.); phenothiazine, rubrene, etc.

When the retardation film-forming composition contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the retardation film-forming composition can be further accelerated. The amount of such a sensitizer used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound.

To ensure stable progress of the polymerization reaction, the retardation film-forming composition may contain an antioxidant. The antioxidant can control the degree of progress of the polymerization reaction of the polymerizable liquid crystal compound.

The antioxidant may be, for example, a primary antioxidant selected from phenol-based antioxidants, amine-based antioxidants, quinone-based antioxidants, and nitroso-based antioxidants, or a secondary antioxidant selected from phosphorus-based antioxidants and sulfur-based antioxidants.

When the retardation film-forming composition contains an antioxidant, the content of the antioxidant is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. Antioxidants can be used alone or in combination of two or more. When the content of the antioxidant is within the above range, polymerization can be carried out without disturbing the alignment of the polymerizable liquid crystal compound.

The retardation film-forming composition may contain a reactive additive. The reactive additive preferably has a carbon-carbon unsaturated bond, an active hydrogen-reactive group, or a thiol group in its molecule. The term "active hydrogen-reactive group" as used herein refers to a group that is reactive with a group having active hydrogen, such as a carboxyl group (-COOH), a hydroxyl group (-OH), or an amino group (-NH ₂ ), and typical examples of such groups include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, and a maleic anhydride group. The reactive additive typically has 1 to 20 reactive groups, preferably 1 to 10 reactive groups.

(5-3) Substrate Examples of the substrate for forming the retardation film include glass substrates and film substrates, with film substrates being preferred, and long rolled films being more preferred in terms of continuous production. Examples of resins constituting the film substrate include linear polyolefins such as polyethylene and polypropylene; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide and polyphenylene oxide; and the like. Among these, from the viewpoint of transparency when used in optical film applications, a film substrate selected from any of triacetyl cellulose, cyclic olefin resins, polymethacrylic acid esters, and polyethylene terephthalate is more preferred.

Commercially available cellulose ester substrates include "Fujitac Film" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M," "KC8UY," and "KC4UY" (all manufactured by Konica Minolta Opto, Inc.). Commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona, Germany), "Arton" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (all manufactured by Zeon Corporation), and "Apel" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). These cyclic olefin resins can be formed into films using known methods such as solvent casting and melt extrusion to form substrates. Commercially available cyclic olefin resin substrates can also be used. Commercially available cyclic olefin resin substrates include "ESCINA" (registered trademark) and "SCA40" (registered trademark) (both manufactured by Sekisui Chemical Co., Ltd.), "ZEONORFILM" (registered trademark) (manufactured by Optes Co., Ltd.), and "ARTONFILM" (registered trademark) (manufactured by JSR Corporation).

The thickness of the substrate is preferably thin enough to allow practical handling, but if it is too thin, the strength decreases and processability tends to be poor. The thickness of the substrate is usually 5 μm to 300 μm, preferably 10 μm to 200 μm, and more preferably 10 to 50 μm. Furthermore, by peeling off the substrate and transferring the retardation film, an even thinner film can be achieved.

(5-4) Alignment Film In this specification, the alignment film has an alignment regulating force that aligns the polymerizable liquid crystal compound in a desired direction.

Alignment films facilitate the alignment of polymerizable liquid crystal compounds. Liquid crystal alignment states, such as horizontal alignment, vertical alignment, hybrid alignment, and tilted alignment, vary depending on the properties of the alignment film and the polymerizable liquid crystal compound, and these combinations can be selected arbitrarily. For example, if the alignment film is made of a material that exerts a horizontal alignment force, the polymerizable liquid crystal compound can form horizontal or hybrid alignment. If the alignment film is made of a material that exerts a vertical alignment force, the polymerizable liquid crystal compound can form vertical or tilted alignment. Terms such as horizontal and vertical refer to the direction of the optical axis of the aligned polymerizable liquid crystal compound relative to the plane of the retardation film. For example, vertical alignment means that the optical axis of the aligned polymerizable liquid crystal compound is perpendicular to the plane of the retardation film. Here, "vertical" means 90°±20° relative to the plane of the retardation film.

When the alignment film is made of an alignment polymer, the alignment control force can be adjusted arbitrarily by changing the surface condition and rubbing conditions. When the alignment film is made of a photoalignment polymer, it can be adjusted arbitrarily by changing the polarized light irradiation conditions, etc. Furthermore, liquid crystal alignment can also be controlled by selecting the physical properties of the polymerizable liquid crystal compound, such as the surface tension and liquid crystallinity.

The alignment film formed between the substrate and the retardation film is preferably insoluble in the solvent used to form the retardation film on the alignment film, and is heat-resistant during the heat treatment required to remove the solvent and align the liquid crystal. Examples of alignment films include alignment films made of orientable polymers, photo-alignment films, groove-alignment films, and stretched films stretched in the alignment direction. When applied to long rolled films, photo-alignment films are preferred because the alignment direction can be easily controlled.

The thickness of the alignment film is typically in the range of 10 nm to 5000 nm, preferably 10 nm to 1000 nm, and more preferably 30 to 300 nm.

Examples of alignment polymers used in rubbed alignment films include polyamides and gelatins containing amide bonds in the molecule, polyimides containing imide bonds in the molecule, and their hydrolyzed products such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred. These alignment polymers may be used alone or in combination of two or more.

One method of rubbing is to bring an oriented polymer film formed on the surface of a substrate by applying an oriented polymer composition to the substrate and annealing it into contact with a rotating rubbing roll wrapped around a rubbing cloth.

Photo-alignment films are made of polymers, oligomers, or monomers with photoreactive groups. Photo-alignment films can obtain alignment control force by irradiating them with polarized light. Photo-alignment films are preferable because the direction of the alignment control force can be freely controlled by selecting the polarization direction of the irradiated polarized light.

A photoreactive group is a group that exhibits liquid crystal alignment ability upon exposure to light. Specifically, it is a group that undergoes a photoreaction that is the origin of liquid crystal alignment ability, such as molecular alignment induction or isomerization, dimerization, photocrosslinking, or photodecomposition upon exposure to light. Among such photoreactive groups, those that undergo dimerization or photocrosslinking are preferred because of their excellent alignment properties. Photoreactive groups capable of undergoing such reactions are preferably those having an unsaturated bond, particularly a double bond, and more preferably groups having at least one bond selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond).

Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Chalcone and cinnamoyl groups are preferred due to their ease of reactivity control and the ability to exert alignment control forces during photoalignment. Examples of photoreactive groups having a C=N bond include groups with structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, and formazan groups, as well as groups with an azoxybenzene basic structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

Polarized light can be irradiated either directly from the film surface or from the substrate side and then transmitted through the film. It is particularly preferable that the polarized light be substantially parallel. The wavelength of the polarized light irradiated should be within a wavelength range in which the photoreactive groups in the polymer or monomer having the photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) with a wavelength of 250 to 400 nm is particularly preferred. Examples of light sources used for polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. High-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are more preferred. These lamps are preferred because of the high emission intensity of ultraviolet light with a wavelength of 313 nm. Polarized light can be irradiated by passing light from the light source through an appropriate polarizer. Examples of such polarizers include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire-grid polarizers.

(6) Pressure-sensitive adhesive layer The optical laminate 1 of this embodiment has three types of pressure-sensitive adhesive layers (a pressure-sensitive adhesive layer in the linear polarizer, a pressure-sensitive adhesive layer 3 between the linear polarizer and the phase shifter, and a pressure-sensitive adhesive layer 42 in the phase shifter).

The linear polarizer internal adhesive layer (not shown in FIG. 1) is a layer provided as an optional component of the linear polarizer 2 for bonding the first protective film 21 to the polarizer 22 and for bonding the polarizer 22 to the second protective film 23. The optical laminate preferably includes both of these linear polarizer internal adhesive layers. The linear polarizer-to-phase shifter adhesive layer 3 is a layer provided for bonding the linear polarizer 2 to the phase shifter 4. The optical laminate preferably includes the linear polarizer-to-phase shifter adhesive layer 3. The phase shifter internal adhesive layer 42 is a layer used within the phase shifter 4 for bonding the first retardation layer 41 (e.g., a λ/4 retardation layer) to the second retardation layer 43 (e.g., a positive C plate).

The adhesive layer inside the linear polarizer, the adhesive layer 3 between the linear polarizer and the phaser, and the adhesive layer 42 inside the phaser may all be pressure-sensitive adhesive layers or adhesive layers. The adhesive layer is a layer formed from a pressure-sensitive adhesive composition (pressure-sensitive adhesive composition), and the adhesive layer is a layer formed from an adhesive composition. The adhesive layer inside the linear polarizer and the adhesive layer 42 inside the phaser are preferably adhesive layers. In particular, the adhesive layer 42 inside the phaser preferably has low moisture permeability from the perspective of suppressing the migration of the antistatic agent described below, and is therefore preferably made of an active energy ray-curable adhesive. Furthermore, to suppress cracking of the phaser, an adhesive layer with a higher elastic modulus than the adhesive layer is preferred. On the other hand, the adhesive layer 3 between the linear polarizer and the phaser is preferably a pressure-sensitive adhesive layer.

(6-1) Adhesive Layer Examples of adhesive compositions that form the adhesive layer include aqueous adhesive compositions and curable adhesive compositions that cure upon heating or irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays. Examples of aqueous adhesive compositions include those in which a polyvinyl alcohol resin or a urethane resin is dissolved in water as the main component, and those in which a polyvinyl alcohol resin or a urethane resin is dispersed in water as the main component. The aqueous adhesive composition may further contain a curable component or crosslinking agent such as a polyhydric aldehyde, a melamine compound, a zirconia compound, a zinc compound, a glyoxal compound, or a water-soluble epoxy resin. Examples of aqueous adhesive compositions include the adhesive composition described in JP 2010-191389 A, the adhesive composition described in JP 2011-107686 A, the composition described in JP 2020-172088 A, and the composition described in JP 2005-208456 A.

The curable adhesive composition is preferably an active energy ray-curable adhesive composition that contains a curable (polymerizable) compound as the main component and cures upon irradiation with active energy rays. Examples of active energy ray-curable adhesive compositions include cationic polymerization adhesive compositions that contain a cationic polymerizable compound as the curable compound, radical polymerization adhesive compositions that contain a radical polymerizable compound as the curable compound, and hybrid adhesive compositions that contain both a cationic polymerizable compound and a radical polymerizable compound as the curable compound.

Cationic polymerizable compounds are compounds or oligomers that undergo cationic polymerization and harden when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays, or when heated. Specific examples include epoxy compounds, oxetane compounds, and vinyl compounds. Epoxy compounds include alicyclic epoxy compounds (compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule) such as 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate; aromatic epoxy compounds (compounds having an aromatic ring and an epoxy group in the molecule) such as bisphenol A diglycidyl ether; and aliphatic epoxy compounds (compounds having at least one oxirane ring bonded to an aliphatic carbon atom in the molecule) such as 2-ethylhexyl glycidyl ether and 1,4-butanediol diglycidyl ether.

Examples of oxetane compounds include compounds having one or more oxetane rings in the molecule, such as 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane.

The cationic polymerization adhesive composition preferably contains a cationic polymerization initiator. The cationic polymerization initiator may be a thermal cationic polymerization initiator or a photo-induced cationic polymerization initiator. Examples of cationic polymerization initiators include aromatic diazonium salts such as benzenediazonium hexafluoroantimonate; aromatic iodonium salts such as diphenyliodonium tetrakis(pentafluorophenyl)borate; aromatic sulfonium salts such as triphenylsulfonium hexafluorophosphate; and iron-arene complexes such as xylene-cyclopentadienyl iron(II) hexafluoroantimonate. The content of the cationic polymerization initiator is typically 0.1 to 10 parts by mass per 100 parts by mass of the cationic polymerizable compound. Two or more types of cationic polymerization initiators may be used.

Examples of cationic polymerization adhesive compositions include the cationic polymerization compositions described in JP 2016-126345 A and JP 2021-113969 A.

Radically polymerizable compounds are compounds or oligomers that undergo a radical polymerization reaction and harden when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays, or when heated. Specific examples include compounds having an ethylenically unsaturated bond. Examples of compounds having an ethylenically unsaturated bond include (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, and vinyl compounds having one or more vinyl groups in the molecule.

Examples of (meth)acrylic compounds include (meth)acrylate monomers and (meth)acrylamide monomers having at least one (meth)acryloyloxy group in the molecule, and (meth)acryl group-containing compounds such as (meth)acrylic oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyl groups in the molecule.

The radical polymerization adhesive composition preferably contains a radical polymerization initiator. The radical polymerization initiator may be a thermal radical polymerization initiator or a photoradical polymerization initiator. Examples of radical polymerization initiators include acetophenone-based initiators such as acetophenone and 3-methylacetophenone; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; xanthone, fluorenone, etc. The content of the radical polymerization initiator is typically 0.1 to 10 parts by mass per 100 parts by mass of the radically polymerizable compound. Two or more types of radical polymerization initiators may be used.

Examples of radical polymerization adhesive compositions include the radical polymerization compositions described in JP 2016-126345 A, JP 2016-153474 A, and WO 2017/183335 A.

The active energy ray-curable adhesive composition may contain additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow control agents, plasticizers, antifoaming agents, antistatic agents, leveling agents, and solvents, as needed.

The bonding of two layers with an adhesive layer can be achieved by applying an adhesive composition to at least one of the bonding surfaces of each of the two layers, overlapping the two layers with the adhesive composition coating interposed between them, pressing them together from above and below using a laminating roll or the like, and then drying the adhesive layer, curing it by irradiating it with active energy rays, or curing it by heating.

Before forming the coating layer of the adhesive layer, at least one of the bonding surfaces of the two layers may be subjected to an adhesion-enhancing treatment such as saponification treatment, corona treatment, plasma treatment, primer treatment, or anchor coating treatment. Various coating methods can be used to form the coating layer of the adhesive composition, including die coaters, comma coaters, gravure coaters, wire bar coaters, and doctor blade coaters.

The light irradiation intensity when irradiating with active energy rays is determined depending on the composition of the active energy ray-curable adhesive composition and is not particularly limited, but is preferably 10 mW/ ^cm2 or more and 1,000 mW/ ^cm2 or less. The irradiation intensity is preferably an intensity in a wavelength range effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. Irradiation is performed once or multiple times at such a light irradiation intensity, and the cumulative light amount is preferably 10 mJ/ ^cm2 or more, and more preferably 100 mJ/ ^cm2 or more and 1,000 mJ/ ^cm2 or less.

The light source used to polymerize and cure the active energy ray-curable adhesive composition is not particularly limited, but examples include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The thickness of the adhesive layer formed from the aqueous adhesive composition may be, for example, 5 μm or less, preferably 1 μm or less, and more preferably 0.5 μm or less, and may be 0.01 μm or more, and preferably 0.05 μm or more. The thickness of the adhesive layer formed from the active energy ray-curable adhesive composition may be, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less, and may be 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1 μm or more.

(6-2) Pressure-sensitive Adhesive Layer As the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer, any conventionally known pressure-sensitive adhesive composition having excellent optical transparency can be used without particular limitation. For example, a pressure-sensitive adhesive composition having a base polymer such as a (meth)acrylic resin, a urethane resin, a silicone resin, or a polyvinyl ether resin can be used. Active energy ray-curable pressure-sensitive adhesive compositions, heat-curable pressure-sensitive adhesive compositions, etc. are also suitable. Among these, pressure-sensitive adhesive compositions having a (meth)acrylic resin as a base polymer, which is excellent in transparency, adhesive strength, removability, weather resistance, heat resistance, etc., are preferred. The pressure-sensitive adhesive composition may further contain a crosslinking agent, a silane compound, an antistatic agent, etc.

[(Meth)acrylic resin]
The (meth)acrylic resin contained in the pressure-sensitive adhesive composition is preferably a polymer (hereinafter also referred to as a "(meth)acrylic acid ester polymer") having as its main component (for example, containing 50 parts by mass or more per 100 parts by mass of the structural units of the (meth)acrylic resin) a structural unit derived from a (meth)acrylic acid alkyl ester represented by the following formula (VIII) (hereinafter also referred to as "structural unit (VIII)"):

[In formula (VIII), R ¹⁰ represents a hydrogen atom or a methyl group, and R ²⁰ represents an alkyl group having 1 to 20 carbon atoms, the alkyl group may have a linear, branched, or cyclic structure, and a hydrogen atom of the alkyl group may be substituted with an alkoxy group having 1 to 10 carbon atoms.]

Examples of the (meth)acrylic acid ester represented by formula (VIII) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, i-hexyl (meth)acrylate, n-heptyl (meth)acrylate, Examples of the alkoxy group-containing alkyl acrylate include n-octyl (meth)acrylate, i-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n- and i-nonyl (meth)acrylate, n-decyl (meth)acrylate, i-decyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, t-butyl (meth)acrylate, etc. Specific examples of the alkoxy group-containing alkyl acrylate include 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-methoxy-2-ethoxyethyl (meth)acrylate, etc. In particular, the alkoxy group-containing acrylate preferably accounts for 10% to 40% by mass, preferably 15% to 40% by mass, more preferably 15% to 35% by mass, and particularly preferably 20% to 35% by mass, based on the total amount of structural units constituting the (meth)acrylic resin (VIII). If this content is less than 10% by mass, the PSA's ionic conductivity is low, necessitating the addition of a large amount of antistatic agent to ensure the desired antistatic properties, resulting in reduced metal corrosion resistance. If it exceeds 40% by mass, the PSA's polarity increases, resulting in a high moisture content and adversely affecting PSA properties. Among these, n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is preferred as the alkyl acrylate, and n-butyl (meth)acrylate is particularly preferred. Furthermore, 2-methoxyethyl acrylate is preferred as the alkoxy group-containing acrylate.

The (meth)acrylic acid ester polymer may contain a structural unit derived from a monomer other than structural unit (VIII). The structural unit derived from the other monomer may be one type, or two or more types. Examples of other monomers that the (meth)acrylic acid ester polymer may contain include a monomer having a polar functional group, a monomer having an aromatic group, and a (meth)acrylamide-based monomer.

Monomers having a polar functional group include (meth)acrylates having a polar functional group. Examples of polar functional groups include hydroxy groups; carboxy groups; substituted or unsubstituted amino groups substituted with alkyl groups having 1 to 6 carbon atoms; and heterocyclic groups such as epoxy groups.

The content of structural units derived from monomers having polar functional groups in the (meth)acrylic acid ester polymer is preferably 10 parts by mass or less, more preferably 0.5 to 10 parts by mass, even more preferably 0.5 to 5 parts by mass, and particularly preferably 1 to 5 parts by mass, per 100 parts by mass of all structural units of the (meth)acrylic acid ester polymer.

Examples of monomers having an aromatic group include (meth)acrylic acid esters having one (meth)acryloyl group and one or more aromatic rings (e.g., benzene ring, naphthalene ring, etc.) in the molecule, and having a phenyl group, phenoxyethyl group, or benzyl group. The inclusion of these structural units can suppress the white spots that occur in polarizing plates in high-temperature, high-humidity environments.

The content of structural units derived from monomers having an aromatic group in the (meth)acrylic acid ester polymer is preferably 20 parts by mass or less, more preferably 4 parts by mass or more and 20 parts by mass or less, and even more preferably 4 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of all structural units of the (meth)acrylic acid ester polymer.

Examples of (meth)acrylamide monomers include N-(methoxymethyl)(meth)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-(propoxymethyl)(meth)acrylamide, N-(butoxymethyl)(meth)acrylamide, and N-(2-methylpropoxymethyl)(meth)acrylamide. The inclusion of these structural units can suppress the bleed-out of additives such as antistatic agents, which will be described later.

Furthermore, structural units derived from monomers other than structural unit (VIII) may include structural units derived from styrene-based monomers, structural units derived from vinyl-based monomers, structural units derived from monomers having multiple (meth)acryloyl groups in the molecule, and the like.

The weight-average molecular weight (hereinafter also referred to simply as "Mw") of the (meth)acrylic resin is preferably 500,000 to 2,500,000. A weight-average molecular weight of 500,000 or more can improve the durability of the pressure-sensitive adhesive layer in high-temperature, high-humidity environments. A weight-average molecular weight of 2,500,000 or less improves operability when applying a coating liquid containing the pressure-sensitive adhesive composition. In this specification, "weight-average molecular weight" and "number-average molecular weight" are polystyrene-equivalent values measured by gel permeation chromatography (GPC).

When the (meth)acrylic resin is dissolved in ethyl acetate to form a 20% by mass solution, the viscosity at 25°C is preferably 20 Pa·s or less, and more preferably 0.1 to 15 Pa·s. When the viscosity of the (meth)acrylic resin at 25°C is within this range, the occurrence of streaks during the production of a pressure-sensitive adhesive layer formed from the resin can be suppressed. The viscosity can be measured using a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth)acrylic resin is preferably in the range of -10 to -60°C, more preferably in the range of -20 to -50°C, and even more preferably in the range of -30 to -45°C. The glass transition temperature can be measured using a differential scanning calorimeter (DSC).

The (meth)acrylic resin may contain two or more types of (meth)acrylic acid ester polymers. Examples of such (meth)acrylic acid ester polymers include those with a weight-average molecular weight lower than the aforementioned (meth)acrylic acid ester polymers, which have a weight-average molecular weight of 500,000 to 2,500,000. More specifically, examples include (meth)acrylic acid ester polymers with a relatively low molecular weight, having a weight-average molecular weight in the range of 50,000 to 300,000, and containing structural unit (VIII) derived from a (meth)acrylic acid ester as the main component.

(Meth)acrylic resins can typically be produced by known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In producing (meth)acrylic resins, polymerization is typically carried out in the presence of a polymerization initiator. The amount of polymerization initiator used is typically 0.001 to 5 parts by mass per 100 parts by mass of the total of all monomers constituting the (meth)acrylic resin. (Meth)acrylic resins can also be produced by polymerization using active energy rays such as ultraviolet light.

[Crosslinking agent]
The pressure-sensitive adhesive composition preferably contains a crosslinking agent, such as a conventional crosslinking agent (e.g., an isocyanate compound, an epoxy compound, an aziridine compound, a metal chelate compound, a peroxide, etc.), and is particularly preferably an isocyanate compound from the viewpoints of the pot life of the pressure-sensitive adhesive composition, the crosslinking rate, and the durability of the optical laminate.

An isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule. Specific examples include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Other examples include adducts obtained by reacting these isocyanate compounds with polyols such as glycerol or trimethylolpropane, as well as dimers and trimers of these isocyanate compounds. Two or more isocyanate compounds may also be combined.

The proportion of the crosslinking agent is, for example, 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the (meth)acrylic resin.

[Silane Compound]
The pressure-sensitive adhesive composition may further contain a silane compound.
Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.
The silane compound may also contain an oligomer derived from the above silane compound.

The content of the silane compound in the pressure-sensitive adhesive composition is typically 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of the (meth)acrylic resin. A silane compound content of 0.01 parts by mass or more tends to improve adhesion between the pressure-sensitive adhesive layer and the adherend, while a content of 10 parts by mass or less tends to prevent the silane compound from bleeding out from the pressure-sensitive adhesive layer.

[Antistatic agent]
The pressure-sensitive adhesive layer may contain an antistatic agent. As the antistatic agent, those shown in "(7) Pressure-sensitive adhesive layer" below can be used.

[others]
The pressure-sensitive adhesive composition may contain one or more additives such as an ultraviolet absorber, a solvent, a crosslinking catalyst, a tackifier, a plasticizer, etc. It is also useful to blend an ultraviolet-curable compound into the pressure-sensitive adhesive composition, form a pressure-sensitive adhesive layer, and then cure the layer by irradiating it with ultraviolet light to form a harder pressure-sensitive adhesive layer.

The adhesive layer can be formed, for example, by dissolving or dispersing the adhesive composition in a solvent to form a solvent-containing adhesive composition, which is then applied to the surface of the substrate or the layer on which the adhesive layer is to be formed, and then drying.

The thickness of the adhesive layer is typically 0.1 to 30 μm, preferably 3 to 30 μm, and more preferably 5 to 25 μm.

(7) Pressure-sensitive adhesive layer The optical laminate 1 includes a pressure-sensitive adhesive layer 5 laminated on the side of the retarder 4 opposite to the linear polarizer 2. The basic structure of the pressure-sensitive adhesive layer 5 is the same as that described above in "(6-2) Pressure-sensitive adhesive layer." Here, the antistatic agent and thickness will be described.

[Antistatic agent]
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer 5 contains an antistatic agent, and the antistatic agent contains an ionic compound composed of an organic cation and an anion represented by the following formula (1).
(C _n F _2n+1 SO ₂ ) ₂ N ^- (1)
(In the formula, n is an integer from 0 to 5.)

Examples of the anion represented by formula (1) include bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ] where n is 1, and bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N ⁻ ] where n is 0.

Examples of organic cations include ammonium cations such as tributylmethylammonium cation, trioctylmethylammonium cation, trimethylpropylammonium cation, tetrabutylammonium cation, and (2-hydroxyethyl)trimethylammonium cation; phosphonium cations such as tributyldodecylphosphonium cation; pyridinium cations such as 1-hexylpyridinium cation, 1-octylpyridinium cation, 4-methyl-1-hexylpyridinium cation, 4-methyl-1-octylpyridinium cation, and 4-methyl-1-butylpyridinium cation; pyrrolidinium cations such as butylmethylpyrrolidinium cation and ethylmethylpyrrolidinium cation; imidazolium cations such as 1-ethyl-3-methylimidazolium cation and 1-butyl-3-methylimidazolium cation; pyrrolidinium cations; alkylammonium cations; sulfonium cations; and the like. Among these, pyrrolidinium cations and alkylammonium cations are particularly preferred because they are less likely to move between layers of the optical laminate 1. Furthermore, organic cations containing nitrogen atoms are preferred, and from the viewpoint of suppressing fluctuations in retardation characteristics when aromatic ring-containing compounds are transferred to the retarder during durability evaluation, aliphatic cations are more preferred, with pyrrolidinium cations and alkylammonium cations being even more preferred.

Ionic compounds that are solid at room temperature (have a melting point of 23°C or higher) are preferred because they provide excellent stability over time in the antistatic properties of the pressure-sensitive adhesive composition. There are no particular restrictions on the molecular weight of the ionic compound, but it is preferable that the molecular weight be 700 or less, and even 500 or less.

The content of the antistatic agent is, for example, 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, more preferably 0.1 to 2.5 parts by mass, and even more preferably 0.1 to 1.5 parts by mass, per 100 parts by mass of the (meth)acrylic resin. Inclusion of 0.1 parts by mass or more of antistatic agent per 100 parts by mass of the non-volatile content of the resin constituting the adhesive layer is preferred as this improves antistatic performance, while an amount of 10 parts by mass or less is preferred as this prevents bleed-out of ionic compounds from the adhesive layer during durability testing, making it easier to maintain durability.

The thickness T3 of the adhesive layer 5 is typically 5 μm or more, and preferably 10 μm or more. The thickness T3 of the adhesive layer 5 is typically 35 μm or less, and preferably 30 μm or less.

<Image display device>
The image display device includes the optical laminate according to the present invention and an image display element (such as an organic EL display element). The optical laminate is disposed on the viewing side of the image display element. The optical laminate can be attached to the image display element using a pressure-sensitive adhesive layer 5.

The image display device is not particularly limited, and examples include organic electroluminescence (organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, and electroluminescence display devices.

Image display devices can be used as mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic billboards, measuring instruments or gauges, office equipment, medical equipment, computing equipment, etc.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these embodiments. In the optical laminate 1 of the above embodiment, the outermost layers are the first protective film 21 and the pressure-sensitive adhesive layer 5. However, if necessary, the first protective film 21 may be provided with a surface protective film to protect its surface, and the pressure-sensitive adhesive layer 5 may be provided with a separator.

The present invention will be described in more detail below with reference to examples , reference examples , and comparative examples. It should be noted that the present invention is not limited to the following examples. In the following description, parts and percentages representing amounts used and contents are based on mass unless otherwise specified. Furthermore, in the following description, numbers such as "second protective film 3" and "adhesive layer 1" represent the types of the multiple types of second protective films, adhesive layers, etc. used, and are unrelated to the symbols in the drawings.

<Measurement and Evaluation>
(1) Thickness of Layer or Film Unless otherwise specified, the thickness of a layer or film was measured using a laser microscope ("LEXT" manufactured by Olympus Corporation) or a digital micrometer ("MH-15M" manufactured by Nikon Corporation).

(2) In-Plane Retardation Value of Layer or Film The in-plane retardation values [nm] of the layer or film at wavelengths of 550 nm and 450 nm were measured using a retardation measuring device (KOBRA-WPR, manufactured by Oji Scientific Instruments Co., Ltd.).

(3) Moisture Permeability of Protective Film The moisture permeability of the second protective film was measured under the following measurement conditions.
Test item: Water vapor permeability Test method: Moisture sensor method Measurement device: Lyssy L80 series water vapor permeability meter Sample preparation method: An aluminum mask was attached to the surface of the second protective film of a laminate described below that included a supporting substrate and a second protective film, and then the supporting substrate was peeled off and another aluminum mask was attached to this peeled surface to prepare a measurement sample. The second protective film 8 (a triacetyl cellulose film having a thickness of 20 μm) used in Comparative Example 1 did not have a supporting substrate, so the supporting substrate was not peeled off.
・Measurement conditions Measurement temperature: 40℃
Relative humidity: 90% RH
Measurement area:
Second protective films 1 to 4: 7.1×10 ⁻⁴ m ² (transmission area when mask is worn)
Second protective film 5: 7.9×10 ⁻⁵ m ² (transmission area when mask is worn)
Measurement sample installation direction: Any

(4) Water Vapor Permeability Coefficient of the Phase Element The water vapor permeability coefficient of the phase element was determined by determining the moisture permeability (unit: g/( ^m2 ·day)) of the phase element in the same manner as in (3) above, except that the measurement temperature was 65°C, and multiplying this by the thickness (unit: mm).

(5) Evaluation of Retardation Change The change in in-plane retardation value when the optical laminate was placed in a high-temperature, humid, and hot environment was measured and evaluated according to the following procedure. A 30 mm x 30 mm sample was cut out from the optical laminate, with the slow axis of the retarder in the long side direction. An evaluation sample was prepared by laminating the sample to alkali-free glass (manufactured by Corning, product number: EAGLE XG (registered trademark)) via the antistatic adhesive layer of the sample. The in-plane retardation values of the evaluation sample at wavelengths of 550 nm and 450 nm were measured using a retardation measurement device (manufactured by Oji Scientific Instruments, KOBRA-WPR). The obtained values were used to calculate the change in in-plane retardation value ΔRe(550) and the wavelength dispersion α (in-plane retardation value Re(450)/in-plane retardation value Re(550)). Five evaluation samples were measured, and the average value was calculated.

The evaluation sample was placed in an oven and subjected to a 336-hour wet heat durability test at a temperature of 60° C. and a relative humidity of 90% RH. The evaluation sample was removed from the oven, and after 3 hours, the in-plane retardation values at wavelengths of 550 nm and 450 nm were measured using the retardation measurement device described above, and the change in the in-plane retardation value ΔRe(550) before and after the heat resistance test was calculated.
A: ΔRe(550) is less than 0.5 B: ΔRe(550) is 0.5 or more and less than 0.7 C: ΔRe(550) is 0.7 or more

The evaluation sample was placed in an oven and subjected to a 504-hour moist heat durability test at a temperature of 60°C and a relative humidity of 90%RH. The evaluation sample was removed from the oven, and three hours later, the in-plane retardation values at wavelengths of 550 nm and 450 nm were measured using the retardation measurement device described above. The amount of change was calculated from the wavelength dispersion α (0 hours) before the heat resistance test and the wavelength dispersion α (504 hours) after the heat resistance test, and Δα, the rate of change in α, was calculated according to the following formula. Of the following criteria, A indicates a smaller change in wavelength dispersion α.
Δα (%) = (α (504 hours) - α (0 hours)) / α (0 hours) × 100
A: |Δα| is less than 0.2 B: |Δα| is 0.2 or more

(6) Evaluation of Metal Corrosion by Optical Laminate A metal-layered glass substrate was prepared by laminating a metal aluminum layer and a metal titanium layer in this order on the surface of an alkali-free glass substrate by sputtering. Next, the optical laminates obtained in the Examples , Reference Examples , and Comparative Examples were cut into pieces measuring 50 mm x 50 mm, and the metal titanium layer side of the metal-layered glass substrate was attached to the adhesive layer of the optical laminate to prepare an evaluation sample. The evaluation sample was stored in an oven at a temperature of 85°C and a relative humidity of 85% RH for 350 hours, and then removed from the oven. The evaluation sample was placed on a backlight with the glass substrate facing down, and the number and size of bright spots due to light leakage were observed to evaluate metal corrosion according to the following criteria.
A+: No bright spots A: 1 to 5 bright spots of 0.1 to 0.5 mm B+: 6 to 15 bright spots of 0.1 to 0.5 mm or 5 bright spots of 0.5 to 1.0 mm B: 6 to 15 bright spots of 0.5 to 1.0 mm C: More than 15 bright spots are observed over the entire surface, but there are some areas where there are no bright spots

[Preparation of Polarizer]
(1) Preparation of Polarizer 1 A polyvinyl alcohol film having a thickness of 20 μm, a degree of polymerization of 2,400, and a degree of saponification of 99.9% or more was uniaxially stretched to a draw ratio of 4.5 times in a dry manner, and while maintaining the tension, the film was immersed in a dye bath at 28° C. containing 0.05 parts of iodine and 5 parts of potassium iodide per 100 parts of water for 60 seconds.

Then, it was immersed for 110 seconds in boric acid aqueous solution 1 at 64°C, which contained 5.5 parts of boric acid and 15 parts of potassium iodide per 100 parts of water. It was then immersed for 30 seconds in boric acid aqueous solution 2 at 67°C, which contained 5.5 parts of boric acid and 15 parts of potassium iodide per 100 parts of water. It was then washed with pure water at 3°C and dried to obtain polarizer 1. The boron content of polarizer 1 measured by the above method was 4.1% by mass. The polarizer thickness was 8 μm.

(2) Preparation of Polarizer 2 A 30 μm-thick polyvinyl alcohol-based resin film (average degree of polymerization: approximately 2400, saponification degree: 99.9 mol% or more) was uniaxially stretched longitudinally by approximately 5 times by dry stretching, and then, while maintaining tension, was immersed in pure water at 60°C for 1 minute, and then immersed in an aqueous solution at 28°C having an iodine/potassium iodide/water mass ratio of 0.05/5/100 for 60 seconds. Thereafter, it was immersed in an aqueous solution at 72°C having a potassium iodide/boric acid/water mass ratio of 8.5/8.5/100 for 300 seconds. Subsequently, it was washed with pure water at 26°C for 20 seconds and then dried at 65°C to obtain a 12 μm-thick linear polarizer in which iodine was adsorbed and aligned in the polyvinyl alcohol-based resin film.

[Protective film production and preparation]
(1) Preparation of First Protective Film 1 As the first protective film 1, a triacetyl cellulose (TAC) film (KC2UATAC manufactured by Konica Minolta, Inc., thickness T1: 25 μm) having a 7 μm thick hard coat layer formed on one side (thickness T1: 32 μm) was prepared.

(2) Preparation of Second Protective Film 1 A 38 μm-thick polyethylene terephthalate film (PET film) ("TN100" manufactured by Toyobo Co., Ltd., having a release layer containing a non-silicone release agent) was prepared as a supporting substrate. The following components were blended to prepare a composition containing a thermoplastic resin.
Cyclic polyolefin resin (Zeonor ZF14 manufactured by Zeon Corporation): 10 parts Cyclohexane: 90 parts

A composition containing the above thermoplastic resin was applied onto the release layer of the supporting substrate using a die by a backcoating method, and the applied layer was then dried under conditions of 40°C for 1 minute, 70°C for 1 minute, and 120°C for 2 minutes to produce a laminate having a cyclic polyolefin resin layer with a thickness T2 of 2 μm as the second protective film 1. The moisture permeability of the second protective film 1 was 63 g/ ^m2 /24 hr.

(3) Preparation of second protective film 2 A laminate having a cyclic polyolefin resin layer with a thickness T2 of 3 μm was prepared as second protective film 2 in the same manner as second protective film 1, except that the amount of the composition containing a thermoplastic resin applied to the release layer of the supporting substrate was changed. The moisture permeability of second protective film 2 was 37 g/m ² /24 hr.

(4) Preparation of Second Protective Film 3 A laminate having a cyclic polyolefin resin layer with a thickness T2 of 4 μm was prepared as the second protective film 3 in the same manner as the preparation of the second protective film 1, except that the amount of the composition containing a thermoplastic resin applied to the release layer of the supporting substrate was changed. The moisture permeability of the second protective film 3 was 19 g/m ² /24 hr.

(5) Preparation of Second Protective Film 4 A cyclic polyolefin resin film having a thickness T2 of 13 μm was prepared as the second protective film 4. The moisture permeability of the second protective film 4 was 4.8 g/m ² /24 hr.

(6) Preparation of Second Protective Film 5 A triacetyl cellulose film having a thickness of 25 μm was prepared as the second protective film 5. The moisture permeability of the second protective film 5 was 1280 g/m2/24 hr.

[Preparation of active energy ray-curable adhesive]
(1) Preparation of Active Energy Ray-Curable Adhesive 1 The following components were blended and mixed, and then degassed to prepare Active Energy Ray-Curable Adhesive 1 (hereinafter simply referred to as "adhesive 1").
(cationically polymerizable compound)
3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name: CEL2021P, manufactured by Daicel Corporation): 70 parts; neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts; 2-ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts (photocationic polymerization initiator)
Product name: CPI-100 (manufactured by San-Apro Co., Ltd., 50% propylene carbonate solution): 4.5 parts (actual solid content 2.25 parts)
(Photosensitizing aid)
1,4-diethoxynaphthalene: 2 parts

[Preparation of Pressure-Sensitive Adhesive Layer]
The following pressure-sensitive adhesive layer 1 and pressure-sensitive adhesive layer 2 were prepared, each having a release film attached to both sides.
(1) Preparation of Pressure-Sensitive Adhesive Layer 1 Pressure-Sensitive Adhesive Layer 1 was prepared by the following procedure. In the Examples and Reference Examples described later, Pressure-Sensitive Adhesive Layer 1 is mainly used as a pressure-sensitive adhesive layer between a linear polarizer and a phase shifter, and in some examples, it is used as a pressure-sensitive adhesive layer inside the phase shifter.

(1-1) Preparation of Acrylic Resin Solution 1 A reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer was charged with a mixed solution of 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 parts of 2-hydroxyethyl acrylate, and 0.5 parts of acrylic acid. The air in the vessel was replaced with nitrogen gas to remove oxygen, and the internal temperature was raised to 55°C. Subsequently, the entire amount of a solution prepared by dissolving 0.12 parts of azobisisobutyronitrile (polymerization initiator) in 10 parts of ethyl acetate was added. After the addition of the polymerization initiator, the temperature was maintained for 1 hour. Next, ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54-56°C. When the concentration of the acrylic resin reached 35% by mass, the addition of ethyl acetate was stopped, and the mixture was further maintained at this temperature for 6 hours after the start of the ethyl acetate addition. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20% by mass, and acrylic resin solution 1 was prepared. The resulting acrylic resin had a weight-average molecular weight Mw of 1,700,000. Mw was measured in terms of standard polystyrene using two "TSKgel GMHHR-H(S)" columns (manufactured by Tosoh Corporation) connected in series as columns in a GPC apparatus, tetrahydrofuran as an eluent, a sample concentration of 2 mg/mL, a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

(1-2) Preparation of Pressure-Sensitive Adhesive Composition 1 To 80 parts of the solid content of the acrylic resin solution 1 obtained in (1-1) above, 20 parts (solid content) of bifunctional acrylate (obtained from Shin-Nakamura Chemical Co., Ltd.; product number "A-DOG"), 2.5 parts of a crosslinking agent (manufactured by Mitsui Chemicals: trade name "D-101E" (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75% by mass)) based on the active ingredient, 1.5 parts of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name "Irgacure 500"), and 0.3 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name "KBM-403") were added, and ethyl acetate was further added to make the solid content concentration 13% to obtain a pressure-sensitive adhesive composition 1.

A-DOG is a diacrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane, and has the following structure:

(1-3) Preparation of Pressure-Sensitive Adhesive Layer 1 The pressure-sensitive adhesive composition 1 prepared in (1-2) above was applied to the release-treated surface of a release film made of a release-treated polyethylene terephthalate film [manufactured by Mitsubishi Chemical: MRV (V04) (thickness: 38 μm)] using an applicator so that the thickness after drying, T3, was 5 μm, and the coating was dried at 100°C for 1 minute to prepare a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet). Next, the surface of the resulting pressure-sensitive adhesive layer opposite the release film side was bonded to the release-treated surface of a release film made of a release-treated polyethylene terephthalate film [manufactured by Mitsubishi Chemical: MRF (thickness: 38 μm)]. Subsequently, ultraviolet light was irradiated under the following conditions to prepare a pressure-sensitive adhesive layer 1. The storage modulus G' of the pressure-sensitive adhesive layer 1 at a temperature of 85°C was 0.125 MPa.
<UV irradiation conditions>
Fusion UV lamp system (manufactured by Fusion UV Systems) H bulb used. Integrated light intensity in the UV wavelength region UVA: 250 mJ/cm ² (measured by measuring device: UV Power Puck II manufactured by Fusion UV).

(2) Preparation of Pressure-Sensitive Adhesive Layer 2 An acrylic pressure-sensitive adhesive layer 2 was prepared by the following procedure. The pressure-sensitive adhesive layer 2 contains an antistatic agent, and in the Examples and Reference Examples described below, it is used as a pressure-sensitive adhesive layer to be attached to the side of the retarder opposite to the linear polarizer side.

(2-1) Preparation of Acrylic Resin Solution 2 A monomer mixture prepared by diluting 42.5 parts by mass of n-butyl acrylate, 5 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl acrylate, 30 parts by mass of 2-methoxyethyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, and 1.5 parts by mass of acrylic acid with ethyl acetate was charged into a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer, and the air inside the vessel was purged with nitrogen gas to remove oxygen, while the internal temperature was raised to 55° C. Thereafter, a solution of azobisisobutyronitrile dissolved in ethyl acetate as a polymerization initiator was added such that the amount of azobisisobutyronitrile was 0.3 parts by mass per 100 parts by mass of the total amount of monomers. After the addition of the polymerization initiator, the temperature was maintained at 55°C for 1 hour. Then, while maintaining the internal temperature at 54 to 56°C, ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hr. When the concentration of the acrylic resin reached 35%, the addition of ethyl acetate was stopped, and the temperature was maintained at 55°C for a further 12 hours from the start of the ethyl acetate addition. Ethyl acetate was then added to adjust the concentration of the acrylic resin to 20%, thereby preparing acrylic resin solution 2. The weight-average molecular weight Mw of the resulting acrylic resin was 1,580,000.

(2-2) Preparation of Pressure-Sensitive Adhesive Composition 2 - Pressure-Sensitive Adhesive Composition 2-1
To 100 parts by mass of the solid content of the acrylic resin solution 2 obtained above, 0.5 parts by mass (active ingredient basis) of a crosslinking agent, trade name "D-103" manufactured by Mitsui Chemicals, Inc. (an ethyl acetate solution (solid content concentration 75% by mass) of a trimethylolpropane adduct of tolylene diisocyanate), 0.5 parts by mass (active ingredient basis) of a silane compound, trade name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd. (3-glycidoxypropyltrimethoxysilane), and 0.54 parts by mass (active ingredient basis) of tributylmethylammonium bis(trifluoromethanesulfonyl)imide as an ionic compound were added, and ethyl acetate was further added so that the solid content concentration became 14%, thereby obtaining a pressure-sensitive adhesive composition 2-1 for producing a pressure-sensitive adhesive layer "AS-PSA1" described below.
Adhesive composition 2-2
A pressure-sensitive adhesive composition 2-2 for producing a pressure-sensitive adhesive layer "AS-PSA2" described below was obtained in the same manner as in the preparation of "(AS-PSA1)" above, except that the ionic compound was changed to butylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide in an amount of 0.47 parts by mass based on the active ingredient.
Adhesive composition 2-3
A pressure-sensitive adhesive composition 2-3 for producing a pressure-sensitive adhesive layer "AS-PSA3" described below was obtained in the same manner as in the preparation of "(AS-PSA1)" above, except that the ionic compound was changed to 4-methyl-1-octylpyridinium bis(trifluoromethanesulfonyl)imide in an amount of 0.51 parts by mass based on the active ingredient.
Adhesive composition 2-4
A pressure-sensitive adhesive composition 2-4 for producing a pressure-sensitive adhesive layer "AS-PSA4" described below was obtained in the same manner as in the preparation of "(AS-PSA1)" above, except that the ionic compound was changed to 4-methyl-1-octylpyridinium hexafluorophosphate in an amount of 0.41 parts by mass based on the active ingredient.

(2-3) Preparation of Pressure-Sensitive Adhesive Layers AS-PSA1, AS-PSA2, AS-PSA3, and AS-PSA4 The pressure-sensitive adhesive composition 2-1 obtained above was applied using an applicator to the release-treated surface of a release film (1) (manufactured by Mitsubishi Chemical Corporation, trade name "MRV38 (V04)", thickness: 38 μm) so that the thickness after drying would be 15 μm, and then dried at a temperature of 100°C for 1 minute to obtain a pressure-sensitive adhesive layer (1) having a thickness of 15 μm. A release film (2) (manufactured by Mitsubishi Chemical Corporation, trade name "MRF38", thickness: 38 μm) was laminated on the opposite side of the obtained pressure-sensitive adhesive layer (1) from the release film (1) so that the release-treated surface faced the pressure-sensitive adhesive layer (1). The obtained laminate was left to stand in an environment of a temperature of 23°C and a relative humidity of 60% for 7 days or more to obtain a pressure-sensitive adhesive layer AS-PSA1. Furthermore, pressure-sensitive adhesive layers AS-PSA2, AS-PSA3, and AS-PSA4 were obtained in the same manner as above, except that pressure-sensitive adhesive compositions 2-2, 2-3, and 2-4 were used as the pressure-sensitive adhesive compositions. These pressure-sensitive adhesive layers AS-PSA1, AS-PSA2, AS-PSA3, and AS-PSA4 are collectively referred to as "pressure-sensitive adhesive layer 2."

[Fabrication of the phase shifter]
(1) Preparation of retardation film A (1-1) Preparation of composition A for forming a photo-alignment film The photo-alignment material (weight average molecular weight: 50,000, m:n = 50:50) having the following structure was produced in accordance with the method described in JP-A-2021-196514. 2 parts of the photo-alignment material and 98 parts of cyclopentanone (solvent) were mixed as components, and the resulting mixture was stirred at 80 ° C. for 1 hour to prepare a composition A for forming a photo-alignment film.
Photoalignable material:

(1-2) Preparation of polymerizable liquid crystal compounds Polymerizable liquid crystal compound (A1) and polymerizable liquid crystal compound (A2) having the structures shown below were prepared. Polymerizable liquid crystal compound (A1) was prepared in the same manner as described in JP-A-2019-003177. Polymerizable liquid crystal compound (A2) was prepared in the same manner as described in JP-A-2009-173893.
Polymerizable liquid crystal compound (A1):

Polymerizable liquid crystal compound (A2):

A solution was obtained by dissolving 1 mg of polymerizable liquid crystal compound (A1) in 10 mL of chloroform. The resulting solution was placed in a measurement cell with an optical path length of 1 cm, and the measurement sample was placed in an ultraviolet-visible spectrophotometer (Shimadzu Corporation, "UV-2450") to measure the absorption spectrum. The wavelength at which maximum absorbance was obtained was read from the resulting absorption spectrum, and the maximum absorption wavelength λmax in the wavelength range of 300 to 400 nm was found to be 356 nm.

(1-3) Preparation of Retardation Film-Forming Composition A The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed in a mass ratio of 90:10 to obtain a mixture. To 100 parts of the obtained mixture, 0.1 parts of a leveling agent "BYK-361N" (manufactured by BM Chemie) and 3 parts of a photopolymerization initiator "Irgacure OXE-03" (manufactured by BASF Japan Ltd.) were added. Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solids concentration was 13%. This mixture was stirred at a temperature of 80 ° C. for 1 hour to prepare a retardation film-forming composition A.

(1-4) Preparation of Retardation Film A The photo-alignment film-forming composition A was applied to a biaxially stretched polyethylene terephthalate (PET) film (Diafoil; manufactured by Mitsubishi Plastics, Inc.) as the substrate A using a bar coater. The resulting coating film was dried at 120°C for 2 minutes and then cooled to room temperature to form a dry film. Thereafter, a UV irradiation device (SPOT CURE SP-9; manufactured by Ushio Inc.) was used to irradiate 100 mJ of polarized ultraviolet light (313 nm standard) to obtain a photo-alignment film A. The film thickness of the photo-alignment film A measured using an ellipsometer M-220 manufactured by JASCO Corporation was 100 nm.

The retardation film-forming composition A was applied onto the obtained photo-alignment film A using a bar coater to form a coating film. This coating film was heated and dried at 120°C for 2 minutes and then cooled to room temperature to obtain a dried film. Next, using a high-pressure mercury lamp ("Uniqure VB-15201BY-A" manufactured by Ushio Inc.), the dried film was irradiated with ultraviolet light at an exposure dose of 500 mJ/cm ² (based on 365 nm) under a nitrogen atmosphere to form a retardation film A in which the polymerizable liquid crystal compound was cured in a state where it was aligned horizontally relative to the plane of the substrate, and a laminate A consisting of substrate A/photo-alignment film A/retardation film A was obtained. The thickness of the retardation film A measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation was 2.0 μm.

The surface of the retardation film A of the laminate A was subjected to a corona treatment, and the laminate A was attached to glass via a 25 μm-thick pressure-sensitive adhesive layer (manufactured by Lintec Corporation), and then the substrate A was peeled off and removed. The in-plane retardation values for light with wavelengths of 450 nm, 550 nm, and 650 nm were calculated using Cauchy's dispersion formula obtained from the measurement results of the in-plane retardation values for light with wavelengths of 448.2 nm, 498.6 nm, 548.4 nm, 587.3 nm, 628.7 nm, and 748.6 nm.
As a result, the in-plane retardation values were Re(450)=122 nm, Re(550)=140 nm, and Re(650)=144 nm, and the relationship between the in-plane retardation values at each wavelength was as follows:
Re(450)/Re(550)=0.87
Re(650)/Re(550)=1.03
(In the formula, Re(450) represents the in-plane retardation value for light with a wavelength of 450 nm, Re(550) represents the in-plane retardation value for light with a wavelength of 550 nm, and Re(650) represents the in-plane retardation value for light with a wavelength of 650 nm.)

(2) Preparation of Retardation Film B (2-1) Preparation of Composition B for Forming Alignment Film 2-butoxyethanol was added to Sunever SE-610 (manufactured by Nissan Chemical Industries, Ltd.), a commercially available alignment polymer, so that the solid content was 1%, to obtain Composition B for forming an alignment film.

(2-2) Preparation of Retardation Film-Forming Composition B 100 parts of a polymerizable liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan), 0.1 parts of a leveling agent "BYK-361N" (manufactured by BYK-Chemie), and 2.5 parts of a photopolymerization initiator "Omnirad 907" (manufactured by IGM Resin B.V.) were mixed. Further, 400 parts of propylene glycol 1-monomethyl ether 2-acetate (PGME) was added, and the resulting mixture was stirred at a temperature of 80°C for 1 hour to prepare a retardation film-forming composition B.
Polymerizable liquid crystal compound LC242:

(2-3) Preparation of Retardation Film B A cyclic olefin resin (COP) film (ZF14, manufactured by Zeon Corporation) was used as the substrate B, and one side of the film was subjected to corona treatment using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.), and the alignment film-forming composition B was applied to the surface using a bar coater and dried for 1 minute at 90° C. The film thickness of the resulting alignment film B was measured with a laser microscope and found to be 30 nm.

A retardation film-forming composition B was applied onto the obtained alignment film B using a bar coater and dried at 90°C for 1 minute to obtain a dried film. The dried film was irradiated with ultraviolet light at an exposure dose of 1000 mJ/ ^cm2 (based on 365 nm) using a high-pressure mercury lamp (Uniqure VB-15201BY-A manufactured by Ushio Inc.) under a nitrogen atmosphere to form a retardation film B, thereby obtaining a laminate B consisting of substrate B/alignment film B/retardation film B. The thickness of the retardation film B, as measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation, was 450 nm.

When the retardation values were measured, Re(550) = 1 nm and Rth(550) = -75 nm. Laminate B had optical properties expressed as nx ≒ ny < nz. Note that the retardation value of the COP at a wavelength of 550 nm is approximately 0, so this does not affect the optical properties.

(3) Preparation of Retarder 1 The retardation film A of Laminate A and the retardation film B of Laminate B were each subjected to corona treatment. An adhesive was applied to the corona-treated surface of either the retardation film A or the retardation film B, and the laminates A and B were then bonded together. The adhesive 1 described above was used. The corona treatment device used was the AGF-B10 manufactured by Kasuga Electric Co., Ltd. The corona treatment was performed once using the corona treatment device described above at an output of 0.3 kW and a treatment speed of 3 m/min. Ultraviolet light was irradiated from the laminate A side to cure the adhesive 1, forming an adhesive layer 1 with a thickness of 1.5 μm. The ultraviolet light was irradiated so that UVA with a wavelength of 320 nm to 390 nm was 420 mJ/ ^cm² . In this way, a retarder 1 with a substrate was prepared, consisting of substrate A/photo-alignment film A/retardation film A/adhesive layer 1/retardation film B/alignment film B/substrate B.

(4) Preparation of Retarder 2 Retarder 2 was prepared in the same manner as in preparation of retarder 1, except that in preparation of retarder 1, laminate A and laminate B were bonded together using pressure-sensitive adhesive layer 1 instead of adhesive 1. In this manner, a substrate-attached retarder 2 consisting of substrate A/photo-alignment film A/retardation film A/pressure-sensitive adhesive layer 1/retardation film B/alignment film B/substrate B was prepared.

<Examples 1 to 8, Reference Examples 9 to 12, Comparative Example 1>
The first protective film 1 prepared above, a polarizer selected from the polarizers 1 and 2, a protective film selected from the second protective films 1 to 5, and a retarder selected from the retarders 1 and 2 were bonded together. Next, a pressure-sensitive adhesive layer was laminated on the surface of the retarder opposite to the second protective film side, thereby obtaining optical laminates of Examples 1 to 8, Reference Examples 9 to 12, and Comparative Example 1. Specific examples are as follows.

Corona treatment was performed on one side of each of the first and second protective films (or the surface of the second protective film of the laminate, if a laminate with a second protective film was used). A water-based adhesive was applied to one side of the polarizer, and the first protective film was then attached. A water-based adhesive was applied to the other side of the polarizer, and the second protective film (or a laminate with a second protective film) was then attached. The resulting film was then dried to obtain a polarizing plate. The water-based adhesive was prepared by dissolving 3 parts of carboxyl-modified polyvinyl alcohol (available from Kuraray Co., Ltd. under the trade name "KL-318") in 100 parts of water, and adding 1.5 parts of a water-soluble polyamide epoxy additive (Sumirez Resin 650 (30) manufactured by Taoka Chemical Co., Ltd., a 30% solids aqueous solution). This resulted in a laminate X (linear polarizing plate) consisting of the first protective film/adhesive layer/polarizer/adhesive layer/second protective film. Here, when a laminate having a second protective film is used, the laminate X will have a structure of first protective film/adhesive layer/polarizer/adhesive layer/second protective film/supporting substrate.

Next, corona treatment was applied to the surface of the second protective film of the laminate X (if the laminate X has a supporting substrate, the surface after peeling and removing the supporting substrate) and the surface exposed by peeling and removing the substrate A of the retarder. The corona treatment device used was the AGF-B10 manufactured by Kasuga Electric Co., Ltd. The corona treatment was performed once using the corona treatment device at an output of 0.3 kW and a treatment speed of 3 m/min. The corona-treated surface of the laminate X and the corona-treated surface of the retarder were bonded together via the pressure-sensitive adhesive layer 1. The substrate B of the retarder was then peeled and removed to obtain a laminate Y comprising, in this order, the first protective film/adhesive layer/polarizer/adhesive layer/second protective film/adhesive layer 1/photo-alignment film A/retardation film A/adhesive layer inside the retarder/retardation film B/alignment film B. Finally, the pressure-sensitive adhesive layer 2 was laminated on the surface of the laminate Y on the retardation film B side to obtain an optical laminate. The obtained optical laminate was evaluated using a retardation measurement device (KOBRA-WPR, manufactured by Oji Scientific Instruments Co., Ltd.), and the in-plane retardation value and wavelength dispersion of the retarder were found to be Re(550) = 140 nm and α = 0.87, respectively.

The following table shows the types of the first protective film, polarizer, second protective film, retarder, and pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer laminated on the surface of the retarder opposite to the second protective film) used in Examples 1 to 8, Reference Examples 9 to 12, and Comparative Example 1. The following table also shows the results of evaluation of the amount of change in retardation and evaluation of metal corrosion performed on each optical laminate.

The results shown in Tables 1 and 2 indicate that when the second protective film has low moisture permeability and the pressure-sensitive adhesive layer contains a predetermined antistatic material, changes in retardation characteristics and metal corrosion are sufficiently suppressed (comparison of Examples 1 to 8, Reference Examples 9 to 12 with Comparative Example 1). Furthermore, when pressure-sensitive adhesive layer 1 is used as the pressure-sensitive adhesive layer within the retarder, the degree of suppression of metal corrosion is slightly weakened (Example 7, Reference Examples 10 and 12). Furthermore, when the thickness of the second protective film is increased, the degree of suppression of metal corrosion is slightly weakened ( Reference Examples 9 to 12). Furthermore, when the thickness of the second protective film is too thin, the degree of suppression of metal corrosion is slightly weakened (Examples 2 and 5).

The present invention can be used as a circular polarizer.

1...optical laminate, 2...linear polarizer, 3...adhesive layer between linear polarizer and retarder, 4...retarder, 5...adhesive layer, 21...first protective film, 22...polarizer, 23...second protective film, 41...first retardation layer, 42...adhesive layer in retarder, 43...second retardation layer.

Claims (7)

An optical laminate including a first protective film, a polarizer, a second protective film, a retarder, and a pressure-sensitive adhesive layer in this order,
The second protective film has a moisture permeability of 1200 g/( ^m2 ·day) or less,
The thickness of the second protective film is 0.1 to 8 μm,
the water vapor permeability coefficient of the retarder is 100 or less,
the pressure-sensitive adhesive layer contains an antistatic agent,
The antistatic agent comprises an ionic compound composed of an organic cation and an anion represented by the following formula (1):
(C _n F _2n+1 SO ₂ ) ₂ N ^- (1)
(In the formula, n is an integer from 0 to 5.) The optical laminate of claim 1, wherein the retarder includes a first retardation layer, an adhesive layer, and a second retardation layer, and has λ/4 plate functionality across the entire visible light range. The optical laminate according to claim 2, wherein the adhesive layer is made of an active energy ray-curable adhesive. The optical laminate according to claim 1, wherein the second protective film is made of a cyclic polyolefin resin. The optical laminate according to claim 1 , wherein the first protective film has a moisture permeability of 100 g/(m ² ·day) or more. The optical laminate according to claim 1, wherein the ionic compound includes an organic cation containing a nitrogen atom. The optical laminate according to any one of claims 1 to 6 ,
and an image display panel to which the optical laminate is attached.