WO2022130766A1

WO2022130766A1 - Foldable polarizing plate

Info

Publication number: WO2022130766A1
Application number: PCT/JP2021/038216
Authority: WO
Inventors: 友樹澤
Original assignee: 住友化学株式会社
Priority date: 2020-12-14
Filing date: 2021-10-15
Publication date: 2022-06-23
Also published as: CN116670742A; KR20230116822A; JP2022094078A; TW202225748A

Abstract

[Problem] To provide a foldable polarizing plate including a thin-film cured layer disposed between a display module and a pressure-sensitive-adhesive layer laminated adjacent to a window unit, the thin-film cured layer having a thickness of 5 µm or less, wherein the foldable polarizing plate is not prone to breaking or cracking even when repeatedly bent about the display module side thereof as a bending center. [Solution] A foldable polarizing plate disposed between a display module and a pressure-sensitive-adhesive layer laminated adjacent to a window unit, said foldable polarizing plate including a thin-film cured layer having a thickness of 5 µm or less, and the thin-film cured layer being present only in a range of 0-90% in the thickness direction from the outermost surface of the display module side of the foldable polarizing plate, 100% being the thickness of the foldable polarizing plate. [Selected drawing] None

Description

Foldable polarizing plate

The present invention relates to a foldable polarizing plate, and also relates to an image display device including the foldable polarizing plate.

As seen in the market in recent years, folderable smart devices have appeared, and the display (image display device) used may be required to be flexible. When the display is bent, bending stress and strain are applied to the members constituting the display. Therefore, it is necessary to design materials specifically for the members constituting the display used for the foldable device. Patent Document 1 proposes a bendable circular polarizing plate including a polarizing element and a retardation film as a member used in a bendable display device.

Japanese Unexamined Patent Publication No. 2014-170221

When designing a polarizing plate specialized for foldable devices, the major problem is cracks and cracks that occur when bent. It is often difficult to apply the design of a rigid display polarizing plate to a foldable device as it is. The polarizing plate is a laminated film in which a plurality of functional films are laminated, but a thin and hard layer is particularly liable to break due to bending. If such a layer is cracked, panel light may leak from the cracked portion, or if the touch panel or light emitting layer is cracked, display may not be possible.

An object of the present invention is a foldable polarizing plate which is arranged between a pressure-sensitive adhesive layer laminated adjacent to a window unit and a display module and includes a thin film cured layer having a thickness of 5 μm or less, and is a display module. It is an object of the present invention to provide a foldable polarizing plate in which cracks and cracks are unlikely to occur even when the side is repeatedly bent with the bending center as the bending center.
Another object of the present invention is a foldable polarizing plate including a thin film cured layer in which a linear polarizing layer and a retardation layer are laminated and having a thickness of 5 μm or less, and the retardation layer side is set with reference to the linear polarizing layer. It is an object of the present invention to provide a foldable polarizing plate in which cracks and cracks are unlikely to occur even when repeatedly bent as a bending center.

The present invention provides the following foldable polarizing plate and image display device.
[1] A foldable polarizing plate arranged between a pressure-sensitive adhesive layer laminated adjacent to a window unit and a display module.
Includes a thin film cured layer with a thickness of 5 μm or less
The thin film cured layer exists only in the range of 0% or more and 90% or less in the thickness direction from the outermost surface of the foldable polarizing plate on the display module side when the thickness of the foldable polarizing plate is 100%. , Foldable polarizing plate.
[2] The foldable polarizing plate according to [1], wherein the Martens hardness of the thin film cured layer at 23 ° C. is 150 N / mm ² or more and 800 N / mm ² or less.
[3] The foldable polarizing plate according to [1] or [2], which has a thickness of 20 μm or more and 150 μm or less.
[4] An image display device including the foldable polarizing plate according to any one of [1] to [3].
[5] A foldable polarizing plate in which a linear polarizing layer and a retardation layer are laminated.
Includes a thin film cured layer with a thickness of 5 μm or less
When the thickness of the foldable polarizing plate is 100%, the thin film cured layer is 0% or more in the thickness direction from the outermost surface on the retardation layer side with respect to the linear polarizing layer of the foldable polarizing plate. Foldable polarizing plate that exists only in the range within%.

According to one aspect of the present invention, it is a foldable polarizing plate including a thin film cured layer arranged between a pressure-sensitive adhesive layer laminated adjacent to a window unit and a display module and having a thickness of 5 μm or less. It is possible to provide a foldable polarizing plate in which cracks and cracks are unlikely to occur even when the display module side is repeatedly bent with the bending center as the bending center.
According to another aspect of the present invention, it is a foldable polarizing plate including a thin film cured layer in which a linear polarizing layer and a retardation layer are laminated and having a thickness of 5 μm or less, and the retardation layer is based on the linear polarizing layer. It is possible to provide a foldable polarizing plate in which cracks and cracks are unlikely to occur even when the side is repeatedly bent with the bending center as the bending center.

It is a schematic sectional drawing which shows an example of the structure in which a foldable polarizing plate is arranged. It is a schematic sectional drawing which shows an example of the layer structure of the foldable polarizing plate which concerns on 1st Embodiment. It is schematic cross-sectional view which shows another example of the layer structure of the foldable polarizing plate which concerns on 1st Embodiment. It is a schematic sectional drawing which shows still another example of the layer structure of the foldable polarizing plate which concerns on 1st Embodiment. It is the schematic sectional drawing which shows the other example of the layer structure of the foldable polarizing plate which concerns on 1st Embodiment. It is a schematic cross-sectional view which shows an example of the layer structure of the foldable polarizing plate which concerns on the 2nd aspect. It is a schematic cross-sectional view which shows another example of the layer structure of the foldable polarizing plate which concerns on the 2nd aspect. It is schematic cross-sectional view which shows an example of the layer structure of the laminated body for a foldable image display device. It is a schematic diagram for demonstrating the evaluation method of bending resistance. It is a schematic diagram for demonstrating the measuring method of Martens hardness.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scales are appropriately adjusted and shown in order to make each component easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

<Foldable polarizing plate>
[First aspect]
The foldable polarizing plate according to the first aspect includes a thin film cured layer arranged between a pressure-sensitive adhesive layer laminated adjacent to a window unit and a display module and having a thickness of 5 μm or less. This thin film cured layer exists only in the range of 0% or more and 90% or less in the thickness direction from the outermost surface of the foldable polarizing plate on the display module side when the thickness of the foldable polarizing plate is 100%.

The foldable polarizing plate 1 shown in FIG. 1 is arranged between the pressure-sensitive adhesive layer 3 laminated adjacent to the window unit 2 and the display module 4. The foldable polarizing plate 1 is preferably arranged so that one surface is in direct contact with the pressure-sensitive adhesive layer 3 laminated adjacent to the window unit 2, and the other surface is in direct contact with the display module 4. .. The window unit 2 can be, for example, a front plate. The display module 4 can be, for example, a touch sensor panel, an image display element, or the like. As the pressure-sensitive adhesive layer 3, those exemplified as the bonding layer described later are applied.

In the present specification, foldable means that the linear polarizing layer in the foldable polarizing plate can be bent along the bending axis when the transmission axis direction is defined as the bending axis. The foldable polarizing plate 1 can be bent with the display module side as the inside. Bending includes a form of bending in which a curved surface is formed on the bent portion. In the form of bending, the bending radius of the bent inner surface is not particularly limited. Bending also includes a form of refraction in which the refraction angle of the inner surface is greater than 0 ° and less than 180 °, and a form of folding in which the bending radius of the inner surface is close to zero or the refraction angle of the inner surface is 0 °. ..

In the present specification, the crack is a crack observed in the thin film cured layer when the foldable polarizing plate is observed in a plan view by the transmitted light of an optical microscope. In the present specification, the term “cracking” refers to a crack in a layer other than the thin film cured layer due to a crack in the thin film cured layer. Cracks and cracks can be observed according to the methods described in the Examples section below.

When the foldable polarizing plate 1 is repeatedly bent so that the bending radius of the inner surface is 1.5 mm along the bending axis with the surface on the display module side as the inner side, the number of bendings is preferably 50,000 times. No cracks occur, and more preferably, no cracks occur even at 80,000 times.

The foldable polarizing plate may be long or single-wafered. The foldable polarizing plate is preferably single-leafed. The single-wafer-shaped foldable polarizing plate can be obtained by cutting from a long foldable polarizing plate. When the foldable polarizing plate is single-leafed, the planar view shape of the foldable polarizing plate may be, for example, a square shape, preferably a square shape having a long side and a short side, and more preferably a rectangle. .. When the plan view shape of the foldable polarizing plate is rectangular, the length of the long side may be, for example, 10 mm or more and 1400 mm or less, preferably 50 mm or more and 600 mm or less. The length of the short side is, for example, 5 mm or more and 800 mm or less, preferably 30 mm or more and 500 mm or less, and more preferably 50 mm or more and 300 mm or less. In addition, in this specification, a plan view means a view from the thickness direction of a layer.

When the plan view shape of the foldable polarizing plate is a square shape, the lengths of the sides of each layer constituting the foldable polarizing plate may be the same as each other. The corners of each layer constituting the foldable polarizing plate may be R-processed, the edges may be notched, or holes may be formed.

The thickness of the foldable polarizing plate may be, for example, 20 μm or more and 150 μm or less, preferably 25 μm or more and 130 μm or less. The thickness of the foldable polarizing plate is the thickness when the foldable polarizing plate is arranged between the pressure-sensitive adhesive layer laminated adjacent to the window unit and the display module. The foldable polarizing plate has an adhesive layer described later on the outermost surface on the display module side for bonding to the display module, and the adhesive layer in which the foldable polarizing plate is laminated adjacent to the window unit and the display module. If there is an adhesive layer when placed between and, the thickness of the foldable polarizing plate includes the thickness of the adhesive layer. Even if the foldable polarizing plate has a separator film or a protective film before being arranged between the pressure-sensitive adhesive layer laminated adjacent to the window unit and the display module, the foldable polarizing plate can be used in the window unit. If the foldable polarizing plate does not have the separator film or the protective film when placed between the adhesive layer laminated adjacently and the display module, the thickness of the foldable polarizing plate does not include the thickness of the separator film or the protective film. ..

The foldable polarizing plate can be used for an image display device. The image display device may be any such as a liquid crystal display device and an organic EL display device. The foldable polarizing plate may be arranged on the front side (visual recognition side) of the image display device, or may be arranged on the back side. Since the foldable polarizing plate of the present invention is bendable, it is suitable for a foldable image display device.

When the image display device is a liquid crystal display device, the foldable polarizing plate can be arranged as a polarizing plate including a polarizing plate arranged on the front side of the front side or the back side of the liquid crystal cell.
When the image display device is an organic EL display device, the foldable polarizing plate can be arranged on the front side as a circular polarizing plate arranged on the front side for the purpose of preventing reflection of external light.

When the foldable polarizing plate is a circular polarizing plate, the foldable polarizing plate can have antireflection performance. In the image display device, by providing a foldable polarizing plate having antireflection performance on the front side of the image display device, it is possible to suppress a decrease in visibility due to reflection of external light.

[Thin film hardened layer]
Although not shown, the foldable polarizing plate 1 includes a thin film cured layer having a thickness of 5 μm or less. The thin film cured layer can be a layer containing a cured product of a curable resin. Examples of the thin film cured layer include a cured resin layer formed on a polarizing element protective layer which is a thermoplastic resin film, a coating protective layer, an adhesive layer for adhering a linear polarizing layer and a polarizing element protective layer, and a phase difference. Among the adhesive layers for adhering the liquid crystal cured layer and the retardation layer contained in the layer, those having a thickness of 5 μm or less can be mentioned. When the thickness of the thin film cured layer exceeds 5 μm, cracks and cracks tend to easily occur in the thin film cured layer. Layers other than the thin film cured layer will be described later.

The thickness of the thin film cured layer is preferably 4.5 μm or less, more preferably 4 μm or less. The thickness of the thin film cured layer 100 is usually 0.5 μm or more.

The thin film cured layer exists only in the range T1 of 0% or more and 90% or less in the thickness direction from the outermost surface of the foldable polarizing plate 1 on the display module 4 side when the thickness of the foldable polarizing plate 1 is 100%. Since the thin film cured layer exists only within the range T1, even when the foldable polarizing plate 1 is repeatedly bent with the display module 4 side as the inside, cracks and cracks tend to be less likely to occur.

The thin film cured layer exists only in the range of preferably 0% or more and 90% or less in the thickness direction from the outermost surface of the foldable polarizing plate 1 on the display module 4 side when the thickness of the foldable polarizing plate 1 is 100%. , More preferably, it is present only in the range of 0% or more and 75% or less, and further preferably, it is present only in the range of 0% or more and 60% or less.

The Martens hardness of the thin film cured layer at a temperature of 23 ° C. (hereinafter, also simply referred to as Martens hardness for simplification) may be, for example, 150 N / mm ² or more and 800 N / mm ² or less. When the Martens hardness of the thin film hardened layer is within the above range, cracks tend to be less likely to occur. Martens hardness can be measured according to the method described in the Examples section below.

The Martens hardness of the thin film cured layer is preferably 150 N / mm ² or more and 700 N / mm ² or less, and more preferably 150 N / mm ² or more and 600 N / mm ² or less from the viewpoint of resistance to cracking.

The Martens hardness of the thin film cured layer can be adjusted by, for example, a method of adjusting the composition of the composition for forming the thin film cured layer used for forming the thin film cured layer. Examples of the method for adjusting the composition of the composition for forming a thin film cured layer include a method for adjusting the type and / or content of the polymerizable monomer and the additive constituting the curable resin. Further, it is also possible to select and use a commercially available product having a predetermined Martens hardness.

The foldable polarizing plate may have a function as a linear polarizing plate including a polarizing element protection layer and a linear polarizing layer, or may have a function as a circular polarizing plate including a linear polarizing plate and a retardation layer. It may have. The foldable polarizing plate 10 shown in FIG. 2 includes a polarizing element protective layer 100, a cured resin layer 101, an adhesive layer 102, a linear polarizing layer 103, a bonded layer 104, and a liquid crystal cured layer (not shown). The retardation layer 105 including the above is provided in this order. The foldable polarizing plate 10 may further include a layer other than the above-mentioned layer. Examples of the other layer include a protective film, an adhesive layer and the like.

[Polar protector protection layer]
The polarizing element protective layer 100 is a layer for protecting the surface of the linear polarizing layer 103, particularly the linear polarizing layer 103. The polarizing element protective layer 100 can be arranged on one side or both sides of the linear polarizing layer 103 via only the adhesive layer or directly. In the present specification, the linear polarizing layer 103 on which the polarizing element protection layer 100 is arranged may be referred to as a linear polarizing plate.

The polarizing element protective layer 100 can be formed from, for example, a thermoplastic resin film or a coating protective layer. The foldable polarizing plate 10 may have the polarizing element protection layer 100 on only one side of the linear polarizing layer 103, or may have the polarizing element protection layer 100 on both sides. When the foldable polarizing plate 10 has polarizing element protective layers on both sides of the linear polarizing layer 103, the polarizing element protective layers 100 may be of the same type or different types. When the polarizing element protective layer 100 is a thermoplastic resin film, the polarizing element protective layer 100 can be bonded to the linear polarizing layer 103 via an adhesive layer described later. When the polarizing element protective layer 100 is a thermoplastic resin film, the polarizing element protective layer 100 can include a cured resin layer 101, which will be described later. The foldable polarizing plate 10 preferably contains a thermoplastic resin film.

[Thermoplastic resin film]
The thermoplastic resin film that can be used as the polarizing element protective layer 100 can be incorporated into the foldable polarizing plate 10 in the form of being bonded to one side or both sides of the linear polarizing layer 103. The thermoplastic resin film may be, for example, a translucent, preferably optically transparent thermoplastic resin film, and examples thereof include a chain polyolefin resin (polyethylene resin, polypropylene resin, poly). Methylpentene resin, etc.), Cyclic polyolefin resin (Norbornen resin, etc.) and other polyolefin resins; Triacetyl cellulose and other cellulose resins; Polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate and other polyester resins; Polycarbonate resin Resins; ethylene-vinyl acetate resin; polystyrene resin; polyamide resin; polyetherimide resin; (meth) acrylic resin such as polymethyl (meth) acrylate resin; polyimide resin; polyether sulfone resin; polysulfone system Resins; polyvinyl chloride-based resins; polyvinylidene chloride-based resins; polyvinyl alcohol-based resins; polyvinyl acetal-based resins; polyether ketone-based resins; polyether ether ketone-based resins; polyether sulfone-based resins; polyamideimide-based resins, etc. Be done. The thermoplastic resin can be used alone or in combination of two or more. Among them, a triacetyl cellulose-based resin film, a cyclic polyolefin-based resin film, and a (meth) acrylic-based resin film are preferable from the viewpoint of strength and translucency.

The thickness of the thermoplastic resin film may be, for example, 30 μm or less, preferably 25 μm or less from the viewpoint of thinning, and usually 1 μm or more, preferably 5 μm or more, and further preferably 15 μm or more. .. The thermoplastic resin film may or may not have a phase difference.

[Curing resin layer]
The cured resin layer 101 is a layer containing a cured product of the curable resin. The cured resin layer 101 can be a layer having functions such as a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an antistatic layer, an antifouling layer, and a conductive layer.

Examples of the curable resin include thermosetting resins and active energy ray curable resins. The cured product of the curable resin can be formed from a composition for forming a cured resin layer containing the curable resin. The composition for forming a curable resin layer may be, for example, a thermosetting composition, a cationic curable composition, a radical curable composition, or the like. The composition for forming a cured resin layer can contain, for example, a polymerizable monomer, a polymerization initiator, an additive, a solvent and the like. Additives include, for example, plasticizers, UV absorbers, infrared absorbers, colorants such as pigments and dyes, optical brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, etc. Examples thereof include lubricants and surfactants.

When the cured resin layer 101 is a hard coat layer, it is possible to easily improve the hardness and scratch property of the linear polarizing layer 103 or the polarizing element protective layer 100. When the thermoplastic resin film includes a cured resin layer 101 which is a hard coat layer, for example, a composition for forming a hard coat layer is applied and cured on the thermoplastic resin film forming the polarizing element protective layer 100, and the hard coat is applied. A thermoplastic resin film provided with a hard coat layer can be produced by forming a cured product of the forming composition, and then bonded to the linear polarizing layer 103 via the adhesive layer 102. A thermoplastic resin film provided with a commercially available cured resin layer can also be used as the stator protective layer 100.

The hard coat layer can be formed from a cured product of a composition for forming a hard coat layer containing an active energy ray-curable resin. Examples of the active energy ray-curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, epoxy resins and the like. The hardcourt layer may contain additives to improve its strength. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, or a mixture thereof. The hardcourt layer preferably contains a UV absorber.

The thickness of the cured resin layer 101 may be, for example, 5 μm or less, preferably 4 μm or less. The thickness of the thin film cured layer 100 is usually 0.5 μm or more.

[Adhesive layer]
The adhesive layer 102 used for bonding the linear polarizing layer 103 and the polarizing element protective layer 100 (or the cured resin layer 101), which is a thermoplastic resin film, is an active energy ray-curable adhesive such as an ultraviolet curable adhesive. It can be formed from an aqueous solution of a polyvinyl alcohol-based resin, an aqueous solution containing a cross-linking agent, or a water-based adhesive such as a urethane-based emulsion adhesive. When the thermoplastic resin films are bonded to both sides of the linear polarizing layer 103, the adhesives forming the two adhesive layers may be of the same type or different types. For example, when a thermoplastic resin film is bonded on both sides, one side may be bonded using a water-based adhesive and the other side may be bonded using an active energy ray-curable adhesive. The ultraviolet curable adhesive may be a mixture of a radically polymerizable (meth) acrylic compound and a photoradical polymerization initiator, a mixture of a cationically polymerizable epoxy compound and a photocationic polymerization initiator, and the like. Further, a cationically polymerizable epoxy compound and a radically polymerizable (meth) acrylic compound may be used in combination, and a photocationic polymerization initiator and a photoradical polymerization initiator may be used in combination as an initiator. The thickness of the adhesive layer may be, for example, 0.1 μm or more and 5 μm or less.

When using an active energy ray-curable adhesive, the adhesive is cured by irradiating it with active energy rays after bonding. The light source of the active energy ray is not particularly limited, but an active energy ray (ultraviolet ray) having a emission distribution having a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, and the like. Black light lamps, microwave-excited mercury lamps, metal halide lamps and the like are preferably used.

Corona treatment, flame treatment, and plasma treatment on one or both of the bonded surfaces in order to improve the adhesiveness between the linear polarizing layer 103 and the polarizing element protective layer 100 (or the cured resin layer 101) which is a thermoplastic resin film. , UV irradiation treatment, primer coating treatment, saponification treatment and other surface treatments may be performed.

[Coating protective layer]
The coating protective layer may be formed by applying a cationically curable composition such as an epoxy resin or a radically curable composition such as (meth) acrylate and curing it, and is coated with an aqueous solution of a polyvinyl alcohol-based resin or the like. It may be dried, and if necessary, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or a dye, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, etc. It may contain an antioxidant, an antioxidant, a lubricant and the like.

When the polarizing element protective layer 100 is a coating protective layer, the thickness of the polarizing element protective layer 100 may be, for example, 0.1 μm or more and 30 μm or less, preferably 0.5 μm or more and 20 μm or less, more preferably from the viewpoint of thinning. Is 1 μm or more and 10 μm or less.

[Linear polarizing layer]
The linear polarizing layer 103 is a linear polarizing element having a property of absorbing linear polarization having a vibration plane parallel to the absorption axis and transmitting linear polarization having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). There can be. Examples of the linear polarizing layer include a stretched film or a stretched layer on which a dichroic dye is adsorbed. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. For dichroic organic dyes, C.I. I. Included are dichroic direct dyes made of disazo compounds such as DIRECT RED 39 and dichroic direct dyes made of compounds such as trisazo and tetrakisazo.

A linear polarizing layer, which is a stretched film having a dichroic dye adsorbed (hereinafter, may be abbreviated as "stretched film"), will be described. The stretched film on which the bicolor dye is adsorbed is usually a step of uniaxially stretching the polyvinyl alcohol-based resin film, and a step of dyeing the polyvinyl alcohol-based resin film with the bicolor dye to adsorb the bicolor dye. , And the polyvinyl alcohol-based resin film on which the bicolor dye is adsorbed can be produced through a step of treating with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. The thickness of the linear polarizing layer, which is a stretched film on which the dichroic dye is adsorbed, may be, for example, 2 μm or more and 40 μm or less.

The polyvinyl alcohol-based resin is obtained by saponifying the polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith is used. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.

A film made of such a polyvinyl alcohol-based resin is used as a raw film for a stretched film. The method for forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a known method. The film thickness of the polyvinyl alcohol-based raw film may be, for example, 10 μm or more and 150 μm or less.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with a dichroic dye, at the same time as dyeing, or after dyeing. If the uniaxial stretching is performed after staining, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. It is also possible to perform uniaxial stretching at these multiple stages. In uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched, or thermal rolls may be used to uniaxially stretch the rolls. Further, the uniaxial stretching may be a dry stretching in which stretching is performed in the atmosphere, or a wet stretching in which the polyvinyl alcohol-based resin film is swollen using a solvent. The draw ratio is usually about 3 times or more and 8 times or less.

Dyeing of a polyvinyl alcohol-based resin film with a dichroic dye is performed, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. For dichroic organic dyes, C.I. I. A dichroic direct dye composed of a disazo compound such as DIRECT RED 39 and a dichroic direct dye composed of a compound such as trisazo and tetrakisazo are included. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

When iodine is used as a dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide and dyeing is usually adopted. The iodine content in this aqueous solution is usually 0.01 parts by mass or more and 1 part by mass or less per 100 parts by mass of water. The content of potassium iodide is usually 0.5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually 20 ° C. or higher and 40 ° C. or lower. The immersion time (staining time) in this aqueous solution is usually 20 seconds or more and 1,800 seconds or less.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing is usually adopted.
The content of the bicolor organic dye in this aqueous solution is usually 1 × 10 ^-4 parts by mass or more and 10 parts by mass or less, preferably 1 × 10 ^-3 parts by mass or more and 1 part by mass or less per 100 parts by mass of water. Yes, more preferably 1 × 10 ^-3 parts by mass or more and 1 × 10 ^-2 parts by mass or less. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dichroic dye aqueous solution used for dyeing is usually 20 ° C. or higher and 80 ° C. or lower. The immersion time (staining time) in this aqueous solution is usually 10 seconds or more and 1,800 seconds or less.

The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid aqueous solution. The content of boric acid in this aqueous boric acid solution is usually 2 parts by mass or more and 15 parts by mass or less, preferably 5 parts by mass or more and 12 parts by mass or less, per 100 parts by mass of water. When iodine is used as the dichroic dye, this aqueous boric acid preferably contains potassium iodide, and the content of potassium iodide in that case is usually 0.1 mass by mass per 100 parts by mass of water. It is 5 parts by mass or more and 15 parts by mass or less, preferably 5 parts by mass or more and 12 parts by mass or less. The immersion time in the boric acid aqueous solution is usually 60 seconds or more and 1,200 seconds or less, preferably 150 seconds or more and 600 seconds or less, and more preferably 200 seconds or more and 400 seconds or less. The temperature of the boric acid treatment is usually 50 ° C. or higher, preferably 50 ° C. or higher and 85 ° C. or lower, and more preferably 60 ° C. or higher and 80 ° C. or lower.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of water in the washing treatment is usually 5 ° C. or higher and 40 ° C. or lower. The immersion time is usually 1 second or more and 120 seconds or less.

After washing with water, a drying treatment is performed to obtain a stretched film on which a dichroic dye is adsorbed. The drying process can be performed using, for example, a hot air dryer or a far-infrared heater. The temperature of the drying treatment is usually 30 ° C. or higher and 100 ° C. or lower, preferably 50 ° C. or higher and 80 ° C. or lower. The drying treatment time is usually 60 seconds or more and 600 seconds or less, preferably 120 seconds or more and 600 seconds or less. By the drying treatment, the moisture content of the stretched film on which the dichroic dye is adsorbed is reduced to a practical level. The water content is usually 5% by mass or more and 20% by mass or less, preferably 8% by mass or more and 15% by mass or less. When the moisture content is less than 5% by mass, the flexibility of the stretched film on which the dichroic dye is adsorbed is lost, and the stretched film on which the dichroic dye is adsorbed is damaged or broken after drying. Sometimes. Further, if the water content exceeds 20% by mass, the thermal stability of the stretched film on which the dichroic dye is adsorbed may deteriorate.

Next, a linearly polarizing layer, which is a stretched layer on which a dichroic dye is adsorbed (hereinafter, may be abbreviated as “stretched layer”) will be described. The stretched layer on which the bicolor dye is adsorbed is usually a step of applying a coating liquid containing the above polyvinyl alcohol resin on a substrate to obtain a laminated film, a step of uniaxially stretching the obtained laminated film, and uniaxial stretching. The step of dyeing the polyvinyl alcohol-based resin layer of the laminated film with a bicolor dye and adsorbing it, the step of treating the film on which the bicolor dye is adsorbed with a boric acid aqueous solution, and washing with water after the treatment with a boric acid aqueous solution. It can be manufactured through a process.
As an example of the base material, those exemplified in the description of the polarizing element protective layer described later are applied.
The base material may be peeled off from the stretched layer, or the base material may be used as a polarizing element protective layer. The thickness of the base material may be, for example, 5 μm or more and 200 μm or less. When the substrate is incorporated into the foldable polarizing plate 10, the thickness of the substrate film is preferably 30 μm or less.

[Lated layer]
The bonding layer 104 for bonding the linear polarizing layer 103 and the retardation layer 105 can be usually a pressure-sensitive adhesive layer formed of a pressure-sensitive pressure-sensitive adhesive (hereinafter, also referred to as a pressure-sensitive adhesive).

The thickness of the pressure-sensitive adhesive layer may be, for example, in the range of 1 μm or more and 50 μm or less, preferably 2 μm or more and 45 μm or less, more preferably 3 μm or more and 30 μm or less, and further preferably 5 μm or more and 20 μm or less.

The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition containing a resin as a main component, such as (meth) acrylic, rubber, urethane, ester, silicone, and polyvinyl ether. Above all, a pressure-sensitive adhesive composition using a (meth) acrylic resin as a base polymer is preferable from the viewpoint of transparency, weather resistance, heat resistance and storage elastic modulus. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

Examples of the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2- (meth) acrylate. A polymer or copolymer having one or more (meth) acrylic acid esters such as ethylhexyl as a monomer is preferably used. It is preferable that the base polymer is copolymerized with a polar monomer. Examples of the polar monomer include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylic acid, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, and glycidyl ( Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as meth) acrylate.

The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a divalent or higher metal ion that forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound that forms an amide bond with a carboxyl group; poly. Epoxy compounds and polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group are exemplified. Of these, polyisocyanate compounds are preferable.

To form the pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive composition is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare a pressure-sensitive adhesive liquid, which is directly applied to the target surface of a foldable polarizing plate. A method for forming an adhesive layer or a sheet-like adhesive layer is formed on a separate film that has been subjected to a mold release treatment, and the adhesive layer is transferred to the target surface of the linear polarizing layer 103 or the retardation layer 105. It can be done by a method or the like.

The separate film can be a film made of a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, or the like. Of these, a stretched film of polyethylene terephthalate is preferable.

The pressure-sensitive adhesive layer contains optional components such as glass fibers, glass beads, resin beads, fillers composed of metal powder and other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents and the like. Can be done.

Examples of the antistatic agent include ionic compounds, conductive fine particles, conductive polymers and the like, and ionic compounds are preferably used.
The cation component constituting the ionic compound may be an inorganic cation or an organic cation.
Examples of the organic cation include pyridinium cation, imidazolium cation, ammonium cation, sulfonium cation, phosphonium cation, piperidinium cation, pyrrolidinium cation and the like, and examples of the inorganic cation include lithium ion and potassium ion.
On the other hand, the anion component constituting the ionic compound may be an inorganic anion or an organic anion, but an anion component containing a fluorine atom is preferable because it provides an ionic compound having excellent antistatic performance. As anion components containing a fluorine atom, hexafluorophosphate anion [(PF _6- ⁾ ], bis (trifluoromethanesulfonyl) imide anion [(CF ₃ SO ₂ ) ₂ N- ^] anion, bis (fluorosulfonyl) imide anion [ (FSO ₂ ) ₂ N- ^] Anions and the like can be mentioned.

[Phase difference layer]
The retardation layer 105 can be arranged on the bending axis side when the foldable polarizing plate 10 is bent toward the display module side. The retardation layer 105 can be laminated on the linear polarizing layer 103 via the bonding layer 104. The retardation layer 105 can be a positive A layer such as a λ / 4 layer or a λ / 2 layer, and a positive C layer. The retardation layer 103 may be formed from a liquid crystal cured layer, or may be formed from a resin film exemplified as the material of the above-mentioned thermoplastic resin film. When the retardation layer 103 includes a liquid crystal curing layer, the retardation layer 103 may further include an adhesive layer, an alignment layer, and a base material described later.

The retardation layer 105 preferably includes a λ / 4 layer, more preferably a λ / 4 layer, and at least one of a λ / 2 layer and a positive C layer. When the retardation layer 105 includes the λ / 2 layer, the λ / 2 layer and the λ / 4 layer can be laminated in order from the linear polarizing layer 103 side. When the retardation layer 105 includes the positive C layer, the λ / 4 layer and the positive C layer may be laminated in order from the linear polarizing layer 103 side, and the positive C layer and the λ / 4 layer may be stacked in order from the linear polarizing layer 103 side. It may be laminated.

The thickness of the retardation layer 105 may be, for example, 0.1 μm or more and 50 μm or less, preferably 1 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 15 μm or less.

The liquid crystal cured layer is a layer of a cured product cured by polymerizing a polymerizable liquid crystal compound. The liquid crystal cured layer may be one in which the polymerizable liquid crystal compounds are polymerized with each other in a liquid crystal oriented state. The polymerizable liquid crystal compound may be oriented in-plane or vertically. When the polymerizable liquid crystal compound is oriented in the plane, the liquid crystal cured layer becomes a positive A layer showing an in-plane phase difference. When the polymerizable liquid crystal compound is vertically oriented, it becomes a positive C layer showing a phase difference in the thickness direction.
The polymerizable liquid crystal compound is a compound having a polymerizable group and can be in a liquid crystal state. The polymerizable liquid crystal compound is cured by the reaction between the polymerizable groups of the polymerizable liquid crystal compound and the polymerization of the polymerizable liquid crystal compound.

The liquid crystal curing layer included in the retardation layer 105 may be one layer, two layers, or three or more layers. When the retardation layer 105 includes two or more liquid crystal curing layers, the liquid crystal curing layers are usually laminated with each other via an adhesive layer. The retardation layer 105 includes an alignment layer for orienting a polymerizable liquid crystal compound when forming a base material and / or a liquid crystal curing layer, in addition to a liquid crystal curing layer and an adhesive layer for laminating them. good. When the retardation layer 105 has a substrate, the substrate is usually removed when the retardation layer 105 is attached to the linear polarizing layer 103.

The adhesive used for the adhesive layer includes an active energy ray-curable adhesive such as an ultraviolet curable adhesive, an aqueous solution of a polyvinyl alcohol-based resin or an aqueous solution containing a cross-linking agent, a urethane-based emulsion adhesive, and the like. Water-based adhesives can be mentioned. When the retardation layer contains two or more adhesive layers, the adhesives may be of the same type or of different types. The thickness of the adhesive layer may be, for example, 0.1 μm or more and 5 μm or less.

The type of the polymerizable liquid crystal compound is not particularly limited, but can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) according to its shape. Further, there are a small molecule type and a high molecular type, respectively. The polymer generally means a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). Any polymerizable liquid crystal compound can be used in the present invention. Further, two or more kinds of rod-shaped liquid crystal compounds, two or more kinds of disc-shaped liquid crystal compounds, or a mixture of rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds may be used. As the rod-shaped liquid crystal compound, for example, the compound described in claim 1 of JP-A No. 11-513019 can be preferably used. As the disk-shaped liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013]-[0108] of JP-A-2010-244033 are preferable. Can be used.

Two or more kinds of polymerizable liquid crystal compounds may be used in combination. In that case, at least one type has two or more polymerizable groups in the molecule. That is, the layer obtained by curing the polymerizable liquid crystal compound is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

The polymerizable liquid crystal compound has a polymerizable group capable of carrying out a polymerization reaction. As the polymerizable group, for example, a functional group capable of an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable. More specifically, examples of the polymerizable group include (meth) acryloyl group, vinyl group, styryl group, allyl group and the like. Among them, the (meth) acryloyl group is preferable. The (meth) acryloyl group is a concept that includes both a meta-acryloyl group and an acryloyl group.

The liquid crystal property of the polymerizable liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, and if the thermotropic liquid crystal is classified by order, it may be a nematic liquid crystal or a smectic liquid crystal.

The liquid crystal cured layer can be formed by applying a composition containing a polymerizable liquid crystal compound (hereinafter, also referred to as a composition for forming a retardation layer) onto, for example, an alignment layer and irradiating it with active energy rays. .. The composition for forming a retardation layer may contain components other than the above-mentioned polymerizable liquid crystal compound. For example, it is preferable that the composition for forming a retardation layer contains a polymerization initiator. As the polymerization initiator used, for example, a thermal polymerization initiator or a photopolymerization initiator is selected depending on the type of the polymerization reaction. For example, examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimers and p-aminophenyl ketones. The amount of the polymerization initiator used is preferably 0.01% by mass or more and 20% by mass or less, and 0.5% by mass or more and 5% by mass or less, based on the total solid content in the coating liquid. Is more preferable. The cured product is a state in which the formed layer alone can exist independently without being deformed or flowed.

Further, the composition for forming a retardation layer may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Among them, a polyfunctional radically polymerizable monomer is preferable.

The polymerizable monomer is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. The amount of the polymerizable monomer used is preferably 1% by mass or more and 50% by mass or less, and more preferably 2% by mass or more and 30% by mass or less, based on the total mass of the polymerizable liquid crystal compound.

Further, the composition for forming a retardation layer may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine-based compounds are particularly preferable.

Further, the composition for forming a retardation layer may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amide (eg, N, N-dimethylformamide), sulfoxide (eg, dimethylsulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide (eg, eg). , Chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Among them, alkyl halides and ketones are preferable. Further, two or more kinds of organic solvents may be used in combination.

Further, the composition for forming the retardation layer includes a vertical alignment agent such as a polarizing element interface side vertical alignment agent and an air interface side vertical alignment agent, and a polarizing element interface side horizontal alignment agent, an air interface side horizontal alignment agent and the like. Various alignment agents such as the horizontal alignment accelerator may be contained. Further, the composition for forming a retardation layer may contain an adhesion improver, a plasticizer, a polymer and the like in addition to the above components.

The active energy ray includes ultraviolet rays, visible light, electron beams, and X-rays, and is preferably ultraviolet rays. Examples of the light source of the active energy ray include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excima laser, and a wavelength range. Examples thereof include LED light sources that emit light of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like.

The irradiation intensity of ultraviolet rays is usually 100 mW / cm ² or more and 3,000 mW / cm ² or less in the case of ultraviolet B waves (wavelength range 280 nm or more and 310 nm or less). The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the cationic polymerization initiator or the radical polymerization initiator. The time for irradiating with ultraviolet rays is usually 0.1 seconds or more and 10 minutes or less, preferably 0.1 seconds or more and 5 minutes or less, more preferably 0.1 seconds or more and 3 minutes or less, and further preferably 0. . 1 second or more and 1 minute or less.

Ultraviolet rays can be irradiated once or in a plurality of times. Although it depends on the polymerization initiator used, the integrated light amount at a wavelength of 365 nm is preferably 700 mJ / cm ² or more, more preferably 1,100 mJ / cm ² or more, and 1,300 mJ / cm ² or more. It is more preferable to do so. The integrated light amount is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the liquid crystal cured layer and improving the heat resistance. The integrated light amount at a wavelength of 365 nm is preferably 2,000 mJ / cm ² or less, and more preferably 1,800 mJ / cm ² or less. The integrated light intensity may lead to coloring of the liquid crystal cured layer.

The thickness of the liquid crystal cured layer is, for example, 0.5 μm or more and 5 μm or less. When the thickness of the liquid crystal cured layer is within the above range, sufficient durability can be obtained and the foldable polarizing plate 10 can be contributed to thinning. The thickness of the liquid crystal cured layer can be adjusted so as to obtain a desired in-plane retardation value and a retardation value in the thickness direction of the λ / 4 layer, the λ / 2 layer or the positive C layer.

The retardation layer 105 may include a stack of a plurality of retardation layers having different retardation characteristics. Each retardation layer may be laminated using an adhesive, or a composition containing a polymerizable liquid crystal compound may be applied to the surface of the already formed retardation layer and cured.

[Base material]
The layer containing the cured product of the polymerizable liquid crystal compound can be formed, for example, on the alignment layer provided on the substrate. The base material has a function of supporting the alignment layer and may be a long base material. This base material functions as a releasable support and can support a liquid crystal curing layer or an alignment layer for transfer. Further, it is preferable that the surface has an adhesive force that can be peeled off. Examples of the base material include a translucent, preferably optically transparent thermoplastic resin film. Examples of the thermoplastic resin film include those exemplified in the above description of the stator protective layer.

The base material may be subjected to various blocking prevention treatments. Examples of the blocking prevention treatment include an easy-adhesion treatment, a treatment of kneading a filler and the like, an embossing treatment (knurling treatment) and the like. By applying such a blocking prevention treatment to the base material, it is possible to effectively prevent the base materials from sticking to each other when the base material is wound, so-called blocking, and the productivity tends to be improved easily. be.

[Orientation layer]
The layer containing the cured product of the polymerizable liquid crystal compound is formed on the substrate via the alignment layer. That is, the base material and the alignment layer are laminated in this order, and the layer containing the cured product of the polymerizable liquid crystal compound is laminated on the alignment layer.

The alignment layer is not limited to the vertical alignment layer, and may be an alignment layer that horizontally aligns the molecular axis of the polymerizable liquid crystal compound, or may be an alignment layer that tiltly aligns the molecular axis of the polymerizable liquid crystal compound. .. The alignment layer has solvent resistance that does not dissolve due to coating of a composition containing a polymerizable liquid crystal compound, which will be described later, and heat resistance in heat treatment for removing the solvent and aligning the liquid crystal compound. preferable. Examples of the alignment layer include an alignment layer containing an orientation polymer, a photoalignment film, and a grub alignment layer in which an uneven pattern or a plurality of grooves are formed and oriented on the surface. The thickness of the oriented layer is usually in the range of 10 nm or more and 10,000 nm or less.

Further, the alignment layer has a function of supporting the liquid crystal cured layer and may function as a releasable support. A liquid crystal curing layer for transfer can be supported, and the surface thereof may have an adhesive strength to the extent that it can be peeled off.

As the resin used for the alignment layer, a resin obtained by polymerizing a polymerizable compound is used. The polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid crystalline non-liquid crystal compound that does not become a liquid crystal state. The polymerizable groups of the polymerizable compound react with each other to polymerize the polymerizable compound, thereby forming a resin. Such a resin is used as an alignment layer for orienting a polymerizable liquid crystal compound at the stage of forming the liquid crystal cured layer, and if it is not contained in the liquid crystal cured layer, it is used as a material for a known oriented layer. The resin is not particularly limited, and a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth) acrylate-based monomer under a polymerization initiator can be used. Specifically, examples of the (meth) acrylate-based monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, and trimethyl propanetriacrylate. , Lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate. , Cyclohexyl methacrylate, methacrylic acid, urethane acrylate and the like can be exemplified. The resin may be one of these or a mixture of two or more.
The alignment layer can be peeled off together with the substrate before and after the step of forming the retardation layer and then laminating it with the linear polarizing layer or the like.

Further, the alignment layer can be included in the liquid crystal curing layer for the purpose of improving the peelability from the substrate and imparting the film strength to the liquid crystal curing layer. When the liquid crystal cured layer contains an oriented layer, it is preferable to use a cured product obtained by curing a monofunctional or bifunctional (meth) acrylate-based monomer, an imide-based monomer, or a vinyl ether-based monomer as the resin used for the oriented layer.
Examples of the monofunctional (meth) acrylate-based monomer include alkyl (meth) acrylates having 4 to 16 carbon atoms, βcarboxyalkyl (meth) acrylates having 2 to 14 carbon atoms, and alkylated phenyl (meth) having 2 to 14 carbon atoms. Examples thereof include acrylates, methoxypolyethylene glycol (meth) acrylates, phenoxypolyethylene glycol (meth) acrylates and isobonyl (meth) acrylates.
Examples of the bifunctional (meth) acrylate-based monomer include 1,3-butanediol di (meth) acrylate; 1,3-butanediol (meth) acrylate; 1,6-hexanediol di (meth) acrylate; ethylene glycol di. (Meta) acrylate; Diethylene glycol di (meth) acrylate; Neopentyl glycol di (meth) acrylate; Triethylene glycol di (meth) acrylate; Tetraethylene glycol di (meth) acrylate; Polyethylene glycol diacrylate; Loyloxyethyl) ether; ethoxylated bisphenol A di (meth) acrylate; propoxylated neopentyl glycol di (meth) acrylate; ethoxylated neopentyl glycol di (meth) acrylate, 3-methylpentanediol di (meth) acrylate, etc. Can be mentioned.
Examples of the imide-based resin obtained by curing the imide-based monomer include polyamide and polyimide. The imide-based resin may be one of these or a mixture of two or more.
Further, the resin forming the alignment layer may contain a monomer other than the monofunctional or bifunctional (meth) acrylate-based monomer, the imide-based monomer and the vinyl ether-based monomer, but the monofunctional or bifunctional (meth) The content ratio of the acrylate-based monomer, the imide-based monomer, and the vinyl ether-based monomer may be 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more in the total monomer. ..

When the alignment layer is included in the retardation layer 105, the thickness of the alignment layer is usually in the range of 10 nm or more and 10,000 nm or less, and when the orientation of the retardation layer 105 is in-plane orientation with respect to the film surface, the alignment layer The thickness is preferably 10 nm or more and 1000 nm or less, and when the orientation of the retardation layer 105 is perpendicular to the film surface, it is preferably 100 nm or more and 10,000 nm or less. When the thickness of the oriented layer is within the above range, the peelability of the base material can be improved and appropriate film strength can be imparted.

[Other layers]
The foldable polarizing plate 10 may further have, for example, at least one of an adhesive layer and a protective film.

[Adhesive layer]
The foldable polarizing plate 10 may have an adhesive layer arranged on the outermost surface on the retardation layer 105 side. The adhesive layer can be a layer for attaching a display module such as a touch sensor panel or an image display element to the foldable polarizing plate 10. The adhesive layer can usually be composed of an adhesive. As the pressure-sensitive adhesive, conventionally known pressure-sensitive adhesives can be used without particular limitation, and pressure-sensitive adhesives having a base polymer such as an acrylic polymer, a urethane-based polymer, a silicone-based polymer, and a polyvinyl ether-based polymer can be used. Further, it may be an active energy ray-curable pressure-sensitive adhesive, a thermosetting pressure-sensitive adhesive, or the like.

[Protect film]
The foldable polarizing plate 10 can include a protective film for protecting the surface thereof, typically the surface of the cured resin layer 100. The protective film can be arranged on the outermost surface of the foldable polarizing plate 10. After the polarizing plate is attached to, for example, an image display element or another optical member, the protective film is peeled off and removed together with the pressure-sensitive adhesive layer contained therein.

The protect film is composed of, for example, a base film and an adhesive layer laminated on the base film. As for the pressure-sensitive adhesive layer, the above description of the bonded layer is applied. The resin constituting the base film is, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, or a thermoplastic resin such as a polycarbonate resin. be able to. A polyester resin such as polyethylene terephthalate is preferable.

The thickness of the protective film is not particularly limited, but is preferably in the range of, for example, 20 μm or more and 200 μm or less. When the thickness of the base material is 20 μm or more, the foldable polarizing plate 10 tends to be easily imparted with strength.

[Layer structure of foldable polarizing plate]
FIG. 3 is a schematic cross-sectional view showing another example of the layer structure of the foldable polarizing plate. The foldable polarizing plate 20 shown in FIG. 3 includes a polarizing element protective layer 100, a cured resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, a bonded layer 104, and a retardation layer 160. Are prepared in this order. The retardation layer 160 includes a first liquid crystal curing layer 161, a second adhesive layer 162, and a second liquid crystal curing layer 163. At least one of the cured resin layer 101, the first adhesive layer 102, the first liquid crystal cured layer 161, the second adhesive layer 162, and the second liquid crystal cured layer 163 can be a thin film cured layer.

FIG. 4 is a schematic cross-sectional view showing still another example of the layer structure of the foldable polarizing plate. The foldable polarizing plate 30 shown in FIG. 4 includes a protective film 180, a polarizing element protective layer 100, a cured resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, and a bonding layer 104. The retardation layer 160 is provided in this order. The retardation layer 160 includes a first liquid crystal curing layer 161, a second adhesive layer 162, and a second liquid crystal curing layer 163. At least one of the cured resin layer 101, the first adhesive layer 102, the first liquid crystal cured layer 161, the second adhesive layer 162, and the second liquid crystal cured layer 163 can be a thin film cured layer.

FIG. 5 is a schematic cross-sectional view showing another example of the layer structure of the foldable polarizing plate. The foldable polarizing plate 40 shown in FIG. 5 includes a polarizing element protective layer 100, a cured resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, a bonded layer 104, and a retardation layer 160. , And the adhesive layer 170 are provided in this order. The retardation layer 160 includes a first liquid crystal curing layer 161, a second adhesive layer 162, and a second liquid crystal curing layer 163. At least one of the cured resin layer 101, the first adhesive layer 102, the first liquid crystal cured layer 161, the second adhesive layer 162, and the second liquid crystal cured layer 163 can be a thin film cured layer.

[Second aspect]
The foldable polarizing plate according to the second aspect includes a thin film cured layer in which a linear polarizing layer and a retardation layer are laminated and have a thickness of 5 μm or less, and the thin film cured layer has a thickness of 100% of the foldable polarizing plate. The foldable polarizing plate exists only in the range of 0% or more and 90% or less in the thickness direction from the outermost surface on the retardation layer side with the linear polarizing layer of the foldable polarizing plate as a reference. As for the description of the shape, size, thickness and use of the foldable polarizing plate, the description in the above-mentioned first aspect is applied.

The foldable polarizing plate 5 shown in FIG. 6 includes a linear polarizing layer 6 and a retardation layer 7. As for the description of the linearly polarized light layer 6 and the retardation layer 7, the description in the first aspect described above is applied.

The foldable polarizing plate 5 can be bent with the retardation layer 7 side as the inside with respect to the linear polarizing layer 6. When the foldable polarizing plate 5 is repeatedly bent with the linear polarizing layer 6 as a reference and the retardation layer 7 side as the inner side so that the bending radius of the inner surface is 1.5 mm along the bending axis, the number of bendings is preferable. No cracks occur even at 50,000 times, and more preferably no cracks occur even at 80,000 times.

[Thin film hardened layer]
Although not shown in FIG. 6, the foldable polarizing plate 5 includes a thin film cured layer having a thickness of 5 μm or less. The thin film cured layer can be a layer containing a cured product of a curable resin. The description in the first aspect described above applies to the examples and preferred ranges of the type, thickness and maltens hardness of the thin film hardened layer.

When the thickness of the foldable polarizing plate 5 is 100%, the thin film cured layer is 0% or more and 90% or less in the thickness direction from the outermost surface on the retardation layer 7 side with the linear polarizing layer 6 of the foldable polarizing plate 5 as a reference. It exists only in the range T2 of. Since the thin film cured layer exists only in the range T2, cracks and cracks are less likely to occur even when the foldable polarizing plate 5 is repeatedly bent with the retardation layer 7 side as the inside with respect to the linear polarizing layer 6 as a reference. It is in.

When the thickness of the foldable polarizing plate 5 is 100%, the thin film cured layer is preferably 0% or more in the thickness direction from the outermost surface on the retardation layer 7 side with the linear polarizing layer 6 of the foldable polarizing plate 5 as a reference. It exists only in the range of% or less, more preferably exists only in the range of 0% or more and 75% or less, and more preferably exists only in the range of 0% or more and 60% or less.

FIG. 7 is a schematic cross-sectional view showing an example of the layer structure of the foldable polarizing plate according to the second aspect of the present invention. The foldable polarizing plate 50 shown in FIG. 7 includes a polarizing element protective layer 200, a cured resin layer 201, an adhesive layer 202, a linear polarizing layer 203, a bonded layer 204, and a liquid crystal cured layer (not shown). ) Is included in this order. At least one of the cured resin layer 201, the adhesive layer 202, and the liquid crystal cured layer can be a thin film cured layer.

The foldable polarizing plate 50 may further include a layer other than the above-mentioned layer. Examples of the other layer include a protective film, an adhesive layer and the like. The description of the above-mentioned first aspect of the stator protective layer 200, the cured resin layer 201, the adhesive layer 202, the linear polarizing layer 203, the bonding layer 204, the retardation layer 205, the protective film and the adhesive layer in the second aspect will be described. Applies.

[Manufacturing method of foldable polarizing plate]
When the foldable polarizing plate includes a polarizing element protective layer and a retardation layer and includes a cured resin layer as a thin film curing layer, the foldable polarizing plate is, for example, a polarizing element protective layer which is a thermoplastic resin film including a cured resin layer. By a method including a bonding step of bonding the linear polarizing layer and the linear polarizing layer via the adhesive layer, and then bonding the retardation layer via the bonding layer on the side opposite to the thin film cured layer side of the linear polarizing layer. Can be manufactured. In the bonding step, when the layers are bonded to each other via the bonding layer, one or both of the bonding surfaces are subjected to a surface activation treatment such as corona treatment in order to improve the adhesion. Is preferable. The cured resin layer, the linear polarizing layer and the retardation layer can be manufactured as described above.

The bonded layer can be prepared as an adhesive sheet. For the pressure-sensitive adhesive sheet, for example, a pressure-sensitive adhesive composition is prepared by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate, and a layer made of the pressure-sensitive adhesive is formed on a release film which has been subjected to a mold release treatment. It can be produced by forming it into a sheet shape and laminating another release film on the laminating layer. Each layer can be bonded by a method in which an adhesive sheet from which one release film has been peeled off is attached to one layer, then the other release film is peeled off, and the other layer is attached.

As a method of applying the adhesive liquid on the release film, a usual coating technique using a die coater, a comma coater, a reverse roll coater, a gravure coater, a rod coater, a wire bar coater, a doctor blade coater, an air doctor coater, etc. Should be adopted.

The release film is preferably composed of a plastic film and a release layer. Examples of the plastic film include polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, and polyolefin films such as polypropylene film. Further, the release layer can be formed from, for example, a composition for forming a release layer. The main component (resin) constituting the release layer forming composition is not particularly limited, and examples thereof include silicone resin, alkyd resin, acrylic resin, and long-chain alkyl resin.

<Image display device>
The foldable polarizing plate of the present invention can be used in an image display device. The image display device is a device having an image display panel, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the image display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, and the like. The foldable polarizing plate can be arranged on the visual side of the image display panel. The foldable polarizing plate can be laminated on an image display device, for example, via an adhesive layer. The image display device can be a foldable image display device.

<Laminate for foldable image display device>
The laminate for a foldable image display device is a laminate for a foldable image display device having a front plate on the visible side of the foldable polarizing plate and a touch panel described later on the side opposite to the front plate of the foldable polarizing plate. be able to. The foldable image display device is composed of a foldable image display device laminate and an organic EL display panel. The foldable image display device laminate is arranged on the visual side of the organic EL display panel and can be folded. It is configured. The laminated body for a foldable image display device may include a foldable polarizing plate and one or both of a front plate and a touch panel, and the stacking order thereof is arbitrary, but the front plate (from the visual recognition side). It is preferable that the window), the foldable polarizing plate, the touch panel, or the front plate, the touch panel, and the foldable polarizing plate are laminated in this order. The presence of the foldable polarizing plate on the visual side of the touch panel is preferable because the pattern on the touch panel is less likely to be visually recognized and the visibility of the displayed image is improved. Each member can be laminated using an adhesive, an adhesive, or the like. Further, a light-shielding pattern formed on at least one surface of any layer of the front plate, the foldable polarizing plate and the touch panel can be provided.

[Front plate]
A front plate may be arranged on the visual side of the foldable polarizing plate. The front plate can be laminated on the foldable polarizing plate via the adhesive layer. Examples of the pressure-sensitive adhesive layer include the above-mentioned pressure-sensitive adhesive layer.

Examples of the front plate include those having a hard coat layer on at least one surface of glass or a resin film. As the glass, for example, highly transparent glass or tempered glass can be used. Particularly when a thin transparent surface material is used, chemically strengthened glass is preferable. The thickness of the glass can be, for example, 20 μm or more and 5 mm or less.

The front plate including the hard coat layer on at least one surface of the resin film can be foldable instead of rigid like the existing glass. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 μm or more and 100 μm or less.

The resin film includes a cycloolefin derivative having a unit of a monomer containing a cycloolefin such as norbornene or a polycyclic norbornene-based monomer, and cellulose (diacetylcellulose, triacetylcellulose, acetylcellulosebutyrate, isobutyl ester cellulose). , Propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, Polypropylene, Polymethylpentene, Polyvinyl Chloride, Polyvinylidene Chloride, Polyvinyl Alcohol, Polyvinylacetal, Polyetherketone, Polyetheretherketone, Polyethersulne, Polymethylmethacrylate, Polyethyleneterephthalate, Polybutyleneterephthalate, Polyethylenenaphthalate, Polycarbonate , Polyurethane, epoxy and other polymers may be used. As the resin film, an unstretched uniaxial or biaxially stretched film can be used. Each of these polymers can be used alone or in combination of two or more. As the resin film, a polyamideimide film or a polyimide film having excellent transparency and heat resistance, a uniaxial or biaxially stretched polyester film, and a cycloolefin derivative film having excellent transparency and heat resistance and being able to cope with an increase in the size of the film. , Polymethylmethacrylate films and triacetylcellulose and isobutylester cellulose films that are transparent and optically homogeneous are preferred. The thickness of the resin film may be 5 μm or more and 200 μm or less, preferably 20 μm or more and 100 μm or less.

[Shading pattern]
The light-shielding pattern (bezel) can be formed on the display element side of the front plate. The shading pattern can hide each wiring of the display device so that it cannot be seen by the user. The color and / or material of the light-shielding pattern is not particularly limited, and can be formed of a resin substance having various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern may be 2 μm or more and 50 μm or less, preferably 4 μm or more and 30 μm or less, and more preferably 6 μm or more and 15 μm or less. Further, in order to suppress the mixing of air bubbles due to the step between the light-shielding pattern and the display unit and the visibility of the boundary portion, the light-shielding pattern can be given a shape.

[Touch panel]
The touch panel is used as an input means. As the touch sensor of the touch panel, various types such as a resistance film method, a surface acoustic wave method, an infrared ray method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Of these, the capacitance method is preferable. It is divided into an active region of the capacitive touch sensor and an inactive region located in the outer portion of the active region. The active area is an area corresponding to the area where the screen is displayed on the display panel (display unit), the area where the user's touch is sensed, and the inactive area is the area where the screen is not displayed on the display device (non-active area). This is the area corresponding to the display unit). The touch panel has a substrate having foldable characteristics; a sensing pattern formed in an active region of the substrate; and a sensing pattern formed in an inactive region of the substrate, and is connected to an external drive circuit via the sensing pattern and a pad portion. Each sensing line for can be included. As the substrate having foldable characteristics, the same material as the transparent substrate of the front plate can be used.

The layer structure of the laminate for the foldable image display device will be described with reference to FIG. In the laminate 60 for a foldable image display device shown in FIG. 8, the foldable polarizing plate 40, the front plate 121 via the adhesive layer 122 on the visible side of the foldable polarizing plate 40, and the foldable polarizing plate 40 are visually recognized. A touch panel 123 is provided on the side opposite to the side via the pressure-sensitive adhesive layer 170. The foldable polarizing plate 40 includes a polarizing element protective layer 100, a cured resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, a bonding layer 104, a retardation layer 160, and an adhesive layer 170. Are prepared in this order. The retardation layer 160 includes a first liquid crystal curing layer 161, a second adhesive layer 162, and a second liquid crystal curing layer 163. At least one of the cured resin layer 101, the first adhesive layer 102, the first liquid crystal cured layer 161, the second adhesive layer 162, and the second liquid crystal cured layer 163 can be a thin film cured layer.

Hereinafter, the present invention will be described in more detail by way of examples. Unless otherwise specified, "%" and "part" in the example are mass% and parts by mass.

[Layer thickness]
The measurement was performed using a contact type film thickness measuring device (“MH-15M” manufactured by Nikon Corporation).

[Bending resistance]
The method for evaluating the bending resistance will be described below with reference to FIG. The prepared foldable polarizing plate was cut into a size of 10 mm on the short side and 100 mm on the long side using a super cutter so that the long side was in the absorption axis direction of the linear polarizing element, and used as a test piece 300. The surface of the test piece 300 (the test piece from which the TAC film was peeled off and removed when the TAC film is arranged on the retardation layer side) is the two

plate jigs

301 and 302 of the bending resistance tester. The short side was fixed so as to be in contact with (FIG. 9a). Kapton film tape (manufactured by Toray DuPont) 303 was used for fixing, and both ends of the test piece were fixed by 10 mm in the long side direction, and the distance L1 between the two

plate jigs

301 and 302 was 53 mm. I fixed it so that it would be. Next, when the bending radius R of the test piece is R = 1.5 mm, the distance L2 between the jigs becomes 2R by moving the two

plate jigs

301 and 302 in the directions indicated by the arrows A1 and A2, respectively. The fixed test piece was continuously changed and bent so that the absorption axis direction of the linear deflector was orthogonal to the bending axis (FIG. 9b). The bending speed was 60 rpm, and the number of times of bending until cracks and cracks were generated in the film was measured.

[Martens hardness]
The Martens hardness was measured using an ultrafine hardness tester (FISCHERSCOPE HM2000: manufactured by Fisher Instruments Co., Ltd.). As shown in FIG. 10, a single film 401 of each layer (the liquid crystal cured layer has no support layer) was adsorbed on the soda glass 402 using static electricity, and the maltens hardness of each layer was measured at a temperature of 23 ° C. .. Using a Vickers indenter 403, the indentation depth in the direction of arrow A3 was 0.2 μm, and the average value of each member n = 3 by indentation measurement according to ISO14577 was obtained as the Martens hardness.

<Example 1>
A triacetyl cellulose (TAC) film and an acrylic resin film are bonded to both sides of a linear modulator (PVA, thickness 8 μm) in which iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film via water, and dried. Both release paper PVA having a layer structure of TAC film / PVA / acrylic resin film was produced. A cyclic olefin resin (thickness 3 μm, maltens hardness 266.843 N / mm ² ) having an ultraviolet absorber-containing hard coat (HC) layer (thickness 3 μm, maltens hardness 266.843 N / mm 2) as a polarizing element protective film by peeling off the acrylic resin film side of both release papers PVA ( The hard coat layer side of the COP) film (thickness 22 μm) was bonded via an adhesive layer (thickness 0.1 μm, Martens hardness 522.611 N / mm ² ) made of an aqueous adhesive, and dried in an oven. The bonded surface was subjected to corona treatment (780 W × 1 pass).

Next, the TAC film of the linear polarizing plate having the layer structure of the obtained COP film / UV absorber-containing HC layer / adhesive layer / PVA / TAC film was peeled off, and the PVA surface was subjected to corona treatment. An adhesive layer (thickness 5 μm) with a separate film was attached thereto.
Liquid crystal of λ / 2 plate (thickness 2 μm, Martens hardness 239.038 N / mm ² ) and λ / 4 plate (thickness 1 μm, Martens hardness 214.012 N / mm ² ) obtained by applying a polymerizable liquid crystal compound to a TAC film and curing it. A retardation layer laminate was prepared in which the surfaces were bonded together with an adhesive layer (thickness 2 μm, Martens hardness 175.665 N / mm ² ) made of an ultraviolet curable adhesive.

After peeling off the separate film of the pressure-sensitive adhesive layer bonded to the linear polarizing plate, peeling off the TAC film on the λ / 2 plate side of the retardation layer laminate, corona treatment is performed only on the liquid crystal surface, and the pressure-sensitive adhesive layer is bonded to the pressure-sensitive adhesive layer. did. Foldable polarizing plate having a layer structure of COP film / UV absorber-containing HC layer / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / TAC film (excluding TAC film) A thickness of 43.1 μm) was obtained. Table 1 shows the evaluation results of bending resistance. In the obtained foldable polarizing plate, a hard coat layer, an adhesive layer made of a water-based adhesive, a λ / 2 plate, an adhesive layer made of an ultraviolet curable adhesive, and a λ / 4 plate are thin film cured layers, and are displayed. The module side is the TAC film side.

<Example 2>
Instead of using the UV absorber-containing hard coat (HC) layer (thickness 3 μm, Martens hardness 266.843 N / mm ² ) in Example 1, the hard coat (HC) layer (without UV absorber, thickness 2 μm, Martens). COP film / HC layer / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate in the same manner as in Example 1 except that the hardness 280.775 N / mm ² ) was used. A foldable polarizing plate having a layer structure of / TAC film (thickness 42.1 μm excluding TAC film) was obtained. The results are shown in Table 1.

<Example 3>
Instead of using the UV absorber-containing hard coat (HC) layer (thickness 3 μm, Martens hardness 266.843 N / mm ² ) in Example 1, the hard coat (HC) layer (no UV absorber, thickness 2 μm, Martens). Except for the fact that a hardness of 280.775 N / mm ² ) was used and that the TAC film was peeled off from the foldable polarizing plate and an adhesive layer (thickness 15 μm) made of an adhesive was attached to the surface on the λ / 4 plate side. A foldable polarizing plate having a layer structure of COP film / HC layer / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / adhesive layer in the same manner as in Example 1 ( A thickness of 57.1 μm including the adhesive layer) was obtained. The results are shown in Table 1.

<Comparative Example 1>
In Example 1, instead of laminating PVA on the UV absorber-containing hard coat (HC) layer side of the polarizing element protective film via an adhesive layer, the adhesive layer is interposed on the COP film side of the polarizing element protective film. HC layer / COP film / adhesive layer / PVA / adhesive layer / λ / 2 board / adhesive layer / λ / 4 board / A foldable polarizing plate having a layer structure of a TAC film was obtained. The results are shown in Table 1.

<Comparative Example 2>
In Example 2, instead of laminating PVA on the hard coat (HC) layer side of the polarizing element protective film via an adhesive layer, PVA is pasted on the COP film side of the polarizing element protective film via an adhesive layer. A folder having a layer structure of HC layer / COP film / adhesive layer / PVA / adhesive layer / λ / 2 board / adhesive layer / λ / 4 board / TAC film in the same manner as in Example 1 except that they are matched. A bull polarizing plate was obtained. The results are shown in Table 1.

<Comparative Example 3>
In Example 3, PVA is attached to the COP film side of the polarizing element protective film via the adhesive layer instead of attaching PVA to the hard coat (HC) layer side of the polarizing element protective film via the adhesive layer. A folder having a layer structure of HC layer / COP film / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / adhesive layer in the same manner as in Example 1 except that they are matched. A bull polarizing plate was obtained. The results are shown in Table 1.

1,5,10,20,30,40,50 Foldable polarizing plate, 2 Window unit, 3,122 Adhesive layer, 4 Display module, 100,200 Polarizer protection layer, 101,201 Cured resin layer, 102, 202 1st adhesive layer, 6,103,203 linearly polarized light layer, 104,204 laminated layer, 7,105,160,205 retardation layer, 121 front plate, 123 touch panel, 161 first liquid crystal curing layer, 162nd 2 Adhesive layer, 163 second liquid crystal curing layer, 170 adhesive layer, 180 protective film, 300 test piece, 301, 302 plate jig, 303 Capton film tape, 401 single film, 402 soda glass, 403 Vickers indenter, L1, Distance between L2 jigs, T1, T2 range

Claims

A foldable polarizing plate arranged between a pressure-sensitive adhesive layer laminated adjacent to a window unit and a display module.
Includes a thin film cured layer with a thickness of 5 μm or less
The thin film cured layer exists only in the range of 0% or more and 90% or less in the thickness direction from the outermost surface of the foldable polarizing plate on the display module side when the thickness of the foldable polarizing plate is 100%. , Foldable polarizing plate.
The foldable polarizing plate according to claim 1, wherein the Martens hardness of the thin film cured layer at 23 ° C. is 150 N / mm 2 or more and 800 N / mm 2 or less.
The foldable polarizing plate according to claim 1 or 2, wherein the thickness is 20 μm or more and 150 μm or less.
An image display device provided with the foldable polarizing plate according to any one of claims 1 to 3.
A foldable polarizing plate in which a linear polarizing layer and a retardation layer are laminated.
Includes a thin film cured layer with a thickness of 5 μm or less
When the thickness of the foldable polarizing plate is 100%, the thin film cured layer is 0% or more in the thickness direction from the outermost surface on the retardation layer side with respect to the linear polarizing layer of the foldable polarizing plate. Foldable polarizing plate that exists only in the range within%.