Foldable polarizing plate

Abstract

This invention provides a foldable polarizing plate disposed between an adhesive layer and a display module stacked adjacent to a window unit, and comprising a thin-film curing layer with a thickness of 5 μm or less. Even when repeatedly bent with the display module side as the bending center, it is not prone to cracking or breakage. The foldable polarizing plate, disposed between an adhesive layer and a display module stacked adjacent to a window unit, comprises a thin-film curing layer with a thickness of 5 μm or less. When the thickness of the foldable polarizing plate is set to 100%, the thin-film curing layer exists only in a range of 0% to 90% in the thickness direction from the outermost surface of the foldable polarizing plate on the display module side.

Description

Technical Field

[0001] This invention relates to a foldable polarizing plate, and also to an image display device having the same. Background Technology

[0002] As seen in the market in recent years, foldable smart devices have emerged, sometimes requiring the display (image display device) used to be flexible. If the display is bent, bending stress and strain are applied to the components constituting the display. Therefore, the components constituting the display used in foldable devices require material design specifically for them. In Patent Document 1, a flexible circular polarizer equipped with a polarizer and a retardation film is proposed as a component for a flexible display device.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-170221 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] When designing polarizing plates specifically for foldable devices, the main challenge lies in the cracking and breakage that occurs during bending. Designs using rigid polarizing plates for displays are often difficult to apply to foldable devices. Polarizing plates are laminated films composed of multiple functional layers, and the thin, rigid layers are particularly prone to breakage when bent. If such a layer breaks, light may leak from the crack, or if the touch panel or light-emitting layer breaks, the display may fail.

[0008] The purpose of this invention is to provide a foldable polarizing plate disposed between an adhesive layer and a display module that are stacked adjacent to a window unit, and includes a thin film curing layer with a thickness of less than 5 μm. This foldable polarizing plate is not prone to cracking or breakage even when repeatedly bent with the display module side as the bending center.

[0009] Another objective of the present invention is to provide a foldable polarizing plate having a linear polarizing layer and a phase difference layer stacked thereon, and including a thin film curing layer with a thickness of less than 5 μm. The foldable polarizing plate is not prone to cracking or breaking even when repeatedly bent with the linear polarizing layer as the reference and the phase difference layer side as the bending center.

[0010] Methods for solving problems

[0011] The present invention provides the following foldable polarizing plate and image display device.

[0012] [1] A foldable polarizing plate disposed between an adhesive layer and a display module that are stacked adjacent to a window unit.

[0013] The foldable polarizing plate includes a thin film curing layer with a thickness of less than 5 μm.

[0014] When the thickness of the foldable polarizing plate is set to 100%, the thin film curing layer exists only in the range of 0% to 90% in the thickness direction from the outermost surface of the foldable polarizing plate on the display module side.

[0015] [2] According to the foldable polarizing plate described in [1], the martensitic hardness of the above-mentioned thin film curing layer at 23°C is 150 N / mm. 2 Above and 800 N / mm 2 the following.

[0016] [3] The foldable polarizing plate described in [1] or [2] has a thickness of more than 20 μm and less than 150 μm.

[0017] [4] An image display device comprising a foldable polarizing plate described in any one of [1] to [3].

[0018] [5] A foldable polarizing plate, which is a foldable polarizing plate having a linear polarizing layer and a phase difference layer stacked on top of each other.

[0019] The foldable polarizing plate includes a thin film curing layer with a thickness of less than 5 μm.

[0020] When the thickness of the foldable polarizing plate is set to 100%, the thin film curing layer exists only in the range of 0% to 90% in the thickness direction, starting from the outermost surface of the phase difference layer side, with the linear polarization layer of the foldable polarizing plate as a reference.

[0021] Invention Effects

[0022] According to one aspect of the present invention, a foldable polarizing plate can be provided, which is disposed between an adhesive layer and a display module stacked adjacent to a window unit and includes a thin film curing layer with a thickness of less than 5 μm. The foldable polarizing plate is not prone to cracking or breaking even when repeatedly bent with the display module side as the bending center.

[0023] According to another aspect of the present invention, a foldable polarizing plate can be provided, which has a linear polarizing layer and a phase difference layer stacked together, and includes a thin film curing layer with a thickness of less than 5 μm. The foldable polarizing plate is not prone to cracking or breaking even when repeatedly bent with the linear polarizing layer as the reference and the phase difference layer side as the bending center. Attached Figure Description

[0024] Figure 1 This is a schematic cross-sectional view showing an example of a configuration with a foldable polarizing plate.

[0025] Figure 2 This is a schematic cross-sectional view illustrating an example of the layered structure of a foldable polarizing plate of the first type.

[0026] Figure 3 This is a schematic cross-sectional view showing another example of the layered structure of the first type of foldable polarizing plate.

[0027] Figure 4 This is a schematic cross-sectional view showing another example of the layered structure of the first type of foldable polarizing plate.

[0028] Figure 5 This is a schematic cross-sectional view showing another example of the layered structure of the first type of foldable polarizing plate.

[0029] Figure 6 This is a schematic cross-sectional view illustrating an example of the layered structure of a second-mode foldable polarizing plate.

[0030] Figure 7 This is a schematic cross-sectional view showing another example of the layered structure of the second type of foldable polarizing plate.

[0031] Figure 8 This is a schematic cross-sectional view illustrating an example of a foldable image display device constructed from layers of a laminate.

[0032] Figure 9 This is a schematic diagram used to illustrate the evaluation method for bending resistance.

[0033] Figure 10 This is a schematic diagram illustrating the method for determining martensitic hardness. Detailed Implementation

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. In all the following drawings, the scale has been appropriately adjusted for easy understanding of the constituent elements, and the scale of each constituent element shown in the drawings may not be consistent with the actual scale of the constituent elements.

[0035] <Foldable Polarizing Plate>

[0036] [First Method]

[0037] In the first embodiment, a foldable polarizing plate is disposed between an adhesive layer and a display module stacked adjacent to the window unit, and has a thin film curing layer with a thickness of 5 μm or less. When the thickness of the foldable polarizing plate is set to 100%, the thin film curing layer exists only in a range of 0% to 90% in the thickness direction from the outermost surface of the foldable polarizing plate on the display module side.

[0038] Figure 1 The foldable polarizing plate 1 shown is disposed between the adhesive layer 3, which is stacked adjacent to the window unit 2, and the display module 4. Preferably, one side of the foldable polarizing plate 1 is configured to directly contact the adhesive layer 3 stacked adjacent to the window unit 2, and the other side is configured to directly contact the display module 4. The window unit 2 may be, for example, a front panel. The display module 4 may be, for example, a touch sensor panel, an image display element, etc. The adhesive layer 3 is used as an example of a bonding layer described later.

[0039] In this specification, "foldable" means that the foldable polarizer can be bent along the bending axis when the transmission axis direction of the linear polarizing layer in the foldable polarizer is taken as the bending axis. The foldable polarizer 1 can be bent with the display module side as the inside. Bending includes a bending shape in which a curved surface is formed in the bending portion. In the bending shape, the bending radius of the inner surface of the bend is not particularly limited. In addition, bending includes a bending shape in which the bending angle of the inner surface is greater than 0° and less than 180°, and a folding shape in which the bending radius of the inner surface is approximately zero or the bending angle of the inner surface is 0°.

[0040] In this specification, crack refers to the crazing observed in the thin-film cured layer when a foldable polarizing plate is observed under transmitted light using an optical microscope from a top view. In this specification, fracture refers to the continuous formation of crazing in layers outside the thin-film cured layer due to cracks in the thin-film cured layer. Fractures and cracks can be observed using the methods described in the embodiments section below.

[0041] When the foldable polarizing plate 1 is repeatedly bent along the bending axis with the display module side surface as the inner side and the bending radius of the inner surface being 1.5 mm, it preferably does not produce cracks even after 50,000 bending cycles, and more preferably does not produce cracks even after 80,000 bending cycles.

[0042] The foldable polarizing plate can be in the form of a strip or a sheet. A sheet-like shape is preferred. A sheet-like foldable polarizing plate can be obtained by cutting from a strip-like foldable polarizing plate. When the foldable polarizing plate is sheet-like, its top-view shape can be, for example, square, preferably a square shape with a long side and a short side, and more preferably rectangular. When the top-view shape of the foldable polarizing plate is rectangular, the length of the long side can 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 can be, 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. It should be noted that, in this specification, "top view" refers to viewing from the thickness direction of the layer.

[0043] When the top view of the foldable polarizing plate is square, the lengths of the sides of each layer constituting the foldable polarizing plate can be the same. The layers constituting the foldable polarizing plate can be rounded at the corners, notched at the ends, or have holes made.

[0044] The thickness of the foldable polarizing plate can 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 it is disposed between the adhesive layer and the display module, which are stacked adjacent to the window unit. The foldable polarizing plate has an adhesive layer (described later) on its outermost surface on the display module side for bonding with the display module. When the foldable polarizing plate has an adhesive layer when disposed between the adhesive layer and the display module, the thickness of the foldable polarizing plate includes the thickness of the adhesive layer. Even if the foldable polarizing plate has a diaphragm or protective film before being disposed between the adhesive layer and the display module, the thickness of the foldable polarizing plate does not include the thickness of the diaphragm or protective film when it is disposed between the adhesive layer and the display module.

[0045] The foldable polarizer can be used in image display devices. The image display device can be any device such as a liquid crystal display device or an organic EL display device. The foldable polarizer can be disposed on the front side (viewing side) or the back side of the image display device. The foldable polarizer of this invention is flexible, therefore suitable for foldable image display devices.

[0046] When the image display device is a liquid crystal display device, the foldable polarizer can be configured as a polarizer that includes a polarizer disposed on the front side of the liquid crystal cell or the back side.

[0047] When the image display device is an organic EL display device, the foldable polarizer can be arranged on the front side in the form of a circular polarizer arranged on the front side to prevent reflection of external light.

[0048] When the foldable polarizer is a circular polarizer, it can possess anti-reflective properties. In image display devices, by providing a foldable polarizer with anti-reflective properties on the front side of the image display device, it is possible to suppress the reduction in visibility caused by the reflection of external light.

[0049] [Film Curing Layer]

[0050] Although not shown, the foldable polarizer 1 includes a thin-film cured layer with a thickness of 5 μm or less. The thin-film cured layer can be a cured layer containing a curable resin. Examples of thin-film cured layers include, for instance, a cured resin layer formed on a polarizer protective layer (which is a thermoplastic resin film), a coating protective layer, an adhesive layer for bonding the linear polarization layer to the polarizer protective layer, a liquid crystal cured layer contained in a retardation layer, and an adhesive layer for bonding the retardation layers to each other, all with a thickness of 5 μm or less. When the thickness of the thin-film cured layer exceeds 5 μm, there is a tendency for the thin-film cured layer to crack or break. Layers other than the thin-film cured layer will be described later.

[0051] 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 typically 0.5 μm or more.

[0052] When the thickness of the foldable polarizing plate 1 is set to 100%, the thin film curing layer exists only within a range T1, which is more than 0% and less than 90% in the thickness direction, starting from the outermost surface of the foldable polarizing plate 1 on the display module 4 side. Because the thin film curing 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 inner side, it is less likely to crack or break.

[0053] When the thickness of the foldable polarizing plate 1 is set to 100%, the thin film curing layer exists only in the range of 0% or more and 90% or less in the thickness direction from the outermost surface of the display module 4 side of the foldable polarizing plate 1, more preferably only in the range of 0% or more and 75% or less, and even more preferably only in the range of 0% or more and 60% or less.

[0054] The martensitic hardness (hereinafter referred to as martensitic hardness for simplicity) of the cured film layer at 23°C can be, for example, 150 N / mm. 2 Above and 800 N / mm 2The following applies. When the martensitic hardness of the cured film layer is within the above-mentioned range, there is a tendency for cracks to form. The martensitic hardness can be measured according to the method described in the examples section below.

[0055] From the perspective of minimizing crack formation, the preferred Martens hardness of the cured film layer is 150 N / mm². 2 Above and 700 N / mm 2 Below, 150 N / mm is preferred. 2 Above and 600N / mm 2 the following.

[0056] The martensitic hardness of the cured film layer can be adjusted, for example, by adjusting the composition of the composition used to form the cured film layer. Examples of methods for adjusting the composition of the composition include adjusting the type and / or content of the polymerizable monomers constituting the curable resin, and the additives. Alternatively, a substance with a specified martensitic hardness can be selected from commercially available products.

[0057] A foldable polarizer can function as a linear polarizer containing a polarizer protective layer and a linear polarization layer, or it can function as a circular polarizer containing a linear polarizer and a phase difference layer. Figure 2 The foldable polarizer 10 shown sequentially comprises a polarizer protective layer 100, a cured resin layer 101, an adhesive layer 102, a linear polarizing layer 103, an adhesive layer 104, and a phase retardation layer 105 including a liquid crystal curing layer (not shown). The foldable polarizer 10 may further include other layers besides those described above. Examples of other layers include a protective film and an adhesive layer.

[0058] [Polarizer Protective Layer]

[0059] The polarizer protective layer 100 is a layer used to protect the surface of the linear polarization layer 103, particularly the linear polarization layer 103. The polarizer protective layer 100 can be disposed on one or both sides of the linear polarization layer 103 by means of an adhesive layer alone or directly. In this specification, the linear polarization layer 103 with the polarizer protective layer 100 disposed thereon is sometimes referred to as a linear polarizer plate.

[0060] The polarizer protective layer 100 can be formed, for example, from a thermoplastic resin film or a coated protective layer. The foldable polarizer 10 may have the polarizer protective layer 100 on only one side of the linear polarizing layer 103, or it may have the polarizer protective layer 100 on both sides. When the foldable polarizer 10 has polarizer protective layers on both sides of the linear polarizing layer 103, the polarizer protective layers 100 may be of the same type or different types. When the polarizer protective layer 100 is a thermoplastic resin film, it can be adhered to the linear polarizing layer 103 using an adhesive layer described later. Alternatively, when the polarizer protective layer 100 is a thermoplastic resin film, it may include a cured resin layer 101 described later. The foldable polarizer 10 preferably includes a thermoplastic resin film.

[0061] [Thermoplastic resin film]

[0062] The thermoplastic resin film that can be used as a polarizer protective layer 100 can be assembled on the foldable polarizer 10 in the form of being attached to one or both sides of the linear polarizer layer 103. As a thermoplastic resin film, for example, it can be a thermoplastic resin film that is light-transmitting, preferably optically transparent. Examples include chain polyolefin resins (polyethylene resins, polypropylene resins, polymethylpentene resins, etc.), cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; ethylene-vinyl acetate resins; polystyrene resins; polyamide resins; polyetherimide resins; (meth)acrylic resins such as poly(meth)acrylate resins; polyimide resins; polyethersulfone resins; polysulfone resins; polyvinyl chloride resins; polyvinylidene chloride resins; polyvinyl alcohol resins; polyvinyl alcohol acetal resins; polyetherketone resins; polyetheretherketone resins; polyethersulfone resins; and polyamide-imide resins. Thermoplastic resins can be used alone or in combination of two or more. Among them, from the viewpoint of strength and light transmittance, triacetyl cellulose resin films, cyclic polyolefin resin films, and (meth)acrylic resin films are preferred.

[0063] The thickness of the thermoplastic resin film can be, for example, 30 μm or less, and from the viewpoint of thinning, preferably 25 μm or less. It is also typically 1 μm or more, preferably 5 μm or more, and even more preferably 15 μm or more. The thermoplastic resin film may or may not have a phase difference.

[0064] [Cure the resin layer]

[0065] The cured resin layer 101 is a layer containing a cured resin. The cured resin layer 101 may be, for example, a layer with functions such as a hard coating, an anti-glare layer, an anti-reflective layer, a light diffusion layer, an antistatic layer, an anti-fouling layer, or a conductive layer.

[0066] Examples of curable resins include thermosetting resins and active energy radiation-curable resins. The cured product of the curable resin can be formed from a curable resin layer-forming composition containing the curable resin. Examples of curable resin layer-forming compositions include thermosetting compositions, cationic curable compositions, and free radical curable compositions. Examples of curable resin layer-forming compositions include polymerizable monomers, polymerization initiators, additives, and solvents. Examples of additives include plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, and surfactants.

[0067] When the cured resin layer 101 is a hard coating, the hardness and scratch resistance of the linear polarizing layer 103 or the polarizer protective layer 100 can be easily improved. When the thermoplastic resin film has a cured resin layer 101 as a hard coating, for example, a hard coating forming composition can be applied to the thermoplastic resin film forming the polarizer protective layer 100 and cured to form a cured product of the hard coating forming composition, thereby producing a thermoplastic resin film with a hard coating, which is then bonded to the linear polarizing layer 103 using an adhesive layer 102. Alternatively, a commercially available thermoplastic resin film with a cured resin layer can be used as the polarizer protective layer 100.

[0068] The hard coating can be formed from a cured composition comprising an active energy radiation-curable resin. Examples of active energy radiation-curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. To improve strength, the hard coating may contain additives. Additives are not limited and may include inorganic microparticles, organic microparticles, or mixtures thereof. The hard coating preferably contains an ultraviolet absorber.

[0069] The thickness of the cured resin layer 101 can be, for example, 5 μm or less, preferably 4 μm or less. The thickness of the thin film cured layer 100 is typically 0.5 μm or more.

[0070] [Adhesive layer]

[0071] The adhesive layer 102 used for bonding the linear polarizing layer 103 to the polarizer protective layer 100 (or cured resin layer 101) of the thermoplastic resin film can be formed from an active energy radiation-curing adhesive such as an ultraviolet-curable adhesive, an aqueous solution of a polyvinyl alcohol-based resin or an aqueous solution containing a crosslinking agent, or an urethane emulsion adhesive, etc. When the thermoplastic resin film is bonded to both sides of the linear polarizing layer 103, the adhesives forming the two adhesive layers can be of the same type or different types. For example, when the thermoplastic resin film is bonded to both sides, an aqueous adhesive can be used on one side and an active energy radiation-curable adhesive can be used on the other side. The ultraviolet-curable adhesive can be a mixture of a free radical polymerizable (meth)acrylic acid compound and a photofree radical polymerization initiator, a mixture of a cationic polymerizable epoxy compound and a photocationic polymerization initiator, etc. Alternatively, cationic polymerizable epoxy compounds and radical polymerizable (meth)acrylic acid compounds can be used in combination, along with photocationic polymerization initiators and photoradical polymerization initiators. The thickness of the adhesive layer can be, for example, 0.1 μm or more and 5 μm or less.

[0072] When using active energy radiation-curing adhesives, the adhesive is cured by irradiating it with active energy radiation after bonding. The source of the active energy radiation is not particularly limited, but active energy radiation (ultraviolet light) with a luminescence distribution at wavelengths below 400 nm is preferred. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps are preferred.

[0073] To improve the adhesion between the linear polarizing layer 103 and the polarizing protective layer 100 (or the cured resin layer 101) which is a thermoplastic resin film, one or both of the bonding surfaces can be subjected to surface treatments such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, primer coating treatment, saponification treatment, etc.

[0074] [Coat a protective layer]

[0075] The protective coating can be formed by coating and curing a cationic curable composition such as epoxy resin or a free radical curable composition such as (meth)acrylate, or by coating and drying an aqueous solution such as polyvinyl alcohol resin. It can contain plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, etc., as needed.

[0076] When the polarizer protective layer 100 is a coated protective layer, the thickness of the polarizer protective layer 100 can be, for example, 0.1 μm or more and 30 μm or less. From the viewpoint of thinning, it is preferable to be 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less.

[0077] [Linear polarization layer]

[0078] The linear polarizing layer 103 can be a linear polarizer that absorbs linearly polarized light with a vibrational plane parallel to its absorption axis and transmits linearly polarized light with a vibrational plane orthogonal to the absorption axis (parallel to the transmission axis). Examples of linear polarizing layers include stretched films or stretched layers adsorbed with dichroic dyes. Specifically, iodine and dichroic organic dyes can be used as dichroic direct dyes, including dichroic direct dyes containing diazo compounds such as CIDIRECT RED 39, and dichroic direct dyes containing compounds such as triazo and tetraazo.

[0079] The linear polarizing layer of a stretched film (hereinafter sometimes abbreviated as "stretched film") adsorbed with a dichroic pigment will be described. The stretched film adsorbed with a dichroic pigment can generally be manufactured by the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing the dichroic pigment by dyeing the polyvinyl alcohol-based resin film with a dichroic pigment; a step of treating the polyvinyl alcohol-based resin film adsorbed with the dichroic pigment with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution. The thickness of the linear polarizing layer of the stretched film adsorbed with the dichroic pigment can, for example, be 2 μm or more and 40 μm or less.

[0080] Polyvinyl alcohol (PVA) resins are obtained by saponifying polyvinyl acetate (PVC) resins. Besides PVC as a homopolymer of PVC, copolymers of PVC and other monomers capable of copolymerizing with PVC can also be used as PVC resins. Examples of other monomers capable of copolymerizing with PVC include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides with ammonium groups.

[0081] The degree of saponification of polyvinyl alcohol (PVA) resins is typically 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. PVA resins can be modified; for example, aldehyde-modified PVA formal or PVA acetal can also be used. The degree of polymerization of PVA resins is typically 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.

[0082] The film made from such polyvinyl alcohol (PVA) resin is used as the raw material for stretch films. There are no particular limitations on the method for making the PVA resin film; known methods can be used. The film thickness of the PVA raw material film can be, for example, 10 μm or more and 150 μm or less.

[0083] Uniaxial stretching of polyvinyl alcohol (PVA) resin films can be performed before, during, or after dyeing with dichroic pigments. When uniaxial stretching is performed after dyeing, it can be done before or during boric acid treatment. Alternatively, uniaxial stretching can be performed at multiple stages. During uniaxial stretching, it can be performed between rollers with different circumferential speeds, or it can be performed using hot rollers. Furthermore, uniaxial stretching can be dry stretching performed in the atmosphere, or wet stretching performed while the PVA resin film is swollen using a solvent. The stretching ratio is typically between 3 and 8 times.

[0084] The dyeing of polyvinyl alcohol (PVA) resin membranes using dichroic dyes is performed, for example, by immersing the PVA resin membrane in an aqueous solution containing a dichroic dye. Specifically, iodine and dichroic organic dyes can be used as dichroic dyes. These include dichroic direct dyes containing diazo compounds, such as cIDIRECT RED 39, and dichroic direct dyes containing compounds such as triazo and tetraazo. The PVA resin membrane is preferably pre-treated by immersion in water before dyeing.

[0085] When using iodine as a dichroic dye, the dyeing method typically involves impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide. The iodine content in this aqueous solution is typically 0.01 parts by weight or more and 1 part by weight or less per 100 parts by weight of water. The potassium iodide content is typically 0.5 parts by weight or more and 20 parts by weight or less per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is typically 20°C or higher and 40°C or lower. Furthermore, the immersion time (dyeing time) in this aqueous solution is typically 20 seconds or more and 1800 seconds or less.

[0086] On the other hand, when using dichroic organic dyes as dichroic pigments, the dyeing method is usually adopted by impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing water-soluble dichroic dyes.

[0087] The content of dichroic organic dyes in this aqueous solution is typically 1 × 10⁻¹⁰ per 100 parts by mass of water. -4 More than 10 parts by weight, preferably 1×10 -3 More than 1 part by weight and less than 1 part by weight, more preferably 1×10-3 More than 1×10 -2 The concentration is less than a certain percentage by weight. This aqueous solution may contain inorganic salts such as sodium sulfate as dyeing auxiliaries. The temperature of the dichroic dye aqueous solution used in dyeing is typically above 20°C and below 80°C. Furthermore, the immersion time (dyeing time) in this aqueous solution is typically above 10 seconds and below 1800 seconds.

[0088] Boric acid treatment following dyeing with a dichroic pigment is typically carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The boric acid content in this aqueous solution is typically 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, relative to 100 parts by mass of water. When iodine is used as the dichroic pigment, the aqueous boric acid solution preferably contains potassium iodide, and the potassium iodide content is typically 0.1 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, relative to 100 parts by mass of water. The immersion time in the aqueous boric acid solution is typically 60 seconds or more and 1200 seconds or less, preferably 150 seconds or more and 600 seconds or less, more preferably 200 seconds or more and 400 seconds or less. The temperature for boric acid treatment is typically 50°C or higher, preferably 50°C or higher and 85°C or less, more preferably 60°C or higher and 80°C or less.

[0089] Boric acid-treated polyvinyl alcohol (PVA) resin membranes are typically subjected to a water washing process. This washing can be performed, for example, by immersing the boric acid-treated PVA resin membrane in water. The water temperature during the washing process is typically above 5°C and below 40°C. Furthermore, the immersion time is typically above 1 second and below 120 seconds.

[0090] After washing, a drying process is performed to obtain a stretch film with adsorbed dichroic pigments. The drying process can be performed using, for example, a hot air dryer or a far-infrared heater. The drying temperature is typically 30°C or higher and 100°C or lower, preferably 50°C or higher and 80°C or lower. The drying time is typically 60 seconds or higher and 600 seconds or lower, preferably 120 seconds or higher and 600 seconds or lower. Through the drying process, the moisture content of the stretch film with adsorbed dichroic pigments is reduced to a practical level. Its moisture content is typically 5% by mass or higher and 20% by mass or lower, preferably 8% by mass or higher and 15% by mass or lower. If the moisture content is lower than 5% by mass, the stretch film with adsorbed dichroic pigments may sometimes lose its flexibility, and may be damaged or break after drying. Furthermore, if the moisture content exceeds 20% by mass, the thermal stability of the stretch film with adsorbed dichroic pigments may deteriorate.

[0091] Next, the linear polarizing layer, which is a stretched layer adsorbed with dichroic pigments (hereinafter sometimes abbreviated as "stretched layer"), will be described. The stretched layer adsorbed with dichroic pigments can generally be manufactured by the following steps: a step of coating a coating solution containing the above-mentioned polyvinyl alcohol resin onto a substrate to obtain a laminated film; a step of uniaxially stretching the obtained laminated film; a step of dyeing the polyvinyl alcohol resin layer of the uniaxially stretched laminated film with dichroic pigments and adsorbing them; a step of treating the film adsorbed with dichroic pigments with an aqueous boric acid solution; and a step of washing with water after treatment with the aqueous boric acid solution.

[0092] As an example of a substrate, the substrate illustrated in the description of the polarizer protective layer described later is used.

[0093] The substrate can be peeled off from the stretching layer, or it can be used as a protective layer for the polarizer. The thickness of the substrate can be, for example, 5 μm or more and 200 μm or less. When the substrate is assembled into the foldable polarizer 10, the thickness of the substrate film is preferably 30 μm or less.

[0094] [Adhesive Layer]

[0095] The bonding layer 104 used to bond the linear polarization layer 103 to the phase difference layer 105 can typically be an adhesive layer formed by a pressure-sensitive adhesive (hereinafter also referred to as an adhesive).

[0096] The thickness of the adhesive layer can be, for example, in the range of 1 μm to 50 μm, preferably 2 μm to 45 μm, more preferably 3 μm to 30 μm, and even more preferably 5 μm to 20 μm.

[0097] The adhesive layer can be composed of an adhesive composition with resins such as (meth)acrylic, rubber, urethane, ester, silicone, and polyvinyl ether as the main components. From the viewpoints of transparency, weather resistance, heat resistance, and storage modulus, an adhesive composition with (meth)acrylic resin as the base polymer is preferred. The adhesive composition can be either an active energy radiation-cured or thermosetting type.

[0098] The (meth)acrylic resin (base polymer) used in the adhesive composition may, for example, be a polymer or copolymer with one or more (meth)acrylic esters such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate as monomers. It is preferable to copolymerize the polar monomer with the base polymer. Examples of polar monomers include, for example, (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate, which have carboxyl, hydroxyl, amide, amino, or epoxy groups.

[0099] The adhesive composition may contain only the aforementioned base polymer, but typically also contains a crosslinking agent. Examples of crosslinking agents include crosslinking agents that are divalent or higher metal ions forming a metal carboxylate salt between themselves and a carboxyl group; crosslinking agents that are polyamine compounds forming an amide bond between themselves and a carboxyl group; crosslinking agents that are polyepoxide compounds or polyols forming an ester bond between themselves and a carboxyl group; and crosslinking agents that are polyisocyanate compounds forming an amide bond between themselves and a carboxyl group. Among these, polyisocyanate compounds are preferred.

[0100] The adhesive layer can be formed, for example, by dissolving or dispersing the adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, and then directly applying it to the object surface of the foldable polarizing plate to form an adhesive layer; or by forming the adhesive layer into a sheet on a diaphragm that has undergone a demolding treatment and then moving it to attach it to the object surface of the linear polarizing layer 103 or the phase difference layer 105.

[0101] The membrane can be a membrane containing polyethylene resins such as polyethylene, polypropylene resins such as polypropylene, polyester resins such as polyethylene terephthalate, etc. Among them, a stretch membrane of polyethylene terephthalate is preferred.

[0102] The adhesive layer can contain any components, such as glass fiber, glass beads, resin beads, fillers containing metal powder or other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, etc.

[0103] Examples of antistatic agents include ionic compounds, conductive microparticles, and conductive polymers, with ionic compounds being preferred.

[0104] The cationic components that make up ionic compounds can be either inorganic or organic cations.

[0105] Examples of organic cations include pyridinium cations, imidazolium cations, ammonium cations, sulfonium cations, phosphonium cations, piperidinium cations, and pyrrolidineium cations. Examples of inorganic cations include lithium ions and potassium ions.

[0106] On the other hand, the anionic component constituting the ionic compound can be an inorganic anion or an organic anion. From the perspective of providing an ionic compound with excellent antistatic properties, anionic components containing fluorine atoms are preferred. Examples of anionic components containing fluorine atoms include hexafluorophosphate anion [(PF6]]. - )], Bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N - [Anion, bis(fluorosulfonyl)imide anion [(FSO2)2N] - Anions, etc.

[0107] [Phase difference layer]

[0108] The phase retardation layer 105 can be disposed on the bending axis side when the foldable polarizer 10 is bent toward the display module side. The phase retardation layer 105 can be laminated onto the linear polarizer 103 by means of the bonding layer 104. The phase retardation layer 105 can be a positive A layer and a positive C layer, such as a λ / 4 layer and a λ / 2 layer. The phase retardation layer 103 can be formed from a liquid crystal curing layer, or it can be formed from a resin film exemplified as a thermoplastic resin film material described above. When the phase retardation layer 103 includes a liquid crystal curing layer, the phase retardation layer 103 can further include an adhesive layer, an alignment layer, and a substrate, which will be described later.

[0109] The phase 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 phase retardation layer 105 includes a λ / 2 layer, the λ / 2 layer and the λ / 4 layer can be stacked sequentially from the linear polarization layer 103 side. When the phase retardation layer 105 includes a positive C layer, the λ / 4 layer and the positive C layer can be stacked sequentially from the linear polarization layer 103 side, or the positive C layer and the λ / 4 layer can be stacked sequentially from the linear polarization layer 103 side.

[0110] The thickness of the phase retardation layer 105 can 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.

[0111] A liquid crystal curing layer is a cured layer formed by the polymerization of polymeric liquid crystal compounds. The liquid crystal curing layer can be formed by the polymerization of polymeric liquid crystal compounds in a liquid crystal orientation state. The polymeric liquid crystal compounds can be oriented in-plane or perpendicularly. When the polymeric liquid crystal compounds are oriented in-plane, the liquid crystal curing layer becomes a positive A layer that displays in-plane phase difference. When the polymeric liquid crystal compounds are oriented perpendicularly, it becomes a positive C layer that displays phase difference in the thickness direction.

[0112] Polymerizable liquid crystal compounds are compounds containing polymerizable groups and are compounds that can be in a liquid crystal state. The polymerizable liquid crystal compound is polymerized by the reaction of its polymerizable groups with each other, thereby solidifying the polymerizable liquid crystal compound.

[0113] The phase retardation layer 105 may include one, two, or three or more liquid crystal curing layers. When the phase retardation layer 105 includes two or more liquid crystal curing layers, these layers are typically stacked together using an adhesive layer. In addition to the liquid crystal curing layers and the adhesive layers that stack them, the phase retardation layer 105 may also include an alignment layer for orienting the polymerizable liquid crystal compound during the formation of the substrate and / or the liquid crystal curing layers. When the phase retardation layer 105 has a substrate, the substrate is typically removed when the phase retardation layer 105 is attached to the linear polarization layer 103.

[0114] Examples of adhesives used in the adhesive layer include UV-curable adhesives, aqueous solutions of polyvinyl alcohol resins or aqueous solutions containing crosslinking agents, and water-based adhesives such as urethane emulsion adhesives. When the phase retardation layer comprises two or more adhesive layers, the adhesives can be of the same type or different types. The thickness of the adhesive layer can be, for example, 0.1 μm or more and 5 μm or less.

[0115] There is no particular limitation on the type of polymerizable liquid crystal compound, but it can be classified into rod-shaped (rod-shaped liquid crystal compound) and disc-shaped (disc-shaped liquid crystal compound, disc-shaped liquid crystal compound) according to its shape. Furthermore, each type has low-molecular-weight and high-molecular-weight forms. It should be noted that "high-molecular-weight" generally refers to a polymer with a degree of polymerization of 100 or more (Polymer Physics, Phase Transfer Kinetics, Masao Doi, p. 2, Iwanami Shoten, 1992). In this invention, any polymerizable liquid crystal compound can be used. Furthermore, two or more rod-shaped liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or mixtures of rod-shaped and disc-shaped liquid crystal compounds can be used. For example, the rod-shaped liquid crystal compound described in claim 1 of Japanese Patent Application Publication No. 11-513019 can be suitably used as a rod-shaped liquid crystal compound. As a disc-shaped liquid crystal compound, for example, the disc-shaped liquid crystal compound described in paragraphs

[0020] to

[0067] of Japanese Patent Application Publication No. 2007-108732 or paragraphs

[0013] to

[0108] of Japanese Patent Application Publication No. 2010-244038 may be used.

[0116] Two or more polymerizable liquid crystal compounds can be used in combination. In this case, at least one of them has two or more polymerizable groups within its molecule. That is, the layer formed by curing the above-mentioned polymerizable liquid crystal compounds is preferably a layer formed by fixing liquid crystal compounds having polymerizable groups through polymerization. In this case, it is no longer necessary to exhibit liquid crystal properties after the layer is formed.

[0117] Polymerizable liquid crystal compounds have polymerizable groups capable of undergoing polymerization reactions. Preferred polymerizable groups include, for example, polymerizable olefinic unsaturated groups, cyclic polymerizable groups, and other functional groups capable of addition polymerization reactions. More specifically, examples of polymerizable groups include (meth)acryloyl, vinyl, styrene, and allyl. Among these, (meth)acryloyl is preferred. It should be noted that (meth)acryloyl is a concept encompassing both methacryloyl and acryloyl groups.

[0118] Polymerizable liquid crystal compounds can be thermotropic or lyotropic. If thermotropic liquid crystals are classified according to their degree of order, they can be nematic or smectic liquid crystals.

[0119] A liquid crystal cured layer can be formed by coating an alignment layer with a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as a phase retardation layer forming composition), for example, and irradiating it with active energy rays. The phase retardation layer forming composition may contain components other than the aforementioned polymerizable liquid crystal compound. For example, a polymerization initiator is preferably included in the phase retardation layer forming composition. The polymerization initiator used is selected according to the form of the polymerization reaction, for example, a thermal polymerization initiator or a photopolymerization initiator. Examples of photopolymerization initiators include α-carbonyl compounds, azobin ethers, α-hydrocarbon-substituted aromatic azobin compounds, polynuclear quinone compounds, combinations of triarylimidazolium dimers and p-aminophenyl ketones, etc. The amount of polymerization initiator used relative to the total solid content in the coating liquid is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less. It should be noted that cured material refers to a state in which the formed layer can stand independently without deforming or flowing.

[0120] Furthermore, from the viewpoint of uniformity and strength of the coated film, the composition for forming the phase retardation layer may contain a polymerizable monomer. Examples of polymerizable monomers include free radical polymerizable or cationic polymerizable compounds. Among these, multifunctional free radical polymerizable monomers are preferred.

[0121] It should be noted that, as a polymerizable monomer, a polymerizable monomer capable of copolymerizing with the aforementioned polymerizable liquid crystal compound is preferred. The amount of polymerizable monomer used relative to the total mass of the polymerizable liquid crystal compound is preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 30% by mass or less.

[0122] Furthermore, from the viewpoint of uniformity of the coated film and film strength, the composition for forming the phase retardation layer may contain a surfactant. Conventionally known compounds can be cited as surfactants. Among these, fluorinated compounds are particularly preferred.

[0123] Furthermore, the composition for forming the phase retardation layer may contain a solvent, preferably an organic solvent. Examples of organic solvents include amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Additionally, two or more organic solvents may be used in combination.

[0124] Furthermore, the composition for forming the retardation layer may include various orientation agents such as vertical orientation promoters (e.g., polarizer interface-side vertical orientation agent, air interface-side vertical orientation agent) and horizontal orientation promoters (e.g., polarizer interface-side horizontal orientation agent, air interface-side horizontal orientation agent). In addition to the above-mentioned components, the composition for forming the retardation layer may also include adhesion modifiers, plasticizers, polymers, etc.

[0125] The aforementioned active energy rays include ultraviolet light, visible light, electron beams, and X-rays, with ultraviolet light being preferred. Examples of light sources for these active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380–440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0126] The intensity of ultraviolet radiation is typically 100 mW / cm² in the ultraviolet B band (wavelength range above 280 nm and below 310 nm). 2 Above and 3000mW / cm 2 The intensity of ultraviolet irradiation is preferably in the wavelength range that is effective in activating cationic polymerization initiators or free radical polymerization initiators. The irradiation time is typically 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 even more preferably 0.1 seconds or more and 1 minute or less.

[0127] Ultraviolet irradiation can be performed once or in multiple sessions. While this also depends on the polymerization initiator used, the cumulative light intensity at a wavelength of 365 nm is preferably set to 700 mJ / cm². 2 The above is more preferably set at 1100 mJ / cm. 2 The above is further optimized to 1300 mJ / cm. 2 The above-mentioned cumulative light intensity is beneficial for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the liquid crystal curing layer and improving heat resistance. The cumulative light intensity at a wavelength of 365 nm is preferably set to 2000 mJ / cm². 2 Hereinafter, a more preferred setting is 1800 mJ / cm 2 The following assumes that the aforementioned cumulative light intensity may cause coloration of the liquid crystal curing layer.

[0128] The thickness of the liquid crystal curing layer is, for example, 0.5 μm or more and 5 μm or less. When the thickness of the liquid crystal curing layer is within the above range, sufficient durability can be obtained, and it can contribute to the thinning of the foldable polarizer 10. The thickness of the liquid crystal curing layer can be adjusted to obtain the desired in-plane phase difference value and thickness direction phase difference value of a λ / 4 layer, a λ / 2 layer, or a positive C layer.

[0129] The phase retardation layer 105 may also comprise a plurality of phase retardation layers, each having different phase retardation characteristics, stacked together. The individual phase retardation layers can be stacked using an adhesive, or a composition comprising a polymerizable liquid crystal compound can be coated onto the surface of the already formed phase retardation layer and cured.

[0130] [Substrate]

[0131] A layer containing a cured polymeric liquid crystal compound can be formed, for example, on an alignment layer disposed on a substrate. The substrate can be a strip-shaped substrate that functions to support the alignment layer. This substrate functions as a release support, capable of supporting the liquid crystal cured layer and the alignment layer for transfer. Furthermore, it is preferable that its surface has adhesive strength sufficient for peeling. Examples of substrates include thermoplastic resin films that are light-transmitting, preferably optically transparent. Examples of thermoplastic resin films include the thermoplastic resin film exemplified in the description of the polarizer protective layer described above.

[0132] Various anti-adhesion treatments can be applied to the substrate. Examples of anti-adhesion treatments include easy-adhesion treatments, treatments involving the incorporation of fillers, and embossing (knurling). By applying such anti-adhesion treatments to the substrate, it is possible to effectively prevent the substrates from adhering to each other during winding, which is known as sticking, and there is a tendency to easily improve productivity.

[0133] [Orientation Layer]

[0134] A layer containing a cured polymeric liquid crystal compound is formed on a substrate using an alignment layer. That is, the cured polymeric liquid crystal compound layer is stacked on the alignment layer in the order of substrate and alignment layer.

[0135] It should be noted that the alignment layer is not limited to a vertical alignment layer; it can be an alignment layer in which the molecular axes of the polymeric liquid crystal compound are horizontally aligned, or an alignment layer in which the molecular axes of the polymeric liquid crystal compound are tilted. Preferably, the alignment layer has solvent resistance that prevents dissolution due to coating of the composition containing the polymeric liquid crystal compound (described later), and heat resistance for solvent removal and heat treatment for the alignment of the liquid crystal compound. Examples of alignment layers include alignment layers containing an alignment polymer, photoalignment films, and groove alignment layers in which a surface-formed pattern or multiple grooves are formed for alignment. The thickness of the alignment layer is typically in the range of 10 nm or more and 10,000 nm or less.

[0136] In addition, the alignment layer has the function of supporting the liquid crystal curing layer and can function as a release support. It can also be an alignment layer that can support the liquid crystal curing layer for transfer and has an adhesive strength on its surface that allows for peeling.

[0137] As the resin used in the alignment layer, a resin polymerized from a polymeric compound can be used. A polymeric compound is a compound having polymeric groups, typically a non-liquid-liquid polymeric non-liquid-liquid compound that does not form a liquid crystal state. The polymeric compound is polymerized by the reaction of its polymeric groups with each other, thereby forming a resin. As long as the resin is used in the formation stage of the liquid crystal curing layer as an alignment layer for aligning the polymeric liquid crystal compound and is not included in the liquid crystal curing layer, and is a resin used as a known material for alignment layers, there are no particular limitations. Cured products obtained by curing monofunctional or polyfunctional (meth)acrylate monomers under a polymerization initiator, as previously known, can be used. Specifically, examples of (meth)acrylate monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, 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, and carbamate acrylates. It should be noted that the resin can be one of these monomers or a mixture of two or more.

[0138] The alignment layer can be peeled off along with the substrate after the phase difference layer is formed, before or after the process of stacking with linear polarization layers, etc.

[0139] Furthermore, for the purpose of improving peelability from the substrate and imparting film strength to the liquid crystal curing layer, an alignment layer may be included in the liquid crystal curing layer. When the liquid crystal curing layer includes an alignment layer, it is preferable to use a cured product obtained by curing monofunctional or difunctional (meth)acrylate monomers, imide monomers, or vinyl ether monomers as the resin for the alignment layer.

[0140] Examples of monofunctional (meth)acrylate monomers include alkyl (meth)acrylates with 4 to 16 carbon atoms, β-carboxyalkyl (meth)acrylates with 2 to 14 carbon atoms, alkylated phenyl (meth)acrylates with 2 to 14 carbon atoms, methoxy polyethylene glycol (meth)acrylates, phenoxy polyethylene glycol (meth)acrylates, and isobornyl (meth)acrylate.

[0141] Examples of difunctional (meth)acrylate monomers include 1,3-butanediol di(meth)acrylate; 1,3-butanediol (meth)acrylate; 1,6-hexanediol di(meth)acrylate; ethylene glycol di(meth)acrylate; diethylene glycol di(meth)acrylate; neopentyl glycol di(meth)acrylate; triethylene glycol di(meth)acrylate; tetraethylene glycol di(meth)acrylate; polyethylene glycol diacrylate; bis(acryloyloxyethyl) ether of bisphenol A; ethoxylated bisphenol A di(meth)acrylate; propoxylated neopentyl glycol di(meth)acrylate; ethoxylated neopentyl glycol di(meth)acrylate; and 3-methylpentyl glycol di(meth)acrylate.

[0142] In addition, examples of imide-based resins formed by curing imide monomers include polyamides and polyimides. It should be noted that the imide-based resin can be one of these or a mixture of two or more.

[0143] In addition, the resin forming the orientation layer may contain monomers other than monofunctional and difunctional (meth)acrylate monomers, imide monomers and vinyl ether monomers, but the proportion of monofunctional and difunctional (meth)acrylate monomers, imide monomers and vinyl ether monomers in the total monomers may be 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more.

[0144] When the retardation layer 105 includes an alignment layer, the thickness of the alignment layer is typically in the range of 10 nm or more and 10,000 nm or less. When the alignment of the retardation layer 105 is in-plane relative to the film surface, the thickness of the alignment layer is preferably 10 nm or more and 1,000 nm or less. When the alignment of the retardation layer 105 is perpendicular to the film surface, the thickness is preferably 100 nm or more and 10,000 nm or less. If the thickness of the alignment layer is within the above range, the peelability of the substrate can be improved, and appropriate film strength can be imparted.

[0145] [Other layers]

[0146] The foldable polarizing plate 10 may also have at least one of an adhesive layer and a protective film.

[0147] [Adhesive layer]

[0148] The foldable polarizer 10 may have an adhesive layer disposed on its outermost surface on the side of the phase retardation layer 105. The adhesive layer may be a layer used for attaching display modules such as touch sensor panels and image display elements to the foldable polarizer 10. The adhesive layer is typically composed of an adhesive. Conventionally known adhesives can be used without particular limitation, and adhesives with base polymers such as acrylic polymers, urethane polymers, silicone polymers, and polyvinyl ether polymers can be used. Alternatively, active energy radiation-cured adhesives, thermosetting adhesives, etc., can also be used.

[0149] [Protective Film]

[0150] The foldable polarizer 10 may include a protective film for protecting its surface, typically the surface of a cured resin layer 100. The protective film may be disposed on the outermost surface of the foldable polarizer 10. The protective film, along with its adhesive layer, is peeled off after the polarizer has been attached, for example, to an image display element or other optical component.

[0151] The protective film, for example, consists of a substrate film and an adhesive layer laminated thereon. Regarding the adhesive layer, the description of the bonding layer described above applies. The resin constituting the substrate film can be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, or a thermoplastic resin such as polycarbonate. A polyester-based resin such as polyethylene terephthalate is preferred.

[0152] The thickness of the protective film is not particularly limited, but is preferably set to a range of 20 μm or more and 200 μm or less. If the thickness of the substrate is 20 μm or more, there is a tendency to easily impart strength to the foldable polarizing plate 10.

[0153] [Layer Structure of the Foldable Polarizing Plate]

[0154] Figure 3 This is a schematic cross-sectional view showing another example of the layered structure of a foldable polarizing plate. Figure 3 The foldable polarizer 20 shown sequentially comprises a polarizer protective layer 100, a cured resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, an adhesive layer 104, and a phase retardation layer 160. The phase retardation layer 160 comprises a first liquid crystal cured layer 161, a second adhesive layer 162, and a second liquid crystal cured layer 163. At least any 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.

[0155] Figure 4 This is a schematic cross-sectional view showing another example of the layered structure of a foldable polarizing plate. Figure 4The foldable polarizer 30 shown sequentially comprises a protective film 180, a polarizer protective layer 100, a curing resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, an adhesive layer 104, and a phase retardation layer 160. The phase retardation layer 160 comprises a first liquid crystal curing layer 161, a second adhesive layer 162, and a second liquid crystal curing layer 163. At least any one of the curing resin layer 101, the first adhesive layer 102, the first liquid crystal curing layer 161, the second adhesive layer 162, and the second liquid crystal curing layer 163 can be a thin film curing layer.

[0156] Figure 5 This is a schematic cross-sectional view showing another example of the layered structure of a foldable polarizing plate. Figure 5 The foldable polarizer 40 shown sequentially comprises a polarizer protective layer 100, a cured resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, an adhesive layer 104, a phase retardation layer 160, and an adhesive layer 170. The phase retardation layer 160 comprises a first liquid crystal cured layer 161, a second adhesive layer 162, and a second liquid crystal cured layer 163. At least any 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.

[0157] [Second Method]

[0158] The second type of foldable polarizer has a linear polarization layer and a phase retardation layer stacked together, and includes a thin film curing layer with a thickness of less than 5 μm. When the thickness of the foldable polarizer is set to 100%, the thin film curing layer exists only in a range of 0% to 90% in the thickness direction, starting from the outermost surface of the phase retardation layer side, with reference to the linear polarization layer of the foldable polarizer. The descriptions regarding the shape, size, thickness, and application of the foldable polarizer are the same as those in the first type described above.

[0159] Figure 6 The foldable polarizer 5 shown includes a linear polarization layer 6 and a phase difference layer 7. The description of the linear polarization layer 6 and the phase difference layer 7 is the same as that in the first embodiment described above.

[0160] The foldable polarizer 5 can be bent with the phase difference layer 7 side as the inner side, based on the linear polarization layer 6. When the foldable polarizer 5 is repeatedly bent along the bending axis with the phase difference layer 7 side as the inner side, based on the linear polarization layer 6, and with the bending radius of the inner surface being 1.5 mm, it preferably does not produce cracks even after 50,000 bends, and more preferably does not produce cracks even after 80,000 bends.

[0161] [Film Curing Layer]

[0162] Although Figure 6Not shown, but the foldable polarizing plate 5 includes a thin film cured layer with a thickness of 5 μm or less. The thin film cured layer may be a layer of cured material containing a curable resin. Examples and preferred ranges of the type, thickness, and martensitic hardness of the thin film cured layer are as described in the first embodiment above.

[0163] When the thickness of the foldable polarizing plate 5 is set to 100%, the thin film curing layer exists only within a range T2, which is more than 0% and less than 90% in the thickness direction, starting from the outermost surface of the phase difference layer 7 side, with the linear polarizing layer 6 of the foldable polarizing plate 5 as the reference. Because the thin film curing layer exists only within the range T2, even when the foldable polarizing plate 5 is repeatedly bent with the linear polarizing layer 6 as the reference and the phase difference layer 7 side as the inner side, it is less likely to crack or break.

[0164] When the thickness of the foldable polarizing plate 5 is set to 100%, the thin film curing layer exists only in the range of 0% or more and 90% or less in the thickness direction from the outermost surface of the phase difference layer 7 side, with the linear polarizing layer 6 of the foldable polarizing plate 5 as a reference. More preferably, it exists only in the range of 0% or more and 75% or less. Even more preferably, it exists only in the range of 0% or more and 60% or less.

[0165] Figure 7 This is a schematic cross-sectional view illustrating an example of the layer configuration of a foldable polarizing plate according to a second aspect of the present invention. Figure 7 The foldable polarizer 50 shown comprises, in sequence, a polarizer protective layer 200, a cured resin layer 201, an adhesive layer 202, a linear polarizing layer 203, an adhesive layer 204, and a phase retardation layer 205 including a liquid crystal cured layer (not shown). 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.

[0166] The foldable polarizer 50 may further include other layers besides those described above. Examples of other layers include a protective film and an adhesive layer. The description of the polarizer protective layer 200, the cured resin layer 201, the adhesive layer 202, the linear polarization layer 203, the bonding layer 204, the phase difference layer 205, the protective film, and the adhesive layer in the second embodiment shall apply to the description in the first embodiment described above.

[0167] [Manufacturing method of foldable polarizing plate]

[0168] In the case where a foldable polarizer includes a polarizer protective layer and a retardation layer, and has a curable resin layer as a thin film curing layer, the foldable polarizer can be manufactured, for example, by a method including a bonding process. This bonding process involves bonding the polarizer protective layer (which is a thermoplastic resin film with a curable resin layer) to the linear polarizing layer using an adhesive layer, and then bonding the retardation layer to the opposite side of the linear polarizing layer from the cured film layer using a bonding layer. In the bonding process, when the layers are bonded together using a bonding layer, to improve adhesion, it is preferable to perform a surface activation treatment, such as corona treatment, on one or both of the bonding surfaces. The curable resin layer, the linear polarizing layer, and the retardation layer can be manufactured as described above.

[0169] The bonding layer can be prepared in the form of an adhesive sheet. The adhesive sheet can be made, for example, by dissolving or dispersing an adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, forming an adhesive-containing layer in sheet form on a release film that has undergone a demolding treatment, and further bonding other release films onto this bonding layer. The layers can be bonded by bonding an adhesive sheet with one release film peeled off to a layer, then peeling off another release film and bonding another layer.

[0170] As a method for applying adhesive liquid to the release film, conventional coating techniques using die coaters, comma coaters, reverse roller coaters, gravure coaters, bar coaters, wire bar coaters, doctor blade coaters, and air knife coaters are sufficient.

[0171] The release film is preferably composed of a plastic film and a release layer. Examples of plastic films include polyester films such as polyethylene terephthalate films, polybutylene terephthalate films, and polyethylene naphthalate films, and polyolefin films such as polypropylene films. The release layer can be formed, for example, from a release layer forming composition. The main component (resin) constituting the release layer forming composition is not particularly limited, and examples include silicone resins, alkyd resins, acrylic resins, and long-chain alkyl resins.

[0172] <Image display device>

[0173] The foldable polarizer of this invention can be used in an image display device. An image display device is a device having an image display panel and including a light-emitting element or device as a light source. Examples of image display devices include liquid crystal displays, organic electroluminescent (EL) displays, inorganic electroluminescent (EL) displays, and touch panel displays. The foldable polarizer can be disposed on the viewing side of the image display panel. The foldable polarizer can, for example, be laminated onto the image display device using an adhesive layer. The image display device can be a foldable image display device.

[0174] <Laminated body for foldable image display device>

[0175] A laminate for a foldable image display device may have a front panel on the viewing side of a foldable polarizing plate and a touch panel (described later) on the opposite side of the foldable polarizing plate from the front panel. The foldable image display device includes a laminate for a foldable image display device and an organic EL display panel. The laminate for a foldable image display device is disposed on the viewing side relative to the organic EL display panel, and is configured to be bendable. The laminate for a foldable image display device may include a foldable polarizing plate, and either or both of the front panel and the touch panel. Their stacking order is arbitrary, but it is preferable to stack them from the viewing side in the order of front panel (window), foldable polarizing plate, touch panel, or front panel, touch panel, foldable polarizing plate. If a foldable polarizing plate is present on the viewing side of the touch panel, the pattern on the touch panel becomes less visible, and the visibility of the displayed image becomes better, which is therefore preferable. The individual components can be laminated using adhesives or similar bonding agents. Additionally, it may have a light-shielding pattern formed on at least one side of any one of the layers of the front panel, the foldable polarizing plate, and the touch panel.

[0176] [Front Panel]

[0177] A front panel can be disposed on the observation side of the foldable polarizer. The front panel can be laminated onto the foldable polarizer using an adhesive layer. Examples of adhesive layers include the adhesive layer described above.

[0178] Examples of front panels include glass and front panels with a hard coating on at least one side of a resin film. For example, high-transmittance glass or tempered glass can be used. Especially when using a thin, transparent surface material, chemically strengthened glass is preferred. The thickness of the glass can be, for example, 20 μm or more and 5 mm or less.

[0179] A front panel with a hard coating on at least one side of a resin film can be foldable, unlike conventional glass. The thickness of the hard coating is not particularly limited; for example, it can be greater than 5 μm but less than 100 μm.

[0180] As a resin membrane, it can be a membrane formed from polymers such as cycloolefin derivatives containing monomers such as norbornene or polycyclic norbornene monomers, cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isobutyl cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose), ethylene-vinyl acetate copolymers, polycyclic cyclic olefins, polyesters, polystyrene, polyamides, polyetherimides, polyacrylic acids, polyimides, polyamide-imides, polyethersulfones, polysulfones, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, epoxy resins, etc. The resin membrane can be unstretched, uniaxial, or biaxially stretched. These polymers can be used individually or in combination of two or more. As the resin film, polyamide-imide films or polyimide films with excellent transparency and heat resistance, uniaxial or biaxial stretched polyester films, cycloolefin derivative films with excellent transparency and heat resistance and capable of handling large-scale films, polymethyl methacrylate films, and triacetyl cellulose and isobutyl cellulose films that are transparent and optically anisotropic are preferred. The thickness of the resin film can be 5 μm or more and 200 μm or less, preferably 20 μm or more and 100 μm or less.

[0181] [Light-blocking pattern]

[0182] A light-shielding pattern (border) can be formed on the display element side of the front panel. The light-shielding pattern can conceal the wiring of the display device, making it invisible to the user. The color and / or material of the light-shielding pattern are not particularly limited, and it can be formed using resin materials with various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern can 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. Furthermore, to suppress the infiltration of air bubbles and the visibility of the interface caused by the height difference between the light-shielding pattern and the display element, the light-shielding pattern can be given a shape.

[0183] [Touch Panel]

[0184] The touch panel serves as an input mechanism. Various touch sensors have been proposed for the touch panel, including resistive film, surface acoustic wave, infrared, electromagnetic induction, and capacitive touch sensors; any type can be used. Among these, capacitive touch sensors are preferred. The capacitive touch sensor consists of an active area and an active area located around the active area. The active area corresponds to the area on the display panel where an image is displayed (the display section), and is the area that senses the user's touch. The active area corresponds to the area on the display device where no image is displayed (the non-display section). The touch panel may include: a substrate with foldable characteristics; a sensing pattern formed on the active area of ​​the substrate; and sensing lines formed on the active area of ​​the substrate for connection to an external driving circuit via the sensing pattern and pads. The substrate with foldable characteristics can be made of the same material as the transparent substrate of the front panel.

[0185] Reference Figure 8 The layer structure of the laminate used in the foldable image display device is explained. Figure 8 The foldable image display device laminate 60 shown includes a foldable polarizer 40, a front panel 121 with an adhesive layer 122 separating the viewing side of the foldable polarizer 40, and a touch panel 123 with an adhesive layer 170 separating the opposite side of the foldable polarizer 40 from the viewing side. The foldable polarizer 40 sequentially includes a polarizer protective layer 100, a curing resin layer 101, a first adhesive layer 102, a linear polarizing layer 103, an adhesive layer 104, a phase retardation layer 160, and an adhesive layer 170. The phase 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 any one of the curing resin layer 101, the first adhesive layer 102, the first liquid crystal curing layer 161, the second adhesive layer 162, and the second liquid crystal curing layer 163 can be a thin-film curing layer.

[0186] Example

[0187] The present invention will be further described in detail below through examples. Unless otherwise specified, "%" and "parts" in the examples refer to mass % and mass parts.

[0188] [Layer thickness]

[0189] The film thickness was measured using a contact film thickness measuring device (Nikon Corporation "MH-15M").

[0190] [Bending resistance]

[0191] The following is for reference Figure 9The evaluation method for bending resistance is explained. A foldable polarizing plate was prepared using a super-cutting machine and cut into dimensions of 10mm short side × 100mm long side, with the long side aligned with the absorption axis of the linear polarizer, to create test piece 300. The short side of test piece 300 (in the case of a test piece with a TAC film on the phase retardation layer side, after the TAC film has been removed) was fixed in contact with the two-piece clamps 301 and 302 of the bending resistance testing machine. Figure 9 a). Using Kapton film tape (manufactured by Toray / DuPont) 303, the two ends of the test piece were fixed 10 mm each along their long sides, with the distance L1 between the two plate clamps 301 and 302 being 53 mm. Next, with the bending radius R of the test piece at 1.5 mm, the two plate clamps 301 and 302 were moved in the directions indicated by arrows A1 and A2, respectively, causing the distance L2 between the clamps to continuously change to 2R. This bent the fixed test piece so that the absorption axis of the linear polarizer was orthogonal to the bending axis. Figure 9 b). Perform bending at a speed of 60 rpm and measure the number of bends until the membrane cracks and breaks.

[0192] [Madall hardness]

[0193] Martens hardness was measured using an ultramicrohardness tester (FISCHERSCOPE HM2000: manufactured by Fischer Instruments Co., Ltd.). Figure 10 As shown, electrostatic force was used to adsorb each layer of single film 401 (the liquid crystal curing layer is a liquid crystal curing layer without a support layer) onto soda glass 402, and the martensitic 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 component n=3 was calculated based on the indentation measurement according to ISO14577 as the martensitic hardness.

[0194] <Example 1>

[0195] A linear polarizer (PVA, 8 μm thick) with iodine-oriented adsorption on a polyvinyl alcohol-based resin film is prepared by bonding a triacetyl cellulose (TAC) film and an acrylic resin film to both sides with water, followed by drying. This produces a two-layer release paper PVA consisting of a TAC film / PVA / acrylic resin film. The acrylic resin film side of the two-layer release paper PVA is then peeled off, revealing a hard coating (HC) layer (3 μm thick, Marsh hardness 266.843 N / mm) containing an ultraviolet absorber, which serves as a protective film for the polarizer. 2 The hard coating side of a cyclic olefin resin (COP) film (22 μm thick) is bonded with an adhesive layer (0.1 μm thick, martensitic hardness 522.611 N / mm) containing a water-based adhesive.2 The surfaces are then bonded together and dried in an oven. The bonded surfaces are then subjected to corona treatment (780W x 1 pass).

[0196] Next, the TAC film of the linear polarizer consisting of a COP film, an HC layer containing UV absorbers, an adhesive layer, a PVA layer, and a TAC film is peeled off, and the PVA surface is corona treated. An adhesive layer (5 μm thick) with a diaphragm is then bonded to it.

[0197] A λ / 2 plate (2 μm thick, Marvin hardness 239.038 N / mm) is formed by coating a polymerizable liquid crystal compound onto a TAC film and then curing it. 2 ) and λ / 4 plate (thickness 1μm, martensitic hardness 214.012N / mm) 2 The liquid crystal surfaces are bonded together with an adhesive layer containing a UV-curable adhesive (2 μm thick, Martens hardness 175.665 N / mm). 2 (Laminate and fabricate phase difference layer stacks)

[0198] The diaphragm of the adhesive layer attached to the linear polarizer was peeled off, and the TAC film on the λ / 2 plate side of the phase retardation layer stack was peeled off. Only the liquid crystal surface was corona treated and then bonded to the adhesive layer. A foldable polarizer consisting of a COP film / HC layer containing UV absorber / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / TAC film was obtained (the thickness excluding the TAC film is 43.1 μm). The evaluation results of the bending resistance are shown in Table 1. In the obtained foldable polarizer, the hard coating layer, the adhesive layer containing water-based adhesive, the λ / 2 plate, the adhesive layer containing UV-curable adhesive, and the λ / 4 plate are thin film curing layers, and the display module side is the TAC film side.

[0199] <Example 2>

[0200] Based on Example 1, a hard coating (HC) layer (without UV absorber, 2 μm thickness, Martens hardness 280.775 N / mm) was used. 2 This can be used instead of a hard coating (HC) layer containing UV absorbers (3μm thickness, Martens hardness 266.843 N / mm). 2 Otherwise, following the same procedure as in Example 1, a foldable polarizing plate (with a thickness of 42.1 μm excluding the TAC film) was obtained having a layer structure consisting of a COP film / HC layer / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / TAC film. The results are shown in Table 1.

[0201] <Example 3>

[0202] Based on Example 1, a hard coating (HC) layer (without UV absorber, 2 μm thickness, Martens hardness 280.775 N / mm) was used. 2 This can replace the use of a hard coating (Hc) layer containing UV absorbers (3μm thickness, Martens hardness 266.843 N / mm). 2 The TAC film was peeled off from the foldable polarizing plate, and an adhesive layer (15 μm thick) containing adhesive was bonded to the surface of the λ / 4 plate. Otherwise, the same procedure as in Example 1 was followed to obtain a foldable polarizing plate (with a thickness of 57.1 μm including the adhesive layer) having a layer structure of COP film / HC layer / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / adhesive layer. The results are shown in Table 1.

[0203] <Comparative Example 1>

[0204] Based on Example 1, instead of bonding PVA to the UV-absorbing hard coating (HC) layer side of the polarizer protective film using an adhesive layer, PVA was bonded to the COP film side of the polarizer protective film using an adhesive layer. Otherwise, the process was the same as in Example 1, resulting in a foldable polarizer consisting of a HC layer containing UV absorbers, a COP film, an adhesive layer, PVA, an adhesive layer, a λ / 2 plate, an adhesive layer, a λ / 4 plate, and a TAC film. The results are shown in Table 1.

[0205] <Comparative Example 2>

[0206] Based on Example 2, instead of bonding PVA to the hard coating (HC) layer side of the polarizer protective film using an adhesive layer, PVA was bonded to the COP film side of the polarizer protective film using an adhesive layer. Otherwise, the process was the same as in Example 1, resulting in a foldable polarizer consisting of an HC layer, a COP film, an adhesive layer, PVA, an adhesive layer, a λ / 2 plate, an adhesive layer, a λ / 4 plate, and a TAC film. The results are shown in Table 1.

[0207] <Comparative Example 3>

[0208] Based on Example 3, instead of bonding PVA to the hard coating (HC) layer side of the polarizer protective film using an adhesive layer, PVA was bonded to the COP film side of the polarizer protective film using an adhesive layer. Otherwise, the process was the same as in Example 1, resulting in a foldable polarizer consisting of an HC layer / COP film / adhesive layer / PVA / adhesive layer / λ / 2 plate / adhesive layer / λ / 4 plate / adhesive layer. The results are shown in Table 1.

[0209] [Table 1]

[0210]

[0211] Explanation of reference numerals in the attached figures

[0212] 1, 5, 10, 20, 30, 40, 50: Foldable polarizing plate; 2: Window unit; 3, 122: Adhesive layer; 4: Display module; 100, 200: Polarizing film protective layer; 101, 201: Cured resin layer; 102, 202: First adhesive layer; 6, 103, 203: Linear polarizing layer; 104, 204: Bonding layer; 7, 105, 160, 205: Phase retardation layer; 12 1: Front panel; 123: Touch panel; 161: First liquid crystal curing layer; 162: Second adhesive layer; 163: Second liquid crystal curing layer; 170: Adhesive layer; 180: Protective film; 300: Test piece; 301, 302: Plate clamps; 303: Kapton film tape; 401: Single film; 402: Sodium glass; 403: Vickers indenter; L1, L2: Distance between clamps; T1, T2: Range.

Claims

1. A foldable polarizing plate disposed between an adhesive layer and a display module that are stacked adjacent to a window unit. For the foldable polarizing plate, starting from the adhesive layer that is stacked adjacent to the window unit, a polarizing protective layer, a thin film curing layer with a thickness of less than 5 μm, and a linear polarizing layer are stacked sequentially. The cured film layer is a layer containing a cured resin. When the thickness of the foldable polarizing plate is set to 100%, the thin film cured layer exists only in a range of 0% to 90% in the thickness direction, starting from the outermost surface of the foldable polarizing plate on the display module side. The Martens hardness of the thin film cured layer is 150 N / mm at 23°C 2 The Martens hardness of the thin film cured layer is 150 N / mm at 23°C 2 The Martens hardness of the thin film cured layer is 150 N / mm at 23°C 2. The foldable polarizing plate according to claim 1, wherein the thickness is 20 μm or more and 150 μm or less.

3. An image display device comprising the foldable polarizing plate as described in claim 1 or 2.

4. A foldable polarizing plate, comprising, in sequence, a polarizer protective layer, a thin film curing layer with a thickness of less than 5 μm, a linear polarizing layer, and a phase difference layer. The cured film layer is a layer containing a cured resin. When the thickness of the foldable polarizing plate is set to 100%, the thin film cured layer exists only in a range of 0% to 90% in the thickness direction, starting from the outermost surface of the phase difference layer side, with the linear polarization layer of the foldable polarizing plate as a reference. The Martens hardness of the thin film cured layer is 150 N / mm at 23°C 2 Above and 800 N / mm 2 Below.

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