Circular polarizing plate and display device

Abstract

Provided is a circular polarizing plate (1) used in a bendable display device, the circular polarizing plate (1) being provided with a polarizer (2) and a phase difference layer (RF) disposed on one side of the polarizer (2), the polarizer (2) having a visibility correction unit transmittance of 42% or more, the phase difference layer (RF) including a 1 / 2 wavelength plate (3) and a 1 / 4 wavelength plate (4), and the 1 / 2 wavelength plate (3) and the 1 / 4 wavelength plate (4) being disposed on the other side of the polarizer (2). The 1 / 2 wavelength plate (3) and the 1 / 4 wavelength plate (4) each include a layer obtained by curing a liquid crystal compound, the slow axis direction of the 1 / 4 wavelength plate (4) is positive in rotation counterclockwise from the absorption axis direction of the polarizing plate (2) and is in the range of-20 DEG to 20 DEG, and the bending direction of the display device is set in the range of 80 DEG to 100 DEG or-10 DEG to 10 DEG with respect to the slow axis direction of the 1 / 4 wavelength plate (4).

Description

[0001] This application is a divisional application of an application with a filing date of November 9, 2018, an application number of 201880071355.6, and an invention name of “Circular Polarization Plate and Display Device”. Technical Field

[0002] The present invention relates to a circular polarization plate and also to a bendable display device including the circular polarization plate.

[0003] This application claims priority based on Japanese Patent Application No. 2017-217106 filed on November 10, 2017, and Japanese Patent Application No. 2018-201205 filed on October 25, 2018, the contents of which are incorporated herein by reference. Background Art

[0004] In the past, circular polarizing plates were used to suppress the adverse effects of external light reflection in display devices. On the other hand, in recent years, there has been an increasing demand for bendable (flexible) display devices, such as organic electroluminescent (EL) display devices. In addition, there is a growing demand for not only simple flexibility of display devices, but also flexibility with a very small radius of curvature.

[0005] However, if the organic EL display device is bent with a very small radius of curvature, a large force is applied to the phase difference layer in the circularly polarizing plate (tensile force is applied to the outside of the bent portion, and compressive force is applied to the inside of the bent portion), so there is a problem that the phase difference of the bent portion changes.

[0006] Therefore, in order to address this problem, the following Patent Document 1 proposes a circularly polarizing plate having a retardation film including a 1 / 2 wavelength (λ / 2) plate and a 1 / 4 wavelength (λ / 4) plate, wherein the λ / 2 plate and the λ / 4 plate respectively contain a liquid crystal compound, and the slow axis direction of the retardation film is adjusted to an angle of 75 to 105 degrees relative to the bending direction of the display device.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2016 / 158300 Summary of the invention

[0010] Problems to be solved by the invention

[0011] However, in the above-mentioned bendable display device, there is a demand for further improvement in visibility and for reduction in change in hue (color tone) of reflected light from a bent portion when the display device is bent.

[0012] Therefore, the circular polarizing plate used in a bendable display device needs to follow the curved portion of the display device and is also required to be less likely to wrinkle before and after the circular polarizing plate is bent.

[0013] The present invention has been made in view of the above conventional situation, and an object of the present invention is to provide a circularly polarizing plate which reduces color change due to bending and is less likely to wrinkle due to bending, and a bendable display device having the circularly polarizing plate.

[0014] Methods used to solve problems

[0015] As a method for solving the above-mentioned problems, according to a method of the present invention, there is provided a circular polarizing plate, characterized in that it is a circular polarizing plate used in a bendable display device, which comprises a polarizer and a phase difference layer arranged on one side of the polarizer, the visibility correction monomer transmittance of the polarizer is greater than 42%, the phase difference layer comprises a 1 / 2 wavelength plate and a 1 / 4 wavelength plate, the 1 / 2 wavelength plate and the 1 / 4 wavelength plate respectively comprise layers obtained by curing liquid crystal compounds, the slow axis direction of the 1 / 4 wavelength plate is in the range of -20° to 20° from the absorption axis direction of the polarizer with the counterclockwise rotation being positive, and the bending direction of the display device is set to the range of 80° to 100° or -10° to 10° relative to the slow axis direction of the 1 / 4 wavelength plate.

[0016] In the circular polarization plate, the half-wave plate and the quarter-wave plate may be bonded to each other via an adhesive layer.

[0017] Furthermore, in the circular polarization plate, the display device may be an organic electroluminescent display device.

[0018] In the circularly polarizing plate, the color tone of the reflected light obtained before and after bending may not be sandwiched between Chromaticity coordinates Coordinate axis and The axis changes the sign of the composition.

[0019] According to an aspect of the present invention, there is provided a bendable display device including any of the above circular polarization plates and a bendable display panel.

[0020] Furthermore, the display device may include a touch sensor disposed on the side of the circular polarizing plate facing the display panel, and a window film disposed on the side opposite to the side of the circular polarizing plate facing the display panel.

[0021] Furthermore, the display device may include a touch sensor disposed on a side of the circular polarization plate opposite to a side facing the display panel.

[0022] That is, the present invention has the following aspects.

[0023] [1] A circular polarizing plate, characterized in that it is a circular polarizing plate used in a bendable display device, comprising a polarizing plate and a phase difference layer arranged on one side of the polarizing plate, the polarizing plate having a visibility correction single body transmittance of 42% or more, the phase difference layer comprising a 1 / 2 wavelength plate and a 1 / 4 wavelength plate, the 1 / 2 wavelength plate and the 1 / 4 wavelength plate respectively comprising a layer obtained by curing a liquid crystal compound, the slow axis direction of the 1 / 4 wavelength plate being in the range of -20° to 20° with the direction of the absorption axis of the polarizing plate being counterclockwise as positive, and the bending direction of the display device is set to be in the range of 80° to 100° or -10° to 10° relative to the slow axis direction of the 1 / 4 wavelength plate.

[0024] [2] The circularly polarizing plate according to [1], wherein the half-wavelength plate and the quarter-wavelength plate are bonded to each other via an adhesive layer.

[0025] [3] The circular polarization plate according to [1] or [2], wherein the display device is an organic electroluminescent display device.

[0026] [4] The circularly polarizing plate according to any one of [1] to [3], wherein the color tone of the reflected light obtained before and after bending is not sandwiched between Chromaticity coordinates Coordinate axis and The axes change sign.

[0027] [5] A bendable display device comprising the circularly polarizing plate according to any one of [1] to [4] and a bendable display panel.

[0028] [6] The bendable display device according to [5] is characterized by comprising a touch sensor arranged on the side of the circular polarizing plate opposite to the display panel, and a window film arranged on the opposite side of the circular polarizing plate opposite to the display panel.

[0029] [7] The flexible display device according to [5], further comprising a touch sensor disposed on the opposite side of the circular polarization plate to the side facing the display panel.

[0030] Effects of the Invention

[0031] As described above, according to the aspects of the present invention, it is possible to provide a circular polarizing plate that reduces color change due to bending and is less likely to wrinkle due to bending, and a bendable display device including the circular polarizing plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a cross-sectional view showing the structure of a circularly polarizing plate according to one embodiment of the present invention.

[0033] Figure 2 Yes means have Figure 1 A cross-sectional view of the structure of a display device that can be bent and has a circular polarization plate shown.

[0034] Figure 3 It is a cross-sectional view showing the structure of an organic EL element.

[0035] Figure 4A It is a schematic diagram for explaining a curved state of a display device.

[0036] Figure 4B It is a schematic diagram for explaining a curved state of a display device.

[0037] Figure 4C It is a schematic diagram for explaining a curved state of a display device.

[0038] Figure 4D It is a schematic diagram for explaining a curved state of a display device.

[0039] Figure 5 It is a schematic diagram for explaining the relationship between the bending direction of the display device and the absorption axis direction of the polarizing plate, and the relationship between the slow axis direction of the λ / 2 plate and the slow axis direction of the λ / 4 plate.

[0040] Figure 6 Yes means have Figure 1 A cross-sectional view of another configuration example of a display device having a bendable circular polarizing plate shown. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0042] It should be noted that, in the drawings used in the following description, in order to facilitate observation of each component, the components are sometimes schematically represented, and sometimes the scales of the dimensions are represented differently according to the components. In addition, the materials, numerical values, etc. illustrated in the following description are examples, and the present invention is not necessarily limited to them, and can be implemented after being appropriately changed within the scope of the subject matter.

[0043] As one embodiment of the present invention, for example Figure 1 The circular polarizing plate 1 shown, and Figure 2The following describes a bendable display device 10 having a circular polarization plate 1 as shown. Figure 1 It is a cross-sectional view showing the structure of the circular polarizing plate 1 . Figure 2 It is a cross-sectional view showing the structure of the display device 10 .

[0044] The circular polarizing plate 1 of this embodiment is as follows Figure 1 As shown, the polarizer 2 is provided, and a phase difference layer RF including a half wavelength (λ / 2) plate 3 and a quarter wavelength (λ / 4) plate 4 disposed on one surface side of the polarizer 2. In addition, protective films (protective layers) 5 and 6 are disposed on both surfaces of the polarizer 2, respectively.

[0045] On one side of the polarizing plate 2, a λ / 2 plate 3 is laminated via a PSA layer (adhesive layer) 7. The λ / 2 plate 3 and the λ / 4 plate 4 are laminated via an adhesive layer or an adhesive layer 8. On the surface of the circular polarizing plate 1 opposite to the λ / 4 plate 4, a PSA layer (adhesive layer) 9 for laminating on a display panel 20 described later is arranged. It should be noted that a release film (not shown) is attached to the surface of the PSA layer 9 until use. In addition, the PSA layers 7 and 9 are formed of, for example, an acrylic adhesive.

[0046] The polarizing plate 2 allows linearly polarized light having a polarization plane in a specific direction to pass therethrough, and the light passing through the polarizing plate 2 becomes linearly polarized light vibrating in the transmission axis direction of the polarizing plate. The thickness of the polarizing plate 2 is, for example, about 1 μm to 80 μm.

[0047] As the polarizer 2, for example, a polarizer obtained by dyeing and stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and a partially saponified film of an ethylene / vinyl acetate copolymer can be used. In addition, a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride can be used. Among them, as a polarizer having excellent optical properties, a polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching is preferably used.

[0048] Dyeing with iodine is performed, for example, by immersing the polyvinyl alcohol film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after the dyeing treatment or at the same time as the dyeing. Alternatively, dyeing can be performed after stretching.

[0049] As required, the polyvinyl alcohol film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the polyvinyl alcohol film in water and washing it before dyeing, not only dirt and anti-blocking agent on the surface of the polyvinyl alcohol film can be washed, but also the polyvinyl alcohol film can be swollen to prevent uneven dyeing.

[0050] As the polarizer 2, for example, a polarizer obtained by orienting a dichroic pigment in a cured film obtained by polymerization of a liquid crystal compound can be used as described in Japanese Patent Publication No. 2016-170368. As the dichroic pigment, a dichroic pigment having absorption in the range of wavelength 380 to 800 nm can be used, preferably an organic dye. As the dichroic pigment, for example, an azo compound can be cited. The liquid crystal compound is a liquid crystal compound that can be polymerized while maintaining the orientation unchanged, and can have a polymerizable group in the molecule.

[0051] The visibility-corrected polarization degree of the polarizer 2 is preferably 95% or more, more preferably 97% or more. In addition, it may be 99% or more, or 99.9% or more. The visibility-corrected polarization degree of the polarizer 2 may be 99.995% or less, or 99.99% or less. The visibility-corrected polarization degree may be calculated by using an absorptiophotometer with an integrating sphere ("V7100" of JASCO Corporation) to correct the obtained polarization degree for visibility using a 2-degree field of view (C light source) of "JIS Z 8701:1999".

[0052] By setting the visibility correction polarization degree of the polarizing plate 2 to 95 to 99.9%, it is easy to adjust the initial (before bending) color tone to a position that is deviated from neutral. Therefore, it becomes less likely to interfere with the color tone of the reflected light before and after bending described later. Chromaticity coordinates Coordinate axis and The coordinate axis changes its sign. In addition, by setting the visibility correction polarization degree of the polarizer 2 to 99.9% or more, the durability of the circular polarizing plate 1 can be improved. On the other hand, if the visibility correction polarization degree of the polarizer 2 is less than 95%, there is a case where it cannot function as an anti-reflection film. That is, if the visibility correction polarization degree of the polarizer 2 is 95% or more, it becomes easy to function as an anti-reflection film.

[0053] The visibility-corrected single transmittance of the polarizer 2 is preferably 42% or more, more preferably 44% or more, preferably 60% or less, and more preferably 50% or less. The visibility-corrected single transmittance can be calculated by using an absorptiophotometer with an integrating sphere ("V7100" manufactured by JASCO Corporation) to correct the obtained transmittance for visibility using a 2-degree field of view (C light source) of JIS Z 8701:1999. The lower limit and the upper limit can be combined arbitrarily. As examples of combinations, 42% or more and 60% or less, and 44% or more and 50% or less can be cited.

[0054] By setting the visibility-corrected single transmittance of the polarizer 2 to 42% or more, the orthogonal color tone of the polarizer 2 can be easily adjusted to a position deviating from the neutral side, so that the color change before and after bending described later can be made inconspicuous. On the other hand, if it is greater than 50%, the polarization degree is too low, and there is a case where the anti-reflection function cannot be achieved. That is, if it is less than 50%, the polarization degree will not be too low, and the anti-reflection function can be easily achieved.

[0055] The λ / 2 plate 3 provides a phase difference of π (=λ / 2) along the electric field vibration direction (polarization plane) of the incident light, and has the function of changing the direction (polarization orientation) of linear polarized light. In addition, if circularly polarized light is incident, the rotation direction of the circularly polarized light can be reversed.

[0056] The in-plane retardation value Re(λ) at a specific wavelength λnm of the λ / 2 plate 3 satisfies Re(λ)=λ / 2. This equation can be achieved at any wavelength (e.g., 550nm) in the visible light region. Among them, the in-plane retardation value Re(550) at a wavelength of 550nm preferably satisfies 210nm≤Re(550)≤300nm. In addition, it is more preferable to satisfy 220nm≤Re(550)≤290nm.

[0057] The retardation value in the thickness direction of the λ / 2 plate 3 measured at a wavelength of 550 nm, that is, Rth(550), is preferably −150 to 150 nm, and more preferably −100 to 100 nm.

[0058] The thickness of the λ / 2 plate 3 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and still more preferably 0.5 to 3 μm from the viewpoint of making the wrinkle prevention effect prominent. It should be noted that the thickness of the λ / 2 plate 3 is the value obtained by measuring the thickness of any five points on the surface and taking the arithmetic average of these values.

[0059] The λ / 2 plate 3 may include a film formed by a resin exemplified as a material for the protective films 5 and 6 described later, a layer obtained by curing a liquid crystal compound, and the like. In the case where the λ / 2 plate 3 is formed by a resin, polycarbonate resins, cyclic olefin resins, styrene resins, and cellulose resins are preferred. In the present embodiment, the λ / 2 plate 3 preferably includes a layer obtained by curing a liquid crystal compound. There is no particular limitation on the type of liquid crystal compound, but it can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disc-shaped type (disc-shaped liquid crystal compound, disc-shaped liquid crystal compound) according to its shape. In addition, there are low-molecular type and high-molecular type, respectively. It should be noted that the so-called polymer generally refers to a substance with a degree of polymerization of 100 or more (Polymer Physics and Phase Transfer Dynamics, written by Masao Doi, page 2, Iwanami Shoten, 1992).

[0060] In this embodiment, any liquid crystal compound can be used. Alternatively, two or more rod-like liquid crystal compounds, two or more disc-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disc-like liquid crystal compound can be used.

[0061] It should be noted that, as the rod-shaped liquid crystal compound, for example, the compound described in claim 1 of JP-A-11-513019 or in paragraphs

[0026] to

[0098] of JP-A-2005-289980 can be suitably used. As the disc-shaped liquid crystal compound, for example, the compound described in paragraphs

[0020] to

[0067] of JP-A-2007-108732 or in paragraphs

[0013] to

[0108] of JP-A-2010-244038 can be suitably used.

[0062] The λ / 2 plate 3 is more preferably formed using a liquid crystal compound (rod-like liquid crystal compound or disc-like liquid crystal compound) having a polymerizable group. This can reduce changes in optical characteristics due to temperature and humidity.

[0063] The liquid crystal compound may be a mixture of two or more. In this case, it is preferred that at least one of the liquid crystal compounds has two or more polymerizable groups. That is, the λ / 2 plate 3 is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disc-shaped liquid crystal compound having a polymerizable group by polymerization, and such a layer is included in the layer obtained by curing the liquid crystal compound. In this case, it is no longer necessary to show liquid crystal properties after the layer is formed.

[0064] The type of polymerizable group contained in the rod-shaped liquid crystal compound or the disc-shaped liquid crystal compound is not particularly limited, and for example, a functional group capable of undergoing addition polymerization, such as a polymerizable ethylenically unsaturated group and a cyclic polymerizable group, is preferred. More specifically, for example, (meth)acryloyl, vinyl, styryl, allyl, etc. can be cited. Among them, (meth)acryloyl is preferred. It should be noted that the so-called (meth)acryloyl is a concept that includes both methacryloyl and acryloyl.

[0065] The method for forming the λ / 2 plate 3 is not particularly limited, and a known method can be used. For example, the λ / 2 plate 3 can be manufactured by applying a composition for forming an optically anisotropic layer (hereinafter referred to as "composition") containing a liquid crystal compound having a polymerizable group to a given substrate (including a temporary substrate) to form a coating film, and subjecting the obtained coating film to a curing treatment (irradiation with ultraviolet rays (light irradiation treatment) or heating treatment).

[0066] The composition can be applied by a known method, for example, a wire rod coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

[0067] The composition may contain ingredients other than the above-mentioned liquid crystal compound. For example, the composition may contain a polymerization initiator. The polymerization initiator used may be selected, for example, from a thermal polymerization initiator and a photopolymerization initiator according to the form of the polymerization reaction. For example, as a photopolymerization initiator, there may be mentioned α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, a combination of triaryl imidazole dimers and para-aminophenyl ketones. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, relative to the total solid content of the composition.

[0068] In addition, the composition may contain a polymerizable monomer from the perspective of uniformity of the coating film and strength of the film. As the polymerizable monomer, free radical polymerizable or cationic polymerizable compounds may be cited. Among them, polyfunctional free radical polymerizable monomers are preferred.

[0069] It should be noted that, as the polymerizable monomer, it is preferred that the monomer be copolymerizable with the above-mentioned liquid crystal compound containing a polymerizable group. As specific polymerizable monomers, for example, the polymerizable monomers described in paragraphs

[0018] to

[0020] of Japanese Patent Publication No. 2002-296423 can be cited. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, relative to the total mass of the liquid crystal compound.

[0070] In addition, in the composition, a surfactant may be included from the aspect of uniformity of the coating film and strength of the film. As the surfactant, conventionally known compounds may be cited. Among them, fluorine compounds are particularly preferred. As specific surfactants, for example, compounds described in paragraphs

[0028] to

[0056] in Japanese Patent Application No. 2001-330725 and compounds described in paragraphs

[0069] to

[0126] in Japanese Patent Application No. 2003-295212 may be cited.

[0071] In addition, the composition 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), halogenated alkyls (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). Among them, halogenated alkyls and ketones are preferred. In addition, two or more organic solvents may be used in combination.

[0072] In addition, the composition may include vertical orientation promoters such as vertical orientation promoters on the interface side of polarizer and vertical orientation promoters on the interface side of air, and various orientation promoters such as horizontal orientation promoters on the interface side of polarizer and horizontal orientation promoters on the interface side of air. In addition, the composition may include adhesion improvers, plasticizers, polymers, etc. in addition to the above-mentioned components.

[0073] The λ / 2 plate 3 may include an alignment film having the function of defining the alignment direction of the liquid crystal compound. The alignment film generally has a polymer as a main component. There are many documents describing the polymer material for the alignment film, and many commercial products are available. Among them, polyvinyl alcohol or polyimide or a derivative thereof is preferably used as the polymer material, and modified or unmodified polyvinyl alcohol is particularly preferably used as the polymer material.

[0074] For the alignment film that can be used in this embodiment, reference can be made to the modified polyvinyl alcohol described in page 43, line 24 to page 49, line 8 of International Publication No. 2001 / 88574 and paragraphs

[0071] to

[0095] of Japanese Patent No. 3907735.

[0075] The alignment film is usually subjected to a known alignment treatment, such as a rubbing treatment or a photo-alignment treatment by irradiating polarized light. However, from the viewpoint of the surface roughness of the alignment film, a photo-alignment treatment is preferred.

[0076] The thickness of the alignment film is not particularly limited, but is often 20 μm or less, preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, and even more preferably 0.01 to 1 μm.

[0077] The λ / 4 plate 4 provides a phase difference of π / 2 (=λ / 4) along the electric field vibration direction (polarization plane) of the incident light, and has the function of converting linearly polarized light of a certain wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light).

[0078] The in-plane retardation value at a specific wavelength λnm of the λ / 4 plate 4, i.e., Re(λ), satisfies Re(λ)=λ / 4. This equation can be achieved at any wavelength (e.g., 550nm) in the visible light region. Among them, the in-plane retardation value at a wavelength of 550nm, i.e., Re(550), preferably satisfies 100nm≤Re(550)≤160nm. In addition, it is more preferable to satisfy 110nm≤Re(550)≤150nm.

[0079] The retardation value in the thickness direction of the λ / 4 plate 4 measured at a wavelength of 550 nm, that is, Rth(550), is preferably −120 to 120 nm, and more preferably −80 to 80 nm.

[0080] The thickness of the λ / 4 plate 4 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and even more preferably 0.5 to 3 μm from the perspective of preventing wrinkles caused by the difference in dimensional changes between the front and back surfaces of the film when bent. It should be noted that the thickness of the λ / 4 plate 4 is the value obtained by measuring the thickness of any five points on the surface and taking the arithmetic average of these values.

[0081] The λ / 4 plate 4 preferably includes a layer obtained by curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, but the same materials as those cited as the material of the λ / 2 plate 3 can be used. Among them, a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disc-shaped liquid crystal compound having a polymerizable group by polymerization is preferred. In this case, it is not necessary to show liquid crystal properties after the layer is formed.

[0082] Among the layers contained in the circular polarizing plate 1, the layer obtained by curing the liquid crystal compound is preferably 1 or 2 layers other than the polarizer 2. In the case where 3 or more layers obtained by curing the liquid crystal compound are included other than the polarizer 2, since the number of layers that may cause wrinkles increases, it is considered that wrinkles are easily generated when bent.

[0083] The protective films 5 and 6 function as protective layers for protecting the polarizer 2, and the protective film 5 is disposed at least on the outer surface of the polarizer 2 (the surface opposite to the side facing the λ / 2 plate 3). In addition, the protective film 6 may be disposed on the inner surface of the polarizer 2 (the surface facing the λ / 2 plate 3).

[0084] As the material of the protective films 5 and 6, for example, a light-transmitting (preferably optically transparent) thermoplastic resin can be used, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.), a cellulose ester resin such as cellulose triacetate and cellulose diacetate, a polyester resin, a polycarbonate resin, a (meth)acrylic resin, a polystyrene resin, or a mixture or copolymer thereof. That is, the λ / 2 plate 3 can also serve as the protective films 5 and 6.

[0085] In addition, the protective films 5 and 6 may be protective films having optical functions such as phase difference films and brightness enhancement films. For example, a phase difference film having an arbitrary phase difference value can be produced by stretching a film containing the above-mentioned thermoplastic resin (uniaxial stretching or biaxial stretching, etc.) or forming a liquid crystal layer on the film.

[0086] Examples of the linear polyolefin-based resin include homopolymers of linear olefins such as polyethylene resins and polypropylene resins, and copolymers containing two or more linear olefins.

[0087] Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerization unit. Specific examples of cyclic polyolefin resins include, for example, ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically, random copolymers), and graft polymers obtained by modifying them with unsaturated carboxylic acids or their derivatives, and hydrogenated products thereof. Among them, as cyclic olefins, for example, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers can be appropriately used.

[0088] Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, copolymers thereof and resins in which a part of the hydroxyl groups is modified with other substituents may also be used. Among them, cellulose triacetate (triacetylcellulose: TAC) is particularly preferred.

[0089] The polyester resin is a resin other than the above-mentioned cellulose ester resin having an ester bond, and is generally a resin containing a polycondensate of a polyacid or its derivative and a polyol. As the polyacid or its derivative, a diacid or its derivative can be used, for example, terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl naphthalate, etc. can be mentioned. As the polyol, a diol can be used, for example, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, cyclohexanedimethanol, etc. can be mentioned.

[0090] Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, and polycyclohexane dimethyl naphthalate.

[0091] The polycarbonate resin includes a polymer in which monomer units are bonded via a carbonate group. The polycarbonate resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified, a copolymer polycarbonate, or the like.

[0092] (Meth)acrylic resins are resins whose main constituent monomers are compounds having (meth)acryloyl groups. Specific examples of (meth)acrylic resins include poly(meth)acrylates such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate-(meth)acrylic acid ester copolymers, methyl methacrylate-(meth)acrylic acid ester copolymers, methyl methacrylate-acrylate-(meth)acrylic acid copolymers, methyl (meth)acrylate-styrene copolymers (MS resins, etc.), and copolymers of methyl methacrylate and compounds having alicyclic hydrocarbon groups (e.g. methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate-norbornyl (meth)acrylate copolymers, etc.). Poly(meth)acrylic acid C such as polymethyl methacrylate is preferably used. 1－6 A polymer containing an alkyl ester (having 1 to 6 carbon atoms) as a main component. More preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

[0093] The thickness of the protective films 5 and 6 is preferably 10 to 200 μm, more preferably 10 to 100 μm, and further preferably 15 to 95 μm. The in-plane retardation value Re (550) of the protective films 5 and 6 is, for example, 0 to 10 nm, and the retardation value Rth (550) in the thickness direction is, for example, −80 to +80 nm.

[0094] The outer protective film 5 may be subjected to surface treatments such as hard coating, anti-reflection, anti-adhesion, and anti-glare treatments on the surface of the side opposite to the polarizer 2 as required. The thickness of the protective film 5 in this case is 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and further preferably 5 μm to 150 μm.

[0095] The inner protective film 6 is preferably optically isotropic. That is, the so-called "optically isotropic" means that the in-plane phase difference value Re (550) is 0nm to 10nm, and the phase difference value Rth (550) in the thickness direction is -10nm to +10nm. In this case, the thickness of the protective film 6 is preferably 20μm to 200μm, more preferably 30μm to 100μm, and further preferably 35μm to 95μm.

[0096] The adhesive layer 8 may be, for example, an active energy ray-curable adhesive (preferably an ultraviolet ray-curable adhesive) containing a curable compound that cures upon exposure to active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, or an aqueous adhesive obtained by dissolving or dispersing an adhesive component such as a polyvinyl alcohol-based resin in water. In the case of the circular polarizing plate 1, by laminating the λ / 2 plate 3 and the λ / 4 plate 4 via the adhesive layer 8, wrinkles can be prevented from being generated when the circular polarizing plate 1 is bent.

[0097] As the active energy ray-curable adhesive, an active energy ray-curable adhesive composition containing a cationically polymerizable curable compound and / or a radically polymerizable curable compound can be preferably used because it exhibits good adhesiveness. The active energy ray-curable adhesive may further contain a cationic polymerization initiator and / or a radical polymerization initiator for initiating a curing reaction of the curable compound.

[0098] Examples of cationically polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (compounds having one or more oxetane rings in the molecule), or combinations thereof. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, or combinations thereof. It is also possible to use cationically polymerizable curable compounds and radically polymerizable curable compounds in combination.

[0099] The active energy ray-curable adhesive may contain additives such as a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoamer, an antistatic agent, a leveling agent, and a solvent as necessary.

[0100] When the λ / 2 plate 3 and the λ / 4 plate 4 are bonded together using an active energy ray-curable adhesive, after the λ / 2 plate 3 and the λ / 4 plate 4 are laminated via the active energy ray-curable adhesive that becomes the adhesive layer 8, active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays are irradiated to cure the adhesive layer. Ultraviolet rays are suitable among them, and 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, metal halide lamps, etc. can be used as the light source in this case. When a water-based adhesive is used, after the λ / 2 plate 3 and the λ / 4 plate 4 are laminated via the water-based adhesive, they can be heated and dried.

[0101] The thickness of the adhesive layer 8 is preferably 0.5 to 5 μm, more preferably 0.5 to 3 μm.

[0102] The storage modulus of the adhesive layer 8 at a temperature of 30° C. is preferably 600 MPa to 4000 MPa, more preferably 700 MPa to 3500 MPa, further preferably 1000 MPa to 3000 MPa, and most preferably 1500 MPa to 3000 MPa. By bonding the λ / 2 plate 3 and the λ / 4 plate 4 together with a hard adhesive layer 8 having such a storage modulus, it is possible to further prevent wrinkles from being generated in the phase difference layer when it is bent.

[0103] Regarding the storage modulus of the adhesive layer 8 at a temperature of 30° C., when the storage modulus of the adhesive layer 8 of the circular polarizing plate 1 at a temperature of 30° C. can be directly measured by the following method, the measured value is adopted. On the other hand, when it is not possible to directly measure, an adhesive layer test piece is formed on a release paper under the same conditions (type of adhesive, curing conditions) as those for forming the adhesive layer 8, and the adhesive layer test piece is peeled off from the release paper and measured by the following method, and the value can be regarded as the same as the obtained storage modulus.

[0104] The storage elastic modulus of the adhesive layer 8 or the adhesive layer test piece can be measured using a commercially available dynamic viscoelasticity device, for example, DVA-220 manufactured by IT Instruments & Controls Co., Ltd.

[0105] The adhesive layer 8 can be any adhesive known in the art, as long as it has a degree of adhesion such that it does not peel off in a high temperature environment, a hot and humid environment, or an environment of repeated high and low temperatures to which the polarizing plate is exposed. Specifically, acrylic adhesives, silicone adhesives, rubber adhesives, etc. can be cited, and acrylic adhesives are particularly preferred from the perspectives of transparency, weather resistance, heat resistance, and processability.

[0106] If necessary, various additives such as tackifiers, plasticizers, glass fibers, glass beads, metal powders, fillers including other inorganic powders, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, antistatic agents, and silane coupling agents may be appropriately blended into the adhesive.

[0107] The adhesive layer 8 is usually formed by applying an adhesive solution to a release sheet and drying the adhesive. Application to the release sheet can be performed by, for example, roll coating such as reverse coating or gravure coating, spin coating, screen coating, injection coating, dip coating, spraying, etc. The release sheet provided with the adhesive layer can be utilized by a transfer method, etc.

[0108] The thickness of the adhesive layer 8 is usually about 3 to 100 μm, preferably 5 to 50 μm.

[0109] The circular polarizing plate 1 of this embodiment is used as Figure 2 The bendable display device 10 shown. Specific examples of the bendable display device 10 include organic EL display devices, liquid crystal display devices using circularly polarized light (typically, VA (Vertical Alignment) mode liquid crystal display devices), MEMS (Micro Electro Mechanical Systems) displays, etc. Among them, the circular polarizing plate 1 of this embodiment can be particularly suitably used in bendable organic EL display devices.

[0110] Specifically, the display device 10 of this embodiment is as follows Figure 2 As shown, the display panel 20 is bendable and the circular polarizing plate 1 is disposed on the visible side of the display panel 20. The circular polarizing plate 1 is attached to the visible side of the display panel 20 via the PSA layer 9 so that the polarizer 2 faces the visible side.

[0111] In the display device 10 of the present embodiment, external light is incident from the visible side of the display panel 20, thereby converting the light passing through the polarizer 2 into linearly polarized light. After the linearly polarized light passes through the λ / 2 plate 3 to change the direction of the linearly polarized light, it passes through the λ / 4 plate 4 to become circularly polarized light. The circularly polarized light is reflected by the display panel 20, thereby becoming circularly polarized light that is reversed relative to the incident light. When the circularly polarized light reflected by the display panel 20 passes through the λ / 4 plate 4 and the λ / 2 plate 3 again, it becomes linearly polarized light that is orthogonal to the incident light. Therefore, the linearly polarized light is blocked by the polarizer 2. As a result, the influence caused by the reflection of external light can be suppressed.

[0112] As an example of the display panel 20, for example, Figure 3 The organic EL element 200 shown. It should be noted that Figure 3 It is a cross-sectional view showing the structure of the organic EL element 200 .

[0113] Specifically, the organic EL element 200 includes a substrate 210, a first electrode 220, an organic EL layer 230, a second electrode 240, and a sealing layer 250 covering them. In addition, as required, the organic EL element 200 may include, for example, a planarization layer (not shown) on the substrate 210, or an insulating layer (not shown) between the first electrode 220 and the second electrode 240 for preventing short circuits.

[0114] The substrate 210 is made of a flexible material. If a flexible substrate 210 is used, the display device 10 can be bent at the above-mentioned radius of curvature. In addition, since the organic EL element 200 can be manufactured by a so-called roll-to-roll process, low-cost and mass production can be achieved. In addition, the substrate 210 is preferably made of a shielding material. Such a substrate 210 can protect the organic EL layer 230 from oxygen and moisture.

[0115] Specific materials of the substrate 210 having shielding properties and flexibility include, for example, thin glass imparted with flexibility, thermoplastic resin or thermosetting resin films imparted with shielding properties, alloys, metals, and the like.

[0116] Examples of thermoplastic resins or thermosetting resins include polyester resins, polyimide resins, epoxy resins, polyurethane resins, polystyrene resins, polyolefin resins, polyamide resins, polycarbonate resins, silicone resins, fluorine resins, and acrylonitrile-butadiene-styrene copolymer resins. Examples of alloys include stainless steel, 36 alloy, and 42 alloy. Examples of metals include copper, nickel, iron, aluminum, and titanium.

[0117] The thickness of the substrate 210 is preferably 5 μm to 500 μm, more preferably 5 μm to 300 μm, and further preferably 10 μm to 200 μm. With such a thickness, the display device 10 can be bent with the above-mentioned radius of curvature. In addition, the organic EL element 200 can be suitably used in a roll-to-roll process.

[0118] The first electrode 220 can function as an anode. In this case, as a material constituting the first electrode, a material having a large work function is preferred from the viewpoint of facilitating hole injection. Specific examples of such materials include transparent conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin oxide added with silicon oxide (ITSO), indium oxide containing tungsten oxide (IWO), indium zinc oxide containing tungsten oxide (IWZO), indium oxide containing titanium oxide (ITiO), indium tin oxide containing titanium oxide (ITTiO), indium tin oxide containing molybdenum (ITMO), and metals such as gold, silver, and platinum, and alloys thereof.

[0119] The organic EL layer 230 is a laminated body including various organic thin films. Specifically, the organic EL layer 230 includes: a hole injection layer 230a including a hole injecting organic material (e.g., a triphenylamine derivative) and provided to improve the hole injection efficiency from the anode; a hole transport layer 230b including, for example, copper phthalocyanine; a light emitting layer 230c including a light emitting organic substance (e.g., anthracene, bis[N-(1-naphthyl)-N-phenyl]benzidine, N,N'-diphenyl-N-N-di(1-naphthyl)-1,1'-(biphenyl)-4,4'-diamine (NPB)); an electron transport layer 230d including, for example, an 8-hydroxyquinoline aluminum complex; and an electron injection layer 230e including an electron injecting material (e.g., a perylene derivative, lithium fluoride) and provided to improve the electron injection efficiency from the cathode.

[0120] In addition, the organic EL layer 230 may also adopt any appropriate combination that can generate light by recombining electrons and holes in the light-emitting layer 230c. In order to transmit the emitted light as much as possible, the thickness of the organic EL layer 230 is preferably as thin as possible, specifically, 5nm to 200nm, more preferably about 10nm.

[0121] The second electrode 240 can function as a cathode. In this case, the material constituting the second electrode 240 is preferably a material with a small work function from the viewpoint of facilitating electron injection and thus improving luminous efficiency. Specific examples of such a material include aluminum, magnesium, and alloys thereof.

[0122] The sealing layer 250 is made of a material having excellent shielding properties and transparency. Examples of the material constituting the sealing layer 250 include epoxy resin and polyurea. Alternatively, the sealing layer 250 may be formed by applying epoxy resin (epoxy resin adhesive) and attaching a shielding sheet thereon.

[0123] The organic EL element 200 can be manufactured continuously using a roll-to-roll process. The organic EL element 200 can be manufactured, for example, in the order of the steps described in Japanese Patent Publication No. 2012-169236. The description of the publication is incorporated into this specification as a reference. In addition, the organic EL element 200 can be continuously stacked with the long circular polarizing plate 1 using a roll-to-roll process to continuously manufacture an organic EL display device.

[0124] The details of the bendable organic EL display device are described in, for example, Japanese Patent No. 4601463 or Japanese Patent No. 4707996. These descriptions are incorporated herein by reference.

[0125] It should be noted that, in the above-mentioned display panel 20, an example of a method using an organic EL element 200 is given, but it is not necessarily limited to this method. The display device 10 to which the present invention is applied can be, for example, a method having a display panel 20 including a liquid crystal display element and a circular polarization plate 1 arranged on the visible side of the display panel 20.

[0126] The display device 10 of this embodiment also includes an image Figure 4A to Figure 4D The bent state shown in the figure (the bent state is fixed). Figure 4A to Figure 4D It is a schematic diagram for explaining a curved state of the display device 10 .

[0127] Specifically, the display device 10 can be, for example, Figure 4A and Figure 4B In addition, from the perspective of maximizing the design and display screen, it can be bent in the middle as shown in the foldable type. Figure 4C and Figure 4D The ends are bent as shown.

[0128] In addition, the display device 10 is Figure 4A to Figure 4D As shown in the figure, the display device 10 may be bent in its length direction or in its width direction. That is, the display device 10 only needs to bend a specific portion (for example, a part or all of the four corners) in an oblique direction according to its use.

[0129] At least a portion of the display device 10 is preferably bent with a curvature radius (bending radius) of 10 mm or less, more preferably 8 mm or less, and further preferably 4 mm or less. The display device 10 of this embodiment reduces the change in the hue (color tone) of the reflected light in the state of being bent with such a very small curvature radius, and is not easy to generate wrinkles in the circular polarizing plate 1. In addition, the lower limit value of the bending radius is not particularly limited, and can be 0 mm or greater than 0 mm.

[0130] Reference Figure 5 (a) and (b) illustrate the relationship between the bending direction (the direction orthogonal to the bending start line L) of the display device 10 and the absorption axis direction of the polarizer 2, and the relationship between the slow axis direction of the λ / 2 plate 3 and the slow axis direction of the λ / 4 plate 4. It should be noted that: Figure 5 (a) and (b) are schematic diagrams for explaining the relationship between the bending direction of the display device 10 and the absorption axis direction of the polarizing plate 2, and the relationship between the slow axis direction of the λ / 2 plate 3 and the slow axis direction of the λ / 4 plate 4. Figure 5 In (a) and (b), the absorption axis direction of the polarizer 2 is indicated by a “dashed line”, the slow axis direction of the λ / 2 plate 3 is indicated by a “one-dot chain line”, and the slow axis direction of the λ / 4 plate 4 is indicated by a “solid line”.

[0131] The display device 10 is Figure 5 As shown in (a) and (b), the flat portion 10a has at least a straight bending start line L ( Figure 5 The curved portion 10b is curved in a direction (curving direction) perpendicular to the bending start line L (the double-dashed line shown in (a) and (b). In this case, the normal direction ( Figure 5 The display device 10 is observed in the Z-axis direction in (a) and (b). The bending direction of the display device 10 corresponds to the direction orthogonal to the straight bending start line L ( Figure 5 (a) and (b) in the Y-axis direction).

[0132] In the display device 10 of the present embodiment, the curvature direction of the display device 10 is set to -10° to 10° (0°) with the counterclockwise direction being positive relative to the slow axis direction (0°) of the λ / 4 plate 4. Figure 5 (a) is 0°) or 80°~100° ( Figure 5 The angle (in (b) is 90°), and is preferably set to a range of -5° to 5° or 85° to 95°, and more preferably set to 0° or 90°.

[0133] At this time, the slow axis direction of the λ / 2 plate 3 is set to form an angle α with respect to the absorption axis direction of the polarizer 2. That is, the circular polarizing plate 1 is arranged on the surface of the display panel 20 so that the slow axis direction of the λ / 2 plate 3 forms an angle α with respect to the absorption axis direction of the polarizer 2.

[0134] In addition, the slow axis direction of the λ / 4 plate 4 is set to form an angle β with respect to the absorption axis direction of the polarizer 2. That is, the circular polarizing plate 1 is arranged on the surface of the display panel 20 in such a manner that the slow axis direction of the λ / 4 plate 4 forms an angle β with respect to the absorption axis direction of the polarizer 2. It should be noted that both the angle α and the angle β are angles with the absorption axis of the polarizer 2 as a reference and with the counterclockwise rotation as positive. With respect to the absorption axis direction (0°) of the polarizer 2, the slow axis direction of the λ / 4 plate 4 is set to form an angle β in the range of -20° to 20° ( Figure 5 (a) and (b) are within the range of -15°.

[0135] Specifically, a preferred combination of angle α and angle β is described. Angle α is preferably -80° to -70°, more preferably -78° to -70°, and further preferably -76° to -70°. At this time, angle β is preferably -20° to -10°, more preferably -18° to -10°, and further preferably -16° to -10°.

[0136] The angle α is preferably 80° to 70°, more preferably 78° to 70°, and even more preferably 76° to 70°. In this case, the angle β is preferably 20° to 10°, more preferably 18° to 10°, and even more preferably 16° to 10°.

[0137] By adjusting the slow axis direction (angle α) of the λ / 2 plate 3 and the slow axis direction (angle β) of the λ / 4 plate 4 so as to be within such a range, it is possible to suppress color change due to bending.

[0138] In addition, the circularly polarizing plate 1 of the present embodiment preferably has no difference in hue between the reflected light obtained before and after bending and the color tone of the reflected light obtained after bending. Color Space Chromaticity coordinates Coordinate axis and That is, it is preferable to set the hue of the reflected light measured by the SCE method before and after bending so as not to cross Chromaticity coordinates Axis and does not cross Thus, even if the hue of the reflected light obtained before and after bending changes, the change in hue can be made inconspicuous. For example, by adjusting the hue of the polarizing plate or adjusting the phase difference value of the phase difference layer, it can be controlled not to cross each coordinate axis.

[0139] In addition, adjusting the wavelength dispersion of the phase difference film is also effective in controlling the color tone. For example, when the phase difference value of the circular polarizing plate 1 is increased, Value and The value becomes lower. When the phase difference value of the circular polarization plate 1 is reduced, Value and The value becomes higher.

[0140] It should be noted that before and after the bending begins, even if Value and If at least one of the values ​​is 0 and the sign of the other value does not change, it is considered that the sign does not change before and after the bend. That is, in this case, it is considered that there is no crossing. Coordinate axis and The bending method for this evaluation can be in accordance with the method described in the examples described later.

[0141] The reflection color tone can be measured using CM-2600d (spectrophotometer manufactured by Konica Minolta Co., Ltd.) In accordance with "JIS Z 8722: 2009", the setting conditions can be set as follows.

[0142] ・Light source: D65 light source

[0143] ・Measurement diameter: 8mmφ

[0144] ・Field of view: 2°

[0145] ・Geometric conditions: Geometric conditions c

[0146] It should be noted that the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0147] For example, a touch sensor may be provided as an input tool of the display device 10. Figure 6 As shown in the display device 30, it is assumed that the display device 10 has a structure that further includes a touch sensor 40 and a window film 50. It should be noted that Figure 6 1 is a cross-sectional view showing another configuration example of a bendable display device 30 including the circular polarization plate 1 .

[0148] exist Figure 6 In the display device 30 shown, the touch sensor 40 is preferably arranged on the side of the circular polarizing plate 1 opposite to the display panel 20, and the window film 50 is preferably arranged on the opposite side of the circular polarizing plate 1 opposite to the display panel 20. If the circular polarizing plate 1 is present on the visible side of the touch sensor 40, the pattern of the touch sensor 40 is less likely to be observed, and the visibility of the image displayed on the display panel 20 is improved, which is preferred.

[0149] thus, Figure 6 The display device 30 shown has a structure in which a display panel 20, a touch sensor 40, a circular polarizing plate 1, and a window film 50 are sequentially stacked using an adhesive or a bonding agent. In addition, a light shielding pattern described later may be provided on at least one surface of any layer of the window film 50, the circular polarizing plate 1, and the touch sensor 40.

[0150] It should be noted that the stacking order of the touch sensor 40 and the window film 50 is not necessarily limited to the above-mentioned structure, and for example, the display panel 20 , the circular polarization plate 1 , the touch sensor 40 , and the window film 50 may be stacked in this order.

[0151] The window film 50 may be the protective film 5 constituting the above-mentioned circular polarizing plate 1 , or may be a structure in which the window film 50 also serves as the protective film 5 of the circular polarizing plate 1 .

[0152] In the present invention, although not shown in the drawings, in addition to the configuration of the display device 10 described above, a touch sensor 40 may be further provided on the side of the circular polarization plate 1 opposite to the side facing the display panel 20 .

[0153] (Window Film)

[0154] The window film 50 is disposed on the visible side of the bendable display device 30 and serves as a protective layer to protect other components from external impact or environmental changes such as temperature and humidity. In the past, glass was used as such a protective layer, but the window film 50 of the bendable display device 30 is not as rigid and hard as glass, but has the property of being bendable.

[0155] The window film 50 includes a bendable transparent base material 51 and a hard coating layer 52 provided on at least one surface of the transparent base material 51 . Figure 6 In the display device 30 shown, the hard coating layer 52 constituting the window film 50 is provided on the surface of the transparent substrate 51 on the opposite side to the circular polarizing plate 1. The hard coating layer 52 becomes the outermost layer of the display device 30 and contacts the external gas (air). In addition, the hard coating layer 52 may also be provided on the surface of the transparent substrate 51 on the side of the circular polarizing plate 1. In addition, the hard coating layer 52 may be provided on only one side of the transparent substrate 51, or may be provided on both sides of the transparent substrate 51.

[0156] (Transparent substrate)

[0157] The visible light transmittance of the transparent substrate 51 is 70% or more, preferably 80% or more. The thickness of the transparent substrate 51 is 5 to 200 μm, preferably 20 to 100 μm.

[0158] As long as the transparent substrate 51 is a polymer film with transparency, any type of film can be used. Specifically, polyolefins such as polyethylene, polypropylene, polymethylpentene, norbornene, or cycloolefin derivatives having units of monomers containing cycloolefins, (modified) celluloses such as diacetyl cellulose, triacetyl cellulose, and propionyl cellulose, acrylic acids such as methyl methacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile / butadiene / styrene copolymers, acrylonitrile / styrene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyesters such as polyarylates, polyamides such as nylon, polyimides, polyamide-imides, polyetherimides, polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, epoxy resins, etc. can be cited. In addition, an unstretched film, a uniaxially stretched film, or a biaxially stretched film thereof may be used.

[0159] These polymers may be used alone or in combination of two or more in the transparent substrate 51. Among the above-mentioned transparent substrates 51, polyamide films, polyamideimide films or polyimide films, polyester films, olefin films, acrylic films, and cellulose films having excellent transparency and heat resistance are preferably used.

[0160] It is also preferred to disperse inorganic particles such as silicon dioxide, organic microparticles, rubber particles, etc. in the polymer film. In addition, it may contain colorants such as pigments and dyes, fluorescent whitening agents, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents and other compounding agents.

[0161] (Hard coating)

[0162] The thickness of the hard coating layer 52 is not particularly limited, but is preferably 2 to 100 μm, for example. If the thickness of the hard coating layer 52 is less than 2 μm, it is difficult to ensure sufficient scratch resistance. On the other hand, if the thickness of the hard coating layer 52 is greater than 100 μm, the bending resistance is reduced, and there is a situation where the problem of curling caused by curing shrinkage occurs. That is, if the thickness of the hard coating layer 52 is more than 2 μm, it is easy to ensure sufficient scratch resistance. In addition, if the thickness of the hard coating layer 52 is less than 100 μm, it is not easy to produce problems such as reduced bending resistance and curling caused by curing shrinkage.

[0163] The hard coating layer 52 can be formed by curing a hard coating composition including a reactive material that forms a crosslinked structure by irradiation with active energy rays or heat energy, but a hard coating layer that is cured by irradiation with active energy rays is preferred.

[0164] The so-called active energy ray is defined as an energy ray that can decompose a compound that generates active species to generate active species. Examples of active energy ray include visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron beams. Among them, ultraviolet rays are particularly preferred.

[0165] The hard coating composition contains a polymer of at least one of a free radical polymerizable compound and a cationic polymerizable compound. The so-called free radical polymerizable compound is a compound having a free radical polymerizable group. The free radical polymerizable group possessed by the free radical polymerizable compound can be any functional group capable of producing a free radical polymerization reaction, and a group containing a carbon-carbon unsaturated double bond can be cited. Specifically, vinyl, (meth)acryloyl, etc. can be cited.

[0166] It should be noted that, when the free radical polymerizable compound has two or more free radical polymerizable groups, these free radical polymerizable groups may be the same or different. For the number of free radical polymerizable groups in one molecule of the free radical polymerizable compound, it is preferably two or more from the aspect of improving the hardness of the hard coating layer 52.

[0167] As the radical polymerizable compound, a compound having a (meth)acryloyl group is preferred from the viewpoint of high reactivity, and compounds called multifunctional acrylate monomers having 2 to 6 (meth)acryloyl groups in one molecule, and oligomers having a molecular weight of several hundreds to several thousands and having several (meth)acryloyl groups in the molecule, called epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate can be preferably used. Preferably, the compound contains one or more selected from epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

[0168] The so-called cationic polymerizable compound is a compound having a cationic polymerizable group such as an epoxy group, an oxetane group, a vinyl ether group, etc. As for the number of cationic polymerizable groups in one molecule of the cationic polymerizable compound, from the aspect of improving the hardness of the hard coating layer 52, it is preferably 2 or more, and more preferably 3 or more. In addition, as the cationic polymerizable compound, it is preferred that the compound has at least one of an epoxy group and an oxetane group as a cationic polymerizable group.

[0169] From the aspect of small shrinkage associated with the polymerization reaction, cyclic ether groups such as epoxy groups and oxetane groups are preferred. In addition, compounds having epoxy groups in cyclic ether groups have the following advantages, that is, compounds with various structures are easy to obtain, the durability of the obtained hard coating layer 52 is not adversely affected, and the compatibility with free radical polymerizable compounds is also easy to control.

[0170] In addition, the oxetane group in the cyclic ether group has the following advantages, namely, the degree of polymerization is easily increased compared with the epoxy group, and it is low in toxicity, which accelerates the network formation rate of the obtained hard coating 52 obtained by the cationic polymerizable compound, and no unreacted monomers will remain in the film in the area mixed with the free radical polymerizable compound, but an independent network will be formed.

[0171] Examples of the cationic polymerizable compound having an epoxy group include polyglycidyl ethers of polyols having an alicyclic ring, or alicyclic epoxy resins obtained by epoxidizing a compound containing a cyclohexene ring or a cyclopentene ring with an appropriate oxidant such as hydrogen peroxide or a peracid; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, and homopolymers and copolymers of glycidyl (meth)acrylate; glycidyl ethers produced by reacting bisphenols such as bisphenol A, bisphenol F, or hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts or caprolactone adducts with epichlorohydrin, and linear novolac epoxy resins, and examples thereof include glycidyl ether-type epoxy resins derived from bisphenols.

[0172] In the hard coating composition, a polymerization initiator may be further included. As the polymerization initiator, free radical polymerization initiator, cationic polymerization initiator, free radical and cationic polymerization initiator, etc. can be cited, and it can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating, and free radicals or cations are generated to promote free radical polymerization and cationic polymerization.

[0173] The radical polymerization initiator may be any one that can release a substance that initiates radical polymerization by at least one of irradiation with active energy rays and heating. For example, examples of thermal radical polymerization initiators include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

[0174] As the active energy ray radical polymerization initiator, there are Type 1 radical polymerization initiators that generate radicals by decomposition of molecules and Type 2 radical polymerization initiators that generate radicals by hydrogen abstraction reaction in the presence of tertiary amines. They can be used alone or in combination.

[0175] The cationic polymerization initiator may be any one of active energy ray irradiation and heating to release a substance that initiates cationic polymerization. As the cationic polymerization initiator, aromatic iodonium salts, aromatic sulfonium salts, cyclopentadienyl iron (II) complexes, etc. may be used. Depending on the difference in structure, they may initiate cationic polymerization by active energy ray irradiation or heating, or by either one of them.

[0176] The polymerization initiator may be contained in an amount of 0.1 to 10% by weight relative to the entire hard coating composition (100% by weight). If the content of the polymerization initiator is less than 0.1% by weight, curing cannot be fully promoted, and it is difficult to achieve the mechanical properties and adhesion of the final coating film. On the other hand, if the content of the polymerization initiator is greater than 10% by weight, there is a situation where poor adhesion, cracking, and curling due to curing shrinkage occur. That is, if the content of the polymerization initiator is more than 0.1% by weight, curing can be fully promoted, and it is easy to achieve the mechanical properties and adhesion of the final coating film. On the other hand, if the content of the polymerization initiator is less than 10% by weight, poor adhesion, cracking, and curling due to curing shrinkage are not easy to occur.

[0177] The hard coating composition may further include one or more selected from solvents and additives. As long as the solvent is capable of dissolving or dispersing the polymerizable compound and the polymerization initiator and is a solvent known as a solvent for the hard coating composition in the technical field, it can be used without limitation. The additive may further include inorganic particles, a leveling agent, a stabilizer, a surfactant, an antistatic agent, a lubricant, an antifouling agent, and the like.

[0178] (Touch Sensor)

[0179] As the touch sensor 40 , various types of touch sensors such as a resistive film type, a surface acoustic wave type, an infrared type, an electromagnetic induction type, and an electrostatic capacitance type have been proposed, and any type may be used. Among them, the electrostatic capacitance type is preferable.

[0180] The capacitive touch sensor 40 can be divided into an active area and an inactive area located outside the active area. The active area corresponds to the area (display part) of the display panel 20 where the screen is displayed and is the area where the user's touch is sensed. On the other hand, the inactive area corresponds to the area (non-display part) of the display panel 20 where the screen is not displayed.

[0181] The touch sensor 40 may include: a substrate having a flexible property, a sensing pattern formed in an active area of ​​the substrate, and sensing lines formed in an inactive area of ​​the substrate and used to connect to an external driving circuit via the sensing pattern and a pad portion. As a substrate constituting the touch sensor 40, a substrate containing a polymer material is generally used.

[0182] As the substrate having flexibility, the same material as the transparent base material 51 of the window film 50 can be used. From the viewpoint of suppressing cracks, the substrate of the touch sensor 40 preferably has a toughness of 2000 MPa% or more, and more preferably has a toughness of 2000 to 30000 MPa%.

[0183] It should be noted that the toughness of the substrate is defined as follows: the stress (MPa) (vertical axis) is plotted against the strain (%) (horizontal axis) obtained by the tensile test of the polymer material constituting the substrate, and is defined as the lower area of ​​the curve until the breaking point in the obtained stress-strain curve. From the viewpoint of suppressing cracks in the touch sensor 40, it is desirable that the substrate constituting the touch sensor 40 has toughness within the above range.

[0184] The sensing pattern may include a first pattern formed along a first direction and a second pattern formed along a second direction. The first pattern and the second pattern are arranged in different directions from each other. The first pattern and the second pattern are formed on the same layer, and each pattern must be electrically connected in order to sense the touched location.

[0185] The first pattern is a structure in which each unit pattern is connected to each other via a connector. On the other hand, the second pattern is a structure in which each unit pattern is separated from each other in an island shape. Therefore, in order to electrically connect the second pattern, an additional bridge electrode is required.

[0186] The sensing pattern can be made of known transparent electrode raw materials. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly (3,4-ethylenedioxythiophene)), carbon nanotubes (CNT), graphene, metal wires, etc. can be used alone or in combination of two or more. Among them, ITO is preferably used.

[0187] The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, terenum, chromium, etc. These metals may be used alone or in combination of two or more.

[0188] The bridge electrode may be formed on the upper part of the sensing pattern via the insulating layer. Alternatively, the bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon.

[0189] The bridge electrode may be formed of the same material as the sensing pattern, for example, may be formed of metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more thereof.

[0190] Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer can be formed only between the contact of the first pattern and the bridge electrode, or it can be formed as a layer covering the sensing pattern. In the latter case, the bridge electrode can be connected to the second pattern via a contact hole formed in the insulating layer.

[0191] As a method for properly compensating for the difference in transmittance between a patterned area where a pattern is formed and a non-patterned area where a pattern is not formed, specifically, as a method for properly compensating for the difference in light transmittance induced by the difference in refractive index between these areas, the touch sensor 40 may further include an optical adjustment layer between the substrate and the electrode.

[0192] The optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical adjustment layer may be formed by coating a photocurable composition including a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. Inorganic particles may be used to increase the refractive index of the optical adjustment layer.

[0193] The photocurable organic binder may include, for example, a copolymer of monomers such as acrylate monomers, styrene monomers, carboxylic acid monomers, etc. The photocurable organic binder may include, for example, a copolymer of different repeating units such as repeating units containing epoxy groups, acrylate repeating units, and carboxylic acid repeating units.

[0194] The inorganic particles may include, for example, zirconium dioxide particles, titanium dioxide particles, aluminum oxide particles, etc. The photocurable composition may further include various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[0195] (Adhesive)

[0196] As the adhesive, water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, moisture-curing adhesives, heat-curing adhesives, anaerobic-curing adhesives, active energy ray-curing adhesives, curing agent mixed adhesives, hot melt adhesives, pressure-sensitive adhesives (adhesives), rewetting adhesives, etc. can be used. Among them, water-based adhesives, active energy ray-curing adhesives, etc. are commonly used. In addition, as water-based adhesives and active energy ray-curing adhesives, the above-mentioned adhesives can be used.

[0197] (Adhesive)

[0198] The adhesive can be classified into acrylic adhesives, urethane adhesives, rubber adhesives, silicone adhesives, etc. according to the main polymer, and any type can be used. In the adhesive, in addition to the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, etc. can be added.

[0199] The adhesive layer is formed by dissolving and dispersing the components constituting the adhesive in a solvent to obtain an adhesive composition, applying the adhesive composition on a substrate and then drying it. The adhesive layer may be formed directly or may be formed separately by transfer printing on the substrate.

[0200] It is also preferred to use a release film to cover the adhesive surface before bonding. The thickness of the adhesive layer when using an active energy ray-curable adhesive is 0.1 to 500 μm, preferably 1 to 300 μm. When using multiple layers of adhesive, the thickness and type of each layer may be the same or different.

[0201] (Shading pattern)

[0202] The light shielding pattern may be applied as at least a part of the frame or housing of the flexible display device 30. The light shielding pattern hides the wiring arranged at the edge of the flexible display device 30, making it difficult to be observed, thereby improving the visibility of the image.

[0203] The shading pattern may be in the form of a single layer or multiple layers. The color of the shading pattern is not particularly limited, and there are various colors such as black, white, and metallic colors. The shading pattern may be formed by a pigment for presenting color, and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, and silicone. In addition, these may be used alone or in a mixture of two or more.

[0204] The light shielding pattern can be formed by various methods such as printing, photolithography, inkjet, etc. The thickness of the light shielding pattern is 1 μm to 100 μm, preferably 2 μm to 50 μm. In addition, it is also preferred to give a shape such as an inclination in the thickness direction of the light shielding pattern.

[0205] [Example]

[0206] The effects of the present invention will be further described below using examples. It should be noted that the present invention is not limited to the following examples, and can be implemented with appropriate changes within the scope of the present invention.

[0207] [Example 1]

[0208] (Production of polarizing film)

[0209] After dyeing a long strip of polyvinyl alcohol film in an aqueous solution containing iodine, the film was uniaxially stretched to 6 times between rollers with different speed ratios in an aqueous solution containing boric acid to obtain a long strip of polarizer having an absorption axis in the length direction. After the long strip of polarizer was stretched, it was rolled up to form a roll. The chromaticity of the polarizer is, orthogonal a = 0.04, orthogonal b = -0.11, the visibility-corrected polarization degree of the polarizer is about 99.995%, and the visibility-corrected single transmittance of the polarizer is 42.7%.

[0210] (Protective film)

[0211] As the protective film, a long strip of triacetyl cellulose film (thickness 40 μm, manufactured by Konica Minolta, trade name: KC4UYW) was used. The protective film was prepared in the form of a roll. It should be noted that the in-plane phase difference value Re (550) of the protective film was 5 nm, and the phase difference value Rth (550) in the thickness direction was 45 nm.

[0212] (λ / 2 plate)

[0213] As the λ / 2 plate, a film including a layer obtained by curing a liquid crystal compound and an alignment film is used.

[0214] (λ / 4 plate)

[0215] As the λ / 4 plate, a film including a layer obtained by curing a liquid crystal compound and an alignment film is used.

[0216] (UV-curing adhesive)

[0217] The following components were mixed and degassed to prepare an ultraviolet curing adhesive.

[0218] 3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name: CEL2021P, manufactured by Daicel Corporation): 70 parts by mass

[0219] Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by Nagese ChemteX Co., Ltd.): 20 parts by mass

[0220] 2-Ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagese ChemteX Co., Ltd.): 10 parts by mass

[0221] Cationic polymerization initiator (trade name: CPI-100, manufactured by San-Apro Co., Ltd.): solid content: 2.25 parts by mass (mixed in the form of a 50% propylene carbonate solution.)

[0222] 1,4-diethoxynaphthalene: 2 parts by mass

[0223] (Fabrication of circular polarizing plate)

[0224] The polarizer, protective film, λ / 2 plate and λ / 4 plate were cut into 200 mm × 300 mm pieces respectively, and the protective film was bonded to both sides of the polarizer via a polyvinyl alcohol adhesive. The λ / 2 plate and the λ / 4 plate were bonded via the above-mentioned ultraviolet curing UV adhesive (adhesive layer). In addition, the λ / 2 plate and the protective film were bonded via an acrylic adhesive layer (PSA layer). The acrylic adhesive layer (PSA layer) with a release film was bonded to the λ / 4 plate.

[0225] When a λ / 2 plate is attached, the slow axis is arranged so that it forms an angle α of -75° with respect to the absorption axis of the polarizer. When a λ / 4 plate is attached, the slow axis is arranged so that it forms an angle β of -15° with respect to the absorption axis of the polarizer. In addition, the absorption axis of the polarizer is arranged so that it is parallel to the longitudinal direction.

[0226] As described above, a circular polarizing plate was produced by sequentially laminating a protective film, a polarizing plate, a protective film, a PSA layer, a λ / 2 plate, a UV adhesive layer, a λ / 4 plate, and a PSA layer. The produced circular polarizing plate was then cut into a size of 20 mm×80 mm.

[0227] (Preparation of samples for evaluation)

[0228] After removing the release film from the circularly polarizing plate of Example 1, the adhesive surface was attached to the matte surface of an aluminum foil (manufactured by UACJ Co., Ltd., trade name “MYFOIL (registered trademark)”) to obtain an evaluation sample.

[0229] As a result, something like Figure 5 As shown in (a), the slow axis of the λ / 2 plate forms an angle α of -75° relative to the absorption axis direction of the polarizer. The slow axis of the λ / 4 plate forms an angle β of -15° relative to the absorption axis direction of the polarizer. The bending direction of the circular polarizing plate forms an angle of 0° relative to the slow axis direction of the λ / 4 plate. The bending start line L of the circular polarizing plate forms 75° relative to the absorption axis direction of the polarizer. By operating as described above, an evaluation sample is obtained. For the obtained evaluation sample, an evaluation test of color change and wrinkle generation was carried out in a state where the bending state was eliminated after bending (flat state).

[0230] (Measurement of storage modulus of adhesive layer test piece at 30°C)

[0231] First, a UV-curable adhesive for bonding a λ / 2 plate to a λ / 4 plate is applied to one side of a 50 μm thick cyclic polyolefin resin film using a coater (rod coater, manufactured by Daiichi Rika Co., Ltd.), and a 50 μm thick cyclic polyolefin resin film is laminated on the coated surface.

[0232] Then, the H-type lamp manufactured by Fusion UV Systems was used to obtain a cumulative light intensity of 1500 mJ / cm 2 The adhesive layer was cured by irradiating with ultraviolet light (UVB). The thickness of the adhesive layer was 30 μm. The adhesive layer was cut into a size of 5 mm×30 mm, and the cyclic polyolefin resin films on both sides were peeled off to obtain a cured film of the adhesive.

[0233] The cured film was held with a 2 cm clamp interval using a dynamic viscoelasticity measuring apparatus "DVA-220" manufactured by IT Instruments and Controls Co., Ltd., with its long side in the stretching direction, and the frequency of stretching and shrinking was set to 10 Hz, and the measuring temperature was set to 30° C. The storage modulus at a temperature of 30° C. was determined. The storage modulus of the adhesive layer test piece at a temperature of 30° C. was 2060 MPa.

[0234] (Evaluation test)

[0235] While pushing a core rod with a diameter of 5 mm, bend the evaluation sample along the outer circumference of the core rod in such a way that the circular polarizing plate is on the outside (OUT) relative to the aluminum foil, so that the bending direction of the display device 10 is at an angle of 0° relative to the slow axis direction (0°) of the λ / 4 plate. Thereafter, the circular polarizing plate is visually observed after bending, and the circular polarizing plate with less color change is evaluated as "A", and the circular polarizing plate with greater color change is evaluated as "B". In addition, the circular polarizing plate with fewer wrinkles is evaluated as "A", and the circular polarizing plate with more wrinkles is evaluated as "B". The evaluation results are shown in Table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0236] [Example 2]

[0237] In Example 2, the same evaluation sample as in Example 1 was prepared. Thereafter, the evaluation sample was bent along the outer peripheral surface of the core rod so that the circular polarizing plate was on the inside (IN) relative to the aluminum foil. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the hue of the reflected light obtained before and after bending was not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0238] [Example 3]

[0239] In Example 3, Figure 5 (b) As shown in the example, the bending direction of the circular polarizing plate forms an angle of 90° with respect to the slow axis direction of the λ / 4 plate, and the bending start line L of the circular polarizing plate forms an angle of -15° with respect to the absorption axis direction of the polarizer. The same evaluation sample as in Example 1 was prepared. Thereafter, the evaluation sample was bent under the same conditions as in Example 1. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the hue of the reflected light obtained before and after bending was not sandwiched. Chromaticity coordinates Coordinate axis and The axes change sign.

[0240] [Example 4]

[0241] In Example 4, the same evaluation sample as in Example 3 was prepared. Thereafter, the evaluation sample was bent along the outer peripheral surface of the core rod so that the circular polarizing plate was on the inner side (IN) relative to the aluminum foil. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color tone of the reflected light obtained before and after bending was not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0242] [Comparative Example 1]

[0243] In Comparative Example 1, the same evaluation sample as in Example 1 was prepared except that the bending direction of the circular polarizing plate formed an angle of 60° with respect to the slow axis direction of the λ / 4 plate and the bending start line L of the circular polarizing plate formed an angle of -45° with respect to the absorption axis direction of the polarizer. Thereafter, the evaluation sample was bent under the same conditions as in Example 1. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the hue of the reflected light obtained before and after bending was not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0244] [Comparative Example 2]

[0245] In Comparative Example 2, the bending direction of the circular polarizing plate forms an angle of -30° with respect to the slow axis direction of the λ / 4 plate, and the bending start line L of the circular polarizing plate is formed at 45° in the absorption axis direction of the polarizer. The same evaluation sample as in Example 1 was prepared. Thereafter, the evaluation sample was bent under the same conditions as in Example 1. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the hue of the reflected light obtained before and after bending was not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0246] [Comparative Example 3]

[0247] In Comparative Example 3, the same evaluation sample as in Comparative Example 1 was prepared except that the λ / 2 plate and the λ / 4 plate were bonded together via an adhesive layer. Thereafter, the evaluation sample was bent under the same conditions as in Example 1. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color tone of the reflected light obtained before and after bending was not sandwiched. Chromaticity coordinates Coordinate axis and The axes change sign.

[0248] [Comparative Example 4]

[0249] In Comparative Example 4, the same evaluation sample as in Comparative Example 2 was prepared except that the λ / 2 plate and the λ / 4 plate were bonded together via an adhesive layer. Thereafter, the evaluation sample was bent under the same conditions as in Example 1. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color tone of the reflected light obtained before and after bending was not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0250] [Comparative Example 5]

[0251] In Comparative Example 5, the same evaluation sample as in Comparative Example 1 was prepared. Thereafter, the evaluation sample was bent along the outer peripheral surface of the core rod so that the circular polarizing plate was on the inner side (IN) relative to the aluminum foil. Thereafter, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color tone of the reflected light obtained before and after bending was not sandwiched by Chromaticity coordinates Coordinate axis and The axes change sign.

[0252]

[0253] [evaluate]

[0254] As is clear from Table 1, Examples 1 to 4 of the present invention provide good results in terms of the change in hue (color tone) of reflected light at the curved portion and the presence or absence of wrinkles, as compared to Comparative Examples 1 to 5.

[0255] Explanation of symbols

[0256] 1 circular polarizing plate, 2 polarizing plate, RF phase difference layer, 3 λ / 2 plate (1 / 2 wavelength plate layer), 4 λ / 4 plate (1 / 4 wavelength plate), 5, 6 protective film (protective layer), 7 PSA layer (adhesive layer), 8 adhesive layer or adhesive layer, 9 PSA layer (adhesive layer), 10 display device, 20 display panel, 30 display device, 40 touch sensor, 50 window film, 200 organic EL element, 210 substrate, 220 first electrode, 230 organic EL layer, 240 second electrode, 250 sealing layer.

Claims

1. A circular polarizing plate, characterized in that: It is a circular polarizing plate used in a bendable display device. It comprises a polarizing plate and a phase difference layer arranged on one side of the polarizing plate. The visibility correction single transmittance of the polarizing plate is 42% or more, The phase difference layer includes a 1 / 2 wavelength plate and a 1 / 4 wavelength plate, The half wavelength plate and the quarter wavelength plate each include a layer obtained by curing a liquid crystal compound, the half wavelength plate and the quarter wavelength plate are bonded to each other via an adhesive layer, and the adhesive layer uses a water-based adhesive or an active energy ray-curable adhesive as an adhesive, The slow axis direction of the 1 / 4 wavelength plate is in the range of -20° to 20° counterclockwise from the absorption axis direction of the polarizer, and the bending direction of the display device is set to the range of 80° to 100° or -10° to 10° relative to the slow axis direction of the 1 / 4 wavelength plate.

2. The circular polarizing plate according to claim 1, wherein The half-wavelength plate and the quarter-wavelength plate are bonded to each other via an adhesive layer.

3. The circular polarizing plate according to claim 1 or 2, characterized in that: The display device is an organic electroluminescent display device.

4. The circular polarizing plate according to claim 1 or 2, characterized in that: The color tone of the reflected light obtained before and after bending is not sandwiched Chromaticity coordinates Coordinate axis and The axes change sign.

5. The circular polarizing plate according to claim 3, characterized in that: The color tone of the reflected light obtained before and after bending is not sandwiched Chromaticity coordinates Coordinate axis and The axes change sign. 6 . A bendable display device comprising the circularly polarizing plate according to claim 1 , and a bendable display panel.

7. The bendable display device according to claim 6, characterized in that: have: a touch sensor disposed on a side of the circular polarization plate opposite to the display panel, and A window film is disposed on the side of the circular polarizing plate opposite to the side facing the display panel.

8. The bendable display device according to claim 6, characterized in that: A touch sensor is provided, and the touch sensor is arranged on the side of the circular polarization plate opposite to the side facing the display panel.

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