KR20200086666A - Circular polarizer and display device - Google Patents

Abstract

The present invention is a circular polarizing plate (1) used in a bendable display device, comprising a polarizer (2) and a retardation layer (RF) disposed on one side of the polarizer (2), the visibility correction unit of the polarizer (2) The transmittance is 42% or more, and the retardation layer (RF) includes a half wave plate 3 and a quarter wave plate 4, and a half wave plate 3 and a quarter wave plate 4 ) Each includes a layer in which the liquid crystal compound is cured, and the slow axis direction of the quarter wave plate 4 is positively counterclockwise from the absorption axis direction of the polarizer 2 in the range of -20° to 20°. In addition, the circular polarizing plate 1, in which the bending direction of the display device is set in the range of 80° to 100° or -10° to 10° with respect to the slow axis direction of the quarter wave plate 4 to provide.

Description

Circular polarizer and display device

The present invention relates to a circular polarizing plate. Further, the present invention relates to a bendable display device having the circular polarizing plate.

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 hereby incorporated by reference. .

Background Art Conventionally, circular polarizing plates have been used to suppress adverse effects of external light reflection in display devices. On the other hand, in recent years, there is a strong demand for a flexible (flexible) display device typified by organic electroluminescence (EL) display devices. In addition, it is desired to realize not only a simple flexible display device, but also a flexible display with a very small radius of curvature.

However, when the organic EL display device is bent with a very small radius of curvature, a large force (tensile force on the outside of the bent portion and compressive force on the inside of the bent portion) is applied to the phase difference layer in the circularly polarizing plate, so the phase difference of the bent portion is changed. There is a problem of discarding.

Therefore, with respect to this problem, in Patent Document 1 below, a phase difference film including a 1/2 wavelength (λ/2) plate and a 1/4 wavelength (λ/4) plate is provided, and the λ/2 plate and λ/ A circular polarizing plate is proposed in which four plates each contain a liquid crystal compound and the slow axis direction of the retardation film is adjusted to define an angle of 75 to 105 degrees with respect to the bending direction of the display device.

Patent Document 1: International Publication No. 2016/158300

However, in the above-mentioned bendable display device, further improvement is required regarding its visibility. In addition, it is desired to reduce a change in color (color) of reflected light in a bent portion when the display device is bent.

For this reason, in a circular polarizing plate applied to a bendable display device, it is necessary to follow the curved portion of the display device. In addition, it is also desired to make wrinkles less likely to occur before and after bending of the circular polarizing plate.

The present invention has been proposed in view of such conventional circumstances, and aims to provide a circular polarizing plate which is less likely to cause wrinkles due to bending while reducing color changes due to bending, and a flexible display device having the circular polarizing plate. do.

As a means for solving the above problems, according to an aspect of the present invention, as a circular polarizing plate used in a bendable display device, a polarizer, a phase difference layer disposed on one side of the polarizer, and the visibility of the polarizer are corrected. Silver is more than 42%, the retardation layer includes a half wave plate and a quarter wave plate, the half wave plate and the quarter wave plate each comprises a layer cured by a liquid crystal compound, The direction of the slow axis of the quarter wave plate is in the range of -20° to 20° with a positive counterclockwise direction from the direction of the absorption axis of the polarizer. A circular polarizing plate is provided in which the bending direction of the display device is set in the range of 80° to 100° or -10° to 10° with respect to the axial direction.

Further, in the circularly polarizing plate, a configuration in which the 1/2 wavelength plate and the 1/4 wavelength plate are adhered through an adhesive layer may be used.

In addition, in the circularly polarizing plate, the display device may be an organic electroluminescent display device.

Further, in the circularly polarizing plate, a configuration in which the color of the reflected light obtained before and after the bending may not be changed with the a ^* coordinate axis and the b ^* coordinate axis in a ^* b ^* chromaticity coordinates interposed therebetween.

Further, according to an aspect of the present invention, there is provided a bendable display device including any one of the circular polarizing plates and a bendable display panel.

In addition, the display device may include a structure in which a touch sensor disposed on a side opposite to the display panel of the circularly polarizing plate and a window film disposed on a side opposite to the side facing the display panel of the circularly polarizing plate are provided. good.

Further, in the display device, a configuration may be provided wherein the circularly polarizing plate is provided with a touch sensor disposed on a side opposite to the side facing the display panel.

That is, the present invention has the following aspects.

[1] A circular polarizing plate used in a bendable display device, comprising a polarizer, and a phase difference layer disposed on one side of the polarizer, wherein the polarizer has a visibility-correcting unitary transmittance of 42% or more, and the phase difference layer is 1/2 A wavelength plate and a quarter wave plate are included, and the half wave plate and the quarter wave plate each include a layer cured by a liquid crystal compound, and the slow axis direction of the quarter wave plate is the polarizer. It is in the range of -20° to 20° with a positive counterclockwise direction from the absorption axis direction of and the bending direction of the display device is 80° to 100° or-with respect to the slow axis direction of the quarter wave plate. A circular polarizing plate, which is set in a range of 10° to 10°.

[2] The circular polarizing plate according to [1], wherein the 1/2 wavelength plate and the 1/4 wavelength plate are adhered through an adhesive layer.

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

[4] Any of [1] to [3], characterized in that the color of the reflected light obtained before and after the bend does not change with a ^* coordinate axis and b ^* coordinate axis in a ^* b ^* chromaticity coordinates interposed therebetween. The circular polarizing plate described in one paragraph.

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

[6] characterized by comprising a touch sensor disposed on a side of the circularly polarizing plate facing the display panel and a window film disposed on a side opposite to the side of the circularly polarizing plate facing the display panel [5] The bendable display device described in.

[7] The bendable display device according to [5], comprising a touch sensor disposed on a side opposite to the side of the circularly polarizing plate facing the display panel.

As described above, according to the aspect of the present invention, it is possible to provide a circular polarizing plate that is less likely to cause wrinkles due to bending and a flexible display device provided with the circular polarizing plate while reducing color change due to bending.

1 is a cross-sectional view showing a configuration of a circular polarizing plate according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a bendable display device provided with the circular polarizing plate shown in FIG. 1.
3 is a cross-sectional view showing the configuration of an organic EL element.
4A is a schematic diagram for describing a curved state of a display device.
4B is a schematic diagram for describing a curved state of the display device.
FIG. 4C is a schematic view for describing a curved state of the display device.
4D is a schematic view for describing a curved state of the display device.
5 is a schematic view for explaining the relationship between the bending direction of the display device and the absorption axis direction of the polarizer, and the slow axis direction of the λ/2 plate and the slow axis direction of the λ/4 plate.
FIG. 6 is a cross-sectional view showing another configuration example of the bendable display device provided with the circular polarizing plate shown in FIG. 1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, components may be schematically illustrated in order to make each component easier to see, and scales of dimensions may be different depending on the components. In addition, the materials, numerical values, etc. which are illustrated in the following description are only examples, and the present invention is not necessarily limited to these, and can be carried out by appropriately changing the scope without changing the subject matter.

As one embodiment of the present invention, a bendable display device 10 including, for example, a circular polarizing plate 1 shown in FIG. 1 and a circular polarizing plate 1 shown in FIG. 2 will be described. Here, FIG. 1 is a cross-sectional view showing the configuration of the circular polarizing plate 1. 2 is a cross-sectional view showing the configuration of the display device 10.

The circularly polarizing plate 1 of the present embodiment, as shown in FIG. 1, has a polarizer 2 and a half-wavelength (λ/2) plate 3 arranged on one side of the polarizer 2. And a phase difference layer (RF) including a quarter wavelength (λ/4) plate 4. In addition, protective films (protective layers) 5 and 6 are disposed on both sides of the polarizer 2, respectively.

On one side of the polarizer 2, a λ/2 plate 3 is laminated through a PSA layer (adhesive layer) 7. The λ/2 plate 3 and the λ/4 plate 4 are laminated through an adhesive layer or an adhesive layer 8. A PSA layer (adhesive layer) 9 for stacking on the display panel 20 to be described later is disposed on a surface of the circular polarizing plate 1 facing the λ/4 plate 4. In addition, a release film (not shown) is bonded to the surface of the PSA layer 9 until it is used. Further, the PSA layers 7 and 9 are formed of, for example, an acrylic adhesive.

The polarizer 2 passes light of linearly polarized light having a polarizing surface in a specific direction, and the light passing through the polarizer 2 becomes linearly polarized light that vibrates in the direction of the transmission axis of the polarizer. The thickness of the polarizer 2 is, for example, about 1 μm to 80 μm.

Examples of the polarizer 2 include hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, with dichroic materials such as iodine and dichroic dyes. In addition to the dyeing treatment and the stretching treatment, polyene-based alignment films such as a dehydration treatment of polyvinyl alcohol and a dehydrochloric acid treatment of polyvinyl chloride can be used. Among them, it is preferable to use one obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching as having excellent optical properties.

Dyeing with iodine is performed, for example, by dipping a polyvinyl alcohol-based film in an aqueous solution of iodine. It is preferable that the draw ratio of uniaxial stretching is 3 to 7 times. Stretching may be performed after dyeing treatment or may be performed while dyeing. Moreover, you may dye|dye after extending|stretching.

The polyvinyl alcohol-based film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, and a drying treatment, if necessary. For example, by staining and washing the polyvinyl alcohol-based film with water before dyeing, it is possible not only to clean the surface of the polyvinyl alcohol-based film, but also to prevent anti-blocking agents, as well as to swell the polyvinyl alcohol-based film to prevent staining and the like. Can.

As the polarizer 2, as described in Japanese Patent Laid-Open No. 2016-170368, for example, one in which a dichroic dye is oriented in a cured film obtained by polymerization of a liquid crystal compound may be used. As the dichroic dye, one having absorption in the range of wavelength 380 to 800 nm can be used, and an organic dye is preferably used. As a dichroic dye, an azo compound is mentioned, for example. The liquid crystal compound is a liquid crystal compound that can be polymerized while being oriented, and may have a polymerizable group in the molecule.

The polarization degree corrected for visibility of the polarizer 2 is preferably 95% or more, and more preferably 97% or more. Moreover, it may be 99% or more, or 99.9% or more. Visibility correction polarization degree of the polarizer 2 may be 99.995% or less, or 99.99% or less. Visibility Correction The polarization degree is corrected by a two-degree field of view (C light source) of "JIS Z 8701:1999" with respect to the obtained polarization degree using an absorbing photometer equipped with an integrating sphere ("V7100" manufactured by Nippon Bunko Co., Ltd.). It can be calculated by performing.

Correcting the visibility of the polarizer 2 By setting the polarization degree to 95 to 99.9%, it is easy to adjust the initial color (before bending) to a position away from the neutral. For this reason, regarding the color of reflected light before and after the bending described later, it is difficult to change the sign with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates. Moreover, the durability of the circularly polarizing plate 1 can be improved by setting the polarization degree corrected for visibility of the polarizer 2 to be 99.9% or more. On the other hand, when the visibility correction polarization degree of the polarizer 2 is less than 95%, it may not function as an antireflection film. That is, when the visibility correction polarization degree of the polarizer 2 is 95% or more, it becomes easy to function as an antireflection film.

The transparency of the polarizer 2 is preferably 42% or more, more preferably 44% or more, more preferably 60% or less, and even more preferably 50% or less. Visibility correction simplex transmittance is corrected for the transmittance obtained by using a light absorbing photometer equipped with an integrating sphere ("V7100" manufactured by Nippon Bunko Co., Ltd.) with a two-degree field of view (C light source) of JIS Z 8701:1999. It can calculate by doing. The lower limit and the upper limit can be arbitrarily combined. Examples of the combination include 42% or more and 60% or less, and 44% or more and 50% or less.

By setting the visibility of the polarizer 2 to be corrected, the transmittance of the simple substance is 42% or more, so that the orthogonal color of the polarizer 2 can be easily adjusted away from the neutral side, so that the color change before and after the bending described later is not noticeable. Can. On the other hand, when it exceeds 50%, the polarization degree becomes too low, and the antireflection function may not be achieved in some cases. That is, if it is 50% or less, it is easy to achieve an antireflection function without excessively low polarization.

The λ/2 plate 3 provides a phase difference of π (=λ/2) in the field oscillation direction (polarization surface) of the incident light, and has a function of changing the direction (polarization direction) of linearly polarized light. In addition, when light of circularly polarized light is incident, the rotational direction of circularly polarized light can be rotated in the opposite direction.

In the λ/2 plate 3, Re(λ), which is an in-plane retardation value at a specific wavelength λ nm, satisfies Re(λ)=λ/2. This expression can be achieved at any wavelength in the visible region (eg, 550 nm). Especially, it is preferable that Re(550) which is an in-plane retardation value at wavelength 550 nm satisfies 210 nm<=Re(550)<=300 nm. Further, it is more preferable to satisfy 220 nm ≤ Re (550) ≤ 290 nm.

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

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 0.5 to 5 µm from the viewpoint of easy to remarkably improve the effect of preventing wrinkles. 3 μm is more preferable. In addition, regarding the thickness of the λ/2 plate 3, the thickness of any five points in the plane was measured, and these were arithmetic average.

The λ/2 plate 3 may include a film containing a resin exemplified as a material for the protective films 5 and 6 to be described later, a layer in which a liquid crystal compound is cured, and the like. When the λ/2 plate 3 is formed of resin, polycarbonate-based resin, cyclic olefin-based resin, styrene-based resin, and cellulose-based resin are particularly preferable. In this embodiment, it is preferable that the λ/2 plate 3 includes a layer in which the liquid crystal compound is cured. The type of the liquid crystal compound is not particularly limited, and can be classified into a bar type (rod-like liquid crystal compound) and a disk type (disc-type liquid crystal compound, discotic liquid crystal compound) based on the shape. In addition, there are low molecular weight type and high molecular weight type, respectively. Here, the polymer generally refers to a polymerization degree of 100 or more (polymer physics and phase transition dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).

Any liquid crystal compound can be used in the present embodiment. Moreover, you may use 2 or more types of rod liquid crystal compounds, 2 or more types of disc type liquid crystal compounds, or a mixture of a rod type liquid crystal compound and a disc type liquid crystal compound.

Moreover, as a rod-like liquid crystal compound, the thing of the claim 1 of Unexamined-Japanese-Patent No. 11-513019, or the paragraph of [0026]-[0098] of Unexamined-Japanese-Patent No. 2005-289980 can be used suitably, for example. As the disc-shaped liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013] to [0108] of JP-A-2010-244038 can be suitably used. .

It is more preferable to form the λ/2 plate 3 using a liquid crystal compound having a polymerizable group (rod-like liquid crystal compound or disc-like liquid crystal compound). Thereby, the change by the temperature of the optical characteristic or the change by humidity can be made small.

The liquid crystal compound may be a mixture of two or more kinds. In that case, it is preferable that at least one 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 cured by the liquid crystal compound. do. In this case, after layering, it is no longer necessary to exhibit liquid crystallinity.

The type of the polymerizable group contained in the rod-like liquid crystal compound or the disc-like liquid crystal compound is not particularly limited, and a functional group capable of addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring polymerizable group is preferable. More specifically, a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, etc. are mentioned, for example. Especially, a (meth)acryloyl group is preferable. Here, the (meth)acryloyl group is a concept including both a methacryloyl group and an acryloyl group.

The method for forming the λ/2 plate 3 is not particularly limited, and known methods can be mentioned. For example, a coating film is formed by applying a composition for forming an optically anisotropic layer containing a liquid crystal compound having a polymerizable group (hereinafter simply referred to as a "composition") to a predetermined substrate (including a temporary substrate), to form a coating film. The λ/2 plate 3 can be produced by subjecting it to curing treatment (irradiation of ultraviolet rays (light irradiation treatment) or heat treatment).

Application of the composition can be carried out by a known method such as a wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method and die coating method.

The composition may contain components other than the liquid crystal compound described above. For example, the composition may contain a polymerization initiator. The polymerization initiator used is, for example, a thermal polymerization initiator or a photo polymerization initiator selected according to the type of polymerization reaction. For example, examples of the photopolymerization initiator include α-carbonyl compounds, acyl ethers, α-hydrocarbon substituted aromatic acylines, polynuclear quinone compounds, and combinations of triarylimidazole dimers and p-aminophenyl ketones. . It is preferable that it is 0.01-20 mass% with respect to the total solid content of a composition, and, as for the usage-amount of a polymerization initiator, it is more preferable that it is 0.5-5 mass %.

Moreover, a polymerizable monomer may be contained in the composition from a point of uniformity and film strength of a coating film. Examples of the polymerizable monomer include radical polymerizable or cationic polymerizable compounds. Especially, a polyfunctional radical polymerizable monomer is preferable.

Moreover, it is preferable that it is copolymerizable with the liquid crystal compound containing the above-mentioned polymerizable group as a polymerizable monomer. Specific examples of the polymerizable monomers include those described in paragraphs [0018] to [0020] of JP 2002-296423 A. The use amount of the polymerizable monomer is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass, based on the total mass of the liquid crystal compound.

Further, the composition may contain a surfactant from the viewpoint of uniformity and film strength of the coating film. Examples of the surfactant include conventionally known compounds. Among them, a fluorine-based compound is particularly preferable. Specific surfactants include, for example, compounds described in paragraphs [0028] to [0056] of Japanese Patent Laid-Open No. 2001-330725, and compounds described in paragraphs [0069] to [0126] of Japanese Patent Application Publication No. 2003-295212. .

In addition, the composition may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amide (eg, N,N-dimethylformamide), sulfoxide (eg, dimethyl sulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide (eg , Chloroform, dichloromethane), esters (eg methyl acetate, ethyl acetate, butyl acetate), ketones (eg acetone, methyl ethyl ketone), ethers (eg tetrahydrofuran, 1,2-dimethoxyethane) Can. Especially, alkyl halide and ketone are preferable. Moreover, you may use together 2 or more types of organic solvents.

In addition, various kinds of compositions such as a vertical alignment agent such as a vertical alignment agent on the polarizer interface side, a vertical alignment agent on the air interface side, and a horizontal alignment agent such as a horizontal alignment agent on the polarizer interface side and a horizontal alignment agent on the air interface side An alignment agent may be included. In addition, the composition may contain, in addition to the above components, an adhesion improver, a plasticizer, a polymer, and the like.

The λ/2 plate 3 may include an alignment film having a function of defining the alignment direction of the liquid crystal compound. The alignment film generally has a polymer as a main component. As a polymer material for an alignment film, there are many literatures, and many commercial products can be obtained. Especially, it is preferable to use polyvinyl alcohol or polyimide, and its derivatives as a polymer material, and it is especially preferable to use a modified or unmodified polyvinyl alcohol.

Regarding the alignment film usable in the present embodiment, the modified polys described in paragraphs [0071] to [0095] of Japanese Patent No. 3907735, page 24, line 24 to page 49, line 8 of International Publication No. 2001/88574. Vinyl alcohol can be referred to.

Moreover, a well-known orientation process is performed to the alignment film. For example, rubbing treatment, polarization photo-alignment treatment, etc. may be mentioned, but from the viewpoint of surface roughness of the alignment film, photo-alignment treatment is preferable.

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

The λ/4 plate 4 provides a phase difference of π/2 (=λ/4) in the direction of electric field oscillation (polarization surface) of incident light, and converts linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light). It has the function of converting to linearly polarized light).

In the λ/4 plate 4, Re(λ) which is an in-plane retardation value at a specific wavelength λ nm satisfies Re(λ)=λ/4. This expression may be achieved at any wavelength in the visible region (eg, 550 nm). Especially, it is preferable that Re(550) which is an in-plane retardation value at wavelength 550 nm satisfies 100 nm<=Re(550)<=160 nm. Further, it is more preferable to satisfy 110 nm ≤ Re (550) ≤ 150 nm.

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

Although the thickness of the λ/4 plate 4 is not particularly limited, 0.5 to 10 μm is preferable, and 0.5 to 5 μm, in that wrinkles due to a difference in dimensional change in the front and back of the film at the time of bending can be prevented. Μm is more preferable, and 0.5 to 3 μm is more preferable. Here, about the thickness of the λ/4 plate 4, the thickness of any five points in the plane was measured, and these were arithmetic average.

It is preferable that the λ/4 plate 4 includes a layer in which the liquid crystal compound is cured. The type of the liquid crystal compound is not particularly limited, but the same material as exemplified as the material for the λ/2 plate 3 can be used. Especially, it is preferable that the rod-like liquid crystal compound which has a polymerizable group or the disc-shaped liquid crystal compound which has a polymerizable group is a layer formed by being fixed by polymerization. In this case, after layering, it is no longer necessary to exhibit liquid crystallinity.

Among the layers included in the circular polarizing plate 1, it is preferable that the layer cured by the liquid crystal compound other than the polarizer 2 is one layer or two layers. In addition to the polarizer 2, when three or more layers of a layer in which the liquid crystal compound is cured are included, it is considered that wrinkles are likely to occur at the time of bending because the number of layers likely to cause wrinkles increases.

The protective films 5 and 6 function as a protective layer for protecting the polarizer 2, and at least on the outer side of the polarizer 2 (the side opposite to the side opposite to the λ/2 plate 3). The protective film 5 is arrange|positioned. Moreover, the protective film 6 may be arrange|positioned on the inner side surface of the polarizer 2 (the surface on the side opposite to the λ/2 plate 3).

As the material of the protective films 5 and 6, for example, a thermoplastic resin having light transmittance (preferably optically transparent), such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.) Polyolefin-based resins such as, cellulose triacetate, cellulose ester-based resins such as cellulose diacetate, polyester-based resins, polycarbonate-based resins, (meth) acrylic resins, polystyrene-based resins or mixtures thereof, copolymers, etc. can be used. have. That is, the λ/2 plate 3 can also serve as the protective films 5 and 6.

Further, the protective films 5 and 6 may be protective films having optical functions such as a retardation film or a brightness enhancing film. For example, a film containing the thermoplastic resin can be stretched (uniaxially stretched or biaxially stretched), or a liquid crystal layer or the like formed on the film can be used as a retardation film having an arbitrary retardation value.

Examples of the chain polyolefin-based resin include copolymers containing two or more chain olefins in addition to homopolymers of chain olefins such as polyethylene resins and polypropylene resins.

The cyclic polyolefin-based resin is a generic term for a resin that is polymerized using a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include, for example, ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene and propylene (typically random copolymers), and unsaturated carbohydrates thereof. And graft polymers modified with carboxylic acids and derivatives thereof, and hydrides thereof. Among them, as a cyclic olefin, a norbornene-based resin using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers is suitably used.

The cellulose ester-based resin is an ester of cellulose and fatty acids. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, those copolymers or portions of hydroxyl groups modified with other substituents may also be used. Among them, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferred.

The polyester-based resin is a resin other than the cellulose ester-based resin having an ester bond, and generally contains a polycondensate of a polyhydric carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylic acid. Diol may be used as the polyhydric alcohol, and examples thereof include ethylene glycol, propane diol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

As specific examples of the polyester resin, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, polycyclohexane And dimethylnaphthalate.

The polycarbonate-based resin includes a polymer in which monomer units are bonded through carbonate groups. As the polycarbonate-based resin, a resin called modified polycarbonate modified with a polymer skeleton, copolymerized polycarbonate, or the like may be used.

The (meth)acrylic resin is a resin containing a compound having a (meth)acryloyl group as its main constituent monomer. Specific examples of the (meth)acrylic resins include poly(meth)acrylic acid esters such as methyl polymethacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylic acid ester copolymer, and meta Methyl acrylate-acrylic acid ester-(meth)acrylic acid copolymer, (meth)acrylic acid methyl-styrene copolymer (MS resin, etc.), copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (for example, methacrylic acid Methyl-methacrylic acid cyclohexyl copolymer, methyl methacrylate-(meth)acrylic acid norbornyl copolymer, and the like). Preferably, a polymer composed mainly of a poly(meth)acrylic acid C _1-6 (carbon number of 1 to 6) alkyl ester such as methyl poly(meth)acrylate is used. More preferably, a methyl methacrylate resin having methyl methacrylate as the main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

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

The outer protective film 5 has surface treatments such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment on the surface opposite to the side opposite to the polarizer 2, if necessary. It may be carried out. 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, still more preferably 5 μm to 150 μm.

It is preferable that the inner protective film 6 is optically isotropic. That is, this "optically isotropic" means that the in-plane retardation value Re(550) is 0 nm to 10 nm, and the retardation value Rth(550) in the thickness direction is -10 nm to +10 nm. The thickness of the protective film 6 in this case is preferably 20 μm to 200 μm, more preferably 30 μm to 100 μm, still more preferably 35 μm to 95 μm.

The adhesive layer 8 is an adhesive, for example, an active energy ray-curable adhesive (preferably an ultraviolet-curable adhesive) containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, or polyvinyl. An aqueous adhesive in which an adhesive component such as an alcohol-based resin is dissolved or dispersed in water can be used. In the circular polarizing plate 1, by laminating the λ/2 plate 3 and the λ/4 plate 4 through the adhesive layer 8, it is possible to prevent wrinkles from forming during bending.

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

Examples of the cationically polymerizable curable compound include an epoxy-based compound (a compound having 1 or 2 or more epoxy groups in a molecule), an oxetane-based compound (a compound having 1 or 2 or more oxetane rings in a molecule), or a combination thereof. Can be lifted. Examples of the radically polymerizable curable compound include (meth)acrylic compounds (compounds having one or two or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having a radically polymerizable double bond, or these. And combinations. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used in combination.

Active energy ray-curable adhesives are cationic polymerization accelerators, ion traps, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow modifiers, plasticizers, antifoaming agents, antistatic agents, leveling agents, solvents, etc., as required. It may contain additives.

When the λ/2 plate (3) and the λ/4 plate (4) are bonded using an active energy ray-curable adhesive, the λ/2 plate (3) and the active energy ray-curable adhesive are used as the adhesive layer (8). After laminating the λ/4 plate 4, the adhesive layer is cured by irradiating active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Among them, ultraviolet light is suitable, and as a light source in this case, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, or the like can be used. In the case of using the water-based adhesive, the λ/2 plate 3 and the λ/4 plate 4 are laminated through the water-based adhesive and then dried by heating.

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

The storage elastic 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, even more preferably 1000 MPa to 3000 MPa, and 1500 MPa. It is most preferable that it is ∼3000 MPa. By bonding the λ/2 plate 3 and the λ/4 plate 4 with the hard adhesive layer 8 showing such a storage elastic modulus, it is possible to further prevent wrinkles from forming in the retardation layer during bending.

The storage elastic modulus at the temperature of 30 degrees C of the adhesive layer 8 is the measured value when the storage elastic modulus at the temperature of 30 degrees C of the adhesive layer 8 in the circular polarizing plate 1 can be measured directly by the following method. Shall be On the other hand, if it cannot be measured directly, the adhesive layer test piece is formed on the release paper under the same conditions as the formation of the adhesive layer 8 (type of adhesive, curing condition), and the adhesive layer test piece is peeled from the release paper. It can be regarded as the same value as the storage modulus measured by the following method.

The storage elastic modulus of the adhesive layer 8 or the adhesive layer test piece can be measured by a commercially available dynamic viscoelasticity device, for example, it can be measured by the product name DVA-220 manufactured by Haiti Chemical Co., Ltd.

The pressure-sensitive adhesive layer 8 may be appropriately selected as a pressure-sensitive adhesive, and has adhesiveness such that peeling does not occur in a high temperature environment, a moist heat environment, or a high temperature and low temperature environment where the polarizing plate is exposed. It can be. Specifically, an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, etc. may be mentioned, and from the viewpoint of transparency, weather resistance, heat resistance and workability, an acrylic pressure-sensitive adhesive is particularly preferred.

In the adhesive, if necessary, tackifiers, plasticizers, glass fibers, glass beads, metal powders, other inorganic powders, fillers, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, antistatic agents, silane coupling agents Various additives may be appropriately blended.

The pressure-sensitive adhesive layer 8 is usually formed by applying a solution of the pressure-sensitive adhesive onto a release sheet and drying it. As the coating on the release sheet, for example, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, a spray method or the like can be employed. The release sheet in which the pressure-sensitive adhesive layer is formed is used by a method for transferring it.

The thickness of the pressure-sensitive adhesive layer 8 is usually about 3 to 100 μm, and preferably 5 to 50 μm.

The circularly polarizing plate 1 of this embodiment is used for a bendable display device 10 as shown in FIG. 2. Specific examples of the bendable display device 10 include an organic EL display device, a liquid crystal display device using circularly polarized light (typically, a liquid crystal display device in VA (Vertical Alignment) mode), a MEMS (Micro Electro Mechanical Systems) display, and the like. Can. Especially, the circularly polarizing plate 1 of this embodiment is used suitably for a flexible organic EL display device.

Specifically, the display device 10 of this embodiment includes a bendable display panel 20 and the circular polarizing plate 1 arranged on the viewer side of the display panel 20, as shown in FIG. have. The circular polarizing plate 1 is adhered to the viewing side of the display panel 20 through the PSA layer 9 so that the polarizer 2 is on the viewing side.

In the display device 10 of this embodiment, when external light is incident on the viewing side of the display panel 20, the light passing through the polarizer 2 becomes linearly polarized light. The linearly polarized light passes through the λ/2 plate 3 and the direction of linearly polarized light is converted, and then passes through the λ/4 plate 4 to become circularly polarized light. The circularly polarized light is reflected by the display panel 20, so that the circularly polarized light is reversed from the time of incidence. When the circularly polarized light reflected from the display panel 20 passes through the lambda /4 plate 4 and the lambda /2 plate 3 again, it becomes linearly polarized light orthogonal to the time of incidence. Therefore, this linearly polarized light is blocked by the polarizer 2. As a result, the influence of external light reflection can be suppressed.

An example of the display panel 20 includes, for example, an organic EL element 200 as shown in FIG. 3. Here, FIG. 3 is a cross-sectional view showing the configuration of the organic EL element 200.

Specifically, the organic EL element 200 has a substrate 210, a first electrode 220, an organic EL layer 230, a second electrode 240, and a sealing layer 250 covering them. have. In addition, the organic EL element 200 may be provided with a planarization layer (not shown) on the substrate 210, if necessary, and a short circuit between the first electrode 220 and the second electrode 240 may be provided. An insulating layer (not shown) may be provided for prevention.

The substrate 210 is made of a flexible material. When the flexible substrate 210 is used, the display device 10 can be bent at a radius of curvature described above. In addition, since the organic EL device 200 can be manufactured by a so-called roll-to-roll process, it is possible to realize low cost and mass production. In addition, the substrate 210 is preferably made of a material having a barrier property. The substrate 210 can protect the organic EL layer 230 from oxygen or moisture.

Specific examples of the material of the substrate 210 having barrier properties and flexibility include, for example, thin glass to which flexibility is given, thermoplastic resin or thermosetting resin film to which barrier properties are applied, alloys, metals, and the like.

Examples of the thermoplastic resin or thermosetting resin include polyester resin, polyimide resin, epoxy resin, polyurethane resin, polystyrene resin, polyolefin resin, polyamide resin, polycarbonate resin, silicone resin, fluorine resin, And acrylonitrile-butadiene-styrene copolymer resins. Examples of the alloy include strainless, 36 alloys, and 42 alloys. Examples of the metal include copper, nickel, iron, aluminum, and titanium.

The thickness of the substrate 210 is preferably 5 μm to 500 μm, more preferably 5 μm to 300 μm, and even more preferably 10 μm to 200 μm. If it is such a thickness, the display device 10 can be bent at the above-mentioned radius of curvature. Further, the organic EL device 200 can be suitably used in a roll-to-roll process.

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 preferable from the viewpoint of easy hole injection. Specific examples of such materials include indium tin oxide (ITO), indium zinc oxide (IZO), indium tin oxide (ITSO) containing silicon oxide, indium oxide (IWO) including tungsten oxide, indium zinc containing tungsten oxide Transparent conductive materials such as oxide (IWZO), indium oxide (ITiO) containing titanium oxide, indium tin oxide (ITTiO) containing titanium oxide, and indium tin oxide (ITMO) containing molybdenum, and gold, silver, and platinum And metals such as these and alloys thereof.

The organic EL layer 230 is a laminate including various organic thin films. Specifically, the organic EL layer 230 includes a hole-injecting organic material (eg, a triphenylamine derivative), and a hole-injecting layer 230a provided to improve hole injection efficiency from the anode, such as copper phthalocyanine A hole transport layer 230b containing a light-emitting organic material (for example, anthracene, bis[N-(1-naphthyl)-N-phenyl]benzidine, N,N'-diphenyl-NN-bis(1-naph) A light emitting layer 230c including til)-1,1'-(biphenyl)-4,4'-diamine (NPB), and an electron transport layer 230d comprising, for example, an 8-quinolinol aluminum complex, It contains an electron injecting material (for example, perylene derivative, lithium fluoride), and has an electron injecting layer 230e provided to improve electron injecting efficiency from the cathode.

As for the organic EL layer 230, any suitable combination may be employed in which the electrons and holes recombine in the light emitting layer 230c to cause light emission. The thickness of the organic EL layer 230 is preferably as thin as possible in order to transmit the emitted light as much as possible, specifically 5 nm to 200 nm, and more preferably about 10 nm.

The second electrode 240 may function as a cathode. In this case, as a material constituting the second electrode 240, a material having a small work function is preferable from the viewpoint of easy electron injection and higher luminous efficiency. Aluminum, magnesium, and these alloys are mentioned as a specific example of such a material.

The sealing layer 250 is made of a material having excellent barrier properties and transparency. Examples of the material constituting the sealing layer 250 include, for example, epoxy resin, polyurea, and the like. In addition, the sealing layer 250 may be formed by coating an epoxy resin (epoxy resin adhesive) and bonding a barrier sheet thereon.

The organic EL device 200 can be continuously produced in a roll-to-roll process. The organic EL device 200 can be manufactured, for example, according to the procedure described in Japanese Patent Laid-Open No. 2012-169236. The description of the above publication is incorporated herein by reference. Further, the organic EL element 200 is continuously stacked in a roll-to-roll process with the elongated circular polarizing plate 1, so that the organic EL display device can be continuously produced.

Further, 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.

In addition, the display panel 20 illustrates an aspect using the organic EL element 200, but is not necessarily limited to such an aspect, and the display device 10 to which the present invention is applied is, for example, a liquid crystal. The aspect provided with the display panel 20 containing a display element and the circularly polarizing plate 1 arrange|positioned at the viewer side of the display panel 20 may be sufficient.

As the display device 10 of this embodiment, as shown in Figs. 4(a) to 4(d), a curved state (a state in which bending is fixed) is also included. Here, FIGS. 4(a) to 4(d) are schematic diagrams for describing a curved state of the display device 10.

Specifically, the display device 10 may be bent at the central portion, for example, as shown in the folding expressions shown in FIGS. 4A and 4B. In addition, from the viewpoint of securing the design performance and the display screen as much as possible, as shown in Figs. 4(c) and 4(d), they may be bent at the ends.

Further, the display device 10 may be bent along its long longitudinal direction or bent along its short longitudinal direction, as shown in Figs. 4(a) to 4(d). That is, the display device 10 only needs to be bent in a specific portion (eg, part or all of the four corners in an oblique direction) according to its use.

It is preferable that the curvature radius (bending radius) of at least a part of the display device 10 is bent to 10 mm or less, more preferably 8 mm or less, and still more preferably 4 mm or less. The display device 10 of the present embodiment reduces the change in color (color) of reflected light in a state of being bent with such a very small radius of curvature, and also makes it difficult to cause wrinkles on the circular polarizing plate 1. The lower limit of the bending radius is not particularly limited, but may be 0 mm or more than 0 mm.

The relationship between the bending direction of the display device 10 (direction perpendicular to the bending start line L) and the absorption axis direction of the polarizer 2, and the slow axis direction of the λ/2 plate 3 and λ/4 plate ( The relationship of the slow axis direction of 4) will be described with reference to Figs. 5A and 5B. Here, FIGS. 5A and 5B show the relationship between the bending direction of the display device 10 and the absorption axis direction of the polarizer 2, and the slow axis direction of the λ/2 plate 3 and the λ/4 plate. It is a schematic diagram for explaining the relationship of the slow axis direction of (4). 5(a) and 5(b), the direction of the absorption axis of the polarizer 2 is indicated by a "dash line", the direction of the slow axis of the λ/2 plate 3 is indicated by a "dotted chain line", λ /4 The slow axis direction of the plate 4 is indicated by a "solid line".

The display device 10 includes at least a flat portion 10a and a straight curved start line L located at an end portion of the flat portion 10a, as shown in FIGS. 5A and 5B. It has a bent portion 10b bent along a direction orthogonal to the bend starting line L (bending direction) from the two-dot chain line shown in Figs. 5A and 5B. In this case, the bending direction of the display device 10 is a straight line when the display device 10 is viewed from the normal direction of the flat portion 10a (the Z-axis direction in Figs. 5A and 5B). Corresponds to the direction orthogonal to the bending start line L of (Y-axis direction in Fig. 5 (a), (b)).

In the display device 10 of this embodiment, the bending direction of the display device 10 with respect to the slow axis direction (0°) of the λ/4 plate 4 is -10° to 10° with a positive counterclockwise direction. (0° in FIG. 5(a)) or 80° to 100° (90° in FIG. 5(b)), preferably -5° to 5° or 85° to 95°, more preferably Is set to 0° or 90°.

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

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 disposed on the surface of the display panel 20 such that the direction of the slow axis of the λ/4 plate 4 is the angle β with respect to the absorption axis direction of the polarizer 2. Here, the angle α and the angle β are angles in which the counterclockwise direction is positive with respect to the absorption axis of the polarizer 2. The angle β is -20° to 20° in the direction of the slow axis of the λ/4 plate 4 relative to the absorption axis direction (0°) of the polarizer 2 in a counterclockwise direction. In a) and (b), the range is -15°).

Specifically, a preferable combination of the angle α and the angle β will be described. The angle α is preferably -80° to -70°, more preferably -78° to -70°, further preferably -76° to -70°. At this time, the angle β is preferably -20° to -10°, more preferably -18° to -10°, and even more preferably -16° to -10°.

In addition, the angle α is preferably 80° to 70°, more preferably 78° to 70°, and even more preferably 76° to 70°. At this time, the angle β is preferably 20° to 10°, more preferably 18° to 10°, and even more preferably 16° to 10°.

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 in such a range, color changes due to bending can be adjusted. Can be suppressed.

In addition, a circularly polarizing plate (1) of the present embodiment, the color of the reflected light obtained before and after the bending, the CIE 1976 L ^* a ^* b ^* a ^* axis and b ^* axis in the a ^* b ^* chromaticity coordinates of a color space, It is preferable that the sign does not change in between. That is, it is preferable that the color of the reflected light measured by the SCE method obtained before and after bending is set to a value that does not span the a ^* coordinate axis in the a ^* b ^* chromaticity coordinates and does not span the b ^* coordinate axis. Accordingly, even if the color of the reflected light obtained before and after bending is changed, the change in color can be made inconspicuous. For example, by adjusting the color of the polarizing plate or the retardation value of the retardation layer, it is possible to control not to cross each coordinate axis.

In addition, adjusting the wavelength dispersibility of the retardation film is also effective for color control. For example, when the phase difference value of the circularly polarizing plate 1 is raised, the a ^* value and the b ^* value are lowered, and when the phase difference value of the circularly polarizing plate 1 is lowered, the a ^* value and the b ^* value are increased.

In addition, if before and after the start of bending, at least one of the a ^* value and the b ^* value is 0, if there is no change in the other sign, it is assumed that the sign does not change before and after the bend. That is, in this case, it is assumed that a ^* coordinate axis and b ^* coordinate axis are not passed. In addition, the bending method at the time of making this evaluation can follow the method described in the Example mentioned later.

The reflection color can be measured by CM-2600d (a spectrophotometer manufactured by Konica Minolta Co., Ltd.). Based on "JIS Z 8722:2009", the setting conditions can be made as follows.

·Light source: D65 light source

·Measurement diameter: 8 mmφ

Vision: 2°

Geometry: Geometry c

In addition, this invention is not necessarily limited to the thing of the said embodiment, Various changes can be made in the range which does not deviate from the meaning of this invention.

For example, the input device of the display device 10 may be configured to include a touch sensor. Specifically, as in the display device 30 shown in FIG. 6, in addition to the configuration of the display device 10, it is also possible to have a configuration including the touch sensor 40 and the window film 50. Here, FIG. 6 is a cross-sectional view showing another configuration example of the bendable display device 30 having the circular polarizing plate 1.

In the display device 30 shown in FIG. 6, it is preferable that the touch sensor 40 is disposed on the side opposite to the display panel 20 of the circular polarizing plate 1, and the window film 50 is, It is preferable that the circularly polarizing plate 1 is disposed on the opposite side to the side facing the display panel 20. When the circularly polarizing plate 1 is present on the viewing side of the touch sensor 40, the pattern of the touch sensor 40 becomes difficult to be visually recognized, and it is preferable because the visibility of the image displayed on the display panel 20 is improved.

Accordingly, in the display device 30 illustrated in FIG. 6, the display panel 20, the touch sensor 40, the circular polarizing plate 1, and the window film 50 are stacked using an adhesive or an adhesive in this order. Have In addition, it is also possible to provide a light-shielding pattern, which will be described later, on at least one surface of any one layer of the window film 50, the circular polarizing plate 1, and the touch sensor 40.

In addition, the stacking order of the touch sensor 40 and the window film 50 is not necessarily limited to the above-described configuration, for example, the display panel 20, the circular polarizing plate 1, the touch sensor 40, the window film It can also be set as the laminated structure in the order of (50).

In addition, regarding the window film 50, the protective film 5 constituting the circular polarizing plate 1 described above may be used, and the window film 50 also serves as a protective film 5 of the circular polarizing plate 1 May be

In addition, although not shown in the present invention, in addition to the configuration of the display device 10, in a configuration provided with a touch sensor 40 on the opposite side to the side facing the display panel 20 of the circular polarizing plate 1 You may.

(Window film)

The window film 50 is disposed on the viewer's side of the bendable display device 30, and serves as a protective layer that protects other components from environmental changes such as impact or temperature and humidity from the outside. Glass has been conventionally used as such a protective layer, but the window film 50 in the flexible display device 30 is not rigid and rigid like glass, but has a bendable property.

The window film 50 has a bendable transparent base material 51 and a hard coat layer 52 provided on at least one surface of the transparent base material 51. In the display device 30 shown in FIG. 6, the hard coat layer 52 constituting the window film 50 is provided on a surface opposite to the circular polarizing plate 1 of the transparent substrate 51. The hard coat layer 52 is an outermost layer of the display device 30 and is in contact with the outside air (air). In addition, the hard coat layer 52 may be provided on the surface of the transparent substrate 51 on the side of the circular polarizing plate 1. Moreover, the hard coat layer 52 may be provided only on one side of the transparent substrate 51 or may be provided on both sides of the transparent substrate 51.

(Transparent description)

The transparent substrate 51 has a transmittance of visible light of 70% or more, and preferably 80% or more. In addition, the thickness of the transparent substrate 51 is 5 to 200 μm, and preferably 20 to 100 μm.

As the transparent base material 51, any polymer film having transparency can be used. Specifically, polyolefins such as polyethylene, polypropylene, polymethylpentene, norbornene, or cycloolefin-based derivatives having units of monomers containing cycloolefin, diacetyl cellulose, triacetyl cellulose, propionyl cellulose, etc. Modification) Celluloses, acrylics such as methyl methacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, ethylene-vinyl acetate Polyesters such as copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyamides such as nylon, polyimides, And films formed of polymers such as polyamideimides, polyetherimides, polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, and epoxy resins. Further, these unstretched films, uniaxially stretched films, or biaxially stretched films can be used.

These polymers may be used alone or in combination of two or more of them in the transparent substrate 51. Preferably, among the above-described transparent substrate 51, it is preferable to use a polyamide film, polyamideimide film or polyimide film, polyester film, olefin film, acrylic film, or cellulose film excellent in transparency and heat resistance. desirable.

It is also preferable to disperse inorganic particles such as silica, organic fine particles, and rubber particles in the polymer film. Further, a colorant such as a pigment or dye, a fluorescent whitening agent, a dispersing agent, a plasticizer, a heat stabilizer, a light stabilizer, an infrared absorber, an ultraviolet absorber, an antistatic agent, an antioxidant, a lubricant, a solvent, etc. may be included.

(Hard coat layer)

The thickness of the hard coat layer 52 is not particularly limited, but is preferably 2 to 100 μm, for example. When the thickness of the hard coat layer 52 is less than 2 μm, it is difficult to ensure sufficient scratch resistance. On the other hand, when the thickness of the hard coat layer 52 exceeds 100 µm, bending resistance decreases, and a curl generation problem due to curing shrinkage may occur. That is, when the thickness of the hard coat layer 52 is 2 µm or more, it becomes easy to ensure sufficient scratch resistance. In addition, when the thickness of the hard coat layer 52 is 100 µm or less, the bending resistance decreases, and it is difficult to cause curling problems due to curing shrinkage.

The hard coat layer 52 may be formed by curing a hard coat composition containing a reactive material that forms a crosslinked structure by irradiating active energy rays or thermal energy, but is preferably cured by irradiation with active energy rays.

The active energy ray is defined as an energy ray capable of decomposing a compound generating an active species to generate an active species. Examples of the active energy ray include visible light, ultraviolet ray, infrared ray, X ray, α ray, β ray, γ ray and electron beam. Among them, ultraviolet rays are particularly preferred.

The hard coat composition contains at least one polymerizable product of a radically polymerizable compound and a cationic polymerizable compound. A radically polymerizable compound is a compound having a radically polymerizable group. The radically polymerizable group of the radically polymerizable compound may be any functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specifically, a vinyl group, a (meth)acryloyl group, etc. are mentioned.

Moreover, when the said radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be the same respectively, or may differ. It is preferable that the number of radically polymerizable groups the radically polymerizable compound has in one molecule is two or more, from the viewpoint of improving the hardness of the hard coat layer 52.

As the radically polymerizable compound, from the viewpoint of high reactivity, a compound having a (meth)acryloyl group is preferable, and a compound or epoxy called a polyfunctional acrylate monomer having 2 to 6 (meth)acryloyl groups in one molecule Oligomers having several (meth)acryloyl groups having molecular weights of several hundred to thousands in a molecule called (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate can be preferably used. It is preferable to include at least one selected from epoxy (meth)acrylate, urethane (meth)acrylate and polyester (meth)acrylate.

The cationic polymerizable compound is a compound having a cationic polymerizable group such as an epoxy group, oxetanyl group, and vinyl ether group. The number of cationically polymerizable groups of the cationically polymerizable compound in one molecule is preferably two or more, and more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer 52. Moreover, as a cationically polymerizable compound, the compound which has at least 1 type of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable.

Cyclic ether groups such as an epoxy group and an oxetanyl group are preferable in that shrinkage due to polymerization reaction is small. In addition, the compound having an epoxy group in the cyclic ether group is advantageous in that a compound of various structures is readily available, does not adversely affect the durability of the obtained hard coat layer 52, and is also easy to control compatibility with a radically polymerizable compound. There is this.

In addition, the oxetanyl group in the cyclic ether group is easy to increase the degree of polymerization compared to the epoxy group, is low toxicity, and increases the rate of network formation obtained from the cationic polymerizable compound of the obtained hard coat layer 52, and is mixed with the radical polymerizable compound. Even in this region, there are advantages such as forming an independent network without leaving unreacted monomers in the membrane.

As a cationically polymerizable compound having an epoxy group, for example, an alicyclic epoxy resin obtained by epoxidizing a polyglycidyl ether of a polyhydric alcohol having an alicyclic ring or a compound containing a cyclohexene ring or a cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. ; Aliphatic epoxy alcohols, or aliphatic epoxy resins such as polyglycidyl ethers of alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl (meth)acrylates; Bisphenols such as bisphenol A, bisphenol F and hydrogenated bisphenol A, or glycidyl ethers and novolac epoxys produced by the reaction of derivatives such as alkylene oxide adducts and caprolactone adducts with epichlorohydrin Resins, and glycidyl ether type epoxy resins derived from bisphenols.

The hard coat composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, and a radical and cationic polymerization initiator, which can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating, and generate radicals or cations to advance radical polymerization and cationic polymerization.

The radical polymerization initiator may be capable of releasing a substance that initiates radical polymerization by irradiation of active energy rays and heating. For example, examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

Examples of the active energy ray radical polymerization initiator include a type 1 radical polymerization initiator in which radicals are generated by decomposition of molecules, and a type 2 radical polymerization initiator that coexists with a tertiary amine to generate radicals through a hydrogen draw reaction. It can also be used together or in combination.

The cationic polymerization initiator may be capable of releasing a substance that initiates cationic polymerization by at least one of active energy ray irradiation and heating. As the cationic polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, or the like can be used. These can initiate cationic polymerization with either or both of active energy ray irradiation or heating due to the difference in structure.

The polymerization initiator may contain 0.1 to 10% by weight relative to the total (100% by weight) of the hard coat composition. If the content of the polymerization initiator is less than 0.1% by weight, curing cannot proceed sufficiently, and it is difficult to realize mechanical properties or adhesion of the finally obtained coating film. On the other hand, if the content of the polymerization initiator exceeds 10% by weight, there is a case that poor adhesion or cracking phenomenon and curl phenomenon due to curing shrinkage may occur. That is, if the content of the polymerization initiator is 0.1% by weight or more, curing can proceed sufficiently, and it is easy to realize mechanical properties or adhesion of the finally obtained coating film. On the other hand, if the content of the polymerization initiator is less than 10 weight, it is difficult to cause poor adhesion, cracking and curling due to curing shrinkage.

The hard coat composition may further include one or more selected from the group consisting of solvents and additives. The solvent is capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and any known solvent as a solvent for the hard coat composition in the art can be used without limitation. The additive may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

(Touch sensor)

As the touch sensor 40, various types of methods such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitive method have been proposed, and any method may be used. Among them, the capacitive type is preferred.

The capacitive touch sensor 40 is divided into an active area and an inactive area located on an outer portion of the active area. The active area is an area corresponding to an area (display unit) on which the screen is displayed on the display panel 20, and is an area where a user's touch is sensed. Meanwhile, the inactive area is an area corresponding to an area (non-display unit) in which the screen is not displayed on the display panel 20.

The touch sensor 40 includes a substrate having flexible characteristics, a sensing pattern formed in an active region of the substrate, and a sensing pattern formed in an inactive region of the substrate, and each sensing line for connecting to an external driving circuit through the sensing pattern and the pad portion It may include. As a substrate constituting the touch sensor 40, a material containing a polymer material is usually used.

As the substrate having flexible properties, a material such as the transparent substrate 51 of the window film 50 can be used. It is preferable from the viewpoint of suppression of cracks that the substrate of the touch sensor 40 has a toughness of 2000 MPa% or more. More preferably, the toughness is 2000 to 30000 MPa%.

In addition, the toughness of the substrate is obtained from the stress-strain curve obtained by plotting the stress (MPa) [longitudinal axis] against the strain (%) [transverse axis] obtained through the tensile test of the polymer material constituting the substrate. It is defined as the lower area of the curve up to the breaking point. It is preferable from the viewpoint of suppressing cracking of the touch sensor 40 that the substrate constituting the touch sensor 40 has the toughness in the above range.

The sensing pattern may have a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and each pattern must be electrically connected to sense a touched point.

The first pattern is a form in which each unit pattern is interconnected through a joint. On the other hand, the second pattern has a structure in which each unit pattern is separated from each other in an island form. Therefore, a separate bridge electrode is required to electrically connect the second pattern.

For the sensing pattern, a well-known transparent electrode material can be applied. 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, and metal wires. Moreover, these can be used individually or in mixture of 2 or more types. Especially, it is preferable to use ITO.

The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, ternium, and chromium. Moreover, these can be used individually or in mixture of 2 or more types.

The bridge electrode may be formed on the sensing pattern through an insulating layer. In addition, a bridge electrode may be formed on the substrate, and an insulating layer and a sensing pattern may be formed thereon.

The bridge electrode may be formed of a material such as a sensing pattern, or may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them.

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 may be formed only between the seam of the first pattern and the bridge electrode, or may be formed on the layer covering the sensing pattern. In the latter case, the bridge electrode may be connected to the second pattern through a contact hole formed in the insulating layer.

The touch sensor 40 appropriately compensates for a difference in transmittance between a patterned region where a pattern is formed and a non-patterned region where no pattern is formed, specifically, a difference in light transmittance caused by a difference in refractive index in these regions. As a means for compensating, an optical control layer may be further included between the substrate and the electrode.

The optical control layer may include an inorganic insulating material or an organic insulating material. The optical control layer may be formed by coating a photocurable composition comprising a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer can be increased by the inorganic particles.

The photocurable organic binder may include, for example, copolymers of respective monomers such as acrylate-based monomers, styrene-based monomers, and carboxylic acid-based monomers. The photocurable organic binder may be a copolymer containing each other repeating unit such as an epoxy group-containing repeating unit, an acrylate repeating unit, or a carboxylic acid repeating unit.

The inorganic particles may include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further include each additive such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

(glue)

Examples of the adhesive include water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent volatilization-type adhesives, moisture-curable adhesives, heat-curable adhesives, anaerobic-curable adhesives, active energy ray-curable adhesives, curing agent mixed adhesives, and hot-melt adhesives, Pressure-sensitive adhesives (adhesives), rewet adhesives, and the like can be used. Among them, water-based adhesives and active energy ray-curable adhesives are frequently used. Moreover, what was mentioned above can be used as an aqueous adhesive and an active-energy-ray-curable adhesive.

(adhesive)

As the pressure sensitive adhesive, depending on the main polymer, acrylic pressure sensitive adhesive, urethane pressure sensitive adhesive, rubber pressure sensitive adhesive, silicone pressure sensitive adhesive and the like can be used. In addition to the main polymer, a crosslinking agent, a silane-based compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, etc. may be added to the pressure-sensitive adhesive.

Each component constituting the pressure-sensitive adhesive is dissolved and dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive layer is formed by drying after coating the pressure-sensitive adhesive composition on a substrate. The adhesive layer may be formed directly, or the one formed on the substrate may be transferred separately.

It is also preferable to use a release film to cover the adhesive surface before adhesion. The thickness of the adhesive layer when using an active energy ray-curable adhesive is 0.1 to 500 µm, and preferably 1 to 300 µm. When using multiple layers of an adhesive, the thickness or kind of each layer may be the same or may differ.

(Shading pattern)

The light-shielding pattern can be applied as at least a part of the bezel or housing of the bendable display device 30. The wiring arranged in the periphery of the bendable display device 30 is hidden by the light-shielding pattern, making it difficult to visually recognize, thereby improving the visibility of the image.

The light shielding pattern may be in the form of a single layer or multiple layers. The color of the light shielding pattern is not particularly limited, and has various colors such as black, white, and metallic. The light-shielding pattern may be formed of a pigment for realizing color, and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, and silicone. Moreover, these can also be used individually or in mixture of 2 or more types.

The light-shielding pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light shielding pattern is 1 µm to 100 µm, and preferably 2 µm to 50 µm. In addition, it is also preferable to give a shape such as a slope in the thickness direction of the optical pattern.

Example

Hereinafter, the effects of the present invention will be more apparent by examples. In addition, this invention is not limited to the following Example, It can be implemented by changing suitably as long as it does not change the summary.

[Example 1]

(Production of polarizer)

The long polyvinyl alcohol film was dyed in an aqueous solution containing iodine, and then uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to obtain a long polarizer having an absorption axis in the longitudinal direction. The elongated polarizer was wound after stretching to obtain a wound body. The chromaticity of this polarizer was orthogonal a=0.04, orthogonal b=-0.11, the polarizer's visibility correction polarization was about 99.995%, and the polarizer's visibility correction corrected group transmittance was 42.7%.

(Protective film)

As the protective film, a long triacetyl cellulose film (40 µm thick, manufactured by Konica Minolta, product name: KC4UYW) was used. This protective film was prepared as a wound body. Moreover, the in-plane retardation value Re(550) of this protective film was 5 nm, and the retardation value Rth(550) in the thickness direction was 45 nm.

(λ/2 edition)

As the λ/2 plate, a film containing a layer in which the liquid crystal compound was cured and an alignment film was used.

(λ/4 version)

As the λ/4 plate, a film comprising a layer in which the liquid crystal compound was cured and an alignment film was used.

(Ultraviolet curing adhesive)

The following components were mixed and defoamed to adjust an ultraviolet curable adhesive.

3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (trade name: CEL2021P, manufactured by Kadashi Chemical Co., Ltd.): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by Nagase Chemtex): 20 parts by mass

2-ethylhexylglycidyl ether (trade name: EX-121, manufactured by Nagase Chemtex): 10 parts by mass

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

1,4-diethoxynaphthalene: 2 parts by mass

(Production of circular polarizing plate)

After cutting the polarizer, the protective film, the λ/2 plate, and the λ/4 plate to 200 mm×300 mm, respectively, a protective film was attached to both sides of the polarizer through a polyvinyl alcohol-based adhesive. The [lambda]/2 plate and the [lambda]/4 plate were pasted through the UV curable UV adhesive (adhesive layer). In addition, the λ/2 plate and the protective film were pasted through an acrylic adhesive layer (PSA layer). An acrylic pressure-sensitive adhesive layer (PSA layer) with a release film was adhered to the λ/4 plate.

When the λ/2 plate was pasted, the slow axis was disposed so as to form an angle α of -75° with respect to the absorption axis of the polarizer. When the λ/4 plate was pasted, the slow axis was arranged so as to form an angle β of -15° with respect to the absorption axis of the polarizer. In addition, the absorption axis of the polarizer was arranged to be parallel in the longitudinal direction.

As described above, a circular polarizing plate was prepared in which a protective film, a polarizer, a protective film, a PSA layer, a λ/2 plate, a UV adhesive layer, a λ/4 plate, and a PSA layer were sequentially stacked. Then, the produced circular polarizing plate was trimmed to a size of 20 mm x 80 mm.

(Preparation of evaluation samples)

After the release film was removed from the original polarizing plate of Example 1, the adhesive side was adhered to the surface of the mat of aluminum foil (manufactured by UACJ, trade name "My foil (registered trademark)") to obtain a sample for evaluation.

As a result, as shown in Fig. 5(a), the slow axis of the λ/2 plate formed an angle α of -75° with respect to the absorption axis direction of the polarizer. The slow axis of the λ/4 plate had an angle β of -15° with respect to the absorption axis direction of the polarizer. The bending direction of the circularly polarizing plate had an angle of 0° with respect to the slow axis direction of the λ/4 plate. The curved starting line L of the circularly polarizing plate was 75° with respect to the absorption axis direction of the polarizer. Thus, a sample for evaluation was obtained. About the obtained sample for evaluation, the evaluation test of color change and wrinkle generation was performed in the state which canceled the bending state after bending (flat state).

(Measurement of storage modulus at a temperature of 30°C of the adhesive layer test piece)

First, ultraviolet rays used to bond the λ/2 plate to the λ/4 plate using a coating machine (Bar Coater, manufactured by Daiichi Rika Co., Ltd.) on one side of a 50 µm-thick cyclic polyolefin-based resin film. A curable adhesive was coated, and a cyclic polyolefin-based resin film having a thickness of 50 µm was further laminated on the coated surface.

Subsequently, ultraviolet rays were irradiated so that the accumulated light amount was 1500 mJ/cm 2 (UVB) by "H bulb" manufactured by Fusion UV Systems, and the adhesive layer was cured. The thickness of the adhesive layer was 30 μm. This was cut to a size of 5 mm x 30 mm, and the cyclic polyolefin-based resin film on both sides was peeled off to obtain a cured film of adhesive.

This cured film was gripped at a gripping tool spacing of 2 cm using a dynamic viscoelasticity measuring device ``DVA-220'' manufactured by Haiti Chemical Co., Ltd. so that its long side was in the tensile direction. Was 10 Hz and the measurement temperature was 30°C, and the storage modulus at the temperature of 30°C was determined. The storage elastic modulus at a temperature of 30°C of the adhesive layer test piece was 2060 MPa.

(Evaluation test)

The sample for evaluation is pressed against a mandrel having a diameter of 5 mm, and is circled along the circumferential surface of the mandrel so that the bending direction of the display device 10 is 0° with respect to the slow axis direction (0°) of the λ/4 plate. The polarizing plate was bent to the outside (OUT) with respect to the aluminum foil. Then, after bending, the circularly polarizing plate was visually observed and evaluated as "A" for small color change and "B" for large color change. In addition, those with little wrinkles were evaluated as "A" and those with many wrinkles as "B". The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Example 2]

In Example 2, samples for evaluation in the same manner as in Example 1 were prepared. Then, the sample for evaluation was bent along the circumferential surface of the mandrel so that the circular polarizing plate became inside (IN) with respect to the aluminum foil. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Example 3]

In Example 3, as shown in FIG. 5(b), the bending direction of the circularly polarizing plate forms an angle of 90° with respect to the slow axis direction of the λ/4 plate, and the bending starting line L of the circularly polarizing plate is A sample for evaluation of the same formula as in Example 1 was produced except that -15° was formed with respect to the absorption axis direction of the polarizer. Then, this evaluation sample was bent under the same conditions as in Example 1. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Example 4]

In Example 4, a sample for evaluation of the same formula as in Example 3 was produced. Then, the sample for evaluation was bent along the circumferential surface of the mandrel so that the circular polarizing plate became inside (IN) with respect to the aluminum foil. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Comparative Example 1]

In Comparative Example 1, the bending direction of the circularly polarizing plate forms an angle of 60° with respect to the slow axis direction of the λ/4 plate, and the bending starting line L of the circularly polarizing plate forms -45° with respect to the absorption axis direction of the polarizer. Except for that, samples for evaluation in the same manner as in Example 1 were produced. Then, this evaluation sample was bent under the same conditions as in Example 1. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Comparative Example 2]

In Comparative Example 2, the bending direction of the circularly polarizing plate forms an angle of -30° with respect to the slow axis direction of the λ/4 plate, and the bending starting line L of the circularly polarizing plate forms 45° with respect to the absorption axis direction of the polarizer. Except for that, samples for evaluation in the same manner as in Example 1 were produced. Then, this evaluation sample was bent under the same conditions as in Example 1. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Comparative Example 3]

In Comparative Example 3, a sample for evaluation in the same manner as in Comparative Example 1 was produced except that the λ/2 plate and the λ/4 plate were pasted through an adhesive layer. Then, this evaluation sample was bent under the same conditions as in Example 1. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Comparative Example 4]

In Comparative Example 4, a sample for evaluation in the same manner as in Comparative Example 2 was produced except that the λ/2 plate and the λ/4 plate were pasted through an adhesive layer. Then, this evaluation sample was bent under the same conditions as in Example 1. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[Comparative Example 5]

In Comparative Example 5, a sample for evaluation of the same formula as Comparative Example 1 was produced. Then, the sample for evaluation was bent along the circumferential surface of the mandrel so that the circular polarizing plate became inside (IN) with respect to the aluminum foil. And after bending, the evaluation test of the same formula as in Example 1 was performed. The evaluation results are shown in Table 1 below. In addition, the color of the reflected light obtained before and after the bending did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates.

[evaluation]

As is clear from Table 1, according to Examples 1 to 4 of the present invention, compared with Comparative Examples 1 to 5, good results were obtained with respect to changes in color (color) of reflected light and presence or absence of wrinkles in the curved portion. Was obtained.

One… Circular polarizer
2… Polarizer
RF... Retardation layer
3… λ/2 plate (1/2 wave plate layer)
4… λ/4 plate (1/4 wave 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 device
210… Board
220… First electrode
230… Organic EL layer
240… Second electrode
250… Sealing layer.

Claims (7)

A circular polarizing plate used in a bendable display device,
A polarizer and a retardation layer disposed on one side of the polarizer,
The polarizer's visibility correction group transmittance is 42% or more,
The retardation layer includes a half wave plate and a quarter wave plate,
The 1/2 wavelength plate and the 1/4 wavelength plate each include a layer cured by a liquid crystal compound,
The direction of the slow axis of the quarter wave plate is in the range of -20° to 20° with a positive counterclockwise direction from the direction of the absorption axis of the polarizer. A circular polarizing plate characterized in that the bending direction of the display device with respect to the axial direction is set in a range of 80° to 100° or -10° to 10°. The circular polarizing plate according to claim 1, wherein the 1/2 wave plate and the 1/4 wave plate are adhered through an adhesive layer. The circular polarizing plate according to claim 1 or 2, wherein the display device is an organic electroluminescence display device. The color of the reflected light obtained before and after bending is characterized in that the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates according to any one of claims 1 to 3. Circular polarizing plate made with. A bendable display device comprising the circularly polarizing plate according to any one of claims 1 to 4 and a bendable display panel. The touch sensor of claim 5, further comprising: a touch sensor disposed on a side of the circularly polarizing plate facing the display panel;
And a window film disposed on a side opposite to the side opposite to the display panel of the circularly polarizing plate. The bendable display device of claim 5, further comprising a touch sensor disposed on a side opposite to the side of the circularly polarizing plate facing the display panel.

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