TWI767086B - Circularly polarizing plate and display device - Google Patents

Abstract

The present invention relates to a circularly polarizing plate l used for a bendable display device including a polarizer 2 and a retardation layer RF disposed on one side of the polarizer 2. A luminosity correction unit transmittance of the polarizer 2 is not less than 42%. The retardation layer RF includes a half wavelength plate 3 and a quarter wavelength plate 4. The half wavelength plate 3 and the quarter wavelength plate 4 each include a layer in which a liquid crystal compound is cured. A slow axis direction of the quarter wavelength plate 4 is in a range of -20° to 20° from an absorption axis direction of the polarizer 2 assuming that a counterclockwise direction is positive, and a bending direction of a display device is set in a range of 80° to 100° or -10° to 10° with respect to the slow axis direction of the quarter wavelength plate 4.

Description

Circular polarizing plate and display device

The present invention relates to circular polarizers. Furthermore, it relates to a flexible display device provided with the aforementioned circular polarizing plate.

In this case, priority is claimed based on Japanese Patent Application No. 2017-217106 filed in Japan on November 10, 2017 and Japanese Patent Application No. 2018-201205 filed in Japan on October 25, 2018. content.

Conventionally, circular polarizers have been used in order to suppress adverse effects caused by reflection of external light in display devices. On the other hand, in recent years, the desire for a bendable (flexible) display device typified by an organic electroluminescence (EL) display device has been increasing. Furthermore, not only flexibility of the display device is required, but also flexibility in a very small radius of curvature is required.

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

Therefore, in response to such a problem, the following Patent Document 1 proposes a circularly polarizing plate including a retardation film including a 1/2 wavelength (λ/2) plate and a 1/4 wavelength (λ/4) plate, and λ/2 The plate and the λ/4 plate each contain a liquid crystal compound, and are adjusted so that the slow axis direction of the retardation film is regulated at an angle of 75 to 105 degrees with respect to the bending direction of the display device.

[Prior Art Literature] [Patent Literature]

Patent Document 1: International Publication No. 2016/158300

However, for the above-mentioned flexible display device, further improvement is required for its visibility. Furthermore, it is required to reduce the change in hue (hue) of the reflected light in the curved portion when the display device is curved.

Therefore, the circular polarizer used in the flexible display device must be able to follow the curved portion of the display device. Furthermore, it is also required that wrinkles are not easily generated before and after the bending of the circularly polarizing plate.

The present invention has been proposed in view of the foregoing circumstances, and an object of the present invention is to provide a circular polarizing plate and a flexible display device provided with the circular polarizing plate, which reduce the color change caused by bending and do not Wrinkles caused by bending are prone to occur.

In terms of means for solving the above-mentioned problems, according to an aspect of the present invention, there can be provided a circularly polarizing plate for use in a flexible display device, the circularly polarizing plate comprising: a polarizer and one of the polarizers The phase difference layer configured on the side; wherein, the visual sensitivity correction monomer transmittance of the aforementioned polarizer is more than 42%, and the aforementioned phase difference layer comprises a 1/2 wavelength plate and a 1/4 wavelength plate, and the aforementioned 1/2 wavelength plate and the aforementioned 1/4 wavelength plate respectively comprise a layer hardened by a liquid crystal compound; when the counterclockwise direction is set as positive, the slow axis direction of the aforementioned 1/4 wavelength plate is calculated from the absorption axis direction of the aforementioned polarizer at The range of -20° to 20°, and 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.

Furthermore, in the aforementioned circularly polarizing plate, the configuration may be such that the aforementioned 1/2 wavelength plate and the aforementioned 1/4 wavelength plate are bonded via an adhesive layer.

Furthermore, in the aforementioned circular polarizing plate, the configuration can be as follows: the aforementioned display device is an organic electroluminescence display device.

Furthermore, in the aforementioned circular polarizing plate, the structure may be such that the sign of the hue of the reflected light obtained before and after bending in the a*b* chromaticity coordinate does not change across the a* coordinate axis and the b* coordinate axis.

Furthermore, according to an aspect of the present invention, a flexible display device can be provided, which includes any one of the aforementioned circular polarizers and a flexible display panel.

Furthermore, in the above-mentioned display device, the configuration may include: a touch sensor disposed on the side of the circular polarizer facing the display panel, and a touch sensor disposed on the side of the circular polarizer and facing the display panel. The window film on the opposite side.

Furthermore, in the above-mentioned display device, the configuration may include a touch sensor arranged on the side opposite to the side facing the display panel of the circularly polarizing plate.

That is, the present invention has the following aspects.

[1] A circular polarizer for use in a flexible display device, the circular polarizer comprising: a polarizer and a retardation layer disposed on one side of the polarizer; wherein the visual sensitivity of the polarizer is The transmittance of the correction monomer is more than 42%; the retardation layer includes a 1/2 wavelength plate and a 1/4 wavelength plate; the foregoing 1/2 wavelength plate and the foregoing 1/4 wavelength plate are respectively made of liquid crystal compounds and hardened. When the counterclockwise direction is set as positive, the slow axis direction of the aforementioned 1/4 wave plate is in the range of -20° to 20° from the absorption axis direction of the aforementioned polarizer; and, relative to the aforementioned 1 In the direction of the slow axis of the /4-wavelength plate, the bending direction of the display device is set in the range of 80° to 100° or -10° to 10°.

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

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

[4] The circularly polarizing plate according to any one of [1] to [3], wherein the sign of the hue of the reflected light obtained before and after bending in the a*b* chromaticity coordinate does not cross the a* coordinate axis and b* coordinate axis.

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

[6] The bendable display device according to [5], comprising: a touch sensor disposed on the side of the circular polarizing plate facing the display panel, and a touch sensor disposed between the circular polarizing plate and the side facing the above-mentioned circular polarizing plate The side of the display panel is the window film arranged on the opposite side.

[7] The bendable display device according to [5], further comprising: a touch sensor disposed on the side opposite to the side facing the display panel of the circular polarizer.

As described above, according to an aspect of the present invention, a circular polarizing plate and a flexible display device including the circular polarizing plate can be provided, which reduce the color change caused by bending and are less likely to cause problems caused by bending. Wrinkles caused by bending.

1‧‧‧Circular polarizer

2‧‧‧Polarizer

3‧‧‧λ/2 plate (1/2 wavelength plate)

4‧‧‧λ/4 plate (1/4 wavelength plate)

5.6‧‧‧Protective film (protective layer)

7‧‧‧PSA layer (adhesive layer)

8‧‧‧Adhesive layer or adhesive layer

9‧‧‧PSA layer (adhesive layer)

10‧‧‧Display device

20‧‧‧Display panel

30‧‧‧Display device

40‧‧‧Touch Sensor

50‧‧‧Window Film

200‧‧‧Organic EL elements

210‧‧‧Substrate

220‧‧‧First electrode

230‧‧‧Organic EL layer

240‧‧‧Second electrode

250‧‧‧Sealing layer

RF‧‧‧Phase Difference Layer

Fig. 1 is a cross-sectional view showing the structure of a circularly polarizing plate according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the structure of a flexible display device provided with the circular polarizing plate shown in Fig. 1 .

FIG. 3 is a cross-sectional view showing the structure of an organic EL element.

FIG. 4A is a schematic diagram for explaining the bending state of the display device.

FIG. 4B is a schematic diagram for explaining the bending state of the display device.

FIG. 4C is a schematic diagram for explaining the bending state of the display device.

FIG. 4D is a schematic diagram for explaining the bending state of the display device.

5 is a schematic diagram for explaining the relationship between the bending direction of the display device and the absorption axis direction of the polarizer, and the relationship between 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 flexible display device including 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, in order to make each component easy to see, a component is shown schematically, and a size scale is changed according to a component. In addition, the materials, numerical values, etc. illustrated in the following description are examples, and the present invention is not limited to these, and can be appropriately changed and implemented within the scope of not changing the gist.

One embodiment of the present invention will be described, for example, with the circular polarizing plate 1 shown in FIG. 1 and the flexible display device 10 including the circular polarizing plate 1 shown in FIG. 2 . In addition, FIG. 1 is a cross-sectional view showing the configuration of the circular polarizing plate 1 . FIG. 2 is a cross-sectional view showing the configuration of the display device 10 .

As shown in FIG. 1, the circularly polarizing plate 1 of the present embodiment includes a polarizer 2, and a retardation layer RF arranged on one surface side of the polarizer 2, and the retardation layer RF includes a 1/2 wavelength (λ/2 ) plate 3 and 1/4 wavelength (λ/4) plate 4. Furthermore, on both surfaces of the polarizer 2, protective films (protective layers) 5 and 6 are arranged, respectively.

On one side of the polarizer 2 , a λ/2 plate 3 is laminated with a PSA layer (adhesive layer) 7 interposed therebetween. The λ/2 plate 3 and the λ/4 plate 4 are laminated with an adhesive layer or an adhesive layer 8 interposed therebetween. On the surface of the circularly polarizing plate 1 facing the λ/4 plate 4, a PSA layer (adhesive layer) 9 for laminating a display panel 20 described later is disposed. In addition, on the surface of this PSA layer 9, a release film (not shown) is attached before use. In addition, the PSA layers 7 and 9 are formed of, for example, an acrylic adhesive.

The polarizer 2 transmits linearly polarized light having a polarization plane in a specific direction, and the light passing through the polarizer 2 becomes linearly polarized light vibrating 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.

For the polarizer 2, in addition to the use of a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene-vinyl acetate copolymer-based partially saponified film, iodine or dimethacrylate can be used. In addition to the dyeing treatment and stretching treatment of dichroic substances such as chromatic dyes, polyene-based alignment films such as dehydration-treated products of polyvinyl alcohol and dehydrochloric acid-treated products of polyvinyl chloride can also be used. Among these, those having excellent optical properties are preferably those obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially extending the film.

The dyeing with iodine can be performed, for example, by immersing a polyvinyl alcohol-based film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment, or may be carried out while dyeing. In addition, dyeing can also be performed after extending|stretching.

The polyvinyl alcohol-based film can be subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment and the like as necessary. For example, by immersing the polyvinyl alcohol-based film in water and washing it before dyeing, not only the dirt on the surface of the polyvinyl alcohol-based film or the anti-blocking agent can be removed, but also the polyvinyl alcohol-based film can be prevented from The mesangium swells and uneven dyeing occurs.

As the polarizer 2, for example, what is described in JP-A No. 2016-170368 can be used to align the dichroic dye in the cured film in which the liquid crystal compound is polymerized. As the dichroic dye, those having absorption in the wavelength range of 380 to 800 nm can be used, and organic dyes are preferably used. Dichroic dyes include, for example, azo compounds. The liquid crystal compound is a liquid crystal compound that can be polymerized directly after alignment, and may have a polymerizable group in the molecule.

The visual sensitivity correction polarization degree of the polarizer 2 is preferably 95% or more, more preferably 97% or more. Furthermore, it may be 99% or more, or 99.9% or more. The viewing sensitivity of the polarizer 2 may be 99.995% or less, or 99.99% or less. To correct the degree of polarization of the visual sensitivity, an absorptiometer with an integrating sphere (“V7100” manufactured by Nippon Shoko Co., Ltd.) can be used. light source) is calculated by performing visual sensitivity correction.

By setting the visual sensitivity correction polarization degree of the polarizer 2 to 95 to 99.9%, it becomes easy to adjust the initial (before bending) hue to a position deviated from neutral. Accordingly, the sign on the a*b* chromaticity coordinate of the hue of the reflected light before and after bending, which will be described later, becomes less likely to change across the a* coordinate axis and the b* coordinate axis. Furthermore, by setting the viewing sensitivity correction polarization degree of the polarizer 2 to be 99.9% or more, the durability of the circularly polarizing plate 1 can be improved. On the other hand, when the optical sensitivity correction polarization degree of the polarizer 2 is less than 95%, the function as an antireflection film may not be exhibited. That is, when the viewing sensitivity correction polarization degree of the polarizer 2 is 95% or more, it becomes easy to function as an antireflection film.

The transmittance of the optical sensitivity correction monomer of the polarizer 2 is preferably 42% or more, more preferably 44% or more, preferably 60% or less, and more preferably 50% or less. To correct the transmittance of a single unit, an absorptiometer with an integrating sphere (“V7100” manufactured by Nippon Spectroscopy Co., Ltd.) can be used. The transmittance obtained is based on the 2-degree field of view of JIS Z 8701:1999 ( C light source) is calculated by performing visual sensitivity correction. The aforementioned lower limit value and upper limit value can be arbitrarily combined. Examples of combinations include 42% or more and 60% or less, and 44% or more and 50% or less.

By setting the transmittance of the optical sensitivity correction unit of the polarizer 2 to 42% or more, the orthogonal hue of the polarizer 2 can be easily adjusted to a position deviating from the neutral side, so that the color change before and after bending, which will be described later, can be changed. Not obvious. On the other hand, when it exceeds 50%, the degree of polarization becomes too low, and the antireflection function may not be achieved. That is, when it is less than 50%, the degree of polarization does not become too low, and it becomes easy to achieve the function of anti-reflection.

The λ/2 plate 3 imparts a phase difference of π (=λ/2) in the electric field vibration direction (polarization plane) of incident light, and has a function of changing the direction (polarization orientation) of linearly polarized light. Furthermore, when circularly polarized light is incident, the rotation direction of the circularly polarized light can be reversed.

Re(λ) of the in-plane retardation value of the λ/2 plate 3 at a specific wavelength λnm satisfies Re(λ)=λ/2. This formula can be achieved at any wavelength (eg, 550 nm) in the visible light region. Among them, it is preferable that Re(550) of the in-plane retardation value at a wavelength of 550 nm satisfies 210 nm≦Re(550)≦300 nm. Furthermore, it is better to satisfy 220nm≦Re(550)≦290nm.

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

The thickness of the λ/2 plate 3 is not particularly limited, but from the viewpoint of easily exerting the effect of preventing wrinkles, it is preferably 0.5 to 10 μm , more preferably 0.5 to 5 μm , and 0.5 μm. To 3 μm is still better. In addition, the thickness of the λ/2 plate 3 is obtained by measuring the thickness of arbitrary 5 points in the plane and arithmetically averaging these.

The λ/2 plate 3 may include a film made of resin exemplified as a material of the protective films 5 and 6 to be described later, a layer formed by curing a liquid crystal compound, and the like. When the λ/2 plate 3 is formed of resins, among them, polycarbonate-based resins, cyclic olefin-based resins, styrene-based resins, and cellulose-based resins are preferred. In this embodiment, the ?/2 plate 3 preferably includes a layer obtained by curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, and can be classified into a rod-like type (rod-like liquid crystal compound) and a discotic type (disc-like liquid crystal compound, discotic liquid crystal compound) from the shape. In addition, each has a low molecular weight type and a high molecular weight type. In addition, the term "polymer" generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics and Phase Transfer Kinetics, by Masao Doi, 2 pages, Iwanami Shoten, 1992).

In this embodiment, an arbitrary liquid crystal compound can also be used. Furthermore, two or more types of rod-like liquid crystal compounds, two or more types of discotic liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a discotic liquid crystal compound may be used.

Moreover, as a rod-shaped liquid crystal compound, it is preferable to use, for example, what is described in the claim 1 of JP-A No. 11-513019 or paragraphs [0026] to [0098] of JP-A No. 2005-289980. The discotic liquid crystal compound is preferably used, for example, as described in paragraphs [0020] to [0067] of JP 2007-108732 A, or paragraphs [0013] to [0108] of JP 2010-244038 A. By.

The λ/2 plate 3 is more preferably formed using a liquid crystal compound (rod-like liquid crystal compound or discotic liquid crystal compound) having a polymerizable group. Thereby, the change by temperature and the change by humidity of an optical characteristic can be reduced.

The liquid crystal compound may be a mixture of two or more. In this 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 polymerizing a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group, and such a layer is included in the liquid crystal compound. hardened layer. In this case, after forming a layer, 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 discotic liquid crystal compound is not particularly limited. For example, it is preferably a polymerizable ethylenically unsaturated group or a cyclic polymerizable group that can undergo an addition polymerization reaction. base. More specifically, (meth)acryloyl group, vinyl group, styryl group, allyl group, etc. are mentioned, for example. Among them, a (meth)acryloyl group is preferred. In addition, the (meth)acryloyl group means a concept including both a methacryloyl group and an acryl group.

The method for forming the λ/2 plate 3 is not particularly limited, and known methods can be used. For example, a composition for forming an optically anisotropic layer (hereinafter, abbreviated as "composition") containing a liquid crystal compound having a polymerizable group can be applied to a predetermined substrate (including a temporary substrate) to form a coating film, and the obtained The coating film is subjected to curing treatment (irradiation of ultraviolet rays (light irradiation treatment) or heat treatment), thereby producing a λ/2 plate 3 .

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

Components other than the above-mentioned liquid crystal compound may be contained in the composition. For example, a polymerization initiator may be contained in the composition. The polymerization initiator used is selected according to the form of the polymerization reaction, for example, a thermal polymerization initiator or a photopolymerization initiator. For example, the photopolymerization initiators include α-carbonyl compounds, acyloin ethers, aromatic alkoxide compounds substituted with α-hydrocarbons, polynuclear quinone compounds, triarylimidazole dimers, and p-aminobenzene combination of ketones, etc. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the composition.

In addition, a polymerizable monomer may be contained in a composition from the viewpoint of the uniformity of a coating film and the intensity|strength of a film. The polymerizable monomer includes radically polymerizable or cationically polymerizable compounds. Among them, polyfunctional radically polymerizable monomers are preferred.

Moreover, as a polymerizable monomer, it is preferable that it is copolymerizable with the above-mentioned polymerizable group-containing liquid crystal compound. Specific polymerizable monomers include, for example, those described in paragraphs [0018] to [0020] of JP-A No. 2002-296423. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, relative to the total mass of the liquid crystal compound.

Furthermore, from the viewpoint of the uniformity of the coating film and the film strength, a surfactant may be contained in the composition. As the surfactant, known compounds can be exemplified. Among them, fluorine-based compounds are particularly preferred. Specific surfactants include, for example, the compounds described in paragraphs [0028] to [0056] in Japanese Patent Application Laid-Open No. 2001-330725, and paragraphs [0069] to [0126] in Japanese Patent Application No. 2003-295212 Compounds described.

In addition, a solvent may be contained in a composition, and it is preferable to use an organic solvent. Examples of the organic solvent include amides (for example, N,N-dimethylformamide), sulfene (for example, dimethylsulfoxide), heterocyclic compounds (for example, pyridine), hydrocarbons (for example, benzene, hexane), Alkyl halides (eg chloroform, dichloromethane), esters (eg methyl acetate, ethyl acetate, butyl acetate), ketones (eg acetone, methyl ethyl ketone), ethers (eg tetrahydrofuran, 1,2- dimethoxyethane). Among them, alkyl halides and ketones are preferred. Furthermore, two or more types of organic solvents may be used in combination.

Furthermore, the composition may also include vertical alignment accelerators such as polarizer interface side vertical alignment agents, air interface side vertical alignment agents, and horizontal alignment accelerators such as polarizer interface side horizontal alignment agents and air interface side horizontal alignment agents. Various alignment agents such as. In addition, the composition may contain an adhesion improver, a plasticizer, a polymer, and the like in addition to the above-mentioned components.

The λ/2 plate 3 may also contain an alignment film having a function of defining the alignment direction of the liquid crystal compound. Alignment films are generally based on polymers. Polymer materials for alignment films are described in many literatures, and many commercial products are also available. Among them, as the polymer material, polyvinyl alcohol, polyimide, and derivatives thereof are preferably used, and modified or unmodified polyvinyl alcohol is particularly preferably used.

For the alignment film that can be used in this embodiment, refer to International Publication No. 2001/88574, page 43, line 24 to page 49, line 8, and Japanese Patent No. 3907735, Nos. [0071] to [0095] ] paragraph described in the modified polyvinyl alcohol.

In addition, a generally known alignment treatment may be performed on the alignment film. For example, rubbing treatment, photo-alignment treatment by irradiating polarized light, etc. are mentioned, and photo-alignment treatment is preferable from the viewpoint of the surface roughness of the alignment film.

The thickness of the alignment film is not particularly limited, and is mostly 20 μm or less, among which, it is preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, and still more preferably 0.01 to 1 μm.

The λ/4 plate 4 is the one that imparts a phase difference of π/2 (=λ/4) in the electric field vibration direction (polarization plane) of the incident light, and has the ability to convert linearly polarized light of a specific wavelength into circularly polarized light (or convert circularly polarized light into circularly polarized light). for linear polarization) function.

Re(λ) of the in-plane retardation value of the λ/4 plate 4 at a specific wavelength λnm satisfies Re(λ)=λ/4. This formula can be achieved at any wavelength (eg, 550 nm) in the visible light region. Among them, it is preferable that Re(550) of the in-plane retardation value at a wavelength of 550 nm satisfies 100 nm≦Re(550)≦160 nm. Furthermore, it is more preferable to satisfy 110nm≦Re(550)≦150nm.

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

The thickness of the λ/4 plate 4 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 μm, from the viewpoint of preventing wrinkling caused by the difference in the dimensions of the front and back surfaces of the film during bending to 5 μm, and more preferably 0.5 to 3 μm. In addition, the thickness of the λ/4 plate 4 is obtained by measuring the thickness of arbitrary 5 points in the plane and arithmetically averaging these thicknesses.

The λ/4 plate 4 preferably includes a layer formed by curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, and the same materials as those listed as the materials of the above-mentioned λ/2 plate 3 can be used. Among them, a layer formed by fixing a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group by polymerization is preferable. In this case, after forming a layer, it is no longer necessary to exhibit liquid crystallinity.

Among the layers contained in the circularly polarizing plate 1 , in addition to the polarizer 2 , a layer formed by curing a liquid crystal compound is preferably one layer or two layers. In addition to the polarizer 2, when three or more layers obtained by curing the liquid crystal compound are included, since the number of layers that may be wrinkled increases, it is presumed that wrinkling is likely to occur during bending.

The protective films 5 and 6 function as protective layers for protecting the polarizer 2 , and the protective film 5 is disposed on at least the outer surface of the polarizer 2 (the surface opposite to the side facing the λ/2 plate 3 ). Furthermore, the protective film 6 may be disposed on the inner surface of the polarizer 2 (the surface facing the side of 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-based resin (polypropylene-based resin, etc.), a cyclic resin, can be used. Polyolefin-based resins such as polyolefin-based resins (norbornene-based resins, etc.), cellulose ester-based resins such as cellulose triacetate, cellulose diacetate, polyester-based resins, polycarbonate-based resins, (Meth)acrylic resin, polystyrene resin, or a mixture thereof, a copolymer, or the like. That is, the λ/2 plate 3 can also serve as the protective films 5 and 6 .

Furthermore, the protective films 5 and 6 may also be protective films having optical functions such as retardation films or brightness enhancement films. For example, a retardation film to which an arbitrary retardation value is imparted can be produced by stretching a film containing the thermoplastic resin (uniaxial stretching, biaxial stretching, etc.), or by forming a liquid crystal layer or the like on the film.

As the chain polyolefin-based resin, for example, in addition to the homopolymers of chain olefins such as polyethylene resins and polypropylene resins, copolymers containing two or more kinds of chain olefins can also be mentioned.

Cyclic polyolefin-based resins are a general term for resins polymerized with cyclic olefins as polymerization units. Specific examples of cyclic polyolefin-based resins include, for example, ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymers of cyclic olefins and linear olefins such as ethylene or propylene ( Representative examples are random copolymers), graft polymers modified with unsaturated carboxylic acids or derivatives thereof, hydrides of these, and the like. Among them, as cyclic olefins, norbornene-based resins obtained by using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers are suitable.

Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of the cellulose ester-based resin include, for example, cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, these copolymers may be used, or the latter may be modified with another substituent at a part of the hydroxyl group. Among them, cellulose triacetate (ie, cellulose triacetate, TAC) is particularly preferred.

The polyester-based resin is a resin other than the above-mentioned cellulose ester-based resin having an ester bond, and is generally composed of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or its derivative, dicarboxylic acid or its derivative can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. A diol can be used as a polyhydric alcohol, For example, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, cyclohexanedimethanol, etc. are mentioned.

Specific examples of polyester-based resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyterephthalate. Propylene Diester, Polypropylene Naphthalate, Polycyclohexane Dimethyl Terephthalate, Polycyclohexane Dimethyl Naphthalate.

The polycarbonate-based resin includes a polymer in which a monomer unit is bonded via a carbonate group. The polycarbonate-based resin may be, for example, a resin called modified polycarbonate in which the polymer skeleton is modified, or a copolymerized polycarbonate or the like.

The (meth)acrylic resin is a resin containing a compound having a (meth)acryloyl group as a main constituent monomer. Specific examples of (meth)acrylic resins include, for example, poly(meth)acrylates such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate- (Meth)acrylate copolymer, methyl methacrylate-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), methyl methacrylate and Copolymers of compounds having alicyclic hydrocarbon groups (eg methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). It is preferable to use a polymer mainly composed of poly(meth)acrylate C _1-6 (carbon number 1 to 6) alkyl ester such as poly(meth)acrylate. More preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

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

As far as the outer protective film 5 is concerned, on its surface opposite to the side opposite to the polarizer 2, hard coating treatment, anti-reflection treatment, anti-adhesion treatment, anti-glare treatment, etc. can be performed as required. Surface treatment. The thickness of the protective film 5 at this time is 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm.

The inner protective film 6 is preferably optically isotropic. That is, the so-called "optical isotropy" 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 at this time is preferably 20 μm to 200 μm, more preferably 30 μm to 100 μm, and still more preferably 35 μm to 95 μm.

As the adhesive layer 8, for example, an active energy ray-curable adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron rays, and X-rays can be used. (preferably an ultraviolet curable adhesive), or a water-based adhesive prepared by dissolving or dispersing an adhesive component such as a polyvinyl alcohol-based resin in water. In the circularly polarizing plate 1, the λ/2 plate 3 and the λ/4 plate 4 are laminated with the adhesive layer 8 interposed therebetween, so that wrinkles can be prevented from being generated during bending.

From the viewpoint of showing good adhesiveness, the active energy ray-curable adhesive is preferably an active energy ray-curable adhesive that can use a cationically polymerizable curable compound and/or a radically polymerizable curable compound. composition. The active energy ray curable adhesive system may further include a cationic polymerization initiator and/or a radical polymerization initiator for starting the curing reaction of the curable compound.

Examples of cationically polymerizable curable compounds include epoxy-based compounds (compounds having one or more epoxy groups in the molecule), oxetane-based compounds (having one or more epoxy groups in the molecule) or a compound with two or more oxetane rings), or a combination of these. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), compounds having radically polymerizable double bonds Other vinyl compounds, or combinations of these. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used in combination.

The active energy ray-curable adhesive may contain a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion imparting agent, a thermoplastic resin, a filler, and a flow regulator as required. , plasticizer, defoamer, antistatic agent, leveling agent, solvent and other additives.

When the λ/2 plate 3 and the λ/4 plate 4 are bonded together using an active energy ray-curable adhesive, the λ/2 plate 3 and the λ/2 plate 3 and λ/ After 4 sheets 4, active energy rays such as ultraviolet rays, visible light, electron rays, X rays, etc. are irradiated to harden the adhesive layer. Among them, ultraviolet rays are preferred, and as the light source, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps can be used. When an aqueous adhesive is used, the λ/2 sheet 3 and the λ/4 sheet 4 may be laminated through the aqueous adhesive, and then heated and dried.

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

The storage elastic modulus of the agent layer 8 at a temperature of 30°C is preferably 600MPa to 4000MPa, more preferably 700MPa to 3500MPa, still more preferably 1000MPa to 3000MPa, and most preferably 1500MPa to 3000MPa. If the λ/2 plate 3 and the λ/4 plate 4 are bonded together with the hard adhesive layer 8 having such a storage elastic modulus, it is easier to prevent the retardation layer from being wrinkled during bending.

Regarding the storage elastic modulus of the adhesive layer 8 at a temperature of 30°C, if the storage elastic modulus of the adhesive layer 8 in the circularly polarizing plate 1 at a temperature of 30°C can be directly measured by the following method, it is set as the measurement. value. On the other hand, if direct measurement is not possible, it is possible to form an adhesive layer test piece on a release paper under the same conditions as when forming the adhesive layer 8 (type of adhesive, curing conditions), and test the adhesive layer. After the sheet was peeled off from the release paper, the storage elastic modulus measured by the following method was the same value.

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, by the product name DVA-220 manufactured by IT Measurement & Control Co., Ltd.

The adhesive layer 8 may be suitably selected from a conventionally known adhesive, and the adhesive layer 8 is an adhesive that has the degree of adhesion to the extent that the polarizing plate is exposed to a high-temperature environment, a humid-heat environment, or an environment of repeated high-temperature and low-temperature conditions without peeling off. Can. Specifically, acrylic adhesives, polysiloxane-based adhesives, rubber-based adhesives, etc. can be mentioned, and in terms of transparency, weather resistance, heat resistance, and processability, acrylic adhesives are particularly preferred. .

Adhesives can be appropriately formulated with tackifiers, plasticizers, fillers including glass fibers, glass beads, metal powders, and other inorganic powders, pigments, colorants, fillers, antioxidants, and ultraviolet absorbers as needed. agents, antistatic agents, silane coupling agents and other additives.

The adhesive layer 8 is usually formed by applying an adhesive solution on a release sheet and drying. When coating on the release sheet, for example, roll coating methods such as reverse coating and gravure coating can be used; spin coating, screen coating, fountain coating, dipping method, spray method, etc. For the release sheet provided with the adhesive layer, the method of transferring the adhesive can be used.

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

The circular polarizing plate 1 of the present embodiment can be used for a flexible display device 10 as shown in FIG. 2 . Specific examples of the flexible 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 a VA (Vertical Alignment) mode), and MEMS (Micro Electro Mechanical Systems) display etc. Among them, the circular polarizing plate 1 of the present embodiment is particularly suitable for a flexible organic EL display device.

Specifically, as shown in FIG. 2 , the display device 10 of the present embodiment includes a flexible display panel 20 and the aforementioned circular polarizer 1 arranged on the viewing side of the display panel 20 . The circular polarizer 1 is attached to the viewing side surface of the display panel 20 via the PSA layer 9 so that the polarizer 2 becomes the viewing side.

In the display device 10 of the present embodiment, the light passing through the polarizer 2 is linearly polarized by making the external light incident from the viewing side of the display panel 20 . This linearly polarized light passes through the λ/2 plate 3 to change the direction of the linearly polarized light, 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 and becomes circularly polarized light reversed from the incident light. When the circularly polarized light reflected by the display panel 20 passes through the λ/4 plate 4 and the λ/2 plate 3 again, it becomes linearly polarized light orthogonal to the incident light. Therefore, the linearly polarized light system is blocked by the polarizer 2 . As a result, the influence caused by the reflection of external light can be suppressed.

An example of the display panel 20 includes, for example, the organic EL element 200 shown in FIG. 3 . In addition, FIG. 3 is a sectional view showing the structure of the organic EL element 200 .

Specifically, this 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 these. Furthermore, the organic EL element 200 may be provided with a planarization layer (not shown) on the substrate 210 as required, and may also be provided with an insulating layer (not shown) for preventing a short circuit between the first electrode 220 and the second electrode 240 . not shown).

The substrate 210 is made of a flexible material. If the flexible substrate 210 is used, the display device 10 can be bent with the above-mentioned radius of curvature. Furthermore, since the organic EL element 200 can be manufactured using a so-called roll-to-roll process, low cost and mass production can be achieved. Furthermore, the substrate 210 is preferably made of a material with barrier properties. In this way, the substrate 210 can protect the organic EL layer 230 from oxygen or moisture.

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

Examples of thermoplastic resins or thermosetting resins include polyester-based resins, polyimide-based resins, epoxy-based resins, polyurethane-based resins, polystyrene-based resins, and polyolefin-based resins. , Polyamide resin, polycarbonate resin, polysilicone resin, fluorine resin, acrylonitrile-butadiene-styrene copolymer resin. Examples of the alloy include stainless steel, 36 alloy, and 42 alloy. Examples of metals 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 still more preferably 10 μm to 200 μm. With such a thickness, the display device 10 can be curved with the above-mentioned radius of curvature. Furthermore, the organic EL device 200 can be applied to a roll-to-roll process.

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

The organic EL layer 230 is a laminate including various organic thin films. Specifically, the organic EL layer 230 has a hole-injecting layer 230a made of a hole-injecting organic material (such as a triphenylamine derivative) and provided to improve the hole-injection efficiency from the anode; for example, The hole transport layer 230b composed of copper phthalocyanine; composed of light-emitting organic substances (such as anthracene, bis[N-(1-naphthyl)-N-phenyl]benzidine, N,N'-diphenyl-N-N - Bis(1-naphthyl)-1,1'-(biphenyl)-4,4'-diamine (NPB)) light-emitting layer 230c; made of, for example, 8-hydroxyquinoline aluminum complex The formed electron transport layer 230d; and the electron injection layer 230e, which is formed of an electron injecting material (eg, perylene derivative, lithium fluoride), and is provided in order to improve the electron injection efficiency from the cathode.

Besides, the organic EL layer 230 can also adopt any appropriate combination that can recombine electrons and holes in the light-emitting layer 230c to generate 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, preferably about 10 nm.

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

The sealing layer 250 may be formed of a material having excellent barrier properties and transparency. The material constituting the sealing layer 250 can be, for example, epoxy resin, polyurea, or the like. Furthermore, the sealing layer 250 can be formed by applying epoxy resin (epoxy resin adhesive) and attaching a barrier sheet thereon.

The organic EL element 200 can be continuously manufactured by a roll-to-roll process. The organic EL element 200 can be manufactured according to, for example, a process based on the procedure described in Japanese Patent Application Laid-Open No. 2012-169236. The descriptions of the aforementioned publications are incorporated herein by reference. In addition, the organic EL element 200 is continuously laminated with the long circular polarizing plate 1 in a roll-to-roll process to continuously manufacture an organic EL display device.

In addition, the details of the flexible 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, although the above-mentioned display panel 20 exemplifies the aspect of using the organic EL element 200, it is not necessarily limited to this aspect. The state of the display panel 20" and the "circular polarizer 1 arranged on the viewing side of the display panel 20".

As shown in FIGS. 4A to 4D, the display device 10 of the present embodiment also includes a curved state (fixed to a curved state). In addition, FIGS. 4A to 4D are schematic diagrams for explaining the bending state of the display device 10 .

Specifically, the display device 10 can be bent at the center in a foldable manner such as shown in FIGS. 4A and 4B . In addition, from the viewpoint of securing the designability and the display screen as much as possible, as shown in FIGS. 4C and 4D, the edges may be curved.

Furthermore, as shown in FIGS. 4A to 4D , the display device 10 can be bent along the long side direction or the short side direction. That is, the display device 10 only needs to bend a specific part (for example, a part or all of the four corners in an oblique direction) according to the application.

At least a part of the display device 10 is preferably curved with a radius of curvature (bending radius) of 10 mm or less, more preferably 8 mm or less, and still more preferably 4 mm or less. In the display device 10 of the present embodiment, the change in the hue (hue) of the reflected light is reduced in the state of being curved with such a very small radius of curvature, and the circular polarizing plate 1 is less likely to be wrinkled. In addition, the lower limit of the bending radius is not particularly limited, and may be 0 mm or more than 0 mm.

The relationship between the bending direction (direction perpendicular to the bending start line L) 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 will be described with reference to FIGS. 5( a ) and ( b ) Relationship with the slow axis direction of the λ/4 plate 4 . In addition, FIGS. 5(a) and (b) are used to illustrate the relationship between the bending direction of the display device 10 and the absorption axis direction of the polarizer 2, as well as the relationship between the slow axis direction of the λ/2 plate 3 and the λ/4 plate 4 Schematic diagram of the relationship of the slow axis direction. In addition, in Figure 5 (a), (b), the direction of the absorption axis of the polarizer 2 is indicated by a "dotted line", the direction of the slow axis of the λ/2 plate 3 is indicated by a "dotted line", and the direction of the λ/4 plate is indicated by a "dotted line". The direction of the slow axis of 4 is indicated by a "solid line".

As shown in FIGS. 5( a ) and ( b ), the display device 10 has at least a flat portion 10 a , and a curved portion 10 b extending from a linear curved start line L (the fifth The two-dot chain line shown in FIGS. (a) and (b) starts and bends in a direction (bending direction) orthogonal to the bending start line L. At this time, when the display device 10 is viewed from the normal direction of the flat portion 10a (the Z-axis direction in FIGS. 5(a) and (b) ), the bending direction of the display device 10 corresponds to the bending of the straight line. The direction perpendicular to the starting line L (the Y-axis direction in Fig. 5 (a), (b)).

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

At this time, the slow axis direction of the λ/2 plate 3 is set to be an angle α with respect to the absorption axis direction of the polarizer 2 . That is, the circular polarizer 1 is arranged on the surface of the display panel 20 so that the slow axis direction of the λ/2 plate 3 becomes the 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 be an angle β with respect to the absorption axis direction of the polarizer 2 . That is, the circular polarizer 1 is arranged on the surface of the display panel 20 so that the slow axis direction of the λ/4 plate 4 becomes the angle β with respect to the absorption axis direction of the polarizer 2 . In addition, both the angle α and the angle β are based on the absorption axis of the polarizer 2 , and the counterclockwise direction is regarded as a positive angle. Regarding the angle β , when the counterclockwise direction is set to be positive, the slow axis direction of the λ/4 plate 4 is set at -20° to 20° with respect to the absorption axis direction (0°) of the polarizer 2 (Fig. 5). (a) and (b) are in the range of -15°).

Specifically, the preferred 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°, and still more preferably -76° to -70°. At this time, the angle β is preferably -20° to -10°, more preferably -18° to -10°, and still more preferably -16° to -10°.

Furthermore, the angle α is preferably 80° to 70°, more preferably 78° to 70°, and still more preferably 76° to 70°. At this time, the angle β is preferably 20° to 10°, more preferably 18° to 10°, and still 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 fall within the aforementioned ranges, color change due to bending can be suppressed.

Furthermore, in the circular polarizing plate 1 of this embodiment, it is preferable that the sign of the hue of the reflected light obtained before and after bending in the a*b* chromaticity coordinates of the CIE1976L*a*b* color space does not cross the a* coordinate axis and b* coordinate axis. That is, the hue of the reflected light measured by the SCE method obtained before and after bending is preferably set to a value that does not cross the a* coordinate axis and the b* coordinate axis in the a*b* chromaticity coordinates. Thereby, even if the hue of the reflected light obtained before and after bending changes, the change of the hue can be made inconspicuous. For example, by adjusting the hue of the polarizing plate or adjusting the retardation value of the retardation layer, it can be controlled so as not to cross each coordinate axis.

Furthermore, adjusting the wavelength dispersion of the retardation film is also effective in controlling the hue. For example, when the retardation value of the circularly polarizing plate 1 is increased, the a* value and the b* value become lower, and when the retardation value of the circularly polarizing plate 1 is lowered, the a* value and the b* value become higher.

In addition, before and after the bending starts, even if at least one of the a* value and the b* value is 0, the other sign does not change, that is, the sign does not change before and after bending. That is, in this case, it is considered that the a* coordinate axis and the b* coordinate axis are not crossed. In addition, the bending method at the time of this evaluation can be based on the method described in the Example mentioned later.

The measurement of the reflection hue can be performed using CM-2600d (spectrophotometer manufactured by Konica Minolta Co., Ltd.). According to "JIS Z 8722:2009", the setting conditions can be set as follows.

‧Light source: D65 light source

‧Measurement diameter: 8mm

‧Field of view: 2°

‧Geometric condition: geometric condition c

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

For example, the input method of the above-mentioned display device 10 may include a touch sensor. Specifically, the display device 30 shown in FIG. 6 may have a configuration including a touch sensor 40 and a window film 50 in addition to the configuration of the display device 10 described above. In addition, FIG. 6 is a cross-sectional view showing another configuration example of the flexible display device 30 including the circular polarizer 1 .

In the display device 30 shown in FIG. 6 , the touch sensor 40 is preferably arranged on the side of the circular polarizer 1 facing the display panel 20 , and the window film 50 is preferably arranged on the side of the circular polarizer 1 facing the display panel 20 . The side of the display panel 20 is the opposite side. If the circular polarizer 1 is present on the viewing side of the touch sensor 40 , the pattern of the touch sensor 40 becomes difficult to see, which improves the visibility of the image displayed on the display panel 20 , which is preferable.

Therefore, in the display device 30 shown in FIG. 6 , the display panel 20 , the touch sensor 40 , the circular polarizer 1 , and the window film 50 are laminated in sequence using an adhesive or an adhesive. constitute. Furthermore, at least one surface of any layer of the window film 50 , the circular polarizer 1 , and the touch sensor 40 may be provided with a light-shielding pattern to be described later.

In addition, the stacking order of the touch sensor 40 and the window film 50 is not necessarily limited to the above-mentioned structure. For example, the display panel 20, the circular polarizer 1, the touch sensor 40, the window can The film 50 is formed by laminating.

Furthermore, the window film 50 may be the protective film 5 constituting the above-mentioned circular polarizer 1 , and the window film 50 may also serve as the protective film 5 of the circular polarizer 1 .

Furthermore, in the present invention, although the illustration is omitted, in addition to the configuration of the display device 10 described above, the touch sensor 40 may be provided on the side opposite to the side facing the display panel 20 of the circular polarizer 1 . composition.

(window film)

The window film 50 is disposed on the viewing side of the flexible display device 30 and serves as a protective layer to protect other components from external shocks and environmental changes such as temperature and humidity. In the past, glass is used for such a protective layer, but the window film 50 in the flexible display device 30 is not as rigid as glass, but has a flexible property.

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

(transparent substrate)

The transparent substrate 51 has a transmittance of visible light above 70%, preferably above 80%. Furthermore, the thickness of the transparent substrate 51 is 5 to 200 μm, preferably 20 to 100 μm.

Any transparent base material 51 may be used as long as it is a polymer film having transparency. Specifically, polyolefins such as polyethylene, polypropylene, polymethylpentene, and cycloolefin derivatives having a monomer unit of norbornene or cycloolefin, cellulose diacetate, cellulose triacetate, etc., can be mentioned. (modified) celluloses such as cellulose propionate, acrylics such as methyl methacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile/butadiene/benzene Ethylene copolymers, acrylonitrile/styrene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate Polyesters such as diesters, polyethylene naphthalate, polycarbonate, polyarylate, etc., polyamides such as nylon, polyimides, polyamides, and polyetherimides , Polyether dust, poly dust, polyvinyl alcohol, polyvinyl acetal, polyurethane, epoxy resin and other polymers formed film. In addition, these unstretched films, uniaxially stretched films, or biaxially stretched films can be used.

In the transparent base material 51, these polymers can be used alone or in a mixture of two or more. Among the above-mentioned transparent substrates 51, it is preferable to use a polyamide film, a polyamide imide film or a polyimide film, a polyester film, an olefin film, and an acrylic film, which are excellent in transparency and heat resistance. , cellulose film.

In the polymer film, it is also preferable to disperse inorganic particles such as silicon oxide, organic fine particles, rubber particles, and the like. Furthermore, it may also contain colorants such as pigments and dyes, optical brighteners, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents, etc.

(hard coating)

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 becomes difficult to ensure sufficient scratch resistance. On the other hand, when the thickness of the hard coat layer 52 exceeds 100 μm, there is a problem that bending resistance decreases and curling occurs due to curing shrinkage. That is, when the thickness of the hard-coat layer 52 is 2 micrometers or more, it becomes easy to ensure sufficient scratch resistance. Furthermore, when the thickness of the hard-coat layer 52 is 100 micrometers or less, it becomes difficult to generate|occur|produce the problem that the bending resistance falls and the curling by hardening shrinkage arises.

The hard coat layer 52 can be formed by irradiating active energy rays or thermal energy to harden a hard coat layer composition containing a reactive material forming a cross-linked structure, and is preferably hardened by irradiating active energy rays.

An active energy ray is defined as an energy ray that can decompose a compound that produces an active species to generate an active species. Examples of active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, alpha rays, beta rays, gamma rays, and electron rays. Among them, particularly preferred is ultraviolet light.

The hard coat layer composition contains at least one polymer of a radically polymerizable compound and a cationically polymerizable compound. The radically polymerizable compound refers to a compound having a radically polymerizable group. The radically polymerizable group possessed by the radically polymerizable compound may be a functional group capable of radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond, and the like. 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 or different, respectively. From the viewpoint of increasing the hardness of the hard coat layer 52 , the number of radically polymerizable groups that the radically polymerizable compound has in one molecule is preferably two or more.

From the viewpoint of high reactivity, the radically polymerizable compound is preferably a compound having a (meth)acryloyl group, and a compound having 2 to 6 (meth)acryloyl groups in one molecule is preferably used. Compounds called polyfunctional acrylate monomers or epoxy (meth)acrylates, urethane (meth)acrylates, and polyester (meth)acrylates having several ( An oligomer with a molecular weight of the meth)acryloyl group in the hundreds to thousands. It is preferable to contain 1 or more types chosen from epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

The cationically polymerizable compound refers to a compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. From the viewpoint of improving the hardness of the hard coat layer 52 , the number of the cationically polymerizable groups that the cationically polymerizable compound has in one molecule is preferably two or more, and more preferably three or more. Furthermore, the cationically polymerizable compound is preferably a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group.

A cyclic ether group such as an epoxy group and an oxetanyl group is preferable from the viewpoint of reducing shrinkage accompanying the polymerization reaction. Furthermore, among the cyclic ether groups, compounds having an epoxy group are compounds that are easy to obtain various structures, do not adversely affect the durability of the hard coat layer 52 obtained, and are incompatible with radically polymerizable compounds. Compatibility is also easy to control and so on.

Furthermore, among the cyclic ether groups, the oxetanyl group is more likely to increase the degree of polymerization than the epoxy group, has low toxicity, and has a network formation speed obtained from the cationically polymerizable compound of the hard coat layer 52 obtained. It is fast, and also in the region where it is mixed with the radically polymerizable compound, no unreacted monomer remains in the film and an independent network is formed.

Examples of the cationically polymerizable compound having an epoxy group include polyglycidyl ether of a polyol having an alicyclic ring, and a compound containing a cyclohexene ring or a cyclopentene ring has been used Alicyclic epoxy resins obtained by epoxidizing appropriate oxidizing agents such as hydrogen oxide and peracid; polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts, aliphatic long-chain polyols Aliphatic epoxy resins such as polyglycidyl ester of acid, homopolymer and copolymer of glycidyl (meth)acrylate; bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, Or these alkylene oxide adducts, caprolactone adducts and other derivatives are reacted with epichlorohydrin, etc. to produce glycidyl ethers, and novolac epoxy resins, etc. Phenol-derived glycidyl ether type epoxy resin, etc.

The hard coat composition may further contain a polymerization initiator. As a polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, etc. are mentioned, It can select and use suitably from these. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations, and perform radical polymerization and cationic polymerization.

The radical polymerization initiator may be released by at least any one of active energy ray irradiation and heating to initiate radical polymerization. For example, as a thermal radical polymerization initiator, organic peroxides, such as hydrogen peroxide and peroxybenzoic acid, azo compounds, such as azobisbutyronitrile, etc. are mentioned.

Active energy ray radical polymerization initiators include the first type of radical polymerization initiators that generate radicals by molecular decomposition, and the second type of radical polymerization initiators that coexist with tertiary amines and generate radicals by hydrogen abstraction reaction. Type 2 radical polymerization initiators can be used alone or in combination.

The cationic polymerization initiator may be released by at least any one of active energy ray irradiation and heating to initiate cationic polymerization. As the cationic polymerization initiator, aromatic iodonium salts, aromatic periconium salts, cyclopentadiene iron (II) complexes, and the like can be used. Depending on the structure, cationic polymerization can be started by either or any of active energy ray irradiation or heating.

The polymerization initiator may be contained in an amount of 0.1 to 10 wt % with respect to the entire hard coat layer composition (100 wt %). When the content of the polymerization initiator is less than 0.1 wt %, curing does not proceed sufficiently, and it is difficult to achieve mechanical properties and adhesion of the finally obtained coating film. On the other hand, when the content of the polymerization initiator exceeds 10% by weight, poor adhesion, cracking, and curling due to hardening shrinkage may occur. That is, when the content of the polymerization initiator is 0.1% by weight or more, curing can proceed sufficiently, and the finally obtained coating film can easily achieve mechanical properties and adhesion. On the other hand, when the content of the polymerization initiator is 10 weight or less, poor adhesion, cracking, and curling due to hardening shrinkage are less likely to occur.

The hard coat composition may further contain one or more selected from the group consisting of solvents and additives. Since the solvent system can dissolve or disperse the polymerizable compound and the polymerization initiator, it can be used without limitation as long as it is known as a solvent for a hard coat layer composition in this technical field. The additives may further contain inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

(touch sensor)

Various types of the touch sensor 40 have been proposed, such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and an electrostatic capacitance method, and any method may be used. Among them, the electrostatic capacitance method is preferable.

The touch sensor 40 of the electrostatic capacitance method is divided into an active area and an inactive area located at the outer portion of the active area. The active area corresponds to the area of the "area (display portion) where the screen is displayed on the display panel 20", and is an area where the user's touch is sensed. On the other hand, the inactive area corresponds to the area "area (non-display portion) where the screen is not displayed on the display panel 20".

The touch sensor 40 may include: a substrate having flexibility, a sensing pattern formed in an active area of the substrate, and a driving circuit formed in an inactive area of the substrate and connecting the sensing pattern to an external driving circuit via a pad portion of each sensing line. The substrate constituting the touch sensor 40 is generally composed of a polymer material.

As the substrate having flexibility, the same material as the transparent base material 51 of the window film 50 can be used. From the aspect of suppressing cracks, the substrate of the touch sensor 40 preferably 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 defined as "plotting the strain (%) [horizontal axis] with respect to the stress (MPa) [vertical axis] obtained by the tensile test of the polymer material constituting the substrate, A stress-strain curve is obtained, in which the area under the curve up to the point of failure is obtained.” From the viewpoint of suppressing cracks in the touch sensor 40 , it is desirable that the substrate constituting the touch sensor 40 has a toughness within the above-mentioned range.

The sensing pattern may include 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 directions different from each other. If the first pattern and the second pattern are to be formed on the same layer and the touched point is to be sensed, each pattern must be electrically connected.

The first pattern is a form in which each unit pattern is connected to each other via a joint. On the other hand, the second pattern has a structure in which the unit patterns are separated from each other in an island-like form. Therefore, in order to electrically connect the second pattern, another bridge electrode is necessary.

A known transparent electrode material can be applied to the sensing pattern. 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), That is, poly(3,4-ethylenedioxythiophene)), carbon nanotubes (CNT), graphene, metal wires, and the like. In addition, these can be used individually or in mixture of 2 or more types. Among them, ITO is preferably used.

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

The bridge electrode may be formed on the upper portion of the sensing pattern via the insulating layer. Furthermore, a bridge electrode can be formed on the substrate, and an insulating layer and a sensing pattern can be formed thereon.

The bridge electrode can also be formed of the same material as the sensing pattern, for example, it can also be formed of metals such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these. .

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 contacts of the first pattern and the bridge electrodes, or may be formed on a layer covering the sensing pattern. In the latter case, the bridge electrode is connected to the second pattern via a contact hole formed in the insulating layer.

In the touch sensor 40, an optical adjustment layer may be further included between the substrate and the electrodes, and the optical adjustment layer is used to properly compensate for the "difference between the patterned area where the pattern is formed and the non-patterned area where the pattern is not formed. The difference in transmittance" (specifically, "the difference in light transmittance induced by the difference in refractive index in these regions") means.

The optical adjustment layer may contain an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by coating a photocurable composition containing a photocurable organic binder and a solvent on a substrate. The photocurable composition may further contain inorganic particles. The refractive index of the optical adjustment layer can be raised by the inorganic particles.

The photocurable organic binder may contain, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer. The photocurable organic binder may be, for example, a copolymer containing repeating units different from each other, such as an epoxy group-containing repeating unit, an acrylate repeating unit, a carboxylic acid repeating unit, and the like.

The inorganic particles may contain, for example, zirconia particles, titanium oxide particles, alumina particles, and the like. The photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing adjuvant.

(adhesive)

Adhesives can be used: water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, moisture-curable adhesives, heat-curable adhesives, anaerobic-curable adhesives , Active energy ray hardening adhesive, hardener mixed adhesive, hot melt adhesive, pressure sensitive adhesive (adhesive), rewet adhesive, etc. Among them, water-based adhesives, active energy ray-curable adhesives, and the like are commonly used. In addition, the above-mentioned adhesive agent can be used for an aqueous adhesive agent and an active energy ray hardening-type adhesive agent.

(adhesive)

As for the adhesive, depending on the main ingredient polymer, any of the acrylic adhesives, urethane-based adhesives, rubber-based adhesives, polysiloxane-based adhesives, etc. can also be used. . In the adhesive, in addition to the main polymer, cross-linking agents, silane-based compounds, ionic compounds, cross-linking catalysts, antioxidants, adhesion imparting agents, plasticizers, dyes, pigments, inorganic fillers, etc. can also be formulated.

An adhesive layer is formed by dissolving and dispersing the components constituting the adhesive in a solvent to obtain an adhesive composition, coating the adhesive composition on a substrate, and drying it. The adhesive layer can be directly formed, or the one formed on the base material can be transferred separately.

If you want to cover the adhesive surface before bonding, it is better to use a release film. The thickness of the adhesive layer when an active energy ray hardening type adhesive is used is 0.1 to 500 μm, preferably 1 to 300 μm. When using multiple layers of adhesive, the thickness and type of each layer may be the same or different.

(shading pattern)

The light-shielding pattern may be suitable for use as at least a part of a bezel or a housing of the flexible display device 30 . The wirings arranged at the edge of the flexible display device 30 are hidden by the shading pattern so that they are not easily seen, thereby improving the visibility of the image.

The light-shielding pattern may be in the form of a single layer or a plurality of layers. The color of the shading pattern is not particularly limited, and may have various colors such as black, white, and metallic. The shading pattern can be formed by pigments used to realize color and polymers such as acrylic resin, ester resin, epoxy resin, polyurethane, polysiloxane, etc. In addition, these can 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, preferably 2 μm to 50 μm. Furthermore, it is also preferable to give a shape such as an inclination in the thickness direction of the light-shielding pattern.

[Example]

Hereinafter, the effect of this invention is demonstrated based on an Example. In addition, this invention is not limited to the following Example, In the range which does not change the summary, an appropriate change can be implemented.

[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 rollers with different rotational speed ratios in an aqueous solution containing boric acid to obtain a long strip with an absorption axis in the longitudinal direction. polarizer. After the elongated polarizer is stretched, it is rolled into a coiled body. The chromaticity of this polarizer is orthogonal a=0.04, orthogonal b=-0.11, the polarizer's visual sensitivity correction polarization is about 99.995%, and the polarizer's visual sensitivity correction monomer transmittance is 42.7%.

(protective film)

A long-length cellulose triacetate film (thickness 40 μm, manufactured by Konica Minolta, trade name: KC4UYPURE ACE) was used as a protective film. This protective film is prepared in the form of a roll. In addition, 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 plate)

As the λ/2 plate, a film including a layer hardened from a liquid crystal compound and an alignment film was used.

(λ/4 plate)

As the λ/4 plate, a film including a layer hardened from a liquid crystal compound and an alignment film was used.

(UV-curable adhesive)

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

3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name: CEL2021P, manufactured by DAICEL Co., Ltd.): 70 parts by mass

Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by NAGASE CHEMTEX Co., Ltd.): 20 parts by mass

2-Ethylhexylglycidyl ether (trade name: EX-121, manufactured by NAGASE CHEMTEX Co., Ltd.): 10 parts by mass

Cationic polymerization initiator (trade name: CPI-100, manufactured by SAN-APRO Co., Ltd.): 2.25 parts by mass in solid content (prepared as a 50% propylene carbonate solution)

1,4-diethoxynaphthalene: 2 parts by mass

(Production of circular polarizer)

After the polarizer, the protective film, the λ/2 plate, and the λ/4 plate were cut out to 200 mm×300 mm, respectively, the protective film was bonded to both surfaces of the polarizer through a polyvinyl alcohol-based adhesive. The λ/2 plate and the λ/4 plate were bonded together via the above-mentioned ultraviolet curable adhesive (adhesive layer). Furthermore, the λ/2 plate and the protective film were bonded together via an acrylic pressure-sensitive adhesive layer (PSA layer). An acrylic adhesive layer (PSA layer) with a release film was attached to the λ/4 plate.

At the time of bonding, the λ/2 plate was arranged so that its slow axis was at an angle α of -75° with respect to the absorption axis of the polarizer. At the time of bonding, the λ/4 plate was arranged so that its slow axis was at an angle β of -15° with respect to the absorption axis of the polarizer. Furthermore, the absorption axis of the polarizer is arranged parallel to the longitudinal direction.

As described above, a circular polarizing plate, which is sequentially laminated by 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, is produced. After that, the produced circular polarizer was cut into a size of 20mm×80mm.

(Preparation of samples for evaluation)

After removing the release film from the circular polarizing plate of Example 1, the adhesive surface was attached to the mat surface of an aluminum foil (manufactured by UACJ Co., Ltd., trade name "MYFOIL (registered trademark)") to obtain evaluation. Use sample.

As a result, as shown in Fig. 5(a), the slow axis of the λ/2 plate has an angle α of -75° with respect to the direction of the absorption axis of the polarizer. The slow axis of the λ/4 plate forms an angle β of -15° with respect to the direction of the absorption axis of the polarizer. The bending direction of the circularly polarizing plate is an angle of 0° with respect to the slow axis direction of the λ/4 plate. The bending start line L of the circular polarizer is 75° with respect to the absorption axis direction of the polarizer. In this way, a sample for evaluation was obtained. About the obtained sample for evaluation, after bending, in the state (flat state) which released the bending state, the evaluation test of the generation|occurence|production of a color change and a wrinkle was performed.

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

First, on one side of a cyclic polyolefin-based resin film with a thickness of 50 μm, using a coater (bar coater, manufactured by Daiichi Rika Co., Ltd.), the coating was applied so that the λ/2 plate and the λ/4 plate were bonded together. The UV-curable adhesive used for the plate was further laminated with a cyclic polyolefin-based resin film having a thickness of 50 μm on the coating surface.

Next, the adhesive layer was cured by irradiating ultraviolet rays through the "H valve" manufactured by FUSION UV SYSTEMS so that the accumulated light intensity would be 1500 mJ/cm ² (UVB). The thickness of the adhesive layer was 30 μm. This was cut into a size of 5 mm×30 mm, and the cyclic polyolefin-based resin films on both sides were peeled off to obtain a cured film of an adhesive.

This cured film was held so that its long side was in the direction of stretching, using a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Measurement & Control Co., Ltd., and the clamp interval was set to 2 cm, and the film was stretched. The frequency of shrinkage was set to 10 Hz, the measurement temperature was set to 30°C, and the storage elastic modulus at a temperature of 30°C was obtained. The storage elastic modulus of the next layer test piece at a temperature of 30° C. is 2060 MPa.

(evaluation test)

While pressing a mandrel (mandrel) having a diameter of 5 mm, the evaluation sample was moved along the center so that the bending direction of the display device 10 was at an angle of 0° with respect to the slow axis direction (0°) of the λ/4 plate. The peripheral surface of the shaft is bent so that the circular polarizer becomes the outer side (OUT) with respect to the aluminum foil. Then, the circularly polarizing plate was visually observed after bending, and the one with less color change was evaluated as "A", and the one with large color change was evaluated as "B". Furthermore, those with few wrinkles were evaluated as "A", and those with many wrinkles were evaluated as "B". The evaluation results thereof are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Example 2]

In Example 2, the same evaluation samples as in Example 1 were produced. Then, this evaluation sample was folded along the peripheral surface of the mandrel, and the circularly polarizing plate was made inward (IN) with respect to the aluminum foil. Then, after bending, the same evaluation test as Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Example 3]

In Example 3, as shown in Fig. 5(b), except that the bending direction of the circular polarizing plate is at an angle of 90° with respect to the slow axis direction of the λ/4 plate, the bending start line of the circular polarizing plate is The L system was other than -15° with respect to the absorption axis direction of the polarizer, and the same evaluation sample as in Example 1 was produced. Then, the sample for evaluation was bent under the same conditions as in Example 1. Then, after bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Example 4]

In Example 4, the same evaluation samples as in Example 3 were produced. Then, this evaluation sample was folded along the peripheral surface of the mandrel, and the circularly polarizing plate was made inward (IN) with respect to the aluminum foil. Then, after the bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Comparative Example 1]

In Comparative Example 1, except that the bending direction of the circular polarizer is at an angle of 60° with respect to the slow axis direction of the λ/4 plate, the bending start line L of the circular polarizer is relative to the absorption axis direction of the polarizer and becomes − Other than 45°, the same evaluation samples as in Example 1 were produced. Then, this evaluation sample was bent under the same conditions as in Example 1. Then, after bending, the same evaluation test as Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Comparative Example 2]

In Comparative Example 2, except that the bending direction of the circular polarizer is at an angle of -30° with respect to the slow axis direction of the λ/4 plate, the bending start line L of the circular polarizer is angled with respect to the absorption axis direction of the polarizer. Other than 45°, the same evaluation samples as in Example 1 were produced. Then, this evaluation sample was bent under the same conditions as in Example 1. Then, after bending, the same evaluation test as Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Comparative Example 3]

In Comparative Example 3, the same evaluation sample as in Comparative Example 1 was produced except that the λ/2 plate and the λ/4 plate were bonded together via the adhesive layer. Then, the sample for evaluation was bent under the same conditions as in Example 1. Then, after the bending, the same evaluation test as in Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Comparative Example 4]

In Comparative Example 4, a sample for evaluation similar to that of Comparative Example 2 was produced, except that the λ/2 plate and the λ/4 plate were bonded together via the adhesive layer. Then, this evaluation sample was bent under the same conditions as in Example 1. Then, after bending, the same evaluation test as Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Comparative Example 5]

In Comparative Example 5, the same evaluation sample as in Comparative Example 1 was produced. Then, this evaluation sample was folded along the peripheral surface of the mandrel, and the circularly polarizing plate was made inward (IN) with respect to the aluminum foil. Then, after bending, the same evaluation test as Example 1 was performed. The evaluation results are shown in Table 1 below. Furthermore, the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis.

[Evaluate]

As can be seen 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 the change in the hue (hue) of the reflected light in the curved portion and the presence or absence of wrinkles. .

1‧‧‧Circular polarizer

2‧‧‧Polarizer

3‧‧‧λ/2 plate (1/2 wavelength plate)

4‧‧‧λ/4 plate (1/4 wavelength plate)

5.6‧‧‧Protective film (protective layer)

7‧‧‧PSA layer (adhesive layer)

8‧‧‧Adhesive layer or adhesive layer

9‧‧‧PSA layer (adhesive layer)

RF‧‧‧Phase Difference Layer

Claims (7)

A circular polarizing plate, which is used in a bendable display device, the circular polarizing plate is provided with: a polarizer and a retardation layer configured on one side of the aforementioned polarizer; wherein, the visual sensitivity correction unit of the aforementioned polarizer The transmittance 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 respectively include a layer hardened by a liquid crystal compound; Taking the counterclockwise direction as positive, the slow axis direction of the aforementioned quarter wave plate is in the range of -20° to 20° from the direction of the absorption axis of the aforementioned polarizer, and relative to the aforementioned quarter wave plate For the slow axis direction, the bending direction of the display device is set in the range of 85° to 95° or -10° to 10°. The circularly polarizing plate according to claim 1, wherein the half-wavelength plate and the quarter-wavelength plate are bonded via an adhesive layer. The circularly polarizing plate according to claim 1 or 2, wherein the display device is an organic electroluminescence display device. The circularly polarizing plate according to claim 1 or 2, wherein the sign in the a*b* chromaticity coordinate of the hue of the reflected light obtained before and after bending does not change across the a* coordinate axis and the b* coordinate axis. A bendable display device is provided with: the circular polarizing plate as described in any one of items 1 to 4 of the patent application scope, and a bendable display panel. The bendable display device according to claim 5, comprising: a touch sensor disposed on the side of the circular polarizer facing the display panel; and A window film disposed on the opposite side of the circular polarizer to the side facing the display panel. The bendable display device described in claim 5 of the claim 5 includes a touch sensor disposed on the side opposite to the side facing the display panel of the circular polarizer.

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