KR20200085755A - Circular polarizer and display device - Google Patents

Abstract

The present invention relates to a circular polarizing plate used in a bendable display device having a polarizer and at least one retardation layer disposed on one side of the polarizer, wherein the color of the reflected light obtained before and after the bending is a ^* b ^* chromaticity coordinate. In a ^* coordinate axis and b ^* coordinate axis, the sign does not change.

Description

Circular polarizer and display device

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

This application claims priority based on Japanese Patent Application No. 2017-217107 filed in Japan on November 10, 2017 and Japanese Patent Application No. 2018-201206 filed in Japan on October 25, 2018, the contents of which are incorporated herein by reference. .

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

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

For this problem, therefore, in Patent Document 1 below, a retardation film showing predetermined optical properties is included, and the slow axis direction of the retardation film is adjusted to define an angle of 20 to 70 degrees with respect to the bending direction of the display device. Circular polarizing plates have been proposed. In addition, Patent Document 1 below discloses the use of a resin film such as Pure Ace WR (Polycarbonate Resin Film) as a retardation film showing predetermined optical properties.

In addition, in the following patent document 2, a retardation film including a 1/2 wavelength (λ/2) plate and a 1/4 wavelength (λ/4) plate is provided, and the λ/2 plate and the λ/4 plate each contain a liquid crystal compound. A circular polarizing plate has been proposed, which includes and is adjusted such that the slow axis direction of the retardation film is 75 to 105 degrees relative to the bending direction of the display device.

Patent Document 1: Japanese Patent Publication No. 2014-170221 Patent Literature 2: International Publication No. 2016/158300

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

On the other hand, the present invention can improve the visibility of the display device by the idea that not only the color change before and after the bend is reduced, but also that the color change is not noticeable before and after the bend. Said there is.

That is, an object of the present invention is to provide a circular polarizing plate capable of making the color change inconspicuous before and after bending and a flexible display device having the circular polarizing plate.

As a means for solving the above problems, according to an aspect of the present invention, as a circular polarizing plate used in a bendable display device, a polarizer, and at least one phase difference layer disposed on one side of the polarizer, before and after bending A circular polarizing plate is provided in which the color of the resulting reflected light does not change with the a ^* coordinate axis and the b ^* coordinate axis in a ^* b ^* chromaticity coordinates.

Further, in the circular polarizing plate, the retardation layer may be configured to include a quarter wave plate.

Further, in the circularly polarizing plate, the retardation layer may be configured to include a half wave plate.

Further, in the circular polarizing plate, the retardation layer may be configured to include a positive C plate.

Moreover, in the said circularly polarizing plate, the said retardation layer may consist of the layer which the liquid crystal compound hardened.

Further, in the circularly polarizing plate, a structure in which at least a portion of the display device is bent to a radius of curvature of 8 mm or less may be sufficient.

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

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

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

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

That is, the present invention has the following aspects.

[1] A circular polarizing plate used in a bendable display device, comprising a polarizer and at least one retardation layer disposed on one side of the polarizer, and the color of reflected light obtained before and after bending is determined by a ^* b ^* chromaticity coordinates. A circular polarizing plate characterized in that the sign does not change with the a ^* and b ^* coordinate axes in between.

[2] The circular polarizing plate according to [1], wherein the retardation layer includes a quarter wave plate.

[3] The circular polarizing plate according to [2], wherein the retardation layer includes a half wave plate.

[4] The circular polarizing plate as described in [2] or [3], wherein the retardation layer includes a positive C plate.

[5] The circular polarizing plate according to any one of [1] to [4], wherein the retardation layer comprises a layer in which a liquid crystal compound is cured.

[6] The circular polarizing plate according to any one of [1] to [5], wherein at least a portion of the display device is bent to a radius of curvature of 8 mm or less.

[7] The circular polarizing plate according to any one of [1] to [6], wherein the display device is an organic electroluminescent display device.

[8] A bendable display device comprising the circular polarizing plate according to any one of [1] to [7] and a bendable display panel.

[9] characterized by comprising a touch sensor disposed on a side of the circularly polarizing plate facing the display panel, and a window film disposed on a side opposite to the side of the circularly polarizing plate facing the display panel [8] The bendable display device described in.

[10] The bendable display device according to [8], comprising a touch sensor disposed on a side opposite to the side of the circularly polarizing plate facing the display panel.

As described above, according to the aspect of the present invention, it is possible to provide a circular polarizing plate capable of making the color change inconspicuous before and after bending and a flexible display device provided with the circular polarizing plate.

1 is a cross-sectional view showing a configuration of a circular polarizing plate according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a bendable display device provided with the circular polarizing plate shown in FIG. 1.
3 is a cross-sectional view showing the configuration of a circular polarizing plate according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a configuration of a bendable display device provided with the circular polarizing plate shown in FIG. 3.
5 is a cross-sectional view showing the configuration of an organic EL element.
6A is a schematic diagram for describing a curved state of a display device.
6B is a schematic diagram for describing a curved state of the display device.
6(c) is a schematic view for describing a curved state of the display device.
6D is a schematic view for describing a curved state of the display device.
7 is a schematic view for explaining a relationship between a bending direction of the display device illustrated in FIG. 2, an absorption axis direction of the polarizer, and a slow axis direction of the first retardation film.
8 is a schematic view for explaining a relationship between a bending direction of the display device illustrated in FIG. 4 and an absorption axis direction of the polarizer, and a slow axis direction of the λ/2 plate and a slow axis direction of the λ/4 plate.
9 is a ^* b ^* chromaticity coordinate diagram for explaining a change in color of reflected light obtained before and after bending of the circular polarizing plate.
10 is a cross-sectional view showing another configuration example of a bendable display device having a circular polarizing plate of the present invention.
11 is a ^* b ^* chromaticity coordinate diagram showing color change before and after bending with respect to Examples 1 to 12 and Comparative Examples 1 to 3.
12 is a ^* b ^* chromaticity coordinate diagram showing color change before and after bending in Examples 13-20.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to drawings.

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

[Circular Polarizing Plate]

(First embodiment)

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

As shown in Fig. 1, the circular polarizing plate 1A of this embodiment has a polarizer 2 and a first retardation film (first retardation layer) 3A arranged on one side of the polarizer 2 And a second retardation film (second retardation layer) 4A. In addition, protective films (protective layers) 5 and 6 are disposed on both sides of the polarizer 2, respectively.

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

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

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

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

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

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

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

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

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

By setting the transmittance of the visibility-adjusted monolith to 42% or more, the orthogonal color of the polarizing plate can be easily adjusted away from the neutral side, so that the color change before and after bending can be made inconspicuous. When it exceeds 50%, the polarization degree becomes too low, and the antireflection function may not be achieved in some cases. That is, if it is 50% or less, the polarization degree is not too low, and it is easy to achieve the antireflection function.

Since the orthogonal color of the polarizer 2 can be easily adjusted away from the neutral side by setting the transmittance of the visibility of the polarizer 2 to be monolithic to be 42% or more, the color of the reflected light obtained before and after the bending described later is a ^* b ^{* It} becomes easy to prevent the sign from being changed with a ^* coordinate axis and b ^* coordinate axis in chromaticity coordinates interposed therebetween. On the other hand, when the monophotometric correction unit transmittance of the polarizer 2 exceeds 50%, it is not preferable because the polarization degree becomes too low and the function as anti-reflection cannot be achieved.

The first retardation film 3A can be a positive A plate functioning as a quarter wavelength (λ/4) plate. The positive A plate has a relationship of Nx>Ny when the refractive index in the slow axis direction in the plane is Nx, the refractive index in the fast axis direction in the plane is Ny, and the refractive index in the thickness direction is Nz. Satisfies. The λ/4 plate has a function of converting linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light).

As long as the relationship of Nx>Ny is satisfied, the first retardation film 3A has any suitable refractive index ellipsoid. Preferably, the refractive index ellipsoid of the first retardation film 3A shows the relationship of Nx>Ny≥Nz (Nz represents the refractive index in the thickness direction). The Nz coefficient of the first retardation film 3A is preferably 1 to 2, more preferably 1 to 1.5, and even more preferably 1 to 1.3.

In addition, it is preferable that the first retardation film 3A exhibits reverse wavelength dispersion characteristics. Specifically, the in-plane retardation value Re(λ) at the wavelength λ[nm] has the relationship of Re(450)<Re(550)<Re(650), 100 nm≤Re(550)≤200 nm. Satisfies. By satisfying such a relationship, it is possible to achieve excellent reflection color in the front direction of the display device 10A described later. Re (550) is preferably in the range of 120 nm ≤ Re (550) ≤ 170 nm.

Although the thickness of the 1st retardation film 3A is not specifically limited, 0.5-10 micrometers is preferable and 0.5-5 micrometers is more preferable from a viewpoint that it is easy to remarkably make the effect of preventing wrinkles at the time of bending. 0.5-3 micrometers is more preferable. In addition, about the thickness of the 1st retardation film 3A, the thickness of arbitrary 5 points in a plane was measured, and these were arithmetic average.

The first retardation film 3A may include a film containing a resin exemplified as a material for the protective films 5 and 6 to be described later, a layer in which a liquid crystal compound is cured, and the like. When forming the 1st retardation film 3A with resin, a polycarbonate resin, a cyclic olefin resin, a styrene resin, and a cellulose resin are especially preferable. In the present embodiment, it is preferable that the first retardation film 3A includes a layer in which a liquid crystal compound is cured. The type of the liquid crystal compound is not particularly limited, and can be classified into a bar type (rod-like liquid crystal compound) and a disc type (disc-type liquid crystal compound, discotic liquid crystal compound) based on the shape. In addition, there are low molecular weight type and high molecular weight type, respectively. Here, the polymer generally refers to a polymerization degree of 100 or more (polymer physics and phase transition dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).

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

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

The first retardation film 3A is more preferably formed using a liquid crystal compound having a polymerizable group (rod-like liquid crystal compound or disc-like liquid crystal compound). Thereby, the change by the temperature of the optical characteristic or the change by humidity can be made small.

The liquid crystal compound may be a mixture of two or more kinds. In that case, it is preferable that at least one has two or more polymerizable groups. That is, the first retardation film 3A is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disc-shaped liquid crystal compound having a polymerizable group by polymerization, and such a layer is included in a layer cured by the liquid crystal compound. do. In this case, after layering, it is no longer necessary to exhibit liquid crystallinity.

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

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

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

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

Moreover, a polymerizable monomer may be contained in the composition from a point of uniformity and film strength of a coating film. Examples of the polymerizable monomer include radical polymerizable or cationic polymerizable compounds. Among them, polyfunctional radical polymerizable monomers are preferred.

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

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

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

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

The 1st phase difference film 3A may contain the alignment film which has a function which defines the orientation direction of a liquid crystal compound. The alignment film generally has a polymer as a main component. As a polymer material for an alignment film, there are many literatures, and many commercial products can be obtained. Especially, it is preferable to use polyvinyl alcohol or polyimide, and its derivatives as a polymer material, and it is especially preferable to use a modified or unmodified polyvinyl alcohol.

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

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

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

The second retardation film 4A can function as a positive C plate. The positive C plate satisfies the relationship of Nz>Nx≥Ny. By including the positive C plate, it is possible to reduce a change in color (color) of reflected light in a bent portion when the display device 10A described later is bent. The difference between the value of Nx and the value of Ny is preferably within 0.5% of the value of Ny, and more preferably within 0.3%. If it is within 0.5%, it can be considered that Nx = Ny substantially.

In the second retardation film 4A, it is preferable that the retardation value Rth(λ) in the thickness direction at the wavelength λ[nm] satisfies the relationship of -300 nm≤Rth(550)≤-20 nm, and -150 It is more preferable to satisfy the relationship of nm≤Rth(550)≤-20 nm.

Although the thickness of the 2nd retardation film 4A is not specifically limited, 0.5-10 micrometers is preferable and 0.5-5 micrometers is preferable at the point which can prevent wrinkles by the difference of the dimensional change in the front and back of a film at the time of bending. More preferably, 0.5 to 3 µm is more preferable. In addition, about the thickness of the 2nd retardation film 4A, the thickness of arbitrary 5 points in a plane was measured, and these were arithmetic average.

It is preferable that the 2nd retardation film 4A contains the layer hardened by the liquid crystal compound. Although the type of the liquid crystal compound is not particularly limited, the same material as exemplified as the material for the first retardation film 3A can be used. Especially, it is preferable that it is a layer in which the rod-shaped liquid crystal compound which has a polymerizable group or the disc-shaped liquid crystal compound which has a polymerizable group is fixed by polymerization. In this case, after layering, it is no longer necessary to exhibit liquid crystallinity.

Among the layers included in the circular polarizing plate 1A, it is preferable that the layer cured by the liquid crystal compound other than the polarizer 2 is one layer or two layers. When the retardation film is a layer in which the liquid crystal compound is cured, the thickness can be reduced, so that the dimensional change of the retardation layer when curved with the same diameter as compared with the use of a thick film type can be reduced, resulting in a retardation change. It is preferable because it can suppress.

In addition, regarding the 1st retardation film 3A and the 2nd retardation film 4A, it is not necessarily limited to the structure in which the above-mentioned liquid crystal compound contains the cured layer, For example, it stretches the film containing a thermoplastic resin ( It is also possible to use the 1st retardation film 3A and the 2nd retardation film 4A to which the above-mentioned phase difference value was given by uniaxial stretching or biaxial stretching, etc.).

The protective films 5 and 6 function as a protective layer for protecting the polarizer 2, and at least the outer surface of the polarizer 2 (a surface opposite to the side opposite to the first retardation film 3A) The protective film 5 is arrange|positioned at. Moreover, the protective film 6 may be arrange|positioned on the surface inside (the side opposite to the 1st retardation film 3A) of the polarizer 2.

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

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

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

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

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

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

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

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

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

The thickness of the protective films 5 and 6 is preferably 10 µm to 200 µm, more preferably 10 µm to 100 µm, further preferably 15 µm to 95 µm. The in-plane retardation value Re(550) of the protective films 5 and 6 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.

The outer protective film 5 is subjected to surface treatments such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment on the surface opposite to the side opposite to the polarizer 2, if necessary. It may be. The thickness of the protective film 5 in this case is 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, still more preferably 5 μm to 150 μm.

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

The adhesive layer 8 is an adhesive, for example, an active energy ray-curable adhesive (preferably an ultraviolet-curable adhesive) containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, or polyvinyl. An aqueous adhesive in which an adhesive component such as an alcohol-based resin is dissolved or dispersed in water can be used. In the circular polarizing plate 1A, by laminating the first retardation film 3A and the second retardation film 4A through the adhesive layer 8, it is possible to prevent wrinkles from being generated during bending. In addition, in the circular polarizing plate 1B, which will be described later, when the λ/2 plate 3B and the λ/4 plate 4B are laminated through the adhesive layer 8, wrinkles can also be prevented when bending. have.

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

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

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

When bonding the retardation films (3A, 4A) using an active energy ray-curable adhesive, after laminating the retardation film (3A) and the retardation film (4A) through the active energy ray-curable adhesive to become the adhesive layer 8, The adhesive layer is cured by irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays. Among them, ultraviolet rays are suitable, and as the light source in this case, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, or the like can be used. In the case of using a water-based adhesive, the retardation film 3A and the retardation film 4A are laminated through a water-based adhesive and then dried by heating.

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

The storage elastic modulus of the adhesive layer 8 at a temperature of 30°C is preferably 600 MPa to 4000 MPa, more preferably 700 MPa to 3500 MPa, further preferably 1000 MPa to 3000 MPa, and further 1500 MPa. It is most preferable that it is ∼3000 MPa. By bonding the retardation films 3A and 4A to each other with the hard adhesive layer 8 showing such a storage elastic modulus, it is possible to further prevent wrinkles from forming in the retardation layer during bending.

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

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

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

For the pressure-sensitive adhesive, a filler, a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber, an antistatic agent, a silane coupling agent, etc., including tackifier, plasticizer, glass fiber, glass beads, metal powder, and other inorganic powders, if necessary , Various additives may be appropriately blended.

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

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

(Second embodiment)

As a second embodiment of the present invention, a bendable display device 10B including, for example, the circular polarizing plate 1B shown in FIG. 3 and the circular polarizing plate 1B shown in FIG. 4 will be described. Here, FIG. 3 is a cross-sectional view showing the configuration of the circular polarizing plate 1B. 4 is a cross-sectional view showing the configuration of a bendable display device 10B having a circular polarizing plate 1B. In the following description, parts equivalent to the circularly polarizing plate 1A will be omitted, and the same reference numerals will be given in the drawings.

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

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

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

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

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

The thickness of the λ/2 plate 3B is not particularly limited, but is preferably 0.5 to 10 µm, more preferably 0.5 to 5 µm, and 0.5 to 3 µm from the viewpoint of easy to remark the effect of preventing wrinkles. Μm is more preferred. In addition, regarding the thickness of the λ/2 plate 3B, the thickness of any five points in the plane was measured, and these were arithmetic average. In the case of a resin film that has been conventionally used, wrinkles are hardly generated in the first place.

It is preferable that the λ/2 plate 3B includes a layer in which the liquid crystal compound is cured. The type of the liquid crystal compound is not particularly limited, and can be classified into a bar type (rod-like liquid crystal compound) and a disc type (disc-type liquid crystal compound, discotic liquid crystal compound) based on the shape. In addition, there are low molecular weight type and high molecular weight type, respectively. Here, the polymer generally refers to a polymerization degree of 100 or more (polymer physics and phase transition dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).

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

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

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

The liquid crystal compound may be a mixture of two or more kinds. In that case, it is preferable that at least one has two or more polymerizable groups. That is, it is preferable that the λ/2 plate 3B is a layer in which a rod-shaped liquid crystal compound having a polymerizable group or a disc-shaped liquid crystal compound having a polymerizable group is fixed by polymerization. In this case, after layering, it is no longer necessary to exhibit liquid crystallinity.

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

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

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

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

Moreover, a polymerizable monomer may be contained in the composition from a point of uniformity and film strength of a coating film. Examples of the polymerizable monomer include radical polymerizable or cationic polymerizable compounds. Among them, polyfunctional radical polymerizable monomers are preferred.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In addition, regarding the λ/2 plate 3B and the λ/4 plate 4B, the liquid crystal compound described above is not necessarily limited to a configuration including a cured layer, and for example, a film containing a thermoplastic resin is stretched ( It is also possible to use the 1st retardation film 3A and the 2nd retardation film 4A to which the above-mentioned phase difference value was given by uniaxial stretching or biaxial stretching, etc.).

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

[Display device]

The circular polarizing plates 1A, 1B of this embodiment are used for the bendable display devices 10A, 10B as shown in Figs. Specific examples of the bendable display devices 10A and 10B include an organic EL display device, a liquid crystal display device using circular polarization (typically, a liquid crystal display device in VA (Vertical Alignment) mode), a MEMS (Micro Electro Mechanical Systems) display, and the like. Can be heard. Among them, the circularly polarizing plates 1A, 1B of the present embodiment are suitably used for a bendable organic EL display device.

Specifically, the display devices 10A, 10B of the present embodiment include the bendable display panel 20 and the circular polarizing plate arranged on the viewer side of the display panel 20, as shown in FIGS. 2 and 4. 1A, 1B). In the display device 10A shown in FIG. 2, the circular polarizing plate 1A has a PSA layer 9 such that the polarizer 2 is on the viewing side and the second retardation film 4A is on the display panel 20 side. ) To the viewer side of the display panel 20. On the other hand, in the display device 10B shown in FIG. 4, the circular polarizing plate 1B has a PSA layer 9 such that the polarizer 2 is on the viewer side and the retardation layer RF is on the display panel 20 side. ) To the viewer's side of the display panel 20.

In the display device 10A of the first embodiment, when external light is incident from the viewing side of the display panel 20, light passing through the polarizer 2 becomes linearly polarized light. The linearly polarized light passes through the first retardation film 3A and the second retardation film 4A, which are lambda /4 plates, and become circularly polarized light. The light of the circularly polarized light is reflected by the display panel 20, so that the circularly polarized light is inverted from the time of incidence. When the circularly polarized light reflected from the display panel 20 passes through the first retardation film 3A and the second retardation film 4A which are again lambda /4 plates, they become linearly polarized light orthogonal to the time of incidence. . Therefore, the light of this linearly polarized light is blocked by the polarizer 2. As a result, the influence of external light reflection can be suppressed.

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

[Organic EL element]

An example of the display panel 20 includes, for example, an organic EL element 200 as shown in FIG. 5. Here, FIG. 5 is a cross-sectional view showing the configuration of the organic EL element 200.

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

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

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

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

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

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

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

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

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

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

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

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

In addition, although the aspect in which the organic EL element 200 is used is illustrated in the display panel 20, it is not necessarily limited to such an aspect, and the display devices 10A and 10B to which the present invention is applied are, for example, An aspect including the display panel 20 including the liquid crystal display element and the circularly polarizing plates 1A, 1B disposed on the viewer side of the display panel 20 may be used.

[Bending direction of display device]

The display devices 10A and 10B of this embodiment also include a bent state (a state in which the bend is fixed) as shown in Figs. 6(a) to 6(d). Here, FIGS. 6(a) to 6(d) are schematic views for explaining the bending state of the display devices 10A and 10B.

Specifically, the display devices 10A and 10B may be bent at the central portion, for example, as shown in the folding expressions shown in FIGS. 6A and 6B. In addition, from the viewpoint of ensuring the design performance and the display screen as much as possible, it may be bent at the end as shown in Figs. 6(c) and 6(d).

Further, the display devices 10A and 10B may be bent along the long length direction or bent along the short length direction as shown in Figs. 6(a) to 6(d). That is, the display devices 10A and 10B need only be bent in a specific portion (eg, some or all of the four corners in an oblique direction) depending on the application.

At least a portion of the display devices 10A and 10B preferably has 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. The display devices 10A and 10B of this embodiment reduce the change in color (color) of reflected light in a state of being bent with such a very small radius of curvature, and wrinkles are less likely to occur on the circular polarizing plates 1A and 1B. At this time, 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 of the display device 10A (direction perpendicular to the bending start line L), the absorption axis direction of the polarizer 2, and the slow axis direction of the first retardation film 3A is shown in FIG. 7A. , (b). 7(a) and 7(b) are schematic diagrams for explaining the relationship between the bending direction of the display device 10A, the absorption axis direction of the polarizer 2, and the slow axis direction of the first retardation film 3A. . 7(a) and 7(b), the absorption axis direction of the polarizer 2 is indicated by a “solid line”, and the slow axis direction of the first retardation film 3A is indicated by a “dash line”.

As shown in (a) and (b) of FIG. 7, the display device 10A includes at least a flat portion 10a and a linear curved start line L located at an end of the flat portion 10a ( It has a bent portion 10b bent along a direction perpendicular to the bend start line L (bending direction) from the two-dot chain line shown in Figs. 7A and 7B. In this case, the bending direction of the display device 10A is linear when the display device 10A is viewed from the normal direction of the flat portion 10a (Z-axis direction in FIGS. 7A and 7B ). Corresponds to the direction orthogonal to the bending start line L of (Y-axis direction in Fig. 7 (a), (b)).

In the display device 10A of the present embodiment, the bending direction of the display device 10A with respect to the absorption axis direction (0°) of the polarizer 2 is -5° to 5° or 85° with the counterclockwise direction positive. It is set to a range of -95°, more preferably 0° (see Fig. 7(a).) or 90° (see Fig. 7(b).).

In the display device 10A of the present embodiment, the slow axis direction of the first retardation film 3A with respect to the absorption axis direction (0°) of the polarizer 2 is 40° to 50° with the counterclockwise direction being positive or It is set in the range of -50° to -40°, more preferably 45° or -45° (see (a) and (b) in Fig. 7).

With respect to the bending direction of the display device 10A, the absorption axis direction of the polarizer 2 is an angle with respect to the bending direction of the display device 10A, as shown in Figs. 6(a) to 6(d). It is set to achieve (α). That is, the circularly polarizing plate 1A is disposed on the surface of the display panel 20 such that the direction of the absorption axis of the polarizer 2 is the angle α with respect to the bending direction of the display device 10A.

Specifically, this angle α is in the range of -5° to 5° or 85° to 95°, more preferably 0° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer 2, more preferably 0° Or it is set to be 90°. By adjusting the absorption axis direction (angle α) of the polarizer 2 to be within such a range, color change due to bending can be suppressed.

The relationship between the bending direction of the display device 10B (the direction perpendicular to the bending start line L) and the absorption axis direction of the polarizer 2, and the slow axis direction of the λ/2 plate 3B and λ/4 plate ( The relationship of the slow axis direction of 4B) will be described with reference to Figs. 8A and 8B. Here, FIGS. 8A and 8B show the relationship between the bending direction of the display device 10B and the absorption axis direction of the polarizer 2, and the slow axis direction and the λ/4 plate of the λ/2 plate 3B. It is a schematic diagram for explaining the relationship of the slow axis direction of (4B). 8(a) and 8(b), the direction of the absorption axis of the polarizer 2 is indicated by a "dash line", the direction of the slow axis of the λ/2 plate 3B is indicated by a "dotted chain line", and λ The slow axis direction of the 4th plate 4B is indicated by a "solid line".

The display device 10B includes, as shown in FIGS. 8A and 8B, at least a flat portion 10a and a linear curved start line L located at an end portion of the flat portion 10a ( It has a bent portion 10b bent along a direction orthogonal to the bend start line L (bending direction) from the two-dot chain line shown in Figs. 8A and 8B. In this case, the bending direction of the display device 10B is a straight line when the display device 10B is viewed from the normal direction of the flat portion 10a (Z-axis direction in FIGS. 8A and 8B). Corresponds to the direction orthogonal to the bending start line L of (Y-axis direction in Fig. 8 (a), (b)).

In the display device 10B of this embodiment, the bending direction of the display device 10B is positively changed from -10° to 10° with the anti-clockwise direction of the display device 10B relative to the slow axis direction (0°) of the λ/4 plate 4B. (0° in FIG. 8(a)) or 80° to 100° (90° in FIG. 8(b)), preferably -5° to 5° or 85° to 95°, more preferably Is set to 0° or 90°.

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

In addition, the slow axis direction of the λ/4 plate 4B is set to form an angle β with respect to the absorption axis direction of the polarizer 2. That is, the circular polarizing plate 1B is disposed on the surface of the display panel 20 such that the direction of the slow axis of the λ/4 plate 4B is the angle β with respect to the absorption axis direction of the polarizer 2. Here, the angle α and the angle β are angles in which the counterclockwise direction is positive, based on the absorption axis of the polarizer 2. The angle β is -20° to 20° with the slow axis direction of the λ/4 plate 4 in the counterclockwise direction relative to the absorption axis direction (0°) of the polarizer 2 (Fig. 8 ( In a) and (b), the range is -15°).

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

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

By adjusting the slow axis direction (angle (α)) of the λ/2 plate 3B and the slow axis direction (angle (β)) of the λ/4 plate 4B so as to be in this range, color change due to bending is suppressed. can do.

[Color change of circular polarizer before and after bending]

By the way, this embodiment of a circularly polarizing plate (1A, 1B) is that the color of the reflected light obtained before and after the bending CIE1976L ^* a ^* b ^* color space a ^* b ^* between the a ^* axis and b ^* axis in a chromaticity coordinates It is characterized in that the sign does not change. That is, the color of the reflected light obtained before and after the bending is set to a value that does not span the a ^* coordinate axis in the a ^* b ^* chromaticity coordinates and does not span the b ^* coordinate axis. Accordingly, even if the color of the reflected light obtained before and after bending is changed, the change in color can be made inconspicuous.

Further, even if at least one of the a ^* value and the b ^* value is 0 before and after the start of bending, if there is no change in the other sign, it is assumed that the sign does not change before and after the bend. That is, in this case, it is assumed that the a ^* and b ^* axes are not passed.

When the display devices 10A, 10B are bent so that the circularly polarizing plates 1A, 1B of the present embodiment are the outer side (OUT), and the circularly polarizing plates 1A, 1B of the present embodiment are displayed as the inner side (IN) In at least one case in which the devices 10A and 10B are bent, the color of the reflected light obtained before and after the bend changes sign with a ^* coordinate axis and b ^* coordinate axis in a ^* b ^* chromaticity coordinate interposed therebetween. It is preferable not to, and it is more preferable that the sign does not change in any case.

Specifically, the color change of the reflected light obtained before and after the bending of the circular polarizing plates 1A and 1B will be described with reference to FIG. 9. Here, FIG. 9 is a ^* b ^* chromaticity coordinate diagram for explaining the color change of the reflected light obtained before and after the bending of the circular polarizing plates 1A, 1B.

As for the color change of the reflected light obtained before and after the bending of the circular polarizing plates 1A and 1B, it is preferable to use a method of measuring the color by removing specular light, called the SCE method, because it is a color evaluation close to that seen by the eye. .

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

·Light source: D65 light source

·Measurement diameter: 8 mmφ

Vision: 2°

Geometry: Geometry c

In addition, in the present embodiment, the aluminum reflector is disposed on the surface opposite to the polarizer 2 side of the circular polarizing plates 1A, 1B through the PSA layer 9 to measure color by the SCE method before bending. . That is, in the case of the circular polarizing plate 1A shown in Fig. 1, an aluminum reflector is disposed on the side of the second retardation film 4A through the PSA layer 9. On the other hand, in the case of the circular polarizing plate 1B shown in Fig. 3, an aluminum reflector is disposed on the side of the retardation layer (RF) through the PSA layer (9). Thereafter, the radius of curvature when bending the circularly polarizing plates 1A, 1B is 5 mm, and at least one bending is applied, and then, on the side opposite to the polarizer 2 side of the circularly polarizing plates 1A, 1B. An aluminum reflector is disposed to measure color by the SCE method after bending. Then, regarding the color change of the reflected light obtained before and after the bending of the circular polarizing plates 1A and 1B, it is confirmed that the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween.

In the present embodiment, with respect to the color of the reflected light obtained before and after bending, the case where the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates is shown in, for example, FIG. 9. In a ^* b ^* chromaticity coordinate diagram, it is agreed that a ^* b ^* chromaticity coordinate in the a ^* coordinate axis and b ^* coordinate axis are not passed an upper limit. In this case, even if the colors of the circular polarizing plates 1A and 1B are changed before and after bending, the change in color can be made inconspicuous. On the other hand, if a ^* b ^* chromaticity coordinates have an a ^* coordinate axis or a b ^* coordinate axis interposed therebetween, an upper limit is easily seen, and the change in color becomes easy to see ("x" in Fig. 9).

In the circular polarizing plates 1A, 1B of the present embodiment, the color of the reflected light obtained before and after the bending is set to a value that does not span the a ^* coordinate axis and the b ^* coordinate axis in a ^* b ^* chromaticity coordinates. The color can be changed by adjusting the colors of the circularly polarizing plates 1A, 1B or by adjusting the phase difference values of the circularly polarizing plates 1A, 1B. In addition, adjusting the wavelength dispersibility of the retardation film is also effective for color control. For example, when the phase difference values of the circularly polarizing plates 1A and 1B are raised, the a ^* value and the b ^* value are lowered, and when the phase difference of the circularly polarizing plates 1A and 1B is lowered, the a ^* value and the b ^* value are increased.

The color of the polarizer (a laminate comprising the polarizer 2 and the protective films 5, 6 bonded to one or both sides thereof through an adhesive layer 8) is represented by Hunter 1948 Lab color space, orthogonal before bending It is preferable that a value is -10 or more and 10 or less, and it is more preferable that it is -5 or more and 5 or less. Moreover, it is preferable that orthogonal b value before bending is -25 or more and 0 or less, and it is more preferable that it is -20 or more and 0 or less. The setting conditions when measuring the color of the polarizing plate can be set as follows.

·Light source: C light source

Vision: 2°

If it is the above-mentioned range, there is no problem in the initial reflection color, and it is easy to adjust so that the upper limit before and after the bending is not exceeded by the combination of the bending direction and the retardation value of the retardation film.

In addition, in the circular polarizing plates 1A, 1B of the present embodiment, in the reflection color before bending, the a ^* value is preferably -8 or more and 8 or less, and more preferably -5 or more and 5 or less. On the other hand, in the circular polarizing plates 1A, 1B of the present embodiment, the b ^* value in the reflection color before bending is preferably -10 or more and 0 or less, and more preferably -5 or more and 0 or less.

In the circular polarizing plates 1A, 1B of the present embodiment, in the reflection color after bending, the a ^* value is preferably -8 or more and 8 or less, and more preferably -5 or more and 5 or less. On the other hand, in the circular polarizing plates 1A, 1B of the present embodiment, the b ^* value in the reflection color after bending is preferably -10 or more and 0 or less, and more preferably -5 or more and 0 or less.

In the circular polarizing plates 1A, 1B of the present embodiment, it is preferable that the color difference values obtained from the difference Δa ^* , Δb ^* between the a ^* value and the b ^* value in the reflection color before and after bending are preferably 0 or more and 5 or less, It is more preferable that it is 3 or less. Here, the color difference value is calculated from [(Δa ^* ) ² +(Δb ^* ) ² ] ^1/2 .

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

For example, a configuration including a touch sensor as an input means of the display devices 10A and 10B may be used. Specifically, as in the display device 30 shown in FIG. 10, in addition to the structures of the display devices 10A and 10B, a structure including the touch sensor 40 and the window film 50 may also be used. Here, FIG. 10 is a cross-sectional view showing another configuration example of the bendable display device 30 having the circular polarizing plates 1A and 1B. The circular polarizing plate 1A shown in FIG. 1 may be used for the circular polarizing plate, or the circular polarizing plate 1B shown in FIG. 3 may be used.

In the display device 30 shown in FIG. 10, the touch sensor 40 is preferably disposed on the side facing the display panel 20 of the circularly polarizing plates 1A, 1B, and the window film 50 It is preferable that the silver is disposed on the opposite side to the side facing the display panel 20 of the circularly polarizing plates 1A, 1B. If the circularly polarizing plates 1A and 1B are present on the viewing side of the touch sensor 40, the pattern of the touch sensor 40 becomes difficult to visualize, and the visibility of the image displayed on the display panel 20 is improved, which is preferable. .

Therefore, in the display device 30 shown in FIG. 10, the display panel 20, the touch sensor 40, the circular polarizing plates 1A, 1B, and the window film 50 are laminated in the order of an adhesive or an adhesive. It has an organized configuration. In addition, it is also possible to provide a light-shielding pattern, which will be described later, on at least one surface of any one layer of the window film 50, the circular polarizing plates 1A, 1B, and the touch sensor 40.

In addition, the stacking order of the touch sensor 40 and the window film 50 is not necessarily limited to the above-described configuration, for example, the display panel 20, the circular polarizing plates 1A, 1B, the touch sensor 40, It may also be of a laminated structure in the order of the window film 50.

As for the window film 50, the protective film 5 constituting the circular polarizing plates 1A, 1B described above may be used, and the window film 50 is a protective film 5 of the circular polarizing plates 1A, 1B. ).

In addition, although not shown in the present invention, in addition to the configuration of the display devices 10A and 10B, the touch sensor 40 is disposed on the opposite side to the side facing the display panel 20 of the circular polarizing plates 1A and 1B. It can also be set as the provided structure.

(Window film)

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

The window film 50 has a bendable transparent base material 51 and a hard coat layer 52 provided on at least one surface of the transparent base material 51. In the display device 30 shown in FIG. 10, the hard coat layer 52 constituting the window film 50 is provided on the surface opposite to the circular polarizing plates 1A, 1B of the transparent base material 51. The hard coat layer 52 is an outermost layer of the display device 30 and is in contact with the outside air (air). Further, the hard coat layer 52 may be provided on the surface of the circular polarizing plates 1A and 1B of the transparent base material 51. Further, the hard coat layer 52 may be provided only on one side of the transparent substrate 51 or may be provided on both sides of the transparent substrate 51.

(Transparent description)

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

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

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

It is also preferable to disperse inorganic particles such as silica, organic fine particles, and rubber particles in the polymer film. In addition, colorants such as pigments and dyes, fluorescent brighteners, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents, etc. may be included.

(Hard coat layer)

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

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

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

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

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

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

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

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

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

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

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

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

Examples of the active energy ray radical polymerization initiator include a type 1 radical polymerization initiator that generates radicals by decomposition of molecules, and a type 2 radical polymerization initiator that coexists with tertiary amines to generate radicals through a hydrogen drawing reaction, each independently or It can also be used in combination.

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

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

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

(Touch sensor)

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

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

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

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

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

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

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

For the sensing pattern, a well-known transparent electrode material can be applied. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly(3,4-ethylenedioxythiophene)), carbon nano And tubes (CNT), graphene, and metal wires. Moreover, these can be used individually or in mixture of 2 or more types. Among them, it is preferable to use ITO.

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

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

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

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

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

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

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

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

(glue)

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

(adhesive)

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

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

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

(Shading pattern)

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

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

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

Example

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

[Example 1]

(Production of polarizer)

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

(Protective film)

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

(First retardation film)

As the first retardation film, a film comprising a layer in which the liquid crystal compound is cured and an alignment film was used. The first retardation film was a λ/4 plate, Re(450)/Re(550) was less than 1.0, and Re(650)/Re(550) was over 1.0.

(2nd retardation film)

As the second retardation film, a film comprising a layer in which the liquid crystal compound was cured and an alignment film was used. This second retardation film is a positive C plate.

(Ultraviolet curing adhesive)

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

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

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

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

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

1,4-diethoxynaphthalene: 2 parts by mass

(Production of circular polarizing plate)

The polarizer, the protective film, the 1st retardation film, and the 2nd retardation film were each cut out to 200 mm x 300 mm, and the protective film was stuck on both surfaces of a polarizer through a polyvinyl alcohol adhesive. The first retardation film and the second retardation film were pasted through the ultraviolet curing adhesive (adhesive layer). Further, the first retardation film and the protective film were pasted through an acrylic adhesive layer (PSA layer). An acrylic pressure-sensitive adhesive layer (PSA layer) with a release film was adhered to the second retardation film. As described above, a circular polarizing plate was prepared in which a protective film, a polarizer, a protective film, a PSA layer, a first retardation film, a UV adhesive layer, a second retardation film, and a PSA layer were sequentially stacked.

The first retardation film (λ/4 plate) is attached to the polarizer so that its slow axis direction becomes -45° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction (the direction orthogonal to the bending start line L) of the circularly polarizing plate becomes -45° with respect to the absorption axis direction (0°) of the polarizer, and the first phase difference film (λ/4 plate) It is adjusted to be 0° with respect to the slow axis direction. Then, the produced circular polarizing plate was trimmed to a size of 20 mm x 80 mm.

(Preparation of evaluation samples)

After removing the release film from the circular polarizing plate of Example 1, the adhesive side was adhered to the surface of the mat of aluminum foil (manufactured by UACJ, trade name "My foil (registered trademark)") to obtain a sample for evaluation. The evaluation sample obtained by measuring the color before and after bending and observing the color change before and after bending was performed on the sample for evaluation thus obtained.

(Color measurement)

First, regarding the sample for evaluation, the reflection color was measured by the SCE method before bending to obtain a ^* and b ^* values before bending. Thereafter, the mandrel with a diameter of 5 mm was pressed against the side of the organic EL display device, and the circularly polarizing plate was bent to the outside (OUT) with respect to the aluminum foil along the circumferential surface of the mandrel. Then, after bending, the bending state was eliminated (in a flat state) to measure the reflection color by the SCE method to obtain a ^* and b ^* values after bending.

(Observation of color)

The color feeling before and after the bending was visually observed to evaluate the ease of viewing the color change. In Table 1, the evaluation was set to A when the change in color was difficult to be recognized, and the evaluation was set to B when it was easy to recognize.

Hereinafter, Table 1 shows a summary of Example 1. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 1, it was confirmed that with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign was not changed with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

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

First, ultraviolet rays used to bond the first retardation film to the second retardation film using a coating machine (bar coater, manufactured by Daiichi Rika Co., Ltd.) on one surface of a cyclic polyolefin resin film having a thickness of 50 μm. A curable adhesive was coated, and a cyclic polyolefin-based resin film having a thickness of 50 µm was further laminated on the coated surface.

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

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

[Example 2]

In Example 2, the bending direction of the circular polarizing plate was adjusted to be 45 degrees with respect to the absorption axis direction (0 degrees) of the polarizer, and 90 degrees with respect to the slow axis direction of the first retardation film (λ/4 plate). Except for this, samples for evaluation in the same manner as in Example 1 were produced. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Hereinafter, Table 1 shows a summary of Example 2. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 2, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 3]

In Example 3, the bending direction of the circular polarizer was adjusted to be -45° with respect to the absorption axis direction (0°) of the polarizer, and 0° with respect to the slow axis direction of the first retardation film (λ/4 plate). , A sample for evaluation in the same manner as in Example 1 was produced except that the phase difference value of the λ/4 plate was changed. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Table 1 below summarizes Example 3. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 3, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 4]

(λ/2 edition)

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

(λ/4 version)

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

(Production of circular polarizing plate)

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

In addition, the λ/4 plate is affixed to the polarizer so that its slow axis direction becomes -15° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be 45° with respect to the absorption axis direction (0°) of the polarizer, and to be 60° with respect to the slow axis direction of the λ/4 plate. Then, the produced circular polarizing plate was trimmed to a size of 20 mm x 80 mm.

After the release film was removed from the circularly polarizing plate of Example 4, the adhesive side was adhered to the surface of the mat of aluminum foil (manufactured by UACJ, trade name "My foil (registered trademark))" to obtain a sample for evaluation. The evaluation sample of the same formula as in Example 1 was performed on the sample for evaluation thus obtained.

Table 1 below summarizes Example 4 below. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 4, regarding the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, it was confirmed that the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 5]

In Example 5, Example except that the bending direction of the circular polarizing plate was adjusted to be -45° with respect to the absorption axis direction (0°) of the polarizer, and -30° with respect to the slow axis direction of the λ/4 plate. A sample for evaluation in the same manner as 4 was produced. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Table 1 below shows the summary of Example 5. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 5, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 6]

In Example 6, the phase difference of the λ/4 plate was adjusted so that the bending direction of the circularly polarizing plate became 45° with respect to the absorption axis direction (0°) of the polarizer, and 60° with respect to the slow axis direction of the λ/4 plate. Samples for evaluation in the same manner as in Example 4 were produced except that the values were changed. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Table 1 below summarizes Example 6. 11, the color change before and after the bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 6, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 7]

In Example 7, the bending direction of the circularly polarizing plate was adjusted to be -45° with respect to the absorption axis direction (0°) of the polarizer, and -30° with respect to the slow axis direction of the λ/4 board, so that the λ/4 board A sample for evaluation of the same formula as in Example 4 was produced except that the phase difference value of was changed. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 7. 11, the color change before and after bending is shown in a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 7, it was confirmed that the color change of the reflected light obtained before and after the bending of the circularly polarizing plate did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates. In addition, it was confirmed that the change in color was inconspicuous.

[Example 8]

In Example 8, the bending direction of the circularly polarizing plate was adjusted to be 0° with respect to the absorption axis direction (0°) of the polarizer, and adjusted to be 45° with respect to the slow axis direction of the first retardation film (λ/4 plate). Except for this, samples for evaluation in the same manner as in Example 1 were produced. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Hereinafter, Table 1 shows a summary of Example 8. 11, the color change before and after the bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 8, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 9]

In Example 9, the bending direction of the circularly polarizing plate was adjusted to be 90° with respect to the absorption axis direction (0°) of the polarizer, and -45° with respect to the slow axis direction of the first retardation film (λ/4 plate). Except for that, samples for evaluation in the same manner as in Example 1 were produced. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Hereinafter, Table 1 shows a summary of Example 9. 11 shows that the color change before and after the bending in Example 9 is shown in the a*b* chromaticity coordinate diagram.

In Example 9, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 10]

In Example 10, Example 4 except that the bending direction of the circularly polarizing plate was adjusted to be -15° with respect to the absorption axis direction (0°) of the polarizer and 0° with respect to the slow axis direction of the λ/4 plate. The sample for evaluation of the same formula was produced. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Table 1 below summarizes Example 10. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 10, it was confirmed that with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 11]

In Example 11, apart from Example 1, the following first retardation film was used as a λ/4 plate. Moreover, the 1st retardation film and the 2nd retardation film were stuck together by the acrylic adhesive layer (PSA layer). The 1st retardation film was arrange|positioned so that the slow axis may make an angle of -45 degrees with respect to the absorption axis of a polarizer. Otherwise, a circular polarizing plate was produced in the same manner as in Example 1.

(First retardation film)

As the first retardation film, a film obtained by uniaxially stretching a film containing a resin containing polycarbonate was used. The in-plane retardation value Re(550) of this third retardation film was 143.5 nm, Re(450)/Re(550) was less than 1.0, and Re(650)/Re(550) exceeded 1.0.

In Example 11, the bending direction of the circularly polarizing plate was adjusted to be 0° with respect to the absorption axis direction (0°) of the polarizer, and 45° with respect to the slow axis direction of the first retardation film (λ/4 plate). Except for this, samples for evaluation in the same manner as in Example 1 were produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 11. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 11, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 12]

In Example 12, the bending direction of the circular polarizing plate was adjusted to be 45 degrees with respect to the absorption axis direction (0 degrees) of the polarizer, and 90 degrees with respect to the slow axis direction of the first retardation film (λ/4 plate). Except for this, samples for evaluation in the same manner as in Example 11 were produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent outward with respect to the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 12. 11, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 12, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 13]

In Example 13, a λ/2 plate and a λ/4 plate were bonded to a λ/2 plate and a λ/4 plate through an acrylic pressure-sensitive adhesive layer (PSA layer) using a film containing a cyclic olefin resin, respectively. In addition, the λ/4 plate is affixed to the polarizer so that its slow axis direction becomes -15° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be 75° with respect to the absorption axis direction (0°) of the polarizer and 90° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation in the same manner as in Example 4 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 13. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 13, regarding the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, it was confirmed that the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 14]

In Example 14, the lambda /4 plate is attached to the polarizer so that the slow axis direction becomes -15° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be -15° with respect to the absorption axis direction (0°) of the polarizer and 0° with respect to the slow axis direction of the λ/4 plate. Other than that, the evaluation sample similar to Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Table 1 below summarizes Example 14. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 14, it was confirmed that with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 15]

In Example 15, the lambda /4 plate is attached to the polarizer so that the slow axis direction becomes -15° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be -45° with respect to the absorption axis direction (0°) of the polarizer, and -30° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation of the same formula as in Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 15. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 15, it was confirmed that the color change of the reflected light obtained before and after the bending of the circularly polarizing plate did not change the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates. In addition, it was confirmed that the change in color was inconspicuous.

[Example 16]

In Example 16, the lambda /4 plate is attached to the polarizer so that the slow axis direction becomes -15° with the counterclockwise direction positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be 45° with respect to the absorption axis direction (0°) of the polarizer, and to be 60° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation of the same formula as in Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Table 1 below summarizes Example 16. 12, the color change before and after the bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 16, it was confirmed that with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 17]

In Example 17, the λ/4 plate was attached to the polarizer so that the slow axis direction was positively counterclockwise from the absorption axis direction (0°) of the polarizer to -15°. In addition, the bending direction of the circularly polarizing plate is adjusted to be 75° with respect to the absorption axis direction (0°) of the polarizer and 90° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation of the same formula as in Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent outward with respect to the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 17. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 17, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 18]

In Example 18, the lambda /4 plate is attached to the polarizer so that the slow axis direction becomes -15° with the counterclockwise direction positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be -15° with respect to the absorption axis direction (0°) of the polarizer and 0° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation of the same formula as in Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent outward with respect to the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 18. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 18, the color change of the reflected light obtained before and after the bending of the circularly polarizing plate was confirmed that the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 19]

In Example 19, the lambda /4 plate is attached to the polarizer so that the slow axis direction becomes -15° with the counterclockwise positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be -45° with respect to the absorption axis direction (0°) of the polarizer, and -30° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation of the same formula as in Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent outward with respect to the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 19. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 19, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circular polarizing plate, the sign did not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Example 20]

In Example 20, the lambda /4 plate is attached to the polarizer so that the slow axis direction becomes -15° with the counterclockwise direction positive from the absorption axis direction (0°) of the polarizer. In addition, the bending direction of the circularly polarizing plate is adjusted to be 45° with respect to the absorption axis direction (0°) of the polarizer, and to be 60° with respect to the slow axis direction of the λ/4 plate. Other than that, a sample for evaluation of the same formula as in Example 13 was produced. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent outward with respect to the aluminum foil along the circumferential surface of the mandrel.

Hereinafter, Table 1 shows a summary of Example 20. 12, the color change before and after bending is shown in the a ^* b ^* chromaticity coordinate diagram in FIG.

In Example 20, regarding the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, it was confirmed that the sign does not change with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was confirmed that the change in color was inconspicuous.

[Comparative Example 1]

In Comparative Example 1, the bending direction of the circularly polarizing plate was adjusted to be 45° with respect to the absorption axis direction (0°) of the polarizer, and 90° with respect to the slow axis direction of the first retardation film (λ/4 plate). , A sample for evaluation in the same manner as in Example 1 was produced except that the phase difference value of the λ/4 plate was changed. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Table 1 below summarizes Comparative Example 1 below. Also, with respect to Comparative Example 1, Fig. 11 shows the color change before and after bending in the a ^* b ^* chromaticity coordinate diagram.

In Comparative Example 1, it was confirmed that the color change of the reflected light obtained before and after the bending of the circularly polarizing plate was changed with the a ^* coordinate axis and the b ^* coordinate axis in a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was possible to easily confirm the change in color.

[Comparative Example 2]

In Comparative Example 2, the bending direction of the circularly polarizing plate was adjusted to be 45° with respect to the absorption axis direction (0°) of the polarizer, and to be 60° with respect to the slow axis direction of the λ/4 board. A sample for evaluation of the same formula as in Example 4 was produced except that the phase difference value was changed. And the evaluation test of the same formula as Example 1 was performed about this evaluation sample.

Table 1 below summarizes Comparative Example 2. 11 shows the color change before and after the bending in Comparative Example 2 in the a ^* b ^* chromaticity coordinate diagram.

In Comparative Example 2, it was confirmed that, with respect to the color change of the reflected light obtained before and after the bending of the circularly polarizing plate, the sign was changed with the a ^* coordinate axis and the b ^* coordinate axis in the a ^* b* chromaticity coordinates interposed therebetween. In addition, it was possible to easily confirm the change in color.

[Comparative Example 3]

In Comparative Example 3, the bending direction of the circularly polarizing plate was adjusted to be -45° with respect to the absorption axis direction (0°) of the polarizer, and -30° with respect to the slow axis direction of the λ/4 plate, so that λ/4 A sample for evaluation in the same manner as in Example 4 was produced except that the phase difference value of the plate was changed. And the evaluation test of the same formula as Example 1 was performed about this sample for evaluation, except that the circular polarizing plate was bent to the inside (IN) of the aluminum foil along the circumferential surface of the mandrel.

Table 1 below summarizes Comparative Example 3 below. Also, with respect to Comparative Example 3, Fig. 11 shows the color change before and after bending in the a ^* b ^* chromaticity coordinate diagram.

In Comparative Example 3, it was confirmed that the color change of the reflected light obtained before and after the bending of the circularly polarizing plate was changed with the a ^* coordinate axis and the b ^* coordinate axis in a ^* b ^* chromaticity coordinates interposed therebetween. In addition, it was possible to easily confirm the change in color.

[evaluation]

As is apparent from Table 1 and FIGS. 11 and 12, according to Examples 1 to 20 of the present invention, compared with Comparative Examples 1 to 3, the change in color (color) of the reflected light in the bent portion is inconspicuous. It is possible to do.

1A, 1B… Circular polarizer, 2… Polarizer, 3A… First retardation film (first retardation layer), 4A... 2nd retardation film (2nd retardation layer), 3B... λ/2 plate (1/2 wave plate), 4B… λ/4 plate (1/4 wave plate), 5, 6… Protective film (protective layer), 7… PSA layer (adhesive layer), 8... Adhesive layer or adhesive layer, 9... PSA layer (adhesive layer), 10… Display device, 20... Display panel, 30… Display device, 40… Touch sensor, 50… Window film, 200… Organic EL device, 210… Substrate, 220... First electrode, 230... Organic EL layer, 240... Second electrode, 250... Sealing layer.

Claims (10)

A circular polarizing plate used in a bendable display device,
A polarizer and at least one retardation layer disposed on one side of the polarizer,
A circular polarizing plate characterized in that the color of the reflected light obtained before and after the bending does not change with the a ^* coordinate axis and the b ^* coordinate axis in a ^* b ^* chromaticity coordinates. The circular polarizing plate of claim 1, wherein the retardation layer comprises a quarter wave plate. The circularly polarizing plate according to claim 2, wherein the retardation layer comprises a half wave plate. The circular polarizing plate according to claim 2 or 3, wherein the retardation layer comprises a positive C plate. The circular polarizing plate according to any one of claims 1 to 4, wherein the retardation layer comprises a layer in which a liquid crystal compound is cured. The circular polarizing plate according to any one of claims 1 to 5, wherein at least a part of the display device is bent to a radius of curvature of 8 mm or less. The circular polarizing plate according to any one of claims 1 to 6, wherein the display device is an organic electroluminescent display device. A bendable display device comprising the circularly polarizing plate according to any one of claims 1 to 7, and a bendable display panel. The touch sensor of claim 8, further comprising: a touch sensor disposed on a side of the circularly polarizing plate facing the display panel;
And a window film disposed on a side opposite to the side opposite to the display panel of the circularly polarizing plate. The bendable display device of claim 8, further comprising a touch sensor disposed on a side opposite to the side of the circularly polarizing plate facing the display panel.

Images