CN111316144B - Circular polarizing plate and display device - Google Patents

Abstract

The present invention relates to a circularly polarizing plate used in a bendable display device, which comprises a polarizer and at least 1 or more retardation layers disposed on one side of the polarizer, wherein the color tone of reflected light obtained before and after bending does not sandwich a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign.

Description

Circular polarizing plate and display device

Technical Field

The present invention relates to a circular polarizing plate. The present invention also relates to a bendable display device including the circularly polarizing plate.

The present application claims priority based on Japanese application No. 2017-217107 filed on Japanese application on 11/10/2017 and Japanese application No. 2018-201206 filed on Japanese application on 10/25/2018, and the contents thereof are incorporated herein by reference.

Background

In the past, circular polarizing plates have been used in order to suppress adverse effects caused by reflection of external light in display devices. On the other hand, in recent years, demands for bendable (flexible) display devices typified by organic Electroluminescence (EL) display devices have been increasing. In addition, not only simple flexibility of the display device but also flexibility at a very small radius of curvature is required.

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

In view of such a problem, patent document 1 listed below proposes a circularly polarizing plate including a retardation film exhibiting predetermined optical characteristics, in which the slow axis direction of the retardation film is adjusted to an angle of 20 to 70 degrees with respect to the bending direction of the display device. Patent document 1 discloses the use of a resin film such as PURE-ACE WR (polycarbonate resin film) as a retardation film exhibiting predetermined optical properties.

Patent document 2 proposes a circularly polarizing plate including a retardation film including a 1/2 wavelength (λ/2) plate and a 1/4 wavelength (λ/4) plate, the λ/2 plate and the λ/4 plate each including a liquid crystal compound, and the slow axis direction of the retardation film being adjusted to an angle of 75 to 105 degrees with respect to the bending direction of the display device.

Documents of the prior art

Patent literature

Patent document 1: japanese unexamined patent publication No. 2014-170221

Patent document 2: international publication No. 2016/158300

Disclosure of Invention

Problems to be solved by the invention

However, the above-described bendable display device is required to have further improved visibility. In addition, it is required to reduce a change in color tone (color and smell) of reflected light at a curved portion when the display device is curved.

To this end, the present invention makes clear: the visibility of the display device can be improved by utilizing the color design that not only reduces the change in color tone before and after bending but also makes the change in color tone inconspicuous before and after bending.

That is, an object of the present invention is to provide a circularly polarizing plate capable of making a change in color tone inconspicuous before and after bending, and a bendable display device including the circularly polarizing plate.

Means for solving the problems

As a means for solving the above problems, according to an aspect of the present invention, there is provided a circularly polarizing plate used for a bendable display device, the circularly polarizing plate including an polarizerA polarizer and at least 1 or more kinds of retardation layers disposed on one side of the polarizer, wherein the color tone of the reflected light obtained before and after bending is not sandwiched by a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign.

In the circularly polarizing plate, the retardation layer may be a structure including a 1/4 wavelength plate.

In the circularly polarizing plate, the retardation layer may be a structure including a 1/2 wavelength plate.

In the circularly polarizing plate, the retardation layer may have a structure including a positive C plate.

In the circularly polarizing plate, the retardation layer may be a layer containing a cured liquid crystal compound.

In the circularly polarizing plate, at least a part of the display device may be curved with a radius of curvature of 8mm or less.

In the circularly polarizing plate, the display device may be an organic electroluminescence display device.

Further, according to an aspect of the present invention, there is provided a bendable display device including the above-described arbitrary circular polarizing plate and a bendable display panel.

The display device may be configured to include a touch sensor disposed on a side of the circularly polarizing plate facing the display panel, and a window film disposed on a side of the circularly polarizing plate opposite to the side facing the display panel.

In the display device, the circular polarizing plate may be provided with a touch sensor disposed on a side opposite to a side thereof facing the display panel.

That is, the present invention has the following aspects.

[1]A circularly polarizing plate for use in a bendable display device, comprising a polarizer and a polarizer arranged on one side of the polarizerAt least 1 or more retardation layers, the color tone of the reflected light obtained before and after bending does not sandwich a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign.

[2] The circularly polarizing plate according to [1], wherein the retardation layer comprises a 1/4 wavelength plate.

[3] The circularly polarizing plate according to [2], wherein the retardation layer comprises a 1/2 wavelength plate.

[4] The circularly polarizing plate according to any one of [2] and [3], wherein the retardation layer comprises a positive C plate.

[5] The circularly polarizing plate according to any one of [1] to [4], wherein the retardation layer comprises a layer obtained by solidifying a liquid crystal compound.

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

[7] The circularly 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 circularly polarizing plate according to any one of [1] to [7] and a bendable display panel.

[9] The bendable display device according to [8], 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 of the circularly polarizing plate opposite to the side facing the display panel.

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

Effects of the invention

As described above, according to the aspect of the present invention, it is possible to provide a circularly polarizing plate capable of making a change in color tone inconspicuous before and after bending, and a bendable display device including the circularly polarizing plate.

Drawings

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

Fig. 2 is a cross-sectional view showing a configuration of a bendable display device including the circularly polarizing plate shown in fig. 1.

Fig. 3 is a cross-sectional view showing the structure of the circularly polarizing plate according to embodiment 2 of the present invention.

Fig. 4 is a cross-sectional view showing a configuration of a bendable display device including the circularly polarizing plate shown in fig. 3.

Fig. 5 is a cross-sectional view showing the structure of the organic EL element.

Fig. 6A is a schematic diagram for explaining a bent state of the display device.

Fig. 6B is a schematic diagram for explaining a bent state of the display device.

Fig. 6C is a schematic diagram for explaining a bent state of the display device.

Fig. 6D is a schematic diagram for explaining a bent state of the display device.

Fig. 7 is a schematic diagram for explaining the relationship between the bending direction of the display device shown in fig. 2, the absorption axis direction of the polarizing plate, and the slow axis direction of the 1 st retardation film.

Fig. 8 is a schematic diagram for explaining the relationship between the bending direction of the display device shown in fig. 4 and the absorption axis direction of the polarizing plate, and the relationship between the slow axis direction of the λ/2 plate and the slow axis direction of the λ/4 plate.

FIG. 9 is a diagram a for explaining a change in color tone of reflected light obtained before and after bending of a circular polarizing plate ^* b ^* And (5) a chromaticity coordinate graph.

Fig. 10 is a cross-sectional view showing another configuration example of a bendable display device including the circularly polarizing plate of the present invention.

FIG. 11 shows changes in color before and after bending a for examples 1 to 12 and comparative examples 1 to 3 ^* b ^* And (5) a chromaticity coordinate graph.

FIG. 12 shows the change in color tone before and after bending in examples 13 to 20 ^* b ^* And (5) a chromaticity coordinate graph.

Detailed Description

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

In the drawings used in the following description, the components may be schematically illustrated in order to facilitate the observation of the components, and the dimensions of the components may be differently illustrated depending on the components. The materials, numerical values, and the like exemplified in the following description are examples, and the present invention is not necessarily limited to these examples, and can be implemented by appropriately changing the materials, numerical values, and the like within a range not changing the gist thereof.

[ circularly polarizing plate ]

(embodiment 1)

As embodiment 1 of the present invention, for example, a circularly polarizing plate 1A shown in fig. 1 and a bendable display device 10A including the circularly polarizing plate 1A shown in fig. 2 will be described. Fig. 1 is a cross-sectional view showing the structure of the circularly polarizing plate 1A. Fig. 2 is a cross-sectional view showing the structure of a bendable display device 10A including a circularly polarizing plate 1A.

As shown in fig. 1, the circularly polarizing plate 1A of the present embodiment includes a polarizer 2, and a 1 st retardation film (1 st retardation layer) 3A and a 2 nd retardation film (2 nd retardation layer) 4A disposed on one surface side of the polarizer 2. Protective films (protective layers) 5 and 6 are disposed on both surfaces of the polarizing plate 2.

On one surface side of the polarizing plate 2, a 1 st retardation film 3A is laminated via a PSA layer (pressure-sensitive adhesive layer) 7. The 1 st retardation film 3A and the 2 nd retardation film 4A are bonded to each other via an adhesive layer or an adhesive layer 8. A PSA layer (pressure-sensitive adhesive layer) 9 for lamination to a display panel 20 described later is disposed on the surface of the circularly polarizing plate 1A facing the 2 nd retardation film 4A. A release film (not shown) is attached to the surface of the PSA layer 9 until it is used. The PSA layers 7 and 9 are formed of, for example, an acrylic adhesive.

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

As the polarizing plate 2, for example, a polarizing plate obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene/vinyl acetate copolymer partially saponified film to dyeing treatment with a dichroic substance such as iodine or a dichroic dye and stretching treatment, or a polyene-based alignment film such as a dehydrated product of polyvinyl alcohol or a desalted product of polyvinyl chloride, or the like can be used. Among them, as the polarizing plate excellent in optical characteristics, a polarizing plate obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching the film is preferably used.

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

The polyvinyl alcohol film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, and the like as necessary. For example, by immersing the polyvinyl alcohol film in water and washing it with water before dyeing, not only dirt and antiblocking agent on the surface of the polyvinyl alcohol film can be washed, but also the polyvinyl alcohol film can be swollen to prevent uneven dyeing and the like.

As the polarizing plate 2, for example, as described in japanese patent application laid-open No. 2016-170368, a polarizing plate in which a dichroic dye is aligned in a cured film obtained by polymerizing a liquid crystal compound can be used. As the dichroic dye, a dichroic dye having absorption in a wavelength range of 380 to 800nm can be used, and an organic dye is preferably used. Examples of the dichroic dye include azo compounds. The liquid crystal compound is a liquid crystal compound capable of being polymerized while maintaining the alignment, and may have a polymerizable group in the molecule.

The visibility correction polarization degree of the polarizing plate 2 is preferably 95% or more, and more preferably 97% or more. The content may be 99% or more, and may be 99.9% or more. The visibility correction polarization degree of the polarizing plate 2 may be 99.995% or less, or may be 99.99% or less. The degree of polarization for visibility correction can be determined by measuring the degree of polarization obtained using an absorption spectrophotometer with an integrating sphere ("V7100" by japan spectrophotometers) according to JIS Z8701: 1999 "2 degree field of view (C illuminant) was calculated with visibility correction.

By setting the visibility correction polarization degree of the polarizing plate 2 to 95 to 99.9%, the initial (before bending) color tone can be easily adjusted to a position deviated from neutral. Therefore, it is difficult to sandwich a between the colors of reflected light before and after bending described later ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. Further, the durability of the circularly polarizing plate 1 can be improved by setting the visibility correction polarization degree of the polarizing plate 2 to 99.9% or more. On the other hand, if the visibility correction polarization degree of the polarizing plate 2 is less than 95%, the polarizing plate may not function as an antireflection film. That is, if the visibility-corrected polarization degree of the polarizing plate 2 is 95% or more, the polarizing plate easily functions as an antireflection film.

The visibility-correcting monomer transmittance of the polarizing plate 2 is preferably 42% or more, more preferably 44% or more, preferably 60% or less, and more preferably 50% or less. The transmittance of the monomer for visibility correction was measured by measuring the obtained transmittance using an absorptiometer with an integrating sphere ("V7100" manufactured by japan spectrofluoric corporation) according to JIS Z8701: 1999 field of view 2 degrees (C illuminant) was calculated with visibility correction. The lower limit value and the upper limit value may be arbitrarily combined. Examples of the combination include 42% to 60%, 44% to 50%.

By setting the visibility correcting element transmittance to 42% or more, the cross color tone of the polarizing plate can be easily adjusted to a position away from the neutral side, and therefore, the color change before and after bending can be made inconspicuous. If the amount is more than 50%, the degree of polarization may be too low, and the antireflection function may not be achieved. That is, if the amount is 50% or less, the polarization degree is not too low, and the antireflection function is easily realized.

Since the cross-color tone of the polarizing plate 2 can be easily adjusted to a position deviated from the neutral side by setting the visibility correction simple substance transmittance of the polarizing plate 2 to 42% or more, the present invention is not limited to the above-described embodimentsThe color tone of the reflected light obtained before and after bending described later is easily prevented from being sandwiched by a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* Case where the coordinate axis changes sign. On the other hand, if the visibility correction simple substance transmittance of the polarizing plate 2 is more than 50%, the polarization degree is too low, and the antireflection function cannot be realized, which is not preferable.

The 1 st retardation film 3A may be a positive A plate that functions as a 1/4 wavelength (λ/4) plate. The positive A plate satisfies a relationship of Nx > Ny where Nx is a refractive index in a slow axis direction in a plane, ny is a refractive index in a fast axis direction in the plane, and Nz is a refractive index in a thickness direction. The λ/4 plate has a function of converting linearly polarized light of a certain specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light).

The 1 st retardation film 3A represents any appropriate refractive index ellipsoid as long as it satisfies Nx > Ny. The refractive index ellipsoid of the 1 st retardation film 3A preferably has a relationship of Nx > Ny ≧ Nz (Nz denotes the refractive index in the thickness direction). The Nz coefficient of the 1 st retardation film 3A is preferably 1 to 2, more preferably 1 to 1.5, and further preferably 1 to 1.3.

The 1 st retardation film 3A preferably exhibits reverse wavelength dispersion characteristics. Specifically, the in-plane phase difference value Re (lambda) at the wavelength lambda [ nm ] satisfies the relationship of Re (450) < Re (550) < Re (650), 100nm. Ltoreq. Re (550). Ltoreq.200 nm. By satisfying such a relationship, an excellent reflection color tone can be realized in the front direction of the display device 10A described later. Re (550) is preferably in the range of 120 nm. Ltoreq. Re (550). Ltoreq.170 nm.

The thickness of the 1 st retardation film 3A is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and still more preferably 0.5 to 3 μm, from the viewpoint of easily making the effect of preventing wrinkles at the time of bending remarkable. The thickness of the 1 st retardation film 3A is a value obtained by measuring the thickness of any 5 points in the plane and arithmetically averaging the measured values.

The 1 st retardation film 3A may include a film formed of a resin exemplified as a material of the protective films 5 and 6 described later, a layer obtained by curing a liquid crystal compound, and the like. When the 1 st retardation film 3A is formed of a resin, among them, a polycarbonate-based resin, a cycloolefin-based resin, a styrene-based resin, and a cellulose-based resin are preferable. In the present embodiment, the 1 st retardation film 3A preferably includes a layer obtained by curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, but the liquid crystal compound can be classified into a rod-like type (rod-like liquid crystal compound) and a discotic type (discotic liquid crystal compound ) depending on the shape. Further, there are low molecular type and high molecular type, respectively. Polymers generally mean those having a polymerization degree of 100 or more (physical translation of polymers 1248012452124901251124631246312473 (physical translation kinetics of polymers), native well, page 2, shibo Shu, 1992).

In this embodiment, any liquid crystal compound can be used. In addition, 2 or more kinds of rod-like liquid crystal compounds, 2 or more kinds of discotic liquid crystal compounds, or a mixture of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.

The rod-like liquid crystal compound may be suitably used, for example, as the compound described in claim 1 of Japanese patent application laid-open No. 11-513019 or paragraphs [0026] to [0098] of Japanese patent application laid-open No. 2005-289980. As the discotic liquid crystal compound, for example, compounds described in paragraphs [0020] to [0067] of jp 2007-108732 a, or paragraphs [0013] to [0108] of jp 2010-244038 a can be suitably used.

The 1 st retardation film 3A is more preferably formed using a liquid crystal compound having a polymerizable group (rod-like liquid crystal compound or discotic liquid crystal compound). Thus, the temperature-dependent change and the humidity-dependent change in the optical characteristics can be reduced.

The liquid crystal compound may be a mixture of 2 or more. In this case, at least 1 species preferably has 2 or more polymerizable groups. That is, the 1 st retardation film 3A is preferably a layer in which a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group is fixed by polymerization, and such a layer is included in a layer obtained by curing the liquid crystal compound. In this case, it is not necessary to exhibit liquid crystallinity even after the layer is formed.

The type of the polymerizable group contained in the rod-like liquid crystal compound or the discotic liquid crystal compound is not particularly limited, and for example, a functional group capable of undergoing an addition polymerization reaction, such as a polymerizable ethylenically unsaturated group or a cyclopolymerizable group, is preferable. More specifically, examples thereof include a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, (meth) acryloyl groups are preferable. The term "(meth) acryloyl" refers to a concept including both methacryloyl and acryloyl groups.

The method for forming the 1 st retardation film 3A is not particularly limited, and known methods can be exemplified. For example, the 1 st retardation film 3A can be produced by applying a composition for forming an optically anisotropic layer (hereinafter, simply referred to as "composition") containing a liquid crystal compound having a polymerizable group to a predetermined substrate (including a temporary substrate) to form a coating film, and subjecting the obtained coating film to a curing treatment (irradiation of ultraviolet rays (light irradiation treatment) or heating treatment).

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

The composition may contain components other than the above-mentioned liquid crystal compound. For example, in the composition, a polymerization initiator may be contained. The polymerization initiator used may be selected from, for example, thermal polymerization initiators and photopolymerization initiators depending on the form of the polymerization reaction. Examples of the photopolymerization initiator include α -carbonyl compounds, acyloin ethers, α -hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the composition.

The composition may contain a polymerizable monomer in view of uniformity of the coating film and strength of the film. Examples of the polymerizable monomer include a radically polymerizable or cationically polymerizable compound. Among them, polyfunctional radical polymerizable monomers are preferable.

The polymerizable monomer is preferably a monomer copolymerizable with the polymerizable group-containing liquid crystal compound. Specific examples of the polymerizable monomer include polymerizable monomers described in paragraphs [0018] to [0020] in Japanese patent application laid-open No. 2002-296423. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, based on the total mass of the liquid crystal compound.

The composition may contain a surfactant in view of uniformity of the coating film and strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine compounds are particularly preferable. Specific examples of the surfactant include compounds described in paragraphs [0028] to [0056] of Japanese patent application laid-open No. 2001-330725 and compounds described in paragraphs [0069] to [0126] of Japanese patent application laid-open No. 2003-295212.

In addition, a solvent may be contained in the composition, and an organic solvent is preferably used. Examples of the organic solvent include amides (e.g., N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1, 2-dimethoxyethane). Among them, alkyl halides and ketones are preferable. In addition, 2 or more organic solvents may be used in combination.

The composition may contain various alignment agents such as a vertical alignment promoter such as a polarizing plate interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment promoter such as a polarizing plate interface side horizontal alignment agent and an air interface side horizontal alignment agent. The composition may further contain an adhesion improving agent, a plasticizer, a polymer, and the like in addition to the above components.

The 1 st retardation film 3A may include an alignment film having a function of defining an alignment direction of the liquid crystal compound. The alignment film generally contains a polymer as a main component. Many documents describe polymer materials for alignment films, and many commercially available products are available. Among them, polyvinyl alcohol, polyimide, or a derivative thereof is preferably used as the polymer material, and particularly preferably, modified or unmodified polyvinyl alcohol is used as the polymer material.

The alignment film that can be used in this embodiment can be a modified polyvinyl alcohol described in International publication No. 2001/88574 at pages 43, 24 to 49, 8 and paragraphs [0071] to [0095] of Japanese patent No. 3907735.

The alignment film is usually subjected to a known alignment treatment. For example, rubbing treatment, photo-alignment treatment by irradiation with polarized light, and the like can be mentioned, but photo-alignment treatment is preferable from the viewpoint of surface roughness of the alignment film.

The thickness of the orientation film is not particularly limited, but is usually 20 μm or less, and among them, it is preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, and still more preferably 0.01 to 1 μm.

The 2 nd retardation film 4A can function as a positive C plate. The positive C plate satisfies the relationship that Nz is more than Nx is more than or equal to Ny. By including the positive C plate, it is possible to reduce a change in color tone (color and smell) of reflected light at a curved portion when the display device 10A described later is curved. The difference between the value of Nx and the value of Ny is preferably within 0.5%, more preferably within 0.3% of the value of Ny. When the ratio is within 0.5%, nx = Ny can be regarded as essential.

The retardation film 4A of the 2 nd retardation film 4A preferably satisfies a relation of-300 nm. Ltoreq. Rth (550). Ltoreq. -20nm in a retardation value Rth (λ) in a thickness direction at a wavelength λ [ nm ], more preferably-150 nm. Ltoreq. Rth (550). Ltoreq.20 nm.

The thickness of the 2 nd retardation film 4A is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and further preferably 0.5 to 3 μm, from the viewpoint of preventing wrinkles caused by the difference in dimensional change between the front and back surfaces of the film at the time of bending. The thickness of the 2 nd retardation film 4A is a value obtained by measuring the thickness of an arbitrary 5 points in the plane and arithmetically averaging the measured values.

The 2 nd retardation film 4A preferably includes a layer obtained by curing a liquid crystal compound. The kind of the liquid crystal compound is not particularly limited, and the same materials as those listed as the materials of the 1 st retardation film 3A can be used. Among them, a layer in which a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group is fixed by polymerization is preferable. In this case, it is not necessary to exhibit liquid crystallinity even after the layer is formed.

Among the layers included in the circularly polarizing plate 1A, the layer obtained by curing the liquid crystal compound is preferably 1 layer or 2 layers other than the polarizer 2. If the retardation film is a layer obtained by curing a liquid crystal compound, the thickness can be reduced, and therefore, the dimensional change of the retardation layer when the retardation film is bent with the same diameter can be reduced as compared with the case of using a thick film type, and as a result, the change in retardation can be suppressed, which is preferable.

The 1 st retardation film 3A and the 2 nd retardation film 4A are not necessarily limited to the above-described structure of the layer containing the cured liquid crystal compound, and for example, the 1 st retardation film 3A and the 2 nd retardation film 4A to which the above-described retardation value is applied by stretching (uniaxial stretching, biaxial stretching, or the like) a film containing a thermoplastic resin can be used.

The protective films 5 and 6 function as protective layers for protecting the polarizing plate 2, and the protective film 5 is disposed at least on the outer surface of the polarizing plate 2 (the surface opposite to the side facing the 1 st retardation film 3A). Further, a protective film 6 may be disposed on the inner surface of the polarizing plate 2 (the surface facing the 1 st retardation film 3A).

Examples of the material of the protective films 5 and 6 include light-transmitting (preferably optically transparent) thermoplastic resins, such as chain polyolefin resins (polypropylene resins, etc.), polyolefin resins such as cyclic polyolefin resins (norbornene resins, etc.), cellulose ester resins such as cellulose triacetate, and cellulose diacetate, polyester resins, polycarbonate resins, (meth) acrylic resins, polystyrene resins, and mixtures and copolymers thereof. That is, the 1 st retardation film 3A may also function as the protective films 5 and 6.

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

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resins and polypropylene resins, and copolymers containing 2 or more kinds of chain olefins.

The cyclic polyolefin resin is a general term for resins obtained by polymerizing cyclic olefins as polymerization units. Specific examples of the cyclic polyolefin-based resin include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with linear olefins such as ethylene and propylene (typically random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products of these. Among these, as the cyclic olefin, for example, a norbornene-based resin using a norbornene-based monomer such as norbornene and polycyclic norbornene-based monomers can be suitably used.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, copolymers thereof and resins in which a part of the hydroxyl groups is modified with other substituents may be used. Among them, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferable.

The polyester resin is a resin other than the cellulose ester resin having an ester bond, and is usually a resin containing a polycondensate of a polybasic acid or a derivative thereof and a polyhydric alcohol. As the polybasic acid or the derivative thereof, a dibasic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl naphthalenedicarboxylate, and the like. Examples of the polyhydric alcohol include diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polypropylene terephthalate, polypropylene naphthalate, polycyclohexanedicarboxylate, and polycyclohexanedicarboxylate.

The polycarbonate-series resin contains a polymer in which monomer units are bonded via a carbonate group. The polycarbonate-based resin may be a resin called modified polycarbonate obtained by modifying a polymer skeleton, copolymerized polycarbonate, or the like.

The (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer. Specific examples of the (meth) acrylic resin include poly (meth) acrylates such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylate copolymers, methyl methacrylate-acrylate- (meth) acrylic acid copolymers, methyl (meth) acrylate-styrene copolymers (such as MS resins), and copolymers of methyl methacrylate and a compound having an alicyclic hydrocarbon group (such as methyl methacrylate-cyclohexyl methacrylate copolymers and methyl methacrylate-norbornyl (meth) acrylate copolymers). Preference is given to using poly (meth) acrylic acid C such as polymethyl (meth) acrylate _1－6 A polymer containing an alkyl ester (having 1 to 6 carbon atoms) as a main component. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

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

The outer protective film 5 may be subjected to surface treatment such as hard coat treatment, antireflection treatment, adhesion prevention treatment, and antiglare treatment on the surface opposite to the side thereof opposite to the polarizing plate 2, as necessary. In this case, the thickness of the protective film 5 is 5mm or less, preferably 1mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm.

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

As the adhesive layer 8, for example, an active energy ray-curable adhesive (preferably, an ultraviolet-curable adhesive) containing a curable compound that is cured by irradiation with an active energy ray such as ultraviolet ray, visible light, electron beam, or X-ray, or an aqueous adhesive obtained by dissolving or dispersing an adhesive component such as a polyvinyl alcohol resin in water can be used as the adhesive. In the circularly polarizing plate 1A, the 1 st retardation film 3A and the 2 nd retardation film 4A are laminated via the adhesive layer 8, whereby wrinkles can be prevented from occurring at the time of bending. In addition, in the circularly polarizing plate 1B described later, the occurrence of wrinkles during bending can be prevented, as in the case where the λ/2 plate 3B and the λ/4 plate 4B are laminated via the adhesive layer 8.

Since the active energy ray-curable adhesive exhibits good adhesion, 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 contain a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound.

Examples of the cationically polymerizable curable compound include an epoxy compound (a compound having 1 or 2 or more epoxy groups in a molecule), an oxetane compound (a compound having 1 or 2 or more oxetane rings in a molecule), and a combination thereof. Examples of the radically polymerizable curable compound include a (meth) acrylic compound (a compound having 1 or 2 or more (meth) acryloyloxy groups in the molecule), another vinyl compound having a radically polymerizable double bond, and a combination thereof. The cationically polymerizable curable compound may be used in combination with the radically polymerizable curable compound.

The active energy ray-curable adhesive may contain additives such as a cationic polymerization accelerator, an ion scavenger, an antioxidant, a chain transfer agent, a thickener, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent, and a solvent, as required.

When the retardation films 3A and 4A are bonded to each other using an active energy ray-curable adhesive, the adhesive layer 8 is formed by laminating the retardation film 3A and the retardation film 4A via the active energy ray-curable adhesive, and then irradiating the adhesive with an active energy ray such as ultraviolet ray, visible light, electron beam, or X-ray to cure the adhesive. Among them, ultraviolet rays are suitable, and a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-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 as the light source in this case. In the case of using an aqueous adhesive, the retardation film 3A and the retardation film 4A may be laminated via an aqueous adhesive and then heated and dried.

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

The storage modulus of the adhesive layer 8 at 30 ℃ is preferably 600 to 4000MPa, more preferably 700 to 3500MPa, still more preferably 1000 to 3000MPa, and most preferably 1500 to 3000MPa. By bonding the retardation films 3A and 4A to each other with the hard adhesive layer 8 exhibiting such a storage modulus, the occurrence of wrinkles in the retardation layer can be further easily prevented during bending.

The storage modulus of the adhesive layer 8 at 30 ℃ is used when the storage modulus of the adhesive layer 8 of the circularly polarizing plate 1A at 30 ℃ can be directly measured by the following method. On the other hand, when the measurement cannot be directly performed, a test piece of an adhesive layer was formed on a release paper under the same conditions as those for forming the adhesive layer 8 (type of adhesive, curing conditions), and the material obtained by peeling the test piece of the adhesive layer from the release paper was measured by the following method, and it was considered that the value was the same as the obtained storage modulus.

The storage modulus of the adhesive layer 8 or the adhesive layer test piece can be measured by a commercially available dynamic visco-elastic device, for example, by a product name DVA-220 manufactured by IT measurement and control co.

The pressure-sensitive adhesive layer 8 may be any pressure-sensitive adhesive as long as it is a pressure-sensitive adhesive that is appropriately selected from conventionally known pressure-sensitive adhesives and has such adhesiveness that peeling or the like does not occur in a high-temperature environment, a moist-heat environment, or an environment where high and low temperatures are repeated to which the polarizing plate is exposed. Specifically, an acrylic adhesive, a silicone adhesive, a rubber adhesive, and the like are mentioned, and an acrylic adhesive is particularly preferable in view of transparency, weather resistance, heat resistance, and processability.

If necessary, various additives such as a tackifier, a plasticizer, glass fibers, glass beads, metal powder, a filler containing other inorganic powder, a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber, an antistatic agent, and a silane coupling agent may be appropriately blended in the adhesive.

The adhesive layer 8 is generally formed by applying a solution of an adhesive to a release sheet and drying the adhesive. The coating on the release sheet may be performed by, for example, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a spray coating method, a dip coating method, or a spray method. The release sheet provided with the adhesive layer can be used by a method of transferring the release sheet, or the like.

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

(embodiment 2)

As embodiment 2 of the present invention, for example, a circularly polarizing plate 1B shown in fig. 3 and a bendable display device 10B provided with the circularly polarizing plate 1B shown in fig. 4 will be described. Fig. 3 is a cross-sectional view showing the structure of the circularly polarizing plate 1B. Fig. 4 is a cross-sectional view showing the structure of a bendable display device 10B including a circularly polarizing plate 1B. In the following description, the same portions as those of the circularly polarizing plate 1A are not described, and the same reference numerals are used in the drawings.

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

On one surface side of the polarizing plate 2, a λ/2 plate 3B is laminated via a PSA layer (adhesive layer) 7. The λ/2 plate 3B and the λ/4 plate 4B are laminated via an adhesive layer or an adhesive layer 8. A PSA layer (pressure-sensitive adhesive layer) 9 for lamination to a display panel 20 described later is disposed on the surface of the circularly polarizing plate 1 facing the λ/4 plate 4B. A release film (not shown) is bonded to the surface of the PSA layer 9 until the time of use. The PSA layers 7 and 9 are formed of, for example, an acrylic adhesive.

The λ/2 plate 3B has a function of changing the direction (polarization direction) of linearly polarized light by giving a phase difference of pi (= λ/2) in the electric field vibration direction (polarization plane) of incident light. When circularly polarized light is incident, the rotation direction of the circularly polarized light can be reversed.

Re (λ), which is an in-plane retardation value at a specific wavelength λ nm of the λ/2 plate 3B, satisfies Re (λ) = λ/2. This formula may be achieved at any wavelength in the visible light region (for example, 550 nm). Among them, re (550), which is an in-plane retardation value at a wavelength of 550nm, preferably satisfies 210 nm. Ltoreq. Re (550). Ltoreq.300 nm. Further, it is more preferable that 220 nm. Ltoreq. Re (550). Ltoreq.290 nm be satisfied.

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

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 still more preferably 0.5 to 3 μm, from the viewpoint of easily making the wrinkle-preventing effect remarkable. The thickness of the λ/2 plate 3B is a value obtained by measuring the thickness of an arbitrary 5 points in the plane and arithmetically averaging the measured values. In the case of a resin film used in the past, wrinkles are not likely to occur in the past.

The λ/2 plate 3B preferably comprises a layer obtained by curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, but the liquid crystal compound can be classified into a rod-like type (rod-like liquid crystal compound) and a discotic type (discotic liquid crystal compound ) depending on the shape. Further, there are low molecular type and high molecular type, respectively. The term "polymer" generally means a substance having a polymerization degree of 100 or more (physical pellet of polymer 12480124521249012511246312473 (physical polymer phase transfer kinetics), native well male book, page 2, rock book store, 1992.

In this embodiment, any liquid crystal compound can be used. In addition, 2 or more kinds of rod-like liquid crystal compounds, 2 or more kinds of discotic liquid crystal compounds, or a mixture of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.

The rod-like liquid crystal compound may be suitably used, for example, as the compound described in claim 1 of Japanese patent application laid-open No. 11-513019 or paragraphs [0026] to [0098] of Japanese patent application laid-open No. 2005-289980. As the disk-shaped liquid crystal compound, for example, compounds described in paragraphs [0020] to [0067] of Japanese patent application laid-open No. 2007-108732 or paragraphs [0013] to [0108] of Japanese patent application laid-open No. 2010-244038 can be suitably used.

The λ/2 plate 3B is more preferably formed using a liquid crystal compound having a polymerizable group (rod-like liquid crystal compound or discotic liquid crystal compound). Thus, the temperature-dependent change and the humidity-dependent change in the optical characteristics can be reduced.

The liquid crystal compound may be a mixture of 2 or more. In this case, at least 1 species preferably has 2 or more polymerizable groups. That is, the λ/2 plate 3B is preferably a layer in which a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group is fixed by polymerization. In this case, it is not necessary to exhibit liquid crystallinity even after the layer is formed.

The type of the polymerizable group contained in the rod-like liquid crystal compound or the discotic liquid crystal compound is not particularly limited, and for example, a functional group capable of addition polymerization such as a polymerizable ethylenically unsaturated group or a cyclopolymerizable group is preferable. More specifically, examples thereof include a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, (meth) acryloyl groups are preferable.

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

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

The composition may contain components other than the above-mentioned liquid crystal compound. For example, in the composition, a polymerization initiator may be contained. The polymerization initiator used may be selected from, for example, thermal polymerization initiators and photopolymerization initiators depending on the form of the polymerization reaction. Examples of the photopolymerization initiator include α -carbonyl compounds, acyloin ethers, α -hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the composition.

The composition may contain a polymerizable monomer in view of uniformity of the coating film and strength of the film. Examples of the polymerizable monomer include a radically polymerizable or cationically polymerizable compound. Among them, polyfunctional radical polymerizable monomers are preferable.

The polymerizable monomer is preferably a monomer copolymerizable with the polymerizable group-containing liquid crystal compound. Specific examples of the polymerizable monomer include polymerizable monomers described in paragraphs [0018] to [0020] in Japanese patent laid-open No. 2002-296423. The amount of the polymerizable monomer used 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.

The composition may contain a surfactant in view of uniformity of the coating film and strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine compounds are particularly preferable. Specific examples of the surfactant include compounds described in paragraphs [0028] to [0056] of Japanese patent application laid-open No. 2001-330725 and compounds described in paragraphs [0069] to [0126] of Japanese patent application laid-open No. 2003-295212.

In addition, a solvent may be contained in the composition, and an organic solvent is preferably used. Examples of the organic solvent include amides (e.g., N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1, 2-dimethoxyethane). Among them, alkyl halides and ketones are preferable. In addition, 2 or more organic solvents may be used in combination.

The composition may contain various alignment agents such as a vertical alignment promoter such as a polarizing plate interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment promoter such as a polarizing plate interface side horizontal alignment agent and an air interface side horizontal alignment agent. The composition may further contain an adhesion improving agent, a plasticizer, a polymer, and the like in addition to the above components.

The λ/2 plate 3B may include an alignment film having a function of defining an alignment direction of the liquid crystal compound. The alignment film generally contains a polymer as a main component. Many documents describe polymer materials for alignment films, and many commercially available products are available. Among them, polyvinyl alcohol, polyimide, or a derivative thereof is preferably used as the polymer material, and particularly preferably, modified or unmodified polyvinyl alcohol is used as the polymer material.

The alignment film that can be used in this embodiment can be referred to as modified polyvinyl alcohol described in International publication No. 2001/88574, page 43, line 24 to page 49, line 8, and Japanese patent application laid-open Nos. 3907735, paragraphs [0071] to [0095 ].

The alignment film is usually subjected to a known alignment treatment. For example, rubbing treatment, photo-alignment treatment by irradiation with polarized light, and the like can be mentioned, but photo-alignment treatment is preferable from the viewpoint of surface roughness of the alignment film.

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

The λ/4 plate 4B has a function of converting a linearly polarized light having a specific wavelength into a circularly polarized light (or converting a circularly polarized light into a linearly polarized light) by giving a phase difference of π/2 (= λ/4) in the electric field vibration direction (polarization plane) of the incident light.

An in-plane retardation value at a specific wavelength λ nm of the λ/4 plate 4B, i.e., re (λ), satisfies Re (λ) = λ/4. This formula may be achieved at any wavelength in the visible light region (for example, 550 nm). Among them, re (550), which is an in-plane retardation at a wavelength of 550nm, preferably satisfies 100nm. Ltoreq. Re (550). Ltoreq.160 nm. Further, it is more preferable that 110 nm. Ltoreq. Re (550). Ltoreq.150 nm be satisfied.

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

The thickness of the λ/4 plate 4B is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and even more preferably 0.5 to 3 μm, in terms of preventing wrinkles caused by the difference in dimensional change between the front and back sides of the film during bending. The thickness of the λ/4 plate 4B is a value obtained by measuring the thickness of an arbitrary 5 points in the plane and arithmetically averaging the measured values.

The λ/4 plate 4B preferably includes a layer obtained by curing a liquid crystal compound. The kind of the liquid crystal compound is not particularly limited, and the same materials as those listed as the material of the λ/2 plate 3B can be used. Among them, a layer in which a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group is fixed by polymerization is preferable. In this case, it is not necessary to exhibit liquid crystallinity even after the layer is formed.

Among the layers included in the circularly polarizing plate 1B, the layer obtained by curing the liquid crystal compound is preferably 1 layer or 2 layers other than the polarizer 2. When 3 or more layers obtained by curing a liquid crystal compound are included in addition to the polarizing plate 2, since the number of layers that may cause wrinkles increases, it is considered that wrinkles are likely to occur during bending.

The λ/2 plate 3B and the λ/4 plate 4B are not necessarily limited to the above-described structure of the layer containing the cured liquid crystal compound, and for example, a 1 st retardation film 3A and a 2 nd retardation film 4A to which the above-described retardation value is applied by stretching (uniaxial stretching, biaxial stretching, or the like) a film containing a thermoplastic resin can be used.

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

[ display device ]

The circularly polarizing plates 1A and 1B of the present embodiment are used in bendable display devices 10A and 10B as shown in fig. 2 and 4. Specific examples of the bendable display devices 10A and 10B include an organic EL display device, a liquid crystal display device using circularly polarized light (typically, a VA (Vertical Alignment) mode liquid crystal display device), a MEMS (Micro Electro Mechanical Systems) display device, and the like. Among them, the circularly polarizing plates 1A and 1B of the present embodiment can be suitably used particularly for a bendable organic EL display device.

Specifically, as shown in fig. 2 and 4, the display devices 10A and 10B according to the present embodiment include a bendable display panel 20 and the circularly polarizing plates 1A and 1B disposed on the visible side of the display panel 20. In the display device 10A shown in fig. 2, the circularly polarizing plate 1A is attached to the visible side of the display panel 20 through the PSA layer 9 so that the polarizer 2 is on the visible side and the 2 nd retardation film 4A is on the display panel 20 side. On the other hand, in the display device 10B shown in fig. 4, the circularly polarizing plate 1B is attached to the surface of the display panel 20 on the viewing side via the PSA layer 9 so that the polarizer 2 is on the viewing side and the retardation layer RF is on the display panel 20 side.

In the display device 10A according to embodiment 1, light passing through the polarizing plate 2 is linearly polarized by external light entering from the viewing side of the display panel 20. The linearly polarized light passes through the 1 st retardation film 3A and the 2 nd retardation film 4A which become λ/4 plates to become circularly polarized light. The circularly polarized light is reflected by the display panel 20, and thereby becomes circularly polarized light which is inverted with respect to the incident light. When the circularly polarized light reflected by the display panel 20 passes through the 1 st retardation film 3A and the 2 nd retardation film 4A serving as λ/4 plates again, the circularly polarized light becomes linearly polarized light orthogonal to the incident light. Thus, the linearly polarized light is blocked by the polarizing plate 2. As a result, the influence of reflection of the external light can be suppressed.

On the other hand, in the display device 10B according to embodiment 2, external light enters from the visible side of the display panel 20, and light passing through the polarizing plate 2 is linearly polarized. The linearly polarized light passes through the λ/2 plate 3B to be converted into circularly polarized light, and then passes through the λ/4 plate 4B. The circularly polarized light is reflected by the display panel 20, and thereby becomes circularly polarized light which is inverted with respect to the incident light. When the circularly polarized light reflected by the display panel 20 passes through the λ/4 plate 4B and the λ/2 plate 3B again, the circularly polarized light becomes linearly polarized light orthogonal to the incident light. Thus, the linearly polarized light is blocked by the polarizing plate 2. As a result, the influence of reflection of the external light can be suppressed.

[ organic EL element ]

An example of the display panel 20 includes an organic EL element 200 as shown in fig. 5. Fig. 5 is a cross-sectional view showing the structure of the organic EL element 200.

Specifically, the organic EL element 200 includes a substrate 210, a 1 st electrode 220, an organic EL layer 230, a 2 nd electrode 240, and a sealing layer 250 covering them. In the organic EL element 200, a planarization layer (not shown) may be provided on the substrate 210, or an insulating layer (not shown) for preventing short-circuiting may be provided between the 1 st electrode 220 and the 2 nd electrode 240, for example, as needed.

The substrate 210 is made of a material having flexibility. By using the substrate 210 having flexibility, the display devices 10A and 10B can be curved with the radius of curvature described above. In addition, since the organic EL element 200 can be manufactured by a so-called roll-to-roll process, low-cost and mass production can be realized. The substrate 210 is preferably made of a material having shielding properties. Such a substrate 210 can protect the organic EL layer 230 from oxygen and moisture.

Specific materials of the substrate 210 having shielding properties and flexibility include thin glass having flexibility, thermoplastic resin or thermosetting resin film having shielding properties, alloys, metals, and the like.

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

The thickness of the substrate 210 is preferably 5 μm to 500. Mu.m, more preferably 5 μm to 300. Mu.m, and still more preferably 10 μm to 200. Mu.m. With such a thickness, the display devices 10A and 10B can be bent with the above-described radius of curvature. In addition, the organic EL element 200 can be suitably used in a roll-to-roll process.

The 1 st electrode 220 can function as an anode. In this case, a material having a large work function is preferable as a material constituting the 1 st electrode in terms of easy realization of hole injection property. Specific examples of such a material include Indium Tin Oxide (ITO), indium Zinc Oxide (IZO), indium tin oxide to which silicon oxide is added (ITSO), indium oxide containing tungsten oxide (IWO), indium zinc oxide containing tungsten oxide (IWZO), indium oxide containing titanium oxide (ITiO), transparent conductive materials such as indium tin oxide containing titanium oxide (ITTiO), indium tin oxide containing molybdenum (ITMO), and metals such as gold, silver, and platinum, and alloys thereof.

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

In addition, any appropriate combination that can generate light emission by recombination of electrons and holes in the light-emitting layer 230c can be used for the organic EL layer 230. In order to transmit emitted light as much as possible, the thickness of the organic EL layer 230 is preferably as thin as possible, specifically, 5nm to 200nm, and more preferably about 10nm.

The 2 nd electrode 240 can function as a cathode. In this case, a material having a small work function is preferable as a material constituting the 2 nd electrode 240 in order to facilitate electron injection and improve light emission efficiency. Specific examples of such materials include aluminum, magnesium, and alloys thereof.

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 epoxy resin and polyurea. The sealing layer 250 may be formed by applying an epoxy resin (epoxy resin adhesive) and attaching a shielding sheet thereto.

The organic EL element 200 can be continuously manufactured by a roll-to-roll process. The organic EL device 200 can be manufactured in the order of steps described in japanese patent laid-open No. 2012-16992, for example. The description of said publication is incorporated herein by reference. Further, the organic EL element 200 is continuously laminated with the long circularly polarizing plates 1A and 1B by a roll-to-roll process, and an organic EL display device can be continuously manufactured.

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.

The display panel 20 is exemplified by the embodiment using the organic EL element 200, but the embodiment is not necessarily limited thereto, and the display devices 10A and 10B to which the present invention is applied may be, for example, an embodiment including the display panel 20 including a liquid crystal display element and the circularly polarizing plates 1A and 1B disposed on the visible side of the display panel 20.

[ bending direction of display device ]

The display devices 10A and 10B according to the present embodiment also include a state in which they are bent (a state in which the bending is fixed) as shown in fig. 6A to 6D. Fig. 6A to 6D are schematic diagrams for explaining the bent state of the display devices 10A and 10B.

Specifically, the display devices 10A and 10B may be bent at the center portion like a folding type as shown in fig. 6A and 6B, for example. In addition, from the viewpoint of ensuring the design and the display screen to the maximum, the end portions may be bent as shown in fig. 6C and 6D.

The display devices 10A and 10B may be curved in the longitudinal direction or in the width direction as shown in fig. 6A to 6D. That is, the display devices 10A and 10B may be formed by bending a specific portion (for example, a part or all of four corners are inclined) according to the use thereof.

At least a part of the display devices 10A and 10B is preferably curved with a radius of curvature (bending radius) of 10mm or less, more preferably 8mm or less, and still more preferably 4mm or less. The display devices 10A and 10B according to the present embodiment reduce the change in color tone (color and taste) of reflected light in the state of being bent with such a very small radius of curvature, and are less likely to cause wrinkles in the circularly polarizing plates 1A and 1B. The lower limit of the bending radius is not particularly limited, and may be 0mm or more than 0mm.

Referring to fig. 7 (a) and (b), the relationship between the bending direction of the display device 10A (the direction orthogonal to the bending start line L), the absorption axis direction of the polarizing plate 2, and the slow axis direction of the 1 st retardation film 3A will be described. Fig. 7 (a) and (b) are schematic diagrams for explaining the relationship between the bending direction of the display device 10A, the absorption axis direction of the polarizing plate 2, and the slow axis direction of the 1 st retardation film 3A. In fig. 7 (a) and (b), the absorption axis direction of the polarizing plate 2 is indicated by a "solid line", and the slow axis direction of the 1 st retardation film 3A is indicated by a "broken line".

As shown in fig. 7 (a) and (b), the display device 10A includes at least a flat portion 10A and a curved portion 10b curved from a straight curve start line L (a two-dot chain line shown in fig. 7 (a) and (b)) located at an end of the flat portion 10A in a direction (a curved direction) orthogonal to the curve start line L. In this case, when the display device 10A is viewed from the normal direction of the flat portion 10A (Z-axis direction in fig. 7 (a) and (b)), the bending direction of the display device 10A corresponds to the direction (Y-axis direction in fig. 7 (a) and (b)) orthogonal to the linear bending start line L.

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

In the display device 10A of the present embodiment, the slow axis direction of the 1 st retardation film 3A is set to be positive with respect to the absorption axis direction (0 °) of the polarizing plate 2 with counterclockwise rotation in the range of 40 ° to 50 °, or-50 ° to-40 °, and more preferably set to 45 ° or-45 ° (see fig. 7 (a) and (b)).

As shown in fig. 6A to 6D, the absorption axis direction of the polarizing plate 2 is set to form an angle α with respect to the bending direction of the display device 10A. That is, the circularly polarizing plate 1A is disposed on the surface of the display panel 20 so that the absorption axis direction of the polarizer 2 is at an angle α with respect to the bending direction of the display device 10A.

Specifically, the angle α is set to a range of-5 ° to 5 ° or 85 ° to 95 ° and more preferably set to 0 ° or 90 ° by rotating counterclockwise from the absorption axis direction (0 °) of the polarizing plate 2. By adjusting the absorption axis direction (angle α) of the polarizing plate 2 so as to fall within such a range, color change due to bending can be suppressed.

With reference to fig. 8 (a) and (B), a relationship between the bending direction of the display device 10B (direction orthogonal to the bending start line L) and the absorption axis direction of the polarizing plate 2, and a relationship between the slow axis direction of the λ/2 plate 3B and the slow axis direction of the λ/4 plate 4B will be described. Fig. 8 (a) and (B) are schematic diagrams for explaining the relationship between the bending direction of the display device 10B and the absorption axis direction of the polarizing plate 2, and the relationship between the slow axis direction of the λ/2 plate 3B and the slow axis direction of the λ/4 plate 4B. In fig. 8 (a) and (B), the absorption axis direction of the polarizing plate 2 is indicated by a "broken line", the slow axis direction of the λ/2 plate 3B is indicated by a "one-dot chain line", and the slow axis direction of the λ/4 plate 4B is indicated by a "solid line".

As shown in fig. 8 (a) and (B), the display device 10B includes at least a flat portion 10a and a curved portion 10B curved from a straight curve start line L (a two-dot chain line shown in fig. 8 (a) and (B)) located at an end of the flat portion 10a in a direction (a curved direction) orthogonal to the curve start line L. In this case, the display device 10B is viewed from the normal direction of the flat portion 10a (the Z-axis direction in fig. 8 (a) and (B)), and the bending direction of the display device 10B corresponds to the direction (the Y-axis direction in fig. 8 (a) and (B)) orthogonal to the linear bending start line L.

In the display device 10B of the present embodiment, the bending direction of the display device 10B is set to a range of-10 ° to 10 ° (0 ° in fig. 8 (a)) or 80 ° to 100 ° (90 ° in fig. 8 (B)), preferably to a range of-5 ° to 5 ° or 85 ° to 95 °, and more preferably to 0 ° or 90 °, with counterclockwise rotation being positive with respect to the slow axis direction (0 °) of the λ/4 plate 4B.

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 polarizing plate 2. That is, the circularly polarizing plate 1B is disposed on the surface of the display panel 20 so that the slow axis direction of the λ/2 plate 3B is at an angle α with respect to the absorption axis direction of the polarizer 2.

Further, 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 polarizing plate 2. That is, the circularly polarizing plate 1B is disposed on the surface of the display panel 20 so that the slow axis direction of the λ/4 plate 4B is at an angle β with respect to the absorption axis direction of the polarizer 2. The angle α and the angle β are both angles that are positive when the polarizer 2 is rotated counterclockwise with respect to the absorption axis thereof. The slow axis direction of the λ/4 plate 4 is rotated counterclockwise to be positive with respect to the absorption axis direction (0 °) of the polarizing plate 2, and the angle β is set in the range of-20 ° to 20 ° (in fig. 8 (a) and (b) — 15 °).

Specifically, a preferred combination of the angle α and the angle β is explained. The angle α is preferably-80 ° to-70 °, more preferably-78 ° to-70 °, and still more preferably-76 ° to-70 °. In this case, the angle β is preferably-20 ° to-10 °, more preferably-18 ° to-10 °, and still more preferably-16 ° to-10 °.

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

By adjusting the slow axis direction (angle α) of the λ/2 plate 3B and the slow axis direction (angle β) of the λ/4 plate 4B so as to fall within such ranges, it is possible to suppress color change due to bending.

[ color tone change of circularly polarizing plate before and after bending ]

The circularly polarizing plates 1A and 1B of the present embodiment are characterized in thatThe color tone of the reflected light obtained before and after bending is not sandwiched by CIE1976L ^* a ^* b ^* A of color space ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. That is, the color tone of the reflected light obtained before and after bending is set so as not to fall over a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and not spanning b ^* Values of the coordinate axes. Thus, even if the color tone of the reflected light obtained before and after bending changes, the change in the color tone can be made inconspicuous.

Note that before and after the start of bending, even if a is ^* Value and b ^* At least one of the values is 0, and when the other sign is not changed, it is considered that the sign is not changed before and after the bending. That is, in this case, it is considered that the step a is not present ^* Coordinate axes and b ^* Coordinate axes.

Preferably, when at least one of the display devices 10A and 10B is bent such that the circularly polarizing plates 1A and 1B of the present embodiment are on the outer side (OUT) and when the display devices 10A and 10B are bent such that the circularly polarizing plates 1A and 1B of the present embodiment are on the inner side (IN), the color tone of the reflected light obtained before and after the bending is not sandwiched by the a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axes change sign, more preferably in neither case.

Specifically, referring to fig. 9, the change in color tone of the reflected light obtained before and after bending of the circularly polarizing plates 1A and 1B will be described. Fig. 9 is a diagram for explaining a change in color tone of reflected light obtained before and after bending of the circularly polarizing plates 1A and 1B ^* b ^* And (5) a chromaticity coordinate graph.

Since the change in color tone of the reflected light obtained before and after bending of the circularly polarizing plates 1A and 1B is evaluated to be close to a visual color tone, it is preferable to use a method called SCE method in which the regular reflection light is removed and the color tone is measured.

The reflection color tone can be measured by CM-2600d (a spectrocolorimeter manufactured by Konica Minolta Co., ltd.). According to "JIS Z8722: 2009", the setting conditions can be set as follows.

Light source: d65 light source

Measurement of diameter: 8mm phi

Field of view: 2 degree

The geometrical conditions are: geometric condition c

In the present embodiment, a reflective plate of aluminum is disposed on the surface of the circularly polarizing plates 1A and 1B opposite to the polarizer 2 side via the PSA layer 9, and the color tone before bending is measured by the SCE method. That is, in the case of the circularly polarizing plate 1A shown in fig. 1, an aluminum reflector is disposed on the 2 nd retardation film 4A side via the PSA layer 9. On the other hand, in the case of the circularly polarizing plate 1B shown in fig. 3, an aluminum reflector is disposed on the side of the retardation layer RF via the PSA layer 9. Thereafter, the circular polarizers 1A and 1B were bent at a curvature radius of 5mm, and after at least 1 bending, an aluminum reflection plate was again disposed on the surface of the circular polarizers 1A and 1B opposite to the polarizer 2 side, and color tone measurement by the SCE method was performed after bending. Thereafter, it was confirmed that a is not sandwiched between the reflected lights before and after bending of the circularly polarizing plates 1A and 1B, and the color tone of the reflected lights is changed ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign.

In the present embodiment, the hue of the reflected light obtained before and after bending is not so called "a" across ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign, as compared with, for example, a shown in FIG. 9 ^* b ^* A is not sandwiched in the chromaticity coordinate diagram ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axes are synonymous across quadrants. In this case, even if the color tone of the circularly polarizing plates 1A and 1B changes before and after bending, the change in color tone can be made inconspicuous. On the other hand, if sandwiching a ^* b ^* A in chromaticity coordinates ^* Coordinate axes or b ^* The coordinate axis crosses the quadrant, and the change in hue is easily observed (x in fig. 9).

In the circularly polarizing plates 1A and 1B of the present embodiment, the color tone of the reflected light obtained before and after the bending is set so as not to cross a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* Values of the coordinate axes. The color tone of the circularly polarizing plates 1A and 1B can be changed by adjusting the color tone or the phase difference between the circularly polarizing plates 1A and 1B. In addition, adjustment of the wavelength dispersion of the retardation film is also effective for control of color tone. For example, when the phase difference value between the circularly polarizing plates 1A and 1B is increased, a ^* Value and b ^* The value becomes low, and when the phase difference value between the circularly polarizing plates 1A and 1B is reduced, a is reduced ^* Value and b ^* The value becomes high.

The color tone of the polarizing plate (laminate comprising the polarizer 2 and the protective films 5 and 6 bonded to one or both surfaces thereof via the adhesive layer 8) is expressed in Hunter 1948Lab color space, and the orthorhombic a value before bending is preferably-10 or more and 10 or less, more preferably-5 or more and 5 or less. The orthogonal b value of the polarizing plate before bending is preferably-25 or more and 0 or less, and more preferably-20 or more and 0 or less. The setting conditions for measuring the color tone of the polarizing plate can be as follows.

Light source: c light source

Field of view: 2 degree

In the above range, the initial reflection color tone is not problematic, and it is easy to adjust the reflection color tone so as not to cross over the quadrant before and after bending by a combination of the bending direction and the retardation value of the retardation film.

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

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

In the circularly polarizing plates 1A and 1B of the present embodiment, the term "a" refers to the reflection color tone before and after bending ^* Value and b ^* Difference in value Δ a ^* 、Δb ^* The obtained color difference value is preferably 0 or more and 5 or less, and more preferably 0 or more and 3 or less. The term "A" is defined as [ (Delta a) ^* ) ² +(Δb ^* ) ² ] ^1/2 And calculating the color difference value.

The present invention is not necessarily limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, a touch sensor may be provided as an input tool of the display devices 10A and 10B. Specifically, like the display device 30 shown in fig. 10, the configuration of the display devices 10A and 10B may be combined with the configuration of the touch sensor 40 and the window film 50. Fig. 10 is a cross-sectional view showing another configuration example of a bendable display device 30 including circularly polarizing plates 1A and 1B. The circularly polarizing plate may be the circularly polarizing plate 1A shown in fig. 1 or the circularly polarizing plate 1B shown in fig. 3.

In the display device 30 shown in fig. 10, the touch sensor 40 is preferably disposed on the side of the circularly polarizing plates 1A and 1B facing the display panel 20, and the window film 50 is preferably disposed on the side opposite to the side of the circularly polarizing plates 1A and 1B facing the display panel 20. The presence of the circularly polarizing plates 1A and 1B on the visible side of the touch sensor 40 is preferable because the pattern of the touch sensor 40 is not easily visible and the visibility of the image displayed on the display panel 20 is improved.

Therefore, the display device 30 shown in fig. 10 has a structure in which the display panel 20, the touch sensor 40, the circularly polarizing plates 1A and 1B, and the window film 50 are laminated in this order using an adhesive, or the like. Further, a light-shielding pattern described later may be provided on at least one surface of the window film 50, the circularly polarizing plates 1A and 1B, or any of the layers of the touch sensor 40.

The order of laminating the touch sensor 40 and the window film 50 is not necessarily limited to the above-described configuration, and for example, the display panel 20, the circularly polarizing plates 1A and 1B, the touch sensor 40, and the window film 50 may be laminated in this order.

The window film 50 may be the protective film 5 constituting the circularly polarizing plates 1A and 1B described above, or the window film 50 may be configured to serve also as the protective film 5 of the circularly polarizing plates 1A and 1B.

Although not shown in the drawings, the present invention may be configured such that the touch sensor 40 is provided on the opposite side of the circularly polarizing plates 1A and 1B from the side facing the display panel 20 in addition to the configuration of the display devices 10A and 10B.

(Window film)

The window film 50 is disposed on the visible side of the bendable display device 30, and functions as a protective layer for protecting other components from external impact and environmental changes such as temperature and humidity. Conventionally, glass has been used as such a protective layer, but the window film 50 of the bendable display device 30 has a characteristic of being bendable, unlike glass, which is rigid and hard.

The window film 50 includes a flexible transparent substrate 51 and a hard coat layer 52 provided on at least one surface of the transparent substrate 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 of the transparent base 51 opposite to the circularly polarizing plates 1A and 1B. The hard coat layer 52 becomes the outermost layer of the display device 30 and is in contact with the outside air (air). The hard coat layer 52 may be provided on the circularly polarizing plates 1A and 1B side of the transparent base 51. The hard coat layer 52 may be provided only on one surface of the transparent base 51, or may be provided on both surfaces of the transparent base 51.

(transparent substrate)

The transparent base material 51 has a visible light transmittance of 70% or more, preferably 80% or more. The thickness of the transparent substrate 51 is 5 to 200. Mu.m, preferably 20 to 100. Mu.m.

Any transparent substrate 51 can be used as long as it is a polymer film having transparency. Specifically, there may be mentioned films formed from polyolefins such as polyethylene, polypropylene, polymethylpentene, norbornene, or cycloolefin derivatives having units containing cycloolefin monomers, (modified) celluloses such as diacetylcellulose, triacetylcellulose, and propionylcellulose, acrylics such as methyl methacrylate (co) polymers, polystyrenes such as styrene (co) polymers, acrylonitrile/butadiene/styrene copolymers, acrylonitrile/styrene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonates, polyesters such as polyarylates, polyamides such as nylon, polyimides, polyamideimides, polyether imides, polyether sulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, epoxy resins, and the like. Further, an unstretched film, a uniaxially stretched film, or a biaxially stretched film thereof may be used.

These polymers may be used alone or in combination of 2 or more kinds thereof in the transparent substrate 51. As the transparent substrate 51, a polyamide film, a polyamideimide film, a polyimide film, a polyester film, an olefin film, an acrylic film, and a cellulose film, which are excellent in transparency and heat resistance, are preferably used.

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

(hard coating)

The thickness of the hard coat layer 52 is not particularly limited, but is preferably 2 to 100 μm, for example. If 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, if the thickness of the hard coat layer 52 is more than 100 μm, the bending resistance is lowered, and there is a case where a problem of occurrence of curling due to curing shrinkage occurs. That is, if the thickness of the hard coat layer 52 is 2 μm or more, sufficient scratch resistance can be easily ensured. Further, if the thickness of the hard coat layer 52 is 100 μm or less, the problem of the reduction in bending resistance and the occurrence of curling due to curing shrinkage is less likely to occur.

The hard coat layer 52 may be formed by curing a hard coat layer composition containing a reactive material that forms a cross-linked structure by irradiation of active energy rays or thermal energy, however, a hard coat layer cured by irradiation of active energy rays is preferable.

The active energy ray is defined as an energy ray that can decompose a compound that generates an active species to generate an active species. Examples of the active energy ray include visible light, ultraviolet light, infrared light, X-ray, α -ray, β -ray, γ -ray, and electron beam. Among them, ultraviolet rays are particularly preferable.

The hard coat composition contains at least 1 polymer of a radical polymerizable compound and a cation polymerizable compound. The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound may be any functional group that can cause a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specific examples thereof include a vinyl group and a (meth) acryloyl group.

When the radical polymerizable compound has 2 or more radical polymerizable groups, the radical polymerizable groups may be the same or different. The number of radical polymerizable groups contained in 1 molecule of the radical polymerizable compound is preferably 2 or more in order to increase the hardness of the hard coat layer 52.

As the radical polymerizable compound, a compound having a (meth) acryloyl group is preferable from the viewpoint of high reactivity, and a compound called a multifunctional acrylate monomer having 2 to 6 (meth) acryloyl groups in 1 molecule, an oligomer called an epoxy (meth) acrylate, a urethane (meth) acrylate, or a polyester (meth) acrylate having several (meth) acryloyl groups in a molecule and having a molecular weight of several hundreds to several thousands can be preferably used. Preferably, the acrylic resin composition contains 1 or more selected from epoxy (meth) acrylate, urethane (meth) acrylate and polyester (meth) acrylate.

The cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxetane group, or a vinyl ether group. The number of the cationically polymerizable groups contained in 1 molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more, from the viewpoint of increasing the hardness of the hard coat layer 52. The cationically polymerizable compound is preferably a compound having at least 1 of an epoxy group and an oxetanyl group as a cationically polymerizable group.

From the viewpoint of reducing shrinkage accompanying the polymerization reaction, a cyclic ether group such as an epoxy group or an oxetane group is preferable. Further, the compound having an epoxy group in a cyclic ether group has advantages that it is easy to obtain various structures, durability of the obtained hard coat layer 52 is not adversely affected, and compatibility with a radical polymerizable compound is also easy to control.

The oxetanyl group in the cyclic ether group has advantages such as being easily higher in polymerization degree than an epoxy group, being low in toxicity, increasing the rate of formation of a network by a cationically polymerizable compound in the obtained hard coat layer 52, and forming an independent network without leaving an unreacted monomer in the film even in a region where the hard coat layer is mixed with a radically polymerizable compound.

Examples of the cationically polymerizable compound having an epoxy group include polyglycidyl ethers of polyhydric alcohols having an alicyclic ring, and alicyclic epoxy resins obtained by epoxidizing compounds containing a cyclohexene ring and a cyclopentene ring with an appropriate oxidizing agent such as hydrogen peroxide and a peracid; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl (meth) acrylate, and the like; examples of the epoxy resin include glycidyl ethers and novolac epoxy resins produced by the reaction of a bisphenol such as bisphenol a, bisphenol F, or hydrogenated bisphenol a, or a derivative thereof such as an alkylene oxide adduct or a caprolactone adduct with epichlorohydrin, and glycidyl ether type epoxy resins derived from a bisphenol.

In the hard coating composition, a polymerization initiator may be further included. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, and the polymerization initiator can be appropriately selected and used from these. These polymerization initiators are decomposed by at least one of irradiation with active energy rays and heating, and generate radicals or cations to advance radical polymerization and cationic polymerization.

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

The active energy ray radical polymerization initiator includes a Type1 radical polymerization initiator which generates radicals by decomposition of molecules and a Type2 radical polymerization initiator which coexists with a tertiary amine and generates radicals by a hydrogen abstraction reaction, and they may be used alone or in combination.

The cationic polymerization initiator may be any one that can release a substance that initiates cationic polymerization by at least one of irradiation with active energy rays and heating. As the cationic polymerization initiator, aromatic iodonium salts, aromatic sulfonium salts, cyclopentadienyl iron (II) complexes, and the like can be used. They can initiate cationic polymerization by some kind of irradiation with active energy rays or heating, or can initiate cationic polymerization by any kind of irradiation with active energy rays or heating, depending on the difference in structure.

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

The hard coating composition may further include one or more selected from a solvent and an additive. The solvent may be used without limitation as long as it is a solvent capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and is known as a solvent for a 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 touch sensors such as a resistive film type, a surface acoustic wave type, an infrared ray type, an electromagnetic induction type, and an electrostatic capacitance type have been proposed, and any type may be used. Among them, the electrostatic capacitance system is preferable.

The capacitive touch sensor 40 can be divided into an active region and an inactive region located in an outer region of the active region. The active region is a region corresponding to a region (display portion) of the display panel 20 where a screen is displayed, and is a region where a user's touch is sensed. On the other hand, the inactive area is an area corresponding to an area (non-display portion) of the display panel 20 where no screen is displayed.

The touch sensor 40 may include: the touch panel includes a substrate having a flexible characteristic, a sensing pattern formed on an active region of the substrate, and sensing lines formed on an inactive region of the substrate and connected to an external driving circuit via the sensing pattern and a pad portion. As a substrate constituting the touch sensor 40, a substrate including a polymer material is generally used.

As the substrate having the flexible property, the same material as the transparent base material 51 of the window film 50 can be used. The substrate of the touch sensor 40 preferably has toughness of 2000MPa% or more in order to suppress cracking. More preferably, the substrate has a toughness of 2000 to 30000 MPa%.

The toughness (toughnesss) of the substrate is defined as follows, in which the Stress (MPa) (vertical axis) is plotted against the strain (%) (horizontal axis) obtained by a tensile test of a polymer material constituting the substrate, and the lower area of the curve up to the breaking point in the obtained Stress-strain curve (Stress-strain curve) is defined as follows. From the viewpoint of suppressing the cracks in the touch sensor 40, it is desirable that the substrate constituting the touch sensor 40 has toughness in the above range.

The sensing pattern may include a 1 st pattern formed along a 1 st direction and a 2 nd pattern formed along a 2 nd direction. The 1 st pattern and the 2 nd pattern are arranged in different directions from each other. The 1 st pattern and the 2 nd pattern are formed on the same layer, and in order to sense a touched point, the patterns must be electrically connected.

The 1 st pattern is a pattern in which the unit patterns are connected to each other via a joint. On the other hand, the 2 nd pattern is a structure in which the unit patterns are separated from each other in an island-like form. Thus, in order to electrically connect the 2 nd pattern, an additional bridge electrode is required.

The sensing pattern may employ a known transparent electrode material. Examples thereof include Indium Tin Oxide (ITO), indium Zinc Oxide (IZO), zinc oxide (ZnO), indium Zinc Tin Oxide (IZTO), cadmium Tin Oxide (CTO), PEDOT (poly (3, 4-ethylenedioxythiophene)), carbon Nanotubes (CNT), graphene, and metal wires. Further, they may be used alone or in combination of 2 or more. Among them, ITO is preferably used.

The metal used for the metal wire is not particularly limited, but examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, \12486, 1252491, and the like. Further, they may be used alone or in combination of 2 or more.

The bridge electrode may be formed on an upper portion of the sensing pattern with an insulating layer interposed therebetween. 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 the same material as the sensing pattern, and may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of 2 or more of these metals.

Since the 1 st pattern and the 2 nd 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 tab of the 1 st pattern and the bridge electrode, or may be formed as a layer covering the sensing pattern. In the latter case, the bridge electrode may be connected to the 2 nd pattern via a contact hole formed in the insulating layer.

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

The optical adjustment layer may contain an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by applying a photocurable composition containing a photocurable organic binder and a solvent onto a substrate. The photocurable composition may further comprise inorganic particles. Inorganic particles may be used to increase the refractive index of the optically modifying layer.

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

The inorganic particles may include, for example, zirconium dioxide particles, titanium dioxide particles, aluminum oxide particles, and the like. The photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing assistant.

(Adhesives)

As the adhesive, an aqueous adhesive, an organic solvent adhesive, a solventless adhesive, a solid adhesive, a solvent volatile adhesive, a moisture curable adhesive, a heat curable adhesive, an anaerobic curable adhesive, an active energy ray curable adhesive, a curing agent mixed adhesive, a hot melt adhesive, a pressure sensitive adhesive (adhesive), a remoistenable adhesive, or the like can be used. Among them, water-based adhesives, active energy ray-curable adhesives, and the like are generally used. The above-mentioned adhesive can be used as a water-based adhesive or an active energy ray-curable adhesive.

(Binder)

The pressure-sensitive adhesive is classified into an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, and the like according to the base polymer, and any of them can be used. The adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like in addition to the main polymer.

The adhesive layer is formed by dissolving and dispersing each component constituting the adhesive in a solvent to obtain an adhesive composition, applying the adhesive composition onto a substrate, and drying the adhesive composition. The adhesive layer may be formed directly or may be separately transferred to the adhesive layer formed on the substrate.

It is also preferable to use a release film for covering the pressure-sensitive adhesive surface before bonding. The thickness of the adhesive layer when an active energy ray-curable adhesive is used is 0.1 to 500. Mu.m, preferably 1 to 300. Mu.m. When a multilayer adhesive is used, the thickness and type of each layer may be the same or different.

(light-shielding pattern)

The light shielding pattern may be applied as at least a portion of a bezel or a housing of the display device 30 that can be bent. The wiring disposed at the edge portion of the bendable display device 30 is hidden by the light shielding pattern and is hard to be viewed, thereby improving the visibility of the image.

The light blocking pattern may be in the form of a single layer or a plurality of layers. The color of the light-shielding pattern is not particularly limited, and the light-shielding pattern has various colors such as black, white, and metallic colors. The light-shielding pattern may be formed of a pigment for color development, and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. In addition, they can be used alone or in a mixture of 2 or more.

The light shielding pattern can be formed by various methods such as printing, photolithography, and inkjet. The thickness of the light-shielding pattern is 1 μm to 100 μm, preferably 2 μm to 50 μm. Further, it is preferable to provide a shape such as an inclination in the thickness direction of the light pattern.

[ examples ]

The effects of the present invention will be further explained below by way of examples. The present invention is not limited to the following examples, and can be implemented by appropriately changing the examples without changing the gist thereof.

[ example 1]

(preparation of polarizing plate)

After dyeing a long polyvinyl alcohol film in an aqueous solution containing iodine, the film was uniaxially stretched 6 times between rolls at different speed ratios in an aqueous solution containing boric acid to obtain a long polarizing plate having an absorption axis in the longitudinal direction. The long polarizing plate is stretched and then wound to form a wound body. The chromaticity of this polarizing plate was a =0.04 in cross section, b = -0.11 in cross section, the visibility correction polarization degree of the polarizing plate was about 99.995%, and the visibility correction individual transmittance of the polarizing plate was 42.7%.

(protective film)

As the protective film, a long triacetyl cellulose film (thickness: 40 μm, trade name: KC4UYW, manufactured by Konica Minolta Co., ltd.) was used. The protective film is prepared in the form of a roll. The protective film had an in-plane retardation value Re (550) of 5nm and a retardation value Rth (550) in the thickness direction of 45nm.

(retardation film No. 1)

A film containing a layer obtained by curing a liquid crystal compound and an alignment film was used as the 1 st retardation film. The 1 st retardation film is a lambda/4 plate, re (450)/Re (550) is less than 1.0, and Re (650)/Re (550) is greater than 1.0.

(retardation film No. 2)

A film containing a layer obtained by curing a liquid crystal compound and an alignment film was used as the 2 nd retardation film. The 2 nd retardation film is a positive C plate.

(ultraviolet ray curing adhesive)

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

3, 4-epoxycyclohexanecarboxylic acid 3',4' -epoxycyclohexylmethyl ester (trade name: CEL2021P, manufactured by Daicel K.K.): 70 parts by mass

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

2-ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagese ChemteX): 10 parts by mass

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

1, 4-diethoxynaphthalene: 2 parts by mass of

(preparation of circularly polarizing plate)

The polarizing plate, the protective film, the 1 st retardation film and the 2 nd retardation film were cut at 200mm × 300mm, and then the protective films were attached to both surfaces of the polarizing plate via a polyvinyl alcohol adhesive. The 1 st retardation film and the 2 nd retardation film are bonded to each other via the above-mentioned ultraviolet curable adhesive (adhesive layer). Further, the 1 st retardation film and the protective film were laminated via an acrylic pressure-sensitive adhesive layer (PSA layer). An acrylic pressure-sensitive adhesive layer (PSA layer) with a release film was attached to the 2 nd retardation film. In the above manner, a circularly polarizing plate was produced in which a protective film, a polarizing plate, a protective film, a PSA layer, a 1 st retardation film, a UV adhesive layer, a 2 nd retardation film, and a PSA layer were sequentially stacked.

The 1 st retardation film (λ/4 plate) was bonded to the polarizing plate so that the slow axis direction thereof was positive at-45 ° in the counterclockwise direction from the absorption axis direction (0 °) of the polarizing plate. The bending direction of the circular polarizing plate (direction orthogonal to the bending start line L) was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 0 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate). Thereafter, the circularly polarizing plate thus produced was cut into a size of 20mm × 80 mm.

(preparation of sample for evaluation)

After removing the release film from the circularly polarizing plate of example 1, the adhesive surface was attached to the matte surface of an aluminum foil (product name "MYFOIL (registered trademark)", manufactured by UACJ) to obtain a sample for evaluation. With respect to the evaluation sample obtained as described above, an evaluation test was performed in which the color tone before and after bending was measured, and the change in color and taste before and after bending was observed.

(measurement of color tone)

First, the SCE method measurement of the reflection color tone before bending was performed on the evaluation sample to obtain a before bending ^* Value and b ^* The value is obtained. Thereafter, a mandrel bar having a diameter of 5mm was pressed against the organic EL display device substitute side, and the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Outside (OUT) the aluminum foil. Thereafter, the measurement of the reflection color tone by the SCE method was performed to obtain a after bending by removing the bent state (in a flat state) after bending ^* Value and b ^* The value is obtained.

(Observation of color and taste)

The color and flavor before and after bending were visually observed to evaluate the easiness of observation of the change in color and flavor. In table 1, the evaluation is a when the change in color and taste is difficult to be observed, and the evaluation is B when the change is easy to be observed.

The contents summarized in example 1 are shown in table 1 below. In addition, for example 1, in a ^* b ^* The hue change before and after the bending is shown in the chromaticity diagram, and the obtained result is shown in fig. 11.

In example 1, it was confirmed that a is not interposed between the reflective films before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

(measurement of storage modulus at 30 ℃ C. Of adhesive layer test piece)

First, an ultraviolet-curable adhesive used for bonding the 1 st retardation film and the 2 nd retardation film was applied to one surface of a 50 μm thick cyclic polyolefin resin film using a coater (bar coater, first chemical and physical Co., ltd.), and then a 50 μm thick cyclic polyolefin resin film was laminated on the applied surface.

Then, an "H-tube" manufactured by Fusion UV Systems was used so that the cumulative light amount was 1500mJ/cm ² The adhesive layer is cured by ultraviolet irradiation (UVB). The thickness of the adhesive layer was 30 μm. The resultant was cut into a size of 5mm × 30mm, and the cyclic polyolefin resin films on both sides were peeled off to obtain a cured film of the adhesive.

The cured film was held at a 2cm clamp interval using a dynamic viscoelasticity measuring apparatus "DVA-220" manufactured by IT measurement control Co., ltd so that the long side thereof was in the stretching direction, and the storage modulus at a temperature of 30 ℃ was determined with the stretching and shrinking frequency set to 10Hz and the measurement temperature set to 30 ℃. The storage modulus of the adhesive layer test piece at 30 ℃ was 2060MPa.

[ example 2]

In example 2, the same sample for evaluation as in example 1 was produced except that the bending direction of the circularly polarizing plate was adjusted to 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 90 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate). Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

Hereinafter, the summary of example 2 is shown in table 1 below. In addition, for example 2, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 11.

In example 2, it was confirmed that a is not interposed between the sheets for the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 3]

In example 3, the same sample for evaluation as in example 1 was produced except that the bending direction of the circular polarizing plate was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate, 0 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate), and the retardation value of the λ/4 plate was changed. Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

The summary of example 3 is shown in table 1 below. In addition, for example 3, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 11.

In example 3, it was confirmed that a is not interposed between the reflected lights before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 4]

(lambda/2 plate)

A film comprising a layer obtained by curing a liquid crystal compound and an alignment film was used as a lambda/2 plate.

(lambda/4 plate)

A film comprising a layer obtained by curing a liquid crystal compound and an alignment film was used as a lambda/4 plate.

(production of circularly polarizing plate)

The polarizing plate, the protective film, the λ/2 plate and the λ/4 plate were cut at 200mm × 300mm, and then the protective film was attached to both surfaces of the polarizing plate via a polyvinyl alcohol adhesive. The λ/2 plate and the λ/4 plate were bonded via the above ultraviolet-curable UV adhesive (adhesive layer). Further, the λ/2 plate and the protective film were bonded via an acrylic pressure-sensitive adhesive layer (PSA layer). An acrylic pressure-sensitive adhesive layer (PSA layer) with a release film was adhered to the λ/4 plate. In this manner, a circular polarizing plate was produced 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 laminated.

The λ/4 plate is attached to the polarizing plate so that the slow axis direction thereof is rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to-15 °. Further, the bending direction of the circular polarizing plate was adjusted to be 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 60 ° with respect to the slow axis direction of the λ/4 plate. Thereafter, the circularly polarizing plate thus produced was cut into a size of 20mm × 80 mm.

After removing the release film from the circularly polarizing plate of example 4, the adhesive surface was attached to the matte surface of an aluminum foil (product name "MYFOIL (registered trademark)", manufactured by UACJ) to obtain a sample for evaluation. The evaluation samples thus obtained were subjected to the same evaluation test as in example 1.

The summary of example 4 is shown in table 1 below. In addition, for example 4, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 4, it was confirmed that a is not sandwiched between the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 5]

In example 5, the same evaluation sample as in example 4 was produced, except that the bending direction of the circularly polarizing plate was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and-30 ° with respect to the slow axis direction of the λ/4 plate. Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

The summary of example 5 is shown in table 1 below. In addition, for example 5, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 5, it was confirmed that a is not interposed between the sheets with respect to the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 6]

In example 6, the same evaluation sample as in example 4 was produced except that the bending direction of the circular polarizing plate was adjusted to 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 60 ° with respect to the slow axis direction of the λ/4 plate, and the phase difference value of the λ/4 plate was changed. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be Inside (IN) with respect to the aluminum foil.

Hereinafter, the summary of example 6 is shown in table 1 below. In addition, for example 6, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 11.

In example 6, it was confirmed that a is not interposed between the reflected lights before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 7]

In example 7, the same evaluation sample as in example 4 was produced except that the bending direction of the circularly polarizing plate was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and-30 ° with respect to the slow axis direction of the λ/4 plate, and the phase difference of the λ/4 plate was changed. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be Inside (IN) with respect to the aluminum foil.

The summary of example 7 is shown in table 1 below. In addition, for example 7, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 7, it was confirmed that the a-interlayer was not present in the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 8]

In example 8, the same evaluation sample as in example 1 was produced except that the bending direction of the circularly polarizing plate was adjusted to 0 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 45 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate). Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

The summary of example 8 is shown in table 1 below. In addition, for example 8, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 8, it was confirmed that a is not sandwiched between changes in color tone of reflected light obtained before and after bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 9]

In example 9, the same evaluation sample as in example 1 was produced except that the bending direction of the circularly polarizing plate was adjusted to 90 ° with respect to the absorption axis direction (0 °) of the polarizing plate and-45 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate). Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

The summary of example 9 is shown in table 1 below. In addition, for example 9, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 9, it was confirmed that a is not interposed between the sheets with respect to the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 10]

In example 10, the same evaluation sample as in example 4 was produced, except that the bending direction of the circularly polarizing plate was adjusted to-15 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 0 ° with respect to the slow axis direction of the λ/4 plate. Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

Hereinafter, for example 10The summary is shown in table 1 below. In addition, for example 10, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 11.

In example 10, it was confirmed that a is not sandwiched between changes in color tone of reflected light obtained before and after bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 11]

In example 11, the following 1 st retardation film was used as a λ/4 plate, unlike example 1. Further, the 1 st retardation film and the 2 nd retardation film were laminated with an acrylic pressure-sensitive adhesive layer (PSA layer). The 1 st retardation film was disposed so that its slow axis formed an angle of-45 ° with respect to the absorption axis of the polarizing plate. Except for this, a circularly polarizing plate was produced in the same manner as in example 1.

(No. 1 retardation film)

A film obtained by uniaxially stretching a film made of a resin containing polycarbonate was used as the 1 st retardation film. The in-plane retardation value Re (550) of the 3 rd retardation film was 143.5nm, re (450)/Re (550) was less than 1.0, and Re (650)/Re (550) was more than 1.0.

In example 11, the same sample for evaluation as in example 1 was produced except that the bending direction of the circularly polarizing plate was adjusted to 0 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 45 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate). Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Inside (IN) the aluminum foil.

The contents summarized in example 11 are shown in table 1 below. In addition, for example 11, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 11, it was confirmed that the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plateWithout sandwiching a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 12]

In example 12, the same evaluation sample as in example 11 was produced except that the bending direction of the circularly polarizing plate was adjusted to 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 90 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate). Thereafter, the same evaluation test as in example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Outside (OUT) the aluminum foil.

The contents summarized in example 12 are shown in table 1 below. In addition, for example 12, will be at a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 12, it was confirmed that a is not sandwiched between changes in color tone of reflected light obtained before and after bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 13]

In example 13, films containing a cycloolefin resin were used for each of the λ/2 plate and the λ/4 plate, and the λ/2 plate and the λ/4 plate were bonded to each other through an acrylic pressure-sensitive adhesive layer (PSA layer). The λ/4 plate is attached to the polarizing plate so that the slow axis direction thereof is rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to-15 °. Further, the bending direction of the circularly polarizing plate was adjusted to 75 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 90 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same evaluation sample as in example 4 was prepared. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be Inside (IN) with respect to the aluminum foil.

Hereinafter, for example 13, the following will be summarizedThe contents of the results are shown in table 1 below. In addition, for example 13, will be at a ^* b ^* Fig. 12 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 13, it was confirmed that a is not sandwiched between changes in color tone of reflected light obtained before and after bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 14]

In example 14, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof positively rotated by-15 ° counterclockwise from the absorption axis direction (0 °) of the polarizing plate. Further, the bending direction of the circular polarizing plate was adjusted to-15 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 0 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same evaluation sample as in example 13 was prepared. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Inside (IN) the aluminum foil.

The contents summarized in example 14 are shown in table 1 below. In addition, for example 14, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 12.

In example 14, it was confirmed that the a-interlayer was not present in the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 15]

In example 15, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof was rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to positive-15 °. Further, the bending direction of the circular polarizing plate was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and-30 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same sample for evaluation as in example 13 was prepared. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Inside (IN) the aluminum foil.

The summary of example 15 is shown in table 1 below. In addition, for example 15, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 12.

In example 15, it was confirmed that a is not sandwiched between changes in color tone of reflected light obtained before and after bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 16]

In example 16, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof was rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to positive-15 °. Further, the bending direction of the circular polarizing plate was adjusted to be 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 60 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same sample for evaluation as in example 13 was prepared. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Inside (IN) the aluminum foil.

The contents summarized in example 16 are shown in table 1 below. In addition, for example 16, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 12.

In example 16, it was confirmed that the a-interlayer was not present in the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 17]

In example 17, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to positive-15 °. Further, the bending direction of the circular polarizing plate was adjusted to 75 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 90 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same evaluation sample as in example 13 was prepared. Thereafter, the same evaluation test as in example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Outside (OUT) the aluminum foil.

The summary of example 17 is shown in table 1 below. In addition, for example 17, will be at a ^* b ^* Fig. 12 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 17, it was confirmed that the a-interlayer was not present in the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 18]

In example 18, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof was rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to positive-15 °. Further, the bending direction of the circularly polarizing plate was adjusted to-15 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 0 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same evaluation sample as in example 13 was prepared. Thereafter, the same evaluation test as in example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Outside (OUT) the aluminum foil.

The contents summarized in example 18 are shown in table 1 below. In addition, for example 18, will be at a ^* b ^* The results obtained by illustrating the change in color tone before and after bending in the chromaticity coordinate graph are shown in fig. 12.

In example 18, for a circleThe color tone of the reflected light obtained before and after the bending of the polarizing plate was changed, and it was confirmed that the polarizing plate was not sandwiched by a ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 19]

In example 19, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof was rotated clockwise from the absorption axis direction (0 °) of the polarizing plate to positive-15 °. Further, the bending direction of the circular polarizing plate was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and-30 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same sample for evaluation as in example 13 was prepared. Thereafter, the same evaluation test as in example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Outside (OUT) the aluminum foil.

The contents summarized in example 19 are shown in table 1 below. In addition, for example 19, will be in a ^* b ^* Fig. 12 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 19, it was confirmed that the a-interlayer was not present in the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

[ example 20]

In example 20, the λ/4 plate was attached to the polarizing plate so that the slow axis direction thereof positively rotated by-15 ° counterclockwise from the absorption axis direction (0 °) of the polarizing plate. Further, the bending direction of the circularly polarizing plate was adjusted to 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 60 ° with respect to the slow axis direction of the λ/4 plate. Except for this, the same sample for evaluation as in example 13 was prepared. Thereafter, the same evaluation test as in example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Outside (OUT) the aluminum foil.

The summary of example 20 is shown in table 1 below. In addition, for example 20, will be at a ^* b ^* Fig. 12 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In example 20, it was confirmed that the a-interlayer was not present in the change in color tone of the reflected light obtained before and after the bending of the circularly polarizing plate ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste was not noticeable.

Comparative example 1

In comparative example 1, the same sample for evaluation as in example 1 was prepared, except that the bending direction of the circular polarizing plate was adjusted to 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate, 90 ° with respect to the slow axis direction of the 1 st retardation film (λ/4 plate), and the retardation value of the λ/4 plate was changed. Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

The summary of comparative example 1 is shown in table 1 below. In addition, for comparative example 1, will be in a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In comparative example 1, it was confirmed that the gap a was interposed between the reflected light and the circularly polarizing plate before and after the bending ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste can be easily confirmed.

Comparative example 2

In comparative example 2, the same evaluation sample as in example 4 was produced except that the bending direction of the circular polarizing plate was adjusted to 45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and 60 ° with respect to the slow axis direction of the λ/4 plate, and the phase difference value of the λ/4 plate was changed. Thereafter, the same evaluation test as in example 1 was performed on the evaluation sample.

The summary of comparative example 2 is shown in table 1 below. In addition, forComparative example 2, will be in a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In comparative example 2, it was confirmed that the gap a was interposed between the reflected light and the circularly polarizing plate before and after the bending ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste can be easily confirmed.

Comparative example 3

In comparative example 3, the same evaluation sample as in example 4 was produced except that the bending direction of the circular polarizing plate was adjusted to-45 ° with respect to the absorption axis direction (0 °) of the polarizing plate and-30 ° with respect to the slow axis direction of the λ/4 plate, and the phase difference of the λ/4 plate was changed. Thereafter, the same evaluation test as IN example 1 was performed on this evaluation sample except that the circularly polarizing plate was bent along the outer peripheral surface of the mandrel bar so as to be positioned Inside (IN) the aluminum foil.

The summary of comparative example 3 is shown in table 1 below. In addition, for comparative example 3, will be in a ^* b ^* Fig. 11 shows the results of the chromaticity diagram illustrating the change in color tone before and after bending.

In comparative example 3, it was confirmed that the gap a was interposed between the reflected light and the circularly polarizing plate before and after the bending ^* b ^* A in chromaticity coordinates ^* Coordinate axes and b ^* The coordinate axis changes sign. In addition, the change in color and taste can be easily confirmed.

[ Table 1]

[ evaluation ]

As is clear from table 1, fig. 11, and fig. 12, according to examples 1 to 20 of the present invention, it is possible to make the change in the color tone (color and taste) of the reflected light at the curved portion less noticeable than in comparative examples 1 to 3.

Description of the symbols

1A, 1B circularly polarizing plate, 2 polarizer, 3A 1 st retardation film (1 st retardation layer), 4A 2 nd retardation film (2 nd retardation layer), 3B λ/2 plate (1/2 wavelength plate), 4B λ/4 plate (1/4 wavelength plate), 5, 6 protective film (protective layer), 7PSA layer (adhesive layer), 8 adhesive layer or adhesive layer, 9PSA layer (adhesive layer), 10 display device, 20 display panel, 30 display device, 40 touch sensor, 50 window film, 200 organic EL element, 210 substrate, 220 st electrode, 1 st electrode, 230 organic EL layer, 240 nd electrode, 250 th sealing layer.

Claims (10)

1. A circularly polarizing plate for use in a bendable display device,

the circularly polarizing plate comprises a polarizing plate and at least 1 or more kinds of retardation layers arranged on one side of the polarizing plate, wherein the transmittance of the polarizing plate for the visibility-correcting monomer is 42% or more and 60% or less,

in the reflected tone before bending, a ^＊ A value of-4.5 to-3.2, and b ^＊ The value is-8.5 to-3.3,

the color tone of the reflected light obtained before and after bending is not sandwiched by a ^＊ b ^＊ A in chromaticity coordinates ^＊ Coordinate axes and b ^＊ The coordinate axis changes sign.

2. The circularly polarizing plate according to claim 1,

the phase difference layer comprises a 1/4 wavelength plate.

3. The circularly polarizing plate of claim 2,

the phase difference layer comprises a 1/2 wavelength plate.

4. The circularly polarizing plate according to claim 2 or 3,

the phase difference layer includes a positive C plate.

5. The circularly polarizing plate according to any one of claims 1 to 3,

the phase difference layer includes a layer obtained by solidifying a liquid crystal compound.

6. The circularly polarizing plate according to any one of claims 1 to 3,

at least a portion of the display device is curved with a radius of curvature of 8mm or less.

7. The circularly polarizing plate according to any one of claims 1 to 3,

the display device is an organic electroluminescent display device.

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

9. The bendable display device according to claim 8, comprising:

a touch sensor disposed on a side of the circular polarizing plate facing the display panel, and a window film disposed on an opposite side of the circular polarizing plate facing the display panel.

10. Bendable display device according to claim 8,

the touch panel includes a touch sensor disposed on the opposite side of the circularly polarizing plate from the display panel.

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