CN111295604A - Circular polarizing plate and display device - Google Patents

Abstract

The invention provides a circularly polarizing plate (1) used in a bendable display device, the liquid crystal display device comprises a polarizing plate (2) and a phase difference layer (RF) arranged on one side of the polarizing plate (2), wherein the transmittance of a visibility-correcting monomer of the polarizing plate (2) is 42% or more, the phase difference layer (RF) comprises an 1/2 wavelength plate (3) and a 1/4 wavelength plate (4), the 1/2 wavelength plate (3) and the 1/4 wavelength plate (4) respectively comprise layers obtained by curing a liquid crystal compound, the slow axis direction of the 1/4 wavelength plate (4) is positive and in the range of-20 DEG to 20 DEG by rotating counterclockwise from the absorption axis direction of the polarizing plate (2), and the bending direction of the display device is set to be in the range of 80 DEG to 100 DEG or-10 DEG to 10 DEG with respect to the slow axis direction of the 1/4 wavelength plate (4).

Description

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 the Japanese application No. 2017-217106 at 11/10/2017 and Japanese application No. 2018-201205 at 25/10/2018, the contents of which are incorporated herein by reference.

Background

In the past, circularly 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 has been 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 the above problem, patent document 1 proposes a circularly polarizing plate including a retardation film including an 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, 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 document

Patent document 1: 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.

For this reason, circular polarizing plates applied to bendable display devices need to follow the bent portions of the display devices. Further, it is also required that wrinkles are not easily generated before and after bending the circular polarizing plate.

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide a circularly polarizing plate which is less likely to cause wrinkles due to bending while reducing color changes due to 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, the circularly polarizing plate used for a bendable display device is characterized by comprising a polarizing plate and a phase difference layer arranged on one side of the polarizing plate, the polarizing plate has a visibility-correcting monomer transmittance of 42% or more, the phase difference layer includes an 1/2 wavelength plate and a 1/4 wavelength plate, the 1/2 wave plate and the 1/4 wave plate each include a layer obtained by curing a liquid crystal compound, the slow axis direction of the 1/4 wave plate is positive in the counterclockwise direction from the absorption axis direction of the polarizing plate and is in the range of-20 DEG to 20 DEG, and the bending direction of the display device is set to a range of 80 DEG to 100 DEG or-10 DEG to 10 DEG with respect to the slow axis direction of the 1/4 wavelength plate.

In the circularly polarizing plate, the 1/2 wavelength plate and the 1/4 wavelength plate may be bonded to each other with an adhesive layer interposed therebetween.

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

In the circularly polarizing plate, the color tone of the reflected light obtained before and after bending may not be a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes the composition of the sign.

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

The display device may 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 disposed on a side opposite to a side facing the display panel.

That is, the present invention has the following aspects.

[1] A circularly polarizing plate used for a bendable display device, comprising a polarizing plate and a retardation layer disposed on one side of the polarizing plate, wherein the polarizer has a visibility-correcting monomer transmittance of 42% or more, the retardation layer comprises an 1/2 wavelength plate and a 1/4 wavelength plate, the 1/2 wavelength plate and the 1/4 wavelength plate each comprise a layer obtained by curing a liquid crystal compound, the slow axis direction of the 1/4 wavelength plate is rotated clockwise from the absorption axis direction of the polarizing plate to a positive value in the range of-20 DEG to 20 DEG, and the bending direction of the display device is set to a range of 80 DEG to 100 DEG or-10 DEG to 10 DEG with respect to the slow axis direction of the 1/4 wavelength plate.

[2] The circularly polarizing plate according to [1], wherein the 1/2 wavelength plate and the 1/4 wavelength plate are bonded to each other with an adhesive layer interposed therebetween.

[3] The circularly polarizing plate according to any one of [1] and [2], wherein the display device is an organic electroluminescent display device.

[4]According to [1]～[3]The circularly polarizing plate according to any one of the above items, 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.

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

[6] The bendable display device according to [5], comprising a touch sensor disposed on 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.

[7] The bendable display device according to [5], comprising 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 in which a color change due to bending is reduced and wrinkles due to bending are less likely to occur, and a bendable display device including the circularly polarizing plate.

Drawings

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

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

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

Fig. 4A is a schematic diagram for explaining a bent state of the display device.

Fig. 4B is a schematic diagram for explaining a bent state of the display device.

Fig. 4C is a schematic diagram for explaining a bent state of the display device.

Fig. 4D is a schematic diagram for explaining a bent state of the display device.

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

Fig. 6 is a cross-sectional view showing another configuration example of a bendable display device including the circularly polarizing plate shown in fig. 1.

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.

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

As shown in fig. 1, the circularly polarizing plate 1 of the present embodiment includes a polarizer 2 and a retardation layer RF including an 1/2 wavelength (λ/2) plate 3 and a 1/4 wavelength (λ/4) plate 4 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 3 is laminated via a PSA layer (adhesive layer) 7. The λ/2 plate 3 and the λ/4 plate 4 are laminated via an adhesive layer or an adhesive layer 8. On the surface of the circularly polarizing plate 1 facing the λ/4 plate 4, a PSA layer (pressure-sensitive adhesive layer) 9 is disposed for lamination to a display panel 20 described later. A release film (not shown) is attached to the surface of the PSA layer 9 until just before use. 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 a 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 simultaneously with the 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, 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 described in japanese patent application laid-open No. 2016-170368. 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, or 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-correcting 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, a is less likely to be interposed between the colors of reflected light before and after bending, which will be 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, when the visibility correction polarization degree of the polarizing plate 2 is 95% or more, the function as an antireflection film is easily exhibited.

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 visibility correction monomer transmittance can be measured by using an absorption spectrophotometer with an integrating sphere ("V7100" manufactured by japan spectrophotometers) 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 of the polarizing plate 2 to 42% or more, the cross-color tone of the polarizing plate 2 can be easily adjusted to a position away from the neutral side, and therefore, the color change can be made inconspicuous before and after bending, which will be described later. On the other hand, if it exceeds 50%, the degree of polarization is 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.

The λ/2 plate 3 has a function of changing the orientation (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.

The in-plane retardation value of λ/2 plate 3 at a specific wavelength λ nm, i.e., Re (λ), 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 to satisfy 220 nm. ltoreq. Re (550). ltoreq.290 nm.

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

The thickness of the λ/2 plate 3 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and 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 3 is a value obtained by measuring the thickness of an arbitrary 5 points in the plane and arithmetically averaging the measured values.

The λ/2 plate 3 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 λ/2 plate 3 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 λ/2 plate 3 preferably includes a layer obtained by curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, 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 thereof. 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-phase-transfer-of-polymer ダイナミクス (kinetics of physical-phase transfer), native-well, page 2, Shibo Shigaku, 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.

As the rod-like liquid crystal compound, for example, the compounds 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 can be suitably used. As the discotic liquid crystal compound, for example, compounds described in paragraphs [0020] to [0067] of Japanese patent laid-open No. 2007-108732 or paragraphs [0013] to [0108] of Japanese patent laid-open No. 2010-244038 can be suitably used.

The λ/2 plate 3 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 3 is preferably a layer formed by fixing a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group by polymerization, 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 λ/2 plate 3 is not particularly limited, and known methods can be used. For example, the λ/2 plate 3 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 a polymerization initiator other than the above-described liquid crystal compound, and the polymerization initiator used may be selected from, for example, thermal polymerization initiators and photopolymerization initiators depending on the form of the polymerization reaction, and examples of the photopolymerization initiator include α -carbonyl compounds, acyloin ethers, α -hydrocarbon-substituted aromatic acyloin compounds, polyquinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, and 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, 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] in Japanese patent application laid-open No. 2001-330725 and compounds described in paragraphs [0069] to [0126] in 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 3 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 or polyimide, or a derivative thereof is preferably used as the polymer material, and particularly, modified or unmodified polyvinyl alcohol is preferably 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 No. 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 not more than 20 μm, preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, and still more preferably 0.01 to 1 μm.

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

The in-plane retardation value of the λ/4 plate 4 at a specific wavelength λ nm, that is, 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 value at a wavelength of 550nm, preferably satisfies 100 nm. 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 lambda/4 plate 4 measured at a wavelength of 550nm, is preferably-120 to 120nm, more preferably-80 to 80 nm.

The thickness of the λ/4 plate 4 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and still 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 4 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 4 preferably comprises 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 3 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 contained in the circularly polarizing plate 1, 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 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 3). The protective film 6 may be disposed on the inner surface of the polarizing plate 2 (the surface facing the λ/2 plate 3).

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 λ/2 plate 3 can 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, a copolymer of these resins or a resin in which a part of the hydroxyl groups is modified with another substituent 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 generally 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 carbonate groups. 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). Preferably, poly (methyl) acrylate such as poly (methyl (meth) acrylate) is used) Acrylic acid C_1－6A 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, -80 nm to +80 nm.

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 +10 nm. The thickness of the protective film 6 in this case is preferably 20 μm to 200 μm, more preferably 30 μm to 100 μm, 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. The circularly polarizing plate 1 can prevent wrinkles from occurring during bending by laminating the λ/2 plate 3 and the λ/4 plate 4 with the adhesive layer 8 interposed therebetween.

Since the active energy ray-curable adhesive exhibits good adhesiveness, an active energy ray-curable adhesive composition containing a cationically polymerizable curable compound and/or a radically polymerizable curable compound can be preferably used. The active energy ray-curable adhesive may further 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 λ/2 plate 3 and the λ/4 plate 4 are bonded to each other using an active energy ray-curable adhesive, the λ/2 plate 3 and the λ/4 plate 4 are laminated via the active energy ray-curable adhesive serving as the adhesive layer 8, and then the adhesive layer is cured by irradiation with an active energy ray such as ultraviolet ray, visible light, electron beam, or X-ray. 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. When an aqueous adhesive is used, the λ/2 plate 3 and the λ/4 plate 4 may be laminated via the 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 3000 MPa. By bonding the λ/2 plate 3 and the λ/4 plate 4 with the hard adhesive layer 8 exhibiting such a storage modulus, it is possible to further easily prevent the occurrence of wrinkles in the retardation layer at the time of bending.

The storage modulus of the adhesive layer 8 at 30 ℃ is measured by the following method when the storage modulus of the adhesive layer 8 of the circularly polarizing plate 1 at 30 ℃ can be directly measured. 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.

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

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

Specifically, as shown in fig. 2, the display device 10 of the present embodiment includes a bendable display panel 20 and the circularly polarizing plate 1 disposed on the visible side of the display panel 20. The circularly polarizing plate 1 is attached to the visible side surface of the display panel 20 via the PSA layer 9 so that the polarizer 2 is visible.

In the display device 10 of the present embodiment, light passing through the polarizing plate 2 is linearly polarized by external light entering from the visible side of the display panel 20. The linearly polarized light passes through the λ/2 plate 3 to be converted into circularly polarized light, and then passes through the λ/4 plate 4 to be converted into linearly 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 λ/4 plate 4 and the λ/2 plate 3 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.

An example of the display panel 20 includes an organic EL element 200 as shown in fig. 3. Fig. 3 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. When the substrate 210 having flexibility is used, the display device 10 can be bent at 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 device 10 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 transparent conductive materials such as 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), indium tin oxide containing titanium oxide (ITTiO), and 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 10 nm.

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 terms of facilitating electron injection and improving 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 element 200 can be manufactured in the order of steps described in japanese patent laid-open No. 2012-1699236, 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 plate 1 by a roll-to-roll process, and an organic EL display device can be continuously manufactured.

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

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 device 10 to which the present invention is applied may be an embodiment including the display panel 20 including a liquid crystal display element and the circularly polarizing plate 1 disposed on the visible side of the display panel 20, for example.

The display device 10 of the present embodiment further includes a state in which it is bent (a state in which the bending is fixed) as shown in fig. 4A to 4D. Fig. 4A to 4D are schematic views for explaining a bent state of the display device 10.

Specifically, the display device 10 may be curved at the center portion like a folding type as shown in fig. 4A and 4B, 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. 4C and 4D.

As shown in fig. 4A to 4D, the display device 10 may be bent in the longitudinal direction or in the width direction. That is, the display device 10 may be formed by bending a specific portion (for example, a part or all of four corners in an oblique direction) according to the use thereof.

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

With reference to fig. 5(a) and (b), the relationship between the bending direction of the display device 10 (the direction orthogonal to the bending start line L) and the absorption axis direction of the polarizing plate 2, and the relationship between the slow axis direction of the λ/2 plate 3 and the slow axis direction of the λ/4 plate 4 will be described. Fig. 5(a) and (b) are schematic diagrams for explaining the relationship between the bending direction of the display device 10 and the absorption axis direction of the polarizing plate 2, and the relationship between the slow axis direction of the λ/2 plate 3 and the slow axis direction of the λ/4 plate 4. In fig. 5(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 3 is indicated by a "one-dot chain line", and the slow axis direction of the λ/4 plate 4 is indicated by a "solid line".

As shown in fig. 5(a) and (b), the display device 10 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. 5(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 10 is viewed from the normal direction of the flat portion 10a (the Z-axis direction in fig. 5(a) and (b)), the bending direction of the display device 10 corresponds to the direction (the Y-axis direction in fig. 5(a) and (b)) orthogonal to the linear bending start line L.

In the display device 10 of the present embodiment, the bending direction of the display device 10 is set to a range of-10 ° to 10 ° (0 ° in fig. 5 (a)) or 80 ° to 100 ° (90 ° in fig. 5 (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 4.

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

The slow axis direction of the λ/4 plate 4 is set to form an angle β with respect to the absorption axis direction of the polarizer 2, that is, the circularly polarizing plate 1 is disposed on the surface of the display panel 20 such that the slow axis direction of the λ/4 plate 4 forms an angle β with respect to the absorption axis direction of the polarizer 2. note that the angles α and β are both angles that are positive in counterclockwise rotation with respect to the absorption axis direction (0 °) of the polarizer 2, and the angle β is set to a range of-20 ° to 20 ° (minus 15 ° in fig. 5(a) and (b)).

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 which 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 which 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 3 and the slow axis direction (angle β) of the λ/4 plate 4 so as to fall within such ranges, color change due to bending can be suppressed.

In addition, the circularly polarizing plate 1 of the present embodiment is preferably such that the color tone of the reflected light obtained before and after bending does not sandwich CIE1976L^＊a^＊b^＊A of color space^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign. That is, it is preferable that the color tone of the reflected light measured by the SCE method obtained before and after the 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. For example, the control can be performed so as not to cross each coordinate axis by adjusting the color tone of the polarizing plate or adjusting the phase difference value of the phase difference layer.

In addition, the adjustment of the wavelength dispersion of the retardation film is also effective for controlling the color tone. For example, in the case where the phase difference value of the circularly polarizing plate 1 is increased, a^＊Value and b^＊The value becomes low, and a is a when the phase difference value of the circularly polarizing plate 1 is reduced^＊Value and b^＊The value becomes high.

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. The bending method for the evaluation may be the method described in the examples described later.

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

Light source: d65 light source

Measurement of diameter: 8mm phi

Field of view: 2 degree

Geometric conditions: geometric condition c

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 device 10. Specifically, as in the display device 30 shown in fig. 6, the touch sensor 40 and the window film 50 may be provided in addition to the configuration of the display device 10. Fig. 6 is a cross-sectional view showing another configuration example of a bendable display device 30 including the circularly polarizing plate 1.

In the display device 30 shown in fig. 6, the touch sensor 40 is preferably disposed on the side of the circularly polarizing plate 1 facing the display panel 20, and the window film 50 is preferably disposed on the side opposite to the side of the circularly polarizing plate 1 facing the display panel 20. The presence of the circularly polarizing plate 1 on the visible side of the touch sensor 40 is preferable because the pattern of the touch sensor 40 is less likely to be observed and the visibility of the image displayed on the display panel 20 is improved.

Therefore, the display device 30 shown in fig. 6 has a structure in which the display panel 20, the touch sensor 40, the circularly polarizing plate 1, 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 any of the window film 50, the circularly polarizing plate 1, and 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 plate 1, 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 plate 1 described above, or the window film 50 may be configured to serve also as the protective film 5 of the circularly polarizing plate 1.

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 plate 1 from the side facing the display panel 20 in addition to the configuration of the display device 10.

(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 or 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 has a transparent substrate 51 that can be bent, 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. 6, the hard coat layer 52 constituting the window film 50 is provided on the surface of the transparent substrate 51 opposite to the circularly polarizing plate 1. 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 surface of the transparent base 51 on the circularly polarizing plate 1 side. The hard coat layer 52 may be provided only on one surface of the transparent base material 51, or may be provided on both surfaces of the transparent base material 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 μm, preferably 20 to 100 μm.

Any transparent substrate 51 can be used as long as it is a polymer film having transparency. Specific examples thereof include polyolefins such as polyethylene, polypropylene, polymethylpentene, norbornene, or cycloolefin derivatives having a unit containing a cycloolefin monomer, (modified) celluloses such as diacetylcellulose, triacetylcellulose, and propionylcellulose, acrylics such as a methyl methacrylate (co) polymer, polystyrenes such as a styrene (co) polymer, acrylonitrile/butadiene/styrene copolymers, acrylonitrile/styrene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonates, polyesters such as polyarylates, polyamides such as nylons, polyimides, polyamideimides, polyether imides, and copolymers of styrene with a vinyl methacrylate (meth) acrylate (meth), And films formed of high molecules such as polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, and epoxy resins. 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, and examples of the active energy ray include visible light, ultraviolet ray, infrared ray, X-ray, α ray, β ray, γ ray, and electron beam.

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 that the polymerization degree is easily increased compared to the epoxy group, the toxicity is low, the rate of forming a network of the cationically polymerizable compound in the obtained hard coat layer 52 is increased, and an independent network is formed without leaving an unreacted monomer in the film even in a region where the cationically polymerizable compound is mixed.

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; 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 initiator 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% based on the whole (100 wt%) of the hard coat composition. 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, the curing can be sufficiently advanced, and the mechanical properties and the 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 liquid crystal display device 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 51 of the window film 50 can be used. The substrate of the touch sensor 40 preferably has toughness of 2000 MPa% 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 by plotting Stress (MPa) (vertical axis) on the strain (%) (horizontal axis) obtained by a tensile test of a polymer material constituting the substrate, and defining the area of the lower part of the curve up to the fracture point in the obtained Stress-strain curve (Stress-strain curve). 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 form 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 manner. 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 a metal wire. 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, テレニウム, chromium, 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 μm, preferably 1 to 300 μm. 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 0.04 for a perpendicular a and-0.11 for a perpendicular b, the visibility correction polarization degree of the polarizing plate was about 99.995%, and the visibility correction single 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 45 nm.

(lambda/2 plate)

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

(lambda/4 plate)

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

(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

(preparation 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-described 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 attached to the λ/4 plate.

The λ/2 plate was disposed so that its slow axis was at an angle α of-75 ° with respect to the absorption axis of the polarizer, the λ/4 plate was disposed so that its slow axis was at an angle β of-15 ° with respect to the absorption axis of the polarizer, and the absorption axis of the polarizer was parallel to the longitudinal direction.

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 λ/2 plate, a UV adhesive layer, a λ/4 plate, and a PSA layer were sequentially stacked. 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 pressure-sensitive 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.

As a result, as in the case shown in fig. 5(a), the slow axis of the λ/2 plate forms an angle α of-75 ° with respect to the absorption axis direction of the polarizing plate, the slow axis of the λ/4 plate forms an angle β of-15 ° with respect to the absorption axis direction of the polarizing plate, the bending direction of the circular polarizing plate forms an angle 0 ° with respect to the slow axis direction of the λ/4 plate, the bending start line L of the circular polarizing plate forms 75 ° with respect to the absorption axis direction of the polarizing plate.

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

First, an ultraviolet-curable adhesive used for bonding λ/2 plates and λ/4 plates was applied to one surface of a 50 μm thick cyclic polyolefin resin film using a coater (bar coater, first chemical and chemical Co., Ltd.), and a 50 μm thick cyclic polyolefin resin film was further laminated on the applied surface.

Then, an accumulated light amount was set to 1500mJ/cm by using an "H-tube" manufactured by Fusion UV Systems²The adhesive layer is cured by ultraviolet irradiation (UVB). The thickness of the adhesive layer was 30 μm. The film was cut into a size of 5mm × 30mm, and the cyclic polyolefin resin films on both surfaces 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 2060 MPa.

(evaluation test)

While pressing a mandrel bar having a diameter of 5mm, the sample for evaluation was bent along the outer peripheral surface of the mandrel bar so that the circularly polarizing plate was located Outside (OUT) the aluminum foil, and the bending direction of the display device 10 was at an angle of 0 ° with respect to the slow axis direction (0 °) of the λ/4 plate. Thereafter, the circularly polarizing plate was visually observed after being bent, and the circularly polarizing plate with little color change was evaluated as "a" and the circularly polarizing plate with large color change was evaluated as "B". The circularly polarizing plate with less wrinkles was evaluated as "a", and the circularly polarizing plate with more wrinkles was evaluated as "B". The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

[ example 2]

In example 2, the same evaluation sample as in example 1 was prepared. Thereafter, the evaluation sample was bent along the outer peripheral surface of the mandrel bar so that the circularly polarizing plate was located Inside (IN) the aluminum foil. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

[ example 3]

In example 3, as in the case shown in fig. 5(b), a sample for evaluation was produced in the same manner as in example 1, except that the bending direction of the circular polarizing plate was set to an angle of 90 ° with respect to the slow axis direction of the λ/4 plate and the bending start line L of the circular polarizing plate was set to-15 ° with respect to the absorption axis direction of the polarizing plate. Thereafter, the sample for evaluation was bent under the same conditions as in example 1. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

[ example 4]

In example 4, the same evaluation sample as in example 3 was prepared. Thereafter, the evaluation sample was bent along the outer peripheral surface of the mandrel bar so that the circularly polarizing plate was located Inside (IN) the aluminum foil. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

Comparative example 1

In comparative example 1, the same evaluation sample as in example 1 was produced except that the bending direction of the circular polarizing plate was formed at an angle of 60 ° with respect to the slow axis direction of the λ/4 plate and the bending start line L of the circular polarizing plate was formed at-45 ° with respect to the absorption axis direction of the polarizing plate. Thereafter, the sample for evaluation was bent under the same conditions as in example 1. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

Comparative example 2

In comparative example 2, the same evaluation sample as in example 1 was produced except that the bending direction of the circular polarizing plate was set to an angle of-30 ° with respect to the slow axis direction of the λ/4 plate and the bending start line L of the circular polarizing plate was set to 45 ° with respect to the absorption axis direction of the polarizing plate. Thereafter, the sample for evaluation was bent under the same conditions as in example 1. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

Comparative example 3

Comparative example 3 was prepared and compared except that the λ/2 plate and the λ/4 plate were bonded via an adhesive layerExample 1 the same sample for evaluation. Thereafter, the sample for evaluation was bent under the same conditions as in example 1. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

Comparative example 4

In comparative example 4, the same evaluation sample as in comparative example 2 was prepared, except that the λ/2 plate and the λ/4 plate were bonded via an adhesive layer. Thereafter, the sample for evaluation was bent under the same conditions as in example 1. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

Comparative example 5

In comparative example 5, the same evaluation sample as in comparative example 1 was prepared. Thereafter, the evaluation sample was bent along the outer peripheral surface of the mandrel bar so that the circularly polarizing plate was located Inside (IN) the aluminum foil. After that, after bending, the same evaluation test as in example 1 was performed. The evaluation results are shown in table 1 below. In addition, the color tone of the reflected light obtained before and after bending is not sandwiched by a^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

[ Table 1]

[ evaluation ]

As is clear from table 1, examples 1 to 4 according to the present invention gave good results with respect to the change in color tone (color and smell) of the reflected light at the curved portion and the presence or absence of the occurrence of wrinkles, as compared with comparative examples 1 to 5.

Description of the symbols

1 circularly polarizing plate, 2 polarizer, RF retardation layer, 3 λ/2 plate (1/2 wavelength plate layer), 4 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 1 st electrode, 230 organic EL layer, 240 nd electrode, 250 sealant layer.

Claims (7)

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

comprising a polarizing plate and a retardation layer disposed on one side of the polarizing plate,

the visibility-correcting monomer transmittance of the polarizing plate is 42% or more,

the phase difference layer includes an 1/2 wavelength plate and a 1/4 wavelength plate,

the 1/2 wave plate and the 1/4 wave plate each include a layer obtained by curing a liquid crystal compound,

the slow axis direction of the 1/4 wave plate is in the range of-20 DEG to 20 DEG when rotated counterclockwise from the absorption axis direction of the polarizer, and the bending direction of the display device is set in the range of 80 DEG to 100 DEG or-10 DEG to 10 DEG with respect to the slow axis direction of the 1/4 wave plate.

2. The circularly polarizing plate according to claim 1,

the 1/2 wave plate and the 1/4 wave plate are bonded together via an adhesive layer.

3. The circularly polarizing plate according to claim 1 or 2,

the display device is an organic electroluminescent display device.

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

the reflected light obtained before and after bending has a hue not separated by a gapA is attaching to^＊b^＊A in chromaticity coordinates^＊Coordinate axes and b^＊The coordinate axis changes sign.

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

6. The bendable display device according to claim 5, comprising:

a touch sensor disposed on a side of the circular polarizing plate opposite to the display panel, and

a window film disposed on an opposite side of the circularly polarizing plate from a side facing the display panel.

7. Bendable display device according to claim 5,

the display device is provided with a touch sensor disposed on the opposite side of the circularly polarizing plate from the side facing the display panel.

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