JP2022069815A - Polarizing plate with retardation layer, and image display device - Google Patents

Abstract

To provide a polarizing plate with a retardation layer that has superior visibility through polarizing sunglasses and also has superior bending properties although having simple composition.SOLUTION: A polarizing plate with a retardation layer is used for a bendable image display device. The polarizing plate with the retardation layer has: a polarizing plate including a polarizer and a protective layer at least on one side of the polarizer; and the retardation layer provided on the opposite side from a view side of the polarizing plate and having a circular polarizing function or elliptic polarizing function, wherein the total thickness is 80 μm or less, the angle that an axis of bending of the image display device and an axis of absorption of the polarizer contain is 30 to 60°, and the protective layer has an elastic modulus of 5,000 MPa or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to a polarizing plate with a retardation layer and an image display device.

In recent years, image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have rapidly become widespread. A polarizing plate and a retardation plate are typically used in an image display device. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1), and recently, there is a strong demand for thinner image display devices. As a result, there is an increasing demand for thinner polarizing plates with a retardation layer. Further, with the expansion of applications of image display devices, demands for image display devices are diversifying. For example, smartphones are required to be foldable and to improve visibility through polarized sunglasses. Therefore, there is a strong demand for a polarizing plate with a retardation layer that can realize such an image display device.

Patent No. 3325560

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to have a retardation layer having a simple structure, excellent visibility through polarized sunglasses, and excellent bendability. The purpose is to provide a polarizing plate.

The polarizing plate with a retardation layer of the present invention is used in a bendable image display device. The polarizing plate with a retardation layer includes a polarizing plate and a polarizing plate containing a protective layer on at least one side of the polarizing element; a circular polarization function or elliptically polarized light provided on the side opposite to the visible side of the polarizing plate. The protective layer has a functional retardation layer; The elastic coefficient of the above is 5000 MPa or less.
In one embodiment, the polarizing plate with a retardation layer has a total thickness of 60 μm or less.
In one embodiment, the thickness of the stator is 10 μm or less.
In one embodiment, the polarizing plate includes a protective layer only on the opposite side of the polarizing element to the retardation layer.
In one embodiment, the elastic modulus of the protective layer is 4000 MPa or less.
In one embodiment, the protective layer has a thickness of 45 μm or less.
In one embodiment, the angle formed by the bending axis and the absorbing axis of the polarizing element is 40 ° to 50 °.
In one embodiment, the retardation layer is an oriented solidified layer of a liquid crystal compound.
In one embodiment, the retardation layer is a single layer, the Re (550) of the retardation layer is 100 nm to 190 nm, and the Re (450) / Re (550) of the retardation layer is 0. It is 8 or more and less than 1, and the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing element is 40 ° to 50 °. In one embodiment, the polarizing plate with a retardation layer further has another retardation layer outside the retardation layer, and the refractive index characteristic of the other retardation layer has a relationship of nz> nx = ny. Is shown.
In one embodiment, the retardation layer has a laminated structure of an oriented solidified layer of a first liquid crystal compound and an oriented solidified layer of a second liquid crystal compound; an oriented solidified layer of the first liquid crystal compound. The Re (550) of the second liquid crystal compound is 200 nm to 300 nm, and the angle formed by the slow axis thereof and the absorption axis of the above-mentioned polarizing element is 10 ° to 20 °; the Re (550) of the oriented solidification layer of the second liquid crystal compound is formed. ) Is 100 nm to 190 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizing element is 70 ° to 80 °.
According to another aspect of the present invention, an image display device is provided. This image display device includes the above-mentioned polarizing plate with a retardation layer.

According to the embodiment of the present invention, in the polarizing plate with a retardation layer, the angle between the bending axis and the absorption axis of the polarizing element when applied to a bendable image display device is optimized, and the elastic modulus of the protective layer is optimized. By optimizing the above, it is possible to realize a polarizing plate with a retardation layer, which has a simple structure, is excellent in visibility through polarized sunglasses, and is excellent in bendability.

It is a schematic perspective view which shows the bent state of the image display device which applied the polarizing plate with a retardation layer by embodiment of this invention. FIG. 3 is a schematic plan view of a polarizing plate with a retardation layer according to one embodiment of the present invention. It is schematic cross-sectional view of the polarizing plate with a retardation layer by one Embodiment of this invention. It is schematic cross-sectional view of the polarizing plate with a retardation layer by another embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols herein are as follows.
(1) Refractive index (nx, ny, nz)
"Nx" is the refractive index in the direction in which the refractive index in the plane is maximized (that is, the direction of the slow phase axis), and "ny" is the direction orthogonal to the slow phase axis in the plane (that is, the direction of the phase advance axis). Is the refractive index of, and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
“Re (λ)” is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in the thickness direction (Rth)
“Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is obtained by the formula: Rth (λ) = (nx-nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.
(5) Angle When referring to an angle herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Thus, for example, "45 °" means ± 45 °; and, for example, "30 ° to 60 °" means + 30 ° to + 60 ° or -30 ° to -60 °.

A. Overall Configuration of Polarizing Plate with Disparity Layer FIG. 1 is a schematic perspective view showing a bent state of an image display device to which a polarizing plate with a retardation layer is applied according to an embodiment of the present invention; FIG. 2 is a schematic perspective view of the present invention. FIG. 3 is a schematic plan view of a polarizing plate with a retardation layer according to one embodiment; FIG. 3 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention; FIG. 4 is a schematic cross-sectional view of the polarizing plate with a retardation layer. It is a schematic cross-sectional view of the polarizing plate with a retardation layer according to another embodiment. The polarizing plate with a retardation layer 100 in the example shown in FIG. 3 typically has a polarizing plate 10 and a retardation layer 20 in this order from the viewing side. In the illustrated example, the polarizing plate 10 includes a polarizing element 11 and protective layers 12 and 13 on both sides of the polarizing element 11. Depending on the purpose, one of the protective layers 12 and 13 may be omitted. In one embodiment, the polarizing plate 10 has a protective layer 12 only on the visible side (opposite side of the retardation layer 20) of the polarizing element 11. The components of the polarizing plate with a retardation layer are typically bonded via any suitable adhesive layer (adhesive layer or adhesive layer: not shown). Practically, an adhesive layer (not shown) is provided on the side opposite to the polarizing plate 10 of the retardation layer 20 (that is, as the outermost layer on the side opposite to the viewing side), and the polarizing plate with the retardation layer is an image. It can be pasted on the display panel. Further, it is preferable that a release film (not shown) is temporarily attached to the surface of the pressure-sensitive adhesive layer until the polarizing plate with a retardation layer is used. By temporarily attaching the release film, the pressure-sensitive adhesive layer can be protected and a roll of the polarizing plate with a retardation layer can be formed.

As shown in FIG. 1, the polarizing plate with a retardation layer is used in a bendable image display device. As shown in FIGS. 1 and 2, in the polarizing plate with a retardation layer, the angle formed by the bending axis F of the image display device and the absorption axis A of the polarizing element 11 is 30 ° to 60 °, preferably 35 ° to 35 °. It is 55 °, more preferably 40 ° to 50 °, still more preferably 42 ° to 48 °, and particularly preferably about 45 °. With such a configuration, a specific layer (typically, a layer that imparts a (elliptical) circular polarization function such as a λ / 4 plate, an in-plane retardation Re) on the visible side of a polarizing plate with a retardation layer. It is possible to realize excellent visibility when visually recognizing through polarized sunglasses without forming an ultra-high retardation layer in which (550) exceeds 1000 nm). Therefore, the polarizing plate with a retardation layer according to the embodiment of the present invention is simple and low cost because the number of layers is small, and as a result, it is thin. Further, with such a configuration, excellent bendability (flexibility) can be realized by a synergistic effect with the effect of optimizing the elastic modulus of the protective layer. More specifically, when the bending axis is parallel to the absorption axis of the substituent, the polarizing plate with a retardation layer (substantially, the polarizing plate) becomes very fragile. On the other hand, when the bending axis is orthogonal to the absorption axis of the polarizing element, it becomes difficult to break, but the visibility when visually recognizing through polarized sunglasses is extremely insufficient. By optimizing the bending axis and the absorption axis of the stator to form the above-mentioned predetermined angle, both excellent bending property (flexibility) and excellent visibility when visually recognizing through polarized sunglasses are achieved. be able to. In the illustrated example, the bending axis F is in the short side direction of the image display device, but the bending axis F may be in the long side direction and has a predetermined angle with respect to the long side direction or the short side direction. It may be a direction (diagonal direction). By defining the absorption axis direction with respect to the bending axis direction, the polarizing plate with a retardation layer is applied to an image display device having a shape other than a rectangle (for example, a circle, an ellipse, a triangle, or an indefinite shape). However, the above effect can be obtained.

The polarizing plate with a retardation layer has a total thickness (total thickness of the polarizing plate, the retardation layer, and the adhesive layer laminating them) of 80 μm or less, preferably 70 μm or less, and more preferably 60 μm or less. It is more preferably 50 μm or less, and particularly preferably 40 μm or less. The total thickness of the polarizing plate with a retardation layer can be, for example, 25 μm or more. According to the embodiment of the present invention, even with such a very small total thickness, excellent visibility can be realized when visually recognizing through polarized sunglasses. In other words, the polarizing plate with a retardation layer can make the total thickness very small even when it is used for applications such as viewing through polarized sunglasses. As a result, the moment of inertia of area at the time of bending becomes small, and the stress applied to each component (layer) becomes small. Therefore, in addition to the excellent visibility when visually recognizing through sunglasses, excellent bendability (flexibility) can be realized.

In the embodiment of the present invention, the elastic modulus of the protective layer 12 and / or 13 is 5000 MPa or less, preferably 4500 MPa or less, more preferably 4000 MPa or less, and further preferably 3500 MPa or less. The lower limit of the elastic modulus of the protective layer can be, for example, 2000 MPa. Preferably, the polarizing plate with a retardation layer (substantially, a polarizing plate) has only the protective layer 12, and the elastic modulus of the protective layer 12 is in the above range. If the elastic modulus of the protective layer is too large, the compressive stress applied to the protective layer becomes large when the strain at the time of bending is the same. As a result, cracks are likely to occur in the protective layer when bending is repeated. By optimizing the elastic modulus of the protective layer to the above range, cracks at the time of bending can be suppressed and excellent bending property (flexibility) can be realized. The elastic modulus can be measured according to JIS Z 2284.

The retardation layer 20 has a circular polarization function or an elliptically polarization function. The retardation layer 20 is typically an alignment solidification layer (liquid crystal alignment solidification layer) of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be significantly increased as compared with the non-liquid crystal material, so that the thickness of the retardation layer for obtaining a desired in-plane retardation can be obtained. Can be made much smaller. Therefore, it is possible to realize a remarkable reduction in thickness of the polarizing plate with a retardation layer. As a result, the above-mentioned excellent bendability (flexibility) can be realized. As used herein, the term "aligned solidified layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and the oriented state is fixed. The "oriented solidified layer" is a concept including an oriented cured layer obtained by curing a liquid crystal monomer as described later. In the retardation layer 20, the rod-shaped liquid crystal compounds are typically oriented in a state of being aligned in the slow axis direction of the retardation layer (homogeneous orientation). The retardation layer 20 may be a single layer as shown in FIG. 3, or may have a laminated structure of two or more layers as shown in FIG.

The polarizing plate with a retardation layer may further include other optical functional layers. The type, characteristics, number, combination, arrangement position, and the like of the optical functional layers that can be provided on the polarizing plate with a retardation layer can be appropriately set according to the purpose. For example, the polarizing plate with a retardation layer may further have a conductive layer or an isotropic substrate with a conductive layer (neither is shown). The conductive layer or the isotropic base material with the conductive layer is typically provided on the outside of the second retardation layer 22 (on the opposite side of the polarizing plate 10). The conductive layer or the isotropic base material with the conductive layer is typically any layer provided as needed, and may be omitted. When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a retardation layer is a so-called inner in which a touch sensor is incorporated between an image display cell (for example, an organic EL cell) and the polarizing plate. It can be applied to a touch panel type input display device. Further, for example, the polarizing plate with a retardation layer may further include another retardation layer. The optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of the other retardation layer can be appropriately set according to the purpose.

Hereinafter, the components of the polarizing plate with a retardation layer will be described in more detail.

B. Polarizing plate B-1. Polarizer As the splitter 11, any suitable polarizing element may be adopted. For example, the resin film forming the polarizing element may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizing element composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine and a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizing element obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is used.

The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Further, it may be dyed after being stretched. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a cleaning treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt and blocking inhibitor on the surface of the PVA-based film, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizing element obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizing element obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The ligand obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying the resin base material. It is produced by forming a PVA-based resin layer on top of the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; obtain. In the present embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin base material. Stretching typically involves immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further comprise, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. In addition, in the present embodiment, preferably, the laminate is subjected to a drying shrinkage treatment in which the laminate is shrunk by 2% or more in the width direction by heating while being conveyed in the longitudinal direction. Typically, the production method of the present embodiment includes subjecting the laminate to an aerial auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, even when PVA is applied on the thermoplastic resin, the crystallinity of PVA can be enhanced and high optical characteristics can be achieved. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of PVA orientation and dissolution when immersed in water in a subsequent dyeing step or stretching step, and high optical characteristics. Will be possible to achieve. Further, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecule and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This makes it possible to improve the optical characteristics of the polarizing element obtained through a treatment step of immersing the laminate in a liquid, such as a dyeing treatment and a stretching treatment in water. Further, the optical characteristics can be improved by shrinking the laminated body in the width direction by the drying shrinkage treatment. The obtained resin base material / polarizing element laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizing element), and the resin base material is peeled off from the resin base material / polarizing element laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. Details of the method for producing such a polarizing element are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

The thickness of the splitter is preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, particularly preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the stator is in such a range, the desired total thickness can be realized and excellent bendability can be realized.

The splitter preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the polarizing element is preferably 41.5% to 46.0%, more preferably 43.0% to 46.0%, still more preferably 44.5% to 46.0%. be. The degree of polarization of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

B-2. Protective Layer The protective layers 12 and 13, respectively, are formed of any suitable film that can be used as a protective layer for the polarizing element as long as the above elastic modulus can be satisfied. Specific examples of the material that is the main component of the film include cellulosic resins such as triacetylcellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, and polysulfones. , Polyester-based, cyclic olefin-based (for example, polynorbornene-based), polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like.

The polarizing plate with a retardation layer is typically arranged on the visual recognition side of the image display device, and the protective layer 12 is arranged on the visual recognition side thereof. Therefore, the protective layer 12 may be subjected to surface treatment such as hard coat treatment, antireflection treatment, sticking prevention treatment, and antiglare treatment, if necessary.

The thicknesses of the protective layers 12 and 13 are preferably 60 μm or less, more preferably 45 μm or less, and further preferably 10 μm to 40 μm, respectively. When the surface treatment is applied, the thickness of the protective layer 12 is the thickness including the thickness of the surface treatment layer.

C. Phase difference layer As described above, the phase difference layer 20 may be a single layer or may have a laminated structure of two or more layers.

When the retardation layer 20 is a single layer, the retardation layer can typically function as a λ / 4 plate. Specifically, the Re (550) of the retardation layer is preferably 100 nm to 180 nm, more preferably 110 nm to 170 nm, and further preferably 110 nm to 160 nm. The thickness of the retardation layer can be adjusted to obtain the desired in-plane retardation of the λ / 4 plate. The thickness of the retardation layer can be, for example, 1.0 μm to 2.5 μm. In the present embodiment, the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing element is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably 44. ° to 46 °. In this embodiment, the polarizing plate with a retardation layer may further have a retardation layer (not shown) exhibiting a refractive index characteristic of nz> nx = ny on the outside of the retardation layer 20. When the retardation layer is a single layer, the retardation layer preferably exhibits a reverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. In this case, Re (450) / Re (550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 to 0.95.

When the retardation layer 20 has a laminated structure, the retardation layer typically has a two-layer structure of an H layer 21 and a Q layer 22 in order from the polarizing plate side as shown in FIG. The H layer can typically function as a λ / 2 plate, and the Q layer can typically function as a λ / 4 plate. Specifically, the Re (550) of the H layer is preferably 200 nm to 300 nm, more preferably 220 nm to 290 nm, still more preferably 230 nm to 280 nm; and the Re (550) of the Q layer is preferably. It is 100 nm to 180 nm, more preferably 110 nm to 170 nm, and even more preferably 110 nm to 150 nm. The thickness of the H layer can be adjusted to obtain the desired in-plane phase difference of the λ / 2 plate. When the H layer is a liquid crystal oriented solidified layer, its thickness can be, for example, 2.0 μm to 4.0 μm. The thickness of the Q layer can be adjusted to obtain the desired in-plane phase difference of the λ / 4 plate. When the Q layer is a liquid crystal oriented solidified layer, its thickness can be, for example, 1.0 μm to 2.5 μm. In the present embodiment, the angle formed by the slow phase axis of the H layer and the absorption axis of the polarizing element is preferably 10 ° to 20 °, more preferably 12 ° to 18 °, and even more preferably 12 °. The angle between the slow axis of the Q layer and the absorption axis of the stator is preferably 70 ° to 80 °, more preferably 72 ° to 78 °, and even more preferably 72 °. It is ~ 76 °. The arrangement order of the H layer and the Q layer may be reversed, and the angle formed by the slow axis of the H layer and the absorption axis of the stator and the slow axis of the Q layer and the absorption axis of the splitter are formed. The angles may be reversed. When the retardation layer has a laminated structure, each layer (for example, H layer and Q layer) may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and the retardation value may be exhibited. May show a positive wavelength dispersion characteristic that decreases according to the wavelength of the measurement light, or may show a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light.

The retardation layer (each layer in the case of having a laminated structure) typically shows a relationship in which the refractive index characteristic is nx> ny = nz. It should be noted that "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny> nz or ny <nz may occur within a range that does not impair the effect of the present invention. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3.

The retardation layer is typically a liquid crystal oriented solidifying layer as described above. Examples of the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) in which the liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystal expression mechanism of the liquid crystal compound may be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the orientation state of the liquid crystal monomer can be fixed by polymerizing or cross-linking (that is, curing) the liquid crystal monomer. After the liquid crystal monomers are oriented, for example, if the liquid crystal monomers are polymerized or crosslinked with each other, the oriented state can be fixed. Here, the polymer is formed by polymerization, and the three-dimensional network structure is formed by crosslinking, but these are non-liquid crystal. Therefore, the formed retardation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change peculiar to a liquid crystal compound, for example. As a result, the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity differs depending on the type. Specifically, the temperature range is preferably 40 ° C. to 120 ° C., more preferably 50 ° C. to 100 ° C., and most preferably 60 ° C. to 90 ° C.

As the liquid crystal monomer, any suitable liquid crystal monomer can be adopted. For example, the polymerizable mesogen compounds described in Special Tables 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US43884553), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such a polymerizable mesogen compound include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

D. Image display device The polarizing plate with a retardation layer according to the above items A to C can be applied to an image display device. Therefore, an image display device including a polarizing plate with a retardation layer is also included in the embodiment of the present invention. The image display device typically includes an image display cell and a polarizing plate with a retardation layer attached to the image display cell via an adhesive layer. Typical examples of the image display device include a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device). The image display device is bendable as described above, and is preferably foldable. In such an image display device, the effect of the polarizing plate with a retardation layer according to the embodiment of the present invention becomes remarkable.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.
(1) Thickness The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). Thicknesses exceeding 10 μm were measured using a digital micrometer (manufactured by Anritsu, product name “KC-351C”).
(2) Elastic modulus The elastic modulus was measured according to JIS Z 2284. Specifically, it was as follows. A strip-shaped sample piece having a width of 10 mm and a length of 100 mm is cut out from the protective layer used in the examples and comparative examples, and the sample piece is cut under the following conditions using a high-speed compatible single-unit autograph (manufactured by Shimadzu Corporation). The elastic modulus was determined from the obtained SS (Stress-Strain) curve by pulling in the longitudinal direction. The measurement conditions were a tensile speed of 50 mm / min, a distance between chucks of 100 mm, and a measurement temperature of room temperature (25 ° C.). The method for obtaining the elastic modulus from the SS curve was as follows. A tangent line is drawn at the initial rise of the SS curve, the strength at the position where the extension line of the tangent line has a 100% elongation rate is read, and the cross-sectional area of the sample piece (thickness x sample width (10 mm)) for which the value is measured is measured. The value divided by is taken as the elastic modulus.
(3) Bending test The polarizing plate with a retardation layer obtained in Examples and Comparative Examples was cut into a size of 100 mm × 55 mm and used as a measurement sample. Here, it was cut out so that the bending axis was in the direction of the short side of the measurement data. This measurement sample was subjected to a continuous bending test using a bending tester (manufactured by Yuasa System Equipment Co., Ltd., product name "CL09 Type D01"). Bending was performed at room temperature so that the protective layer on the visual side was on the inside. The radius of curvature of the bend was 3 mm. The presence or absence of cracks when bent 500,000 times was visually observed and evaluated according to the following criteria.
◯: No cracks were observed ×: Cracks were observed (4) Visibility when visually recognized through polarized sunglasses The polarizing plate on the visual recognition side of a commercially available liquid crystal display device was removed, and the surface from which the polarizing plate was removed was removed. After washing, the polarizing plate with a retardation layer obtained in Examples and Comparative Examples was attached to the washed surface. Bonding is performed so that the angles between the absorption axis of the polarizing element of the polarizing plate with a retardation layer and the short side of the liquid crystal display device are 0 °, 30 °, 40 °, 45 °, 50 °, 60 ° and 90 °. rice field. A predetermined character was displayed on the liquid crystal display device thus obtained, and the display screen was observed by wearing polarized sunglasses. Here, the absorption axis direction of the polarized sunglasses was observed according to each of the short side direction and the long side direction of the image display device, and evaluated according to the following criteria.
○: The contents of the display screen could be recognized in an understandable manner regardless of whether the absorption axis direction of the polarized sunglasses was aligned with either the short side direction or the long side direction. ×: Absorption of the polarized sunglasses in at least one of the short side direction and the long side direction. The contents of the display screen could not be recognized when the axial directions were aligned.

[Example 1-1]
1. 1. Fabrication of Polarizing Plate As a thermoplastic resin base material, an amorphous isophthal copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75 ° C. is used, and one side of the resin base material is treated with corona. Was given.
100 parts by weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer") are mixed at a ratio of 9: 1. A PVA aqueous solution (coating solution) was prepared by dissolving 13 parts by weight of potassium iodide in water.
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 μm, and a laminate was prepared.
The obtained laminate was uniaxially stretched 2.4 times in the vertical direction (longitudinal direction) in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water), the polarizing element finally obtained is charged. It was immersed for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) became a predetermined value (staining treatment).
Then, it was immersed in a cross-linked bath having a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70 ° C., the total in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
Then, the laminate was immersed in a washing bath having a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while drying in an oven kept at about 90 ° C., the sauce was brought into contact with a heating roll made of SUS whose surface temperature was kept at about 75 ° C. (dry shrinkage treatment).
In this way, a polarizing element having a thickness of about 5 μm was formed on the resin substrate, and a polarizing plate having a resin substrate / polarizing element configuration was obtained.

Further, an HC-TAC film as a protective base material (protective layer) is placed on the surface of the obtained substituent (the surface opposite to the resin base material) via an ultraviolet curable adhesive (thickness 1.0 μm). I pasted them together. The HC-TAC film is a film in which a hard coat (HC) layer (thickness 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and the TAC film is attached so as to be on the splitter side. I matched it. In this way, a polarizing plate having a protective layer / polarizing element configuration was obtained. The elastic modulus of the protective layer was 3872 MPa.

ポリエチレンテレフタレート（ＰＥＴ）フィルム（厚み３８μｍ）表面を、ラビング布を用いてラビングし、配向処理を施した。配向処理の方向は、偏光板に貼り合わせる際に偏光子の吸収軸の方向に対して視認側から見て１５°方向となるようにした。この配向処理表面に、上記液晶塗工液をバーコーターにより塗工し、９０℃で２分間加熱乾燥することによって液晶化合物を配向させた。このようにして形成された液晶層に、メタルハライドランプを用いて１ｍＪ/ｃｍ^２の光を照射し、当該液晶層を硬化させることによって、ＰＥＴフィルム上に液晶配向固化層Ａを形成した。液晶配向固化層Ａの厚みは２μｍ、面内位相差Ｒｅ（５５０）は２７０ｎｍであった。さらに、液晶配向固化層Ａは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。液晶配向固化層ＡをＷ層として用いた。
塗工厚みを変更したこと、および、配向処理方向を偏光子の吸収軸の方向に対して視認側から見て７５°方向となるようにしたこと以外は上記と同様にして、ＰＥＴフィルム上に液晶配向固化層Ｂを形成した。液晶配向固化層Ｂの厚みは１μｍ、面内位相差Ｒｅ（５５０）は１４０ｎｍであった。さらに、液晶配向固化層Ｂは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。液晶配向固化層ＢをＱ層として用いた。 2. 2. Preparation of Phase Difference Layer 10 g of polymerizable liquid crystal (manufactured by BASF: trade name "Pariocolor LC242", represented by the following formula) showing a nematic liquid crystal phase and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: A liquid crystal composition (coating liquid) was prepared by dissolving 3 g of the trade name "Irgacure 907") in 40 g of toluene.

The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth and subjected to an orientation treatment. The direction of the alignment treatment was set to be 15 ° when viewed from the visual recognition side with respect to the direction of the absorption axis of the polarizing element when the polarizing plate was attached. The liquid crystal coating liquid was applied to the alignment-treated surface with a bar coater, and the liquid crystal compound was oriented by heating and drying at 90 ° C. for 2 minutes. The liquid crystal layer thus formed was irradiated with light of 1 mJ / cm ² using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal oriented solidified layer A on the PET film. The thickness of the liquid crystal oriented solidified layer A was 2 μm, and the in-plane retardation Re (550) was 270 nm. Further, the liquid crystal oriented solidified layer A had a refractive index distribution of nx> ny = nz. The liquid crystal alignment solidified layer A was used as the W layer.
On the PET film in the same manner as above, except that the coating thickness was changed and the orientation processing direction was set to be 75 ° when viewed from the visual side with respect to the direction of the absorber's absorption axis. The liquid crystal oriented solidified layer B was formed. The thickness of the liquid crystal oriented solidified layer B was 1 μm, and the in-plane retardation Re (550) was 140 nm. Further, the liquid crystal oriented solidified layer B had a refractive index distribution of nx> ny = nz. The liquid crystal alignment solidification layer B was used as the Q layer.

3. 3. Fabrication of polarizing plate with retardation layer 1. On the surface of the polarizing plate of the polarizing plate obtained in 2. above. The liquid crystal oriented solidified layer A (W layer) and the liquid crystal oriented solidified layer B (Q layer) obtained in 1) were transferred in this order. At this time, the angle between the absorption axis of the stator and the slow axis of the oriented solidification layer A is 15 °, and the angle between the absorption axis of the splitter and the slow axis of the oriented solidification layer B is 75 °. Transferred (bonded). Each transfer (bonding) was performed via an ultraviolet curable adhesive (thickness 1.0 μm). In this way, a polarizing plate with a retardation layer having a structure of a protective layer / adhesive / polarizing element / adhesive / W layer / adhesive / Q layer was obtained. The thickness of the obtained polarizing plate with a retardation layer was 43 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 30 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the evaluations of (3) and (4) above. The results are shown in Table 1.

[Example 1-2] to [Example 1-5] and [Comparative Example 1-1] to [Comparative Example 1-2]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Example 2-1]
A polarizing plate having a protective layer / polarizing element configuration was produced in the same manner as in Example 1-1. On the other hand, a retardation layer (a single retardation layer that exhibits inverse dispersion wavelength dependence and can function as a λ / 4 plate) and another retardation layer (positive C plate) were prepared as follows.
After adding 55 parts of the compound represented by the formula (II), 25 parts of the compound represented by the formula (III), and 20 parts of the compound represented by the formula (IV) to 400 parts of cyclopentanone (CPN), 60 parts are added. Heat to ℃, stir to dissolve, and after confirming the dissolution, return to room temperature, Irgacure 907 (manufactured by BASF Japan Co., Ltd.) 3 parts, Megafuck F-554 (manufactured by DIC Co., Ltd.) 0.2 parts, 0.1 part of p-methoxyphenol (MEHQ) was added, and the mixture was further stirred to obtain a solution. The solution was clear and uniform. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, a polyimide solution for an alignment film was applied to a glass substrate having a thickness of 0.7 mm by a spin coating method, dried at 100 ° C. for 10 minutes, and then fired at 200 ° C. for 60 minutes to obtain a coating film. .. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing device. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by a spin coating method, and dried at 100 ° C. for 2 minutes. The obtained coating film was cooled to room temperature and then irradiated with ultraviolet rays at an intensity of 30 mW / cm ² for 30 seconds using a high-pressure mercury lamp to obtain a liquid crystal oriented solidified layer C. The thickness of the liquid crystal oriented solidified layer was 3.0 μm, and the in-plane retardation Re (550) was 130 nm. The Re (450) / Re (550) of the liquid crystal oriented solidified layer was 0.851, showing the reverse dispersion wavelength characteristic. This liquid crystal oriented solidified layer was used as a retardation layer.

20 parts by weight of the side chain liquid crystal polymer represented by the following chemical formula (I) (numbers 65 and 35 in the formula represent mol% of the monomer unit and are conveniently represented by a block polymer: weight average molecular weight 5000). Dissolve 80 parts by weight of a polymerizable liquid crystal (BASF: trade name Palocolor LC242) showing a nematic liquid crystal phase and 5 parts by weight of a photopolymerization initiator (Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The liquid crystal coating liquid was prepared. Then, the liquid crystal is formed by applying the coating liquid to a base film (norbornene-based resin film: manufactured by Nippon Zeon Corporation, trade name "Zeonex") with a bar coater, and then heating and drying at 80 ° C. for 4 minutes. Oriented. By irradiating this liquid crystal layer with ultraviolet rays and curing the liquid crystal layer, a liquid crystal oriented solidified layer (positive C plate, thickness 3 μm) to be another retardation layer was formed on the substrate. Re (590) of this layer was 0 nm, Rth (590) was -100 nm, and showed a refractive index characteristic of nz> nx = ny.

The liquid crystal oriented solidified layer C was transferred to the surface of the polarizing element of the polarizing plate obtained above via the pressure-sensitive adhesive layer (thickness 5 μm), and the positive C plate was further transferred to the surface of the liquid crystal oriented solidified layer C. In this way, a polarizing plate with a retardation layer having a structure of a protective layer / adhesive / a polarizing element / an adhesive layer / a retardation layer / an adhesive / a positive C plate was obtained. The thickness of the obtained polarizing plate with a retardation layer was 49 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 30 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Example 2-2] to [Example 2-5] and [Comparative Example 2-1] to [Comparative Example 2-2]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 2-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Example 3-1]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1-1 except that an acrylic resin film (thickness 20 μm) was used instead of the HC-TAC film as the protective layer. The elastic modulus of the protective film was 2881 MPa. The thickness of the obtained polarizing plate with a retardation layer was 31 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 30 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Example 3-2] to [Example 3-5] and [Comparative Example 3-1] to [Comparative Example 3-2]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 3-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Example 4-1]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1-1 except that an acrylic resin film (thickness 40 μm) was used instead of the HC-TAC film as the protective layer. The elastic modulus of the protective film was 3066 MPa. The thickness of the obtained polarizing plate with a retardation layer was 51 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 30 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Example 4-2] to [Example 4-5] and [Comparative Example 4-1] to [Comparative Example 4-2]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 4-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 5-1]
A retardation layer (a single retardation layer that exhibits inverse dispersion wavelength dependence and can function as a λ / 4 plate) was prepared as follows.
Polymerization was carried out using a batch polymerization apparatus consisting of two vertical stirring reactors equipped with a stirring blade and a reflux condenser. 30.31 parts by mass (0.047 mol) of bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane (BPFM) synthesized by the method described in JP-A-2015-25111, isosorbide (ISB). , Rocket Foil Co., Ltd.) 39.94 parts by mass (0.273 mol), Spiroglycol (SPG, manufactured by Mitsubishi Gas Chemicals Co., Ltd.) 30.20 parts by mass (0.099 mol), Diphenyl carbonate (DPC, Mitsubishi Chemical Co., Ltd.) (Manufactured by Co., Ltd.) was charged with 69.67 parts by mass (0.325 mol) and 7.88 × 10 ^-4 parts by mass (4.47 × ^10-6 mol) of calcium acetate monohydrate as a catalyst. After substituting nitrogen under reduced pressure in the reactor, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature was brought to 220 ° C. 40 minutes after the start of the temperature rise, and the depressurization was started at the same time as controlling to maintain this temperature, and the temperature was 13.3 kPa 90 minutes after reaching 220 ° C. The phenol vapor produced by the polymerization reaction was guided to a reflux condenser at 110 ° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the non-condensed phenol vapor was guided to a condenser at 45 ° C. for recovery. Nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 20 kPa in 40 minutes. Then, while further reducing the pressure, the polymerization was allowed to proceed until the predetermined stirring power was obtained. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, the produced polyester carbonate was extruded into water, and the strands were cut to obtain pellets. The ratio of the structural units derived from each monomer of this resin was BPFM / ISB / SPG / DPC = 21.5 / 39.4 / 30.0 / 9.1% by mass. The obtained pellets are vacuum dried at 100 ° C. for 6 hours or more, and then a single shaft extruder (manufactured by Isuzu Kakohki Co., Ltd., screw diameter 25 mm, cylinder set temperature: 250 ° C.), T-die (width 300 mm, set temperature). : 220 ° C.), a chill roll (set temperature: 120 to 130 ° C.), and a film forming apparatus equipped with a winder were used to prepare a long unstretched film having a length of 3 m, a width of 200 mm, and a thickness of 100 μm. This long unstretched film was stretched at a stretching temperature of Tg (139 ° C.) to obtain a retardation film having a thickness of 37 μm. The obtained retardation film exhibited a refractive index characteristic of nx> ny = nz, Re (550) was 145 nm, and Re (450) / Re (550) was 0.85.

The retardation film obtained above was used as the retardation layer, the retardation film was bonded to the polarizing element via an adhesive layer (thickness 5 μm) instead of the adhesive layer, and the retardation layer. Protective layer / adhesive / polarizing element / pressure-sensitive adhesive layer / retardation layer (phase difference film) in the same manner as in Example 1-1 except that the positive C plate used in Example 2-1 was transferred to the surface. A polarizing plate with a retardation layer having the structure of / adhesive / positive C plate was obtained. The thickness of the obtained polarizing plate with a retardation layer was 89 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 0 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 5-2] to [Comparative Example 5-7]
A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 5-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 6-1]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1-1 except that an HC-COP film was used instead of the HC-TAC film as the protective layer. The elastic modulus of the protective film was 1988 MPa. The thickness of the obtained polarizing plate with a retardation layer was 84 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 30 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 6-2] to [Comparative Example 6-7]
A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 6-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 7-1]
A polarizing plate was produced as follows.
A polyvinyl alcohol-based resin film having an average degree of polymerization of 2,400, a saponification degree of 99.9 mol%, and a thickness of 30 μm was prepared. The polyvinyl alcohol film was immersed in a swelling bath (water bath) at 20 ° C. for 30 seconds between rolls having different peripheral speed ratios and stretched 2.4 times in the transport direction while swelling (swelling step). Dyeing by immersing in a dyeing bath at 30 ° C. (an aqueous solution having an iodine concentration of 0.03% by weight and a potassium iodide concentration of 0.3% by weight) so that the single transmittance after final stretching becomes a desired value. While using the original polyvinyl alcohol film (polyvinyl alcohol film not stretched at all in the transport direction) as a reference, the film was stretched 3.7 times in the transport direction (dyeing step). The immersion time at this time was about 60 seconds. Next, the original polyvinyl alcohol film was placed while immersing the dyed polyvinyl alcohol film in a cross-linked bath at 40 ° C. (an aqueous solution having a boric acid concentration of 3.0% by weight and a potassium iodide concentration of 3.0% by weight). It was stretched up to 4.2 times in the transport direction as a reference (crosslinking step). Further, the obtained polyvinyl alcohol film is immersed in a stretching bath at 64 ° C. (an aqueous solution having a boric acid concentration of 4.0% by weight and a potassium iodide concentration of 5.0% by weight) for 50 seconds to obtain the original polyvinyl alcohol. After stretching up to 6.0 times in the transport direction with reference to the alcohol film (stretching step), it was immersed in a washing bath at 20 ° C. (an aqueous solution having a potassium iodide concentration of 3.0% by weight) for 5 seconds (washing). Process). The washed polyvinyl alcohol film was dried at 30 ° C. for 2 minutes to prepare a stator (thickness 12 μm). The HC-TAC film was bonded to one surface of the obtained polarizing element in the same manner as in Example 1-1, and the TAC film having a thickness of 25 μm was bonded to the other surface. In this way, a polarizing plate having a structure of a visible side protective layer (HC-TAC film) / a stator / an inner protective layer (TAC film) was produced. The elastic modulus of the visual-viewing side protective layer was 3872 MPa as in Example 1-1.

Protective layer / adhesive / polarizing element / adhesive / protective layer / adhesive layer / retardation layer (phase difference film) in the same manner as in Comparative Example 5-1 except that the polarizing plate obtained above was used. A polarizing plate with a retardation layer having the structure of / adhesive / positive C plate was obtained. The thickness of the obtained polarizing plate with a retardation layer was 116 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 0 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 7-2] to [Comparative Example 7-7]
A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 7-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 8-1]
Brightness improving film (water absorption 0.75%, amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 30 μm) with a water absorption of 0.75% and Tg 75 ° C.) prepared in Comparative Example 7-1 on one side. To prepare a polarizing plate having a brightness-enhancing film / polarizing element. The following procedure is the same as in Example 1-1, and a polarizing plate with a retardation layer having a structure of a protective layer (brightness improving film) / adhesive / polarizing element / adhesive / W layer / adhesive / Q layer is used. Obtained. The elastic modulus of the protective layer was 5005 MPa. The thickness of the obtained polarizing plate with a retardation layer was 48 μm. This polarizing plate with a retardation layer was punched into a rectangle of a predetermined size corresponding to a bendable image display device having a bending axis in the short side direction. Here, the absorber was punched so that the absorption axis was 0 ° with respect to the bending axis. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[Comparative Example 8-2] to [Comparative Example 8-7]
A polarizing plate with a retardation layer was obtained in the same manner as in Comparative Example 8-1 except that the angle between the absorption axis and the bending axis of the polarizing element was punched so as to be the angle shown in Table 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1-1. The results are shown in Table 1.

[evaluation]
As is clear from Table 1, according to the embodiment of the present invention, it can be seen that a polarizing plate with a retardation layer having excellent bendability and visibility when visually recognized through polarized sunglasses can be obtained.

The polarizing plate with a retardation layer of the present invention is a bendable image display device, and can be suitably used for an image display device that can be visually recognized through polarized sunglasses.

10 Polarizing plate 11 Polarizer 12 Protective layer 20 Phase difference layer 21 H layer 22 Q layer 100 Polarizing plate with retardation layer 102 Polarizing plate with retardation layer 102

Claims (12)

A polarizing plate with a retardation layer used in a bendable image display device.
A polarizing plate containing a polarizing element and a protective layer on at least one side of the polarizing element; and a retardation layer having a circular polarization function or an elliptically polarizing function provided on the side opposite to the visible side of the polarizing plate; Have and
The total thickness is 80 μm or less,
The angle formed by the bending axis of the image display device and the absorption axis of the polarizing element is 30 ° to 60 °.
The elastic modulus of the protective layer is 5000 MPa or less.
Polarizing plate with retardation layer. The polarizing plate with a retardation layer according to claim 1, wherein the total thickness is 60 μm or less. The polarizing plate with a retardation layer according to claim 1 or 2, wherein the polarizing element has a thickness of 10 μm or less. The polarizing plate with a retardation layer according to any one of claims 1 to 3, wherein the polarizing plate includes a protective layer only on the side opposite to the retardation layer of the polarizing element. The polarizing plate with a retardation layer according to claim 4, wherein the elastic modulus of the protective layer is 4000 MPa or less. The polarizing plate with a retardation layer according to claim 5, wherein the protective layer has a thickness of 45 μm or less. The polarizing plate with a retardation layer according to any one of claims 1 to 6, wherein the angle formed by the bending axis and the absorption axis of the polarizing element is 40 ° to 50 °. The polarizing plate with a retardation layer according to any one of claims 1 to 7, wherein the retardation layer is an orientation-solidified layer of a liquid crystal compound. The retardation layer is a single layer, the Re (550) of the retardation layer is 100 nm to 190 nm, and the Re (450) / Re (550) of the retardation layer is 0.8 or more and less than 1. The polarizing plate with a retardation layer according to claim 8, wherein the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing element is 40 ° to 50 °. The ninth aspect of the present invention indicates that the polarizing plate with a retardation layer further has another retardation layer outside the retardation layer, and the refractive index characteristics of the other retardation layer show a relationship of nz> nz = ny. The above-mentioned polarizing plate with a retardation layer. The retardation layer has a laminated structure of an oriented solidified layer of a first liquid crystal compound and an oriented solidified layer of a second liquid crystal compound.
The Re (550) of the oriented solidified layer of the first liquid crystal compound is 200 nm to 300 nm, and the angle formed by the slow axis thereof and the absorption axis of the polarizing element is 10 ° to 20 °.
The Re (550) of the oriented solidified layer of the second liquid crystal compound is 100 nm to 190 nm, and the angle between the slow axis thereof and the absorption axis of the substituent is 70 ° to 80 °.
The polarizing plate with a retardation layer according to claim 8. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 11.

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