Polarizing plate with phase difference layer and image display device using the same

Abstract

To provide a polarizing plate with a phase difference layer that has high light resistance and durability. [Solution] The polarizing plate with a phase difference layer according to an embodiment of the present invention comprises a polarizing plate containing a polarizer and a phase difference layer, and is rectangular in shape. The direction of the long side of the polarizing plate with the phase difference layer and the direction of the slow phase axis of the phase difference layer are parallel.

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate with a phase difference layer and an image display device using the same. [Background technology]

[0002] In recent years, image display devices, such as liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays and inorganic EL displays), have rapidly become widespread. Typically, polarizers and phase difference plates are used in image display devices. In practical terms, polarizers with an integrated phase difference layer are widely used (e.g., Patent Document 1). As the demand for thinner image display devices increases, so does the demand for thinner polarizers with phase difference layers. To achieve this, progress is being made in thinning phase difference films. Furthermore, to evaluate the durability of phase difference films, the fabricated films are subjected to various evaluation tests. With thin phase difference films, a decrease in durability (e.g., light resistance) can be a problem. Therefore, there is a need for polarizers with a phase difference layer that possess high light resistance and durability. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 3325560 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a thin polarizing plate with a phase difference layer that has high light resistance and durability. [Means for solving the problem]

[0005] The polarizing plate with a phase difference layer of the present invention is a rectangular polarizing plate with a phase difference layer having a polarizing plate containing a polarizer and a phase difference layer, wherein the direction of the long side of the polarizing plate with a phase difference layer is parallel to the direction of the slow phase axis of the phase difference layer. In one embodiment, the boric acid content of the polarizer is 25% by weight or less. In one embodiment, the angle between the absorption axis of the polarizer and the direction of the long side of the polarizing plate with the phase difference layer is 35° to 55°. In one embodiment, the ratio of the length of the long side to the length of the short side of the polarizing plate with the phase difference layer is 1.1 to 2.2. In one embodiment, the phase difference layer is an orientation solidified layer of a liquid crystal compound having a circular polarization function or an elliptic polarization function. In one embodiment, the dimensional shrinkage rate in the short-side direction of the polarizing plate with an upper phase difference layer is 0.076% or more when irradiated with xenon light for 100 hours under conditions of 50°C and 50%RH. In one embodiment, the total thickness of the polarizing plate with the phase difference layer is 60 μm or less. In another aspect of the present invention, an image display device is provided. This image display device comprises the polarizing plate with the phase difference layer described above. In one embodiment, the image display device is an organic electroluminescent display device or an inorganic electroluminescent display device. [Effects of the Invention]

[0006] According to embodiments of the present invention, a thin polarizing plate with a phase difference layer having high light resistance and durability can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0009] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated using 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 the phase difference in the thickness direction measured with light of wavelength λnm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured with light of wavelength 550nm at 23°C. Rth(λ) can be calculated using the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is calculated using the formula Nz = Rth / Re. (5)Angle In this specification, when an angle is referred to, it encompasses both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°.

[0010] A. Overall configuration of a polarizing plate with a phase difference layer Figure 1 is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to one embodiment of the present invention. The polarizing plate with a phase difference layer 100 in the illustrated example has a polarizing plate 10, a phase difference layer 20, and an adhesive layer 30 in this order from the viewing side. The polarizing plate 10 typically includes a polarizer 11 and a protective layer 12 disposed on the viewing side of the polarizer 11. Depending on the purpose, another protective layer (not shown) may be provided on the side of the polarizer 11 opposite to the viewing side (the side of the polarizer 11 where the protective layer 12 is not laminated). The phase difference layer 20 is typically an orientation solidification layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function (hereinafter sometimes simply referred to as a liquid crystal orientation solidification layer). The polarizing plate with a phase difference layer has the adhesive layer 30 as the outermost layer and is made attachable to an image display device (substantially an image display cell). In practical terms, it is preferable that a release liner is temporarily attached to the surface of the adhesive layer 30 until the polarizing plate is put into use. By temporarily attaching a release liner, the adhesive layer can be properly protected.

[0011] The polarizing plate with a phase difference layer according to the embodiment of the present invention is rectangular and has a short side and a long side. The ratio of the length of the long side to the length of the short side (length of long side / length of short side) of the polarizing plate with a phase difference layer is, for example, greater than 1, preferably 1.1 to 3.0, more preferably 1.3 to 2.7, and even more preferably 1.5 to 2.5. By having the ratio of the length of the long side to the length of the short side of the polarizing plate with a phase difference layer within the above range, deterioration such as a decrease in phase difference due to sunlight can be suppressed, and a polarizing plate with a phase difference layer that has high light resistance and durability can be provided.

[0012] In this embodiment of the present invention, the long side direction of the polarizing plate 100 with a phase difference layer and the slow phase axis direction of the phase difference layer 20 are parallel. As described above, dimensional shrinkage of the polarizing plate with a phase difference layer may occur under the conditions of a xenon light irradiation test. This dimensional shrinkage tends to be greater in the short side direction, and the phase difference layer may also shrink more in the short side direction as a result of the shrinkage. Therefore, the phase difference may decrease, and reliability may decrease. Because the long side direction of the polarizing plate 100 with a phase difference layer and the slow phase axis direction of the phase difference layer 20 are parallel, as the polarizing plate with a phase difference layer shrinks, the phase difference layer shrinks in a direction that increases uniaxiality, and the phase difference may increase. Therefore, the decrease in phase difference due to dimensional shrinkage and the improvement in phase difference due to the increase in uniaxiality can be balanced. As a result, deterioration such as the decrease in phase difference due to the xenon light irradiation test can be suppressed, and a polarizing plate with a phase difference layer that has high light resistance and durability can be provided. In this specification, "parallel" includes not only cases where the planes are perfectly parallel, but also cases where the angle between the long side direction of the phase difference layer polarizer and the slow phase axis direction of the phase difference layer is approximately parallel, for example, -5° to 5°.

[0013] The angle between the absorption axis of the polarizer 11 and the direction of the long side of the polarizing plate 100 with a phase difference layer is preferably 35° to 55°, more preferably 40° to 50°, even more preferably 42° to 48°, and particularly preferably about 45°. By having the angle between the absorption axis of the polarizer 11 and the direction of the long side of the polarizing plate 100 with a phase difference layer within the above range, deterioration such as a decrease in phase difference due to sunlight can be further suppressed, and a polarizing plate with a phase difference layer that has high light resistance and durability can be provided.

[0014] When a polarizing plate with a phase difference layer is irradiated with xenon light for 100 hours under conditions of 55°C and 50%RH, the dimensional shrinkage rate in the short-side direction is preferably 0.076% or more, more preferably 0.090% or more, and even more preferably 0.12% or more. The dimensional shrinkage in the short-side direction is, for example, 0.16% or less. By having the dimensional shrinkage in the short-side direction within the above range, a balance can be achieved between the decrease in phase difference due to dimensional shrinkage and the improvement in phase difference due to the increase in uniaxiality. As a result, deterioration such as the decrease in phase difference due to xenon light irradiation testing can be suppressed, and a polarizing plate with a phase difference layer that has high light resistance and durability can be provided. In this specification, the dimensional shrinkage rate in the short-side direction refers to the shrinkage rate of the polarizing plate with a phase difference layer before and after the xenon light irradiation test. This is calculated by measuring the shrinkage distance (mm) in the short-side direction of the polarizing plate with a phase difference layer using an XY length measuring instrument after irradiating it with xenon light for 100 hours under conditions of a black panel temperature of 55°C and humidity of 55%RH, and then using the following formula based on the said shrinkage distance. Short-side contraction rate = (short-side contraction distance) / (short-side length before xenon light irradiation) × 100

[0015] The phase difference layer 20 is preferably a liquid crystal alignment solidification layer. The phase difference layer 20 may be a single layer or may have a laminated structure of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer.

[0016] The polarizing plate with a phase difference layer may further include another phase difference layer and / or a conductive layer or an isotropic substrate with a conductive layer (neither of which are shown). The other phase difference layer is typically provided between the phase difference layer 20 and the adhesive layer 30 (i.e., outside the phase difference layer 20). The other phase difference layer typically exhibits a refractive index characteristic of nz > nx = ny. The conductive layer or isotropic substrate with a conductive layer is typically provided between the phase difference layer 20 and the adhesive layer 30. The other phase difference layer and the conductive layer or isotropic substrate with a conductive layer are typically provided in this order from the phase difference layer 20 side. The other phase difference layer and the conductive layer or isotropic substrate with a conductive layer are optional layers provided as needed, and either or both may be omitted. When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a phase difference layer can be applied to a so-called inner touch panel type input display device in which a touch sensor is incorporated between an image display cell (e.g., an organic EL cell) and the polarizing plate.

[0017] The optical properties (e.g., refractive index, in-plane phase difference, Nz coefficient, photoelastic coefficient), thickness, and placement of the other phase difference layer can be appropriately set according to the purpose.

[0018] The total thickness of the polarizing plate with a phase difference layer is preferably 100 μm or less, more preferably 60 μm or less, even more preferably 55 μm or less, even more preferably 50 μm or less, and particularly preferably 40 μm or less. The total thickness may be, for example, 28 μm or more. According to embodiments of the present invention, such an extremely thin polarizing plate with a phase difference layer can be realized. Furthermore, such a polarizing plate with a phase difference layer may have extremely excellent flexibility and bending durability. Therefore, such a polarizing plate with a phase difference layer can be particularly suitably applied to curved image display devices and / or bendable or foldable image display devices. The total thickness of the polarizing plate with a phase difference layer refers to the sum of the thicknesses of the polarizing plate, the phase difference layer (if another phase difference layer exists, the phase difference layer and the other phase difference layer), and the adhesive layer or tack layer for laminating them (i.e., the total thickness of the polarizing plate with a phase difference layer does not include the thickness of the conductive layer or isotropic substrate with a conductive layer, as well as the tack layer 30 and any release liner that may be temporarily attached to its surface).

[0019] The components of a polarizing plate with a phase difference layer will be explained in more detail below.

[0020] B. Polarizing plate B-1.Polarizer The polarizer is typically composed of a polyvinyl alcohol (PVA) resin film containing a dichroic substance. The thickness of the polarizer is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, and even more preferably 2 μm to 5 μm. A polarizer thickness within this range can greatly contribute to the thinning of the polarizing plate with a phase difference layer. Furthermore, the effects of the present invention are particularly pronounced in thin polarizing plates with a phase difference layer using such a polarizer.

[0021] The boric acid content of the polarizer is preferably 25% by weight or less, more preferably 11% to 25% by weight, and even more preferably 12% to 25% by weight. When the boric acid content of the polarizer is within this range, degradation such as a decrease in phase difference due to xenon light irradiation tests can be suppressed, and a polarizing plate with a phase difference layer that has high light resistance and durability can be provided. Furthermore, it is possible to maintain good ease of curl adjustment during bonding, and to improve the appearance durability during heating while effectively suppressing curl during heating. The boric acid content can be calculated, for example, as the amount of boric acid contained in the polarizer per unit weight using the following formula from the neutralization method.

number

[0022] The iodine content of the polarizer is preferably 2% by weight or more, and more preferably 2% to 10% by weight. When the iodine content of the polarizer is within this range, the synergistic effect with the boric acid content allows for good maintenance of ease of curl adjustment during lamination, good suppression of curl during heating, and improved appearance durability during heating. In this specification, "iodine content" refers to the total amount of iodine contained in the polarizer (PVA-based resin film). More specifically, in the polarizer, iodine is in the form of iodide ions (I - ), iodine molecule (I2), polyiodide ion (I3) - , I5 - Iodine exists in forms such as (PVA·I3), and the iodine content as used herein refers to the amount of iodine encompassing all of these forms. The iodine content can be calculated, for example, by the calibration curve method of X-ray fluorescence analysis. Polyiodide ions exist in a state in which they form a PVA-iodine complex in a polarizer. The formation of such a complex can cause absorption dichroism in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ions (PVA·I3) - ) has an absorption peak around 470 nm, and is a complex of PVA and pentaiodide ions (PVA·I5 -) has an absorption peak around 600 nm. As a result, polyiodide ions can absorb light over a wide range of visible light depending on their form. On the other hand, iodide ions (I - ) has an absorption peak around 230 nm and is not substantially involved in the absorption of visible light. Therefore, the polyiodide ions present in the complex state with PVA may be primarily responsible for the absorption performance of the polarizer.

[0023] The polarizer preferably exhibits absorption dichroism at a wavelength of 380 nm to 780 nm. The single-element transmittance Ts of the polarizer is preferably 40% to 48%, more preferably 41% to 46%. The degree of polarization P of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher. The above single-element transmittance is typically the Y value obtained by measuring with an ultraviolet-visible spectrophotometer and correcting for luminous efficiency. The above degree of polarization is typically determined by the following formula based on the parallel transmittance Tp and orthogonal transmittance Tc, which are measured with an ultraviolet-visible spectrophotometer and corrected for luminous efficiency. Degree of polarization (%)={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100

[0024] Polarizers can typically be made using laminates of two or more layers. A specific example of a polarizer obtained using a laminate is a polarizer made using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer made using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be made, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer may be laminated onto the peeled surface according to the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0025] A typical method for manufacturing a polarizer involves forming a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate to form a laminate, and then subjecting the laminate to the following processes in this order: air-assisted stretching, dyeing, water-assisted stretching, and drying shrinkage by heating while transporting in the longitudinal direction to shrink by 2% or more in the width direction. This makes it possible to provide a polarizer that is very thin, has excellent optical properties, and suppresses variations in optical properties. In other words, by introducing assisted stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, thereby achieving high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This makes it possible to improve the optical properties of polarizers obtained through processing steps that involve immersing the laminate in a liquid, such as dyeing and underwater stretching. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment.

[0026] B-2.Protective layer The protective layer 12 is formed from any suitable film that can be used as a protective layer for the polarizer. Specific examples of materials that make up the main component of the film include cellulosic resins such as triacetylcellulose (TAC), and transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic, and acetate. Thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone can also be used. In addition, glassy polymers such as siloxane polymers can also be used. Polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As materials for this film, for example, a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains, and a thermoplastic resin having substituted or unsubstituted phenyl groups and nitrile groups in its side chains can be used. Examples include a resin composition having an alternating copolymer of isobutene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the above resin composition.

[0027] As described later, the polarizing plate with a phase difference layer is typically placed on the viewing side of the image display device, and the protective layer 12 is typically placed on the viewing side. Therefore, the protective layer 12 may be subjected to surface treatments such as hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating as needed. Furthermore / or, the protective layer 12 may be subjected to treatments that improve visibility when viewed through polarized sunglasses (typically, by providing (elliptic) circular polarization function or providing ultra-high phase difference) as needed. By applying such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate with a phase difference layer can be suitably applied to image display devices that may be used outdoors.

[0028] The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. When surface treatment is performed, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

[0029] C. Retardation layer As described above, the retardation layer 20 typically has a circular polarization function or an elliptical polarization function. The retardation layer typically shows a refractive index characteristic relationship of nx > ny = nz. The retardation layer is typically provided to impart antireflection characteristics to a polarizing plate, and when the retardation layer is a single layer, it can function as a λ / 4 plate. In this case, the in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 130 nm to 160 nm. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny > nz or ny < nz may occur. The retardation layer is preferably an alignment solidification layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function.

[0030] When the retardation layer 20 is composed of a single layer, its thickness is preferably 0.5 μm to 7 μm, more preferably 1 μm to 5 μm. By using a liquid crystal compound, an in-plane retardation equivalent to that of a resin film can be achieved with a thickness much thinner than that of the resin film.

[0031] The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3. By satisfying such a relationship, when the polarizing plate with a retardation layer is used in an image display device, a very excellent reflected hue can be achieved.

[0032] The phase difference layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measured light, positive wavelength dispersion characteristics in which the phase difference value decreases with the wavelength of the measured light, or flat wavelength dispersion characteristics in which the phase difference value hardly changes with the wavelength of the measured light. In one embodiment, the phase difference layer exhibits inverse dispersion wavelength characteristics. In this case, the Re(450) / Re(550) of the phase difference layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, extremely excellent anti-reflective properties can be achieved.

[0033] The angle θ between the slow axis of the phase difference layer 20 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. When the angle θ is within this range, by making the phase difference layer a λ / 4 plate as described above, a polarizer with a phase difference layer having excellent circular polarization characteristics (and consequently, excellent anti-reflective properties) can be obtained.

[0034] In another embodiment, the phase difference layer 20 may have a laminated structure of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer. In this case, either the first liquid crystal alignment solidification layer or the second liquid crystal alignment solidification layer may function as a λ / 4 plate and the other as a λ / 2 plate. Therefore, the thicknesses of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be adjusted to obtain a desired in-plane phase difference between the λ / 4 plate and the λ / 2 plate. For example, when the first liquid crystal alignment solidification layer functions as a λ / 2 plate and the second liquid crystal alignment solidification layer functions as a λ / 4 plate, the thickness of the first liquid crystal alignment solidification layer is, for example, 2.0 μm to 3.0 μm, and the thickness of the second liquid crystal alignment solidification layer is, for example, 1.0 μm to 2.0 μm. In this case, the in-plane phase difference Re(550) of the first liquid crystal alignment solidification layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 250 nm to 280 nm. The in-plane phase difference Re(550) of the second liquid crystal alignment solidification layer is as described above with respect to a single layer.

[0035] The angle between the slow axis of the first liquid crystal alignment solidification layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably about 15°. The angle between the slow axis of the second liquid crystal alignment solidification layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably about 75°. With such a configuration, it is possible to obtain characteristics close to ideal inverse wavelength dispersion characteristics, and as a result, extremely excellent anti-reflective properties can be achieved.

[0036] As described above, the phase difference layer 20 is preferably an orientation-solidified layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny in the resulting phase difference layer can be made significantly larger compared to non-liquid crystal materials, so the thickness of the phase difference layer required to obtain the desired in-plane phase difference can be significantly reduced. As a result, further thinning of the polarizing plate with the phase difference layer can be achieved. In this specification, "liquid crystal orientation-solidified layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and its orientation state is fixed. Note that "orientation-solidified layer" is a concept that includes orientation-hardened layers obtained by hardening liquid crystal monomers as described later.

[0037] The phase difference layer, which is an orientation solidification layer of liquid crystal compounds, can be formed using a composition containing a polymerizable liquid crystal compound. In this specification, a polymerizable liquid crystal compound contained in a composition means a compound that has polymerizable groups and is liquid crystalline. A polymerizable group means a group that participates in polymerization reactions, and is preferably a photopolymerizable group. Here, a photopolymerizable group means a group that can participate in polymerization reactions by active radicals or acids generated from a photopolymerization initiator.

[0038] The liquid crystalline properties may be thermotropic or lyotropic. Furthermore, the liquid crystalline phase may be nematic or smectic. From the viewpoint of ease of manufacturing, thermotropic nematic liquid crystalline properties are preferred.

[0039] In one embodiment, the retardation layer that is a single layer is formed using a composition containing a liquid crystal compound represented by the following formula (1). L 1 -SP 1 -A 1 -D 3 -G 1 -D 1 -Ar-D 2 -G 2 -D 4 -A 2 -SP 2 -L 2 (1)

[0040] L 1 and L 2 each independently represent a monovalent organic group, and at least one of L 1 and L 2 represents a polymerizable group. Any suitable group is included as the monovalent organic group. As the polymerizable group represented by at least one of L 1 and L 2 a radical polymerizable group (a group capable of radical polymerization) can be mentioned. As the radical polymerizable group, any suitable radical polymerizable group can be used. Preferably, it is an acryloyl group or a methacryloyl group. From the viewpoint of high polymerization speed and productivity improvement, the acryloyl group is preferable. The methacryloyl group can also be used in the same manner as the polymerizable group of the high birefringence liquid crystal.

[0041] SP 1 and SP 2 each independently represent a single bond, a linear or branched alkylene group, or a divalent linking group in which one or more of -CH2- constituting a linear or branched alkylene group having 1 to 14 carbon atoms are substituted with -O-. As the linear or branched alkylene group having 1 to 14 carbon atoms, preferably, a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group can be mentioned.

[0042] A 1 and A 2 each independently represent an alicyclic hydrocarbon group or an aromatic ring substituent. A 1 ​2 Preferably, it is an aromatic ring substituent having 6 or more carbon atoms or a cycloalkylene ring having 6 or more carbon atoms.

[0043] D 1 , D 2 , D 3 and D 4 Each of these independently represents a single bond or a divalent linking group. Specifically, D 1 , D 2 , D 3 and D 4 These are single bonds, -O-CO-, -C(=S)O-, and -CR bonds. 1 R 2 -, -CR 1 R 2 -CR 3 R 4 -, -O-CR 1 R 2 -, -CR 1 R 2 -O-CR 3 R 4 -,-CO-O-CR 1 R 2 -, -O-CO-CR 1 R 2 -, -CR 1 R 2 -O-CO-CR 3 R 4 -, -CR 1 R 2 -CO-O-CR 3 R 4 -, -NR 1 -CR 2 R 3 -, or -CO-NR 1 - represents. However, D 1 , D 2 , D 3 and D 4 At least one of them represents -O-CO-. Among them, D 3 It is preferable that -O-CO-, D 3 and D 4 It is more preferable that it is -O-CO-. 1 and D 2 Preferably, it is a single bond. 1 , R 2 , R3 and R 4 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms.

[0044] G 1 and G 2 each independently represents a single bond or an alicyclic hydrocarbon group. Specifically, G 1 and G 2 may each independently represent an unsubstituted or substituted divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms. Further, one or more of -CH2- constituting the alicyclic hydrocarbon group may be substituted with -O-, -S-, or -NH-. G 1 and G 2 preferably represents a single bond.

[0045] Ar represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar represents an aromatic ring selected from the group consisting of groups represented by the following formulas (Ar-1) to (Ar-6). In the following formulas (Ar-1) to (Ar-6), *1 represents the bonding position with D 1 and *2 represents the bonding position with D 2 and.

Chemical formula

[0046] In formula (Ar-1), Q 1 represents N or CH, and Q 2 represents -S-, -O-, or -N(R 5 )-. R 5 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0047] In formulas (Ar-1) to (Ar-6), Z 1 , Z 2 and Z[[ID=5k4]] 3 each independently represents a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, -NR 6 R 7 , or -SR8 Represents R 6 ~R 8 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Z 1 and Z 2 These elements may bond to each other to form a ring. The ring may be alicyclic, heterocyclic, or aromatic, and is preferably an aromatic ring. The formed ring may be substituted with substituents.

[0048] In equations (Ar-2) and (Ar-3), A 3 and A 4 These are -O- and -N(R) respectively, independently. 9 R represents a group selected from the group consisting of -, -S-, and -CO-. 9 R represents a hydrogen atom or substituent. 9 The substituent shown is Y in formula (Ar-1) above. 1 Examples of substituents that may be present include the same ones as those that may be present.

[0049] In formula (Ar-2), X represents a hydrogen atom or an unsubstituted or substituted nonmetal atom from Group 14 to 16. Examples of Group 14 to 16 nonmetal atoms represented by X include oxygen, sulfur, unsubstituted or substituted nitrogen, and unsubstituted or substituted carbon atoms. The substituent is Y in formula (Ar-1) above. 1 Examples of substituents that may be present include the same ones as those that may be present.

[0050] In formula (Ar-3), D 5 and D 6 These are, independently, single bonds, -O-CO-, -C(=S)O-, and -CR bonds. 1 R 2 -, -CR 1 R 2 -CR 3 R 4 -, -O-CR 1 R 2 -, -CR 1 R 2 -O-CR 3 R 4 -,-CO-O-CR 1R 2 -, -O-CO-CR 1 R 2 -, -CR 1 R 2 -O-CO-CR 3 R 4 -, -CR 1 R 2 -CO-O-CR 3 R 4 -, -NR 1 -CR 2 R 3 -, or -CO-NR 1 - represents R 1 , R 2 , R 3 and R 4 This is as stated above.

[0051] In formula (Ar-3), SP 3 and SP 4 Each of these independently represents a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more of the -CH2- groups constituting a linear or branched alkylene group having 1 to 12 carbon atoms are substituted with -O-, -S-, -NH-, -N(Q)-, or -CO-, where Q represents a polymerizable group.

[0052] In formula (Ar-3), L 3 and L 4 Each of these independently represents a monovalent organic group, L 3 and L 4 Furthermore, L in formula (1) above 1 and L 2 At least one of them represents a polymerizable group.

[0053] In formulas (Ar-4) to (Ar-6), Ax represents an organic group having 2 to 30 carbon atoms having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocycles. In formulas (Ar-4) to (Ar-6), Ax preferably has an aromatic heterocycle, and more preferably has a benzothiazole ring. In formulas (Ar-4) to (Ar-6), Ay represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may be unsubstituted or substituted, or an organic group having 2 to 30 carbon atoms having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocycles. In formulas (Ar-4) to (Ar-6), Ay preferably represents a hydrogen atom.

[0054] In equations (Ar-4) to (Ar-6), Q 3 Q represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may be unsubstituted or substituted. In formulas (Ar-4) to (Ar-6), Q 3 This preferably represents a hydrogen atom.

[0055] Among such Ar groups, preferred examples include those represented by the above formula (Ar-4) or (Ar-6).

[0056] Specific examples of liquid crystal compounds represented by formula (1) are disclosed in International Publication No. 2018 / 123551. The description in said publication is incorporated herein by reference. These compounds may be used individually or in combination of two or more.

[0057] The composition containing the liquid crystal compound preferably contains a polymerization initiator. Any suitable polymerization agent can be used as the polymerization initiator. Preferably, it is a photopolymerization initiator that can initiate the polymerization reaction by ultraviolet irradiation. Examples of photopolymerization initiators include α-carbonyl compounds (as described in U.S. Patent Nos. 2,367,661 and 2,367,670), acyloin ethers (as described in U.S. Patent No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (as described in U.S. Patent No. 2,722,512), polynuclear quinone compounds (as described in U.S. Patent Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketones (as described in U.S. Patent No. 3,549,367), oxadiazole compounds (as described in U.S. Patent No. 4,212,970), and acylphosphine oxide compounds (as described in Japanese Patent Publication No. 63-40799, Japanese Patent Publication No. 5-29234, Japanese Patent Application Publication No. 10-95788 and Japanese Patent Application Publication No. 10-29997). The description in the said publication is incorporated herein by reference. A single polymerization initiator may be used, or two or more may be used in combination.

[0058] Compositions containing liquid crystal compounds preferably contain a solvent from the viewpoint of ease of forming the phase difference layer. Any suitable solvent can be used, and organic solvents are preferably used.

[0059] A composition containing a liquid crystal compound further comprises any other suitable components. Examples include antioxidants such as phenolic antioxidants, other liquid crystal compounds, leveling agents, surfactants, tilt angle control agents, orientation aids, plasticizers, and crosslinking agents.

[0060] A liquid crystal alignment solidification layer can be formed by applying an orientation treatment to the surface of a predetermined substrate, coating the surface with a composition (coating liquid) containing a liquid crystal compound to orient the liquid crystal compound in a direction corresponding to the orientation treatment, and fixing the orientation state. In one embodiment, the substrate is any suitable resin film, and the liquid crystal alignment solidification layer formed on the substrate can be transferred to the surface of a polarizing plate.

[0061] Any suitable orientation treatment can be employed as described above. Specifically, these include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of mechanical orientation treatment include rubbing and stretching. Specific examples of physical orientation treatment include magnetic field orientation treatment and electric field orientation treatment. Specific examples of chemical orientation treatment include oblique deposition and photo-oriented orientation treatment. The processing conditions for each orientation treatment can be any suitable conditions depending on the purpose.

[0062] The orientation of liquid crystal compounds is achieved by treating them at a temperature that exhibits the liquid crystal phase, depending on the type of liquid crystal compound. This temperature treatment causes the liquid crystal compound to enter a liquid crystal state, and it then orients according to the orientation treatment direction on the substrate surface.

[0063] In one embodiment, the orientation state is fixed by cooling the liquid crystal compound oriented as described above. If the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the orientation state is fixed by subjecting the liquid crystal compound oriented as described above to a polymerization treatment or a crosslinking treatment.

[0064] Details of the method for forming the oriented solidified layer are described in Japanese Patent Publication No. 2006-163343. The description in said publication is incorporated herein by reference.

[0065] D. Another phase difference layer Another phase difference layer may be a so-called positive C plate, as described above, whose refractive index characteristics exhibit the relationship nz>nx=ny. By using a positive C plate as another phase difference layer, oblique reflections can be effectively prevented, enabling a wider viewing angle for the anti-reflective function. In this case, the phase difference Rth(550) in the thickness direction of the other phase difference layer is preferably -50nm to -300nm, more preferably -70nm to -250nm, even more preferably -90nm to -200nm, and particularly preferably -100nm to -180nm. Here, "nx=ny" includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the other phase difference layer may be less than 10nm.

[0066] Another phase difference layer having refractive index characteristics nz>nx=ny can be formed from any suitable material. The other phase difference layer preferably consists of a film containing a liquid crystal material fixed to a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the phase difference layer are described in paragraphs

[0020] to

[0028] of Japanese Patent Application Publication No. 2002-333642. In this case, the thickness of the other phase difference layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0067] E. Adhesive layer Any suitable adhesive can be used as the adhesive constituting the adhesive layer 30. Examples of suitable adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these adhesives, those that exhibit excellent optical transparency, appropriate wettability, cohesiveness, and adhesive properties, and excellent weather resistance and heat resistance are preferably used. Acrylic-based adhesives are preferably used as they exhibit such characteristics.

[0068] F. Conductive layer or isotropic substrate with conductive layer The conductive layer can be formed by depositing a metal oxide film on any suitable substrate using any appropriate film deposition method (e.g., vacuum deposition, sputtering, CVD, ion plating, spraying, etc.). Examples of metal oxides include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among these, indium-tin composite oxide (ITO) is preferred.

[0069] When the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, and more preferably 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

[0070] The conductive layer may be transferred from the substrate to the phase difference layer (or another phase difference layer, if present) and used as a constituent layer of the polarizing plate with a phase difference layer by itself, or it may be laminated to the phase difference layer (or another phase difference layer, if present) as a laminate with the substrate (substrate with conductive layer). Preferably, the substrate is optically isotropic, and therefore the conductive layer can be used as an isotropic substrate with a conductive layer in a polarizing plate with a phase difference layer.

[0071] Any suitable isotropic substrate can be used as the optically isotropic substrate (isotropic substrate). Examples of materials that constitute the isotropic substrate include materials whose main backbone is a resin that does not have a conjugated system, such as norbornene resin or olefin resin, and materials that have cyclic structures such as lactone rings or glutarimide rings in the main chain of an acrylic resin. When such materials are used, the occurrence of phase difference due to the orientation of molecular chains can be suppressed to a small extent when an isotropic substrate is formed. The thickness of the isotropic substrate is preferably 50 μm or less, and more preferably 35 μm or less. The lower limit of the thickness of the isotropic substrate is, for example, 20 μm.

[0072] The conductive layer and / or the conductive layer of the isotropic substrate with the conductive layer may be patterned as needed. Patterning can create conductive and insulating portions. As a result, electrodes can be formed. These electrodes can function as touch sensor electrodes that detect contact with a touch panel. Any suitable patterning method can be used. Specific examples of patterning methods include wet etching and screen printing.

[0073] G. Method for manufacturing polarizing plates with phase difference layer A polarizing plate with a phase difference layer according to an embodiment of the present invention can be manufactured by any suitable method. In one embodiment, a polarizing plate with a phase difference layer can be manufactured by laminating a polarizing plate cut into a rectangle of a designed size and a phase difference layer via any suitable adhesive such that the direction of the long side of the rectangle and the slow axis direction of the phase difference layer are parallel. When laminating the polarizing plate and the phase difference layer, they may be laminated so that the absorption axis of the polarizer and the slow axis of the phase difference layer are at a predetermined angle.

[0074] In one embodiment, a polarizing plate with a phase difference layer can be manufactured by laminating a large (e.g., elongated) polarizing plate and a phase difference layer via any suitable adhesive such that the absorption axis of the polarizer and the slow axis of the phase difference layer are at a predetermined angle, and then cutting the resulting polarizing plate with a phase difference layer into a rectangle of a designed size such that the direction of the long side of the polarizing plate with a phase difference layer is parallel to the slow axis of the phase difference layer.

[0075] H. Image display device The polarizing plates with phase difference layers described in sections A to F above can be applied to image display devices. Accordingly, embodiments of the present invention encompass image display devices using such polarizing plates with phase difference layers. Typical examples of image display devices include liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays, inorganic EL displays). An image display device according to an embodiment of the present invention is equipped with a polarizing plate with phase difference layers described in sections A to F above on its viewing side. The polarizing plate with phase difference layers is laminated such that the phase difference layer faces the image display cell (e.g., liquid crystal cell, organic EL cell, inorganic EL cell) side (the polarizer faces the viewing side). In one embodiment, the image display device has a curved shape (substantially a curved display screen) and / or is bendable or foldable. [Examples]

[0076] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight.

[0077] (1) Thickness Thicknesses of 10 μm or less were measured using an interferometer (Otsuka Electronics Co., Ltd., product name "MCPD-3000"). Thicknesses exceeding 10 μm were measured using a digital micrometer (Anritsu Corporation, product name "KC-351C").

[0078] (2) Phase difference decrease The adhesive layers of the polarizing plates with phase difference layers obtained in the examples and comparative examples were laminated onto a 0.5 mm thick glass plate (80 mm x 150 mm), and the phase difference value (initial phase difference value) was measured using a phase difference measuring device (manufactured by Oji Keisokuki Co., Ltd., product name: KOBRA). Next, using a xenon weather resistance tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name: Atlas Weatherometer Ci4400, inner filter: borosilicate type S, outer filter: soda lime), a xenon weather resistance test was conducted at a wavelength of 420 nm and a voltage of 0.8 W / m² under BP (black panel) temperature of 55°C and humidity of 55% RH. 2 The polarizer was irradiated with xenon for 100 hours under the specified conditions. Next, the phase difference value of the polarizer with a phase difference layer was measured in the same manner, and the difference from the initial phase difference value was calculated as the phase difference reduction.

[0079] (3) Dimensional shrinkage The adhesive layers of the polarizing plates with phase difference layers obtained in the examples and comparative examples were laminated onto a 0.5 mm thick glass plate (80 mm x 150 mm). Then, using a xenon weather resistance tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name: Atlas Weatherometer Ci4400, inner filter: borosilicate type S, outer filter: soda lime), a xenon weather resistance test was conducted at a wavelength of 420 nm and a voltage of 0.8 W / m² under BP (black panel) temperature of 55°C and humidity of 55% RH. 2 The polarizing plate with a phase difference layer was irradiated with xenon for 100 hours under the specified conditions. Next, the dimensional shrinkage on the short side of the polarizing plate with a phase difference layer was measured using an XY length measuring instrument (Mitutoyo Corporation, product name: Image Measuring Instrument QVA1517-PRO AEIM(SP)). The portion with the largest amount of shrinkage was defined as the dimensional shrinkage of the polarizing plate with a phase difference layer. Furthermore, the shrinkage rate was calculated from the measured dimensional shrinkage using the following formula. Short-side contraction rate = (short-side contraction distance) / (short-side length before xenon light irradiation) × 100

[0080] [Example 1] [Manufacturing Example 1: Fabrication of Polarizing Plates] 1. Fabrication of a polarizer As the thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length, with a water absorption rate of 0.75% and a Tg of approximately 75°C was used. One side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer Z410") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a 13 μm thick PVA-based resin layer, thereby creating a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the polarizers were immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizers obtained would be 43.0% or higher (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 3.7% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the laminate was dried in an oven maintained at 90°C while being brought into contact with a SUS (stainless steel) heated roll with a surface temperature maintained at 75°C for approximately 2 seconds (drying shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the drying shrinkage treatment was 5.2%. In this way, a polarizer with a thickness of 5 μm (containing 20% ​​by weight of boric acid) was formed on a resin substrate.

[0081] 2. Fabrication of polarizing plates An HC-COP film was bonded as a protective layer to the surface of the polarizer obtained above (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. Specifically, the curing adhesive was applied to a total thickness of 1.0 μm and bonded using a roll press. Then, UV light was irradiated from the protective layer side to cure the adhesive. The HC-COP film is a cycloolefin (COP) film (manufactured by Zeon Corporation, product name "ZF12", thickness 25 μm) with a hard coat (HC) layer (thickness 2 μm) formed on it, and it was bonded so that the COP film was on the polarizer side. Next, the resin substrate was peeled off to obtain a polarizer plate having the structure of protective layer (HC layer / COP film) / adhesive layer / polarizer.

[0082] [Manufacturing Example 2: Fabrication of Phase Difference Layer] 55 parts by weight of the compound represented by formula (I), 25 parts by weight of the compound represented by formula (II), and 20 parts by weight of the compound represented by formula (III) were added to 400 parts by weight of cyclopentanone (CPN), and then heated to 60°C and stirred to dissolve. After that, the solution of the compounds was allowed to return to room temperature, and 3 parts by weight of Irgacure 907 (BASF Japan), 0.2 parts by weight of Megafac F-554 (DIC), and 0.1 parts by weight of p-methoxyphenol (MEHQ) were added to the solution of the compounds, and the mixture was stirred further. The solution after stirring was clear and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. Furthermore, a polyimide solution for the alignment film was applied to a 0.7 mm thick glass substrate using a spin coating method, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The obtained coating film was then rubbed using a commercially available rubbing device to form an alignment film. Next, the polymerizable composition obtained above was applied to the substrate (essentially the orientation film) by spin coating and dried at 100°C for 2 minutes. After the resulting coated film was cooled to room temperature, it was heated using a high-pressure mercury lamp at 30 mW / cm². 2 The liquid crystal compound was irradiated with ultraviolet light at a certain intensity for 30 seconds to obtain a phase difference layer, which is an oriented solidified layer. The in-plane phase difference Re(550) of the phase difference layer was 130 nm. Furthermore, the Re(450) / Re(550) of the phase difference layer was 0.851, indicating inverse dispersion wavelength characteristics. The phase difference layer can function as a λ / 4 plate. [ka] [ka]

[0083] [Manufacturing Example 3: Fabrication of another phase difference layer] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (the numbers 65 and 35 in the formula indicate the mole percent of monomer units and are conveniently represented as a block polymer: weight-average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a vertically aligned PET substrate using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. By irradiating this liquid crystal layer with ultraviolet light and curing the liquid crystal layer, a second phase difference layer (thickness 3 μm) exhibiting refractive index characteristics of nz>nx=ny was formed on the substrate. [ka]

[0084] The phase difference layer obtained in Manufacturing Example 2 and another phase difference layer obtained in Manufacturing Example 3 were transferred in that order to the polarizer surface of the polarizer plate obtained in Manufacturing Example 1. At this time, the transfer (bonding) was carried out so that the angle between the absorption axis of the polarizer and the slow phase axis of the phase difference layer obtained in Manufacturing Example 2 was 45°. Each transfer (bonding) was carried out via the ultraviolet-curing adhesive (thickness 1.0 μm) used in Manufacturing Example 1. In this way, a laminate having the configuration of protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / phase difference layer / adhesive layer / another phase difference layer was fabricated. Next, the laminate was cut into a rectangle with a long side of 130 mm and a short side of 66 mm so that the long side direction of the polarizer plate with the phase difference layer and the slow phase axis of the phase difference layer were parallel.

[0085] Next, an adhesive layer (5 μm thick) was provided on the surface of another phase difference layer, and a polarizing plate with a phase difference layer was obtained having the following configuration: protective layer (HC layer / COP film) / adhesive layer / polarizer / protective layer (triacetylcellulose film) / adhesive layer / phase difference layer / adhesive layer / another phase difference layer / adhesive layer. The total thickness of the obtained polarizing plate with a phase difference layer was 100 μm. The obtained polarizing plate with a phase difference layer was subjected to the evaluations described in (2) and (3) above. The results are shown in Table 1.

[0086] [Examples 2-4] In the polarizer fabrication process, a polarizer with a phase difference layer was fabricated in the same manner as in Example 1, except that the concentration of the boric acid aqueous solution used in the cross-linking process was changed to obtain polarizers with the boric acid content shown in Table 1. The obtained polarizer with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0087] (Comparative Example 1) A laminate having the configuration of a protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / phase difference layer (phase difference layer / adhesive layer / another phase difference layer) was fabricated in the same manner as in Example 1. Next, the laminate was cut into a rectangle with a long side of 130 mm and a short side of 66 mm so that the long side direction of the polarizing plate with the phase difference layer and the slow phase axis of the phase difference layer were perpendicular to each other.

[0088] Next, an adhesive layer (15 μm thick) was provided on the surface of another phase difference layer to obtain a polarizing plate with a phase difference layer having the following configuration: protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / phase difference layer / adhesive layer / another phase difference layer / adhesive layer. The total thickness of the obtained polarizing plate with a phase difference layer was 39.5 μm. The obtained polarizing plate with a phase difference layer was subjected to the evaluations described in (2) and (3) above. The results are shown in Table 1.

[0089] (Comparative Examples 2-6) In the polarizer fabrication process, a polarizer with a phase difference layer was fabricated in the same manner as in Comparative Example 1, except that the concentration of the boric acid aqueous solution used in the cross-linking process was changed to obtain polarizers with the boric acid content shown in Table 1. The obtained polarizer with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0090] [Table 1]

[0091] [evaluation] As is clear from Table 1, the polarizing plate with a phase difference layer according to the embodiment of the present invention showed suppressed reduction in phase difference even when subjected to weather resistance testing, and possessed high light resistance and durability. [Industrial applicability]

[0092] The polarizing plate with a phase difference layer of the present invention is suitably used as a circular polarizing plate for liquid crystal display devices, organic EL display devices, and inorganic EL display devices. [Explanation of symbols]

[0093] 10 Polarizing plates 11 Polarizer 12 Protective layer 20 Retardation layer 30 Adhesive layer 100 Polarizing plate with retardation layer

Claims

[Claim 1] A rectangular polarizing plate with a phase difference layer, comprising a polarizing plate containing a polarizer and a phase difference layer, A polarizing plate with a phase difference layer, wherein the direction of the long side of the polarizing plate with the phase difference layer is parallel to the direction of the slow phase axis of the phase difference layer.

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