Polarizing plate with a slowing layer and the image display device using this polarizing plate.

Abstract

The invention relates to a polarizing plate with a retarding layer, which comprises a fixed, aligned layer of liquid crystal compound and whose detachment of the fixed, aligned layer of liquid crystal compound is prevented. The polarizing plate with a retarding layer (100) in the scheme of the invention comprises: a polarizing plate (10) comprising a polarizing glass (11) and a protective layer (12) arranged on at least one side of the polarizing glass; a first adhesive layer (31); and a retarding layer (20) laminated onto the polarizing plate through the first adhesive layer. The retarding layer is a fixed, aligned layer of liquid crystal compound, and comprises a permeable layer (20a), which is made up by the permeation of the first adhesive layer near its interface with the first adhesive layer.

Description

Polarizing plate with retardation layer and image display device using the same

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

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have rapidly become widespread. Image display devices typically use polarizing plates and retardation plates. In practice, retardation layer-attached polarizing plates, which integrate a polarizing plate and a retardation plate, are widely used (e.g., Patent Document 1). Recently, along with the increasing demand for thinner image display devices, there has been an increasing demand for thinner retardation layer-attached polarizing plates. To meet this demand, a retardation layer has been proposed, which is a layer formed by aligning a liquid crystal compound in a predetermined direction and fixing the alignment state. However, a problem with layers formed from such liquid crystal compounds is that they are prone to peeling.

[0003] Patent No. 5745686

[0004] The present invention has been made to solve the above-mentioned conventional problems, and a main object of the present invention is to provide a polarizing plate with a retardation layer, which has an alignment and solidification layer of a liquid crystal compound and in which peeling of the alignment and solidification layer of the liquid crystal compound is suppressed.

[0005] The polarizing plate with a retardation layer of the present invention comprises a polarizing plate including a polarizer and a protective layer on at least one side of the polarizer; and a retardation layer laminated on the polarizing plate via a first adhesive layer. The retardation layer is an alignment-solidified layer of a liquid crystal compound, and includes a permeation layer formed by penetration of the adhesive of the first adhesive layer near the interface with the first adhesive layer. In one embodiment, the polarizing plate includes the polarizer and a protective layer arranged on the side of the polarizer opposite the retardation layer. In another embodiment, the polarizing plate includes the polarizer and protective layers arranged on both sides of the polarizer. In this case, the protective layer arranged on the retardation layer side of the polarizer may include a permeation layer formed by penetration of the adhesive of the first adhesive layer near the interface with the first adhesive layer. In one embodiment, the retardation layer is a single layer of a layer of a fixed alignment of a liquid crystal compound, and the retardation layer has an Re(550) of 100 nm to 190 nm, and the angle between the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50°. In another embodiment, the retardation layer has a layer of a fixed alignment of a first liquid crystal compound and a layer of a fixed alignment of a second liquid crystal compound laminated on the layer of the fixed alignment of the first liquid crystal compound via a second adhesive layer; and the layer of the fixed alignment of the first liquid crystal compound and the layer of the fixed alignment of the second liquid crystal compound each include a penetration layer formed by penetration of the adhesive of the second adhesive layer near the interface with the second adhesive layer. The Re(550) of the alignment-fixed layer of the first liquid crystal compound is 200 nm to 300 nm, and the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°; the Re(550) of the alignment-fixed layer of the second liquid crystal compound is 100 nm to 190 nm, and the angle between its slow axis and the absorption axis of the polarizer is 70° to 80°. In one embodiment, the adhesive of the first and second adhesive layers each contains acryloylmorpholine. In one embodiment, the retardation layer-attached polarizing plate further has another retardation layer on the outer side of the retardation layer, and the refractive index characteristics of the another retardation layer exhibit the relationship nz > nx = ny. According to another aspect of the present invention, there is provided an image display device. The image display device includes the retardation layer-attached polarizing plate described above.

[0006] According to the present invention, in a polarizing plate with a retardation layer having a layer of solidified alignment of a liquid crystal compound, by providing a penetration layer formed by penetration of the adhesive of the adhesive layer near the interface between the layer of solidified alignment of the liquid crystal compound and an adjacent adhesive layer, it is possible to realize a polarizing plate with a retardation layer in which peeling of the layer of solidified alignment of the liquid crystal compound is suppressed.

[0007] 1 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to one embodiment of the present invention; 2 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to another embodiment of the present invention; 3 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to yet another embodiment of the present invention; 4 is a transmission electron microscope (TEM) image showing the state of the interface between the adhesive layer and the retardation layer in the retardation layer-attached polarizing plate of Example 1; and 5 is a TEM image showing the state of the interface between the adhesive layer and the retardation layer in the retardation layer-attached polarizing plate of Comparative Example 1.

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] (Definition 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 in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the in-plane direction perpendicular to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-Plane Retardation (Re) "Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Thickness Direction Retardation (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of 550 nm wavelength at 23°C. Rth(λ) is calculated 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 calculated by Nz = Rth / Re. (5) Angle: When referring to angles in this specification, the angle includes both clockwise and counterclockwise angles relative to the reference direction. Therefore, for example, "45°" means ±45°. (6) Solidified Alignment Layer: A "solidified alignment layer" refers to a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer and the alignment state is fixed. The concept of a "solidified alignment layer" encompasses a hardened alignment layer obtained by hardening a liquid crystal monomer, as described below. (7) (Meth)acrylic: "(Meth)acrylic" refers to acrylic and / or methacrylic.

[0010] A. Overall Configuration of a Polarizing Plate with a Retardation Layer FIG. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The illustrated polarizing plate with a retardation layer 100 includes a polarizing plate 10 and a retardation layer 20 laminated to the polarizing plate 10 via a first adhesive layer 31. A polarizing plate typically includes a polarizer and a protective layer disposed on at least one side of the polarizer. The illustrated polarizing plate 10 includes a polarizer 11 and a first protective layer 12 disposed on one side of the polarizer 11 (the side opposite the retardation layer). In an embodiment of the present invention, the retardation layer 20 is a layer in which the liquid crystal compound is aligned and solidified, and includes a penetration layer 20a formed by penetration of the adhesive of the first adhesive layer 31 near the interface with the first adhesive layer 31. By providing such a penetration layer, peeling of the retardation layer (the layer in which the liquid crystal compound is aligned and solidified) can be significantly suppressed. Furthermore, peeling of the retardation layer (the layer with solidified alignment of the liquid crystal compound) can be particularly significantly suppressed by providing the first adhesive layer 31 directly on the polarizer 11 as in this embodiment. According to the configuration of this embodiment, for example, the peel strength between the first adhesive layer and the layer with solidified alignment of the liquid crystal compound is extremely large, so that the first adhesive layer and the layer with solidified alignment of the liquid crystal compound do not peel off in a normal peeling operation, and other interlayer peeling (for example, peeling between the polarizer and the first adhesive layer) can also be prevented.

[0011] FIG. 2 is a schematic cross-sectional view of a retardation layer-attached polarizing plate according to another embodiment of the present invention. In the illustrated retardation layer-attached polarizing plate 101, the polarizing plate 10 includes a polarizer 11, a first protective layer 12 disposed on one side of the polarizer 11 (the side opposite the retardation layer), and a second protective layer 13 disposed on the other side of the polarizer 11 (the side facing the retardation layer). In this embodiment, the second protective layer 13 may include a permeation layer 13a formed by the penetration of the adhesive of the first adhesive layer 31 near the interface with the first adhesive layer 31. Providing the permeation layer 13a can, for example, prevent peeling between the first adhesive layer and the alignment / solidification layer of the liquid crystal compound and increase the peel strength between the first adhesive layer and the second protective layer. The permeation layer 13a is optional and may or may not be formed on the second protective layer 13.

[0012] As described above, the retardation layer 20 is an alignment-solidified layer of a liquid crystal compound. The retardation layer 20 may be a single layer of an alignment-solidified layer as shown in FIGS. 1 and 2, or may have a laminated structure of a first alignment-solidified layer 21 and a second alignment-solidified layer 22 as shown in FIG. 3. In the embodiment shown in FIG. 3, the first alignment-solidified layer 21 and the second alignment-solidified layer 22 are laminated via a second adhesive layer 32. In this case, the first alignment-solidified layer 21 includes a permeation layer 21a formed by the adhesive of the second adhesive layer 32 penetrating near the interface with the second adhesive layer 32; and the second alignment-solidified layer 22 includes a permeation layer 22a formed by the adhesive of the second adhesive layer 32 penetrating near the interface with the second adhesive layer 32. In this embodiment, peeling between the second adhesive layer and the first alignment-solidified layer 21 and the second alignment-solidified layer 22 can be particularly significantly suppressed. For example, a normal peeling operation may not cause the second adhesive layer to peel off from the first alignment solidified layer 21 and the second alignment solidified layer 22, and cohesive failure of the second adhesive layer may occur. In the embodiment of the present invention, it is sufficient that a permeation layer 20a (21a in this embodiment) formed by the adhesive of the first adhesive layer 31 permeates into the vicinity of the interface between the retardation layer 20 and the first adhesive layer 31. Therefore, the first alignment solidified layer 21 and the second alignment solidified layer 22 may be laminated, for example, via a pressure-sensitive adhesive layer.

[0013] As described above, the permeation layer is formed by the penetration of the adhesive from the adhesive layer. Specifically, permeation layers 20a, 21a, and 22a are portions of the alignment and solidification layers 20, 21, and 22 of the liquid crystal compound where the adhesive component is present, respectively; permeation layer 13a is a portion of the second protective layer 13 where the adhesive component is present. Although the detailed structure of the permeation layer is unclear, it is presumed that the molecules of the permeated adhesive (essentially the cured component before curing) become entangled (or, in some cases, chemically bonded by reaction) with the liquid crystal molecules of the alignment and solidification layer or the resin molecules constituting the second protective layer, thereby suppressing peeling. Furthermore, the formation of the permeation layer suppresses interfacial reflection, thereby suppressing display unevenness.

[0014] The thickness of the penetration layer is preferably 5 nm to 100 nm, more preferably 10 nm to 50 nm. The ratio of the thickness of the penetration layer to the thickness of the liquid crystal compound alignment layer (penetration layer / alignment layer) is preferably 0.2% to 20%, more preferably 0.2% to 10%. When the thickness of the penetration layer and the thickness ratio are within these ranges, peeling can be effectively suppressed and display unevenness can be effectively suppressed. If the thickness of the penetration layer is too large, the penetration layer and / or adhesive layer may become brittle and may peel off more easily. The thickness of the penetration layer can be measured from a transmission electron microscope (TEM) image of the cross section of the retardation layer-attached polarizing plate.

[0015] The peel strength between the first adhesive layer 31 and the liquid crystal compound alignment solidified layer 20 is preferably 0.7 N / 15 mm or more, more preferably 1.0 N / 15 mm or more, and even more preferably 1.5 N / 15 mm or more. It is difficult to specify an upper limit for this peel strength. This is because cohesive failure of the first adhesive layer or interlayer delamination between the first adhesive layer and the polarizing plate (typically, the second protective layer) occurs before the first adhesive layer 31 and the liquid crystal compound alignment solidified layer 20 are peeled off. The same applies to the peel strength between the second adhesive layer 32 and the first alignment solidified layer 21 and the second alignment solidified layer 22. The peel strength can be measured, for example, at a peel angle of 90° and a peel speed of 300 mm / min.

[0016] The above embodiments may be combined as appropriate, and modifications obvious to those skilled in the art may be made to the components of the above embodiments. For example, the polarizer of the retardation layer-attached polarizer of Fig. 3 may be provided with a second protective layer as shown in Fig. 2; the retardation layer of the retardation layer-attached polarizer of Fig. 2 may have a laminated structure of a first alignment-fixed layer 21 and a second alignment-fixed layer 22 as shown in Fig. 3; the retardation layer of the retardation layer-attached polarizer of Fig. 1 to Fig. 3 may be replaced with an optically equivalent structure as long as it is an alignment-fixed layer of a liquid crystal compound.

[0017] The retardation layer-attached polarizing plate according to an embodiment of the present invention may further include other optically functional layers. For example, the retardation layer-attached polarizing plate may further include another retardation layer and / or a conductive layer or a conductive layer-attached isotropic substrate (neither of which is shown). The other retardation layer and the conductive layer or the conductive layer-attached isotropic substrate are typically provided on the outside of the retardation layer 20 (the side opposite the polarizing plate 10). The other retardation layer typically exhibits a refractive index characteristic of nz > nx = ny. Such another retardation layer may be provided, for example, when the retardation layer 20 is a single layer of an orientation-solidified layer. The other retardation layer and the conductive layer or the conductive layer-attached isotropic substrate are typically provided in this order from the retardation layer 20 side. The other retardation layer and the conductive layer or the conductive layer-attached isotropic substrate are typically optional layers that are provided as needed, and either one or both may be omitted. In addition, when a conductive layer or a conductive-layer-attached isotropic substrate is provided, the retardation layer-attached polarizing plate 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 a polarizing plate. The type, characteristics, number, combination, arrangement position, etc. of the optical functional layer that can be provided in the retardation layer-attached polarizing plate can be appropriately set depending on the purpose.

[0018] The polarizing plate with a retardation layer of the present invention may be in the form of a sheet or a long sheet. In this specification, the term "long sheet" means a long and narrow shape whose length is sufficiently longer than its width, and includes, for example, a long and narrow shape whose length is 10 times or more, preferably 20 times or more, its width. A long polarizing plate with a retardation layer can typically be wound into a roll.

[0019] In practice, a pressure-sensitive adhesive layer (not shown) is provided as the outermost layer on the side of the retardation layer opposite the polarizing plate, so that the retardation layer-attached polarizing plate can be attached to an image display cell. Furthermore, it is preferable that a release film is temporarily attached to the surface of the pressure-sensitive adhesive layer until the retardation layer-attached polarizing plate is used. Temporarily attaching the release film protects the pressure-sensitive adhesive layer and enables the retardation layer-attached polarizing plate to be formed into a roll.

[0020] The total thickness of the retardation layer-attached polarizing plate is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, and particularly preferably 55 μm or less. The lower limit of the total thickness may be, for example, 28 μm. According to embodiments of the present invention, such an extremely thin retardation layer-attached polarizing plate can be realized. Such a retardation layer-attached polarizing plate can have extremely excellent flexibility and bending durability. Such a retardation layer-attached polarizing plate can be particularly suitably applied to curved image display devices and / or image display devices that can be bent or folded. The total thickness of the retardation layer-attached polarizing plate refers to the sum of the thicknesses of all layers constituting the retardation layer-attached polarizing plate, excluding the adhesive layer.

[0021] The components of the retardation layer-attached polarizing plate will be described in more detail below.

[0022] B. Polarizing Plate B-1. Polarizer Any appropriate polarizer can be adopted as the polarizer 11. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0023] Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with iodine or a dichroic substance such as a dichroic dye and stretched, and polyene-based oriented films such as dehydrated PVA films and dehydrochlorinated polyvinyl chloride films. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching it is used because of its excellent optical properties.

[0024] The dyeing with iodine is carried out, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA-based film may be stretched and then dyed. If necessary, the PVA-based film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA-based film in water and washing it before dyeing, it is possible to wash away dirt and antiblocking agents from the surface of the PVA-based film and also to swell the PVA-based film, thereby preventing uneven dyeing and the like.

[0025] Specific examples of polarizers obtained using laminates include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the solution to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In this embodiment, stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further involve in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The obtained 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 from the resin substrate / polarizer laminate and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such a method for producing a polarizer are described in, for example, JP 2012-73580 A. The entire disclosure of this publication is incorporated herein by reference.

[0026] The thickness of the polarizer is preferably 15 μm or less, more preferably 1 μm to 12 μm, even more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0027] The polarizer preferably exhibits absorptive dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is, as described above, 43.0% to 46.0%, preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0028] B-2. Protective Layer The first protective layer 12 and the second protective layer 13 are each formed of any appropriate film that can be used as a protective layer for a polarizer. Specific examples of materials that can be the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones. Other examples include glassy polymers such as siloxane polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in its side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in its side chain, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0029] As described below, the retardation layer-attached polarizing plate according to an embodiment of the present invention is typically disposed on the viewing side of an image display device, and the first protective layer 12 is typically disposed on the viewing side. Therefore, the first protective layer 12 may be subjected to a surface treatment such as a hard coat treatment, an anti-reflection treatment, an anti-sticking treatment, or an anti-glare treatment, as needed. Furthermore / alternatively, the first protective layer 12 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, by imparting an (elliptically) polarizing function or an ultra-high phase difference), as needed. By performing such a treatment, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the retardation layer-attached polarizing plate can be suitably applied to image display devices that can be used outdoors.

[0030] The thickness of the first protective layer is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm. When a surface treatment is applied, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

[0031] In one embodiment, the second protective layer 13 is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the thickness direction retardation Rth(550) is -10 nm to +10 nm. In one embodiment, the second protective layer 13 can be a retardation layer having any appropriate retardation value. In this case, the in-plane retardation Re(550) of the retardation layer is, for example, 110 nm to 150 nm. The thickness of the second protective layer is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 10 μm to 60 μm.

[0032] C. Retardation Layer As described above, the retardation layer 20 is an oriented and solidified layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to non-liquid crystal materials, so the thickness of the retardation layer required to obtain a desired in-plane retardation can be significantly reduced. As a result, a polarizing plate with a retardation layer can be further thinned. In this embodiment, typically, rod-shaped liquid crystal compounds are oriented in a state where they are aligned in the slow axis direction of the retardation layer (homogeneous orientation).

[0033] Examples of liquid crystal compounds include liquid crystal compounds whose liquid crystal phase is a nematic phase (nematic liquid crystals). Examples of such liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The mechanism by which the liquid crystallinity of liquid crystal compounds is expressed may be either lyotropic or thermotropic. Liquid crystal polymers and liquid crystal monomers may be used alone or in combination.

[0034] 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 crosslinking (i.e., curing) the liquid crystal monomer. After the liquid crystal monomer is aligned, for example, the alignment state can be fixed by polymerizing or crosslinking the liquid crystal monomers with each other. Here, a polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystals. Therefore, the formed retardation layer does not undergo, for example, a transition to a liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which is specific to liquid crystal compounds. As a result, the retardation layer becomes a retardation layer that is not affected by temperature changes and has excellent stability.

[0035] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type of the liquid crystal monomer. 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.

[0036] Any appropriate liquid crystal monomer can be used as the liquid crystal monomer. For example, polymerizable mesogen compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0,261,712, DE 19,504,224, DE 4,408,171, and GB 2,280,445 can be used. Specific examples of such polymerizable mesogen compounds include LC242 (product name) from BASF, E7 (product name) from Merck, and LC-Silicon-CC3767 (product name) from Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferred.

[0037] The alignment and solidification layer of the liquid crystal compound can be formed by performing an alignment treatment on the surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. In one embodiment, the substrate is any appropriate resin film, and the alignment and solidification layer formed on the substrate can be transferred to the surface of polarizing plate 10. In another embodiment, the substrate can be second protective layer 13. In this case, the transfer step is omitted, and lamination can be performed by roll-to-roll processing continuously from the formation of the alignment and solidification layer (retardation layer), further improving productivity.

[0038] Any appropriate alignment treatment can be adopted as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique deposition and photoalignment treatment. Any appropriate treatment conditions can be adopted for the various alignment treatments depending on the purpose.

[0039] The alignment of liquid crystal compounds is achieved by treating them at a temperature at which they exhibit a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compounds assume a liquid crystal state and are aligned in accordance with the alignment treatment direction of the substrate surface.

[0040] In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0041] Specific examples of liquid crystal compounds and details of the method for forming the alignment solidified layer are described in, for example, JP-A-2006-163343, the disclosure of which is incorporated herein by reference.

[0042] In one embodiment, the retardation layer 20 is a single layer of a layer of a liquid crystal compound with a fixed alignment, as shown in Figures 1 and 2. When the retardation layer 20 is composed of a single layer of a layer of a liquid crystal compound with a fixed alignment, its thickness is preferably 0.5 µm to 7 µm, and more preferably 1 µm to 5 µm. By using a liquid crystal compound, it is possible to achieve an in-plane retardation equivalent to that of a resin film with a thickness that is significantly thinner than that of a resin film.

[0043] The retardation layer typically exhibits a refractive index characteristic of nx>ny=nz. The retardation layer is typically provided to impart anti-reflection properties to the polarizing plate, and when the retardation layer is a single layer of an orientation-solidified 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. Note that "ny=nz" here encompasses not only cases where ny and nz are completely equal, but also cases where they are substantially equal. Therefore, there may be cases where ny>nz or ny<nz, as long as the effects of the present invention are not impaired.

[0044] 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 obtained polarizing plate with a retardation layer is used in an image display device, an extremely excellent reflection hue can be achieved.

[0045] The retardation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the retardation value hardly changes according to the wavelength of the measurement light. In one embodiment, the retardation layer exhibits a reverse dispersion wavelength characteristic. In this case, the Re(450) / Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent anti-reflection properties can be achieved.

[0046] The angle θ between the slow axis of the retardation 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°. If the angle θ is in this range, by using a λ / 4 plate as the retardation layer as described above, a retardation layer-attached polarizing plate having very excellent circular polarization properties (as a result, very excellent antireflection properties) can be obtained.

[0047] In another embodiment, the retardation layer 20 may have a laminated structure of a first alignment solidified layer 21 and a second alignment solidified layer 22, as shown in FIG. 3 . In this case, either the first alignment solidified layer 21 or the second alignment solidified layer 22 may function as a λ / 4 plate, and the other may function as a λ / 2 plate. Therefore, the thicknesses of the first alignment solidified layer 21 and the second alignment solidified layer 22 may be adjusted to obtain the desired in-plane retardation of the λ / 4 plate or the λ / 2 plate. For example, when the first alignment solidified layer 21 functions as a λ / 2 plate and the second alignment solidified layer 22 functions as a λ / 4 plate, the thickness of the first alignment solidified layer 21 is, for example, 2.0 μm to 3.0 μm, and the thickness of the second alignment solidified layer 22 is, for example, 1.0 μm to 2.0 μm. In this case, the in-plane retardation Re(550) of the first alignment solidified 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 retardation Re(550) of the second alignment solidified layer is as described above for a single-layer alignment solidified layer. The angle between the slow axis of the first alignment solidified 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 alignment solidified 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 this configuration, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, it is possible to realize very excellent antireflection characteristics. The liquid crystal compounds constituting the first alignment solidified layer and the second alignment solidified layer, the methods for forming the first alignment solidified layer and the second alignment solidified layer, the optical properties, etc. are as described above for the single-layer alignment solidified layer.

[0048] D. Adhesive Layer The first adhesive layer and the second adhesive layer are collectively referred to as the adhesive layer. The first adhesive layer and the second adhesive layer may have the same configuration or different configurations. Any suitable adhesive capable of penetrating into the alignment / solidification layer of the liquid crystal compound to form a permeation layer can be used as the adhesive constituting the adhesive layer. Typical examples of the adhesive include active energy ray-curable adhesives. Examples of active energy ray-curable adhesives include ultraviolet-curable adhesives and electron beam-curable adhesives. In terms of the curing mechanism, examples of active energy ray-curable adhesives include radical-curable adhesives, cationic-curable adhesives, anionic-curable adhesives, and hybrids of radical-curable and cationic-curable adhesives. Typically, radical-curable ultraviolet-curable adhesives can be used. This is because they are highly versatile and their properties (configuration) can be easily adjusted.

[0049] The adhesive typically contains a curing component and a photopolymerization initiator. Typical examples of the curing component include monomers and / or oligomers having functional groups such as (meth)acrylate groups and (meth)acrylamide groups. Specific examples of the curing component include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, EO-modified diglycerin tetraacrylate, γ-butyrolactone acrylate, acryloylmorpholine, unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone, N-methylpyrrolidone, hydroxyethylacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, and N-ethoxymethylacrylamide. These curing components may be used alone or in combination of two or more.

[0050] Preferably, the adhesive contains a curing component having a heterocyclic ring. Examples of curing components having a heterocyclic ring include acryloylmorpholine, γ-butyrolactone acrylate, unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone, and N-methylpyrrolidone. More preferred curing components are unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone and acryloylmorpholine, and a particularly preferred curing component is acryloylmorpholine. The curing component having a heterocyclic ring can be contained in the adhesive in a proportion of preferably 50 parts by weight or more, more preferably 60 parts by weight or more, and even more preferably 70 to 95 parts by weight per 100 parts by weight of the curing component (if an oligomer component, described below, is present, the total of the curing component and the oligomer component). The acryloylmorpholine can be contained in the adhesive in a proportion of preferably 5 to 60 parts by weight, more preferably 10 to 50 parts by weight per 100 parts by weight of the curing component (if an oligomer component is present, the total of the curing component and the oligomer component).

[0051] The adhesive may further contain an oligomer component in addition to the curing component. The use of the oligomer component reduces the viscosity of the adhesive before curing and improves operability. A typical example of the oligomer component is a (meth)acrylic oligomer. Examples of (meth)acrylic monomers constituting the (meth)acrylic oligomer include (meth)acrylic acid (having 1 to 20 carbon atoms) alkyl esters, cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), alkoxy group- or phenoxy group-containing (meth)acrylic acid esters (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, etc.), and the like. ) acrylic acid esters (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (for example, glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (for example, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc.), alkylaminoalkyl (meth)acrylates (for example, dimethylaminoethyl (meth)acrylate, etc.).Specific examples of (meth)acrylic acid (C1 to C20) alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate. These (meth)acrylates may be used alone or in combination of two or more.

[0052] As the photopolymerization initiator, a photopolymerization initiator known in the art can be used in a blending amount known in the art, and therefore a detailed description thereof will be omitted.

[0053] The thickness of the adhesive layer (after the adhesive has hardened) is preferably 0.1 μm to 3.0 μm. By applying the adhesive to such a thickness, a permeation layer of appropriate thickness can be formed.

[0054] Details of the adhesive are described in, for example, JP 2018-017996 A. The disclosure of this publication is incorporated herein by reference.

[0055] E. Another Retardation Layer As described above, the another retardation layer may be a so-called positive C plate, whose refractive index characteristics exhibit the relationship nz > nx = ny. By using a positive C plate as the another retardation layer, reflection in oblique directions can be effectively prevented, enabling the anti-reflection function to have a wide viewing angle. In this case, the thickness direction retardation Rth(550) of the another retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even more preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. Here, "nx = ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane retardation Re(550) of the another retardation layer may be less than 10 nm.

[0056] The separate retardation layer having the refractive index characteristic of nz > nx = ny can be formed from any appropriate material. The separate retardation layer is preferably made of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in paragraphs

[0020] to

[0028] of JP-A No. 2002-333642. In this case, the thickness of the separate retardation 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.

[0057] F. Conductive Layer or Isotropic Substrate with Conductive Layer The conductive layer can be formed by forming a metal oxide film on any suitable substrate by any appropriate film formation 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.

[0058] When the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, more preferably 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

[0059] The conductive layer may be transferred from the substrate to the retardation layer (or another retardation layer, if present) and used alone as a constituent layer of a retardation-layer-attached polarizing plate, or may be laminated with the substrate (substrate with conductive layer) as a laminate on the retardation layer (or another retardation layer, if present). Preferably, the substrate is optically isotropic, and therefore the conductive layer can be used in a retardation-layer-attached polarizing plate as an isotropic substrate with a conductive layer.

[0060] Any suitable isotropic substrate can be used as the optically isotropic substrate (isotropic substrate). Examples of materials constituting the isotropic substrate include materials having a non-conjugated resin as the main skeleton, such as norbornene resins and olefin resins, and materials having a cyclic structure, such as a lactone ring or glutarimide ring, in the main chain of an acrylic resin. By using such materials, when an isotropic substrate is formed, the occurrence of retardation due to the orientation of molecular chains can be minimized. The thickness of the isotropic substrate is preferably 50 μm or less, more preferably 35 μm or less. The lower limit of the thickness of the isotropic substrate is, for example, 20 μm.

[0061] The conductive layer and / or the conductive layer of the isotropic substrate with a conductive layer can be patterned as needed. By patterning, conductive portions and insulating portions can be formed. As a result, electrodes can be formed. The electrodes can function as touch sensor electrodes that detect touch on the touch panel. Any appropriate patterning method can be used. Specific examples of patterning methods include wet etching and screen printing.

[0062] G. Image Display Device The retardation layer-attached polarizing plate described in the above sections A to F can be applied to an image display device. Accordingly, the present invention encompasses an image display device using such a retardation layer-attached polarizing plate. Representative examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices, inorganic EL display devices (e.g., quantum dot display devices)). An image display device according to an embodiment of the present invention includes the retardation layer-attached polarizing plate described in the above sections A to F on its viewing side. The retardation layer-attached polarizing plate is laminated so that the retardation layer faces the image display cell (e.g., liquid crystal cell, organic EL cell, inorganic EL cell) (so that the polarizer faces the viewing side). In one embodiment, the image display device has a curved shape (essentially a curved display screen) and / or is bendable or foldable. In such an image display device, the retardation layer-attached polarizing plate of the present invention exhibits remarkable effects.

[0063] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are by weight.

[0064] [Production Example 1] Adhesive A was prepared by mixing 50 parts of unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone ("Placcel FA1DDM" manufactured by Daicel Corporation), 40 parts of acryloylmorpholine ("ACMO (registered trademark)" manufactured by Kojin Co., Ltd.), 10 parts of an acrylic oligomer ("ARFON UP-1190" manufactured by Toagosei Co., Ltd.), and 3 parts of "KAYACURE DETX-S" (manufactured by Nippon Kayaku Co., Ltd.) and 3 parts of OMNIRAD907 (IGM Resins Italia S.r.l.) as photopolymerization initiators.

[0065] [Production Example 2] Adhesive B was prepared by mixing 50 parts of unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone ("Placcel FA1DDM" manufactured by Daicel Corporation), 40 parts of phenoxydiethylene glycol acrylate ("Light Acrylate P2H-A" manufactured by Kyoeisha Chemical Co., Ltd.), 10 parts of an acrylic oligomer ("ARFON UP-1190" manufactured by Toagosei Co., Ltd.), and 3 parts of "KAYACURE DETX-S" (manufactured by Nippon Kayaku Co., Ltd.) and 3 parts of OMNIRAD907 (IGM Resins Italia S.r.l.) as photopolymerization initiators.

[0066] Example 1 1. Preparation of Polarizing Plate An A-PET (amorphous polyethylene terephthalate) film (manufactured by Mitsubishi Plastics, Inc., product name: Novaclear SH046, thickness 200 μm) was prepared as a substrate, and its surface was subjected to corona treatment (58 W / m2 / min). On the other hand, a PVA (polymerization degree 4200, saponification degree 99.2%) containing 1 wt% of acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name: Gohsefimer Z200, polymerization degree 1200, saponification degree 99.0% or more, acetoacetyl modification degree 4.6%) was prepared and coated to a film thickness of 12 μm after drying. The film was then dried for 10 minutes by hot air drying at 60°C to prepare a laminate having a PVA-based resin layer on the substrate. Next, this laminate was first stretched 2.0 times in air at 130°C to obtain a stretched laminate. Next, the stretched laminate was immersed in a boric acid insolubilizing solution at 30°C for 30 seconds to insolubilize the PVA-based resin layer in which the PVA molecules contained in the stretched laminate were oriented. The boric acid insolubilizing solution used in this step had a boric acid content of 3 wt% relative to 100 wt% water. A dyed laminate was produced by dyeing this stretched laminate. The dyed laminate was produced by immersing the stretched laminate in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30°C, thereby adsorbing iodine into the PVA-based resin layer contained in the stretched laminate. The iodine concentration and immersion time were adjusted so that the resulting polarizer had a single transmittance of 44.5%. Specifically, the dyeing solution contained water as the solvent, an iodine concentration in the range of 0.08 to 0.25 wt%, and a potassium iodide concentration in the range of 0.56 to 1.75 wt%. The iodine to potassium iodide concentration ratio was 1:7. Next, the colored laminate was immersed in a boric acid crosslinking solution at 30°C for 60 seconds to crosslink the PVA molecules in the iodine-adsorbed PVA-based resin layer. The boric acid crosslinking solution used in this step had a boric acid content of 3 wt% relative to 100 wt% water and a potassium iodide content of 3 wt% relative to 100 wt% water. The resulting colored laminate was then stretched 2.7 times in the same direction as the above-mentioned stretching in air at a stretching temperature of 70°C in the boric acid solution, resulting in a final stretch ratio of 5.4 times, thereby obtaining a substrate / polarizer laminate. The polarizer had a thickness of 5 μm.The boric acid crosslinking aqueous solution used in this step contained 6.5 wt% boric acid relative to 100 wt% water and 5 wt% potassium iodide relative to 100 wt% water. The resulting laminate was removed from the boric acid aqueous solution, and the boric acid adhering to the polarizer surface was washed with an aqueous solution containing 2 wt% potassium iodide relative to 100 wt% water. The washed laminate was dried with hot air at 60°C. A 40 μm-thick triacetyl cellulose (TAC) film was bonded to the polarizer surface of the substrate / polarizer laminate obtained above via a PVA-based adhesive, yielding a laminate having a protective layer (TAC film) / polarizer / resin substrate configuration. Furthermore, the resin substrate was peeled from this laminate, and a 40 μm-thick TAC film was bonded to the peeled surface to yield a laminate (polarizing plate) having a protective layer (TAC film) / polarizer / protective layer (TAC film) configuration.

[0067] 2. Preparation of Aligned and Solidified Layer of Liquid Crystal Compound Constituting Retardation Layer 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "Irgacure 907") were dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid). The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed with a rubbing cloth to perform an alignment treatment. The direction of the alignment treatment was set to a 45° angle from the viewing side with respect to the direction of the absorption axis of the polarizer when it was attached to the polarizing plate. The above liquid crystal coating solution was applied to this alignment-treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90° C. for 2 minutes. The liquid crystal layer thus formed was irradiated with 1 mJ / cm using a metal halide lamp. ２ The liquid crystal layer was cured by irradiating the PET film with light of 1000 W at ...

[0068] 3. Preparation of Polarizing Plate with Retardation Layer The liquid crystal alignment solidified layer A obtained in 2. above was transferred to the surface of the polarizing plate (essentially a TAC film as a protective layer) obtained in 1. above via the adhesive A (thickness after curing: 1.0 μm) obtained in Production Example 1. In this way, a polarizing plate with a retardation layer was obtained having a configuration of protective layer (TAC film) / polarizer / protective layer (TAC film) / adhesive layer (adhesive A) / retardation layer (liquid crystal alignment solidified layer A, λ / 4 plate, slow axis 45° direction). When the cross section of the obtained polarizing plate with a retardation layer was observed with a transmission electron microscope (TEM), a penetration layer formed by the adhesive A penetrating into both the retardation layer (liquid crystal alignment solidified layer A) and the protective layer (TAC film) was confirmed. A TEM image showing the state of the interface between the adhesive layer and the retardation layer (liquid crystal alignment solidified layer A) is shown in FIG. 4.

[0069] 4. Evaluation of Peelability The peelability of the obtained polarizing plate with a retardation layer was evaluated. Specifically, the evaluation was as follows. The obtained polarizing plate with a retardation layer was cut into a size of 200 mm parallel to the absorption axis direction of the polarizer and 15 mm in the perpendicular direction, and then bonded to a glass plate. A peel test was performed in a 90° direction at a peel speed of 300 mm / min using a Tensilon universal testing machine RTC manufactured by A&D Co., Ltd., and the peel strength was measured. In the peel test, peeling occurred at the interface between the TAC film and the adhesive layer, and the peel strength was 0.8 N / 15 mm.

[0070] [Example 2] A retardation layer-attached polarizing plate having a configuration of protective layer (TAC film) / polarizer / protective layer (COP film) / adhesive layer (adhesive A) / retardation layer (liquid crystal alignment solidified layer A, λ / 4 plate, slow axis 45° direction) was obtained in the same manner as in Example 1, except that a cycloolefin resin (COP) film was attached to the release surface of the resin substrate instead of the TAC film in the production of the polarizing plate. When the cross section of the obtained retardation layer-attached polarizing plate was observed with a transmission electron microscope (TEM), a permeation layer formed by the adhesive A permeating into the retardation layer (liquid crystal alignment solidified layer A) was confirmed. Furthermore, the peelability of the obtained retardation layer-attached polarizing plate was evaluated in the same manner as in Example 1. In a peel test, peeling occurred at the interface between the retardation layer (liquid crystal alignment solidified layer A) and the adhesive layer, and the peel strength was 0.7 N / 15 mm.

[0071] [Example 3] A retardation layer-attached polarizing plate having a configuration of protective layer (TAC film) / polarizer / protective layer (acrylic film) / adhesive layer (adhesive A) / retardation layer (liquid crystal alignment solidified layer A, λ / 4 plate, slow axis 45° direction) was obtained in the same manner as in Example 1, except that an acrylic resin film was attached to the release surface of the resin substrate instead of the TAC film in the production of the polarizing plate. When the cross section of the obtained retardation layer-attached polarizing plate was observed with a transmission electron microscope (TEM), a permeation layer formed by the adhesive A permeating into the retardation layer (liquid crystal alignment solidified layer A) was confirmed. Furthermore, the peelability of the obtained retardation layer-attached polarizing plate was evaluated in the same manner as in Example 1. In a peel test, peeling occurred at the interface between the acrylic film and the adhesive layer, and the peel strength was 0.3 N / 15 mm.

[0072] [Example 4] A retardation layer-attached polarizing plate having a configuration of protective layer (TAC film) / polarizer / adhesive layer (adhesive A) / retardation layer (liquid crystal alignment solidified layer A, λ / 4 plate, slow axis 45° direction) was obtained in the same manner as in Example 1, except that no protective layer was provided on the release surface of the resin substrate in the production of the polarizing plate. When the cross section of the obtained retardation layer-attached polarizing plate was observed with a transmission electron microscope (TEM), a permeation layer formed by penetration of adhesive A into the retardation layer (liquid crystal alignment solidified layer A) was confirmed. Furthermore, the releasability of the obtained retardation layer-attached polarizing plate was evaluated in the same manner as in Example 1. In the peel test, no peeling occurred.

[0073] [Example 5] A polarizing plate having a protective layer (TAC film) / polarizer configuration was obtained in the same manner as in Example 4. A liquid crystal alignment solidified layer B was formed on a PET film in the same manner as in Example 1, except that the coating thickness was changed and the alignment treatment direction was set to a 15° angle relative to the absorption axis of the polarizer as viewed from the viewing side. The liquid crystal alignment solidified layer B had a thickness of 2.5 μm and an in-plane retardation Re(550) of 270 nm. The liquid crystal alignment solidified layer B was transferred to the polarizer surface of the polarizing plate via adhesive A (thickness after curing: 1.0 μm). Furthermore, a liquid crystal alignment solidified layer A prepared in the same manner as in Example 1, except that the alignment treatment direction was set to a 75° angle relative to the absorption axis of the polarizer as viewed from the viewing side, was transferred to the surface of the liquid crystal alignment solidified layer B via adhesive A (thickness after curing: 1.0 μm). In this way, a retardation layer-attached polarizing plate was obtained having a configuration of protective layer (TAC film) / polarizer / adhesive layer (adhesive A) / liquid crystal alignment solidified layer B (λ / 2 plate, slow axis 15° direction) / adhesive layer (adhesive A) / liquid crystal alignment solidified layer A (λ / 4 plate, slow axis 75° direction). When the cross section of the obtained retardation layer-attached polarizing plate was observed with a transmission electron microscope (TEM), permeation layers formed by the adhesive A permeating into both the liquid crystal alignment solidified layer A and the liquid crystal alignment solidified layer B were confirmed. Furthermore, the peelability of the obtained retardation layer-attached polarizing plate was evaluated in the same manner as in Example 1. In the peel test, the adhesive layer between the liquid crystal alignment solidified layer A and the liquid crystal alignment solidified layer B underwent cohesive failure.

[0074] Comparative Example 1 A retardation layer-attached polarizing plate having a configuration of protective layer (TAC film) / polarizer / adhesive layer (adhesive B) / retardation layer (liquid crystal alignment solidified layer A, λ / 4 plate, slow axis 45° direction) was obtained in the same manner as in Example 4, except that adhesive B (thickness after curing: 1.0 μm) obtained in Production Example 2 was used instead of adhesive A. When the cross section of the obtained retardation layer-attached polarizing plate was observed with a transmission electron microscope (TEM), no permeation layer was observed. A TEM image showing the state of the interface between the adhesive layer and the retardation layer (liquid crystal alignment solidified layer A) is shown in FIG. 5. Furthermore, the peelability of the obtained retardation layer-attached polarizing plate was evaluated in the same manner as in Example 1. In a peel test, peeling occurred at the interface between the liquid crystal alignment solidified layer A and the adhesive layer, and the peel strength was 0.5 N / 15 mm.

[0075] [Evaluation] As is clear from a comparison between the Examples and the Comparative Examples, the Examples of the present invention can suppress peeling of the liquid crystal alignment solidified layer.

[0076] The retardation layer-attached polarizing plate of the present invention is suitably used as a circular polarizing plate for liquid crystal displays, organic EL displays, and inorganic EL displays.

[0077] REFERENCE SIGNS LIST 10 Polarizing plate 11 Polarizer 12 First protective layer 13 Second protective layer 20 Retardation layer 20a Permeation layer 21 First alignment solidified layer 21a Permeation layer 22 Second alignment solidified layer 22a Permeation layer 31 First adhesive layer 32 Second adhesive layer 100 Retardation layer-attached polarizing plate 101 Retardation layer-attached polarizing plate 102 Retardation layer-attached polarizing plate

Claims

1. A polarizing plate with a retardation layer, comprising: a polarizing plate including a polarizer and a protective layer on at least one side of the polarizer; and a retardation layer laminated on the polarizing plate via a first adhesive layer, wherein the retardation layer is an alignment-solidified layer of a liquid crystal compound, and the retardation layer includes a permeation layer formed by permeation of the adhesive of the first adhesive layer near the interface with the first adhesive layer.

2. The polarizing plate with a retardation layer according to claim 1, wherein the polarizing plate comprises the polarizer and a protective layer disposed on the polarizer opposite to the retardation layer.

3. The retardation layer-attached polarizing plate according to claim 1, wherein the polarizing plate comprises the polarizer and protective layers disposed on both sides of the polarizer.

4. A polarizing plate with a retardation layer according to claim 3, wherein the protective layer arranged on the retardation layer side of the polarizer includes a penetration layer formed by penetration of the adhesive of the first adhesive layer near the interface with the first adhesive layer.

5. The polarizing plate with a retardation layer according to any one of claims 1 to 4, wherein the retardation layer is a single layer of a liquid crystal compound with a fixed alignment, the retardation layer has an Re(550) of 100 nm to 190 nm, and the angle between the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50°.

6. The polarizing plate with a retardation layer according to any one of claims 1 to 4, wherein the retardation layer comprises a fixed alignment layer of a first liquid crystal compound and a fixed alignment layer of a second liquid crystal compound laminated on the fixed alignment layer of the first liquid crystal compound via a second adhesive layer, wherein the fixed alignment layer of the first liquid crystal compound and the fixed alignment layer of the second liquid crystal compound each include a penetration layer formed by penetration of the adhesive of the second adhesive layer near the interface with the second adhesive layer, wherein the fixed alignment layer of the first liquid crystal compound has an Re(550) of 200nm to 300nm and the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°, and wherein the Re(550) of the fixed alignment layer of the second liquid crystal compound is 100nm to 190nm and the angle between its slow axis and the absorption axis of the polarizer is 70° to 80°.

7. The polarizing plate with a retardation layer according to any one of claims 1 to 6, wherein the adhesive of the first and second adhesive layers each contains acryloylmorpholine.

8. A polarizing plate with a retardation layer according to any one of claims 1 to 7, further comprising another retardation layer on the outer side of the retardation layer, the refractive index characteristics of the other retardation layer exhibiting the relationship nz > nx = ny.

9. An image display device comprising the polarizing plate with a retardation layer according to any one of claims 1 to 8.

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