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

Abstract

The present invention provides a thin polarizing plate with a retardation layer, which has excellent reliability in a high-temperature and high-humidity environment when applied to an image display device and can suppress an increase in reflectance. The polarizing plate with a retardation layer of the present invention sequentially includes a polarizing plate containing a polarizing element, a retardation layer, and an adhesive layer from the visually recognizable side. The retardation layer is an orientation cured layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function. The polarizing plate with a retardation layer is provided with an iodine permeation inhibition layer between the polarizing element and the adhesive layer, and the iodine permeation inhibition layer is a solidified product or a thermoset product of a coating film of a resin organic solvent solution; the iodine absorption index of the iodine permeation inhibition layer is 0.015 or less.

Description

Technical Field

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

[0002] In recent years, image display devices typified by liquid crystal display devices and electroluminescent (EL) display devices (e.g., organic EL display devices, inorganic EL display devices) have rapidly spread. Image display devices typically use a polarizing plate and a retardation plate. In practical applications, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (e.g., Patent Document 1). However, recently, as the demand for thinning of image display devices has increased, the demand for thinning of the polarizing plate with a retardation layer has also increased. For the purpose of thinning the polarizing plate with a retardation layer, thinning (or omission) of the protective layer of the polarizing member that has a large influence on the thickness and thinning of the retardation film have been promoted. However, when a thin polarizing plate with a retardation layer is applied to an image display device, there are cases where the reliability is insufficient in a high-temperature and high-humidity environment. More specifically, the polarizing plate with a retardation layer is typically used as an antireflection film, but there are cases where the reflectance of the image display device increases in a high-temperature and high-humidity environment. In addition, when a thin polarizing plate with a retardation layer is applied to an image display device, there are cases where metal components (e.g., electrodes, sensors, wirings, metal layers) of the image display device are corroded.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 3325560 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The present invention has been made to solve the above-described prior problems, and its main object is to provide a thin polarizing plate with a retardation layer that has excellent reliability in a high-temperature and high-humidity environment when applied to an image display device and can suppress an increase in reflectance.

[0008] Means for Solving the Problems

[0009] The polarizing plate with a retardation layer of the present invention has, in order from the visually recognizable side, a polarizing plate including a polarizing member, a retardation layer, and an adhesive layer. The retardation layer is an alignment cured layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function. An iodine permeation inhibition layer is provided between the polarizing member and the adhesive layer of the polarizing plate with a retardation layer. The iodine permeation inhibition layer is a solidified product or a thermoset product of a coating film of a resin organic solvent solution; the iodine absorption index of the iodine permeation inhibition layer is 0.015 or less.

[0010] In one embodiment, the iodine permeation inhibiting layer is disposed between the polarizer and the retardation layer. In another embodiment, the iodine permeation inhibiting layer is disposed between the retardation layer and the adhesive layer.

[0011] In one embodiment, there are two or more iodine permeation inhibiting layers between the polarizer and the adhesive layer.

[0012] In one embodiment, the potassium absorption index of the iodine permeation inhibiting layer is 0.015 or less.

[0013] In one embodiment, the glass transition temperature of the resin constituting the iodine permeation inhibiting layer is 85°C or higher, and the weight average molecular weight Mw is 25,000 or higher.

[0014] In one embodiment, the resin constituting the iodine permeation inhibiting layer contains a copolymer obtained by polymerizing a monomer mixture, the monomer mixture containing more than 50 parts by weight of a (meth)acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by formula (1):

[0015]

[0016] (In the formula, X represents a functional group containing a reactive group, and the reactive group is at least one reactive group selected from the group consisting of a vinyl group, a (meth)acryloyl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group, R 1 and R 2 each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aryl group, or an optionally substituted heterocyclic group, R 1 and R 2 optionally connect to each other to form a ring).

[0017] In one embodiment, the retardation layer is a single layer, the Re(550) of the retardation layer is 100 nm to 190 nm, and the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50°.

[0018] In one embodiment, the above-mentioned retardation layer has a laminated structure of an alignment cured layer of a first liquid crystal compound and an alignment cured layer of a second liquid crystal compound; the Re(550) of the alignment cured layer of the first liquid crystal compound is 200 nm to 300 nm, and the angle formed by its slow axis and the absorption axis of the above-mentioned polarizer is 10° to 20°; the Re(550) of the alignment cured layer of the second liquid crystal compound is 100 nm to 190 nm, and the angle formed by its slow axis and the absorption axis of the polarizer is 70° to 80°.

[0019] In one embodiment, the above-mentioned polarizing plate with a retardation layer further has another retardation layer between the above-mentioned retardation layer and the above-mentioned adhesive layer, and the refractive index characteristics of this other retardation layer show a relationship of nz > nx = ny.

[0020] In one embodiment, the above-mentioned polarizing plate with a retardation layer further has a conductive layer or an isotropic substrate with a conductive layer between the above-mentioned iodine permeation inhibition layer and the above-mentioned adhesive layer.

[0021] In one embodiment, the total thickness of the above-mentioned polarizing plate with a retardation layer is 60 μm or less.

[0022] According to another aspect of the present invention, an image display device is provided. This image display device includes the above-mentioned polarizing plate with a retardation layer.

[0023] In one embodiment, the above-mentioned image display device is an organic electroluminescent display device or an inorganic electroluminescent display device.

[0024] Effects of the Invention

[0025] According to the embodiment of the present invention, by providing an iodine permeation inhibition layer having a specified iodine absorption index at a specified position of a thin polarizing plate with a retardation layer, an increase in reflectance in a high-temperature and high-humidity environment can be suppressed when the polarizing plate with a retardation layer is applied to an image display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A It is a schematic cross-sectional view of a polarizing plate with a retardation layer according to an embodiment of the present invention.

[0027] Figure 1B It is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention.

[0028] Figure 2 It is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention.

[0029] Figure 3 It is a schematic cross-sectional view of a polarizing plate with a retardation layer according to still another embodiment of the present invention.

[0030] Figure 4 Schematic cross-sectional view of a polarizing plate with a phase difference layer according to another embodiment of the present invention.

[0031] Figure 5 Schematic cross-sectional view of a polarizing plate with a phase difference layer according to another embodiment of the present invention. Detailed Embodiments

[0032] Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0033] (Definition of Terms and Symbols)

[0034] The terms and symbols in this specification are defined as follows.

[0035] (1) Refractive Index (nx, ny, nz)

[0036] "nx" is the refractive index in the direction where the in-plane refractive index reaches the maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction.

[0037] (2) In-Plane Phase Difference (Re)

[0038] "Re(λ)" is the in-plane phase difference measured at 23 °C with light of wavelength λ nm. For example, "Re(550)" is the in-plane phase difference measured at 23 °C with light of wavelength 550 nm. When the thickness of the layer (thin film) is set to d (nm), Re(λ) is obtained by the formula: Re(λ) = (nx - ny) × d.

[0039] (3) Phase Difference in the Thickness Direction (Rth)

[0040] "Rth(λ)" is the phase difference in the thickness direction measured at 23 °C with light of wavelength λ nm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23 °C with light of wavelength 550 nm. When the thickness of the layer (thin film) is set to d (nm), Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d.

[0041] (4) Nz Coefficient

[0042] The Nz coefficient can be obtained by Nz = Rth / Re.

[0043] (5) Angle

[0044] When an angle is mentioned in this specification, the angle includes both the clockwise direction and the counterclockwise direction with respect to the reference direction. Therefore, for example, "45°" means ±45°.

[0045] A. Overall Structure of Polarizing Plate with Phase Difference Layer

[0046] Figure 1A FIG. 4 is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to an embodiment of the present invention; Figure 1B FIG. 5 is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to another embodiment of the present invention. Figure 1A and Figure 1B The polarizing plates 100 and 101 with a phase difference layer each have a polarizing plate 10, a phase difference layer 20, and an adhesive layer 30 in this order from the visually recognizable side. The polarizing plate 10 typically includes a polarizing element 11 and a protective layer 12 disposed on the visually recognizable side of the polarizing element 11. Depending on the purpose, another protective layer (not shown) may be provided on the side of the polarizing element 11 opposite to the visually recognizable side (protective layer 12). The phase difference layer 20 is an alignment cured 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 alignment cured layer). The adhesive layer 30 is provided as the outermost layer, and the polarizing plate with a phase difference layer can be attached to an image display device (substantially an image display unit).

[0047] In an embodiment of the present invention, an iodine permeation inhibition layer 40 is provided between the polarizing element 11 and the adhesive layer 30. The iodine permeation inhibition layer 40 can be provided between the polarizing element 11 and the phase difference layer 20 (i.e., adjacent to the polarizing element 11) as shown in Figure 1A , or can be provided between the phase difference layer 20 and the adhesive layer 30 as shown in Figure 1B . When the iodine permeation inhibition layer is provided between the polarizing element and the phase difference layer (especially when the iodine permeation inhibition layer is adjacent to the polarizing element), the movement of iodine from the polarizing element can be inhibited in a high-temperature and high-humidity environment, and the advantage of improved reliability can be obtained. When the iodine permeation inhibition layer is provided between the phase difference layer and the adhesive layer (especially when the iodine permeation inhibition layer is adjacent to the adhesive layer), it is also possible to prevent the movement of components other than iodine that may affect metal corrosion (such as residue monomer components in ultraviolet curable adhesives and decomposition products of photoinitiators) into the adhesive, and the advantage of further improving the metal corrosion inhibition effect can be obtained.

[0048] In the polarizing plate with a phase difference layer, two or more iodine permeation inhibition layers may be provided between the polarizing element and the adhesive layer (for example Figure 4 and Figure 5 ). By having two or more iodine permeation inhibition layers in the polarizing plate with a phase difference layer, the corrosion of metal components can be significantly inhibited when the polarizing plate with a phase difference layer is applied to an image display device.

[0049] Figure 4 In the polarizing plate with a phase difference layer shown in FIG. 6, two iodine permeation inhibition layers are provided between the polarizing element and the adhesive layer. Figure 4In the example shown, there are two iodine permeation inhibiting layers provided between the polarizer 11 and the retardation layer 20 and between the retardation layer 20 and the adhesive layer 30. In one embodiment, the iodine permeation inhibiting layer is provided adjacent to the polarizer. In another embodiment, the iodine permeation inhibiting layer is provided adjacent to the retardation layer. "Adjacent" in this specification means directly laminated without using an adhesive layer or the like.

[0050] Figure 5 In the polarizing plate with a retardation layer shown, three iodine permeation inhibiting layers are provided between the polarizer and the adhesive layer. Figure 5 In the example shown, two iodine permeation inhibiting layers are provided between the polarizer 11 and the retardation layer 20, and one iodine permeation inhibiting layer is provided between the retardation layer 20 and the adhesive layer 30. One of the two iodine permeation inhibiting layers between the polarizer 11 and the retardation layer 20 is provided adjacent to the polarizer, and the other is provided adjacent to the retardation layer.

[0051] In the polarizing plate with a retardation layer, the iodine permeation inhibiting layer can also be four or more layers (for example, 4 layers, 5 layers, 6 layers). The more the number of iodine permeation inhibiting layers, the more the metal corrosion inhibition effect can be improved. The number of iodine permeation inhibiting layers can be set in consideration of costs, manufacturing efficiency, the layer thickness of the polarizing plate with a retardation layer, and the like.

[0052] The iodine absorption index of the iodine permeation inhibiting layer is 0.015 or less. By providing such an iodine permeation inhibiting layer at a predetermined position of the polarizing plate with a retardation layer, when the polarizing plate with a retardation layer is applied to an image display device, the movement of iodine in the polarizer to the image display device (substantially the image display unit) can be significantly inhibited. As a result, when the polarizing plate with a retardation layer is applied to an image display device, a decrease in reliability caused by iodine in a high-temperature and high-humidity environment can be inhibited, and thus an increase in reflectance can be inhibited. Furthermore, the potassium absorption index of the iodine permeation inhibiting layer is preferably 0.015 or less. By having not only an iodine absorption index below a specified value but also a potassium absorption index below a specified value, the iodine permeation inhibiting layer can further inhibit a decrease in reliability caused by iodine in a high-temperature and high-humidity environment, and thus can further inhibit an increase in reflectance.

[0053] Such an effect is peculiar to a polarizing plate with a thin retardation layer (typically, a polarizing plate with a retardation layer being a liquid crystal alignment cured layer). That is, the inventors newly discovered the following problem: when applying a polarizing plate with a thin retardation layer to an image display device, there is a case where the reflectance increases in a high-temperature and high-humidity environment, and it was clarified that such a problem can be caused by iodine. Then, through repeated studies, it was found that an iodine permeation inhibition layer having the iodine absorption index as described above is useful as a means for preventing iodine from moving to the image display device (substantially an image display unit), and thus the present invention was completed. That is, such an effect solves a hitherto unknown new problem and is an unexpectedly excellent effect. Furthermore, as described later, the iodine permeation inhibition layer can be formed very thin, and by providing the iodine permeation inhibition layer, the protective layer on the side opposite to the visual recognition side can be omitted. Therefore, through their synergistic effect, it is also possible to contribute to further thinning of the polarizing plate with a retardation layer. It should be noted that such an iodine permeation inhibition layer can also have an effect of significantly suppressing the corrosion of metal components (such as electrodes, sensors, wirings, metal layers) of the image display device.

[0054] As Figure 2As shown, in the polarizing plate 102 with a phase difference layer according to another embodiment, another phase difference layer 50 and / or a conductive layer or an isotropic substrate with a conductive layer 60 may also be provided. The other phase difference layer 50 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 relationship of nz > nx = ny. The conductive layer or the isotropic substrate with a conductive layer 60 is typically provided between the iodine permeation inhibiting layer 40 and the adhesive layer 30 (i.e., outside the iodine permeation inhibiting layer 40). The other phase difference layer 50 and the conductive layer or the isotropic substrate with a conductive layer 60 are typically provided in sequence starting from the side of the phase difference layer 20. In the illustrated example, the iodine permeation inhibiting layer 40, the phase difference layer 20, the other phase difference layer 50, and the conductive layer or the isotropic substrate with a conductive layer 60 are provided in sequence from the visually recognizable side. However, as long as the other phase difference layer 50 is provided between the phase difference layer 20 and the adhesive layer 30, and the conductive layer or the isotropic substrate with a conductive layer 60 is provided between the iodine permeation inhibiting layer 40 and the adhesive layer 30, any appropriate arrangement order may be adopted. The other phase difference layer 50 and the conductive layer or the isotropic substrate with a conductive layer 60 are typically arbitrary layers provided as needed, and either one or both of them may be omitted. It should be noted that, for convenience, the phase difference layer 20 is sometimes referred to as the first phase difference layer, and the other phase difference layer 50 is referred to as the second phase difference layer. When providing a conductive layer or an isotropic substrate with a conductive layer, the polarizing plate with a phase difference layer can be applied to a so-called in-cell touch panel type input display device in which a touch sensor is incorporated between an image display unit (e.g., an organic EL unit) and the polarizing plate. In the embodiment of the present invention, by providing the conductive layer or the isotropic substrate with a conductive layer 60 outside the iodine permeation inhibiting layer 40, corrosion of the conductive layer can be significantly suppressed.

[0055] As described above, the first phase difference layer 20 is a liquid crystal alignment cured layer. The first phase difference layer 20 may be a single layer as shown in Figure 1A , Figure 1B and Figure 2 or may have a laminated structure of a first liquid crystal alignment cured layer 21 and a second liquid crystal alignment cured layer 22 as shown in Figure 3 .

[0056] The above embodiments may be appropriately combined, and obvious changes in the industry may also be added to the constituent elements of the above embodiments. For example, a second phase difference layer 50 and / or a conductive layer or an isotropic substrate with a conductive layer 60 may be provided on the polarizing plate 101 with a phase difference layer of Figure 1B ; the phase difference layer 20 of the polarizing plate 101 with a phase difference layer of Figure 1B may also have a two-layer structure as shown in Figure 3 ; a second phase difference layer 50 and / or a conductive layer or an isotropic substrate with a conductive layer 60 may be provided on the polarizing plate 101 with a phase difference layer of Figure 3A second retardation layer 50 and / or a conductive layer or an isotropic substrate with a conductive layer is / are provided on the polarizing plate 103 with a retardation layer; Figure 2 The iodine permeation inhibiting layer 40 of the polarizing plate 102 with a retardation layer may also be provided between the retardation layer 20 and the conductive layer or the isotropic substrate with a conductive layer 60.

[0057] The polarizing plate with a retardation layer according to an embodiment of the present invention may further include other retardation layers. The optical properties (e.g., refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the other retardation layers may be appropriately set according to the purpose.

[0058] The polarizing plate with a retardation layer according to an embodiment of the present invention may be in a single sheet form or in a long strip form. As used in this specification, the term "long strip form" refers to an elongated shape that is sufficiently long relative to the width, for example, including an elongated shape with a length that is 10 times or more, preferably 20 times or more, relative to the width. The polarizing plate with a retardation layer in a long strip form can be wound into a roll.

[0059] The total thickness of the polarizing plate with a retardation layer is preferably 60 μm or less, more preferably 55 μm or less, further preferably 50 μm or less, and particularly preferably 40 μm or less. The lower limit of the total thickness may be, for example, 28 μm. According to an embodiment of the present invention, such an extremely thin polarizing plate with a retardation layer can be achieved. Furthermore, even when such an extremely thin polarizing plate with a retardation layer is applied to an image display device, a decrease in reliability caused by iodine in a high-temperature and high-humidity environment can be suppressed, and thus an increase in reflectance can be suppressed. Furthermore, corrosion of metal components (e.g., electrodes, sensors, wirings, metal layers) of the image display device can be significantly suppressed. In addition, such a polarizing plate with a retardation layer can have extremely excellent flexibility and bending durability. Therefore, such a polarizing plate with a retardation layer is particularly suitable for application to a curved image display device and / or a foldable or bendable image display device. It should be noted that the total thickness of the polarizing plate with a retardation layer refers to the sum of the thicknesses of the polarizing plate, the retardation layer (the first retardation layer and the second retardation layer when the second retardation layer exists), the iodine permeation inhibiting layer, and the adhesive layer or bonding agent layer used for laminating them (i.e., the total thickness of the polarizing plate with a retardation layer does not include the thickness of the conductive layer or the isotropic substrate with a conductive layer 60, as well as the adhesive layer 30 and the release film that can be temporarily adhered to its surface).

[0060] In practical applications, it is preferable to temporarily adhere a release film to the surface of the adhesive layer 30 until the polarizing plate with a retardation layer is put into use. By temporarily adhering the release film, a roll of the polarizing plate with a retardation layer can be formed while protecting the adhesive layer.

[0061] The constituent elements of the polarizing plate with a phase difference layer will be described in more detail below. It should be noted that, regarding the adhesive layer 30, a well-known configuration in the industry can be adopted, and thus the description of the detailed configuration of the adhesive layer is omitted.

[0062] B. Polarizing plate

[0063] B-1. Polarizing element

[0064] Typically, the polarizing element is composed of a polyvinyl alcohol (PVA)-based resin film containing a dichroic substance. The thickness of the polarizing element is preferably 1 μm to 8 μm, more preferably 1 μm to 7 μm, and further preferably 2 μm to 5 μm. As long as the thickness of the polarizing element is within such a range, it can contribute significantly to the thinning of the polarizing plate with a phase difference layer. Furthermore, in the thin polarizing plate with a phase difference layer using such a polarizing element, the effects of the present invention are remarkable.

[0065] The boric acid content of the polarizing element is preferably 10% by weight or more, more preferably 13% to 25% by weight. As long as the boric acid content of the polarizing element is within such a range, the ease of curl adjustment during bonding can be well maintained and the curl during heating can be well suppressed through the synergistic effect with the iodine content described below, while improving the appearance durability during heating. The boric acid content can be calculated, for example, by the neutralization method in the form of the amount of boric acid contained per unit weight of the polarizing element using the following formula.

[0066]

[0067] The iodine content of the polarizing element is preferably 2% by weight or more, more preferably 2% to 10% by weight. When the iodine content of the polarizing element is within such a range, through the synergistic effect with the above-mentioned boric acid content, the ease of curl adjustment during bonding can be well maintained, the curl during heating can be well suppressed, and the appearance durability during heating can be improved. In this specification, the "iodine content" refers to the total amount of iodine contained in the polarizing element (PVA-based resin film). More specifically, in the polarizing element, iodine exists in the forms of iodide ions (I - ), iodine molecules (I2), polyiodide ions (I3 - , I5 - ), etc. In this specification, the iodine content refers to the amount of iodine containing all these forms. The iodine content can be calculated, for example, by the standard curve method of fluorescent X-ray analysis. It should be noted that polyiodide ions exist in the polarizing element in a state of forming a PVA-iodine complex. By forming such a complex, dichroic absorption will be exhibited in the visible light wavelength range. Specifically, the complex of PVA and triiodide ions (PVA·I3 - ) has an absorption peak near 470 nm, and the complex of PVA and pentaiodide ions (PVA·I5 -) has an absorption peak near 600 nm. As a result, polyiodide ions can absorb light in a wide range of visible light depending on their form. On the other hand, iodide ions (I - ) have an absorption peak near 230 nm and substantially do not interfere with the absorption of visible light. Therefore, polyiodide ions present in the form of a complex with PVA mainly interfere with the absorption performance of the polarizing element.

[0068] The polarizing element preferably exhibits absorption dichroism at any wavelength in the wavelength range of 380 nm to 780 nm. The monomer transmittance Ts of the polarizing element is preferably 40% to 48%, more preferably 41% to 46%. The degree of polarization P of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more. The above monomer transmittance is typically the Y value obtained by measuring with a UV-visible spectrophotometer and performing visual sensitivity correction. The above degree of polarization is typically calculated by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc obtained by measuring with a UV-visible spectrophotometer and performing visual sensitivity correction.

[0069] Degree of polarization (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100

[0070] The polarizing element is typically made of two or more stacked layers. As a specific example of a polarizing element obtained using a stacked body, a polarizing element obtained using a stacked body of a resin substrate and a PVA-based resin layer coated on the resin substrate can be cited. A polarizing element obtained using a stacked body of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, as follows: A PVA-based resin solution is coated on the resin substrate and dried to form a PVA-based resin layer on the resin substrate, thereby obtaining a stacked body of the resin substrate and the PVA-based resin layer; the stacked body is stretched and dyed to form the PVA-based resin layer into a polarizing element. Stretching typically includes immersing the stacked body in a boric acid aqueous solution and stretching. Further, if necessary, stretching may further include air stretching the stacked body at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. The obtained stacked body of the resin substrate / polarizing element can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizing element), or the resin substrate can be peeled off from the stacked body of the resin substrate / polarizing element and any appropriate protective layer can be laminated on the peeled surface for use according to the purpose. The detailed content of such a method for manufacturing a polarizing element is described, for example, in Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire disclosures of these publications are incorporated herein by reference.

[0071] Typical methods for manufacturing polarizing elements include: forming a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of a long strip-shaped thermoplastic resin substrate to form a laminate; and successively performing an air-assisted stretching treatment, a dyeing treatment, a water stretching treatment, and a drying shrinkage treatment on the laminate. The drying shrinkage treatment is carried out by heating while conveying the laminate in the longitudinal direction, causing it to shrink by 2% or more in the width direction. Thus, a very thin polarizing element with excellent optical properties and suppressed non-uniformity of optical properties can be provided. That is, by introducing assisted stretching, the crystallinity of PVA can be improved even when PVA is coated on a thermoplastic resin, achieving high optical properties. In addition, by simultaneously improving the orientation of PVA in advance, problems such as a decrease in the orientation of PVA or dissolution when immersed in water during subsequent dyeing and stretching processes can be prevented, achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared with the case where the PVA-based resin layer does not contain a halide, the orientation disorder of polyvinyl alcohol molecules and the decrease in orientation can be suppressed. Thus, the optical properties of the polarizing element obtained through processing steps such as dyeing treatment and water stretching treatment by immersing the laminate in a liquid can be improved. Furthermore, by performing a drying shrinkage treatment to shrink the laminate in the width direction, the optical properties can be improved.

[0072] B-2. Protective layer

[0073] The protective layer 12 is formed of any suitable thin film that can be used as a protective layer of the polarizing element. Specific examples of the material that is the main component of this thin film include cellulose-based resins such as cellulose triacetate (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, acetate-based, and other transparent resins. In addition, thermosetting resins or ultraviolet curable resins such as (meth)acrylic-based, urethane-based, (meth)acrylic urethane-based, epoxy-based, and silicone-based resins can also be mentioned. Furthermore, for example, glassy polymers such as siloxane-based polymers can also be mentioned. In addition, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01 / 37007) can also be used. As the material of this thin film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used. For example, a resin composition having an alternating copolymer formed from isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. This polymer film can be, for example, an extruded product of the above resin composition.

[0074] The polarizing plate with a phase difference layer is typically disposed on the visual recognition side of the image display device as described later, and the protective layer 12 is typically disposed on its visual recognition side. Therefore, the protective layer 12 can also be subjected to surface treatments such as hard coating treatment, antireflection treatment, antiadhesion treatment, antiglare treatment, etc. as needed. Further / alternatively, the protective layer 12 can also be subjected to a treatment for improving the visual recognition when visually recognizing through polarized sunglasses (typically, imparting an (elliptical) circular polarization function, imparting an ultrahigh phase difference) as needed. By performing such a treatment, excellent visual recognition can still be achieved even when visually recognizing the display screen through a polarizing lens such as polarized sunglasses. Therefore, the polarizing plate with a phase difference layer can also be suitably used for an image display device that can be used outdoors.

[0075] The thickness of the protective layer is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm. It should be noted that when the surface treatment is performed, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

[0076] C. First phase difference layer

[0077] The first phase difference layer 20 is a liquid crystal alignment cured layer as described above. By using a liquid crystal compound, the difference between nx and ny of the obtained phase difference layer can be made significantly larger than that of a non-liquid crystal material, so that the thickness of the phase difference layer used to obtain the desired in-plane phase difference can be made significantly smaller. As a result, further thinning of the polarizing plate with a phase difference layer can be achieved. In this specification, the so-called "liquid crystal alignment cured layer" refers to a layer in which a liquid crystal compound is aligned in a specified direction in the layer and its alignment state is fixed. It should be noted that the "alignment cured layer" is a concept including the alignment cured layer obtained by curing a liquid crystal monomer as described later. In this embodiment, typically, the rod-shaped liquid crystal compound is aligned in a state of being arranged along the slow axis direction of the first phase difference layer (parallel alignment).

[0078] Examples of the liquid crystal compound include liquid crystal compounds having a nematic liquid crystal phase (nematic liquid crystals). As such liquid crystal compounds, for example, liquid crystal polymers and liquid crystal monomers can be used. The mechanism for expressing the liquid crystallinity of the liquid crystal compound can be lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer can be used alone or in combination.

[0079] 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 by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer, the alignment state of the liquid crystal monomer can be fixed. After aligning the liquid crystal monomers, for example, when the liquid crystal monomers are polymerized or crosslinked with each other, the above alignment state can be fixed thereby. Here, a polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the formed first retardation layer, for example, does not exhibit the situation where the liquid crystal compound is transformed into a liquid crystal phase, a glass phase, or a crystal phase due to temperature changes. As a result, the first retardation layer becomes a retardation layer with extremely excellent stability that is not affected by temperature changes.

[0080] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, this temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

[0081] As the above liquid crystal monomer, any suitable liquid crystal monomer can be used. For example, polymerizable liquid crystal precursor compounds described in Japanese Patent Application Laid-Open No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. As specific examples of such polymerizable liquid crystal precursor compounds, for example, the product name LC242 of BASF, the product name E7 of Merck, and the product name LC-Sillicon-CC3767 of Wacker-Chem can be cited. As the liquid crystal monomer, a nematic liquid crystal monomer is preferably used, for example.

[0082] The liquid crystal alignment cured layer can be formed as follows: An alignment treatment is performed on the surface of a specified substrate, and a coating liquid containing a liquid crystal compound is coated on this surface to align the liquid crystal compound in a direction corresponding to the above alignment treatment, and the alignment state is fixed, thereby forming the layer. In one embodiment, the substrate is any suitable resin film, and the liquid crystal alignment cured layer formed on this substrate can be transferred to the surface of an adjacent layer (for example, a polarizer, an iodine permeation inhibition layer).

[0083] As the above alignment treatment, any suitable alignment treatment can be used. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be cited. As specific examples of mechanical alignment treatment, rubbing treatment and stretching treatment can be cited. As specific examples of physical alignment treatment, magnetic field alignment treatment and electric field alignment treatment can be cited. As specific examples of chemical alignment treatment, oblique evaporation method and photoalignment treatment can be cited. The treatment conditions for various alignment treatments can be any suitable conditions according to the purpose.

[0084] The alignment of the liquid crystal compound can be carried out by treatment at a temperature at which the liquid crystal phase is exhibited, depending on the type of the liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound becomes a liquid crystal state and is aligned corresponding to the alignment treatment direction of the substrate surface.

[0085] In one embodiment, the fixation of the alignment state is carried out by cooling the liquid crystal compound that has been aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the fixation of the alignment state is carried out by performing a polymerization treatment or a crosslinking treatment on the liquid crystal compound that has been aligned as described above.

[0086] Specific examples of the liquid crystal compound and details of the method for forming the alignment curing layer are described in Japanese Patent Laid-Open No. 2006-163343. The description of this publication is incorporated herein by reference.

[0087] In one embodiment, the first retardation layer 20 is a single layer as Figure 1A , Figure 1B and Figure 2 shown. When the first 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 at a thickness significantly thinner than that of the resin film.

[0088] The first retardation layer has a circular polarization function or an elliptical polarization function as described above. The first retardation layer typically shows a refractive index characteristic of nx > ny = nz. The first retardation layer is typically provided to impart an antireflection characteristic to a polarizing plate, and when the first retardation layer is a single layer, it can function as a λ / 4 plate. At this time, the in-plane retardation Re(550) of the first retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and further preferably 130 nm to 160 nm. It should be noted that 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, there may be cases where ny > nz or ny < nz within the range that does not impair the effects of the present invention.

[0089] The Nz coefficient of the first 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 the obtained retardation layer is used in an image display device, a very excellent reflected hue can be achieved.

[0090] The first retardation layer can exhibit an anomalous dispersion wavelength characteristic in which the phase difference increases with the wavelength of the measurement light, a normal wavelength dispersion characteristic in which the phase difference decreases with the wavelength of the measurement light, and a flat wavelength dispersion characteristic in which the phase difference hardly changes with the wavelength of the measurement light. In one embodiment, the first retardation layer exhibits an anomalous dispersion wavelength characteristic. At this time, 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 antireflection characteristics can be achieved.

[0091] The angle θ formed by the slow axis of the first retardation layer 20 and the absorption axis of the polarizing member 11 is preferably 40° to 50°, more preferably 42° to 48°, and further preferably about 45°. As long as the angle θ is within such a range, by forming the first retardation layer into a λ / 4 plate as described above, a polarizing plate with a retardation layer having very excellent circular polarization characteristics (resulting in very excellent antireflection characteristics) can be obtained.

[0092] In another embodiment, the first retardation layer 20 is as Figure 3As shown, there is a laminated structure having a first liquid crystal alignment cured layer 21 and a second liquid crystal alignment cured layer 22. At this time, either the first liquid crystal alignment cured layer 21 or the second liquid crystal alignment cured layer 22 can function as a λ / 4 plate, and the other can function as a λ / 2 plate. Therefore, the thicknesses of the first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22 can be adjusted in such a way as to obtain a desired in-plane phase difference of a λ / 4 plate or a λ / 2 plate. For example, when the first liquid crystal alignment cured layer 21 functions as a λ / 2 plate and the second liquid crystal alignment cured layer 22 functions as a λ / 4 plate, the thickness of the first liquid crystal alignment cured layer 21 is, for example, 2.0 μm to 3.0 μm, and the thickness of the second liquid crystal alignment cured layer 22 is, for example, 1.0 μm to 2.0 μm. At this time, the in-plane phase difference Re(550) of the first liquid crystal alignment cured layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and further preferably 250 nm to 280 nm. The in-plane phase difference Re(550) of the second liquid crystal alignment cured layer is as described above for a single layer. The angle formed by the slow axis of the first liquid crystal alignment cured layer and the absorption axis of the polarizing member is preferably 10° to 20°, more preferably 12° to 18°, and further preferably about 15°. The angle formed by the slow axis of the second liquid crystal alignment cured layer and the absorption axis of the polarizing member is preferably 70° to 80°, more preferably 72° to 78°, and further preferably about 75°. As long as it has such a configuration, a characteristic close to an ideal anomalous wavelength dispersion characteristic can be obtained, and as a result, a very excellent antireflection characteristic can be achieved. Regarding the liquid crystal compound constituting the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer, the formation method of the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer, the optical characteristics, etc., they are as described above for a single layer.

[0093] D. Iodine Permeation Inhibiting Layer

[0094] Iodine permeation inhibition layer As described above, the iodine absorption index is 0.015 or less. The iodine absorption index is preferably 0.012 or less, more preferably 0.009 or less, still more preferably 0.007 or less, and particularly preferably 0.005 or less. The smaller the iodine absorption index, the more preferable, and ideally it is zero, and its lower limit can be, for example, 0.001. The iodine absorption index is an index of the iodine permeation inhibition ability of the iodine permeation inhibition layer, and the smaller this index, the more difficult it is for iodine to be absorbed by the iodine permeation inhibition layer (that is, iodine is easily blocked by the iodine permeation inhibition layer). Therefore, as long as the iodine absorption index is within such a range, when the polarizing plate with a phase difference layer is applied to an image display device, the movement of iodine in the polarizing member to the image display device (substantially the image display unit) can be significantly suppressed. As a result, when the polarizing plate with a phase difference layer is applied to an image display device, a decrease in reliability caused by iodine in a high-temperature and high-humidity environment can be suppressed, and thus an increase in reflectance can be suppressed. Furthermore, as described above, for the iodine permeation inhibition layer, the potassium absorption index is preferably 0.015 or less. The potassium absorption index is more preferably 0.013 or less, still more preferably 0.011 or less, and particularly preferably 0.009 or less. The smaller the potassium absorption index, the more preferable, and ideally it is zero, and its lower limit can be, for example, 0.002. The potassium absorption index is an index of the potassium permeation inhibition ability of the iodine permeation inhibition layer, and the smaller this index, the less likely potassium is to be absorbed by the iodine permeation inhibition layer. As a result, iodine in the form of potassium iodide and iodine in the form of polyiodide (I3 - K + ) are less likely to be absorbed by the iodine permeation inhibition layer. Therefore, as long as the potassium absorption index is within such a range, the movement of iodine can be suppressed not only in the form of elemental iodine but also in the forms of potassium iodide and polyiodide. The iodine absorption index can be defined as the iodine intensity (kcps) obtained by fluorescent X-ray analysis of the iodine permeation inhibition layer, and the potassium absorption index can be defined as the potassium intensity (kcps) obtained by fluorescent X-ray analysis of the iodine permeation inhibition layer.

[0095] Typically, the iodine permeation inhibiting layer is a solidified product or a thermoset product of a coating film of an organic solvent solution of a resin. As long as it has such a structure, the thickness can be made very thin (for example, 10 μm or less). The thickness of the iodine permeation inhibiting layer is preferably 0.05 μm to 10 μm, more preferably 0.08 μm to 5 μm, still more preferably 0.1 μm to 1 μm, and particularly preferably 0.2 μm to 0.7 μm. Furthermore, as long as it has such a structure, the iodine permeation inhibiting layer can be formed directly (i.e., without using an adhesive layer or a binder layer) on an adjacent layer (for example, a polarizer, a retardation layer). According to an embodiment of the present invention, as described above, the polarizer, the retardation layer, and the iodine permeation inhibiting layer are very thin, and the adhesive layer or the binder for laminating the iodine permeation inhibiting layer can be omitted. Therefore, the total thickness of the polarizing plate with a retardation layer can be made extremely thin. Furthermore, since the hygroscopicity and moisture permeability of such an iodine permeation inhibiting layer are smaller than those of a solidified product of an aqueous coating film such as an aqueous solution or an aqueous dispersion, it has the advantage of excellent humidity resistance. As a result, a polarizing plate with a retardation layer having excellent durability that can maintain optical properties even in a high-temperature and high-humidity environment can be achieved. In addition, such an iodine permeation inhibiting layer can, for example, suppress the adverse effects of ultraviolet irradiation on the polarizing plate (polarizer) compared with a cured product of an ultraviolet curable resin. The iodine permeation inhibiting layer is preferably a solidified product of a coating film of an organic solvent solution of a resin. The solidified product has less shrinkage during thin film formation and does not contain residual monomers, etc. compared with the cured product. Therefore, deterioration of the thin film itself can be suppressed, and adverse effects of residual monomers, etc. on the polarizing plate (polarizer) can be suppressed.

[0096] Furthermore, the glass transition temperature (Tg) of the resin constituting the iodine permeation inhibiting layer is, for example, 85°C or higher, and the weight average molecular weight Mw is, for example, 25,000 or higher. As long as the Tg and Mw of the resin are within such ranges, due to the synergistic effect with the effect brought about by forming the iodine permeation inhibiting layer with a solidified product or a thermoset product of a coating film of an organic solvent solution of a resin, even if it is very thin, the movement of iodine in the polarizer to the image display unit can be significantly suppressed. As a result, when the polarizing plate with a retardation layer is applied to an image display device, a decrease in reliability caused by iodine in a high-temperature and high-humidity environment can be suppressed, and thus an increase in reflectance can be suppressed. Furthermore, corrosion of metal components can be significantly suppressed. The Tg of the resin is preferably 90°C or higher, more preferably 100°C or higher, still more preferably 110°C or higher, and particularly preferably 120°C or higher. The upper limit of Tg can be, for example, 200°C. In addition, the Mw of the resin is preferably 30,000 or higher, more preferably 35,000 or higher, still more preferably 40,000 or higher. The upper limit of Mw can be, for example, 150,000.

[0097] As the resin constituting the iodine permeation inhibiting layer, any suitable thermoplastic resin or thermosetting resin can be used as long as it can form a solidified product or a thermoset of a coating film in an organic solvent solution and has the above-described Tg and Mw. A thermoplastic resin is preferred. Examples of the thermoplastic resin include acrylic resins and epoxy resins. An acrylic resin and an epoxy resin may also be used in combination. Representative examples of the acrylic resin and the epoxy resin that can be used for the iodine permeation inhibiting layer are described below.

[0098] Typically, the acrylic resin contains, as a main component, repeating units derived from (meth)acrylate monomers having a linear or branched structure. In this specification, (meth)acrylic acid means acrylic acid and / or methacrylic acid. The acrylic resin may contain repeating units derived from any suitable comonomer used according to the purpose. Examples of the comonomer include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, an aromatic ring-containing (meth)acrylate, and a heterocyclic ring-containing vinyl monomer. By appropriately setting the type, amount, combination, and copolymerization ratio of the monomer units, an acrylic resin having the above-specified Mw can be obtained.

[0099] <Boron-containing acrylic resin>

[0100] In one embodiment of the acrylic resin, it contains a copolymer obtained by polymerizing the following monomer mixture (hereinafter sometimes referred to as a boron-containing acrylic resin), the monomer mixture containing more than 50 parts by weight of a (meth)acrylate monomer and more than 0 part by weight and less than 50 parts by weight of a monomer represented by the formula (1) (hereinafter sometimes referred to as a comonomer).

[0101]

[0102] (In the formula, X represents a functional group containing a reactive group, the reactive group being at least one reactive group selected from the group consisting of a vinyl group, a (meth)acryloyl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group, R 1 and R 2 each independently represent a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aryl group, or an optionally substituted heterocyclic group, R 1 and R 2 optionally connect to each other to form a ring).

[0103] The boron-containing acrylic resin typically has a repeating unit represented by the following formula. By polymerizing a monomer mixture containing the comonomer represented by formula (1) and a (meth)acrylic monomer, the boron-containing acrylic resin has a boron-containing substituent (e.g., the repeating unit of k in the following formula) in the side chain. Thus, when the iodine permeation inhibition layer is disposed adjacent to the polarizer, the adhesion to the polarizer is improved. The boron-containing substituent may be contained continuously (i.e., in a block form) in the boron-containing acrylic resin or may be contained randomly in the boron-containing acrylic resin.

[0104]

[0105] (In the formula, R 6 represents an arbitrary functional group, and j and k represent integers of 1 or more).

[0106] <(Meth)acrylic monomer>

[0107] As the (meth)acrylic monomer, any suitable (meth)acrylic monomer can be used. For example, (meth)acrylate monomers having a linear or branched structure and (meth)acrylate monomers having a cyclic structure can be cited.

[0108] As the (meth)acrylate monomer having a linear or branched structure, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl methyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. can be cited. Methyl (meth)acrylate is preferably used. Only one kind of (meth)acrylate monomer can be used, or two or more kinds can be used in combination.

[0109] As (meth)acrylate monomers having a cyclic structure, for example, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyloxyethoxyethyl (meth)acrylate, dicyclopentyl (meth)acrylate, biphenyl (meth)acrylate, o-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethoxyethyl (meth)acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth)acrylate, o-biphenyloxy-2-hydroxypropyl (meth)acrylate, p-biphenyloxy-2-hydroxypropyl (meth)acrylate, m-biphenyloxy-2-hydroxypropyl (meth)acrylate, N-(meth)acryloyloxyethyl-o-biphenylcarbamate, N-(meth)acryloyloxyethyl-p-biphenylcarbamate, N-(meth)acryloyloxyethyl-m-biphenylcarbamate, monomers containing a biphenyl group such as o-phenylphenol glycidyl ether acrylate, terphenyl (meth)acrylate, o-terphenyl oxyethyl (meth)acrylate, etc. are exemplified. It is preferable to use 1-adamantyl (meth)acrylate and dicyclopentyl (meth)acrylate. By using these monomers, a polymer having a high glass transition temperature can be obtained. These monomers may be used alone or in combination of two or more.

[0110] In addition, a silsesquioxane compound having a (meth)acryloyl group can be used instead of the above-mentioned (meth)acrylate monomer. By using the silsesquioxane compound, an acrylic polymer having a high glass transition temperature can be obtained. Silsesquioxane compounds having various skeletal structures such as a cage structure, a ladder structure, and a random structure are known. The silsesquioxane compound may have only one of these structures or may have two or more. The silsesquioxane compound may be used alone or in combination of two or more.

[0111] As the silsesquioxane compound containing a (meth)acryloyl group, for example, the MAC grade and the AC grade of the SQ series of Toagosei Co., Ltd. can be used. The MAC grade is a silsesquioxane compound containing a methacryloyl group. Specifically, for example, MAC-SQ TM-100, MAC-SQ SI-20, MAC-SQ HDM, etc. can be exemplified. The AC grade is a silsesquioxane compound containing an acryloyl group. Specifically, for example, AC-SQ TA-100, AC-SQ SI-20, etc. can be exemplified.

[0112] (Meth)acrylate monomers are used in an amount of more than 50 parts by weight relative to 100 parts by weight of the monomer mixture.

[0113] <Copolymer monomer>

[0114] As a comonomer, the monomer represented by the above formula (1) is used. By using such a comonomer, a substituent containing boron is introduced into the side chain of the resulting polymer. Only one kind of comonomer can be used, or two or more kinds can be used in combination.

[0115] Examples of the aliphatic hydrocarbon group in the above formula (1) include a linear or branched alkyl group having 1 to 20 carbon atoms optionally having a substituent, a cyclic alkyl group having 3 to 20 carbon atoms optionally having a substituent, and an alkenyl group having 2 to 20 carbon atoms. Examples of the aryl group include a phenyl group having 6 to 20 carbon atoms optionally having a substituent, a naphthyl group having 10 to 20 carbon atoms optionally having a substituent, and the like. Examples of the heterocyclic group include a 5-membered ring group or a 6-membered ring group containing at least one heteroatom optionally having a substituent. It should be noted that R 1 and R 2 optionally connect to each other to form a ring. R 1 and R 2 are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom.

[0116] The reactive group contained in the functional group represented by X is at least one selected from the group consisting of a vinyl group, a (meth)acryloyl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group. The preferred reactive group is a (meth)acryloyl group and / or a (meth)acrylamide group. By having these reactive groups, when the iodine permeation inhibiting layer is disposed adjacent to the polarizing member, the adhesion to the polarizing member is further improved.

[0117] In one embodiment, the functional group represented by X is preferably a functional group represented by Z-Y-. Here, Z represents a functional group containing at least one reactive group selected from the group consisting of a vinyl group, a (meth)acryloyl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group, and Y represents a phenylene group or an alkylene group.

[0118] Specifically, the following compounds can be used as the comonomer.

[0119]

[0120]

[0121] The comonomer is used in an amount greater than 0 parts by weight and less than 50 parts by weight relative to 100 parts by weight of the monomer mixture. It is preferably 0.01 parts by weight or more and less than 50 parts by weight, more preferably 0.05 parts by weight to 20 parts by weight, still more preferably 0.1 parts by weight to 10 parts by weight, and particularly preferably 0.5 parts by weight to 5 parts by weight.

[0122] <Acrylic resin containing a lactone ring, etc.>

[0123] In another embodiment, the acrylic resin has a repeating unit containing a ring structure selected from a lactone ring unit, a glutaric anhydride unit, a succinimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. In the repeating unit of the acrylic resin, only one kind of repeating unit containing a ring structure may be included, or two or more kinds may be included.

[0124] The lactone ring unit is preferably represented by the following general formula (2):

[0125]

[0126] In general formula (2), R 2 , R 3 and R 4 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. It should be noted that the organic residue may also contain an oxygen atom. The acrylic resin may contain only a single lactone ring unit, or may contain various lactone ring units in which R 2 , R 3 and R 4 in the above general formula (2) are different. The acrylic resin having a lactone ring unit has been described in, for example, Japanese Patent Application Laid-Open No. 2008-181078, and the description of this publication is incorporated herein by reference.

[0127] The succinimide unit is preferably represented by the following general formula (3):

[0128]

[0129] In general formula (3), R 11 and R 12 each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R 13 represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. In general formula (3), preferably, R 11 and R 12 are each independently hydrogen or methyl, and R 13 is hydrogen, methyl, butyl, or cyclohexyl. More preferably, R 11 is methyl, R 12 is hydrogen, and R 13 is methyl. The acrylic resin may contain only a single succinimide unit, or may contain R 11 , R 12 and R 13Various different glutarimide units. Acrylic resins having glutarimide units are described, for example, in JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492, JP-A-2006-337493, and JP-A-2006-337569, the disclosures of which are incorporated herein by reference. It should be noted that, regarding the glutaric anhydride unit, except that the nitrogen atom substituted by R in the above general formula (3) is an oxygen atom, the above description of the glutarimide unit is applicable. 13 Regarding the glutarimide unit, the above description is applicable except that the nitrogen atom substituted by R in the above general formula (3) is an oxygen atom.

[0130] Regarding the maleic anhydride unit and the maleimide (N-substituted maleimide) unit, the structure is determined by the name, and thus specific description is omitted.

[0131] The content ratio of the repeating unit containing a ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, and still more preferably 20 mol% to 30 mol%. It should be noted that the acrylic resin contains a repeating unit derived from the above-mentioned (meth)acrylic monomer as the main repeating unit.

[0132] <Epoxy resin>

[0133] As the epoxy resin, an epoxy resin having an aromatic ring is preferably used. By using an epoxy resin having an aromatic ring as the epoxy resin, when the iodine permeation inhibiting layer is disposed adjacent to the polarizing member, the adhesion to the polarizing member can be improved. Further, when the adhesive layer is disposed adjacent to the iodine permeation inhibiting layer, the anchoring force of the adhesive layer can be improved. Examples of the epoxy resin having an aromatic ring include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins and other bisphenol type epoxy resins; novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, hydroxybenzaldehyde phenol novolak varnish epoxy resin; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, epoxidized polyethylene phenol, naphthol type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins. Bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin are preferably used. The epoxy resin may be used alone or in combination of two or more.

[0134] The iodine permeation inhibiting layer can be formed by coating a coating film with an organic solvent solution of the resin as described above and solidifying or thermosetting the coating film. As the organic solvent, any suitable organic solvent capable of dissolving or uniformly dispersing the acrylic resin can be used. Specific examples of the organic solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone. The resin concentration of the solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. As long as the resin concentration is such, a uniform coating film can be formed.

[0135] The solution can be coated on any suitable substrate or on an adjacent layer (e.g., a polarizer, a retardation layer). When the solution is coated on the substrate, the solidified product (iodine permeation inhibiting layer) of the coating film formed on the substrate is transferred onto the adjacent layer. When the solution is coated on the adjacent layer, a protective layer is directly formed on the adjacent layer by drying (solidifying) the coating film. It is preferred that the solution is coated on the adjacent layer to directly form a protective layer on the adjacent layer. With such a configuration, the adhesive layer or binder layer required for transfer can be omitted, and thus, the polarizing plate with a retardation layer can be made thinner. As a coating method of the solution, any suitable method can be adopted. Specific examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, knife coating (comma coating, etc.).

[0136] The iodine permeation inhibiting layer can be formed by solidifying or thermosetting the coating film of the solution. The heating temperature for solidification or thermosetting is preferably 100 °C or lower, more preferably 50 °C to 70 °C. As long as the heating temperature is within such a range, adverse effects on the polarizer can be prevented. The heating time can vary according to the heating temperature. The heating time can be, for example, 1 minute to 10 minutes.

[0137] The iodine permeation inhibiting layer (substantially the organic solvent solution of the above resin) can contain any suitable additives according to the purpose. Specific examples of the additives include ultraviolet absorbers; leveling agents; antioxidants such as hindered phenol-based, phosphorus-based, and sulfur-based antioxidants; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxides; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers, inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants; etc. The type, quantity, combination, addition amount, etc. of the additives can be appropriately set according to the purpose.

[0138] E. Second Retardation Layer

[0139] As described above, the second retardation layer can be a so-called positive C-plate having a refractive index characteristic of nz > nx = ny. By using a positive C-plate as the second retardation layer, obliquely incident reflections can be well prevented, and the anti-reflection function can be made wide-angle. At this time, the retardation Rth(550) in the thickness direction of the second retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, still 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 second retardation layer can be less than 10 nm.

[0140] The second retardation layer having a refractive index characteristic of nz > nx = ny can be formed of any suitable material. The second retardation layer is preferably formed of a thin film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented can be a liquid crystal monomer or a liquid crystal polymer. As a specific example of the liquid crystal compound and the method for forming the retardation layer, the liquid crystal compound and the method for forming the retardation layer described in paragraphs

[0020] to

[0028] of Japanese Patent Application Laid-Open No. 2002-333642 can be cited. At this time, the thickness of the second retardation layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, still more preferably 0.5 μm to 5 μm.

[0141] F. Conductive layer or isotropic substrate with a conductive layer

[0142] The conductive layer can be formed by depositing a metal oxide film on any suitable substrate using any suitable film-forming method (for example, vacuum evaporation, sputtering, CVD, ion plating, spraying, etc.). Examples of the metal oxide 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 them, indium tin composite oxide (ITO) is preferred.

[0143] 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.

[0144] The conductive layer can be transferred from the above-mentioned substrate to the first retardation layer (or the iodine permeation inhibition layer or the second retardation layer when there is a second retardation layer), and the conductive layer itself can be used as a constituent layer of a polarizing plate with a retardation layer. Alternatively, it can be laminated on the first retardation layer (or the iodine permeation inhibition layer or the second retardation layer when there is a second retardation layer) in the form of a laminate with the substrate (substrate with a conductive layer). Preferably, the above-mentioned substrate is optically isotropic. Therefore, the conductive layer can be used as an isotropic substrate with a conductive layer for a polarizing plate with a retardation layer.

[0145] As an optically isotropic substrate (isotropic substrate), any suitable isotropic substrate can be used. As materials constituting the isotropic substrate, for example, materials having a main skeleton of a resin without a conjugated system such as a norbornene-based resin or an olefin-based resin, and materials having a cyclic structure such as a lactone ring or a glutarimide ring in the main chain of an acrylic resin can be cited. If such materials are used, the retardation caused by molecular chain orientation can be suppressed to a small value when forming the isotropic substrate. 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.

[0146] The conductive layer and / or the conductive layer of the isotropic substrate with a conductive layer can be patterned as needed. By patterning, a conductive portion and an insulating portion can be formed. As a result, an electrode can be formed. The electrode can function as a touch sensor electrode for detecting contact with a touch panel. As a patterning method, any suitable method can be adopted. As a specific example of the patterning method, a wet etching method and a screen printing method can be cited.

[0147] G. Image display device

[0148] The polarizing plate with a retardation layer described in the above items A to F can be applied to an image display device. Therefore, an embodiment of the present invention includes an image display device using such a polarizing plate with a retardation layer. As a representative example of the image display device, a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device) can be cited. The image display device according to the embodiment of the present invention includes the polarizing plate with a retardation layer described in the above items A to F on its visual recognition side. The polarizing plate with a retardation layer is laminated such that the retardation layer faces the image display unit (for example, a liquid crystal unit, an organic EL unit, an inorganic EL unit) side (the polarizing member faces the visual recognition side). Such an image display device is very thin, but has excellent reliability in a high-temperature and high-humidity environment, and an increase in reflectance is suppressed. Furthermore, corrosion of metal members is significantly suppressed. In one embodiment, the image display device has a curved shape (substantially a curved display screen) and / or is bendable or foldable.

[0149] Example

[0150] Hereinafter, the present invention will be specifically described using examples, but the present invention is not limited by these examples. The measurement methods of each characteristic are as described below. In addition, unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight.

[0151] (1) Thickness

[0152] For a thickness of 10 μm or less, it is measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). For a thickness greater than 10 μm, it is measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C").

[0153] (2) Iodine absorption index and potassium absorption index

[0154] The resin solutions used in the examples and comparative examples are coated on a 38-μm polyethylene terephthalate (PET) film so that the dried thickness becomes 1 μm and dried to obtain a test specimen of a resin layer / PET film. The obtained test specimen is immersed in a 10% aqueous solution of potassium iodide adjusted to 23 °C (90 parts by weight of pure water and 10 parts by weight of potassium iodide) for 24 hours. After immersion, the test specimen is taken out from the aqueous solution, the water droplets on the surface are wiped off, and the intensities (kcps) of iodine and potassium are obtained by fluorescence X-ray measurement on the surface of the resin layer. The obtained intensity of iodine is used as the iodine absorption index, and the intensity of potassium is used as the potassium absorption index. It should be noted that the conditions for fluorescence X-ray analysis are as described below.

[0155] · Analysis device: Fluorescence X-ray analyzer (XRF) manufactured by Rigaku Denki Kogyo Co., Ltd., product name "ZSX100e"

[0156] · Test specimen: Circular specimen with a diameter of 10 mm

[0157] · Anti-cathode: Rhodium

[0158] · Spectrometer crystal: Lithium fluoride

[0159] · Excitation light energy: 40 kV - 90 mA

[0160] · Iodine measurement ray: I-LA

[0161] · Quantification method: FP method

[0162] · 2θ angle peak: 103.078 deg (iodine), 136.847 deg (potassium)

[0163] · Measurement time: 40 seconds

[0164] (3) Reflectance increase

[0165] The polarizing plates with a phase difference layer obtained in the examples and comparative examples were bonded to alkali-free glass to prepare test specimens. The test specimens were placed on a reflector with a reflectance of 80%, and the value measured at 550 nm in SCI mode using a spectrophotometer (CM700D manufactured by Konica Minolta) was taken as the reflectance (%), which was regarded as the initial reflectance. Further, after subjecting the test specimens to a reliability test (placed in an environment of 60 °C and 90% RH for 500 hours and then placed in an environment of 23 °C and 55% RH for 24 hours), the reflectance was measured in the same manner as above. The reflectance increase was calculated by the following formula.

[0166] Reflectance increase (%) = Initial reflectance (%) - Reflectance after reliability test (%)

[0167] Furthermore, the evaluation was carried out according to the following criteria.

[0168] Good: Reflectance increase is less than 0.50%

[0169] Acceptable: Reflectance increase is 0.50% or more and less than 1.00%

[0170] Poor: Reflectance increase is 1.00% or more

[0171] (4) Metal corrosiveness (48 hours)

[0172] A silver nanowire solution (manufactured by MERCK, nanowire size: diameter 115 nm, length 20 μm to 50 μm, isopropyl alcohol (IPA) solution with a solid content of 0.5%) was coated on one side of a 50-μm polyethylene terephthalate (PET) film with a wire bar so that the wet film thickness became 15 μm, and dried in an oven at 100 °C for 5 minutes to form a silver nanowire coating film. Then, an overcoat liquid (solid content concentration: about 1%) containing 99 parts of methyl isobutyl ketone (MIBK), 1 part of pentaerythritol tetraacrylate (PETA), and 0.03 part of a photoinitiator (manufactured by BASF, product name "IRGACURE 907") was coated on the surface of the silver nanowire coating film with a wire bar so that the wet film thickness became 10 μm, and dried in an oven at 100 °C for 5 minutes. Then, active energy rays were irradiated to cure the overcoat film, and a metal film having a structure of PET film / silver nanowire layer / overcoat layer (thickness 100 nm) was fabricated. The metal film was bonded to a 0.5-mm-thick glass plate using an adhesive (15 μm) to obtain a laminate of metal film / adhesive / glass plate. The resistance value of the obtained laminate was measured with a non-contact resistance measuring device (manufactured by Napson, product name "EC-80"), and the result was 50 Ω / □.

[0173] The polarizing plate with a phase difference layer obtained in the examples and comparative examples was attached to the outer coating surface of the metal thin film of the laminate to serve as a test specimen. The resistance value of this test specimen was measured with a non-contact resistance meter as the initial resistance value. Furthermore, after subjecting the test specimen to a reliability test (storing it in an environment of 85°C and 85% RH for 48 hours and then storing it in an environment of 23°C and 55% RH for 2 hours), the resistance value was measured in the same manner as above. The resistance value increase rate was calculated by the following formula. Note that when the measured value (resistance value) was greater than the measurement limit (1000 Ω / sq) of the non-contact resistance meter, the measured value was assumed to be 1500 Ω / sq.

[0174] Resistance value increase rate (%) = { (resistance value after reliability test - initial resistance value) / initial resistance value} × 100

[0175] Furthermore, evaluation was performed according to the following criteria.

[0176] Good: Resistance value increase rate is less than 200%

[0177] Bad: Resistance value increase rate is 200% or more

[0178] (5) Metal corrosion resistance (200 hours)

[0179] The polarizing plate with a phase difference layer obtained in the examples and comparative examples was attached to the outer coating formation surface of the metal thin film of the laminate obtained in (2) to serve as a test specimen. The resistance value of this test specimen was measured with a non-contact resistance meter as the initial resistance value. Furthermore, after subjecting the test specimen to a reliability test (storing it in an environment of 85°C and 85% RH for 200 hours and then storing it in an environment of 23°C and 55% RH for 2 hours), the resistance value was measured in the same manner as above. The resistance value increase rate was calculated by the following formula. Note that when the measured value (resistance value) was greater than the measurement limit (1000 Ω / sq) of the non-contact resistance meter, the measured value was assumed to be 1500 Ω / sq.

[0180] Resistance value increase rate (%) = { (resistance value after reliability test - initial resistance value) / initial resistance value} × 100

[0181] Furthermore, evaluation was performed according to the following criteria.

[0182] Excellent: Resistance value increase rate is less than 200%

[0183] Good: Resistance value increase rate is 200% or more and less than 2000%

[0184] Bad: Resistance value increase rate is 2000% or more

[0185] [Example 1]

[0186] 1. Production of Polarizing Element

[0187] As the thermoplastic resin substrate, an amorphous isophthalic acid copolyethylene terephthalate film (thickness: 100 μm) in the form of a long strip with a water absorption rate of 0.75% and a Tg of about 75°C is used. Corona treatment is performed on one side of the resin substrate.

[0188] To 100 parts by weight of a PVA-based resin in which polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “GOHSEFIMER Z410”) are mixed in a ratio of 9:1, 13 parts by weight of potassium iodide is added, and the resulting product is dissolved in water to prepare a PVA aqueous solution (coating solution).

[0189] The above PVA aqueous solution is coated on the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

[0190] The obtained laminate is subjected to free-end unidirectional stretching to 2.4 times in the longitudinal direction (length direction) between rollers with different circumferential speeds in an oven at 130°C (air-assisted stretching treatment).

[0191] Next, the laminate is immersed in an insolubilizing bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilizing treatment).

[0192] Next, in a dyeing bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water), the concentration is adjusted so that the monomer transmittance (Ts) of the finally obtained polarizing element is 43.0% or more, and the laminate is immersed for 60 seconds (dyeing treatment).

[0193] Next, the laminate is immersed in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (crosslinking treatment).

[0194] Thereafter, while immersing the laminate in a boric acid aqueous solution at a liquid temperature of 70°C (boric acid concentration 4.0% by weight, potassium iodide concentration 5% by weight), unidirectional stretching is performed in the longitudinal direction (length direction) between rollers with different circumferential speeds so that the total stretching ratio becomes 5.5 times (stretching treatment in water).

[0195] Thereafter, the laminate is immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).

[0196] Thereafter, while drying in an oven maintained at 90°C, it is brought into contact with a SUS heating roller having a surface temperature maintained at 75°C for about 2 seconds (dry shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the dry shrinkage treatment is 5.2%.

[0197] Thus, a polarizing member with a thickness of 5 μm is formed on the resin substrate.

[0198] 2. Production of polarizing plate

[0199] An HC-COP film is adhered as a protective layer to the surface of the above-obtained polarizing member (the surface on the side opposite to the resin substrate) by means of an ultraviolet curable adhesive. Specifically, the coating is performed so that the total thickness of the curable adhesive becomes 1.0 μm, and lamination is carried out using a rolling mill. Thereafter, UV light is irradiated from the protective layer side to cure the adhesive. It should be noted that the HC-COP film is a film in which a hard coat (HC) layer (thickness 2 μm) is formed on a cycloolefin (COP) film (manufactured by Zeon Corporation, product name "ZF12", thickness 25 μm), and it is adhered in such a manner that the COP film faces the polarizing member side. Then, the resin substrate is peeled off to obtain a polarizing plate having a structure of protective layer (HC layer / COP film) / adhesive layer / polarizing member.

[0200] 3. Production of the first alignment cured layer and the second alignment cured layer constituting the retardation layer

[0201] 10 g of a polymerizable liquid crystal showing a nematic liquid crystal phase (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photoinitiator for this polymerizable liquid crystal compound (manufactured by BASF: trade name "IRGACURE 907") are dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid).

[0202]

[0203] The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) is rubbed with a friction cloth to perform an alignment treatment. The alignment direction is set to be 15° with respect to the absorption axis direction of the polarizing member when viewed from the visual recognition side when adhered to the polarizing plate. The above liquid crystal coating liquid is applied to the alignment-treated surface using a bar coater, and heated and dried at 90°C for 2 minutes to orient the liquid crystal compound. The liquid crystal layer thus formed is irradiated with light of 1 mJ / cm 2 to cure the liquid crystal layer, thereby forming a liquid crystal alignment cured layer A on the PET film. The thickness of the liquid crystal alignment cured layer A is 2.5 μm, and the in-plane retardation Re(550) is 270 nm. Further, the liquid crystal alignment cured layer A has a refractive index distribution of nx > ny = nz.

[0204] The coating thickness was changed, and the direction of the alignment treatment was set to be 75° with respect to the absorption axis direction of the polarizer when viewed from the visual recognition side. Except for this, the same operations as above were performed, and a liquid crystal alignment cured layer B was formed on the PET film. The thickness of the liquid crystal alignment cured layer B was 1.5 μm, and the in-plane retardation Re(550) was 140 nm. Furthermore, the liquid crystal alignment cured layer B had a refractive index distribution of nx > ny = nz.

[0205] 4. Formation of the retardation layer

[0206] The liquid crystal alignment cured layer A and the liquid crystal alignment cured layer B obtained in the above 3. were successively transferred onto the surface of the polarizer of the polarizing plate obtained in the above 2. At this time, the transfer (lamination) was performed such that the angle formed by the absorption axis of the polarizer and the slow axis of the liquid crystal alignment cured layer A was 15° and the angle formed by the absorption axis of the polarizer and the slow axis of the liquid crystal alignment cured layer B was 75°. It should be noted that each transfer (lamination) was performed using the ultraviolet curable adhesive (thickness 1.0 μm) used in the above 2. Thus, a laminate having a structure of protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / retardation layer (first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer) was produced.

[0207] 5. Production of the polarizing plate with a retardation layer

[0208] 20 parts of an acrylic resin (manufactured by Kusumoto Chemicals, product name "B-811", Tg: 110°C, Mw: 40,000) was dissolved in 80 parts of methyl ethyl ketone to obtain a resin solution (20%). This resin solution was coated on the surface of the second liquid crystal alignment cured layer of the laminate obtained in the above 4. using a wire bar, and the coated film was dried at 60°C for 5 minutes to form an iodine permeation inhibiting layer (thickness 0.5 μm) composed of a solidified product of the coated film of the organic solvent solution of the resin. The iodine absorption index of the iodine permeation inhibiting layer was 0.0046, and the potassium absorption index was 0.0087. Then, an adhesive layer (thickness 15 μm) was provided on the surface of the iodine permeation inhibiting layer to obtain a polarizing plate with a retardation layer having a structure of protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / retardation layer (first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer) / iodine permeation inhibiting layer / adhesive layer. The total thickness of the obtained polarizing plate with a retardation layer was 39.5 μm. The obtained polarizing plate with a retardation layer was subjected to the evaluations in the above (3) to (5). Furthermore, regarding the metal corrosiveness, a comparison was made with Comparative Example 1 (described later) in which the iodine permeation inhibiting layer was not formed. The results are shown in Tables 1 and 2.

[0209] [Example 2]

[0210] 97.0 parts of methyl methacrylate (MMA, manufactured by Fujifilm Wako Pure Chemical Corporation, trade name "methyl methacrylate monomer"), 3.0 parts of the comonomer represented by the above general formula (1e), and 0.2 parts of a polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Corporation, trade name "2,2'-azobis(isobutyronitrile)") were dissolved in 200 parts of toluene. Then, while heating to 70 °C under a nitrogen atmosphere, a polymerization reaction was carried out for 5.5 hours to obtain a boron-containing acrylic resin solution (solid content concentration: 33%). The Tg of the obtained boron-containing acrylic polymer was 110 °C, and the Mw was 80,000. Using this boron-containing acrylic polymer instead of the acrylic resin "B-811" and setting the thickness of the iodine permeation inhibiting layer to 0.3 μm, a polarizing plate with a phase difference layer was produced in the same manner as in Example 1 except for this. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0211] [Example 3]

[0212] Except for setting the thickness of the iodine permeation inhibiting layer to 0.5 μm, a polarizing plate with a phase difference layer was produced in the same manner as in Example 2. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0213] [Example 4]

[0214] Except for using a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., trade name "jER (registered trademark) 1256B40", Tg: 100 °C, Mw: 45,000) instead of the acrylic resin "B-811", a polarizing plate with a phase difference layer was produced in the same manner as in Example 1. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0215] [Example 5]

[0216] Using a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., trade name "jER (registered trademark) YX7200B35", Tg: 150 °C, Mw: 30,000) instead of the acrylic resin "B-811" and setting the thickness of the iodine permeation inhibiting layer to 0.3 μm, a polarizing plate with a phase difference layer was produced in the same manner as in Example 1 except for this. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0217] [Example 6]

[0218] A polarizing plate with a retardation layer was produced in the same manner as in Example 5, except that the thickness of the iodine permeation inhibiting layer was set to 0.5 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0219] [Example 7]

[0220] A polarizing plate with a retardation layer was produced in the same manner as in Example 1, except that a blend of 15 parts of "B-811" and 85 parts (in terms of solid content) of a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., trade name "jER (registered trademark) YX6954BH30") was used instead of the acrylic resin "B-811". The Tg of this blend was 125°C and the Mw was 38000. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0221] [Example 8]

[0222] The resin blend used in Example 7 was coated on the polarizer side of the polarizing plate having the structure of a protective layer (HC layer / COP film) / adhesive layer / polarizer obtained in 2. of Example 1 and dried to form an iodine permeation inhibiting layer (thickness 0.5 μm) composed of a solidified product of a coating film of a resin organic solvent solution. A liquid crystal alignment cured layer A and a liquid crystal alignment cured layer B were sequentially transferred onto the surface of the iodine permeation inhibiting layer in the same manner as in Example 1, and a polarizing plate with a retardation layer having the structure of a protective layer (HC layer / COP film) / adhesive layer / polarizer / iodine permeation inhibiting layer / adhesive layer / retardation layer (first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer) / adhesive layer was obtained. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0223] [Example 9]

[0224] Except for using the boron-containing acrylic polymer in Example 2, a laminate having a structure of a protective layer (HC layer / COP film) / adhesive layer / polarizer / iodine permeation inhibiting layer was produced in the same manner as in Example 8. Then, a blend of 15 parts of the boron-containing acrylic polymer obtained in Example 2 and 85 parts (in terms of solid content) of a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., trade name “jER (registered trademark) YX6954BH30”) was used. Except for this, a polarizing plate with a retardation layer having a structure of a protective layer (HC layer / COP film) / adhesive layer / polarizer / iodine permeation inhibiting layer / adhesive layer / retardation layer (first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer) / iodine permeation inhibiting layer / adhesive layer was obtained in the same manner as in Example 1. The total thickness of the obtained polarizing plate with a retardation layer was 40 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0225] [Example 10]

[0226] The iodine permeation inhibiting layer provided between the polarizer and the retardation layer and adjacent to the polarizer was formed of a blend of 15 parts of the boron-containing acrylic polymer obtained in Example 2 and 85 parts (in terms of solid content) of a thermoplastic epoxy resin (manufactured by Mitsubishi Chemical Co., trade name “jER (registered trademark) YX6954BH30”). Except for this, a polarizing plate with a retardation layer was obtained in the same manner as in Example 9. The total thickness of the obtained polarizing plate with a retardation layer was 40 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0227] [Example 11]

[0228] The iodine permeation inhibiting layer formed between the polarizer and the retardation layer and adjacent to the polarizer was formed between the polarizer and the retardation layer and adjacent to the retardation layer. Except for this, a polarizing plate with a retardation layer having a structure of a protective layer (HC layer / COP film) / adhesive layer / polarizer / adhesive layer / iodine permeation inhibiting layer / retardation layer (first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer) / iodine permeation inhibiting layer / adhesive layer was obtained in the same manner as in Example 10. The total thickness of the obtained polarizing plate with a retardation layer was 40 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0229] [Example 12]

[0230] The operation was the same as in Example 9, and an iodine permeation inhibition layer was further formed between the polarizing member and the retardation layer at a position adjacent to the polarizing member. Except for this, a polarizing plate with a retardation layer having a structure of protective layer (HC layer / COP film) / adhesive layer / polarizing member / iodine permeation inhibition layer / adhesive layer / iodine permeation inhibition layer / retardation layer (first liquid crystal alignment cured layer / adhesive layer / second liquid crystal alignment cured layer) / iodine permeation inhibition layer / adhesive layer was obtained in the same manner as in Example 11. The total thickness of the obtained polarizing plate with a retardation layer was 40.5 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0231] [Comparative Example 1]

[0232] A polarizing plate with a retardation layer was produced in the same manner as in Example 1, except that the iodine permeation inhibition layer was not formed. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0233] [Comparative Example 2]

[0234] An acrylic resin “B-723” (manufactured by Enomoto Kasei Co., Ltd., Tg: 54 °C, Mw: 200000) was used instead of the acrylic resin “B-811”. Except for this, a polarizing plate with a retardation layer was produced in the same manner as in Example 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0235] [Comparative Example 3]

[0236] A photocurable epoxy resin (manufactured by Mitsubishi Chemical Co., trade name “jER (registered trademark) 828”) was used instead of the acrylic resin “B-811”, and “CPI100P” manufactured by San-Apro Ltd. was used as a photopolymerization initiator. Except for this, a polarizing plate with a retardation layer was produced in the same manner as in Example 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0237] [Comparative Example 4]

[0238] Except for using a PVA-based resin (manufactured by Mitsubishi Chemical Co., trade name “GOHSENOL Z200”, Tg: 80 °C, Mw: 8800) instead of the acrylic resin “B-811”, a polarizing plate with a retardation layer was produced in the same manner as in Example 1. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0239] [Reference Example 1]

[0240] 1. Production of Polarizing Plate

[0241] A polarizing plate having a structure of a protective layer (HC layer / COP film) / polarizing element was obtained in the same manner as in Example 1.

[0242] 2. Production of Retardation Film Constituting Retardation Layer

[0243] 2-1. Polymerization of Polyester Carbonate Resin

[0244] Polymerization was carried out using a batch polymerization apparatus composed of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluorene-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spirodiol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 -2 parts by mass (6.78×10 -5 mol) of calcium acetate monohydrate as a catalyst were added. After replacing the inside of the reactor with nitrogen under reduced pressure, it was heated using a heat medium, and stirring was started at the time when the internal temperature reached 100°C. The internal temperature was raised to 220°C 40 minutes after the start of heating, and it was controlled to maintain this temperature while starting decompression at the same time, so that it became 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C to return a small amount of monomer components contained in the phenol vapor to the reactor, and the uncondensed phenol vapor was introduced into a condenser at 45°C for recovery. After introducing nitrogen into the first reactor to temporarily restore it to atmospheric pressure, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Then, heating and decompression in the second reactor were started, and after 50 minutes, the internal temperature became 240°C and the pressure became 0.2 kPa. Thereafter, polymerization was carried out until a specified stirring power was reached. At the time when the specified power was reached, nitrogen was introduced into the reactor to restore the pressure, and the produced polyester carbonate resin was extruded into water, and the strand was cut to obtain pellets.

[0245] 2-2. Production of Retardation Film

[0246] After vacuum drying the obtained polyester carbonate resin (pellets) at 80 °C for 5 hours, a film-forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel set temperature: 250 °C), a T-die (width 200 mm, set temperature: 250 °C), a cooling roll (set temperature: 120 - 130 °C), and a winder was used to produce a long resin film with a thickness of 135 μm. The obtained long resin film was stretched in the width direction at a stretching temperature of 133 °C and a stretching ratio of 2.8 times to obtain a retardation film with a thickness of 53 μm. The Re(550) of the obtained retardation film was 141 nm, Re(450) / Re(550) was 0.82, and the Nz coefficient was 1.12.

[0247] 3. Fabrication of a polarizing plate with a retardation layer

[0248] The retardation film obtained in 2. above was adhered to the surface of the polarizing element of the polarizing plate obtained in 1. above with an acrylic-based adhesive (thickness 5 μm). At this time, it was adhered in such a way that the absorption axis of the polarizing element and the slow axis of the retardation film formed an angle of 45°. Further, an adhesive layer the same as that in Example 1 was provided on the surface of the retardation layer. Thus, a polarizing plate with a retardation layer having a structure of protective layer / adhesive layer / polarizing element / adhesive layer / retardation layer (stretched film of resin film) / adhesive layer was obtained. The total thickness of the obtained polarizing plate with a retardation layer was 91 μm. The obtained polarizing plate with a retardation layer was subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0249] [Table 1]

[0250]

[0251] [Table 2]

[0252]

[0253] * The blend is a blend of an acrylic resin and an epoxy resin

[0254] * Position A represents between the retardation layer and the adhesive layer, position B represents the position adjacent to the polarizing element between the polarizing element and the retardation layer,

[0255] Position C represents the position adjacent to the retardation layer between the polarizing element and the retardation layer.

[0256] [Evaluation]

[0257] As is clear from Table 1, the polarizing plate with a phase difference layer according to the embodiments of the present invention can significantly suppress the increase in reflectance in a high-temperature and high-humidity environment by forming an iodine permeation suppression layer having an iodine absorption index equal to or less than a specified value. In addition, by forming such an iodine permeation suppression layer, the metal corrosion in a high-temperature and high-humidity environment can also be significantly suppressed. Furthermore, it is clear from Reference Example 1 that such an increase in reflectance and metal corrosion are problems peculiar to very thin polarizing plates with a phase difference layer.

[0258] As is clear from Table 2, the polarizing plates with a phase difference layer according to Embodiments 9 to 12 of the present invention can significantly suppress metal corrosion even when left for a long time (200 hours) in a high-temperature and high-humidity environment by including two or three iodine permeation suppression layers. Therefore, it can be understood that the polarizing plates with a phase difference layer according to Embodiments 9 to 12 of the present invention can significantly suppress the corrosion of metal members when applied to an image display device.

[0259] Industrial Applicability

[0260] The polarizing plate with a phase difference layer of the present invention can be suitably used as a circular polarizing plate for a liquid crystal display device, an organic EL display device, and an inorganic EL display device.

[0261] Description of Reference Numerals

[0262] 10: Polarizing plate

[0263] 11: Polarizing element

[0264] 12: Protective layer

[0265] 20: Phase difference layer

[0266] 30: Adhesive layer

[0267] 40: Iodine permeation suppression layer

[0268] 100: Polarizing plate with a phase difference layer

[0269] 101: Polarizing plate with a phase difference layer

[0270] 102: Polarizing plate with a phase difference layer

[0271] 103: Polarizing plate with a phase difference layer

[0272] 104: Polarizing plate with a phase difference layer

[0273] 105: Polarizing plate with a phase difference layer

Claims

1. A polarizing plate with a phase difference layer, which sequentially has a polarizing plate including a polarizing element, a phase difference layer, and an adhesive layer from the visual recognition side; The phase difference layer is an alignment cured layer of a liquid crystal compound having a circular polarization function or an elliptical polarization function; The polarizing element contains iodine, An iodine permeation inhibition layer is provided between the polarizing element and the adhesive layer, and the iodine permeation inhibition layer is composed of a thermoplastic resin soluble in an organic solvent; The iodine absorption index of the iodine permeation inhibition layer is 0.015 or less, The resin constituting the iodine permeation inhibition layer includes a copolymer obtained by polymerizing a monomer mixture, and the monomer mixture includes more than 50 parts by weight of a (meth)acrylic acid-based monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by the formula (1), In the formula, X represents a functional group containing a reactive group, and the reactive group is at least one reactive group selected from the group consisting of a vinyl group, a (meth)acryloyl group, a styryl group, a (meth)acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, a hydroxyl group, an amino group, an aldehyde group, and a carboxyl group, R 1 and R 2 each independently represents a hydrogen atom, an aliphatic hydrocarbon group optionally having a substituent, an aryl group optionally having a substituent, or a heterocyclic group optionally having a substituent, R 1 and R 2 optionally connect to each other to form a ring.

2. The polarizing plate with a phase difference layer according to claim 1, wherein, The iodine permeation inhibiting layer is disposed between the polarizing member and the retardation layer.

3. The polarizing plate with a phase difference layer according to claim 1, wherein, The iodine permeation inhibiting layer is disposed between the retardation layer and the adhesive layer.

4. The polarizing plate with a phase difference layer according to claim 1, wherein, There are two or more iodine permeation inhibiting layers between the polarizing member and the adhesive layer.

5. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, wherein, The potassium absorption index of the iodine permeation inhibiting layer is 0.015 or less.

6. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, wherein, The glass transition temperature of the resin constituting the iodine permeation inhibiting layer is 85 °C or higher, and the weight average molecular weight Mw is 25,000 or higher.

7. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, wherein, The retardation layer is a single layer, Re(550) of this retardation layer is 100 nm to 190 nm, The angle formed by the slow axis of this retardation layer and the absorption axis of the polarizing member is 40° to 50°.

8. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, wherein, The retardation layer has a laminated structure of an alignment cured layer of a first liquid crystal compound and an alignment cured layer of a second liquid crystal compound; Re(550) of the alignment cured layer of this first liquid crystal compound is 200 nm to 300 nm, and the angle formed by its slow axis and the absorption axis of the polarizing member is 10° to 20°; Re(550) of the alignment cured layer of this second liquid crystal compound is 100 nm to 190 nm, and the angle formed by its slow axis and the absorption axis of the polarizing member is 70° to 80°.

9. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, wherein, There is also another retardation layer between the retardation layer and the adhesive layer, and the refractive index characteristics of this another retardation layer show a relationship of nz>nx = ny.

10. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, wherein, There is also a conductive layer or an isotropic substrate with a conductive layer between the iodine permeation inhibiting layer and the adhesive layer.

11. The polarizing plate with a phase difference layer according to any one of claims 1 to 4, having a total thickness of 60 μm or less.

12. An image display device including the polarizing plate with a phase difference layer according to any one of claims 1 to 11.

13. The image display device according to claim 12, which is an organic electroluminescent display device or an inorganic electroluminescent display device.

Images