Polarizing Plate and Organic Electroluminescence Display Device

Abstract

To provide a polarizing plate that has extremely good durability.SOLUTION: A polarizing plate according to an embodiment of the present invention has: a polarizer that has a first principal surface and a second principal surface opposite to each other; a laminated film that is arranged on the first principal surface of the polarizer, and includes a base material and a hard coat layer in this order from the side of the polarizer; and a phase difference layer that is arranged on the second principal surface of the polarizer. The moisture permeability of the laminated film is 600 g / m2 24h or less. After the laminated film is placed in an environment of 65°C and 95%RH for 48 hours, the rate of change in the moisture permeability of the laminated film is 1.5 or less. The moisture permeability of the phase difference layer is 200 g / m2 24h or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polarizing plate and an organic electroluminescence (EL) display device.

Background Art

[0002] In recent years, with the spread of thin displays, displays equipped with organic EL panels (organic EL display devices) have been proposed. Since the organic EL panel has a highly reflective metal layer, problems such as external light reflection and background reflection are likely to occur. Therefore, it is known to prevent these problems by providing a polarizing plate with a retardation layer, which is a combination of a polarizing plate and a retardation plate, on the viewing side of the organic EL panel main body (for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] With the spread of thin displays, extremely high moisture resistance may be required for organic EL display devices, and extremely high moisture resistance may also be required for polarizing plates. Moreover, the polarizing plate provided in the organic EL display device is likely to decolorize, and decolorization tends to be promoted in a high-humidity environment.

[0005] The present invention has been made to solve the above problems, and its main object is to provide a polarizing plate having extremely excellent durability.

Means for Solving the Problems

[0006] The polarizing plate according to an embodiment of the present invention includes a polarizer having a first main surface and a second main surface facing each other, a laminated film disposed on the first main surface side of the polarizer and including a base material and a hard coat layer in this order from the polarizer side, and a retardation layer disposed on the second main surface side of the polarizer. The moisture permeability of the laminated film is 600 g / m 2 ·24 h or less, and the change rate of the moisture permeability of the laminated film by leaving the laminated film in an environment of 65° C. and 95% RH for 48 hours is 1.5 or less. The moisture permeability of the retardation layer is 200 g / m 2 ·24 h or less. In one embodiment, the change rate is 1.1 or more. In one embodiment, the thickness of the hard coat layer is 1 μm or more. In one embodiment, the thickness of the hard coat layer is 7 μm or less. In one embodiment, the laminated film includes an intermediate layer containing components derived from the base material and components derived from the hard coat layer between the base material and the hard coat layer. In one embodiment, the retardation layer is disposed adjacent to the polarizer. In one embodiment, Re(450) / Re(550) of the retardation layer is 0.8 or more and less than 1. In one embodiment, the single transmittance of the polarizer is 43.0% or more. In one embodiment, the thickness of the polarizer is 10 μm or less. According to another aspect of the present invention, an organic electroluminescence display device is provided. This organic electroluminescence display device has the above polarizing plate.

Advantages of the Invention

[0007] According to the embodiment of the present invention, a polarizing plate with extremely excellent durability can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. Further, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0010] (Definitions of Terms and Symbols) The definitions of terms and symbols in this specification are as follows. (1) Refractive Index (nx, ny, nz) “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), “ny” is the refractive index in the 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. (2) In-Plane Phase Difference (Re) “Re(λ)” is the in-plane phase difference measured with light of wavelength λ nm at 23°C. For example, “Re(550)” is the in-plane phase difference measured with light of wavelength 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ)=(nx - ny)×d, where d (nm) is the thickness of the layer (film). (3) Phase Difference in the Thickness Direction (Rth) “Rth(λ)” is the phase difference in the thickness direction measured with light of wavelength λ nm at 23°C. For example, “Rth(550)” is the phase difference in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) is obtained by the formula: Rth(λ)=(nx - nz)×d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°.

[0011] A. Polarizing plate FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an example of a schematic configuration of a laminated film of the polarizing plate shown in FIG. 1. The polarizing plate (polarizing plate with a retardation layer) 100 has a polarizer 10 having first and second main surfaces 10a and 10b facing each other, a laminated film 20 disposed on the first main surface 10a side of the polarizer 10, and a retardation layer 30 and an adhesive layer 40 disposed on the second main surface 10b side of the polarizer 10. The laminated film 20 includes a base material 21 and a hard coat layer 22 in this order from the polarizer 10 side, and the base material 21 can function as a protective layer of the polarizer 10. The polarizing plate 100 is typically arranged in an organic EL display device such that the laminated film 20 is on the viewing side rather than the polarizer 10.

[0012] In the illustrated example, the retardation layer 30 is a single layer, but different from the illustrated example, it may have a laminated structure of two or more layers. Specifically, the retardation layer 30 may include two or more layers having different optical properties (for example, refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient). Also, in the illustrated example, no protective layer is disposed between the polarizer 10 and the retardation layer 30, and the retardation layer 30 is disposed adjacent to the polarizer 10 and can function as a protective layer of the polarizer 10, but the polarizing plate 100 may have a protective layer disposed between the polarizer 10 and the retardation layer 30. Note that adjacent includes not only being directly adjacent but also being adjacent through an adhesive layer described later.

[0013] Each member constituting the polarizing plate can be laminated via any appropriate adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive agent layer. For example, the laminated film 20 is bonded to the polarizer 10 via an adhesive layer (preferably, using an active energy ray-curable adhesive). For example, the retardation layer 30 is bonded to the polarizer 10 or a protective layer (not shown) via an adhesive layer (preferably, using an active energy ray-curable adhesive) or via an adhesive agent layer (e.g., an acrylic adhesive agent). When the retardation layer 30 has a laminated structure of two or more layers, each retardation layer is bonded, for example, via an adhesive layer (preferably, using an active energy ray-curable adhesive). The thickness of the adhesive layer is preferably 0.4 μm or more, more preferably 0.4 μm to 3.0 μm, and even more preferably 0.6 μm to 1.5 μm. The thickness of the adhesive agent layer is preferably 1 μm to 10 μm.

[0014] The adhesive agent layer 40 disposed on the second main surface 10b side of the polarizer 10 enables the polarizing plate 100 to be attached to the organic EL panel body, for example. Although not shown, a release liner is practically bonded to the surface of the adhesive agent layer 40. The release liner can be temporarily attached until the polarizing plate is put into use. By using the release liner, for example, the adhesive agent layer is protected and the polarizing plate can be formed into a roll.

[0015] The polarizing plate may be in a long strip shape or a single sheet shape. Here, the "long strip shape" refers to an elongated shape in which the length is sufficiently long with respect to the width, for example, an elongated shape in which the length is 10 times or more, preferably 20 times or more, the width. The long strip-shaped polarizing plate can be wound into a roll.

[0016] A-1. Polarizer The above-mentioned polarizer is typically a film containing a dichroic substance (typically, iodine).

[0017] The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, and particularly preferably 8 μm or less, from the viewpoint of thinning, for example. On the other hand, the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, and still more preferably 3 μm or more.

[0018] The polarizer preferably exhibits absorption dichroism at any wavelength in the wavelength range of 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 40.0% or more, preferably 41.5% or more, more preferably 43.0% or more, and still more preferably 44.5% or more. In the case of a polarizer having a high single transmittance, the above-mentioned decolorization problem can become more prominent. On the other hand, the single transmittance is, for example, 48.0% or less, may be 46.0% or less, or may be 45.0% or less. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

[0019] The above single transmittance is typically the Y value measured using an ultraviolet-visible spectrophotometer and corrected for visual sensitivity. The degree of polarization is typically determined by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured using an ultraviolet-visible spectrophotometer and corrected for visual sensitivity. Degree of polarization (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100

[0020] The polarizer can be produced by any suitable method. Specifically, the polarizer may be produced from a single-layer resin film or may be produced using a laminate of two or more layers.

[0021] A method for manufacturing a polarizer from the above-mentioned single-layer resin film typically includes subjecting the resin film to a dyeing treatment with a dichroic substance such as iodine or a dichroic dye and a stretching treatment. As the resin film, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or a partially saponified ethylene-vinyl acetate copolymer-based film is used. The method may further include an insolubilization treatment, a swelling treatment, a crosslinking treatment, and the like. Since such a manufacturing method is well-known and commonly used in the art, a detailed description thereof will be omitted.

[0022] The polarizer obtained using the above laminate can be produced, for example, using a laminate of a resin substrate and a resin film or a resin layer (typically, a PVA-based resin layer). Specifically, it can be produced by applying a PVA-based resin solution to a resin substrate and drying it to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In the present embodiment, preferably, a PVA-based resin layer containing a halide and a PVA-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Further, stretching may further include air stretching the laminate at a high temperature (for example, 95°C or higher) before stretching in the aqueous boric acid solution, if necessary. In addition, in the present embodiment, preferably, the laminate is subjected to a drying shrinkage treatment in which it is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of the present embodiment includes subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing auxiliary stretching, even when PVA is applied on a thermoplastic resin, it is possible to enhance the crystallinity of PVA and achieve high optical properties. At the same time, by enhancing the orientation of PVA in advance, problems such as a decrease in the orientation of PVA and dissolution when immersed in water in subsequent dyeing and stretching steps can be prevented, and high optical properties can be achieved. Further, 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 disturbance of the orientation of PVA molecules and the decrease in orientation can be suppressed, and high optical properties can be achieved. Further, by shrinking the laminate in the width direction by the drying shrinkage treatment, high optical properties can be achieved. A polarizing plate can be obtained by laminating a protective layer on the peeling surface obtained by peeling the resin substrate from the obtained laminate of the resin substrate / polarizer, or on the surface opposite to the peeling surface. Details of such a method for manufacturing a polarizer are described, for example, in JP-A-2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

[0023] A-2. Laminated Film In one embodiment, as shown in FIG. 2, the laminated film 20 has a base material (protective layer) 21 and a hard coat layer 22, and further, an intermediate layer 23 may be formed between the base material 21 and the hard coat layer 22. The polarizing plate according to the embodiment of the present invention is typically disposed on the viewing side of the organic EL display device, and the hard coat layer 22 is disposed on the viewing side of the base material 21. The hard coat layer 22 may function as other functional layers such as an antireflection layer, an anti-sticking layer, and an antiglare layer, for example.

[0024] The thickness of the laminated film is, for example, 15 μm or more and 70 μm or less, preferably 20 μm or more and 50 μm or less.

[0025] The moisture permeability of the laminated film at 40 ° C. and 92% RH is 600 g / m 2 ·24 h or less, preferably 550 g / m 2 ·24 h or less, more preferably 500 g / m 2 ·24 h or less, still more preferably 450 g / m 2 ·24 h or less. On the other hand, the moisture permeability of the laminated film at 40 ° C. and 92% RH is preferably 300 g / m 2 ·24 h or more, preferably 320 g / m 2 ·24 h or more, more preferably 340 g / m 2 ·24 h or more.

[0026] The moisture permeability of the laminated film subjected to the humidification treatment at 40 ° C. and 92% RH is preferably 800 g / m 2 ·24 h or less, more preferably 700 g / m 2 ·24 h or less, still more preferably 600 g / m 2 ·24 h or less. The change rate of the moisture permeability due to the humidification treatment (moisture permeability after the humidification treatment / moisture permeability before the humidification treatment) is 1.5 or less, preferably 1.4 or less. By using such a laminated film, extremely high moisture resistance can be achieved. The humidification treatment is performed, for example, by placing the laminated film in an environment of 65 ° C. and 95% RH for 48 hours.

[0027] The water vapor permeability of the laminated film subjected to the humidification treatment at 40 °C and 92% RH is preferably 400 g / m 2 ·24 h or more, more preferably 450 g / m 2 ·24 h or more, still more preferably 500 g / m 2 ·24 h or more. The change rate of the water vapor permeability due to the humidification treatment (water vapor permeability after the humidification treatment / water vapor permeability before the humidification treatment) is preferably 1.1 or more, more preferably 1.2 or more. By using such a laminated film, decoloration can be suppressed. The inventors of the present invention have found that when a polarizing plate is used in an organic EL display device, the main cause of the problem that the polarizing plate is likely to decolorize is derived from the members constituting the organic EL panel and is ammonia (substantially ammonium ions) that is likely to be generated in a high-humidity environment. By discharging the ammonium ions that have invaded the polarizing plate (polarizer), decoloration can be suppressed. And by disposing a member having a high water vapor permeability on one side (typically the viewing side) of the polarizer, decoloration can be suppressed. Specifically, the decomposition of the dichroic substance (typically an iodine complex) contained in the polarizer can be suppressed.

[0028] The above-mentioned base material can be composed of any suitable film that can be used as a protective layer for the polarizer. Examples of the material constituting such a base material (film) include cellulose-based resins such as triacetyl cellulose (TAC), cycloolefin-based resins such as polynorbornene, polycarbonate-based resins, (meth)acrylic-based resins, polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and polyolefin-based resins such as polyethylene. Preferably, a cellulose-based resin such as triacetyl cellulose (TAC) is used as the material constituting the base material.

[0029] The thickness of the base material is, for example, 10 μm or more and 65 μm or less, preferably 15 μm or more and 45 μm or less.

[0030] The above hard coat layer is typically formed by coating the above base material with a hard coat layer forming material and curing the coated layer. The hard coat layer forming material typically contains a curable compound as a layer forming component. Examples of the curing mechanism of the curable compound include thermosetting type and photocuring type. Examples of the curable compound include monomers, oligomers, and prepolymers. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. Examples of the polyfunctional monomer or oligomer include monomers or oligomers having two or more (meth)acryloyl groups, urethane (meth)acrylate or oligomers of urethane (meth)acrylate, epoxy-based monomers or oligomers, and silicone-based monomers or oligomers.

[0031] The above hard coat layer forming material may contain any suitable additive. Examples of the additive include polymerization initiators, leveling agents, anti-blocking agents, dispersion stabilizers, thixotropic agents, antioxidants, ultraviolet absorbers, defoaming agents, thickeners, dispersants, surfactants, catalysts, fillers, lubricants, antistatic agents, etc. The type, combination, content, etc. of the additive can be appropriately set according to the purpose and desired properties.

[0032] When the curable compound is of the thermosetting type, the heating temperature is, for example, 60°C to 140°C, preferably 60°C to 100°C. When the curable compound is of the photocuring type, the curing treatment is typically performed by ultraviolet irradiation. The integrated light amount of ultraviolet irradiation is, for example, 100 mJ / cm 2 ~300 mJ / cm 2 . It is also possible to combine ultraviolet irradiation and heating.

[0033] The thickness of the hard coat layer is preferably 1 μm or more, more preferably 1.5 μm or more, and still more preferably 2 μm or more. With such a thickness, it is possible to prevent the moisture permeability of the laminated film from becoming too high. In addition, the scratch resistance of the resulting polarizing plate can be ensured. On the other hand, the thickness of the hard coat layer is preferably 7 μm or less, more preferably 6 μm or less, and still more preferably 5 μm or less. With such a thickness, the above moisture permeability can be satisfactorily satisfied, for example, decoloration can be suppressed. The scratch resistance can be evaluated, for example, by visually checking the degree of scratches generated on the surface of the hard coat layer after rubbing a cylinder with #0000 steel wool attached to the bottom surface against the surface of the hard coat layer 1000 times back and forth at a speed of about 100 mm per second under a load of 1.0 kg.

[0034] The intermediate layer may contain components derived from the base material and components derived from the hard coat layer. Specifically, it can be formed by the compatibility (mixing) of the components forming the base material and the components forming the hard coat layer. For example, when the base material contains TAC, examples of the components derived from the base material include TAC, acetic acid, and cellulose. In the laminated film, the interfaces between the intermediate layer and the base material and between the intermediate layer and the hard coat layer can be confirmed by transmission electron microscope (TEM) observation.

[0035] The thickness of the intermediate layer is, for example, 1 μm or more and 30 μm or less, preferably 1 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less.

[0036] The ratio of the thickness of the hard coat layer to the thickness of the intermediate layer (thickness of the hard coat layer / thickness of the intermediate layer) is preferably 0.5 or more, more preferably 0.6 or more. With such a thickness ratio, for example, it is possible to suppress the change in the moisture permeability of the laminated film due to humidification. On the other hand, the ratio of the thickness of the hard coat layer to the thickness of the intermediate layer (thickness of the hard coat layer / thickness of the intermediate layer) is preferably 1.0 or less, more preferably 0.9 or less. With such a thickness ratio, the above moisture permeability can be satisfactorily satisfied, for example, decoloration can be suppressed.

[0037] The intermediate layer can be formed by, for example, adding a good solvent capable of dissolving the base material to a solvent that may be contained in the hard coat layer forming material. Specifically, a part of the components contained in the hard coat layer forming material (typically, the solvent) is mixed with and / or penetrates into the base material, so that the components forming the base material and the components forming the hard coat layer are compatible (mixed), and the intermediate layer can be formed.

[0038] Examples of the solvent that may be contained in the hard coat layer forming material include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, TBA (tert-butyl alcohol), and 2-methoxyethanol; ketones such as acetone, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), and cyclopentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, and PMA (propylene glycol monomethyl ether acetate); ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl cellosolve and butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene. These may be used alone or in combination of two or more. The content of the solvent is set so that the solid content concentration of the hard coat layer forming material is, for example, 20% by weight or more and 50% by weight or less, preferably 30% by weight or more and 45% by weight or less.

[0039] As the good solvent capable of dissolving the base material, for example, a solvent in which the dissolution amount of the base material (solute) with respect to 100 parts by weight of the solvent is 30 parts by weight or more is used. As a specific example, when the base material contains TAC, as the good solvent capable of dissolving the base material, for example, cyclopentanone (for example, the dissolution amount of TAC with respect to 100 parts by weight of cyclopentanone is 40 parts by weight), MEK (for example, the dissolution amount of TAC with respect to 100 parts by weight of MEK is 60 parts by weight), cyclohexanone, methyl acetate, and ethyl acetate are preferably used.

[0040] In one embodiment, the hard coat layer forming material includes a good solvent capable of dissolving the substrate and a poor solvent that substantially does not dissolve the substrate. As the poor solvent that substantially does not dissolve the substrate, for example, a solvent in which the dissolution amount of the substrate (solute) is less than 30 parts by weight with respect to 100 parts by weight of the solvent is used, and preferably a solvent in which the dissolution amount of the substrate (solute) is 10 parts by weight or less with respect to 100 parts by weight of the solvent is used. When the substrate contains TAC, as the poor solvent that substantially does not dissolve the substrate, for example, ethanol, isopropyl alcohol, and hexane are preferably used. The ratio of the content of the good solvent capable of dissolving the substrate to the content of the poor solvent that substantially does not dissolve the substrate in the hard coat layer forming material (content of good solvent / content of poor solvent, weight ratio) is, for example, 1.5 or less, preferably 0.3 or more and 1.2 or less, and more preferably 0.4 or more and 1.1 or less.

[0041] A-3. Retardation layer As described above, the retardation layer may be a single layer as shown in the figure, or may have a laminated structure of two or more layers. When the retardation layer is a single layer, the retardation layer can typically function as a λ / 4 plate. The retardation layer is typically provided to impart antireflection characteristics to the organic EL display device. The retardation layer typically exhibits a refractive index characteristic relationship of nx>ny=nz. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 120 nm to 160 nm. Here, "ny=nz" includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Specifically, ny>nz or ny<nz may occur. The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. By satisfying such a relationship, an organic EL display device having a very excellent reflection hue can be obtained.

[0042] When the retardation layer is a single layer, the retardation layer preferably exhibits an inverse-dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. In this case, Re(450) / Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, extremely excellent antireflection characteristics can be realized.

[0043] The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. If the angle is within such a range, an organic EL display device having extremely excellent antireflection characteristics can be obtained by using the retardation layer as a λ / 4 plate as described above.

[0044] The moisture permeability of the retardation layer at 40 °C and 92% RH is 200 g / m 2 ·24 h or less, preferably 150 g / m 2 ·24 h or less, more preferably 100 g / m 2 ·24 h or less. Such a retardation layer can function as a blocking layer that blocks the intrusion of ammonia (ammonium ions) into the polarizer and can contribute to the suppression of discoloration. Specifically, when the moisture permeability of the laminated film is too high, it may be difficult to ensure extremely high moisture resistance. Therefore, by combining such a blocking layer, it is possible to significantly suppress discoloration while ensuring extremely high moisture resistance. On the other hand, the moisture permeability of the retardation layer at 40 °C and 92% RH is, for example, 50 g / m 2 ·24 h or more. When the retardation layer has a laminated structure of two or more layers, the moisture permeability of the retardation layer refers to the moisture permeability of the laminated structure that may include an adhesive layer.

[0045] The retardation layer can be composed of any suitable material as long as it can satisfy the above characteristics. Specifically, the retardation layer may be a resin film (a stretched resin film), or may be an alignment cured layer of a liquid crystal compound (a liquid crystal alignment cured layer). Preferably, the retardation layer is composed of a resin film (a stretched resin film). In this case, the thickness of the retardation layer is preferably 10 μm or more and 70 μm or less, more preferably 20 μm or more and 60 μm or less.

[0046] Typical examples of the resin constituting the resin film include polycarbonate resins or polyester carbonate resins (hereinafter sometimes simply referred to as polycarbonate resins). As the polycarbonate resin, any appropriate polycarbonate resin can be used as long as the desired moisture permeability can be obtained. For example, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri- or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from an alicyclic dimethanol and / or a structural unit derived from di-, tri- or polyethylene glycol; more preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri- or polyethylene glycol. The polycarbonate resin may optionally contain structural units derived from other dihydroxy compounds. The retardation layer can be formed by stretching a film composed of the polycarbonate resin as described above under any appropriate stretching conditions. Details of the polycarbonate resin and the method for forming the retardation layer are described, for example, in JP-A-2014-10291, JP-A-2014-26266, JP-A-2015-212816, JP-A-2015-212817, JP-A-2015-212818, JP-A-2017-54093, and JP-A-2018-60014. The descriptions of these publications are incorporated herein by reference.

[0047] A-4. Others The thickness of the adhesive layer 40 is preferably 10 μm to 20 μm. The adhesive layer can be composed of any suitable adhesive. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and blending ratio of the monomers forming the base resin of the adhesive, as well as the blending amount of the crosslinking agent, reaction temperature, reaction time, etc., an adhesive having desired properties according to the purpose can be prepared. The base resin of the adhesive may be used alone or in combination of two or more. The base resin is preferably an acrylic resin (specifically, the adhesive layer is preferably composed of an acrylic adhesive).

[0048] B. Organic EL Display Device The above polarizing plate can be used in an organic EL display device. Therefore, the organic EL display device according to an embodiment of the present invention has the above polarizing plate.

[0049] FIG. 3 is a schematic cross-sectional view showing an outline of a state in which a polarizing plate is disposed on an organic EL panel in an organic EL display device according to one embodiment of the present invention. The polarizing plate (polarizing plate with a retardation layer) 100 is disposed such that the polarizer 10 is closer to the organic EL panel main body 70 than the laminated film 20. Specifically, the polarizing plate 100 is attached to the organic EL panel main body 70 by an adhesive layer 40.

[0050] The organic EL panel body 70 has a substrate 71, a circuit layer including a thin film transistor (TFT), etc., and an upper structure layer 72 including an organic light emitting diode (OLED), a sealing film for sealing the OLED, etc. For example, when a flexible substrate (e.g., a resin substrate) is used as the substrate 71, the obtained organic EL display device can achieve bending, buckling, folding, winding, etc. The upper structure layer 72 includes, for example, a nitrogen-containing layer (e.g., a nitride layer such as silicon nitride or silicon oxynitride), and ammonia (ammonium ions) can be generated from the upper structure layer 72. According to the above polarizer, decolorization can be suppressed in the organic EL display device. Further, the problem of decolorization can be solved without changing the design of the configuration of the organic EL panel body.

Example

[0051] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measuring methods for thickness and moisture permeability are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. 1. Thickness For a thickness of 10 μm or less, it was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). For a thickness exceeding 10 μm, it was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). 2. Moisture Permeability The moisture permeability was determined by the cup method (JIS Z 0208).

[0052] [Example 1] (Production of Polarizer) As the thermoplastic resin substrate, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) in a long shape, having a water absorption rate of 0.75% and a Tg of about 75°C was used. One side of the resin substrate was subjected to corona treatment. 100 parts by weight of a PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetylacetylated PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer Z410") at a weight ratio of 9:1, with 13 parts by weight of potassium iodide added thereto, was dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was applied to 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. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds in an oven at 130°C (air-assisted stretching treatment). Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilizing treatment). Next, the laminate was immersed in a dyeing bath at a liquid temperature of 30°C (an aqueous iodine solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with 100 parts by weight of water) for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer was 43.0% (dyeing treatment). Next, the laminate was immersed in a crosslinking bath at a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (crosslinking treatment). Thereafter, while the laminate was immersed in an aqueous boric acid solution at a liquid temperature of 70°C (boric acid concentration: 4.0% by weight, potassium iodide: 5.0% by weight), uniaxial stretching was performed in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds so that the total stretching ratio was 5.5 times (stretching treatment in water). Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Thereafter, while drying in an oven maintained at 90°C, the laminate was brought into contact with a SUS heating roll whose surface temperature was maintained at 75°C for about 2 seconds (drying shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the drying shrinkage treatment was 5.2%. In this way, a polarizer with a thickness of 5 μm was formed on the resin substrate.

[0053] (Preparation of Hard Coat Layer Forming Material) 50 parts by weight of an ultraviolet curable acrylate resin (manufactured by DIC Corporation, trade name "Lucidear 17-806", solid content 80%) was prepared. Per 100 parts by weight of the resin solid content of this resin, 3 parts by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name "OMNIRAD 907") and 0.05 parts by weight of a leveling agent (manufactured by DIC Corporation, trade name "GRANDIC PC4100", solid content 10%) were mixed to obtain a mixture. The obtained mixture was diluted with a mixed solvent of isopropyl alcohol (IPA) and cyclopentanone (CPN) at a mixing ratio of 65:35 by weight so that the solid content concentration became 36% to prepare a hard coat layer forming material.

[0054] (Production of Laminated Film) The obtained hard coat layer forming material (coating liquid) was coated on a 25-μm-thick TAC film (manufactured by Konica Minolta, trade name "KC2UA") using a bar coater. After drying the coating layer by heating the TAC film with the coating layer formed thereon at 80°C for 1 minute, ultraviolet rays with an integrated light amount of 300 mJ / cm 2 were irradiated with a high-pressure mercury lamp to cure the coating layer, and a laminated film with a thickness of 32 μm and a moisture permeability of 440 g / m 2 ·24 h at 40°C and 92% RH was obtained.

[0055] (Production of Film Constituting the Phase Difference Layer 1) Polymerization was carried out using a batch polymerization apparatus consisting 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 spiroglycol (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(A certain amount in mol) was charged. After replacing the inside of the reactor with nitrogen under reduced pressure, it was heated with a heat medium, and stirring was started when the internal temperature reached 100°C. After 40 minutes from the start of heating up, the internal temperature reached 220°C, and while controlling to maintain this temperature, reduced pressure was started and it was set to 13.3 kPa in 90 minutes after reaching 220°C. The phenol vapor by-produced along with the polymerization reaction was led to a reflux condenser at 100°C, the monomer components contained in a small amount in the phenol vapor were returned to the reactor, and the phenol vapor that did not condense was led to a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor to once restore the pressure to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating up and reduced pressure in the second reactor were started, and the internal temperature was set to 240°C and the pressure to 0.2 kPa in 50 minutes. Thereafter, the polymerization was allowed to proceed until a predetermined stirring power was reached. When the predetermined 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 strands were cut to obtain pellets.

[0056] The obtained polyester carbonate resin (pellets) was vacuum dried at 80°C for 5 hours, and then a film forming apparatus equipped with a single screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chill 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 143°C and a stretching ratio of 2.8 times to obtain a stretched film with a thickness of 47 μm and a moisture permeability of 75 g / m 2 ·24 h at 40°C and 92% RH. The Re(550) of the obtained stretched film was 147 nm, Re(450) / Re(550) was 0.86, and the Nz coefficient was 1.12.

[0057] (Production of polarizing plate) On the surface of the polarizer of the resin substrate / polarizer laminate obtained above, the laminated film obtained above was bonded via an ultraviolet curable adhesive (thickness after curing: 1.0 μm). Next, the resin substrate was peeled off from the polarizer, and the obtained retardation layer (stretched film) was bonded to this peeled surface via an acrylic adhesive layer with a thickness of 5 μm. At this time, the polarizer was bonded so that the absorption axis of the polarizer and the slow axis of the retardation layer formed an angle of 45°. Next, an adhesive layer with a thickness of 15 μm was formed on the surface of the retardation layer with an acrylic adhesive to obtain a polarizing plate.

[0058] [Example 2] A polarizing plate was obtained in the same manner as in Example 1, except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 50:50 was used in the preparation of the hard coat layer forming material. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40 °C and 92% RH was 380 g / m 2 ·24 h.

[0059] [Examples 3 and 4] A polarizing plate was obtained in the same manner as in Examples 1 and 2, except that the film constituting the retardation layer was produced by the method shown below. The thickness of the obtained stretched film was 37 μm, and the moisture permeability at 40 °C and 92% RH was 105 g / m 2 ·24 h, Re(550) was 144 nm, Re(450) / Re(550) was 0.86, and the Nz coefficient was 1.09.

[0060] (Production of the film constituting the retardation layer 2) A polyester carbonate resin (pellets) obtained in the same manner as in Example 1 except that 0.7 parts by mass of an acrylic resin (PMMA) was melt-kneaded was vacuum-dried at 80°C for 5 hours, and then using a film forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chill roll (set temperature: 120 - 130°C), and a winder, a long resin film with a thickness of 105 μm was produced. The obtained long resin film was stretched in the width direction at a stretching temperature of 138°C and a stretching ratio of 2.8 times to obtain a stretched film.

[0061] [Comparative Example 1] In the preparation of the hard coat layer forming material, a polarizing plate was obtained in the same manner as in Example 1 except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 30:70 was used. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40°C and 92% RH was 380 g / m 2 ·24h.

[0062] [Comparative Example 2] In the preparation of the hard coat layer forming material, a polarizing plate was obtained in the same manner as in Example 1 except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 20:80 was used. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40°C and 92% RH was 380 g / m 2 ·24h.

[0063] [Comparative Example 3] In the preparation of the hard coat layer forming material, a polarizing plate was obtained in the same manner as in Example 1 except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 10:90 was used. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40°C and 92% RH was 380 g / m 2 ·24h.

[0064] [Comparative Example 4] A polarizing plate was obtained in the same manner as in Example 3, except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 30:70 was used in the preparation of the hard coat layer forming material. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40 °C and 92% RH was 380 g / m 2 ·24 h.

[0065] [Comparative Example 5] A polarizing plate was obtained in the same manner as in Example 3, except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 20:80 was used in the preparation of the hard coat layer forming material. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40 °C and 92% RH was 380 g / m 2 ·24 h.

[0066] [Comparative Example 6] A polarizing plate was obtained in the same manner as in Example 3, except that a mixed solvent in which IPA and CPN were mixed at a weight ratio of 10:90 was used in the preparation of the hard coat layer forming material. The thickness of the obtained laminated film was 33 μm, and the moisture permeability at 40 °C and 92% RH was 380 g / m 2 ·24 h.

[0067] [Comparative Examples 7 and 8] A polarizing plate was obtained in the same manner as in Examples 1 and 2, except that the liquid crystal alignment cured layer shown below was used as the retardation layer.

[0068] (Preparation of the liquid crystal alignment cured layer constituting the retardation layer) 55 parts of the compound represented by formula (I), 25 parts of the compound represented by formula (II), and 20 parts of the compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN). After that, the mixture was heated to 60 °C, stirred and dissolved. After dissolution was confirmed, the mixture was returned to room temperature, 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 part of Megafac F-554 (manufactured by DIC Corporation), and 0.1 part of p-methoxyphenol (MEHQ) were added, and stirring was further carried out to obtain a solution. The solution was transparent and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, a polyimide solution for an alignment film was applied to a glass substrate with a thickness of 0.7 mm by spin coating method, dried at 100 °C for 10 minutes, and then fired at 200 °C for 60 minutes to obtain a coating film. The obtained coating film was subjected to rubbing treatment to form an alignment film. The rubbing treatment was carried out using a commercially available rubbing apparatus. The polymerizable composition obtained above was applied to the substrate (substantially the alignment film) by spin coating method and dried at 100 °C for 2 minutes. After the obtained coating film was cooled to room temperature, it was irradiated with ultraviolet rays for 30 seconds at an intensity of 30 mW / cm 2 to obtain a liquid crystal alignment cured layer. The thickness of the obtained liquid crystal alignment cured layer was 3 μm, the moisture permeability at 40 °C and 92% RH was 815 g / m 2 ·24 h, the in-plane retardation Re(550) was 130 nm, and Re(450) / Re(550) was 0.851.

[0069] [Chemical formula] [Chemical formula]

[0070] [Comparative Examples 9, 10, and 11] A polarizing plate was obtained in the same manner as in Comparative Examples 1, 2, and 3 except that the liquid crystal alignment cured layer was used as a retardation layer.

[0071] For the examples and comparative examples, the following evaluations were carried out. The evaluation results are summarized in Table 1. [Evaluation] 1. Structure of the laminated film The cross-section of the obtained laminated film was observed with a transmission electron microscope (TEM) (magnification: 10,000 times), the laminated structure was confirmed, and the thickness of the layer on the TAC film (base material) was measured. 2. Change in water vapor transmission rate of the laminated film The obtained laminated film was placed in an environment of 65°C and 95% RH for 48 hours (humidification treatment). The water vapor transmission rate of the laminated film after the humidification treatment at 40°C and 92% RH was measured. 3. Transmittance change 1 (ammonia decolorization) The obtained polarizing plate was bonded to a non-alkali glass plate with a silicon oxynitride film having a thickness of 500 nm formed on the surface, and then this was placed in an environment of 65°C and 95% RH for 48 hours (humidification test). The transmittance Ts of the polarizing plate before and after the humidification test was measured using an ultraviolet-visible spectrophotometer ("LPF-2000" manufactured by Otsuka Electronics Co., Ltd.), and the transmittance change ΔTs (ΔTs = Ts after the humidification test - Ts before the humidification test) was calculated. In addition, by subjecting the non-alkali glass plate with the silicon oxynitride film formed thereon to the humidification test, generation of ammonia was confirmed. 4. Transmittance change 2 (moisture resistance) The obtained polarizing plate was bonded to a non-alkali glass plate, and then this was placed in an environment of 65°C and 95% RH for 336 hours (humidification test). The transmittance Ts of the polarizing plate before and after the humidification test was measured using an ultraviolet-visible spectrophotometer ("LPF-2000" manufactured by Otsuka Electronics Co., Ltd.), and the transmittance change ΔTs (ΔTs = Ts after the humidification test - Ts before the humidification test) was calculated.

[0072]

Table 1

[0073] In each example and comparative example, formation of the intermediate layer was confirmed by TEM observation. In each example, it was confirmed that the transmittance change ΔTs was within the range of ±3%.

Industrial applicability

[0074] The polarizing plate according to an embodiment of the present invention is suitably used, for example, in an organic EL display device.

Explanation of Signs

[0075] 10 Polarizer 20 Laminated film 30 Retardation layer 40 Adhesive layer 100 Polarizing plate

Claims

1. A polarizer having a first major surface and a second major surface facing each other, a laminated film disposed on the first major surface side of the polarizer and including a base material and a hard coat layer in this order from the polarizer side, and a retardation layer disposed on the second major surface side of the polarizer, The water vapor permeability of the laminated film is 600 g / m ２ ·24 h or less, and wherein a change rate of moisture permeability of the laminated film by placing the laminated film in an environment of 65° C. and 95% RH for 48 hours is 1.1 or more and 1.5 or less, The moisture permeability of the retardation layer is 200 g / m ２ ·24 h or less, a polarizing plate.

2. The polarizing plate according to claim 1, wherein a thickness of the hard coat layer is 1 μm or more.

3. The polarizing plate according to claim 1 or 2, wherein a thickness of the hard coat layer is 7 μm or less.

4. The polarizing plate according to any one of claims 1 to 3, wherein the laminated film includes an intermediate layer containing components derived from the base material and components derived from the hard coat layer between the base material and the hard coat layer.

5. The polarizing plate according to any one of claims 1 to 4, wherein the retardation layer is disposed adjacent to the polarizer.

6. The polarizing plate according to any one of claims 1 to 5, wherein Re(450) / Re(550) of the retardation layer is 0.8 or more and less than 1.

7. The polarizing plate according to any one of claims 1 to 6, wherein a single transmittance of the polarizer is 43.0% or more.

8. The polarizing plate according to any one of claims 1 to 7, wherein a thickness of the polarizer is 10 μm or less.

9. An organic electroluminescence display device having the polarizing plate according to any one of claims 1 to 8.

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