JP7702364B2 - Polarizing plate and organic electroluminescence display device - Google Patents

Description

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

In recent years, with the spread of thin displays, displays equipped with organic EL panels (organic EL display devices) have been proposed. Because organic EL panels have a highly reflective metal layer, they are prone to problems such as external light reflection and background glare. It is known that these problems can be prevented by providing a polarizing plate with a retardation layer, which combines a polarizing plate and a retardation plate, on the viewing side of the organic EL panel body (for example, Patent Document 1 and Patent Document 2).

JP 2002-372622 A Patent No. 3325560

As flat panel displays become more widespread, organic EL display devices may be required to have extremely high moisture resistance, and polarizing plates may also be required to have extremely high moisture resistance. Furthermore, polarizing plates installed in organic EL display devices are prone to discoloration, and discoloration tends to be accelerated in high humidity environments.

The present invention was made to solve the above problems, and its main objective is to provide a polarizing plate with extremely excellent durability.

A polarizing plate according to an embodiment of the present invention comprises a polarizer having a first main surface and a second main surface facing each other, a laminate film disposed on the first main surface side of the polarizer and including a substrate 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, wherein the moisture permeability of the laminate film is 600 g/ ^m2 ·24 h or less, a rate of change in the moisture permeability of the laminate film caused by placing the laminate film in an environment of 65° C. and 95% RH for 48 hours is 1.5 or less, and the moisture permeability of the retardation layer is 200 g/ ^m2 ·24 h or less.
In one embodiment, the rate of change is 1.1 or greater.
In one embodiment, the hard coat layer has a thickness of 1 μm or more.
In one embodiment, the hard coat layer has a thickness of 7 μm or less.
In one embodiment, the laminate film includes an intermediate layer between the substrate and the hard coat layer, the intermediate layer including a component derived from the substrate and a component derived from 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 polarizer has a single transmittance of 43.0% or more.
In one embodiment, the polarizer has a thickness of 10 μm or less.
According to another aspect of the present invention, there is provided an organic electroluminescence display device, the organic electroluminescence display device having the above polarizing plate.

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

1 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a schematic configuration of a laminate film of the polarizing plate shown in FIG. 1 . 1 is a schematic cross-sectional view showing an organic EL panel and a polarizing plate disposed in the organic EL display device according to one embodiment of the present invention.

The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. In addition, in order to make the description clearer, the drawings may show the width, thickness, shape, etc. of each part more diagrammatically than in the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

(Definition of terms and symbols)
The definitions of terms and symbols used in this specification are as follows.
(1) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular 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 retardation measured with light having a wavelength of λ nm at 23° C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23° C. Re(λ) is calculated by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Retardation in the thickness direction (Rth)
"Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23° C. For example, "Rth(550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23° C. Rth(λ) is calculated by the formula: Rth(λ)=(nx-nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz Coefficient The Nz coefficient is calculated by Nz=Rth/Re.
(5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise angles with respect to a reference direction. Thus, for example, "45°" means ±45°.

A. Polarizing Plate FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a polarizing plate according to one 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. A polarizing plate (polarizing plate with retardation layer) 100 has a polarizer 10 having a first main surface 10a and a second main surface 10b facing each other, a laminated film 20 arranged on the first main surface 10a side of the polarizer 10, and a retardation layer 30 and a pressure-sensitive adhesive layer 40 arranged on the second main surface 10b side of the polarizer 10. The laminated film 20 includes a substrate 21 and a hard coat layer 22 in this order from the polarizer 10 side, and the substrate 21 can function as a protective layer for the polarizer 10. The polarizing plate 100 is typically arranged so that the laminated film 20 is closer to the viewing side than the polarizer 10 in an organic EL display device.

In the illustrated example, the retardation layer 30 is a single layer, but unlike 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 with different optical properties (e.g., refractive index properties, in-plane retardation, Nz coefficient, photoelastic coefficient). 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 for 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 to each other, but also being adjacent to each other via an adhesive layer described later.

Each member constituting the polarizing plate may be laminated via any suitable adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and a pressure-sensitive adhesive 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 a pressure-sensitive adhesive layer (e.g., an acrylic pressure-sensitive adhesive). 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 pressure-sensitive adhesive layer is preferably 1 μm to 10 μm.

The adhesive layer 40 arranged on the second main surface 10b side of the polarizer 10 allows the polarizing plate 100 to be attached to the organic EL panel body, for example. Although not shown, in practice, a release liner is attached to the surface of the adhesive layer 40. The release liner can be temporarily attached until the polarizing plate is used. By using the release liner, for example, the adhesive layer is protected and the polarizing plate can be formed into a roll.

The polarizing plate may be long or in the form of a sheet. Here, "long" refers to an elongated shape in which the length is sufficiently long compared to the width, for example, a long and thin shape in which the length is 10 times or more, preferably 20 times or more, the width. A long polarizing plate can be wound into a roll.

A-1. Polarizer The polarizer is typically a film containing a dichroic material (typically, iodine).

For example, from the viewpoint of thinning, the thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, even more preferably 10 μm or less, and particularly preferably 8 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more.

The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 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 even more preferably 44.5% or more. In a polarizer having a high single transmittance, the above-mentioned decolorization problem may become more pronounced. On the other hand, the single transmittance is, for example, 48.0% or less, and 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 even more preferably 99.9% or more.

The single transmittance is typically a Y value measured using an ultraviolet-visible spectrophotometer and subjected to luminosity correction. The polarization degree is typically calculated by the following formula based on the parallel transmittance Tp and the crossed transmittance Tc measured using an ultraviolet-visible spectrophotometer and subjected to luminosity correction.
Degree of polarization (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

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

A typical method for producing a polarizer from the above-mentioned single-layer resin film includes subjecting the resin film to a dyeing process using a dichroic substance such as iodine or a dichroic dye, and a stretching process. 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 an ethylene-vinyl acetate copolymer-based partially saponified film is used. The method may further include an insolubilization process, a swelling process, a crosslinking process, etc. Such a production method is well known and commonly used in the industry, so a detailed description is omitted.

The polarizer obtained using the laminate can be produced, for example, by using a laminate of a resin substrate and a resin film or resin layer (typically, a PVA-based resin layer). Specifically, a PVA-based resin solution is applied to a resin substrate, and dried to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and the laminate is stretched and dyed to make the PVA-based resin layer into a polarizer. In this embodiment, preferably, a PVA-based resin layer containing a halide and a PVA-based resin is formed on one side of the resin substrate. The stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, the stretching may further include, as necessary, stretching the laminate in air at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, preferably, the laminate is subjected to a drying and shrinking treatment in which the laminate is heated while being transported in the longitudinal direction to shrink the laminate 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 the auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it is possible to increase the crystallinity of PVA, and high optical properties can be achieved. In addition, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in the orientation or dissolution of PVA when immersed in water in the subsequent dyeing or stretching process can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the orientation disorder and the decrease in the orientation of PVA molecules can be suppressed compared to when the PVA-based resin layer does not contain a halide, and high optical properties can be achieved. Furthermore, 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 peeled surface obtained by peeling the resin substrate from the obtained resin substrate/polarizer laminate, or on the surface opposite to the peeled surface. Details of the manufacturing method of such a polarizer are described, for example, in JP 2012-73580 A and Japanese Patent No. 6470455. The entire disclosures of these publications are incorporated herein by reference.

A-2. Laminated Film In one embodiment, as shown in Fig. 2, the laminated film 20 has a substrate (protective layer) 21 and a hard coat layer 22, and an intermediate layer 23 may be formed between the substrate 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 closer to the viewing side than the substrate 21. The hard coat layer 22 may function as another functional layer, such as an anti-reflection layer, an anti-sticking layer, or an anti-glare layer.

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

The moisture permeability of the laminated film at 40°C and 92% RH is 600 g/ ^m2 ·24h or less, preferably 550 g/ ^m2 ·24h or less, more preferably 500 g/ ^m2 ·24h or less, and even more preferably 450 g/ ^m2 ·24h or less. On the other hand, the moisture permeability of the laminated film at 40°C and 92% RH is preferably 300 g/ ^m2 ·24h or more, preferably 320 g/ ^m2 ·24h or more, and more preferably 340 g/ ^m2 ·24h or more.

The moisture permeability of the laminated film subjected to the humidification treatment at 40°C and 92% RH is preferably 800 g/ ^m2 ·24h or less, more preferably 700 g/ ^m2 ·24h or less, and even more preferably 600 g/ ^m2 ·24h or less. The change rate of 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.

The moisture permeability of the laminated film subjected to the humidification treatment at 40°C and 92% RH is preferably 400 g/ ^m2 ·24h or more, more preferably 450 g/ ^m2 ·24h or more, and even more preferably 500 g/ ^m2 ·24h or more. The rate of change in moisture permeability due to the humidification treatment (moisture permeability after the humidification treatment/moisture permeability before the humidification treatment) is preferably 1.1 or more, more preferably 1.2 or more. By using such a laminated film, decolorization can be suppressed. The present inventors have found that the main cause of the problem that the polarizing plate is easily decolorized when used in an organic EL display device is ammonia (substantially ammonium ion) which originates from the members constituting the organic EL panel and is easily generated in a high humidity environment, and that decolorization can be suppressed by discharging the ammonium ion that has entered the polarizing plate (polarizer). And, decolorization can be suppressed by arranging a member having high moisture permeability on one side (typically, the viewing side) of the polarizer. Specifically, decomposition of a dichroic material (typically, an iodine complex) contained in the polarizer can be suppressed.

The substrate may be made of any suitable film that can be used as a protective layer for a polarizer. Examples of materials constituting such a substrate (film) include cellulose-based resins such as triacetyl cellulose (TAC), cycloolefin-based resins such as polynorbornene, polycarbonate-based resins, (meth)acrylic 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 substrate.

The thickness of the substrate is, for example, 10 μm or more and 65 μm or less, and preferably 15 μm or more and 45 μm or less.

The hard coat layer is typically formed by applying a hard coat layer-forming material to the substrate and curing the applied layer. The hard coat layer-forming material typically includes a curable compound as a layer-forming component. Examples of the curing mechanism of the curable compound include a thermosetting type and a photocurable type. Examples of the curable compound include a monomer, an oligomer, and a prepolymer. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. Examples of the polyfunctional monomer or oligomer include a monomer or oligomer having two or more (meth)acryloyl groups, a urethane (meth)acrylate or an oligomer of a urethane (meth)acrylate, an epoxy-based monomer or oligomer, and a silicone-based monomer or oligomer.

The hard coat layer forming material may contain any suitable additive. Examples of additives include polymerization initiators, leveling agents, antiblocking agents, dispersion stabilizers, thixotropic agents, antioxidants, UV absorbers, defoamers, thickeners, dispersants, surfactants, catalysts, fillers, lubricants, and antistatic agents. The types, combinations, and amounts of additives may be appropriately set according to the purpose and desired properties.

When the curable compound is a thermosetting compound, the heating temperature is, for example, 60° C. to 140° C., and preferably 60° C. to 100° C. When the curable compound is a photocurable compound, the curing treatment is typically performed by ultraviolet ray irradiation. The integrated light amount of the ultraviolet ray irradiation is, for example, 100 mJ/cm ² to 300 mJ/cm ^2. The ultraviolet ray irradiation and heating may be combined.

The thickness of the hard coat layer is preferably 1 μm or more, more preferably 1.5 μm or more, and even more preferably 2 μm or more. Such a thickness can 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 even more preferably 5 μm or less. With such a thickness, the above moisture permeability can be satisfactorily satisfied, and for example, discoloration can be suppressed. The scratch resistance can be evaluated, for example, by rubbing the surface of the hard coat layer with a cylinder with steel wool #0000 attached to the bottom surface by reciprocating 1000 times at a speed of about 100 mm per second under a load of 1.0 kg, and then visually checking the degree of scratches on the surface of the hard coat layer.

The intermediate layer may contain components derived from the substrate and components derived from the hard coat layer. Specifically, the intermediate layer may be formed by the components forming the substrate and the components forming the hard coat layer being compatible (mixed). For example, when the substrate contains TAC, the components derived from the substrate include TAC, acetic acid, and cellulose. In the laminate film, the interface between the intermediate layer and the substrate and the interface between the intermediate layer and the hard coat layer can be confirmed by observation with a transmission electron microscope (TEM).

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.

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, and more preferably 0.6 or more. With such a thickness ratio, for example, it is possible to suppress changes 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, and more preferably 0.9 or less. With such a thickness ratio, the above moisture permeability can be satisfactorily satisfied, and for example, discoloration can be suppressed.

The intermediate layer can be formed, for example, by adding a good solvent capable of dissolving the substrate to a solvent that may be included in the hard coat layer-forming material. Specifically, a part of the components included in the hard coat layer-forming material (typically the solvent) mixes with the substrate and/or penetrates the substrate, and the components forming the substrate and the components forming the hard coat layer become compatible (mixed), forming the intermediate layer.

Examples of solvents that may be included in the hard coat layer forming material include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, TBA (tertiary 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 solids concentration of the hard coat layer forming material is, for example, 20% by weight or more and 50% by weight or less, and is preferably 30% by weight or more and 45% by weight or less.

As a good solvent capable of dissolving the above-mentioned substrate, for example, a solvent in which the amount of substrate (solute) dissolved per 100 parts by weight of the solvent is 30 parts by weight or more is used. As a specific example, when the substrate contains TAC, for example, cyclopentanone (for example, the amount of TAC dissolved per 100 parts by weight of cyclopentanone is 40 parts by weight), MEK (for example, the amount of TAC dissolved per 100 parts by weight of MEK is 60 parts by weight), cyclohexanone, methyl acetate, and ethyl acetate are preferably used as good solvents capable of dissolving the substrate.

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

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 anti-reflection properties to an organic EL display device. The retardation layer typically exhibits a relationship of nx>ny=nz in terms of refractive index properties. 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 completely equal, but also the case where they are substantially equal. Specifically, there may be cases where ny>nz or ny<nz. 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 an extremely excellent reflection hue can be obtained.

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, and more preferably 0.8 or more and 0.95 or less. With such a configuration, it is possible to realize very excellent anti-reflection properties.

The angle between 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 this range, an organic EL display device with excellent anti-reflection properties can be obtained by using a λ/4 plate as the retardation layer as described above.

The moisture permeability of the retardation layer at 40°C and 92% RH is 200g/ ^m2 ·24h or less, preferably 150g/ ^m2 ·24h or less, more preferably 100g/ ^m2 ·24h or less. Such a retardation layer can function as a blocking layer that blocks the intrusion of ammonia (ammonium ion) into the polarizer, and can contribute to suppressing decoloration. Specifically, if the moisture permeability of the laminated film is too high, it may be difficult to ensure extremely high moisture resistance, so by combining such a blocking layer, decoloration can be significantly suppressed 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, 50g/ ^m2 ·24h or more. In addition, 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.

The retardation layer may be made of any suitable material as long as it satisfies the above-mentioned characteristics. Specifically, the retardation layer may be a resin film (stretched resin film) or a liquid crystal compound alignment solidification layer (liquid crystal alignment solidification layer). Preferably, the retardation layer is made of a resin film (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.

Representative examples of resins constituting the resin film include polycarbonate-based resins or polyester carbonate-based resins (hereinafter, sometimes simply referred to as polycarbonate-based resins). As the polycarbonate-based resin, any appropriate polycarbonate-based resin can be used as long as the desired moisture permeability is obtained. For example, the polycarbonate-based resin contains 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 an alicyclic diol, an alicyclic dimethanol, a di-, tri- or polyethylene glycol, and an alkylene glycol or a spiro glycol. Preferably, the polycarbonate resin comprises a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and/or a structural unit derived from a di-, tri- or polyethylene glycol; more preferably, a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, and a structural unit derived from a di-, tri- or polyethylene glycol. The polycarbonate resin may comprise a structural unit derived from other dihydroxy compounds as required. The retardation layer can be formed by stretching the film composed of the above-mentioned polycarbonate resin under any suitable stretching conditions. Details of the polycarbonate resin and the method of 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 in these publications are incorporated herein by reference.

A-4. Others The thickness of the adhesive layer 40 is preferably 10 μm to 20 μm. The adhesive layer may be made 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 compounding ratio of the monomers forming the base resin of the adhesive, as well as the compounding 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 types. The base resin is preferably an acrylic resin (specifically, the adhesive layer is preferably made of an acrylic adhesive).

B. Organic EL Display Device The polarizing plate may be used in an organic EL display device. Accordingly, an organic EL display device according to an embodiment of the present invention includes the polarizing plate.

Figure 3 is a schematic cross-sectional view showing an outline of a state in which a polarizing plate is arranged 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 arranged so that the polarizer 10 is closer to the organic EL panel body 70 than the laminated film 20. Specifically, the polarizing plate 100 is attached to the organic EL panel body 70 by an adhesive layer 40.

The organic EL panel body 70 has a substrate 71 and an upper structure layer 72 including a circuit layer including thin film transistors (TFTs) and the like, organic light emitting diodes (OLEDs), and a sealing film for sealing the OLEDs. For example, when a flexible substrate (e.g., a resin substrate) is used as the substrate 71, the resulting organic EL display device can be curved, bent, folded, rolled up, and the like. 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. The polarizing plate can suppress decoloration in the organic EL display device. In addition, the decoloration problem can be solved without changing the design of the configuration of the organic EL panel body.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The thickness and moisture permeability were measured as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight.
1. Thickness Thicknesses of 10 μm or less were measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"), and thicknesses of more than 10 μm were measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name "KC-351C").
2. Moisture Permeability The moisture permeability was determined by the cup method (JIS Z 0208).

[Example 1]
(Preparation of Polarizer)
The thermoplastic resin substrate used was a long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of about 75° C. One side of the resin substrate was subjected to a corona treatment.
A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4,200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "GOHSEFFIMER Z410") in a weight ratio of 9:1, and dissolving the mixture in water.
The above PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.
The resulting laminate was uniaxially stretched at its free end to 2.4 times its original size in the machine direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130° C. (auxiliary air stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment).
Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) having a liquid temperature of 30° C. for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be 43.0% (dyeing treatment).
Next, the plate was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).
Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4.0% by weight, potassium iodide concentration: 5.0% by weight) at a liquid temperature of 70° C., and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment).
Thereafter, while drying in an oven maintained at 90° C., the laminate was brought into contact with a SUS heated roll having a surface temperature maintained at 75° C. for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%.
In this manner, a polarizer having a thickness of 5 μm was formed on the resin substrate.

(Preparation of Hard Coat Layer-Forming Material)
50 parts by weight of ultraviolet-curable acrylate resin (DIC Corporation, trade name "Luxidia 17-806", solid content 80%) was prepared. 3 parts by weight of photopolymerization initiator (IGM Resins, trade name "OMNIRAD907") and 0.05 parts by weight of leveling agent (DIC Corporation, trade name "GRANDIC PC4100", solid content 10%) were mixed per 100 parts by weight of resin solid content of this resin to obtain a mixture. The obtained mixture was diluted with a mixed solvent of isopropyl alcohol (IPA) and cyclopentanone (CPN) in a mixing ratio of 65:35 by weight so that the solid content concentration was 36%, to prepare a hard coat layer forming material.

(Preparation of Laminated Film)
The obtained hard coat layer forming material (coating liquid) was applied onto a 25 μm thick TAC film (Konica Minolta, Inc., product name "KC2UA") using a bar coater. The TAC film on which the coating layer was formed was heated at 80° C. for 1 minute to dry the coating layer, and then the coating layer was cured by irradiating it with ultraviolet light from a high pressure mercury lamp at an integrated light quantity of 300 mJ/cm ² to obtain 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.

(Preparation of film constituting retardation 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)fluoren-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 x 10 ^-2 parts by mass (6.78 x 10 ^-5 mol) of calcium acetate monohydrate as a catalyst were charged. After the inside of the reactor was replaced with nitrogen under reduced pressure, it was heated with a heat medium, and stirring was started when the inside temperature reached 100°C. The internal temperature was allowed to reach 220°C 40 minutes after the start of the temperature rise, and the pressure was simultaneously reduced to 13.3 kPa in 90 minutes after the temperature reached 220°C. Phenol vapor by-produced during the polymerization reaction was led to a reflux condenser at 100°C, a small amount of monomer components contained in the phenol vapor were returned to the reactor, and uncondensed phenol vapor was led to a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature rise and pressure reduction 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, 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 polyester carbonate resin produced was extruded into water, and the strands were cut to obtain pellets.

The obtained polyester carbonate resin (pellets) was vacuum dried at 80 ° C for 5 hours, and then a long resin film having a thickness of 135 μm was produced using a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250 ° C), a T-die (width 200 mm, setting temperature: 250 ° C), a chill roll (setting temperature: 120 to 130 ° C) and a winder. 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 having 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.

(Preparation of Polarizing Plate)
The laminated film obtained above was attached to the polarizer surface of the resin substrate/polarizer laminate obtained above via an ultraviolet-curable adhesive (thickness after curing: 1.0 μm). Next, the resin substrate was peeled off from the polarizer, and the retardation layer (stretched film) obtained above was attached to this peeled surface via an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm. At this time, the polarizer was attached so that the absorption axis of the polarizer and the slow axis of the retardation layer were at an angle of 45°. Next, a pressure-sensitive adhesive layer having a thickness of 15 μm was formed on the surface of the retardation layer using an acrylic pressure-sensitive adhesive to obtain a polarizing plate.

[Example 2]
A polarizing plate was obtained in the same manner as in Example 1, except that a mixed solvent of IPA and CPN in 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.

[Examples 3 and 4]
A polarizing plate was obtained in the same manner as in Examples 1 and 2, except that a film constituting a retardation layer was prepared by the following method. The thickness of the obtained stretched film was 37 μm, 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.

(Preparation of film constituting retardation layer 2)
A polyester carbonate-based resin (pellet) 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 a long resin film having a thickness of 105 μm was produced using a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120 to 130°C) and a winder. The obtained long resin film was stretched in the width direction at a stretching temperature of 138°C and a stretch ratio of 2.8 times to obtain a stretched film.

[Comparative Example 1]
A polarizing plate was obtained in the same manner as in Example 1, except that a mixed solvent of IPA and CPN in 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.

[Comparative Example 2]
A polarizing plate was obtained in the same manner as in Example 1, except that a mixed solvent of IPA and CPN in 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.

[Comparative Example 3]
A polarizing plate was obtained in the same manner as in Example 1, except that a mixed solvent of IPA and CPN in 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.

[Comparative Example 4]
A polarizing plate was obtained in the same manner as in Example 3, except that a mixed solvent of IPA and CPN in 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.

[Comparative Example 5]
A polarizing plate was obtained in the same manner as in Example 3, except that in the preparation of the hard coat layer-forming material, a mixed solvent in which IPA and CPN were mixed at a mixing ratio of 20:80 by weight 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 ·24 h.

[Comparative Example 6]
A polarizing plate was obtained in the same manner as in Example 3, except that a mixed solvent of IPA and CPN in 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.

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

(Preparation of Liquid Crystal Alignment Solidified Layer Constituting 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), and then the mixture was heated to 60°C and stirred to dissolve. After dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Co., Ltd.), 0.2 parts of Megafac F-554 (manufactured by DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) were added and further stirred to obtain a solution. The solution was transparent and uniform. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, the polyimide solution for the alignment film was applied to a glass substrate having a thickness of 0.7 mm using a spin coat method, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The obtained coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing device. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating, and dried at 100°C for 2 minutes. The obtained coating film was cooled to room temperature, and then irradiated with ultraviolet light at an intensity of 30 mW/ ^cm2 for 30 seconds using a high-pressure mercury lamp to obtain a liquid crystal alignment solidified layer. The obtained liquid crystal alignment solidified layer had a thickness of 3 μm, a moisture permeability at 40°C and 92% RH of 815 g/ ^m2 ·24h, an in-plane retardation Re(550) of 130 nm, and a Re(450)/Re(550) of 0.851.

[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 above liquid crystal alignment solidified layer was used as a retardation layer.

The following evaluations were carried out for the Examples and Comparative Examples. 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) to confirm the laminated structure and to measure the thickness of the layer on the TAC film (substrate).
2. Change in Moisture Permeability of Laminate Film The laminate film obtained was left in an environment of 65° C. and 95% RH for 48 hours (humidification treatment). The moisture permeability of the laminate film after the humidification treatment at 40° C. and 92% RH was measured.
3. Change in transmittance 1 (ammonia decolorization)
The obtained polarizing plate was attached to a non-alkali glass plate having a silicon oxynitride film formed on its surface with a thickness of 500 nm, and then the plate 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 (Otsuka Electronics Co., Ltd., “LPF-2000”), and the change in transmittance ΔTs (ΔTs=Ts after humidification test−Ts before humidification test) was calculated. It should be noted that the generation of ammonia was confirmed by subjecting the non-alkali glass plate having the silicon oxynitride film formed thereon to the humidification test.
4. Change in transmittance 2 (moisture resistance)
The obtained polarizing plate was attached to a non-alkali glass plate, and then left 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 (Otsuka Electronics Co., Ltd., “LPF-2000”), and the change in transmittance ΔTs (ΔTs=Ts after the humidification test−Ts before the humidification test) was calculated.

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

The polarizing plate according to the embodiment of the present invention is suitable for use in, for example, an organic EL display device.

REFERENCE SIGNS LIST 10 Polarizer 20 Laminated film 30 Retardation layer 40 Pressure-sensitive adhesive layer 100 Polarizing plate

Claims (9)

a polarizer having a first principal surface and a second principal surface opposed to each other;
a laminate film disposed on the first main surface side of the polarizer, the laminate film including a substrate and a hard coat layer in this order from the polarizer side;
a retardation layer disposed on the second main surface side of the polarizer,
The moisture permeability of the laminated film is 600 g/ ^m2 ·24 h or less,
a change in moisture permeability of the laminated film when the laminated film is placed 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/ ^m2 ·24 h or less.
Polarizing plate. The polarizing plate according to claim 1 , wherein the hard coat layer has a thickness of 1 μm or more. 3. The polarizing plate according to claim 1 , wherein the hard coat layer has a thickness of 7 μm or less. The polarizing plate according to claim 1 , wherein the laminate film includes an intermediate layer between the substrate and the hard coat layer, the intermediate layer containing a component derived from the substrate and a component derived from the hard coat layer. The polarizing plate according to claim 1 , wherein the retardation layer is disposed adjacent to the polarizer. The polarizing plate according to claim 1 , wherein Re(450)/Re(550) of the retardation layer is 0.8 or more and less than 1 . The polarizing plate according to claim 1 , wherein the polarizer has a single transmittance of 43.0% or more. The polarizing plate according to claim 1 , wherein the polarizer has a thickness of 10 μm or less. An organic electroluminescence display device comprising the polarizing plate according to claim 1 .

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