WO2022049910A1

WO2022049910A1 - Polarizing plate, polarizing plate with phase difference layer, and organic electroluminescent display device

Info

Publication number: WO2022049910A1
Application number: PCT/JP2021/027001
Authority: WO
Inventors: 善則南川; 真由美森崎; 景亮後藤
Original assignee: 日東電工株式会社
Priority date: 2020-09-02
Filing date: 2021-07-19
Publication date: 2022-03-10
Also published as: CN116057608A; KR20230056688A; TW202220843A; JP7411520B2; JP2022042217A; JP2024029094A

Abstract

Provided are: a polarizing plate in which decolorization is remarkably suppressed when applied to an organic EL display device; and a polarizing plate with a phase difference layer. A polarizing plate according to an embodiment of the present invention includes a polyvinyl alcohol resin layer, a protective layer provided on the visible side of the polyvinyl alcohol resin layer, and an adhesive layer disposed on the reverse side from the visible side of the polyvinyl alcohol resin layer. The polyvinyl alcohol resin layer includes a first polyvinyl alcohol resin layer that functions as a polarizer, and a second polyvinyl alcohol resin layer provided on the visible side of the first polyvinyl alcohol resin layer. The thickness of the second polyvinyl alcohol resin layer is 0.03-2 μm. The boric acid concentration on the surface of the polyvinyl alcohol resin layer on the reverse side from the visible side is higher than the boric acid concentration on the visible-side surface, and the difference therebetween is 0.3 wt% or more. The moisture permeability of the protective layer on the visible side is at least 200 g/m²•24 h.

Description

Polarizing plate, polarizing plate with retardation layer and organic electroluminescence display device

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

In recent years, with the spread of thin displays, displays (organic EL display devices) equipped with organic EL panels 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 circular polarizing plate on the visual recognition side (for example, Patent Documents 1 to 3). However, there is a problem that the circular polarizing plate provided in the organic EL display device (substantially, the polarizing plate included in the circular polarizing plate) is easily decolorized.

Japanese Patent Application Laid-Open No. 2003-31239 Japanese Patent Application Laid-Open No. 2002-372622 Japanese Patent No. 3325560

The present invention has been made to solve the above-mentioned conventional problems, and a main object thereof is to provide a polarizing plate in which decolorization is remarkably suppressed when applied to an organic EL display device and a polarizing plate with a retardation layer. To do.

The polarizing plate according to the embodiment of the present invention is arranged on the polyvinyl alcohol-based resin layer, the protective layer provided on the visible side of the polyvinyl alcohol-based resin layer, and the side opposite to the visible side of the polyvinyl alcohol-based resin layer. Includes a pressure-sensitive adhesive layer. The polyvinyl alcohol-based resin layer comprises a first polyvinyl alcohol-based resin layer that functions as a polarizing element and a second polyvinyl alcohol-based resin layer provided on the visible side of the first polyvinyl alcohol-based resin layer. include. The thickness of the second polyvinyl alcohol-based resin layer is 0.03 μm to 2 μm; the boric acid concentration on the surface of the polyvinyl alcohol-based resin layer opposite to the visible side is larger than the boric acid concentration on the visible side surface. Moreover, the difference is 0.3% by weight or more; the moisture permeability of the protective layer on the visual recognition side is ²⁰⁰ g / m 2.24 h or more.
In one embodiment, the boric acid concentration of the first polyvinyl alcohol-based resin layer is 14% by weight or more.
In one embodiment, the first polyvinyl alcohol-based resin layer has a single transmittance of 42.5% or more; the ratio of the orthogonal absorbance A ₅₅₀ at a wavelength of 550 nm to the orthogonal absorbance A ₂₁₀ at a wavelength of 210 nm (A). ₅₅₀ / A ₂₁₀ ) is 1.4 or more; the ratio of the orthogonal absorbance A ₄₇₀ at a wavelength of 470 nm to the orthogonal absorbance A ₆₀₀ at a wavelength of 600 nm (A ₄₇₀ / A ₆₀₀ ) is 0.7 or more; and orthogonal b. The value is greater than -10.
In one embodiment, the iodine concentration of the polarizing element is 2% by weight to 10% by weight.
In one embodiment, the polarizing plate has an absolute value | ΔP | of a change in degree of polarization when exposed to ammonia vapor for 2 hours in an environment of 60 ° C. of 50% or less.
According to another aspect of the present invention, a polarizing plate with a retardation layer is provided. This polarizing plate with a retardation layer has the above-mentioned polarizing plate and a retardation layer.
According to yet another aspect of the present invention, an organic electroluminescence display device is provided. This organic electroluminescence display device includes the above-mentioned polarizing plate or the above-mentioned polarizing plate with a retardation layer.

According to the embodiment of the present invention, in the polyvinyl alcohol-based resin layer of the polarizing plate, a second polyvinyl alcohol-based resin layer is provided adjacent to the first polyvinyl alcohol-based resin layer that functions as a polarizing element, and a second polyvinyl alcohol-based resin layer is provided. By providing a concentration gradient such that the boric acid concentration on the visible side surface of the polyvinyl alcohol-based resin layer is smaller than the boric acid concentration on the surface opposite to the visible side of the first polyvinyl alcohol-based resin layer by a predetermined value or more. It is possible to realize a polarizing plate in which decolorization is significantly suppressed and a polarizing plate with a retardation layer when applied to an organic EL display device.

It is a schematic sectional drawing of the polarizing plate by one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. It was

A. Polarizer A-1. Overall Configuration of Polarizing Plate FIG. 1 is a schematic cross-sectional view of the polarizing plate according to one embodiment of the present invention. The polarizing plate 100 of the illustrated example includes a polyvinyl alcohol (PVA) -based resin layer 10, a protective layer (visual-viewing side protective layer) 30 provided on the visible side of the PVA-based resin layer 10, and a visible side of the PVA-based resin layer 10. Includes a pressure-sensitive adhesive layer 40 disposed on the opposite side of the surface. The PVA-based resin layer 10 includes a first PVA-based resin layer 11 that functions as a polarizing element, and a second PVA-based resin layer 12 provided on the visible side of the first PVA-based resin layer 11. The second PVA-based resin layer 12 can also function as an adhesive layer for bonding the first PVA-based resin layer 11 and the visual-viewing side protective layer 30. Typically, the optical functional layer can be bonded via the pressure-sensitive adhesive layer 40. Typical examples of the optical functional layer include another protective layer (inner protective layer) and a retardation layer. The inner protective layer may preferably be omitted. When the optical functional layer is a retardation layer, a polarizing plate with a retardation layer is configured. The polarizing plate with a retardation layer will be described in Section B below. The polarizing plate 100 may be attached to the organic EL panel via the pressure-sensitive adhesive layer 40.

In the embodiment of the present invention, the boric acid concentration on the surface of the PVA-based resin layer 10 (substantially the first PVA-based resin layer 11) opposite to the visible side is the PVA-based resin layer 10 (substantially). The difference from the boric acid concentration on the visible side surface of the second PVA-based resin layer 12) (hereinafter, may be referred to as a boric acid concentration gradient) is 0.3% by weight or more. More specifically, the boric acid concentration of the first PVA-based resin layer is higher than the boric acid concentration of the second PVA-based resin layer, and therefore, the boric acid on the surface opposite to the visible side of the PVA-based resin layer. A boric acid concentration gradient is formed in which the concentration is larger than the boric acid concentration on the surface on the visual side. The boric acid concentration gradient is preferably 0.4% by weight or more, and more preferably 0.5% by weight or more. The boric acid concentration gradient can be, for example, 27% by weight or less. The present inventors faced a new problem that the polarizing plate and the polarizing plate with a retardation layer are decolorized when the polarizing plate and the polarizing plate with a retardation layer are applied to an organic EL display device, and the present inventors are keen on the problem. As a result of the examination, it was found that the cause of the decolorization was ammonia (substantially ammonium ion) generated from the organic EL panel. Furthermore, since the above-mentioned decolorization is suppressed as the boric acid concentration in the polarizing element is higher, it was discovered that the higher the boric acid concentration, the easier it is to block ammonium ions. Based on such findings, a second PVA-based resin layer is provided adjacent to the modulator (first PVA-based resin layer) to form a PVA-based resin layer having a two-layer structure, and the PVA-based resin layer can be visually recognized. By providing a concentration gradient such that the boric acid concentration on the side surface is smaller than the boric acid concentration on the surface opposite to the viewing side by a predetermined value or more, ammonium ions that invade the polarizing element from the organic EL panel side are blocked as much as possible. Moreover, it was found that the PVA-based resin layer on the visual recognition side (the side far from the organic EL panel) can easily discharge ammonium ions, and the new problem was solved. This is because the crosslink density of the PVA-based resin decreases as the distance from the organic EL panel increases, so that ammonium ions do not easily invade the polarizing element (first PVA-based resin layer), and even if they do, they are on the visual side. It is presumed that this is because it is easy to pull out. Further, by making the second PVA-based resin layer function as an adhesive for adhering the polarizing element and the protective layer, it is not necessary to provide the second PVA-based resin layer separately from the adhesive, and the thickness is reduced and manufactured. It is advantageous in terms of both efficiency and cost.

The boric acid concentration (at the time of application) of the second PVA-based resin layer is 1% by weight or less, preferably 0.8% by weight or less, more preferably 0.5% by weight or less, and further preferably 0. .2% by weight or less, particularly preferably substantially zero. When the concentration of the second PVA-based resin layer is in such a range, the above-mentioned desired boric acid concentration gradient is realized with a polarizing element having practical optical characteristics (first PVA-based resin layer). be able to. Here, the boric acid concentration of the substituent (first PVA-based resin layer) is preferably 15% by weight or more, more preferably 16% by weight or more, and further preferably 16% by weight to 26% by weight. be. When the boric acid concentration of the decoder is in such a range, practical optical characteristics can be obtained, and the desired boric acid concentration gradient can be realized with the second PVA-based resin layer. Further, it is possible to improve the appearance durability at the time of humidification while maintaining the ease of curl adjustment at the time of bonding well and suppressing the curl at the time of heating satisfactorily. The boric acid concentration can be determined using, for example, Fourier Transform Infrared Spectroscopy (FT-IR). Specifically, it is as follows. The second PVA-based resin layer is measured by total internal reflection attenuation spectroscopy (ATR) using a Fourier transform infrared spectrophotometer (for example, manufactured by PerkinElmer, trade name "SPECTRUM2000") and polarized light as the measurement light. The intensity of the acid peak (665 cm ^-1 ) and the intensity of the reference peak (2941 cm ^-1 ) are measured. The boric acid amount index can be calculated from the obtained boric acid peak intensity and the reference peak intensity by the following formula, and further, the boric acid concentration can be calculated from the calculated boric acid amount index by the following formula.
(Boric acid amount index) = (Intensity of boric acid peak 665 cm ^-1 ) / (Intensity of reference peak 2941 cm ^-1 )
(Boric acid concentration) = (Boric acid amount index) x 6.61 + 0.47

The thickness of the second PVA-based resin layer is 0.03 μm to 2 μm, preferably 0.03 μm to 1 μm, more preferably 0.04 μm to 0.5 μm, and further preferably 0.04 μm to 0. It is 1 μm, and particularly preferably 0.05 μm to 0.1 μm. When the thickness of the second PVA-based resin layer is in such a range, ammonium ions can be more easily discharged. As a result, when the polarizing plate and the polarizing plate with a retardation layer are applied to an organic EL display device, decolorization can be suppressed even more satisfactorily.

The polarizing plate has a degree of polarization change ΔP of preferably 50% or less, more preferably 25% or less, still more preferably 10% or less when exposed to ammonia vapor for 2 hours in an environment of 60 ° C. .. The smaller the degree of polarization change ΔP is, the more preferable it is, and ideally it is zero. According to the embodiment of the present invention, by adopting the above-mentioned configuration, the invasion of ammonium ions into the polarizing element (first PVA-based resin layer) is satisfactorily suppressed, and the ammonium ions from the polarizing element are suppressed. Can be discharged well. As a result, even when the polarizing plate is exposed to ammonia, the change in the degree of polarization (substantially, the decrease in the degree of polarization) can be significantly suppressed. Such a polarizing plate (as a result, a polarizing plate with a retardation layer) can satisfactorily suppress decolorization when applied to an organic EL display device.

Hereinafter, the first PVA-based resin layer (polarizer), the second PVA-based resin layer, the protective layer, and the pressure-sensitive adhesive layer will be specifically described.

A-2. First PVA-based Resin Layer The first PVA-based resin layer functions as a polarizing element as described above. Therefore, in the present specification, the first PVA-based resin layer may be referred to as a polarizing element. The modulator is typically composed of a PVA-based resin film containing a dichroic substance (typically iodine).

The substituent preferably has a ratio (A ₅₅₀ / A ₂₁₀ ) of the orthogonal absorbance A ₅₅₀ at a wavelength of 550 nm to the orthogonal absorbance A ₂₁₀ at a wavelength of 210 nm of 1.4 or more, and has an orthogonal absorbance A ₄₇₀ at a wavelength of 470 nm and a wavelength of 600 nm. The ratio to the orthogonal absorbance A ₆₀₀ in (A ₄₇₀ / A ₆₀₀ ) is 0.7 or more, and the orthogonal b value is larger than -10. The modulator used in the embodiment of the present invention has a very large ratio (A ₅₅₀ / A ₂₁₀ ) and (A ₄₇₀ / A ₆₀₀ ) as compared with a normal thin polarizing element. This is because the content ratio of iodine ions (having absorption in the ultraviolet region near 210 nm) that do not form a complex with PVA in the polarizing element is very small, and the content ratio of PVA-iodine complex (having absorption in the visible region) is very small. Means that is very large. More specifically, the substituent has a very large content ratio of PVA-I ₅ ^- complex having absorption near 600 nm, and a large content ratio of PVA-I ₃ ^- complex having absorption near 480 nm. It is maintained without decreasing. Here, since the thickness of the polarizing element means the length of the optical path length, if the thickness of the polarizing element is simply reduced, the optical path length is shortened and the polarization performance is also deteriorated. Since the amount of iodine that can be contained in the polarizing element is limited, it is essential to efficiently utilize the iodine contained in the polarizing element in order to achieve both high polarization performance and thinning of the polarizing element. In other words, by reducing iodine ions that have absorption in the ultraviolet and do not contribute to polarization performance, and by improving the ratio of PVA-iodine complexes that have absorption in the visible region, both high polarization performance and thinning of the polarizing element can be achieved. Will be possible. In other words, by increasing the ratio (A ₅₅₀ / A ₂₁₀ ), it is possible to achieve thinness and high optical characteristics. Furthermore, by maintaining the ratio (A ₄₇₀ / A ₆₀₀ ) above a predetermined value, good polarization performance can be realized over the entire visible light range. Given the limited amount of iodine in thin polarizing elements, it has been difficult to increase both the ratio (A ₅₅₀ / A ₂₁₀ ) and the ratio (A ₄₇₀ / A ₆₀₀ ) with conventional techniques. In the modulator used in the embodiment, both of these can be increased. The ratio (A ₅₅₀ / A ₂₁₀ ) is preferably 1.8 or more, more preferably 2.0 or more, and even more preferably 2.2 or more. The upper limit of the ratio (A ₅₅₀ / A ₂₁₀ ) can be, for example, 3.5. The ratio (A ₄₇₀ / A ₆₀₀ ) is preferably 0.75 or more, more preferably 0.80 or more, still more preferably 0.85 or more. The upper limit of the ratio (A ₄₇₀ / A ₆₀₀ ) is, for example, 2.00, preferably 1.33. The orthogonal absorbance is determined by the following formula based on the orthogonal transmittance Tc measured when determining the degree of polarization described later.
Orthogonal absorbance = log10 (100 / Tc)

Further, the orthogonal b value of the polarizing element is larger than -10, preferably -7 or more, and more preferably -5 or more, as described above. The upper limit of the orthogonal b value is preferably +10 or less, and more preferably +5 or less. According to the present invention, it is possible to realize an orthogonal b value in such a range. The orthogonal b value indicates the hue when the polarizing elements (polarizing plates) are arranged in the orthogonal state, and the larger the absolute value of this numerical value, the more the orthogonal hue (black display in the image display device) appears to be tinted. Means. For example, when the orthogonal b value is as low as −10 or less, the black display appears to be colored blue, and the display performance is deteriorated. That is, according to the embodiment of the present invention, it is possible to obtain a polarizing element that can realize an excellent hue at the time of displaying black. The orthogonal b value can be measured by a spectrophotometer typified by LPF200.

The splitter preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the modulator is preferably 46.0% or less, and more preferably 45.0% or less. On the other hand, the single transmittance is preferably 41.5% or more, more preferably 42.0% or more, and further preferably 42.5% or more. The degree of polarization of the splitter is preferably 99.990% or more, and preferably 99.998% or less. The polarizing element used in the embodiment of the present invention can have both a high single transmittance and a high degree of polarization. The single transmittance is typically a Y value measured with an ultraviolet-visible spectrophotometer and corrected for luminosity factor. The single transmittance is a value when the refractive index of one surface of the polarizing plate is converted to 1.50 and the refractive index of the other surface is converted to 1.53. The degree of polarization is typically obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured by using an ultraviolet-visible spectrophotometer and corrected for luminosity factor.
Degree of polarization (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100

The thickness of the splitter 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. On the other hand, the thickness of the polarizing element may be, for example, 1 μm or more, for example, 2 μm or more, and may be, for example, 3 μm or more. When the thickness of the splitter is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The resin film forming the polarizing element may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizing element composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine and a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizing element obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is used.

The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Further, it may be dyed after being stretched. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a cleaning treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt and blocking inhibitor on the surface of the PVA-based film, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizing element obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizing element obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizing element obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a stator. obtain. In the present embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin base material. Stretching typically involves immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further comprise, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. In addition, in the present embodiment, preferably, the laminate is subjected to a drying shrinkage treatment in which the laminate is shrunk by 2% or more in the width direction by heating while being conveyed in the longitudinal direction. Typically, the production method of the present embodiment includes subjecting the laminate to an aerial auxiliary 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 on the thermoplastic resin, the crystallinity of PVA can be enhanced and high optical characteristics can be achieved. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of PVA orientation and dissolution when immersed in water in a subsequent dyeing step or stretching step, and high optical characteristics. Will be possible to achieve. Further, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecule and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This makes it possible to improve the optical characteristics of the polarizing element obtained through a treatment step of immersing the laminate in a liquid, such as a dyeing treatment and a stretching treatment in water. Further, the optical characteristics can be improved by shrinking the laminated body in the width direction by the drying shrinkage treatment. The obtained resin base material / polarizing element laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizing element), and the resin base material is peeled off from the resin base material / polarizing element laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. Details of the method for producing such a polarizing element are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

A-3. Second PVA-based Resin Layer The second PVA-based resin layer can be typically formed by applying and drying a PVA-based resin aqueous solution. The average degree of polymerization of the PVA-based resin contained in the aqueous solution is preferably about 100 to 5000, and more preferably 1000 to 4000. The average saponification degree is preferably about 85 mol% to 100 mol%, more preferably 90 mol% to 100 mol%. When the average degree of polymerization and the average degree of saponification are in such a range, the adhesiveness with the first PVA-based resin layer is excellent, and as a result, with respect to the emission of ammonium ions at the interface with the first PVA-based resin layer. Adverse effects can be prevented. As a result, when the polarizing plate and the polarizing plate with a retardation layer are applied to the organic EL display device, decolorization can be suppressed more satisfactorily.

The PVA-based resin preferably contains an acetoacetyl group. This is because the adhesion between the polarizing element and the protective layer is excellent, and the durability can be excellent. The acetoacetyl group-containing PVA-based resin can be obtained, for example, by reacting the PVA-based resin with diketene by an arbitrary method. The degree of acetoacetyl group modification of the acetoacetyl group-containing PVA resin is typically 0.1 mol% or more, preferably about 0.1 mol% to 40 mol%, and more preferably 1 mol% to 20 mol. %, Especially preferably 2 mol% to 7 mol%. The degree of acetoacetyl group modification is a value measured by NMR.

The resin concentration in the PVA-based resin aqueous solution is preferably 0.1% by weight to 15% by weight, more preferably 0.5% by weight to 10% by weight. The viscosity of the aqueous solution is preferably 1 to 50 mPa · s. The pH of the aqueous solution is preferably 2 to 6, more preferably 2.5 to 5, still more preferably 3 to 5, and particularly preferably 3.5 to 4.5.

The PVA-based resin aqueous solution (as a result, the second PVA-based resin layer) may contain a metal compound colloid in one embodiment. The metal compound colloid is one in which the metal compound fine particles are dispersed in the dispersion medium, and is electrostatically stabilized due to the mutual repulsion of the same kind of charges of the fine particles, and can have permanent stability. .. It was

The average particle size of the fine particles forming the metal compound colloid is set to any appropriate value as long as it does not adversely affect the optical characteristics such as transparency and polarization characteristics. It is preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm. This is because the fine particles can be uniformly dispersed in the second PVA-based resin layer.

As the metal compound, any suitable compound is used. For example, metal oxides such as alumina, silica, zirconia and titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate and calcium phosphate; minerals such as celite, talc, clay and kaolin. Be done. A positively charged metal compound colloid is preferably used. Examples of the metal compound include alumina, titania and the like, and alumina is particularly preferable.

A-4. Protective Layer The visible side protective layer 30 and the inner protective layer (if any) are each formed of any suitable film that can be used as a protective layer for the stator. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based. , Polyester-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

The visual-viewing side protective layer has a moisture permeability of preferably ²⁰⁰ g / m 2.24 h or more, more preferably 300 g / ^m 2.24 h or more, still more preferably 330 g / m 2.24 h or ^more , and particularly preferably. Is 360 g / ^m 2.24 hours or more, and particularly preferably 400 g / ^m 2.24 hours or more. The upper limit of the moisture permeability of the visible side protective layer may be, for example, 1000 g / ^m 2.24 h. When the moisture permeability of the visual-viewing side protective layer is within such a range, the emission of ammonium ions is further promoted, and as a result, the decolorization of the polarizing plate and the polarizing plate with a retardation layer can be further suppressed. In this case, the visible side protective layer may preferably be composed of a TAC film. The moisture permeability can be measured according to JIS Z 0208.

The visible side protective layer may be subjected to surface treatment such as hard coat treatment, antireflection treatment, sticking prevention treatment, and antiglare treatment, if necessary. Further / or, if necessary, the visual-viewing side protective layer is provided with a process for improving visibility when visually recognizing through polarized sunglasses (typically, a (elliptical) circular polarization function is imparted, and an ultra-high level is provided. (Giving a phase difference) may be applied. By performing such processing, excellent visibility can be realized even when the display screen is visually recognized through a polarizing lens such as polarized sunglasses. Therefore, the polarizing plate and the polarizing plate with a retardation layer can be suitably applied to an image display device that can be used outdoors.

The thickness of the visible side protective layer 30 is preferably 10 μm to 60 μm, more preferably 15 μm to 50 μm. When the surface treatment is applied, the thickness of the visible side protective layer 30 is the thickness including the thickness of the surface treatment layer.

The inner protective layer (if present) is preferably optically isotropic in one embodiment. As used herein, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. say. The thickness of the other protective layer is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 10 μm to 30 μm. In embodiments of the invention, the inner protective layer may preferably be omitted.

A-5. Adhesive layer Typical examples of the adhesive constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and adhesives. Examples include polyether adhesives. A pressure-sensitive adhesive having desired characteristics according to the purpose by adjusting the type, number, combination and blending ratio of the monomers forming the base resin of the pressure-sensitive adhesive, as well as the blending amount of the cross-linking agent, the reaction temperature, the reaction time and the like. Can be prepared. The base resin of the pressure-sensitive adhesive may be used alone or in combination of two or more. An acrylic pressure-sensitive adhesive (acrylic pressure-sensitive adhesive composition) is preferable from the viewpoint of transparency, processability, durability and the like. The acrylic pressure-sensitive adhesive composition typically contains a (meth) acrylic polymer as a main component. The (meth) acrylic polymer can be contained in the pressure-sensitive adhesive composition in a proportion of, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more in the solid content of the pressure-sensitive adhesive composition. The (meth) acrylic polymer contains an alkyl (meth) acrylate as a main component as a monomer unit. In addition, (meth) acrylate means acrylate and / or methacrylate. The alkyl (meth) acrylate may be contained in a proportion of preferably 80% by weight or more, more preferably 90% by weight or more, in the monomer component forming the (meth) acrylic polymer. Examples of the alkyl group of the alkyl (meth) acrylate include a linear or branched alkyl group having 1 to 18 carbon atoms. The average number of carbon atoms of the alkyl group is preferably 3 to 9, and more preferably 3 to 6. The preferred alkyl (meth) acrylate is butyl acrylate. As the monomer (copolymerization monomer) constituting the (meth) acrylic polymer, in addition to the alkyl (meth) acrylate, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, an aromatic ring-containing (meth) acrylate, and a complex Examples include ring-containing vinyl-based monomers. The acrylic pressure-sensitive adhesive composition may preferably contain a silane coupling agent and / or a cross-linking agent. Examples of the silane coupling agent include epoxy group-containing silane coupling agents. Examples of the cross-linking agent include isocyanate-based cross-linking agents and peroxide-based cross-linking agents. Further, the acrylic pressure-sensitive adhesive composition may contain an antioxidant and / or a conductive agent. Details of the pressure-sensitive adhesive are described in, for example, JP-A-2006-183022, JP-A-2015-199942, JP-A-2018-053114, JP-A-2016-190996, and International Publication No. 2018/008712. The description of these publications is incorporated herein by reference.

The adhesive has a storage elastic modulus at 25 ° C., preferably 1.0 × 10 ⁴ Pa to 1.0 × 10 ⁶ Pa, and more preferably 1.0 × 10 ⁴ Pa to 1.0 × 10 ⁵ Pa. Is. When the storage elastic modulus of the pressure-sensitive adhesive is within such a range, peeling or floating between layers can be suppressed, and adverse effects on the emission of ammonium ions can be prevented.

The pressure-sensitive adhesive may have a creep amount ΔCr at 70 ° C. of, for example, 65 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, and further 15 μm or less. The lower limit of the creep amount ΔCr is, for example, 0.5 μm. When the creep amount is in such a range, peeling or floating between layers can be suppressed and an adverse effect on the emission of ammonium ions can be prevented, as in the case of the storage elastic modulus. The creep value can be measured, for example, by the following procedure: A load of 500 gf is applied to the adhesive adhered to the stainless steel test plate on the joint surface of 20 mm in length × 20 mm in width with the test plate fixed. Add vertically below. The creep amount (displacement amount) of the adhesive to the test plate at each time point 100 seconds and 3600 seconds after the start of applying the load is measured, and the values are Cr ₁₀₀ and Cr ₃₆₀₀ , respectively. From the measured Cr ₁₀₀ and Cr ₃₆₀₀ , the creep amount ΔCr can be obtained by the formula ΔCr = Cr ₃₆₀₀ −Cr ₁₀₀ .

The thickness of the pressure-sensitive adhesive layer is preferably 2 μm to 40 μm, more preferably 3 μm to 20 μm, and further preferably 4 μm to 15 μm.

B. Polarizing plate with retardation layer As described in item A-1, the polarizing plate according to the embodiment of the present invention comprises a polarizing plate with a retardation layer in which the retardation layers are bonded via the pressure-sensitive adhesive layer 40. You may. Therefore, a polarizing plate with a retardation layer can also be included in the embodiment of the present invention. The polarizing plate with a retardation layer according to the embodiment of the present invention can significantly suppress decolorization when applied to an organic EL display device. The retardation layer typically has a circular polarization function or an elliptically polarizing function. The retardation layer typically exhibits reverse dispersion wavelength characteristics and can function as a λ / 4 plate. The retardation layer may be a stretched film of a resin film or an oriented solidified layer of a liquid crystal compound (liquid crystal oriented solidified layer). The retardation layer is preferably a stretched film of a resin film. With such a configuration, the invasion of ammonium ions into the stator can be satisfactorily suppressed. Typical examples of the resin constituting the resin film include a polycarbonate-based resin and a polyester carbonate-based resin.

C. Organic EL Display Device The polarizing plate according to the above item A and the polarizing plate with a retardation layer according to the above item B can be applied to the organic EL display device. Therefore, an organic EL display device including a polarizing plate or a polarizing plate with a retardation layer is also included in the embodiment of the present invention. The organic EL display device typically includes a polarizing plate or a polarizing plate with a retardation layer on the visible side thereof. The polarizing plate with a retardation layer is laminated so that the retardation layer is on the organic EL cell side (the polarizing plate is on the visual recognition side). In one embodiment, the organic EL display device has a curved shape (substantially a curved display screen) and / or is bendable or bendable. As described above, when the polarizing plate and the polarizing plate with a retardation layer are applied to the organic EL display device, the present inventors use the polarizing plate and the polarizing plate by ammonia (substantially ammonium ions) generated from the organic EL panel. A new problem of decolorization of a polarizing plate with a retardation layer was discovered, and the problem was solved by the polarizing plate according to the above item A and the polarizing plate with a retardation layer according to the above item B. That is, in the organic EL display device, the effect of the polarizing plate and the polarizing plate with a retardation layer according to the embodiment of the present invention is remarkable.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.
(1) Thickness The thickness of the first PVA-based resin layer was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The thickness of the second PVA-based resin layer was determined by cutting the polarizing plates of Examples and Comparative Examples and observing the cross section of the polarizing plate using a scanning electron microscope (“JSM7100F” manufactured by JEOL Ltd.). Measured from the image.
(2) Single transmittance and degree of polarization The polarizing plates used in the Examples and Comparative Examples were measured with an ultraviolet-visible spectrophotometer (“LPF200” manufactured by Otsuka Electronics Co., Ltd.), and the single transmittance Ts and parallel transmittance Tp were measured. The orthogonal transmittance Tc was defined as Ts, Tp and Tc of the polarizing elements, respectively. These Ts, Tp and Tc are Y values measured by the JIS Z8701 two-degree visual field (C light source) and corrected for luminosity factor. From the obtained Tp and Tc, the degree of polarization P was determined by the following formula.
Degree of polarization P (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100
The orthogonal absorbance A ₂₁₀ was obtained from the orthogonal transmittance Tc ₂₁₀ having a measurement wavelength of 210 nm, and the orthogonal absorbance A ₅₅₀ was obtained from the orthogonal transmittance Tc ₅₅₀ having a measurement wavelength of 550 nm, respectively, using "U4100" manufactured by Hitachi High-Technologies Corporation. Further, the orthogonal absorbance A ₄₇₀ is obtained from the orthogonal transmittance Tc ₄₇₀ having a measurement wavelength of 470 nm, and the orthogonal absorbance A ₆₀₀ is obtained from the orthogonal transmittance Tc ₆₀₀ having a measurement wavelength of 600 nm. Obtained using.
(3) Moisture permeability Measured according to JIS Z 0208. Specifically, the protective layer (the film constituting the film) used in Examples and Comparative Examples was cut into a circle of 10 cmΦ and used as a measurement sample. The moisture permeability of this measurement sample was measured using "MOCON" manufactured by Hitachi, Ltd. under the test conditions of 40 ° C. and 92% RH.
(4) Orthogonal b value The polarizing plate used in the Examples and Comparative Examples was measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name "V7100"), and the hue in the cross Nicol state was determined. .. The lower the orthogonal b value (negative value and larger absolute value), the more the hue is blue rather than neutral.
(5) Boric acid concentration With respect to the polarizing plates obtained in Examples and Comparative Examples, the polarization was measured using a Fourier transform infrared spectrophotometer (FT-IR) (manufactured by PerkinElmer, trade name "SPECTRUM2000"). The intensity of the boric acid peak (665 cm ^-1 ) and the intensity of the reference peak (2941 cm ^-1 ) were measured by total reflection spectroscopy (ATR) measurement using light. The boric acid amount index was calculated from the obtained boric acid peak intensity and the reference peak intensity by the following formula, and further, the boric acid concentration was determined from the calculated boric acid amount index by the following formula.
(Boric acid amount index) = (Intensity of boric acid peak 665 cm ^-1 ) / (Intensity of reference peak 2941 cm ^-1 )
(Boric acid concentration) = (Boric acid amount index) x 6.61 + 0.47
(6) Ammonia decolorization test 1.5 ml of a 10% aqueous ammonia solution was placed in a glass bottle (cylindrical shape having a diameter of 30 mm and a depth of 50 mm). At this time, the distance from the liquid surface of the aqueous ammonia solution to the mouth (upper end) of the glass bottle was about 30 mm. The polarizing plates obtained in Examples and Comparative Examples were cut out into a size of 30 mm × 30 mm and used as measurement data. The measurement material was attached to the edge of the mouth of the glass bottle via the adhesive layer so that the mouth of the glass bottle was completely covered with this measurement material and the steam did not leak from the gap. The glass bottle covered with the measurement material was heated at 60 ° C. for 2 hours. The absolute value | ΔP | of the change in the degree of polarization was calculated from the following equation, where the degree of polarization of the polarizing plate (substantially the polarizing element) before heating was P ₀ and the degree of polarization after heating was P ₂₀ . The smaller | ΔP |, the more the decolorization due to ammonia is suppressed.
| ΔP | = | P ₂₀ -P ₀ |
Based on the obtained ΔP, it was evaluated according to the following criteria.
A: | ΔP | is 10% or less B: | ΔP | is greater than 10% and 25% or less C: | ΔP | is greater than 25% and 50% or less D: | ΔP | is greater than 50% and 75% or less E: | ΔP | is greater than 75%

[Example 1]
1. 1. Fabrication of Polarizer As a thermoplastic resin base material, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape and a Tg of about 75 ° C. was used, and one side of the resin base material was treated with corona. Was given.
100 parts by weight of PVA-based resin in which polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer") are mixed at a ratio of 9: 1. A PVA aqueous solution (coating solution) was prepared by dissolving 13 parts by weight of potassium iodide in water.
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60 ° C. to form a PVA-based resin layer having a thickness of 13 μm, and a laminate was prepared.
The obtained laminate was uniaxially stretched 2.4 times in the vertical direction (longitudinal direction) in an oven at 130 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, in a dyeing bath having a liquid temperature of 30 ° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1: 7 with respect to 100 parts by weight of water), the polarizing element finally obtained is charged. It was immersed for 60 seconds while adjusting the concentration so that the simple substance transmittance (Ts) was 43.0% (staining treatment).
Then, it was immersed in a cross-linked bath having a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70 ° C., the total in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
Then, the laminate was immersed in a washing bath having a liquid temperature of 20 ° C. (an aqueous solution obtained by blending 3 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Then, while drying in an oven kept at about 90 ° C., it was brought into contact with a heating roll made of SUS whose surface temperature was kept at about 75 ° C. (dry shrinkage treatment).
In this way, a polarizing element was formed on the resin substrate, and a laminate having a resin substrate / polarizing element (first PVA-based resin layer) configuration was obtained. The thickness of the splitter (first PVA-based resin layer) was 5 μm, and the single transmittance was 43.0%.

2. 2. Preparation of Polarizing Plate A second PVA-based resin layer was formed on the surface of the polarizing element (first PVA-based resin layer) of the laminate obtained above, and a protective layer was laminated. Specifically, it is as follows. Acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, solid content concentration 4%, manufactured by Mitsubishi Chemical Corporation, trade name "Gosenex Z-200") 6. An aqueous resin composition was obtained by mixing 02 parts, 25 parts of an aqueous solution containing a positively charged alumina colloid (average particle size 15 nm) at a solid content concentration of 3.2%, and 18.98 parts of pure water. The surface of the first PVA-based resin layer is coated so that the thickness of the resin composition after drying is 0.09 μm, and the HC-TAC film is bonded using a roll machine, and then the resin composition is applied. By drying, a second PVA-based resin layer was formed, and the polarizing element and the protective layer were bonded together. The HC-TAC film is a film in which a hard coat (HC) layer (thickness 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and the TAC film is the first PVA-based resin layer side. It was pasted together so that it would be. The moisture permeability of the HC-TAC film was 427 g / ^m 2.24 h. Next, the resin base material is peeled off, an acrylic pressure-sensitive adhesive (thickness 20 μm) is placed on the peeled surface, and a visible side protective layer (HC-TAC film) / second PVA-based resin layer / first PVA-based resin is placed. A polarizing plate having a layer (polarizer) / pressure-sensitive adhesive layer (acrylic pressure-sensitive adhesive) was obtained. The boric acid concentration on the surface opposite to the visible side of the first PVA-based resin layer was 17.5% by weight, and the boric acid concentration on the visible side surface of the second PVA-based resin layer was 17.0% by weight. rice field. Further, in the obtained polarizing plate, the A ₅₅₀ / A ₂₁₀ of the polarizing element was 2.59, the A ₄₇₀ / A ₆₀₀ was 0.96, and the orthogonal b value was −1.6. The obtained polarizing plate was subjected to the evaluation of (6) above. The results are shown in Table 1.
The acrylic adhesive was prepared as follows. A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler contains 91 parts of butyl acrylate, 6 parts of acryloyl morpholine, 2.7 parts of acrylic acid, and 0.3 parts of 4-hydroxybutyl acrylate. A mixture of monomers was charged. Further, 0.1 part of 2,2'-azobisisobutyronitrile was charged to 100 parts of this monomer mixture together with 100 parts of ethyl acetate as a polymerization initiator, and nitrogen gas was introduced with gentle stirring to introduce nitrogen. After the substitution, the liquid temperature in the flask was maintained at around 55 ° C. and the polymerization reaction was carried out for 8 hours to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 2.7 million and Mw / Mn = 3.8. For 100 parts of the solid content of the acrylic polymer solution, 0.1 part of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Co., Ltd., trade name "Coronate L") and peroxide cross-linking agent (manufactured by Nippon Oil & Fats Co., Ltd.) , Product name "Niper BMT") 0.3 parts and epoxy group-containing silane coupling agent (manufactured by Shinetsu Chemical Industry Co., Ltd., product name "KBM-403") 0.2 parts are blended to obtain an acrylic pressure-sensitive adhesive. rice field.

[Example 2]
A polarizing plate was obtained in the same manner as in Example 1 except that the conditions of the cross-linking treatment for producing the polarizing element (first PVA-based resin layer) were changed to change the boric acid concentration of the polarizing element. The boric acid concentration on the surface opposite to the visible side of the first PVA-based resin layer was 21.8% by weight, and the boric acid concentration on the visible side surface of the second PVA-based resin layer was 19.7% by weight. rice field. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 3]
The thickness of the second PVA-based resin layer was set to 0.07 μm, and the conditions for the cross-linking treatment when producing the polarizing element (first PVA-based resin layer) were changed to change the boric acid concentration of the polarizing element. A polarizing plate was obtained in the same manner as in Example 1 except that it was changed. The boric acid concentration on the surface opposite to the visible side of the first PVA-based resin layer was 21.8% by weight, and the boric acid concentration on the visible side surface of the second PVA-based resin layer was 20.3% by weight. rice field. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 4]
Resin base material / polarization in the same manner as in Example 1 except that the conditions of the cross-linking treatment and the stretching treatment for producing the splitter (first PVA-based resin layer) were changed to change the optical characteristics of the splitter. A laminate having a child composition was obtained. The thickness of the splitter was 5 μm, the single transmittance was 43.0%, A ₅₅₀ / A ₂₁₀ was 1.37, A ₄₇₀ / A ₆₀₀ was 0.90, and the orthogonal b value was -2.62. The following procedure was the same as in Example 1 to obtain a polarizing plate. The boric acid concentration on the surface opposite to the visible side of the first PVA-based resin layer was 14.3% by weight, and the boric acid concentration on the visible side surface of the second PVA-based resin layer was 13.9% by weight. rice field. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 5]
At the same time, a long roll of a polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") having a thickness of 30 μm is uniaxially stretched in the longitudinal direction so as to be 5.9 times in the longitudinal direction by a roll stretching machine. A extruder (first PVA-based resin layer) having a thickness of 12 μm was prepared by performing swelling, dyeing, cross-linking, and washing treatment, and finally drying treatment.
Specifically, the swelling treatment was carried out by stretching 2.2 times while treating with pure water at 20 ° C. Next, the dyeing treatment was carried out in an aqueous solution at 30 ° C. in which the weight ratio of iodine and potassium iodide was adjusted so that the simple substance transmittance of the obtained polarizing element was 43.0% and the weight ratio was 1: 7. However, it was stretched 1.4 times. Further, the cross-linking treatment adopted a two-step cross-linking treatment, and the first-step cross-linking treatment was carried out 1.2 times while being treated with an aqueous solution in which boric acid and potassium iodide were dissolved at 40 ° C. The boric acid content of the aqueous solution of the first-step crosslinking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. The second-step cross-linking treatment was carried out by stretching 1.6 times while treating with an aqueous solution in which boric acid and potassium iodide were dissolved at 65 ° C. The boric acid content of the aqueous solution of the second-step crosslinking treatment was 4.3% by weight, and the potassium iodide content was 5.0% by weight. The washing treatment was carried out with an aqueous potassium iodide solution at 20 ° C. The potassium iodide content of the aqueous solution of the washing treatment was set to 2.6% by weight. Finally, the drying treatment was carried out at 70 ° C. for 5 minutes to obtain a substituent (first PVA-based resin layer).
A polarizing plate was obtained in the same manner as in Example 1 except that this polarizing element (first PVA-based resin layer) was used. Here, the boric acid concentration on the surface opposite to the visible side of the first PVA-based resin layer is 24% by weight, and the boric acid concentration on the visible side surface of the second PVA-based resin layer is 21.6% by weight. there were. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A laminate having a resin substrate / polarizing element configuration was obtained in the same manner as in Example 1. The same HC-TAC film as in Example 1 was attached to the surface of the polarizing element of the laminate via an ultraviolet curable adhesive (thickness 1 μm). That is, the second PVA-based resin layer was not formed. In this way, a polarizing plate having a structure of a visible side protective layer (HC-TAC film) / adhesive / polarizing element / adhesive layer (acrylic adhesive) was obtained. The boric acid concentration on the surface of the PVA-based resin layer (polarizer only) opposite to the visible side was 13.6% by weight, and the boric acid concentration on the visible side surface was 15.4% by weight. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
A polarizing plate was obtained in the same manner as in Comparative Example 1 except that the conditions of the cross-linking treatment for producing the polarizing element were changed to change the boric acid concentration of the polarizing element. The boric acid concentration on the surface of the PVA-based resin layer (polarizer only) opposite to the visible side was 16.6% by weight, and the boric acid concentration on the visible side surface was 18.6% by weight. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
A polarizing plate was obtained in the same manner as in Example 1 except that an HC-COP film was used as a protective layer on the visual viewing side. The HC-COP film was a film in which a hard coat (HC) layer (thickness 2 μm) was formed on a COP film (thickness 25 μm), and the moisture permeability was 35 g / ^m 2.24 h. The obtained polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[evaluation]
As is clear from Table 1, according to the embodiment of the present invention, it is possible to obtain a polarizing plate in which the degree of polarization hardly changes (that is, does not decolorize) even when exposed to ammonia. That is, according to the embodiment of the present invention, it can be seen that a polarizing plate having suppressed decolorization and a polarizing plate with a retardation layer can be realized when applied to an organic EL display device. On the other hand, the polarizing plate of the comparative example has a significantly reduced polarization function.

The polarizing plate of the present invention is suitably used for an organic EL display device, and the polarizing plate with a retardation layer is preferably used as an antireflection circular polarizing plate for an organic EL display device.

10 PVA-based resin layer 11 First PVA-based resin layer (polarizer)
12 Second PVA-based resin layer 30 Protective layer 40 Adhesive layer 100 Polarizing plate

Claims

It includes a polyvinyl alcohol-based resin layer, a protective layer provided on the visible side of the polyvinyl alcohol-based resin layer, and an adhesive layer arranged on the side opposite to the visible side of the polyvinyl alcohol-based resin layer.
The polyvinyl alcohol-based resin layer comprises a first polyvinyl alcohol-based resin layer that functions as a polarizing element, and a second polyvinyl alcohol-based resin layer provided on the visible side of the first polyvinyl alcohol-based resin layer. Including
The thickness of the second polyvinyl alcohol-based resin layer is 0.03 μm to 2 μm.
The boric acid concentration on the surface opposite to the visible side of the polyvinyl alcohol-based resin layer is larger than the boric acid concentration on the visible side surface, and the difference is 0.3% by weight or more.
The moisture permeability of the protective layer on the visual recognition side is 200 g / m 2.24 h or more.
Polarizer.
The polarizing plate according to claim 1, wherein the boric acid concentration of the first polyvinyl alcohol-based resin layer is 14% by weight or more.
The first polyvinyl alcohol-based resin layer is
The single transmittance is 42.5% or more,
The ratio (A 550 / A 210 ) of the orthogonal absorbance A 550 at a wavelength of 550 nm to the orthogonal absorbance A 210 at a wavelength of 210 nm is 1.4 or more.
The ratio (A 470 / A 600 ) of the orthogonal absorbance A 470 at a wavelength of 470 nm and the orthogonal absorbance A 600 at a wavelength of 600 nm is 0.7 or more, and
Orthogonal b value is greater than -10,
The polarizing plate according to claim 1 or 2.
The polarizing plate according to any one of claims 1 to 3, wherein the iodine concentration of the polarizing element is 2% by weight to 10% by weight.
The polarizing plate according to any one of claims 1 to 4, wherein the absolute value | ΔP | of the change in degree of polarization when exposed to ammonia vapor for 2 hours in an environment of 60 ° C. is 50% or less.
A polarizing plate with a retardation layer having the polarizing plate according to any one of claims 1 to 5 and a retardation layer.
An organic electroluminescence display device comprising the polarizing plate according to any one of claims 1 to 5 or the polarizing plate with a retardation layer according to claim 6.