Polarizing plate and display device using same

Abstract

Provided are: a polarizing plate having durability in a high-temperature and high-humidity environment; and a display device using the polarizing plate. A polarizing plate in which a protective film A is affixed to one surface of a polarizer and a protective film B is affixed to the other surface, the polarizing plate being characterized in that the protective film A is a hard coating film in which a hard coating layer is formed on one surface of a transparent substrate, and the moisture permeability TA of the protective film A and the moisture permeability TB of the protective film B at 40 DEG C and 90% RH satisfy the following conditions (1) and (2) at the same time, when P1 is the peak intensity of 1782-1683 cm <-1 > and P2 is the peak intensity of 1427-1374 cm <-1 > as measured by an ATR method using a germanium prism, the following condition (3) is satisfied. 240 g / m2 / day > TA > 70 g / m2 / day (1) 70 g / m2 / day > = TB (2) 0.060 < = P2 / P1 < = 0.150 (3).

Description

Technical Field

[0001] The present invention relates to a polarizing plate and a display device using the polarizing plate. Background Art

[0002] Polyvinyl alcohol (PVA) is mainly used in polarizing plates used in display devices. PVA has extremely poor water resistance, so protective films are attached to both sides. In the past, protective films for polarizing plates used triacetyl cellulose (TAC) films laminated with a hard coating layer, with a moisture permeability of 300 to 1000 g / m 2 / day or so, but there is a problem that under the severe conditions of high temperature and high humidity, it is impossible to prevent PVA from absorbing water and causing degradation.

[0003] Therefore, protective films using cycloolefin polymer (COP) and polyethylene terephthalate (PET) have been developed instead of TAC, and the moisture permeability of the protective films has been reduced to 5 to 100%.

[0004] 100g / m 2 / day or so.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-144076 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In recent years, polarizing plates with durability under extremely high temperature and humidity have been required for automotive applications, etc. In high temperature and humidity environments, when the water vapor barrier property of the protective film is too high, although there is no moisture intrusion from the outside, there are cases where moisture generated from the substrate or the adhesive used to attach the protective film is retained in the polarizing plate, causing deterioration.

[0010] Therefore, an object of the present invention is to provide a polarizing plate having durability in a high-temperature and high-humidity environment and a display device using the polarizing plate.

[0011] Means for solving problems

[0012] The polarizing plate of the present invention is a polarizing plate in which a protective film A is attached to one surface of a polarizer and a protective film B is attached to the other surface, wherein the protective film A is a hard coating film in which a hard coating layer is formed on one surface of a transparent substrate, and the moisture permeability TA of the protective film A and the moisture permeability TB of the protective film B at 40° C. and 90% RH simultaneously satisfy the following conditions (1) and (2), and the moisture permeability TA of the protective film A and the moisture permeability TB of the protective film B at 1782 to 1683 cm measured by an ATR method using a germanium prism are 1782 to 1683 cm -1The peak intensity of 1427-1374 cm -1 When the peak intensity of is set to P2, the following condition (3) is satisfied.

[0013] 240g / m 2 / day>TA>70g / m 2 / day…(1)

[0014] 70g / m 2 / day≥TB…(2)

[0015] 0.060≤P2 / P1≤0.150…(3).

[0016] Furthermore, a display device according to the present invention includes the above-mentioned polarizing plate.

[0017] Effects of the Invention

[0018] According to the present invention, a polarizing plate having durability in a high-temperature and high-humidity environment and a display device using the polarizing plate can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [ Figure 1 ] Figure 1 It is a cross-sectional view showing a schematic structure of a polarizing plate according to an embodiment. DETAILED DESCRIPTION

[0020] Figure 1 It is a cross-sectional view showing a schematic structure of a polarizing plate according to an embodiment.

[0021] The polarizing plate 10 includes a polarizer 1, a protective film A attached to one side of the polarizer 1, and a protective film B attached to the other side of the polarizer 1. The polarizer 1 is formed by adsorbing iodine or a dye on a polyvinyl alcohol (PVA) film and orienting it. Since the PVA constituting the polarizer 1 has poor strength and water resistance, the protective films A and B are attached to both sides of the polarizer 1.

[0022] The protective film A is a hard coating film having a hard coating layer 3 formed on one surface of a transparent substrate 2. The hard coating layer 3 is a functional layer that covers the soft transparent substrate 2 and imparts hardness and water vapor barrier properties to the protective film A. As the transparent substrate 2, a triacetyl cellulose (TAC) film having excellent transparency can be suitably used.

[0023] The protective film A can be formed by coating a hard coat-forming composition on one side of the transparent substrate 2, drying the composition, and curing the coating by ultraviolet irradiation, wherein the hard coat-forming composition contains an active energy ray-curable compound, a hydrophobic material, a photopolymerization initiator, and a solvent.

[0024] As the active energy ray-curable compound, for example, a monofunctional, bifunctional, or trifunctional or higher (meth)acrylate monomer can be used. It should be noted that in this specification, "(meth)acrylate" is a general term for both acrylate and methacrylate, and "(meth)acryloyl" is a general term for both acryloyl and methacryloyl.

[0025] Examples of the monofunctional (meth)acrylate compound include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, and (meth)acrylate. Isodecyl acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, benzyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phosphoric acid (meth)acrylate, ethylene oxide modified phosphoric acid (meth)acrylate, phenoxy (meth)acrylate, ethylene oxide modified phenoxy (meth)acrylate, propylene oxide modified phenoxy (meth)acrylate meth)acrylate, phenol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, propylene oxide modified nonylphenol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl hydrogenated phthalate, 2-(meth)acryloyloxyethyl hydrogenated phthalate -(meth)acryloxypropyl ester, 2-(meth)acryloxypropyl hexahydrohydrophthalate, 2-(meth)acryloxypropyl tetrahydrohydrophthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, and adamantane derivative mono(meth)acrylate such as adamantane acrylate having a monovalent mono(meth)acrylate derived from 2-adamantane or adamantanediol.

[0026] Examples of the bifunctional (meth)acrylate include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate and other di(meth)acrylates.

[0027] Examples of trifunctional or higher (meth)acrylates include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tri-2-hydroxyethyl isocyanurate tri(meth)acrylate, glycerol tri(meth)acrylate and the like; trifunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate and the like; Acid ester compounds; polyfunctional (meth)acrylate compounds having three or more functions such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane hexa(meth)acrylate; and polyfunctional (meth)acrylate compounds in which a part of these (meth)acrylates is substituted with an alkyl group or ε-caprolactone, etc.

[0028] In addition, urethane (meth)acrylates may be used as the polyfunctional monomers. Examples of urethane (meth)acrylates include urethane (meth)acrylates obtained by reacting a product obtained by reacting an isocyanate monomer or prepolymer with a polyester polyol with a (meth)acrylate monomer having a hydroxyl group.

[0029] Examples of urethane (meth)acrylates include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer.

[0030] The above-mentioned multifunctional monomer may be used alone or in combination of two or more. In addition, the above-mentioned multifunctional monomer may be a monomer in the composition or an oligomer obtained by partial polymerization.

[0031] The hydrophobic material is a component for making the hard coat layer 3 express hydrophobicity and adjusting the moisture permeability of the protective film A. As the hydrophobic material contained in the hard coat layer 3, a cycloolefin polymer or a (meth)acrylate containing an alicyclic structure can be used.

[0032] As the (meth)acrylate containing an alicyclic structure, for example, (meth)acrylate having one or more of a cyclopentane structure, a dicyclopentane structure, a cyclohexane structure, a cyclodecane structure, a tricyclodecane structure, an isobornyl structure, and an adamantane structure can be used.

[0033] Specific examples of the (meth)acrylate containing an alicyclic structure include: monofunctional (meth)acrylates such as cyclohexyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexanol (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, 2-dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyloxyethyl methacrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecyl (meth)acrylate, tricyclodecane dimethanol mono(meth)acrylate, and adamantyl (meth)acrylate; and cyclohexanedimethanol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, di(meth)acrylate, and isobornyl (meth)acrylate. Polyfunctional (meth)acrylates such as dicyclopentenyl meth)acrylate, dicyclopentadienyl di(meth)acrylate, bornyl di(meth)acrylate, isobornyl di(meth)acrylate, tricyclodecyl di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, adamantyl di(meth)acrylate, adamantane dimethanol di(meth)acrylate, adamantane diethanol di(meth)acrylate, dihydroxymethyl dicyclopentane di(meth)acrylate, norbornane dimethylol di(meth)acrylate, cyclohexanedimethanol tri(meth)acrylate, adamantyl tri(meth)acrylate, adamantane trimethanol tri(meth)acrylate, norbornane trimethylol tri(meth)acrylate, tricyclodecane trimethanol tri(meth)acrylate, and perhydro-1,4,5,8-dimethylnaphthalene-2,3,7-(oxymethyl) tri(meth)acrylate. These (meth)acrylates may be used alone or as a mixture of one or more thereof.

[0034] As the photopolymerization initiator, free radical polymerization initiators such as acetophenone, benzophenone, thioxanthone, benzoin, benzoin methyl ether, and acylphosphine oxide can be used. As the polymerization initiator, for example, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide, 2,2-diethoxy acetophenone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-phenyl acetophenone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler's ketone, acetophenone, 2-chlorothioxanthone, etc. can be used. Among these, one kind can be used alone, or two or more kinds can be used in combination.

[0035] As the solvent, one of the following solvents can be used or a mixture of two or more thereof: alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol, isopropanol, and isobutanol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; keto alcohols such as diacetone alcohol; aromatic hydrocarbons such as benzene, toluene, and xylene; glycols such as ethylene glycol, propylene glycol, and hexylene glycol; glycol ethers such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, diethyl cellosolve, diethyl carbitol, and propylene glycol monomethyl ether; esters such as dimethyl carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, and amyl acetate; ethers such as dimethyl ether and diethyl ether; N-methylpyrrolidone and dimethylformamide.

[0036] In addition, various additives such as antistatic agents, defoaming agents, antioxidants, ultraviolet absorbers, infrared absorbers, colorants, light stabilizers, inhibitors, photosensitizers, antifouling agents, leveling agents, oleophobic agents, hydrophobic agents, anti-fingerprint adhesion agents, etc. may be added to the hard coat forming composition as needed.

[0037] There is no particular limitation on the method for applying the hard coat-forming composition, and for example, coating can be performed using a spin coater, a roll coater, a reverse roll coater, a gravure coater, a micro gravure coater, an air knife coater, a rod coater, a wire bar coater, a die coater, a dip coater, a spray coater, an applicator, or the like.

[0038] The coating thickness of the hard coat layer-forming composition (film thickness of the coating film) is preferably 10 μm or less, more preferably 8 μm or less. If the coating thickness of the hard coat layer-forming composition exceeds 10 μm, curling is likely to occur due to shrinkage during curing of the coating film, which is not preferred.

[0039] Moreover, the pencil hardness of the protective film A (hard coat film) is preferably 3 H or more. When the pencil hardness of the protective film A is 3 H or more, the surface hardness of the polarizing plate is excellent and the durability is improved.

[0040] The protective film B is a low moisture permeable film made of any one of cycloolefin polymer (COP), polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA). The protective film B is attached to the polarizer 1 via an ultraviolet curable adhesive. The thickness of the protective film B is not particularly limited, but is preferably 10 to 100 μm.

[0041] Note that, in the display device, the protective film B is disposed on the display panel side, and the hard coat layer 3 of the protective film A is disposed on the viewing side (the side opposite to the display panel).

[0042] The transparent substrate 2 of the protective film A is pasted on the PVA film of the polarizer 1 using a water paste (PVA aqueous solution) as an adhesive. It should be noted that in order to ensure the close adhesion between the transparent substrate 2 and the PVA film, the protective film A is subjected to a saponification treatment before pasting. Since a water paste is used when the protective film A is pasted on the polarizer 1, even after the drying process, moisture may be contained in the adhesive layer and the TAC film. In the case of using a film with low moisture permeability to constitute both the protective films A and B, although the intrusion of moisture from the outside can be suppressed, in an extremely high temperature environment such as in a car in summer, the moisture contained in the adhesive and / or the transparent substrate 2 continues to be retained in the polarizing plate 10, thereby causing the polarizer 1 to deteriorate.

[0043] Therefore, in the polarizing plate 10 involved in this embodiment, by setting a difference between the moisture permeability of the protective film A and the moisture permeability of the protective film B, and setting the moisture permeabilities of the protective film A and the protective film B within specific ranges, respectively, the deterioration of the polarizer 1 caused by moisture from the adhesive and / or TAC film is suppressed.

[0044] Specifically, when the moisture permeabilities of the protective films A and B at 40°C and 90% RH are TA and TB, respectively, TA and TB simultaneously satisfy the following conditions (1) and (2). It should be noted that both moisture permeabilities TA and TB are values ​​measured according to the moisture permeability test method (cup method) for moisture-proof packaging materials specified in JIS Z 0208:1976.

[0045] 240g / m 2 / day>TA>70g / m 2 / day…(1)

[0046] 70g / m 2 / day≥TB…(2)

[0047] The polarizing plate 10 involved in this embodiment satisfies the above-mentioned conditions (1) and (2) at the same time, thereby being able to suppress the intrusion of moisture from the outside into the interior of the polarizing plate, and, for example, when exposed to a high temperature environment of 85°C, being able to discharge to the outside the moisture generated by the adhesive used to adhere the protective film A and the polarizer 1 and / or the transparent substrate 2 of the protective film A.

[0048] In the hard coating layer 3, the wavelengths of 1782 to 1683 cm-1 measured by the ATR method using a germanium prism were -1 The peak intensity (peak height) of 1427-1374 cm -1 When the peak intensity of 1782-1683 cm is defined as P2, P2 / P1 is defined as the degree of curing. -1 The peak at 1427 to 1374 cm corresponds to the stretching vibration peak of the C=O bond of the (meth)acryloyl group constituting the (meth)acrylate compound. -1 The intensity corresponds to the stretching vibration peak of the C=C bond of the (meth)acryloyl group of the (meth)acrylate compound. When the value of the curing degree P2 / P1 of the hard coating layer 3 becomes smaller, the pencil hardness increases, and when the curing degree P2 / P1 becomes larger, the pencil hardness decreases. In addition, when the value of the curing degree P2 / P1 becomes smaller, the moisture permeability tends to decrease, and when the value of the curing degree P2 / P1 becomes larger, the moisture permeability tends to increase. Therefore, there is a curing degree P2 / P1 range that can achieve both pencil hardness and moisture permeability. Specifically, the curing degree P2 / P1 preferably satisfies the following condition (3).

[0049] 0.060≤P2 / P1≤0.150…(3)

[0050] When the curing degree P2 / P1 is less than 0.060, the above condition (1) may not be satisfied due to the low moisture permeability of the protective film A. In this case, the moisture generated by the transparent substrate 2 of the protective film A cannot be discharged to the outside. When the curing degree P2 / P1 exceeds 0.150, the pencil hardness of the protective film A deteriorates. In addition, the above condition (1) may not be satisfied due to the high moisture permeability. In this case, it is difficult to suppress the intrusion of moisture from the outside into the polarizing plate. It should be noted that the above condition (1) is more preferably 239.7 g / m 2 / day≥TA≥93.5g / m 2 / day, more preferably 212g / m 2 / day≥TA≥152.9g / m 2 / day, more preferably 191.7 g / m 2 / day≥TA≥152.9g / m 2In addition, the condition (3) is more preferably 0.067≤P2 / P1≤0.149, further preferably 0.101≤P2 / P1≤0.137, and further preferably 0.101≤P2 / P1≤0.126.

[0051] As described above, the polarizing plate 10 involved in this embodiment has a protective film A and a protective film B that satisfy the above conditions (1) to (3). With this structure, the protective film B arranged on the display panel side almost blocks the entry and exit of moisture. On the other hand, the protective film A arranged on the viewing side can inhibit moisture from invading the inside of the polarizing plate 10 from the outside, and can release the moisture generated inside the polarizing plate 10 in an extremely high temperature environment. Therefore, in the polarizing plate 10 involved in this embodiment, when used in a high temperature environment, the moisture generated inside the polarizing plate 10 will not be retained, so the degradation of the polarizer can be suppressed, thereby maintaining the optical performance of the polarizing plate 10 for a longer period of time.

[0052] In addition, by making the degree of curing of the hard coat layer 3 of the protective film A satisfy the above condition (3), it is possible to impart high pencil hardness while controlling the moisture permeability of the protective film A within a preferred range. As a result, the low moisture permeability and surface hardness of the protective film A can be maintained for a long time, thereby improving the durability of the polarizing plate.

[0053] Therefore, according to the present embodiment, it is possible to provide the polarizing plate 10 having excellent durability in a high-temperature and high-humidity environment.

[0054] The polarizing plate 10 of this embodiment can be used in combination with an image display panel such as a liquid crystal panel or an organic EL panel to form an image display device. The image display device can also have a touch panel. Since the polarizing plate 10 of this embodiment has excellent durability in a high temperature and high humidity environment, it can be suitably used as an image display device mounted in an extremely high temperature and high humidity environment such as a car.

[0055] Example

[0056] Hereinafter, embodiments for implementing the present invention will be described.

[0057] A hard coat layer-forming composition was prepared containing a main material (polymerizable material), a hydrophobic material, a photopolymerization initiator, and a solvent in the proportions shown in Table 1. It should be noted that Irgacure (registered trademark) 184 shown in Table 1 is 1-hydroxycyclohexyl phenyl ketone.

[0058] The prepared hard coating forming composition was applied to a TAC film (trade name: TJ40 manufactured by FUJI FILM) having a thickness of 40 μm using a wire bar coater in a manner to obtain a coating thickness as described in Table 2. After the coating was dried by heating in an oven at 60°C for 1 minute, ultraviolet rays were irradiated in a UV curing device under a nitrogen atmosphere (oxygen concentration was 500 ppm or less) to cure the coating, thereby producing protective films A (hard coating films) involved in Examples 1 to 6 and Comparative Examples 1 to 7. In Comparative Examples 6 and 7, a polymethyl methacrylate (PMMA) film having a thickness of 60 μm and a cycloolefin polymer (COP) film having a thickness of 26 μm were used as protective film A. In addition, a COP film having a thickness of 26 μm was used as protective film B.

[0059] [Table 1]

[0060]

[0061] The TAC film surface of protective film A and the polarizer were adhered together using water paste and dried, and then protective film B was adhered to the polarizer using an ultraviolet curable adhesive, and the ultraviolet curable adhesive was cured by irradiating ultraviolet rays to obtain a polarizing plate. It should be noted that in Comparative Example 5, protective film A was used as protective film B.

[0062] (Moisture Permeability)

[0063] According to the moisture permeability test method (cup method) for moisture-proof packaging materials specified in JIS Z 0208:1976, the moisture permeability TA of the protective film A and the moisture permeability TB of the protective film B before being attached to the polarizer were measured under the conditions of 40°C and 90 RH%.

[0064] (degree of curing)

[0065] The hard coat layer of the protective film A was subjected to FT-IR analysis by the ATR method. The FT-IR measurement results showed that the wavelengths of 1782 to 1683 cm -1 Peak height P1, 1427~1374cm -1 The peak height P2 of the peak was used to determine the curing degree P2 / P1. At this time, FT / IR-610 manufactured by JASCO Corporation was used as an infrared spectrometer, and a germanium prism was used as a prism.

[0066] (Pencil hardness)

[0067] Using a pencil (uni, 3H manufactured by Mitsubishi Pencil Co., Ltd.) and a Clemens scratch tester (HA-301, manufactured by TESTERSANGYO Co., Ltd.), a scratch test was performed on the hard coat surface of the protective film A under the conditions of a load of 500 g and a scratch speed of 0.5 mm / sec. The scratch test was performed on 5 samples, and the samples with two or more scratches on the hard coat surface were evaluated as NG, and the other samples were evaluated as OK.

[0068] (Polarization Degree of Polarizing Plate after High-Temperature and High-Humidity Durability Test)

[0069] The polarizing plates involved in each embodiment and each comparative example were placed in a thermostatic chamber at 85°C and 85%RH, and the polarization degree was measured 240 hours and 500 hours after the placement. It should be noted that the polarization degree was calculated by correcting the value measured by an absorptiophotometer with an integrating sphere (V7100, manufactured by JASCO Corporation) using a 2-degree viewing field (C light source) of JIS Z 8701 for visibility.

[0070] Table 2 shows the properties of the protective films A and B according to the examples and comparative examples and the measured values ​​of the polarization degree of the polarizing plate (initial value, before and after the high-temperature and high-humidity durability test).

[0071] [Table 2]

[0072]

[0073] The moisture permeability TA of the protective film A and the moisture permeability TB of the protective film B of the polarizing plates involved in Examples 1 to 6 satisfy the above conditions (1) and (2), and the degree of curing of the hard coating layer of the protective film A satisfies the above condition (3). Therefore, even after being placed in a thermostatic chamber at 85°C and 85%RH for 500 hours, a high polarization value is shown and the surface hardness is also good.

[0074] On the other hand, in Comparative Example 1, the degree of cure P2 / P1 exceeded the range of condition (3), and the pencil hardness of the surface of the protective film A decreased, so the surface hardness also decreased.

[0075] In Comparative Example 2, the moisture permeability TA of the protective film A was lower than the range of condition (1). Therefore, moisture continued to remain in the polarizing plate, and the polarization degree after being placed in a thermostatic chamber at 85°C and 85%RH for 500 hours was lower than that of the example.

[0076] In Comparative Example 3, the moisture permeability TA of the protective film A exceeds the range of condition (1), and the moisture permeability TA of the protective film A becomes high. Therefore, the intrusion of moisture from the outside cannot be fully suppressed, and the polarization degree after being placed in a constant temperature bath at 85°C and 85% RH for 500 hours is inferior to that of the example. In addition, the curing degree P2 / P1 exceeds the range of condition (3), so the pencil hardness of the surface of the protective film A decreases, and the surface hardness also decreases.

[0077] In Comparative Example 4, the degree of curing P2 / P1 is lower than the range of condition (3), so the pencil hardness of the surface of the protective film A is sufficient, but the moisture permeability TA of the protective film A is lower than the range of condition (1). Therefore, moisture continues to remain in the polarizing plate, and the polarization degree after being placed in a constant temperature chamber at 85°C and 85% RH for 500 hours is lower than that of the example.

[0078] In Comparative Example 5, the moisture permeability TB of the protective film A exceeded the range of condition (2), and the moisture permeability TB of the protective film B became high. Therefore, the intrusion of moisture from the outside could not be sufficiently suppressed, and the polarization degree after exposure to a constant temperature chamber at 85°C and 85%RH for 500 hours was lower than that of the examples.

[0079] In Comparative Examples 6 and 7, PMMA film and COP film with extremely low moisture permeability TA were used as protective film A, respectively. After being placed in a constant temperature bath at 85°C and 85% RH for 500 hours, the polarization degree deteriorated. It is believed that this is because the moisture permeability TA of protective film A is too low, so when exposed to high temperature and high humidity, the moisture contained in protective film A and / or adhesive (water paste) continues to remain in the polarizing plate, causing the polarizer to deteriorate. In addition, the protective film A of Comparative Examples 6 and 7 is not provided with a hard coating layer, so the surface hardness is worse than that of the embodiment.

[0080] Industrial Applicability

[0081] The present invention can be used as a polarizing plate used in a display device, and is particularly suitable as a polarizing plate for a display device used in a high temperature environment such as in a vehicle.

[0082] Explanation of symbols

[0083] AProtective FilmA

[0084] B Protective Film

[0085] 1 Polarizer

[0086] 2Transparent substrate

[0087] 3Hard coating

[0088] 10 polarizing plates

Claims

1. A polarizing plate, wherein a protective film A is attached to one surface of a polarizer and a protective film B is attached to the other surface, characterized in that: The protective film A is a hard coating film having a hard coating layer formed on one side of a transparent substrate. The moisture permeability TA of the protective film A and the moisture permeability TB of the protective film B at 40° C. and 90% RH simultaneously satisfy the following conditions (1) and (2), The ATR method using a germanium prism was used to measure the 1782-1683 cm -1 The peak intensity of 1427-1374 cm -1 When the peak intensity of is set to P2, the following condition (3) is satisfied: 240g / m 2 / day>TA>70g / m 2 / day…(1) 70g / m 2 / day≥TB…(2) 0.060≤P2 / P1≤0.150…(3).

2. The polarizing plate according to claim 1, wherein The transparent substrate is a triacetyl cellulose film.

3. The polarizing plate according to claim 1, wherein The protective film A has a pencil hardness of 3H or more.

4. The polarizing plate according to claim 1, wherein The protective film B is a film made of any one of a cycloolefin polymer, polyethylene terephthalate, and polymethyl methacrylate. 5 . A display device comprising the polarizing plate according to claim 1 .

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