Polarizing plate

Abstract

The present application provides a polarizing plate that maintains a high degree of polarization even in a humid heat environment. A polarizing plate comprising a polarizing sheet layer, a phase difference layer, and a resin layer disposed between the polarizing sheet layer and the phase difference layer, the phase difference layer being formed of a cured product of a liquid crystal composition, the resin layer having a Martens hardness of 160 N / mm 2 or more and 500 N / mm 2 or less.

Description

[0001] This application is a divisional application of an application with the application date of June 21, 2019, the application number of 201910547411.5, and the invention name of "polarizing plate". TECHNICAL FIELD

[0002] The present application relates to a polarizing plate, and also relates to an organic electroluminescence display device. BACKGROUND

[0003] In the past, as a polarizing light supplying element in a display device such as a liquid crystal display device and an organic electroluminescence display device (hereinafter also referred to as an organic EL display device), or as a polarizing light detecting element, a polarizing plate has been widely used. As for the polarizing plate, a polarizing plate configured by attaching a protective film (protective layer) to a polarizing film (polarizing plate layer) on one side or both sides using an adhesive or the like is known.

[0004] As the polarizing film, a polarizing film in which a dichroic dye such as iodine is oriented on a film formed of a polyvinyl alcohol-based resin is known. Iodine in the polarizing film exists in the form of an iodine complex, and the iodine complex itself is oriented depending on the orientation of the polyvinyl alcohol-based resin. It is known that the iodine complex absorbs light in the visible region, thereby causing the polarizing film to exhibit a polarizing property (polarizing degree).

[0005] A polarizing plate provided with a polarizing plate layer and a phase difference layer is widely used in an image display device (for example, Patent Document 1).

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENTS

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-54093 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, in a case where the polarizing plate described in Patent Document 1 is left in a humid heat environment (for example, an environment at a temperature of 80°C and a relative humidity of 90%), the polarizing degree sometimes decreases.

[0011] The present application has been achieved in view of such a situation, and an object thereof is to provide a polarizing plate and an organic EL display device that can maintain a high polarizing degree even in a humid heat environment.

[0012] MEANS FOR SOLVING THE PROBLEMS

[0013] The present inventors and others have conducted intensive studies, and as a result, it is presumed that the reason for the decrease in the polarizing degree in a humid heat environment is that a component contained in the phase difference layer is transferred to the polarizing plate layer, and reacts with an iodine complex that contributes to polarized light or a crosslinking point for maintaining the iodine complex, thereby causing the iodine complex to disappear.

[0014] For the presumed reason, the present inventors et al. found that a polarizing plate according to the following can maintain a high degree of polarization even in a hot and humid environment, thereby completing the present application.

[0015] One embodiment of the present application provides a polarizing plate including a polarizing sheet layer, a phase difference layer, and a resin layer disposed between the polarizing sheet layer and the phase difference layer, the phase difference layer being formed of a cured product of a liquid crystal composition, and the resin layer having a Martens hardness of 160 N / mm 2 or more and 500 N / mm 2 or less.

[0016] In one embodiment of the present application, the phase difference layer can be configured as a layer that imparts a 1 / 4 wavelength phase difference.

[0017] One embodiment of the present application provides a polarizing plate including a polarizing sheet layer, a first phase difference layer, a resin layer disposed between the polarizing sheet layer and the first phase difference layer, and a second phase difference layer disposed on the side of the resin layer with the polarizing sheet layer as a reference, the first phase difference layer being formed of a cured product of a first liquid crystal composition, the second phase difference layer being formed of a cured product of a second liquid crystal composition, and the resin layer having a Martens hardness of 160 N / mm 2 or more and 500 N / mm 2 or less.

[0018] In one embodiment of the present application, the first phase difference layer can be configured as a layer that satisfies the relationship of n x ≥ n y ≥ n z when the in-plane refractive index in the slow axis direction is set to n z , the in-plane refractive index in the direction orthogonal to the slow axis direction is set to n x , and the thickness direction refractive index is set to n y .

[0019] In one embodiment of the present application, the second phase difference layer can be configured to be disposed between the resin layer and the first phase difference layer and to be in contact with the resin layer.

[0020] In one embodiment of the present application, the second phase difference layer can be configured to be disposed between the resin layer and the polarizing sheet layer and to be in contact with the resin layer.

[0021] In one embodiment of the present application, the resin layer can be configured to be in contact with the first phase difference layer.

[0022] In one embodiment of the present application, the second phase difference layer can be configured as a layer that imparts a 1 / 4 wavelength phase difference.

[0023] One embodiment of the present application provides an organic electroluminescent display device including: an organic electroluminescent display element; and the polarizing plate described above disposed on the observation side of the organic electroluminescent display element.

[0024] Effects of the Invention

[0025] According to one embodiment of the present application, a polarizing plate and an organic EL display device that maintain a high degree of polarization even in a humid heat environment can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a cross-sectional schematic view showing an example of the layer structure of the polarizing plate of the first embodiment.

[0027] Figure 2 is a schematic view showing an example of the manufacturing method of the polarizing plate of the first embodiment.

[0028] Figure 3 is a cross-sectional schematic view showing an example of the structure of the organic EL display device of the first embodiment.

[0029] Figure 4 is a schematic cross-sectional view showing an example of the layer structure of the organic EL element.

[0030] Figure 5 is a cross-sectional schematic view showing an example of the layer structure of the polarizing plate of the second embodiment.

[0031] Figure 6 is a schematic view showing an example of the manufacturing method of the polarizing plate of the second embodiment.

[0032] Figure 7 is a cross-sectional schematic view showing an example of the layer structure of the polarizing plate of the third embodiment.

[0033] Figure 8 is a schematic view showing an example of the manufacturing method of the polarizing plate of the third embodiment.

[0034] Figure 9 is a cross-sectional schematic view showing an example of the layer structure of the polarizing plate of the fourth embodiment.

[0035] Figure 10 is a schematic view showing an example of the manufacturing method of the polarizing plate of the fourth embodiment.

[0036] Figure 11 is a cross-sectional schematic view showing an example of the layer structure of the polarizing plate of the fifth embodiment.

[0037] Figure 12 is a schematic view showing an example of the manufacturing method of the polarizing plate of the fifth embodiment.

[0038] Description of Reference Numerals

[0039] 1, 2, 3, 4, 5 ... polarizing plate,

[0040] 12 ...polarizer layer,

[0041] 13 ...resin layer,

[0042] 16 ...phase difference layer,

[0043] 17 ...first phase difference layer,

[0044] 18 ...Second phase difference layer DETAILED DESCRIPTION

[0045] <First embodiment>

[0046] [Polarizing plate]

[0047] The following is based on Figure 1 The polarizing plate according to the first embodiment will be described.

[0048] Note that the drawings used in the following description may sometimes be enlarged for the purpose of emphasizing a characteristic portion, and the dimensional ratios of the various components are not necessarily the same as those in actual figures. Furthermore, for the same purpose, non-characteristic portions may sometimes be omitted from the illustration.

[0049] Figure 1 1 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate of the first embodiment. Figure 1 As shown, the polarizing plate 1 of this embodiment includes a protective layer 11, a polarizer layer 12, a resin layer 13, a first adhesive layer 14, a second adhesive layer 15, a phase difference layer 16, and an alignment layer 19. Figure 1 As shown, the polarizing plate 1 has a layer structure including a protective layer 11 (protective film) only on one side 12a of the polarizer layer 12. Among polarizing plates, those having a protective film only on one side of the polarizer layer tend to have a low polarization degree, and thus the effect of the present invention is significant.

[0050] In this specification, the “polarizer layer” refers to an optical layer having a property of transmitting linearly polarized light having a vibration plane orthogonal to its absorption axis when unpolarized light is incident.

[0051] A retardation layer 16 is disposed on the other surface 12 b of the polarizing plate layer 12 .

[0052] The resin layer 13 is disposed between the polarizer layer 12 and the retardation layer 16. The resin layer 13 is in contact with the polarizer layer 12 at one surface 13a thereof.

[0053] The first adhesive layer 14 is disposed between the resin layer 13 and the phase difference layer 16, and adheres the resin layer 13 and the phase difference layer 16.

[0054] The orientation layer 19 is disposed on the side opposite to the resin layer 13 with the phase difference layer 16 as a reference, and is in contact with the surface 16b of the phase difference layer 16.

[0055] The second adhesive layer 15 is disposed on the side opposite to the phase difference layer 16 with the orientation layer 19 as a reference, and is in contact with the surface (the other surface) 19b of the orientation layer 19. When the polarizing plate 1 is applied to the organic EL display device described later, the polarizing plate 1 is adhered to the display panel via the second adhesive layer 15.

[0056] The side of the one surface 12a of the polarizing plate layer 12 is a surface on the observation side when the polarizing plate 1 is applied to the organic EL display device described later. The protective layer 11 is disposed on the side of the one surface 12a of the polarizing plate layer 12. The protective layer 11 is adhered to the polarizing plate layer 12 via an adhesive (not shown).

[0057] The polarizing plate 1 can be in a long strip shape, or can be a single piece obtained by cutting a long strip-shaped polarizing plate to a prescribed length. The long strip-shaped polarizing plate includes a long strip-shaped protective layer, a long strip-shaped polarizing plate layer, and a long strip-shaped resin layer.

[0058] Hereinafter, each layer constituting the polarizing plate 1 of the first embodiment will be described in detail.

[0059] (Polarizing plate layer)

[0060] As the polarizing plate layer 12, any appropriate polarizing plate layer can be used. For example, the resin film forming the polarizing plate layer 12 can be a single-layer resin film, or can be a laminated film of two or more layers. The polarizing plate layer 12 can be a cured film in which a dichroic dye is oriented to a polymerizable liquid crystal compound, and the polymerizable liquid crystal compound is polymerized.

[0061] As a specific example of the polarizing plate layer 12 composed of a single-layer resin film, a film subjected to dyeing treatment based on a dichroic substance such as iodine or a dichroic dye, and stretching treatment, a polyene-based orientation film, and the like can be given.

[0062] As the hydrophilic polymer film, a polyvinyl alcohol (hereinafter, sometimes referred to as PVA) film, a partially formalized PVA film, an ethylene-vinyl acetate copolymer partially saponified film, and the like can be given.

[0063] As the polyene-based orientation film, a dehydrated product of PVA or a dehydrochlorinated product of polyvinyl chloride, and the like can be given.

[0064] As the polarizing plate layer 12, a film obtained by dyeing a PVA-based film with iodine and uniaxially stretching the same is preferably used from the viewpoint of excellent optical properties.

[0065] Iodine in the polarizing plate layer exists in the form of an iodine complex, which is oriented depending on the orientation of the PVA-based resin, and the iodine complex itself is also oriented. It is known that this iodine complex absorbs light in the visible region, thereby causing the polarizing plate layer to exhibit a polarizing property (polarization degree).

[0066] A PVA-based resin having a saponification degree of 85 to 100 mol%, preferably 98 mol% or more can be modified, and for example, a polyvinyl formal or polyvinyl acetal modified with an aldehyde or the like can also be used. The PVA resin has a polymerization degree of 1000 to 10000, preferably 1500 to 5000.

[0067] The thickness of the polarizing plate layer 12 is preferably 2 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more. In addition, the thickness of the polarizing plate layer 12 is preferably 30 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less. Note that the above upper limit and lower limit values can be combined arbitrarily.

[0068] If the thickness of the polarizing plate layer 12 is thin, iodine at the end portion of the polarizing plate layer 12 is easily removed in an environment of high temperature and high humidity. Therefore, the thickness of the polarizing plate layer 12 is preferably 5 μm or more. In addition, in the case where the thickness of the polarizing plate layer 12 is thick, breakage of the polarizing plate layer 12 easily occurs in a cold-heat exchange test. Therefore, the thickness of the polarizing plate layer is preferably 15 μm or less.

[0069] In the present specification, the "thickness of a layer" refers to the dimension in the stacking direction of the layer in a polarizing plate. As the "layer" in the present embodiment, for example, a protective layer, a polarizing plate layer, a resin layer, a first adhesive layer, a phase difference layer, a second adhesive layer, and the like can be cited.

[0070] The thickness of a layer can be obtained, for example, by measuring the thickness of the layer at any nine points using a white interference type non-contact film thickness meter or a contact type film thickness meter, and calculating the average value thereof.

[0071] In the case of using a non-contact film thickness meter, precise measurement can be performed without contacting the measurement object. Therefore, even if the measurement object is a part of a layered body, the film thickness of the measurement object can be measured without peeling the layers.

[0072] (Protective Layer)

[0073] As the protective layer 11, a film formed of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, stretchability, and the like is used.

[0074] As specific examples of such thermoplastic resins, there can be mentioned: cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether sulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymers; cyclic polyolefin resins having a cyclic structure and a norbornene structure (also referred to as norbornene-based resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins; and mixtures thereof.

[0075] In order to improve the adhesion to the polarizing plate layer formed of a PVA-based resin and a dichroic substance, a surface treatment (e.g., corona treatment) or the like can be applied to the film formed of a thermoplastic resin, or a primer layer (also referred to as a base coat layer) or the like can be formed.

[0076] The moisture permeability of the protective layer 11 at a temperature of 40°C and a relative humidity of 90% RH is preferably 1 to 1500 g / m 2 • 24 hr. The moisture permeability can be measured in accordance with JIS Z 0208:1976.

[0077] The thickness of the protective layer 11 is preferably 3 μm or more, more preferably 5 μm or more, and can also be 15 μm or more. In addition, the thickness of the protective layer 11 is preferably 50 μm or less, more preferably 30 μm or less. Note that the upper and lower limits described above can be combined arbitrarily.

[0078] (Phase difference layer)

[0079] The phase difference layer 16 can be, for example, a positive A layer, a negative A layer, a positive C layer or a negative C layer. Specifically, if the phase difference layer 16 is an A layer, it is preferably a layer imparting a positive front phase difference of 1 / 4 wavelength or a layer imparting a positive front phase difference of 1 / 2 wavelength.

[0080] In the case where the phase difference layer 16 is a C layer, the value of the phase difference in the thickness direction Rth at a wavelength of 550 nm is preferably -90 nm to -10 nm. A C layer in this range is excellent in durability and also enables thinning.

[0081] In this specification, the “layer that imparts a front phase difference of 1 / 4 wavelength” is a phase difference layer that converts linearly polarized light of a wavelength in the visible light region into circularly polarized light (or converts circularly polarized light into linearly polarized light). The front phase difference value of the “layer that imparts a front phase difference of 1 / 4 wavelength” at a wavelength of 550nm can be 110nm to 160nm, or 130nm to 150nm. The “layer that imparts a front phase difference of 1 / 2 wavelength” is a phase difference layer that converts the polarization orientation of linearly polarized light of a wavelength in the visible light region by 90°. The front phase difference value of the “layer that imparts a front phase difference of 1 / 2 wavelength” at a wavelength of 550nm can be 250nm to 300nm, or 260nm to 280nm.

[0082] In this specification, a "positive C layer" refers to a layer having a refractive index in the slow axis direction in the plane as n x The refractive index in the fast axis direction of the plane is set to n y , and the refractive index in the thickness direction is set to n z When n is satisfied z >n x ≥n y The layer of this relationship. x and n y Specifically, if n x With n y If the difference is within 0.01, then we can say that n x and n y Substantially equal.

[0083] In this specification, a "negative C layer" refers to a layer having a refractive index in the slow axis direction in the plane set to n. x The refractive index in the fast axis direction of the plane is set to n y , and the refractive index in the thickness direction is set to n z When n is satisfied z <n y ≤n x The layer of this relationship. x and n y Specifically, if n x With n y If the difference is within 0.01, then we can say that n x and n y Substantially equal.

[0084] The polarizing plate 1 including the polarizer layer 12 and the retardation layer 16 can preferably function as a circularly polarizing plate. That is, the retardation layer 16 is preferably a layer that imparts a retardation of 1 / 4 wavelength.

[0085] The phase difference layer 16 is formed using a cured product of a liquid crystal composition as a forming material. The liquid crystal composition contains a liquid crystal compound.

[0086] The kind of the liquid crystal compound used in the present embodiment is not particularly limited, and can be classified into a rod-like type (rod-like liquid crystal compound) and a disc-like type (disc-like liquid crystal compound, discotic liquid crystal compound) according to the shape thereof. Further, there are low-molecular type and high-molecular type, respectively. Note that the high-molecular generally refers to a high-molecule having a polymerization degree of 100 or more.

[0087] In the present embodiment, any liquid crystal compound can be used. Further, two or more kinds of rod-like liquid crystal compounds, two or more kinds of disc-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disc-like liquid crystal compound can also be used.

[0088] Note that the rod-like liquid crystal compound and the disc-like liquid crystal compound can use a publicly known material.

[0089] The cured product of the liquid crystal compound is more preferably formed using a rod-like liquid crystal compound having a polymerizable group or a disc-like liquid crystal compound having a polymerizable group. Thereby, it is possible to reduce the temperature change or the humidity change of the optical characteristics.

[0090] Two or more kinds of liquid crystal compounds can be used in combination. In this case, it is preferable that at least one of them has two or more polymerizable groups in the molecule. That is, the cured product of the liquid crystal compound is preferably a cured product formed by polymerization of a rod-like liquid crystal compound having a polymerizable group or a disc-like liquid crystal compound having a polymerizable group. In this case, it is not necessary to exhibit liquid crystal properties after becoming a cured product.

[0091] In the case where the rod-like liquid crystal compound or the disc-like liquid crystal compound has a polymerizable group, the kind of the polymerizable group is not particularly limited. As the polymerizable group, a functional group capable of undergoing an addition polymerization reaction, such as a polymerizable ethylenic unsaturated group or a ring polymerizable group, is preferable. More specifically, as the polymerizable group, (meth)acryloyl group, vinyl group, styryl group, allyl group, and the like can be exemplified. Among them, (meth)acryloyl group is preferable. Note that (meth)acryloyl group refers to a concept including both methacryloyl group and acryloyl group.

[0092] An ingredient other than the above-described liquid crystal compound can be contained in the liquid crystal composition.

[0093] For example, a polymerization initiator can be contained in the liquid crystal composition. The polymerization initiator used is selected according to the form of the polymerization reaction, such as a thermal polymerization initiator or a photopolymerization initiator.

[0094] As the photopolymerization initiator, for example, an α-ketone compound, an acyloin ether, an α-hydrocarbon-substituted aromatic acyloin compound, a polynuclear quinone compound, a combination of a triaryl imidazole dimer and a p-aminophenyl ketone, or the like can be exemplified.

[0095] The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, relative to the total solid content in the liquid crystal composition.

[0096] In the liquid crystal composition, a polymerizable monomer can be contained for the purpose of improving the uniformity of a film coated with the liquid crystal composition and the strength of the film. As the polymerizable monomer, a radical polymerizable or cationic polymerizable compound can be exemplified. Among them, a multifunctional radical polymerizable monomer is preferred.

[0097] Note that, as the polymerizable monomer, a polymerizable monomer capable of copolymerizing with a liquid crystal compound having the above-described polymerizable group (hereinafter also referred to as a polymerizable liquid crystal compound) is preferred.

[0098] As the polymerizable monomer, a publicly known material can be used.

[0099] The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, relative to the total mass of the liquid crystal compound.

[0100] In the liquid crystal composition, a publicly known surfactant can be contained for the purpose of improving the uniformity of a film coated with the liquid crystal composition and the strength of the film. As the surfactant, a publicly known compound can be exemplified. Among them, a fluorine-based compound is particularly preferred.

[0101] A solvent can be contained in the liquid crystal composition, and an organic solvent is preferably used.

[0102] As the organic solvent, for example, an amide such as N,N-dimethylformamide; a sulfoxide such as dimethyl sulfoxide; a heterocyclic compound such as pyridine; a hydrocarbon such as benzene, hexane; a halogenated alkane such as chloroform, dichloromethane; an ester such as methyl acetate, ethyl acetate, butyl acetate; a ketone such as acetone, methyl ethyl ketone; an ether such as tetrahydrofuran, 1,2-dimethoxyethane can be exemplified. Among them, as the organic solvent, a halogenated alkane, a ketone is preferred. In addition, two or more kinds of organic solvents can be used in combination.

[0103] In the liquid crystal composition, in addition to the above-described components, a close contact improver, a plasticizer, a polymer, or the like can be contained.

[0104] A cured product of the liquid crystal composition can be formed by coating the liquid crystal composition on the alignment layer 19 described later and subjecting it to horizontal alignment, vertical alignment, or oblique alignment, and then curing.

[0105] The thickness of the phase difference layer 16 is preferably 0.1 μm or more. In addition, the thickness of the phase difference layer 16 is preferably 10 μm or less, more preferably 5 μm or less. Note that the above upper limit and lower limit values can be combined arbitrarily.

[0106] If the thickness of the phase difference layer 16 is within the above range, both durability and thinness can be achieved.

[0107] The thickness of the phase difference layer 16 is preferably adjusted in a manner that a desired in-plane retardation value and a thickness direction retardation value can be obtained.

[0108] In a case where a polarizing plate having a polarizing plate layer such as the polarizing plate layer 12 and a phase difference layer such as the phase difference layer 16 is left in a humid heat environment (for example, an environment at a temperature of 80°C and a relative humidity of 90%), the degree of polarization sometimes decreases.

[0109] The present inventors and others have speculated that the reason for the decrease in the degree of polarization of the polarizing plate in the humid heat environment is that the iodine complex disappears. As a reason for the disappearance of the iodine complex, it is considered that a component contained in the phase difference layer migrates to the polarizing plate layer and reacts with the iodine complex that contributes to polarized light or a crosslinking point for holding the iodine complex.

[0110] With respect to the speculated reason, the present inventors and others have made the following assumption: by inhibiting the migration of the component contained in the phase difference layer to the polarizing plate layer, it is possible to inhibit the decrease in the degree of polarization. As a result of repeated research by the present inventors and others, it has been found that by providing the following resin layer between the polarizing plate layer and the phase difference layer, it is possible to maintain a high degree of polarization even in a humid heat environment, and thus the present application has been completed.

[0111] (Resin layer)

[0112] The resin layer 13 is preferably formed of a reaction product of a resin composition containing a (meth)acrylic resin and a multifunctional monomer.

[0113] ((Meth)acrylic resin)

[0114] The (meth)acrylic resin contained in the resin composition is preferably a polymer (hereinafter also referred to as a (meth)acrylate polymer) containing a structural unit derived from a urethane (meth)acrylate or an alkyl (meth)acrylate represented by the following formula (I) (hereinafter also referred to as structural unit (I)).

[0115] In the present specification, "(meth)acrylic acid" means either one of acrylic acid or methacrylic acid. The same applies to "(meth)" in "(meth)acrylate" and the like.

[0116] In the present specification, "from" means that a chemical structure is changed due to polymerization of a raw material monomer, but no other structural change occurs.

[0117] The urethane (meth) acrylate can be an aliphatic urethane (meth) acrylate or an aromatic urethane (meth) acrylate. The urethane acrylate is prepared, for example, using a (meth) acrylic acid and / or a (meth) acrylate ester, a polyol, and a diisocyanate. Specifically, the urethane acrylate can be produced by a method of using a hydroxy (meth) acrylate prepared from a polyol and a (meth) acrylic acid and / or a (meth) acrylate ester, which has at least one hydroxy group remaining, and reacting it with a diisocyanate.

[0118] As the (meth) acrylate used in the production of the urethane acrylate, there are exemplified, for example, (meth) acrylate alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) acrylate; and (meth) acrylate cycloalkyl esters such as cyclohexyl (meth) acrylate.

[0119] The polyol used in the production of the urethane acrylate is a compound having at least two hydroxy groups in the molecule. If specific examples are exemplified, there are ethylene glycol, trimethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol ester of hydroxypivalic acid, cyclohexanedimethanol, 1,4-cyclohexanediol, spiro glycol, tricyclodecane dimethanol, hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene oxide-added bisphenol A, trimethylol ethane, tris (dimethylol) propane, glycerol, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, glucose, and the like.

[0120] The diisocyanate used in the production of the urethane acrylate can be various diisocyanates of aromatic, aliphatic, or alicyclic types. If specific examples are exemplified, there are tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 1,5-naphthalene diisocyanate, diphenyl-4,4'-diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and hydrogenates of compounds having aromatic rings in them, and the like.

[0121] The weight average molecular weight (hereinafter also referred to as Mw) of the urethane (meth)acrylate is preferably 100 to 1000.

[0122]

[0123] In formula (I), R 10 represents a hydrogen atom or a methyl group. R 20 represents an alkyl group having 1 to 20 carbon atoms. The above alkyl group can have any of a linear, branched or cyclic structure. The hydrogen atom of the above alkyl group can be substituted with an alkoxy group having 1 to 10 carbon atoms or a urethane group having 1 to 10 carbon atoms.

[0124] As the (meth)acrylate represented by formula (I), for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, t-butyl (meth)acrylate, and the like can be exemplified.

[0125] As the specific examples of the alkyl (meth)acrylate containing an alkoxy group, 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and the like can be exemplified.

[0126] Among them, as the (meth)acrylate represented by formula (I), n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is preferably contained, and n-butyl (meth)acrylate is more preferably contained.

[0127] The (meth)acrylate polymer can contain a structural unit from another monomer other than the structural unit (I). The structural unit from another monomer can be one or two or more. As the other monomer which the (meth)acrylate polymer can contain, a monomer having a polar functional group, a monomer having an aromatic group, an acrylamide-based monomer can be exemplified.

[0128] As the monomer having a polar functional group, a (meth)acrylate having a polar functional group can be exemplified. As the polar functional group, a hydroxyl group, a carboxyl group, a substituted amino group, an unsubstituted amino group, and the like can be exemplified. As the polar functional group, a heterocyclic group such as an epoxy group, and the like can also be exemplified.

[0129] The content of the structural unit derived from the monomer having a polar functional group in the (meth)acrylate polymer is preferably 20 parts by mass or less, more preferably 0.1 parts by mass or more and 20 parts by mass or less, further preferably 0.1 parts by mass or more and 10 parts by mass or less, particularly preferably 0.5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total structural units of the (meth)acrylate polymer.

[0130] As the monomer having an aromatic group, a (meth)acrylate having one (meth)acryloyl group and one or more aromatic rings (e.g., benzene ring, naphthalene ring, etc.) in the molecule and having a phenyl group, phenoxyethyl group, or benzyl group can be exemplified. By including these structural units, whitening of the polarizing plate produced under a high-temperature, high-humidity environment can be suppressed.

[0131] The content of the structural unit derived from the monomer having an aromatic group in the (meth)acrylate polymer is preferably 50 parts by mass or less, more preferably 4 parts by mass or more and 50 parts by mass or less, further preferably 4 parts by mass or more and 25 parts by mass or less, relative to 100 parts by mass of the total structural units of the (meth)acrylate polymer.

[0132] As the acrylamide-based monomer, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-(2-methylpropoxymethyl)acrylamide, and the like can be exemplified. By including these structural units, bleeding of an additive such as an antistatic agent described later can be suppressed.

[0133] Further, as the structural unit derived from other monomers other than the structural unit (I), a structural unit derived from a styrene-based monomer, a structural unit derived from a vinyl-based monomer, a structural unit derived from a monomer having a plurality of (meth)acryloyl groups in the molecule, and the like can be included.

[0134] The weight average molecular weight (Mw) of the (meth)acrylate polymer is preferably 500,000 to 2,500,000. If the weight average molecular weight is 500,000 or more, the durability of the resin layer 13 under a high-temperature, high-humidity environment can be improved. If the weight average molecular weight is 2,500,000 or less, the handleability at the time of applying the resin composition becomes good. The molecular weight distribution (Mw / Mn) indicated by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (hereinafter also referred to simply as Mn) is, for example, 2 to 10.

[0135] In the present specification, the "weight average molecular weight" and the "number average molecular weight" are polystyrene conversion values measured by a gel permeation chromatography (GPC) method.

[0136] From the viewpoint of adhesiveness and durability, the glass transition temperature of the (meth)acrylic resin is preferably -60°C to -10°C. Note that the glass transition temperature can be measured using a differential scanning calorimeter (DSC).

[0137] The (meth)acrylic resin can include two or more (meth)acrylate polymers.

[0138] (multi-functional monomer)

[0139] In the present specification, the multi-functional monomer refers to a multi-functional (meth)acrylate monomer having three or more (meth)acryloyloxy groups in a molecule.

[0140] As the multi-functional (meth)acrylate monomer of three or more functions, there can be mentioned poly(meth)acrylates of aliphatic polyols of three or more functions such as glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, di(trimethylol)propane tri(meth)acrylate, di(trimethylol)propane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, di-pentaerythritol tetra(meth)acrylate, di-pentaerythritol penta(meth)acrylate, and di-pentaerythritol hexa(meth)acrylate. In addition, there can be mentioned poly(meth)acrylates of halogen-substituted polyols of three or more functions, tri(meth)acrylates of alkylene oxide adducts of glycerol, tri(meth)acrylates of alkylene oxide adducts of trimethylolpropane, 1,1,1-tris[(meth)acryloyloxyethoxyethoxy]propane, tri(hydroxyethyl)isocyanurate tri(meth)acrylate, urethane (meth)acrylates, and the like.

[0141] The resin composition preferably includes a publicly known radical polymerization initiator.

[0142] (other components)

[0143] The resin composition can include additives such as a single or two or more ultraviolet absorbers, antistatic agents, solvents, crosslinking catalysts, tackifying resins (tackifiers), plasticizers, and the like. In addition, it is also useful to form a resin layer 13 by incorporating an ultraviolet-curable compound in the resin composition and then curing it by irradiation of ultraviolet rays to make a harder resin layer.

[0144] The reaction product of such a resin composition forms a crosslinked structure. Therefore, it is considered that the resin layer 13 is capable of inhibiting the components contained in the phase difference layer 16 from being transferred into the polarizing plate layer 12. In addition, it is considered that the more dense the crosslinked structure is, the less the components contained in the phase difference layer 16 are transferred into the polarizing plate layer 12 and are instead retained in the resin layer 13.

[0145] The density of the cross-linked structure can be indirectly confirmed by measuring the Martens hardness of the resin layer 13 according to ISO 14577. As the number of cross-linking points in the resin layer 13 increases, the distance between the polymer molecules decreases, resulting in a denser cross-linked structure. Furthermore, the bonding strength between the polymer molecules increases, making deformation less likely, thereby increasing the hardness of the resin layer 13. In other words, in the resin layer 13, the greater the hardness, the denser the cross-linked structure.

[0146] The Martens hardness of the resin layer 13 is 160 N / mm 2 Above and 500N / mm 2 Below, can also be less than 500N / mm 2 If the Martens hardness of the resin layer 13 is 500N / mm 2 Below this, the polymer molecular chains of the resin layer 13 can move, and the flexibility of the resin layer 13 becomes sufficiently high. It is believed that if the flexibility of the resin layer 13 is sufficiently high, the resin layer is less likely to break due to the expansion and contraction of the polarizer layer. As a result, the flexibility of the polarizing plate 1 becomes sufficiently high. On the other hand, it is believed that if the Martens hardness is 160N / mm 2 The crosslinked structure becomes sufficiently dense, and the components contained in the retardation layer 16 can be sufficiently suppressed from migrating to the polarizer layer 12. As a result, the polarization degree of the polarizing plate 1 is unlikely to decrease even in a hot and humid environment (e.g., a temperature of 80°C and a relative humidity of 90%).

[0147] The Martens hardness is preferably 170 N / mm 2 More than 190N / mm 2 In addition, the Martens hardness is more preferably 400N / mm 2 Below, can also be less than 400N / mm 2 It should be noted that the above-mentioned upper limit value and lower limit value can be arbitrarily combined.

[0148] In this embodiment, the Martens hardness is preferably 160 N / mm 2 Above and 500N / mm 2 The mixing ratio of the (meth)acrylic resin, polyfunctional monomer, etc. used can be appropriately adjusted within the following range. For example, the mixing ratio of the polyfunctional monomer to the (meth)acrylic resin can be 15:85 to 85:15, or 40:60 to 80:20.

[0149] Generally, a resin layer having such a Martens hardness is rarely placed inside a laminate (polarizing plate). The reason for this is that even if the Martens hardness is 500 N / mm, the resin layer is fixed inside the laminate. 2 Next, the resin layer may also break due to expansion and contraction of the polarizer layer.

[0150] On the other hand, in the present embodiment, the resin layer 13 having such Martens hardness is disposed inside the polarizing plate 1. In order to suppress the breakage of the resin layer 13 due to the expansion and contraction of the polarizing plate layer 12, the breakage load of the resin layer 13 is preferably 500 g or more and 2000 g or less, and can be less than 2000 g.

[0151] The breakage load of the resin layer 13 can be measured in the following manner. A handy compression tester (KES-G5) manufactured by KATO TECH Co., Ltd. can be used in the measurement. The test piece (resin layer) is held with a jig having a through hole (11 mm in diameter) in the center, which is provided in the above tester. Here, the size of the test piece used is such that it covers the above through hole, and the thickness of the test piece is the thickness of the resin layer. Next, a pressure head is pressed into the test piece. The load at the time when the test piece is broken by the pressure head or the pressure head penetrates the test piece is defined as the breakage load (unit: g). The pressure head used is a pressure head having a spherical tip with a diameter of 1 mm. The speed at which the pressure head is pressed is set to 0.33 cm / sec. The temperature of the environment in which the breakage load is measured is set to 23°C. In the case where the handy compression tester (KES-G5) is used, the sensitivity is set to 10, and the voltage is set to 5 mm / 10 V.

[0152] In the present embodiment, the blending ratio of the (meth)acrylic resin, the polyfunctional monomer, and the like, which form the resin layer, is appropriately adjusted so as to be within the range where the breakage load is 500 g or more and 2000 g or less. For example, the blending ratio of the polyfunctional monomer to the (meth)acrylic resin can be 15:85 to 85:15, or 40:60 to 80:20.

[0153] Next, the method for measuring the Martens hardness of the resin layer 13 will be described. The Martens hardness of the resin layer 13 is measured by performing an indentation test in accordance with ISO 14577. Specifically, as a film hardness meter, a nanoindenter tester (ENT-2100) manufactured by Elionix Co., Ltd. can be used, as described in the column of Examples. A test sample formed of the resin layer 13 is set in the above tester, and a Berkovich pressure head is brought into contact with and pressed into the test sample, whereby the Martens hardness can be measured. The initial load is set to 0 mN, and the maximum load is set to 0.5 mN.

[0154] The maximum load is maintained, i.e., the time for which the maximum load is maintained, can be set to 1000 m seconds. The temperature of the environment in which the Martens hardness is measured can be set to 23°C.

[0155] It is also preferable to make the thickness of the resin layer 13 a prescribed value or more. The thickness of the resin layer 13 is preferably 0.5 μm or more, can be 1 μm or more, can be 3 μm or more, and can be 8 μm or more. The upper limit of the thickness of the resin layer 13 is not particularly limited. For example, in order to reduce the degree of curing shrinkage of the resin layer 13, the thickness of the resin layer 13 can be 20 μm or less, or can be 15 μm or less.

[0156] (First Adhesive Layer)

[0157] In the present specification, an "adhesive" refers to a substance that exhibits a soft rubber-like state and exhibits adhesion by itself by being attached to an adherend. In addition, the energy ray-curable adhesive described later can adjust the adhesion by irradiation of energy rays.

[0158] As the adhesive constituting the first adhesive layer 14, an adhesive known in the past that is excellent in optical transparency can be used without particular limitation, and for example, an adhesive having an acrylic, urethane, silicone, polyvinyl ether, or the like as a base polymer can be used. In addition, as the adhesive constituting the first adhesive layer 14, an energy ray-curable adhesive, a heat-curable adhesive, or the like can be used.

[0159] "Energy ray-curable" refers to a property of being cured by irradiation of energy rays such as ultraviolet rays or electron rays. An energy ray-curable adhesive has adhesion even before irradiation of energy rays. Therefore, an energy ray-curable adhesive can be closely adhered to an adherend and the close adhesion can be adjusted by curing by irradiation of energy rays.

[0160] An energy ray-curable adhesive contains an acrylic adhesive and an energy ray-polymerizable compound. A crosslinking agent is preferably blended in an energy ray-curable adhesive. In addition, a photopolymerization initiator or a photosensitizer, or the like can be blended in an energy ray-curable adhesive as needed.

[0161] Among them, an adhesive having an acrylic resin as a base polymer is suitable in that it is excellent in transparency, adhesion, re-peeling properties, weather resistance, heat resistance, and the like.

[0162] The thickness of the first adhesive layer 14 is preferably 3 μm or more, and more preferably 5 μm or more. In addition, the thickness of the first adhesive layer 14 is preferably 40 μm or less, and more preferably 30 μm or less. Note that the above upper limit and lower limit values can be combined arbitrarily. If the thickness of the first adhesive layer 14 is 3 μm or more, the resin layer 13 and the phase difference layer 16 can be sufficiently adhered. If the thickness of the first adhesive layer 14 is 40 μm or less, the phase difference layer 16 is less likely to be shifted.

[0163] In manufacturing the polarizing plate 1 of the present embodiment, when the resin layer 13 and the phase difference layer 16 are laminated via the first adhesive layer 14 under a strong pressure, the thickness of the first adhesive layer 14 is sometimes made thinner than when the lamination is performed under a weak pressure. This is caused by the stretchability of the first adhesive layer 14, and if the resin layer 13 and the phase difference layer 16 are left for a while after the lamination, the thickness of the first adhesive layer 14 becomes the original thickness. Therefore, when the resin layer 13 and the phase difference layer 16 are laminated via the first adhesive layer 14 under a strong pressure, a constant value can be obtained by measuring the thickness of the first adhesive layer 14 after, for example, 5 minutes have passed.

[0164] (Oriented layer)

[0165] The oriented layer 19 is not limited to a vertical alignment layer that vertically aligns the molecular axis of the liquid crystal compound, but can be a horizontal alignment layer that horizontally aligns the molecular axis of the liquid crystal compound, or a tilted alignment layer that tilts the molecular axis of the liquid crystal compound.

[0166] As the oriented layer 19, a material having solvent resistance that does not dissolve due to the coating of the liquid crystal composition or the like is preferable. In addition, as the oriented layer 19, a material having heat resistance to a heat treatment for removing a solvent or aligning the liquid crystal compound is preferable.

[0167] As the material of the oriented layer 19, an alignment film containing an alignment polymer, a photo-alignment film, or a groove alignment film in which a concave-convex pattern or a plurality of grooves are formed on the surface and aligned can be exemplified.

[0168] The thickness of the oriented layer 19 is, for example, in the range of 10 nm or more and 10,000 nm or less, preferably in the range of 10 nm or more and 1,000 nm or less, more preferably in the range of 10 nm or more and 500 nm or less, and further preferably in the range of 10 nm or more and 200 nm or less.

[0169] As the resin used in the oriented layer 19, there is no particular limitation as long as it is a resin used as a material of a known alignment film, and a cured product of a (meth)acrylate monomer of a single or multiple functionality that has been publicly known in the past, which is cured in the presence of a polymerization initiator, or the like can be used.

[0170] Specifically, as the resin used in the alignment layer 19, as the (meth)acrylate-based monomer, for example, 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono 2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, urethane acrylate, and the like can be exemplified.

[0171] Note that the resin used in the alignment layer 19 can be one of them, or a mixture of two or more of them.

[0172] (Second Adhesive Layer)

[0173] As the adhesive constituting the second adhesive layer 15, an adhesive excellent in optical transparency conventionally known can be used without particular limitation.

[0174] As the adhesive constituting the second adhesive layer 15, the same materials as those exemplified above as the adhesive constituting the first adhesive layer 14 can be used. The thickness of the first adhesive layer 14 and the thickness of the second adhesive layer 15 can be the same or different.

[0175] The thickness of the second adhesive layer 15 is preferably 3 μm or more, more preferably 5 μm or more. In addition, the thickness of the second adhesive layer 15 is preferably 40 μm or less, more preferably 30 μm or less. Note that the upper limit value and the lower limit value described above can be combined arbitrarily.

[0176] If the thickness of the second adhesive layer 15 is 3 μm or more, the phase difference layer and the display panel described later can be sufficiently adhered. If the thickness of the second adhesive layer 15 is 40 μm or less, the phase difference layer 16 disposed via the second adhesive layer 15 and the display panel described later are less likely to be shifted.

[0177] When the phase difference layer 16 is attached to the display panel via the second adhesive layer 15 under a strong pressure in the production of the organic EL display device described later, the thickness of the second adhesive layer 15 is sometimes made thinner than when the attachment is performed under a weak pressure. This is caused by the stretchability of the second adhesive layer 15, and the thickness of the second adhesive layer becomes the original thickness if the phase difference layer 16 is attached to the display panel and left for a while. Therefore, when the phase difference layer 16 is attached to the display panel via the second adhesive layer 15 under a strong pressure, a constant value can be obtained by measuring the thickness of the second adhesive layer 15 after, for example, 5 minutes have passed.

[0178] (Polarizing plate)

[0179] The total thickness of the polarizing plate 1 is preferably 30 μm or more. In addition, the total thickness of the polarizing plate 1 is preferably 500 μm or less, more preferably 300 μm or less, and further preferably 100 μm or less. Note that the upper limit and the lower limit described above can be combined arbitrarily.

[0180] If the total thickness of the polarizing plate is 500 μm or less, the thinning of the polarizing plate 1 can be contributed. If the total thickness of the polarizing plate 1 is 30 μm or more, the strength of the polarizing plate 1 is improved.

[0181] In the present specification, the "total thickness of the polarizing plate" means the dimension in the stacking direction of the polarizing plate. The total thickness of the polarizing plate can be obtained, for example, by measuring the thickness of the polarizing plate at any five points using a micrometer and calculating the average value thereof.

[0182] Note that the "total thickness of the polarizing plate" is the total value of the thickness of the film finally mounted on the image display device. That is, the "total thickness of the polarizing plate" does not include the thickness of the film which is not finally mounted on the image display device. As the film which is not finally mounted on the image display device, a release film, a surface protective film can be given.

[0183] The total thickness of the polarizing plate 1 can also be obtained by measuring the thickness of the protective layer 11, the polarizing plate layer 12, the resin layer 13, the first adhesive layer 14, the phase difference layer 16, the second adhesive layer 15, and all the optical film layers, adhesive layers, and adhesive agent layers other than those included in the polarizing plate and finally mounted on the image display device, respectively, and adding the values thereof.

[0184] The thickness of the protective layer 11, the polarizing plate layer 12, the resin layer 13, the first adhesive layer 14, the phase difference layer 16, the second adhesive layer 15, and all the optical film layers, adhesive layers, and adhesive agent layers other than those included in the polarizing plate can be measured by the method described in the present specification.

[0185] In the present specification, the degree of polarization of the polarizing plate is evaluated using two parameters called "visibility-corrected monomer transmittance (Ty)" and "visibility-corrected degree of polarization (Py)". Ty and Py are the transmittance and the degree of polarization at the visible region (wavelength of 380 to 780 nm) which are corrected in such a manner that the weighting of the vicinity of 550 nm at which the sensitivity of the human eye is the highest is maximized, respectively. Light having a wavelength of less than 380 nm is generally not visually recognized by the human eye, and thus is not taken into account in Ty and Py.

[0186] Ty of the polarizing plate 1 is a value obtained in an image display device such as an organic EL display device to which the polarizing plate 1 is applied. Ty of the polarizing plate 1 is preferably 40% or more and 47% or less, and more preferably 41% or more and 45% or less. By being in the above range, the balance between Ty and Py becomes more favorable. If Ty of the polarizing plate 1 is 40% or more, the luminance of the image display device becomes sufficiently high. If Ty of the polarizing plate 1 is 47% or less, Py becomes sufficiently high, and the contrast becomes favorable. On the other hand, in the case where Ty of the polarizing plate 1 is less than 40%, it is appropriate to increase the input power of the image display device in order to make the luminance of the image display device sufficiently high.

[0187] Py of the polarizing plate 1 is preferably 99.9% or more, and more preferably 99.95% or more, and can be 99.99% or more.

[0188] When a damp heat test in which the polarizing plate 1 is left in an environment at a temperature of 80°C and a relative humidity of 90% for 24 hours is performed, the absolute value of the difference between Py before and after the test (hereinafter also referred to as ΔPy) of the polarizing plate 1 is 0% or more and 13% or less. In addition, the difference between Ty before and after the test (hereinafter also referred to as ΔTy) of the polarizing plate 1 is 0% or more and 5% or less. If ΔPy and ΔTy are in the above ranges, it can be said that the polarizing plate 1 can maintain a high degree of polarization even in a damp heat environment.

[0189] From the viewpoint of damp heat resistance, ΔPy of the polarizing plate 1 is preferably 10% or less, more preferably 8% or less, and further preferably 5% or less.

[0190] In addition, from the viewpoint of damp heat resistance, ΔTy of the polarizing plate 1 is preferably 4% or less, and more preferably 3% or less.

[0191] In the present specification, Ty of the polarizing plate 1 is measured using a spectrophotometer with an integrating sphere ("V7100" manufactured by Japan Spectroscopic Co., Ltd.). MD transmittance and TD transmittance are obtained in the range of wavelengths of 380 nm to 780 nm, and the monomer transmittance at each wavelength is calculated based on Equation (1).

[0192] Next, the visibility correction monomer transmittance is obtained by performing visibility correction using a 2-degree field of view (C light source) of JIS Z 8701. Here, the "MD transmittance" indicates the transmittance when the direction of polarized light emitted from a Glan-Thompson prism is parallel to the transmission axis of the polarizing plate sample. In addition, the "TD transmittance" indicates the transmittance when the direction of polarized light emitted from a Glan-Thompson prism is orthogonal to the transmission axis of the polarizing plate sample.

[0193]

[0194] In the present specification, with respect to the Py of the polarizing plate 1, the degree of polarization at each wavelength is calculated based on Equation (2) from the above-mentioned MD transmittance and TD transmittance. Further, the visibility correction degree of polarization is obtained by performing visibility correction using a 2-degree field of view (C light source) of JIS Z 8701.

[0195]

[0196] [Manufacturing method of polarizing plate]

[0197] Hereinafter, the manufacturing method of the polarizing plate 1 of the first embodiment will be described based on Figure 2 The manufacturing method of the polarizing plate of the first embodiment will be described.

[0198] The polarizing plate 1 of the present embodiment can be manufactured by sequentially laminating each layer constituting the polarizing plate 1, or can be manufactured by pre-laminating each layer adjacent to each other, and then laminating the laminates to each other. In addition, each layer constituting the polarizing plate 1 can be manufactured using a publicly known method, or a commercially available material can be used.

[0199] Figure 2 is a schematic view showing an example of the manufacturing method of the polarizing plate of the first embodiment. As shown in Figure 2 First, the laminate A including the polarizing plate layer 12, the laminate B including the phase difference layer 16, the first adhesive 140 forming the first adhesive layer 14, and the second adhesive 150 forming the second adhesive layer 15 are prepared.

[0200] The laminate A is a laminate in which the protective layer 11, the polarizing plate layer 12, and the resin layer 13 are sequentially laminated.

[0201] The laminate B is a laminate in which the phase difference layer 16 and the orientation layer 19 are laminated.

[0202] The manufacturing method of the laminate A and the laminate B is not particularly limited.

[0203] Next, the resin layer 13 of the laminate A and the phase difference layer 16 of the laminate B are opposed to each other, and the first adhesive 140 is disposed between the laminate A and the laminate B, to obtain a composite laminate.

[0204] Next, the composite laminate is pressed from both sides of the laminate A or the laminate B to bond the laminate A and the laminate B. This yields a composite laminate in which the laminate A, the first adhesive layer 14, and the laminate B are laminated in this order.

[0205] Next, the second adhesive 150 is laminated on the other surface 19b of the orientation layer 19 of the obtained composite laminate. In this way, the polarizing plate 1 is obtained.

[0206] In addition, the lamination order of each layer constituting the polarizing plate 1 is not limited to this.

[0207] It is believed that the polarizing plate 1 of this embodiment includes the resin layer 13, thereby suppressing the transfer of components contained in the retardation layer 16 to the polarizer layer 12. This is believed to be mainly because the components contained in the retardation layer 16 are not easily transferred to the polarizer layer 12 and are retained in the resin layer 13. Therefore, the polarizing plate 1 of this embodiment can maintain a high degree of polarization even in a hot and humid environment.

[0208] [Organic EL display device]

[0209] Below, refer to Figure 3 An organic EL display device including the polarizing plate according to the first embodiment will be described.

[0210] Figure 3 1 is a schematic cross-sectional view showing an example of the structure of the organic EL display device according to the first embodiment. Figure 3 As shown, the organic EL display device 100 includes a display panel 10 and a polarizing plate 1 .

[0211] Polarizing plate 1 is disposed on the viewing side of display panel 10. Polarizing plate 1 is bonded to display panel 10 by second adhesive layer 15 of polarizing plate 1. One surface 11a of protective layer 11 of polarizing plate 1 is the viewing side of organic EL display device 100.

[0212] The display panel 10 includes an organic electroluminescent display element (hereinafter also referred to as an organic EL element). That is, the polarizing plate 1 is disposed on the viewing side of the organic EL element.

[0213] Figure 4 Schematic cross-sectional view showing an example of the layer structure of an organic EL element. Figure 4 As shown, the organic EL element 200 includes a substrate 201, an anode 202, an organic EL layer 203, a cathode 204, and a sealing layer 205 covering them. Furthermore, the organic EL element 200 may include, as necessary, a planarization layer (not shown) on the substrate 201, or an insulating layer (not shown) between the anode 202 and the cathode 204 to prevent short circuits.

[0214] Each layer constituting the organic EL element can use a publicly known material.

[0215] The organic EL element 200 can be continuously manufactured by a publicly known roll-to-roll process. Further, by continuously laminating the organic EL element 200 and the long polarizing plate 1 with the roll-to-roll process, the organic EL display device 100 can be continuously manufactured.

[0216] According to the organic EL display device 100 configured as above, high display quality can be maintained even in a humid heat environment.

[0217] <Second Embodiment>

[0218] [Polarizing plate]

[0219] Hereinafter, the polarizing plate of the second embodiment will be described with reference to Figure 5 The polarizing plate of the second embodiment is partly common to the polarizing plate of the first embodiment. Therefore, the same reference numerals are given to the constituent elements common to the first embodiment in the present embodiment, and detailed description will be omitted.

[0220] Figure 5 is a cross-sectional schematic view showing an example of the layer constitution of the polarizing plate of the second embodiment. As shown in Figure 5 The polarizing plate 2 of the present embodiment includes a protective layer 11, a polarizing sheet layer 12, a resin layer 13, a first adhesive layer 14, a second adhesive layer 15, a first phase difference layer 17, a second phase difference layer 18, a first orientation layer 20, a second orientation layer 21, and an adhesive layer 22.

[0221] In the polarizing plate 2 of the present embodiment, the first phase difference layer 17 and the second phase difference layer 18 are provided as phase difference layers. The first phase difference layer 17 and the second phase difference layer 18 are disposed on the other face 12b side of the polarizing sheet layer 12. The resin layer 13 is disposed between the polarizing sheet layer 12 and the first phase difference layer 17. The second phase difference layer 18 is disposed on the resin layer 13 side with the polarizing sheet layer 12 as a reference. The second phase difference layer 18 is disposed between the resin layer 13 and the first phase difference layer 17.

[0222] The first phase difference layer 17 and the second phase difference layer 18 are adhered via the adhesive layer 22.

[0223] The second orientation layer 21 contacts a face (the other face) 17b of the first phase difference layer 17 on the side opposite to the adhesive layer 22.

[0224] The first orientation layer 20 contacts a face (one face) 18a of the second phase difference layer 18 on the side opposite to the adhesive layer 22. The first orientation layer 20 is adhered to the resin layer 13 via the first adhesive layer 14. The first adhesive layer 14 is provided on the other face 13b of the resin layer 13.

[0225] The second adhesive layer 15 contacts a surface (the other surface) 21b of the second alignment layer 21 on the side opposite the first retardation layer 17 side.

[0226] Hereinafter, each layer constituting the polarizing plate 2 of the second embodiment will be described in detail.

[0227] (First Retardation Layer, Second Retardation Layer)

[0228] The first retardation layer 17 and the second retardation layer 18 can each independently be, for example, a layer imparting a phase difference of 1 / 2 wavelength, a layer imparting a phase difference of 1 / 4 wavelength, or the like, a positive A layer, a negative A layer, a positive C layer, or a negative C layer. The first retardation layer 17 and the second retardation layer 18 can be the same material or different materials.

[0229] In the present specification, the "layer imparting a phase difference of 1 / 2 wavelength" refers to a phase difference layer that converts the polarization azimuth of linearly polarized light of a certain specific wavelength by 90°.

[0230] As one side of the present embodiment, it is preferable that either of the first retardation layer 17 and the second retardation layer 18 be a layer imparting a phase difference of 1 / 4 wavelength and the other be a layer imparting a phase difference of 1 / 2 wavelength. In addition, it is preferable that either of the first retardation layer 17 and the second retardation layer 18 be a layer imparting a phase difference of 1 / 4 wavelength and the other be a positive C layer.

[0231] Therefore, the thicknesses of the first retardation layer 17 and the second retardation layer 18, and the materials constituting them are suitably adjusted in a manner to obtain a desired in-plane phase difference value, a thickness direction phase difference value.

[0232] In the case where the first retardation layer 17 is a layer imparting a phase difference of 1 / 4 wavelength and the second retardation layer 18 is a layer imparting a phase difference of 1 / 2 wavelength, it is preferable that the thickness of the first retardation layer 17 be, for example, 1 μm or more and 10 μm or less, and the thickness of the second retardation layer 18 be, for example, 1 μm or more and 10 μm or less.

[0233] In the case where the first retardation layer 17 is a positive C layer and the second retardation layer 18 is a layer imparting a phase difference of 1 / 4 wavelength, the thickness of the first retardation layer 17 is, for example, 1 μm or more and 10 μm or less, and the thickness of the second retardation layer 18 is, for example, 1 μm or more and 10 μm or less.

[0234] Note that the thickness of the first retardation layer 17 and the thickness of the second retardation layer 18 can be obtained using the measurement method of the thickness of the layer described in the first embodiment.

[0235] The first phase difference layer 17 uses a cured product of a first liquid crystal composition as a forming material. The second phase difference layer 18 uses a cured product of a second liquid crystal composition as a forming material. The first liquid crystal composition and the second liquid crystal composition can use the same materials as those exemplified in the phase difference layer 16 of the first embodiment. The first liquid crystal composition and the second liquid crystal composition can be the same or different.

[0236] When a polarizing plate having a polarizing plate layer such as the polarizing plate layer 12 and phase difference layers such as the first phase difference layer 17 and the second phase difference layer 18 is left in a humid heat environment (for example, an environment of 80°C in temperature and 90% in relative humidity), the degree of polarization can sometimes decrease.

[0237] It is considered that, also in the polarizing plate 2 of the present embodiment, by providing the resin layer 13 between the polarizing plate layer 12 and the first phase difference layer 17 and the second phase difference layer 18, it is possible to suppress the transfer of the components contained in the two phase difference layers to the polarizing plate layer 12. As a result, the present inventors have found that by providing the resin layer 13 between the polarizing plate layer 12 and the first phase difference layer 17 and the second phase difference layer 18, it is possible to maintain a high degree of polarization even in a humid heat environment, and thus completed the present application.

[0238] (First alignment layer, second alignment layer)

[0239] The first alignment layer 20 and the second alignment layer 21 can use the same materials as those exemplified in the alignment layer 19 of the first embodiment. The first alignment layer 20 and the second alignment layer 21 can be the same or different.

[0240] (Bonding layer)

[0241] In the present specification, the "bonding layer" refers to an adhesive layer or a cohesive layer. As the cohesive layer, the above-described materials can be appropriately used. Hereinafter, a case where the bonding layer 22 is an adhesive layer will be described. An "adhesive" is a substance that can be applied to a substrate in a liquid state at the time of application to the substrate, and exhibits adhesiveness by being cured (i.e., does not exhibit adhesiveness until cured).

[0242] As the adhesive that bonds the first phase difference layer 17 and the second phase difference layer 18, for example, a water-based adhesive or a radiation-curable adhesive can be exemplified.

[0243] As the water-based adhesive, for example, an adhesive in which a PVA-based resin is dissolved or dispersed in water can be exemplified.

[0244] As the radiation-curable adhesive, for example, an adhesive containing a curable compound that is cured by irradiation of active energy rays such as ultraviolet rays, visible light, electron rays, X-rays can be exemplified.

[0245] As the active energy ray-curable adhesive, either or both of a cationically polymerizable curable compound and a radically polymerizable curable compound are preferably contained from the viewpoint of exhibiting good adhesion. The active energy ray-curable adhesive can further contain either or both of a cationic polymerization initiator and a radical polymerization initiator for initiating the curing reaction of the above-mentioned curable compound.

[0246] The cationically polymerizable curable compound and the radically polymerizable curable compound can use a publicly known material.

[0247] The active energy ray-curable adhesive can contain, as needed, a cationic polymerization promoter, an ion trap agent, an antioxidant, a chain transfer agent, an adhesion promoter, a thermoplastic resin, a filler, a flow adjusting agent, a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent, a solvent, and the like.

[0248] The thickness of the adhesive layer 22 is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.05 μm or more and 5 μm or less. If the thickness of the adhesive layer 22 is 0.01 μm or more, the polarizing plate 2 has sufficient strength, and thus is less likely to be broken. If the thickness of the adhesive layer 22 is 10 μm or less, floating or peeling is less likely to occur between the first phase difference layer 17 and the second phase difference layer 18. In addition, appearance defects of the polarizing plate 2 caused by curing shrinkage of the adhesive are less likely to occur.

[0249] [Manufacturing method of polarizing plate]

[0250] Hereinafter, based on Figure 6 The manufacturing method of the polarizing plate of the second embodiment will be described.

[0251] The polarizing plate 2 of the present embodiment can be manufactured by sequentially stacking each layer constituting the polarizing plate 2, or can be manufactured by pre-stacking each layer adjacent to each other, and then stacking the stack with each other. In addition, each layer constituting the polarizing plate 2 can be manufactured using a publicly known method, or a commercially available material can be used.

[0252] Figure 6 is a schematic view showing an example of the manufacturing method of the polarizing plate of the second embodiment. As Figure 6 shown, first, a stack A including the polarizing plate layer 12, a stack C including the first phase difference layer 17 and the second phase difference layer 18, a first adhesive 140 forming the first adhesive layer 14, and a second adhesive 150 forming the second adhesive layer 15 are prepared.

[0253] The stack A is the same as the stack used in the manufacturing method of the polarizing plate of the first embodiment.

[0254] The laminate C is a laminate in which the first orientation layer 20, the second retardation layer 18, the adhesive layer 22, the first retardation layer 17, and the second orientation layer 21 are sequentially stacked. The laminate C is obtained by joining the laminate of the first orientation layer 20 and the second retardation layer 18 to the laminate of the first retardation layer 17 and the second orientation layer 21 in a state in which the first retardation layer 17 and the second retardation layer 18 face each other, using the adhesive layer 22.

[0255] Next, the resin layer 13 of the laminate A is made to face the first orientation layer 20 of the laminate C, and the first adhesive 140 is disposed between the laminate A and the laminate C, to obtain a composite laminate.

[0256] Next, the composite laminate is pressed from both sides of the laminate A or the laminate C, to join the laminate A and the laminate C. Thus, a composite laminate in which the laminate A, the first adhesive layer 14, and the laminate C are sequentially stacked is obtained.

[0257] Next, the second adhesive 150 is stacked on the other face 21b of the second orientation layer 21 of the obtained composite laminate. Thus, the polarizing plate 2 is obtained.

[0258] Note that the order of stacking of the layers constituting the polarizing plate 2 is not limited to this.

[0259] It is considered that, since the polarizing plate 2 of the present embodiment has the above-described resin layer 13, the components contained in the first retardation layer 17 and the second retardation layer 18 can be inhibited from being transferred to the polarizing sheet layer 12. It is considered that the main reason for this is that the components contained in the first retardation layer 17 and the second retardation layer 18 are less likely to be transferred to the polarizing sheet layer 12, but are blocked in the resin layer 13. Thus, the polarizing plate 2 of the present embodiment can maintain a high degree of polarization even in a humid heat environment.

[0260] [Third Embodiment]

[0261] [Polarizing Plate]

[0262] Hereinafter, the polarizing plate of the third embodiment will be described with reference to Figure 7 The polarizing plate of the third embodiment will be described. The polarizing plate of the third embodiment is partly common to the polarizing plate of the second embodiment. Thus, the same reference numerals are assigned to the constituent elements common to the second embodiment in the present embodiment, and detailed description will be omitted.

[0263] Figure 7 is a cross-sectional schematic view showing an example of the layer constitution of the polarizing plate of the third embodiment. As shown in Figure 7 The polarizing plate 3 of the present embodiment includes a protective layer 11, a polarizing sheet layer 12, a resin layer 13, a second adhesive layer 15, a first retardation layer 17, a second retardation layer 18, a first orientation layer 20, a second orientation layer 21, an adhesive layer 22, and a third adhesive layer 23.

[0264] Different from the polarizing plate 2 of the second embodiment, the first alignment layer 20 is formed directly on the other surface 13b of the resin layer 13. The polarizer layer 12 and the resin layer 13 are bonded together via a third adhesive layer 23.

[0265] As the adhesive constituting the third adhesive layer 23 , the same materials as those exemplified as the adhesive constituting the first adhesive layer 14 in the first embodiment can be used.

[0266] The thickness of the second adhesive layer 15 and the thickness of the third adhesive layer 23 may be the same or different.

[0267] [Method for Manufacturing Polarizing Plate]

[0268] The following is based on Figure 8 A method for manufacturing a polarizing plate according to the third embodiment will be described.

[0269] The polarizing plate 3 of this embodiment can be manufactured by sequentially stacking the layers constituting the polarizing plate 3, or by pre-stacking adjacent layers and then stacking the laminates. In addition, the layers constituting the polarizing plate 3 can be manufactured using a known method or commercially available materials.

[0270] Figure 8 Schematic diagram showing an example of a method for manufacturing a polarizing plate according to the third embodiment. Figure 8 As shown, first, a stack D including a polarizer layer 12, a stack E including a resin layer 13, a first phase difference layer 17 and a second phase difference layer 18, a third adhesive 230 forming a third adhesive layer 23, and a second adhesive 150 forming a second adhesive layer 15 are prepared.

[0271] The laminate D is a laminate in which a protective layer 11 and a polarizer layer 12 are laminated.

[0272] The laminate E is a laminate in which the resin layer 13 , the first orientation layer 20 , the second retardation layer 18 , the adhesive layer 22 , the first retardation layer 17 , and the second orientation layer 21 are laminated in this order.

[0273] The laminate E is obtained by bonding a laminate of the resin layer 13 , the first orientation layer 20 , and the second retardation layer 18 to a laminate of the first retardation layer 17 and the second orientation layer 21 using an adhesive layer 22 so that the first retardation layer 17 and the second retardation layer 18 face each other.

[0274] Next, the manufacturing method of the laminate of the resin layer 13, the first alignment layer 20, and the second phase difference layer 18 will be described. First, the resin layer 13 is formed. Next, the first alignment layer 20 is formed directly on the surface of the resin layer 13. Next, the second phase difference layer 18 is formed on the surface of the first alignment layer 20. In this way, the laminate of the resin layer 13, the first alignment layer 20, and the second phase difference layer 18 is obtained.

[0275] Next, the polarizing plate layer 12 of the laminate D is opposed to the resin layer 13 of the laminate E, and the third adhesive 230 is disposed between the laminate D and the laminate E, to obtain a composite laminate.

[0276] Next, the composite laminate is pressed from both sides of the laminate D or the laminate E, to adhere the laminate D and the laminate E. In this way, the composite laminate in which the laminate D, the third adhesive layer 23, and the laminate E are sequentially laminated is obtained.

[0277] Next, the second adhesive 150 is laminated on the other surface 21b of the second alignment layer 21 of the obtained composite laminate. In this way, the polarizing plate 3 is obtained.

[0278] It is to be noted that the lamination order of each layer constituting the polarizing plate 3 is not limited to this.

[0279] It is considered that, since the polarizing plate 3 of the present embodiment has the above-described resin layer 13, the components contained in the first phase difference layer 17 and the second phase difference layer 18 can be inhibited from being transferred into the polarizing plate layer 12. It is considered that the main reason is that the components contained in the first phase difference layer 17 and the second phase difference layer 18 are not easily transferred into the polarizing plate layer 12 but are blocked in the resin layer 13. Therefore, the polarizing plate 3 of the present embodiment can maintain a high degree of polarization even in a humid heat environment.

[0280] [Fourth Embodiment] [Fourth Embodiment]

[0281] [Polarizing Plate] [Fourth Embodiment]

[0282] Hereinafter, the polarizing plate of the fourth embodiment will be described with reference to Figure 9 The polarizing plate of the fourth embodiment will be described. The polarizing plate of the fourth embodiment is partly common to the polarizing plate of the third embodiment. Therefore, the same reference numerals are assigned to the constituent elements common to the third embodiment in the present embodiment, and detailed description will be omitted. [Fourth Embodiment]

[0283] [Fourth Embodiment] Figure 9 is a cross-sectional schematic view showing an example of the layer constitution of the polarizing plate of the fourth embodiment. As shown in Figure 9 The polarizing plate 4 of the present embodiment includes a protective layer 11, a polarizing plate layer 12, a resin layer 13, a second adhesive layer 15, a first phase difference layer 17, a second phase difference layer 18, a first alignment layer 20, a second alignment layer 21, an adhesive layer 22, a fourth adhesive layer 24, and a fifth adhesive layer 25.

[0284] Unlike the polarizing plate 3 of the third embodiment, the resin layer 13 is disposed between the first phase difference layer 17 and the second phase difference layer 18. That is, the first phase difference layer 17 is disposed on the side opposite to the polarizing plate layer 12 with the resin layer 13 as a reference. On the other hand, the second phase difference layer 18 is disposed between the resin layer 13 and the polarizing plate layer 12.

[0285] The reason is not clear, but it is clear that the positive C layer has a significantly greater effect of reducing the degree of polarization in a humid heat environment than a layer that imparts a phase difference of 1 / 4 wavelength or the like. Therefore, in the case where the resin layer 13 is taken as a reference and at least the first phase difference layer 17 is present on the side opposite to the polarizing plate layer 12 as in the present embodiment, it is preferable that the first phase difference layer 17 be a positive C layer and the second phase difference layer 18 be a layer that imparts a phase difference of 1 / 4 wavelength. In this case, the effect of the present application that the high degree of polarization is maintained even in a humid heat environment is easily obtained.

[0286] As the adhesive that constitutes the fourth adhesive layer 24 and the fifth adhesive layer 25, the same materials as those exemplified as the adhesive that constitutes the first adhesive layer 14 of the first embodiment can be used.

[0287] The thickness of the fourth adhesive layer 24 and the thickness of the fifth adhesive layer 25 can be the same or different.

[0288] [Manufacturing method of polarizing plate]

[0289] Hereinafter, the manufacturing method of the polarizing plate of the fourth embodiment will be described based on the above-described manufacturing method of the polarizing plate of the first embodiment. Figure 10 The manufacturing method of the polarizing plate of the fourth embodiment will be described.

[0290] The polarizing plate 4 of the present embodiment can be manufactured by sequentially stacking each layer that constitutes the polarizing plate 4, or can be manufactured by pre-stacking each layer that is adjacent to each other, and then stacking the stacks with each other. In addition, each layer that constitutes the polarizing plate 4 can be manufactured by a publicly known method, or a commercially available material can be used.

[0291] Figure 10 is a schematic view showing an example of the manufacturing method of the polarizing plate of the fourth embodiment. As shown in Figure 10 First, a stack F including the polarizing plate layer 12, the resin layer 13, and the second phase difference layer 18, a stack G including the first phase difference layer 17, a fifth adhesive 250 that forms the fifth adhesive layer 25, and a second adhesive 150 that forms the second adhesive layer 15 are prepared.

[0292] The stack F is a stack in which the protective layer 11, the polarizing plate layer 12, the fourth adhesive layer 24, the second phase difference layer 18, the first orientation layer 20, and the resin layer 13 are sequentially stacked.

[0293] The laminate G is a laminate of the first phase difference layer 17 and the second alignment layer 21.

[0294] The method of manufacturing the laminate F and the laminate G is not particularly limited.

[0295] Next, the resin layer 13 of the laminate F and the first phase difference layer 17 of the laminate G are opposed to each other, and the fifth adhesive 250 is disposed between the laminate F and the laminate G, to obtain a composite laminate.

[0296] Next, the composite laminate is pressed from both sides of the laminate F or the laminate G, to adhere the laminate F and the laminate G. Thus, a composite laminate in which the laminate F, the fifth adhesive layer 25, and the laminate G are sequentially laminated is obtained.

[0297] Next, the second adhesive 150 is laminated on the other face 21b of the second alignment layer 21 of the obtained composite laminate. Thus, the polarizing plate 4 is obtained.

[0298] It is to be noted that the lamination order of each layer constituting the polarizing plate 4 is not limited to this.

[0299] It is considered that, since the polarizing plate 4 of the present embodiment is provided with the above-described resin layer 13, the components contained in the first phase difference layer 17 can be inhibited from being transferred into the polarizing sheet layer 12. It is considered that the main reason is that the components contained in the first phase difference layer 17 are not easily transferred into the polarizing sheet layer 12, but are blocked in the resin layer 13. Thus, the polarizing plate 4 of the present embodiment can maintain a high degree of polarization even in a humid heat environment.

[0300] [Fourth Embodiment] [Fourth Embodiment]

[0301] [Polarizing Plate] [Fourth Embodiment]

[0302] Hereinafter, the configuration of the polarizing plate of the fourth embodiment will be described with reference to Figure 11 The polarizing plate of the fourth embodiment will be described. The polarizing plate of the fourth embodiment is partly common to the polarizing plate of the third embodiment. Thus, the same reference numerals are assigned to the constituent elements common to the third embodiment in the present embodiment, and detailed description will be omitted. [Fourth Embodiment]

[0303] [Fourth Embodiment] Figure 11 is a cross-sectional schematic view showing an example of the layer configuration of the polarizing plate of the fourth embodiment. As shown in Figure 11 The polarizing plate 4 of the present embodiment includes the protective layer 11, the polarizing sheet layer 12, the resin layer 13, the second adhesive layer 15, the first phase difference layer 17, the second phase difference layer 18, the first alignment layer 20, the second alignment layer 21, the adhesive layer 22, and the fourth adhesive layer 24. [Fourth Embodiment]

[0304] In contrast to the polarizing plate of the fourth embodiment, the first phase difference layer 17 and the second phase difference layer 18 are brought into contact with each other via the resin layer 13. That is, the resin layer 13 not only functions to suppress the transfer of the components contained in the first phase difference layer 17 into the polarizing plate layer 12, but also functions to join the first phase difference layer 17 and the second phase difference layer 18.

[0305] The reason is not clear, but it is clear that the positive C layer has a significantly greater effect of reducing the degree of polarization in a humid heat environment than a layer that imparts a phase difference of 1 / 4 wavelength or the like. Therefore, in the case where the resin layer 13 is used as a reference to provide at least the first phase difference layer 17 on the side opposite to the polarizing plate layer 12 as in the present embodiment, it is preferable that the first phase difference layer 17 be a positive C layer and the second phase difference layer 18 be a layer that imparts a phase difference of 1 / 4 wavelength. In this case, the effect of the present application that a high degree of polarization is maintained even in a humid heat environment is easily obtained.

[0306] [Method for manufacturing polarizing plate]

[0307] Hereinafter, the method for manufacturing the polarizing plate 5 of the fifth embodiment will be described based on the flowchart shown in FIG. 9. Figure 12 The method for manufacturing the polarizing plate 5 of the fifth embodiment will be described.

[0308] The polarizing plate 5 of the present embodiment can be manufactured by sequentially stacking each layer constituting the polarizing plate 5, or can be manufactured by pre-stacking each layer adjacent to each other, and stacking the stacks with each other. In addition, each layer constituting the polarizing plate 5 can be manufactured using a publicly known method, or a commercially available material can be used.

[0309] Figure 12 is a schematic view showing an example of the method for manufacturing the polarizing plate of the fifth embodiment. As shown in Figure 12 First, the stack H including the polarizing plate layer 12 and the second phase difference layer 18, the stack I including the resin composition 130 forming the resin layer 13 and the first phase difference layer 17, and the second adhesive 150 forming the second adhesive layer 15 are prepared.

[0310] The stack H is a stack in which the protective layer 11, the polarizing plate layer 12, the fourth adhesive layer 24, the first orientation layer 20, and the second phase difference layer 18 are sequentially stacked.

[0311] The stack I is a stack in which the resin composition 130, the first phase difference layer 17, and the second orientation layer 21 are sequentially stacked.

[0312] The method for manufacturing the stack H and the stack I is not particularly limited.

[0313] Next, the second phase difference layer 18 of the laminate H was bonded to the resin composition 130 of the laminate I, and a composite laminate was obtained. Thus, a composite laminate in which the laminate H and the laminate I were laminated was obtained. By curing the resin composition 130 of the composite laminate, the resin layer 13 was formed between the first phase difference layer 17 and the second phase difference layer 18.

[0314] Next, the second adhesive 150 was laminated on the other face 21b of the second alignment layer 21 of the obtained composite laminate. Thus, the polarizing plate 5 was obtained.

[0315] Note that the lamination order of each layer constituting the polarizing plate 5 is not limited to this.

[0316] It is considered that, since the polarizing plate 5 of the present embodiment is provided with the above-described resin layer 13, the components contained in the first phase difference layer 17 can be inhibited from being transferred into the polarizing sheet layer 12. It is considered that the main reason for this is that the components contained in the first phase difference layer 17 are less likely to be transferred into the polarizing sheet layer 12, but are blocked in the resin layer 13. Thus, the polarizing plate 5 of the present embodiment can maintain a high degree of polarization even in a humid heat environment.

[0317] The above describes examples of suitable embodiments according to the present application with reference to the drawings, but needless to say, the present application is not limited to these examples. The shapes and combinations of each of the constituent members shown in the above examples are one example, and various changes can be made based on design requirements and the like without departing from the gist of the present application.

[0318] Example

[0319] Hereinafter, the present application will be described using examples, but the present application is not limited to these examples. Note that, in the present example, as the phase difference layer, a positive C layer having a greater effect of reducing the degree of polarization in a humid heat environment than a layer imparting a phase difference of ¼ wavelength was used. The Martens hardness of the resin layer, and Ty and Py of the polarizing plate in the present example were obtained using the following methods.

[0320] [Resin Layer Martens Hardness]

[0321] The resin layer was subjected to an indentation test in accordance with ISO 14577, and the Martens hardness of the resin layer was measured. Specifically, as a film hardness tester, a nanoindentation tester (ENT-2100) manufactured by Elionix Corporation was used. A sample formed of the resin layer was set in the above tester, and a Berkovich indenter was brought into contact with and indented into the side surface of the sample, whereby the Martens hardness was measured. The initial load was set to 0 mN, and the maximum load was set to 0.5 mN. The maximum load holding was set to 1000 m seconds. The temperature of the environment in which the Martens hardness was measured was 23°C.

[0322] [Resin Layer Breaking Load]

[0323] The breaking load of the resin layer was measured in the following manner. A light compression tester (KES-G5) manufactured by KATO TECH Co., Ltd. was used in the measurement. The test piece (resin layer) was held by a jig having a through hole (1 1 mm in diameter) in the center, which was provided in the tester. Here, the size of the test piece used was such that it covered the through hole, and the thickness of the test piece was the thickness of the resin layer. Next, a presser was pressed into the test piece. The load at which the test piece was broken by the presser or the presser penetrated the test piece was measured as the breaking load (unit: g). A presser having a spherical tip with a diameter of 1 mm was used. The speed at which the presser was pressed was set to 0.33 cm / sec. The temperature of the environment in which the breaking load was measured was 23°C. The sensitivity was set to 10, and the voltage was set to 5 mm / 10 V.

[0324] [Ty, Py of polarizing plate]

[0325] Ty of the polarizing plate was measured using a spectrophotometer with an integrating sphere ("V7100" manufactured by Japan Spectroscopic Co., Ltd.). MD transmittance and TD transmittance were obtained in the range of wavelengths from 380 nm to 780 nm, and the monomer transmittance at each wavelength was calculated based on Equation (1). Next, the visibility correction was performed using the 2-degree field of view (C light source) of JIS Z 8701, and the visibility-corrected monomer transmittance was obtained.

[0326]

[0327] As for Py of the polarizing plate, the degree of polarization at each wavelength was calculated based on Equation (2) from the above-mentioned MD transmittance and TD transmittance. Further, the visibility correction was performed using the 2-degree field of view (C light source) of JIS Z 8701, and the visibility-corrected degree of polarization was obtained.

[0328]

[0329] [Examples 1 to 4, Comparative Example 1]

[0330] [Manufacture of polarizing film]

[0331] A PVA film (average degree of polymerization: about 2400, saponification degree: 99.9 mol% or more) having a thickness of 20 μm was uniaxially stretched to about 6 times by dry stretching, and then immersed in pure water at 40°C for 40 seconds while being kept in tension.

[0332] Next, the film was immersed in a dyeing aqueous solution of iodine / potassium iodide / water having a mass ratio of 0.044 / 5.7 / 100 at 28°C for 30 seconds, whereby dyeing treatment was performed.

[0333] Next, the dyeing-treated film was immersed in a 70°C aqueous boric acid solution having a mass ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 for 120 seconds, whereby a cross-linking treatment was performed.

[0334] Next, the cross-linking-treated film was washed with pure water at 8°C for 15 seconds, and then dried at 60°C for 50 seconds while being maintained under a tension of 300 N / m, and then dried at 75°C for 20 seconds. In this way, a polarizing film having a thickness of 7 μm in which iodine was oriented and adsorbed on the PVA film was obtained.

[0335] [Manufacture of the laminate (1)]

[0336] As the protective film, a cycloolefin resin film (COP, ZF-14 UV-absorption-free, thickness 13 μm, manufactured by ZEON Corporation) was prepared. The obtained polarizing film and the cycloolefin resin film were bonded to each other by injecting a water-based adhesive therebetween, and then laminated by using a nip roll. The obtained laminate was dried at 60°C for 2 minutes while being maintained under a tension of 430 N / m, and a laminate (1) having a polarizing plate layer and a protective layer disposed on one face of the polarizing plate layer was obtained. The thickness of the laminate A was 20 μm.

[0337] Note that the above water-based adhesive was prepared by adding 3 parts by mass of carboxyl-modified polyvinyl alcohol (Kuraray Poval (registered trademark) KL318, manufactured by Kuraray Co., Ltd.) and 1.5 parts by mass of a water-soluble polyamide epoxy resin (Sumirez Resin (registered trademark) 650, manufactured by NOK Corporation; solid content concentration 30% aqueous solution) to 100 parts by mass of water.

[0338] [Manufacture of the laminate (2)]

[0339] As the transparent substrate, a substrate formed of a polyethylene terephthalate film having a thickness of 38 μm was prepared. An alignment layer for vertical alignment was applied to one face of the transparent substrate in such a manner that the film thickness became 3 μm, and ultraviolet rays were irradiated in such a manner that the cumulative light amount became 20 mJ / cm 2

[0340] Note that the above alignment layer for vertical alignment was prepared by mixing 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis(2-vinyloxyethyl) ether in a ratio of 1:1:4:5, and adding LUCIRIN (registered trademark) TPO as a polymerization initiator in a ratio of 4% with respect to the total mass of the obtained mixture.

[0341] A liquid crystal composition containing a polymerizable nematic liquid crystal compound (RMM28B, manufactured by Merck Co., Ltd.) was applied to the alignment layer by die coating.​

[0342] In the preparation of the liquid crystal composition, a mixed solvent in which methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CHN) having a boiling point of 155°C were mixed at a mass ratio (MEK:MIBK:CHN) of 35:30:35 was used as a solvent. Then, the liquid crystal composition prepared so that the solid content per 100 g of the liquid crystal composition was 1 to 1.5 g was applied to the alignment layer so that the application amount before drying was 4 to 5 g.

[0343] After the liquid crystal composition was applied to the alignment layer, the resulting applied layer was subjected to a drying treatment with a drying temperature of 75°C and a drying time of 120 seconds. Thereafter, the liquid crystal compound was polymerized and cured by irradiation with ultraviolet rays (UV). In this way, a laminate (2) composed of a phase difference layer, an alignment layer, and a transparent substrate was obtained. The phase difference layer was a positive C layer satisfying the relationship of n z >n x =n y The total thickness of the phase difference layer and the alignment layer was 4 μm.

[0344] [Preparation of resin composition]

[0345] A resin composition containing an acrylic resin was prepared by dissolving 100 parts by mass of dipentaerythritol hexaacrylate (hereinafter also referred to as DPHA) (ARONIX (registered trademark) M-403, manufactured by DAIKIN INDUSTRIES, LTD., multifunctional acrylate) and an acrylate resin (Ebecryl (registered trademark) 4858, manufactured by UCB, aliphatic urethane acrylate) in total, 3 parts by mass of 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropane-l-one (Irgacure (registered trademark) 907; manufactured by Ciba Specialty Chemicals, Inc.), 0.25 parts by mass of a fluorine-based leveling agent (F-554, manufactured by DIC, oligomer containing a fluorine group and an oleophilic group) in 250 parts by mass of isopropyl alcohol. It is to be noted that DPHA and the acrylate resin were compounded at the mass compounding ratios shown in Table 1.

[0346] [Manufacture of laminate (3)]

[0347] The resin composition was applied to the phase difference layer of the laminate (2) using a bar coater. After the resulting applied film was dried at 80°C for 1 minute, ultraviolet rays were irradiated using a high-pressure mercury lamp ("Unicure VB-15201BY-A", manufactured by USHIO ELECTRIC CO., LTD.) (under a nitrogen atmosphere, cumulative light quantity at a wavelength of 365 nm: 400 mJ / cm 2), thereby forming a resin layer. In this way, a laminate (3) composed of the transparent substrate, the alignment layer, the phase difference layer, and the resin layer is produced.

[0348] [Manufacture of LAMINATE (4)]

[0349] After performing a corona treatment on the polarizing plate layer of the laminate (1), the above-mentioned laminate (3) and the laminate (1) were adhered via an adhesive (1) (pressure-sensitive adhesive manufactured by LINTEC Corporation, thickness 15 μm). After the adhesion, only the transparent substrate was peeled off, thereby producing a laminate (4).

[0350] [Manufacture of Polarizing Plate]

[0351] After performing a corona treatment on the alignment layer of the laminate (4), an adhesive (2) (pressure-sensitive adhesive manufactured by LINTEC Corporation, thickness 25 μm) was adhered, thereby producing a laminate (5) (polarizing plate). The laminate (5) was provided with the adhesive (2), the alignment layer, the phase difference layer, the resin layer, the adhesive (1), the polarizing plate layer, and the protective layer in this order.

[0352] [Manufacture of Polarizing Plate for Evaluation]

[0353] The laminate (5) was adhered to an alkali-free glass using the adhesive (2), thereby producing a sample.

[0354] [Comparative Example 2]

[0355] A sample was produced in the same manner as in Example 1, except that the resin layer was not formed.

[0356] [Hygrothermal Durability Test]

[0357] The samples of Examples 1 to 4 and Comparative Examples 1 and 2 were left in an environment of 80°C and 90% relative humidity for 24 hours, and a hygrothermal durability test was performed. The ΔPy and ΔTy of the polarizing plates before and after the test were measured.

[0358] The thickness, the Martens hardness, the breaking load, and the results of the hygrothermal durability test of the resin layer are shown in Table 1.

[0359] [Table 1]

[0360]

[0361] As shown in Table 1, the ΔPy and ΔTy of the polarizing plates of Examples 1 to 4 to which one embodiment of the present application was applied were smaller than those of the polarizing plates of Comparative Examples 1 and 2. It is considered from this that the polarizing plate of one embodiment of the present application has a Martens hardness of 160 N / mm 2 and 500 N / mm 2The following resin layer is thus able to suppress the transfer of the components contained in the phase difference layer to the polarizing plate layer. It is considered that the main reason is that the components contained in the phase difference layer are less likely to be transferred to the polarizing plate layer, but are blocked in the resin layer. Thus, the polarizing plate of one embodiment of the present application can maintain a high degree of polarization even in a humid heat environment.

[0362] It is confirmed from the above that the present application is useful.

Claims

1. A polarizing plate comprising: Polarizing layer Phase difference layer, and A resin layer disposed between the polarizer layer and the phase retardation layer The resin layer is formed from the reaction product of a resin composition comprising a (meth)acrylic resin and a polyfunctional (meth)acrylic ester monomer having three or more (meth)acryloyloxy groups in the molecule. The phase retardation layer is formed using a cured liquid crystal composition as the forming material. The martensitic hardness of the resin layer, as determined by ISO 14577, is 160 N / mm. 2 Above and 400N / mm 2 the following, The breaking load of the resin layer is above 500g and below 2000g.

2. The polarizing plate according to claim 1, wherein, The phase difference layer is a layer that imparts a 1 / 4 wavelength phase difference.

3. A polarizing plate, comprising: Polarizing layer First phase difference layer The resin layer disposed between the polarizer layer and the first phase difference layer, and A second phase retardation layer is disposed on the resin layer side with reference to the polarizer layer. The first phase retardation layer is formed using a cured product of the first liquid crystal composition as the forming material. The second phase retardation layer is formed using a cured product of the second liquid crystal composition. The resin layer is formed from the reaction product of a resin composition comprising a (meth)acrylic resin and a polyfunctional (meth)acrylic ester monomer having three or more (meth)acryloyloxy groups in the molecule. The martensitic hardness of the resin layer, as determined according to ISO 14577, is 160 N / mm. 2 Above and 400N / mm 2 the following, The breaking load of the resin layer is above 500g and below 2000g.

4. The polarizing plate according to claim 3, wherein, The first phase retardation layer has a refractive index of n along the slow axis direction in the in-plane. x Let n be the refractive index of the direction orthogonal to the slow axis in the plane. y And let the refractive index in the thickness direction be n. z When n z >n x ≥n y The layers of this relationship.

5. The polarizing plate according to claim 4, wherein, The second phase difference layer is disposed between the resin layer and the first phase difference layer, and is in contact with the resin layer.

6. The polarizing plate according to claim 4, wherein, The second phase difference layer is disposed between the resin layer and the polarizer layer, and is in contact with the resin layer.

7. The polarizing plate according to claim 6, wherein, The resin layer is in contact with the first phase difference layer.

8. The polarizing plate according to any one of claims 3 to 7, wherein, The second phase difference layer is a layer that imparts a 1 / 4 wavelength phase difference.

9. An organic electroluminescent display device, comprising: Organic electroluminescent display elements, and The polarizing plate according to any one of claims 1 to 8 is disposed on the observation side of the organic electroluminescent display element.

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