Polarizing plate and optical display device

Abstract

The present invention provides a polarizing plate and an optical display device comprising the same, the polarizing plate comprising a polarizer, and a polarizer protective layer, a positive A layer and a positive C layer which are laminated on one surface of the polarizer in this order from the polarizer, the polarizer protective layer being an anisotropic optical layer, and the positive A layer and the positive C layer being laminated on the polarizer protective layer at a wavelength of 550 nm, and the positive A layer and the positive C layer being laminated on the polarizer protective layer in this order from the polarizer. The in-plane phase difference (Re) is more than 10 nm, the biaxial degree (NZ) is more than 0.9 and less than or equal to 1.2, and the slow axis of the polarizer protection layer is parallel to the light absorption axis of the polarizer.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2025-0039485, filed on March 27, 2025, entitled "Polarizing Plate and Optical Display Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to polarizing plates and optical display devices. Background Technology

[0003] Both liquid crystal display devices and organic light-emitting diode (OLED) display devices include polarizing plates. In particular, OLED display devices include polarizing plates, thus effectively removing reflections caused by external light and achieving vivid image quality.

[0004] The polarizing plate includes a polarizer and a retardation layer sequentially stacked on the lower surface of the polarizer. While a resin film can be used as the retardation layer, if a liquid crystal layer is used, it is formed by coating a liquid crystal layer composition, thus providing a thinner polarizing plate. A protective film may also be included between the polarizer and the retardation layer. This protective film can improve the mechanical strength of the polarizing plate.

[0005] Typically, the protective film should not affect the optical performance of the retardation layer; therefore, isotropic protective films are usually used. An isotropic protective film is one in which the refractive index nx along the slow axis and the refractive index ny along the fast axis are identical at a wavelength of 550 nm. Therefore, the isotropic protective film is an unstretched protective film, which may increase the thickness of the polarizing plate.

[0006] The background technology of this invention is disclosed in Japanese Patent Publication No. 2006-251659, etc. Summary of the Invention

[0007] Technical issues

[0008] The purpose of this invention is to provide a polarizing plate that provides the optical effects, blocking effects, and thinness of a phase retardation layer.

[0009] Another object of the present invention is to provide a polarizing plate that provides optical effects, blocking effects and thinness of a laminate of positive A layer and positive C layer.

[0010] Solution to the problem

[0011] One aspect of this invention is a polarizing plate.

[0012] The aforementioned polarizing plate includes: a polarizer, and a polarizer protective layer, a positive A layer and a positive C layer, which are sequentially stacked on one surface of the polarizer. The polarizer protective layer is an anisotropic optical layer with an in-plane phase difference (Re) of more than 10 nm and a biaxiality (NZ) greater than 0.9 and less than or equal to 1.2 at a wavelength of 550 nm. The slow axis of the polarizer protective layer is parallel to the light absorption axis of the polarizer.

[0013] Another aspect of this invention is an optical display device.

[0014] The aforementioned optical display device includes the polarizing plate of the present invention.

[0015] Invention Effects

[0016] The polarizing plate of the present invention does not adversely affect the optical performance of the polarizing plate even though the protective layer of the polarizer is anisotropic, and provides the optical effect of the laminate of positive A layer and positive C layer, while providing a barrier effect, thereby improving the reliability of the polarizing plate. By providing a thin effect, it can provide a thin effect for optical display devices. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0018] Figure 2 This is a cross-sectional view of a polarizing plate according to another embodiment of the present invention. Detailed Implementation

[0019] The invention will be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement it. The invention can be implemented in various different ways and is not limited to the embodiments described herein.

[0020] The terminology used herein is for illustrative purposes only and is not intended to limit the scope of the invention. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0021] In the figures, for the purpose of clearly illustrating the invention, parts unrelated to the description have been omitted. Throughout the specification, the same or similar constituent elements are given the same reference numerals. The lengths and sizes of the constituent elements in the figures are for illustrative purposes; however, the invention is not limited to the lengths and sizes of the constituent elements shown in the figures.

[0022] In this specification, "upper part" and "lower part" are defined based on the accompanying drawings. Depending on the viewing angle, "upper part" can be changed to "lower part" and "lower part" can be changed to "upper part." The term "on" or "above" includes not only the case directly above but also the case where there are other structures in between. Conversely, the terms "directly on," "directly above," "directly formed," or "directly connected" refer to the case where there are no other structures in between.

[0023] In this specification, "in-plane phase difference (Re)," "thickness direction phase difference (Rth)," and "biaxiality degree (NZ)" are represented by the following equations A, B, and C:

[0024] [Formula A]

[0025]

[0026] [Formula B]

[0027]

[0028] [Formula C]

[0029]

[0030] (In Equations A, B, and C above, nx, ny, and nz are the refractive indices of the optical device along the slow axis, fast axis, and thickness, respectively, at the measured wavelength, and d is the thickness of the optical device (unit: nm).)

[0031] Unless otherwise specified in this specification, the in-plane phase difference, thickness direction phase difference, and degree of biaxiality are values ​​measured by transmitting light along the normal direction relative to the in-plane direction of the optics.

[0032] In this specification, when describing angles, "+" indicates an angle in the clockwise direction relative to the reference (0°), and "-" indicates an angle in the counterclockwise direction relative to the reference (0°).

[0033] In this specification, "(meth)acrylate" may refer to acrylate or methacrylate.

[0034] In this specification, when describing numerical ranges, "X to Y" means above X and below Y.

[0035] The polarizing plate of the present invention can be applied to light-emitting device display devices, including liquid crystal display devices or organic light-emitting device display devices. For example, the polarizing plate described above can be used as an anti-reflective polarizing plate in an organic light-emitting device display device.

[0036] The polarizing plate of the present invention includes a laminate of a positive A layer and a positive C layer as a protective layer on one surface of the polarizer panel side. Therefore, the polarizing plate can provide an optical effect derived from the laminate, namely an anti-reflection effect. Here, "anti-reflection effect" can refer to the effect of reducing the maximum reflectivity in all directions and reducing the hue change between the front and the sides.

[0037] The aforementioned polarizing plate also includes a polarizing protective layer, as described below, between the polarizing film and the aforementioned laminate. The aforementioned polarizing protective layer is an anisotropic optical layer with an in-plane phase difference (Re) of 10 nm or more at a wavelength of 550 nm and a biaxiality (NZ) greater than 0.9 and less than or equal to 1.2. The slow axis of the aforementioned polarizing protective layer is parallel to the light absorption axis of the aforementioned polarizing film.

[0038] In one embodiment, the light absorption axis of the polarizer can be the mechanical direction of the polarizer.

[0039] In one embodiment, as described below, the anisotropic optical layer can be manufactured by stretching. Therefore, the anisotropic optical layer, compared to a polarizer protective layer manufactured without stretching, for example, compared to an isotropic optical layer, can provide a thinner polarizer effect.

[0040] The aforementioned anisotropic optical layers have the aforementioned in-plane phase difference and biaxiality, and satisfy the axial relationship. Therefore, they may not affect the realization of the aforementioned optical effect, i.e., the anti-reflection effect, derived from the stack of the aforementioned positive A layer and positive C layer.

[0041] In one embodiment, the anisotropic optical layer can be a polyester-based, polymethyl methacrylate-based, or cyclic olefin polymer-based protective layer. Therefore, when the polarizing plate is placed under high temperature and high humidity for a long time, and dichroic substances such as iodine are dissolved from the polarizing film, the polarizing plate can prevent the laminate from being contaminated by dichroic substances and the panel of the optical display device from being contaminated by dichroic substances, thereby providing a barrier effect.

[0042] According to one embodiment, the polarizing plate includes: a polarizer, and a polarizer protective layer, a positive A layer and a positive C layer, which are sequentially stacked on one surface of the polarizer. The polarizer protective layer is an anisotropic optical layer. At a wavelength of 550 nm, the in-plane phase difference (Re) of the polarizer protective layer is 10 nm or more, and the biaxiality (NZ) is greater than 0.9 and less than or equal to 1.2. The slow axis of the polarizer protective layer is parallel to the light absorption axis of the polarizer.

[0043] The polarizing plate according to one embodiment will now be described in detail.

[0044] polarizer

[0045] Polarizers include light-absorbing polarizers, which have the following functions: separating incident light into two orthogonal polarizing components, allowing one polarizing component to be transmitted and absorbing the other polarizing component.

[0046] In one embodiment, in the in-plane direction of the polarizer, the axis with a high refractive index can be the light absorption axis of the polarizer (e.g., the machine direction of the polarizer (MD)), and the axis with a low refractive index can be the light transmission axis of the polarizer (e.g., the transverse direction of the polarizer (TD)).

[0047] The polarization degree of the polarizer can be above 95%, specifically 95% to 100%, and more specifically 98% to 100%. Within this range, excellent optical properties of the polarizer can be achieved.

[0048] Polarizing films can include polarizing films containing dichroic dyes and uniaxially stretched. Specifically, polarizing films containing dichroic dyes can include those manufactured by MD uniaxial stretching of a polarizing film substrate film and dyeing it with a dichroic dye (e.g., containing iodine or potassium iodide as an iodine-containing substance). The substrate film for the polarizing film may contain polyvinyl alcohol-based films or derivatives thereof, but is not limited thereto. Polarizing films can be manufactured according to methods known in the art.

[0049] The thickness of the polarizer can range from 1 μm to 40 μm, for example, 5 μm to 30 μm or 5 μm to 15 μm. Within this range, it can be used for polarizing plates.

[0050] Polarizing film protective layer

[0051] The polarizer protective layer is adjacent to the polarizer and located on the panel side, compared to the laminate of positive A layer and positive C layer described below.

[0052] The aforementioned polarizer protective layer is an anisotropic optical layer. Here, "anisotropic optical layer" refers to an optical layer in which the refractive index nx along the slow axis and the refractive index ny along the fast axis are different at a wavelength of 550 nm.

[0053] In one embodiment, the anisotropic optical layer can be a polymer film manufactured by stretching. This polymer film serves as a non-stretched polarizer protective layer, which, for example, offers the advantage of providing a thinner profile compared to isotropic optical layers. Furthermore, compared to polarizer protective layers in the form of liquid crystal layers, this polymer film offers the advantage of providing a barrier effect.

[0054] Here, "barrier effect" refers to the ability to prevent corrosion of the panel caused by the leaching of dichroic substances such as iodine from the polarizer when the polarizer is placed under high temperature and high humidity for a long time.

[0055] For example, the aforementioned polymer membrane can be a polyester-based, polymethyl methacrylate-based, or cyclic olefin polymer-based membrane. The aforementioned polyester-based or cyclic olefin polymer-based membranes can readily provide the aforementioned barrier effect. The aforementioned polyester-based membrane can be a polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, or polybutylene naphthalate membrane.

[0056] The anisotropic optical layer has the following characteristics: (i) an in-plane phase difference (Re) of 10 nm or more at a wavelength of 550 nm; (ii) a biaxiality (NZ) greater than 0.9 and less than or equal to 1.2 at a wavelength of 550 nm; and (iii) a slow axis of the anisotropic optical layer that is parallel to the light absorption axis of the polarizer.

[0057] The anisotropic optical layer, by simultaneously satisfying (i) to (iii) above, may not affect the optical effect, i.e., the anti-reflection effect, brought about by the stack of the positive A layer and the positive C layer.

[0058] In the above (i) to (iii), if only (i) is satisfied, color distortion caused by phase difference usually occurs. However, in this invention, if all conditions (i) to (iii) are satisfied, color distortion will not occur. This was discovered by the inventors of this invention through research.

[0059] In one embodiment, the anisotropic optical layer has an in-plane phase difference of 10 to 1000 nm at a wavelength of 550 nm, for example, it can be 100 to 1000 nm.

[0060] If (ii) is not satisfied in (i) to (iii) above, there may be a problem in achieving the above-mentioned polarizer effect. If the biaxiality (NZ) is below 0.9, the hue change between the front and side surfaces may increase. If the biaxiality (NZ) is greater than 1.2, the maximum reflectivity may increase.

[0061] In one embodiment, the biaxiality of the anisotropic optical layer at a wavelength of 550 nm can be between 1 and 1.2.

[0062] If (iii) is not satisfied in (i) to (iii) above, the maximum reflectivity will increase, which may lead to an increase in the hue change between the front and the side.

[0063] The aforementioned polarizer protective layer can be manufactured by: producing an unstretched film from a resin-containing composition by melt extrusion or solution casting, and then uniaxially stretching the unstretched film in a mechanical direction. For example, the stretch ratio is 1.5 times or more, such as 2 to 6 times.

[0064] In one embodiment, the resin may comprise one or more of polyester resins, polymethyl methacrylate resins, or cyclic olefin polymer resins. In this case, the anisotropic optical layer may be advantageous in providing a barrier effect.

[0065] In one embodiment, the slow axis of the polarizer protective layer may be parallel to the mechanical direction of the polarizer protective layer.

[0066] The thickness of the aforementioned polarizer protective layer is 20 μm or less, for example, 10 μm or less, or for example, it can be greater than 0 μm and less than or equal to 10 μm. Within the above range, a thinner polarizer plate can be provided.

[0067] The polarizing plate may include an adhesive layer or bonding layer between the anisotropic optical layer and the positive A layer. The polarizing plate may also include an adhesive layer or bonding layer between the positive A layer and the positive C layer.

[0068] Phase difference layer stack

[0069] The stack of positive A layer and positive C layer is stacked in the order of polarizer, polarizer protective layer and phase difference layer.

[0070] In one embodiment, for an anti-reflective polarizing plate suitable for an organic light-emitting display, the polarizer can be stacked in the order of polarizer, polarizer protective layer, positive A layer, and positive C layer. In this case, the order of positive A layer and positive C layer can be interchanged.

[0071] The positive C layer can satisfy Refractive index relationship. At a wavelength of 550 nm, the phase difference in the thickness direction of the positive C layer is -150 nm to -50 nm, for example, it can be -110 nm to -50 nm or -90 nm to -50 nm. Within these ranges, anti-reflective effects can be easily provided.

[0072] The positive C layer has an in-plane phase difference of 0 nm to 10 nm at a wavelength of 550 nm, preferably 0 nm to 5 nm. Within this range, the aforementioned thickness-direction phase difference can be easily provided.

[0073] Layer A can satisfy Refractive index relationship. At a wavelength of 550 nm, the in-plane phase difference of the positive A layer is 100 nm to 160 nm, preferably 110 nm to 150 nm. Within this range, anti-reflective effects can be easily provided.

[0074] The positive A layer exhibits a biaxiality of 0.9 to 1.2 at a wavelength of 550 nm, preferably 0.95 to 1.1. Within this range, it contributes to providing an anti-reflective effect.

[0075] The positive C layer can be a liquid crystal layer or a non-liquid crystal layer.

[0076] When the positive C layer is a liquid crystal layer, it can be formed by coating a liquid crystal layer composition onto a substrate film or similar material and then drying and curing it. The liquid crystal layer-shaped positive C layer is manufactured without stretching or similar processes, thus easily reducing the bending of the polarizing plate. The liquid crystal layer composition can be formed from conventional liquid crystal layer compositions known to those skilled in the art. For example, the liquid crystal layer composition can be a nematic liquid crystal or a disk-shaped liquid crystal, etc.

[0077] When the positive C layer is a non-liquid crystal layer, it can be formed by coating a non-liquid crystal layer onto a substrate film or similar material using a composition, followed by drying and curing. The non-liquid crystal layer in the form of the positive C layer is a non-stretchable coating layer, manufactured without stretching or other processes; therefore, it is easier to reduce the bending of the polarizing plate.

[0078] As a non-stretched coating layer, the composition forming the positive C layer may contain, for example, compounds such as cellulose esters, cellulose ethers, cellulose resins, polystyrene resins, oligomers, or monomers.

[0079] Cellulose compounds may contain at least a portion of the hydroxyl groups [C2 hydroxyl, C3 hydroxyl, or C6 hydroxyl] of the sugar monomers forming cellulose that are substituted with acyl or ether groups. That is, cellulose compounds may contain one or more of cellulose ester polymers and cellulose ether polymers.

[0080] For example, cellulose polymers can include cellulose ester polymers: as shown in Formula 1 below, the cellulose polymer contains at least a portion of the hydroxyl groups [C2 hydroxyl, C3 hydroxyl, or C6 hydroxyl] of the sugar monomers forming cellulose that are substituted with acyl groups. In this case, the acyl groups may be substituted or unsubstituted.

[0081] [Chemical Formula 1]

[0082]

[0083] (In the above chemical formula 1, n is an integer greater than or equal to 1.)

[0084] Substituents used in cellulose esters or acyl groups may each contain one or more of the following: halogen, nitro, alkyl (e.g., alkyl with 1 to 20 carbon atoms), alkenyl (e.g., alkenyl with 2 to 20 carbon atoms), cycloalkyl (e.g., cycloalkyl with 3 to 10 carbon atoms), aryl (e.g., aryl with 6 to 20 carbon atoms), heteroaryl (e.g., aryl with 3 to 10 carbon atoms), alkoxy (e.g., alkoxy with 1 to 20 carbon atoms), acyl, or halogen-containing functional groups. Substituents may be the same or different.

[0085] The aforementioned "acyl group" can be as known to those skilled in the art, RC(=O)- ( As a connecting symbol, R can be an alkyl group with 1 to 20 carbon atoms, a cycloalkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, or an arylalkyl group with 7 to 20 carbon atoms. The aforementioned "acyl group" is bonded to the ring of cellulose through ester bonding (through oxygen atoms).

[0086] For convenience, the terms "alkyl", "alkenyl", "cycloalkyl", "aryl", "heteroaryl", "alkoxy", and "acyl" are each non-halogenated systems that do not contain halogens. The composition for the first phase difference layer may contain the above-mentioned cellulose ester system alone, or it may contain a mixture of the above-mentioned cellulose ester system.

[0087] The term "halogen" refers to fluorine (F), Cl, Br, or I, preferably F.

[0088] The aforementioned "halogen-containing functional group" refers to an organic functional group containing one or more halogens, which may include aromatic, aliphatic, or alicyclic functional groups. For example, a halogen-containing functional group may refer to an alkyl group with 1 to 20 carbon atoms substituted by a halogen, an alkenyl group with 2 to 20 carbon atoms substituted by a halogen, an alkynyl group with 2 to 20 carbon atoms substituted by a halogen, a cycloalkyl group with 3 to 10 carbon atoms substituted by a halogen, an alkoxy group with 1 to 20 carbon atoms substituted by a halogen, an acyl group with 6 to 20 carbon atoms substituted by a halogen, or an arylalkyl group with 7 to 20 carbon atoms substituted by a halogen, but is not limited to these.

[0089] The aforementioned "halogen-substituted acyl group" can be R'-C(=O)- ( The symbol R' represents an alkyl group with 1 to 20 carbon atoms substituted by a halogen, a cycloalkyl group with 3 to 20 carbon atoms substituted by a halogen, an aryl group with 6 to 20 carbon atoms substituted by a halogen, or an arylalkyl group with 7 to 20 carbon atoms substituted by a halogen. The aforementioned "halogen-substituted acyl group" is bonded to the ring of cellulose via ester bonding (through oxygen atoms).

[0090] Cellulose ester polymers can be manufactured by conventional methods known to those skilled in the art, or by purchasing commercially available products. For example, cellulose ester polymers having acyl groups as substituents are manufactured by reacting a sugar monomer or polymer of a sugar monomer forming cellulose of the above chemical formula 1 with trifluoroacetic acid or trifluoroacetic anhydride, or by reacting with trifluoroacetic acid or trifluoroacetic anhydride and then further reacting with an acylating agent (e.g., carboxylic anhydride or carboxylic acid), or by reacting trifluoroacetic acid or trifluoroacetic anhydride together with an acylating agent, followed by polymerization.

[0091] Polystyrene polymers may contain repeating units of the following chemical formula 2:

[0092] [Chemical Formula 2]

[0093]

[0094] (In the above chemical formula 2, Indicates the connection point, R 1 R 2 R 3 Each of the following is independently a hydrogen atom, alkyl group, substituted alkyl group, or halogen; R is independently an alkyl group, substituted alkyl group, halogen, hydroxyl group, carboxyl group, nitro group, alkoxy group, amino group, sulfonate group, phosphate group, acyl group, acyloxy group, phenyl group, alkoxycarbonyl group, cyano group; and n is an integer from 0 to 5.

[0095] Polystyrene polymers can be halogenated polystyrene polymers. In formula 2, R... 1 R 2 R 3 One or more of them are halogens and / or at least one R can be a halogen. In one embodiment, the halogen represents fluorine (F), Cl, Br or I, preferably F.

[0096] For example, halogenated polystyrene polymers can be formed by polymerizing a mixture containing one or more of 1-(2,2-difluorovinyl)-2-fluorobenzene and 1',2',2'-trifluorostyrene. The mixture may also contain styrene.

[0097] Preferably, the positive C layer can be a liquid crystal layer. In this case, a thin polarizing plate can be provided.

[0098] The thickness of the positive C layer is less than 10 μm, specifically greater than 0 μm and less than or equal to 10 μm, and more specifically, it can be from 1 μm to 5 μm. Within the above range, it can be used for polarizing plates, providing a thinner polarizing plate effect.

[0099] The positive A layer can be a liquid crystal layer or a non-liquid crystal layer.

[0100] When the positive A layer is a liquid crystal layer, it can be formed by coating a liquid crystal layer composition onto a substrate film or similar material and then drying and curing it. The liquid crystal layer in the form of the positive A layer is manufactured without stretching or similar processes, thus easily reducing the bending of the polarizing plate. The liquid crystal layer composition can be formed from conventional liquid crystal layer compositions known to those skilled in the art. For example, the liquid crystal layer composition can be a nematic liquid crystal or a disk-shaped liquid crystal, etc.

[0101] When the positive A layer is a non-liquid crystal layer, the positive A layer can be a film formed from one or more resins selected from the following: cellulose-based resins including triacetyl cellulose (TAC); polyester-based resins including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PET), and polybutylene naphthalate; cyclic olefin polymer-based resins; polycarbonate-based resins; polyethersulfone-based resins; polysulfone-based resins; polyamide-based resins; polyimide-based resins; polyolefin-based resins; polyarylate-based resins; polyvinyl alcohol-based resins; polyvinyl chloride-based resins; and polyvinylidene chloride-based resins. Preferably, the positive A layer can be a cyclic olefin polymer-based layer.

[0102] Preferably, the positive A layer can be a liquid crystal layer. In this case, a thin polarizing plate can be provided.

[0103] The thickness of the positive A layer can be less than 10 μm, specifically, it can be greater than 0 μm and less than or equal to 10 μm, and more specifically, it can be from 3 μm to 5 μm. Within the above range, it can be used for polarizing plates, providing a thinner polarizing plate effect.

[0104] In one embodiment, the slow axis of the positive A layer forms an angle of 40 to 50° with the light absorption axis of the polarizer, for example, 45°. Within this range, the anti-reflection effect of the laminated phase retardation layers can be further improved.

[0105] On the other hand, when at least one of the positive A layer and the positive C layer is a liquid crystal layer, a thinner polarizing effect can be achieved. However, when the polarizing plate is placed under high temperature and high humidity for a long time, the liquid crystal layer may be contaminated by dichroic substances such as iodine that may leach from the polarizer. However, the polarizer protective layer described above provides a barrier effect, thus preventing contamination caused by dichroic substances such as iodine. As an anisotropic optical layer, it provides a thinner polarizing effect without affecting the optical effects of the positive A layer and the positive C layer.

[0106] Adhesive layer

[0107] The adhesive layer can be formed from a composition comprising an adhesive resin. In one embodiment, the adhesive resin may comprise one or more of (meth)acrylic resins, epoxy resins, silane resins, and polyurethane resins; preferably, (meth)acrylic resins may be used. In one embodiment, the adhesive layer may be a pressure-sensitive adhesive layer.

[0108] The thickness of the aforementioned adhesive layer is 3 to 20 μm, for example, it can be 5 to 10 μm. Within this range, a thinner polarizing plate can be achieved.

[0109] Adhesive layer

[0110] The adhesive layer may include an adhesive layer formed from an adhesive composition comprising an adhesive resin.

[0111] In one embodiment, the adhesive layer may comprise an adhesive layer formed of a photocurable adhesive or a thermocurable adhesive. In one embodiment, the photocurable adhesive may comprise an epoxy resin, a (meth)acrylate resin, and a photoinitiator. The epoxy resin, (meth)acrylate resin, and photoinitiator may be of common types known to those skilled in the art.

[0112] The thickness of the aforementioned adhesive layer is 0.1 to 5 μm, for example, it can be 0.1 to 3 μm. Within this range, a thinner polarizing plate can be achieved.

[0113] The polarizing plate may also include a protective layer on the other surface of the polarizer.

[0114] protective layer

[0115] The protective layer is stacked on the upper surface of the polarizer, which can improve the mechanical strength of the polarizer.

[0116] The aforementioned protective layer can be a coating or film of a liquid crystal layer or a non-liquid crystal layer. For example, the aforementioned protective layer can be an optically transparent film. Specifically, the aforementioned protective layer can be a film formed from one or more resins selected from the following: cellulose-based resins containing triacetyl cellulose (TAC); polyester-based resins containing polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; cyclic olefin polymer (COP)-based resins; polycarbonate-based resins; polyethersulfone-based resins; polysulfone-based resins; polyamide-based resins; polyimide-based resins; polyolefin-based resins; polyarylate-based resins; polyvinyl alcohol-based resins; polyvinyl chloride-based resins; and polyvinylidene chloride-based resins. In one embodiment, the aforementioned protective layer can be a cellulose-based or cyclic olefin polymer (COP)-based protective layer containing triacetyl cellulose (TAC).

[0117] The thickness of the aforementioned protective layer is from 25 μm to 80 μm, for example, it can be from 30 μm to 60 μm. Within this range, it can be used for polarizing plates.

[0118] The aforementioned protective layer can be bonded to the polarizer via an adhesive layer or bonding layer. The adhesive layer or bonding layer can be formed from a thermosetting or photocurable adhesive composition. The thickness of the adhesive layer or bonding layer can be from 1 μm to 30 μm, for example, from 2 μm to 10 μm or from 2 μm to 3 μm.

[0119] The aforementioned protective layer may be further coated with a functional coating on at least one surface. This functional coating may be a hard coating, a fingerprint-resistant layer, an anti-reflective layer, a low-reflective layer, an anti-glare layer, a primer layer, etc.

[0120] Figures 1 to 2 This is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0121] Reference Figure 1 The polarizing plate may include: a polarizer 10, a polarizer protective layer 20, a positive A layer 30 and a positive C layer 40 sequentially stacked on the lower surface of the polarizer 10, and a protective layer 50 stacked on the upper surface of the polarizer 10.

[0122] Reference Figure 2 The polarizing plate may include: a polarizing film 10, a polarizing film protective layer 20, a first adhesive layer or bonding layer 60, a positive A layer 30, a second adhesive layer or bonding layer 70 and a positive C layer 40, which are sequentially stacked on the lower surface of the polarizing film 10, and a protective layer 50 stacked on the upper surface of the polarizing film 10.

[0123] The optical display device of the present invention includes the polarizing plate of the present invention. In one embodiment, the optical display device may be a liquid crystal display device or a light-emitting device display device.

[0124] The liquid crystal display device includes a liquid crystal panel, a polarizing plate of the present invention laminated on the light emitting surface of the liquid crystal panel, and a polarizing plate (light source side polarizing plate) disposed on the light incident surface of the liquid crystal panel. The polarizing plate disposed on the light incident surface may include polarizing plates commonly known to those skilled in the art. The polarizing plate of the present invention can be used as a visual side polarizing plate. However, the present invention is not limited thereto; the polarizing plate of the present invention can be used as a visual side polarizing plate or a light source side polarizing plate.

[0125] The light-emitting device display device includes a panel containing light-emitting devices and a polarizing plate of the present invention located on the panel. The light-emitting device display device can be an organic light-emitting device display device, an inorganic light-emitting device display device, or an organic-inorganic light-emitting device display device.

[0126] The structure and function of the present invention will now be described in more detail through preferred embodiments. However, the following embodiments are provided to aid in understanding the present invention, and the scope of the present invention is not limited to the following embodiments.

[0127] Example 1

[0128] (1) Manufacturing of polarizers

[0129] A polyvinyl alcohol membrane (TS3000, manufactured by KURARAY, thickness: 30 μm), washed with water at 25 °C, was swelled in a swelling bath at 25 °C. The membrane, after passing through the swelling bath, was then treated for 65 seconds in a dyeing bath at 30 °C containing an aqueous solution of 1 mol / ml potassium iodide and 0.45 wt% boric acid. The membrane, after passing through the dyeing bath, was stretched in a wet stretching bath at 60 °C containing an aqueous solution of 3.6 wt% boric acid at a uniaxial stretching ratio of 5.6 times the MD. The membrane, after passing through the wet stretching bath, was treated for 65 seconds in a crosslinking bath containing an aqueous solution of 3 wt% boric acid at 25 °C. The membrane, after passing through the crosslinking bath, was treated for 10 seconds in a color-correcting bath containing a color-correcting solution of 2.5 wt% potassium iodide at 23 °C. The membrane, after passing through the color-correcting bath, was washed with water and dried to produce a polarizer (thickness: 10 μm).

[0130] (2) Manufacturing of polarizing plates

[0131] As the positive A layer, a liquid crystal layer (with an in-plane phase difference of 142nm at a wavelength of 550nm, thickness: 2μm, MR4DN-I (0.83), manufactured by DNP Corporation) was used.

[0132] As the positive C layer, a liquid crystal layer (with a phase difference of -80nm in the thickness direction at a wavelength of 550nm, thickness: 1μm, MCP-I (80), manufactured by DNP Corporation) was used.

[0133] A composition containing polyethylene terephthalate (PET) was melt-extruded to produce an unstretched PET film. The unstretched PET film was then uniaxially stretched along a mechanical direction at a stretch ratio of 4, and heat-fixed to produce a polarizer protective layer. This polarizer protective layer is a PET film and an anisotropic optical layer with an in-plane phase difference of 1000 nm and a biaxiality of 1 at a wavelength of 550 nm, and a thickness of 5 μm.

[0134] A light-curing adhesive (epoxy resin adhesive) is coated on the upper surface of the polarizer manufactured above as a protective layer, and then a triacetyl cellulose membrane is bonded to it.

[0135] A polyethylene terephthalate film, a positive A layer, and a positive C layer, all manufactured as described above, are sequentially deposited on the lower surface of the polarizer and bonded together using a photocurable adhesive to create a polarizing plate. In this case, the slow axis of the positive A layer forms a 45° angle with the light absorption axis of the polarizer, and the light absorption axis of the polarizer is parallel to the slow axis of the polyethylene terephthalate film.

[0136] Example 2

[0137] In Example 1, when manufacturing the polyethylene terephthalate film, it was stretched along the mechanical direction, and the stretching ratio and stretching temperature were changed. Otherwise, the polarizing plate was manufactured by the same method as in Example 1.

[0138] Example 3

[0139] In Example 1, when manufacturing the polyethylene terephthalate film, it was stretched along the mechanical direction, and the stretching ratio and stretching temperature were changed. Otherwise, the polarizing plate was manufactured by the same method as in Example 1.

[0140] Comparative Example 1

[0141] In Example 1, when manufacturing the polyethylene terephthalate film, it was stretched along the mechanical direction, and the stretching ratio and stretching temperature were changed. Otherwise, the polarizing plate was manufactured by the same method as in Example 1.

[0142] Comparative Example 2

[0143] In Example 1, when manufacturing the polyethylene terephthalate film, it was stretched in the transverse direction, and the stretching ratio and stretching temperature were changed. Otherwise, the polarizing plate was manufactured by the same method as in Example 1.

[0144] Comparative Example 3

[0145] In Example 1, when bonding the polyethylene terephthalate film to the polarizer, the film was attached by twisting the angle by 90°. Otherwise, the polarizer was manufactured by the same method as in Example 1.

[0146] Comparative Example 4

[0147] In Example 1, the polyethylene terephthalate film was replaced with an isotropic triacetyl cellulose (TAC) film, and the polarizing plate was manufactured using the same method as in Example 1.

[0148] The physical properties of the polarizing plates of the embodiments and comparative examples were evaluated in Table 1 below.

[0149] (1) Anti-reflection effect: The maximum reflectivity and hue change in all directions were calculated using the Techwiz1D simulation program and the mirror extension method. The OLED panel was used as the reference for the fully reflective plate.

[0150] (2) Visual evaluation of the degree of panel corrosion due to iodine leaching: The polarizing film was bonded to the aluminum foil and placed in a constant temperature and humidity chamber at 85°C. The liquid crystal and polarizing film were bonded using UV bonding, and the surface bonded to the aluminum foil was bonded using PSA bonding. An evaluation film (thickness: 1T) was placed between the upper and lower glass panes to prevent corrosion from occurring only in specific locations and to ensure that the constant temperature and humidity conditions were uniformly applied to the entire surface. After 288 hours, the degree of corrosion was visually evaluated and classified as good / poor. The criteria were as follows: when corrosion was visible to the naked eye, it was classified as poor; when there was no change, it was classified as normal; and when there was no change, it was classified as good.

[0151]

[0152] • Angle: The angle formed between the slow axis of the protective layer of the polarizer and the light absorption axis of the polarizer.

[0153] • Hue variation: In La b Based on color coordinates, a Overall range and b The value of multiplying the entire range.

[0154] As shown in Table 1 above, the polarizing plate of the present invention has an omnidirectional maximum reflectance of less than 4.5% and a hue change value of less than 1000, providing good performance in panel corrosion evaluation. Furthermore, the polarizing plate of the present invention includes an anisotropic optical layer, thereby providing a thin profile.

[0155] Conversely, as shown in Table 1 above, comparative examples that do not meet the requirements for biaxiality of the polarizer protective layer, or the angle between the light absorption axis of the polarizer and the slow axis of the polarizer protective layer according to the present invention, show poorer performance compared to the embodiments in terms of hue change and omnidirectional maximum reflectivity. Furthermore, Comparative Example 4, which has an isotropic optical layer, does not provide a thinner profile compared to the embodiments due to the greater thickness of the isotropic optical layer.

[0156] Simple modifications and alterations to the present invention can be readily implemented by those skilled in the art, and such modifications or alterations are all considered to be included within the scope of the present invention.

Claims

1. A polarizing plate, wherein, include: A polarizer, and a polarizer protective layer, and a stack of positive A layer and positive C layer sequentially stacked on one surface of the polarizer. The polarizer protective layer is an anisotropic optical layer. The polarizer protective layer, at a wavelength of 550 nm, exhibits an in-plane phase difference (Re) of more than 10 nm and a biaxiality (NZ) greater than 0.9 and less than or equal to 1.

2. The slow axis of the polarizer protective layer is parallel to the light absorption axis of the polarizer.

2. The polarizing plate according to claim 1, wherein, The polarizer protective layer has an in-plane phase difference of 10 to 1000 nm at a wavelength of 550 nm.

3. The polarizing plate according to claim 1, wherein, The slow axis of the polarizer protective layer is parallel to the mechanical direction of the polarizer protective layer.

4. The polarizing plate according to claim 1, wherein, The polarizer protective layer is a polyester-based, polymethyl methacrylate-based, or cyclic olefin polymer-based film.

5. The polarizing plate according to claim 1, wherein, The thickness of the polarizer protective layer is less than 20 μm.

6. The polarizing plate according to claim 1, wherein, The positive A layer is a liquid crystal layer, and the positive C layer is a liquid crystal layer.

7. The polarizing plate according to claim 1, wherein, The polarizer is sequentially stacked with the polarizer protective layer, the positive A layer, and the positive C layer.

8. The polarizing plate according to claim 1, wherein, The positive C layer has a phase difference of -150nm to -50nm in the thickness direction at a wavelength of 550nm.

9. The polarizing plate according to claim 1, wherein, The positive A layer has an in-plane phase difference of 100nm to 160nm at a wavelength of 550nm.

10. An optical display device, wherein, The polarizing plate includes any one of claims 1 to 9.

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