Polarizing plate and optical display device

Abstract

The invention discloses a polarizing plate and an optical display device. A polarizing plate includes a polarizer and a retardation layer laminated on a surface of the polarizer, the retardation layer including a retardation film satisfying a relationship nx > nz > ny, where nx, ny, and nz are refractive indexes of the retardation film in a slow axis direction, a fast axis direction, and a thickness direction of the retardation film, respectively, at a wavelength of 550 nm, the orientation direction of the main chain of the resin contained in the retardation film with respect to the light transmission axis of the polarizer is in the range of-5 DEG to + 5 DEG, and the retardation film has a biaxality of 0.2 to 0.6 at a wavelength of 550 nm.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0074730 filed in the Korean Intellectual Property Office on June 12, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Aspects of embodiments of the present invention relate to a polarizing plate and an optical display device including the polarizing plate. Background Art

[0004] The liquid crystal display device includes a liquid crystal panel as a panel of an optical display device, a viewer-side polarizer stacked on the upper surface of the liquid crystal panel, and a light source-side polarizer stacked on the lower surface of the liquid crystal panel. Among the methods of driving the liquid crystal panel, the transverse electric field method is a method of orienting a liquid crystal compound in the in-plane direction of the substrate of the liquid crystal panel by an electric field including a component substantially parallel to the substrate surface. The transverse electric field method includes an in-plane switching (IPS) method, a fringefield switching (FFS) method, or a similar method. By providing a retardation layer between the liquid crystal panel and the polarizer, the transverse electric field method can improve contrast and viewing angle, and minimize or reduce color changes.

[0005] The background art of the present invention is disclosed in Korean Patent Application Publication No. 2013-0103595. Summary of the invention

[0006] According to an aspect of an embodiment of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and capable of improving visibility at all viewing angles and minimizing or reducing color change.

[0007] According to another aspect of an embodiment of the present invention, there is provided a polarizing plate including a retardation film consisting of a single layer and capable of improving light leakage by reducing a maximum light transmittance in a black mode at all viewing angles.

[0008] According to another aspect of an embodiment of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and thus exhibiting an excellent thickness-reducing effect.

[0009] According to another aspect of an embodiment of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and capable of being manufactured to have a wide width in a transverse direction.

[0010] According to an embodiment, a laminate composed of a positive C (+C) retardation layer and a positive A (+A) retardation layer may be used as a retardation layer. For example, in a polarizing plate, a polarizer, a +C layer, a photosensitive adhesive layer, and a +A layer may be stacked in the stated order. The polarizing plate may include two retardation layers, a +C layer and a +A layer. Therefore, in order to provide an effect of thinning the polarizing plate, the retardation layer may be formed of a single layer.

[0011] According to one or more embodiments of the present invention, a polarizing plate includes a polarizer and a delay layer stacked on the surface of the polarizer, wherein the delay layer includes a delay film satisfying the relationship nx>nz>ny, wherein nx, ny and nz are the refractive indices of the delay film in the slow axis direction, fast axis direction and thickness direction of the delay film at a wavelength of 550nm, respectively, the orientation direction of the main chain of the resin contained in the delay film relative to the light transmission axis of the polarizer is in the range of -5° to +5°, and the delay film has a biaxiality of 0.2 to 0.6 at a wavelength of 550nm.

[0012] According to an embodiment, an optical display device includes the polarizing plate according to the embodiment.

[0013] According to one or more embodiments of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and capable of improving visibility at all viewing angles and minimizing or reducing color change.

[0014] According to one or more embodiments of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and capable of improving light leakage by reducing a maximum light transmittance in a black mode at all viewing angles.

[0015] According to one or more embodiments of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and thus exhibiting an excellent thickness reduction effect.

[0016] According to one or more embodiments of the present invention, there is provided a polarizing plate including a retardation film composed of a single layer and capable of being manufactured to have a wide width in a transverse direction. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 2 is a cross-sectional view of a polarizing plate according to another embodiment.

[0019] Figure 3The maximum light transmittance values ​​(Y axis, unit: %) at all viewing angles according to the biaxiality (NZ) and in-plane retardation (X axis, unit: nm) of the retardation film at a wavelength of 550 nm are shown when the polarizing plate according to the embodiment is mounted on a device using the transverse electric field method and operated. Figure 3 In the figure, ■ represents the light transmittance when the NZ of the retardation film is 0.4 at a wavelength of 550 nm, ● represents the light transmittance when the NZ of the retardation film is 0.5 at a wavelength of 550 nm, and ▲ represents the light transmittance when the NZ of the retardation film is 0.6 at a wavelength of 550 nm. DETAILED DESCRIPTION

[0020] The present invention will be described in more detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. It should be understood that the present invention can be implemented in different ways and is not limited to the embodiments described herein.

[0021] In the accompanying drawings, parts not related to the description may be omitted to clearly illustrate the present invention, and the same or similar components are represented by the same reference numerals throughout the specification. In the accompanying drawings, the length and size of each component may be provided to illustrate the present invention; however, the present invention is not limited to the length and size of each component shown in the accompanying drawings.

[0022] The terms used herein are used to describe some exemplary embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, a singular expression includes a plural expression.

[0023] In this specification, “in-plane retardation Re” is represented by the following equation A, “thickness direction retardation Rth” is represented by the following equation B, and “biaxiality NZ” is represented by the following equation C.

[0024] Formula A

[0025] Re = (nx - ny)xd;

[0026] Formula B

[0027] Rth = ((nx + ny) / 2 - nz) xd;

[0028] Formula C

[0029] NZ=(nx-nz) / (nx-ny),

[0030] Wherein, in equations A to C, nx, ny and nz are the refractive indices of the optical device in the slow axis direction, the fast axis direction and the thickness direction of the optical device at the measuring wavelength, respectively, and d is the thickness of the optical device (unit: nm). In equations A to C, the measuring wavelength may be a specific wavelength selected from 450 nm to 650 nm.

[0031] In this specification, unless otherwise specified, nx, ny and nz refer to the refractive index of an optical device in the slow axis (axis with maximum refractive index in the in-plane direction), the fast axis (axis with minimum refractive index in the in-plane direction) and the thickness direction of the optical device at a wavelength of 550 nm.

[0032] As used herein, when describing an angle, "+" refers to a counterclockwise direction about a reference point, while "-" refers to a clockwise direction about a reference point.

[0033] In this specification, the term "light transmittance" refers to total light transmittance, not orthogonal light transmittance.

[0034] Herein, the term "(meth)acryloyl" refers to acryloyl and / or methacryloyl.

[0035] As used herein, to express a numerical range, the expression “X to Y” means “greater than or equal to X and less than or equal to Y (X≤ and ≤Y)”.

[0036] The polarizing plate according to the embodiment includes a retardation film composed of a single layer. The polarizing plate improves visibility at all viewing angles, minimizes or reduces color changes, improves light leakage by reducing the maximum light transmittance in black mode at all viewing angles, and has an excellent thickness reduction effect. In this context, "reducing the maximum light transmittance" refers to reducing the light transmittance of light emitted at all viewing angles in black mode when the polarizing plate is applied to an optical display device and operated, thereby preventing or substantially preventing light leakage.

[0037] In embodiments, a smaller maximum light transmittance may be more desirable. In embodiments, the maximum light transmittance may be less than or equal to 0.9%, such as 0 to 0.5%, 0 to 0.3%, 0.1% to 0.4%, or 0.1% to 0.3%.

[0038] The polarizing plate according to the embodiment includes a retardation film composed of a single layer, and the retardation film may be manufactured to have a wide width in a transverse direction, thereby improving workability and economic feasibility when manufacturing the polarizing plate.

[0039] According to the embodiment, the polarizing plate includes a polarizer and a delay layer stacked on the surface of the polarizer, wherein the delay layer includes a delay film satisfying the relationship nx>nz>ny, wherein nx, ny and nz are the refractive indices of the delay film in the slow axis direction, fast axis direction and thickness direction of the delay film at a wavelength of 550nm, respectively, the orientation direction of the main chain of the resin contained in the delay film relative to the light transmission axis of the polarizer is in the range of -5° to +5°, and the delay film has a biaxiality of 0.2 to 0.6 at a wavelength of 550nm.

[0040] The polarizing plate can be a polarizing plate on the audience side or a polarizing plate on the light source side.

[0041] According to embodiments, the retardation layer may be located between the polarizer of the viewer-side polarizing plate and the panel (eg, liquid crystal panel) of the optical display device. In embodiments, the light absorption axis of the polarizer of the viewer-side polarizing plate and the alignment direction of the liquid crystal of the panel may be substantially orthogonal to each other.

[0042] According to another embodiment, the retardation layer may be located between the polarizer of the light source side polarizing plate and the panel of the optical display device. In an embodiment, the light absorption axis of the polarizer of the light source side polarizing plate and the alignment direction of the liquid crystal of the panel may be substantially orthogonal to each other.

[0043] In the embodiment, the retardation film is a retardation film composed of a single layer. This provides an effect of reducing the thickness of the polarizing plate in the manufacture of the polarizing plate, and improves processability and economic feasibility. Herein, "a retardation film composed of a single layer" refers to a retardation film composed of only one layer, rather than two or more retardation films joined by a photosensitive adhesive layer, an adhesive layer, etc.

[0044] According to an embodiment, the thickness of the retardation film may be 40 μm to 100 μm, for example, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, for example, 40 μm to 80 μm. Within this range, the retardation film can be applied to the polarizing plate and can provide a thickness reduction effect.

[0045] In an embodiment, the retardation layer may be formed of only the retardation film. This provides an effect of reducing the thickness of the polarizing plate in the manufacture of the polarizing plate, and improves workability and economic feasibility.

[0046] According to an embodiment, in the polarizing plate, only a retardation film exists between the polarizer and the adherend (e.g., a panel of an optical display device). In this case, in the polarizing plate, an adhesive layer, a retardation film, and a photosensitive adhesive layer may be sequentially stacked on the surface of the polarizer, and the photosensitive adhesive layer may be adhered to the adherend.

[0047] According to another embodiment, in the polarizing plate, there may be a retardation film and one or more lower protective layers between the polarizer and the adherend (e.g., a panel of an optical display device). The lower protective layer may be present between the polarizer and the retardation film and / or between the retardation film and the adherend. In an embodiment, in the polarizing plate, an adhesive layer, a retardation film, a lower protective layer, and a photosensitive adhesive layer may be sequentially stacked on the surface of the polarizer, and the photosensitive adhesive layer may be adhered to the adherend.

[0048] In an embodiment, at a wavelength of 550 nm, the lower protective layer may have an in-plane retardation of less than or equal to 10 nm (e.g., 0 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, e.g., 0 nm to 10 nm). Within the above range, the effect of protecting the polarizer can be provided without affecting the function and effect of the retardation film. The lower protective layer may be an optically transparent film or coating. For example, the lower protective layer may be a film made of one or more resins selected from the following: cellulose resins including triacetylcellulose (TAC), polyester resins including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., cyclic olefin copolymer (COC) resin, cyclic olefin polymer (COP) resin, polycarbonate resin, polyether sulfone resin, polysulfone resin, polyamide resin, polyimide resin, polyolefin resin, polyarylate resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin and acrylic resin.

[0049] In the retardation film, nx>nz>ny, wherein nx, ny and nz are the refractive indices of the retardation film in the slow axis direction, the fast axis direction and the thickness direction of the retardation film at a wavelength of 550 nm, respectively, and the orientation direction of the main chain of the resin contained in the retardation film relative to the light transmission axis of the polarizer is within the range of -5° to +5°. Even if the polarizing plate includes a retardation film composed of a single layer, this can also help provide an effect of improving visibility at all viewing angles while minimizing or reducing color changes and reducing light transmittance in black mode at all viewing angles.

[0050] In the retardation film, nx>nz>ny at a wavelength of 550nm. This ensures that nx>ny and 0<(nx-nz) / (nx-ny)<1, thereby reducing changes according to the viewing angle when the retardation film is used, and when the retardation film is applied to a birefringent panel of an optical display device, the contrast or visibility in black and white displays is improved and color changes are reduced.

[0051] According to an embodiment, (nx-ny) may be 0.0022 to 0.0075, for example, 0.0028 to 0.0075, and (nx-nz) may be 0.00044 to 0.0045, for example, 0.00066 to 0.0038. Within the above range, when the retardation film is used, the change according to the viewing angle can be reduced, and when the retardation film is applied to the birefringence panel of the optical display device, the contrast or visibility in the black and white display can be improved and the color change can be reduced.

[0052] According to an embodiment, in the retardation film, nx may be 1.500 to 1.710, such as 1.500, 1.550, 1.600, 1.650, 1.700 or 1.710, such as 1.500 to 1.705, ny may be 1.480 to 1.700, such as 1.480, 1.500, 1.550, 1.600, 1.650 or 1.700, such as 1.485 to 1.700, and nz may be 1.500 to 1.705, such as 1.500, 1.550, 1.600, 1.650, 1.700 or 1.705, such as 1.500 to 1.700. Within the above range, the above ranges of (nx-ny) and (nx-nz) can be easily achieved and can be conducive to the manufacture of the retardation film.

[0053] In an embodiment, the orientation direction of the main chain of the resin contained in the retardation film relative to the light transmission axis of the polarizer is within a range of -5° to +5°. By ensuring that the retardation film is manufactured using the composition for the retardation film to be described below and that the retardation film can satisfy the optical properties to be described below, this can provide an effect of improving visibility at all viewing angles and reducing light transmittance in black mode at all viewing angles.

[0054] According to an embodiment, the orientation direction of the main chain of the resin contained in the retardation film may be in the range of -3° to +3° relative to the light transmission axis of the polarizer, or may be 0°. Within the above range, the above effects can be achieved, and by making the mechanical direction (MD) of the retardation film and the mechanical direction of the polarizer substantially parallel to each other, the processability of manufacturing a roll-to-roll polarizing plate can be improved.

[0055] The orientation direction of the main chain of the resin contained in the delay film can be measured by conventional methods known to those skilled in the art. For example, the orientation direction of the main chain can be determined by visually inspecting the grain orientation of the delay film in the stretching direction. For example, the orientation direction of the main chain can be determined by measuring the crystal structure of the resin in the delay film by X-ray measurement of the delay film, measuring the dynamic structure of the resin in the delay film by nuclear magnetic resonance (NMR) measurement of the delay film, and measuring the orientation direction by Raman and infrared spectroscopy. The light transmission axis of the polarizer may be in the transverse direction of the polarizer.

[0056] When the retardation film is laminated on the polarizer, the angle formed by the orientation direction of the main chain of the resin contained in the retardation film and the light transmission axis of the polarizer may be implemented by adjusting the angle between the main chain direction and the light transmission axis of the polarizer.

[0057] According to an embodiment, the retardation film has a biaxiality of 0.2 to 0.6 at a wavelength of 550 nm. If the biaxiality is less than 0.2, the light transmittance in black mode increases at all viewing angles, resulting in poor black visibility and simultaneous observation of yellow and blue. If the biaxiality is greater than 0.6, the light transmittance in black mode increases at all viewing angles, resulting in poor black visibility and simultaneous observation of yellow and blue. For example, the biaxiality may be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6, such as 0.4 to 0.6, and within the above range, a significantly excellent effect can be achieved.

[0058] According to an embodiment, the retardation film exhibits a value of equation 1 between 0.8 and 1.2 and a range of equation 2 between 0.9 and 1.1, and within these ranges of equation 1 and equation 2, the retardation film can be manufactured using a composition for a retardation film to be described below, and can be used to improve visibility at all viewing angles and reduce light transmittance in black mode at all viewing angles. For example, the value of equation 1 may be 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, or 1.2, such as 0.9 to 1.1, and the value of equation 2 may be 0.9, 0.95, 1.0, 1.05, or 1.1, such as 0.95 to 1.05.

[0059] Equation 1

[0060] Re(450nm) / Re(550nm);

[0061] Equation 2

[0062] Re(650nm) / Re(550nm),

[0063] In Equation 1 and Equation 2, Re(450nm), Re(550nm) and Re(650nm) are the in-plane retardations of the retardation film at wavelengths of 450nm, 550nm and 650nm, respectively (unit: nm).

[0064] According to an embodiment, the delay film may have an in-plane delay of 176nm to 360nm, for example 176nm, 180nm, 185nm, 190nm, 195nm, 200nm, 205nm, 210nm, 215nm, 220nm, 225nm, 230nm, 235nm, 240nm, 245nm, 250nm, 255nm, 260nm, 265nm, 270nm, 275nm, 280nm, 285nm, 290nm, 295nm, 300nm, 305nm, 310nm, 315nm, 320nm, 325nm, 330nm, 335nm, 340nm, 345nm, 350nm, 355nm or 360nm, for example 225nm to 308nm, at a wavelength of 450nm to 650nm. Within the above range, the value of Equation 1 and the value of Equation 2 can be easily obtained, and the light transmittance in the black mode can be reduced at all viewing angles.

[0065] According to an embodiment, the delay film may have an in-plane delay of 220nm to 300nm and a biaxiality of 0.2 to 0.6 at a wavelength of 550nm. Within the above range, the effect of reducing the light transmittance in black mode at all viewing angles can be easily provided. In an embodiment, the in-plane delay of the delay film at a wavelength of 550nm is 220nm, 225nm, 230nm, 235nm, 240nm, 245nm, 250nm, 255nm, 260nm, 265nm, 270nm, 275nm, 280nm, 285nm, 290nm, 295nm or 300nm, such as 250nm to 280nm, and the biaxiality is 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6, such as 0.4 to 0.6. Within the above range, the light transmittance may be significantly reduced to 0.3% or less.

[0066] Figure 3 The figure shows the light transmittance value (Y-axis, unit: %) according to the biaxiality NZ and in-plane retardation (X-axis, unit: nm) of the retardation film at a wavelength of 550 nm when the polarizing plate according to the embodiment is mounted on a panel corresponding to the lateral electric field method (for example, an in-plane switching (IPS) liquid crystal panel) and operated.

[0067] exist Figure 3In the figure, ■ represents the light transmittance when the NZ of the retardation film is 0.4 at a wavelength of 550 nm, ● represents the light transmittance when the NZ of the retardation film is 0.5 at a wavelength of 550 nm, and ▲ represents the light transmittance when the NZ of the retardation film is 0.6 at a wavelength of 550 nm.

[0068] Reference Figure 3 , it can be seen that when the in-plane retardation of the retardation film is in the range of 250nm to 280nm and the biaxiality of the retardation film is in the range of 0.4 to 0.6 at a wavelength of 550nm, the light transmittance is significantly reduced to 0.3% or less.

[0069] The retardation film may be formed of the composition for a retardation film.

[0070] The composition for a retardation film may include a resin and at least one of the following Chemical Formulae I to IV. The composition for a retardation film may contribute to achieving the above-mentioned optical properties.

[0071] The resin is a cellulose ester resin, and the resin is contained as a main component of the retardation film. Here, the term "main component" may mean the case where the resin is contained in an amount of 70 wt % or more, for example, 75 wt % to 99 wt % or 80 wt % to 99 wt % based on the solid content of the retardation film or the composition for the retardation film.

[0072] The cellulose ester resin may include a plurality of aromatic -CO- groups, a plurality of first unsaturated or saturated (C 1-6 ) cellulose ester resin selectively substituted with alkyl-CO- groups and multiple hydroxyl groups.

[0073] In the present invention, "aromatic -CO-" can be (i) (C 6-20 ) aryl-CO-, wherein the aryl group is unsubstituted or has 1 to 5 R 1 or (ii) heteroaryl-CO-, wherein heteroaryl is a 5- to 10-membered ring having 1 to 4 heteroatoms selected from N, O and S, and heteroaryl is unsubstituted or has 1 to 5 R 1 Replace. 1 Following are the definitions that will be explained below.

[0074] According to an embodiment, the position-selectively substituted cellulose ester resin may include a plurality of alkyl-acyl or alkyl-CO- groups, a plurality of aryl-acyl or aryl-CO- groups, and a plurality of heteroaryl-acyl or heteroaryl-CO- groups.

[0075] The acyl substituent or R-CO- shall represent a substituent having the following structure.

[0076]

[0077] Such acyl or R-CO- groups in cellulose esters are typically bonded to the pyranose ring of cellulose through an ester bond (ie, through an oxygen atom).

[0078] The aromatic -CO- may be an acyl substituent substituted with an aromatic-containing ring system. Examples thereof may include aryl-CO- or heteroaryl-CO-. Specific examples include benzoyl, naphthoyl, and furanoyl, each of which is unsubstituted or substituted.

[0079] The term "aryl-acyl" substituent shall mean an acyl substituent where "R" is an aryl group. The term "aryl" shall mean a monovalent group formed by removing a hydrogen atom from a ring carbon in an arene (i.e., a monocyclic or polycyclic aromatic hydrocarbon). In certain instances, the aryl-acyl group precedes the carbon unit: for example (C 5-6 ) aryl-acyl, (C 6-12 ) aryl-acyl or (C 6-20 ) aryl-acyl. Examples of aryl groups suitable for use in various aspects include phenyl, benzyl, tolyl, xylyl and naphthyl, but the present invention is not limited thereto. Such aryl groups may be substituted or unsubstituted.

[0080] The term "alkyl-acyl" shall mean an acyl substituent where "R" is an alkyl group. The term "alkyl" means a monovalent group formed by removing a hydrogen atom from a non-aromatic hydrocarbon, and may include heteroatoms. Alkyl groups suitable for use herein may be linear, branched, or cyclic, and may be saturated or unsaturated. Alkyl groups suitable for use herein include any (C 1-20 ) alkyl, (C 1-12 ) alkyl, (C 1-5 ) alkyl or (C 1-3 In various aspects, the alkyl group may be C 1-5 In another aspect, the alkyl group may be C 1-3 Straight chain alkyl. Specific examples of suitable alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl, cyclopentyl and cyclohexyl. Examples of alkyl-acyl groups include acetyl, propionyl, butyroyl, etc.

[0081] The term "haloalkyl" refers to an alkyl substituent in which at least one hydrogen is replaced by a halogen group. The carbon units in the haloalkyl group are generally included, for example, halo (C 1-6 ) alkyl. The haloalkyl group may be straight chain or branched. Non-limiting examples of haloalkyl groups include chloromethyl, trifluoromethyl, dibromoethyl, and the like.

[0082] The term "heteroalkyl" refers to an alkyl group in which one or more carbon atoms are replaced with a heteroatom such as, for example, N, O, and S.

[0083] The term "heteroaryl" means an aryl group in which one or more of the carbon units in the aryl ring are replaced by heteroatoms (e.g., O, N, or S). The heteroaryl ring may be monocyclic or polycyclic. Typically, the units constituting the heteroaryl ring system include, for example, a five-membered to twenty-membered ring system. A five-membered heteroaryl is a ring system having five atoms forming a heteroaryl ring. Non-limiting examples of heteroaryls include pyridine, quinoline, pyrimidine, thienyl, etc.

[0084] The term "alkoxy" means an alkyl-O- or an alkyl group attached to an oxy group at the terminal end. Typically, it comprises a carbon unit, such as (C 1-6 ) alkoxy. Non-limiting examples of alkoxy include methoxy, ethoxy, propoxy, and the like.

[0085] The term "haloalkoxy" refers to an alkoxy group in which one or more hydrogen atoms are replaced by halogen atoms. 1-6 Non-limiting examples of haloalkoxy include trifluoromethoxy, bromomethoxy, 1-bromo-ethoxy, and the like.

[0086] The term "halo" refers to a halogen such as fluoro, chloro, bromo or iodo.

[0087] The term "degree of substitution (DS)" is used to describe the substitution level of substituents among the substituents of each anhydroglucose unit ("anhydroglucose unit, AGU"). In general, conventional cellulose includes three hydroxyl groups that can be substituted in each AGU. Therefore, DS can have a value between 0 and 3. However, low molecular weight cellulose mixed esters can have a total degree of substitution slightly higher than 3 due to end group contribution. Since DS is a statistical average, a value of 1 does not ensure that each AGU has a single substituent. In some cases, there may be unsubstituted anhydroglucose units, some anhydroglucose units have two substituents, some anhydroglucose units have three substituents, and more often the value is not an integer. The total DS is defined as the average of all substituents in each anhydroglucose unit. The degree of substitution of each AGU can also refer to a specific substituent, such as, for example, a hydroxyl, acetyl, butyryl or propionyl. In addition, the degree of substitution can indicate the carbon unit of the anhydroglucose unit.

[0088] When the degree of substitution refers to the hydroxyl group (ie DS OH), the reference value refers to the average number of unsubstituted hydroxyl groups per glucose anhydride. Therefore, DS is not used in calculating the total degree of substitution. OH .

[0089] Position selectivity can be measured by determining the relative degree of substitution (RDS) at C6, C3, and C2 in the cellulose ester by carbon 13 NMR spectroscopy (reference: [Macromolecules, 1991, 24, 3050-3059]). In the case where one type of acyl substituent is present or when the second acyl substituent is present in a small amount (DS < 0.2), the RDS can be most easily measured directly by integration of the ring carbons. When two or more acyl substituents are present in similar amounts, in addition to determining the ring RDS, it is sometimes necessary to completely replace the cellulose ester with additional substituents in order to independently determine the RDS of each substituent by integration of the carbonyl carbon. In conventional cellulose esters, position selectivity is generally not observed, and the RDS ratios of C6 / C3, C6 / C2, or C3 / C2 are generally close to 1 or less than 1. In essence, conventional cellulose esters are random copolymers. In contrast, when one or more acylating agents are added to cellulose dissolved in a suitable solvent, the C6 position of the cellulose is acylated much faster than the C2 and C3 positions. Thus, the C6 / C3 ratio and the C6 / C2 ratio are significantly greater than 1, which is a characteristic of 6,3- or 6,2-enhanced positionally selectively substituted cellulose esters.

[0090] According to an embodiment, cellulose esters generally include the following structure:

[0091]

[0092] Where R 2 , R 3 and R 6 is hydrogen (assuming R 2 , R 3 and R 6 are not hydrogen at the same time) and / or an alkyl-acyl group and / or an aryl-acyl group bonded to cellulose through an ester bond, and n is an integer greater than or equal to 1.

[0093] The cellulose esters prepared by these methods may have a degree of polymerization ("degree of polymerization, DP") greater than or equal to 10, greater than or equal to 50, greater than or equal to 100, or greater than or equal to 250.

[0094] Suitable acylating agents for use herein may include alkyl or aryl carboxylic acid anhydrides, carboxylic acid halides and / or carboxylic acid esters containing the above alkyl or aryl groups, which are suitable for use in the acyl substituents of the position-selectively substituted cellulose esters described herein, but the present invention is not limited thereto. Examples of suitable carboxylic acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, pivaloyl anhydride, benzoic anhydride and naphthoyl anhydride, but the present invention is not limited thereto. Examples of carboxylic acid halides include acetyl, propionyl, butyryl, pivaloyl, benzoyl and naphthoyl chlorides or bromides, but the present invention is not limited thereto. Examples of carboxylic acid esters include acetyl, propionyl, butyryl, pivaloyl, benzoyl and naphthoyl methyl esters, but the present invention is not limited thereto. In one or more aspects, the acylating agent can be one or more carboxylic anhydrides selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, pivaloyl anhydride, benzoyl anhydride, and naphthoyl anhydride.

[0095] The cellulose ester resin may include a plurality of aromatic -CO- groups, a plurality of first unsaturated or saturated (C 1-6 ) A cellulose ester resin selectively substituted with an alkyl-CO- group and a plurality of hydroxyl groups.

[0096] According to an embodiment, the cellulose ester resin has a hydroxyl substitution degree of 0.2 to 2.0, a C2 substitution degree of 0.15 to 0.8, a C3 substitution degree of 0.05 to 0.6, a C6 substitution degree of 0.05 to 0.6, and a total substitution degree of 0.25 to 2.5.

[0097] According to an embodiment, the cellulose ester resin has a hydroxyl substitution degree of 0.2 to 2.0, a C2 substitution degree of an aromatic-CO group or an alkyl-CO group of 0.15 to 0.8, a C3 substitution degree of an aromatic-CO group or an alkyl-CO group of 0.05 to 0.6, a C6 substitution degree of an aromatic-CO group or an alkyl-CO group of 0.05 to 0.6, and a total substitution degree of an aromatic-CO group or an alkyl-CO group of 0.25 to 2.5.

[0098] Cellulose ester resin has a first unsaturated or saturated 1-6 ) The degree of substitution (“DS FAk ”) may be 0.7 to 2.2. In one aspect, the cellulose ester resin has a first unsaturated or saturated (C 1-6 )The degree of substitution of the alkyl-acyl substituents may be from 0.7 to 1.9.

[0099] In one class of this aspect, the first unsaturated or saturated (C 1-20The alkyl-CO- substituent is acetyl, propionyl, butyryl, isobutyryl, 3-methylbutyryl, pentanoyl, 4-methylpentanoyl, 3-methylpentanoyl, 2-methylpentanoyl, hexanoyl or crotonyl. In one class of this aspect, the first unsaturated or saturated (C 1-6 ) The alkyl-CO- substituent is acetyl, propionyl or crotonyl.

[0100] In one aspect or in combination with any other aspect, the cellulose ester resin may further include a plurality of second (C 1-20 )alkyl-CO-substituent. In one class of this aspect, the second (C 1-20 ) The degree of substitution (“DS SAk ”) is in the range of 0.05 to 0.6.

[0101] In one category of this aspect, the second (C 1-20 The alkyl-CO-substituent is acetyl, propionyl, butyryl, isobutyryl, 3-methylbutyryl, valeryl, 4-methylvaleryl, 3-methylvaleryl, 2-methylvaleryl, hexanoyl, pivalil or 2-ethylhexanoyl. In a class of this aspect, the second (C 1-20 The alkyl-CO-substituent is acetyl, isobutyryl, 3-methylbutyryl, valeryl, 4-methylvaleryl, 3-methylvaleryl, 2-methylvaleryl, hexanoyl or 2-ethylhexanoyl. In one class of this aspect, the second (C 1-20 ) The alkyl-CO- substituent is acetyl or 2-ethylhexanoyl.

[0102] In one aspect or in combination with any other aspect, the aromatic -CO- is (C 6-20 ) aryl-CO-, wherein the aryl group is unsubstituted or has 1 to 5 R 1 In one class of this aspect, the aromatic -CO- is unsubstituted or has 1 to 5 R 1 In one class of this aspect, the aromatic -CO- is unsubstituted or has 1 to 5 R 1 In one class of this aspect, the aromatic -CO- is unsubstituted or has 1 to 5 R 1 Substituted naphthoyl.

[0103] In one aspect or in combination with any other aspect, the aromatic -CO- is unsubstituted or is substituted with R 1 In one class of this aspect, the total DS of the cellulose ester is ArCO 0.4 to 1.2. In this category, C3DS ArCO With C3DS ArCOThe sum is in the range of 0.30 to 0.75.

[0104] In one aspect or in combination with any other aspect, the aromatic -CO- is unsubstituted or has 1-5 R 1 In one class of this aspect, the total DS of the cellulose ester is ArCO 0.30 to 0.6. In this category, C3DS ArCO With C3DS ArCO The sum is in the range of 0.20 to 0.40. In the subcategories of this category, C3DS ArCO With C3DS ArCO The sum is in the range of 0.30 to 0.40.

[0105] In one aspect or in combination with any other aspect, aromatic -CO- is heteroaryl-CO-, wherein heteroaryl is a five- to ten-membered ring having 1 to 4 heteroatoms selected from N, O and S, and heteroaryl is unsubstituted or has 1 to 5 R 1 In a class of this aspect, heteroaryl-CO- is pyridine-CO-, pyrimidine-CO-, furanyl-CO- or pyrrolyl-CO-. In a class of this aspect, heteroaryl-CO- is 2-furoyl.

[0106] In one aspect or in combination with any other aspect, the cellulose ester has a total DS of 0.2 to 1.6 ArCO (totDS ArCO ). In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 1.0 to 1.6 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.3 to 1.25 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.4 to 1.2 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.4 to 0.8 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.3 to 0.8 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.3 to 0.6 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.2 to 0.6 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.2 to 0.5 ArCO In one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.8 to 1.2 ArCOIn one aspect or in combination with any other aspect, the cellulose ester has a totDS of 0.5 to 1.1 ArCO .

[0107] In one aspect or in combination with any other aspect, DS OH In one aspect or in combination with any other aspect, DS OH In one aspect or in combination with any other aspect, DS OH In one aspect or in combination with any other aspect, DS OH In one aspect or in combination with any other aspect, DS OH In one aspect or in combination with any other aspect, DS OH In one aspect or in combination with any other aspect, DS OH In the range of 0.5 to 0.8.

[0108] In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.2 to 1.25. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.2 to 0.4. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.3 to 0.4. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.4 to 1.2. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.4 to 1.1. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.4 to 1.0. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.5 to 1.1. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.6 to 1.0. In one aspect or in combination with any other aspect, C2DSArCO With C3DS ArCO The sum is in the range of 0.6 to 1.25. In one aspect or in combination with any other aspect, C2DS ArCO With C3DS ArCO The sum is in the range of 0.30 to 0.75.

[0109] The composition for a retardation film (that is, a retardation film) may include a component A having at least one of Formula I to Formula IV:

[0110] Chemical formula I

[0111]

[0112] Wherein, in Chemical Formulae I to IV, Ring A is (C 6-20 ) aryl or a five- to ten-membered heteroaryl group containing 1 to 4 heteroatoms selected from N, O or S; Ring B is (C 6-20 )aryl or a five- to ten-membered heteroaryl group containing 1 to 4 heteroatoms selected from N, O or S; Ring C is (C 6-20 ) aryl or a 5- to 10-membered heteroaryl group containing 1 to 4 heteroatoms selected from N, O or S; R 1 Saturated or unsaturated (C 1-20 ) alkyl; saturated or unsaturated halogenated (C 1-20 ) alkyl; (C 6-20 ) aryl; a five- to ten-membered heteroaryl group containing 1 to 4 heteroatoms selected from N, O or S; or -CH2C(O)-R 3 ; R 2 are independently hydrogen, saturated or unsaturated (C 1-20 ) alkyl, or saturated or unsaturated halogenated (C 1-20 ) alkyl; R 3 Saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, (C 6-20 ) aryl or a five- to ten-membered heteroaryl group containing 1 to 4 heteroatoms selected from N, O or S, wherein the aryl or heteroaryl group is unsubstituted or consists of 1 to 5 R 6 Replacement; R 4 Saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, or saturated or unsaturated (C 1-20 )alkyl-CO-(C 1-20 ) alkyl, each of which is unsubstituted or substituted with: 1 to 3 hydroxyl groups, saturated or unsaturated (C 1-20) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halogenated (C 1-20 ) alkoxy, saturated or unsaturated hydroxyl (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy-hydroxy (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-CO-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkyl-CO, saturated or unsaturated (C 1-20 )alkyl-COO, saturated or unsaturated (C 1-20 )alkyl-O-CO-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkyl-COO-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-COO-(C 1-20 ) alkyl or (C 1-20 )alkoxy-(C 1-20 )alkyl-O-CO-(C 1-20 ) alkyl; each R 5 are independently hydroxyl, cyano, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halogenated (C 1-20 ) alkoxy or halogen; each R 6 are independently hydroxyl, cyano, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halogenated (C 1-20 ) alkoxy or halogen or (C 6-20 ) aryl, wherein aryl is unsubstituted or has 1 to 5 R 7 Replace; each R 7 are independently hydroxyl, saturated or unsaturated (C 1-6 ) alkyl, saturated or unsaturated halogenated (C 1-6 ) alkyl or saturated or unsaturated (C 1-6 ) alkoxy; R 8Saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, or saturated or unsaturated halogen (C 1-20 ) alkoxy; each R 9 For R 4 -O-, hydroxyl, saturated or unsaturated (C 1-20 ) alkyl, a saturated or unsaturated hetero(C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkyl-CO-(C 1-20 ) alkyl-, saturated or unsaturated (C 1-20 )alkyl-COO-(C 1-20 ) alkyl-, saturated or unsaturated (C 1-20 )alkyl-COO-, saturated or unsaturated (C 1-20 )alkyl-O-CO-, saturated or unsaturated (C 1-20 )alkyl-CO-, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-CO-O-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-O-CO-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-COO-(C 1-20 ) alkyl, (C 1-20 )alkoxy-(C 1-20 )alkyl-O-CO-(C 1-20 )alkyl-(C 6-10 )aryl, or a five- to ten-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O and S, each of which is unsubstituted or substituted with: 1 to 3 hydroxyl groups, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halogenated (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halogenated (C 1-20 ) alkoxy, saturated or unsaturated hydroxyl (C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy-hydroxy (C 1-20) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-CO-(C 1-20 ) alkyl-, saturated or unsaturated (C 1-20 )alkyl-CO, saturated or unsaturated (C 1-20 )alkyl-COO, saturated or unsaturated (C 1-20 )alkyl-O-CO-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkyl-COO-(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 )alkoxy-(C 1-20 )alkyl-COO-(C 1-20 ) alkyl, or (C 1-20 )alkoxy-(C 1-20 )alkyl-O-CO-(C 1-20 )alkyl; each n is 0, 1, 2, 3, 4 or 5; each m is 0, 1, 2, 3 or 4; and k is 0, 1, 3 or 4.

[0113] According to an embodiment, component A may be 1,3-diphenyl-1,3-propanedione, avobenzone, (2-hydroxy-4-(octyloxy)phenyl)(phenyl)methanone, (2-hydroxy-4-methoxyphenyl)(2-hydroxyphenyl)methanone, 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-(hexyloxy)phenol (Tinuvin 1577), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-[2-hydroxy-3-(dodecyloxy and tridecyloxy)propoxy]phenol (Tinuvin 4 00), 2-(4-(4,6-di([1,1'-biphenyl]-4-yl)-1,3,5-triazine-2-yl)-3-hydroxyphenoxy) propionate (Tianlaiwen 479), 6,6'-(6-(2,4-dibutoxyphenyl)-1,3,5-triazine-2,4-diyl)bis(3-butoxyphenol) (Tianlaiwen 460), 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-(3-((2-ethylhexyl)oxy)-2-hydroxypropoxy)phenol (Tianlaiwen 405), 7-diethylamino-4-methylcoumarin or a combination thereof.

[0114] According to an embodiment, component A may be present in an amount greater than 1 wt %. In one class of this aspect, component A may be present in a range of 1 wt % to 30 wt %. In one class of this aspect, component A may be present in a range of 1 wt % to 20 wt %. In one class of this aspect, component A may be present in a range of 1 wt % to 15 wt %. Within the above range, the effects of the present invention can be easily implemented.

[0115] In an embodiment, the composition for the delay film may further include a plasticizer to increase the processability and flexibility of the delay film. In an embodiment, the plasticizer may be included in an amount of 0.1 wt % to 10 wt % (e.g., 0.1 wt % to 5 wt %) based on the solid content of the delay film or the composition for the delay film. Within the above range, the glass transition temperature and melting temperature of the material in which the delay film is formed can be reduced, thereby enabling lower temperature and / or simplified film manufacturing.

[0116] The plasticizer may be selected from phosphate-type plasticizers, phthalate-type plasticizers, terephthalate-type plasticizers, trimelitate-type plasticizers, benzoate-type plasticizers, glycolate-type plasticizers, citrate-type plasticizers, polyol ester-type plasticizers, polyol-type plasticizers or polyester-type plasticizers.

[0117] Non-limiting examples of glycolate plasticizers can include methylphthaloyl methyl glycolate, ethylphthaloyl ethyl glycolate, propylphthaloyl propyl glycolate, butylphthaloyl butyl glycolate, octylphthaloyl octyl glycolate, methylphthaloyl ethyl glycolate, ethylphthaloyl methyl glycolate, ethylphthaloyl propyl glycolate, methylphthaloyl butyl glycolate, ethylphthaloyl butyl glycolate, butylphthaloyl methyl glycolate, butylphthaloyl ethyl glycolate, propylphthaloyl butyl glycolate, butylphthaloyl propyl glycolate, methylphthaloyl octyl glycolate, ethylphthaloyl octyl glycolate, octylphthaloyl methyl glycolate, and octylphthaloyl ethyl glycolate.

[0118] The delay film may be manufactured by solution casting and stretching the composition for the delay film. According to an embodiment, the delay film may be manufactured by preparing a casting solution using the composition for the delay film itself or adding a solvent to the composition for the delay film, applying the casting solution to a base substrate and drying it to prepare an unstretched film, and stretching the unstretched film in the transverse direction (TD) of the unstretched film.

[0119] In an embodiment, during the manufacture of an unstretched film, the orientation direction of the main chain of the resin contained in the retardation film can be adjusted by adjusting the viscosity of the composition for the retardation film, the concentration of the resin in the composition for the retardation film, and the stretching direction and stretching ratio of the unstretched film.

[0120] In an embodiment, the slow axis of the retardation film may be in a range of -5° to +5° (eg, -3° to +3°) relative to the light absorption axis of the polarizer, or may be 0°. Within the above range, the effects of the present invention may be easily implemented.

[0121] In embodiments, the slow axis of the retardation film may be substantially parallel to the machine direction of the retardation film.

[0122] The polarizer may convert incident natural light or polarized light into linear polarized light in a specific direction. In an embodiment, the polarizer may have a thickness of 2 μm to 30 μm, and in an embodiment may have a thickness of 4 μm to 25 μm, and may be used for a polarizing plate within the above range.

[0123] The polarizer can be manufactured from a film including a polyvinyl alcohol resin as a main component by a conventional method known to those skilled in the art. For example, the polarizer can be a polarizer manufactured by iodine dyeing and stretching. The polarizer has a light absorption axis and a light transmission axis orthogonal to the light absorption axis in the in-plane direction, and the light absorption axis can be MD, and the light transmission axis can be TD.

[0124] In an embodiment, the polarizing plate may further include one or more upper protective layers on the upper surface of the polarizer.

[0125] The upper protective layer may include one or more of an optically transparent protective coating and an optically transparent protective film. The protective coating may include a coating formed of a composition comprising an actinic radiation curable compound. The protective film is an optically transparent film and may include a film formed of at least one selected from, for example, a cellulose resin including triacetyl cellulose (TAC), a polyester resin including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., a cyclic polyolefin resin, a polycarbonate resin, a polyether sulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, a polyolefin resin, a polyarylate resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, and a polyvinylidene chloride resin. In an embodiment, a TAC film or a PET film may be used.

[0126] In an embodiment, the upper protective layer may have a thickness of 0.1 μm to 100 μm, and in one embodiment may have a thickness of 5 μm to 70 μm, and in one embodiment may have a thickness of 15 μm to 45 μm, and may be used for a polarizing plate within the above range.

[0127] The upper protective layer may be adhered to an adherend through an adhesive layer. The upper protective layer may be omitted when omitting the upper protective layer does not impair the function of the polarizing plate.

[0128] The polarizing plate may further include a photosensitive adhesive layer on its lowermost surface. The photosensitive adhesive layer may adhere the polarizing plate to the panel. The photosensitive adhesive layer may be formed of a photosensitive adhesive composition known to those skilled in the art.

[0129] Reference Figure 1 The polarizing plate may include a polarizer 100 , an upper protective layer 300 stacked on an upper surface of the polarizer 100 , and a retardation film 200 stacked on a lower surface of the polarizer 100 .

[0130] Reference Figure 2 The polarizing plate may include a polarizer 100 , an upper protective layer 300 stacked on an upper surface of the polarizer 100 , and a retardation film 200 and a lower protective layer 400 sequentially stacked on a lower surface of the polarizer 100 .

[0131] Optical display device

[0132] According to an embodiment, an optical display device includes the polarizing plate. The optical display device may include a liquid crystal display device. The polarizing plate may be included in the optical display device as a viewer-side polarizing plate. In an embodiment, the liquid crystal display device is a horizontal alignment mode liquid crystal display device, such as an in-plane switching (IPS) mode, a fringe field switching (FFS) mode, an advanced super dimensions switching (ADS) mode, or a plane to lineswitching (PLS) mode liquid crystal display device.

[0133] According to an embodiment, a liquid crystal display device may include a liquid crystal panel, a viewer-side polarizing plate located on a side surface of the liquid crystal panel, and a light source-side polarizing plate located on another side surface of the liquid crystal panel. The light absorption axis of the polarizer of the viewer-side polarizing plate may be substantially orthogonal to the light absorption axis of the light source-side polarizing plate. When the light absorption axis of the polarizer of the viewer-side polarizing plate is 0°, the light absorption axis of the light source-side polarizing plate may be 90°, and the rubbing direction of the liquid crystal in the liquid crystal panel may be 90°. The viewer-side polarizing plate may include the polarizing plate according to the above-described embodiment.

[0134] Herein, the configuration and operation of the present invention will be further described in detail through some examples of the present invention. However, it should be understood that these examples are provided as examples of the present invention and should not be interpreted as limiting the scope of the present invention in any way.

[0135] Example 1

[0136] An unstretched film was prepared by a solution casting method using a composition for a delay film (Eastman Chemical Ltd.), wherein the composition for a delay film includes a position-selectively substituted cellulose ester resin (propionyl substitution degree of C2 is 0.26, propionyl substitution degree of C3 is 0.34, propionyl substitution degree of C6 is 0.53, total propionyl substitution degree is 2.33, and hydroxyl substitution degree is 1.87). The unstretched film was stretched at a stretch ratio of 1.5 in the transverse direction of the prepared unstretched film to prepare a delay film (in-plane retardation is 270nm, biaxiality is 0.4, thickness is 56μm, and at a wavelength of 550nm, nx=1.5323, ny=1.5275, and nz=1.5304).

[0137] A polyvinyl alcohol film (TS#20, Kuraray Co., Ltd., thickness before stretching: 20 μm) was stretched six times along the MD axis in an aqueous solution at 55° C., thereby preparing a polarizer having a total light transmittance of 45%.

[0138] A polyethylene terephthalate (PET) film having an antireflection layer formed thereon is laminated on the upper surface of the prepared polarizer, and the prepared retardation film is laminated on the lower surface of the polarizer, thereby manufacturing a polarizing plate. In the manufactured polarizing plate, an angle formed by the main chain direction of the cellulose ester resin selectively substituted in the retardation film relative to the light transmission axis of the polarizer (lateral direction of the polarizer) is 0°.

[0139] Example 2 to Example 6

[0140] A polarizing plate was manufactured in the same manner as in Example 1 except that a site-selectively substituted cellulose ester resin having a substitution degree changed compared with that in Example 1 was used and the stretching ratio was changed.

[0141] Comparative Examples 1 to 4

[0142] A polarizing plate was manufactured in the same manner as in Example 1, except that the in-plane retardation and / or biaxiality and / or stretch ratio of the retardation film in Example 1 were changed.

[0143] The following physical properties were evaluated using the polarizing plates of Examples and Comparative Examples, and the results are shown in Table 1 below.

[0144] (1) Optical properties of retardation film: The optical properties of the retardation film were measured using AxoScan.

[0145] (2) Angle: The angle of the main chain direction of the cellulose ester resin in the delay film relative to the light transmission axis of the polarizer in the polarizing plate is obtained by measuring the light transmission axis of the polarizer using AxoScan when the polarizer and the delay film are separated from each other, measuring the main chain direction of the cellulose ester resin by an X-ray diffraction (X-RD) method, and then calculating the relative angle.

[0146] (3) Maximum light transmittance (unit: %): The polarizing plate manufactured in the examples and comparative examples was attached to a Samsung Electronics TV model with an IPS liquid crystal panel instead of the viewer-side polarizing plate, and the polarizing plate was driven. In addition, the maximum light transmittance in black mode was calculated at all viewing angles based on the TechWiz 1D (Sanayi System, South Korea) simulation program. However, the reduction in light transmittance caused by the color filter inside the panel was excluded in the above calculation. This means that since the maximum light transmittance is low, light leakage can be prevented and visibility can be improved.

[0147] (4) Black visibility and color: The polarizing plates manufactured in the examples and comparative examples were attached to a Samsung Electronics TV model having an IPS liquid crystal panel instead of a viewer-side polarizing plate, and the polarizing plates were driven. In addition, black visibility and color were evaluated using a visual evaluation method.

[0148] Table 1

[0149]

[0150] The retardation films of the examples and comparative examples satisfy the relationship of nx>nz>ny at a wavelength of 550 nm.

[0151] As shown in Table 1, the polarizing plate of the present invention includes a retardation film composed of a single layer, thereby improving visibility at all viewing angles, minimizing or reducing color changes, and reducing the maximum light transmittance in black mode at all viewing angles to provide a light leakage improvement effect. On the other hand, as shown in Table 1, the polarizing plate of the comparative example having a retardation film that does not satisfy the optical properties of the present invention has the above effects lower than those of the example.

[0152] Although some exemplary embodiments of the present invention have been described herein, it should be understood that modifications or changes may be easily made by those skilled in the art, and therefore such modifications or changes should be construed as being included within the scope of the present invention.

Claims

1. A polarizing plate, include: polarizer; as well as a retardation layer, laminated on the surface of the polarizer, wherein the retardation layer comprises a retardation film satisfying the relationship nx>nz>ny, wherein nx, ny and nz are the refractive indices of the retardation film in the slow axis direction, the fast axis direction and the thickness direction of the retardation film at a wavelength of 550 nm, respectively, The orientation direction of the main chain of the resin contained in the retardation film is within the range of -5° to +5° with respect to the light transmission axis of the polarizer, and The retardation film has a biaxiality of 0.2 to 0.6 at a wavelength of 550 nm. 2 . The polarizing plate according to claim 1 , wherein the retardation film is a retardation film composed of a single layer. 3 . The polarizing plate according to claim 1 , wherein the retardation film has an in-plane retardation of 220 nm to 300 nm at a wavelength of 550 nm.

4. The polarizing plate according to claim 1, wherein in the retardation film, a value of the following equation 1 is in the range of 0.8 to 1.2, and a value of the following equation 2 is in the range of 0.9 to 1.1, Equation 1 Re(450nm) / Re(550nm); Equation 2 Re(650nm) / Re(550nm), In Equation 1 and Equation 2, Re(450nm), Re(550nm) and Re(650nm) are the in-plane retardation of the retardation film at wavelengths of 450nm, 550nm and 650nm, respectively, and the unit of the in-plane retardation is nm. 5 . The polarizing plate according to claim 1 , wherein a slow axis of the retardation film is within a range of −5° to +5° with respect to a light absorption axis of the polarizer. The polarizing plate according to claim 1 , wherein a slow axis of the retardation film is parallel to a machine direction of the retardation film. 7 . The polarizing plate according to claim 1 , wherein the retardation film is a retardation film stretched in a transverse direction.

8. The polarizing plate according to claim 1, wherein (nx-ny) is in the range of 0.0022 to 0.0075, and (nx-nz) is in the range of 0.00044 to 0.0045.

9. The polarizing plate according to claim 1, wherein nx is in the range of 1.500 to 1.710, ny is in the range of 1.480 to 1.700, and NZ is in the range of 1.500 to 1.

705. 10 . The polarizing plate according to claim 1 , wherein the resin is a main component of the retardation film. 11 . The polarizing plate according to claim 1 , wherein the resin is a cellulose ester resin.

12. The polarizing plate according to claim 11, wherein the cellulose ester resin comprises a plurality of aromatic -CO- groups, a plurality of first unsaturated or saturated (C 1-6 ) A cellulose ester resin in which an alkyl-CO- group and a plurality of hydroxyl groups are selectively substituted.

13. The polarizing plate according to claim 12, wherein in the cellulose ester resin, The degree of hydroxyl substitution is in the range of 0.2 to 2.0, The C2 substitution degree is in the range of 0.15 to 0.8, The C3 substitution degree is in the range of 0.05 to 0.6, The C6 substitution degree is in the range of 0.05 to 0.6, and The total degree of substitution is in the range of 0.25 to 2.

5. 14 . The polarizing plate according to claim 1 , wherein the retardation layer is formed of only the retardation film. 15 . The polarizing plate according to claim 1 , wherein the retardation film has a thickness of 40 μm to 100 μm. 16 . The polarizing plate according to claim 1 , further comprising a protective layer laminated on the other surface of the polarizer.

17. An optical display device comprising the polarizing plate according to claim 1.

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