Polarizing plate and optical display device having the same

Abstract

To provide a polarizing plate which has a single-layer retardation film and offers improved visibility across all azimuths and minimized color changes.SOLUTION: A polarizing plate disclosed herein comprises a polarizer and a retardation layer laminated on one surface of the polarizer. The retardation layer includes a retardation film satisfying a condition expressed as nx>nz>ny at a wavelength of 550 nm, (where nx, ny, and nz respectively represent a refractive index of the retardation film in a slow axis direction, a refractive index of the retardation film in a fast axis direction, and a refractive index of the retardation film in a thickness direction at a wavelength of 550 nm). An orientation direction of a main chain of a resin contained in the retardation film is in a range of -5° to +5° relative to a light absorption axis of the polarize. The retardation film has a degree of biaxiality in a range of 0.3 to 0.7 at a wavelength of 550 nm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims priority from Korean Patent Application No. 10-2023-086333, filed with the Korean Intellectual Property Office on July 4, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] Technical Field The present application relates to a polarizing plate and an optical display device including the same. [Background technology]

[0003] An LCD device includes a liquid crystal panel as an optical display panel, a viewer-side polarizing plate laminated on the upper surface of the liquid crystal panel, and a light source-side polarizing plate laminated on the lower surface of the liquid crystal panel. Among the driving methods of the LCD panel, the in-plane electric field method is a method in which the liquid crystal compound responds in the in-plane direction of the substrate by an electric field including a component approximately parallel to the substrate surface of the LCD panel. The in-plane electric field method includes the IPS and FFS methods. The in-plane electric field method can widen the contrast ratio and viewing angle and minimize color change by providing a retardation layer between the liquid crystal panel and the polarizer.

[0004] According to one embodiment, the retardation layer can be a laminate of a retardation layer of a +C layer and a +A layer. For example, the polarizing plate can be laminated in the order of a polarizer, a +C layer, an adhesive layer, and a +A layer. However, such a polarizing plate has two retardation layers, a +C layer and a +A layer. Therefore, in order to provide the effect of making the polarizing plate thinner, it is preferable to make the retardation layer a single layer.

[0005] The background art of the present invention is disclosed in Korean Patent Publication No. 2013-0103595 and the like. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a polarizing plate that includes a single-layer retardation film, improves visibility at all azimuth angles, and minimizes color change.

[0007] An object of the present invention is to provide a polarizing plate that includes a single-layer retardation film and has reduced light transmittance at all azimuth angles.

[0008] An object of the present invention is to provide a polarizing plate which includes a single-layer retardation film and is excellent in terms of the effect of reducing the thickness.

[0009] An object of the present invention is to provide a polarizing plate which has a single-layer retardation film and can be produced by roll-to-roll production. [Means for solving the problem]

[0010] According to one embodiment of the present invention, a polarizing plate is provided.

[0011] The polarizing plate includes a polarizer and a retardation layer laminated on one surface of the polarizer, the retardation layer includes a retardation film having nx>nz>ny (nx, ny, and nz are the refractive indexes of the retardation film in the slow axis direction, the fast axis direction, and the thickness direction at a wavelength of 550 nm, respectively) in which the orientation direction of the main chain of the resin contained in the retardation film forms an angle of -5° to +5° with respect to the light absorption axis of the polarizer, and the retardation film has a degree of biaxiality of 0.3 to 0.7 at a wavelength of 550 nm.

[0012] According to one embodiment of the present invention, an optical display device includes the polarizing plate. Effect of the Invention

[0013] According to an embodiment of the present invention, there is provided a polarizing plate having a single-layer retardation film, which improves visibility at all azimuth angles and minimizes color change.

[0014] According to one embodiment of the present invention, there is provided a polarizing plate having a single-layer retardation film and reduced light transmittance at all azimuth angles.

[0015] According to one embodiment of the present invention, there is provided a polarizing plate which includes a single-layer retardation film and has an excellent effect of reducing the thickness.

[0016] According to one embodiment of the present invention, there is provided a polarizing plate having a single-layer retardation film and capable of being produced by roll-to-roll production. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention. [Diagram 2] FIG. 4 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention. [Diagram 3] This is a diagram showing the in-plane retardation (X-axis, unit: nm) and light transmittance (Y-axis, unit: %) at a wavelength of 550 nm according to the degree of biaxiality (NZ) of the retardation film at a wavelength of 550 nm when a polarizing plate according to one embodiment of the present invention is mounted and driven in a lateral electric field mode. In Fig. 3, ■ represents the light transmittance when the retardation film has an NZ of 0.4 at a wavelength of 550 nm, ● represents the light transmittance when the retardation film has an NZ of 0.5 at a wavelength of 550 nm, and ▲ represents the light transmittance when the retardation film has an NZ of 0.6 at a wavelength of 550 nm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the invention. The present invention may, however, be embodied in various different forms and is not limited to the embodiments set forth herein.

[0019] In order to clearly explain the present invention in the drawings, parts that are not relevant to the explanation are omitted, and the same or similar components are designated by the same reference numerals throughout the specification. The length, thickness, etc. of each component in the drawings are illustrated for the purpose of explaining the present invention, and the present invention is not limited to the length, thickness, etc. described in the drawings.

[0020] The terms used herein are merely used to describe generic embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0021] In this specification, the "in-plane retardation (Re)" can be represented by the following formula A, the "thickness direction retardation (Rth)" can be represented by the following formula B, and the "degree of biaxiality (NZ)" can be represented by the following formula C. [Formula A] Re = (nx-ny) × d [Formula B] Rth = ((nx + ny) / 2-nz) × d [Formula C] NZ = (nx-nz) / (nx-ny) (In the above formulas A to C, nx, ny, and nz are the refractive indices in the slow axis direction, fast axis direction, and thickness direction of the optical element at the measurement wavelength, respectively, and d is the thickness (unit: nm) of the optical element.) In the above formulas A to C, the measurement wavelength may be any specific wavelength between 450 nm and 650 nm.

[0022] In this specification, unless otherwise specified, nx, ny, and nz respectively refer to the slow axis (the axis with the maximum refractive index in the in-plane direction), fast axis (the axis with the minimum refractive index in the in-plane direction), and refractive index in the thickness direction of an optical element at a wavelength of 550 nm.

[0023] When describing angles in this specification, "+" means counterclockwise relative to a reference, and "-" means clockwise relative to a reference.

[0024] As used herein, "(meth)acrylic" means acrylic and / or methacrylic.

[0025] In this specification, when a range of numerical values ​​is indicated, "X to Y" means "X or more and Y or less (X≦ and ≦Y)."

[0026] A polarizing plate according to an embodiment of the present invention includes a single-layer retardation film. The polarizing plate improves visibility at all azimuth angles, minimizes color change, reduces light transmittance at all azimuth angles, and is excellent in terms of the effect of reducing thickness. Here, "reducing light transmittance" means reducing the degree of light transmission emitted from all azimuth angles when the polarizing plate is applied to an optical display device and driven, and light leakage (light leakage) can be prevented. The lower the maximum light transmittance, the more preferable. In one specific example, the maximum light transmittance when the polarizing plate is driven may be 0.5% or less, for example, 0 to 0.5%, or 0.1 to 0.5%.

[0027] The polarizing plate according to one embodiment of the present invention includes a single-layer retardation film, and the polarizing plate can be manufactured by roll-to-roll method, thereby improving processability and economy in manufacturing the polarizing plate.

[0028] A polarizing plate according to one embodiment of the present invention includes a polarizer and a retardation layer laminated on one surface of the polarizer. The retardation layer includes a retardation film in which nx>nz>ny (nx, ny, and nz are the refractive indexes of the retardation film in the slow axis direction, the fast axis direction, and the thickness direction at a wavelength of 550 nm, respectively) is satisfied. The orientation direction of the main chain of the resin contained in the retardation film is at an angle of -5° to +5° with respect to the light absorption axis of the polarizer. The retardation film has a degree of biaxiality of 0.3 to 0.7 at a wavelength of 550 nm.

[0029] The retardation layer may be laminated on a light incident surface of the polarizer for internal light. Here, the 'light incident surface of the polarizer for internal light' refers to a surface where light emitted from an optical display panel enters the polarizer, and the internal light may be light emitted from a backlight unit.

[0030] The polarizing plate may be a viewer-side polarizing plate or a light source-side polarizing plate.

[0031] According to one embodiment of the present invention, the retardation layer may be located between the polarizer of the viewer-side polarizing plate and a panel for an optical display device (e.g., a liquid crystal panel). Preferably, 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 perpendicular to each other.

[0032] According to another embodiment of the present invention, the retardation layer may be located between the polarizer of the light source side polarizing plate and the panel for optical display device. Preferably, 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 perpendicular to each other.

[0033] The retardation film is a single-layer retardation film. This has the effect of reducing the thickness of the polarizing plate, improving the processability and economy when manufacturing the polarizing plate. Here, "single-layer retardation film" means a retardation film consisting of only one layer, without two or more layers of retardation film being bonded together by an adhesive layer or bonding layer.

[0034] According to one embodiment of the present invention, the retardation film may have a thickness of 40 to 100 μm, for example, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 μm, for example, 40 to 80 μm. In this range, the retardation film can be applied to a polarizing plate, and can provide a thinning effect.

[0035] The retardation layer may be composed of only a retardation film, which can reduce the thickness of the polarizing plate and improve the processability and economy during the manufacture of the polarizing plate.

[0036] According to an embodiment of the present invention, the polarizing plate may have only a retardation film between the polarizer and the adherend (e.g., a panel for an optical display device). In this case, the polarizing plate may have an adhesive layer, a retardation film, and an adhesive layer laminated in this order on one side of the polarizer, and the adhesive layer may adhere to the adherend.

[0037] According to another embodiment of the present invention, the polarizing plate may have a retardation film and one or more lower protective layers between the polarizer and the substrate (e.g., a panel for an optical display device). The lower protective layer may be between the polarizer and the retardation film and / or between the retardation film and the substrate. In one specific example, the polarizing plate may have an adhesive layer, a retardation film, a lower protective layer, and an adhesive layer laminated in order on one side of the polarizer, and the adhesive layer may adhere to the substrate.

[0038] The lower protective layer may have an in-plane retardation of 10 nm or less at a wavelength of 550 nm, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 nm, for example, 0 to 10 nm. In this range, the protective effect of 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 layer. For example, the lower protective layer may be a film made of one or more resins selected from cellulose-based materials including triacetyl cellulose (TAC) and the like, polyester-based materials including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, cyclic olefin copolymer (COC)-based materials, cyclic olefin polymer (COP)-based materials, polycarbonate-based materials, polyethersulfone-based materials, polysulfone-based materials, polyamide-based materials, polyimide-based materials, polyolefin-based materials, polyarylate-based materials, polyvinyl alcohol-based materials, polyvinyl chloride-based materials, polyvinylidene chloride-based materials, and acrylic-based materials.

[0039] The retardation film has a refractive index of nx>nz>ny (nx, ny, nz are the refractive index of the retardation film in the slow axis direction, the fast axis direction, and the thickness direction at a wavelength of 550 nm, respectively) at a wavelength of 550 nm, and the orientation direction of the main chain of the resin contained in the retardation film forms an angle of -5° to +5° with respect to the light absorption axis of the polarizer. This makes it easy to provide the effect of improving visibility at all azimuth angles, minimizing color change, and reducing light transmittance at all azimuth angles, even if the polarizing plate is a single layer and has a retardation film with nx>nz>ny at a wavelength of 550 nm.

[0040] The retardation film satisfies nx>nz>ny at a wavelength of 550 nm. This means that by making nx>ny and 0<(nx-nz) / (nx-ny)<1, the retardation film can be used to reduce changes due to viewing angles, improve visibility in contrast or black and white display, and reduce color changes when applied to birefringent optical display panels.

[0041] According to one embodiment of the present invention, (nx-ny) is 0.0022 to 0.0075, for example, 0.0022, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, for example, 0.00275 to 0.0075, (nx-nz) is , 0.00066 to 0.00525, for example, 0.00066, 0.00070, 0.00080, 0.00090, 0.0010, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.00525, for example, 0.000825 to 0.00525. Within this range, the retardation film has little change due to the viewing angle when applied, and can be useful for improving the brightness ratio or visibility in black and white display when applied to a birefringent optical display panel.

[0042] According to one embodiment of the present invention, in the retardation film, nx may be 1.500 to 1.710, for example, 1.500, 1.550, 1.600, 1.650, 1.700, 1.710, for example, 1.500 to 1.705, ny may be 1.480 to 1.700, for example, 1.480, 1.500, 1.550, 1.600, 1.650, 1.700, for example, 1.485 to 1.700, and nz may be 1.500 to 1.705, for example, 1.500, 1.550, 1.600, 1.650, 1.700, 1.705, for example, 1.500 to 1.700. In this range, the range of nx-ny and nx-nz as described above can be easily reached, and the manufacture of the retardation film can be facilitated.

[0043] The orientation direction of the main chain of the resin contained in the retardation film forms an angle of -5° to +5° with respect to the light absorption axis of the polarizer. This is because the retardation film is manufactured from a composition for retardation film described below, and the retardation film satisfies the optical properties described below, thereby improving visibility at all azimuth angles and providing the effect of reducing light transmittance at all azimuth angles.

[0044] According to one embodiment of the present invention, the orientation direction of the main chain of the resin contained in the retardation film may be −3° to +3°, or 0° with respect to the light absorption axis of the polarizer. In this range, it is easy to obtain the above-mentioned effects.

[0045] The main chain direction of the resin contained in the retardation film can be measured by a conventional method known to those skilled in the art. For example, the main chain orientation direction can be confirmed by visually checking the texture of the retardation film in the stretching direction. For example, the main chain orientation direction can be confirmed by measuring the crystal structure of the resin in the retardation film by X-ray measurement of the retardation film (e.g., X-ray diffraction (X-RD)), measuring the dynamic structure of the resin in the retardation film by NMR measurement of the retardation film, and measuring the orientation direction by Raman and infrared spectroscopy. The light absorption axis of the polarizer may be the machine direction of the polarizer.

[0046] The angle between the orientation direction of the main chain of the resin contained in the retardation film and the light absorption axis of the polarizer can be realized by adjusting the angle between the main chain direction and the light absorption axis of the polarizer when laminating the retardation film on the polarizer.

[0047] According to one embodiment of the present invention, the retardation film has a biaxiality of 0.3 to 0.7 at a wavelength of 550 nm. If the biaxiality is less than 0.3, the light transmittance in the black state is high at all viewing angles, and the black luminance may be poor. If the biaxiality is more than 0.7, the light transmittance in the black state is high at all viewing angles, and the black luminance may be poor. For example, the degree of biaxiality may be 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, for example, 0.4 to 0.6, and a remarkably excellent effect is obtained within this range.

[0048] According to one embodiment of the present invention, the retardation film may have a value of 0.8 to 1.2 in the following formula 1 and a value of 0.9 to 1.1 in the following formula 2. Within the range of the values ​​of formula 1 and formula 2, the retardation film is manufactured using the composition for retardation film described below, and it may be easy to provide the effect of improving visibility at all viewing angles and reducing the light transmittance in the black state at all viewing angles. For example, the value of the following formula 1 may be 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, for example, 0.9 to 1.1, and the value of the following formula 2 may be 0.9, 0.95, 1.0, 1.05, 1.1, for example, 0.95 to 1.05. [Formula 1] Re(450nm) / Re(550nm) [Formula 2] Re(650nm) / Re(550nm) (In Equation 1 and Equation 2, Re(450nm), Re(550nm), and Re(650nm) are the in-plane retardation (unit: nm) of the retardation film at wavelengths of 450nm, 550nm, and 650nm, respectively.)

[0049] According to one embodiment of the present invention, the retardation film may have an in-plane retardation of 220 to 300 nm at a wavelength of 450 to 650 nm, for example, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300 nm, for example, 250 to 280 nm. In this range, the value of formula 1 and the value of formula 2 can be easily reached, and it can be easy to provide the effect of reducing the light transmittance at all azimuth angles.

[0050] According to one embodiment of the present invention, the retardation film may have an in-plane retardation of 220 to 300 nm at a wavelength of 550 nm, and a degree of biaxiality of 0.3 to 0.7. In this range, it may be easy to provide the effect of reducing light transmittance at all azimuth angles. For example, the in-plane retardation may be 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300 nm, preferably 250 to 280 nm, and the degree of biaxiality may be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, for example, 0.4 to 0.6. In this range, the light transmittance may be significantly reduced to 0.5% or less.

[0051] Fig. 3 is a diagram showing the in-plane retardation (X-axis, unit: nm) and light transmittance (Y-axis, unit: %) at a wavelength of 550 nm according to the degree of biaxiality (NZ) of the retardation film at a wavelength of 550 nm when a polarizing plate of one embodiment of the present invention is mounted on a horizontal electric field type, for example, an IPS liquid crystal panel and driven. In Fig. 3, ■ represents the light transmittance when the retardation film has an NZ of 0.4 at a wavelength of 550 nm, ● represents the light transmittance when the retardation film has an NZ of 0.5 at a wavelength of 550 nm, and ▲ represents the light transmittance when the retardation film has an NZ of 0.6 at a wavelength of 550 nm.

[0052] Referring to FIG. 3, it can be seen that when the retardation film has an in-plane retardation of 220 to 300 nm at a wavelength of 550 nm and a degree of biaxiality of 0.3 to 0.7, preferably when the in-plane retardation is 250 to 280 nm and the degree of biaxiality is 0.4 to 0.6, the light transmittance is significantly reduced to 0.5% or less.

[0053] The retardation film may be formed from a composition for a retardation film.

[0054] The retardation film composition may include a resin and one or more of the compounds represented by the following formulas I to IV. The retardation film composition may facilitate achieving the optical properties described above.

[0055] The resin is a cellulose ester resin, and is contained in the retardation film as a main component. Here, "main component" means that the resin is contained in an amount of 70% by weight or more, for example, 75 to 99% by weight, or 80 to 99% by weight, based on the solid content of the retardation film or the composition for the retardation film.

[0056] The cellulose ester resin is a resin in which at least some of the hydrogen atoms of the hydroxyl groups (OH) at C2, C3, and C6 of cellulose are substituted with a plurality of aromatic -CO- groups; 1-6 ) a cellulose ester resin regioselectively substituted with one or more alkyl-CO- groups.

[0057] Here, “aromatic —CO—” refers to (i) an aryl group unsubstituted or substituted by 1 to 5 R1, (C 6-20 (ii) heteroaryl is a 5- to 10-membered ring having 1 to 4 heteroatoms selected from N, O and S, and heteroaryl may be unsubstituted or heteroaryl-CO- substituted by 1 to 5 R1, where R1 is as defined below.

[0058] The cellulose ester resin is a resin in which at least some of the hydrogen atoms of the hydroxyl groups (OH) at C2, C3, and C6 of cellulose are substituted with a plurality of aromatic -CO- groups; 1-6 ) alkyl-CO- groups, and at least a portion of the hydroxyl groups (OH) at C2, C3 and C6 are regioselectively unsubstituted.

[0059] According to one embodiment of the present invention, the regioselectively substituted cellulose ester-based resin may include a plurality of alkyl-acyl or alkyl-CO- groups; a plurality of aryl-acyl or aryl-CO- groups; a plurality of heteroaryl-acyl or heteroaryl-CO- groups.

[0060] An acyl substituent or R-CO- refers to a substituent having the structure:

[0061] [ka]

[0062] In cellulose esters such acyl or R-CO- groups are generally attached to the pyranose ring of cellulose via an ester bond (ie, via an oxygen atom).

[0063] Aromatic -CO- can be an acyl substituent having an aromatic-containing ring system. Examples may include aryl-CO- or heteroaryl-CO-. Specific examples include benzoyl, naphthoyl and furoyl, each of which may be unsubstituted or substituted.

[0064] The term "aryl-acyl" substituent refers to an acyl substituent in which "R" is an aryl group. The term "aryl" refers to a monovalent group formed by removing a hydrogen atom from a ring carbon of an arene (i.e., a monocyclic or polycyclic aromatic hydrocarbon). In some cases, the aryl-acyl group is located before a carbon unit: for example, (C5-6 ) aryl-acyl, (C 6-12 ) aryl-acyl, or (C 6-20 ) aryl-acyl. Examples of aryl groups suitable for use in the various embodiments include, but are not limited to, phenyl, benzyl, tolyl, xylyl, and naphthyl. Such aryl groups may be substituted or unsubstituted.

[0065] The term "alkyl-acyl" refers to an acyl substituent where "R" is an alkyl group. "Alkyl" means a monovalent group formed by removing a hydrogen atom from a non-aromatic hydrocarbon, and may contain 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 ), (C 1-12 ), (C 1-5 ), or (C 1-3 ) alkyl groups. In various embodiments, the alkyl groups include C 1-5 In yet another embodiment, the alkyl group can be a straight chain alkyl group. 1-3 It may be a straight chain alkyl group. 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 groups. Examples of alkyl-acyl groups include acetyl, propionyl, and butyroyl, and the like.

[0066] The term "haloalkyl" refers to an alkyl substituent in which one or more hydrogens are replaced by a halogen group. The carbon unit of a haloalkyl group, e.g., halo(C 1-6 ) alkyl is often included. Haloalkyl groups can be straight or branched. Non-limiting examples of haloalkyl include chloromethyl, trifluoromethyl, dibromoethyl, and the like.

[0067] The term "heteroalkyl" means an alkyl in which one or more carbon atoms have been replaced with a heteroatom such as, for example, N, O and S.

[0068] The term "heteroaryl" refers to an aryl in which one or more of the carbon units of the aryl ring are replaced by a heteroatom such as O, N, and S. The heteroaryl ring can be monocyclic or polycyclic. Often, the units that make up the heteroaryl ring system include, for example, 5- to 20-membered ring systems. A 5-membered heteroaryl refers to a ring system having 5 atoms that form the heteroaryl ring. Non-limiting examples of heteroaryl include pyridinyl, quinolinyl, pyrimidinyl, and thiophenyl, and the like.

[0069] The term "alkoxy" refers to an alkyl-O- or alkyl group terminally attached to an oxygen group. Often, the term refers to a carbon unit, e.g., (C 1-6 ) alkoxy. Non-limiting examples of alkoxy include methoxy, ethoxy, propoxy, and the like.

[0070] The term "haloalkoxy" refers to an alkoxy in which one or more of the hydrogens are replaced with a halogen. Often, the term refers to a carbon unit, e.g., halo(C 1-6 )alkoxy. Non-limiting examples of haloalkoxy include trifluoromethoxy, bromomethoxy, 1-bromo-ethoxy, and the like.

[0071] The term "halo" means halogens such as fluoro, chloro, bromo or iodo.

[0072] The term "degree of substitution (DS)" is used to describe the substitution level of the substituents of the sugar substituents, which are anhydroglucose units ("AGU"). Generally, conventional cellulose contains three hydroxyl groups that may be substituted on each AGU. Thus, DS can have a value of 0 to 3. However, low molecular weight cellulose mixed esters can have a total degree of substitution slightly higher than 3 due to the contribution of the end groups. Since DS is a statistical average, not all AGUs have a single substituent even if the value is 1. In some cases, there may be unsubstituted anhydroglucose units, some have two, some have three, and more often the value is not an integer. Total DS is defined as the average number of all substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to a specific substituent, such as, for example, hydroxyl, acetyl, butyryl, or propionyl. The degree of substitution can also specify the carbon units of the anhydroglucose unit.

[0073] When the degree of substitution refers to hydroxyl (i.e., the degree of substitution with hydroxyl, DS OH ), the designation refers to the average hydroxyl group per unsubstituted anhydroglucose. OH is not used in calculating the total degree of substitution.

[0074] Regioselectivity can be measured by determining the relative degree of substitution ("RDS") at C6, C3 and C2 of the cellulose ester by carbon-13 NMR spectroscopy (reference [Macromolecules, 1991, 24, 3050-3059]). In the case of one type of acyl substituent, or when a second acyl substituent is present in small amounts (DS<0.2), the RDS can be most easily measured directly by integration of the ring carbons. In the case of two or more acyl substituents present in similar amounts, in addition to determining the ring RDS, the cellulose ester may have to be fully substituted with additional substituents in order to measure the RDS of each substituent independently by integration of the carbonyl carbon. In conventional cellulose esters, regioselectivity is generally not observed, and the C6 / C3, C6 / C2 or C3 / C2 RDS ratios are generally close to 1 or less. In essence, conventional cellulose esters are random copolymers. In contrast, when one or more acylation reagents are added to cellulose dissolved in a suitable solvent, the C6 position of cellulose is acylated much more rapidly than the C2 and C3 positions. As a result, the C6 / C3 and C6 / C2 ratios are much greater than 1, which is characteristic of 6,3- or 6,2-enhanced regioselectively substituted cellulose esters.

[0075] According to one embodiment of the present invention, the cellulose ester generally comprises the following structure:

[0076] [ka]

[0077] (In the formula, R 2 , R 3 , and R 6 is hydrogen (where R 2 , R 3 and R 6 is / are not hydrogen at the same time) or are alkyl-acyl and / or aryl-acyl groups bonded to cellulose via ester bonds, and n is an integer equal to or greater than 1).

[0078] The degree of polymerization ("DP") of the cellulose esters produced by these methods can be 10 or more, 50 or more, 100 or more, or 250 or more.

[0079] The acylating reagent may include, but is not limited to, alkyl or aryl carboxylic anhydrides, carboxylic acid halides, and / or carboxylic acid esters containing the aforementioned alkyl or aryl groups suitable for use in the acyl substituent of the regioselectively substituted cellulose esters described herein. Examples of suitable carboxylic acid anhydrides include, but are not limited to, acetic anhydride, propionic anhydride, butyric anhydride, pivaloyl anhydride, benzoic anhydride, and naphthoyl anhydride. Examples of carboxylic acid halides include, but are not limited to, acetyl, propionyl, butyryl, pivaloyl, benzoyl, and naphthoyl chlorides or bromides. Examples of carboxylic acid esters include, but are not limited to, acetyl, propionyl, butyryl, pivaloyl, benzoyl, and naphthoyl methyl esters. In one or more embodiments, the acylating agent may be one or more carboxylic acid anhydrides selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, pivaloyl anhydride, benzoyl anhydride, and naphthoyl anhydride.

[0080] The cellulose ester resin has a plurality of aromatic -CO- groups as a substituent; a plurality of primary unsaturated or saturated (C 1-6 ) an alkyl-CO- group; and a cellulose ester resin regioselectively substituted with one or more of a plurality of hydroxy groups as substituents.

[0081] According to one embodiment of the present invention, the cellulose ester resin may have a degree of substitution with hydroxy of 0.2 to 2.0, a degree of substitution with C2 of 0.15 to 0.8, a degree of substitution with C3 of 0.05 to 0.6, a degree of substitution with C6 of 0.05 to 0.6, and a total degree of substitution of 0.25 to 2.5.

[0082] According to one embodiment of the present invention, the cellulose ester resin may have a degree of substitution with hydroxy of 0.2 to 2.0, a degree of substitution at C2 by an aromatic-CO group or an alkyl-CO group of 0.15 to 0.8, a degree of substitution at C3 by an aromatic-CO group or an alkyl-CO group of 0.05 to 0.6, a degree of substitution at C6 by an aromatic-CO group or an alkyl-CO group of 0.05 to 0.6, and a total degree of substitution by an aromatic-CO group or an alkyl-CO group of 0.25 to 2.5.

[0083] The cellulose ester resin is a primary unsaturated or saturated (C 1-6 ) Alkyl-Acyl Substituent ("DS FAk In one embodiment, the cellulose ester resin has a degree of substitution of 0.7 to 1.9 for primary unsaturated or saturated (C 1-6 ) The alkyl-acyl substituents may have any degree of substitution.

[0084] In one class of such embodiments, the first unsaturated or saturated (C 1-20 ) alkyl-CO-substituents are acetyl, propionyl, butyryl, isobutyryl, 3-methylbutanoyl, pentanoyl, 4-methylpentanoyl, 3-methylpentanoyl, 2-methylpentanoyl, hexanoyl or crotonyl. In one class of such embodiments, the first unsaturated or saturated (C 1-6 ) The alkyl-CO-substituent is acetyl, propionyl or crotonyl.

[0085] In one embodiment or in combination with any other embodiment, the cellulose ester-based resin comprises a plurality of second (C 1-20 In one class of such embodiments, the second (C 1-20 ) alkyl-CO-substituent ("DS SAk」 ) is 0.05 to 0.6.

[0086] In some of these types of cases, 1-20The second (C ) alkyl-CO- substituent is acetyl, propionyl, butyryl, isobutyryl, 3-methylbutanoyl, pentanoyl, 4-methylpentanoyl, 3-methylpentanoyl, 2-methylpentanoyl, hexanoyl, pivalyl, or 2-ethylhexanoyl. 1-20 ) alkyl-CO-substituents are acetyl, isobutyryl, 3-methylbutanoyl, pentanoyl, 4-methylpentanoyl, 3-methylpentanoyl, 2-methylpentanoyl, hexanoyl, or 2-ethylhexanoyl. In one class of such embodiments, the second (C 1-20 ) The alkyl-CO-substituent is acetyl or 2-ethylhexanoyl.

[0087] In one embodiment or in combination with any other embodiment, the aromatic -CO- is (C 6-20 ) aryl-CO-, where aryl is unsubstituted or substituted with 1-5 R1. In one class of such embodiments, aromatic-CO- is benzoyl or naphthoyl, which is unsubstituted or substituted with 1-5 R1. In one class of such embodiments, aromatic-CO- is benzoyl, which is unsubstituted or substituted with 1-5 R1. In one class of such embodiments, aromatic-CO- is naphthoyl, which is unsubstituted or substituted with 1-5 R1.

[0088] In one embodiment or in combination with any other embodiment, the aromatic -CO- is benzoyl unsubstituted or substituted by R1. In one class of such embodiments, the cellulose ester has a total DS of 0.40 to 1.20. ArCO In one subcategory of this category, C3DS ArCO and C3DS ArCO The sum is 0.30 to 0.75.

[0089] In one embodiment or in combination with any other embodiment, the aromatic -CO- is naphthoyl unsubstituted or substituted with 1 to 5 R1. In one class of such embodiments, the cellulose ester has a total DS of 0.30 to 0.6. ArCO In one subcategory of this category, C3DS ArCO and C3DS ArCO The sum of these is 0.20 to 0.40. In one subcategory of this category, C3DS ArCO and C3DS ArCO The sum is 0.30 to 0.40.

[0090] In one embodiment or in combination with any other embodiment, aromatic-CO- is heteroaryl-CO-, where heteroaryl is a 5- to 10-membered ring having 1- to 4-heteroatoms selected from N, O and S, where heteroaryl is unsubstituted or substituted by 1-5 R1. In one class of such embodiments, heteroaryl-CO- is pyridinyl-CO-, pyrimidinyl-CO-, furanyl-CO-, or pyrrolyl-CO-. In one class of such embodiments, heteroaryl-CO- is 2-furoyl.

[0091] In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.4 to 1.6. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 1.0 to 1.6. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.3 to 1.25. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.4 to 1.2. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.4 to 0.8. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.3 to 0.8. ArCOIn one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.3 to 0.6. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.2 to 0.6. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.2 to 0.5. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.8 to 1.2. ArCO In one embodiment or in combination with any other embodiment, the cellulose ester has a totDS of 0.5 to 1.1. ArCO has.

[0092] In one embodiment or in combination with any other embodiment, DS OH In one embodiment or in combination with any other embodiment, DS OH In one embodiment or in combination with any other embodiment, DS OH In one embodiment or in combination with any other embodiment, DS OH In one embodiment or in combination with any other embodiment, DS OH In one embodiment or in combination with any other embodiment, DS OH In one embodiment or in combination with any other embodiment, DS OH is 0.5 to 0.8.

[0093] In one embodiment or in combination with any other embodiment, C2DS ArCO and C3DS ArCO The sum of is 0.3 to 1.25. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.2 to 0.4. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCOThe sum of is 0.3 to 0.4. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.4 to 1.2. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.4 to 1.1. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.4 to 1.0. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.5 to 1.1. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.6 to 1.0. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum of is 0.6 to 1.25. In one embodiment or in combination with any other embodiment, the C2DS ArCO and C3DS ArCO The sum is 0.30 to 0.75.

[0094] The composition for a retardation film, ie, the retardation film, may contain one or more components A of the chemical formulae I to IV.

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099] (In the chemical formulas I to IV, Ring A is (C 6-20 ) aryl or a 5- to 10-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O, and S; Ring B is (C 6-20 ) aryl or a 5- to 10-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O, and S; Ring C is (C 6-20 ) aryl or a 5- to 10-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O, and S; R 1 is saturated or unsaturated (C 1-20 ) alkyl; saturated or unsaturated halo(C 1-20 ) alkyl; optionally 1 to 5 substituted with alkyl, haloalkyl, alkoxy, haloalkoxy or halo (C 6-20 ) aryl; 5- to 10-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O, and S; or -CH2C(O)-R3, R 2 are independently hydrogen, saturated or unsaturated (C 1-20 ) alkyl, or saturated or unsaturated halo(C 1-20 ) alkyl; R 3 is saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, (C 6-20 ) aryl, or a 5- to 10-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O, and S, where the aryl or heteroaryl is unsubstituted or substituted with 1 to 5 R 6 Replaced by; R 4 is saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, or saturated or unsaturated (C 1-20)Alkyl-CO-(C 1-20 ) alkyl, where each group is unsubstituted or substituted with 1 to 3 hydroxyl, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halo(C 1-20 ) alkoxy, saturated or unsaturated hydroxy (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 ) substituted by alkyl; Each R 5 are independently hydroxy, cyano, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halo(C 1-20 ) alkoxy, or halo; Each R 6 are independently hydroxy, cyano, saturated or unsaturated (C 1-20) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxy, saturated or unsaturated halo(C 1-20 ) alkoxy, or halo or (C 6-20 ) aryl, where aryl is unsubstituted or substituted with 1 to 5 R 7 Replaced by; Each R 7 are independently hydroxyl, saturated or unsaturated (C 1-6 ) alkyl, saturated or unsaturated halo(C 1-6 ) alkyl, or saturated or unsaturated (C 1-6 ) alkoxyl; R 8 is saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxyl, or saturated or unsaturated halo(C 1-20 ) alkoxyl; Each R 9 is R4-O-, hydroxy, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated hetero (C 1-20 ) alkyl, saturated or unsaturated halo(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-(C1-20 ) 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, 5- to 10-membered heteroaryl containing 1 to 4 heteroatoms selected from N, O, and S; In this case, each group may be unsubstituted or may contain 1 to 3 hydroxyl, saturated or unsaturated (C 1-20 ) alkyl, saturated or unsaturated halo(C 1-20 ) alkyl, saturated or unsaturated (C 1-20 ) alkoxyl, saturated or unsaturated halo(C 1-20 ) alkoxyl, 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 or 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 ) substituted by alkyl; each n is 0, 1, 2, 3, 4, or 5; each m is 0, 1, 2, 3, or 4; k is 0, 1, 3 or 4.

[0100] According to one embodiment of the present invention, component A is selected from the group consisting of 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-triazin-2-yl)-5-(hexyloxy)phenol (Tinuvin (Tinuvin) 1577), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[2-hydroxy-3-(dodecyloxy- and tridecyloxy)propoxy]phenol (Tinuvin 400), isopropyl alcohol, ethyl ... octyl 2-(4-(4,6-di([1,1'-biphenyl]-4-yl)-1,3,5-triazin-2-yl)-3-hydroxyphenoxy)propanoate (Tinuvin 479), 6,6'-(6-(2,4-tibutoxipenyl)-1,3,5-triazin-2,4-diyl)bis(3-butoxyphenol) (Tinuvin 460), 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(3-((2-ethylhexyl)oxy)-2-hydroxypropoxy)phenol (Tinuvin 405), 7-diethylamino-4-methylcoumarin, or combinations thereof.

[0101] According to one embodiment of the present invention, component A may be present in an amount of 1% by weight or more. In one class of such embodiments, component A may be present in a range of 1 to 30% by weight. In one class of such embodiments, component A may be present in a range of 1 to 20% by weight. In one class of such embodiments, component A may be present in a range of 1 to 15% by weight. Within this range, the effects of the present application may be easily realized.

[0102] The composition for retardation film may further contain a plasticizer to improve the workability and flexibility of the retardation film. The plasticizer may be contained in an amount of 0.1 to 10 wt %, for example, 0.1 to 5 wt %, based on the solid content of the retardation film or the composition for retardation film. In this range, the glass transition temperature and melting temperature of the material from which the retardation film is formed can be reduced, allowing for lower temperature and / or simplified film production.

[0103] The plasticizer can be selected from phosphate type plasticizers, phthalate type plasticizers, terephthalate type plasticizers, trimellitate type plasticizers, benzoate type plasticizers, glycolate type plasticizers, citrate type plasticizers, polyhydric alcohol ester type plasticizers, polyol type plasticizers, polyester type plasticizers, and the like.

[0104] Non-limiting examples of glycolate plasticizers may include methylphthalyl methyl glycolate, ethylphthalyl ethyl glycolate, propylphthalyl propyl glycolate, butylphthalyl butyl glycolate, octylphthalyl octyl glycolate, methylphthalyl ethyl glycolate, ethylphthalyl methyl glycolate, ethylphthalyl propyl glycolate, methylphthalyl butyl glycolate, ethylphthalyl butyl glycolate, butylphthalyl methyl glycolate, butylphthalyl ethyl glycolate, butylphthalyl ethyl glycolate, propylphthalyl butyl glycolate, butylphthalyl propyl glycolate, methylphthalyl octyl glycolate, ethylphthalyl octyl glycolate, octylphthalyl methyl glycolate and octylphthalyl ethyl glycolate.

[0105] The retardation film may be manufactured by solution casting and stretching the composition for retardation film. According to one embodiment of the present invention, the retardation film may be manufactured by preparing a casting solution by adding a solvent to the composition for retardation film itself or the composition for retardation film, applying the casting solution to a substrate and drying it to prepare an unstretched film, and stretching the unstretched film in the machine direction of the unstretched film.

[0106] In one specific example, the orientation direction of the main chain of the resin contained in the retardation film can be adjusted by 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 when producing the unstretched film.

[0107] In one embodiment, the slow axis of the retardation film may be at an angle of −5° to +5°, for example, −3° to +3°, or 0°, relative to the light transmission axis of the polarizer. Within this range, the effects of the present application may be easily realized.

[0108] In one embodiment, the slow axis of the retardation film may be substantially parallel to the width direction of the retardation film.

[0109] A polarizer can convert incident natural light or polarized light into linearly polarized light in a specific direction. The polarizer may have a thickness of 2 to 30 μm, specifically, 4 to 25 μm, and can be used in a polarizing plate within this range.

[0110] The polarizer can be manufactured from a film mainly composed of a polyvinyl alcohol-based resin by a conventional method known to those skilled in the art. For example, the polarizer can be manufactured by iodine dyeing and stretching. The polarizer has a light absorption axis and a light transmission axis perpendicular to the light absorption axis in the in-plane direction, and the light absorption axis may be MD and the light transmission axis may be TD.

[0111] The polarizing plate may further include a top protective layer on the top surface of the polarizer.

[0112] The upper protective layer may include one or more of an optically transparent protective coating layer and a protective film. The protective coating layer may include a coating layer formed of a composition containing an active energy ray curable compound. The protective film is an optically transparent film, and may be a film made of one or more resins selected from, for example, cellulose-based films including triacetyl cellulose (TAC) and the like, polyester-based films including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and the like, cyclic polyolefin-based films, polycarbonate-based films, polyethersulfone-based films, polysulfone-based films, polyamide-based films, polyimide-based films, polyolefin-based films, polyarylate-based films, polyvinyl alcohol-based films, polyvinyl chloride-based films, and polyvinylidene chloride-based films. Specifically, TAC and PET films can be used.

[0113] The upper protective layer may have a thickness of 0.1 to 100 μm, specifically 5 to 70 μm, specifically 15 to 45 μm, and can be used in a polarizing plate within this range.

[0114] The upper protective layer may be attached to the adherend by an adhesive layer. If the absence of the upper protective layer does not affect the function of the polarizing plate, the upper protective layer may be omitted.

[0115] The polarizing plate may further include an adhesive layer on the bottom surface thereof. The adhesive layer serves to adhere the polarizing plate to the panel. The adhesive layer may be formed of a conventional adhesive composition known to those skilled in the art.

[0116] Referring to FIG. 1, the polarizing plate may include a polarizer 100 , an upper protective layer 300 laminated on an upper surface of the polarizer 100 , and a retardation film 200 laminated on a lower surface of the polarizer 100 .

[0117] Referring to FIG. 2, the polarizing plate may include a polarizer 100, an upper protective layer 300 laminated on an upper surface of the polarizer 100, a retardation film 200 and a lower protective layer 400 sequentially laminated on a lower surface of the polarizer 100.

[0118] optical display device According to an embodiment of the present invention, an optical display device includes a polarizer. The optical display device may include a liquid crystal display device. The polarizer may be included in a viewer-side polarizer of the optical display device. In one embodiment, the liquid crystal display device may be an in-plane switching (IPS), fringe-field switching (FFS), advanced super dimension switching (ADS) or PLS mode liquid crystal display device having a horizontal alignment mode liquid crystal.

[0119] According to one embodiment of the present invention, a liquid crystal display device may include a liquid crystal panel, a viewer-side polarizing plate on one side of the liquid crystal panel, and a light source-side polarizing plate on the other side of the liquid crystal panel. The light absorption axis of the polarizer in the viewer-side polarizing plate may be substantially perpendicular to the light absorption axis of the light source-side polarizing plate. When the light absorption axis of the polarizer in the viewer-side polarizing plate is 0°, the light absorption axis of the light source-side polarizing plate may be at 90°, and the rubbing direction of the liquid crystal in the liquid crystal panel may be at 90°.

[0120] The configuration and operation of the present invention will be described in more detail below based on preferred embodiments of the present invention, however, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any sense.

[0121] Example 1 A composition for retardation film (regioselectively substituted cellulose ester resin, containing a propionyl group C2 substitution degree of 0.26, a propionyl group C3 substitution degree of 0.34, a propionyl group C6 substitution degree of 0.53, a propionyl group total substitution degree of 2.33, and a hydroxyl substitution degree of 1.87) was prepared by solution casting of the composition for retardation film (regioselectively substituted cellulose ester resin, contained as a main component, EASTMAN Chemical Ltd.). The unstretched film thus prepared was stretched in the machine direction of the unstretched film at a stretch ratio of 1.5 times to produce a retardation film (in-plane retardation at a wavelength of 550 nm: 270 nm, degree of biaxiality: 0.6, thickness: 56 μm, nx = 1.5323, ny = 1.5275, nz = 1.5294).

[0122] A polyvinyl alcohol film (TS#20, Kuraray, Japan, thickness before stretching: 20 μm) was stretched 6 times uniaxially in the machine direction of the film using an aqueous iodine solution at 55° C. to produce a polarizer with a light transmittance of 45%.

[0123] A polyethylene terephthalate (PET) film with an anti-reflection layer was laminated on the upper surface of the manufactured polarizer, and the manufactured retardation film was laminated on the lower surface of the polarizer to manufacture a polarizing plate. In the manufactured polarizing plate, the angle between the light absorption axis of the polarizer (machine direction of the polarizer) and the main chain direction of the site-selectively substituted cellulose ester resin in the retardation film is 0°.

[0124] Examples 2 to 5 A polarizing plate was manufactured in the same manner as in Example 1, except that a regioselectively substituted cellulose ester resin with a different substitution degree was used, the solution casting conditions were changed, and the stretching ratio was changed to change the retardation film.

[0125] Comparative Example 1 to Comparative Example 4 A polarizing plate was manufactured in the same manner as in Example 1, except that a regioselectively substituted cellulose ester resin with a different substitution degree was used, the solution casting conditions were changed, and the stretching ratio was changed to change the retardation film.

[0126] The polarizing plates of the examples and comparative examples were evaluated for the following physical properties, which are shown in Table 1 below.

[0127] (1) Optical properties of retardation film: The retardation film was measured using AXOSCAN. (2) Angle: The angle between the light absorption axis of the polarizer in the polarizing plate (machine direction of the polarizer) and the main chain direction of the cellulose ester resin in the retardation film was measured by measuring the light absorption axis of the polarizer using AXOSCAN while the retardation film and the polarizer were separated, and measuring the main chain direction of the cellulose ester resin using X-ray diffraction (X-RD) method, and the relative angle between the light absorption axis and the main chain direction was calculated. (3) Maximum light transmittance (unit: %): In a Samsung Electronics TV model equipped with an IPS LCD panel, the polarizers manufactured in the examples and comparative examples were attached instead of the polarizer on the viewing side and driven. The maximum light transmittance in the black state at all viewing angles was calculated using the Extended Jones Matrix method using the TECHWIZ 1D (SANAI SYSTEM, KOREA) simulation program. However, the reduction in light transmittance due to the color filter inside the panel was excluded from the above calculation. The lower the maximum light transmittance, the more light leakage can be prevented and the better the visibility can be. (4) Black luminance and hue: In a Samsung Electronics TV model equipped with an IPS LCD panel, the polarizers manufactured in the examples and comparative examples were attached instead of the polarizer on the viewing side, and the TV was driven. Then, the black luminance and hue were evaluated by visual evaluation.

[0128] [Table 1]

[0129] *The retardation films of the examples and comparative examples each satisfy nx>nz>ny at a wavelength of 550 nm.

[0130] As can be seen from Table 1, the polarizing plate of the present invention has a single-layer retardation film, and provides the effects of improving visibility at all viewing angles, minimizing color change, reducing the maximum light transmittance in the black state at all viewing angles, and improving light leakage. On the other hand, as can be seen from Table 1, the polarizing plate of the comparative example having a retardation film that does not satisfy the optical characteristics of the present application had lower effects as described above compared to the examples.

[0131] Simple modifications and variations of the present invention can be easily implemented by those having ordinary skill in the art, and all such modifications and variations are deemed to be included within the scope of the present invention.

Claims

1. The polarizer includes a retardation layer laminated on one surface of the polarizer, The retardation layer includes a retardation film having a relationship of nx>nz>ny at a wavelength of 550 nm (nx, ny, and nz are the refractive indexes of the retardation film in the slow axis direction, the fast axis direction, and the thickness direction at a wavelength of 550 nm, respectively), the orientation direction of the main chain of the resin contained in the retardation film forms an angle of −5° to +5° with respect to the light absorption axis of the polarizer, The retardation film is a polarizing plate having a degree of biaxiality of 0.3 to 0.7 at a wavelength of 550 nm.

2. The polarizing plate according to claim 1 , wherein the retardation film is a single-layer retardation film.

3. 2. The polarizing plate according to claim 1, wherein the retardation film has an in-plane retardation of 220 to 300 nm at a wavelength of 550 nm.

4. The polarizing plate according to claim 1, wherein the retardation film has a value of the following formula 1 of 0.8 to 1.2 and a value of the following formula 2 of 0.9 to 1.

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

5. 2. The polarizing plate according to claim 1, wherein the slow axis of the retardation film is at an angle of −5° to +5° with respect to the light transmission axis of the polarizer.

6. The polarizing plate according to claim 1 , wherein the slow axis of the retardation film is parallel to a width direction of the retardation film.

7. The polarizing plate according to claim 1 , wherein the retardation film is a retardation film stretched in a machine direction (MD).

8. 2. The polarizing plate according to claim 1, wherein nx-ny is 0.0022 to 0.0075, and nx-nz is 0.00066 to 0.00525.

9. 2. The polarizing plate according to claim 1, wherein nx is from 1.500 to 1.710, ny is from 1.480 to 1.700, and nz is from 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 cellulose ester resin is a resin in which at least some of the hydrogen atoms of the hydroxyl groups (OH) at C2, C3, and C6 of the cellulose are substituted with a plurality of aromatic -CO- groups; １－６ 12. The polarizing plate according to claim 11, comprising a cellulose ester resin regioselectively substituted with one or more of the following: ) alkyl-CO- groups.

13. The cellulose ester resin is The degree of substitution with hydroxy is 0.2 to 2.0; The degree of substitution with C2 is 0.15 to 0.8, The degree of substitution with C3 is 0.05 to 0.6, The degree of substitution with C6 is 0.05 to 0.6; The polarizing plate according to claim 12, wherein the total degree of substitution is from 0.25 to 2.

5.

14. The polarizing plate according to claim 1 , wherein the retardation layer is composed of the retardation film alone.

15. 2. The polarizing plate according to claim 1, wherein the retardation layer has a thickness of 40 to 100 μm.

16. The polarizing plate according to claim 1 , further comprising a protective layer laminated on another surface of the polarizer.

17. An optical display comprising the polarizing plate according to any one of claims 1 to 16.

Images