Polarizing plate and optical display including same

Abstract

The invention provides a polarizing plate and an optical display including the same. The polarizing plate includes: a polarizing film; a first base layer; and a pattern layer, the first base layer and the pattern layer being sequentially formed on the light exit surface of the polarizing film, in which the pattern layer includes a first layer and a second layer sequentially formed on the first base layer, the first layer having a higher refractive index than the second layer, and wherein the first layer comprises a patterned portion formed at at least a portion thereof facing the second layer, the patterned portion comprising at least two optical patterns and a flat interval between the optical patterns adjacent to each other.

Description

[0001] The present invention is a divisional application of the invention patent application with application number 201910618567.8 filed on July 10, 2019, and invention name: Polarizing plate and optical display including polarizing plate.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of Korean Patent Application No. 10-2018-0080196 filed on July 10, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present invention relates to a polarizing plate and an optical display comprising the polarizing plate. Background Art

[0005] Liquid crystal displays (LCDs) operate by emitting light through a liquid crystal panel after receiving light from a backlight unit. Because light from the backlight unit is vertically incident on the LCD screen, the sides of the LCD screen have a lower contrast ratio (CR) than the front of the screen. Therefore, development of optical films capable of increasing the side contrast ratio continues.

[0006] This type of optical film is configured so that light from the polarizing film can be diffused by the pattern formed at the interface between the low-refractive-index resin layer and the high-refractive-index resin layer when the light enters the high-refractive-index resin layer from the low-refractive-index resin layer, thereby improving the side contrast ratio. However, this configuration of the optical film alone cannot fully improve the contrast ratio.

[0007] To improve the side contrast ratio, methods have been proposed, such as changing the pattern shape or incorporating particles into the low-refractive-index resin layer or the high-refractive-index resin layer. However, the former method has the following problems: even a slight change in the pattern shape can lead to a sharp change in the side contrast ratio. Furthermore, the latter method has the following problems: an additional process is required to control the refractive index difference between the particles and the resin layer, and the presence of particles can lead to a decrease in optical transparency, such as an increase in haze or a decrease in luminous efficiency.

[0008] The background art of the present invention is disclosed in Japanese Unexamined Patent Publication No. 2006-251659. Summary of the Invention

[0009] One aspect of the present invention is to provide a polarizing plate capable of improving a side contrast ratio of an optical display.

[0010] Another aspect of the present invention is to provide a polarizing plate capable of improving the front contrast ratio of an optical display.

[0011] Another aspect of the present invention is to provide a polarizing plate that can significantly improve the side contrast ratio of an optical display without incorporating particles into a pattern layer and thereby prevent a reduction in optical transparency (e.g., increased haze) due to the presence of particles, while preventing the emission of polarized light from being obstructed due to the presence of particles, thereby improving luminous efficiency.

[0012] Another aspect of the present invention is to provide an optical display comprising the polarizing plate of the present invention.

[0013] According to one aspect of the present invention, a polarizing plate is provided, comprising: a polarizing film; a first base layer; and a pattern layer, wherein the first base layer and the pattern layer are sequentially formed on a light-emitting surface of the polarizing film, wherein the pattern layer comprises a first layer and a second layer sequentially formed on the first base layer, the first layer having a higher refractive index than the second layer, and wherein the first layer comprises a patterned portion formed at at least a portion thereof facing the second layer, wherein the patterned portion comprises at least two optical patterns and a flat interval between the optical patterns adjacent to each other.

[0014] According to another aspect of the present invention, an optical display including the polarizing plate of the present invention is provided.

[0015] The present invention provides a polarizing plate capable of improving the side contrast ratio of an optical display.

[0016] The present invention provides a polarizing plate capable of improving the front contrast ratio of an optical display.

[0017] The present invention provides a polarizing plate that can significantly improve the lateral contrast ratio of an optical display without incorporating particles into a pattern layer and thus prevent the reduction in optical transparency (e.g., increase in haze) caused by the presence of particles, while preventing the emission of polarized light from being blocked due to the presence of particles, thereby improving luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention.

[0019] Figure 2 is an exploded perspective view of a pattern layer of a polarizing plate according to an embodiment.

[0020] Figure 3 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0021] Figure 4 It is a cross-sectional view of the polarizing plate according to Comparative Example 2 or Comparative Example 4. DETAILED DESCRIPTION

[0022] Embodiments of the present invention will be described in detail with reference to the accompanying drawings to provide a thorough understanding of the present invention to those skilled in the art. It should be understood that the present invention can be embodied in various ways and is not limited to the following embodiments. In the drawings, portions not relevant to the description will be omitted for clarity. Similar components will be represented by similar reference numerals throughout this specification.

[0023] As used herein, spatially relative terms such as "upper" and "lower" are defined with reference to the accompanying drawings. Thus, it should be understood that the term "upper surface" is used interchangeably with the term "lower surface," and that when an element, such as a layer or film, is referred to as being "on" another element, the element may be directly on the other element, or intervening elements may be present. On the other hand, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0024] Herein, the terms "horizontal direction" and "vertical direction" refer to the longitudinal direction and the lateral direction of the rectangular screen of the liquid crystal display, respectively. Herein, "side" refers to (0°, 60°) in a spherical coordinate system represented by (φ, θ), where the horizontal direction is referenced, "front" is represented by (0°, 0°), the left endpoint is represented by (180°, 90°), and the right endpoint is represented by (0°, 90°).

[0025] Herein, "aspect ratio" refers to the ratio of the maximum height of an optical pattern to its maximum width (maximum height / maximum width).

[0026] Herein, “pitch” refers to the distance between a pair of adjacent optical patterns, for example, the sum of the maximum width W of an optical pattern and the width L of a flat section adjacent to the optical pattern.

[0027] Herein, the "bottommost portion" refers to the lowest portion in the engraved optical pattern, and may be a point or a plane.

[0028] Herein, "in-plane retardation (Re)" is a value measured at a wavelength of 550 nanometers and is represented by Equation A:

[0029] Re=(nx-ny)×d,---(A)

[0030] wherein nx and ny are the refractive indices of the slow axis and the fast axis of the corresponding protective layer or base layer at a wavelength of 550 nanometers, respectively, and d is the thickness of the protective layer or base layer (unit: nanometer).

[0031] As used herein, the term "(meth)acryl" refers to acryl and / or methacryl.

[0032] Herein, “X to Y” means “X or greater than X to Y or less than Y” or “≥X and ≤Y”.

[0033] The inventors of the present invention have discovered that, compared to a typical polarizing plate that does not include a patterned layer, a polarizing plate in which a first base layer and a patterned layer, described in detail below, are sequentially stacked on the light-exiting surface of a polarizing film can significantly improve the side contrast ratio of an optical display while minimizing a decrease in the front contrast ratio, and have therefore completed the present invention. Furthermore, the inventors of the present invention have discovered that a polarizing plate in which a first base layer and a patterned layer, described in detail below, are sequentially stacked on the light-exiting surface of a polarizing film can significantly improve the side contrast ratio of an optical display simply by controlling the relationship between the layers in the patterned layer in terms of refractive index, and have therefore completed the present invention.

[0034] In the following, reference will be made to Figure 1 and Figure 2 A polarizing plate according to one embodiment of the present invention is described. Figure 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention, and Figure 2 yes Figure 1 An exploded perspective view of the pattern layer shown in FIG.

[0035] See Figure 1 The polarizing plate 10 may include a polarizing film 100 , a first base layer 200 , a pattern layer 300 and a second base layer 400 .

[0036] Polarizing film

[0037] The first base layer 200, the pattern layer 300 and the second base layer 400 are sequentially formed on the light emitting surface of the polarizing film 100. The polarizing film 100 can make the light emitted from the liquid crystal panel ( Figure 1 The polarized light from the polarizing film 100 may pass through the first base layer 200, the pattern layer 300, and the second base layer 400 in the stated order.

[0038] In one embodiment, the polarizing film 100 may include a polarizer. Specifically, the polarizer may include a polyvinyl alcohol-based polarizer prepared by uniaxially stretching a polyvinyl alcohol film, or a polyene-based polarizer prepared by dehydrating a polyvinyl alcohol film. The polarizer may have a thickness of 5 to 40 microns, for example, 5, 10, 15, 20, 25, 30, 35, or 40 microns. Within this range, the polarizer can be used in optical displays.

[0039] In another embodiment, the polarizing film 100 may further include a base layer formed on at least one surface of the polarizer. The base layer can improve the reliability of the polarizer by protecting the polarizer and enhance the mechanical strength of the polarizer. The base layer may include at least one of an optically transparent protective film or an optically transparent protective coating. The base layer may be described below.

[0040] although Figure 1 Although not shown, at least one of the aforementioned base layer and adhesive layer may be further stacked on the light incident surface of the polarizing film 100. The adhesive layer may adhesively attach the polarizing plate to an adherend, such as a liquid crystal panel, an OLED panel, and the like.

[0041] First base layer

[0042] The first base layer 200 is formed on the light incident surface of the pattern layer 300 and can support the pattern layer 300. The first base layer 200 can be formed directly on the first layer 310 of the pattern layer 300, thereby reducing the thickness of the polarizing plate 10. Herein, the expression "formed directly on..." means that no adhesive layer, bonding layer, or adhesive bonding layer is interposed between the first base layer 200 and the pattern layer 300. However, it should be understood that the present invention is not limited thereto and the first base layer can be formed on the first layer via an adhesive layer, bonding layer, or adhesive bonding layer.

[0043] The total transmittance of the first base layer 200 may be 90% or greater, for example, 90% to 100%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, as measured in the visible region. Within this range, the first base layer can transmit incident light without affecting the incident light.

[0044] The first base layer 200 may be a protective film or a protective coating, which includes a light incident surface and a light exiting surface opposite to the light incident surface. Preferably, the protective film is used as the first base layer to more stably support the pattern layer.

[0045] When the first base layer is a protective film, the first base layer may include a single layer of optically transparent resin film. However, it should be understood that the present invention is not limited thereto and the first base layer may include a multilayer optically transparent resin film. The protective film can be prepared by melt-extruding the resin. A process for stretching the resin may be further added. The resin may include at least one of the following: a cellulose ester resin, such as triacetylcellulose (TAC); a cyclic polyolefin resin, such as an amorphous cyclic olefin polymer (COP); a polycarbonate resin; a polyester resin, such as polyethylene terephthalate (PET); a polyethersulfone resin; a polysulfone resin; a polyamide resin; a polyimide resin; a non-cyclic polyolefin resin; a poly(meth)acrylate resin, such as poly(methyl methacrylate) resin; a polyvinyl alcohol resin; a polyvinyl chloride resin; and a polyvinylidene chloride resin.

[0046] Although the protective film can be a non-stretched film, the protective film can be a retardation film or an isotropic optical film obtained by stretching the resin by a predetermined method and having a certain range of retardation. In one embodiment, the protective film can be an isotropic optical film having an in-plane retardation of 60 nanometers or less, specifically 0 nanometers to 60 nanometers, more specifically 40 nanometers to 60 nanometers, for example 40 nanometers, 41 nanometers, 42 nanometers, 43 nanometers, 44 nanometers, 45 nanometers, 46 nanometers, 47 nanometers, 48 ​​nanometers, 49 nanometers, 50 nanometers, 51 nanometers, 52 nanometers, 53 nanometers, 54 nanometers, 55 nanometers, 56 nanometers, 57 nanometers, 58 nanometers, 59 nanometers or 60 nanometers. Within this range, the polarizing plate can provide good image quality through viewing angle compensation. In this article, "isotropic optical film" refers to a film having substantially the same nx, ny and nz, and the expression "substantially the same" not only includes the case where nx, ny and nz are exactly the same, but also includes the case where there is an acceptable error tolerance between nx, ny and nz. In addition, the protective film can be stretched unidirectionally to prevent rainbow spots from being generated on the protective film.

[0047] In one embodiment, the in-plane retardation of the first base layer may be 15,000 nm or less, specifically 3,000 nm to 15,000 nm, specifically 4,000 nm or more, more specifically 5,000 nm or more, and even more specifically 6,000 nm to 15,000 nm or 8,000 nm to 15,000 nm, for example, 8,000 nm, 9,000 nm, 10,000 nm, 11,000 nm, 12,000 nm, 13,000 nm, 14,000 nm, or 15,000 nm. Within this range, the patterned layer can further diffuse light passing through the first base layer, thereby improving the contrast ratio of the optical display.

[0048] The protective coating layer may be formed from an actinic radiation-curable resin composition comprising an actinic radiation-curable compound and a polymerization initiator. The actinic radiation-curable compound may comprise at least one of a cationically polymerizable curable compound, a free radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy compound having at least one epoxy group per molecule or an oxetane compound having at least one oxetane ring per molecule. The epoxy compound may comprise at least one of a hydrogenated epoxy compound, a linear aliphatic epoxy compound, a cyclic aliphatic epoxy compound, and an aromatic epoxy compound.

[0049] Examples of free radical polymerizable curable compounds may include (meth)acrylate monomers having at least one (meth)acryloyloxy group per molecule and (meth)acrylate oligomers having at least two (meth)acryloyloxy groups per molecule, which can be obtained by reacting at least two compounds containing functional groups. Examples of (meth)acrylate monomers may include monofunctional (meth)acrylate monomers having one (meth)acryloyloxy group per molecule, difunctional (meth)acrylate monomers having two (meth)acryloyloxy groups per molecule, and polyfunctional (meth)acrylate monomers having three or more (meth)acryloyloxy groups per molecule. Examples of (meth)acrylate oligomers may include urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, and epoxy (meth)acrylate oligomers. A polymerization initiator may cure the actinic radiation curable compound. The polymerization initiator may include at least one of an optical cationic initiator and a photosensitizer. Each of the optical cationic initiator and the photosensitizer may be any one generally known in the art.

[0050] The thickness of the first base layer 200 can be 5 to 200 microns, specifically 30 to 120 microns. More specifically, the thickness of the first base layer 200 of a protective film type can be 30 to 100 microns, preferably 30 to 90 microns, such as 30, 40, 50, 60, 70, 80, or 90 microns. The thickness of the first base layer 200 of a protective coating type can be 1 to 50 microns, such as 1, 5, 10, 20, 30, 40, or 50 microns. Within this range, the first base layer 200 can be used in a polarizing plate.

[0051] The first base layer 200 may have a surface treatment layer formed on at least one surface thereof. These surface treatment layers include, for example, a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low-reflectivity layer, and an ultra-low-reflectivity layer. The hard coating layer, anti-fingerprint layer, and anti-reflection layer can provide additional functionality to the first base layer, polarizing film, and the like. Specifically, the primer layer can improve the bonding of the first base layer to an adherend (e.g., a patterned layer or polarizing film).

[0052] Pattern layer

[0053] The pattern layer 300 may be formed on the light exiting surface of the first base layer 200 and may diffuse light passing through the first base layer 200 .

[0054] The pattern layer 300 may include a first layer 310 and a second layer 320 opposite to the first layer 310. Preferably, the pattern layer 300 includes only the first layer 310 and the second layer 320.

[0055] The first layer 310 has a higher refractive index than the second layer 320. The first layer 310 may include a patterned portion formed at least at a portion of the first layer facing the second layer 320, and may include at least two patterned optical patterns 311 and a flat area 312 between adjacent patterned optical patterns 311. In this manner, the polarizing plate can significantly improve the side contrast ratio with respect to light from the first base layer 200. The inventors of the present invention have discovered that when the second layer 320 of the patterned layer 300 has a higher refractive index than the first layer 310, or when the polarizing film 100 is formed adjacent to the second layer 320, the effect of improving the side contrast ratio can be significantly reduced.

[0056] The first layer 310 is formed directly on the second layer 320, and a patterned portion described in detail below is formed at the interface between the first layer 310 and the second layer 320. Figure 1 , the patterned portion is shown as being formed on the entire contact surface between the first layer 310 and the second layer 320. However, it should be understood that the present invention is not limited thereto and the patterned portion may be partially formed on the contact surface between the first layer 310 and the second layer 320.

[0057] The patterned portion includes at least two patterned optical patterns 311 and flat sections 312 between adjacent patterned optical patterns 311. The polarizing plate includes a repeated combination of patterned optical patterns 311 and flat sections 312. Herein, a "patterned optical pattern" refers to an optical pattern that protrudes toward the light-emitting surface of the first base layer 200.

[0058] The patterned portion may satisfy Relationship 1. When the patterned portion satisfies Relationship 1, the polarizing plate may further improve the side contrast ratio of the optical display.

[0059] <Relationship 1>

[0060] 1 <C / P≤10,---(1)

[0061] Wherein C represents the pitch of the patterned portion (unit: micrometer), and P represents the maximum width of the optical pattern (unit: micrometer).

[0062] Preferably, the value of C / P (ratio of C to P) is from 1.1 to 8.0, specifically from 1.1 to 5.0, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.

[0063] The patterned optical pattern 311 has a curved surface. Polarized light from the first layer 310 enters the second layer 320 via the curved surface. Utilizing the curved surface, the patterned optical pattern allows light that has passed through the first base layer 200 and the first layer 310 to enter the second layer 320 in various directions depending on the point at which the light is incident on the patterned optical pattern 311.

[0064] Figure 1 A polarizing plate is shown in which the curved surface is aspherical and the patterned optical pattern 311 is a lenticular lens pattern. However, it should be understood that the present invention is not limited thereto and that the curved surface may be spherical, parabolic, ellipsoidal, hyperbolic, or amorphous. Although the patterned optical pattern is shown as having a flat curved surface, the patterned optical pattern may have unevenness to further improve light diffusion.

[0065] As an alternative to the lenticular lens pattern, the engraved optical pattern 311 may be: a pattern including one flat surface and flat inclined surfaces formed at its bottommost portion and having a trapezoidal cross section (e.g., a truncated prism shape having a triangular cross section (a cut prism shape)); an engraved pattern including one flat surface and curved inclined surfaces formed at its bottommost portion (e.g., a pattern formed by truncating a flat surface and having a curved inclined surface); Figure 1 a cut lenticular lens pattern or a truncated microlens (cut microlens) pattern obtained by cutting the bottom of a lenticular lens pattern; or a pattern with an N-sided polygonal cross-section (N is an integer from 3 to 20) such as a rectangular cross-section or a square cross-section.

[0066] The aspect ratio of the patterned optical pattern 311 can be greater than 0 and less than or equal to 3.0, specifically 0.4 to 3.0, more specifically 0.7 to 3.0, such as 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0. Within this range, the polarizing plate can improve the side contrast ratio and side viewing angle of the optical display.

[0067] The maximum width P of the patterned optical pattern 311 can be greater than 0 micrometers and less than or equal to 15 micrometers, specifically 2 micrometers to 15 micrometers, such as 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, 11 micrometers, 12 micrometers, 13 micrometers, 14 micrometers, or 15 micrometers. The maximum height H of the patterned optical pattern 311 can be greater than 0 micrometers and less than or equal to 50 micrometers, specifically 1 micrometer to 45 micrometers, such as 1 micrometer, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, or 45 micrometers. Within these maximum width and maximum height ranges, the patterned optical pattern can provide light diffusion.

[0068] The ratio of the sum of the maximum widths of the patterned optical patterns 311 to the total width of the first layer 310 can be 40% to 60%, specifically 45% to 55%, such as 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%. Within this range, the polarizer can improve the side contrast ratio and side viewing angle of the optical display. The patterned optical patterns 311 can be arranged at a predetermined pitch C to further diffuse the condensed light. The patterned optical patterns 311 can be arranged at a pitch C greater than 0 micrometers and 60 micrometers or less, specifically 5 micrometers to 60 micrometers, such as 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, or 60 micrometers. Within this range, the polarizer can provide further improved light condensation and diffusion.

[0069] The ratio of the maximum width P of the engraved optical pattern 311 to the width L of the flat interval 312 may have a value greater than 0 and less than or equal to 9, specifically 0.1 to 3, more specifically 0.15 to 2, for example, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95 or 2. Within this range, the polarizing plate can reduce the difference between the front contrast ratio and the side contrast ratio of the optical display, while improving the contrast ratio of the optical display at a given side viewing angle and a given front viewing angle. In addition, the polarizing plate can prevent the moiré phenomenon.

[0070] The minimum distance between the patterned optical pattern 311 and the first base layer 200, that is, the minimum distance D between the bottommost portion of the patterned optical pattern 311 and the first base layer 200 (also referred to as "wall thickness"), can be greater than 0 μm and less than or equal to 30 μm, specifically 1 μm to 20 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm. Within this range, uniformity of film hardness and coating thickness can be ensured.

[0071] The ratio (H / A) of the maximum height H of the patterned optical pattern 311 to the distance A between the uppermost surface of the pattern layer 300 and the lowermost portion of the patterned optical pattern 311 may be greater than 0 and less than or equal to 1, specifically, 0.3 to 1.0, such as 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0. Within this range, uniformity of film hardness and coating thickness can be ensured.

[0072] In the cross-sectional area of ​​the pattern layer 300, the ratio of the sum of the cross-sectional areas of the filling patterns 321 of the second layer 320 to the total cross-sectional area of ​​the first layer 310 can be 40% to 60%, preferably 45% to 55%, for example, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%. Within this range, the polarizing plate can improve the side visibility of the optical display.

[0073] The second layer 320 includes a filling pattern 321 formed at the interface with the first layer 310 and filling at least a portion of the engraved optical pattern 311. The filling pattern 321 may completely fill the optical pattern or partially fill the optical pattern. Preferably, the filling pattern 321 completely fills the engraved optical pattern 311.

[0074] Although Figure 1 , the polarizing plate is shown to include engraved optical patterns having the same aspect ratio, maximum width, maximum height, and pitch, but it should be understood that the present invention is not limited thereto and the polarizing plate may include engraved optical patterns having different aspect ratios, maximum width, maximum height, and pitch.

[0075] The flat interval 312 may be formed between adjacent engraved optical patterns 311. The flat interval 312 allows polarized light from the first layer 310 to directly enter the second layer 320 therethrough, thereby improving the front contrast ratio and front brightness of the optical display.

[0076] Polarized light from the first base layer 200 is transmitted from the first layer 310 to the second layer 320, with the protrusions of the engraved optical pattern 311 facing the first base layer 200. The width L of the flat section 312 can be greater than 0 μm and less than or equal to 50 μm, specifically greater than 0 μm and less than or equal to 30 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, or 30 μm. Within this range, the polarizing plate can provide photopolymerization and diffusion.

[0077] Although Figure 1 In FIG. 1 , the polarizing plate is shown to include flat sections having the same width, but it should be understood that the present invention is not limited thereto and the polarizing plate may include flat sections having different widths.

[0078] See Figure 2 The patterned optical pattern 311 can extend in a stripe shape in its longitudinal direction. In this way, the polarizing plate can increase the side viewing angle of the optical display. Alternatively, the patterned optical pattern can be formed in a dot shape. In this context, the term "dot" means that the optical pattern is dispersed.

[0079] The first layer 310 has a higher refractive index than the second layer 320. The inventors of the present invention have discovered that the side contrast ratio of an optical display can be significantly improved by allowing polarized light from the polarizing film 100 to be transmitted through the first layer 310 to the second layer 320, and by including the first layer 310 with an engraved optical pattern 311 protruding toward the polarizing film 100. The refractive index difference between the first layer 310 and the second layer 320 can be 0.05 or greater, specifically 0.05 to 0.3, more specifically 0.05 to 0.2, such as 0.1 to 0.2. Within this range, the polarizing plate can further improve the side contrast ratio of the optical display.

[0080] The refractive index of the first layer 310 may be 1.50 or greater, specifically 1.50 to 1.70, more specifically 1.50 to 1.65. Within this range, the polarizing plate can improve the side contrast ratio of the optical display. The refractive index of the second layer 320 may be greater than 0 and less than 1.50, specifically greater than or equal to 1.3 and less than 1.50, more specifically greater than or equal to 1.35 and less than 1.50. Within this range, the polarizing plate can improve the side contrast ratio of the optical display.

[0081] The first layer 310 may be formed from a composition comprising a resin having a refractive index within the aforementioned range. For example, the first layer may comprise a UV-curable or thermally curable resin, such as, but not limited to, at least one of a (meth)acrylic resin, an epoxy resin, a urethane resin, and a silicone resin. The composition may further comprise various additives, such as an initiator to accelerate the curing of the resin.

[0082] In one embodiment, the first layer can be a particle-free resin layer. Generally, in order to improve the side contrast ratio of an optical display, a method has been proposed to incorporate high refractive index particles (having a higher refractive index than the first layer) into the high refractive index layer. The high refractive index particles are, for example, light diffusers, light absorbers, etc. According to the present invention, by adjusting the stacking relationship between the first layer and the second layer relative to the light exit surface of the polarizing film and the protrusion direction of the engraved optical pattern, the side contrast ratio can be significantly improved without incorporating these particles into the first layer, and thus the optical transparency and luminous efficiency of the optical display can be further improved. The haze of the polarizing plate can be 0% to 30%, specifically 0% to 25%, for example, 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%.

[0083] The second layer 320 may be formed from a composition comprising a resin having a refractive index within the aforementioned range. For example, the second layer may comprise a UV-curable or thermally curable resin, such as, but not limited to, at least one of a (meth)acrylic resin, an epoxy resin, a urethane resin, and a silicone resin. The composition may further comprise various additives, such as an initiator to accelerate the curing of the resin.

[0084] In one embodiment, the second layer may be a particle-free resin layer. Generally, to improve the side contrast ratio of optical displays, a method has been proposed of incorporating particles, such as light diffusers and light absorbers, into the second layer. According to the present invention, by adjusting the stacking relationship between the first and second layers relative to the light-emitting surface of the polarizing film and the protrusion direction of the engraved optical pattern, the side contrast ratio can be significantly improved without incorporating these particles into the second layer.

[0085] In one embodiment, the second layer can be formed from a binder composition that exhibits bonding properties after curing to provide bonding properties. Thus, the second layer can be directly bonded to the second base layer, thereby reducing the thickness of the polarizing plate. The second layer can have good bonding properties relative to the second base layer (particularly a polyester film).

[0086] The pattern layer 300 may have a thickness greater than 0 micrometer and less than or equal to 200 micrometers, specifically 10 to 150 micrometers, such as 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 150 micrometers. Within this range, the pattern layer can be used in a polarizing plate.

[0087] Second base layer

[0088] The second base layer 400 may be formed on the light-emitting surface of the pattern layer 300 to transmit light from the pattern layer 300 therethrough. The second base layer 400 may be formed directly on the second layer 320 of the pattern layer 300, thereby reducing the thickness of the polarizing plate 10. Herein, the expression "formed directly on..." means that no adhesive layer, bonding layer, or adhesive bonding layer is interposed between the second base layer 400 and the pattern layer 300. However, it should be understood that the present invention is not limited thereto and the second base layer may be formed on the second layer via an adhesive layer, bonding layer, or adhesive bonding layer.

[0089] The material, thickness, refractive index, and retardation of the second base layer 400 may be the same as or different from those of the first base layer 200 .

[0090] In one embodiment, the in-plane retardation of the second base layer may be 15,000 nm or less, specifically 3,000 nm to 15,000 nm, more specifically 4,000 nm or greater, yet more specifically 5,000 nm or greater, yet more specifically 6,000 nm to 15,000 nm or 8,000 nm to 15,000 nm, for example 8,000 nm, 9,000 nm, 10,000 nm, 11,000 nm, 12,000 nm, 13,000 nm, 14,000 nm, or 15,000 nm. Within this range, the polarizing plate can further diffuse light diffused by the contrast-enhancing layer, thereby further improving the contrast ratio of the optical display. In one embodiment, when the in-plane retardation values ​​of the first and second base layers are within the aforementioned ranges, the polarizing plate can further improve the contrast ratio of the optical display.

[0091] Although Figure 1 Although not shown, a functional layer may be further formed on the light-emitting surface of the second base layer 400. The functional layer may provide additional functionality to the polarizing plate. For example, the functional layer may include at least one of the following: a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflectivity layer, and an ultra-low reflectivity layer, but is not limited thereto.

[0092] Although the polarizing plate is shown as including the Figure 1 The second base layer 400 is formed on the pattern layer in the embodiment of the present invention, but it should be understood that the present invention is not limited thereto and the second base layer may be omitted. In this case, the uppermost surface of the second layer may serve as a functional layer. In this context, the expression "serving as a functional layer" means that the uppermost surface of the second layer serves as at least one of the following: a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflectivity layer, and an ultra-low reflectivity layer. In this context, the second layer may serve as a functional layer by undergoing surface treatment during its formation.

[0093] Next, we will refer to Figure 3 A polarizing plate according to another embodiment of the present invention is described.

[0094] See Figure 3 The polarizing plate 20 according to this embodiment may include a pattern layer 300A. The polarizing plate 20 according to this embodiment is substantially the same as the polarizing plate 10 according to the above embodiment, except that a pattern layer 300A is formed instead of the pattern layer 300.

[0095] The pattern layer 300A includes a first layer 310A; and a second layer 320A formed directly on the first layer 310A, wherein a patterned portion described in detail below is formed at an interface between the first layer 310A and the second layer 320A.

[0096] The patterned portion includes at least two patterned optical patterns 311A ​​and flat sections 312A between adjacent patterned optical patterns 311A. The polarizing plate includes a repeating combination of patterned optical patterns 311A ​​and flat sections 312A at the interface between the first layer 310A and the second layer 320A. As used herein, a "patterned optical pattern" refers to an optical pattern that protrudes toward the first base layer 200.

[0097] The patterned portion may satisfy Equation 1, and the patterned optical pattern 311A ​​may have a base angle θ of 60° to 90°. Herein, base angle θ refers to the angle formed between the inclined surface of the patterned optical pattern 311A ​​and the maximum width P1 of the patterned optical pattern 311A. Herein, inclined surface 313A refers to the inclined surface of the patterned optical pattern 311A ​​directly connected to the flat section 312A. When the patterned portion satisfies Equation 1 and the base angle of the patterned optical pattern is within the aforementioned range, the polarizing plate can improve the side contrast ratio of the optical display while increasing the contrast ratio of the optical display at a given side viewing angle. Specifically, the value of the base angle θ of the engraved optical pattern may be 70° to 90°, and the value of C1 / P1 (the ratio of C1 to P1) may be 1.1 to 8.0, for example, 1.1 to 5.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.

[0098] <Relationship 1>

[0099] 1 <C1 / P1≤10,---(1)

[0100] Wherein C1 represents the pitch of the patterned portion (unit: micrometer), and P1 represents the maximum width of the optical pattern (unit: micrometer).

[0101] Although the engraved optical pattern 311A ​​is shown as Figure 3 The pattern has the same base angle at both sides thereof, but the engraved optical pattern may have different base angles as long as the base angle is within the range of 60° to 90° as described above.

[0102] The patterned optical pattern 311A ​​may be a patterned optical pattern including a first surface 314A formed at a bottommost portion thereof and at least one inclined surface 313A connected to the first surface 314A. Figure 3 , the patterned optical pattern is shown as a trapezoidal optical pattern in which two adjacent inclined surfaces 313A are connected by a first surface 314A, but it should be understood that the present invention is not limited thereto and the patterned optical pattern may be an optical pattern having a rectangular cross-section or a square cross-section.

[0103] First surface 314A is formed at the bottommost portion of the engraved optical pattern and can improve the viewing angle and brightness of the optical display by further diffusing light reaching first layer 310A. Therefore, the polarizing plate according to this embodiment can improve light diffusion, thereby minimizing brightness loss. First surface 314A can be flat to facilitate the manufacture of the polarizing plate. However, it should be understood that the present invention is not limited to this and first surface 314A can have slight unevenness or can be a curved surface.

[0104] The first surface 314A may be parallel to at least one of the flat section 312A, the lowermost surface of the first layer 310A, and the uppermost surface of the second layer 320A.

[0105] The width of the first surface 314A can be 0.5 microns to 30 microns, specifically 1 micron to 15 microns, such as 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns, or 15 microns. Within this range, the polarizing plate can be used in an optical display and can improve the contrast ratio of the optical display.

[0106] The aspect ratio of the patterned optical pattern 311A ​​can be greater than 0 and less than or equal to 3.0, specifically 0.4 to 3.0, more specifically 0.7 to 3.0, such as 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0. The patterned optical pattern within this range can improve the side contrast ratio and side viewing angle of the optical display.

[0107] The maximum height H1 of the engraved optical pattern 311A ​​can be greater than 0 micrometers and less than or equal to 50 micrometers, specifically 1 micrometer to 45 micrometers, such as 1 micrometer, 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, or 45 micrometers. Within this range, the polarizing plate can improve the contrast ratio, viewing angle, and brightness of the optical display while preventing moire.

[0108] The maximum width P1 of the engraved optical pattern 311A ​​can be greater than 0 micrometers and less than or equal to 15 micrometers, specifically 2 micrometers to 15 micrometers, such as 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, 11 micrometers, 12 micrometers, 13 micrometers, 14 micrometers, or 15 micrometers. Within this range, the polarizing plate can improve the contrast ratio, viewing angle, and brightness of the optical display while preventing moire.

[0109] The minimum distance between the patterned optical pattern 311A ​​and the first base layer 200, that is, the minimum distance D1 between the bottommost portion of the patterned optical pattern 311A ​​and the first base layer 200 (also referred to as "wall thickness") can be 0 to 30 μm, specifically 1 to 20 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm. Within this range, uniformity of film hardness and coating thickness can be ensured.

[0110] The ratio of the sum of the maximum widths of the engraved optical patterns 311A ​​to the total width of the first layer 310A can be 40% to 60%, specifically 45% to 55%, for example, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%. Within this range, the polarizing plate can improve the side contrast ratio and side viewing angle of the optical display.

[0111] The ratio (H1 / A1) of the maximum height H1 of the patterned optical pattern 311A ​​to the distance A1 between the uppermost surface of the pattern layer 300A and the lowermost portion of the patterned optical pattern 311A ​​may be greater than 0 and less than or equal to 1, specifically 0.3 to 1.0, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0. Within this range, uniformity of film hardness and coating thickness can be ensured. Figure 3 , the patterned portion is shown as including carved optical patterns having the same base angle, width of the first surface, maximum height, and maximum width. However, it should be understood that the patterned portion may include carved optical patterns having different base angles, width of the first surface, maximum height, and maximum width.

[0112] The flat section 312A allows light passing through the first layer 310A to pass therethrough into the second layer 320A, thereby improving the front brightness of the optical display.

[0113] The ratio of the maximum width P1 of the engraved optical pattern 311A ​​to the width L1 of the flat interval 312A may be greater than 0 and less than or equal to 9, specifically 0.1 to 3, more specifically 0.15 to 2, for example, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95 or 2. Within this range, the difference between the front contrast ratio and the side contrast ratio of the optical display can be reduced, while the contrast ratios of the optical display at a given side viewing angle and a given front viewing angle can be improved. In addition, the moire phenomenon can be prevented.

[0114] The width L1 of the flat section 312A may be greater than 0 μm and less than or equal to 50 μm, specifically greater than 0 μm and less than or equal to 30 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, or 30 μm. Within this range, the polarizing plate can improve the front brightness of the optical display.

[0115] The maximum width of a patterned optical pattern 311A ​​and an adjacent flat section 312A forms a spacing (C1). The patterned optical patterns can be arranged at a spacing C1 greater than 0 microns and less than or equal to 60 microns, specifically 5 to 60 microns, such as 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 microns. Within this range, the polarizing plate can improve the contrast ratio of an optical display while preventing moire.

[0116] In the cross-sectional area of ​​the pattern layer 300A, the ratio of the sum of the cross-sectional areas of the filling patterns 321A of the second layer 312A to the total cross-sectional area of ​​the first layer 311A ​​can be 40% to 60%, specifically 45% to 55%, for example, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%. Within this range, the polarizing plate can improve the side visibility of the optical display.

[0117] Although Figure 3 In FIG, the patterned portion is shown as including patterned optical patterns having the same pitch and maximum width, but the patterned portion can include patterned optical patterns having different pitches and maximum widths.

[0118] The optical display according to the present invention may include the polarizing plate according to the present invention. In one embodiment, the optical display may be a liquid crystal display or a light emitting device display.

[0119] In one embodiment, the polarizing plate 10 can be used as an observer-side polarizing plate in a liquid crystal display. Herein, the term "observer-side polarizing plate" means a polarizing plate disposed at the observer side relative to the liquid crystal panel and opposite to the light source.

[0120] In one embodiment, a liquid crystal display includes a backlight unit, a first polarizing plate, a liquid crystal panel, and a second polarizing plate, and is stacked in the order stated, wherein the second polarizing plate may include a polarizing plate according to the present invention. The liquid crystal panel may adopt a vertical alignment (VA) mode, an IPS mode, a patterned vertical alignment (PVA) mode, or a super-patterned vertical alignment (S-PVA) mode, but is not limited thereto. In another embodiment, the polarizing plate according to the present invention may be used as a light source side polarizing plate. In this article, the term "light source side polarizing plate" refers to a polarizing plate disposed at the light source side relative to the liquid crystal panel. In another embodiment, the polarizing plate according to the present invention may be used as an observer side polarizing plate and a light source side polarizing plate relative to the liquid crystal panel.

[0121] Next, the present invention will be described in more detail with reference to some examples. However, it should be noted that these examples are provided for illustration only and should not be understood in any way as limiting the present invention.

[0122] Example 1

[0123] A resin (SSC-6000, SHIN-AT&C Co., Ltd., South Korea) was used as a high refractive index layer composition (not containing particles). Herein, the high refractive index layer composition may further include a predetermined solvent.

[0124] A resin (SSC-4000, Shinan Co., Ltd., South Korea) was used as the low refractive index layer composition (not containing particles). Herein, the low refractive index layer composition may further include a predetermined solvent.

[0125] The high refractive index layer composition for the first base layer was applied to the upper surface of a transparent PET film (super birefringent film (SRF), Toyobo Co., Ltd., thickness: 80 microns, in-plane retardation = 8,000 nanometers) to a predetermined thickness. Subsequently, a film having a pattern and flat areas formed alternately thereon was applied to the coating to transfer the pattern to the coating, followed by curing via UV radiation, thereby forming a first layer containing a patterned portion as shown in Table 1, in which the engraved optical pattern and the flat areas were alternately arranged. A low refractive index layer composition was applied to the first layer to completely fill the engraved optical pattern.

[0126] Subsequently, a coating layer was laminated on one surface of a transparent PET film for a second base layer (SRF, Toyobo Co., Ltd., thickness: 80 μm, in-plane retardation = 8,000 nm) having an antireflection layer formed on the other surface thereof, and then cured via UV irradiation, thereby forming a second base layer on the pattern layer.

[0127] The polarizer was manufactured by stretching a polyvinyl alcohol film to 3 times its original length at 60° C., adsorbing iodine onto the stretched film, and then stretching the film to 2.5 times the stretched length in a boric acid aqueous solution at 40° C.

[0128] The polarizing plate was manufactured by bonding a polarizer to the lower surface of the transparent PET film for the first base layer using a UV curable bonding agent.

[0129] The manufactured polarizing plate has the following structure: a first base layer, a first layer (high refractive index layer), a second layer (low refractive index layer) and a second base layer are sequentially stacked on the light exiting surface of the polarizer, and the engraved optical pattern protrudes toward the first base layer.

[0130] Example 2

[0131] A resin (SSC-5500, Shinan Co., Ltd., South Korea) was used as a high refractive index layer composition (not containing particles). Herein, the high refractive index layer composition may further include a predetermined solvent.

[0132] A resin (SSC-4500, Shinan Co., Ltd., South Korea) was used as the low refractive index layer composition (not containing particles). Herein, the low refractive index layer composition may further include a predetermined solvent.

[0133] A polarizing plate was manufactured in the same manner as in Example 1, except that the refractive indices of the first layer and the second layer were changed using the high refractive index layer composition and the low refractive index layer composition, as shown in Table 2.

[0134] Example 3

[0135] A polarizing plate was manufactured in the same manner as in Example 1, except that the engraved optical pattern and the flat area were changed, as shown in Table 1.

[0136] Example 4

[0137] A polarizing plate was manufactured in the same manner as in Example 3, except that the refractive indices of the first layer and the second layer were changed using the high refractive index layer composition and the low refractive index layer composition used in Example 2, as shown in Table 2.

[0138] Comparative Example 1

[0139] A polarizer was prepared by stretching a polyvinyl alcohol film to 3 times its original length at 60° C., adsorbing iodine onto the stretched film, and then stretching the film to 2.5 times the stretched length in an aqueous boric acid solution at 40° C. A polarizing plate was manufactured by bonding a transparent PET film (SRF, Toyobo Co., Ltd., thickness: 80 μm, in-plane retardation = 14,000 nm) for a first base layer to the upper surface of the prepared polarizer using a UV-curable bonding agent.

[0140] Comparative Example 2

[0141] One surface of a transparent PET film (SRF, Toyobo Co., Ltd., thickness: 80 microns, in-plane retardation = 8,000 nanometers) used as the second base layer was coated with a predetermined thickness of the high refractive index layer composition of Example 1, which had an antireflection layer formed on its other surface. Subsequently, a film having a pattern and flat areas alternately formed thereon was applied to the coating layer to transfer the pattern to the coating layer, followed by curing via UV radiation, thereby forming a high refractive index layer in which the engraved optical pattern and flat areas listed in Table 1 were alternately arranged. Subsequently, the low refractive index layer composition of Example 1 was applied to the high refractive index layer to completely fill the engraved optical pattern.

[0142] Subsequently, the coating layer was laminated on the upper surface of a transparent PET film for the first base layer (SRF, Toyobo Co., Ltd., thickness: 80 μm, in-plane retardation = 8,000 nm), followed by curing. Subsequently, a polarizing plate was manufactured by bonding the polarizer of Example 1 to the lower surface of the transparent PET film for the first base layer using a UV-curable adhesive, followed by curing.

[0143] Figure 4 This is a cross-sectional view of the polarizing plate of Comparative Example 2. Figure 4 The polarizing plate of comparative example 2 includes: a polarizer 100, a first base layer 200, a low refractive index layer 510, a high refractive index layer 520 and a second base layer 400, wherein the first base layer, the low refractive index layer, the high refractive index layer and the second base layer are stacked in sequence on the light emitting surface of the polarizer 100.

[0144] Comparative Example 3

[0145] A polarizing plate was manufactured in the same manner as in Example 1, except that the refractive indices of the first layer and the second layer were changed, as listed in Table 2.

[0146] Comparative Example 4

[0147] A polarizing plate was manufactured in the same manner as in Comparative Example 2, except that the refractive indices of the first and second layers were changed as listed in Table 2, and zirconium oxide was added as high refractive index particles to the high refractive index layer.

[0148] Table 1

[0149]

[0150] The polarizing plates manufactured according to Examples and Comparative Examples were evaluated for the following properties.

[0151] Manufacturing of polarizing plates on the light source side

[0152] The polarizer was prepared by stretching a polyvinyl alcohol film to 3 times its original length at 60°C, adsorbing iodine onto the stretched film, and then stretching the film to 2.5 times its stretched length in a boric acid aqueous solution at 40°C. As a base layer, a triacetyl cellulose film (thickness: 80 microns) was bonded to both surfaces of the polarizer using a binder for polarizing plates (Z-200, Nippon Goshei Co., Ltd.) to produce a polarizer. The manufactured polarizer was used as a light source-side polarizer.

[0153] Manufacturing of LCD modules

[0154] The liquid crystal display module was manufactured by sequentially assembling the manufactured light source side polarizing plate, liquid crystal panel (PVA mode), and polarizing plates manufactured in Examples and Comparative Examples. Here, the assembly was performed so that the second base layer of the polarizing plate was positioned outermost.

[0155] An LED light source, a light guide plate, and a liquid crystal display module were assembled into a liquid crystal display including a single-sided LED light source (having the same configuration as a Samsung TV (55-inch UHD TV (2016 model), model: UN55KS8000F), except that the liquid crystal display module was manufactured using each of the polarizing plates manufactured in the example and the comparative example).

[0156] The luminance in the white mode and the luminance in the black mode were measured at the front (0°, 0°) and the side (0°, 60°) in a spherical coordinate system using a luminance tester EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM).

[0157] The front contrast ratio is calculated as the ratio of the luminance value in white mode to the luminance value in black mode as measured in spherical coordinates (0°, 0°). The side contrast ratio is calculated as the ratio of the luminance value in white mode to the luminance value in black mode as measured in spherical coordinates (0°, 60°).

[0158] In Table 2, the 1 / 2 viewing angle refers to a viewing angle having a luminance of 1 / 2 of the front luminance.

[0159] In Table 2, a 1 / 3 viewing angle refers to a viewing angle having a luminance of 1 / 3 of the front luminance.

[0160] Optical transparency: The optical transparency was measured on each of the polarizing plates manufactured in Examples and Comparative Examples. When the tested polarizing plate had a haze of 0% to 30%, the polarizing plate was evaluated as "translucent", and when the tested polarizing plate had a haze of more than 30%, the polarizing plate was evaluated as "opaque".

[0161] Table 2

[0162]

[0163] *In Table 2, the numerical values ​​in parentheses refer to the percentage of the contrast ratio of each of the liquid crystal displays according to Example and Comparative Example to the contrast ratio of the liquid crystal display according to Comparative Example 1.

[0164] As shown in Table 2, the polarizing plate according to the present invention can significantly improve the side contrast ratio while minimizing the reduction of the front contrast ratio. In addition, the polarizing plate according to the present invention has good optical transparency.

[0165] In contrast, the polarizing plates of Comparative Examples 2 and 3, which do not contain particles and have structures different from those of the polarizing plate according to the present invention, have a reduced front contrast ratio and significantly poorer side contrast ratio improvement compared to the polarizing plate according to the present invention. Furthermore, the polarizing plate of Comparative Example 4 exhibits poor transparency and brightness uniformity.

[0166] It should be understood that those skilled in the art can make various modifications, changes, alterations and equivalent embodiments without departing from the spirit and scope of the present invention.

Claims

1. A polarizing plate, comprising: polarizing film; First base layer; and a pattern layer, wherein the first base layer and the pattern layer are sequentially formed on the light exiting surface of the polarizing film, The pattern layer includes a first layer and a second layer sequentially formed on the first base layer, the first layer has a higher refractive index than the second layer, and wherein the first layer includes a patterned portion formed at at least a portion thereof facing the second layer, the patterned portion including at least two optical patterns and a flat section between the optical patterns adjacent to each other, Each of the optical patterns is a double convex lens pattern protruding toward the first base layer, The patterned portion satisfies equation 1: 1 <C / P≤10,---(1) Wherein C represents the pitch of the patterned portion, and P represents the maximum width of the optical pattern, wherein the units of C and P are: micrometer, Wherein, the minimum distance between the bottom of the optical pattern of the pattern layer and the first base layer is greater than 0 micrometers and less than or equal to 30 micrometers, The level of the flat section is between the top surface of the second layer and the bottom of the optical pattern. The refractive index of the first layer is 1.55 to 1.65 and the refractive index of the second layer is 1.4 to 1.

45. 2 . The polarizing plate according to claim 1 , wherein the first layer is a particle-free resin layer. The polarizing plate according to claim 1 , wherein the second layer is a particle-free resin layer. 4 . The polarizing plate of claim 1 , wherein each of the optical patterns has an aspect ratio greater than 0 and less than or equal to 3.

0. 5 . The polarizing plate of claim 1 , wherein the second layer comprises a filling pattern formed at an interface with the first layer and filling at least a portion of the optical pattern. 6 . The polarizing plate according to claim 5 , wherein a ratio of a sum of cross-sectional areas of the filling patterns of the second layer to a total cross-sectional area of ​​the first layer in a cross-sectional area of ​​the pattern layer is in a range of 40% to 60%. 7 . The polarizing plate according to claim 1 , wherein the first base layer is directly formed on the first layer and has an in-plane retardation of 15,000 nm or less at a wavelength of 550 nm.

8. The polarizing plate according to claim 1, further comprising: A second base layer is formed on the light emitting surface of the second layer. 9 . The polarizing plate of claim 8 , wherein the second base layer is directly formed on the second layer and has an in-plane retardation of 15,000 nm or less at a wavelength of 550 nm.

10. The polarizing plate according to claim 8, wherein the second base layer comprises at least one of a cellulose ester resin, a cyclic polyolefin resin, a polycarbonate resin, a polyester resin, a polyethersulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, a non-cyclic polyolefin resin, a poly(meth)acrylate resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, and a polyvinylidene chloride resin.

11. The polarizing plate according to claim 8, further comprising: a functional layer formed on the light-emitting surface of the second base layer, The functional layer comprises at least one of the following: a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflectivity layer, and an ultra-low reflectivity layer.

12. The polarizing plate according to claim 8, wherein the first base layer is directly formed on the first layer and has an in-plane retardation of 3,000 nm to 15,000 nm at a wavelength of 550 nm, and the second base layer is directly formed on the second layer and has an in-plane retardation of 3,000 nm to 15,000 nm at a wavelength of 550 nm. 13 . The polarizing plate according to claim 1 , wherein the second layer has an uppermost surface serving as a functional layer.

14. An optical display comprising the polarizing plate according to any one of claims 1 to 13.

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