阅读说明：本技术 偏光板和包括偏光板的光学显示器 (Polarizing plate and optical display including the same ) 是由 吴泳 李正浩 魏东镐 于 2019-07-10 设计创作，主要内容包括：本发明提供一种偏光板和一种包含偏光板的光学显示器。偏光板包含：偏光膜；第一基础层；以及图案层,第一基础层和图案层依序形成于偏光膜的光出射表面上,其中图案层包含依序形成于第一基础层上的第一层和第二层,第一层比第二层具有更高的折射率,且其中第一层包含形成在其面向第二层的至少一部分处的图案化部分,图案化部分包含至少两个光学图案和彼此相邻的光学图案之间的平坦区间。(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, a first base layer and the pattern layer being sequentially formed on the light exit surface of the polarizing film, wherein 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 includes a patterned portion formed at least a portion thereof facing the second layer, the patterned portion including at least two optical patterns and a flat zone between the optical patterns adjacent to each other.)

1. A polarizing plate comprising:

a polarizing film; a first base layer; and a pattern layer, the first base layer and the pattern layer being sequentially formed on a light exit surface of the polarizing film,

wherein 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 includes a patterned portion formed at least a portion thereof facing the second layer, the patterned portion including at least two optical patterns and a flat zone between the optical patterns adjacent to each other.

2. The polarizing plate of claim 1, wherein the difference in refractive index between the first layer and the second layer is 0.05 or greater than 0.05.

3. The polarizing plate of claim 1, wherein the first layer is a particle-free resin layer.

4. The polarizing plate of claim 1, wherein the second layer is a particle-free resin layer.

5. The polarizing plate of claim 1, wherein each of the optical patterns comprises at least one of: a lenticular lens pattern; a pattern including one flat surface and a flat inclined surface formed at a bottommost portion of the pattern and having a polygonal cross-section; a pattern including one flat surface and a curved inclined surface formed at a bottommost portion of the pattern; and a pattern having an N-sided polygonal cross-section, wherein N is an integer between 3 and 20.

6. The polarizing plate of claim 1, wherein each of the optical patterns is a lenticular pattern or a pattern including one flat surface and a flat inclined surface formed at the bottommost portion of the pattern and having a polygonal cross-section.

7. The polarizing plate of claim 1, wherein the patterned portion satisfies relation 1:

1<C/P≤10，---(1)

wherein C represents a pitch of the patterned portion and P represents a maximum width of the optical pattern, wherein the units of C and P are: and (3) micron.

8. The polarizing plate of claim 1, wherein each of the optical patterns is an engraved optical pattern comprising one flat surface and a flat inclined surface formed at the bottommost portion thereof and having a polygonal cross section or an engraved lenticular lens pattern.

9. 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.

10. The polarizing plate of claim 1, wherein the pattern layer has a wall thickness greater than 0 microns and less than or equal to 30 microns.

11. The polarizing plate of claim 1, wherein each of the optical patterns is an engraved optical pattern, and the second layer comprises a filling pattern formed at an interface with the first layer and filling at least a portion of the engraved optical pattern.

12. The polarizing plate of claim 11, wherein in a cross-sectional area of the pattern layer, 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 is in a range of 40% to 60%.

13. The polarizing plate of claim 1, wherein the first base layer is formed directly on the first layer and has an in-plane retardation of 15,000 nanometers or less than 15,000 nanometers at a wavelength of 550 nanometers.

14. The polarizing plate of claim 1, further comprising:

a second base layer formed on a light exit surface of the second layer.

15. The polarizing plate of claim 14, wherein the second base layer is formed directly on the second layer and has an in-plane retardation of 15,000 nanometers or less than 15,000 nanometers at a wavelength of 550 nanometers.

16. The polarizing plate of claim 14, wherein the second base layer comprises at least one of: cellulose ester resins, cyclic polyolefin resins, polycarbonate resins, polyester resins, polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, acyclic polyolefin resins, poly (meth) acrylate resins, polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins.

17. The polarizing plate of claim 14, further comprising:

a functional layer formed on a light exit surface of the second base layer,

wherein the functional layer comprises at least one of: a primer layer, a hard coat layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low-reflectance layer, and an ultra-low reflectance layer.

18. The polarizing plate of claim 1, wherein the second layer has an uppermost surface serving as a functional layer.

19. The polarizing plate of claim 14, wherein the first base layer is formed directly on the first layer and has an in-plane retardation of 3,000 to 15,000 nanometers at a wavelength of 550 nanometers, and the second base layer is formed directly on the second layer and has an in-plane retardation of 3,000 to 15,000 nanometers at a wavelength of 550 nanometers.

20. An optical display comprising the polarizing plate of any one of claims 1 to 19.

Technical Field

The present invention relates to a polarizing plate and an optical display including the same.

Background

The liquid crystal display is operated to emit light through the liquid crystal panel after receiving light from the backlight unit. Since light from the backlight unit is perpendicularly incident on the screen of the liquid crystal display, the side of the screen of the liquid crystal display has a lower Contrast Ratio (CR) than the front of the screen. Therefore, the development of optical films capable of increasing the side contrast ratio is continuously in progress.

Such an optical film is configured such that light from the polarizing film can be diffused by a pattern formed at an 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 a side contrast ratio. However, this configuration of the optical film alone cannot sufficiently improve the contrast ratio.

In order to improve the side contrast ratio, a method of changing the shape of a pattern or a method of incorporating particles into a low refractive index resin layer or a high refractive index resin layer has been proposed. However, the former has the following problems: even slight variations in pattern shape can cause the side contrast ratio to vary dramatically. In addition, the latter has the following problems: an additional process of controlling a refractive index difference between the particles and the resin layer is required, and the presence of the particles may cause deterioration in optical transparency, such as increase in haze or reduction in luminous efficiency.

Disclosure of Invention

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

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

It is still another aspect of the present invention to provide a polarizing plate that can significantly improve a side contrast ratio of an optical display without incorporating particles into a pattern layer and thus can prevent a reduction in optical transparency (e.g., an increase in haze) due to the presence of particles, while preventing the obstruction of emission of polarized light due to the presence of particles, thereby improving light emission efficiency.

It is still another aspect of the present invention to provide an optical display including the polarizing plate of the present invention.

According to an aspect of the present invention, there is provided a polarizing plate including: a polarizing film; a first base layer; and a pattern layer sequentially formed on the light exit surface of the polarizing film, wherein 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 includes a patterned portion formed at least a portion thereof facing the second layer, the patterned portion including at least two optical patterns and a flat zone between the optical patterns adjacent to each other.

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

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

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

The present invention provides a polarizing plate that can significantly improve the side contrast ratio of an optical display without incorporating particles into a pattern layer and thus can prevent a reduction in optical transparency (e.g., an increase in haze) due to the presence of particles, while preventing the obstruction of emission of polarized light due to the presence of particles, thereby improving light emission efficiency.

Drawings

Fig. 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention.

Fig. 2 is an exploded perspective view of a pattern layer of a polarizing plate according to an embodiment.

Fig. 3 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

Fig. 4 is a cross-sectional view of a polarizing plate according to comparative example 2 or comparative example 4.

Detailed Description

Embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to provide a thorough understanding of the invention to those skilled in the art. It is to be understood that the present invention may be embodied in various forms and is not limited to the following embodiments. In the drawings, portions irrelevant to the description will be omitted for clarity. Like components will be represented by like reference numerals throughout this specification.

Spatially relative terms such as "upper" and "lower" are defined herein with reference to the accompanying drawings. Thus, it will 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 "disposed on" another element, the element can be directly disposed 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 therebetween.

Herein, the terms "horizontal direction" and "vertical direction" mean the longitudinal direction and the lateral direction of a rectangular screen of a liquid crystal display, respectively. Herein, "lateral" refers to (0 °,60 °) in a spherical coordinate system represented by (Φ, θ), where with reference to the horizontal direction, "front" is represented by (0 ° ), the left end point is represented by (180 °,90 °), and the right end point is represented by (0 °,90 °).

Herein, the "aspect ratio" refers to a ratio of the maximum height of the optical pattern to the maximum width thereof (maximum height/maximum width).

Herein, the "pitch" means a distance between a pair of adjacent optical patterns, for example, a sum of a maximum width W of one optical pattern and a width L of one flat zone adjacent thereto.

In this context, "bottom-most portion" refers to the lowest portion of the patterned optical pattern and may be a dot or a plane.

Herein, "in-plane retardation (Re)" is a value measured at a wavelength of 550 nm and is represented by equation a:

Re＝(nx-ny)×d，---(A)

where nx and ny are the refractive indices of the slow axis and the fast axis, respectively, of the corresponding protective or base layer at a wavelength of 550 nm, and d is the thickness (unit: nm) of the protective or base layer.

Herein, the term "(meth) propenyl" refers to propenyl and/or methylpropenyl.

As used herein, "X to Y" means "X is either greater than X to Y or less than Y" or ". gtoreq.X and. ltoreq.Y".

The inventors of the present invention found that: the polarizing plate in which the first base layer and the pattern layer described in detail below are sequentially stacked on the light exit surface of the polarizing film may significantly improve the side contrast ratio of the optical display while minimizing the reduction of the front contrast ratio, as compared to a typical polarizing plate not including the pattern layer, and thus the present invention has been completed. In addition, the inventors of the present invention found that: a polarizing plate in which a first base layer and a pattern layer, described in detail below, are sequentially stacked on a light exit surface of a polarizing film may significantly improve a side contrast ratio of an optical display only by controlling a relationship in refractive index between layers in the pattern layer, and thus the present invention has been completed.

Hereinafter, a polarizing plate according to one embodiment of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention, and fig. 2 is an exploded perspective view of a pattern layer shown in fig. 1.

Referring to fig. 1, a polarizing plate 10 may include a polarizing film 100, a first base layer 200, a pattern layer 300, and a second base layer 400.

Polarizing film

The first base layer 200, the pattern layer 300, and the second base layer 400 are sequentially formed on the light exit surface of the polarizing film 100. The polarizing film 100 may polarize light received from a liquid crystal panel (not shown in fig. 1) and transmit the light therethrough. 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.

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, such as 5, 10, 15, 20, 25, 30, 35, or 40 microns. Within this range, the polarizer may be used in an optical display.

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 polarizing plate while enhancing the mechanical strength of the polarizing plate by protecting the polarizer. The base layer may comprise at least one of an optically transparent protective film or an optically transparent protective coating. The base layer may be as described below.

Although not shown in fig. 1, 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, or the like.

First base layer

The first base layer 200 is formed on a light incident surface of the pattern layer 300 and may support the pattern layer 300. The first base layer 200 may be directly formed on the first layer 310 of the pattern layer 300, thereby reducing the thickness of the polarizing plate 10. Herein, the expression "directly formed 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 is to be understood that the present invention is not limited thereto and the first base layer may be formed on the first layer via an adhesive layer, a bonding layer, or an adhesive bonding layer.

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

The first base layer 200 may be a protective film or coating layer including a light incident surface and a light exiting surface opposite to the light incident surface. Preferably, the protective film serves as a first base layer to more firmly support the pattern layer.

When the first base layer is a protective film, the first base layer may comprise a single layer of an optically transparent resin film. However, it is to 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 may be prepared by melt extruding a resin. A process of stretching the resin may be further added. The resin may comprise at least one of: cellulose ester resins such as triacetyl cellulose (TAC); cyclic polyolefin resins such as amorphous Cyclic Olefin Polymers (COP); a polycarbonate resin; polyester resins such as polyethylene terephthalate (PET); polyether sulfone resin; polysulfone resin; a polyamide resin; a polyimide resin; a non-cyclic polyolefin resin; poly (meth) acrylate resins such as poly (methyl methacrylate) resin; a polyvinyl alcohol resin; a polyvinyl chloride resin; and polyvinylidene chloride resin.

Although the protective film may be an unstretched film, the protective film may be a retardation film or an isotropic optical film that is obtained by stretching a resin by a predetermined method and has a certain range of retardation. In one embodiment, the protective film may be an isotropic optical film having an in-plane retardation of 60 nm or less than 60 nm, specifically 0 nm to 60 nm, more specifically 40 nm to 60 nm, such as 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm, 51 nm, 52 nm, 53 nm, 54 nm, 55 nm, 56 nm, 57 nm, 58 nm, 59 nm, or 60 nm. In this range, the polarizing plate can provide good image quality through viewing angle compensation. Herein, "isotropic optical film" refers to a film having substantially the same nx, ny, and nz, and the expression "substantially the same" includes not only the case where nx, ny, and nz are identical, but also the case where there is an acceptable margin of error 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.

In one embodiment, the in-plane retardation of the first base layer may be 15,000 nanometers or less than 15,000 nanometers, specifically 3,000 nanometers to 15,000 nanometers, specifically 4,000 nanometers or greater than 4,000 nanometers, more specifically 5,000 nanometers or greater than 5,000 nanometers, yet more specifically 6,000 nanometers to 15,000 nanometers or 8,000 nanometers to 15,000 nanometers, such as 8,000 nanometers, 9,000 nanometers, 10,000 nanometers, 11,000 nanometers, 12,000 nanometers, 13,000 nanometers, 14,000 nanometers, or 15,000 nanometers. In this range, the pattern layer may further diffuse light passing through the first base layer, thereby improving the contrast ratio of the optical display.

The protective coating 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 radical 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 include at least one of a hydrogenated epoxy compound, a chain aliphatic epoxy compound, a cyclic aliphatic epoxy compound, and an aromatic epoxy compound.

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

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

The first base layer 200 may be formed on at least one surface thereof with a surface treatment layer, such as 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. Hard coatings, anti-fingerprint layers, anti-reflection layers, etc. may provide additional functionality to the first base layer, the polarizing film, etc. In particular, the primer layer may improve the bonding of the first base layer to an adherend (e.g., a pattern layer or a polarizing film).

Patterned layer

The pattern layer 300 may be formed on the light exit surface of the first base layer 200, and may diffuse light passing through the first base layer 200.

The patterned layer 300 may include a first layer 310 and a second layer 320 opposite the first layer 310. Preferably, the patterned layer 300 includes only the first layer 310 and the second layer 320.

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

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. In fig. 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 is 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.

The patterned portion includes: at least two patterned optical patterns 311; and flat regions 312 between adjacent patterned optical patterns 311. The polarizing plate includes a repeating combination of the engraved optical pattern 311 and the flat section 312. Herein, the "embossed optical pattern" refers to an optical pattern protruding toward the light exit surface of the first base layer 200.

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

< relation 1>

1<C/P≤10，---(1)

Where C represents the pitch of the patterned portion (unit: micrometer) and P represents the maximum width of the optical pattern (unit: micrometer).

Preferably, the value of C/P (ratio of C to P) is 1.1 to 8.0, in particular 1.1 to 5.0, such as 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.

The engraved optical pattern 311 has a curved surface. Polarized light from the first layer 310 enters the second layer 320 via the curved surface. With a curved surface, the patterned optical pattern can allow 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.

Fig. 1 shows a polarizing plate in which the curved surface is an aspherical surface and the engraved optical pattern 311 is a lenticular lens pattern. However, it is to be understood that the present invention is not limited thereto and the curved surface may be a spherical, parabolic, ellipsoidal, hyperboloidal, or amorphous curved surface. Although the patterned optical pattern is shown as having a flat curved surface, the patterned optical pattern can have unevenness to further improve light diffusion.

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

The aspect ratio of the engraved optical pattern 311 may 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 the side viewing angle of the optical display.

The maximum width P of the engraved optical pattern 311 may be greater than 0 microns and less than or equal to 15 microns, specifically 2 microns to 15 microns, such as 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. The maximum height H of the embossed optical pattern 311 can be greater than 0 microns and less than or equal to 50 microns, specifically 1 micron to 45 microns, such as 1 micron, 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, or 45 microns. Within these maximum widths and maximum heights, the embossed optical pattern can provide light diffusion.

The ratio of the sum of the maximum widths of the patterned optical pattern 311 to the total width of the first layer 310 can have a value of 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 polarizing plate can improve the side contrast ratio and the side viewing angle of the optical display. The patterned optical pattern 311 may be arranged at a predetermined pitch C to further diffuse the polymerized light. The embossed optical patterns 311 may be arranged at a pitch C that is greater than 0 microns and 60 microns or less than 60 microns, specifically 5 microns to 60 microns, such as 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, or 60 microns, in which range the polarizing plate may provide further improved photopolymerization and diffusion.

The ratio of the maximum width P of the engraved optical pattern 311 to the width L of the flat zone 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, such as 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 may reduce the difference between the front-side contrast ratio and the side-side contrast ratio of the optical display while improving the contrast ratio of the optical display at a given side viewing angle and at a given front viewing angle. In addition, the polarizing plate can prevent a moire (moire) phenomenon.

The minimum distance between the engraved optical pattern 311 and the first base layer 200, i.e., the minimum distance D (also referred to as "wall thickness") between the bottommost portion of the engraved optical pattern 311 and the first base layer 200, can have a value greater than 0 microns and less than or equal to 30 microns, specifically 1 micron to 20 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, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, or 20 microns. Within this range, the uniformity of film hardness and coating thickness can be ensured.

The ratio (H/a) of the maximum height H of the engraved optical pattern 311 to the distance a between the uppermost surface of the pattern layer 300 and the lowermost portion of the engraved optical pattern 311 may have a value 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, the uniformity of film hardness and coating thickness can be ensured.

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 may have a value of 40% to 60%, preferably 45% to 55%, for example 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%. In this range, the polarizing plate can improve the side visibility of the optical display.

The second layer 320 includes a filling pattern 321 formed at an interface with the first layer 310 and filling at least a portion of the patterned 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 patterned optical pattern 311.

Although in fig. 1, the polarizing plate is illustrated as including the engraved optical patterns having the same aspect ratio, maximum width, maximum height, and spacing, it is to be understood that the present invention is not limited thereto and the polarizing plate may include the engraved optical patterns having different aspect ratios, maximum widths, maximum heights, and spacings.

The flat region 312 may be formed between adjacent patterned optical patterns 311. The flat region 312 allows polarized light from the first layer 310 to pass directly into the second layer 320, thereby improving the front contrast ratio and front brightness of the optical display.

Polarized light from the first base layer 200 is transmitted from the first layer 310 to the second layer 320, and the protrusions of the patterned optical pattern 311 face the first base layer 200. The width L of the flat zone 312 can be greater than 0 microns and less than or equal to 50 microns, specifically greater than 0 microns and less than or equal to 30 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, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, 20 microns, 21 microns, 22 microns, 23 microns, 24 microns, 25 microns, 26 microns, 27 microns, 28 microns, 29 microns, or 30 microns. In this range, the polarizing plate may provide photopolymerization and diffusion.

Although the polarizing plate is illustrated as including the flat sections having the same width in fig. 1, it is to be understood that the present invention is not limited thereto and the polarizing plate may include the flat sections having different widths.

Referring to fig. 2, the engraved optical pattern 311 may extend in a stripe shape in a longitudinal direction thereof. In this way, the polarizing plate may increase the side viewing angle of the optical display. Alternatively, the engraved optical pattern may be formed in a dot shape. In this context, the term "dots" means that the optical pattern is dispersed.

The first layer 310 has a higher refractive index than the second layer 320. The inventors of the present invention found that: the side contrast ratio of the optical display may be significantly improved by allowing polarized light from the polarizing film 100 to be transmitted to the second layer 320 through the first layer 310 and allowing the first layer 310 to include the engraved optical pattern 311 protruding toward the polarizing film 100. The difference in refractive index between the first layer 310 and the second layer 320 can be 0.05 or greater than 0.05, 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 may further improve the side contrast ratio of the optical display.

The refractive index of the first layer 310 may be 1.50 or greater than 1.50, 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.

The first layer 310 may be formed of a composition including a resin capable of satisfying the aforementioned refractive index range. For example, the first layer may include a UV curable or thermal curable resin, such as at least one of a (meth) acrylic resin, an epoxy resin, a urethane resin, and a silicone resin, but is not limited thereto. Herein, the composition may further comprise various additives, such as an initiator that promotes curing of the resin.

In one embodiment, the first layer may be a particle-free resin layer. In general, in order to improve the side contrast ratio of an optical display, a method of incorporating high refractive index particles (having a higher refractive index than the first layer) into a high refractive index layer, such as a light diffuser, a light absorber, etc., has been proposed, according to the present invention, by adjusting the stacking relationship between the first layer and the second layer with respect to the light exit surface of the polarizing film and the projection 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 the light emission efficiency of the optical display can be further improved. The haze of the polarizing plate may 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%.

The second layer 320 may be formed of a composition including a resin capable of satisfying the aforementioned refractive index range. For example, the second layer may include a UV curable or thermal curable resin, such as at least one of a (meth) acrylic resin, an epoxy resin, a urethane resin, and a silicone resin, but is not limited thereto. Herein, the composition may further comprise various additives, such as an initiator that promotes curing of the resin.

In one embodiment, the second layer may be a particle-free resin layer. Generally, in order to improve the side contrast ratio of an optical display, a method of incorporating particles, such as a light diffuser, a light absorber, and the like, into a second layer has been proposed. According to the present invention, by adjusting the stacking relationship between the first layer and the second layer with respect to the light exit surface of the polarizing film and the projection direction of the engraved optical pattern, the side contrast ratio can be significantly improved without incorporating these particles into the second layer.

In one embodiment, the second layer may be formed of a binder composition exhibiting binding properties after curing to have the binding properties. Accordingly, the second layer may be directly bonded to the second base layer, thereby reducing the thickness of the polarizing plate. The second layer may have good bonding properties with respect to the second base layer, in particular a polyester film.

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

Second base layer

The second base layer 400 may be formed on the light exit surface of the pattern layer 300 to transmit light from the pattern layer 300 therethrough. Second base layer 400 may be directly formed on second layer 320 of pattern layer 300, thereby reducing the thickness of polarizing plate 10. Herein, the expression "directly formed 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 is to 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, a bonding layer, or an adhesive bonding layer.

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.

In one embodiment, the in-plane retardation of the second base layer can be 15,000 nanometers or less than 15,000 nanometers, specifically 3,000 nanometers to 15,000 nanometers, more specifically 4,000 nanometers or greater than 4,000 nanometers, yet more specifically 5,000 nanometers or greater than 5,000 nanometers, yet more specifically 6,000 nanometers to 15,000 nanometers or 8,000 nanometers to 15,000 nanometers, such as 8,000 nanometers, 9,000 nanometers, 10,000 nanometers, 11,000 nanometers, 12,000 nanometers, 13,000 nanometers, 14,000 nanometers, or 15,000 nanometers. In this range, the polarizing plate may further diffuse the light diffused through the contrast improving layer, thereby further improving the contrast ratio of the optical display. In one embodiment, the polarizing plate may further improve the contrast ratio of the optical display when the in-plane retardation values of the first and second base layers are within the aforementioned range.

Although not shown in fig. 1, a functional layer may be further formed on the light exit surface of the second base layer 400. The functional layer may provide an additional function to the polarizing plate. For example, the functional layer may include at least one of: a primer layer, a hard coat 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.

Although the polarizing plate is illustrated as including the second base layer 400 formed on the pattern layer in fig. 1, it is to 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. Herein, the expression "serving as a functional layer" means that the uppermost surface of the second layer serves as at least one of: a primer layer, a hard coat layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low-reflectance layer, and an ultra-low reflectance layer. Herein, the second layer may serve as a functional layer by undergoing surface treatment or the like during its formation.

Next, a polarizing plate according to another embodiment of the present invention will be described with reference to fig. 3.

Referring to fig. 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-described embodiment, except that a pattern layer 300A is formed instead of the pattern layer 300.

The patterned 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.

The patterned portion comprises at least two patterned optical patterns 311A; and a flat zone 312A between adjacent patterned optical patterns 311A. The polarizing plate includes a repeating combination of an engraved optical pattern 311A and a flat space 312A at an interface between a first layer 310A and a second layer 320A. Herein, the "embossed optical pattern" refers to an optical pattern protruding toward the first base layer 200.

The patterned portion may satisfy relation 1, and the engraved optical pattern 311A may have a base angle θ of 60 ° to 90 °. Herein, the base angle θ means an angle formed between the inclined surface of the engraved optical pattern 311A and the maximum width P1 of the engraved optical pattern 311A. Herein, the inclined surface 313A refers to an inclined surface of the engraved optical pattern 311A directly connected to the flat zone 312A. When the patterned portion satisfies relation 1 and the bottom angle of the engraved optical pattern is within the aforementioned range, the polarizing plate may 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 (ratio of C1 to P1) may be 1.1 to 8.0, such as 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.

< relation 1>

1<C1/P1≤10，---(1)

Where C1 represents the pitch of the patterned portions (unit: micrometer) and P1 represents the maximum width of the optical pattern (unit: micrometer).

Although the engraved optical pattern 311A is illustrated as having the same base angle at both sides thereof in fig. 3, the engraved optical pattern may have different base angles as long as the base angle is in the range of 60 ° to 90 ° as described above.

The engraved optical pattern 311A may be an engraved optical pattern including a first surface 314A formed at the bottommost portion thereof and at least one inclined surface 313A connected to the first surface 314A. Although in fig. 3, the engraved optical pattern is illustrated as a trapezoidal optical pattern in which two adjacent inclined surfaces 313A are connected by a first surface 314A, it is to be understood that the present invention is not limited thereto and the engraved optical pattern may be an optical pattern having a rectangular or square cross section.

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

The first surface 314A may be parallel to at least one of: a flat zone 312A, a lowermost surface of the first layer 310A, and an uppermost surface of the second layer 320A.

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

The aspect ratio of the engraved optical pattern 311A may 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. Embossing the optical pattern within this range can improve the side contrast ratio and side viewing angle of the optical display.

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

The maximum width P1 of the engraved optical pattern 311A may be greater than 0 microns and less than or equal to 15 microns, specifically 2 microns to 15 microns, such as 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 improve the contrast ratio, viewing angle and brightness of the optical display while preventing moire phenomenon.

The minimum distance between the engraved optical pattern 311A and the first base layer 200, i.e., the minimum distance D1 (also referred to as "wall thickness") between the lowermost portion of the engraved optical pattern 311A and the first base layer 200, can have a value of 0 microns to 30 microns, specifically 1 micron to 20 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, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, or 20 microns. Within this range, the uniformity of film hardness and coating thickness can be ensured.

The ratio of the sum of the maximum widths of the patterned optical pattern 311A to the total width of the first layer 310A can have a value of 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 polarizing plate can improve the side contrast ratio and the side viewing angle of the optical display.

The value of the ratio (H1/a1) of the maximum height H1 of the engraved optical pattern 311A to the distance a1 between the uppermost surface of the pattern layer 300A and the lowermost portion of the engraved optical pattern 311A 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, the uniformity of film hardness and coating thickness can be ensured. In fig. 3, the patterned portion is shown as containing an engraved optical pattern 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 an engraved optical pattern having different base angles, widths of the first surface, maximum heights, and maximum widths.

The flat section 312A allows light passing through the first layer 310A to enter the second layer 320A therethrough, thereby improving the front luminance of the optical display.

The ratio of the maximum width P1 of the patterned optical pattern 311A to the width L1 of the land 312A can have a value greater than 0 and less than or equal to 9, specifically 0.1 to 3, more specifically 0.15 to 2, such as 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-side contrast ratio and the side-side contrast ratio of the optical display may be reduced while improving the contrast ratio of the optical display at a given side viewing angle and at a given front viewing angle. In addition, a ripple phenomenon can be prevented.

Width L1 of flat zone 312A may be greater than 0 microns and less than or equal to 50 microns, specifically greater than 0 microns and less than or equal to 30 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, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, 20 microns, 21 microns, 22 microns, 23 microns, 24 microns, 25 microns, 26 microns, 27 microns, 28 microns, 29 microns, or 30 microns. In this range, the polarizing plate can improve the front luminance of the optical display.

The maximum width of one patterned optical pattern 311A and one flat section 312A adjacent thereto form a pitch (C1). The engraved optical pattern may be arranged at a pitch C1, said pitch C1 being greater than 0 microns and less than or equal to 60 microns, in particular 5 microns to 60 microns, such as 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns or 60 microns. Within this range, the polarizing plate can improve the contrast ratio of the optical display while preventing the moire phenomenon.

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 may have a value of 40% to 60%, specifically 45% to 55%, for example 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%. In this range, the polarizing plate can improve the side visibility of the optical display.

Although in fig. 3, the patterned portions are shown as including engraved optical patterns having the same pitch and maximum width, the patterned portions may include engraved optical patterns having different pitches and maximum widths.

The optical display according to the present invention may comprise 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.

In one embodiment, polarizing plate 10 may be used as a viewer-side polarizing plate in a liquid crystal display. Herein, the term "viewer-side polarizing plate" means a polarizing plate disposed at a viewer side with respect to the liquid crystal panel and opposite to the light source.

In one embodiment, a liquid crystal display includes a backlight unit, a first polarizing plate, a liquid crystal panel, and a second polarizing plate, which may include the polarizing plate according to the present invention, and is stacked in the stated order. The liquid crystal panel may employ 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 can be used as a light source side polarizing plate. Herein, the term "light source side polarizing plate" refers to a polarizing plate disposed at the light source side with respect to the liquid crystal panel. In another embodiment, the polarizing plate according to the present invention can be used as a viewer-side polarizing plate and a light source-side polarizing plate with respect to a liquid crystal panel.

Next, the present invention will be described in more detail with reference to some examples. It should be noted, however, that these examples are provided for illustration only and should not be construed as limiting the invention in any way.

Example 1

A resin (SSC-6000, new ann corporation of korea (SHIN-A T & C co., Ltd.)) was used as the high refractive index layer composition (containing no particles). Herein, the high refractive index layer composition may further include a predetermined solvent.

A resin (SSC-4000, new ann, korea) was used as the low refractive index layer composition (without particles). Herein, the low refractive index layer composition may further comprise a predetermined solvent.

The high refractive index layer composition for the first base layer was coated onto the upper surface of a transparent PET film (super birefringent film (SRF), Toyobo co., Ltd., thickness: 80 μm, in-plane retardation: 8,000 nm) to a predetermined thickness. Subsequently, a film having a pattern and a flat zone 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 first layer including patterned portions as shown in table 1, in which the engraved optical pattern and the flat zone are alternately arranged. A low refractive index layer composition is coated onto the first layer to completely fill the patterned optical pattern.

Subsequently, a coating layer was laminated on one surface of a transparent PET film (SRF, toyo textile, thickness: 80 μm, in-plane retardation: 8,000 nm) for a second base layer, which had an antireflection layer formed on the other surface thereof, and then cured via UV radiation, thereby forming a second base layer on the pattern layer.

The polarizer was manufactured by: the polyvinyl alcohol film was stretched to 3 times its original length at 60 ℃ and iodine was adsorbed to the stretched film, followed by stretching the film to 2.5 times the stretched length in an aqueous boric acid solution at 40 ℃.

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 adhesive.

The manufactured polarizing plate has the following structure: wherein the first base layer, the first layer (high refractive index layer), the second layer (low refractive index layer) and the second base layer are sequentially stacked on the light exit surface of the polarizer and the patterned optical pattern protrudes toward the first base layer.

Example 2

Resin (SSC-5500, New Korea company) was used as the high refractive index layer composition (without particles). Herein, the high refractive index layer composition may further include a predetermined solvent.

A resin (SSC-4500, new ann, korea) was used as the low refractive index layer composition (without particles). Herein, the low refractive index layer composition may further comprise a predetermined solvent.

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.

Example 3

A polarizing plate was manufactured in the same manner as in example 1, except that the engraved optical pattern and the flat zone were changed, as shown in table 1.

Example 4

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.

Comparative example 1

The polarizer was prepared by: the polyvinyl alcohol film was stretched to 3 times its original length at 60 ℃ and iodine was adsorbed to the stretched film, followed by stretching the film to 2.5 times the stretched length in an aqueous boric acid solution at 40 ℃. The polarizing plate was manufactured by bonding a transparent PET film (SRF, toyo textile, thickness: 80 μm, in-plane retardation: 14,000 nm) for the first base layer to the upper surface of the prepared polarizer using a UV curable binder.

Comparative example 2

One surface of a transparent PET film (SRF, toyo textile, thickness: 80 micrometers, in-plane retardation: 8,000 nanometers) for the second base layer having an anti-reflection layer formed on the other surface thereof was coated with the high refractive index layer composition of example 1 at a predetermined thickness. Subsequently, a film having a pattern and flat sections 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 the flat sections alternately arranged as listed in table 1. Subsequently, the low refractive index layer composition of example 1 was coated onto the high refractive index layer to completely fill the patterned optical pattern.

Subsequently, a coating layer was laminated on the upper surface of a transparent PET film (SRF, toyo textile co., thickness: 80 μm, in-plane retardation: 8,000 nm) for the first base layer, followed by curing. Subsequently, a polarizing plate was manufactured by: the polarizer of example 1 was bonded to the lower surface of the transparent PET film for the first base layer using a UV curable bonding agent, followed by curing.

Fig. 4 is a cross-sectional view of the polarizing plate of comparative example 2. Referring to fig. 4, the polarizing plate of comparative example 2 includes: the polarizer 100, the first base layer 200, the low refractive index layer 510, the high refractive index layer 520, and the 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 sequentially stacked on the light exit surface of the polarizer 100.

Comparative example 3

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.

Comparative example 4

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.

TABLE 1

Each of the polarizing plates manufactured according to examples and comparative examples was evaluated with the following characteristics. The results are shown in table 2.

Production of light source side polarizing plate

The polarizer was prepared by: the polyvinyl alcohol film was stretched to 3 times its original length at 60 ℃ and iodine was adsorbed to the stretched film, followed by stretching the film to 2.5 times the stretched length in an aqueous boric acid solution at 40 ℃. As the base layer, triacetyl cellulose films (thickness: 80 μm) were bonded to both surfaces of the polarizer using a bonding agent for a polarizing plate (Z-200, Nippon Goshei co., Ltd.) to thereby manufacture a polarizing plate. The produced polarizing plate was used as a light source side polarizing plate.

Manufacture of liquid crystal display module

A liquid crystal display module is manufactured by: each of the manufactured light source side polarizing plate, liquid crystal panel (PVA mode), and polarizing plates manufactured in examples and comparative examples was assembled in order. Herein, the assembly is performed such that the second base layer of the polarizing plate is positioned at the outermost portion.

The LED light source, the light guide plate, and the liquid crystal display module were assembled into a liquid crystal display including a single-sided LED light source (having the same configuration as Samsung (Samsung) TV (55 inch UHD TV (model 2016), model no 55KS8000F) except that the liquid crystal display module was manufactured using each of the polarizing plates manufactured in the examples and comparative examples).

The luminance in the white mode and the luminance in the black mode were measured at the front (0 ° ) and the side (0 °,60 °) in a spherical coordinate system using a luminance tester EZCONTRAST X88RC (EZXL-176R-F422a4, ELDIM).

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

In table 2, the 1/2 viewing angle refers to a viewing angle with a brightness of 1/2 of front brightness.

In table 2, the 1/3 viewing angle refers to a viewing angle with a brightness of 1/3 of front brightness.

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

TABLE 2

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.

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.

In contrast, the polarizing plates of comparative examples 2 to 3, which do not contain particles and have different structures from the polarizing plate according to the present invention, allow the front contrast ratio to be reduced while providing significantly inferior improvement in the side contrast ratio, as compared to the polarizing plate according to the present invention. In addition, the polarizing plate of comparative example 4 exhibited inferior characteristics in terms of transparency and uniformity of brightness.

It is to be understood that various modifications, changes, alterations, and equivalent embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention.