TW202232155A - Optical laminate and optical display apparatus comprising the same - Google Patents

Abstract

An optical laminate and an optical display apparatus including the same. The optical laminate includes: a polarizer; and a pattern layer stacked on one surface of the polarizer, wherein the pattern layer includes a first layer and a second layer sequentially stacked on the polarizer and a patterned portion is formed at an interface between the first layer and the second layer, the second layer having a higher index of refraction than the first layer and containing core-shell particles having a titania-containing core and a zirconia-containing shell surrounding the titania-containing core, the core-shell particles comprising titania and zirconia in a concentration ratio (titania:zirconia) of 1:5 to 1:8.

Description

Optical laminate and optical display device including the same

The present invention relates to an optical laminate and an optical display device including the same. [Cross-reference to related applications]

This application claims the benefit of Korean Patent Application No. 10-2021-0011923 filed on January 27, 2021 with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

The liquid crystal display includes a viewer-side polarizing plate disposed on one surface of the liquid crystal panel and a light-source-side polarizing plate disposed on the other surface thereof. In general, the viewer-side polarizing plate has a structure including a polarizer and a protective layer stacked on at least one surface of the polarizer. However, when such a viewer-side polarizer is applied to a liquid crystal display, despite high brightness, the visibility of the liquid crystal display suffers from significant deterioration due to low front and lateral contrast ratios. Accordingly, the viewer-side polarizing plate may include a predetermined-shaped patterned portion formed at the interface between the high-refractive index layer and the low-refractive index layer in order to improve contrast and visibility.

The viewer-side polarizing plate may include a predetermined-shaped patterned portion formed at the interface between the high-refractive index layer and the low-refractive index layer in order to improve contrast and visibility.

The high-refractive layer may be formed by depositing a composition for the high-refractive layer on one surface of the protective layer or on the low-refractive layer, and then curing the composition. The composition for the high-refractive layer may include an aromatic resin, a sulfur-based resin, or nanoparticles having a high refractive index to ensure high refractive index. However, although the monofunctional or bifunctional aromatic resin or sulfur-based resin can achieve high refractive index, the hardness of the pattern layer suffers from deterioration. In addition, aromatic resins generally have a problem of yellowing, while sulfur-based resins have a problem of having a sulfur odor, making their production difficult. Although nanoparticles with a high refractive index can achieve high refraction, the nanoparticles make it difficult to adjust the viscosity of the composition and lead to deterioration of transmittance and adhesion to the protective layer.

On the other hand, since the pattern layer is composed of a high-refractive-index layer and a low-refractive layer and is stacked on the polarizer, the high-refractive layer must have high transmittance, and the pattern layer and the laminate of the pattern layer and the protective layer must be Has high transmittance.

The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2014-0108974 and the like.

An object of the present invention is to provide an optical laminate including a second layer having high light transmittance and high refractive index.

Another object of the present invention is to provide an optical laminate including a pattern layer or a laminate of a pattern layer and a protective layer, the pattern layer having a suitable light transmittance with respect to a polarizer to improve screen visibility.

Still another object of the present invention is to provide an optical laminate comprising a second layer having good adhesion to the protective layer or the first layer while ensuring improved brightness and contrast.

One aspect of the present invention pertains to an optical laminate.

The optical laminate includes: a polarizer; and a pattern layer stacked on one surface of the polarizer, wherein the pattern layer includes a first layer and a second layer sequentially stacked on the polarizer, and a patterned portion is formed at the interface between the first layer and the second layer, the second layer has a higher refractive index than the first layer, and contains core-shell particles, the second layer has a higher refractive index than the first layer, and the The core-shell particles have a titania-containing core and a zirconia-containing shell surrounding the titania-containing core, the core-shell particles comprising titania and a 1:5 to 1:8 concentration ratio (titania:zirconia) Zirconia.

The core-shell particles may be present in the second layer in an amount from about 5% to about 60% by weight.

The core-shell particles may have a refractive index of about 2.0 or greater.

The core-shell particles may have an average particle size (D50) of about 10 nanometers to about 100 nanometers.

The second layer may include a matrix and the core-shell particles embedded in the matrix, and the matrix may have a lower refractive index than the core-shell particles.

The second layer may have a light transmittance of about 82% or greater.

The pattern layer may have a light transmittance of about 82% or greater.

The difference in refractive index between the second layer and the first layer may be about 0.5 or greater, and the second layer may have a refractive index of about 1.60 or greater.

The patterned portion may include at least one engraved pattern and a separating surface between two adjacent engraved patterns.

The engraved pattern may have a first facet formed at a top portion thereof and lateral sides connected to the first facet.

The lateral sides may comprise flat surfaces or curved surfaces.

The lateral sides may be raised from the second layer towards the first layer or from the first layer towards the second layer.

The optical laminate may further include a first protective layer on the upper surface of the second layer.

The laminate of the second layer and the first protective layer may have a light transmittance of about 82% or more.

The optical laminate may further include a second protective layer stacked on the lower surface of the polarizer and/or a third protective layer stacked between the polarizer and the pattern layer.

An optical display device according to the present invention may include the optical laminate according to the present invention.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the accompanying drawings. It should be understood that the present invention may be implemented in various ways and is not limited to the following examples. The following embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can thoroughly understand the present invention.

Although the length, thickness or width of various components may be exaggerated in the drawings for understanding, the present invention is not limited thereto. Throughout the specification, the same parts will be designated by the same reference numbers.

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 said to be placed "on" another element, the element may be placed directly on the other element components, or there may be intermediate components. On the other hand, when an element is said to be placed "directly on" another element, there are no intervening elements.

Herein, "transmittance" means a value measured at a wavelength of 300 nm to 800 nm, specifically at a wavelength of 550 nm.

Herein, "refractive index" means a value measured at a wavelength of 300 nm to 800 nm, in particular at a wavelength of 550 nm.

Herein, the terms "horizontal direction" and "vertical direction" mean the longitudinal direction and the lateral direction, respectively, of a rectangular screen of a liquid crystal display. In addition, on the screen of the liquid crystal display, the lateral side refers to (0°, 30°) or (0°, 60°) in the spherical coordinate system represented by (ϕ, θ), and in the spherical coordinate system (ϕ, θ) θ), with the horizontal direction as the reference, the positive side is indicated by (0°, 0°).

As used herein, "top portion" refers to the highest point of the engraving.

As used herein, "aspect ratio" refers to the ratio of a pattern's maximum height to its maximum width (maximum height/maximum width).

As used herein, "pitch" means the sum of the distances between two adjacent engravings, eg, the sum of the maximum width of one engraving and the largest width of the separating surface.

In this paper, "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 on the slow axis and fast axis of the corresponding protective layer at a wavelength of 550 nm, respectively, and d is the thickness of the protective layer (unit: nanometer).

As used herein, the term "(meth)acrylic group" refers to an acrylic group and/or a methacrylic group.

The expression "X to Y" used herein to denote a particular numerical range means a value greater than or equal to X and less than or equal to Y (X≤and≤Y).

The optical laminate according to the present invention includes a pattern layer composed of a second layer having a high refractive index and a first layer having a low refractive index, and is stacked on the upper surface of the polarizer, wherein the second layer is A patterned portion is formed at the interface between the layer and the first layer. In the optical laminate, the second layer of the pattern layer has a suitable light transmittance relative to the polarizer by controlling the composition of the second layer of the pattern layer to increase light transmittance, thereby further improving screen visibility. In addition, the optical laminate may further include a protective layer on the upper surface of the pattern layer or between the pattern layer and the polarizer, wherein the pattern layer exhibits good adhesion to the polarizer or the protective layer. In addition, the laminate of the protective layer and the second layer has improved light transmittance, thereby improving screen visibility.

The optical laminate includes: a polarizer; and a pattern layer stacked on one surface of the polarizer, wherein the pattern layer includes a first layer and a second layer sequentially stacked on the polarizer, and a patterned portion is formed at the interface between the first layer and the second layer, the second layer has a higher refractive index than the first layer, and contains core-shell particles, the second layer has a higher refractive index than the first layer, and the The core-shell particles have a titania-containing core and a zirconia-containing shell surrounding the titania-containing core, the core-shell particles comprising titania and a 1:5 to 1:8 concentration ratio (titania:zirconia) Zirconia.

Hereinafter, an optical laminate according to an embodiment of the present invention will be described with reference to FIG. 1 .

1 , an optical laminate according to an embodiment includes: a polarizer 400 ; and a pattern layer 300 and a first protective layer 500 sequentially stacked on an upper surface of the polarizer 400 , wherein the pattern layer 300 includes sequentially stacked on The first layer 100 and the second layer 200 on the polarizer 400 . In one embodiment, the optical stack may be a polarizer.

The upper surface of the polarizer 400 may be the light incident surface or the light exit surface of the polarizer, preferably the light exit surface of the polarizer. Herein, "light exit surface" means a surface through which internal light emitted from a backlight unit including a light source is emitted. In this embodiment, the second layer is stacked on the light exit surface of the polarizer. However, it should be understood that the present invention is not limited thereto. polarizer

Polarizer 400 is used to polarize incident light and may include typical polarizers known to those skilled in the art. Specifically, the polarizer may include a polyvinyl alcohol-based polarizer formed by uniaxially stretching a polyvinyl alcohol film or a polyene-based polarizer formed by dehydration of a polyvinyl alcohol film.

The polarizer 400 may have a light transmittance of about 40% or more, specifically about 40% to about 50%. Within this range, polarizers can help improve screen visibility.

The polarizer 400 may have a thickness of about 5 microns to about 40 microns. Within this range, polarizers can be used in optical display devices. pattern layer

The pattern layer 300 is stacked on the light exit surface of the polarizer 400 to transmit light emitted from the polarizer 400 and can be used to improve brightness and viewing angle by the patterned portion described in detail below.

The pattern layer 300 includes a first layer 100 and a second layer 200 sequentially stacked on the polarizer 400 , wherein the second layer 200 has a higher refractive index than the first layer 100 .

As described in detail below, the second layer 200 may have an index of refraction of about 1.60 or greater, and the first layer 100 may have an index of refraction of about 1.55 or less. The polarizer 400 may have a refractive index of 1.3 to 1.5. Since the light emitted from the polarizer passes through the pattern layer, each of the second layer and the pattern layer must have suitable light transmittance.

The second layer 200 can have about 82% or more, such as about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90% , about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100%, specifically about 82% to about 95% % transmittance. Within this range, the second layer can improve screen visibility by improving the transmittance of light emitted from the polarizer.

As described in detail below, the protective layer may be further interposed between the pattern layer 300 and the polarizer 400 . However, since the protective layer is a film or coating formed of an optically transparent resin, the protective layer does not substantially affect the light emitted from the polarizer. Therefore, the protective layer does not affect the improvement of screen visibility or brightness.

In one embodiment, the pattern layer 300 may have about 82% or more, such as about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89% %, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99% or about 100%, specifically about 82% to about 95% transmittance. Within this range, the patterned second layer can improve screen visibility by improving the transmittance of light emitted from the polarizer. Second floor

The second layer 200 may be stacked on the light exit surface of the polarizer 400 and the light exit surface of the first layer 100 to improve brightness by emitting light that has passed through the polarizer and the first layer. Herein, "light exit surface" means a surface through which internal light emitted from a backlight unit including a light source is emitted.

The second layer 200 has a higher refractive index than the first layer 100 . The refractive index difference between the second layer 200 and the first layer 100 may be about 0.1 or greater than 0.1, such as about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 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, 3.0, specifically about 0.1 to about 3.0, more specifically About 0.1 to about 1. Within this range, the second layer can help improve brightness through the pattern layer.

The second layer 200 may have a refractive index of about 1.60 or greater, such as about 1.60, 1.65, 1.70, 1.75, specifically about 1.60 to about 1.75, more specifically about 1.60 to about 1.70. Within this range, the second layer may contribute to the advantageous effects of the present invention.

The second layer 200 includes core-shell particles (not shown in FIG. 1 ) having a titania-containing core and a zirconia-containing shell surrounding the titania-containing core. The core-shell particles comprise titania and zirconia in a concentration ratio (titania:zirconia) of 1:5 to 1:8. For example, the concentration ratio may be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, or 1:8.

Since the core-shell particles have a zirconia-containing core and a titania-containing shell surrounding the zirconia-containing core, the second layer may have a refractive index within the above-mentioned range. However, in this case, the second layer may suffer from deterioration of light transmittance, and the pattern layer cannot have proper light transmittance, thereby resulting in poor screen visibility. Within this concentration ratio range, the second layer may have high light transmittance, and the laminate of the second layer and the pattern layer or the laminate of the second layer and the protective layer described below may have a suitable value with respect to the polarizer transmittance, thereby ensuring good screen visibility. The concentration ratio is determined in consideration of the patterned portion provided to the patterned layer, as described in detail below.

The core-shell particles have a titania-containing core and a zirconia-containing shell surrounding the titania-containing core. The core may comprise about 90 mol% or greater than 90 mol%, such as about 90 mol%, about 91 mol%, about 92 mol%, about 93 mol%, about 94 mol%, about 95 mol% mol%, about 96 mol%, about 97 mol%, about 98 mol%, about 99 mol% or about 100 mol%, specifically about 95 mol% to about 100 mol% of titanium dioxide . Within this range, the second layer can easily achieve the above-mentioned refractive index and light transmittance. The shell may comprise about 90 mol% or greater than 90 mol%, such as about 90 mol%, about 91 mol%, about 92 mol%, about 93 mol%, about 94 mol%, about 95 mol% Molar %, about 96 mol %, about 97 mol %, about 98 mol %, about 99 mol % or about 100 mol %, specifically about 95 mol % to about 100 mol % oxidation zirconium. Within this range, the second layer can easily achieve the above-mentioned refractive index and light transmittance.

The concentration ratio can be calculated by measuring the concentration of each of titania and zirconia contained in the core-shell particles using Inductively Coupled Plasma Optics Spectrometry (ICP-OES).

Titanium dioxide contained in the core has a higher refractive index than zirconia contained in the shell. The refractive index of titania may be greater than about 2.0 to about 4.0, specifically greater than about 2.0 to about 3.0, and the refractive index of zirconia may be about 1.5 to about 2.0, specifically about 1.6 to about 2.0. Although titania has a higher refractive index than zirconia, the second layer includes core-shell particles having a titania-containing core and a zirconia-containing shell surrounding the titania-containing core to provide a high refractive index and high light transmittance, At the same time, the pattern layer is allowed to have suitable light transmittance relative to the polarizer, thereby improving screen visibility.

In one embodiment, the core may have a higher refractive index than the shell.

Core-shell particles can be prepared by typical methods known to those skilled in the art. For example, but not limited to, core-shell particles can be prepared by hydrolysis and condensation.

The core-shell particles may have true-spherical shape, spherical shape, amorphous shape, elliptical shape, etc., but are not limited thereto. The average particle size (D50) of the core-shell particles may be about 10 nm to about 100 nm, such as about 10 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, about 35 nm, about 40 nm, about 45 nm, about 50 nm, about 55 nm, about 60 nm, about 65 nm, about 70 nm, about 75 nm, about 80 nm, about 85 nm, about 90 nm, about 95 nm, or about 100 nm, specifically about 10 nm to about 50 nm. Within this range, the core-shell particles can be included in the second layer of the pattern layer and not affect the light emitted from the first layer.

In the second layer, the content of core-shell particles may be from about 5 wt% to about 60 wt%, such as about 5 wt%, about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt%, about 50 wt%, about 55 wt% or 60 wt%, specifically about 10 wt% to about 40 wt%, more specifically It is about 20 wt% to about 30 wt%. Within this range, the core-shell particles allow the second layer to have a refractive index within the above range, and can improve the light transmittance of the second layer while ensuring good adhesion of the second layer to the polarizer or protective layer, while The front brightness is not degraded.

The refractive index of the core-shell particles can be about 2.0 or greater, such as about 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0, specifically about 2.0 to about 3.0. Within this range, the core-shell particles allow the second layer to easily have a refractive index within the above range.

The second layer 200 may include core-shell particles and a matrix in which the core-shell particles are embedded. Although the matrix may have a higher refractive index than the core-shell particles, the matrix may have a lower refractive index than the core-shell particles to prevent problems when using aromatic resins or sulfur resins. The matrix may have a refractive index of about 1.50 or greater, such as about 1.50, 1.56, 1.57, 1.58, 1.59, specifically about 1.50 to less than about 2.0. Within this range, the second layer can easily achieve the above-mentioned refractive index.

The matrix may be formed of a composition including an ultraviolet curable resin and/or a thermosetting resin. For example, the resin may include at least one selected from (meth)acrylic resin, polycarbonate resin, silicone resin and epoxy resin, but is not limited thereto. The composition may further include at least one selected from the group consisting of photoinitiators and thermal initiators and/or various other additives.

The light transmittance of the laminate of the second layer 200 and the first protective layer 500 may be about 82% or greater, such as 82%, about 83%, about 84%, about 85%, about 86%, about 87% %, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99% or About 100%, specifically about 82% to about 95%. Within this range, the laminate can improve screen visibility by improving the transmittance of light emitted from the polarizer. level one

The first layer 100 may be formed on the light exit surface of the polarizer 400 and serve to transmit light emitted from the polarizer.

The refractive index of the first layer 100 may be about 1.55 or less, specifically about 1.4 to about 1.55. Within this range, the difference in refractive index between the first layer and the second layer within the above-mentioned range can be easily achieved.

The first layer 100 may be formed of any suitable composition as long as the first layer can provide a refractive index within the above range. Specifically, the first layer may be formed of a composition including an ultraviolet curable resin and/or a thermosetting resin. For example, the resin may include at least one selected from (meth)acrylic resin, polycarbonate resin, silicone resin and epoxy resin, but is not limited thereto. The composition may further include at least one selected from the group consisting of photoinitiators and thermal initiators and/or various other additives.

The first layer 100 may be an adhesive layer or a non-adhesive layer that does not exhibit adhesiveness. The optical stack including the adhesive first layer allows the first layer to be stacked on the polarizer or any protective layer without the adhesive layer, thereby providing additional reduction in thickness of the optical stack.

In one embodiment, the first layer 100 may be free of core-shell particles, or may include core-shell particles. patterned part

The pattern layer 300 may include a patterned portion at the interface between the second layer 200 and the first layer 100 . The patterned portion may include at least one engraved pattern 210 and a separation surface 220 between two adjacent engraved patterns. With the patterned portion, the patterned layer can achieve a significant improvement in viewing angle and contrast on the lateral side of the screen of the liquid crystal display. "Engraved pattern" means a raised pattern protruding from the lower surface of the pattern layer toward the second layer. In one embodiment, the patterned portion is formed by repeated combinations of the engraved pattern and the separating surface.

The second layer 200 may include at least one engraving pattern 210 and a separation surface 220 between two adjacent engraving patterns.

The aspect ratio of the engraved pattern 210 may be about 0.5 to about 4.0. Within this range, the engraved pattern can significantly improve the viewing angle and contrast on the lateral side of the screen of the liquid crystal display. Preferably, the aspect ratio of the engraved pattern is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, specifically about 0.5 to about 3.0, more specifically about 0.5 to about 2.0. Within this range, the engraved pattern can significantly improve the viewing angle and contrast on the lateral side of the screen of the liquid crystal display.

The engraved pattern 210 is composed of a first facet 211 formed at a top portion thereof and lateral sides connected to the first facet 212 . For ease of description, the surface formed at the top portion of the engraved pattern is referred to as the first facet.

"Lateral side" means the entire surface portion of the engraved pattern sandwiched between the top portion (specifically, the first facet 211 ) and the separation surface 220 to connect the top portion to the separation surface.

The first facet 211 allows the vertical component of light that has passed through the polarizer to pass therethrough, thereby improving frontal contrast and brightness. The first facet 211 may be parallel to the maximum width of the engraved pattern or separation surface, and may be a flat surface. Alternatively, the first facet may have roughness on its surface.

The width of the first facet 211 may be greater than 0 μm to 10 μm, preferably 2 μm to 8 μm. Within this range, the first facet 211 can improve the front contrast and brightness on the lateral side of the screen of the liquid crystal display.

Lateral sides 212 may include flat surfaces, curved surfaces, or combinations thereof. Here, "combined" means a surface that includes both a flat surface and a curved surface.

The flat surface may be one flat surface, as shown in FIG. 1 , or may be a polygonal surface composed of at least 2, in particular 2 to 10 flat surfaces connected to each other. The flat surface may be raised from the second layer 200 toward the first layer 100 , or raised from the first layer 100 toward the second layer 200 .

The curved surface may be one curved surface, or may be a curved surface composed of at least 2, in particular 2 to 10, curved surfaces having different radii of curvature and connected to each other. The curved surface may be a convex surface protruding from the second layer 200 toward the first layer 100 or from the first layer 100 toward the second layer 200 .

The engraving pattern 210 may satisfy Relation 1, and the base angle (θ) may be about 70° to about 90°, specifically, about 70° to about 85°. Within this range, engraved patterns can help improve frontal contrast and brightness. Here, the base angle θ refers to the angle formed between a portion of the lateral side of the embossed pattern directly connected to the separating surface thereof and the width of the embossed pattern. Preferably, the P/W value of the engraved pattern 210 is, for example, about 1.1, 1.2, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9 , 9.5 or 10, specifically about 1.2 to about 4. 1 < P/W ≤ 10, ---(1) where P indicates the pitch (unit: micrometer) of the engraving pattern, and W indicates the maximum width (unit: micrometer) of the engraving pattern.

The maximum width (W) of the engraved pattern 210 may be about 5 micrometers to about 20 micrometers, specifically, about 8 micrometers to about 15 micrometers. Within this range, the optical laminate can easily achieve the aspect ratio according to the present invention.

The height (H) of the engraved pattern 210 may be about 5 micrometers to about 25 micrometers, specifically, about 5 micrometers to about 20 micrometers. Within this range, the optical laminate can easily achieve the aspect ratio according to the present invention.

As shown in FIG. 1 , the engraving pattern 210 may have a trapezoidal shape having a rectangular cross-sectional shape. However, it should be understood that the present invention is not limited thereto, as long as the engraved pattern has the first facet and lateral sides as described above.

The separation surface 220 is used to diffuse light reaching the separation surface while maintaining frontal contrast and brightness. The separation surface can be a flat surface, a curved surface or a rough surface. Preferably, the separation surface is a flat surface to enable easy formation of the patterned portion.

The width L of the separation surface 220 may be 1 micrometer to 300 micrometers, specifically, 3 micrometers to 50 micrometers. Within this range, the separation surface can improve frontal brightness.

The ratio of the maximum width of the engraved pattern to the width of the separation surface may be about 9 or less, specifically about 0.1 to about 5, and more specifically about 0.1 to about 3. Within this range, the engraved pattern improves frontal brightness while reducing the difference between frontal and lateral contrast.

The pitch P of the patterned portions may be about 5 micrometers to about 500 micrometers, specifically, about 10 micrometers to about 50 micrometers. Within this range, the patterned portion can improve brightness and contrast, while preventing a moiré phenomenon.

FIG. 1 shows a cross section of the engraving pattern taken along the maximum width direction. Although not shown in FIG. 1, the engraved pattern may have a striped shape.

The longitudinal direction of the engraving pattern 210 may be inclined by an angle of about -20° to about +20°, eg, about -5°, with respect to the absorption axis (0°) of the polarizer 400 (the machine direction (MD) of the polarizer) to an angle of about +5°, or an angle of 0°. Within this range, the engraving pattern 210 can improve the suppression of the moiré phenomenon.

The first layer 100 may be formed with filling patterns 110 filling at least a portion of the engraving patterns 210 . The engraved pattern 210 may be completely or partially filled with the filling pattern 110 . The filling pattern 110 may be formed of the above-described composition for the first layer. first protective layer

The first protective layer 500 may be formed on the second layer 200 to support the first layer 100 and the second layer 200 . The first protective layer 500 is a light-transmitting layer, and allows light emitted from the optical display device and having diffused through the first and second layers to pass therethrough. The first protective layer 500 may be directly formed on the second layer 200 .

The first protective layer 500 may be integrally formed with the second layer 200 . As used herein, "integral" means that the protective layer is not independent of the first layer.

The first protective layer 500 may be a retardation film having a predetermined retardation range, a retardation coating, an isotropic optical film or an isotropic coating. In one embodiment, the Re of the first protective layer may be about 6,000 nanometers or more, about 8,000 nanometers or more, specifically about 10,000 nanometers or more, more specifically about 10,000 nanometers or more More specifically, greater than about 10,000 nanometers, more specifically about 10,100 nanometers to about 15,000 nanometers. Within this range, the first protective layer can prevent rainbow spots from being visible and can promote the diffusion of light diffused through the second layer. In another embodiment, the protective layer may have a Re of about 60 nm or less, specifically about 0 nm to about 60 nm, more specifically about 40 nm to about 60 nm m of isotropic optical films. Within this range, the first protective layer can compensate the viewing angle to improve image quality. "Isotropic optical film" means an optical film having substantially the same nx, ny, and nz values. Here, the expression "substantially the same" includes not only the case where nx, ny, and nz are identical, but also the case where acceptable tolerances exist.

The thickness of the first protective layer 500 may be 30 micrometers to 120 micrometers, specifically, 55 micrometers to 105 micrometers. Within this range, the protective layer can be used in an optical display device. The light transmittance of the first protective layer in the visible spectrum may be 80% or more, specifically, 85% to 95%. The protective layer may include a film formed by uniaxially or biaxially stretching an optically transparent resin. Specifically, the resin may include at least one selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate Polyester resins such as polyester, polybutylene naphthalate, acrylic resins, cyclic olefin polymer (COP) resins, cellulose ester resins including triacetylcellulose (TAC), Vinyl acetate, polyvinyl chloride (PVC), polynorbornene, polycarbonate (PC), polyamide, polyacetal, polyphenylene ether, polyphenylene sulfide, polysilicon, polyether Dust, polyarylate and polyimide resins. The first protective layer may include a film manufactured after resin modification. The modification may include copolymerization, branching, cross-linking or modification of the terminal molecules.

In one embodiment, the light transmittance of the laminate of the first layer, the second layer and the first protective layer may be about 70% to about 95%, specifically about 80% to about 90%. Within this range, the laminate can ensure good frontal and lateral visibility.

Although not shown in FIG. 1 , a functional layer may be formed on one surface or the other surface of the first protective layer. The functional layer may be a separate layer from the protective layer, or may be integrally formed therewith. The functional layer may include at least one layer selected from the group consisting of an anti-reflection layer, a low-reflection layer, a hard coat layer, an anti-glare layer, an anti-fingerprint layer, an anti-pollution layer, a diffusion layer, a refractive functional layer, and a primer layer.

Next, an optical laminate according to another embodiment of the present invention will be described.

The optical laminate according to this embodiment includes: a polarizer; and a pattern layer and a first protective layer sequentially stacked on the upper surface of the polarizer, wherein the pattern layer includes a first layer and a first protective layer sequentially stacked on the polarizer Two layers, and may further include a second protective layer stacked on the lower surface of the polarizer and/or a third protective layer sandwiched between the polarizer and the pattern layer. The optical laminate includes a second protective layer and/or a third protective layer, whereby additional functions are provided by the second protective layer and the third protective layer while improving the strength of the optical laminate.

The second protective layer and the third protective layer may be at least one selected from the plurality of protective layers described above with respect to the first protective layer.

Hereinafter, the optical laminate according to the present embodiment will be described with reference to FIG. 2 . FIG. 2 is a cross-sectional view of an engraved pattern of the optical laminate according to the present embodiment.

The optical laminate according to the present embodiment includes: a polarizer; and a pattern layer and a first protective layer sequentially stacked on the upper surface of the polarizer, wherein the pattern layer includes the first layer and The second layer, and has the engraving pattern shown in FIG. 2 instead of the engraving pattern shown in FIG. 1 . The optical laminate according to this embodiment is substantially the same as the optical laminate according to the above-described embodiments, except that the optical laminate according to this embodiment has the engraving pattern shown in FIG. 2 instead of the engraving pattern shown in FIG. 1 . same as above.

Referring to FIG. 2, lateral sides of the engraving pattern may include a first lateral facet 213 and a second lateral facet 214 that are continuous with each other. Each of the first lateral facet 213 and the second lateral facet 214 may be a flat surface or a curved surface.

In one embodiment, the lateral sides of the engraved pattern may consist of only the first lateral facet and the second lateral facet. In this embodiment, the first lateral facet 213 is directly connected to the separation surface 220 , and the second lateral facet 214 is directly connected to the first facet 211 .

In another embodiment, the lateral sides of the engraved pattern may include a first lateral facet 213, a second lateral facet 214, and a connecting facet that connects the first lateral facet 213 or the second lateral facet 214 is attached to the separation surface or first facet. The connecting surface may be a curved surface or a flat surface, but is not limited thereto. In one embodiment, the lateral sides of the engraving may be free of facets with the same base angle.

The first lateral facet 213 and the second lateral facet 214 have different base angles with respect to the maximum width W1 of the engraved pattern or a plane parallel thereto, and satisfy the relational expressions 2 and 3: θ1 > θ2, ---(2) where θ1 denotes the base angle of the first lateral facet, θ2 denotes the base angle of the second lateral facet, 70° ≤ θ1 ≤ 90°, and 0° < θ2 < 90°; and 0.5 ≤ h1/(h1 + h2) < 1.0, ---(3) where h1 indicates the projected height of the first transverse facet 213 on the maximum height H of the engraving pattern 210 , and h2 indicates the projected height of the second transverse facet 214 on its maximum height H.

Herein, "projected height" means a height corresponding to, for example, the height of the first lateral facet 213 of FIG. 2 relative to the maximum height H of the engraving pattern.

A first lateral facet and a second lateral facet having different base angles are continuously formed on lateral sides of the engraved pattern. When the base angle of the first lateral facet is greater than the base angle of the second lateral facet, the base angle θ1 of the first lateral facet may be in the range of 70° ≤ θ1 ≤ 90°; relative to the maximum height of the engraving pattern, The projected height of the first transverse facet on the maximum height of the engraved pattern may be about 0.5 times to less than about 1.0 times the entire projected height (of the first transverse facet and the second transverse facet); and the longitudinal and transverse dimensions of the engraved pattern The ratio exceeds 1.0, whereby the viewing angle and contrast on the lateral side of the engraving pattern are significantly improved.

Preferably, the base angle θ1 of the first lateral facet 213 is 70° to 90°, more preferably 75° to 90° or 80° to 85°. Within this range, the engraved pattern can help improve contrast and viewing angles, and can be easily formed.

Preferably, the base angle θ2 of the second lateral facet 214 is greater than 0° to less than 90° (about 0° < θ2 < 90°), more preferably 60° to 80°, 70° to 80° or 70°. ° to 75°. Within this range, the engraved pattern can help improve contrast and viewing angles, and can be easily formed.

Hereinafter, an optical laminate according to yet another embodiment will be described with reference to FIG. 3 . FIG. 3 is a cross-sectional view of the engraving pattern of the optical laminate according to the present embodiment.

The optical laminate according to the present embodiment includes: a polarizer; and a pattern layer and a first protective layer sequentially stacked on the upper surface of the polarizer, wherein the pattern layer includes the first layer and The second layer has the engraving pattern shown in FIG. 3 instead of the engraving pattern shown in FIG. 1 . The optical laminate according to this embodiment is substantially the same as the optical laminate according to the above-described embodiments, except that the optical laminate according to this embodiment has the engraving pattern shown in FIG. 3 instead of the engraving pattern shown in FIG. 1 . same as above.

Referring to FIG. 3 , lateral sides of the engraving pattern may include a first lateral facet 215 and a second lateral facet 216 that are continuous with each other. Each of the first lateral facet 215 and the second lateral facet 215 may be a flat surface or a curved surface.

The first lateral facet 215 and the second lateral facet 216 have different base angles with respect to the maximum width W1 of the engraving pattern, and satisfy the relational expressions 2 and 3: θ1 > θ2, ---(2) where θ1 denotes the base angle of the first lateral facet, θ2 denotes the base angle of the second lateral facet, 70° ≤ θ1 ≤ 90°, and 0° < θ2 < 90°; and 0.5 ≤ h1/(h1 + h2) < 1.0, ---(3) where h1 indicates the projected height of the first transverse facet 215 on the maximum height H of the engraved pattern 210, and h2 indicates the projected height of the second transverse facet 216 on its maximum height H.

A first lateral facet and a second lateral facet having different base angles are continuously formed on lateral sides of the engraved pattern. When the base angle of the first lateral facet is greater than the base angle of the second lateral facet, the base angle θ1 of the first lateral facet may be in the range of 70° ≤ θ1 ≤ 90°; relative to the maximum height of the engraving pattern, The projected height of the first transverse facet on the maximum height of the engraved pattern may be about 0.5 times to less than about 1.0 times the entire projected height (of the first transverse facet and the second transverse facet); and the longitudinal and transverse dimensions of the engraved pattern The ratio exceeds 1.0, thereby significantly improving the viewing angle and contrast ratio on the lateral side of the screen of the liquid crystal display.

Each of the first lateral facet 215 and the second lateral facet 216 may be a flat surface to enable easy formation of engraved patterns. Alternatively, at least one of the first lateral facet and the second lateral facet may be a curved surface or a flat surface having a curved surface formed on at least a portion thereof.

Preferably, the base angle θ1 of the first lateral facet 215 is 80° to 90°, more preferably 85° to 90° or 80° to 85°. Within this range, the engraved pattern can help improve contrast and viewing angles, and can be easily formed.

Preferably, the base angle θ2 of the second lateral facet 216 is greater than 0° to less than 90° (about 0° < θ2 < 90°), more preferably 60° to 80° or 70° to 80°. Within this range, the engraved pattern can help improve contrast and viewing angles, and can be easily formed.

The optical display device according to the present invention may include the optical laminate according to the present invention. For example, optical display devices may include light emitting diode displays including organic light emitting diode displays, liquid crystal displays, and the like.

In an embodiment, a liquid crystal display may include a backlight unit, a light source-side optical laminate, a liquid crystal panel, and a viewer-side polarizer stacked in the stated order, wherein the viewer-side polarizer may include the optical laminate 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 not Just that.

Next, the present invention will be described in more detail with reference to 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 (1) Preparation of the second layer composition

By mixing 50 parts by weight of an ultraviolet curable resin (SSC5410, SHIN-A T&C Co., Ltd.) and 50 parts by weight of the dispersion of Core-shell particles of core and zirconia shell, KC Tech Co., Ltd.), then the mixture was stirred at 200 rpm using Dispermat (VMS Ltd.) for 1 hours to prepare a second layer composition. (2) Preparation of the first layer composition

It was prepared by mixing 55.2 wt % of an acrylic copolymer (N9695, Nippon Synthesis Co., Ltd.) and 44.8 wt % of methyl ethyl ketone, followed by stirring the mixture at 500 rpm for 30 minutes. A first layer composition was prepared. (3) Manufacture of optical laminates

By stretching the polyvinyl alcohol film to 3 times its original length at 60°C, dyeing the stretched film with iodine, and further stretching the film to 2.5 in aqueous boric acid at 40°C A polarizer (thickness: 13 μm, light transmittance: 44%) was prepared by doubling.

A polyethylene terephthalate (PET) film (Toyobo Co. , Ltd.), thickness: 80 μm) to the upper surface of the polarizer, and a cyclic olefin polymer (COP) film (Zeoon) was bonded using an adhesive for polarizing plates (Z-200, Japan Gosher Co., Ltd.). Co., Ltd. (ZEON Co., Ltd.) is bonded to the lower surface of the polarizer.

The prepared second layer composition was placed on a polyethylene terephthalate film having a low reflection layer (wherein the low reflection layer was formed on the upper surface of the PET film, and the primer layer was formed under it On the surface, between the lower surface of DSG-17 (Z) PET80, DNP Co., Ltd.) and the molding film for forming the patterned portion, and extrusion was performed, followed by ultraviolet irradiation. Then, the molded film was removed from the resulting product to form a second layer on the lower surface of the polyethylene terephthalate film.

As shown in Figure 1, a patterned portion (W: 8 μm, H: 5 μm, P: 15 μm, θ: 82°) was formed on the second layer.

The first layer composition was deposited to a predetermined thickness on the lower surface of the second layer, and dried in an oven at 90° C. for 4 minutes to form the first layer on the lower surface of the second layer, thereby preparing a A laminate of a low-reflection layer, a second layer, and a polyethylene terephthalate film of the first layer. The first layer has an index of refraction and adhesion of 1.474.

The optical laminate was prepared by attaching the laminate to the upper surface of the PET film through the first layer of the laminate. Example 2 to Example 4

A second layer composition and an optical laminate were prepared in the same manner as in Example 1 except that the components of the second layer composition were changed as listed in Table 1. Comparative Example 1 to Comparative Example 4

A second layer composition and an optical laminate were prepared in the same manner as in Example 1 except that the components of the second layer composition were changed as listed in Table 1. Comparative Example 5

Polarizers were fabricated in the same manner as in Example 1. By adhering a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., thickness: 80 μm) to the polarizer via an adhesive for polarizing plate (Z-200, Japan Gosher Co., Ltd.) Optical stacks were fabricated by adhering a cycloolefin polymer (COP) film (Zeon Co., Ltd.) to the lower surface of the polarizer via an adhesive (Z-200, Japan Gosher Co., Ltd.) for polarizers on the upper surface. layer body.

Details of the second layer compositions used in the Examples and Comparative Examples are shown in Table 1. Dispersions of core-shell particles 1 to 6, dispersions of zirconia particles and dispersions of titanium dioxide particles were obtained from KC Technologies Ltd. Table 1 example Comparative example 1 2 3 4 1 2 3 4 SSC5410 50 50 53 56 35 65 35 53 Dispersion containing core-shell particles 1 50 - - - - - - - Dispersion containing core-shell particles 2 - 50 - - - - - - Dispersions containing core-shell particles 3 - - 47 - - - - - Dispersions containing core-shell particles 4 - - - 44 - - - - Dispersions containing zirconia particles - - - - 65 - - - Dispersions containing titanium dioxide particles - - - - - 35 - - Dispersion containing core-shell particles 5 - - - - - - 65 - Dispersion containing core-shell particles 6 - - - - - - - 47 Refractive index of the second layer composition 1.61 1.61 1.61 1.61 1.61 1.61 1.61 1.63

The following properties shown in Table 1 were evaluated for each of the optical laminates fabricated in the Examples and Comparative Examples. < Manufacture of light source side optical laminate >

By stretching the polyvinyl alcohol film to 3 times its original length at 60°C and dyeing the stretched film with iodine, then stretching the dyed film to 2.5 times in aqueous boric acid at 40°C And made polarizers. By adhering a cycloolefin polymer (COP) film (Zeon Co., Ltd.) to the upper surface of the polarizer via an adhesive for polarizing plate (Z-200, Japan Gosher Co., Ltd.), and attaching polyterephthalate A ethylene formate (PET) film (Toyobo Co., Ltd., thickness: 80 μm) was adhered to the lower surface of the polarizer via an adhesive for polarizer (Z-200, Japan Gosher Co., Ltd.) to manufacture the light source side polarizer. < Manufacture of liquid crystal display modules >

By sequentially assembling a light emitting diode (LED) light source, a light source side polarizer, a liquid crystal panel (PVA mode), and in each of the optical laminates fabricated in the examples and comparative examples, a single product including a single A liquid crystal display module of an edge-type light source with the same configuration as a Samsung television (TV) (55", model: UN55KS8000F). A patterned layer was placed on the light exit surface of the polarizer.

(1) Concentration ratio: The concentration ratio was measured by inductively coupled plasma optical spectroscopy (ICP-OES). About 0.02 grams to about 0.03 grams of dispersion samples containing inorganic particles are weighed in a Teflon container for microwave use. Then, 5 ml of nitric acid and 1 ml of hydrofluoric acid were injected into the vessel, which was then closed and placed in a microwave digestion apparatus. The device was run at 200°C for 1 hour to dissolve organic and inorganic materials. After the release of coldness, the disappearance of the shape of the sample was confirmed, and the sample was placed in a 100 ml polyethylene (PE) bottle and diluted to about 100 g with distilled water. Next, the concentration ratio of the samples was measured using ICP-OES.

(2) Brightness and relative brightness: use EZContrast (EZContrast) X88RC (EZXL-176R-F422A4, ELDIM S.A.) in the spherical coordinate system in the manufactured liquid crystal display module The positive side (0°,0°) of , measures the brightness in white mode. Relative luminance was calculated by calculating the ratio of luminance in each of the Example and Comparative Example to that of Comparative Example 5.

(3) Transmittance (unit: %): Referring to Examples and Comparative Examples, a second layer was formed on one surface of a polyethylene terephthalate (PET) film having a low reflection layer. Then, the transmittance of the laminate of the PET film and the second layer was measured using a light transmittance tester (NDH2000, Nippon Denshoku Co., Ltd.).

(4) Cross-cut: Referring to Examples and Comparative Examples, a laminate of the second layer and the first layer was formed on the polyethylene terephthalate film having the low-reflection layer, and then Crosscuts are measured according to ASTM D3359. After performing a cross-section experiment on 100 samples, the number of remaining samples was counted. The higher the number of remaining samples, the higher the adhesion of the second layer to the polyethylene terephthalate film with the low reflectivity layer. Table 2 example Comparative example 1 2 3 4 1 2 3 4 5 Second floor refractive index 1.633 1.633 1.634 1.634 1.633 1.635 1.633 1.654 - Particle content (wt%) 25.5 25.5 24.0 22.4 33.2 17.9 33.2 24.0 - particle type core-shell particle 1 core-shell particle 2 core-shell particle 3 core-shell particle 4 Zirconia Titanium dioxide core-shell particle 5 Core-Shell Particles 6 - Concentration ratio (Ti:Zr) 1:7.3 1:8 1:6.5 1:5.3 - - 1:9 1:4.5 - Average particle size (D50, nm) 14 14 14 14 14 14 14 14 - brightness brightness 452.1 451.6 436.4 424.8 452.6 403.9 453.1 393.4 524.5 relative brightness 86 86 83 81 86 77 86 75 100 Transmittance 86 86 84 82 86 78 86 77 - cross cut 100/100 100/100 100/100 100/100 54/100 100/100 56/100 100/100 -

As shown in Table 2, in the optical laminate according to the present invention, the protective layer and the second layer have suitable light transmittances with respect to the polarizer. Accordingly, although not shown in Table 2, the optical laminate according to the present invention has good screen visibility. Furthermore, the optical laminate according to the present invention has good adhesion to the protective layer and allows a high improvement in brightness. In addition, although not shown in Table 2, the optical laminates according to the present invention have better lateral contrast ratios than the optical laminates of Comparative Examples 1 to 5.

Accordingly, the present invention provides an optical laminate including a second layer having high light transmittance and high refractive index. The present invention provides an optical laminate comprising a pattern layer or a laminate of a pattern layer and a protective layer, the pattern layer having a suitable light transmittance relative to a polarizer to improve screen visibility. The present invention provides an optical laminate including a second layer having good adhesion to a protective layer or a first layer while ensuring improved brightness and contrast.

In contrast, the optical laminates of Comparative Examples 1 to 5 each including a second layer not satisfying the characteristics of the present invention did not provide any effect of the present invention.

Although some embodiments have been described herein, it should be understood that various modifications, changes, alterations and equivalent embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention.

100: first floor 110: Fill Pattern 200: second floor 210: Engraving Pattern 211: The first facet 212: Lateral side 213, 215: First transverse facet 214, 216: Second transverse facet 220: Separation Surface 300: Pattern Layer 400: polarizer 500: first protective layer H: height h1, h2: projection height L: width P: pitch W: maximum width θ, θ1, θ2: base angle

1 is a cross-sectional view of an optical laminate according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of an engraved pattern of the optical laminate shown in FIG. 1 . 3 is a cross-sectional view of an engraved pattern of an optical laminate according to another embodiment of the present invention.

100: first floor

110: Fill Pattern

200: second floor

210: Engraving Pattern

211: The first facet

212: Lateral side

300: Pattern Layer

400: polarizer

500: first protective layer

H: height

L: width

P: pitch

W: maximum width

θ: base angle

Claims (16)

An optical stack, comprising: polarizers; and a patterned layer, stacked on one surface of the polarizer, wherein the pattern layer includes a first layer and a second layer sequentially stacked on the polarizer, and a patterned portion is formed at the interface between the first layer and the second layer, the second layer has a higher refractive index than the first layer and contains core-shell particles having a titania-containing core and a zirconia-containing shell surrounding the titania-containing core, The core-shell particles comprise titania and zirconia in a concentration ratio of titania:zirconia of 1:5 to 1:8. The optical stack of claim 1, wherein the core-shell particles are present in the second layer in an amount from about 5% to about 60% by weight. The optical stack of claim 1, wherein the core-shell particles have an index of refraction of about 2.0 or greater. The optical stack of claim 1, wherein the core-shell particles have an average particle size (D50) of about 10 nanometers to about 100 nanometers. The optical stack of claim 1, wherein the second layer comprises a matrix and the core-shell particles embedded in the matrix, the matrix having a lower refractive index than the core-shell particles . The optical stack of claim 1, wherein the second layer has a light transmittance of about 82% or greater. The optical laminate of claim 1, wherein the pattern layer has a light transmittance of about 82% or greater. The optical stack of claim 1, wherein the difference in refractive index between the second layer and the first layer is about 0.5 or greater, and the second layer has a refractive index of about 1.60 or greater refractive index. The optical laminate of claim 1, wherein the patterned portion includes at least one engraving pattern and a separation surface between two adjacent engraving patterns. The optical laminate of claim 9, wherein the engraved pattern has a first facet formed at a top portion thereof and lateral sides connected to the first facet. The optical stack of claim 10, wherein the lateral side comprises a flat surface or a curved surface. The optical stack of claim 10, wherein the lateral side is raised from the second layer toward the first layer or from the first layer toward the second layer. The optical laminate according to claim 1, further comprising: a first protective layer formed on the upper surface of the second layer. The optical laminate of claim 13, wherein the laminate of the second layer and the first protective layer has a light transmittance of 82% or more. The optical laminate according to claim 1, further comprising: a second protective layer stacked on the lower surface of the polarizer and/or a third protective layer stacked between the polarizer and the pattern layer. An optical display device comprising the optical laminate according to any one of claim 1 to claim 15.

Images