Polarizing plate and liquid crystal display including the same

Abstract

The present invention discloses a polarizing plate and a liquid crystal display including the same. The polarizing plate comprises: a polarizer; and a pattern layer, which is formed on one surface of the polarizer and includes a high refractive index layer having at least one engraved pattern and a low refractive index layer having a filling pattern that fills at least a portion of the engraved pattern, the polarizing plate further includes a first protective layer, the polarizing plate has a stacking structure in which a polarizer, a low refractive index layer, a high refractive index layer and a first protective layer are sequentially stacked, or a stacking structure in which a polarizer, a first protective layer, a low refractive index layer and a high refractive index layer are sequentially stacked, wherein the first protective layer includes a base film formed of at least one resin selected from triacetyl cellulose, polyethylene terephthalate, a cycloolefin polymer and an acrylic resin; and wherein the high refractive index layer has a higher refractive index than the low refractive index layer. The present invention provides a polarizing plate capable of improving the side contrast ratio, the side viewing angle and the brightness uniformity.

Description

[0001] The present invention is a divisional application of the invention patent application with application number 201610108075.0 filed on February 26, 2016 and invention name “Polarizing plate and liquid crystal display including a polarizing plate”. Technical Field

[0002] The invention relates to a polarizing plate and a liquid crystal display comprising the polarizing plate. Background Art

[0003] The liquid crystal display is operated to emit light through the liquid crystal panel after receiving light from the backlight unit. Therefore, the liquid crystal display provides good color quality on its front side. However, in terms of color quality, contrast ratio and / or viewing angle, the liquid crystal display exhibits lower properties on its side than on its front side.

[0004] A liquid crystal display comprises a polarizing plate, a liquid crystal panel and a backlight unit. In order to improve the color quality and contrast ratio at the side of the liquid crystal display, various attempts have been made to develop an improved liquid crystal panel or liquid crystal structure. However, the modification of the liquid crystal panel has limitations on the improvement of the color quality and contrast ratio at the side of the liquid crystal display and requires a complicated process. In addition, as the screen size of the liquid crystal display increases, the brightness uniformity of the liquid crystal display also continues to decrease. Therefore, a separate liquid crystal display module must be provided depending on the screen size, thereby reducing the processability and economic feasibility.

[0005] An example of the background art is disclosed in Japanese Patent Laid-Open No. 2006-251659. Summary of the invention

[0006] According to one aspect of the present invention, a polarizing plate may include: a polarizer; and a pattern layer formed on one surface of the polarizer and including a high refractive index layer having at least one engraved pattern and a low refractive index layer having a filling pattern filling at least a portion of the engraved pattern, and the polarizing plate may further include a first protective layer, the polarizing plate having a stacking structure in which a polarizer, a low refractive index layer, a high refractive index layer and a first protective layer are stacked in sequence or a stacking structure in which a polarizer, a first protective layer, a low refractive index layer and a high refractive index layer are stacked in sequence, wherein the first protective layer includes a base film formed of at least one resin selected from the group consisting of triacetyl cellulose, polyethylene terephthalate, a cycloolefin polymer and an acrylic resin, and wherein the high refractive index layer has a higher refractive index than the low refractive index layer.

[0007] According to an embodiment of the present invention, the engraved pattern may include an optical pattern having a curved surface or a prism pattern having a triangular to decagonal cross section.

[0008] According to one embodiment of the present invention, the engraved pattern may include an optical pattern having a truncated triangular cross-sectional prism shape, a truncated biconvex lens shape, or a shape including one or more flat surfaces at the uppermost surface of the optical pattern and having an n-gonal cross-section, wherein n is an integer of 5 or greater.

[0009] According to an embodiment of the present invention, the high refractive index layer may further include a flat portion between adjacent engraved patterns.

[0010] According to an embodiment of the present invention, a ratio of a maximum pitch of the engraved pattern to a pitch of the flat portion may be 1 or less.

[0011] According to an embodiment of the present invention, the refractive index difference between the high refractive index layer and the low refractive index layer may be 0.30 or less.

[0012] According to an embodiment of the present invention, the first protective layer has an in-plane retardation of 8,000 nm or more at a wavelength of 550 nm, and is formed of the polyethylene terephthalate resin.

[0013] According to an embodiment of the present invention, the first protective layer includes a base film and a primer layer formed on at least one surface of the base film, and a ratio of a refractive index of the primer layer to a refractive index of the base film may be 1.0 or less.

[0014] According to an embodiment of the present invention, the first protective layer has a light transmittance of 90% or more at a wavelength of 550 nm.

[0015] According to an embodiment of the present invention, the first protective layer is formed by uniaxially stretching a base film formed of the polyethylene terephthalate resin.

[0016] According to an embodiment of the present invention, a low refractive index layer, a high refractive index layer and a first protective layer are sequentially stacked on the polarizer.

[0017] According to an embodiment of the present invention, the high refractive index layer is directly formed on the first protective layer.

[0018] According to an embodiment of the present invention, the polarizing plate may further include a bonding layer formed between the polarizer and the low refractive index layer.

[0019] According to an embodiment of the present invention, the polarizing plate may further include a second protective layer formed on the other surface of the polarizer.

[0020] According to an embodiment of the present invention, the second protective layer may include a film formed of at least one of triacetyl cellulose, polyethylene terephthalate, cycloolefin polymer, and acrylic resin.

[0021] According to another aspect of the present invention, a liquid crystal display may include the polarizing plate as described above.

[0022] The present invention provides a polarizing plate capable of improving a side contrast ratio, a side viewing angle, and brightness uniformity while minimizing a change in brightness uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0024] Figure 2 for Figure 1 An exploded perspective view of the pattern layer of the polarizing plate shown in FIG.

[0025] Figure 3 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0026] Figure 4 FIG. 4 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0027] Figure 5 FIG. 4 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0028] Figure 6 FIG. 4 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0029] Figure 7 FIG. 4 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0030] Figure 8 is a perspective view of a liquid crystal display according to an embodiment of the present invention.

[0031] Fig. 9 This is a picture of the display when measuring brightness uniformity. DETAILED DESCRIPTION

[0032] Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can practice the present invention. It should be understood that the present invention can be implemented in different ways and is not limited to the following embodiments. In the accompanying drawings, parts irrelevant to the description will be omitted for clarity. Throughout this specification, the same components will be represented by the same drawing element symbols.

[0033] As used herein, spatially relative terms such as "on" and "under" are defined with reference to the accompanying drawings. Therefore, it should be understood that "on" and "under" can be used interchangeably. It should be understood that when a layer is referred to as being "on" another layer, the layer may be formed directly on the other layer or there may be intervening layers. Therefore, it should be understood that when a layer is referred to as being "directly on" another layer, there are no intervening layers therebetween.

[0034] As used 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.

[0035] As used herein, the term “side surface” means an area where θ ranges from 60° to 90° (Φ, θ) in a spherical coordinate system, where, with reference to the horizontal direction, the front side is indicated by (0°, 0°), the left endpoint is indicated by (180°, 90°), and the right endpoint is indicated by (0°, 90°).

[0036] As used herein, the term "aspect ratio" refers to the ratio of the maximum height of an optical structure to the maximum width of the optical structure (maximum height / maximum width). As used herein, the term "period" means the distance between adjacent engraved patterns, such as the sum of the pitch of one engraved pattern and the pitch of one flat portion in the high refractive index layer of the pattern layer. As used herein, the term "in-plane retardation (Re)" is represented by equation A, the term "out-of-plane retardation (Rth)" is represented by equation B, and the term "degree of biaxiality (NZ)" is represented by equation C:

[0037] <Equation A>

[0038] Re=(nx-ny)xd

[0039] <Equation B>

[0040] Rth=((nx+ny) / 2-nz)xd

[0041] <Equation C>

[0042] NZ=(nx-nz) / (nx-ny)

[0043] (where nx, ny and nz are the refractive indices at a wavelength of 550 nm in the slow axis direction, fast axis direction and thickness direction of the corresponding optical device, respectively, and d is the thickness of the corresponding optical device (in nm)).

[0044] As used herein, nx, ny, and nz are refractive indices at a wavelength of 550 nm in the slow axis direction, the fast axis direction, and the thickness direction of the corresponding optical device, respectively.

[0045] As used herein, the term "brightness uniformity" is a value calculated by {(minimum brightness) / (maximum brightness)} x 100. Here, see Fig. 9 , in a liquid crystal display constructed by assembling a light source, a light guide plate, and a liquid crystal display module, the brightness is measured at each of points A, B, and C, where the center point, the left end point, and the right end point of the display screen 1 are indicated by B, A, and C, respectively, and the maximum brightness value (maximum brightness) and the minimum brightness value (minimum brightness) are obtained. When measuring the brightness, a brightness tester EZ Contrast Analyzer X88RC (EZXL-176R-F422A4, Eldim Co., Ltd.) is fixed to point B and then guided to face each of points A, B, and C. Fig. 9 , place A, B, and C on the same line.

[0046] As used herein, the term "(meth)acryloyl" refers to acryloyl and / or methacryloyl.

[0047] As used herein, the term "top portion" refers to a portion located at an uppermost portion relative to a lowermost portion of a certain structure. Herein, the refractive index is a value measured using an Abber refractometer at a wavelength of 550 nm.

[0048] In the following, we will refer to Figure 1 and Figure 2 A polarizing plate according to one embodiment of the present invention is described in detail. Figure 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention, and Figure 2 for Figure 1 An exploded perspective view of the pattern layer of the polarizing plate shown in FIG.

[0049] See also Figure 1 , a polarizing plate 100 according to one embodiment may include a polarizer 10 , a pattern layer 20 , a first protective layer 30 , and a bonding layer 40 .

[0050] The polarizer 10 may be formed on the pattern layer 20, and may polarize light entering the polarizing plate. The polarizer 10 may include a typical polarizer known to those skilled in the art. Specifically, the polarizer 10 may include a polyvinyl alcohol polarizer obtained by uniaxially stretching a polyvinyl alcohol film along a machine direction (machine direction; MD), or a polyene polarizer obtained by dehydrating a polyvinyl alcohol film. The thickness of the polarizer 10 may be about 1 μm to about 60 μm, specifically about 2 μm to about 50 μm, and more specifically about 2 μm to about 30 μm. Within this thickness range, the polarizer may be used in a liquid crystal display, and may have an advantage in thickness reduction. Although Figure 1Although not shown in the figure, the polarizer 10 may further include an adhesive layer on the lower side thereof to promote the adhesion of the polarizing plate 100. Specifically, the adhesive layer may be formed of an adhesive composition including an adhesive resin such as (meth) acrylic resin, epoxy resin, silicone resin and the like, optionally including a curing agent, and optionally including a silane coupling agent.

[0051] The pattern layer 20 may be formed on the polarizer 10 and may diffuse polarized light received from the polarizer 10. As a result, a liquid crystal display including the polarizing plate 100 according to this embodiment may have a strong contrast ratio on the side of the liquid crystal display while improving the viewing angle and visibility and brightness uniformity at the side thereof. The thickness of the pattern layer 20 may be about 40 μm or less, specifically about 3 μm to about 40 μm, and more specifically about 5 μm to about 30 μm. Within this thickness range, the pattern layer may be used in a liquid crystal display and may have advantages in thickness reduction while improving viewing angle, visibility, and brightness uniformity without affecting other optical properties.

[0052] See also Figure 1 and Figure 2 The pattern layer 20 may include a high refractive index layer 202 (which includes at least one engraved pattern 207 ) and a low refractive index layer 201 (which includes a filling pattern 205 filling at least a portion of the engraved pattern 207 ).

[0053] The high refractive index layer 202 may be formed on the low refractive index layer 201 and may diffuse light that has reached the low refractive index layer 201 and is not reflected by the flat portion 206 toward the filling pattern 205 , thereby significantly improving the effects of light collection and diffusion.

[0054] The high refractive index layer 202 may have a higher refractive index than the low refractive index layer 201. Specifically, the refractive index of the high refractive index layer 202 may be about 1.50 or more than 1.50, specifically about 1.50 to about 1.65, more specifically about 1.50 to about 1.60. Within this range, the high refractive index layer 202 can ensure a good light diffusion effect. The high refractive index layer 202 can be formed by a composition for a high refractive index layer, the composition comprising a UV-curable transparent resin, the refractive index of the UV-curable transparent resin being about 1.50 or more than 1.50, specifically about 1.50 to about 1.65, more specifically about 1.50 to about 1.60. Specifically, the transparent resin may include at least one of (meth) acrylic acid, polycarbonate, silicone and epoxy resin, but is not limited thereto. The composition for the high refractive index layer may further include a typical photoinitiator for forming the high refractive index layer. The refractive index difference between the high refractive index layer 202 and the low refractive index layer 201 (refractive index of the high refractive index layer-refractive index of the low refractive index layer) may be about 0.30 or less, specifically about 0.10 to about 0.15. Within this range, the pattern layer 20 can ensure good effects of light collection and diffusion.

[0055] The high refractive index layer 202 may further include a light diffuser to improve the light diffusion effect. The light diffuser may include an organic light diffuser, an inorganic light diffuser or a mixture thereof. A mixture of an organic light diffuser and an inorganic light diffuser may be beneficial to improving the diffusivity and transmittance of the high refractive index layer. In the high refractive index layer 202, the light diffuser may be used alone or as a mixture thereof. The organic light diffuser may include at least one of (meth) acrylic particles, siloxane particles and styrene particles. The inorganic light diffuser may include at least one of the following: calcium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide and zinc oxide. Specifically, the inorganic light diffuser may more advantageously prevent the whiteness from decreasing while improving the light diffusion rate more compared to the light diffuser including only the organic light diffuser. The light diffuser is not limited to a specific shape and particle size. Specifically, the light diffuser may include spherical cross-linked particles. The average particle size (D50) of the light diffuser may be about 0.1 μm to about 30 μm, specifically about 0.5 μm to about 10 μm. Within this range, the light diffuser can achieve a light diffusion effect, increase the surface roughness of the pattern layer, so that the bonding strength with the first protective layer is no longer a problem, and good dispersion can be ensured. In the high refractive index layer, the light diffuser may be present in an amount of about 0.1 wt% to about 20 wt%, specifically about 1 wt% to about 15 wt%. Within this range, the light diffuser can ensure a light diffusion effect.

[0056] See also Figure 2, the high refractive index layer 202 may have a first plane 204, which may include at least one engraved pattern 207 and at least one flat portion 206 formed thereon. Figure 2 The pattern layer is shown, which includes engraved patterns 207 and flat portions 206 arranged alternately thereon one by one. However, it should be understood that the formation sequence of the engraved patterns 207 and the flat portions 206 is not limited thereto. The engraved pattern 207 may be a lenticular lens pattern including a curved surface. The curved surface acts as a lens to diffuse the polarized light received from the polarizer 10 by refracting the light in various directions depending on the position where the light arrives thereon. Figure 2 The pattern layer 20 is shown, wherein the curved surface is an aspherical surface. However, the curved surface may include a spherical surface, a parabolic surface, an elliptical surface, a hyperbolic surface, or an amorphous surface, or may be implemented in a form including both a curved surface and a flat surface. In addition, although the double convex lens pattern is Figure 2 The engraved pattern 207 is described as a pattern layer, but the engraved pattern 207 may be a prism pattern having a triangular to decagonal cross section and a curved surface at its top portion. Figure 2 The curved surface is illustrated as having a smooth surface without roughness, but the curved surface may further include roughness to improve the light diffusion effect.

[0057] Although the engraved pattern 207 is not limited to a specific aspect ratio, the aspect ratio of the engraved pattern may be, for example, about 1.0 or less, specifically about 0.4 to about 1.0, and more specifically about 0.7 to about 1.0. Within this aspect ratio range, the engraved pattern can increase the contrast ratio and viewing angle at the side and the brightness uniformity, while minimizing the change in brightness uniformity immediately after the screen size of the liquid crystal display increases. Figure 1 , the aspect ratio refers to the ratio of the maximum height of the engraved pattern to the maximum spacing. The ratio of the sum of the maximum spacings of the engraved pattern 207 to the total width of the high refractive index layer 202 can range from about 40% to about 60%, specifically about 45% to about 55%. Within these aspect ratio and width ratio ranges, the engraved pattern can increase the contrast ratio and viewing angle at the side and the brightness uniformity, while minimizing the change in brightness uniformity immediately after the screen size of the liquid crystal display increases. See again Figure 1, the maximum pitch (P1) of the engraved pattern 207 may be about 20 μm or less, specifically about 10 μm or less, more specifically about 5 μm to about 10 μm. The maximum height (H1) of the engraved pattern 207 may be about 16 μm or less, specifically about 10 μm or less, more specifically about 3.0 μm to about 10 μm. Within the range of these pitches and heights, the engraved pattern 207 can provide a light diffusion effect while suppressing the moiré phenomenon and making it easy to complete the machining. The engraved pattern 207 can be arranged in a predetermined period, thereby further improving the light diffusion effect. Specifically, the engraved pattern 207 can be arranged in a period (C) of about 20 μm or less, specifically about 10 μm to about 20 μm. Within this range, the engraved pattern 207 can ensure a strong effect in the collection and diffusion of light.

[0058] The flat portion 206 may be disposed between the engraved patterns 207 , and diffuse the light by totally reflecting the light through the engraved patterns 207 when the light reaches the flat portion 206 .

[0059] The ratio (P1 / P2) of the maximum pitch P1 of the engraved pattern 207 to the pitch P2 of the flat portion 206 may be about 1 or less, specifically about 0.5 to about 1.0. Within this range, the high refractive index layer can ensure a high effect in light collection and diffusion while suppressing the Moiré phenomenon. The pitch (P2) of the flat portion 206 may be about 10 μm or less, specifically about 5 μm to about 10 μm. Within this range, the flat portion can improve the contrast ratio while suppressing the Moiré phenomenon.

[0060] The low refractive index layer 201 may be formed on the polarizer 10 , and diffuses polarized light by refracting light in various directions depending on the incident position of light after receiving light in one direction from the polarizer 10 .

[0061] The refractive index of the low refractive index layer 201 may be less than about 1.50, specifically about 1.35 to less than about 1.50, and more specifically about 1.35 to about 1.49. Within this range, the low refractive index layer 201 can provide a high light diffusion effect and can facilitate the manufacture of the pattern layer. The low refractive index layer 201 can be formed from a composition for a low refractive index layer, the composition comprising a UV-curable transparent resin, the refractive index of the UV-curable transparent resin being less than about 1.50, specifically about 1.35 to less than about 1.50, and more specifically about 1.35 to about 1.49. Specifically, the transparent resin may include at least one of (meth) acrylic acid, polycarbonate, silicone, and epoxy resin, but is not limited thereto. The composition for the low refractive index layer may further include a typical photoinitiator for forming the low refractive index layer. See again Figure 2, the low refractive index layer 201 may include a second plane 203, which faces the first plane 204 of the high refractive index layer 202 and includes at least one filling pattern 205. The filling pattern 205 may fill at least a portion of the engraved pattern 207 of the high refractive index layer 202. As used herein, the expression "filling at least a portion" includes both a structure in which the filling pattern completely fills the engraved pattern 207 and a structure in which the filling pattern partially fills the engraved pattern 207. In the structure in which the filling pattern partially fills the engraved pattern, the remaining and unfilled portions of the engraved pattern may be filled with air or a resin having a predetermined refractive index. Specifically, the refractive index of the resin may be equal to or higher than the refractive index of the low refractive index layer, and equal to or lower than the refractive index of the high refractive index layer. Although Figure 2 A pattern layer in which the filling pattern 205 and the engraving pattern 207 extend in a stripe shape is shown, but the filling pattern 205 and the engraving pattern 207 may form a dot shape. As used herein, the term "dot" means that the combination of the filling pattern and the engraving pattern is dispersed. The low refractive index layer 201 may also further include the light diffuser described above. In the low refractive index layer, the light diffuser may be present in an amount of about 0.1wt% to about 20wt%, specifically about 1wt% to about 15wt%. Within this range, the light diffuser can ensure a light diffusion effect.

[0062] although Figure 1 and Figure 2 A pattern layer 20 is shown including a high refractive index layer 202 (which includes at least one engraved pattern 207 formed thereon) and a low refractive index layer 201 (which includes a fill pattern 205 that fills at least a portion of the engraved pattern 207), but the pattern layer may include a low refractive index layer having at least one engraved pattern 207 and a high refractive index layer including a fill pattern 205 that fills at least a portion of the engraved pattern 207.

[0063] Next, the first protective layer 30 will be described.

[0064] See again Figure 1 , the first protective layer 30 may be formed on the high refractive index layer 202 to protect the pattern layer 20 and the polarizer 10. Figure 1 A structure is shown in which the polarizer 10, the bonding layer 40, the low refractive index layer 201, the high refractive index layer 202 and the first protective layer 30 are stacked in sequence, but an embodiment of the present invention may also include a structure in which the polarizer 10, the bonding layer 40, the first protective layer 30, the low refractive index layer 201 and the high refractive index layer 202 are stacked in sequence.

[0065] The first protective layer 30 may be integrated with the pattern layer 20. As used herein, the term "integrated" means a state in which the first protective layer 30 and the pattern layer 20 are not independently separated from each other. For example, the first protective layer 30 may be directly formed on the high refractive index layer 202 without a binder interposed therebetween. Specifically, the high refractive index layer 202 may be a coating formed by applying a composition for a high refractive index layer to the first protective layer 30. The thickness of the first protective layer 30 may be about 150 μm or less, specifically about 20 μm to about 150 μm, more specifically about 30 μm to about 100 μm. Within this thickness range, the first protective layer 30 may be used in a liquid crystal display. The ratio of the thickness of the pattern layer 20 to the thickness of the first protective layer 30 (the thickness of the pattern layer / the thickness of the first protective layer) may be about 2 or less, specifically about 0.02 to about 0.75, more specifically about 0.1 to about 0.4. Within this range, the first protective layer can prevent the degradation of reliability (which is attributed to the penetration of external moisture into the polarizing plate) while suppressing the warping and wrinkling of the polarizing plate. At a wavelength of 550nm, the transmittance of the first protective layer 30 can be about 90% or more, specifically about 90% to about 99%. Within this range, when mounted on a polarizer, the first protective layer can increase the transmittance of the polarizing plate to eliminate the requirement for increased transmittance of the polarizer, thereby further improving the polarization degree of the polarizer. The first protective layer 30 may include a base film formed of an optically transparent resin. Specifically, the resin may include at least one selected from the following: polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate, acrylic resins, cyclic olefin polymers (COP) resins, cellulose resins containing triacetylcellulose (TAC) and the like. The first protective layer 30 may include a base film formed by modifying the aforementioned resin. The modification may include copolymerization, branching, crosslinking or modification of terminal molecules. In one embodiment, the in-plane retardation (Re) of the first protective layer 30 may be about 8,000 nm or more, about 10,000 nm or more, specifically higher than about 10,000 nm, more specifically about 10,100 nm to about 50,000 nm, and more specifically about 10,100 nm to about 15,000 nm. Within this range, the first protective layer 30 can prevent rainbow spots from being seen, suppress rainbow mura, minimize light leakage at the sides of the liquid crystal display, and prevent retardation changes depending on the incident angle of light.The out-of-plane retardation (Rth) of the first protective layer 30 may be about 15,000 nm or less, specifically about 10,000 nm to about 12,000 nm. The difference nx-ny of the first protective layer 30 may be about 0.1 to about 0.2. Within this range, the first protective layer 30 can prevent the generation of rainbow spots by suppressing the retardation variation depending on the incident angle and wavelength of light. The degree of biaxiality (NZ) of the first protective layer 30 may be about 1.8 or less, specifically about 1.5 to about 1.8, and more specifically about 1.5 to about 1.7. Within this range, the first protective layer 30 can prevent the generation of rainbow spots, minimize light leakage at the side of the liquid crystal display, prevent the retardation variation depending on the incident angle of light, and suppress the retardation variation depending on the wavelength of light. For the first protective layer 30, a ratio (Rth / Re) of out-of-plane retardation to in-plane retardation (Re) may be about 1.3 or less, specifically about 1.0 to about 1.2. Within this range, the first protective layer 30 may prevent the generation of rainbow spots. Figure 1Although not shown in the figure, the first protective layer 30 may include a base film and a primer layer formed on at least one surface of the base film. The base film may support the first protective layer 30 and may have a refractive index ratio relative to the primer layer in a predetermined range, thereby improving the transmittance of the first protective layer 30. Specifically, the refractive index ratio of the primer layer to the base film (refractive index of the primer layer / refractive index of the base film) may be about 1.0 or less than 1.0, specifically about 0.6 to about 1.0, more specifically about 0.69 to about 0.95, more specifically about 0.7 to about 0.9, and more specifically about 0.72 to about 0.88. Within this range, the base film can improve the transmittance of the first protective layer. The refractive index of the base film may be about 1.3 to about 1.7, specifically about 1.4 to about 1.6. Within this range, the base film may be applied to the first protective layer of the polarizing plate, which may facilitate the adjustment of the refractive index relative to the primer layer, and may improve the transmittance of the first protective layer. The in-plane retardation (Re) of the substrate film may be about 8,000 nm or more, about 10,000 nm or more, specifically higher than about 10,000 nm, more specifically about 10,100 nm to about 50,000 nm, and even more specifically about 10,100 nm to about 15,000 nm. Within this range, the substrate film can prevent the generation of rainbow spots, suppress rainbow moire, minimize light leakage at the side of the liquid crystal display, and minimize the delay variation depending on the incident angle and wavelength of light. The out-of-plane retardation (Rth) of the substrate film may be about 15,000 nm or less, specifically about 10,000 nm to about 12,000 nm. The difference nx-ny of the substrate film may be about 0.1 to 0.2. Within this range, the substrate film can prevent the generation of rainbow spots by minimizing the delay variation depending on the incident angle and wavelength of light. The degree of biaxiality (NZ) of the substrate film may be about 1.8 or less, specifically about 1.5 to about 1.8, and more specifically about 1.5 to about 1.7. Within this range, the substrate film can prevent the generation of rainbow spots and light leakage at the sides of the liquid crystal display, and minimize the delay variation depending on the incident angle and wavelength of light. For the substrate film, the ratio (Rth / Re) of the out-of-plane delay (Rth) to the in-plane delay (Re) may be about 1.3 or less, specifically about 1.0 to about 1.2. Within this range, the substrate film can prevent the generation of rainbow spots. The thickness of the substrate film may be about 150 μm or less, specifically about 20 μm to about 150 μm, and more specifically about 30 μm to about 100 μm. Within this range, the substrate film may be coated on the first protective layer. The substrate film may be obtained by uniaxially stretching a film formed of an optically transparent resin.Specifically, the resin may include at least one selected from the following: polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate, acrylic resins, cyclic olefin polymer (COP) resins, cellulose resins including triacetylcellulose (TAC) and the like. More specifically, the base film may be formed of polyethylene terephthalate resin to increase the strength of the base film, thereby improving the processability of the polarizing plate. The primer layer is formed between the base film and the pattern layer 20 to be directly disposed on the pattern layer 20 (upper side), and reinforces the adhesion between the base film and the pattern layer 20. The refractive index of the primer layer may be about 1.0 to about 1.6, specifically about 1.1 to about 1.6, and more specifically about 1.1 to about 1.5. Within the range of this refractive index, the primer layer can be used in a polarizing plate, and relative to the refractive index of the substrate film, it can show a suitable refractive index, thereby improving the transmittance of the first protective layer. The thickness of the primer layer can be about 1nm to about 200nm, specifically about 60nm to about 200nm. Within this thickness range, the primer layer can be used in a polarizing plate, and relative to the refractive index of the substrate film, it can show a suitable refractive index, thereby improving the transmittance of the first protective layer without brittleness. The primer layer can be a non-urethane primer layer without a urethane group. Specifically, the primer layer can be formed by a composition for the primer layer, the composition comprising resins and monomers such as polyester resins and acrylic resins. The primer layer can ensure the above refractive index by adjusting the mixing ratio (e.g., molar ratio) of these monomers. The composition for the primer layer may further include at least one additive, such as a UV absorber, an antistatic agent, a defoamer, a surfactant, and the like. The first protective layer 30 can be formed by the following steps: forming a primer layer on at least one surface of the base film, and then uniaxially stretching the film to about 2 to 10 times its initial length only in the transverse direction (TD). Alternatively, the first protective layer 30 can be formed by the following steps: uniaxially stretching the melt extruded film to 2 to 10 times its initial length, heat treating the stretched film in a predetermined temperature range, and stretching the heat-treated film in TD under relaxation conditions. The heat treatment is performed at the glass transition temperature Tg of the resin (specifically, about 100°C to about 300°C) for about 1 second to about 2 hours. The TD elongation can be about 0 times to about 3 times, specifically about 0.1 times to about 2 times, and more specifically about 0.1 times to about 1 times. Within these temperature and elongation ranges, the protective film can maintain a delay, and the crystallization and stabilization of the first protective layer can be achieved.

[0066] The first protective layer 30 is a film uniaxially stretched in TD as described above, and the polarizer 10 is a film uniaxially stretched in MD. In the polarizing plate 100, the TD of the first protective layer 30 may be substantially orthogonal to the MD of the polarizer 10. As a result, it is possible to prevent the polarizing plate 100 from being bent. As used herein, "substantially orthogonal to" may include not only a structure in which the TD of the first protective film 30 and the MD of the polarizer 10 intersect each other, but also a structure in which the TD of the protective film 30 and the MD of the polarizer 10 intersect each other at a certain angle (within an acceptable error limit) from 90°.

[0067] although Figure 1 Although not shown in the figure, the first protective layer 30 may further include a functional layer on one surface thereof. The functional coating may provide at least one of anti-reflection, low reflection, hard coating, anti-glare, anti-fingerprint, anti-pollution, diffusion and refraction functions to the first protective layer 30. In one embodiment, the functional layer may be formed on the first protective layer 30 as an independent layer. For example, the functional layer may be formed on the first protective layer 30 by coating a composition for a functional layer on the first protective layer 30 or via a bonding layer or an adhesive layer. In another embodiment, the functional layer may be realized by one surface of the first protective layer 30.

[0068] Next, the bonding layer 40 will be described.

[0069] The bonding layer 40 may be formed between the polarizer 10 and the pattern layer 20 to bond the polarizer 10 to the pattern layer 20. The bonding layer 40 may be formed by a typical composition for a bonding layer. In one embodiment, the composition for the bonding layer may include an epoxy resin, a (meth) acrylic monomer, a free radical photoinitiator, and a cationic photoinitiator. In another embodiment, the composition for the bonding layer may include a water-based polyvinyl alcohol binder. The composition for the bonding layer may further include the aforementioned light diffuser to further improve the light diffusion effect. The thickness of the bonding layer 40 may be about 1 μm to about 20 μm, specifically about 1 μm to about 10 μm, and more specifically about 1 μm to about 5 μm. Within this thickness range, the bonding layer may exhibit good bonding strength and promote the thickness reduction of the polarizing plate. However, if the pattern layer 20 exhibits adhesive properties, the bonding layer 40 may be excluded.

[0070] Next, we will refer to Figure 3 A polarizing plate according to another embodiment is described. Figure 3 is a cross-sectional view of a polarizing plate according to another embodiment.

[0071] See also Figure 3, a polarizing plate 200 according to another embodiment is substantially the same as the polarizing plate 100 according to the above embodiment, except that the polarizing plate 200 includes a pattern layer 21 instead of the pattern layer 20 to reduce the ratio of the width of the engraved pattern to the width of the pattern layer 20, thereby suppressing the moiré phenomenon, and the height of the engraved pattern can be reduced, thereby achieving a reduction in the thickness of the pattern layer. The pattern layer 21 may be formed on the polarizer 10, and may diffuse polarized light received from the polarizer 10. As a result, the pattern layer 21 may improve the contrast ratio and the viewing angle and visibility at the side, as well as the brightness uniformity.

[0072] See also Figure 3 The pattern layer 21 may include a high refractive index layer 209 (which includes at least one engraved prism pattern 211) and a low refractive index layer 208 (which includes at least one filling pattern 210 filling at least a portion of the engraved prism pattern 211). Figure 3 A polarizing plate including an engraved prism pattern 211 having a triangular cross section is shown. Alternatively, the polarizing plate has an engraved prism pattern having an n-shaped cross section (n is an integer from 4 to 10). In addition, Figure 3 The polarizing plate according to this embodiment shown in FIG. 2 does not include a flat portion between the engraved prism patterns 211. According to this embodiment, the polarizing plate may further include a flat portion between the engraved prism patterns 211. Figure 1 In addition, the roughness can be further formed on Figure 3 , to further improve the light diffusion effect. The maximum pitch (P3) of the engraved prism pattern 211 may be about 20 μm or less, specifically about 7 μm to about 15 μm. The maximum height (H3) of the engraved prism pattern 211 may be about 3 μm to about 16 μm, specifically about 4 μm to about 16 μm. The vertex angle (θ) of the engraved prism pattern 211 may be about 55° to about 90°, specifically about 65° to about 80°. Although the engraved prism pattern 211 is not limited to a specific aspect ratio, the aspect ratio of the engraved prism pattern 211 may be, for example, about 1 or less, specifically about 0.50 to about 0.96, more specifically about 0.6 to about 0.8. Within the range of these pitches, heights, vertex angles, and aspect ratios, the engraved prism pattern 211 can ensure good effects of light collection and diffusion.

[0073] Next, we will refer to Figure 4 A polarizing plate according to another embodiment is described. Figure 4 is a cross-sectional view of a polarizing plate according to another embodiment.

[0074] See also Figure 4, a polarizing plate 300 according to another embodiment is substantially the same as the polarizing plate 100 according to the above embodiment, except that the polarizing plate 200 includes a pattern layer 22 instead of the pattern layer 20. The pattern layer 22 may include a low refractive index layer 212 and a high refractive index layer 213. The high refractive index layer 213 may include at least one engraved pattern 214 and at least one flat portion 215, and may have a curved surface 216 formed at an interface between the engraved pattern 214 and the flat portion 215 to provide a further improved effect of light collection and diffusion. The low refractive index layer 212 may include at least one filling pattern 217 that fills at least a portion of the engraved pattern 214.

[0075] Next, we will refer to Figure 5 A polarizing plate according to still another embodiment is described. Figure 5 is a cross-sectional view of a polarizing plate according to yet another embodiment.

[0076] See also Figure 5 The polarizing plate 400 according to another embodiment is substantially the same as the polarizing plate 100 according to the above embodiment, except that the polarizing plate 400 includes a second protective layer 50 instead of the first protective layer 30, and the high refractive index layer 202 is formed between the bonding layer 40 and the low refractive index layer 201. Figure 5 Although not shown in the figure, the polarizing plate 400 according to this embodiment may further include a bonding layer 40 and a first protective layer 30 sequentially formed on the polarizer 10, that is, the first protective layer 30, the bonding layer 40, the polarizer 10, the bonding layer 40, the high refractive index layer 202, the low refractive index layer 201, and the second protective layer 50 are sequentially formed. According to this embodiment, the polarizing plate 400 may include a pattern layer 21 instead of the pattern layer 20. The following description will be given only about the second protective layer 50.

[0077] The second protection layer 50 may be formed under the low refractive index layer 201 to support the pattern layer 20 .

[0078] The second protective layer 50 may be formed of an optically transparent resin. Specifically, the resin may include TAC, PET, COP, and acrylic resin. More specifically, the resin may include TAC, COP, and acrylic resin. The second protective layer 50 may include a film formed by modifying the aforementioned resin. The modification may include copolymerization, branching, crosslinking, or modification of end molecules.

[0079] The second protective layer 50 may have a predetermined delay range to provide a viewing angle compensation function. In one embodiment, the in-plane delay (Re) of the second protective layer 50 may be about 40nm to about 60nm. In another embodiment, the second protective layer 50 may have the same delay as the first protective layer described above. Within this range, the second protective layer can compensate for the viewing angle to provide good image quality. The thickness of the second protective layer 50 may be about 150μm or less, specifically about 20μm to about 150μm, more specifically about 30μm to about 100μm. Within this range, the second protective layer can be used in a polarizing plate. The ratio of the thickness of the pattern layer 20 to the thickness of the second protective layer 50 (the thickness of the pattern layer / the thickness of the second protective layer) may be about 2 or less than 2, specifically about 0.02 to about 0.75, more specifically about 0.1 to about 0.4. Within this range, the second protective layer can prevent degradation of reliability due to penetration of external moisture into the polarizing plate while suppressing warping and wrinkling of the polarizing plate.

[0080] Next, we will refer to Figure 6 A polarizing plate according to still another embodiment is described. Figure 6 is a cross-sectional view of a polarizing plate according to yet another embodiment.

[0081] See also Figure 6 The polarizing plate 500 according to another embodiment is substantially the same as the polarizing plate 100 according to the above embodiment, except that a bonding layer 40 and a second protective layer 50 are further sequentially formed below the polarizer 10. The bonding layer 40 and the second protective layer 50 can further suppress the bending of the polarizing plate. Figure 6 A polarizing plate having a structure in which the bonding layer 40 formed between the polarizer 10 and the pattern layer 20 is the same as the bonding layer 40 formed between the polarizer 10 and the second protective layer 50 is shown, but it should be understood that the bonding layer 40 formed between the polarizer 10 and the pattern layer 20 may be different from the bonding layer formed between the polarizer 10 and the second protective layer 50 in thickness, composition, and the like. Figure 6 The polarizing plate according to the embodiment shown in FIG. 1 includes the pattern layer 20, but the polarizing plate according to the embodiment may include the pattern layer 21 instead of the pattern layer 20. Figure 6 Although not shown in the figure, the polarizing plate according to this embodiment may further include an adhesive layer under the second protective layer 50. The adhesive layer may be formed of an adhesive composition, which includes an adhesive resin such as a (meth)acrylic resin, an epoxy resin, a silicone resin, and the like, a curing agent, and a silane coupling agent. The (meth)acrylic resin may include a typical (meth)acrylic copolymer containing an alkyl group, a hydroxyl group, an aromatic group, a carboxylic acid group, an alicyclic group, an isoalicyclic group, and the like. Specifically, the (meth)acrylic resin may be formed of a monomer mixture, which includes a monomer mixture containing C1 to C10 Unsubstituted alkyl (meth) acrylic monomers, containing C1 to C 10 Alkyl (meth) acrylic acid monomers, containing C6 to C 20 Aromatic (meth) acrylic monomers, carboxylic acid-containing (meth) acrylic monomers, C3 to C 20 The (meth)acrylic monomer of the alicyclic group and the C3 to C4 monomer containing at least one of nitrogen (N), oxygen (O) and sulfur (S) 10 (Meth) acrylic monomers of heteroalicyclic groups. The curing agent may include a multifunctional (meth) acrylate, which includes a difunctional (meth) acrylate, such as hexanediol diacrylate; a trifunctional (meth) acrylate, such as trimethylolpropane tri(meth) acrylate; a tetrafunctional (meth) acrylate, such as pentaerythritol tetra(meth) acrylate; a pentafunctional (meth) acrylate, such as dipentaerythritol penta(meth) acrylate; and a hexafunctional (meth) acrylate, such as dipentaerythritol hexa(meth) acrylate, but is not limited thereto. The silane coupling agent may include a typical silane coupling agent, such as 3-glycidyloxypropyltrimethoxysilane. As used in the preparation of the adhesive layer, the adhesive composition may include 100 parts by weight of a (meth) acrylic resin, about 0.1 parts by weight to about 30 parts by weight of a curing agent, and about 0.1 parts by weight to about 20 parts by weight of a silane coupling agent. In the case of this content of the adhesive composition, the adhesive layer can allow the polarizing plate to be effectively attached to the liquid crystal panel. The thickness of the adhesive layer can be about 10 μm to about 100 μm. Within this thickness range, the adhesive layer can allow the polarizing plate to be effectively attached to the liquid crystal panel and can be used in the polarizing plate.

[0082] Next, we will refer to Figure 7 A polarizing plate according to still another embodiment is described. Figure 7 is a cross-sectional view of a polarizing plate according to yet another embodiment.

[0083] See also Figure 7 The polarizing plate 600 according to still another embodiment is substantially the same as the polarizing plate 100 according to the above embodiment, except that the polarizing plate 600 includes a pattern layer 23 instead of the pattern layer 20 .

[0084] See also Figure 7, the pattern layer 23 may include a high refractive index layer 219 (which includes at least one engraved pattern 220 and a flat portion 206) and a low refractive index layer 218 (which includes a filling pattern 221 that fills at least a portion of the engraved pattern 220). The engraved pattern 220 may be an engraved optical pattern, which includes a flat surface 220a at its uppermost surface. The flat surface 220a is formed at the uppermost surface of the engraved pattern and promotes the diffusion of light emitted from the optical display and reaching the low refractive index layer 218, thereby increasing the viewing angle and brightness. Therefore, the polarizing plate 600 can minimize the brightness loss through the improvement of the light diffusion effect, and can improve visibility by increasing the 1 / 2 viewing angle or the 1 / 3 viewing angle. The flat surface 220a may be parallel to one surface of the polarizer 10, the flat portion 206, or the first protective layer 30. See again Figure 7 , the engraved pattern 220 has a trapezoidal cross-sectional shape, in which a flat surface 220a is formed at its uppermost surface, and the inclined surface 220b is flat (for example: a truncated prism pattern with a truncated triangular cross-section, i.e., a truncated prism shape). Alternatively, the engraved pattern 220 may have a shape in which one or more flat surfaces are formed on its uppermost surface and the inclined surface is a curved surface (for example: a truncated double convex lens pattern or a truncated microlens pattern), or a shape including one or more flat surfaces at its uppermost surface and having an n-angle cross-section (n is an integer of 5 or greater than 5, specifically 5 to 20).

[0085] Then, refer to Figure 8 A liquid crystal display according to an embodiment of the present invention is described. Figure 8 is a perspective view of a liquid crystal display according to an embodiment of the present invention.

[0086] See also Figure 8 According to one embodiment, a liquid crystal display 1100 may include a light source 910, a light guide plate 920, a reflective sheet 930, a diffuser sheet 940, a first polarizing plate 950, a liquid crystal panel 960, and a second polarizing plate 970, wherein the second polarizing plate 970 may include a polarizing plate according to an embodiment of the present invention.

[0087] The light source 910 may generate light and may be disposed to face the light guide plate 920. The light source 910 may be a linear light lamp, a surface light lamp, or various other light sources such as a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED). A light source cover 911 may be further disposed outside the light source 910. Figure 8In the embodiment, the light source 910 is disposed on only one side of the light guide plate 920, but the light source 910 may also be further disposed on the other side of the light guide plate 920 (at the side of the light guide plate 920 opposite to the one side of the light guide plate 920), and may be a direct type light source.

[0088] The light guide plate 920 may be disposed at a side of the light source 910 , and may internally reflect light received from the light source 910 toward the diffusion sheet 940 .

[0089] The diffusion sheet 940 may diffuse the light received from the light guide plate 920 to supply the light to the first polarizing plate 950. The diffusion sheet 940 may include a prism sheet having an optical pattern formed on a light incident plane thereof, a prism sheet having an optical pattern formed on a light exit plane thereof, and the like. The diffusion sheet 940 may include a composite optical sheet having two or more prism sheets stacked thereon.

[0090] The liquid crystal panel 960 may be disposed between the first polarizing plate 950 and the second polarizing plate 970 , and may be configured to allow light received from the first polarizing plate 950 to be transmitted to the second polarizing plate 970 through the liquid crystal panel.

[0091] The liquid crystal panel 960 may include a first substrate, a second substrate, and a liquid crystal layer fixed between the first substrate and the second substrate and serving as a display medium. The first substrate may include a color filter and a black matrix mounted thereon. The second substrate may include: a switching device configured to control the electro-optical properties of the liquid crystal; an injection line configured to supply a gate signal to the switching device and the signal line in order to provide a source signal; a pixel electrode; and a counter electrode. The liquid crystal layer may include liquid crystals that are uniformly aligned when no electric field is applied. Specifically, the liquid crystal panel may adopt a vertical alignment (VA) mode, a patterned vertical alignment (PVA) mode, or a super-patterned vertical alignment (S-PVA) mode, but is not limited thereto.

[0092] The first polarizing plate 950 may be disposed on one surface of the liquid crystal panel 960 to face the light emission plane of the diffusion sheet 940, and may be configured to polarize the light received from the diffusion sheet 940 and diffuse the light toward the liquid crystal panel 960. The first polarizing plate 950 may include a polarizer and a protective film formed on at least one surface of the polarizer. The polarizer and the protective film are well known to those skilled in the art.

[0093] The reflective sheet 930 may be formed on a lower surface of the light guide plate 920 and may reflect light emitted from the light source 910 to the light guide plate 920 , thereby improving light emitting efficiency.

[0094] Although the second polarizing plate 970 may be Figure 8 9 is described as including the polarizing plate according to the embodiment of the present invention, but the first polarizing plate 950 may include the polarizing plate according to the embodiment instead of the second polarizing plate 970 .

[0095] Next, a method of manufacturing a polarizing plate according to an embodiment of the present invention will be described.

[0096] The polarizing plate according to this embodiment may be manufactured by assembling a stacked structure of a first protective layer and a pattern layer on a polarizer.

[0097] First, a stacked structure of a first protective layer and a pattern layer is manufactured. Specifically, a composition for a high refractive index layer is applied to one surface of the first protective layer. The composition can be applied to a thickness of about 40 μm or less than 40 μm, specifically about 3 μm to about 40 μm, and more specifically about 5 μm to about 30 μm. Coating is not limited to a specific method. For example, coating can be performed by rod coating, die coating, slide coating and the like. The high refractive index layer is formed by transferring the pattern to the coating using a pattern film having an embossed filling pattern and a flat portion formed thereon. Thereafter, a composition for a low refractive index layer is applied to the pattern so as to fill the pattern, and cured to form a low refractive index layer. Curing can be performed by at least one of photocuring or thermal curing. Light at a wavelength of 400 nm or less (energy density of about 10 mJ / cm 2 To about 1000mJ / cm 2 ) to perform photocuring. Thermal curing may be performed at about 40° C. to about 200° C. for about 1 hour to about 30 hours. Under these conditions, the resin or composition for the pattern layer may be fully cured, thereby increasing the hardness of the pattern layer. In this method, the pattern layer is a coating formed on the first protective layer and may directly contact the first protective layer. Thereafter, a composition for a bonding layer is applied to one surface of the pattern layer, bonded to a polarizer, and cured to manufacture a polarizing plate. Curing may be performed by at least one of photocuring or thermal curing.

[0098] Hereinafter, the present invention will be described in more detail with reference to some examples. However, it should be understood that these examples are provided for illustration only and should not be understood as limiting the present invention in any way.

[0099] Example 1: Manufacturing of polarizing plate

[0100] The polarizer was manufactured by stretching a polyvinyl alcohol film to 3 times its original length at 60°C and adsorbing iodine onto the stretched film, followed by stretching the resulting film to 2.5 times the stretched length of the film in a boric acid aqueous solvent at 40°C.

[0101] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent PET film (COSMOSHINE SRF, thickness: 80 μm, Re=14,000 nm at a wavelength of 550 nm, Toyobo Co., Ltd.) for a first protective layer. Using a film having an embossed lenticular lens pattern (pitch: 10 μm, height: 10 μm) and a flat portion (pitch: 10 μm) alternately formed thereon, an engraved lenticular lens pattern and a flat portion were formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the PET film. Next, a UV curing resin (SSC140, Shin-A T&C) was applied onto the high refractive index layer so that the engraved lenticular lens pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0102] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) was applied to one surface of the low refractive index layer, and the low refractive index layer was bonded to the manufactured polarizer, followed by curing, thereby manufacturing a polarizing plate.

[0103] Example 2: Manufacturing of polarizing plate

[0104] A polarizer was manufactured in the same manner as in Example 1.

[0105] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent PET film (COSMOSHINE SRF, thickness: 80 μm, Re=14,000 nm at a wavelength of 550 nm, Toyobo Co., Ltd.) for a first protective layer. Using a film having an embossed prism pattern (pitch: 13 μm, height: 10 μm, vertex angle: 65.5°, triangular cross section) formed thereon, an engraved prism pattern was formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the PET film. Next, a UV curing resin (SSC140, Shin-A T&C) was applied onto the high refractive index layer so that the engraved prism pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0106] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) was applied to one surface of the low refractive index layer, and the low refractive index layer was bonded to the manufactured polarizer, followed by curing, thereby manufacturing a polarizing plate.

[0107] Example 3: Manufacturing of polarizing plate

[0108] A polarizer was manufactured in the same manner as in Example 1.

[0109] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent PET film (COSMOSHINE SRF, thickness: 80 μm, Re=14,000 nm at a wavelength of 550 nm, Toyobo Co., Ltd.) for a first protective layer. Using a film having an embossed lenticular lens pattern (pitch: 10 μm, height: 10 μm) and a flat portion (pitch: 10 μm) alternately formed thereon, an engraved lenticular lens pattern and a flat portion were formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the PET film. Next, a UV curing resin (SSC143, Shin-A T&C) was applied onto the high refractive index layer so that the engraved lenticular lens pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0110] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) is coated onto one surface of each of the low refractive index layer and the TAC film for the second protective film (KC4DR-1, thickness: 40 μm, Konica Minolta Co., Ltd.), which is in turn bonded to the manufactured polarizer so that the low refractive index layer, the polarizer and the TAC film are stacked sequentially in this order, followed by curing to manufacture a polarizing plate.

[0111] Example 4: Manufacturing of polarizing plate

[0112] A polarizer was manufactured in the same manner as in Example 1.

[0113] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent PET film (COSMOSHINE SRF, thickness: 80 μm, Re=14,000 nm at a wavelength of 550 nm, Toyobo Co., Ltd.) for a first protective layer. Using a film having an embossed prism pattern (pitch: 13 μm, height: 10 μm, vertex angle: 65.5°, triangular cross section) formed thereon, an engraved prism pattern was formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the PET film. Next, a UV curing resin (SSC143, Shin-A T&C) was applied onto the high refractive index layer so that the engraved prism pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0114] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) is coated onto one surface of each of the low refractive index layer and the TAC film for the second protective film (KC4DR-1, thickness: 40 μm, Konica Minolta Co., Ltd.), which is in turn bonded to the manufactured polarizer so that the low refractive index layer, the polarizer and the TAC film are stacked sequentially in this order, followed by curing to manufacture a polarizing plate.

[0115] Example 5: Manufacturing of polarizing plate

[0116] A polarizer was manufactured in the same manner as in Example 1.

[0117] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent PET film (COSMOSHINE SRF, thickness: 80 μm, Re=14,000 nm at a wavelength of 550 nm, Toyobo Co., Ltd.) for a first protective layer. Using a film having an embossed lenticular lens pattern (pitch: 10 μm, height: 10 μm) and a flat portion (pitch: 10 μm) alternately formed thereon, an engraved lenticular lens pattern and a flat portion were formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the PET film. Next, a UV curing resin (SSC143, Shin-A T&C) was applied onto the high refractive index layer so that the engraved lenticular lens pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0118] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) is coated onto one surface of each of the low refractive index layer and the COP film for the second protective film (ZB12, thickness: 50 μm, Zeon Co., Ltd.), which is in turn bonded to the manufactured polarizer so that the low refractive index layer, the polarizer and the COP film are stacked sequentially in this order, followed by curing to manufacture the polarizing plate.

[0119] Example 6: Manufacturing of polarizing plate

[0120] A polarizer was manufactured in the same manner as in Example 1.

[0121] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent TAC film (KC4DR-1, thickness: 40 μm, Konica Corporation) for a first protective layer. Using a film having an embossed lenticular lens pattern (pitch: 10 μm, height: 10 μm) and a flat portion (pitch: 10 μm) alternately formed thereon, an engraved lenticular lens pattern and a flat portion were formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the TAC film. Next, a UV curing resin (SSC143, Shin-A T&C) was applied onto the high refractive index layer so that the engraved lenticular lens pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0122] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) is coated onto one surface of each of the low refractive index layer and the TAC film for the second protective film (KC4DR-1, thickness: 40 μm, Konica Minolta Co., Ltd.), which is in turn bonded to the manufactured polarizer so that the low refractive index layer, the polarizer and the TAC film are stacked sequentially in this order, followed by curing to manufacture a polarizing plate.

[0123] Example 7: Manufacturing of polarizing plate

[0124] A polarizer was manufactured in the same manner as in Example 1.

[0125] A coating layer was formed by applying a UV curing resin (SSC155, Shin-A T&C) onto one surface of a transparent COP film (ZB12, thickness: 50 μm, Ruiong Co., Ltd.) for a first protective layer. Using a film having an embossed lenticular lens pattern (pitch: 10 μm, height: 10 μm) and a flat portion (pitch: 10 μm) alternately formed thereon, an engraved lenticular lens pattern and a flat portion were formed on the coating layer, followed by curing, thereby forming a high refractive index layer on the COP film. Next, a UV curing resin (SSC143, Shin-A T&C) was applied onto the high refractive index layer so that the engraved lenticular lens pattern could be completely filled with the UV curing resin, followed by curing, thereby forming a pattern layer having a low refractive index layer formed directly on the high refractive index layer.

[0126] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) is coated onto one surface of each of the low refractive index layer and the TAC film for the second protective film (KC4DR-1, thickness: 40 μm, Konica Minolta Co., Ltd.), which is in turn bonded to the manufactured polarizer so that the low refractive index layer, the polarizer and the TAC film are stacked sequentially in this order, followed by curing to manufacture a polarizing plate.

[0127] Comparative Example 1: Production of polarizing plate

[0128] A polarizer was manufactured in the same manner as in Example 1.

[0129] A binder for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.) is coated on both surfaces of the polarizer, which is in turn bonded to a transparent PET film for a first protective layer (COSMOSHINE SRF, thickness: 80 μm, Re=14,000 nm at a wavelength of 550 nm, Toyobo Co., Ltd.) and a TAC film for a second protective film (KC4DR-1, thickness: 40 μm, Konica Minolta Co., Ltd.), so that the transparent PET film, the polarizer and the TAC film are stacked sequentially in this order, followed by curing to manufacture a polarizing plate.

[0130] The components of the polarizing plates manufactured in the examples and comparative examples are shown in Table 1. In addition, the polarizing plates were evaluated according to the following properties. To this end, each liquid crystal display module was manufactured by the following method.

[0131] Preparation Example 1: Production of polarizing plate

[0132] The polarizer was manufactured by stretching a polyvinyl alcohol film to 3 times its original length at 60° C., adsorbing iodine onto the stretched film, and then stretching the resulting film to 2.5 times the stretched length of the film in a boric acid aqueous solvent at 40° C. A triacetyl cellulose film (thickness: 80 μm) was bonded to both surfaces of the polarizer via a bonding agent for polarizing plates (Z-200, Nippon Synthetic Chemical Co., Ltd.), thereby providing a polarizing plate.

[0133] Preparation Example 2: Fabrication of Composite Optical Sheets

[0134] A composition was prepared, which included 35 wt % of epoxy acrylate, 15 wt % of urethane acrylate oligomer, 36 wt % of o-phenylphenol ethoxylated acrylate, 10 wt % of trimethylolpropane 9-ethoxylated acrylate and 4 wt % of a photoinitiator.

[0135] The composition was applied to one surface of a polyethylene terephthalate (PET) film (T910E, thickness: 125 μm, Mitsubishi Corporation) for a first base film to form a coating layer. A prism pattern (triangular cross section, height: 12 μm, pitch: 24 μm, vertex angle: 90°, aspect ratio: 0.5) was transferred from a pattern roll having an embossing pattern corresponding to the prism pattern to the coating layer, followed by curing, thereby forming a first optical sheet having a first prism pattern formed thereon.

[0136] The composition was applied to one surface of a polyethylene terephthalate (PET) film (T910E, thickness: 125 μm, Mitsubishi Corporation) for a second base film to form a coating layer. A prism pattern (triangular cross section, height: 12 μm, pitch: 24 μm, vertex angle: 90°, aspect ratio: 0.5) was transferred from a pattern roll having an embossing pattern corresponding to the prism pattern to the coating layer, followed by curing, thereby forming a second optical sheet having a second prism pattern formed thereon.

[0137] The composite optical sheet is manufactured in such a manner that a second optical sheet is stacked on the first optical sheet such that a longitudinal direction of the first prism pattern is orthogonal to a longitudinal direction of the second prism pattern.

[0138] Preparation Example 3: Fabrication of Liquid Crystal Display Module

[0139] Each of the polarizing plate of the example or comparative example, the liquid crystal panel (PVA mode), and the polarizing plate of Preparation Example 1 are sequentially stacked on top of each other via a bonding layer, and the composite optical sheet manufactured in Preparation Example 2 is attached to the lower side of the first polarizing plate of Preparation Example 1, thereby manufacturing a liquid crystal display module.

[0140] (1) Brightness: An LED light source, a light guide plate, and a liquid crystal display module were assembled to manufacture a liquid crystal display, one side of which contained a side-light type LED light source (the configuration was the same as that of a Samsung LED TV (UN32H5500)), except for the configuration of the liquid crystal display modules manufactured in the example and the comparative example. The front brightness was measured using an EZ contrast analyzer X88RC (EZXL-176R-F422A4, Eldim Co., Ltd.). The relative brightness was calculated by {(brightness of the example and comparative example) / (brightness of comparative example 1)} x 100.

[0141] (2) 1 / 2 viewing angle and 1 / 3 viewing angle: A liquid crystal display was manufactured in the same manner as in the evaluation item (1), and the luminance was measured using an EZ contrast analyzer X88RC (EZXL-176R-F422A4, Eldim Co., Ltd.). The 1 / 2 viewing angle and the 1 / 3 viewing angle mean viewing angles at which the luminance value becomes 1 / 2 and 1 / 3 of the front luminance, respectively.

[0142] (3) Contrast ratio: A liquid crystal display was manufactured in the same manner as in Evaluation Item 1, and the spherical coordinate system (Φ, θ) and contrast ratio were measured using an EZ Contrast Analyzer X88RC (EZXL-176R-F422A4, Eldim Co., Ltd.).

[0143] (4) Brightness uniformity and rate of change of brightness uniformity: A 50" or 55" liquid crystal display as listed in Table 1 was manufactured by assembling an LED light source, a light guide plate, a liquid crystal display module, and a screen unit having a major axis and a minor axis. Fig. 9 , in a liquid crystal display including a light source, a light guide plate and a liquid crystal display module, the brightness is measured at each of points A, B and C, where the center point, the left end point and the right end point of the display screen 1 are indicated by B, A and C respectively, and the maximum brightness value (maximum brightness) and the minimum brightness value (minimum brightness) are obtained. The brightness uniformity can be calculated by (minimum brightness) / (maximum brightness) x 100. When measuring the brightness, the brightness tester EZ Contrast Analyzer X88RC (EZXL-176R-F422A4, Eldim Co., Ltd.) is fixed to point B and then guided to face each of points A, B and C. Next, the brightness uniformity of the 50" LCD (a) and the brightness uniformity of the 55" LCD (b) are obtained. The rate of change of brightness uniformity can be calculated by |ba| / ax 100.

[0144]

[0145]

[0146]

[0147] As shown in Table 1, the liquid crystal display module manufactured in the example has high front brightness, can increase the side viewing angle by increasing the 1 / 2 viewing angle and the 1 / 3 viewing angle, and has a high side contrast ratio. In addition, the liquid crystal display module manufactured in the example can increase the brightness uniformity, and by minimizing the change in brightness uniformity depending on the screen size of the liquid crystal display, it is not necessary to change it due to the size change of the liquid crystal display, thereby improving processability and economic feasibility. Therefore, the present invention provides a polarizing plate capable of improving the side contrast ratio, the side viewing angle and the brightness uniformity while minimizing the change in brightness uniformity.

[0148] On the contrary, despite the high relative brightness, the liquid crystal display module of Comparative Example 1 (which does not use the polarizing plate of the example) does not show significant improvement in viewing angle and contrast ratio. In addition, the liquid crystal display module of Comparative Example 1 (which does not use the polarizing plate of the example) shows low brightness uniformity and significant variation in brightness uniformity depending on the screen size of the liquid crystal display, and thus has low processability and economic feasibility compared to the liquid crystal display module manufactured in the example.

[0149] It should 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.

Claims

1. A polarizing plate, characterized in that: include: polarizer; a pattern layer formed on one surface of the polarizer, wherein the pattern layer comprises a high refractive index layer and a low refractive index layer, wherein the high refractive index layer has at least one engraved pattern and the low refractive index layer has a filling pattern filling at least a portion of the engraved pattern; as well as The first protective layer, The polarizing plate has a stacked structure in which the polarizer, the low refractive index layer, the high refractive index layer and the first protective layer are sequentially stacked in this order, or a stacked structure in which the polarizer, the first protective layer, the low refractive index layer and the high refractive index layer are sequentially stacked in this order, wherein the first protective layer comprises a base film formed of at least one resin selected from triacetyl cellulose, polyethylene terephthalate, cycloolefin polymer and acrylic resin, and wherein the high refractive index layer has a higher refractive index than the low refractive index layer, The ratio of the thickness of the pattern layer to the thickness of the first protective layer is 0.02 to 0.75, wherein the engraved pattern comprises an optical pattern having a curved surface or a prism pattern having a triangular to decagonal cross section, or The engraved pattern includes an optical pattern having a truncated triangular cross-sectional prism shape, a truncated biconvex lens shape, or a shape including one or more flat surfaces at the uppermost surface of the optical pattern and having an n-gonal cross-section, wherein n is an integer of 5 or greater.

2. The polarizing plate according to claim 1, characterized in that The high refractive index layer further includes a flat portion between adjacent engraved patterns.

3. The polarizing plate according to claim 2, characterized in that: A ratio of a maximum pitch of the engraved pattern to a pitch of the flat portion is 1 or less.

4. The polarizing plate according to claim 1, characterized in that A refractive index difference between the high refractive index layer and the low refractive index layer is 0.30 or less.

5. The polarizing plate according to claim 1, characterized in that: The first protective layer has an in-plane retardation of 8,000 nm or more at a wavelength of 550 nm, and is formed of the polyethylene terephthalate resin.

6. The polarizing plate according to claim 1, characterized in that The first protective layer includes the base film and a primer layer formed on at least one surface of the base film, and a ratio of a refractive index of the primer layer to a refractive index of the base film is 1.0 or less.

7. The polarizing plate according to claim 6, characterized in that: The first protective layer has a light transmittance of 90% or more at a wavelength of 550 nm.

8. The polarizing plate according to claim 1, wherein: The first protective layer is formed by uniaxially stretching a base film formed of the polyethylene terephthalate resin.

9. The polarizing plate according to claim 1, wherein: The low refractive index layer, the high refractive index layer, and the first protective layer are sequentially stacked on the polarizer.

10. The polarizing plate according to claim 9, characterized in that: The high refractive index layer is directly formed on the first protective layer.

11. The polarizing plate according to claim 9, characterized in that: Further included is a bonding layer formed between the polarizer and the low refractive index layer.

12. The polarizing plate according to claim 1, characterized in that Further including: A second protective layer is formed on the other surface of the polarizer.

13. The polarizing plate according to claim 12, characterized in that: The second protective layer includes a film formed of at least one of triacetyl cellulose, polyethylene terephthalate, cycloolefin polymer, and acrylic resin.

14. A liquid crystal display, characterized in that: The invention comprises the polarizing plate as claimed in claim 1.

Images