KR102237004B1 - Optical film for improving contrast ratio, polarizing plate comprising the same and liquid crystal display apparatus comprising the same - Google Patents

Abstract

A protective layer and a pattern layer formed on the protective layer, wherein the pattern layer includes a pattern portion having a relief optical pattern on one surface and a flat portion between the relief optical pattern and the relief optical pattern immediately adjacent thereto, , The optical pattern has a base angle (θ) of 55° to 90°, the pattern part satisfies Equation 1, and further includes a gap fill layer directly facing the pattern layer, and the gap fill layer includes a matrix and the Contrast ratio improving optical film comprising first particles included in a matrix, the absolute value of the difference in refractive index between the matrix and the first particle is 0 to 0.03, and the difference in refractive index between the pattern layer and the gap fill layer is 0.06 or more, A polarizing plate including the same and a liquid crystal display including the same are provided.

Description

Optical film for improving contrast ratio, polarizing plate including the same, and liquid crystal display device including the same {OPTICAL FILM FOR IMPROVING CONTRAST RATIO, POLARIZING PLATE COMPRISING THE SAME AND LIQUID CRYSTAL DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to an optical film for improving contrast ratio, a polarizing plate including the same, and a liquid crystal display device including the same.

The liquid crystal display is operated by emitting light from a backlight unit through two polarizing plates. Accordingly, the color sense from the front of the screen of the liquid crystal display device is good, but the color sense, contrast ratio, and viewing angle of the side of the screen of the liquid crystal display device may be lower than the front.

In order to increase the color sense, contrast ratio, and viewing angle from the side, attempts have been made to improve the liquid crystal panel or the liquid crystal structure. However, there is a limit to improvement through deformation of the liquid crystal panel, and the process is complicated. As the LCD device becomes larger, the disadvantage of the VA system has a narrow viewing angle. In order to solve this problem, if a pattern structure having internal diffusion is inserted, the viewing angle is widened and visibility is improved.

The viewing angle can be improved by including an optical film for improving contrast ratio in the viewing side polarizing plate. In addition, by laminating an optical film for improving contrast ratio on a polarizing plate and an anti-glare film having surface irregularities on the optical film for improving contrast ratio, it is possible to obtain an anti-glare effect for external light. Conventional anti-glare films consist of a matrix forming a film and anti-glare particles, such as beads, dispersed in the matrix, and control internal and external haze by using the refractive index between the matrix and the anti-glare particles, and diffusion of internal or external light and Scattering can be implemented.

However, when the anti-glare film is laminated on the optical film for improving the contrast ratio, the effect of improving visibility due to the optical film for improving the contrast ratio may be reduced by additional internal diffusion while passing through the anti-glare film. In addition, the polarizing plate can be thickened by including a total of two base layers as a protective layer (substrate layer) for an anti-glare film and a protective layer (substrate layer) for an optical film with improved contrast ratio.

Background art of the present invention is disclosed in Japanese Laid-Open Patent No. 2006-251659.

An object of the present invention is to provide an optical film with improved contrast ratio capable of obtaining an effect of scattering external light by particles while maintaining an effect of improving front and side visibility due to a pattern layer and a gap fill layer.

Another object of the present invention is to provide an optical film with improved contrast ratio in which moire does not occur even if a pattern layer and anti-glare particles are included.

Another object of the present invention is to provide an optical film with improved contrast ratio that can be thinned.

The optical film for improving contrast ratio of the present invention includes a protective layer and a pattern layer formed on the protective layer, and the pattern layer is between the embossed optical pattern on one side and the embossed optical pattern immediately adjacent to the embossed optical pattern. A pattern portion having a flat portion is provided, and the optical pattern has a base angle (θ) of 55° to 90°, and the pattern portion satisfies Equation 1 below,

<Equation 1>

1 <P/W ≤ 10

(In Equation 1, P is the period of the pattern part (unit: μm),

W is the maximum width of the optical pattern (unit: μm)),

Further comprising a gap fill layer in direct contact with one surface of the pattern layer,

The gap fill layer includes a matrix and a first particle included in the matrix, the absolute value of the difference in refractive index between the matrix and the refractive index of the first particle is 0 to 0.03, and the refractive index of the pattern layer and the gap fill layer The difference can be more than 0.06.

The polarizing plate of the present invention may include a polarizing film and an optical film for improving contrast ratio of the present invention formed on the polarizing film.

The liquid crystal display device of the present invention may include the polarizing plate of the present invention.

The present invention provides an optical film with improved contrast ratio capable of obtaining an effect of scattering external light by particles while maintaining the effect of improving front and side visibility due to the pattern layer and the gap fill layer.

The present invention provides an optical film with improved contrast ratio in which moire does not occur even if the pattern layer and anti-glare particles are included.

The present invention provides an optical film with improved contrast ratio that can be thinned.

1 is a cross-sectional view of an optical film for improving contrast ratio according to an embodiment of the present invention.
2 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

With reference to the accompanying drawings, embodiments will be described in detail so that those of ordinary skill in the art may easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and the same reference numerals are assigned to the same or similar components throughout the specification.

In the present specification, "upper part" and "lower part" are defined based on the drawings, and "upper part" may be changed to "lower part" and "lower part" may be changed to "upper part" according to the viewpoint of the view, and "on" or What is referred to as “on” may include a case where other structures are interposed not only above but also in the middle. On the other hand, to be referred to as "directly on", "directly on", or "directly formed" or "directly formed in contact" means that no other structure is interposed therebetween.

In the present specification, “horizontal direction” and “vertical direction” refer to the longitudinal direction and the unidirectional direction of a rectangular LCD screen, respectively. In the present specification, "front" and "side" refer to the horizontal direction, when (φ, θ) by the spherical coordinate system, the front is (0°, 0°), and the left end point When is (180°, 90°) and the right end point is (0°, 90°), the side means (0°, 60°).

In the present specification, the "top part" means the highest part of the embossed optical pattern.

In the present specification, "aspect ratio" means a ratio of the maximum height to the maximum width of the optical pattern (maximum height/maximum width).

In the present specification, "period" means a distance between adjacent optical patterns, for example, the sum of the maximum width of one optical pattern and the width of one flat portion immediately adjacent to the optical pattern.

In the present specification, the "plane direction retardation (Re)" is a value at a wavelength of 550 nm, and is represented by the following formula A:

<Equation A>

Re = (nx-ny) x d

(In Equation A, nx and ny are the refractive indexes in the slow axis direction and the fast axis direction of the protective layer or substrate layer, respectively, at a wavelength of 550 nm, and d is the thickness (unit: nm) of the protective layer or substrate layer).

In the present specification, "(meth)acrylic" means acrylic and/or methacrylic.

Hereinafter, an optical film for improving contrast ratio according to an embodiment of the present invention will be described with reference to FIG. 1. 1 is a cross-sectional view of an optical film for improving contrast ratio according to an embodiment of the present invention.

Referring to FIG. 1, the optical film 10 for improving contrast ratio includes a protective layer 100 and a pattern layer 210 formed on the protective layer 100, and a gap directly facing one surface of the pattern layer 210 A gap fill layer 220 may be included.

Protective layer

The protective layer 100 may be formed on one surface of the pattern layer 210, that is, the light incident surface, and may support the pattern layer 210. In one embodiment, the protective layer is formed directly on the pattern layer, it is possible to thin the optical film to improve the contrast ratio. The "directly formed" means that no adhesive layer, adhesive layer, or adhesive adhesive layer is interposed between the protective layer and the pattern layer. However, the present invention is not limited thereto.

The protective layer 100 may be optically transparent, and may include a light incident surface and a light exit surface opposite to the light incident surface. The pattern layer 210 is formed on the light exit surface of the protective layer 100. The protective layer 100 may have a total light transmittance of 90% or more in the visible light region, for example, 90% to 100%. In the above range, the incident light can be transmitted through the pattern layer without affecting it.

The protective layer 100 may be a protective film type or a protective coating layer type.

When the protective layer is a protective film type, it may include an optically transparent resin film. The protective film may be formed by melting and extruding a resin. If necessary, an additional stretching process may be added. The resin includes a cellulose ester resin including triacetylcellulose (TAC), a cyclic polyolefin resin including amorphous cyclic polyolefin (COP), a polycarbonate resin, polyethylene terephthalate (PET), etc. Polyacrylate resins including polyester resins, polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, acyclic-polyolefin resins, polymethylmethacrylate resins, etc. It may include at least one of a vinyl alcohol-based resin, a polyvinyl chloride-based resin, and a polyvinylidene chloride-based resin.

The protective film may be a non-stretched film, but may be a retardation film or an isotropic optical film having a retardation in a predetermined range by stretching the resin by a predetermined method. In one embodiment, the protective film may be an isotropic optical film having Re of 60 nm or less, specifically 0 nm to 60 nm, and more specifically 40 nm to 60 nm. By compensating the viewing angle in the above range, the image quality can be improved. The "isotropic optical film" refers to a film in which nx, ny, and nz are substantially the same, and the "substantially identical" includes all cases including a slight error as well as completely identical cases. In another embodiment, the protective film may be a retardation film having Re of 60 nm or more. For example, the protective film may have a Re of 60 nm to 350 nm. For example, the protective film may have a Re of 8,000 nm or more, specifically 10,000 nm or more, more specifically 10,000 nm or more, more specifically 10,100 nm to 30,000 nm, and 10,100 nm to 15,000 nm. In the above range, it is possible to prevent a rainbow stain from being visually recognized, and a diffusion effect of light diffused through the contrast ratio improving layer may be increased.

The protective coating layer may be formed of an active energy ray-curable resin composition containing an active energy ray-curable compound and a polymerization initiator. The active energy ray-curable compound may include at least one of a cationic polymerizable curable compound, a radical polymerizable curable compound, a urethane resin, and a silicone-based resin. The cationic polymerizable curable compound may be an epoxy compound having at least one epoxy group in the molecule, or an oxetane compound having at least one oxetane ring in the molecule. The epoxy compound may be at least one of a hydrogenated epoxy compound, a chain aliphatic epoxy compound, a cyclic aliphatic epoxy compound, and an aromatic epoxy compound.

The radically polymerizable curable compound can be obtained by reacting two or more types of a (meth)acrylate monomer having at least one (meth)acryloyloxy group in a molecule, and a compound containing a functional group, and at least two (meth)acryloyl oxides in the molecule. (Meth)acrylate oligomers having a time period are mentioned. As the (meth)acrylate monomer, a monofunctional (meth)acrylate monomer having one (meth)acryloyloxy group in the molecule, and a bifunctional (meth)acrylate having two (meth)acryloyloxy groups in the molecule. It may be a monomer, and a polyfunctional (meth)acrylate monomer having three or more (meth)acryloyloxy groups in the molecule. The (meth)acrylate oligomer may be a urethane (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, an epoxy (meth)acrylate oligomer, or the like. The polymerization initiator can cure the active energy ray-curable compound. The polymerization initiator may include at least one of a photocationic initiator and a photosensitizer. The photocationic initiator and photosensitizer may be those commonly known to those skilled in the art.

Preferably, the protective layer 100 may be a non-surface-treated protective film type or a protective coating layer type that is not surface-treated. As will be described in detail below, the optical film with improved contrast ratio does not require surface treatment on the protective layer since the gap fill layer exhibits an anti-glare effect, thus simplifying the manufacturing process of the optical film with improved contrast ratio and improving the contrast ratio due to the surface treatment. May not affect the optical function of the device.

The protective layer 100 may have a refractive index of 1.4 to 1.7, preferably 1.45 to 1.65.

The thickness of the protective layer 100 is from 10 μm to 200 μm, specifically, from 20 μm to 200 μm, in the case of the protective film type, from 20 μm to 250 μm, preferably from 30 μm to 200 μm, and in the case of the protective coating layer type, from 5 μm It can be 50 μm. It can be used for a polarizing plate in the above range.

As shown in FIG. 1, the protective layer 100 may be a single layer or a multilayer structure of two or more protective films or protective coating layers.

Pattern layer

The pattern layer 210 may be formed on the light exit surface of the protective layer 100 to emit light emitted from the protective layer 210. The pattern layer 210 includes an embossed optical pattern 211 on one surface of the pattern layer 210 and a flat portion 212 between the embossed optical pattern 211 and the embossed optical pattern 211 immediately adjacent thereto. It may be a layer having a pattern part. The pattern layer 210 includes the pattern portion directly in contact with the gap fill layer 220 on one surface.

The optical pattern 211 may be an optical pattern including one or more inclined surfaces 213 having a first surface 214 formed on the top and connected to the first surface 214. The pattern portion satisfies Equation 1 below, and the optical pattern 211 may have a base angle θ of 55° to 90°. The base angle θ refers to an angle between 55° and 90° between the inclined surface 213 of the optical pattern 211 and the line of the maximum width W of the optical pattern 211. In this case, the inclined surface 213 means an inclined surface directly connected to the flat portion 212 of the optical pattern 211. Within the above range, it is possible to improve the front contrast ratio and the side contrast ratio at the same time, reduce the difference between the front contrast ratio and the side contrast ratio, and increase the contrast ratio at the same side viewing angle and the same front viewing angle: Specifically, the base angle (θ) Is 70° to 90°, P/W (ratio of P to W) may be 1.2 to 8:

<Equation 1>

1 <P/W ≤ 10

(In Equation 1, P is the period of the pattern part (unit: μm),

W is the maximum width of the optical pattern (unit: μm)).

1 illustrates a case where both base angles θ of the optical pattern are the same, but if the base angles are included in the above 55° to 90°, optical patterns having different base angles θ may be included in the scope of the present invention.

The optical pattern 211 may be an embossed optical pattern including one or more inclined surfaces 213 having a first surface 214 formed on the top and connected to the first surface 214. 1 illustrates a trapezoidal optical pattern in which two adjacent inclined surfaces 213 are connected by a first surface 214 in the optical pattern 211, but the present invention is not limited thereto, and the optical pattern has a trapezoidal cross section. In addition to the phosphorus optical pattern, it may be a rectangular or square optical pattern.

The first surface 214 is formed on the top, so that the light reaching the pattern layer 210 in the optical display device is further diffused by the first surface 214 to increase the viewing angle and brightness. Therefore, it is possible to minimize the luminance loss by increasing the light diffusion effect. The first surface 214 is a flat surface and may facilitate the manufacturing process of the optical film with improved contrast ratio. However, the first surface 214 may have fine irregularities or may be curved. When the first surface is formed as a curved surface, a lenticular lens pattern may be formed. 1 shows a pattern in which one plane is formed on the top (first side) and the inclined plane is a plane, and the cross-section is a trapezoidal shape (eg, a shape in which the upper part of a prism having a triangular cross-section is cut, cut-prism type). . However, the first surface is formed on the top of the embossed optical pattern and the embossed pattern in which the inclined surface is curved (e.g., a cut-lenticular lens in which the upper part of the lenticular lens pattern is cut, or the upper part of the microlens pattern is A cut-micro lens in a cut form may also be included in the scope of the present invention. In addition, a pattern having an N-shape (N is an integer of 3 to 20) such as a rectangle or a square may be included in the cross section.

The first surface 214 may be formed parallel to at least one of the flat portion 212 and the lowest surface of the pattern layer 210. 1 shows a case where the first surface 214 of the optical pattern 211, the flat portion 212, and the lowest surface of the pattern layer 210 are parallel to each other.

The first surface 214 may have a width A of 0.5 μm to 30 μm, specifically 1 μm to 15 μm. In the above range, it can be used for an optical display device, and an effect of improving the contrast ratio can be expected.

The optical pattern 211 may have an aspect ratio (H1/W) of 0.1 to 10, specifically 0.1 to 7.0, and more specifically 0.1 to 5.0. Within the above range, it is possible to improve the contrast ratio and viewing angle from the side of the optical display device.

The maximum height H1 of the optical pattern 211 may be more than 0 μm and less than 20 μm, specifically more than 0 μm and less than 15 μm, and more specifically more than 0 μm and less than 10 μm. In the above range, the contrast ratio is improved, the viewing angle is improved, and the luminance is improved, and moire or the like may not appear.

The maximum width W of the optical pattern 211 may be more than 0 µm and less than 20 µm, specifically more than 0 µm and less than 15 µm, and more specifically more than 0 µm and less than 10 µm. In the above range, the contrast ratio is improved, the viewing angle is improved, and the luminance is improved, and moire or the like may not appear.

1 illustrates a pattern portion in which an optical pattern in which adjacent optical patterns have the same base angle, the width of the first surface, the maximum height, and the maximum width, respectively, is formed. However, neighboring optical patterns may have different base angles, widths of the first surface, maximum heights, and maximum widths.

The flat portion 212 may increase front luminance by emitting light that has passed through the pattern layer 210 to the gap fill layer 220.

The ratio (W/L) of the maximum width (W) of the optical pattern 211 to the width (L) of the flat portion 212 is greater than 0 and 9 or less, specifically 0.1 to 3, more specifically 0.15 to 2 days I can. In the above range, the difference between the front contrast ratio and the side contrast ratio can be reduced, and the contrast ratio can be increased at the same side viewing angle and the same front viewing angle. The width L of the flat portion 212 may be 1 μm to 50 μm, specifically 1 μm to 20 μm. In the above range, there may be an effect of increasing the front luminance.

The flat portion 212 immediately adjacent to the maximum width W of one optical pattern 211 forms one period P. The period P may be 1 μm to 50 μm, specifically 1 μm to 40 μm. Within the above range, it is possible to prevent moiré while having an effect of improving the contrast ratio.

1 shows pattern portions having the same adjacent period and maximum width, respectively, but the period and maximum width may be different from each other.

Although not specified in FIG. 1, FIG. 1 shows that the optical pattern is formed in a stripe-shaped extended shape in the length direction of the optical pattern, but the optical pattern may be formed in a dot shape. The "dot" means that the combination of the filling pattern and the optical pattern is dispersed. Preferably, the optical pattern is formed to extend in a stripe shape, so that the left and right viewing angles can be enlarged.

When the difference in refractive index between the pattern layer 210 and the gap fill layer 220 is 0.06 or more, preferably 0.08 to 0.3, more preferably 0.08 to 0.2, and 0.08 to 0.15, the light diffusion effect may be excellent compared to other frontal CR reduction. .

The pattern layer 210 may have a refractive index of 1.52 or more, preferably 1.55 to 1.70, more preferably 1.60 to 1.70. As described above, the higher the refractive index, the higher the difference between the gap-fill layer and the refractive index, and the light diffusion effect can be maximized.

The pattern layer 210 may be formed of a composition for a pattern layer including at least one of a thermosetting resin and a photocurable resin capable of providing the refractive index.

For example, the pattern layer 210 may be formed of at least one of a resin having an aromatic group and a resin not having an aromatic group (non-aromatic resin). The resin having an aromatic group may include, for example, a resin having fluorene or naphthalene, but is not limited thereto.

The pattern layer 210 may be formed of a composition for a pattern layer including at least one of a thermosetting monomer and a photocurable monomer capable of providing the refractive index. For example, the composition for a pattern layer may contain a bifunctional or higher (meth)acrylic monomer.

Specifically, (meth)acrylic monomers are ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, tricyclodecane dimethanol Di(meth)acrylate, nonanediol di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene Glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, Bifunctional (meth)acrylic systems such as di(meth)acrylates such as tripropylene glycol di(meth)acrylate and hydroxypivalate neopentyl glycol di(meth)acrylate; Trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris2-hydroxyethylisocyanurate tri(meth)acrylic Tri(meth)acrylate, such as tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, etc. Functional (meth)acrylic; Tetrafunctional (meth)acrylic systems such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol tetra(meth)acrylate; 5-functional (meth)acrylic systems, such as dipentaerythritol penta(meth)acrylate and ditrimethylolpropane penta(meth)acrylate; Dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane hexa(meth)acrylate, and the like.

The pattern layer may be formed of a composition for a pattern layer including at least one of a thermosetting resin and a photocurable resin, and at least one of a thermosetting monomer and a photocurable monomer that can provide the refractive index. At least one of a thermosetting resin and a photocurable resin, and at least one of a thermosetting monomer and a photocurable monomer may form a matrix of the pattern layer.

The pattern layer may be formed of a composition for a pattern layer including one or more of high refractive inorganic particles, for example, zirconium oxide (zirconia) and titanium oxide (titania). The composition for a pattern layer including the inorganic particles having a high refractive index can increase the refractive index of the pattern layer and increase the light resistance reliability of the pattern layer even if it does not contain a resin having an aromatic group. A resin having an aromatic group may be yellowed when exposed to external ultraviolet rays for a long period of time, thereby reducing light resistance reliability. The high refractive inorganic particles may be included in 10% to 80% by weight, preferably 20% to 80% by weight, 20% to 75% by weight, more preferably 30% to 70% by weight in the pattern layer. . In the above range, it is possible to increase the refractive index of the pattern layer and increase the light resistance reliability.

The high refractive index inorganic particles are particles having a high refractive index compared to the matrix of the pattern layer, and may have a refractive index of 1.8 or more, preferably 2.0 or more, and 2.0 to 3.0. Within the above range, it may be easy to secure the refractive index of the pattern layer. The inorganic particles may include particles that are not surface-treated, but by surface treatment, compatibility with other components may be improved. The surface treatment may be 5% to 50% of the total surface area of the inorganic particles. Preferably, the pattern layer may include zirconia, and it is easy to adjust the refractive index compared to the gap fill layer, so that the effect of improving visibility may be improved.

The average particle diameter (D50) of the high refractive index inorganic particles may be 1 nm to 80 nm, preferably 5 nm to 50 nm. The average particle diameter (D50) can be measured by a conventional method known to those skilled in the art. In the above range, light scattering does not occur, and there may be an effect of increasing the refractive index of the high refractive index layer.

The composition for a pattern layer may further include at least one of a photoinitiator and a thermal initiator to facilitate formation of the pattern layer by curing the composition. For example, it may include at least one of phosphorus-based, triazine-based, acetophenone-based, benzophenone-based, thioxanthone-based, benzoin-based, oxime-based, and phenylketone-based.

The composition for the pattern layer may further include conventional additives such as a release agent, a defoaming agent, a leveling agent, an antioxidant, an ultraviolet absorber, and a light stabilizer. The composition for the pattern layer may be a solvent-free type that does not contain a solvent, but may further include a solvent to facilitate formation of the pattern layer. As the solvent, a conventional solvent can be used.

Gap fill layer

The gap fill layer 220 is formed directly with one surface of the pattern layer 210 and is formed on the light exit surface of the pattern layer 210. The gap fill layer 220 may increase the light diffusion effect by diffusing light incident from the light exit surface of the pattern layer 210.

The gap fill layer 220 may be a planarization layer for flattening the contrast ratio improving layer 200 by filling at least a part of a gap between the optical pattern 211 of the pattern layer 210 and the adjacent optical pattern 211.

In one embodiment, the gap fill layer 220 may completely fill a gap between the optical pattern 211 of the pattern layer 210 and the adjacent optical pattern 211.

In one embodiment, the thickness of the gap fill layer 220 is greater than the maximum height of the optical pattern 211 and completely fills the gap between the optical pattern 211 of the pattern layer 210 and the neighboring optical pattern 211 The top portion of the optical pattern 211 may be completely covered.

The refractive index of the pattern layer 210 is higher than that of the gap fill layer 220. The contrast ratio improving layer 200 composed of the pattern layer 210 and the gap fill layer 220 can improve the side contrast ratio by diffusing and emitting light incident from the light incident surface of the pattern layer 210, and the side contrast ratio. Even if is increased, the reduction of the front contrast ratio can be minimized, the difference between the front contrast ratio and the side contrast ratio can be reduced, and the contrast ratio can be increased at the same side viewing angle and the same front viewing angle.

The gap fill layer 220 may have a refractive index greater than 0 and 1.53 or less, specifically 1.43 to 1.525. In the above range, the difference in refractive index with the pattern layer may be increased, so that the visibility effect may be excellent.

The gap fill layer 220 may include a matrix and first particles 230 included in the matrix. At least some of the first particles 230 may be exposed on the surface of the gap fill layer 220 to form surface irregularities, and may have the same refractive index compared to the matrix. Through this, the light passing through the pattern layer 210 is not scattered by the first particles, so that the effect of improving visibility is not affected, and the anti-glare effect due to surface irregularities and the moire suppression effect by the first particles exposed to the surface Can also provide. Some of the first particles 230 may be exposed on the surface of the gap fill layer 220 and the rest of the first particles may be dispersed between the optical patterns.

Even if the first particles are dispersed between the optical patterns, the internal haze of the first particles is minimized in the range of 0 to 0.03 of the absolute value of the difference in refractive index compared to the matrix, so that the effect of improving visibility is not affected.

The first particles 230 may be included in 1% to 50% by weight, preferably 2% to 40% by weight, and more preferably 2% to 30% by weight of the gap fill layer 220. In the above range, external unevenness may be formed to have an effect of scattering external light.

In one embodiment, 1% or more and less than 20% of the diameter of the first particles included in the gap fill layer may be exposed on the surface of the gap fill layer, that is, the uppermost surface of the gap fill layer. It can also occur. In the above range, the anti-glare effect can be achieved while maintaining the effect of improving the contrast ratio of light emitted from the pattern layer.

In one embodiment, the maximum distance (also referred to as'skin thickness') between the first surface 214 that is the top of the pattern layer 210 and the top surface of the gap fill layer 220 is more than 0 µm and 15 µm or less, preferably May be 5㎛ to 10㎛. Within the above range, the anti-glare effect can be sufficiently exhibited without affecting the effect of improving the visibility of light emitted from the top of the pattern layer. When a conventional anti-glare film is laminated on an optical film with improved contrast, light emitted from the pattern layer has no choice but to reach the anti-glare particles through the film constituting the anti-glare film. In the present invention, by setting the absolute value of the difference in refractive index between the matrix and the first particle in the gap fill layer to 0 to 0.03 in the thickness of the above-described flesh, the side visibility is improved and the anti-glare effect can be achieved by external irregularities.

The first particles 230 may include particles that generate an anti-glare effect by scattering light incident from the matrix. The first particles may include spherical or amorphous particles, and preferably include spherical particles. Through this, the appearance can be improved by uniformly scattering light on the surface of the gap fill layer.

The first particles may have an average particle diameter (D50) of more than 0 µm to 20 µm or less, preferably 2 µm to 15 µm, and more preferably 2 µm to 10 µm. In the above range, it may be included in the gap fill layer, and an anti-glare effect may be achieved.

The average particle diameter of the first particles may be smaller than the width of the first surface, which is the top portion of the embossed optical pattern, or the maximum width of the embossed optical pattern or the maximum width of the flat portion. In this case, an anti-glare effect may be produced and moiré may not occur.

The first particles 230 are particles having a refractive index in which the absolute value of the difference in refractive index compared to the matrix is 0 to 0.03, and accordingly, the visibility effect of the lower portion can be maintained. An anti-glare effect can be exerted on the light incident from the pattern layer. In one embodiment, the first particles may have the same or lower refractive index compared to the matrix.

The first particles are conventional anti-glare particles and may include at least one of organic particles, inorganic particles, and organic-inorganic hybrid particles. The organic particles may be formed of polymethyl methacrylate, polystyrene, or a copolymer of polymethyl methacrylate and styrene, but are not limited thereto. The inorganic particles may include silica, titania, zirconia, alumina, and the like, but are not limited thereto. Preferably, the compatibility with the matrix can be improved by using organic particles, more preferably polymethyl methacrylate particles.

The first particles may have a refractive index of more than 0 and 1.53 or less, specifically 1.43 to 1.53, and 1.43 to 1.525.

The matrix may support the gap fill layer and support the first particles to be exposed on the surface of the gap fill layer. The matrix may be formed of a composition for a gap fill layer capable of securing an absolute value of 0 to 0.03 of the difference in refractive index compared to the first particle. The matrix may have a refractive index of more than 0 and 1.53 or less, specifically 1.43 to 1.53, and 1.43 to 1.525.

The composition for the gap fill layer may include a photocurable compound, a (meth)acrylic monomer, an initiator, and first particles.

The photocurable compound may include a compound (at least one of oligomers and resins) having a UV curable group, such as a (meth)acrylate group or an epoxy group. The photocurable compound may include at least one of a bifunctional or more polyfunctional (meth)acrylic oligomer, and a resin formed therefrom. The photocurable compound is a polyfunctional (meth)acrylate such as an ester of a polyhydric alcohol and (meth)acrylic acid, or a polyfunctional urethane (meth) synthesized from a polyhydric alcohol, an isocyanate compound, or a hydroxy ester of (meth)acrylic acid. It may include one or more of acrylates. The (meth)acrylic monomer may include one or more of the (meth)acrylic monomers described above in the composition for the pattern layer. The initiator may include at least one of the initiators described above in the composition for the pattern layer. The first particles are as described above.

The composition for the gap fill layer may further include conventional additives such as a dispersant, a defoaming agent, a leveling agent, a slip agent, an antioxidant, an ultraviolet absorber, a light stabilizer, and an anti-fingerprint agent.

For example, a UV reactive silicone additive (eg, UV3500) may be used as a leveling agent. For example, as a dispersant, a high molecular weight block copolymer deagglomeration dispersant (eg, Disperbyk-2163) can be used. For example, a UV-curable fluorine-based acrylic compound (eg, KY 1203) may be used as the anti-fingerprint agent.

The composition for the gap-fill layer may be a solvent-free type that does not contain a solvent, but may further include a solvent to facilitate formation of the gap-fill layer. The solvent may be a conventional solvent, for example, but may include at least one of propylene glycol monomethyl ether acetate and methyl isobutyl ketone, but is not limited thereto.

The composition for the gap fill layer may further include second particles having a higher refractive index than the first particles 230. Through this, when the composition for the gap fill layer is cured, the absolute value of the difference in refractive index between the matrix and the first particle may be greater than 0 and 0.03 or less.

The second particle may have a refractive index of 1.8 or more, preferably 2.0 or more, and 2.0 to 3.0. Within the above range, it may be easy to secure the refractive index of the gap fill layer.

The second particles may include particles substantially the same as those of the inorganic particles having a high refractive index described above in the pattern layer. Preferably, the second particle may include zirconia. The average particle diameter (D50) of the second particles may be 5 nm to 80 nm. The average particle diameter (D50) can be measured by a conventional method known to those skilled in the art. In the above range, there may be an effect of increasing the refractive index of the high refractive layer.

The second particles may be included in a composition for a gap fill layer or a gap fill layer in an amount of 10 wt% to 80 wt%, preferably 10 wt% to 75 wt%, and 15 wt% to 70 wt%. In the above range, there may be an effect of maintaining the hardness of the layer while maintaining the dispersibility.

The maximum thickness of the gap fill layer 220 may be greater than 0 µm and less than 30 µm, for example, greater than 0 µm and less than 20 µm. In the above range, it is possible to prevent the occurrence of warpage such as curl.

The first particles 230 of the contrast ratio improving layer 200 may be included in an amount of 1% to 50% by weight, preferably 2% to 40% by weight. In the above range, the anti-glare effect can be achieved while maintaining the effect of improving the contrast ratio.

The haze of the optical film 10 for improving contrast ratio may be 0% or more and 35% or less. In the above range, it can be used for an optical display device.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG. 2. 2 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

Referring to FIG. 2, the polarizing plate 20 includes a polarizing film 300 and an optical film for improving contrast ratio, and the optical film for improving contrast ratio may include an optical film for improving contrast ratio according to an embodiment of the present invention.

The optical film for improving contrast ratio may be formed on the light exit surface of the polarizing film 300. The contrast ratio improvement optical film may improve a front contrast ratio and a side contrast ratio by diffusing polarized light transmitted through the polarizing film 300 and improve a viewing angle.

The polarizing film 300 may polarize light incident from the liquid crystal panel and transmit it to the contrast ratio improving layer 200. The polarizing film 300 is formed on the light incident surface of the contrast ratio improving layer 200.

The polarizing film 300 may include a polarizer. Specifically, the polarizer may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film. The polarizer may have a thickness of 5 μm to 40 μm. In the above range, it can be used for an optical display device.

The polarizing film 300 may include a polarizer and a protective layer formed on one surface of the polarizer, that is, a light incident surface of the polarizer. The protective layer protects the polarizer, thereby increasing the reliability of the polarizing plate and increasing the mechanical strength of the polarizing plate. The protective layer may include one or more of optically transparent, protective film or protective coating layer. The protective layer is as described above.

The polarizing plate may be formed by a conventional method. For example, it may be prepared by preparing an optical film for improving contrast ratio by the above-described method, and bonding a polarizing film through a first resin layer among the optical films for improving contrast ratio. The first resin layer has excellent adhesion to the polarizing film.

The liquid crystal display device of the present invention may include the polarizing plate of the present invention. In one embodiment, the liquid crystal panel may be included as a polarizing plate on the viewing side. The "view-side polarizing plate" is disposed to face the screen side, that is, the light source side with respect to the liquid crystal panel.

In one embodiment, in the liquid crystal display, a backlight unit, a first polarizing plate, a liquid crystal panel, and a second polarizing plate are sequentially stacked, and the second polarizing plate may include the polarizing plate of the present invention. The liquid crystal panel may employ a vertical alignment (VA) mode, an IPS mode, a patterned vertical alignment (PVA) mode, or a super-patterned vertical alignment (S-PVA) mode, but is not limited thereto. In another embodiment, the liquid crystal panel may be included as a light source side polarizing plate. The "light source side polarizing plate" is disposed on the light source side with respect to the liquid crystal panel. In another embodiment, both the viewing side polarizing plate and the light source side polarizing plate of the liquid crystal panel may include the polarizing plate of the present invention.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are for aiding understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Manufacturing example One: For pattern layer Composition preparation

Non-solvent crude solution containing zirconia HR-10-1 (Japan Catalytic Co., Ltd., average particle diameter of zirconia (D50): 11 nm, zirconia is 80% by weight dispersed in benzyl acrylate as a high refractive index compound, refractive index 1.67) 73 parts by weight, trimethylpropane 22 parts by weight of triacrylate were mixed, 4.5 parts by weight of initiator TPO LG (IGC), and 0.5 parts by weight of release agent BYK 3500 were mixed to prepare a composition for a pattern layer. The refractive index of the composition for pattern layers was 1.60. In the composition for the pattern layer, zirconia is contained in 51% by weight based on solid content.

Manufacturing example 2: Preparation of composition for gap fill layer

As a photocurable compound, UP111 (ENTIS, 70% by weight solid content, solvent: PEME (propylene glycol methyl ether)) 23 parts by weight, SR833S (Sartomer) 8.4 parts, HDDA (ENTIS) 8 parts by weight, PGME (propylene glycol) Monomethyl ether acetate) 46 parts by weight and MIBK (methyl isobutyl ketone) 12 parts by weight were mixed and stirred. After the stirring was completed, 1.15 parts by weight of the initiator Omnirad 184 (IGC), 0.03 parts by weight of UV reactive silicone additive UV3500, 0.07 parts by weight of dispersant Disperbyk-2163 (BYK), and 0.05 parts by weight of anti-fingerprint KY1203 (Shin Etsu) were added and stirred. A crude liquid was prepared.

MSX-105 (refractive index: 1.495, polymethyl methacrylate particles, average particle diameter (D50): 5.41 μm, monodisperse particles, Sekisui Co., Ltd.) was mixed with the crude liquid as organic particles to prepare a composition for a gap fill layer. The organic particles based on the solid content of the composition for a gap-fill layer are contained in an amount of 6% by weight.

Manufacturing example 3: Preparation of composition for gap fill layer

A crude liquid was prepared in the same manner as in Preparation Example 2.

MBX-2H (refractive index: 1.495, polymethyl methacrylate particles, average particle diameter (D50): 2.7 μm, medium-dispersion particles, Sekisui Co.) was mixed with the prepared crude liquid as organic particles to prepare a composition for a gap fill layer. The organic particles based on the solid content of the composition for a gap-fill layer are contained in an amount of 6% by weight.

Manufacturing example 4: Preparation of composition for gap fill layer

As a photocurable compound, UP111 (ENTIS, 70% by weight of solid content, solvent is PEME) 24 parts by weight, zirconia-containing solvent-free crude solution HR-10-1 (Japan Catalytic Company, average particle diameter of zirconia (D50): 11 nm) 17 parts by weight, 46 parts by weight of PGME and 12 parts by weight of MIBK were mixed and stirred. After the stirring was completed, 1.15 parts by weight of the initiator Omnirad 184 (IGC), 0.03 parts by weight of UV reactive silicone additive UV3500, 0.07 parts by weight of dispersant Disperbyk-2163 (BYK), and 0.05 parts by weight of anti-fingerprint KY1203 (Shin Etsu) were added and stirred. A crude liquid was prepared.

MSX-105 (refractive index: 1.495, polymethyl methacrylate particles, average particle diameter (D50): 5.41 μm, monodisperse particles, Sekisui Co., Ltd.) was mixed with the crude liquid as organic particles to prepare a composition for a gap fill layer. The organic particles based on the solid content of the composition for a gap-fill layer are contained in an amount of 6% by weight.

Manufacturing example 5: Preparation of the composition for the gap fill layer

A crude liquid was prepared in the same manner as in Preparation Example 2.

A composition for a gap fill layer by mixing SMX-5R (refractive index: 1.555, polystyrene-polymethylmethacrylate copolymer particles, average particle diameter (D50): 5 μm, polydisperse particles, Sekisui Co., Ltd.) as organic particles in the prepared crude liquid Was prepared. The organic particles based on the solid content of the composition for a gap-fill layer are contained in an amount of 6% by weight.

Manufacturing example 6: gap For fill layer Composition preparation

A crude liquid was prepared in the same manner as in Preparation Example 2.

SBX-4 (refractive index: 1.595, polystyrene particles, average particle diameter (D50): 4 μm, polydisperse particles, Sekisui Co., Ltd.) as organic particles was mixed with the prepared crude liquid to prepare a composition for a gap fill layer. The organic particles based on the solid content of the composition for a gap-fill layer are contained in an amount of 6% by weight.

Manufacturing example 7: gap For fill layer Composition preparation

A crude liquid was prepared in the same manner as in Preparation Example 2. No particles were included.

Manufacturing example 8: gap For fill layer Composition preparation

As a photocurable compound, UP111 (ENTIS, 70% by weight of solid content, solvent: PEME) 38.5 parts by weight, zirconia-containing solvent-free crude solution HR-10-1 (Japan Catalytic Company, zirconia average particle diameter (D50): 11 nm, high refractive index compound) Zirconia is dispersed at 80% by weight in benzyl acrylate) 6.5 parts by weight, 42 parts by weight of PGME, and 12 parts by weight of MIBK were mixed and stirred. After the stirring was completed, 1.15 parts by weight of the initiator Omnirad 184 (IGC), 0.03 parts by weight of UV reactive silicone additive UV3500, 0.07 parts by weight of dispersant Disperbyk-2163 (BYK), and 0.05 parts by weight of anti-fingerprint KY1203 (Shin Etsu) were added and stirred. A crude liquid was prepared.

MXS-105 (refractive index: 1.495, polymethyl methacrylate particles, average particle diameter (D50): 5.41 μm, monodisperse particles, Sekisui Co., Ltd.) as organic particles was mixed with the crude liquid to prepare a composition for a gap fill layer. The composition for a gap-fill layer contains 6% by weight of organic particles and 16% by weight of zirconia based on the solid content.

Manufacturing example 9: For pattern layer Composition preparation

Non-solvent crude solution containing zirconia HR-10-1 (Japan Catalytic Company, an average particle diameter of zirconia (D50): 11 nm, 80% by weight of zirconia is dispersed in benzyl acrylate as a high refractive index compound, refractive index 1.67) 40 parts by weight, trimethyl 60 parts by weight of propane triacrylate was mixed, 4.5 parts by weight of the initiator TPO LG (IGC), and 0.5 parts by weight of the release agent BYK 3500 were mixed to prepare a composition for a pattern layer. The refractive index of the composition for pattern layers was 1.55. In the composition for the pattern layer, zirconia is contained in an amount of 28% by weight based on solid content.

Example One

A coating layer was prepared by coating the composition for a pattern layer of Preparation Example 1 on one side of a polyethylene terephthalate film (SKC, thickness: 40 μm) as a protective layer. A pattern layer was formed by applying and curing the pattern and the flat portion to the coating layer using the optical film in which the embossed prism pattern and the flat portion were formed.

The composition for a gap fill layer of Preparation Example 2 was applied on the pattern layer prepared above with #18, dried at 80° C. for 2 minutes, and photocured to prepare an optical film for improving contrast ratio. Specific specifications of the optical pattern and the flat portion of the prepared optical film for improving contrast ratio are shown in Table 1 below.

The polyvinyl alcohol film was stretched three times at 60° C., adsorbed iodine, and then stretched 2.5 times in a boric acid aqueous solution at 40° C. to prepare a polarizer. A polarizing plate was manufactured by adhering a polarizer to the other surface of the protective layer among the optical films for improving contrast ratio with an adhesive.

Example 2

In Example 1, a contrast ratio improved optical film and a polarizing plate were manufactured in the same manner, except that the composition for a gap fill layer of Preparation Example 3 was used instead of the composition for a gap fill layer of Preparation Example 2.

Example 3

In Example 1, a contrast ratio improved optical film and a polarizing plate were manufactured in the same manner, except that the composition for a gap fill layer of Preparation Example 8 was used instead of the composition for a gap fill layer of Preparation Example 2.

Comparative example 1 to Comparative example 4

In Example 1, a contrast ratio improved optical film and a polarizing plate were manufactured in the same manner, except that the composition for a gap fill layer of Table 2 was used instead of the composition for a gap fill layer of Preparation Example 2.

Comparative example 5

In Example 3, a contrast ratio improved optical film and a polarizing plate were prepared in the same manner, except that the pattern layer composition of Preparation Example 9 was used instead of the pattern layer composition of Preparation Example 1.

Reference example One

A polarizer was manufactured in the same manner as in Example 1. A polarizing plate was manufactured by adhering a polyethylene terephthalate film (SKC, thickness: 40 μm) as a protective layer on one side of the polarizer with an adhesive.

Optical pattern shape Optical pattern height (H1)
(㎛) Optical pattern maximum width (W)
(㎛) Width of the first surface of the optical pattern (A)
(㎛) Base angle of optical pattern
(°) Width of flat part (L)
(㎛) Flesh thickness
(㎛) Cut-prism
(Trapezoid, embossed) 8 8 8 86 10 9

The following physical properties were evaluated for the optical films and polarizing plates for improving the contrast ratio of Examples and Comparative Examples, and the results are shown in Table 2 below.

Haze and total light transmittance ( unit:% ) of the improved contrast ratio optical film : The haze and transmittance were measured with NTH 2000 manufactured by Nippon Denshok. NDH2000 is DF (Diffuse Transmitted Light) in the wavelength range of 400 to 700 nm. Measure PT (parallel transmitted light), TT (total transmitted light), and Haze.

DF: The sum of the light transmitted from the lamp by diffusing it through the sample.

PT: The sum of the light transmitted from the lamp by passing through the sample and going straight.

TT: Sum of diffused and parallel transmitted light

Haze: The degree of haze that appears through the sample.

Haze(%)=DF(Diffuse light)/TT(Total transmitted light)x100

Side contrast ratio ( unit:% ) And viewing angle ( Unit:° ):

For the polarizing plates of Examples and Comparative Examples, the side contrast ratio and 1/2 viewing angle (up and down, left and right) were evaluated, and the results are shown in Table 2 below. The side contrast ratio and 1/2 viewing angle were evaluated by manufacturing a module for a liquid crystal display device by the following method.

Manufacturing of the first polarizing plate

The polyvinyl alcohol film was stretched three times at 60° C., adsorbed iodine, and then stretched 2.5 times in an aqueous boric acid solution at 40° C. to prepare a first polarizer. A first polarizing plate was manufactured by adhering a triacetylcellulose film (thickness 80 μm) as a base layer on both sides of the first polarizer with an adhesive for a polarizing plate (Z-200, Nippon Goshei).

Manufacturing of module for liquid crystal display device

The first polarizing plate, the liquid crystal panel (PVA mode), and the polarizing plates manufactured in Examples and Comparative Examples were sequentially assembled to prepare a module for a liquid crystal display device. The polarizing plates prepared in Examples and Comparative Examples were assembled as a viewing side polarizing plate, and a gap fill layer was disposed at the outermost side toward the viewing side.

A liquid crystal display device including a one-side edge type LED light source by assembling an LED light source, a light guide plate, and a liquid crystal display module (same configuration as Samsung LED TV (UN32H5500) except for the configuration of the liquid crystal display module of Examples and Comparative Examples) ) Was prepared.

Using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM), luminance values were measured in each of the white mode and the black mode for the side surfaces of the spherical coordinate system (0°, 60°). The side contrast ratio was calculated as the ratio of the luminance value of the white mode to the luminance value of the black mode in the spherical coordinate system (0°, 60°). The 1/2 viewing angle was taken as the angle at which 1/2 of the front luminance appeared in the white mode.

External light scattering effect : The external light scattering was evaluated by measuring 60° reflection gloss using BYK Gardner according to JIS Z8741 and ISO 2813. If the 60° reflection gloss is less than 90, the external light scattering effect was evaluated as "yes", and if not, it was evaluated as "no".

Reference example Example Comparative example One One 2 3 One 2 3 4 5 Composition of Gap Fill Layer - Manufacturing Example 2 Manufacturing Example 3 Manufacturing example
8 Manufacturing Example 4 Manufacturing Example 5 Manufacturing Example 6 Manufacturing Example 7 Manufacturing example
8 Pattern layer composition - Manufacturing Example 1 Manufacturing Example 1 Manufacturing Example 1 Manufacturing Example 1 Manufacturing Example 1 Manufacturing Example 1 Manufacturing Example 1 Manufacturing Example 9 Refractive index First particle - 1.495 1.495 1.495 1.495 1.555 1.595 - 1.495 matrix - 1.495 1.495 1.525 1.555 1.495 1.495 1.495 1.525 Pattern layer - 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.55 Protective layer - 1.65 1.65 1.65 1.65 1.65 1.65 1.65 1.65 Refractive index difference 1 - 0.00 0.00 0.03 0.06 0.06 0.100 - 0.03 Refractive index difference 2 - 0.105 0.105 0.08 0.045 0.105 0.105 0.105 0.03 Haze 0 33.5 34.8 34.95 35.24 42.1 56.4 30 33.7 Total light transmittance 90.5 90.94 91.1 91.54 90.86 91.63 91.45 90.5 90.57 Side contrast ratio 100 134 135 124 115 117 123 134 112 1/2
Viewing angle Right and left 62.4 69.8 70.1 68.6 64.2 65.2 63.2 69.8 63.4 Top-bottom 58.3 57.7 57.2 57.6 58.4 58.6 59.3 57.3 58.3 External light scattering effect none has exist has exist has exist has exist has exist has exist none has exist

*Refractive index difference 1: The absolute value of the difference between the refractive index of the matrix and the refractive index of the first particle in the gap fill layer

*Refractive index difference 2: Refractive index of the pattern layer-Refractive index of the gap fill layer

As shown in Table 2, the polarizing plate of the present invention has excellent front visibility and side visibility improvement effect, excellent side contrast ratio, and external light scattering effect by particles.

On the other hand, Comparative Example 1 in which the absolute value of the difference in refractive index between the matrix and the first particle is out of the scope of the present invention and the difference in the refractive index between the pattern layer and the gap fill layer is less than 0.06, the absolute value of the difference in refractive index between the matrix and the first particle is the present invention. Comparative Examples 2 and 3 outside the range of had an external light scattering effect, but the effect of improving front visibility and side visibility was weak, and the side contrast ratio was not good.

Comparative Example 4 containing no particles had no external light scattering effect, and it was necessary to additionally laminate a film to obtain the external light scattering effect, and thus the effect of the present invention could not be obtained.

The absolute value of the difference in refractive index between the matrix and the first particle satisfies the scope of the present invention, but Comparative Example 5 in which the difference in refractive index between the pattern layer and the gap-fill layer is out of the scope of the present invention had a poor side contrast ratio and a good 1/2 left and right viewing angle. Did.

Simple modifications or changes of the present invention can be easily implemented by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (14)

Including a protective layer and a pattern layer formed on the protective layer,
The pattern layer includes a pattern portion having a relief optical pattern on one surface and a flat portion between the relief optical pattern and the adjacent relief optical pattern, and the optical pattern has a base angle θ of 55° to 90° And, the pattern part satisfies the following formula 1,
<Equation 1>
1 <P/W ≤ 10
(In Equation 1, P is the period of the pattern part (unit: μm),
W is the maximum width of the optical pattern (unit: μm)),
Further comprising a gap fill layer in direct contact with one surface of the pattern layer,
The gap fill layer includes a matrix and first particles included in the matrix,
The absolute value of the difference in refractive index between the matrix and the first particle is 0 to 0.03,
The refractive index difference between the pattern layer and the gap fill layer is 0.06 or more, and the refractive index of the pattern layer is higher than that of the gap fill layer.
The optical film of claim 1, wherein the gap fill layer includes irregularities having a height of 1% or more and less than 20% of the diameter of the first particle.
The optical film of claim 1, wherein a maximum distance between the first surface that is the top of the pattern layer and the top surface of the gap fill layer is more than 0 μm and 15 μm or less.
The optical film of claim 1, wherein the average particle diameter of the first particles is smaller than the width of the first surface that is the top of the embossed optical pattern.
The optical film of claim 1, wherein the first particles are contained in an amount of 1% to 50% by weight of the gap fill layer.
The optical film of claim 1, wherein the first particles include anti-glare particles.
The optical film according to claim 1, wherein the ratio (W/L) of the maximum width (W) of the embossed optical pattern to the width (L) of the flat portion (212) is 0.1 to 3.
The optical film of claim 1, wherein the first particles are formed of at least one of polymethyl methacrylate, polystyrene, and a copolymer of polymethyl methacrylate and styrene.
The optical film of claim 1, wherein the pattern layer is formed of a resin without an aromatic group and a composition for a pattern layer comprising inorganic particles having a high refractive index compared to the matrix of the pattern layer.
The optical film of claim 1, wherein the embossed optical pattern includes an optical pattern having a trapezoidal shape, a rectangle shape, or a square shape in cross section.
delete The optical film of claim 1, wherein the gap fill layer further includes second particles having a higher refractive index than the first particles.
Polarizing film; And a contrast ratio improving optical film formed on the light exit surface of the polarizing film, wherein the contrast ratio improving optical film comprises the contrast ratio improving optical film of any one of claims 1 to 10 and 12. .
A liquid crystal display device comprising the polarizing plate of claim 13.

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