KR102194873B1 - Optical film for improving contrast ratio, polarizing plate comprising the same and liquid crystal display apparatus comprising the same - Google Patents

Abstract

Protective layer; And a contrast ratio improving layer including a second resin layer sequentially stacked from the protective layer and a first resin layer facing the second resin layer, wherein the second resin layer has a refractive index higher than that of the first resin layer. High, the first resin layer has a pattern portion having a flat portion between at least one portion facing the second resin layer, two or more embossed optical patterns and the embossed optical pattern and the immediately adjacent embossed optical pattern The second resin layer includes a mixture of a dipyrromethene-based dye and an azopyridone-based dye, a contrast ratio improving optical film, a polarizing plate including the same, and a liquid crystal display including the same.

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 device is operated by emitting light from a backlight unit through a liquid crystal panel. Since light from the backlight unit is vertically incident on the screen of the liquid crystal display device, the side of the screen of the liquid crystal display device has a contrast ratio (CR) relative to the front side. Therefore, development of an optical film with improved contrast ratio that increases the side contrast ratio is in progress.

The contrast ratio improvement optical film includes a high refractive index layer and a low refractive index layer, and improves the side contrast ratio by an optical pattern. The side contrast ratio can be improved by an optical film in which flat portions and optical patterns are alternately formed. However, although the side contrast ratio could have been improved to some extent by the contrast ratio improved optical film, the front contrast ratio decreased as the light emitted to the front was disturbed by the optical pattern. There is a problem in that the reflectance increases due to incident on the optical pattern. On the other hand, when applied to an optical display device, an optical film with improved contrast ratio must be disposed at the outermost side. Therefore, the optical film with improved contrast ratio is continuously exposed to external light. The optical film with improved contrast ratio, which has low light resistance reliability, may cause yellowing or change in light transmittance, thereby lowering the reliability of the optical display device.

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 improving light resistance reliability.

Another object of the present invention is to provide an optical film with improved contrast ratio capable of improving front contrast ratio and lowering reflectance.

Another object of the present invention is to provide a polarizing plate and an optical display device including the optical film for improving contrast ratio of the present invention.

The optical film for improving contrast ratio of the present invention includes a protective layer; And a contrast ratio improving layer including a second resin layer sequentially stacked from the protective layer and a first resin layer facing the second resin layer, wherein the second resin layer has a refractive index higher than that of the first resin layer. High, the first resin layer has a pattern portion having a flat portion between at least one portion facing the second resin layer, two or more embossed optical patterns and the embossed optical pattern and the immediately adjacent embossed optical pattern And, the second resin layer may include a mixture of dipyrromethene-based dye and azopyridone-based dye.

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 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 improving light resistance reliability.

The present invention provides an optical film with improved contrast ratio capable of improving front contrast ratio and lowering reflectance.

The present invention provides a polarizing plate and an optical display device including the optical film for improving contrast ratio of the present invention.

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 a perspective 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, what is 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 this specification, "front" and "side" are based on the horizontal direction, when (φ, θ) by the spherical coordinate system, the front is (0°, 0°), and the left end point When (180°, 90°) and the right end point are (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 expressed by the following formula A:

<Equation A>

Re = (nx-ny) x d

(In Equation A, nx and ny are 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, for the optical film with improved contrast ratio, "ΔYI" refers to the initial YI (yellow index) of the optical film with improved contrast ratio, and YI measured after leaving the optical film with improved contrast under light resistance test conditions is referred to as YIb. When YIb-means YIa.

In the present specification, for the optical film with improved contrast ratio, "△T" denotes the initial T (light transmittance such as total light transmittance) of the optical film with improved contrast ratio, and Tb is the measured T after leaving the optical film with improved contrast under light resistance test conditions When used, it means ｜Tb-Ta｜.

In the present specification, "ΔYI" and "ΔT" of the polarizing plate mean values measured using a polarizing plate instead of the optical film for improving contrast ratio.

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

In the present specification "substituted or unsubstituted", "substituted" means that at least one hydrogen atom in the functional group is a halogen atom (F, Cl, Br or I), a hydroxy group, a nitro group, a cyano group, an amino group (NH ₂ , NH (R ²⁰⁰ ) Or N(R ²⁰¹ )(R ²⁰² ), wherein R ²⁰⁰ , R ²⁰¹ and R ²⁰² are the same or different from each other, and each independently a substituted or unsubstituted C1 to C10 alkyl group or a substituted or unsubstituted C6 to C20 Aryl group), amidino group, hydrazine group, hydrazone group, carboxyl group, C1 to C10 alkyl group, C2 to C10 alkenyl group, C2 to C10 alkynyl group, C5 to C10 alicyclic organic group, C6 to C10 aryl group , And means substituted with one or more substituents selected from the group consisting of C3 to C10 heterocyclic groups.

The inventors of the present invention include a mixture of dipyrromethene-based dye and azo pyridone-based dye in the second resin layer in the contrast ratio improving optical film having the pattern portion described below, thereby providing light fastness reliability. The present invention was found to be excellent, and the front contrast ratio can be improved without affecting the side contrast ratio improvement by the pattern portion, the reflectance can be remarkably lowered, and the degree of side color shift can be reduced. Was completed. The "excellent light resistance reliability" means that a polarizing plate including an optical film with improved contrast ratio or an optical film with improved contrast ratio was irradiated for 500 hours at a light resistance test condition (41mW/m ² at a wavelength of 420 nm, eg: xenon arc of Q-SUN Corporation. lamp), it means that the yellow index (YI) and the amount of change (or rate of change) of the light transmittance are low. This will be described in detail below.

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, in the optical film 10 for improving contrast, a protective layer 100 and a layer for improving contrast 200 are sequentially formed.

Protective layer

The protective layer 100 may be formed on one surface of the contrast ratio improving layer 200 to support the contrast ratio improving layer 200. The protective layer 100 is formed directly with the second resin layer 220 of the contrast ratio improving layer 200, so that the optical film 10 for improving contrast ratio can be thinned. The "directly formed" means that no adhesive layer, adhesive layer, or point adhesive layer is interposed between the protective layer 100 and the contrast ratio improving layer 200. The contrast ratio improving layer 200 is formed on the light incident surface of the protective layer 100.

The protective layer 100 may have a total transmittance of 90% or more, for example, 90% to 100% in the visible light region. In the above range, the incident light can be transmitted without affecting it.

The protective layer 100 may be a protective film or a protective coating layer including a light incident surface and a light exit surface facing the light incident surface. For example, by using a protective film as the protective layer, the degree of support for the contrast ratio improving layer may be excellent.

When the protective layer is a protective film, the protective layer may include a single layer of optically transparent resin film. However, the protective layer may include a case where a plurality of resin films are laminated. 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, non-cyclic-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 greater than 60 nm. For example, the protective film may have a Re of 60 nm to 500 nm and 60 nm to 300 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 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. (Meth)acrylate monomers include monofunctional (meth)acrylate monomers having one (meth)acryloyloxy group in the molecule, and bifunctional (meth)acrylates 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, or an epoxy (meth)acrylate oligomer. 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.

The thickness of the protective layer 100 is 5 µm to 200 µm, specifically, 30 µm to 120 µm, for a protective film type, 30 µm to 100 µm, specifically 50 µm to 90 µm, for a protective coating layer type, 5 µm to Can be 50㎛. It can be used for a polarizing plate in the above range.

Surface treatment layers such as a primer layer, a hard coating layer, an anti-fingerprint layer, an antireflection layer, an anti-glare layer, a low reflection layer, and an ultra low reflection layer may be further formed on at least one surface of the protective layer 100. A hard coating layer, an anti-fingerprint layer, an antireflection layer, etc. may provide additional functions to a protective layer, a polarizing film, and the like. The primer layer can improve adhesion between the protective layer and the adherend (eg, a polarizing film or a second resin layer).

Contrast ratio Improvement floor

The contrast ratio improving layer 200 is formed on the light incident surface of the protective layer 100.

The contrast ratio improving layer 200 includes a first resin layer 210 and a second resin layer 220 facing the first resin layer 210. In one embodiment, the contrast ratio improving layer 200 includes only the first resin layer 210 and the second resin layer 220.

The first resin layer 210 is formed on the light incident surface of the second resin layer 220 so that light incident from the lower surface of the first resin layer 210 may be emitted to the second resin layer 220. . The first resin layer 210 may diffuse light by refracting and emitting light incident from the lower surface in various directions according to the incident position.

The first resin layer 210 is formed directly on the second resin layer 220, and the second resin layer 220 (the lower surface of the second resin layer) directly contacts the first resin layer 210. The pattern portion detailed below is formed on the interface. 1 shows that the pattern portion completely contacts the second resin layer 220. However, it may be included in the scope of the present invention that the pattern portion contacts at least a portion of the second resin layer 220. A portion that does not contact between the second resin layer 220 and the first resin layer 210 may be filled with air or a resin having a predetermined refractive index. For example, the pattern portion is completely in contact with the second resin layer 220.

The pattern unit may include at least one embossed optical pattern 221; And a flat portion 222 formed between the embossed optical pattern 221 and the immediately adjacent optical pattern 221. In the pattern portion, a combination of the embossed optical pattern 221 and the flat portion 222 is repeatedly formed.

The first resin layer 210 includes an upper surface 210a and a lower surface 210b. The upper surface 210a of the first resin layer 210 corresponds to the pattern portion as an interface between the first resin layer 210 and the second resin layer 220.

In one embodiment, the pattern portion satisfies Equation 1 below, and the optical pattern 221 may have a base angle (θ) of 75° to 90°. The base angle θ refers to an angle between the inclined surface 223 of the optical pattern 221 and the line of the maximum width W of the optical pattern 221. In this case, the inclined surface 223 means an inclined surface directly connected to the flat portion 222 of the optical pattern 221. In the above range, the side contrast ratio can be improved, and the contrast ratio can be increased at the same side viewing angle: Specifically, the base angle θ is 80° to 90°, and P/W (the ratio of P to W) is 1.2 to 8 can be:

<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 angle θ is included in the above 75° to 90°, optical patterns having different base angles θ may be included in the scope of the present invention. .

The optical pattern 221 may be an embossed optical pattern including one or more inclined surfaces 223 having a first surface 224 formed on the top and connected to the first surface 224. 1 illustrates a trapezoidal optical pattern in which two adjacent inclined surfaces 223 are connected by a first surface 224, 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 polygonal optical pattern such as a rectangle or a square.

The first surface 224 is formed on the top, so that the light reaching the second resin layer 220 in the optical display device is further diffused by the first surface 224 to increase the viewing angle and brightness. Therefore, it is possible to minimize the luminance loss by enhancing the light diffusion effect. The first surface 224 is a flat surface and may facilitate the manufacturing process of the optical film with improved contrast ratio. However, the first surface 224 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 surface) and the inclined surface 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, a relief pattern in which the first surface is formed on the top of the embossed pattern and the inclined surface is a curved surface (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 cut. In the case of a cut-micro lens), it may be included in the scope of the present invention. In addition, a pattern having an N-shaped (N is an integer of 3 to 20) such as a rectangle or a square may be included.

The first surface 224 is parallel to at least one of the flat portion 222, the lowest surface of the first resin layer 210, and the highest surface of the second resin layer 220 (ie, the upper surface of the second resin layer). Can be formed. 1 shows a case where the first surface 224 of the optical pattern 221, the flat portion 222, the lowest surface of the first resin layer 210, and the highest surface of the second resin layer 220 are parallel to each other. will be.

The first surface 224 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 221 may have an aspect ratio (H1/W) of 0.1 to 10, specifically 0.1 to 7, more specifically 0.1 to 5, and even more specifically 0.1 to 1. 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 221 may be 20 μm or less, specifically 15 μm or less, and more specifically 10 μm or less. In the above range, the contrast ratio is improved, the viewing angle is improved, and the luminance is improved, and moiré may not appear.

The maximum width W of the optical pattern 221 may be 20 μm or less, specifically 15 μm or less, and more specifically 10 μm or less. 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 adjacent optical patterns are formed with optical patterns having the same base angle, a first surface width, a maximum height, and a maximum width. However, neighboring optical patterns may have different base angles, widths of the first surface, maximum heights, and maximum widths.

The flat portion 222 may increase front luminance by emitting light that has passed through the first resin layer 210 to the second resin layer 220.

The ratio (W/L) of the maximum width (W) of the optical pattern 221 to the width (L) of the flat portion 222 may be 9 or less, specifically 0.1 to 3, and more specifically 0.15 to 2 . Within 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. In addition, there may be an anti-moire effect. The width L of the flat portion 222 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 222 immediately adjacent to the maximum width W of one optical pattern 221 forms one period P. The period P may be 1 μm to 50 μm, specifically 1 μm to 40 μm. It is possible to prevent moiré while improving the contrast ratio within the above range.

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

The first resin layer 210 may have a refractive index of less than 1.52, specifically 1.35 or more and less than 1.52. In the above range, the light diffusion effect may be large, manufacture may be easy, and the light diffusion of polarized light and the effect of improving the contrast ratio may be large.

The first resin layer 210 may be formed of a composition for a first resin layer including a curable resin. The composition for the first resin layer may further include an initiator. The curable resin may include at least one of a UV curable resin and a thermosetting resin. The UV curable resin and the thermosetting resin are each of a common type known to those skilled in the art. For example, a (meth)acrylic resin may be used as the curable resin, but is not limited thereto. The initiator is as described in the second resin layer below. The composition for the first resin layer may further include the additive described in the composition for the second resin layer below.

The first resin layer 210 may be non-adhesive without adhesiveness. When the first resin layer 210 is non-adhesive, the optical film for improving the contrast ratio may be laminated to an adherend (eg, a polarizing film) by using an adhesive, an adhesive, or a point adhesive. In the present invention, the first resin layer 210 may be adhesive. When the first resin layer 210 is adhesive, the optical film for improving the contrast ratio can be laminated to the adherend without an additional adhesive, an adhesive, or an adhesive, so that a thinning effect of the polarizing plate can be obtained.

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 optical pattern is dispersed. For example, the optical pattern is formed extending in a stripe shape, so that the left and right viewing angles can be enlarged.

The second resin layer 220 has a higher refractive index than the first resin layer 210. Therefore, the contrast ratio improving layer 200 can improve the side contrast ratio by diffusing and emitting light incident from the light incident surface of the first resin layer 210, and minimizing the reduction of the front contrast ratio even when the side contrast ratio is increased, 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 difference in refractive index between the second resin layer 220 and the first resin layer 210 may be 0.05 or more, specifically 0.05 to 0.3, and more specifically 0.05 to 0.2. In the above range, the effect of improving the diffusion and contrast ratio of light may be large.

The second resin layer 220 may have a refractive index of 1.50 or more, specifically 1.55 to 1.70. In the above range, the light diffusion effect may be excellent.

The second resin layer 220 may include a mixture of a dipyrromethene-based dye and an azopyridone-based dye. The second resin layer 220 is formed on the light exit surface of the first resin layer 210, and when applied to an optical display device, the second resin layer 220 may be more affected by external light than the first resin layer 210. Since the second resin layer 220 includes a mixture of a dipyrromethene-based dye and an azopyridone-based dye, the light resistance reliability of the optical film for improving contrast ratio can be improved and reflectance can be reduced.

In one embodiment, the optical film for improving the contrast ratio may have a ΔYI of 2 or less, for example 1.5 or less, or 1.1 or less, according to the following Equation 2, and a ΔT of 3% or less, for example, 2.8 % Or less, or 1.1% or less. In the above range, the light resistance reliability is excellent, and the optical film can be used for a long time:

<Equation 2>

△YI = YIb-YIa

(In Equation 2, the initial YI of the optical film with improved contrast ratio is YIa,

YI measured after leaving the optical film with improved contrast ratio in light resistance test conditions is referred to as YIb.)

<Equation 3>

△T = ｜Tb-Ta｜

(In Equation 3, the initial light transmittance of the optical film with improved contrast ratio is Ta,

The light transmittance measured after leaving the optical film with improved contrast ratio in light resistance test conditions is referred to as Tb).

In Equation 2, YIa may be 3 or less, for example 1.5 or less, and YIb may be 4 or less, for example 3 or less, or 2 or less. In Equation 3, Ta may be 60% or more, for example 63% or more, and Tb may be 55% or more, for example 60% or more.

In one embodiment, the optical film for improving contrast ratio may have a YI change rate of 250% or less and a T change rate of 4% or less after lightfastness reliability evaluation. The "change rate of YI" may be defined as ΔYI/YIa × 100, and the "change rate of T" may be defined as ΔT/Ta × 100.

In one embodiment, the optical film for improving contrast ratio may have a reflectance of 2% or less, for example, 1.5% or less, as measured by the protective layer. Within the above range, visibility can be improved when applied to an optical display device.

In one embodiment, the mixture of dipyrromethene-based dye and azopyridone-based dye may be a black dye. Through this, the side contrast ratio can be improved by absorbing light incident from the side surfaces of the embossed optical pattern of the first resin layer.

In one embodiment, the dipyrromethene-based dye may have a maximum absorption wavelength of 450 nm to 600 nm. In the above range, there may be an effect of improving the front contrast ratio and lowering the reflectance.

In one embodiment, the dipyrromethene-based dye may be a blue dye or a purple dye.

In one embodiment, the dipyrromethene-based dye may be a zinc (Zn)-containing dipyrromethene-based dye.

In one embodiment, the dipyrromethene-based dye may be an amide bond-containing dipyrromethene-based dye.

In one embodiment, the azopyridone-based dye may have a maximum absorption wavelength of 400nm to 500nm. In the above range, there may be an effect of improving the front contrast ratio and lowering the reflectance.

In one embodiment, the azo pyridone-based dye may be a yellow dye.

In one embodiment, the azo pyridone dye may be a cyano azo pyridone dye.

The "maximum absorption wavelength" refers to a wavelength exhibiting a maximum absorption peak, and can be measured by a conventional method known to those skilled in the art.

The mixture of dipyrromethene-based dye and azopyridone-based dye may be included in an amount of 0.1% to 20% by weight, for example, 0.1% to 5% by weight, in the second resin layer. In the above range, there may be an effect of improving the front contrast ratio, lowering the reflectance, and improving the light resistance reliability.

The dipyrromethene-based dye may be included in an amount of 0.05% to 10% by weight, for example, 0.05% to 5% by weight, and 0.05% to 2.5% by weight of the second resin layer. In the above range, there may be an effect of improving the front contrast ratio, lowering the reflectance, and improving the light resistance reliability.

The azopyridone-based dye may be included in an amount of 0.05% to 10% by weight, for example, 0.05% to 5% by weight, and 0.05% to 2.5% by weight of the second resin layer. In the above range, there may be an effect of improving the front contrast ratio, lowering the reflectance, and improving light resistance reliability.

In one embodiment, the dipyrromethene-based dye is a blue dye, and may be represented by the following Formula 1:

<Formula 1>

(In Formula 1,

R ¹ is a halogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, or a substituted or unsubstituted C6 to C20 aryl group,

R ² is a substituted or unsubstituted C3 to C20 alicyclic cyclic group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C1 to C20 alkoxy group,

m and n are each independently an integer of 0 to 5,

L is represented by the following formula (2),

<Formula 2>

(In Chemical Formula 2,

L ¹ is -O(C=O)- or -S-,

A is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 alicyclic cyclic group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group)

R ³ is a single bond, a substituted or unsubstituted C1 to C20 alkylene group, or-(C=O)O-,

R ⁴ is a (meth)acrylate group, or a substituted or unsubstituted 3 to C20 alicyclic cyclic group,

R ⁵ is hydrogen or a substituted or unsubstituted C1 to C20 alkyl group).

For example, R ⁴ may be a (meth)acrylate group.

In one embodiment, m and n may be 0, respectively.

In another embodiment, R ¹ may be a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, or a substituted or unsubstituted C6 to C20 aryl group.

In one embodiment, R ² may be a substituted or unsubstituted C1 to C20 alkoxy group or a substituted or unsubstituted C6 to C20 aryl group.

In other embodiments, R ² may be a substituted or unsubstituted adamantyl group or a substituted or unsubstituted phenyl group. However, the phenyl group is selected from the group consisting of a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkoxy group, and a substituted or unsubstituted C1 to C10 alkylthio group. Can have.

In one embodiment, R ² is a'unsubstituted adamantyl group'or'halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkoxy group and a substituted or unsubstituted C1 to C10 It may be a phenyl group having only at least one substituent selected from the group consisting of an alkylthio group as a substituent.

In one embodiment, R ³ may be a substituted or unsubstituted C1 to C20 alkylene group.

In one embodiment, L may be represented by any one selected from the group consisting of the following Chemical Formulas 3 to 7.

<Formula 3>

<Formula 4>

<Formula 5>

<Formula 6>

<Formula 7>

(In Chemical Formulas 3 to 7,

R ⁶ is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted amino group, or a substituted or unsubstituted acyl group,

R ⁷ to R ⁹ are each independently a hydroxy group, or a substituted or unsubstituted C1 to C10 alkyl group, provided that at least one of R ⁷ and R ⁸ is a hydroxy group,

R ¹⁰ is a substituted or unsubstituted C1 to C10 alkyl group,

o and p are each independently an integer of 0 to 3, provided that 0 ≤ o + p ≤ 5,

q is an integer from 0 to 4.

The "substituted or unsubstituted amino group" may be represented by the following formula (8).

<Formula 8>

(In Chemical Formula 8,

R ^x is a substituted or unsubstituted C1 to C10 alkyl group,

z is an integer from 0 to 5).

The "substituted or unsubstituted acyl group" may be represented by the following formula (9).

<Formula 9>

In one embodiment, R ⁷ to R ⁹ are each independently a hydroxy group or a t-butyl group (tert-butyl group), provided that at least one of R ⁷ and R ⁸ may be a hydroxy group.

R ¹⁰ may be a substituted or unsubstituted methyl group, a substituted or unsubstituted ethyl group, a substituted or unsubstituted propyl group, a substituted or unsubstituted butyl group, or a substituted or unsubstituted pentyl group.

In one embodiment, the dye of Formula 1 may be represented by the following Formulas 1-1 to 1-3:

<Formula 1-1>

<Formula 1-2>

(In Formula 1-1 and Formula 1-2, R ¹ , R ² , R ⁵ , L are the same as defined in Formula 1, and R ¹¹ , R ¹² , R ¹³ are each independently substituted or unsubstituted C1 to C20 alkyl group, substituted or unsubstituted C1 to C20 alkoxy group, or substituted or unsubstituted C6 to C20 aryl group)

<Formula 1-3>

(In Chemical Formula 1-3, R ² , R ³ , R ⁴ , R ⁵ , and L are as defined in Chemical Formula 1).

In one embodiment, Formula 1 may be represented by any one of Formulas 10-1 to 10-13 below:

<Formula 10-1>

<Formula 10-2>

<Formula 10-3>

<Formula 10-4>

<Formula 10-5>

<Formula 10-6>

<Formula 10-7>

<Formula 10-8>

<Formula 10-9>

<Formula 10-10>

<Formula 10-11>

<Formula 10-12>

<Formula 10-13>

(In Formula 10-13, Ac means *-CO-CH ₃ )

The dye of Formula 1 may be prepared by a conventional method known to those skilled in the art.

In one embodiment, the azo pyridone-based dye may be represented by the following Formula 21:

<Formula 21>

(In Chemical Formula 21,

R ¹ , R ² are each independently a substituted or unsubstituted C1 to C20 alkyl group, *-C(=O)OR', *-OC(=O)R', or a substituted or unsubstituted (meth)acrylate And R'is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, or a substituted or unsubstituted C6 to C20 aryl group,

However, at least one of R ¹ and R ² is a substituted or unsubstituted (meth)acrylate group

R ³ is a substituted or unsubstituted C1 to C20 alkyl group).

In Formula 21, the substituted or unsubstituted (meth)acrylate group may be represented by the following Formula 22, Formula 23, Formula 24, or Formula 25.

<Formula 22>

<Formula 23>

<Formula 24>

<Formula 25>

(In Chemical Formulas 22 to 25,

L ¹ to L ³ are each independently a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C6 to C20 arylene group, or *-L'-C(=O)O-L``-*, and , Wherein L'and L'' are each independently a substituted or unsubstituted C1 to C5 alkylene group or a substituted or unsubstituted C6 to C12 arylene group,

R ⁴ is a hydrogen atom or a methyl group).

In one embodiment, the compound of Formula 21 may be represented by the following Formula 26, Formula 27, Formula 28, and Formula 29:

<Formula 26>

<Formula 27>

<Formula 28>

<Formula 29>

(In Chemical Formulas 26 to 29, R ² and R ³ are as defined in Chemical Formula 21, and L ¹ , L ² , L ³ and R ⁴ are as defined in Chemical Formulas 22 to 25).

Formula 21 may be represented by any one selected from the group consisting of Formulas 30-1 to 30-20.

<Formula 30-1>

<Formula 30-2>

<Formula 30-3>

<Formula 30-4>

<Formula 30-5>

<Formula 30-6>

<Formula 30-7>

<Formula 30-8>

<Formula 30-9>

<Formula 30-10>

<Formula 30-11>

<Formula 30-12>

<Formula 30-13>

<Formula 30-14>

<Formula 30-15>

<Formula 30-16>

<Formula 30-17>

<Formula 30-18>

<Formula 30-19>

<Formula 30-20>

The azopyridone-based dye of Formula 21 can be prepared by a conventional method known to those skilled in the art.

In one embodiment, the dipyrromethene-based dye may include a mixture of a dye represented by Chemical Formula 1 in which R ⁴ is a (meth)acrylate group and an azopyridone-based dye represented by Chemical Formula 21. Through this, the dipyrromethene-based dye and the azopyridone-based dye are cured to form a polymer or cured with a curable resin described below to form a polymer, thereby further improving the light resistance reliability of the second resin layer.

The second resin layer may be formed of a composition for a second resin layer comprising a mixture of dipyrromethene-based dye and azopyridone-based dye.

The composition for the second resin layer may further include at least one of a UV-curable compound and a heat-curable compound as a curable compound. The "compound" may include one or more of a monomer, an oligomer, or a resin. For example, by using a UV-curable compound as the curable compound, the second resin layer can be formed in a short period of time, and the pattern shape can be well formed when the pattern is formed. It may include a UV-curable compound (meth)acrylic monomer, oligomer, or resin.

In one embodiment, the curable compound is a resin having high refractive properties, and may include a compound having a benzene ring structure and a compound having a repetition plate derived from a compound containing a benzene ring structure as a main skeleton. Through this, it is possible to secure a high refractive index of the second resin layer. At this time, the curable resin may have a refractive index of 1.55 or more, for example, 1.58 to 1.62 after curing. Within the above range, it is possible to secure the refractive index of the second resin layer.

In one embodiment, the curable compound may include a compound having a monofunctional to 6functional curable functional group (eg, a UV curable functional group, a thermosetting functional group). For example, the curable compound is 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol (600) di(meth)acrylate. ) Polyethylene glycol di(meth)acrylate including acrylate, neopentyl glycol adipate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylic Rate, ethylene oxide-modified di(meth)acrylate, di(meth)acryloxy ethyl isocyanurate, allylated cyclohexyl di(meth)acrylate, tricyclodecanedimethanol (meth)acrylate, dimethylol dish Clopentanedi(meth)acrylate, ethylene oxide-modified hexahydrophthalic acid di(meth)acrylate, tricyclodecane dimethanol(meth)acrylate, neopentyl glycol-modified trimethylpropane di(meth)acrylate, adamantane Difunctional (meth)acrylates such as di(meth)acrylate or 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; Trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide Ethylene oxide modified trimethylolpropane tri(meth)acrylate, including modified trimethylolpropane tri(meth)acrylate, ethoxylated (6) trimethylolpropane tri(meth)acrylate, or tris(meth) Trifunctional (meth)acrylates such as acryloxyethyl isocyanurate; Tetrafunctional (meth)acrylates such as diglycerin tetra(meth)acrylate or pentaerythritol tetra(meth)acrylate; 5-functional (meth)acrylates such as dipentaerythritol penta (meth)acrylate; And 6-functional acrylates such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate, but are not limited thereto. For example, the (meth)acrylate monomer is trifunctional (meth)acrylate such as ethylene oxide-modified trimethylolpropane tri(meth)acrylate including ethoxylated (6) trimethylolpropane tri(meth)acrylate, etc. )Acrylate can be used.

In the composition for the second resin layer, the curable compound may be included in an amount of 5% to 40% by weight, for example, 10% to 30% by weight. Within the above range, the process of forming the second resin layer after pattern formation may be easy and there may be an effect of improving mechanical properties.

The composition for the second resin layer may further include an initiator.

The initiator cures the curable compound and may include at least one of a photo initiator and a thermal initiator. These can use common types known to those skilled in the art. The photoinitiator may include at least one of phosphorus-based, triazine-based, acetophenone-based, benzophenone-based, thioxanthone-based, benzoin-based, oxime-based, and phenylketone-based.

The initiator may be included in an amount of 5% by weight or less, for example, 1% to 5% by weight of the composition for the second resin layer or the second resin layer based on solid content. In the above range, the composition for the second resin layer can be sufficiently cured, and the light transmittance of the contrast ratio improving layer can be prevented from being lowered with the remaining amount of initiator.

The composition for the second resin layer may further include inorganic nanoparticles.

By further including inorganic nanoparticles, the contrast ratio is improved. Even if the surface hardness of the optical film is increased or the refractive index of the second resin layer is not used, even if a compound having an aromatic group is not used, the light resistance reliability can be improved and the side contrast ratio is improved. can do.

In one embodiment, the inorganic nanoparticles may include one or more of zirconia, titania, silica, and alumina. For example, zirconia may be included as an inorganic nanoparticle. In particular, by including zirconia, even if a compound having an aromatic group is not used in the second resin layer, the refractive index of the second resin layer is increased, thereby improving light resistance reliability and improving the side contrast ratio.

Zirconia may have a refractive index of 1.5 or more, for example, 1.5 to 2.5. In the above range, the refractive index of the second resin layer may be increased, and the reflectance may be lowered by adjusting the refractive index between the second resin layer and the first resin layer to improve visibility. Zirconia is spherical or non-spherical, for example, spherical particles and may have an average particle diameter (D50) of 5 nm to 100 nm, for example 10 nm to 30 nm. In the above range, it can be used for the second resin layer, and the transmittance and haze of the film can be improved to improve the optical properties, and the thinning effect of the film can be obtained. Zirconia may not be surface-treated, but surface treatment prevents the composition for the second resin layer from becoming a sol, thereby enhancing the stability of the crude liquid. For example, zirconia may be surface-treated with a (meth)acrylic compound or the like, but is not limited thereto.

The inorganic nanoparticles may be included in an amount of 5% to 75% by weight, for example, 15% to 55% by weight, and 25% to 55% by weight of the second resin layer or the composition for the second resin layer. In the above range, the light resistance reliability of the film may be increased, and the improvement of the viewing angle due to the optical pattern may not be affected.

The composition for the second resin layer uses a common solvent such as ethanol (EtOH), propylene glycol monomethyl ether acetate (PGME), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), etc. It may include, but is not limited thereto.

The composition for the second resin layer may further include conventional additives known to those skilled in the art. The additive may include at least one of a dispersant, a leveling agent, a surface modifier, an antioxidant, an antifoaming agent, an ultraviolet absorber, and a light stabilizer.

The maximum thickness of the second resin layer 220 may be 30 μm or less, for example, 20 μm or less. In the above range, it is possible to prevent the occurrence of warpage such as curl.

The maximum thickness of the second resin layer 220-The maximum height of the optical pattern 221 (also referred to as a “skin thickness”) may be 30 μm or less, for example, 20 μm or less, or 10 μm or less. In the above range, there may be an effect of minimizing a reduction in side contrast ratio.

The contrast ratio improving layer 200 may have a thickness of 10 μm to 100 μm, specifically 10 μm to 50 μm, and more specifically 10 μm to 40 μm. In the above range, it can be used for an optical display device.

The contrast ratio improving layer can be manufactured by a conventional method known to those skilled in the art. For example, the contrast ratio improvement layer is formed by coating the composition for the second resin layer on the protective layer, applying and curing the optical pattern and the flat portion to form a second resin layer, and applying and curing the composition for the first resin layer. Can be, but is not limited thereto.

Hereinafter, an optical film for improving contrast ratio according to another embodiment of the present invention will be described.

The optical film for improving contrast ratio of the present embodiment includes a dipyrromethene-based dye; And a mixture of a polymer of an azopyridone-based dye and a UV-curable monomer, and are substantially the same as the optical film for improving the contrast ratio of the present embodiment. By including a polymer of an azopyridone-based dye and a UV-curable monomer instead of the azo-pyridone-based dye, it is possible to further increase the light resistance reliability improvement effect.

The "UV curable monomer" may include a monomer having 1 to 6 (meth)acrylate groups. For example, the UV curable monomer may include at least one of methyl acrylate, methyl meth acrylate, ethyl acrylate, and ethyl meth acrylate, but is not limited thereto.

The dipyrromethene-based dye may be a dipyrromethene-based dye of Formula 1. The azo pyridone-based dye may be an azo pyridone-based dye represented by Chemical Formula 21.

Hereinafter, an optical film for improving contrast ratio according to another embodiment of the present invention will be described.

The optical film for improving the contrast ratio of the present embodiment includes an azopyridone dye; And a mixture of a polymer of a dipyrromethene-based dye and a UV-curable monomer, and is substantially the same as the optical film for improving the contrast ratio of the present embodiment. By including a polymer of a dipyrromethene-based dye and a UV-curable monomer instead of the dipyrromethene-based dye, it is possible to further improve the light resistance reliability improvement effect. The dipyrromethene-based dye may be a dipyrromethene-based dye of Formula 1 wherein R ⁴ is a (meth)acrylate group. The azo pyridone-based dye may be an azo pyridone-based dye represented by Chemical Formula 21.

Hereinafter, an optical film for improving contrast ratio according to another embodiment of the present invention will be described.

The optical film for improving contrast ratio of the present embodiment is a polymer of a dipyrromethene-based dye and a UV curable monomer; And a mixture of a polymer of an azopyridone-based dye and a UV-curable monomer, and are substantially the same as the optical film for improving the contrast ratio of the present embodiment. Through this, the light resistance reliability improvement effect may be greater.

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 optical film for improving contrast ratio may diffuse polarized light transmitted through the polarizing film 300 to improve a front contrast ratio and a side contrast ratio, improve a viewing angle, and improve black visibility.

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 at least one 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 manufactured by manufacturing an optical film for improving contrast ratio by the above-described method, and bonding a polarizing film to the other surface of the protective layer. The adhesion may be formed with one or more of commonly known water-based and photo-curable adhesives.

The liquid crystal display 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 a 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 still 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 1: of formula 10-13 Dipyrromethenic Dye manufacturing

<Formula 10-13>

To 15 mL of acetic acid neat solution, 4 g of amino pyrrole acrylate was added and stirred at room temperature. Triethylorthoformate was slowly added dropwise to the obtained reaction solution. The temperature of the obtained reaction solution was raised to 90° C. and stirred for 12 hours. The precipitate generated after the reaction was washed with acetonitrile and dried to obtain Diamino dipyrromethane (2).

Diamino dipyrromethane (2) 3 g and 51 mL of Toluene were added, and NaOH (aq.) 8 mL was added, followed by stirring at room temperature. 3.5 g of benzoyl chloride was slowly added dropwise to the obtained reaction solution. The solution was stirred at 100° C. for 12 hours. After the reaction was completed, Toluene was removed. H ₂ O + NaCl (aq) was added to the obtained product, extracted with dichloro methane, separated, and the solvent was dried by evaporation to obtain the diamide dipyrromethane (3).

To 3.3 g of diamide dipyrromethane (3), 32 ml of Ethanol was added and stirred at room temperature. 0.7 g of Zn(OAc) ₂ was slowly added dropwise to the obtained reaction solution. The obtained reaction solution was stirred at room temperature for 3 hours. After completion of the reaction, work up with water and extracted with dichloromethane. Evaporation was performed and precipitation was washed with methanol to obtain the Zn chelated Dipyrromethane product (4).

Manufacturing example 2: of formula 30-1 Azo Preparation of pyridone dye

<Formula 30-1>

In a 125 mL Erlenmeyer flask, 3.12 g of 4-aminobenzoic acid, 75.6 ml of DI water, and 17.28 ml of HCl (35%) were stirred under an ice bath. 14.4ml of sodium nitrite aqueous solution (1mM) was added dropwise and stirred for 3 hours under an ice bath. 4.35g of ethyl cyanoacetate and 4.97g of ethylhexylamine were added and reflux reaction was performed at 110℃ for 2 hours. 5g of ethylaetoacetate and 3.76g of piperidine were added and reacted overnight under reflux. After TLC confirmation, the pyridone compound (1) was synthesized by washing with acid and water several times.

4.722 g of pyridone compound (1) was added to 20 ml of DI water, and then NaOH aqueous solution was added (pH 8) to dissolve. The dissolved pyridone compound (1) was added to the 125 ml Erlenmeyer flask containing 4-aminobenzoic acid, and the pH was adjusted to neutral with sodium carbonate (10%) aqueous solution. After filter purification with water, it was dried in vacuo to give compound (2). 5.5 g of compound (2) was added to a 250 ml flask, 2.09 g of (3), 2.16 g of TBAB, and 70 ml of acetonitrile were added, followed by an overnignt reaction at 90° C. under reflux. After work-up with MC/water, column purification was performed to synthesize the compound represented by Chemical Formula 30-1. ¹ H NMR of the prepared Chemical Formula 30-1 is as follows: ¹ H NMR (DMSO): 15.02 (s, 1H), 8.1 (m, 1H), 7.94 (m, 1H), 7.73 (m, 1H), 7.55(m, 1H), 6.65(m, 1H), 6.17(m, 1H), 4.7(m, 1H), 4.3(m, 2H), 3.9(m, 2H), 2.03(s, 1H) 1.73( m, 3H), 1.96 (m, 3H), 1.81 (m, 1H), 1.28 (m, 8H), 0.91 (m, 6H).

Example One

( 1) For the second resin layer Composition preparation

In a mixed solvent of 5,000 mL of cyclohexanone and 5,000 mL of PGMEA (propylene glycol monomethyl ether acetate), 3 g of the dye of Formula 10-13 prepared in Preparation Example 1 and 3 g of methyl methacrylate (MMA) were added, and a thermal reaction initiator 0.2 g of phosphorus V-601 was added. Polymerization was performed at 90° C. for 24 hours to prepare 5 g of a dye polymer in which the dye of Formula 10-13 was polymerized.

To a mixed solvent of 3,000 mL of cyclohexanone and 3,000 mL of PGMEA, 2 g of a dye of Formula 30-1 prepared in Preparation Example 2 and 2 g of MMA were added, and 0.15 g of V-601, a thermal reaction initiator, was added. Polymerization was performed at 90° C. for 24 hours to prepare 3 g of a dye polymer in which the dye of Formula 30-1 was polymerized.

A dye mixture was prepared by mixing the prepared dye polymer of Formula 10-13 polymerized with the dye polymer of Formula 30-1. In the dye mixture, 50% by weight of the dye polymer polymerized with the dye of Formula 10-13 and 50% by weight of the dye polymer polymerized with the dye of Formula 30-1 are included.

Trimethylolpropane triacrylate 45 parts by weight, initiator TPO-L 2 parts by weight, zirconia sol (average particle diameter of zirconia (D50): 10 nm, solid content: 40% by weight, KC Tech, SP-40B) 53 parts by weight of a resin mixture The composition was prepared.

A composition for a second resin layer was prepared by mixing 80 parts by weight of the resin composition and 20 parts by weight of the prepared dye mixture.

( 2) For the first resin layer Composition preparation

100 parts by weight of the sticky PL8540 as an acrylic copolymer was mixed with 80 parts by weight of methyl ethyl ketone as a diluent, and stirred at 500 rpm for 30 minutes using a stirrer to prepare a composition for a first resin layer.

( 3) Contrast ratio Improved optical film manufacturing

As a protective layer, a coating layer was formed by applying the prepared composition for a second resin layer on one surface (light incident surface) of a polyethylene terephthalate (PET) film (Toyobo, TA044, thickness: 80 μm). A second resin layer was formed by applying the optical pattern and the flat portion to the coating layer using a film in which the optical pattern and the flat portion were alternately formed, and UV curing with an amount of UV 500 mJ/cm ² .

The prepared first resin layer composition was coated on one side of the prepared second resin layer and dried in a dry oven at 90° C. for 4 minutes to form a first resin layer, thereby preparing an optical film for improving contrast ratio. The first resin layer has adhesiveness and has a lower refractive index than the second resin layer. Table 1 below shows the specifications of the pattern portion of the contrast ratio improvement layer.

( 4) Polarizing plate Produce

A polarizing plate was prepared by laminating one side of the first resin layer of the contrast ratio improved optical film and the side of the PET film of the lower plate polarizing film (product name AMN-6143CPS(CO)) having a three-layer PET/PVA/COP structure of Samsung SDI.

Example 2

In Example 1, 90 parts by weight of a resin composition and 10 parts by weight of a dye mixture were mixed to prepare a composition for a second resin layer, and a contrast ratio improving optical film and a polarizing plate were prepared in the same manner.

Example 3

In Example 1, 50 parts by weight of the resin composition and 50 parts by weight of the dye mixture were mixed to prepare a composition for a second resin layer, and a contrast ratio improving optical film and a polarizing plate were prepared in the same manner.

Example 4

In Example 1, a contrast ratio improved optical film and a polarizing plate were prepared in the same manner, except that 70 parts by weight of the resin composition and 30 parts by weight of the dye mixture were mixed to prepare a composition for the second resin layer.

Example 5

In Example 1, a contrast ratio improved optical film and a polarizing plate were prepared in the same manner, except that 99 parts by weight of the resin composition and 1 part by weight of the dye mixture were mixed to prepare the composition for the second resin layer.

Example 6

The dye of Formula 10-13 of Preparation Example 1, the dye of Formula 30-1 of Preparation Example 2, trimethylolpropane triacrylate, initiator TPO-L, zirconia sol (average particle diameter of zirconia (D50): 10 nm, solid content: 40 % By weight, KC Tech, SP-40B) was mixed to prepare a composition for a second resin layer comprising the dye and zirconia shown in Table 1 below on a solid basis.

In Example 1, an optical film for improving contrast ratio and a polarizing plate were manufactured in the same manner, except that the composition for the second resin layer was used instead of the composition for the second resin layer.

Comparative example One

Without an optical film for improving the contrast ratio, a lower polarizing film (product name AMN-6143CPS(CO)) having a three-layer PET/PVA/COP structure from Samsung SDI was used.

Comparative example 2

In Example 1, as a composition for a second resin layer, 99.5 parts by weight of the resin composition and Orasol® Black X51 (BASF, average particle diameter (D50): 10 nm, powder, chromium metal: 1: 2 complex salt of azo compound) 0.5 Except for using the composition for the second resin layer prepared by mixing parts by weight, contrast ratio improved optical film and polarizing plate were prepared in the same manner.

Comparative example 3

In Example 1, as the composition for the second resin layer, the contrast ratio was improved by the same method except for using the composition for the second resin layer prepared by mixing 99.5 parts by weight of the resin composition and 0.5 parts by weight of the dye of Formula 10-13. A film and a polarizing plate were prepared.

Comparative example 4

In Example 1, as the composition for the second resin layer, the contrast ratio was improved by the same method except for using the composition for the second resin layer prepared by mixing 99.5 parts by weight of the resin composition and 0.5 parts by weight of the dye of Formula 30-1. A film and a polarizing plate were prepared.

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)
(㎛) Cycle(P)
(㎛) Cut-prism
(Trapezoid, embossed pattern) 5 8 6.7 86 7 15

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 Tables 2 and 3 below.

Panel reflectance : A spectrophotometer (Konica Minolta, CM-2600D), which is a reflectance measuring instrument, after laminating the optical film for improving the contrast ratio of the Examples and Comparative Examples on an LCD VN-type Samsung Electronics SUHD 55-inch liquid crystal panel with an adhesive having a refractive index of 1.46 to 1.50 In the SCI reflection mode (light source: D65 light source), it was measured in a range of 320 nm to 800 nm in wavelength, but the Y (D65) value was measured among the measured values.

Yellow index : For optical films with improved contrast ratios of Examples and Comparative Examples, transmission mode (light source: D65 light source, light source aperture: Φ25.4mm, measurement viewing angle: 2°, 8mm diameter) with a spectrophotometer (Konica Minolta, CM3600A) Mode) in the range of 320 nm to 800 nm. The initial YI measured for the contrast ratio improved film specimen was referred to as YIa, and the YI measured after the contrast ratio improved film specimen was left to stand in the following light resistance test conditions was referred to as YIb.

Light transmittance: The light transmittance was measured with NDH 2000 manufactured by Nippon Denko for the optical films with improved contrast ratio of the Examples and Comparative Examples. The initial light transmittance initially measured for the contrast ratio improved optical film specimen was Ta, and the light transmittance measured after the contrast ratio improved optical film specimen was allowed to stand under the following light resistance test conditions was referred to as Tb.

(Light resistance test evaluation method)

Q-SUN's Xe-1-S light resistance device was used. The sample was placed so that the light irradiated by the light source of the light-resistant device and the protective layer of the optical film for improving contrast ratio face each other. Measurement conditions are using Daylight BB Filter, and the amount of light is 41mW/m ² at a wavelength of 420nm. After 500 hours, the light is turned off and the change due to light is evaluated.

Light source side Manufacture of polarizer

The polyvinyl alcohol film was stretched 3 times at 60°C, adsorbed iodine, and then stretched 2.5 times in an aqueous boric acid solution at 40°C to prepare a polarizer. A polarizing plate was prepared by bonding a triacetylcellulose film (thickness: 80 μm) as a base layer on both sides of the polarizer with an adhesive for a polarizing plate (Z-200, Nippon Goshei). The prepared polarizing plate was used as a light source side polarizing plate.

Manufacturing of module for liquid crystal display device

The prepared light source side polarizing plate, a liquid crystal panel (PVA mode), and the polarizing plates prepared in Examples and Comparative Examples were sequentially assembled to prepare a module for a liquid crystal display. Of the polarizing plates prepared in Examples and Comparative Examples, the protective layer was assembled to come out to the outermost.

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 (Samsung TV (55-inch, manufactured in 2016, excluding the configuration of the liquid crystal display module of Examples and Comparative Examples) Model name: UN55KS8000F) and the same configuration) was prepared.

Using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM), the spherical coordinate system is used in white mode and black mode at the front (0°, 0°) and side (0°, 60°). The luminance value was measured. The front 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°, 0°). 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°). It was calculated as a ratio to Comparative Example 1.

Example One 2 3 4 5 6 First resin layer Refractive index 1.47 1.47 1.47 1.47 1.47 1.47 Resin 2
layer Refractive index 1.59 1.60 1.61 1.61 1.62 1.59 Dipyrromethenic dye
(weight%) One 0.5 2.5 1.5 0.05 One Azopyridone dye
(weight%) One 0.5 2.5 1.5 0.05 One Zirconia
(weight%) 42.4 47.7 50.35 51.41 52.47 29.6 Contrast ratio
(%) (0°, 0°) 64 71 84 84 88 66 (0°, 60°) 65 72 83 83 88 65 Panel reflectance (%) 0.42 0.72 0.81 0.92 1.02 0.43 YIa 0.83 0.65 0.55 0.52 0.43 0.92 YIb 1.72 1.58 1.62 1.26 1.42 1.88 △YI 0.89 0.93 1.07 0.74 0.99 0.96 Ta(%) 75.3 78.8 81.3 82.0 87.0 63.2 Tb(%) 74.2 76.0 80.5 81.2 86.3 61.4 △T(%) 1.1 2.8 0.8 0.8 0.7 1.8

Comparative example One 2 3 4 First resin layer Refractive index - 1.47 1.47 1.47 2nd resin layer Refractive index - 1.62 1.63 1.63 X51
(weight%) - 0.5 0 0 Dipyrromethenic dye
(weight%) - 0 0.5 0 Azopyridone dye
(weight%) - 0 0 0.5 Zirconia (% by weight) - 53 53 53 Contrast ratio (%) (0°, 0°) 100 90.0 87.1 85 (0°, 60°) 100 141 88.8 84.1 Panel reflectance (%) 0.35 0.82 0.74 0.54 YIa 0.55 0.56 0.62 0.66 YIb 0.67 3.82 3.77 3.71 △YI 0.12 3.26 3.15 3.05 Ta(%) 94 82.2 84.4 85.1 Tb(%) 93 77.2 80.3 81.5 △T(%) One 5.0 4.1 3.6

As shown in Table 2, the optical film for improving contrast ratio of the present invention can improve front contrast ratio, lower reflectance, and improve light resistance reliability.

On the other hand, Comparative Example 1 containing a metal complex dye in the second resin layer had poor light resistance reliability. Comparative Examples 2 and 3 including only one of dipyrromethene-based dye and azopyridone-based dye also had poor light resistance reliability.

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 (23)

Protective layer; And a contrast ratio improving layer including a second resin layer sequentially stacked from the protective layer and a first resin layer facing the second resin layer,
The second resin layer has a higher refractive index than the first resin layer,
The first resin layer includes at least a portion facing the second resin layer, a pattern portion having two or more embossed optical patterns and a flat portion between the embossed optical pattern and the immediately adjacent embossed optical pattern, ,
The second resin layer comprises a mixture of dipyrromethene-based dye and azopyridone-based dye, contrast ratio improving optical film.
The optical film for improving contrast ratio of claim 1, wherein ΔYI according to Equation 2 below is 2 or less:
<Equation 2>
△YI = YIb-YIa
(In Equation 2, the initial YI of the optical film with improved contrast ratio is YIa,
YI measured after leaving the optical film with improved contrast ratio in light resistance test conditions is referred to as YIb).
The optical film for improving contrast ratio of claim 1, wherein ΔT according to Equation 3 below is 3% or less:
<Equation 3>
△T = ｜Tb-Ta｜
(In Equation 3, the initial total light transmittance of the optical film with improved contrast ratio is Ta,
The total light transmittance measured after leaving the optical film with improved contrast ratio under light resistance test conditions is referred to as Tb).
The optical film of claim 1, wherein the mixture is a black dye.
The optical film of claim 1, wherein the dipyrromethene-based dye has a maximum absorption wavelength of 450 nm to 600 nm.
The optical film of claim 1, wherein the azopyridone-based dye has a maximum absorption wavelength of 400 nm to 500 nm.
The optical film of claim 1, wherein the dipyrromethene-based dye is a blue dye or a purple dye.
The optical film of claim 1, wherein the azopyridone-based dye is a yellow dye.
The optical film of claim 1, wherein the dipyrromethene-based dye is a dipyrromethene-based dye containing zinc (Zn).
The optical film of claim 1, wherein the azo pyridone dye is a cyano azo pyridone dye.
The optical film of claim 1, wherein the dipyrromethene-based dye is represented by the following formula (1):
<Formula 1>

(In Formula 1,
R ¹ is a halogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, or a substituted or unsubstituted C6 to C20 aryl group,
R ² is a substituted or unsubstituted C3 to C20 alicyclic cyclic group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C1 to C20 alkoxy group,
m and n are each independently an integer of 0 to 5,
L is represented by the following formula (2),
<Formula 2>

(In Chemical Formula 2,
L ¹ is -O(C=O)- or -S-,
A is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 alicyclic cyclic group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group)
R ³ is a single bond, a substituted or unsubstituted C1 to C20 alkylene group, or-(C=O)O-,
R ⁴ is a (meth)acrylate group, or a substituted or unsubstituted 3 to C20 alicyclic cyclic group,
R ⁵ is hydrogen or a substituted or unsubstituted C1 to C20 alkyl group).
The optical film of claim 1, wherein the azopyridone dye is represented by the following formula (21):
<Formula 21>

(In Chemical Formula 21,
R ¹ , R ² are each independently a substituted or unsubstituted C1 to C20 alkyl group, *-C(=O)OR', *-OC(=O)R', or a substituted or unsubstituted (meth)acrylate And R'is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, or a substituted or unsubstituted C6 to C20 aryl group,
However, at least one of R ¹ and R ² is a substituted or unsubstituted (meth)acrylate group
R ³ is a substituted or unsubstituted C1 to C20 alkyl group).
The method of claim 1, wherein the dipyrromethene-based dye is the following formula 10-13,
The azo pyridone-based dye is of the following formula 30-1, contrast ratio improved optical film:
<Formula 10-13>

<Formula 30-1>

The optical film of claim 1, wherein the mixture is contained in an amount of 0.1% to 20% by weight of the second resin layer.
The optical film of claim 1, wherein the second resin layer further comprises zirconia.
The method of claim 1, wherein the second resin layer comprises the dipyrromethene-based dye; And a mixture of a polymer of the azopyridone-based dye and a UV-curable monomer.
According to claim 1, The second resin layer is a polymer of the dipyrromethene-based dye and a UV curable monomer; And a mixture of the azopyridone dyes.
According to claim 1, The second resin layer is a polymer of the dipyrromethene-based dye and a UV curable monomer; And a mixture of a polymer of the azopyridone-based dye and a UV-curable monomer.
The optical film of claim 1, wherein the first resin layer is adhesive.
The optical film of claim 1, wherein the optical pattern comprises a pattern having a trapezoidal shape, a rectangle shape, or a square shape in cross section.
The optical film of claim 1, wherein the embossed optical pattern has a base angle (θ) of 75° to 90°, and the pattern portion satisfies the following Equation 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)).
Polarizing film; And the optical film for improving the contrast ratio of any one of claims 1 to 21 formed on the light exit surface of the polarizing film.
A liquid crystal display device comprising the polarizing plate of claim 22.

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