KR20180116739A - Optical film for improving contrast ratio, polarizing plate comprising the same and liquid crystal display apparatus comprising the same - Google Patents

Abstract

Provided are an optical film with an improved contrast ratio, a polarizing plate including the same, and an optical display device including the same. The optical film with an improved contrast ratio comprises: a contrast ratio improvement layer; and at least one of an anti-reflection layer and an antiglare layer directly formed on the contrast ratio improvement layer. The contrast ratio improvement layer includes a first resin layer and a second resin layer facing the first resin layer. The second resin layer includes a pattern portion having optical patterns and a flat portion between the optical patterns, and the optical patterns have a base angle (θ) of 55 to 90°. The pattern portion satisfies equation 1, 1 < P/W <= 10, and the second resin layer is made of a composition for the second resin layer including at least one among a high refractive index hardening compound and a zirconium oxide. The high refractive index hardening compound includes a fluorene-based compound, a mixture of a thiol-based compound and a polyene-based compound, or a combination thereof.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical film for improving contrast ratio, a polarizing plate including the optical film, and a liquid crystal display device including the polarizing plate. [0002]

The present invention relates to an optical film for improving contrast ratio, a polarizing plate including the optical film, and a liquid crystal display including the same. More specifically, the present invention improves the front contrast ratio and the side contrast ratio, increases the viewing angle, and increases the hardness. Therefore, it is unnecessary to separately laminate the hard coating film. A polarizing plate including the optical film, and a liquid crystal display including the same.

A liquid crystal display device is operated by emitting light from a backlight unit through a liquid crystal panel. Since the light from the backlight unit is vertically incident on the screen of the liquid crystal display device, the contrast ratio (CR) of the front side of the screen of the liquid crystal display device is inevitably lowered. Therefore, development of a contrast ratio optical film that increases the side contrast ratio is proceeding.

Generally, the contrast ratio improving optical film improves the contrast ratio by the optical pattern. For example, the contrast ratio can be improved by the optical film in which the flat portion and the optical pattern are alternately formed. The optical pattern has an inclined surface. The incident light is refracted and diffused on the inclined surface to improve the contrast ratio, and the flat portion emits light reaching the flat portion, thereby diffusing light and maintaining the luminance. However, the side contrast ratio can be improved due to the optical pattern, but the front contrast ratio is generally decreased relatively.

On the other hand, the optical display device may not be continuously driven, but may be in a non-driven state. When the optical display device is in the non-driving state, the black light sensation may be caused by the light reflected by the external light and the screen quality may be deteriorated.

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

An object of the present invention is to provide an optical film with improved contrast ratio that can improve a front contrast ratio and a side contrast ratio.

Another object of the present invention is to provide a contrast ratio improving optical film capable of enlarging a side viewing angle.

Another object of the present invention is to provide an optical film with improved contrast ratio, which is high in hardness and does not need to laminate a hard coating film separately, and which can be thinned.

It is still another object of the present invention to provide an optical film with improved contrast ratio that can lower the minimum reflectance and improve the screen quality even in the non-driven state and enhance the black sensation.

It is still another object of the present invention to provide a polarizing plate comprising the optical film for improving the contrast ratio of the present invention.

It is still another object of the present invention to provide a liquid crystal display device including the polarizing plate of the present invention.

The optical film for improving contrast ratio of the present invention comprises a contrast ratio improving layer; And an antireflection layer and an antiglare layer formed directly on the contrast improvement layer, wherein the contrast ratio improvement layer includes a first resin layer and a second resin layer opposed to the first resin layer, 2 resin layer has an optical pattern and a pattern portion having a flat portion between the optical patterns, wherein the optical pattern has a base angle (?) Of 55 to 90, the pattern portion satisfies the following formula (1)

<Formula 1>

1 &lt; P / W &amp;le; 10

(Where P is the period (unit: μm) of the pattern portion,

W is the maximum width (unit: 占 퐉) of the optical pattern)

Wherein the second resin layer is formed of a composition for a second resin layer containing at least one of a high refractive index curable compound and a zirconium oxide, the high refractive index curable compound being a fluorene compound; A mixture of a thiol compound and a polyene compound; Or a combination thereof.

The polarizing plate of the present invention may include a polarizing film and the contrast improving layer 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 that can improve the front contrast ratio and side contrast ratio.

The present invention provides an optical film with improved contrast ratio capable of enlarging a lateral viewing angle.

The present invention provides a contrast-improving optical film which is high in hardness and does not need to laminate a hard coating film separately, and which can be thinned.

The present invention provides an optical film with improved contrast ratio that can be thinned because it is unnecessary to separately laminate a low reflection film having a low minimum reflectance.

The present invention provides an optical film with improved contrast ratio that can improve the screen quality and improve the black visual feeling even in the non-driven state by lowering the minimum reflectance.

The present invention provides a polarizing plate comprising the optical film for improving the contrast ratio of the present invention.

The present invention provides a liquid crystal display device including the polarizing plate 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 an optical film for improving contrast ratio according to another embodiment of the present invention.
3 is a cross-sectional view of a contrast ratio improving optical film according to another embodiment of the present invention.
4 is a cross-sectional view of a polarizer according to an embodiment of the present invention.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

The terms "upper" and "lower" in this specification are defined with reference to the drawings, wherein "upper" may be changed to "lower", "lower" What is referred to as "on" may include not only superposition, but also intervening other structures in the middle. On the other hand, what is referred to as "directly on "," directly above ", or "directly formed" or "directly contacting"

In the present specification, the terms "horizontal direction" and "vertical direction" mean the longitudinal direction and the unidirectional direction of the rectangular liquid crystal display screen, respectively. In the present specification, the terms "front" and "side" refer to the horizontal direction (φ, θ) by the spherical coordinate system, the front surface is (0 °, 0 °) (0 °, 90 °) and the right end point (0 °, 90 °), respectively.

As used herein, the term "top part " means the highest part of the optical pattern of the engraved.

As used herein, the term "aspect ratio" means the ratio of the maximum height to the maximum width of the optical pattern (maximum height / maximum width).

As used herein, the term "period" means a distance between neighboring optical patterns, for example, a sum of a maximum width of one optical pattern and a width of one flat portion.

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

<Formula A>

Re = (nx - ny) xd

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

As used herein, "(meth) acrylic" means acrylic and / or methacrylic.

As used herein, "hardness " means pencil hardness, unless otherwise noted.

Hereinafter, an optical film for improving contrast ratio according to an embodiment of the present invention will be described with reference to FIG. 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 contrast enhancing optical film 10 may include a contrast enhancing layer 100A and an antireflective layer 200. The antireflection layer 200 is formed directly on the contrast ratio improving layer 100A. The "directly formed" means that no other optical film, adhesive layer, adhesive layer, or the like is formed between the contrast enhancement layer 100A and the antireflection layer 200. [

Contrast ratio Improvement layer

The contrast enhancement layer 100A includes a first resin layer 110A and a second resin layer 120A opposed to the first resin layer 110A.

The second resin layer

The second resin layer 120A is directly formed on the first resin layer 110A and is formed on the light exit surface of the first resin layer 110A. The second resin layer 120A can increase the light diffusion effect by diffusing the light incident from the light exit surface of the first resin layer 110A.

The second resin layer 120A has a pattern portion having a flat portion 122 between at least one optical pattern 121 and immediately adjacent optical pattern 121. [ The optical pattern 121 may be an engraved optical pattern composed of at least one inclined surface 123 having a first surface 124 formed at the top and connected to the first surface 124. The second resin layer 120A is composed of a top surface 120Aa and a bottom surface 120Ab. The upper surface 120Aa of the second resin layer 120A is formed directly on the antireflection layer 200. [ The lower surface 120Ab of the second resin layer 120A corresponds to the pattern portion.

The pattern portion satisfies the following expression (1), and the optical pattern (121) can have a base angle (?) Of 55 to 90 degrees. The base angle? Means an angle formed by the inclined plane 123 of the optical pattern 121 and the line of the maximum width W of the optical pattern 121 to 55 to 90 degrees. Here, the inclined surface 123 refers to an inclined surface directly connected to the flat portion 122 of the optical pattern 121. In the above range, it is possible to simultaneously improve the front contrast ratio and the side contrast ratio, to reduce the difference between the front contrast ratio and the side contrast ratio, and to increase the contrast ratio on the same side viewing angle and the same front viewing angle. Specifically, Can be from 70 DEG to 90 DEG, and P / W (ratio of P to W) can be 1.2 to 8:

<Formula 1>

1 &lt; P / W &amp;le; 10

(In the above formula (1), P is the period (unit: mu m) of the pattern portion,

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

Fig. 1 shows the case where both base angles of the optical pattern are the same. However, optical patterns different in base angle may be included in the scope of the present invention if the base angle is included in the range of 55 [deg.] To 90 [deg.] Mentioned above.

The optical pattern 121 may be an engraved optical pattern composed of at least one inclined surface 123 having a first surface 124 formed at the top and connected to the first surface 124. 1, the optical pattern 121 shows a trapezoidal optical pattern in which two adjacent inclined surfaces 123 are connected by the first surface 124, but the present invention is not limited thereto. The optical pattern may be a rectangular or square optical pattern in addition to an optical pattern whose cross section is trapezoidal.

The first surface 124 is formed at the top, and the light reaching the second resin layer 120A in the optical display device is further diffused by the first surface 124, thereby increasing the viewing angle and brightness. Therefore, the light diffusion effect can be enhanced and the luminance loss can be minimized.

The first surface 124 may be a flat surface to facilitate the process of producing the contrast ratio improving optical film. However, the first surface 124 may be formed with fine irregularities or a curved surface. 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 slope is plane, and the cross-section is in a trapezoidal shape (for example, a cut-prism shape in which the top of a prism having a triangular cross section is cut) . However, when the engraved pattern is a cut-lenticular lens in which a first surface is formed at the top and a sloped surface is a curved surface (e.g., a cut-lenticular lens in which the top of the lenticular lens pattern is cut, A cut-micro lens) may be included in the scope of the present invention. It may also include a pattern in which the cross section is an N-square (N is an integer of 3 to 20) such as a rectangle or a square.

The first surface 124 is parallel to at least one of the flat portion 122, the lowest surface of the first resin layer 110A, and the top surface of the second resin layer 120A (i.e., the upper surface of the second resin layer) . 1 shows a case where the first surface 124 of the optical pattern 121, the flat portion 122, the minimum surface of the first resin layer 110A, and the top surface of the second resin layer 120A are parallel to each other will be.

The width A of the first surface 124 may be 0.5 탆 to 30 탆, specifically 1 탆 to 15 탆. In the above range, it can be used in an optical display device, and an effect of improving the contrast ratio can be expected.

The optical pattern 121 may have an aspect ratio (H1 / W) of 0.1 to 10, specifically 0.1 to 7.0, more specifically 0.1 to 5.0. In the above range, it is possible to improve the contrast ratio and the viewing angle at the side in the optical display device.

The maximum height H1 of the optical pattern 121 may be 20 占 퐉 or less, specifically 15 占 퐉 or less, more specifically, 10 占 퐉 or less. In the above range, the improvement of the contrast ratio, the improvement of the viewing angle, and the improvement of the luminance are shown, and the moire and the like may not appear.

The maximum width W of the optical pattern 121 may be 20 占 퐉 or less, specifically 15 占 퐉 or less, more specifically, 10 占 퐉 or less. In the above range, the improvement of the contrast ratio, the improvement of the viewing angle, and the improvement of the luminance are shown, and the moire and the like may not appear.

1 shows a pattern portion in which neighboring optical patterns have a base angle, a width of a first surface, a maximum height, and a maximum width, respectively. However, neighboring optical patterns may have different base angles, widths of first side, maximum height, and maximum width, respectively.

The flat portion 122 can increase the front luminance by emitting the light that has passed through the first resin layer 110A to the second resin layer 120A.

The ratio (W / L) of the maximum width W of the optical pattern 121 to the width L of the flat portion 122 may be 9 or less, specifically 0.1 to 3, more specifically 0.15 to 2 . 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 in the same side viewing angle and the same front viewing angle. In addition, there may be a moire preventing effect. The width L of the flat portion 122 may be 1 占 퐉 to 50 占 퐉, specifically, 1 占 퐉 to 20 占 퐉. In the above range, the front luminance may be increased.

The maximum width W of one optical pattern 121 and the immediately adjacent flat portion 122 form one period P. The period P may be 1 탆 to 50 탆, specifically 1 탆 to 40 탆. Moire can be prevented while the contrast ratio is improved within the above range.

FIG. 1 shows a pattern unit having the same neighboring period, but the periods may be different from each other, or at least one of neighboring periods may have a different cycle.

The maximum thickness of the second resin layer 120A may be 50 mu m or less, for example, 30 mu m or less. In this range, it is possible to prevent the occurrence of warpage such as curl.

The maximum height of the second resin layer 120A-the maximum height of the optical pattern 121 (also referred to as a "thickness") may be 30 μm or less, for example, 20 μm or less and 10 μm or less. In the above range, it is possible to minimize the side contrast ratio reduction.

Fig. 1 shows a case where the optical pattern is an engraved pattern. However, the optical pattern may be a relief pattern.

Although not shown in Fig. 1, Fig. 1 shows that the optical pattern is formed in an elongated form of a stripe shape in the longitudinal direction, but the optical pattern may be formed in a dot shape. The "dot" means that the combination of the fill pattern and the optical pattern is dispersed. Preferably, the optical pattern is elongated in a stripe shape to produce a right-and-left viewing angle enlarging effect.

The refractive index of the second resin layer 120A is higher than that of the first resin layer 110A. Accordingly, the contrast ratio improving layer 100A can improve the side contrast ratio by diffusing and emitting the light incident from the light incident surface of the first resin layer 110A, minimizing reduction of the front contrast ratio even if 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 in the same side view angle and the same front view angle.

The absolute value of the refractive index difference between the second resin layer 120A and the first resin layer 110A (the refractive index of the second resin layer-the refractive index of the first resin layer) is 0.05 to 0.30, specifically 0.05 to 0.20, 0.10 to 0.20. In this range, the effect of improving the diffusion of light and the contrast ratio may be large. In particular, the contrast ratio improving layer having a refractive index difference of 0.10 to 0.20 has an excellent polarizing diffusing effect in an optical display device, so that the contrast ratio can be increased even at the same viewing angle.

The refractive index of the second resin layer 120A may be 1.50 or more, specifically 1.55 to 1.70. Within this range, the light diffusion effect can be excellent.

The second resin layer 120A may be formed of a composition for a second resin layer containing at least one of a high refractive index curable compound, zirconium oxide (zirconia). The high refractive index curable compound is a fluorene compound; A mixture of a thiol compound and a polyene compound; Or a combination thereof.

The composition for the second resin layer may further comprise a UV curable compound. Preferably, the UV curable compound may comprise urethane (meth) acrylate.

The composition for the second resin layer may further comprise a polyisocyanate.

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

Contrast Improvement The optical film 10 includes at least one of a high refractive index curable compound and a zirconium oxide in the second resin layer 120A to secure the hardness property so that no additional hard coat layer coating or lamination is required and a viewing angle, And the side contrast ratio can be improved at the same time. By directly forming the antireflection layer 200 on the second resin layer 120A having such hardness and high refractive index properties, the lowest reflectance can be remarkably lowered, and the viewing angle, contrast ratio, hardness, Is possible.

The contrast ratio improvement optical film 10 can have a pencil hardness of not less than 1H, for example, 2H to 3H, measured in the antireflection layer 200. [ In this range, it can be used in the outer part of the optical display device without the hard coating layer, the protective film / protective layer.

Also, since the antireflection layer 200 is formed on the second resin layer 120A, the lowest reflectance of the optical film for improving the contrast ratio is lowered to prevent visibility of stains and the like even in the non-driving state of the optical display device, can do. Specifically, the minimum reflectance of the optical film for improving the contrast ratio may be 0.7% or less, for example, 0.6% or less, for example, 0.5% or less, for example, 0.4% or less. In the above range, the effect of improving the black visual feeling can be recognized when the optical display device is not driven. In the present specification, "black tactile sensation" refers to the degree of blackness of the screen without the occurrence of unevenness due to external light when the optical display device is not driven.

In one embodiment, the composition for the second resin layer comprises a fluorene compound as a high refractive index curable compound, and may include a UV curable compound and an initiator.

The high refractive index curable compound may further include a curable compound having an aromatic group as a non-fluorene base. Preferably, a mixture of a fluorene compound and a curing compound having an aromatic group as a non-fluorene compound may be included. As the fluorene compound, the compound of the following formula (1) may have a refractive index of 1.6 or more, specifically 1.615 to 1.635, more specifically 1.62 to 1.63. In the above range, the refractive index of the second resin layer can be increased, and the viewing angle and contrast ratio can be improved by the difference in refractive index between the first resin layer and the first resin layer. In addition, the lowest reflectance of the entire contrast ratio improving film can be lowered.

In one embodiment, the fluorene-based compound may comprise a compound of formula (1) Therefore, the refractive index of the second resin layer can be increased:

&Lt; Formula 1 >

(Wherein m and n are each an integer of 1 or more, m + n is an integer of 2 to 8, and R is hydrogen or a methyl group). Preferably, m + n may be four.

The curable compound having an aromatic group as the non-fluorene system can lower the viscosity of the second resin layer and improve the coating property and increase the refractive index of the second resin layer. The refractive index of the curable compound having an aromatic group as the non-fluorene group may be 1.55 or more, specifically 1.56 to 1.59, more specifically, 1.57 to 1.58.

In one embodiment, the curable compound having an aromatic group as the non-fluorene system may be a biphenyl-based compound, and may include, for example, a compound of the following formula:

(2)

(Wherein n is an integer of 1 to 4, and R is hydrogen or a methyl group).

The compounds of formulas (1) and (2) may be synthesized by conventional methods known to those skilled in the art, or commercially available products may be used.

A mixture of a high refractive index curable compound, that is, a fluorene compound or a mixture of a fluorene compound and a curing compound having an aromatic group as a non-fluorene group may be contained in an amount of 5 to 75 wt% based on the solid content in the composition for the second resin layer . In this range, the refractive index of the second resin layer can be increased, the hardness can be increased, and the lowest reflectance can be lowered compared to the first resin layer. Preferably, the high refractive index curable compound may comprise from 5 wt% to 65 wt%, from 5 wt% to 60 wt%, and from 10 wt% to 65 wt%.

The UV curable compound is different from the high refractive index curable compound and has a lower refractive index than the high refractive index curable compound, but forms a matrix of the second resin layer.

The UV curable compound may be preferably a compound having a UV curable group such as a (meth) acrylate group or an epoxy group. The UV curable compound may include at least one of a bifunctional or higher polyfunctional (meth) acrylate-based monomer, an oligomer formed therefrom, and a resin formed therefrom. For example, the UV curable compound may be a bifunctional to 10-functional (meth) acrylate compound.

The UV curable compound is a polyfunctional urethane (meth) acrylate synthesized from a polyfunctional (meth) acrylate such as a polyhydric alcohol and an ester of (meth) acrylic acid, or a polyhydric alcohol, an isocyanate compound, or a hydroxy ester of (meth) Acrylate. &Lt; / RTI &gt; Preferably, by using a polyfunctional urethane (meth) acrylate, the refractive index and the hardness can be further increased in combination with the fluorene compound.

Examples of the bifunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (Meth) acrylate, nonane diol di (meth) acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di Acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tripropylene glycol di ) Acrylate, and di (meth) acrylate such as hydroxypivalic acid neopentyl glycol di (meth) acrylate.

Examples of trifunctional or more (meth) acrylate compounds include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) Tri (meth) acrylate such as tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate and glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (Meth) acrylate compounds such as ditrimethylolpropane tri (meth) acrylate and ditrimethylolpropane tri (meth) acrylate, and trifunctional (meth) acrylate compounds such as pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (Meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, (Meth) acrylate compounds such as dipentaerythritol hexa (meth) acrylate and ditrimethylol propane hexa (meth) acrylate, and polyfunctional (meth) acrylate compounds having a part of these (meth) And a polyfunctional (meth) acrylate compound substituted with a lactone.

A polyfunctional urethane (meth) acrylate is preferably used because it is possible to design a desired molecular weight and molecular structure among the UV curable compounds and to easily balance the physical properties of the second resin layer to be formed .

The polyfunctional urethane (meth) acrylate is synthesized from a polyol, an isocyanate compound, and a hydroxy ester of (meth) acrylic acid. The polyol may include at least one of an aromatic polyol, an aliphatic polyol, and an alicyclic polyol. Preferably, it may be at least one of an aliphatic polyol and an alicyclic polyol. In such a case, the occurrence of yellowing of the antireflection film may be small. The polyol may include, but is not limited to, one or more of a polyester diol, a polycarbonate diol, a polyolefin diol, a polyether diol, a polythioether diol, a polysiloxane diol, a polyacetal diol, and a polyester amide diol. The isocyanate compound may be any aliphatic, alicyclic or aromatic polyfunctional isocyanate compound.

The UV curable compound may be contained in an amount of 20% by weight to 90% by weight based on solids in the composition for the second resin layer. In the above range, the mechanical strength of the contrast improving layer may be good. Preferably, the UV curable compound may comprise from 20 wt% to 60 wt%, and from 35 wt% to 50 wt%.

The initiator can cure the high refractive index curable compound, UV curable compound to form the second resin layer. The initiator may include one or more of conventional photoradical initiators, photo cationic initiators known to those skilled in the art. Although not particularly limited, an initiator having an absorption wavelength of 400 nm or less can be used. The photoradical initiator is a catalyst which generates radicals by light irradiation to catalyze curing and includes at least one of phosphorous, triazine, acetophenone, benzophenone, thioxanthone, benzoin, oxime, and phenylketone can do. Photo cationic initiators may include salts of cations and anions. Specific examples of the cation include diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl) iodonium, (4-methylphenyl) Triarylsulfonium such as triphenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium and the like, bis [4- (diphenylsulfonyl) phenyl] (Diphenylsulfonyl) -phenyl] sulfide, bis [4- (di (4- (2-hydroxyethyl) phenyl) Dien-1-yl) [(1,2,3,4,5,6-η) - (1-methylethyl) benzene] iron (1+). Specific examples of the anion include tetrafluoroborate (BF ₄ ^- ), hexafluorophosphate (PF ₆ ^- ), hexafluoroantimonate (SbF ₆ ^- ), hexafluoroarsenate (AsF ₆ ^- And chlorantimonate (SbCl ₆ ^- ).

The initiator may be contained in an amount of 2% by weight to 5% by weight based on the solid content in the composition for the second resin layer. Within the above range, the composition for the second resin layer can be sufficiently cured and the light transmittance of the contrast improvement layer can be prevented from being lowered with the remaining amount of initiator. Preferably, the initiator may comprise from 2% to 4% by weight.

The composition for the second resin layer may further include conventional additives known to those skilled in the art. The additives may include, but are not limited to, leveling agents, surface modifiers, antioxidants, defoamers, ultraviolet absorbers, light stabilizers, and the like. The additive may be contained in an amount of 0.05 part by weight to 1 part by weight, preferably 0.1 part by weight to 1 part by weight based on 100 parts by weight of the high refractive index curable compound, the UV curable compound and the initiator based on the solid content in the composition for the second resin layer. Within this range, additive effects can be achieved without affecting the effect of the high refractive index curable compound.

The composition for the second resin layer may further include a solvent to improve the coating property. The solvent may include at least one of propylene glycol monomethyl ether, methyl ethyl ketone, and methyl isobutyl ketone.

In another embodiment, the composition for the second resin layer comprises zirconium oxide; UV curable compounds; And an initiator.

The composition for the second resin layer may further include the above-mentioned additives and solvents. UV curable compounds and initiators are as described above.

The zirconium oxide may have an average particle diameter (D50) of 1 nm to 50 nm, specifically 5 nm to 20 nm. Within the above range, there may be an effect of increasing the hardness without deterioration of optical properties of the second resin layer. The shape of the zirconium oxide is not limited, but may be spherical, amorphous, plate-like, or the like. As the zirconium oxide, a surface-treated zirconium oxide may be used, but the surface treatment with a (meth) acrylate group or the like can strengthen the bond with the UV curable compound. The "average particle diameter (D50)" can be measured by a conventional method known to a person skilled in the art.

The composition for the second resin layer may contain 5 wt% to 75 wt% of zirconium oxide, 20 wt% to 90 wt% of UV curable compound, and 2 wt% to 5 wt% of initiator based on the solid content. In the above range, it is possible to secure the hardness, improve the contrast ratio, and improve the side contrast ratio.

In another embodiment, the composition for the second resin layer comprises a mixture of a thiol compound and a polyene compound as a high refractive index curable compound, and may further comprise a zirconium oxide and an initiator. The zirconium oxide can increase the hardness of the cured product of the thiol compound and the polyene compound.

The composition for the second resin layer may further comprise a polyisocyanate. The composition for the second resin layer may further include the above-mentioned additives and solvents. The zirconium oxide and the initiator are as described above.

The thiol compound may be included together with the polyene compound to increase the refractive index of the second resin layer and increase the curing rate of the composition for the second resin layer. The thiol compound may include at least one of pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), and 1,2-ethanedithiol. The polyene compound may include at least one of 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione and pentaerythritol tetraacrylate.

The polyisocyanate may comprise at least one of xylene diisocyanate, isophorone diisocyanate. Preferably, it may include isophorone diisocyanate.

In one embodiment, the composition for the second resin layer comprises 5 to 50% by weight of a thiol compound, 5 to 50% by weight of a polyene compound, 5 to 75% by weight of a zirconium oxide, 1 to 75% % To 5% by weight. Within this range, the refractive index of the second resin layer can be increased, the curing rate of the composition for the second resin layer can be increased, and the hardness can be increased. Preferably, the composition for the second resin layer contains 10 to 50% by weight of a thiol compound, 10 to 50% by weight of a polyene compound, 5 to 75% by weight of a zirconium oxide, 2% To 4% by weight. More preferably, the thiol compound may be contained in the composition for the second resin layer in an amount of 5% by weight to 20% by weight, most preferably 10% by weight to 15% by weight. More preferably, the polyene compound may be included in the composition for the second resin layer in an amount of 5% by weight to 20% by weight, and most preferably 10% by weight to 15% by weight. Within this range, the refractive index of the second resin layer can be increased, the curing rate of the composition for the second resin layer can be increased, and the hardness can be increased.

In another embodiment, the composition for the second resin layer comprises 5 to 50% by weight of a thiol compound, 5 to 50% by weight of a polyene compound, 5 to 75% by weight of a zirconium oxide, 5 to 75% by weight of a polyisocyanate 5 % To 25 wt%, and 1 wt% to 5 wt% of an initiator. Within this range, the refractive index of the second resin layer can be increased, the curing rate of the composition for the second resin layer can be increased, and the hardness can be increased. Preferably, the composition for the second resin layer contains 10 to 50% by weight of a thiol compound, 10 to 50% by weight of a polyene compound, 5 to 75% by weight of a zirconium oxide, 10% by weight of a polyisocyanate, To 15% by weight of the initiator, and 2% to 4% by weight of the initiator. More preferably, the thiol compound may be contained in the composition for the second resin layer in an amount of 5% by weight to 20% by weight, most preferably 10% by weight to 15% by weight. More preferably, the polyene compound may be included in the composition for the second resin layer in an amount of 5% by weight to 20% by weight, and most preferably 10% by weight to 15% by weight.

The first resin layer

The first resin layer 110A can diffuse the light by refracting the light incident from the lower surface in the optical display device in various directions according to the incident position and emitting the light. The first resin layer 110A is formed directly in contact with the second resin layer 120A.

The first resin layer 110A may include a filling pattern 111 filling at least a part of the optical pattern 121. [ The "filling at least a part" includes both cases where the optical pattern is completely filled or partially filled. When the filling pattern partially fills the optical pattern, the remaining portion may be filled with air or a resin having a predetermined refractive index. Specifically, the resin may have a refractive index equal to or larger than that of the first resin layer and equal to or smaller than that of the second resin layer.

The first resin layer 110A may be a layer including the filling pattern 111. [ The refractive index of the first resin layer 110A may be less than 1.52, specifically 1.35 or more and less than 1.50. In the above range, the light diffusion effect is large, the production can be facilitated, and the light diffusion of polarized light and the effect of improving the contrast ratio can be large.

In one embodiment, the first resin layer 110A may be formed of a composition for a first resin layer including a UV curable compound, an initiator. Accordingly, as described above, the contrast ratio improving optical film 10 may include a second resin layer 120A and a first resin layer 110A, thereby increasing the hardness. The UV curable compound and the initiator are as described in the composition for the second resin layer. The composition for the first resin layer may further include the additive described in the composition for the second resin layer.

In another embodiment, the first resin layer 110A may be formed of a composition for the first resin layer including a UV curable compound (non-fluorine UV curable compound containing no fluorine), an initiator, and a fluorine-containing UV curable compound . The fluorine-containing UV curable compound can lower the refractive index of the first resin layer 110A, and can exhibit antifouling property and releasability increasing effect.

Preferably, the composition for the first resin layer may include a (meth) acrylate multifunctional as the UV curable compound. As a result, hardness improvement and chemical resistance effect can be obtained.

For example, the composition for the first resin layer may contain 15 wt% to 90 wt%, for example, 15 wt% to 50 wt% of a fluorine-containing UV curable compound, 5 wt% of a fluorine-free UV curable compound, To 80 wt%, for example 5 wt% to 50 wt%, an initiator 1 wt% to 5 wt%, and an additive 0.1 wt% to 4 wt%. Within this range, there may be an effect of improving mold releasability and chemical resistance in the pattern mold.

The contrast improvement layer 100A may have a thickness of 10 mu m to 100 mu m, specifically 10 mu m to 50 mu m, and more specifically 10 mu m to 40 mu m. In the above range, it can be used in an optical display device.

The contrast enhancement layer may be prepared by conventional methods known to those skilled in the art. For example, the contrast ratio improving layer may be formed by coating a release film or a protective layer with a composition for a first resin layer, applying an optical pattern and a flat portion and curing the first resin layer, applying the resin for the second resin layer But it is not limited thereto.

Antireflection layer

The antireflection layer 200 is formed directly on the contrast ratio improving layer 100A. The contrast ratio improving optical film can remarkably lower the lowest reflectance of the optical film for improving the contrast ratio by stacking the second resin layer 120A and the antireflection layer 200. [

The antireflection layer 200 has a lower refractive index than the second resin layer 120A. The refractive index of the antireflection layer may be 1.35 or less. But the refractive index is not limited to the above range, and the lower the refractive index, the lower the reflectance can be. For example, the antireflection layer 200 may have a refractive index of 1.25 to 1.35.

The antireflection layer 200 may have a thickness of 500 nm or less, for example, 200 nm or less and 150 nm or less. In the above range, it can be used for antireflection purposes on the contrast improving optical film.

The antireflection layer 200 may be formed by coating a composition for an antireflection layer on the contrast ratio improving layer 100A and curing the composition. The composition for an antireflection layer may include inorganic particles, a fluorine-containing monomer or oligomer thereof, a fluorine-free monomer or oligomer thereof, an initiator, and a fluorine-containing additive.

The inorganic particles have a hollow structure, and the refractive index of the antireflection layer can be lowered by lowering the refractive index. The refractive index of the inorganic particles may be 1.4 or less, for example, 1.2 to 1.38. The inorganic particles have shapes such as spherical, amorphous, and plate-like shapes, and hollow silica can be used. The inorganic particles may be untreated untreated hollow particles or surface treated with UV curable functional groups. The average particle diameter (D50) of the inorganic particles is equal to or less than the thickness of the antireflection layer, and may be 30 nm to 150 nm, for example, 50 nm to 100 nm. In the above range, it can be included in the antireflection layer, and optical properties such as haze and transmittance can be improved. The inorganic particles may be contained in an amount of 20 to 70% by weight, for example, 40 to 60% by weight of the antireflection layer. Within the above range, it is possible to have scratch resistance and have the lowest reflectance lowering effect.

The fluorine-containing monomer or oligomer thereof together with the inorganic particles lowers the refractive index of the antireflection layer and forms a matrix of the antireflection layer together with the fluorine-free monomer or oligomer thereof. The fluorine-containing monomer may include a fluorine-containing (meth) acrylate-based compound. The fluorine-containing monomers may comprise conventional compounds known to those skilled in the art. For example, the fluorine-containing monomer or oligomer thereof may be bifunctional or hexafunctional and may include a fluorine-containing urethane acrylate or oligomer thereof. Thus, the antireflection layer may have an antifouling property and scratch resistance effect.

The fluorine-free monomer or oligomer thereof forms a matrix of the antireflection layer and may comprise the UV curable compound. The fluorine-free monomer or oligomer thereof may be a bifunctional or more functional, e.g., bifunctional to 10-functional (meth) acrylate compound, and these may be included singly or in combination of two or more. Specifically, the fluorine-free monomer may include a polyfunctional (meth) acrylate such as the above-described polyhydric alcohol and an ester of (meth) acrylic acid.

The initiator may be the same as or different from those described above in the composition for the second resin layer.

The additive adds antifouling property and slimness to the antireflection layer, and conventional additives known to those skilled in the art can be used. The additive may include at least one of a fluorine-containing additive and a silicon-based additive. The fluorine-containing additive may be a UV-curable fluorinated acrylic compound. For example, a KY-1200 series (KY-1203) including KY-1203 can be used.

The composition for an antireflection layer comprises 20 wt% to 70 wt% of solid inorganic particles, 10 wt% to 50 wt% of a fluorine containing monomer or oligomer thereof, 5 wt% to 25 wt% of a fluorine-free monomer or oligomer thereof, 2 wt% To 5 wt%, and 1 wt% to 10 wt% of an additive. Within the above range, it is possible to have scratch resistance and have the lowest reflectance lowering effect. Preferably, the composition for antireflection layer comprises 40 to 60% by weight of inorganic particles based on solids, 20 to 40% by weight of fluorine-containing monomer or oligomer thereof, 5 to 15% by weight of fluorine-free monomer or oligomer thereof, From 2 wt% to 4 wt% of an initiator, and from 2 wt% to 7 wt% of an additive.

The composition for the antireflection layer may further include conventional additives known to those skilled in the art. For example, it may include, but is not limited to, antifoaming agents, antioxidants, ultraviolet absorbers, light stabilizers, leveling agents and the like. The composition for the antireflection layer may further include a solvent to improve the coating property. The solvent may include at least one of methyl ethyl ketone, methyl isobutyl ketone, and ethylene glycol dimethyl ether.

1 shows a case where the antireflection layer 200 is a single layer. However, the antireflection layer 200 may be two or more layers, and in this case, it may include a laminate of a high refractive index layer and a low refractive index layer.

1 shows a case where the refractive index of the second resin layer 120A is higher than that of the first resin layer 110A. However, a case where the refractive index of the second resin layer 120A is lower than that of the first resin layer 110A may be included in the scope of the present invention. At this time, the refractive index of the second resin layer 120A may be less than 1.52, specifically 1.35 or more and less than 1.50, and the refractive index of the first resin layer 110A may be 1.50 or more, specifically 1.55 to 1.70. Within this range, the light diffusion effect can be excellent. In the above range, the side contrast ratio improvement effect can be obtained. In this case, the second resin layer may be formed of a composition including the above-described UV curable compound, initiator. The first resin layer may be formed of a composition including the high refractive index curable compound, UV curable compound, and initiator.

1 shows a case where the antireflection layer 200 is directly formed on the contrast ratio improving layer 100A. However, a case where a high refractive index layer is further formed between the contrast enhancement layer 100A and the antireflection layer 200 may be included in the scope of the present invention. The high-refraction layer may be formed directly on the contrast-enhancement layer 100 (A) and the antireflection layer 200, respectively. The high refractive index layer has a higher refractive index than the antireflection layer (200). Therefore, the lowest reflectance of the optical film having improved contrast ratio can be further lowered. The high refractive index layer may have a refractive index of 1.60 or more, for example, 1.60 to 1.73. The high refractive index layer may have a thickness of 300 nm or less, for example, 250 nm or less. In the above range, it can be used for an optical film for improving the contrast ratio.

The high-refraction layer may be any of the UV curable compounds described above; Zirconium oxide, and antimony oxide; And a composition for a high-refraction layer comprising the initiator. The zirconium oxide can increase the refractive index of the high-refractive-index layer and impart the function of increasing the hardness of the high-refractive-index layer. The zirconium oxide may not be surface-treated, but it may be surface-treated to improve compatibility and further increase the hardness of the high-refraction layer. The antimony oxide can increase the refractive index of the high-refractive-index layer, increase the hardness of the high-refractive-index layer, and provide antistatic effect. Zirconium oxide and antimony oxide may have an average particle diameter (D50) of 1 nm to 300 nm, specifically 5 nm to 50 nm. Within the above range, the antireflection film may have an effect of increasing hardness without deterioration of optical properties. The composition for a high-refractive-index layer may further comprise the additive.

The high refractive index layer can be formed by coating a composition for a high refractive index layer with a predetermined thickness on the contrast ratio improving layer and curing the composition. The antireflection layer may be formed by coating a high refractive index layer with a composition for an antireflection layer to a predetermined thickness and curing the composition.

Although not shown in FIG. 1, a protective layer may be further formed on the lower surface of the contrast enhancement layer 100A. The protective layer can support the optical film for improving the contrast ratio. Or the protective layer may be a protective layer of the polarizing film of the polarizing plate described below. The protective layer is as described above.

Hereinafter, an optical film for improving contrast ratio according to another embodiment of the present invention will be described with reference to FIG. 2 is a cross-sectional view of an optical film for improving contrast ratio according to another embodiment of the present invention.

2, the contrast ratio improving optical film 20 has a contrast ratio improving effect according to an embodiment of the present invention, except that the antiglare layer 300 is formed instead of the antireflection layer 200 on the contrast ratio improving layer 100A. Is substantially the same as the optical film (10). Since the antiglare layer 300 is formed instead of the antireflection layer 200, the minimum reflectance of the optical film having the contrast ratio can be relatively increased, but the effect of preventing fingerprints may be further increased. In addition, the second resin layer 120A can be imparted with flame retardancy at the same time, and in such a case, the additional antiglare layer 300 can be omitted.

The antiglare layer 300 may have a thickness of 30 mu m or less, for example, 20 mu m or less and 10 mu m or less. In the above range, it can be used for an optical film for improving the contrast ratio.

The antiglare layer 300 may be formed by coating the antiglare layer composition on the contrast ratio improving layer 100A and curing the composition.

The composition for the antiglare layer may comprise a UV curable compound, fine particles, and an initiator. The UV curable compound may include the UV curable compound described above in the composition for the second resin layer. The initiator may include the above-described initiator in the composition for the second resin layer. The UV curable compound may be contained in the composition for an antiglare layer in an amount of 50% by weight to 95% by weight, preferably 60% by weight to 90% by weight, based on solids. Within the above range, the mechanical strength of the antiglare layer can be increased and an antiglare effect can be obtained. The initiator may be contained in the composition for the antiglare layer in an amount of 1 wt% to 10 wt%, preferably 1 wt% to 5 wt%, and preferably 1 wt% to 3 wt% based on solids. Within the above range, the composition for the antiglare layer can be sufficiently cured, and the permeability as the remaining amount of the initiator can be prevented from being lowered.

The fine particles are for imparting an antiglare effect and may include organic fine particles. The organic fine particles may be formed of at least one of a (meth) acrylic resin, a styrene or styrene derivative resin, a polyester resin, and an olefin resin. Preferably, the organic fine particles may be formed of a crosslinked resin. The fine particles may have an average particle diameter (D50) of 20 mu m or less, for example, 10 mu m or less. In the above range, it may be included in the antiglare layer, and there may be no image degradation problem when used in an optical display device. The refractive index of the fine particles may be 1.50 or more, for example, 1.50 to 1.70. Within this range, an antiglare effect can be obtained. The fine particles may be contained in the composition for an anti-glare layer in an amount of 1 to 10% by weight, preferably 2 to 7% by weight, based on solids. Within this range, an antiglare effect can be obtained.

The composition for the antiglare layer may further include conventional additives known to those skilled in the art. For example, it may include, but is not limited to, antifoaming agents, antioxidants, ultraviolet absorbers, light stabilizers, leveling agents and the like. The composition for the antiglare layer may further include a solvent to improve the coating property. The solvent may include at least one of methyl ethyl ketone, methyl isobutyl ketone, and ethylene glycol dimethyl ether. The additive may be contained in the composition for the antiglare layer in an amount of 0.01 to 30% by weight, preferably 0.1 to 15% by weight, based on the solids content. In the above range, the additive effect can be obtained without affecting the antiglare effect.

2 shows a case where the antiglare layer 300 is directly formed on the contrast ratio improving layer 100A. However, a case where the high refractive index layer described above is further formed between the contrast improving layer 100A and the antiglare layer 300 may be included in the scope of the present invention.

Hereinafter, a contrast ratio improving optical film according to another embodiment of the present invention will be described with reference to FIG. 3 is a cross-sectional view of a contrast ratio improving optical film according to another embodiment of the present invention.

3, the contrast improving optical film 30 may be formed by a method similar to that of the first embodiment of the present invention, except that the antiglare layer 300 of FIG. 2 is further formed between the contrast ratio improving layer 100A and the antireflection layer 200. FIG. Is substantially the same as the contrast improving optical film 10 according to the example. The antiglare layer 300 is formed directly on the contrast ratio improving layer 100A and the antireflection layer 200, respectively. The antiglare layer and the antireflection layer are sequentially formed on the contrast improvement layer so that the antiglare property and antireflection effect can be obtained.

3 shows a case where the antiglare layer 300 and the antireflection layer 200 are sequentially formed on the contrast ratio improving layer 100A. However, the case where a high refractive index layer for lowering the total reflectance is further formed between the antiglare layer 300 and the antireflection layer 200 and the antiglare layer, the high refractive index layer and the antireflection layer are sequentially formed on the contrast ratio improving layer, . The high-refraction layer is as described above.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG. 4 is a cross-sectional view of a polarizer according to an embodiment of the present invention.

Referring to FIG. 4, the polarizing plate 40 includes a polarizing film 400 and a contrast enhancing optical film, and the contrast enhancing optical film may include a contrast enhancing optical film according to an embodiment of the present invention. The contrast improving optical film 10 may be formed on the light output surface of the polarizing film 400. [ The contrast improving optical film 10 diffuses the polarized light transmitted through the polarizing film 400 to improve the front contrast ratio and the side contrast ratio, thereby improving the viewing angle. Further, since the hardness is high by including the first resin layer and the second resin layer, it is not necessary to laminate a separate hard coating film and a protective layer / protective film on the polarizing plate, thereby achieving a thinning effect. Further, by lowering the minimum reflectance by stacking the second resin layer and the antiglare layer / antireflection layer, it is possible to improve the appearance of black by increasing the black visual feeling even when the optical display device is not driven.

The polarizing film 400 can polarize the light incident from the liquid crystal panel and transmit the polarized light to the contrast improving layer 100A. The polarizing film 400 is formed on the light incidence surface of the contrast enhancing layer 100A.

The polarizing film 400 may include a polarizer. Specifically, the polarizer may include a polyvinyl alcohol polarizer produced by uniaxially stretching a polyvinyl alcohol film, or a polyene polarizer produced by dehydrating a polyvinyl alcohol film. The polarizer may have a thickness of 5 占 퐉 to 40 占 퐉. In the above range, it can be used in an optical display device.

The polarizing film 400 may include a polarizer and a protective layer formed on at least one side of the polarizer. The protective layer can protect the polarizer, thereby increasing the reliability of the polarizer and increasing the mechanical strength of the polarizer. The protective layer may comprise one or more of an optically transparent, protective film or protective coating layer.

When the protective layer is a protective film type, it may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding the resin. If necessary, a further stretching process may be added. The resin includes a cyclic polyolefin-based resin including a cellulose ester-based resin including triacetyl cellulose and the like, an amorphous cyclic olefin polymer (COP), a polycarbonate-based resin, polyethylene terephthalate Based resin, a polyacrylate-based resin including a polyamide-based resin, a polyimide-based resin, a non-cyclic-polyolefin-based resin, and a polymethylmethacrylate resin, A polyvinyl 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 phase difference film or an isotropic optical film having a predetermined range of retardation by stretching the resin by a predetermined method. In one embodiment, the protective film may have a Re of at least 8,000 nm, specifically at least 10,000 nm, more specifically at least 10,000 nm, more specifically from 10,100 nm to 15,000 nm. In this range, it is possible to prevent rainbow stains from being visible, and the diffusion effect of light diffused through the contrast ratio improvement layer can be made larger. In another embodiment, the protective film may be an isotropic optical film having a Re of 60 nm or less, specifically 0 nm to 60 nm, more specifically 40 nm to 60 nm. The viewing angle can be compensated in the above range to improve the image quality. The "isotropic optical film" means a film in which nx, ny, and nz are substantially the same, and the "substantially the same" includes not only completely identical cases but also cases including some errors.

The protective coating layer may be formed of an active energy ray-curable resin composition comprising 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 radically 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 radical polymerizable curable compound may be a (meth) acrylic compound having at least one (meth) acryloyloxy group in the molecule.

The epoxy compound may be at least one of a hydrogenated epoxy compound, a chained aliphatic epoxy compound, a cyclic aliphatic epoxy compound, and an aromatic epoxy compound.

Radical polymerizable curable compounds can provide a protective coating layer having excellent hardness and mechanical strength and high durability. The radical polymerizable curable compound can be obtained by reacting two or more (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule, a compound having a functional group and at least two (meth) acryloyloxy Examples of the (meth) acrylate monomer include monofunctional (meth) acrylate monomers having one (meth) acryloyloxy group in the molecule, two (meth) acrylate monomers having two (Meth) acrylate monomer having at least three (meth) acryloyloxy groups in the molecule, and a polyfunctional (meth) acrylate monomer having at least three (meth) acryloyloxy groups in the molecule. (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 Gwangyang ionic initiator may be any of those conventionally known to those skilled in the art. Specifically, the onium ion initiator can use an onium salt including a cation and an anion. Specifically, the cation is at least one selected from the group consisting of diphenyl iodonium, 4-methoxydiphenyl iodonium, bis (4-methylphenyl) iodonium, bis (4-tert- butylphenyl) iodonium, bis (dodecylphenyl) Triarylsulfonium such as diaryliodonium such as [(methylphenyl) [(4- (2-methylpropyl) phenyl) iodonium, triphenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium, 4- (diphenylsulfono) phenyl] sulfide, and the like. Specifically, the anion is phosphate (PF ₆ ^-) hexafluoropropane, borates (BF ₄ ^-) tetrafluoroborate, antimonate hexafluorophosphate (SbF ₆ ^-), are Senate hexafluorophosphate (AsF ₆ ^-), hexamethylene And chlorantimonate (SbCl ₆ ^- ). The photosensitizer may be any of those conventionally known to those skilled in the art. Specifically, the photosensitizer may be at least one selected from the group consisting of thioxanthone, phosphorus, triazine, acetophenone, benzophenone, benzoin, and oxime. The active energy ray curable resin composition may further include conventional additives such as silicone leveling agents, ultraviolet absorbers, and antistatic agents.

The thickness of the protective layer may be from 5 to 200 탆, specifically from 30 탆 to 120 탆, from 30 탆 to 100 탆 for the protective film type, and from 5 탆 to 50 탆 for the protective coating layer type. Can be used for the polarizer in the above range.

A surface treatment layer such as a primer layer, a hard coat layer, a translucent layer, an antireflection layer, an antiglare layer, a low reflection layer, and an ultra low reflection layer may be further formed on at least one surface of the protective layer. The primer layer can improve the adhesion between the polarizer and the protective layer. The hard coat layer, the translucent layer, the antireflection layer and the like can provide additional functions to the protective layer, the polarizing film and the like.

The polarizing plate can be formed by a conventional method. For example, the polarizing plate can be formed by forming a contrast ratio improving layer on one surface of a polarizing film, coating the composition for an antireflection layer on the contrast ratio improving layer, and then curing, but is not limited thereto.

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 can be included as a viewing side polarizing plate. The "viewer-side polarizing plate" is disposed opposite to the screen side, i.e., the light source side, with respect to the liquid crystal panel.

In one embodiment, the liquid crystal display device may include a backlight unit, a first polarizing plate, a liquid crystal panel, and a second polarizing plate sequentially laminated, and the second polarizing plate may include the polarizing plate of the present invention. The liquid crystal panel may employ a VA (vertical alignment) mode, an IPS mode, a PVA (patterned vertical alignment) mode, or an S-PVA (super-patterned vertical alignment) mode. In another embodiment, it may be included as a light source side polarizing plate for a liquid crystal panel. 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 with respect to the liquid crystal panel may include the polarizing plate of the present invention. Preferably, the polarizing plate of the present invention can be used as a visual side polarizing plate.

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

Manufacturing example  1: Preparation of composition for first resin layer

3 g of fluorine-based UV curable compound SFA-420 (Shinya T & C, fluoric oligomer), 9 g of UV curable compound HDDA (Entis, bifunctional acrylate), 0.5 g of initiator TPO (BASF) BYK Co.) were added and dissolved completely.

Manufacturing example  2: Preparation of composition for second resin layer

50 g of UV curable compound UP111 (Entis, polyfunctional urethane acrylate), 50 g of BPF-022S (enrichment solvent), which is a solution containing a mixture of the compound of Formula 1 and the compound of Formula 2, which is a high refractive index curing compound, Irgacure -184 (BASF) and 0.1 g of additive BYK-399 (BYK) were dissolved in 100 g of propylene glycol monomethyl ether (Samseon Chemical) and 100 g of methyl ethyl ketone (Samseon Chemical).

Manufacturing example  3: Preparation of composition for the second resin layer

30 g of UV curable compound UP111 (Entis, polyfunctional urethane acrylate), 80 g of zirconia particle dispersion SZK-330A (Ranco, ZrO2 sol), 3 g of Irgacure-184 (BASF) as an initiator, BYK-399 100 g of propylene glycol monomethyl ether (Samseon Chemical Co., Ltd.) and 100 g of methyl ethyl ketone (Samseon Chemical Co., Ltd.) were added and dissolved completely.

Manufacturing example  4: For antireflection layer  Composition manufacturing

2.75 g of a fluorine-free monomer M306 (TOAGOSEI) is added to 61.3 g of THRULYA 5320 (JGC Catalyst and chemicals, including hollow silica) and completely dissolved. 51.7 g of a fluorine-containing monomer SFA-420 (Shin-A T & C) was added thereto, followed by stirring for 5 minutes. Add 3.75 g of fluorine-based additive KY-1203 (Shinetsu) and stir for 5 minutes. 0.75 g of initiator Irgacure 127 (BASF) is added and completely dissolved. , 585 g of methyl ethyl ketone (Samcheon Chemical Co.) and 297 g of methyl isobutyl ketone (Samcheon Chemical Co.) were added and stirred for 30 minutes.

Manufacturing example  5: For Bangyeon layer  Composition manufacturing

100 g of UV curable compound PETIA (Entis), 10 g of organic fine particle-containing solution SX500H (Soken Co., average particle diameter: 5 탆, cross-linked polystyrene particles), 3.5 g of initiator Irgacure-184 (BASF), additive BYK- ), 80 g of solvent propylene glycol monomethyl ether (Samseon Chemical Co., Ltd.) and 60 g of methyl ethyl ketone (Samseon Chemical Co., Ltd.) were added and stirred.

Manufacturing example  6: Preparation of composition for second resin layer

3 g of UV curable compound UP111 (Entis, polyfunctional urethane acrylate), Irgacure-184 (BASF) as an initiator and 0.1 g of BYK-399 (BYK) as an additive were dissolved in propylene glycol monomethyl ether ), And 100 g of methyl ethyl ketone (Samseon Chemical Co., Ltd.) were added and dissolved completely.

Manufacturing example  7: Preparation of composition for second resin layer

57 g of pentaerythritol tetrakis (2-mercaptoacetate) (PETSA, MARUZEN CHEMICAL TRADING), 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione (TTT , 30 g of a mixture containing 43 g of BOC SCIENCES) and 1 g of an initiator TPO, 70 g of a zirconia particle dispersion (solid content 50%, in PGEMA (propylene glycol methyl ether acetate), Pixeligent) were mixed to prepare a composition for a second resin layer Respectively.

Manufacturing example  8: Preparation of composition for second resin layer

A composition for a second resin layer was prepared in the same manner as in Preparation Example 7, except that 50 g of the mixture and 50 g of the zirconia particle dispersion were mixed instead of 30 g of the mixture.

Manufacturing example  9: Preparation of composition for second resin layer

A composition for a second resin layer was prepared in the same manner as in Preparation Example 7, except that 70 g of the mixture and 30 g of the zirconia particle dispersion were mixed instead of 30 g of the mixture.

Manufacturing example  10: Preparation of composition for second resin layer

57 g of pentaerythritol tetrakis (2-mercaptoacetate) (PETSA, MARUZEN CHEMICAL TRADING), 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione (TTT , 30 g of a mixture containing 20 g of isophorone diisocyanate (IPDI) and 1 g of initiator TPO, and 70 g of a zirconia particle dispersion (solid content 50%, in PGEMA (propylene glycol methyl ether acetate, Pixeligent) Thereby preparing a composition for a second resin layer.

Manufacturing example  11: Preparation of composition for second resin layer

A composition for a second resin layer was prepared in the same manner as in Production Example 10 except that 50 g of the mixture and 30 g of the zirconia particle dispersion were mixed instead of 30 g of the mixture.

Manufacturing example  12: Preparation of composition for second resin layer

A composition for a second resin layer was prepared in the same manner as in Production Example 10, except that 70 g of the mixture and 70 g of the zirconia particle dispersion were mixed instead of 30 g of the mixture.

Example  One

The first resin layer composition of Preparation Example 1 was coated on one side of a triacetyl cellulose film (Fuji, TG60UL, thickness: 60 탆) as a protective layer, and a pattern portion was applied and cured to form a first resin layer. The composition for the second resin layer of Production Example 2 was coated on the first resin layer and cured to form a contrast ratio improving layer having the optical patterns shown in Table 1 below. The upper surface of the second resin layer is a flat surface.

The second resin layer as one side of the contrast ratio improving layer was coated with the antireflection layer composition of Preparation Example 4 and cured to prepare a contrast ratio improving optical film having an antireflection layer (thickness: 150 nm) formed thereon.

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 polarizer.

(Z-200, Nippon Goshei) was coated on the other side of the triacetylcellulose film in the contrast ratio improving optical film, and the polarizer was attached to the polarizing plate.

Example  2

In Example 1, the composition for the antiglare layer of Production Example 5 was coated and cured to prepare the antiglare layer (thickness: 8 占 퐉) in place of the antireflection layer composition in Production Example 4 to prepare a contrast ratio improving optical film. A polarizing plate was produced in the same manner as in Example 1.

Example  3

In Example 1, the composition for the antiglare layer of Production Example 5 was coated on the second resin layer on one side of the contrast ratio improvement layer and cured to form an antiglare layer (thickness: 8 탆). An anti-reflection layer (thickness: 150 nm) was formed on the anti-glare layer by coating the anti-reflection layer composition of Production Example 4 and curing the anti-reflection layer composition to prepare a contrast ratio improving optical film. A polarizing plate was produced in the same manner as in Example 1.

Example  4

A contrast ratio improving optical film and a polarizing plate were prepared in the same manner as in Example 2, except that the composition for the second resin layer in Production Example 3 was used in place of the composition for the second resin layer in Production Example 2.

Example  5 - Example  10

The same procedure was followed as in Example 1 and Example 2 except that the composition for the second resin layer in Table 3 below was used in place of the composition for the second resin layer and the antiglare layer or antireflection layer in Table 3 was formed A contrast ratio improvement optical film and a polarizing plate were produced.

Comparative Example  One

A contrast ratio improving optical film and a polarizing plate were produced in the same manner as in Example 1, except that the composition for the second resin layer in Production Example 6 was used in place of the composition for the second resin layer in Production Example 2.

Comparative Example  2

A contrast ratio improving optical film and a polarizing plate were produced in the same manner as in Example 2 except that the composition for the second resin layer of Production Example 6 was used in place of the composition for the second resin layer of Production Example 2.

Comparative Example  3

A contrast ratio improving optical film and a polarizing plate were produced in the same manner as in Example 3, except that the composition for the second resin layer of Production Example 6 was used in place of the composition for the second resin layer in Production Example 2.

Comparative Example  4

In Example 1, a contrast ratio improving optical film and a polarizing plate were produced in the same manner, except that the antireflection layer of Production Example 4 was not formed.

Optical pattern shape Maximum optical pattern height (H1)
(탆) Maximum optical pattern width (W)
(탆) The width (A) of the first surface of the optical pattern,
(탆) Base of optical pattern
(°) The width of the flat part (L)
(탆) Cut-prism
(Trapezoid) 8 8 6 86 10

The pencil hardness and the lowest reflectance were evaluated with respect to the contrast ratio-improving optical films of Examples and Comparative Examples, and the results are shown in Tables 2, 3, and 4 below.

Pencil hardness

Measured using a HEIDON instrument and measured using a Mitsubishi pencil having a speed of 0.5 mm / sec, a weight of 500 g, and a hardness of 1H or 2H. After measuring each 5 times using a pencil of the corresponding hardness, if not scratching more than 3 times, the hardness of the pencil is evaluated by the hardness of the film. Pencil hardness was measured in the antireflection layer or the antiglare layer as the outermost layer of the contrast improvement film.

Lowest reflectance

Improvement of Contrast Ratio of Examples and Comparative Examples The CL-885 black acrylic sheet of Nitto resin having a refractive index of 1.46 to 1.50 was formed on the triacetyl cellulose film of the optical film, and the specimen was laminated at 70 DEG C, and a spectrophotometer (Light source: D65 light source, light source diameter: Φ25.4 mm, measurement angle of view: 2 °, 8 mm diameter mode) with SCI reflection mode (Konica Minolta Co., Ltd., CM3600A) at a wavelength of 320 nm to 800 nm. Respectively.

The front luminance, the contrast ratio, and the viewing angle were evaluated for the polarizing plates of Examples and Comparative Examples. The results are shown in Tables 2, 3 and 4.

A module for a liquid crystal display was manufactured and evaluated by the following method.

Preparation of first polarizing plate

The polyvinyl alcohol film was stretched three times at 60 DEG C, adsorbed to iodine, and then stretched 2.5 times in an aqueous boric acid solution at 40 DEG C to prepare a first polarizer. A triacetyl cellulose film (thickness: 80 占 퐉) was bonded to both surfaces of the first polarizer with a polarizer adhesive (Z-200, manufactured by Nippon Goshei) to prepare a first polarizer plate.

Manufacture of Module for Liquid Crystal Display

The first polarizing plate, the liquid crystal panel (PVA mode), and the polarizing plates prepared in the above-mentioned 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 with a viewer-side polarizing plate, and an antireflection film was disposed at the outermost side on the visual side.

A liquid crystal display device including a LED light source, a light guide plate, and a module for a liquid crystal display device and including a one-sided edge type LED light source (same configuration as the Samsung LED TV (UN32H5500) except for the configuration of the module for the liquid crystal display device of the embodiment and the comparative example ).

White mode and black mode in the spherical coordinate system front (0 °, 0 °) and side (0 °, 60 °) respectively using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM) 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 by 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 °).

In the white mode, the viewing angle representing the luminance corresponding to 1/2 or 1/3 of the front luminance was defined as 1/2 viewing angle or 1/3 viewing angle.

Example One 2 3 4 1st
Resin layer Furtherance Production Example 1 Production Example 1 Production Example 1 Production Example 1 Refractive index 1.45 1.45 1.45 1.45 Second
Resin layer Furtherance Production Example 2 Production Example 2 Production Example 2 Production Example 3 Refractive index 1.55 1.55 1.55 1.57 Antireflection layer Production Example 4 include Not included include Not included Anticyclone layer Production Example 5 Not included include include include Pencil hardness 2H 2H 2H 2H Low reflectance (%) 0.28 0.48 0.38 0.51 Front luminance (nit) 99 98 99 99 Contrast ratio (0 [deg.], 0 [deg.]) 96 94 95 97 (0 [deg.], 60 [deg.]) 110 106 108 111 Viewing angle 1/2 (°)
(Right and left) 95 95 94 97 1/3 (°)
(Right and left) 108 107 107 108

Example 5 6 7 8 9 10 1st
Resin layer Furtherance Production Example 1 Production Example 1 Production Example 1 Production Example 1 Production Example 1 Production Example 1 Refractive index 1.45 1.45 1.45 1.45 1.45 1.45 Second
Resin layer Furtherance Production Example 7 Production Example 8 Production Example 9 Production Example 10 Production Example 11 Production Example 12 Refractive index 1.620 1.595 1.570 1.612 1.587 1.562 Antireflection layer Production Example 4 include Without include Without include Without Anticyclone layer Production Example 5 Without include Without include Without include Pencil hardness 2H 2H 2H 2H 2H 2H Low reflectance (%) 0.62 0.47 0.38 0.68 0.30 0.68 Front luminance (nit) 97 99 98 96 98 99 Contrast ratio (0 [deg.], 0 [deg.]) 97 96 93 96 98 95 (0 [deg.], 60 [deg.]) 107 108 110 111 112 110 Viewing angle 1/2 (°)
(Right and left) 97 96 95 97 98 97 1/3 (°)
(Right and left) 107 108 106 106 109 107

Comparative Example One 2 3 4 1st
Resin layer Furtherance Production Example 1 Production Example 1 Production Example 1 Production Example 1 Refractive index 1.45 1.45 1.45 1.45 Second
Resin layer Furtherance Production Example 6 Production Example 6 Production Example 6 Production Example 2 Refractive index 1.51 1.51 1.51 1.55 Antireflection layer Production Example 4 include Not included include Not included Anticyclone layer Production Example 5 Not included include include Not included Pencil hardness 2H 2H 2H 2H Low reflectance (%) 0.36 0.81 0.4 0.8 Front luminance (nit) 98 97 97 98 Contrast ratio (0 [deg.], 0 [deg.]) 89 88 89 90 (0 [deg.], 60 [deg.]) 98 98 98 99 Viewing angle 1/2 (°)
(Right and left) 86 85 84 85 1/3 (°)
(Right and left) 98 99 97 99

As shown in Tables 2 and 3, the contrast ratio-improving optical films and polarizing plates of the present invention have high hardness, improved front contrast ratio and side contrast ratio, and low minimum reflectance. By lowering the minimum reflectance, it is possible to improve the screen quality and increase the black visual feeling even in the non-driving state.

On the other hand, among the second resin layers of the present invention, in Examples 1 to 4 which do not contain a high refractive index curable compound or zirconium oxide, hardness can be secured, but the effect of improving the front contrast ratio and side contrast ratio is weak and the lowest reflectance is relatively high .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (25)

A contrast enhancement layer; And an antireflection layer and an antiglare layer directly formed on the contrast ratio improvement layer,
Wherein the contrast enhancement layer includes a first resin layer and a second resin layer opposed to the first resin layer, the second resin layer has a pattern portion having an optical pattern and a flat portion between the optical patterns,
Wherein the optical pattern has a base angle &amp;thetas; of 55 DEG to 90 DEG, the pattern portion satisfies the following formula 1,
<Formula 1>
1 &lt; P / W &amp;le; 10
(Where P is the period (unit: μm) of the pattern portion,
W is the maximum width (unit: 占 퐉) of the optical pattern)
The second resin layer is formed of a composition for a second resin layer containing at least one of a high refractive index curable compound and a zirconium oxide,
The high refractive index curable compound is a fluorene compound; A mixture of a thiol compound and a polyene compound; Or a combination thereof.
The optical film of claim 1, wherein the contrast ratio improving optical film has a minimum reflectance of 0.7% or less as measured on at least one of the antireflection layer and the antiglare layer.
The optical film of claim 1, wherein the second resin layer has a higher refractive index than the first resin layer.
The optical film according to claim 1, wherein the fluorene compound comprises a compound represented by the following formula (1):
&Lt; Formula 1 >

(Wherein m and n are each an integer of 1 or more, m + n is an integer of 2 to 8, and R is hydrogen or a methyl group).
The optical film according to claim 1, wherein the high refractive index curable compound is the fluorene compound, and the high refractive index curable compound further comprises a biphenyl compound.
The optical film according to claim 5, wherein the composition for the second resin layer further comprises a UV curable compound and an initiator.
7. The optical film according to claim 6, wherein the UV curable compound comprises a polyfunctional urethane (meth) acrylate.
The optical film according to claim 1, wherein the composition for the second resin layer comprises the zirconium oxide, a UV curable compound, and an initiator.
The optical film according to claim 8, wherein the UV curable compound comprises a polyfunctional urethane (meth) acrylate.
The optical film according to claim 1, wherein the composition for the second resin layer comprises a mixture of the thiol compound and the polyene compound, the zirconium oxide, and an initiator.
The method of claim 10, wherein the thiol compound is at least one of pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), and 1,2- Including,
Wherein the polyene compound comprises at least one of 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione and pentaerythritol tetraacrylate. film.
The optical film according to claim 10, wherein the composition for the second resin layer further comprises a polyisocyanate.
13. The optical film according to claim 12, wherein the polyisocyanate comprises at least one of xylene diisocyanate and isophorone diisocyanate.
The optical film of claim 1, wherein an absolute value of a refractive index difference between the second resin layer and the first resin layer is 0.05 to 0.30.
The antireflection film as claimed in claim 1, wherein the antireflection layer is formed of a composition for an antireflection layer comprising inorganic particles, a fluorine-containing monomer or oligomer thereof, a fluorine-free monomer or oligomer thereof, an initiator and a fluorine-containing additive .
The optical film according to claim 15, wherein the inorganic particles are contained in an amount of 20 to 70% by weight of the antireflection layer.
16. The optical film according to claim 15, wherein the inorganic particles comprise hollow silica.
The optical film of claim 1, wherein the antiglare layer comprises organic fine particles, and the organic fine particles are contained in an amount of 1 wt% to 10 wt% of the antiglare layer.
The optical film according to claim 18, wherein the organic fine particles comprise cross-linked polystyrene-based particles.
The optical film of claim 1, wherein the contrast-improving optical film has the antiglare layer or the antireflection layer formed on the contrast-improving layer.
The optical film according to claim 1, wherein the contrast-improving optical film has the antiglare layer and the antireflection layer sequentially formed from the contrast-improving layer.
The optical system according to claim 1, wherein the optical pattern includes an optical pattern in which a first surface is formed at a top portion and at least one inclined surface connected to the first surface, and the inclined surface is a plane or a curved surface, film.
Polarizing film; And
And a contrast ratio improving optical film according to any one of claims 1 to 22 formed on one side of the polarizing film.
The polarizing plate according to claim 23, wherein the contrast ratio improving optical film is formed on a light exit surface of the polarizing film.
A liquid crystal display device comprising the polarizer of claim 23.

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