KR102414308B1 - Polarizing plate and optical display apparatus comprising the same - Google Patents

Abstract

polarizer; and a first retardation layer and a second retardation layer sequentially stacked on a lower surface of the polarizer, wherein an alignment layer is formed at an interface between the first retardation layer and the second retardation layer, and the second retardation layer includes It includes a coating layer containing a cellulose ester-based compound, wherein the second retardation layer further includes a cured product of a composition containing at least one of a UV curable compound and a thermosetting compound. A polarizing plate and an optical display device including the same are provided.

Description

Polarizing plate and optical display device including same

The present invention relates to a polarizing plate and an optical display device including the same. More specifically, the present invention relates to a polarizing plate having a thinning effect, excellent antireflection, excellent black luminous effect, and fairness improvement effect by having a second retardation layer with high solvent resistance, and an optical display device including the same.

The light emitting display device has a high reflectance from the side due to the reflector included in the light emitting display device. Accordingly, the light emitting display device needs a polarizing plate capable of improving the black visual sensation by lowering the reflectance at the side.

The polarizing plate includes a polarizer and a retardation film provided on one surface of the polarizer. In the retardation film, two or more retardation films are laminated. Conventionally, a positive C layer was prepared by coating a liquid crystal on an alignment layer or by rubbing a substrate and then coating the liquid crystal. A retardation film was prepared by laminating a retardation film capable of implementing in-plane retardation and a positive C layer as an adhesive layer. However, the lamination process by the adhesive layer may reduce the fairness of the polarizing plate and thicken the polarizing plate.

Background art of the present invention is disclosed in Korean Patent Application Laid-Open No. 10-2016-0006817 and the like.

An object of the present invention is to provide a polarizing plate provided with a second retardation layer with high solvent resistance.

Another object of the present invention is to provide a polarizing plate that provides an excellent antireflection effect and an excellent black luminance improvement effect even when an alignment layer is directly laminated on a second retardation layer.

Another object of the present invention is to provide a polarizing plate in which an alignment layer is directly laminated on a second retardation layer to provide a thinning effect.

Another object of the present invention is to provide a polarizing plate with improved processability by improving scratch defects caused by friction with rolls and eliminating the need to use a release film when manufacturing a polarizing plate.

A polarizing plate according to one aspect of the present invention is provided.

1. A polarizer is a polarizer; and a first retardation layer and a second retardation layer sequentially stacked on a lower surface of the polarizer, wherein an alignment layer is formed at an interface between the first retardation layer and the second retardation layer, and the second retardation layer includes A coating layer containing a cellulose ester compound is included, and the second retardation layer further includes a cured product of a composition containing at least one of a UV curable compound and a thermosetting compound.

In 2.1, the second retardation layer may further include a cured product of the UV curable compound-containing composition.

In 3.1-2, the second retardation layer may further include a cured product of the composition containing the thermosetting compound.

In 4.1-3, the second retardation layer may be a positive C layer.

In 5.1-4, the cellulose ester-based compound may include at least one of cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).

In 6.1-5, the cured product of the composition containing at least one of the UV curable compound and the thermosetting compound may be included in the cellulose ester compound-containing coating layer or the second retardation layer.

In 7.1-6, the cured product of the composition containing at least one of the UV curable compound and the thermosetting compound may be included in the upper surface of the cellulose ester compound-containing coating layer or the second retardation layer.

In 8.1-7, the UV curable compound may include at least one of fluorene-based monofunctional or polyfunctional (meth)acrylate, and alkylene glycol group-containing monofunctional or polyfunctional (meth)acrylate.

In 9.8, the monofunctional or polyfunctional (meth)acrylate containing an alkylene glycol group may include a monofunctional or polyfunctional (meth)acrylate containing 6 to 20 moles of ethylene glycol.

In 10.1-9, the thermosetting compound may include a thermosetting compound having at least one of an epoxy group, a (meth)acrylate group, and an isocyanate group.

In 11.1-10, the cured product may be included in an amount of 1 wt% to 35 wt% of the second retardation layer.

In 12.1-11, the alignment layer may be directly formed on the first retardation layer and the second retardation layer, respectively.

In 13.1-12, the alignment layer may include a liquid crystal alignment layer.

In 14.1-13, the first retardation layer may be a reverse wavelength dispersion retardation layer.

In 15.1-14, the first retardation layer may have an in-plane retardation (Re) of 80 nm to 160 nm at a wavelength of 550 nm.

In 16.1-15, the laminate of the first retardation layer, the alignment layer, and the second retardation layer may have an in-plane retardation Re of 70 nm to 170 nm at a wavelength of 550 nm.

In 17.1-16, the laminate of the first retardation layer, the alignment layer, and the second retardation layer may satisfy Equation 3 and Equation 4 below:

[Equation 3]

0.8 ≤ Re(450)/Re(550) < 1.0

[Equation 4]

1.0 < Re(650)/Re(550) ≤ 1.2

(In Equations 3 and 4 above,

Re (450), Re (550), Re (650) is the in-plane retardation of the laminate of the first retardation layer, the alignment layer, and the second retardation layer at a wavelength of 450 nm, a wavelength of 550 nm, and a wavelength of 650 nm, respectively (Re) (unit: nm) ).

In 18.1-17, a protective layer may be further laminated on the upper surface of the polarizer.

An optical display device according to another aspect of the present invention includes the polarizing plate of the present invention.

The present invention provides a polarizing plate having a second retardation layer with high solvent resistance.

The present invention provides a polarizing plate that provides an excellent anti-reflection effect and an excellent black luminance improvement effect even when the alignment layer is directly laminated on the second retardation layer.

The present invention provides a polarizing plate in which an alignment layer is directly laminated on a second retardation layer to provide a thinning effect.

The present invention provides a polarizing plate with improved processability by improving scratch defects caused by friction with a roll and eliminating the need to use a release film when manufacturing a polarizing plate.

1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.
2 is a POM (Polarized Optical Microscope) evaluation results of Examples and Comparative Examples.

Hereinafter, embodiments of the present application will be described in more detail with reference to the accompanying drawings. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present application may be sufficiently conveyed to those skilled in the art. In order to clearly express the components of each device in the drawings, the sizes such as widths and thicknesses of the components are somewhat enlarged, and the sizes of the widths and thicknesses of the components are limited to the scope of the present invention. it's not going to be In a plurality of drawings, the same reference numerals refer to substantially the same components.

In this specification, "upper" and "lower" are defined based on the drawings, and depending on the perspective of the city, "upper" may be changed to "lower" and "lower" to "upper", and "on" or What is referred to as “on” may include cases where other structures are interposed in the middle as well as immediately above. On the other hand, reference to "directly on" or "immediately on" or "directly forming" refers to no intervening other structures such as intermediates.

In the present specification, the "in-plane retardation (Re)" is represented by the following formula A, the "thickness direction retardation (Rth)" is represented by the following formula B, and the "biaxiality degree (NZ)" is represented by the following formula C:

[Formula A]

Re = (nx - ny) x d

[Formula B]

Rth = ((nx + ny)/2 - nz) x d

[Formula C]

NZ = (nx - nz)/(nx - ny)

(In Equations A to C, nx, ny, and nz are refractive indices in the slow axis direction, fast axis direction, and thickness direction of the optical element, respectively, at the measurement wavelength, and d is the thickness of the optical element. (unit: nm)).

In Equations A to C, "optical element" means a first retardation layer, a second retardation layer, or a laminate of a first retardation layer and a second retardation layer. In Formulas A to C, “measurement wavelength” may mean a wavelength of 450 nm, 550 nm, or 650 nm.

As used herein, “(meth)acryl” means acrylic and/or methacrylic.

When describing a numerical range in the present specification, "X to Y" means X or more and Y or less (X≤ and ≤Y).

In the polarizing plate of the present invention, the first retardation layer is laminated on the second retardation layer without an adhesive layer, an adhesive layer or an adhesive layer, an alignment film is formed at the interface between the first retardation layer and the second retardation layer, and the second retardation layer is A coating layer containing a cellulose ester compound is included, and the second retardation layer further includes a cured product of a composition containing at least one of a UV curable compound and a heat curable compound.

The second retardation layer further includes a cured product of a composition containing at least one of a UV curable compound and a heat curable compound, so that the solvent resistance of the second retardation layer is increased, so that the alignment film on the surface on which the first retardation layer is formed in the second retardation layer It can be made to form stably. As will be described in detail below, the second retardation layer is a coating layer containing a cellulose ester compound, and if it does not include a cured product of a composition containing at least one of a UV curable compound and a heat curable compound, the solvent resistance is weakened and the alignment layer cannot be properly formed. The first retardation layer is formed by coating a composition for the first retardation layer on the alignment layer and then curing the composition. Since the alignment layer is stably formed on the second retardation layer, the first retardation layer can properly realize the intended retardation, and through this, the stack of the second retardation layer, the alignment layer, and the first retardation layer is applied to the optical display device. When applied, it is possible to implement an excellent anti-reflection effect from the side and an excellent black visual effect. In addition, since the adhesive layer, the adhesive layer, or the adhesive layer is not formed between the first retardation layer and the second retardation layer, the polarizing plate can be made thin.

In addition, the polarizing plate of the present invention can improve fairness. That is, when the second retardation layer, the alignment layer, and the first retardation layer are sequentially formed on the release film and then laminated with the polarizer, the polarizing plate can be easily manufactured and there may be no scratch defect due to friction with the roll. However, when an alignment layer, a first retardation layer, and a second retardation layer are formed on the release film and then laminated with a polarizer, the release film is inevitably peeled off. The laminate of the alignment layer, the first retardation layer, and the second retardation layer usually has a thickness of 5 μm or less and is not easy to handle without an additional release film.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG. 1 .

Referring to FIG. 1 , the polarizing plate includes a polarizer 40 , a first retardation layer 10 , an alignment layer 30 , and a second retardation layer 20 . On the lower surface of the polarizer 40 , a first retardation layer 10 , an alignment layer 30 , and a second retardation layer 20 are sequentially stacked.

[2nd phase difference layer]

The second retardation layer 20 implements a thickness direction retardation (Rth) within a predetermined range, thereby implementing an antireflection effect and a black luminous effect on the side surface of the polarizing plate together with the first retardation layer.

In one embodiment, the thickness direction retardation (Rth) of the second retardation layer at a wavelength of 550 nm may be -60 nm to -20 nm. In the above range, the polarizing plate may provide an anti-reflection effect and an effect of improving black visual perception when applied to an optical display device. Specifically, the second retardation layer may have an Rth of -50 nm to -30 nm at a wavelength of 550 nm, most specifically -45 nm to -35 nm.

The second retardation layer has a refractive index relationship of nz > nx ≒ ny (nx, ny, nz is the refractive index of the second retardation layer in the slow axis direction, the fast axis direction, and the thickness direction at a wavelength of 550 nm) in order to secure the thickness direction retardation have That is, the second retardation layer may be a positive C layer.

The second retardation layer includes a cellulose ester-based compound-containing coating layer. Accordingly, the inventors of the present invention may form the second retardation layer without an alignment layer by forming the second retardation layer using the cellulose ester-based compound or the cellulose ester-based compound-containing composition. In addition, since the cellulose ester-based compound is a non-liquid crystalline compound, it is not brittle like liquid crystal, and thus the durability of the polarizing plate may be improved.

In one embodiment, the second retardation layer includes a coating layer containing a cellulose ester-based compound and does not include an alignment layer on a lower surface of the second retardation layer.

In addition, since the second retardation layer includes a cellulose ester-based compound-containing coating layer, the glass transition temperature of the second retardation layer may be increased to increase durability of the polarizing plate.

In one embodiment, the second retardation layer may have a glass transition temperature of 140°C or higher, for example, 140°C to 200°C. In the above range, durability of the polarizing plate may be increased.

The cellulose ester-based compound may include at least one of a cellulose ester-based resin, a cellulose ester-based oligomer, and a cellulose ester-based monomer. These may be included alone or in mixture of two or more.

Cellulose ester-based compounds refer to the condensation reaction product from the reaction of a hydroxyl group on cellulose with a carboxylic acid group of a carboxylic acid. The cellulose ester-based compound may be regioselectively or randomly substituted. Regioselectivity can be determined by determining the relative degree of substitution at C6, C3, C2 on the cellulose ester by carbon 13 NMR. Cellulose esters can be prepared by conventional methods by contacting a cellulose solution with one or more C1 to C20 acylating agents for a contact time sufficient to provide a cellulose ester having the desired degree of substitution and polymerization. Preferred acylating agents are one or more C1 to C20 straight or branched chain alkyl or aryl carboxylic acid anhydrides, carboxylic acid halides, diketones, or acetoacetic acid esters. Examples of anhydrides of carboxylic acids include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, hexanoic anhydride, 2-ethylhexanoic anhydride, nonanoic anhydride, lauric anhydride, palmitic anhydride, stearic anhydride, benzoic anhydride, substituted benzoic anhydride, phthalic anhydride, isophthalic anhydride. Examples of carboxylic acid halides include acetyl, propionyl, butyryl, hexanoyl, 2-ethylhexanoyl, lauroyl, palmitoyl, benzoyl, substituted benzoyl, and stearoyl chloride. Examples of the acetoacetic acid ester may include methylacetoacetate, ethylacetoacetate, propylacetoacetate, butylacetoacetate, and tert-butylacetoacetate. Most preferred acylating agents are C2 to C9 straight or branched chain alkyl carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, 2-ethylhexanoic anhydride, nonanoic anhydride, stearic anhydride and the like.

Preferred examples of the cellulose ester compound may include, but are not limited to, one or more of cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).

In one embodiment, the cellulose ester-based compound may have a substituent of two different acyl groups. At least one or more of the acyl groups may include an aromatic substituent, and the cellulose ester-based compound may have a relative degree of substitution (RDS) of C6>C2>C3. C6 denotes the degree of substitution at carbon 6 in the cellulose ester, C2 denotes the degree of substitution at carbon 2 in the cellulose ester, and C3 denotes the degree of substitution at carbon 3 in the cellulose ester. The aromatic compound may include benzoate or substituted benzoate.

In another embodiment, the cellulose ester-based compound comprises a regioselective substituted cellulose ester compound having the following (a) and (b),

(a) a plurality of chromophore-acyl substituents, (b) a plurality of pivaloyl substituents;

The cellulose ester-based compound has a hydroxyl group substitution degree of about 0.1 to about 1.2, the cellulose ester-based compound has a chromophore acyl substitution degree of about 0.4 to about 1.6, and the chromophore at carbon 2 of the cellulose ester-based compound The difference between the sum of the morphophore acyl substitution degree and the chromophore acyl substitution degree at carbon 3 and the chromophore acyl substitution degree at carbon 6 is about 0.1 to about 1.6, and the chromophore-acyl is i), (ii), (iii), (iv):

(i)(C6-20)aryl-acyl, wherein aryl is aryl unsubstituted or substituted with 1 to 5 R ₁ ,

(ii) heteroaryl-acyl, wherein heteroaryl is a 5-10 membered ring having 1 to 4 heteroatoms selected from N, O, S, wherein the heteroaryl is unsubstituted or 1 to 5 is substituted with R ₁ of

(iii)

The aryl is C1-6 aryl,

said aryl is unsubstituted or substituted with 1 to 5 R 1 ,

(iv)

The heteroaryl is a 5-10 membered ring having 1 to 4 heteroatoms selected from N, O, S, the heteroaryl is unsubstituted or substituted with 1 to 5 R ₁ ,

이다.each R ₁ is independently nitro, cyano, (C1-6)alkyl, halo(C1-6)alkyl, (C6-20)aryl-CO2-, (C6-20)aryl, (C1-6) ) alkoxy, halo (C1-6) alkoxy, halo, 5 to 10 membered heteroaryl having 1 to 4 heteroatoms selected from N, O, S, or

to be.

In one embodiment, the chromophore-acyl may be unsubstituted or substituted benzoyl, or unsubstituted or substituted naphthyl.

In one embodiment, the chromophore-acyl may be selected from the group:

In this case, * represents the bonding site of the chromophore-acyl substituent to the oxygen of the cellulose ester.

The cellulose ester-based compound may be included in an amount of 65 wt% to 99 wt% of the second retardation layer. In the above range, the second retardation layer may secure the aforementioned thickness direction retardation. Specifically, the cellulose ester-based compound may be included in an amount of 80 wt% to 99 wt%, more specifically 80 wt% to 97 wt% of the second retardation layer. In the above range, the retardation in the thickness direction of the second retardation layer may be easily expressed.

The cellulose ester-based compound may express the thickness direction retardation of the present invention by being coated on a release film and then dried. The release film is not particularly limited, and may include a cellulose-based film containing triacetyl cellulose or the like, or a polyester-based film containing polyethylreterephthalate. The release film may be peeled off after forming the second retardation layer. The coating thickness may be greater than 0 μm and less than or equal to 5 μm, specifically 1 μm to 5 μm, and more specifically 2 μm to 4 μm. Within the above range, the thickness direction retardation of the second retardation layer may be expressed.

The coating layer containing the cellulose ester compound may further include an additive having an aromatic fused ring in addition to the cellulose ester compound.

The additive having the aromatic fused ring may serve to control the thickness direction retardation expression rate and wavelength dispersion of the second retardation layer. The additive having an aromatic fused ring may include naphthalene, anthracene, phenanthrene, pyrene, and Structure 1 or Structure 2 below. The additive having the aromatic fused ring may include 2-naphthyl benzoate, 2,6-naphthalene dicarboxylic acid diester of the following structure 3, naphthalene, abietic acid ester of the following structure 4, etc. Not limited to:

[Structure 1]

[Structure 2]

[Structure 3]

(In Structure 3, R is C1 to C20 alkyl or C6 to C20 aryl, n is an integer from 0 to 6)

[Structure 4]

(In Structure 4, R is C1 to C20 alkyl or C6 to C20 aryl)

Preferably, the additive having an aromatic fused ring is, for example, at least one of naphthalene, anthracene, phenanthrene, pyrene, 2-naphthyl benzoate, and 2,6-naphthalene dicarboxylic acid diester of structure 3 above. may include, but are not limited to.

The additive having an aromatic fused ring may be included in an amount of 35 wt% or less, specifically 5 wt% to 35 wt%, specifically 10 wt% to 30 wt% of the second retardation layer. Within the above range, there may be effects of increasing the thermal stability of the second retardation layer, increasing the retardation expression rate per thickness, and controlling wavelength dispersion.

The second retardation layer further includes a cured product of a composition containing at least one of a UV curable compound and a heat curable compound.

UV curable compounds do not react with cellulose ester compounds. The thermosetting compound does not react with the cellulose ester compound. Through this, the thickness direction retardation of the second retardation layer may not be affected.

A cured product of a composition containing at least one of a UV curable compound and a heat curable compound prevents the second retardation layer from being damaged by the solvent contained in the composition for forming an alignment film when forming the alignment film on the second retardation layer, thereby preventing the second retardation layer from being damaged. By allowing the thickness direction retardation of the layers to be properly implemented and the alignment layer to be stably formed, the target first retardation layer can be normally formed. The second retardation layer, which does not contain a cured product of a composition containing at least one of a UV curable compound and a heat curable compound, is damaged by the solvent contained in the composition for forming an alignment film, so that the alignment film and the first retardation layer are damaged by the coating layer containing the cellulose ester compound. It could not be formed properly.

The cured product of the composition containing at least one of a UV curable compound and a heat curable compound may be included in at least a portion of the cellulose ester compound-containing coating layer or the second retardation layer.

In one embodiment, the cured product of the composition containing at least one of a UV curable compound and a heat curable compound may be included in the cellulose ester compound-containing coating layer or the second retardation layer. For example, the second retardation layer may include a cellulose ester-based compound; and coating a composition comprising at least one of a UV curable compound and a thermosetting compound on a release film, and drying and/or curing.

In another embodiment, the cured product of the composition containing at least one of a UV curable compound and a heat curable compound is an upper surface of the coating layer containing the cellulose ester compound or the second retardation layer, that is, the interface between the coating layer and the alignment layer containing the cellulose ester compound or the second retardation It may be included at the interface between the layer and the alignment layer. For example, the second retardation layer may be formed by coating a composition including at least one of a UV curable compound and a thermosetting compound on a coating layer containing a cellulose ester compound, and drying and/or curing the composition.

Preferably, the second retardation layer may include a cured product of a composition including at least one of a UV curable compound and a thermosetting compound. The composition containing at least one of the UV curable compound and the thermosetting compound may not affect the retardation in the thickness direction of the coating layer containing the cellulose ester compound.

Hereinafter, a UV curable compound is demonstrated.

The UV curable compound may include at least one of conventional monomers, oligomers, and polymers that can be cured by UV irradiation. The UV curable compound may include at least one UV curable functional group, for example, at least one of a (meth)acrylate group, a vinyl group, and an epoxy group, preferably a (meth)acrylate group, but is not limited thereto. The UV curable compound may comprise one or more of monomers, oligomers, polymers, containing one or more, for example two or more, such as two to ten, UV curable functional groups.

Specifically, the UV curable compound is 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentylglycol di(meth)acrylate, polyethylene glycol di(meth)acrylate , neopentyl glycol adipate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified di (meth) acrylate, di ( Meth)acryloxyethyl isocyanurate, allylated cyclohexyl di(meth)acrylate, tricyclodecanedimethanol (meth)acrylate, dimethylol dicyclopentanedi(meth)acrylate, ethylene oxide modified hexahydro Phthalic acid di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, neopentylglycol-modified trimethylpropane di(meth)acrylate, adamantane di(meth)acrylate or 9,9-bis bifunctional acrylates such as [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 trifunctional acrylates such as modified trimethylolpropane tri(meth)acrylate, trifunctional urethane (meth)acrylate, or tris(meth)acryloxyethyl isocyanurate; tetrafunctional acrylates such as diglycerol tetra(meth)acrylate or pentaerythritol tetra(meth)acrylate; 5-functional acrylates, such as dipentaerythritol penta (meth)acrylate; And dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. isocyanate monomer and trimethylolpropane tri (meth) acrylate and hexafunctional acrylates such as reactants, but is not limited thereto.

In one embodiment, the UV curable compound may include a high refractive index UV curable compound having a refractive index of 1.6 or more, for example, 1.6 to 1.7. By using the UV curable compound of the high refractive index, the light transmittance of the second retardation layer may be increased by reducing the difference in refractive index with the cellulose ester compound.

For example, the high refractive index UV curable compound may include a fluorene-based polyfunctional (meth)acrylate. The fluorene-based polyfunctional (meth)acrylate may further enhance the solvent resistance of the coating layer containing the cellulose ester compound due to the fluorene group while providing a high refractive index. For example, the fluorene-based polyfunctional (meth)acrylate may include a compound represented by the following Chemical Formula 1, but is not limited thereto:

[Formula 1]

(In Formula 1, 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 4.

For example, the UV-curable compound having a high refractive index may include a (meth)acrylate having a biphenyl group. The biphenyl group-containing (meth)acrylate has a refractive index of 1.55 or more, for example, 1.55 to 1.60, which can provide a high refractive index. For example, the biphenyl group-containing (meth)acrylate may include a compound represented by the following formula (2), but is not limited thereto:

[Formula 2]

(In Formula 2, n is an integer of 1 to 4, R is hydrogen or a methyl group).

The compounds of Formulas 1 and 2 may be synthesized by a conventional method or commercially available products may be used.

In another embodiment, the UV curable compound may contain an alkylene glycol group-containing monofunctional or polyfunctional (meth)acrylate. The monofunctional or polyfunctional (meth)acrylate containing an alkylene glycol group has excellent compatibility with the cellulose ester-based compound, and thus a transparent second retardation layer can be obtained. For example, the alkylene glycol group-containing (meth) acrylate is a monofunctional or polyfunctional (meth) acrylate containing 6 mol to 20 mol of ethylene glycol, specifically methoxy containing 6 mol to 20 mol of ethylene glycol At least one of polyethylene glycol (meth) acrylate, ethylhexyl polyethylene glycol (meth) acrylate containing 6 to 20 moles of ethylene glycol, and octyl polyethylene glycol (meth) acrylate containing 6 to 20 moles of ethylene glycol may include, but is not limited to.

The heat-curable compound may include at least one of conventional monomers, oligomers, and polymers that can be cured by heat. The thermosetting compound may include, but is not limited to, one or more thermosetting functional groups such as, but not limited to, an epoxy group, a (meth)acrylate group or an isocyanate group. The thermally curable compound may comprise one or more of monomers, oligomers, polymers, containing one or more, such as two or more, such as two to ten, thermally curable functional groups.

Preferably, the UV-curable compound may include at least one of fluorene-based, biphenyl-based, or alkylene glycol-based monofunctional or polyfunctional (meth)acrylate. Preferably, the thermosetting compound may include at least one of isocyanate-based compounds. These may enable the formation of the alignment layer and the first retardation layer to be better while the retardation in the thickness direction of the second retardation layer is well realized.

The composition containing at least one of a UV curable compound and a heat curable compound may further include an initiator. The initiator can accelerate curing of UV curable compounds, heat curable compounds. The initiator may include at least one of a photo radical initiator, a photo cationic initiator, and a thermal initiator. Conventional types known to those skilled in the art may be employed as the photo radical initiator, photo cationic initiator, and thermal initiator.

The composition containing at least one of a UV curable compound and a heat curable compound may be a solvent-free type. Alternatively, the composition containing at least one of a UV curable compound and a heat curable compound may further include a solvent to facilitate formation of the cellulose ester compound-containing coating layer. The solvent may include a conventional solvent known to those skilled in the art as long as it does not affect the retardation in the thickness direction of the cellulose ester-based compound-containing coating layer.

The composition containing at least one of a UV curable compound and a heat curable compound may further contain at least one of a monomer, an oligomer, and a resin that can react with a cellulose ester compound if it does not affect the thickness direction retardation of the second retardation layer. may be

One or more of the UV curable compound and the thermosetting compound may be included in an amount of 1 to 30 parts by weight, specifically 5 to 20 parts by weight, based on 100 parts by weight of the cellulose ester-based compound. In the above range, it is possible to increase the solvent resistance of the coating layer containing the cellulose ester compound so that the alignment film and the first retardation layer are stably formed, and the second retardation layer can express the thickness direction retardation of the present invention.

The cured product of the UV-curable compound or the cured product of the composition containing the UV-curable compound is 1 wt% to 35 wt%, specifically 1 wt% to 20 wt%, more specifically 3 wt% to 20 wt% of the second retardation layer may be included. In the above range, it is possible to increase the solvent resistance of the coating layer containing the cellulose ester compound so that the alignment film and the first retardation layer are stably formed, and the second retardation layer can express the thickness direction retardation of the present invention.

The cured product of the thermosetting compound or the cured product of the composition containing the thermosetting compound is used in an amount of 1 wt% to 35 wt%, specifically 1 wt% to 20 wt%, more specifically 3 wt% to 20 wt% of the second retardation layer. may be included. In the above range, it is possible to increase the solvent resistance of the coating layer containing the cellulose ester compound so that the alignment film and the first retardation layer are stably formed, and the second retardation layer can express the thickness direction retardation of the present invention.

The second retardation layer may have a degree of biaxiality (NZ) of 0.2 or less at a wavelength of 550 nm, specifically -0.1 to 0.1. In the above range, there may be a side viewing angle compensation effect.

The second retardation layer may have a thickness of 5 μm or less, specifically more than 0 μm and 5 μm or less, and more specifically 2 μm to 4 μm. In the above range, it can be used for a polarizing plate, and a thinning effect of the polarizing plate can be obtained.

Although not shown in FIG. 1 , a release film may be further laminated on the lower surface of the second retardation layer. The release film may protect the second retardation layer from external foreign matter.

Although not shown in FIG. 1 , an adhesive layer may be further laminated on the lower surface of the second retardation layer. The adhesive layer may laminate a polarizing plate on a panel for an optical display device.

[Orientation film]

An alignment layer 30 is formed at the interface between the second retardation layer 20 and the first retardation layer 10 . The alignment layer may allow the first retardation layer to express the desired in-plane retardation by aligning the material expressing the retardation when the composition for the first retardation layer is coated.

The alignment layer is formed directly on the second retardation layer. The "directly formed" means that any adhesive layer, adhesive layer, or adhesive layer is not interposed between the alignment layer and the second retardation layer.

The alignment layer is a liquid crystal alignment layer, and may include a liquid crystal alignment layer prepared by photo-alignment, but the present invention is not limited thereto. The liquid crystal alignment layer aligns the liquid crystal without rubbing the surface of the organic layer made of conventional polyimide or the like, thereby solving the problem of oscillation or static electricity and uniformly aligning the liquid crystal.

The alignment layer may be formed of a polymer composition for a liquid crystal alignment layer. The alignment layer may be formed of a commonly used polymer composition if it can implement the first retardation layer described in detail below.

In one embodiment, the polymer composition may include a photosensitive branched polymer and an organic solvent expressing liquid crystallinity.

The photosensitive side chain type polymer exhibiting liquid crystallinity has a photosensitive side chain bonded to the main chain, and can cause a crosslinking reaction, an isomerization reaction, or an optical Fris rearrangement reaction in response to light. The side chain-type polymer has a main chain and a side chain bonded to the main chain, and the side chain may have a photosensitive group capable of reacting with light at an end thereof to undergo a crosslinking reaction, isomerization reaction, or light Fris rearrangement reaction.

The main chain is a radical polymerizable group such as hydrocarbon, (meth)acrylate, itaconate, fumarate, maleate, alpha-methylene-gamma butyrolactone, styrene, vinyl, maleimide, norbornene, among siloxane It may be formed by polymerization of one or more, but is not limited thereto.

The side chain having the photosensitivity may include a cinnamoyl group, a coumarin group, or a chalcone group. For example, the photosensitive side chain may include one or more of the following Chemical Formulas 3-1 to 3-6, but the present invention is not limited thereto:

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Formula 3-4]

[Formula 3-5]

[Formula 3-6]

(In Formulas 3-1 to 3-6, * is a connection site,

T is a single bond or a C1-C12 alkylene group, and the hydrogen atom couple|bonded with them may be substituted by the halogen group;

Y ₁ represents a ring selected from a monovalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring and an alicyclic hydrocarbon having 5 to 8 carbon atoms, or 2 to 6 identical or different selected from their substituents is a group formed by bonding the rings of the ring through a bonding group B, and the hydrogen atoms bonded thereto are each independently -COOR ₀ (wherein R ₀ represents an alkyl group having 1 to 5 carbon atoms), -NO ₂ , -CN , -CH=C(CN) ₂ , -CH=CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

Y ₂ is a group selected from the group consisting of a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, an alicyclic hydrocarbon having 5 to 8 carbon atoms, and combinations thereof, and a hydrogen atom bonded thereto may be each independently substituted with -NO ₂ , -CN, -CH=C(CN) ₂ , -CH=CH-CN, a halogen group, an alkyl group having 1 to 5 carbon atoms, or an alkyloxy group having 1 to 5 carbon atoms;

each D is independently a single bond, -O-, -CH ₂ -, -COO-, -OCO-, -CONH-, -NH-CO-, -CH=CH-CO-O-, or -O-CO -CH=CH-;

R represents a C1-C6 alkoxy group, or represents the same definition as Y< ₁ >;

Cou represents a coumarin-6-yl group or a coumarin-7-yl group, and hydrogen atoms bonded thereto are each independently -NO ₂ , -CN, -CH=C(CN) ₂ , -CH=CH-CN, You may substituted with a halogen group, a C1-C5 alkyl group, or a C1-C5 alkyloxy group;

As for q1 and q2, one is 1 and the other is 0;

q3 is 0 or 1;

H and I are each independently a group selected from a divalent benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a pyrrole ring, and combinations thereof".

The organic solvent is not particularly limited as long as it is an organic solvent that dissolves the solid content contained in the polymer composition. Specifically, the organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone , N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy- N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, Methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether , Dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol Monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3- methoxybutyl acetate, tripropylene glycol methyl ether, etc. are mentioned. The organic solvent may be included alone or in a mixture of two or more.

The polymer composition may further include a reactive mesogenic compound. The reactive mesogenic compound may include a compound having an aromatic mesogenic group, a vinyl group, an acrylate group, a methacrylate group, a propenyl group, or an epoxy group.

The polymer composition may further include a crosslinking agent other than the photosensitive side chain type polymer and reactive mesogen compound that express the above-described liquid crystallinity. The crosslinking agent may allow the crosslinking reaction by the polymer to proceed so that the alignment layer is stably formed.

The polymer composition may include at least one of a fluorine-based surfactant, a silicone-based surfactant, and a nonionic surfactant as a compound for improving the uniformity of the alignment layer thickness and the surface smoothness. These surfactants may be included in an amount of 0.01 parts by weight to 5 parts by weight, preferably 0.01 parts by weight to 1 part by weight, based on 100 parts by weight of the polymer included in the polymer composition.

The alignment layer may be prepared by applying the polymer composition to the second retardation layer to form a coating film, heating the obtained coating film, and irradiating polarized UV light, but is not limited thereto.

The alignment layer may contain at least one of the above-described organic solvents as long as it does not affect the retardation of the first retardation layer.

[First phase difference layer]

The first retardation layer 10 is directly formed on the alignment layer. The "directly formed" means that any adhesive layer, adhesive layer, or adhesive layer is not interposed between the alignment layer and the first retardation layer.

The first retardation layer has an in-plane retardation within a predetermined range, so that the linearly polarized light is circularly polarized together with the second retardation layer, thereby implementing the effect of preventing side reflection and improving the black luminance.

In one embodiment, the first retardation layer may have an in-plane retardation of 80 nm to 160 nm, specifically 100 nm to 150 nm, more specifically 130 nm to 150 nm, and most specifically 138 nm to 145 nm at a wavelength of 550 nm. In the above range, it is possible to implement the effect of preventing side reflection and improving the sense of blackness together with the second retardation layer.

The first retardation layer may be a retardation layer having reverse wavelength dispersion. Since the first retardation layer has reverse wavelength dispersion, it is possible to further improve the lateral reflection prevention effect together with the second retardation layer. In one embodiment, the first retardation layer may satisfy Equation 1 and Equation 2 below.

[Equation 1]

0.8 ≤ Re(450)/Re(550) < 1.0

[Equation 2]

1.0 < Re(650)/Re(550) ≤ 1.2

(In Equation 1 and Equation 2 above,

Re(450), Re(550), and Re(650) are in-plane retardation (Re) (unit: nm) of the first retardation layer at a wavelength of 450 nm, a wavelength of 550 nm, and a wavelength of 650 nm, respectively.

In one embodiment, the in-plane retardation of the first retardation layer at a wavelength of 450 nm may be 64 nm to 144 nm, specifically 81 nm to 135 nm, and more specifically 112 nm to 129 nm. In the above range, the reverse wavelength dispersion of the first retardation layer may be secured. In one embodiment, the first retardation layer may have an in-plane retardation of 80 nm to 192 nm, specifically 100 nm to 180 nm, more specifically 138 nm to 172 nm at a wavelength of 650 nm. In the above range, the reverse wavelength dispersion of the first retardation layer may be secured.

The first retardation layer may have a degree of biaxiality (NZ) of 0.7 to 1.3, specifically 0.8 to 1.2, and more specifically 0.9 to 1.1 at a wavelength of 550 nm. In the above range, there may be an anti-reflection effect in front.

The first retardation layer may have a thickness of 15 μm or less, specifically more than 0 μm and 15 μm or less, and more specifically 0.1 μm to 7 μm. In the above range, it can be used for a polarizing plate, and a thinning effect of the polarizing plate can be obtained.

The first retardation layer may include a liquid crystal coating layer. The first retardation layer is not affected by the type of liquid crystal as long as the in-plane retardation of the present invention can be realized by being aligned by the alignment layer.

Although not shown in FIG. 1 , the first retardation layer and the polarizer may be laminated by forming an adhesive layer, an adhesive layer, or an adhesive layer between the first retardation layer and the polarizer.

[Laminate body of first retardation layer, alignment film, and second retardation layer]

The thickness of the laminate of the first retardation layer, the alignment layer, and the second retardation layer may be 10 µm or less, for example, more than 0 µm to 10 µm or less, more specifically, 3 µm to 7 µm. Within the above range, it is possible to implement a thin polarizing plate.

The laminate of the first retardation layer, the alignment layer, and the second retardation layer may have reverse wavelength dispersion. Specifically, the laminate of the first retardation layer, the alignment layer, and the second retardation layer may satisfy Equation 3 and Equation 4 below:

[Equation 3]

0.8 ≤ Re(450)/Re(550) < 1.0

[Equation 4]

1.0 < Re(650)/Re(550) ≤ 1.2

(In Equations 3 and 4 above,

Re (450), Re (550), Re (650) is the in-plane retardation of the laminate of the first retardation layer, the alignment layer, and the second retardation layer at a wavelength of 450 nm, a wavelength of 550 nm, and a wavelength of 650 nm, respectively (Re) (unit: nm) ).

In one embodiment, Re (450) / Re (550) may be 0.8 to 0.95, preferably 0.85 to 0.95. Re(650)/Re(550) may be greater than 1.0 and less than or equal to 1.1.

The laminate of the first retardation layer, the alignment layer and the second retardation layer has an in-plane retardation Re of 60 nm to 150 nm at a wavelength of 450 nm, preferably 60 nm to 140 nm, and an in-plane retardation Re at a wavelength of 550 nm of 70 nm to 170 nm, preferably 70 nm to 160 nm , the in-plane retardation Re at a wavelength of 650 nm may be 70 nm to 170 nm, preferably 70 nm to 160 nm. In the above range, there may be an effect of preventing side reflection and improving the visual perception of black.

[Polarizer]

The polarizer 40 may implement an antireflection effect by linearly polarizing external light to circularly polarize the linearly polarized light together with the first retardation layer and the second retardation layer.

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. Within the above range, it can be used for a polarizing plate.

Although not shown in FIG. 1 , a protective layer to be described in detail below may be further laminated on the lower surface of the polarizer. For details on the protective layer, refer to the detailed description below.

The polarizing plate may have a light transmittance of 90% or more, for example, 90% to 100% in a visible light region (eg, a wavelength of 400 nm to 700 nm). Within the above range, it can be used for an optical display device.

Hereinafter, a polarizing plate of another embodiment of the present invention will be described.

The polarizing plate of this embodiment includes a protective layer, a polarizer, a first retardation layer, an alignment layer, and a second retardation layer. A first retardation layer, an alignment layer, and a second retardation layer are sequentially stacked on a lower surface of the polarizer, and a protective layer is stacked on an upper surface of the polarizer. It is substantially the same as the polarizing plate of the embodiment of the present invention except that a protective layer is further laminated.

The protective layer may be laminated on the upper surface of the polarizer to protect the polarizer. The protective layer may include at least one of an optically transparent protective coating layer and a protective film.

The protective film is a cellulose ester-based resin containing triacetyl cellulose (TAC), etc., a cyclic polyolefin-based resin containing amorphous cyclic polyolefin (COP), etc., a polycarbonate-based resin, polyethylene terephthalate (PET), etc. Poly(meth)acrylate-based resins including polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethylmethacrylate resins, and the like It may include a film formed of at least one of a resin, polyvinyl alcohol-based resin, polyvinyl chloride-based resin, and polyvinylidene chloride-based resin, but is not limited thereto.

The protective coating layer may be formed of a composition for a protective coating layer including an active energy ray-curable compound. The active energy ray-curable compound may include at least one of (meth)acrylate-based, epoxy-based, and oxetane-based compounds, but is not limited thereto.

A functional coating layer may be additionally formed on the other surface of the protective insect. The functional coating layer may include, but is not limited to, at least one of a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflection layer, and an ultra-low reflection layer.

The protective film may be laminated on the polarizer by an adhesive layer, an adhesive layer, or an adhesive layer. The pressure-sensitive adhesive layer, the adhesive layer, or the pressure-sensitive adhesive layer may be formed of a conventional pressure-sensitive adhesive known to those skilled in the art, but is not limited thereto.

Hereinafter, an optical display device of the present invention will be described.

The optical display device of the present invention includes the polarizing plate of the present invention. The optical display device may include, but is not limited to, a light emitting device such as an organic light emitting display device.

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 provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example 1

A triacetyl cellulose (TAC) film (TD80UL, Fuji Company) was used as the release film.

Based on the solid content, 100 parts by weight of a cellulose ester-based compound (Eastman, Inc.), 5 parts by weight of a UV curable compound (BPF-022, Hannong Chemical Corporation, fluorene-based diacrylate, etc.), Irgacure photoinitiator 184 (Ciba Corp.) 3 parts by weight, methyl ethyl ketone and toluene as solvents were mixed so as to have a solid content of 8% by weight to prepare a composition for a second retardation layer. The prepared composition for the second retardation layer was coated on the upper surface of the TAC film to a predetermined thickness and dried to remove the solvent and photocured to form a second retardation layer (positive C layer).

A liquid crystal aligning agent (Nissan Corporation, HSAP-201, including butyl acetate) was coated on the upper surface of the second retardation layer to a predetermined thickness to form a coating film. An alignment film was formed by irradiating and heating the coating film with polarized ultraviolet rays.

A liquid crystal compound (Merck Corporation, RMM-1905), which is a composition for a first retardation layer, is coated on the upper surface of the alignment layer to a predetermined thickness and cured to form a first retardation layer (Re:142nm at a wavelength of 550nm, NZ:1.0, reverse wavelength dispersion ) was formed.

A polarizer (thickness: 12 μm) was prepared by stretching the polyvinyl alcohol film 3 times at 60° C., adsorbing iodine, and then stretching it 2.5 times in an aqueous boric acid solution at 60° C.

The prepared polarizer was adhered to the upper surface of the prepared first retardation layer with a UV curable adhesive, and the TAC film was released to prepare a polarizing plate.

Example 2

In Example 1, a polarizing plate was manufactured in the same manner as in Example 1, except that 10 parts by weight of the UV curable compound (BPF-022) was used.

Example 3

In Example 1, 5 parts by weight of a trifunctional acrylate (SR415, SATOMER, Inc.) containing 20 moles of ethylene glycol was used instead of 5 parts by weight of the UV curable compound (BPF-022) in Example 1 and A polarizing plate was manufactured in the same manner.

Example 4

Based on the solid content, 100 parts by weight of a cellulose ester compound (Eastman), 20 parts by weight of a diisocyanate compound (Duranate TKA-100, Asahi Kasei), 8% by weight of methyl ethyl ketone and toluene A composition for a second retardation layer was prepared by mixing so as to become A polarizing plate was manufactured in the same manner as in Example 1, except that the prepared composition for the second retardation layer was used and heat-cured.

Comparative Example 1

Based on the solid content, 100 parts by weight of a cellulose ester-based compound (Eastman, Inc.) and methyl ethyl ketone and toluene as solvents were mixed so as to have a solid content of 8% by weight to prepare a composition for a second retardation layer. A polarizing plate was manufactured in the same manner as in Example 1, except that the prepared composition for the second retardation layer was used.

Comparative Example 2

Based on the solid content, 100 parts by weight of a cellulose ester-based compound (Eastman, Inc.), 10 parts by weight of a silicone-based leveling agent (BYK-333, BYK, non-curable) as a leveling agent, methyl ethyl ketone and toluene as a solvent, 8 parts by weight of a solid content % to prepare a composition for a second retardation layer. A polarizing plate was manufactured in the same manner as in Example 1, except that the prepared composition for the second retardation layer was used.

Comparative Example 3

Based on the solid content, 100 parts by weight of a cellulose ester-based compound (Eastman), 10 parts by weight of a fluorine-based leveling agent (F-444, 3M, non-curable) as a leveling agent, methyl ethyl ketone and toluene as a solvent was mixed so as to have a solid content of 8% by weight to prepare a composition for a second retardation layer. A polarizing plate was manufactured in the same manner as in Example 1, except that the prepared composition for the second retardation layer was used.

The physical properties of Table 1 below were evaluated for the second retardation layer, the first retardation layer, and the polarizing plate prepared in Examples and Comparative Examples. The results are shown in Table 1 and Figure 2 below.

(1) Retardation: For the laminate of the first retardation layer, the second retardation layer, the first retardation layer, the alignment layer, and the second retardation layer prepared in Examples and Comparative Examples, the retardation was measured using Axoscan.

(2) Degree of in-plane retardation alignment of the first retardation layer: The degree of in-plane retardation alignment of the first retardation layer was evaluated using a Polarized Optical Microscope (POM). When the alignment layer was well formed, “○” was evaluated, and when the alignment layer was not well formed, “×” was evaluated.

Example comparative example One 2 3 4 One 2 3 2nd floor Rth -38.8 -36.8 -39.1 -38.9 -40.0 -37.2 -36.6 1st floor+
alignment film
+
2nd layer laminate Re ₍₄₅₀₎ 125.3 126.5 128.6 120.0 54.4 -** -** Re ₍₅₅₀₎ 141.9 146.4 142.6 136.7 62.6 -** -** Re ₍₆₅₀₎ 144.6 149.3 145.9 139.5 65.2 -** -** degree of orientation O O O O X X X

**: In Table 1, in Comparative Examples 2 and 3, the formation of the alignment layer and the first retardation layer was poor, and thus the retardation was not measured.

As shown in Table 1 and FIG. 2, the polarizing plate of the present invention has a good degree of alignment when the alignment layer is formed on the second retardation layer. The alignment layer + the first retardation layer stack realizes the desired retardation.

On the other hand, in Comparative Examples 1 to 3 in which the second retardation layer does not include a cured product of a composition containing at least one of a UV curable compound and a heat curable compound, the alignment layer and the first retardation layer are not properly formed, so the second retardation The layer + alignment layer + first retardation layer laminate could not realize the desired retardation.

Simple modifications or changes of the present invention can be easily carried out 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 (19)

polarizer; and a first retardation layer and a second retardation layer sequentially stacked on the lower surface of the polarizer,
An alignment layer is formed at an interface between the first retardation layer and the second retardation layer,
The second retardation layer includes a cellulose ester-based compound-containing coating layer,
The second retardation layer further comprises a cured product of a composition containing at least one of a UV curable compound and a thermosetting compound,
The second retardation layer is a positive C layer,
The cured product of the composition containing at least one of the UV curable compound and the thermosetting compound is included in the cellulose ester compound-containing coating layer or the second retardation layer, the polarizing plate.
The polarizing plate of claim 1, wherein the second retardation layer comprises a cured product of the UV curable compound-containing composition.
The polarizing plate of claim 1 , wherein the second retardation layer comprises a cured product of the composition containing the thermosetting compound.
delete The polarizing plate of claim 1, wherein the cellulose ester-based compound comprises at least one of cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).
delete delete According to claim 1, wherein the UV-curable compound is a fluorene-based monofunctional or polyfunctional (meth) acrylate, comprising at least one of alkylene glycol group-containing monofunctional or polyfunctional (meth) acrylate, polarizer.
The polarizing plate according to claim 8, wherein the alkylene glycol group-containing monofunctional or polyfunctional (meth)acrylate comprises a monofunctional or polyfunctional (meth)acrylate containing 6 to 20 moles of ethylene glycol. .
The polarizing plate according to claim 1, wherein the thermosetting compound comprises a thermosetting compound having at least one of an epoxy group, a (meth)acrylate group, and an isocyanate group.
The polarizing plate according to claim 1, wherein the cured product is included in an amount of 1 wt% to 35 wt% of the second retardation layer.
The polarizing plate of claim 1 , wherein the alignment layer is directly formed on the first retardation layer and the second retardation layer, respectively.
The polarizing plate of claim 1 , wherein the alignment layer includes a liquid crystal alignment layer.
The polarizing plate of claim 1 , wherein the first retardation layer is a reverse wavelength dispersion retardation layer.
The polarizing plate of claim 1, wherein the first retardation layer has an in-plane retardation (Re) of 80 nm to 160 nm at a wavelength of 550 nm.
The polarizing plate of claim 1, wherein the laminate of the first retardation layer, the alignment layer, and the second retardation layer has an in-plane retardation Re of 70 nm to 170 nm at a wavelength of 550 nm.
The polarizing plate according to claim 1, wherein the laminate of the first retardation layer, the alignment layer, and the second retardation layer satisfies the following Equations 3 and 4:
[Equation 3]
0.8 ≤ Re(450)/Re(550) < 1.0
[Equation 4]
1.0 < Re(650)/Re(550) ≤ 1.2
(In Equations 3 and 4 above,
Re (450), Re (550), Re (650) is the in-plane retardation of the laminate of the first retardation layer, the alignment layer, and the second retardation layer at a wavelength of 450 nm, a wavelength of 550 nm, and a wavelength of 650 nm, respectively (Re) (unit: nm) ).
The polarizing plate according to claim 1, wherein a protective layer is further laminated on the upper surface of the polarizer.
A liquid crystal display device comprising the polarizing plate of any one of claims 1 to 3, 5, and 8 to 18.

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