KR20210088236A - Retardation film, polarizing plate comprising same, liquid crystal display device comprising same and organic light emitting diode display device comprising same - Google Patents

Abstract

The present invention relates to a retardation film, to a polarizing plate including the same, to a liquid crystal display device including the same, and to an organic light emitting element display including the same. The retardation film includes a cellulose-based resin and an ethyl cellulose resin. By changing the wavelength dispersion, a specific reverse wavelength dispersion can be implemented.

Description

Retardation film, polarizing plate including same, liquid crystal display including same, and organic light emitting device display including same

The present invention relates to a retardation film, a polarizing plate including the same, a liquid crystal display including the same, and an organic light emitting diode display including the same.

Based on the recent development of optical technology, plasma display panel (PDP), liquid crystal display (LCD), organic light emitting diodes (OLED), etc. Display devices using the method have been proposed and marketed. Recently, the characteristics required for such display devices are becoming more advanced, and accordingly, the characteristics required for peripheral components such as optical films applied to the display devices are also being advanced. In particular, in recent display devices, as thin film reduction, weight reduction, and screen area enlargement are promoted, wide viewing angle, high contrast, suppression of image color change according to viewing angle, and uniformity of screen display are particularly important issues.

The retardation film is an optical film used in a display device for the purpose of improving a viewing angle and display quality, and can be divided into those having forward wavelength dispersion, flat wavelength dispersion, and reverse wavelength dispersion according to wavelength dispersion characteristics. The retardation film having positive wavelength dispersion refers to a retardation film having a characteristic that the retardation value generated as the wavelength of incident light increases, and the retardation film having flat wavelength dispersion has a similar degree regardless of the wavelength of incident light. It means a retardation film having a characteristic in which a retardation value occurs, and a retardation film having reverse wavelength dispersion means a retardation film having a characteristic in which a retardation value generated as the wavelength of incident light increases.

Most of the retardation films developed so far have positive wavelength dispersion or flat wavelength dispersion. As such, in the case of retardation films having positive wavelength dispersion or flat wavelength dispersion, the degree of retardation also changes when the wavelength of light changes. There is a problem in that it is difficult to obtain a uniform color or visual sensation. On the other hand, in the case of reverse wavelength dispersion, the larger the optical wavelength, the larger the phase delay value. Therefore, it is attracting attention in that a relatively uniform phase delay can be implemented in a relatively wide optical wavelength band.

However, since wavelength dispersion is a characteristic that appears uniquely depending on the material of the retardation film, it is necessary to find a new raw material to manufacture a retardation film having reverse wavelength dispersion in one sheet, which is not easy in reality. Therefore, conventionally, two or more retardation films having different wavelength dispersibility are laminated using an adhesive or an adhesive to prepare a retardation film having reverse wavelength dispersibility, or a resin having a positive retardation value and a resin having a negative retardation value are used together. A method for producing a retardation film having reverse wavelength dispersion by extruding to form a laminate and stretching the same has been proposed.

However, in the case of the first method, if the optical axes of the two retardation films to be laminated are not accurately arranged, reverse wavelength dispersion does not appear, so manufacturing is very difficult. In the case of the second method, there is a problem of the resin forming each layer. If the glass transition temperature is not similar, elongation does not occur properly, so there is a problem that the usable resin is limited.

In addition, in the case of the retardation film having improved wavelength dispersion by reverse wavelength dispersion, the glass transition temperature is very low, and thus, there is a problem in that the heat resistance is weak.

Therefore, there is a demand for the development of a retardation film that is easy to manufacture, has excellent heat resistance, and can implement reverse wavelength dispersion.

Korean Publication No. 2005-0101743

An object of the present invention is to provide a retardation film, a polarizing plate including the same, a liquid crystal display including the same, and an organic light emitting diode display including the same.

An exemplary embodiment of the present application is a cellulose-based resin comprising at least one selected from the group consisting of cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP); And a retardation film comprising a retardation film composition comprising an ethyl cellulose resin having flat wavelength dispersibility or a cured product thereof,

The cellulose-based resin: ethyl cellulose resin having flat wavelength dispersibility satisfies 99:1 to 66:34,

The retardation film is intended to provide a retardation film that satisfies the following Equations 1 and 2.

[Equation 1]

0.5 < R _in (450)/R _in (550) < 0.99

[Equation 2]

1.0 < R _in (650)/R _in (550) < 1.2

In the above formulas 1 and 2,

R _in (λ) is the in-plane retardation at a wavelength of λ nm, and is the value of _{(n x} -n _{y ) xd,}

The n _x is the refractive index in the slow axis (Slow Axis) direction of the retardation film plane,

Wherein n _y is the refractive index in the fast axis direction of the retardation film plane,

d is the thickness of the retardation film.

Another exemplary embodiment is a polarizer; And it provides a polarizing plate comprising at least one retardation film according to an exemplary embodiment of the present application.

Another exemplary embodiment is a liquid crystal cell; an upper polarizing plate provided in the upper layer of the liquid crystal cell; a lower polarizing plate provided in the lower layer of the liquid crystal cell; and a backlight unit provided on a lower layer of the lower polarizing plate, wherein at least one of the upper polarizing plate and the lower polarizing plate includes: a polarizer; and a retardation film according to an exemplary embodiment of the present application disposed on one surface of the polarizer.

Finally, an exemplary embodiment of the present application is an organic light emitting device (OLED) panel; and an upper polarizing plate provided on the organic light emitting diode (OLED) panel, wherein the upper polarizing plate includes: a polarizer; and an organic light emitting diode (OLED) display including the retardation film according to the present application disposed on one surface of the polarizer.

Cellulose-based resin and flat wavelength dispersibility comprising at least one selected from the group consisting of cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP) in the retardation film composition included in the retardation film according to the present invention As the ethyl cellulose resin is included in a specific content at the same time, it has a characteristic that can implement a specific reverse wavelength dispersion by changing the wavelength dispersion.

In particular, the retardation film composition included in the retardation film according to the present invention contains an ethyl cellulose resin having flat wavelength dispersibility with high Rin expression, and at the same time satisfies reverse wavelength dispersibility and R _in (550) is 100 nm. It has a feature that can be formed to have a low thickness to satisfy. That is, when the retardation film according to the present application is used as an OLED polarizing plate or LCD wide viewing angle polarizing plate, _{it must satisfy a certain level of R in} (550) value, and as it includes the retardation film composition according to the present application, R _in ( 550) can be formed to have a low thickness to satisfy 100 nm, thereby reducing the cost of manufacturing the polarizing plate itself, and has a feature of achieving slimming of a display including the same.

Since the retardation film comprising the retardation film composition according to the present invention has reverse wavelength dispersion in which the retardation value increases as the light wavelength increases, it has a characteristic capable of generating a relatively uniform degree of retardation in a wide light band. do. As a result, when the retardation film of the present invention is applied to a polarizing plate or a liquid crystal display device, it has characteristics capable of realizing superior color, luminance and optical properties compared to the prior art.

In addition, the organic light emitting diode (OLED) display including the retardation film according to the present application has excellent anti-reflection characteristics not only in the front direction of the screen but also in the oblique direction.

1 is a view showing a laminated structure of a polarizing plate according to an exemplary embodiment of the present application.
2 is a diagram illustrating a laminated structure of a polarizing plate according to an exemplary embodiment of the present application.
3 is a diagram illustrating a liquid crystal display device according to an exemplary embodiment of the present application.
4 is a diagram illustrating a schematic stacked structure of an organic light emitting diode (OLED) display according to an exemplary embodiment of the present application.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiment of the present invention is provided in order to explain the present invention in more detail to those with ordinary knowledge in the art.

An exemplary embodiment of the present application is a cellulose-based resin comprising at least one selected from the group consisting of cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP); And a retardation film comprising a retardation film composition comprising an ethyl cellulose resin having flat wavelength dispersibility or a cured product thereof,

The cellulose-based resin: ethyl cellulose resin having flat wavelength dispersibility satisfies 99:1 to 66:34,

The retardation film is intended to provide a retardation film that satisfies the following Equations 1 and 2.

[Equation 1]

0.5 < R _in (450)/R _in (550) < 0.99

[Equation 2]

1.0 < R _in (650)/R _in (550) < 1.2

In the above formulas 1 and 2,

R _in (λ) is the in-plane retardation at a wavelength of λ nm, and is the value of _{(n x} -n _{y ) xd,}

The n _x is the refractive index in the slow axis (Slow Axis) direction of the retardation film plane,

Wherein n _y is the refractive index in the fast axis direction of the retardation film plane,

d is the thickness of the retardation film.

In an exemplary embodiment of the present application, that the cellulose-based resin: ethyl cellulose resin having flat wavelength dispersibility satisfies 99:1 to 66:34 is a cellulose-based resin included in the retardation film composition included in the retardation film. It means the content ratio of the resin and the ethyl cellulose resin having flat wavelength dispersibility.

The retardation film composition according to the present invention includes a cellulose-based resin comprising at least one selected from the group consisting of cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP); and an ethyl cellulose resin having flat wavelength dispersibility, wherein the cellulose-based resin: ethyl cellulose resin having flat wavelength dispersibility satisfies 99:1 to 66:34, preferably 95:5 to 70:30 range can be satisfied.

The retardation film composition according to the present invention includes a specific content of the specific material, and has a characteristic that can implement specific reverse wavelength dispersion by changing wavelength dispersion. In particular, the retardation film composition included in the retardation film according to the present invention includes an ethyl cellulose resin having flat wavelength dispersibility with high Rin expression in the above content range, and at the same time satisfies reverse wavelength dispersibility and R _in (550) It has the characteristic that the thickness to satisfy this 100 nm can be formed low. That is, when the retardation film according to the present application is used as an OLED polarizing plate or LCD wide viewing angle polarizing plate, _{it must satisfy a certain level of R in} (550) value, and as it includes the retardation film composition according to the present application, R _in ( 550) can be formed to have a low thickness to satisfy 100 nm, thereby reducing the cost of manufacturing the polarizing plate itself, and has a feature of achieving slimming of a display including the same.

In Equations 1 and 2, R _in (λ) is a measurement of the plane-direction phase difference at a wavelength of λ nm, and the measurement is a value measured using Axoscan manufactured by Axometrics. That is, in Equations 1 and 2, R _in (450), R _in (550), and R _in (650) mean in-plane retardation values at 450 nm, 550 nm, and 650 nm, respectively.

The in-plane retardation at each wavelength is a value determined by the difference between the refractive index in the slow axis direction and the refractive index in the fast axis direction and the thickness of the retardation film as shown in the description of Equations 1 and 2 above. to be. The slow axis and fast axis are determined according to the orientation direction of the polymer chain of the retardation film, and the direction in which the polymer chain is oriented is called the slow axis, which is at each wavelength. Since it takes a long time for light to pass through, the direction in which the phase difference delay is greatest is called the slow axis. The fast axis is the opposite concept, and the direction in which the polymer chain has a smaller orientation is called the fast axis, which takes a short time for light to pass at each wavelength, so the direction with the smallest phase difference delay is advanced. This is called the Fast Axis.

In Equation 1, the in-plane retardation at a wavelength of _{550 nm may be referred to as R in} (550), and the in-plane retardation may be referred to _{as R in (450) at a wavelength of 450 nm. When R in} (450)/R _in (550), which is the phase difference ratio at two wavelengths, is less than 1, it is called reverse wavelength dispersion, when it is 1, flat (flat) wavelength dispersion, and when it has a value greater than 1, normal wavelength dispersion indicates

It can be seen that Equation 2 also represents reverse wavelength dispersion when R _in (650)/R _in (550) has the range of Equation 2 as in Equation 1 above.

In an exemplary embodiment of the present application, the number average molecular weight of the cellulose-based resin including at least one selected from the group consisting of the cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP) is 20,000 g/mol may be more than

In an exemplary embodiment of the present application, the number average molecular weight of the cellulose-based resin including at least one selected from the group consisting of the cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP) is 20,000 g/mol or more, preferably 30,000 g/mol or more, and more preferably 40,000 g/mol or more.

In an exemplary embodiment of the present application, the number average molecular weight of the cellulose-based resin including at least one selected from the group consisting of the cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP) is 300,000 g/mol may be below.

In an exemplary embodiment of the present application, the number average molecular weight of the ethyl cellulose resin having flat wavelength dispersibility provides a retardation film composition that is 19,000 g/mol or more.

In another exemplary embodiment, the number average molecular weight of the ethyl cellulose resin having flat wavelength dispersibility provides a retardation film composition that is 25,000 g/mol or more.

In another exemplary embodiment, the number average molecular weight of the ethyl cellulose resin having flat wavelength dispersibility provides a retardation film composition that is 150,000 g/mol or less.

The number average molecular weight refers to using the average molecular weight to express the molecular weight of the sample when the constituent units of the molecules are the same but different molecular weights, and the number average molecular weight is a value obtained by dividing the total weight by the number of chains, and is the average polymerization degree of the chains. It means a value multiplied by the molecular weight of the repeating unit.

In an exemplary embodiment of the present application, the cellulose-based resin provides a retardation film that is a cellulose acetate butyrate (CAB) resin having reverse wavelength dispersibility.

In particular, when the cellulose-based resin includes cellulose acetate butyrate (CAB) having reverse wavelength dispersibility, since a chemical group having a longer chain length than that of cellulose acetate propionate (CAP) is attached, flexibility is high and cellulose It has the characteristics of being able to form a plasticizer content lower than that of acetate propionate (CAP).

In addition, when the cellulose-based resin contains cellulose acetate butyrate (CAB) having reverse wavelength dispersibility, the Rin expression property is particularly high because the cellulose chain can be spread more widely, and the miscibility with ethyl cellulose is high. have better characteristics.

In an exemplary embodiment of the present application, the thickness for R _in (550) of the retardation film to satisfy 100 nm is 65 μm or less to provide a retardation film.

In an exemplary embodiment of the present application, _{a thickness for R in} (550) of the retardation film to satisfy 100 nm may be 65 μm or less, preferably 64 μm or less, and more preferably 62 μm or less.

In an exemplary embodiment of the present application, the thickness for R _in (550) of the retardation film to satisfy 100 nm may be 15 μm or more, preferably 20 μm or more, and more preferably 25 μm or more.

In an exemplary embodiment of the present application, the thickness for R _in (550) of the retardation film to satisfy 100 nm is 15 μm or more and 65 μm or less, preferably 20 μm or more and 64 μm or less, more preferably 25 μm or more and 62 μm or less.

The retardation film composition included in the retardation film according to the present invention contains a specific content of ethyl cellulose resin having flat wavelength dispersibility with high Rin expression, and at the same time satisfies reverse wavelength dispersibility and R _in (550) is 100 nm It has a feature that can be formed to have a low thickness to satisfy.

The retardation film according to the present invention can implement reverse wavelength dispersion by including a cellulose-based resin including at least one selected from the group consisting of the cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP), , furthermore, by _{including a specific content of ethyl cellulose resin having flat wavelength dispersibility with high R in} expression, it can be formed to have a low thickness to satisfy reverse wavelength dispersibility and Rin (550) to satisfy 100 nm at the same time will have

That is, when used as an OLED polarizing plate or LCD wide viewing angle polarizing plate, a certain level of R _in value must be satisfied, and at this time, the polarizing plate includes the retardation film composition according to the present application, so that R _in (550) satisfies 100 nm It is possible to form a low thickness for this purpose, the cost of manufacturing the polarizing plate itself can be reduced, and the display including the same can be made slim.

In an exemplary embodiment of the present application, the retardation film composition includes at least one selected from the group consisting of a solvent, a dispersant, an antioxidant, an adhesion enhancer, a photoinitiator, a thermal initiator, and a tackifier It provides a retardation film composition .

In particular, when the retardation film composition further includes an antioxidant, the durability of the retardation film including the same may be improved later.

In an exemplary embodiment of the present application, the crosslinking agent may include a crosslinking compound, and the crosslinking agent may use an isocyanate-based crosslinking agent, and those known in the art may be used.

According to an exemplary embodiment of the present specification, the cross-linkable compound is hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate having 2 to 14 ethylene groups, trimethyl Allpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, 2-trisacryloyloxymethylethylphthalic acid, propylene group Acidic modifications of propylene glycol di(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate with the number of a compound obtained by esterifying a polyhydric alcohol such as a mixture of pentaerythritol hexa(meth)acrylate (trade name: TO-2348, TO-2349, manufactured by Dong-A Synthetic Co., Ltd., Japan) with α,β-unsaturated carboxylic acid; a compound obtained by adding (meth)acrylic acid to a compound containing a glycidyl group, such as a trimethylolpropane triglycidyl ether acrylic acid adduct and a bisphenol A diglycidyl ether acrylic acid adduct; Ester compound of a compound having a hydroxyl group or an ethylenically unsaturated bond, such as a phthalic acid diester of β-hydroxyethyl (meth)acrylate and a toluene diisocyanate adduct of β-hydroxyethyl (meth)acrylate, and a polyhydric carboxylic acid , or adducts with polyisocyanates; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; and 9,9'-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, which may include one or more selected from the group consisting of, but not limited to, those known in the art. You can use common ones.

According to an exemplary embodiment of the present specification, the photoinitiator is a triazine-based compound, a biimidazole compound, an acetophenone-based compound, an O-acyloxime-based compound, a thioxanthone-based compound, a phosphine oxide-based compound, a coumarin-based compound, and a benzophenone It may be substituted with one or two or more substituents selected from the group consisting of non-based compounds.

Specifically, according to an exemplary embodiment of the present specification, the photoinitiator is 2,4-trichloromethyl-(4'-methoxyphenyl)-6-triazine, 2,4-trichloromethyl-(4'-methyl Toxystyryl)-6-triazine, 2,4-trichloromethyl-(piflonyl)-6-triazine, 2,4-trichloromethyl-(3',4'-dimethoxyphenyl)-6 -triazine, 3-{4-[2,4-bis(trichloromethyl)-s-triazin-6-yl]phenylthio}propanoic acid, 2,4-trichloromethyl-(4'-ethyl ratio triazine-based compounds such as phenyl)-6-triazine or 2,4-trichloromethyl-(4'-methylbiphenyl)-6-triazine; 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl biimidazole or 2,2'-bis(2,3-dichlorophenyl)-4,4',5 biimidazole-based compounds such as ,5'-tetraphenylbiimidazole; 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxye Toxy)-phenyl (2-hydroxy)propyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenyl acetophenone, 2-methyl-(4-methylthiophenyl)-2-mol Acetopes such as polyno-1-propan-1-one (Irgacure-907) or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one (Irgacure-369) non-type compounds; O-acyloxime compounds such as Irgacure OXE 01 and Irgacure OXE 02 manufactured by Ciba Geigy; benzophenone compounds such as 4,4'-bis(dimethylamino)benzophenone or 4,4'-bis(diethylamino)benzophenone; thioxanthone-based compounds such as 2,4-diethyl thioxanthone, 2-chlorothioxanthone, isopropyl thioxanthone or diisopropyl thioxanthone; 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide or bis(2,6-dichlorobenzoyl)propyl phosphine oxide Phosphine oxide type compounds, such as; 3,3'-carbonylvinyl-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 3-benzoyl-7-(diethylamino)coumarin; 3-benzoyl-7-methoxy-coumarin or 10,10'-carbonylbis[1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-Cl] Coumarin-based compounds such as -benzopyrano[6,7,8-ij]-quinolizin-11-one may be used alone or two or more may be mixed, but the present invention is not limited thereto.

In addition, the thermal initiator may use one known in the art.

Usable solvents include alcohol solvents such as methanol, ethanol, isopropyl alcohol and butanol, alkoxy alcohol solvents such as 2-methoxyethanol, 2-ethoxyethanol, and 1-methoxy-2-propanol, acetone, Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone and cyclohexanone, propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether , ether solvents such as diethylene glycol monomethyl ether, diethyl glycol monoethyl ether, diethyl glycol monopropyl ether, diethyl glycol monobutyl ether, diethylene glycol-2-ethylhexyl ether, benzene, toluene, xylene Aromatic solvents such as can be used alone or in combination.

In an exemplary embodiment of the present application, the retardation film provides a retardation film that satisfies the following Equations 3 and 4.

[Equation 3]

20nm ≤ R _in (550) ≤ 300nm

[Equation 4]

-300nm ≤ R _th (550) ≤ 0nm

In Equations 3 and 4,

R _in (550) is the in-plane retardation at a wavelength of 550 nm, (n _x -n _y ) is the value of xd,

R _th (550) is the thickness direction retardation at a wavelength of 550 nm, and is a value of {n _z -(n _x +n _y )/2} xd,

The n _x is the refractive index in the slow axis (Slow Axis) direction of the retardation film plane,

Wherein n _y is the refractive index in the fast axis direction of the retardation film plane,

Wherein n _z is the refractive index in the thickness direction of the retardation film,

d is the thickness of the retardation film.

In Equations 3 and 4, R _in (λ) is a measurement of the plane-direction phase difference at a wavelength of λ nm, and the measurement is a value measured using Axoscan manufactured by Axometrics. In addition, R _th (λ) is the phase difference in the thickness direction at the λ nm wavelength, and the refractive index in the thickness direction is measured with AxoScan equipment, and is a value determined by the thickness and the difference between the average of the refractive indices in the plane direction.

In an exemplary embodiment of the present application, the thickness of the retardation film is 10 μm or more and 150 μm can be below.

In another exemplary embodiment, the thickness of the retardation film is 10 μm or more and 150 μm or less, preferably 15 µm or more and 120 µm or less, more preferably 30 µm or more and 90 µm may be below.

As can be seen from Equations 1 to 4, the retardation value changes depending on the thickness of the retardation film, and in the present application, when the thickness of the retardation film has the above range, it has reverse wavelength dispersion, and later included in the liquid crystal display device In this case, it has the characteristics of increasing the size and durability of the liquid crystal display in a suitable thickness range.

In an exemplary embodiment of the present application, the solvent included in the retardation film composition may be in a state removed from the retardation film by drying or curing the composition.

On the other hand, the method for producing the retardation film of the present invention having the above characteristics is not particularly limited, and may be prepared by a method of film-forming and stretching the composition after preparing the composition.

The composition is prepared by, for example, pre-blending the film raw material with any suitable mixer such as an omni mixer, and then extrusion-kneading the obtained mixture. In this case, the mixer used for extrusion kneading is not specifically limited, For example, arbitrary suitable mixers, such as extruders, such as a single screw extruder and a twin screw extruder, and a pressure kneader, can be used.

As a method of the said film shaping|molding, arbitrary suitable film shaping|molding methods, such as the solution casting method (solution casting method), the melt extrusion method, the calendering method, the compression molding method, are mentioned, for example. Among these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are preferable.

The solvent used for the said solution casting method (solution casting method), For example, aromatic hydrocarbons, such as benzene, toluene, and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride; dimethylformamide; Dimethyl sulfoxide etc. are mentioned. These solvents may be used independently and may use 2 or more types together.

As an apparatus for implementing the said solution casting method (solution casting method), a drum type casting machine, a band type casting machine, a spin coater, etc. are mentioned, for example. On the other hand, examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature may be 150°C to 350°C, or 200°C to 300°C.

In the case of forming a film by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the extruded film is wound to obtain a roll-shaped film.

After the film is formed through the above process, the film is stretched. In the stretching process, longitudinal (MD) stretching and transverse direction (TD) stretching may be performed, respectively, or both may be performed. In addition, in the case of performing both the longitudinal stretching and the transverse stretching, stretching in either direction may be performed first and then stretching in the other direction, or stretching in both directions may be performed simultaneously. In addition, the stretching may be performed in one step or may be performed in multiple steps. In the case of longitudinal stretching, stretching may be performed by a speed difference between rolls, and in the case of transverse stretching, a tenter may be used. The starting angle of the rail of the tenter is usually within 10 degrees, suppressing the bowing phenomenon occurring during transverse stretching and controlling the angle of the optical axis regularly. Even when transverse stretching is performed in multiple steps, a bowing suppression effect can be obtained.

The stretching temperature is preferably in a range near the glass transition temperature of the composition as a raw material for the film, and when the glass transition temperature of the composition is Tg, preferably (Tg-30°C) to (Tg+100°C), more Preferably it is in the range of (Tg-20 degreeC) - (Tg+80 degreeC), More preferably, it is (Tg-5 degreeC) - (Tg+20 degreeC). There exists a possibility that sufficient draw ratio may not be obtained that extending|stretching temperature is less than (Tg-30 degreeC). Conversely, when the stretching temperature exceeds (Tg+100°C), a flow (flow) of the resin composition occurs, and there is a fear that stable stretching cannot be performed.

In addition, in the exemplary embodiment of the present application, the stretching ratio in the step of stretching the film may be 1.05 to 10 times based on the length in the stretching direction.

In addition, the total draw ratio is 1.1 times or more, or 1.2 times or more, or 1.5 times or more, based on the total stretch area of the base film, and may be stretched to be 25 times or less, or 10 times or less, or 7 times or less. If the stretching ratio is less than 1.1 times, the effect of stretching may not be sufficiently achieved, and if it exceeds 25 times, the film layer may be cracked.

Before the stretching, a process of flattening the coated surface of the composition and drying to volatilize the solvent included in the composition may be further performed.

The retardation film may be subjected to heat treatment (annealing) or the like after stretching treatment in order to stabilize its optical isotropy or mechanical properties. The heat treatment conditions are not particularly limited and any suitable conditions known to those skilled in the art may be employed.

The retardation film of the present invention as described above may be usefully applied to a polarizing plate and/or a liquid crystal display device. In one embodiment of the present invention, the present invention is a polarizer; And it provides a polarizing plate comprising at least one retardation film of the present application.

1 is a diagram illustrating a stacked structure of a polarizing plate 103 according to an exemplary embodiment of the present application. Specifically, the polarizing plate 103 has a structure in which a polarizer 102 and a retardation film 101 are laminated on one surface of the polarizer.

In an exemplary embodiment of the present application, the polarizer is not particularly limited, and a polarizer well known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye is used.

A polarizer exhibits a characteristic of extracting only light vibrating in one direction from incident light while vibrating in multiple directions. These properties can be achieved by stretching polyvinyl alcohol (PVA), which has absorbed iodine, with a strong tension. For example, more specifically, a step of swelling the PVA film by immersing it in an aqueous solution to swell, dyeing the swollen PVA film with a dichroic material that imparts polarization, stretching the dyed PVA film ) to form a polarizer through a stretching step of arranging the dichroic dye material side by side in the stretching direction, and a complementary color step of correcting the color of the PVA film that has undergone the stretching step. However, the polarizing plate of the present invention is not limited thereto.

In an exemplary embodiment of the present application, the polarizer and the retardation film may be adhered with an adhesive, and the available adhesive is not particularly limited as long as it is known in the art. For example, there are water-based adhesives, one-component or two-component polyvinyl alcohol (PVA)-based adhesives, polyurethane-based adhesives, epoxy-based adhesives, styrene-butadiene rubber-based (SBR-based) adhesives, or hot melt adhesives, but the present invention It is not limited only to these examples.

The retardation film may be directly attached to one or both surfaces of the polarizer. In addition, it is attached on the protective film of a conventional polarizing plate having a protective film attached to both sides of the polarizer, and can be usefully used as a retardation film.

When the retardation film is directly attached to one or both surfaces of the polarizer, for example, the structure may be an upper protective film/polarizer/retardation film or retardation film/polarizer/lower protective film. The attachment method is a roll coater, gravure coater, bar coater, knife coater, capillary coater, or microchamber doctor blade coater, etc. to apply the adhesive on the surface of the retardation film or the polarizer in a dropwise manner. It may be carried out by a method of spraying, heating and laminating a laminate including a retardation film and a polarizer with a lamination roll, a method of laminating by pressing at room temperature, or a method of UV curing.

2 is a diagram illustrating a laminated structure of a polarizing plate according to an exemplary embodiment of the present application. Specifically, the polarizing plate 103 may have a structure in which a polarizer protective film 104 / adhesive layer 105 / retardation film 101 / polarizer 102 / polarizer protective film 104 are stacked in this order. In particular, the polarizer protective film 104 adhered to the adhesive layer 105 of the polarizer protective film 104 may be removed together with the adhesive layer 105 when included in the final liquid crystal display device.

In an exemplary embodiment of the present application, a polarizer protective film is attached to one surface of the polarizer, and the retardation film according to the present application is attached to the opposite surface of the polarizer protective film to the side to which the polarizer protective film is attached. do.

In an exemplary embodiment of the present application, the polarizer protective film is a cycloolefin polymer (COP)-based film, an acrylic film, a triacetylcellulose (TAC)-based film, a cycloolefin copolymer (COC)-based film, a polynorbornene (PNB)-based film, and a polyethylene (PET)-based film. It may be made of any one or more of terephtalate)-based films.

In an exemplary embodiment of the present application, a liquid crystal display device including the polarizing plate is provided.

In addition, an exemplary embodiment of the present application is a liquid crystal cell; an upper polarizing plate provided in the upper layer of the liquid crystal cell; a lower polarizing plate provided in the lower layer of the liquid crystal cell; and a backlight unit provided on a lower layer of the lower polarizing plate, wherein at least one of the upper polarizing plate and the lower polarizing plate includes: a polarizer; and a retardation film according to an exemplary embodiment of the present application disposed on one surface of the polarizer.

In an exemplary embodiment of the present application, the upper polarizing plate includes the polarizer; and the retardation film, wherein the retardation film is disposed to face the liquid crystal cell.

In an exemplary embodiment of the present application, the lower polarizing plate includes the polarizer; and the retardation film, wherein the retardation film is disposed to face the backlight unit.

The upper polarizing plate may include the polarizer; and the retardation film, wherein the retardation film is disposed to face the liquid crystal cell, wherein the upper polarizing plate includes the polarizer; and the retardation film, wherein the retardation film is disposed in the liquid crystal cell direction in the liquid crystal display device, and specifically, a backlight unit/lower polarizing plate/liquid crystal cell/retardation film/polarizer is laminated in this order It means having a structure.

The lower polarizing plate may include the polarizer; and the retardation film, wherein the retardation film is disposed to face the backlight unit, wherein the lower polarizing plate includes the polarizer; and the retardation film, wherein the retardation film is disposed in the backlight unit direction in the liquid crystal display device, and specifically, the backlight unit/polarizer/retardation film/liquid crystal cell/upper polarizing plate is laminated in this order It means having a structure.

In the liquid crystal display device according to the present application, when the retardation film of the upper polarizing plate is disposed to face the liquid crystal cell, or the retardation film of the lower polarizing plate is disposed to face the backlight unit, it is included in the retardation film The triazine-based birefringence regulator may have a main purpose of improving the function of the panel with a phase difference expression function rather than a main function of ultraviolet absorption.

In the present invention, the terms 'top' and 'upper' refer to a plane or direction in which a polarizing plate is disposed to face a viewer side, that is, a viewer side when the polarizing plate is mounted on a device such as a liquid crystal display. Conversely, 'bottom side' and 'bottom side' refer to the side or direction in which the polarizer is disposed to face the backlight unit, that is, opposite to the viewer, when the polarizer is mounted on the device.

The backlight unit includes a light source irradiating light from the rear surface of the liquid crystal panel, and the type of the light source is not particularly limited, and a general LCD light source such as CCFL, HCFL, or LED may be used.

3 is a diagram illustrating a liquid crystal display device according to an exemplary embodiment of the present application. Specifically, an upper polarizing plate 11 and a lower polarizing plate 12 may be stacked on both sides of the liquid crystal cell 10 , and a surface in contact with the liquid crystal cell 10 of the lower polarizing plate 12 adjacent to the backlight unit 14 and It may have a structure in which the protective film 13 is laminated on the opposite surface. A polarizing plate according to an exemplary embodiment of the present application may be used as the upper polarizing plate 11 and the lower polarizing plate 12 , and preferably, a polarizing plate according to an exemplary embodiment of the present application may be used as the lower polarizing plate 12 .

The protective film is the same as the content of the above-described polarizer protective film.

In an exemplary embodiment of the present application, an organic light emitting device (OLED) panel; and an upper polarizing plate provided on the organic light emitting diode (OLED) panel, wherein the upper polarizing plate includes: a polarizer; and an organic light emitting diode (OLED) display including the retardation film according to the present application disposed on one surface of the polarizer.

The organic light emitting diode (OLED) display including the retardation film according to the present application has excellent anti-reflection characteristics not only in the front direction of the screen but also in the oblique direction.

4 shows a schematic stacking structure of an organic light emitting diode (OLED) display according to the present application, and the stacking order of the polarizer and the retardation film may be changed depending on the use thereof.

In the exemplary embodiment of the present application, the structure of the organic light emitting diode (OLED) display is not particularly limited, and any known structure may be employed. Since these structures are well known in the art, detailed descriptions thereof will be omitted.

Typically, in the organic light emitting device (OLED) display, an anode and a cathode are stacked on a substrate, and at least one organic thin film layer may be provided between the anode and the cathode, and the organic thin film layer may be Green) and a light emitting layer for realizing blue colors, and may additionally include at least one of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.

In an exemplary embodiment of the present application, the emission layer may include a host and a dopant.

Hereinafter, through specific examples of the invention, the action and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

< manufacturing example >

< comparative example >

One) comparative example One

10.0 g of EASTMAN Chemical's CAB 381-20, a cellulose acetate butyrate (CAB), was dissolved in 66.9 g of ethyl acetate, followed by stirring to prepare a transparent solution. EASTMAN Chemical's CAB 381-20, a cellulose acetate butyrate, had a number average molecular weight of 70,000 g/mol. After preparing the polymer solution, it was cast to a certain thickness on a 100um PET film (SKC) using an applicator, dried in a drying oven at 50°C for 5 minutes, and then dried in a drying oven at 110°C for 10 minutes. After peeling the dried coating film from the PET film, it was uniaxially stretched 2.0 times at a temperature of 160° C. with a Lab stretching machine, and the thickness and phase difference were measured and shown in Table 2 below.

2) comparative example 2

10.0 g of EASTMAN Chemical's CAP 482-20, which is cellulose acetate propionate (CAP), was dissolved in 66.9 g of ethyl acetate, followed by stirring to prepare a transparent solution. EASTMAN Chemical's CAP 482-20, a cellulose acetate propionate, has a number average molecular weight of 75,000 g/mol. After preparing the polymer solution, it was cast to a certain thickness on a 100um PET film (SKC) using an applicator, dried in a drying oven at 50°C for 5 minutes, and then dried in a drying oven at 110°C for 10 minutes. After peeling the dried coating film from the PET film, it was uniaxially stretched 2.0 times at a temperature of 165° C. with a Lab stretching machine, and the thickness and phase difference were measured and shown in Table 2 below.

3) comparative example 3

DOW's ETHOCEL™ Standard 10, 3.5 g of ethyl cellulose, and EASTMAN Chemical's CAB 381-2, 6.5 g, of cellulose acetate butyrate (CAB) were dissolved in 66.9 g of ethyl acetate, followed by stirring to prepare a transparent solution. . At this time, ETHOCEL™ Standard 10, an ethyl cellulose, had a number average molecular weight of 25,000 g/mol, and EASTMAN Chemical CAB 381-2, a cellulose acetate butyrate, had a number average molecular weight of 40,000 g/mol. After preparing the polymer solution, it was cast to a certain thickness on a 100um PET film (SKC) using an applicator, dried in a drying oven at 50°C for 5 minutes, and then dried in a drying oven at 110°C for 10 minutes. After peeling the dried coating film from the PET film, it was uniaxially stretched 2.5 times at 150° C. with a Lab stretching machine, and the thickness and phase difference were measured and shown in Table 2 below.

4) Example One

0.5 g of DOW's ETHOCEL™ Standard 100 as ethyl cellulose and 9.5 g of EASTMAN Chemical's CAB 381-20 as cellulose acetate butyrate were dissolved in 66.9 g of ethyl acetate, followed by stirring to prepare a transparent solution. At this time, ETHOCEL™ Standard 100, an ethyl cellulose, had a number average molecular weight of 63,000 g/mol, and EASTMAN Chemical CAB 381-20, a cellulose acetate butyrate, had a number average molecular weight of 70,000 g/mol. After preparing the polymer solution, it was cast to a certain thickness on a 100um PET film (SKC) using an applicator, dried in a drying oven at 50°C for 5 minutes, and then dried in a drying oven at 110°C for 10 minutes. After peeling the dried coating film from the PET film, it was uniaxially stretched 2.0 times at a temperature of 155° C. with a Lab stretching machine, and the thickness and phase difference were measured and shown in Table 2 below.

5) Example 2

1.0 g of DOW's ETHOCEL™ Standard 100, which is ethyl cellulose, and 9.0 g of EASTMAN Chemical's CAB 381-20, which is cellulose acetate butyrate, were dissolved in 66.9 g of ethyl acetate, followed by stirring to prepare a transparent solution. It proceeded in the same manner as in Example 1.

6) Example 3 to 15

It was prepared in the same manner as in Example 1 except that the composition and content included in each retardation film composition were changed according to Table 1 below, and the thickness and retardation were measured and shown in Table 2 below.

7) Example 16

3.0 g of DOW's ETHOCEL™ Standard 100 as ethyl cellulose and 7.0 g of EASTMAN Chemical's CAP 482-20 as cellulose acetate propionate were dissolved in 66.9 g of ethyl acetate, followed by stirring to prepare a transparent solution. Afterwards, 10.0 phr of polyethylene adipate, a product of Sigma aldrich's number average molecular weight of 10000 g/mol, was dissolved in the resin solid content of 100, followed by additional stirring to prepare a transparent solution. After preparing the polymer solution, it was cast to a certain thickness on a 100um PET film (SKC) using an applicator, dried in a drying oven at 50°C for 5 minutes, and then dried in a drying oven at 110°C for 10 minutes. After peeling the dried coating film from the PET film, it was uniaxially stretched 2.5 times at 160° C. with a Lab stretching machine, and the thickness and phase difference were measured and shown in Table 2 below.

resin 1 ratio
(%) resin 2 ratio
(%) additive ratio
(phr) menstruum stretching temperature
(℃) draw ratio Comparative Example 1 - - CAB-381-20 100 - - Ethyl acetate 160 2.0X Comparative Example 2 - - CAP-482-20 100 - - Ethyl acetate 165 2.0X Comparative Example 3 ETHOCEL™ Standard 10 35 CAB-381-2 65 - - Ethyl acetate 150 2.5X Example 1 ETHOCEL™ Standard 100 5 CAB-381-20 95 - - Ethyl acetate 155 2.0X Example 2 ETHOCEL™ Standard 100 10 CAB-381-20 90 - - Ethyl acetate 155 2.0X Example 3 ETHOCEL™ Standard 100 15 CAB-381-20 85 - - Ethyl acetate 155 2.0X Example 4 ETHOCEL™ Standard 100 20 CAB-381-20 80 - - Ethyl acetate 155 2.0X Example 5 ETHOCEL™ Standard 100 5 CAB-381-20 95 - - Ethyl acetate 155 2.5X Example 6 ETHOCEL™ Standard 100 10 CAB-381-20 90 - - Ethyl acetate 155 2.5X Example 7 ETHOCEL™ Standard 100 10 CAB-381-20 90 - - Methylene chloride, Ethyl alcohol 155 2.5X Example 8 ETHOCEL™ Standard 100 15 CAB-381-2 85 - - Methylene chloride, Ethyl alcohol 150 2.5X Example 9 ETHOCEL™ Standard 10 15 CAB-381-20 85 - - Methylene chloride, Ethyl alcohol 155 2.5X Example 10 ETHOCEL™ Standard 10 25 CAB-381-2 85 - - Methylene chloride, Ethyl alcohol 150 2.5X Example 11 ETHOCEL™ Standard 100 15 CAB-381-20 85 - - Ethyl acetate 155 2.5X Example 12 ETHOCEL™ Standard 100 20 CAB-381-20 80 - - Ethyl acetate 155 2.5X Example 13 ETHOCEL™ Standard 100 10 CAP-482-20 90 - - Ethyl acetate 165 2.5X Example 14 ETHOCEL™ Standard 100 20 CAP-482-20 80 - - Ethyl acetate 165 2.5X Example 15 ETHOCEL™ Standard 100 30 CAP-482-20 70 - - Ethyl acetate 165 2.5X Example 16 ETHOCEL™ Standard 100 30 CAP-482-20 70 Poly(ethylene adipate) 10 Ethyl acetate 160 2.5X

film thickness
(μm) R _in (550)
(nm) R _th (550)
(nm) Required thickness to satisfy R _{in (550) 100nm} R _in (450)/ R _in (550) R _in (650)/ R _in (550) Comparative Example 1 123.6 147.6 -73.6 83.7 0.90 1.06 Comparative Example 2 119.2 81.2 -42.4 146.8 0.72 1.16 Comparative Example 3 60.2 327.8 -180.4 18.4 0.99 1.01 Example 1 56.6 122.2 -63.4 46.3 0.92 1.05 Example 2 66.8 157 -74.8 42.5 0.94 1.03 Example 3 54.4 162.8 -87.6 33.4 0.96 1.03 Example 4 54.4 172.8 -89.2 31.5 0.97 1.02 Example 5 55.2 128.4 -70.4 43.0 0.91 1.05 Example 6 55.6 162.4 -83.8 34.2 0.93 1.04 Example 7 47.4 143.0 -79.8 33.1 0.94 1.03 Example 8 47.0 144.4 -94.2 32.5 0.95 1.03 Example 9 43.8 109.6 -71.6 40.0 0.94 1.04 Example 10 47.6 181.2 -124.6 26.7 0.97 1.02 Example 11 49.8 162.6 -95.8 30.6 0.95 1.03 Example 12 52 193.8 -112.4 26.8 0.96 1.02 Example 13 54.2 87.4 -54.6 62.0 0.85 1.08 Example 14 42.6 115 -72.0 37.0 0.93 1.04 Example 15 40.8 141.2 -91.6 28.9 0.96 1.02 Example 16 41.2 115.4 -74.6 35.7 0.96 1.02

As can be seen in Examples 1 to 16 of Tables 1 and 2, in the retardation film composition included in the retardation film according to the present invention, from the group consisting of cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP) It was confirmed that by simultaneously including a specific content of a cellulosic resin including at least one selected and an ethyl cellulose resin having flat wavelength dispersibility, the wavelength dispersibility was changed to implement a specific reverse wavelength dispersibility. .

In particular, the retardation film composition included in the retardation film according to the present invention is R _in It contains an ethyl cellulose resin having high flat wavelength dispersibility, which satisfies reverse wavelength dispersibility and at the same time R _in (550) has a characteristic that can be formed to have a low thickness to satisfy 100 nm, that is , When the retardation film according to the present application is used as an OLED polarizing plate or LCD wide viewing angle polarizing plate, a certain level of R _in (550) value must be satisfied, and as the retardation film composition according to the present application is included, R _in (550) ) can be formed to have a low thickness to satisfy 100 nm, so it is possible to reduce the cost of manufacturing the polarizer itself, and it can be confirmed that it has the characteristics of achieving slimming of the display including the same.

In addition, since the retardation film comprising the retardation film composition according to the present invention has reverse wavelength dispersion in which the retardation value increases as the light wavelength increases, a relatively uniform degree of retardation can be generated in a wide optical band. As a result, it was confirmed that when the retardation film of the present invention is applied to a polarizing plate or a liquid crystal display device, it has characteristics that can realize superior color, luminance, and optical properties compared to the prior art.

In the case of Comparative Examples 1 and 2 of Tables 1 and 2, the retardation film composition does not contain an ethyl cellulose resin having flat wavelength dispersibility, and R _in (550) is formed to have a high thickness to satisfy 100 nm. Accordingly, as the thickness of the final polarizing plate increased, it was confirmed that it was difficult to slim the display device including the same, and in the case of Comparative Example 3 of Tables 1 and 2, cellulose acetate butyrate (CAB) included in the retardation film composition ) resin and cellulose acetate propionate (CAP) in the case of out of the content range of the ethyl cellulose resin having a cellulose resin and flat wavelength dispersibility containing at least one selected from the group consisting of R _in (450) / R _in (550) is out of the range of Equation 1 according to the present application, and it can be confirmed that the desired wavelength dispersion (reverse wavelength dispersion) does not appear.

101: retardation film
102: polarizer
103: polarizing plate
104: polarizer protective film
105: adhesive layer
10: liquid crystal cell
11: upper polarizer
12: lower polarizer
13: protective film
14: backlight unit
15: organic light emitting device panel
16: organic light emitting device display

Claims (12)

Cellulose-based resin comprising at least one selected from the group consisting of cellulose acetate butyrate (CAB) resin and cellulose acetate propionate (CAP); and ethyl cellulose resin having flat wavelength dispersibility;
A retardation film composition comprising a retardation film composition or a retardation film comprising a cured product thereof,
The cellulose-based resin: ethyl cellulose resin having flat wavelength dispersibility satisfies 99:1 to 66:34,
The retardation film is a retardation film that satisfies the following formulas 1 and 2:
[Equation 1]
0.5 < R _in (450)/R _in (550) < 0.99
[Equation 2]
1.0 < R _in (650)/R _in (550) < 1.2
In the above formulas 1 and 2,
R _in (λ) is the in-plane retardation at the wavelength λ nm, and is the value of _{(n x} -n _{y ) xd,}
The n _x is the refractive index in the slow axis (Slow Axis) direction of the retardation film plane,
Wherein n _y is the refractive index in the fast axis direction of the retardation film plane,
d is the thickness of the retardation film. The method according to claim 1,
The cellulose-based resin is a cellulose acetate butyrate (CAB) resin having reverse wavelength dispersion retardation film. The method according to claim 1,
The thickness of the retardation film _{to satisfy R in} (550) of 100 nm is 65 μm or less of the retardation film. The method according to claim 1,
The retardation film composition is a retardation film comprising at least one selected from the group consisting of a solvent, a dispersant, an antioxidant, an adhesion enhancer, a photoinitiator, a thermal initiator, and a tackifier. The method according to claim 1,
The retardation film, the retardation film that satisfies the following formulas 3 and 4:
[Equation 3]
20nm ≤ R _in (550) ≤ 300nm
[Equation 4]
-300nm ≤ R _th (550) ≤ 0nm
In Equations 3 and 4,
R _in (550) is the in-plane retardation at a wavelength of 550 nm, (n _x -n _y ) is the value of xd,
R _th (550) is the thickness direction retardation at a wavelength of 550 nm, and is a value of {n _z -(n _x +n _y )/2} xd,
The n _x is the refractive index in the slow axis (Slow Axis) direction of the retardation film plane,
Wherein n _y is the refractive index in the fast axis direction of the retardation film plane,
Wherein n _z is the refractive index in the thickness direction of the retardation film,
d is the thickness of the retardation film. The method according to claim 1,
The thickness of the retardation film is 10 μm or more and 150 μm The following retardation film. polarizer; and
A polarizing plate comprising at least one retardation film of any one of claims 1 to 6. 8. The method of claim 7,
A polarizer protective film is attached to one surface of the polarizer,
A polarizing plate in which the retardation film is attached to a surface opposite to the surface to which the polarizer protective film is attached of the polarizer. liquid crystal cell;
an upper polarizing plate provided in the upper layer of the liquid crystal cell;
a lower polarizing plate provided in the lower layer of the liquid crystal cell; and
and a backlight unit provided in a lower layer of the lower polarizing plate,
At least one of the upper polarizing plate and the lower polarizing plate may include a polarizer; and the retardation film of any one of claims 1 to 6 disposed on one surface of the polarizer. 10. The method of claim 9,
The upper polarizing plate may include the polarizer; and the retardation film,
The retardation film is a liquid crystal display device that is disposed to face the liquid crystal cell. 10. The method of claim 9,
The lower polarizing plate may include the polarizer; and the retardation film,
The retardation film is disposed to face the backlight unit. organic light emitting diode (OLED) panels; and
an upper polarizing plate provided on the organic light emitting diode (OLED) panel;
An organic light emitting diode (OLED) display comprising:
The upper polarizing plate may include a polarizer; and an organic light emitting diode (OLED) display comprising the retardation film of any one of claims 1 to 6 disposed on one surface of the polarizer.

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