KR20150037447A - Retadation film and preparing method for retadation film - Google Patents

Abstract

The present invention relates to a retardation film including: a base film having a negative retardation characteristic and biaxially oriented; and a coating layer formed on at least one surface of the base film, having a positive retardation characteristic, and biaxially oriented to the width direction (TD), and to a method for preparing the retardation film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a retardation film,

The present invention relates to a retardation film and a manufacturing method thereof, and more specifically, to a retardation film that can be applied to an IPS mode liquid crystal display device as a retardation film and a method of manufacturing the retardation film.

The liquid crystal display device is spreading as an optical display device because its power consumption is lower than that of a cathode ray tube display, its volume is small, its weight is light and it is easy to carry. In general, a liquid crystal display device has a basic structure in which a polarizing plate is provided on both sides of a liquid crystal cell, and the orientation of the liquid crystal cell changes depending on whether an electric field is applied to the driving circuit, and the characteristics of light transmitted through the polarizing plate are changed, Is visualized. At this time, the path of light and the birefringence change depending on the incident angle of the incident light because the liquid crystal is an anisotropic material having two different refractive indices.

Due to such characteristics, the liquid crystal display device has a problem that the contrast ratio, which is a measure for how much the image is seen clearly according to the viewing angle, is changed and the gray scale inversion phenomenon occurs, It has disadvantages. In order to overcome such disadvantages, an optical compensation film for developing an optical retardation generated in a liquid crystal cell is used for a liquid crystal display device.

Various liquid crystal modes have been developed in order to secure a clear image quality and a wide viewing angle in a liquid crystal display device. Typical examples thereof include Double Domain TN (Twisted Nematic), ASM (axially symmetric aligned microcell), OCB blend, VA, multidomain VA, SE, surrounding electrode, patterned VA, in-plane switching (IPS), and fringe-field switching (FFS) . Each of these modes has a unique liquid crystal arrangement and has inherent optical anisotropy.

Therefore, in order to manifest the phase difference due to the optical anisotropy of these liquid crystal modes, an optically anisotropic phase difference film corresponding to each mode is required. Especially, in the case of the IPS mode, since the liquid crystal having a positive dielectric anisotropy is horizontally aligned, the optical anisotropy at the oblique angle in the non-driven state is not greater than that of the other modes, so that an excellent viewing angle can be obtained by using the isotropic protective film alone . In this case, however, compensation for the absorption axis of the polarizer at the high inclination angle is not performed at all, so that the contrast may be deteriorated due to the viewing angle and color modulation may occur. Therefore, in order to secure a perfect viewing angle, the IPS mode liquid crystal display should also use an appropriate retardation film do.

A structure in which a phase difference film for an IPS mode is composed of a multilayer film of two or more layers is actually presented. In order to realize a multilayer film, a method of stacking different films using an adhesive is proposed. Alternatively, a process of coating a material exhibiting a phase difference with liquid crystal after the stretched film is prepared through a separate stretching process is separately performed.

However, when the adhesive layer is laminated using an adhesive as described above, it is difficult to reduce the thickness of the film due to the presence of the adhesive layer. If the optical axes of the two films to be laminated are not precisely arranged, In addition, when a process of coating a material exhibiting a phase difference with liquid crystal after the stretched film is prepared through a separate stretching process is performed separately, there are drawbacks in that the manufacturing process is complicated and the manufacturing cost is increased because it is subjected to various steps.

Therefore, it is possible to appropriately adjust the retardation value in the plane direction and the retardation value in the thickness direction of the IPS mode liquid crystal display device, to have an excellent effect of improving the viewing angle when applied to the IPS mode liquid crystal display device, And a method for producing the same.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide an IPS mode liquid crystal display device capable of appropriately adjusting the retardation value in the plane direction and the retardation value in the thickness direction, And a phase difference film which can be manufactured in a thin form and can be manufactured by a simple process, and a method for producing the same.

On the other hand, the object of the present invention is not limited to the above description. It will be understood by those of ordinary skill in the art that there is no difficulty in understanding the additional problems of the present invention.

In one aspect, the present invention provides a biaxially stretched substrate film having negative retardation characteristics; And a coating layer formed on at least one side of the base film and uniaxially stretched in the width direction (TD), having a positive retardation characteristic.

On the other hand, the retardation film preferably satisfies the following formulas (1) and (2).

(1): 50 nm < R _{in , total} < 300 nm

(2): 10 nm < R _{th , total} < 300 nm

In the above formulas (1) and (2), R _{in , total} is the retardation value of the entire retardation film measured in the visible light wavelength band, R _{th and total} are the retardation values of the entire retardation film measured in the visible light wavelength band Value.

It is preferable that the retardation film has an Nz value of less than 1, which is represented by the following formula (3).

Equation _{(3): Nz = R th} , total / R in, total

R _{in , total} is the retardation value of the entire retardation film, R _{th, total} is the thickness retardation value of the entire retardation film, and R _{in , total} and R _th, All of which are retardation values measured in the visible light wavelength band.

The retardation film preferably satisfies the following formulas (4) and (5).

(4): 0 nm < R _{in , a} < 250 nm

(5): 10 nm < R _{th , a} < 300 nm

In the above formulas (4) and (5), R _{in , a} is the retardation value in the plane direction of the base film measured in the visible light wavelength band, and R _{th , a} is the retardation value in the thickness direction of the base film measured in the visible light wavelength band .

It is also preferable that the retardation film satisfies the following formulas (6) and (7).

(6): 50 nm < R _{in , b} < 300 nm

(7): -290 nm < R _{th , b} < 0 nm

In the formulas (6) and (7), R _{in , b} is the retardation value in the plane direction of the coating layer measured in the visible light wavelength band, and R _{th , b} is the retardation value in the thickness direction of the coating layer measured in the visible light wavelength band.

It is preferable that the retardation film satisfies the following formula (8).

(8): n _{x , total} > n _{z , total} > n _{y , total}

In the formula (8), n _{x and total} are refractive indices in the direction in which the refractive index in the plane direction of the entire retardation film is the maximum (that is, in the slow axis direction), and n _{y and total} are perpendicular the direction the direction of the refractive index (that is, fast axis direction), n _z, is the refractive index of the _total of the entire retardation film thickness direction, in this case, the n _{x, total,} n _{y, total,} n _{z and total} are measured values in the visible light wavelength band.

On the other hand, the base film may be a film comprising a polyvinylcarbazole, a polyvinylnaphthalene, a styrene resin, a blending resin containing an acrylic resin and a styrene resin, or an acrylic resin containing a styrene monomer .

Meanwhile, the coating layer may include a polycarbonate resin, a polyimide resin, a cyclic olefin resin, or a polyamide resin.

The thickness of the retardation film is preferably 5 to 80 탆.

Meanwhile, the retardation film is preferably used for a liquid crystal display device of a planar switching (IPS) mode.

The present invention also provides a liquid crystal display device including the retardation film.

According to another aspect of the present invention, there is provided a method of manufacturing a polarizing plate, comprising: uniaxially stretching a base film having negative retardation characteristics in a longitudinal direction (MD); Forming a coating layer on at least one surface of the substrate film uniaxially stretched in the longitudinal direction (MD) using a polymer material having a positive retardation characteristic; And uniaxially stretching the base film on which the coating layer is formed in the transverse direction (TD).

On the other hand, in the step of uniaxially stretching in the longitudinal direction (MD), the base film is preferably stretched by 1.1 to 4.0 times.

In the uniaxially stretching in the longitudinal direction (MD), the base film is preferably stretched to a thickness of 20 to 250 탆.

Also, in the step of forming the coating layer, it is preferable that the coating layer is coated to a thickness of 1 to 30 탆.

In the step of uniaxially stretching in the transverse direction (TD), it is preferable that the base film on which the coating layer is formed is stretched by 1.1 to 4.0 times.

In the step of uniaxially stretching in the transverse direction (TD), it is preferable that the base film on which the coating layer is formed is stretched to a thickness of 5 to 80 탆.

In addition, the solution of the above-mentioned problems does not list all the features of the present invention. The various features of the present invention and the advantages and effects thereof will be more fully understood by reference to the following specific embodiments.

The retardation film according to the present invention has a retardation property suitable for use as an IPS mode retardation film, and thus has an excellent effect of improving the viewing angle when applied to an IPS mode retardation film. In addition, although it is a multi-layer structure, since an adhesive layer is unnecessary, it can be manufactured in a thin shape.

Further, the retardation film according to the present invention is manufactured by coating and stretching a polymer material having a positive retardation property on a base film having a negative retardation property, which is uniaxially stretched, and there is no need for a separate alignment process, And a method of coating the retardation-developing substance is very simple.

In addition, since the retardation film according to the present invention does not require a step of laminating with an adhesive, there is no decrease in optical characteristics due to the presence of the adhesive layer or deviation of the retardation plate axis.

First, terms used in this specification are defined.

(1) where n _x is the refractive index in the direction in which the refractive index in the plane direction is the maximum (that is, the slow axis direction), and n _y is the refractive index in the direction perpendicular to the slow axis in the plane direction , and n _z means the refractive index in the thickness direction. The above n _x , n _y , and n _z are generally measured in a visible light wavelength band, more specifically, light having a wavelength of 400 to 780 nm. For example, it can be measured at 450 nm, 550 nm or 650 nm.

On the other hand, n _{x and total} are refractive indices in the direction in which the refractive index in the plane direction of the entire retardation film becomes the maximum (that is, in the slow axis direction), and n _{y and total} are the directions in the direction perpendicular to the slow axis of the entire retardation film , The phase in the fast axis direction), and n _{z , total} is the refractive index in the thickness direction of the entire retardation film.

On the other hand, the n _x, n _y, n _z, and is possible to measure by the conventional method well known in the art, for example, can be measured using the equipment of Axoscan Axomatrics社.

(2) R _in denotes a retardation value _in the visible direction _in a visible light wavelength band, more specifically, _in a light having a wavelength of 400 to 780 nm. The retardation value R _in = (n _x -n _y ) It becomes. In this case, n _x is the direction in which the refractive index in the plane direction is the maximum, n _y is the direction perpendicular to the x axis, d is the thickness of the base film, the retardation film or the coating layer .

On the other hand, R _{in , a} represents the in-plane retardation value of the base film _{in the} visible light wavelength band, more specifically, the light having a wavelength of 400 to 780 nm, R _{in and b} denote the visible light wavelength bands, more specifically wavelengths of 400 to 780 nm R _{in and total} represent the retardation values of the entire retardation film including the base film and the coating layer in the visible light wavelength band, more specifically, light having a wavelength of 400 to 780 nm, .

On the other hand, _in the R it can be measured by a known method known in the art and, for example, can be measured using the equipment of Axoscan Axomatrics社.

(3) R _th is obtained by the visible light wavelength region, and more specifically by means of the thickness retardation value of from 400 to 780nm wavelength light, the thickness retardation value _{R th = × d (n z} -n y) It becomes. In this case, n _x is the direction in which the refractive index in the plane direction becomes maximum at the wavelength, n _y is the direction perpendicular to the x axis, n _z is the thickness direction, d is the thickness The thickness of the film, the retardation film or the coating layer.

In the meantime, _{Rth , a} represents the retardation value in the thickness direction of the base film in the visible light wavelength band, more specifically, in the wavelength range of 400 to 780 nm, _{Rth , b} is the visible light wavelength band, more specifically, the wavelength in the range of 400 to 780 nm R _{th , total} represents the retardation value in the thickness direction of the whole retardation film including the base film and the coating layer in the visible light wavelength band, more specifically, the light having the wavelength of 400 to 780 nm as the retardation value in the thickness direction of the coating layer .

On the other hand, the R _th can be determined by well-known methods known in the art and, for example, can be measured using the equipment of Axoscan Axomatrics社.

(4) Nz is in a visible light wavelength band, than that specifically means a ratio of the retardation value in the thickness direction to the retardation value in the plane direction in the 400 to 780nm wavelength light, Nz = R _{th, total} / R _{in, total} . For example, Nz may be a ratio of the retardation value in the thickness direction to the retardation value in the plane direction in the light having a wavelength of 450 nm, 550 nm, or 650 nm.

(5) The positive retardation property means that the maximum refractive index is expressed along the stretching direction at the time of stretching, and the negative retardation property means that the maximum refractive index is expressed along the direction perpendicular to the stretching direction at the time of stretching.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

The inventors of the present invention have conducted intensive studies to solve the above problems. As a result, they have found that a film having negative phase difference is uniaxially stretched in a machine direction, a polymer material having a positive phase difference is coated, It is possible to achieve the same object, and the present invention has been completed.

More specifically, the retardation film of the present invention has a negative retardation property and is a biaxially stretched base film; And a coating layer formed on at least one surface of the base film and having a positive retardation characteristic and uniaxially stretched in the width direction (TD).

At this time, it is preferable that the retardation film satisfies the following formulas (1) and (2). According to the studies of the present inventors, when the retardation film of the present invention satisfies the following formulas (1) and (2), it has been shown that the IPS mode liquid crystal display device has excellent viewing angle improving effect when used as a retardation film.

(1): 50 nm < R _{in , total} < 300 nm

(2): 10 nm < R _{th , total} < 300 nm

In the above formulas (1) and (2), R _{in , total} is the retardation value of the entire retardation film measured in the visible light wavelength band, R _{th and total} are the retardation values of the entire retardation film measured in the visible light wavelength band Value. That is, in the retardation film of the present invention, R _{in , total} and R _{th, total} are light in a visible light wavelength band, more specifically, light of any wavelength of 400 to 780 nm, for example, 450 nm, 550 nm, or 650 nm (1) and (2) even when measured by light.

The retardation film preferably has a retardation value in the range of 50 to 200 nm or 60 to 150 nm, more preferably 80 to 130 nm, in the entire retardation film measured in the visible light wavelength band. It is particularly preferable that the thickness direction retardation value of the entire retardation film measured in the visible light wavelength band of the retardation film is 30 to 200 nm or 50 to 150 nm, more preferably 60 to 100 nm. In this case, the above-described viewing angle improving effect can be more effectively expressed.

The retardation film preferably has an Nz value of less than 1, more preferably 0.3 to 0.9, particularly preferably 0.5 to 0.7, expressed by the following formula (3). In this case, it is very suitable for use as a retardation film of a liquid crystal display device of various modes, in particular, an IPS mode liquid crystal display device.

Equation _{(3): Nz = R th} , total / R in, total

R _{in , total} is the retardation value of the entire retardation film, R _{th, total} is the thickness retardation value of the entire retardation film, and R _{in , total} and R _th, All of which are retardation values measured in the visible light wavelength band. That is, even if the retardation film of the present invention measures Nz in the visible light wavelength band, more specifically, light having any wavelength of 400 to 780 nm, for example, light having a wavelength of 450 nm, 550 nm, or 650 nm, It is preferable to satisfy it.

The retardation film preferably satisfies the following formulas (4) and (5).

(4): 0 nm < R _{in , a} < 250 nm

(5): 10 nm < R _{th , a} < 300 nm

In the above formulas (4) and (5), R _{in , a} is the retardation value in the plane direction of the base film measured in the visible light wavelength band, and R _{th , a} is the retardation value in the thickness direction of the base film measured in the visible light wavelength band . That is, in the retardation film of the present invention, R _{in , a} and R _{th , a} are light in any wavelength range of visible light wavelength band, more specifically 400 to 780 nm wavelength, for example, 450 nm, 550 nm, or 650 nm (4) and (5) even when measured by light.

It is also preferable that the retardation film satisfies the following formulas (6) and (7).

(6): 50 nm < R _{in , b} < 300 nm

(7): -290 nm < R _{th , b} < 0 nm

In the formulas (6) and (7), R _{in , b} is the retardation value in the plane direction of the coating layer measured in the visible light wavelength band, and R _{th , b} is the retardation value in the thickness direction of the coating layer measured in the visible light wavelength band. That is, in the retardation film of the present invention, R _{in , b,} and R _{th , b} are light in any wavelength range of visible light wavelength band, more specifically 400 to 780 nm, for example, 450 nm, 550 nm, or 650 nm It is preferable to satisfy the above-mentioned expressions (6) and (7) even when measured by light.

When the base film and the coating layer of the retardation film of the present invention have the retardation value in the plane direction and the retardation in the thickness direction, the retardation value and the retardation value in the thickness direction of the entire retardation film are appropriately applied .

It is preferable that the retardation film satisfies the following formula (8). In this case, it can be very usefully applied to the IPS mode liquid crystal display as a retardation compensation film.

(8): n _{x , total} > n _{z , total} > n _{y , total}

In the formula (8), n _{x and total} are refractive indices in the direction in which the refractive index in the plane direction of the entire retardation film is the maximum (that is, in the slow axis direction), and n _{y and total} are perpendicular the direction the direction of the refractive index (that is, fast axis direction), n _z, is the refractive index of the _total of the entire retardation film thickness direction, in this case, the n _{x, total,} n _{y, total,} n _{z and total} are measured values in the visible light wavelength band. That is, even when the retardation film of the present invention is measured in the visible light wavelength band, more specifically, light having any wavelength of 400 to 780 nm, for example, light having a wavelength of 450 nm, 550 nm, or 650 nm, It is preferable to satisfy it.

On the other hand, the retardation film of the present invention satisfying at least one of the above-mentioned formulas (1) to (8) can be produced by suitably controlling the base material, the raw material for forming the coating layer, the stretching condition and the like.

First, in the present invention, the raw material of the base film may be any high molecular substance having a negative retardation property, and the kind thereof is not particularly limited. For example, polyvinylcarbazole, polyvinylnaphthalene, a styrene resin, a blending resin including an acrylic resin and a styrene resin, and an acrylic resin including a styrene monomer can be used.

At this time, the styrenic resin may be used without particular limitation as long as it contains a styrene-based monomer as a main component. Examples of the styrenic monomer include but are not limited to styrene,? -Methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, ? -Methylstyrene, 4-fluoro-? -Methylstyrene, 4-chlorostyrene, 2,4,6-trimethylstyrene, cis-? -Methylstyrene, trans-? methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2,3 2-chlorostyrene, 4-fluorostyrene, 4-fluorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, octachlorostyrene, 2- Hydroxystyrene, 2-hydroxystyrene, 4-hydroxystyrene, and the like can be used in combination. Among them, And more preferably in the α- methyl styrene. These may be used alone or in combination.

In addition to the above styrene type monomer, the styrene type resin may also be used in combination with a styrene type monomer in combination of two or more kinds of maleic anhydride type monomer, maleimide type monomer, acrylonitrile type monomer and the like. For example, the styrene-based resin includes styrene-based monomers; And at least one monomer selected from the group consisting of maleic anhydride-based monomer, maleimide-based monomer and acrylonitrile-based monomer.

Examples of the maleic anhydride monomer include maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, propyl maleic anhydride, isopropyl maleic anhydride, cyclohexyl maleic anhydride and phenyl maleic anhydride. Can be; Examples of the maleimide-based monomer include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, For example; Examples of the acrylonitrile-based monomer include acrylonitrile, methacrylonitrile, ethacrylonitrile, and phenyl acrylonitrile. However, the present invention is not limited thereto.

More specifically, the styrenic resin includes, but is not limited to, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer,? -Methylstyrene-acrylonitrile copolymer, N-phenylmaleimide-? -Methylstyrene-acrylonitrile copolymer, N-phenylmaleimide-styrene-acrylonitrile copolymer, N-phenylmaleimide-a-methylstyrene-styrene-acrylonitrile copolymer and the like.

The acrylic resin includes a (meth) acrylic monomer as a main component, and includes not only a homopolymer resin composed of a (meth) acrylic monomer but also a copolymer resin in which other monomers other than a (meth) acrylic monomer are copolymerized.

The (meth) acrylic monomer is not limited to acrylate and methacrylate but also includes derivatives of acrylate and methacrylate. Examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n -butyl Methacrylate, t -butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxy methyl methacrylate, Acrylates such as ethyl acrylate, propyl acrylate, n -butyl acrylate, t -butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, Acrylate, oligomers thereof, etc. Among them, Methacrylate, one or more preferably alkyl (meth) acrylates such as methyl acrylate, is not limited thereto. These may be used alone or in combination.

On the other hand, in order to improve heat resistance, the acrylic resin may include a maleic anhydride monomer, a maleimide monomer, and the like, other than the (meth) acrylic monomer. Among them, it is more preferable to include a maleic anhydride-based monomer or a maleimide-based monomer. Examples of the maleic anhydride monomer include maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, propyl maleic anhydride, isopropyl maleic anhydride, cyclohexyl maleic anhydride and phenyl maleic anhydride. ; Examples of the maleimide-based monomer include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, But are not limited thereto. These may be used alone or in combination.

On the other hand, in order to further improve the negative retardation property, the acrylic resin may contain a styrene monomer as a monomer other than the (meth) acrylic monomer. Although not limited thereto, it is more preferable that styrene or? -Methylstyrene is included among the styrene-based monomers. These may be used alone or in combination.

On the other hand, the acrylic resin may be used in combination with (meth) acrylic monomers by mixing two or more kinds of styrenic monomers, maleic anhydride monomers, maleimide monomers, and the like. For example, the acrylic resin may include (meth) acrylic monomers; And one or more monomers selected from the group consisting of styrene-based monomers, maleic anhydride-based monomers and maleimide-based monomers.

More specifically, the acrylic resin includes, but is not limited to, cyclohexyl maleic anhydride-methyl methacrylate copolymer, N-cyclohexyl maleimide-methyl methacrylate copolymer, styrene-cyclohexyl maleic anhydride- Methyl methacrylate copolymer, styrene-N-cyclohexylmaleimide-methyl methacrylate copolymer,? -Methylstyrene-N-cyclohexylmaleimide-methyl methacrylate copolymer,? -Methylstyrene-N-phenyl Maleimide-methyl methacrylate copolymer,? -Methylstyrene-N-cyclohexylmaleimide-methyl methacrylate-cyclohexyl methacrylate copolymer, and the like.

Meanwhile, in the blending resin comprising the styrene resin and the acrylic resin, the styrene resin is preferably about 1 to about 99 parts by weight, more preferably about 5 to about 80 parts by weight per 100 parts by weight of the blending resin, 10 to 70 parts by weight. When the content of the styrene-based resin is less than 1 part by weight, there is a problem that it is difficult to prepare a retardation film which gives a desired retardation value due to lowering of the retardation development. Therefore, there is a problem that the thickness of the film Lt; / RTI &gt;

On the other hand, when a styrene-based monomer is contained in the acrylic resin, the acrylic resin may be used as a polymer material having a negative retardation property without blending with the styrene-based resin. In this case, the acrylic resin may include (meth) acrylic monomers; Styrene-based monomers; And optionally one or more monomers selected from the group consisting of a maleic anhydride monomer and a maleimide monomer, and examples thereof include (meth) acrylic monomers, styrene monomers, maleic anhydride monomers, maleimide monomers Are the same as those described above.

In addition, the polyvinylcarbazole has a carbazole skeleton in the molecule such as poly (9-vinylcarbazole), and polyvinylcarbazole generally used in the art can be used without any particular limitation.

The polyvinylnaphthalene has a naphthalene skeleton in the molecule such as poly (2-vinylnaphthalene), and polyvinylnaphthalene generally used in the art can be used without particular limitation.

Next, in the present invention, the raw material of the coating layer may be any polymer material having a positive retardation characteristic, and the kind thereof is not particularly limited. For example, a polycarbonate resin, a polyimide resin, a cyclic olefin resin, a polyamide resin, or the like can be used.

The polycarbonate resin may include a repeating unit represented by the following general formula (1).

[Chemical Formula 1]

In Formula 1, X is a divalent group containing at least one benzene ring, aliphatic ring, or aliphatic chain, and 1 is an integer of 5 to 10,000.

In the above formula (1), examples of the divalent group containing at least one benzene ring include, but are not limited to, those selected from the group consisting of the following structural formulas. At this time, the divalent group may be connected to the main chain of the polycarbonate resin at any position of the benzene ring.

In the above formula (1), the divalent group containing at least one aliphatic ring may include, but is not limited to, 4 to 14, or 4 to 10, or 4 to 8 ring atoms of a non- Quot; refers to a cyclic, cyclic, bicyclic or tricyclic hydrocarbon moiety. The ring atoms may contain oxygen as well as carbon atoms. At this time, the divalent group may be connected to the main chain of the polycarbonate resin at any position of the aliphatic ring.

In the formula 1, the divalent group containing at least one aliphatic chain may be a straight or branched chain having 1 to 10, or 1 to 8, or 1 to 6 carbon atoms, &Lt; / RTI &gt; At this time, the divalent group can be connected to the main chain of the polycarbonate resin at any position of the aliphatic chain.

The polyimide resin can be used without particular limitation as long as it has an imide group in the main chain. For example, polyimide, polyetherimide and the like can be used. have.

The cyclic olefin-based resin may be a cyclic olefin-based resin well-known in the art without any particular limitation, and examples thereof include, but are not limited to, cycloolefin polymer (COP), cycloolefin copolymer COC) may be used.

The polyamide resin can be used without particular limitation, provided that the polyamide resin has an amide group in the main chain. For example, the polyamide resin may include repeating units represented by the following formula 2 or 3 . &Lt; / RTI &gt;

(2)

In the general formula 2, A is C _{2 -16} aliphatic hydrocarbon chains, C _{5 -14} aliphatic hydrocarbon ring or an aromatic C _{6 -14} hydrocarbon chain, X ₁ is a halogen atom or a C _{1 -6} alkyl group, a is 0 to 3, and n is an integer of 5 to 10,000.

Herein, in the formula (A), the C _{2 -16} aliphatic hydrocarbon chain means a hydrocarbon portion of 2 to 16, or 4 to 14, or 6 to 12 carbon atoms, and includes, but is not limited to, methylene An ethylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, a nonanemethylene group, a decamethylene group, an undecamethylene group, a dodecamethylene group, a tridecamethylene group, A methylene group, a pentadecamethylene group, a hexadecamethylene group, and the like.

Further, in A of Formula 2, C _{5 -14} aliphatic hydrocarbon ring of 5 to 14, or 5 to 10, or 5 to 6 ring carbon cyclic saturated or unsaturated non-aromatic mono-, bicyclic Refers to a tricyclic hydrocarbon moiety and includes, but is not limited to, a cycloalkane ring such as a cyclopentane ring or a cyclohexane ring, a cycloalkene ring such as a cyclopentene ring, a cyclohexene ring, or a cyclooctene ring, And the like.

Further, in A of Formula 2, C _{6 -14} aromatic hydrocarbon ring means a monocyclic, bicyclic or tricyclic aromatic hydrocarbon portion having 6 to 14, or 6 to 12 ring atoms, and this But are not limited to, benzene rings, naphthalene rings, anthracene rings, biphenyl rings, and the like.

On the other hand, in the above formula (2), the bonding position of the polyamide resin of A with the main chain is not particularly limited and may be an asymmetric position or a symmetrical position. For example, when A is a cyclohexane ring, it may be a cyclohexane ring in which the 1,3 carbon is bonded to the main chain, or a cyclohexane ring in which the 1,4 carbon is bonded to the main chain.

Further, in X ₁ of the formula 2, C _{1 - 6} alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t- butyl group can be given. Examples. At this time, X ₁ is substituted with hydrogen at an arbitrary position of A.

(3)

In Formula 3, B and C are each independently a C _{2 -16} aliphatic hydrocarbon chain, a C _{5 -14} aliphatic hydrocarbon ring, or a C _{6 -14} aromatic hydrocarbon ring, and X ₂ and X ₃ are each independently a halogen atom or a c _{1 -6} alkyl group, b and c are each independently an integer of 0 ~ 3, m is an integer of 5 to 10,000.

In the above formulas (B) and (C), the C _{2 -16} aliphatic hydrocarbon chain means a hydrocarbon portion of 2 to 16, or 4 to 14, or 6 to 12 carbon atoms, , Methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, Tetradecamethylene group, tetradecamethylene group, pentadecamethylene group, hexadecamethylene group and the like.

Further, in the above formula B and C 3, C _{5 -14} aliphatic hydrocarbon ring of 5 to 14, or 5 to 10, or 5 to 6 ring carbon cyclic saturated or unsaturated non-aromatic mono, Bicyclic and tricyclic hydrocarbon moieties, and includes, but is not limited to, cycloalkane rings such as cyclopentane rings and cyclohexane rings, cycloalkane rings such as cyclopentene rings, cyclohexene rings, and cyclooctene rings, ) Rings, and the like.

Further, in the above formula 3 B and C, C _{6 -14} aromatic hydrocarbon ring means a monocyclic, bicyclic or tricyclic aromatic hydrocarbon portion having a dog 6 to 14, or 6 to 12 ring atoms, and But are not limited to, benzene rings, naphthalene rings, anthracene rings, biphenyl rings, and the like.

In the above formula (3), the bonding position of the polyamide resin of B and C with the main chain is not particularly limited, and may be an asymmetric position or a symmetrical position. For example, when B or C is a cyclohexane ring, it may be a cyclohexane ring in which the 1,3 carbon is bonded to the main chain, or a cyclohexane ring in which the 1,4 carbon is bonded to the main chain.

In the above Formula 3, X ₂ and X ₃ of the C _{1 - 6} alkyl group as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t- butyl group can be given. Examples . X ₂ is substituted and bonded to hydrogen at any position of B, and X ₃ is substituted and bonded to hydrogen at any position of C;

On the other hand, though not limited thereto, it is more preferable that the polyamide resin contains a repeating unit represented by the following formula (4). In this case, the positive phase difference characteristic can be realized more effectively.

[Chemical Formula 4]

In the above Formula 4, D is a C _{2 -16} aliphatic hydrocarbon chain, E ₁ and E ₂ are each independently a cyclohexane ring or a benzene ring, X _4, X ₅ and X ₆ is a halogen atom or a C each independently ₁ and _-6 alkyl group, X ₇ is a single bond, a methylene group or a dimethylmethylene group, d, e1 and e2 are each independently an integer of 0 ~ 2, k is an integer of 5 to 10,000.

In the formula (D), the C _{2 -16} aliphatic hydrocarbon chain refers to hydrocarbon moieties of 2 to 16, or 4 to 14, or 6 to 12 carbon atoms, including, but not limited to, methylene An ethylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, a nonanemethylene group, a decamethylene group, an undecamethylene group, a dodecamethylene group, a tridecamethylene group, A methylene group, a pentadecamethylene group, a hexadecamethylene group, and the like.

Further, in the above Formula 4 E ₁ and E _2, wherein E ₁ and E ₂ are, and among them more preferable, especially cyclohexane ring, wherein, with the E ₁ and E ₂ of poly amide-based resin main chain of the The bonding position is not particularly limited and may be an asymmetric position or a symmetric position. For example, when E ₁ and E ₂ are cyclohexane rings, they may be a cyclohexane ring in which the 1,3 carbon is bonded to the main chain, or a cyclohexane ring in which the 1,4 carbon is bonded to the main chain.

In Formula 4, X ₄ and X ₅ And C ₁ of X _{6 - 6} in an alkyl group is a methyl group, may be mentioned an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t- butyl group. Examples. At this time, the X ₄ is bonded is substituted on hydrogen from any desired position of D, X ₅ is bonded is substituted on hydrogen from any desired position of E _1, X ₆ is optionally substituted on hydrogen from any desired position of the E ₂ .

Meanwhile, in the present invention, the thickness of the retardation film is preferably 5 to 80 탆, and may be, for example, 10 to 70 탆 or 15 to 65 탆. The retardation film of the present invention is advantageous in that it can be thinned to a thickness of 80 탆 or less since the film is not laminated using an adhesive. However, when the thickness of the film is less than 5 mu m, the thickness becomes too thin, and the handling properties of the retardation film and the polarizing plate may become poor.

Next, a method for producing the retardation film of the present invention will be described.

A method of producing a retardation film of the present invention comprises: uniaxially stretching a base film having negative retardation characteristics in a longitudinal direction (MD); Forming a coating layer on at least one surface of the substrate film uniaxially stretched in the longitudinal direction (MD) using a polymer material having a positive retardation characteristic; And uniaxially stretching the base film on which the coating layer is formed in a width direction (TD).

The method of producing a retardation film of the present invention can obtain a desired retardation film only by two consecutive stretches, and can produce a retardation film which can be applied to an IPS mode liquid crystal display device by a simpler process.

First, in the present invention, the base film may be formed by using a polymer material having a negative retardation characteristic and using a film forming method well known in the art, for example, extrusion molding, solution casting, calender molding, Alternatively, a multilayer film may be produced through co-extrusion with other polymers and used. Alternatively, commercially available films having negative retardation characteristics may be used. Specific examples of the polymer material having negative phase difference characteristics are the same as those described above.

On the other hand, the step of uniaxially stretching the base film having the negative retardation characteristics of the present invention in the longitudinal direction (MD) can be carried out by a stretching method well known in the art. For example, when the glass transition temperature of the base film is Tg, the film is stretched by 1.1 to 4.0 times in a roll-to-roll manner at a temperature of (Tg-20) ° C to (Tg + 30) . &Lt; / RTI &gt;

More specifically, in the present invention, the step of uniaxially stretching in the longitudinal direction is preferably a step of stretching the base film to 1.1 to 4.0 times It is preferably stretched to, for example, 1.2 to 3.5 times or 1.3 to 3.0 times. If the stretching ratio is less than 1.1 times, toughness of the film is lowered, and the produced retardation film may be difficult to apply to the polarizing plate. If the stretching ratio is more than 4.0 times, the film may be broken during stretching, Film production can be difficult.

In the present invention, the uniaxially stretching in the longitudinal direction is preferably performed such that the thickness of the base film is 20 to 250 占 퐉. For example, the thickness is 25 to 230 占 퐉 or 30 to 200 占 퐉 So that it can be stretched. If the thickness of the film after uniaxial stretching in the longitudinal direction is less than 20 占 퐉, the thickness of the film becomes too thin when the film is stretched in the width direction, and the handling properties of the film and the polarizing plate may become poor, And if it exceeds 250 탆, it may be difficult to make the polarizer thinner.

In the present invention, the step of uniaxially stretching in the longitudinal direction is preferably performed at a temperature of (Tg-20) DEG C to (Tg + 30) DEG C, where Tg is the glass transition temperature of the base film , And more preferably at a temperature of about (Tg) ° C to (Tg + 20) ° C. In this case, when the uniaxial stretching in the longitudinal direction is performed at a temperature lower than (Tg-20) DEG C, the storage elastic modulus of the film may be lowered, and thus the loss elastic modulus may become larger than the storage elastic modulus. Further, when the polymerization is carried out at a temperature higher than (Tg + 30) DEG C, the orientation of the polymer chain may be alleviated and lost. On the other hand, the glass transition temperature can be measured by a differential scanning calorimeter (DSC). For example, in the case of using a differential scanning calorimeter (DSC), when a sample of about 10 mg is sealed in a special pen and heated at a constant temperature, the endothermic heat and the heat generation amount of the material due to the phase change occur, The transition temperature can be measured.

A step of uniaxially stretching the base film having negative phase difference characteristics in the longitudinal direction and then forming a coating layer on at least one side of the base film using a polymer material having a positive phase difference characteristic on one side. The step of forming the coating layer may be performed by a method well known in the art. For example, a composition including a polymer material having a positive phase difference and a solvent may be applied to the substrate by a microgravure coating method, a comma coating method, a bar coating method, a roller coating method, a spin coating method, a printing method, a dip coating method, , A blade coating method, a gravure printing method, and the like, followed by drying. Specific examples of the polymer material having the positive phase difference are the same as described above. Examples of usable solvents include methylene chloride, chloroform, tetrahydrofuran (THF), 1,3-dioxane, cyclopentanone, N- Alcohols such as methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), ethanol and methanol, water and the like. These solvents may be used alone or in combination of two or more.

Meanwhile, in the step of forming the coating layer having the positive phase retardation characteristic, it is preferable to coat the coating layer so that the thickness of the coating layer is about 1 to 30 mu m. For example, when the thickness of the coating layer is 2 to 20 mu m, . &Lt; / RTI &gt; In this case, the thickness of the coating layer is related to the property of exhibiting the retardation. When the coating layer is coated with a thickness of less than 1 탆, the film exhibits a positive retardation and may not exhibit a desired retardation. On the other hand, If the thickness of the retardation film is more than the thickness of the retardation film, the characteristic of developing the positive retardation may become too large, and the thickness of the retardation film may become thin.

If necessary, in order to improve the adhesive force between the base film and the coating layer, the step of uniaxially stretching the base film having the negative retardation characteristics in the machine direction and the step of forming the coating layer having the positive retardation characteristics, The surface of the base film may be corona treated.

When the coating layer is formed on the base film through the above process, the base film on which the coating layer is formed is stretched in the transverse direction (TD). When the film is stretched in the width direction, the base film having a negative retardation characteristic and the coating layer having a positive retardation characteristic can be simultaneously stretched by one stretching process. Therefore, the base film having the negative retardation characteristics is biaxially stretched in the longitudinal direction and the width direction, and the coating layer having the positive retardation property is uniaxially stretched in the width direction.

On the other hand, the step of uniaxially stretching the base film in which the coating layer of the present invention is formed in the transverse direction (TD) can be similarly conducted by a stretching method well known in the art. For example, when the glass transition temperature of the base film is Tg, the stretching can be carried out by a method of stretching the film in the width direction at a temperature of (Tg-20) ° C to (Tg + 30) ° C using a tenter stretcher at a stretching ratio of 1.1 to 4.0 .

More specifically, in the present invention, the step of uniaxially stretching in the transverse direction comprises: 1.1 to 4.0 times It is preferably stretched to, for example, 1.2 to 3.5 times or 1.3 to 3.0 times. If the stretching ratio is less than 1.1 times, toughness of the film is lowered, and the produced retardation film may be difficult to apply to the polarizing plate. If the stretching ratio is more than 4.0 times, the film may be broken during stretching, Film production can be difficult.

Also, in the present invention, the uniaxially stretching in the width direction is preferably performed such that the thickness of the base film on which the coating layer is formed is 5 to 80 占 퐉, for example, 10 to 70 占 퐉 or 15 to 65 占 퐉 have. At this time, the thickness of the retardation film after the uniaxially stretching in the width direction becomes the thickness of the final film, and when the thickness of the final film is less than 5 mu m, the thickness of the film becomes too thin and the handling property of the film and the polarizing plate becomes poor And may be bent or broken during the manufacturing process of the film or the polarizing plate or during the handling of the product. If it exceeds 80 탆, it may be difficult to thin the polarizing plate.

In the present invention, the step of uniaxially stretching in the transverse direction is preferably performed at a temperature of (Tg-20) DEG C to (Tg + 30) DEG C, where Tg is the glass transition temperature of the base film , And more preferably at a temperature of about (Tg) ° C to (Tg + 20) ° C. In this case, when the uniaxial stretching in the longitudinal direction is performed at a temperature lower than (Tg-20) DEG C, the storage elastic modulus of the film may be lowered, and thus the loss elastic modulus may become larger than the storage elastic modulus. Further, when the polymerization is carried out at a temperature higher than (Tg + 30) DEG C, the orientation of the polymer chain may be alleviated and lost. On the other hand, the glass transition temperature can be measured by a differential scanning calorimeter (DSC). For example, in the case of using a differential scanning calorimeter (DSC), when a sample of about 10 mg is sealed in a special pen and heated at a constant temperature, the endothermic heat and the heat generation amount of the material due to the phase change occur, The transition temperature can be measured.

Meanwhile, when the retardation film according to the present invention is applied to an IPS mode liquid crystal display device, the retardation film has an excellent viewing angle improving effect and can be suitably used as a retardation film for an IPS mode liquid crystal display device.

Meanwhile, the present invention provides a polarizing plate comprising at least one or more of the retardation films. In this case, the retardation film according to the present invention may be directly attached to one side or both sides of the polarizer, or may be attached to a protective film of a polarizing plate having a protective film on both sides of the polarizer.

When the retardation film is directly attached to one surface or both surfaces of the polarizer, for example, the structure may be a structure of an upper protective film / polarizer / retardation film, retardation film / polarizer / lower protective film, retardation film / Protective film or an upper protective film / polarizer / lower protective film / retardation film.

Meanwhile, the present invention provides a liquid crystal display device including at least one or more of the retardation films. For example, the present invention provides an IPS mode liquid crystal display device including at least one or more retardation films.

The liquid crystal display may include a liquid crystal cell and a first polarizing plate and a second polarizing plate respectively provided on both surfaces of the liquid crystal cell, and the retardation film may be disposed between the liquid crystal cell and the first polarizing plate and / And may be provided between the polarizing plates. That is, a retardation film may be provided between the first polarizing plate and the liquid crystal cell, and a retardation film may be provided between the second polarizing plate and the liquid crystal cell, or between the first polarizing plate and the liquid crystal cell, 2 or more .

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the invention by the following examples.

Example  One

Acrylonitrile copolymer (LG Chemical, SAN82TR, acrylonitrile content: 20% by weight) and poly (cyclohexylmaleimide-co-methylmethacrylate) (LMmmA, 830HR) At a weight ratio of 250 占 폚 and 200 rpm using a twin extruder to prepare a resin composition. An undrawn film having a width of 800 mm and a thickness of 170 占 퐉 was prepared using the T-die cast film under the condition of 250 占 폚. The unstretched film was stretched in the longitudinal direction at a temperature of 125 캜 in a roll to roll manner to obtain a uniaxially stretched film.

A solution (solvent 1,3-dioxolane) containing 18% by weight of polycarbonate (LGPC, DVD1080) containing a benzene ring in the molecule was applied to the uniaxially stretched film using a micro gravure coater, Respectively.

The coated film was stretched twice in the transverse direction at a temperature of 125 캜 using a tenter stretching machine to prepare a retardation film having a thickness of 65 탆.

Example  2

A uniaxially stretched film was prepared in the same manner as in Example 1, and a solution (solvent 1,3-dioxolane) containing 10% by weight of thermoplastic polyimide (SABIC, XH6050) in a uniaxially stretched film was coated on a microgravure coater And coated to a thickness of 4 탆.

The coated film was stretched twice in the transverse direction at a temperature of 125 캜 using a tenter stretching machine to prepare a retardation film having a thickness of 61 탆.

Example  3

An unoriented film having a width of 800 mm and a thickness of 60 占 퐉 was produced by using a? -methylstyrene-acrylonitrile copolymer (LG Chemistry AMSAN, Tg 119 ° C) at 250 ° C using a T- The unstretched film was stretched twice in the longitudinal direction at a temperature of 130 캜 in a roll to roll manner to produce a uniaxially stretched film.

A solution (solvent 1,3-dioxolane) containing 10 wt% of polyethersimide (Sabic, Ultem) was applied to the uniaxially stretched film using a micro gravure coater and coated to a thickness of 4 탆.

The coated film was stretched twice in the transverse direction at a temperature of 130 캜 using a tenter stretching machine to prepare a retardation film having a thickness of 21 탆.

Example  4

A uniaxially stretched film was prepared in the same manner as in Example 1, and then a solution (solvent chloroform) in which 20 wt% of a cycloolefin copolymer (Ticona, Topas) was contained in the uniaxially stretched film was coated with a microgravure coater And coated to a thickness of 20 탆.

The coated film was stretched twice in the width direction at a temperature of 125 캜 using a tenter stretching machine to prepare a retardation film having a thickness of 68 탆.

At this time, the experimental results of Examples 1 to 4 are shown in Table 1 below. More specifically, in Table 1 below, the retardation values of the coating layer, the film layer and the composite film are described, and the Nz values of the composite film are described. At this time, the retardation value was measured based on light having a wavelength of 550 nm, and the retardation value was measured using an Axoscan's Axoscan measuring apparatus.

division Coating layer phase difference
(R _in / R _th , nm) Film layer phase difference
(R _in / R _th , nm) Composite film phase difference
(R _in / R _th , nm) Composite film Nz Example 1 125 / -26 15/121 109/70 0.6 Example 2 130 / -46 12/125 115/60 0.5 Example 3 123 / -40 10/128 112/72 0.6 Example 4 125 / -40 12/125 113/73 0.6

As shown in Table 1, it can be seen that the retardation film of the present invention exhibits a retardation value and a Nz value suitable for the retardation film for a phase switching liquid crystal display apparatus, while using a manufacturing method that goes through a simplified step .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (17)

A biaxially stretched base film having negative retardation characteristics; And
A retardation film formed on at least one surface of the base film and having a positive retardation characteristic and uniaxially stretched in a width direction (TD).
The method according to claim 1,
Wherein the retardation film satisfies the following expressions (1) and (2).
(1): 50 nm < R _{in , total} < 300 nm
(2): 10 nm < R _{th , total} < 300 nm
In the above formulas (1) and (2)
R _{in and total} are plane retardation values of the entire retardation film measured in the visible light wavelength band,
_{Rth , total} is the thickness direction retardation value of the entire retardation film measured in the visible light wavelength band.
The method according to claim 1,
Wherein the retardation film has a Nz value of less than 1, represented by the following formula (3).
Equation _{(3): Nz = R th} , total / R in, total
In the above formula (3)
R _{in , total} is the retardation value in the plane direction of the entire retardation film,
_{Rth , total} is the retardation value in the thickness direction of the entire retardation film,
In this case, R _{in , total} and R _{th , total} are the retardation values measured in the visible light wavelength band.
The method of claim 1, wherein
Wherein the retardation film satisfies the following expressions (4) and (5).
(4): 0 nm < R _{in , a} < 250 nm
(5): 10 nm < R _{th , a} < 300 nm
In the above formulas (4) and (5)
R _{in , a} is the retardation value in the plane direction of the base film measured in the visible light wavelength band,
_{Rth , a} is the retardation value in the thickness direction of the base film measured in the visible light wavelength band.
The method according to claim 1,
Wherein the retardation film satisfies the following formulas (6) and (7).
(6): 50 nm < R _{in , b} < 300 nm
(7): -290 nm < R _{th , b} < 0 nm
In the above formulas (6) and (7)
R _{in , b} is the retardation value in the plane direction of the coating layer measured in the visible light wavelength band,
_{Rth , b} is the retardation value in the thickness direction of the coating layer measured in the visible light wavelength band.
The method according to claim 1,
Wherein the retardation film satisfies the following formula (8).
(8): n _{x , total} > n _{z , total} > n _{y , total}
In the above formula (8)
n _{x , total} is the refractive index in the direction in which the refractive index in the plane direction of the entire retardation film becomes maximum (that is, in the slow axis direction)
n _{y , total} is the refractive index of the entire retardation film in the direction perpendicular to the slow axis (i.e., the fast axis direction)
n _{z , total} is the refractive index in the thickness direction of the entire retardation film,
In this case, the n _{x, total,} n _{y, total} And n _{z , total} is the value measured in the visible light wavelength band.
The method according to claim 1,
Wherein the base film comprises an acrylic resin including a polyvinylcarbazole, polyvinylnaphthalene, a styrene resin, a blending resin comprising an acrylic resin and a styrene resin, or an acrylic resin containing a styrene monomer. film.
The method according to claim 1,
Wherein the coating layer comprises a polycarbonate resin, a polyimide resin, a cyclic olefin resin, or a polyamide resin.
The method according to claim 1,
Wherein the retardation film has a thickness of 5 to 80 占 퐉.
The method according to claim 1,
Wherein the retardation film is for a planar switching (IPS) mode liquid crystal display.
A liquid crystal display device comprising the retardation film according to any one of claims 1 to 10.
Uniaxially stretching a base film having negative retardation characteristics in a longitudinal direction (MD);
Forming a coating layer on at least one surface of the substrate film uniaxially stretched in the longitudinal direction (MD) using a polymer material having a positive retardation characteristic; And
Uniaxially stretching the base film on which the coating layer is formed in the transverse direction (TD);
Wherein the retardation film has a thickness of 100 to 500 nm.
13. The method of claim 12,
And the step of uniaxially stretching in the longitudinal direction (MD) comprises stretching the base film to 1.1 to 4.0 times.
13. The method of claim 12,
Wherein the uniaxially stretching in the longitudinal direction (MD) comprises stretching the base film to a thickness of 20 to 250 mu m.
13. The method of claim 12,
Wherein the step of forming the coating layer comprises coating the coating layer with a thickness of 1 to 30 탆.
13. The method of claim 12,
Wherein the uniaxially stretching in the transverse direction (TD) comprises stretching the base film on which the coating layer is formed by 1.1 to 4.0 times.
13. The method of claim 12,
Wherein the uniaxially stretching in the transverse direction (TD) comprises stretching the base film on which the coating layer is formed to a thickness of 5 to 80 탆.