KR101674244B1 - Retardation film and liquid crystal display including the same - Google Patents

Abstract

The present invention relates to an acrylic film having negative retardation characteristics; And an amide-based film having a negative C type or negative B type phase difference, and a liquid crystal display including the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a retardation film and a liquid crystal display device including the retardation film.

The present invention relates to a retardation film and a liquid crystal display device including the retardation film, and more particularly, to a retardation film having a structure in which an acrylic film having negative retardation characteristics is laminated on an amide film having a retardation of negative C type or negative B type Film and a liquid crystal display device including the same.

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. In particular, since the liquid crystal having a positive dielectric anisotropy is horizontally aligned in the IPS mode, the optical anisotropy in the non-driven state is not greater than the other modes, which is advantageous in that an excellent viewing angle can be secured even 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.

On the other hand, in the case of the IPS mode liquid crystal display device, it is difficult to sufficiently realize the compensating effect when the uniaxial or biaxially stretched film is used alone. Currently, the IPS mode retardation film is a multilayer film composed of two or more layers, A liquid crystal film on which a liquid crystal layer is coated, and the like are generally used. Typically, a nematic liquid crystal is coated on a uniaxially stretched COP (cyclic olefin polymer) film to compensate the viewing angle. However, in the case of such a liquid crystal film, even if the alignment of the liquid crystal and the thickness of the coating slightly vary, the phase difference of the entire compensation film is greatly changed, which makes it difficult to control the phase difference. In addition, it is disadvantageous in that it is difficult to commercialize it because of high manufacturing cost due to expensive liquid crystal unit price.

Further, although a retardation film for coating a non-liquid crystalline retardation developing material having a negative C characteristic to an acrylic retardation film and controlling a retardation value in a plane direction and a retardation value in a thickness direction has been developed, an acrylic film is usually used in an aromatic Hydrocarbon, or organic chlorine, and when such a retardation developing substance is coated using such a solvent, problems such as poor adhesion, increase in brittleness, decrease in phase difference and occurrence of stain may occur .

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems described above, and it is an object of the present invention to provide an acrylic film having negative retardation characteristics by laminating an acrylic film having negative retardation characteristics on an amide film having a retardation of negative C type or negative B type, And which can be applied to an IPS mode liquid crystal display device, and a liquid crystal display device including the same.

In one aspect, the present invention relates to an acrylic film having negative retardation characteristics; And an amide-based film having a negative C type or negative B type phase difference.

At this time, it is preferable that the retardation film 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 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.

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

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.

It is preferable that the acrylic film having the negative retardation characteristics satisfy the following formulas (4) and (5).

(4): 50 nm < R _{in , a} < 250 nm

(5): 80 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 acrylic film having the negative retardation characteristic measured in the visible light wavelength band,

R _{th , a} is the retardation value in the thickness direction of the acrylic film having negative retardation characteristics measured in the visible light wavelength band.

It is preferable that the amide-based film having the negative C type retardation satisfies the following formulas (6) and (7).

(6): -50 nm <R _{in , b 1} <50 nm

(7): -200 nm < R _{th , b 1} < 0 nm

In the above formulas (6) and (7)

R _{in and b 1} are retardation values in the plane direction of an amide-based film having a negative C-type retardation measured in a visible light wavelength band,

_{Rth and b1} are retardation values in the thickness direction of the amide type film having the negative C type retardation measured in the visible light wavelength band.

It is preferable that the amide-based film having the negative B-type retardation satisfies the following formulas (8) and (9).

Equation _{(8): 0nm <R in} , b2 <100nm

Equation _{(9): -200nm <R th} , b2 <0nm

In the above formulas (8) and (9)

R _{in, b2} is the plane retardation value of the amide-based film having a retardation of the negative type B measured in the visible light wavelength band,

_{Rth and b2} are retardation values in the thickness direction of an amide type film having a negative B type retardation measured in a visible light wavelength band.

It is preferable that the retardation film satisfies the following formula (10).

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

In the above formula (10)

n _{x , total} is a refractive index in a 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)

n _{y , total} is the refractive index in the direction perpendicular to the slow axis of the entire retardation film (i.e., the fast axis direction)

n _{z , total} is the refractive index in the thickness direction of the entire retardation film,

At this time, the n _{x , total} , n _{y , total} , n _{z , total} is the value measured in the visible light wavelength band.

On the other hand, the amide-based film having the negative C type or negative B type retardation may include a polyamide type resin containing units represented by the following formula (1) or (2).

[Chemical Formula 1]

In Formula 1,

A is a C _{2 -16} aliphatic hydrocarbon chain, a C _{5 -14} aliphatic hydrocarbon ring or a C _{6 -14} aromatic hydrocarbon ring,

X ₁ is a halogen atom or a C _{1 -6} alkyl group,

a is an integer of 0 to 3,

n is an integer of 5 to 10,000.

(2)

In Formula 2,

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,

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 to 3,

and m is an integer of 5 to 10,000.

On the other hand, it is more preferable that the amide-based film having the negative C type or negative B type retardation includes a polyamide type resin containing a unit represented by the following formula (3).

(3)

In Formula 3,

D is a C _{2 -16} aliphatic hydrocarbon chain,

E ₁ and E ₂ are each independently a cyclohexane ring or a benzene ring,

And X _4, X ₅ and X ₆ is an alkyl group each independently a halogen atom or a C _{1 -6,}

X ₇ is a single bond, a methylene group or a dimethylmethylene group,

d, e1 and e2 are each independently an integer of 0 to 2,

and k is an integer of 5 to 10,000.

On the other hand, the thickness of the amide-based film having the negative C type or negative B type phase difference is preferably 5 to 40 mu m.

On the other hand, the acrylic film having negative phase difference characteristics may include a blending resin including an acrylic resin and a styrene resin, or an acrylic resin including a styrene monomer.

Here, the acrylic resin of the blending resin may be a (meth) acrylic monomer; And at least one monomer selected from the group consisting of styrene-based monomers, maleic anhydride-based monomers and maleimide-based monomers.

The styrene-based resin of the blending resin may be a styrene-based monomer; And at least one monomer selected from the group consisting of maleic anhydride-based monomer, maleimide-based monomer and acrylonitrile-based monomer.

The acrylic resin containing the styrene-based monomer may be a (meth) acrylic monomer; Styrene-based monomers; And at least one monomer selected from the group consisting of maleic anhydride-based monomers and maleimide-based monomers.

On the other hand, the acrylic film having the negative retardation characteristics may further comprise a rubber component.

On the other hand, the acrylic film having the negative retardation characteristics and the amide film having the negative C type or negative B type retardation may be adhered by an adhesive or an adhesive.

Preferably, the retardation film is for an IPS mode liquid crystal display.

In another aspect, the present invention provides a liquid crystal display device including the retardation film.

The retardation film according to the present invention is excellent in durability because it uses an amide-based film as a film having a retardation of negative C type or negative B type, and because of the high retardation property of the amide type film, a desired retardation As a result, thinning is also possible, and problems such as poor adhesion, increase in brittleness, decrease in phase difference, and occurrence of stain do not occur.

Also, the retardation film according to the present invention can easily adjust the retardation value in the plane direction and the retardation value in the thickness direction, and is excellent in the viewing angle improving effect, and can be used as an IPS mode retardation film or the like.

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, and d is the thickness of the film to be measured. For example, R _in may be a retardation value in the plane direction in the light having a wavelength of 450 nm, 550 nm, or 650 nm.

On the other hand, R _{in , a} represents the in-plane retardation value of the acrylic film _{in the} visible light wavelength band, more specifically 400 to 780 nm wavelength, R _{in and b 1} denote the visible light wavelength band, more specifically, a represents a plane direction retardation value of the amide-based film having a phase difference of a negative C-type on the light, R _{in, b2} is the visible light wavelength region, and more specifically, having a phase difference of a negative type B in the 400 to 780nm wavelength And R _{in and total} denote the retardation values of the entire retardation film 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 the maximum, n _y is the direction perpendicular to the x axis, n _z is the thickness direction, d is the film to be measured, .

On the other hand, _{Rth , a} represents the retardation value in the thickness direction of the acrylic film _{in the} visible light wavelength band, more specifically, the light having the wavelength of 400 to 780 nm _{, Rin and b1} are wavelengths in the visible light wavelength band, more specifically, 400 to 780 nm a represents the thickness retardation value of the amide-based film having a phase difference of a negative C-type on the light, R _{in, b2} is the visible light wavelength region, and more specifically, having a phase difference of a negative type B in the 400 to 780nm wavelength And R _{in and total} denote retardation values _in the plane direction of the entire retardation film in the visible light wavelength band, more specifically, light having a wavelength of 400 to 780 nm.

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.

(6) The negative C type means that n _x ? N _y > n _z is satisfied, and the negative B type means that n _x > n _y > n _z is satisfied. At this time, as described above, n _x is in the plane of the film, and the refractive index of the refractive index of the large direction, n _y is a refractive index in the direction perpendicular to the n _x direction in the plane of the film, n _z is the thickness Lt; / RTI &gt;

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 extensive research to solve the above problems. As a result, in the case of using an amide-based film having a negative C type or negative B type phase difference and an acrylic film having negative phase difference properties as a phase difference film, The present invention has been accomplished on the basis of the findings that it is easy to adjust the retardation value in the direction and the retardation value in the thickness direction, is excellent in durability, can be made thin, and can be applied to an IPS mode liquid crystal display device.

More specifically, the retardation film according to the present invention is an acrylic film having negative retardation characteristics; And an amide-based film having a negative C type or negative B type phase difference. At this time, it is preferable that the acrylic film and the amide-based film are biaxially stretched in the longitudinal direction (MD) and the transverse direction (TD).

On the other hand, the retardation film preferably 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.

It is more preferable that the retardation film has a retardation value in the range of 60 to 250 nm or 70 to 200 nm and a retardation value in the thickness direction of 20 to 250 nm or 30 to 200 nm in the entire retardation film measured in the visible light wavelength band. In this case, the above-described viewing angle improving effect can be more effectively expressed.

Further, the retardation film preferably has an Nz value of less than 1, more preferably 0.1 to 0.9, particularly preferably 0.2 to 0.8, 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

In the formula (3), R _{in, total} is the plane retardation value of the entire retardation film, R _{th, total} is the retardation value of the entire retardation film thickness direction, wherein said R _{in, total} and R _{th, total} is 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.

It is preferable that the retardation film satisfies the following expressions (4) and (5) for the acrylic film having the negative retardation characteristics. In this case, the retardation value in the plane direction and the thickness direction retardation value of the entire retardation film can be adjusted to appropriate values for application to the IPS mode retardation film.

(4): 50 nm < R _{in , a} < 250 nm

(5): 80 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 acrylic film having a negative retardation characteristic measured in a visible light wavelength band, R _{th , a} is a negative retardation Is a retardation value in the thickness direction of the acrylic film. 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 more preferable that the phase difference film has an in-plane retardation value of 70 to 200 nm and a thickness retardation value of 100 to 250 nm in the acrylic film having the negative retardation characteristic measured in the visible light wavelength band. In this case, the retardation value in the plane direction and the retardation value in the thickness direction of the entire retardation film can be more effectively adjusted to appropriate values for application as an IPS mode retardation film.

It is preferable that the retardation film satisfies the following formulas (6) and (7) as the amide-based film having the negative C type retardation. In this case, the retardation value in the plane direction and the thickness direction retardation value of the entire retardation film can be adjusted to appropriate values for application to the IPS mode retardation film.

(6): -50 nm <R _{in , b 1} <50 nm

(7): -200 nm < R _{th , b 1} < 0 nm

In the formulas (6) and (7), R _{in and b 1} are plane retardation values of an amide type film having a negative C type retardation measured in a visible light wavelength band, R _{th and b 1} are measured in a visible light wavelength band Is a thickness direction retardation value of an amide type film having a negative C type retardation. That is, in the retardation film of the present invention, R _{in , b 1} and R _{th , b 1} are visible light wavelength bands, more specifically light of any wavelength of 400 to 780 nm, for example, 450 nm, 550 nm, or 650 nm (6) and (7) even when measured by light,

It is more preferable that the phase difference film has a retardation value in the plane direction of -20 to 20 nm and a retardation in the thickness direction of -150 to 0 nm of the amide type film having the negative C type retardation measured in the visible light wavelength band. In this case, the retardation value in the plane direction and the retardation value in the thickness direction of the entire retardation film can be more effectively adjusted to appropriate values for application as an IPS mode retardation film.

It is preferable that the retardation film satisfies the following formulas (8) and (9) for the amide-based film having the negative B-type retardation. In this case, the retardation value in the plane direction and the thickness direction retardation value of the entire retardation film can be adjusted to appropriate values for application to the IPS mode retardation film.

Equation _{(8): 0nm <R in} , b2 <100nm

Equation _{(9): -200nm <R th} , b2 <0nm

In the above formula (8) and _(9), R _{in, b2} is the plane retardation value of the amide-based film having a retardation of the negative type B measured in the visible light wavelength range, R _{th, b2} is measured in the visible light wavelength band Is the thickness direction retardation value of the amide type film having the negative B type phase difference. That is, the retardation film of the invention wherein R _{in, b2} and R _{th, b2} is the visible light wavelength region, and more specifically, from 400 to 780nm in which any of the wavelengths of the wavelength of light, for example, of 450nm, 550nm, or 650nm wavelength (8) and (9) are satisfied even when measured by light.

On the other hand, it is more preferable that the phase difference film has the retardation value in the plane direction of 0 to 80 nm and the retardation value in the thickness direction of -150 to 0 nm of the amide type film having the negative B type retardation measured in the visible light wavelength band. In this case, the retardation value in the plane direction and the retardation value in the thickness direction of the entire retardation film can be more effectively adjusted to appropriate values for application as an IPS mode retardation film.

It is preferable that the retardation film satisfies the following formula (10). In this case, it can be very usefully applied to the IPS mode liquid crystal display as a retardation compensation film.

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

In the formula (10), n _{x, total} is the refractive index of a phase difference film plane direction and the refractive index of the entire direction is maximum (that is, the direction of the slow axis), n _{y, total} is perpendicular to the slow axis of the entire retardation film 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 (10) can be produced by suitably controlling a raw material for forming an acrylic film and an amide film, .

First, the acrylic film having the negative retardation characteristic preferably includes an acrylic resin as a main component, and the acrylic resin includes a (meth) acrylic monomer as a main component and is a homopolymer resin composed of a (meth) acrylic monomer But also a copolymer resin in which other monomers other than the (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 further improve the negative retardation property of the acrylic film having negative retardation characteristics, the acrylic resin may include 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, in order to improve the heat resistance of the acrylic film having a negative retardation property, the acrylic resin may contain a monomer other than the (meth) acrylic monomer, such as a lactone monomer, a lactam monomer, a glutaric anhydride monomer, Maleic anhydride-based monomer, maleimide-based monomer, and the like. 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 the acrylic resin, a mixture of two or more kinds of the above styrene type monomer, lactone type monomer, lactam type monomer, glutaric anhydride type monomer, glutaric imide type monomer, maleic anhydride type monomer, maleimide type monomer, And may be used together with (meth) acrylic monomers. 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.

It is further preferable that the acrylic film having the negative retardation characteristics of the present invention comprises a blending resin including an acrylic resin and a styrene resin. Generally, since acrylic resins have negative retardation characteristics, it is possible to produce a flexible B type film by uniaxial or biaxial stretching, but it is difficult to realize a high level of retardation due to the low optical anisotropy of the chain itself. However, when an acrylic resin is blended with a styrenic resin, it is possible to realize a high level of phase difference while having a negative retardation characteristic.

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 it is more preferably a α- methylstyrene. These may be used alone or in combination.

In order to improve the heat resistance of the film, the styrene-based resin may include a maleic anhydride monomer or a maleimide monomer in addition to the styrene monomer. The maleic anhydride monomer may include maleic anhydride, Methyl maleic anhydride, ethyl maleic anhydride, propyl maleic anhydride, isopropyl maleic anhydride, cyclohexyl maleic anhydride, phenyl maleic anhydride and the like; 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 improve the miscibility with the acrylic resin, the styrenic resin may include an acrylonitrile monomer in addition to the styrene monomer. As the acrylonitrile monomer, acrylonitrile, methacryl Rhenitrile, ethacrylonitrile, phenyl acrylonitrile, and the like, but the present invention is not limited thereto. These may be used alone or in combination.

On the other hand, the styrene-based resin may be used in combination with the styrene-based monomer by mixing two or more kinds of the maleic anhydride monomer, the maleimide monomer, the acrylonitrile 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.

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.

On the other hand, when the acrylic resin contains a styrene monomer, the acrylic resin may be used as it is without blending with the styrene 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.

Meanwhile, in order to improve the toughness, impact resistance and the like of the film, the acrylic film having the negative retardation characteristic may further include a rubber component. The rubber component is preferably an acrylic rubber, a rubber-acrylic graft-type core-shell polymer, or a mixture thereof, but is not limited thereto.

On the other hand, the acrylic rubber can obtain a thermoplastic resin composition having excellent transparency when the refractive index of the acrylic resin is similar to that of the rubber component, and an acrylic rubber having a refractive index of 1.480 to 1.550 can be used without any particular limitation. For example, alkyl acrylates such as butyl acrylate, 2-ethylhexyl acrylate, and the like.

In addition, the rubber-acrylic graft-type core-shell polymer can be used without particular limitation if it is a rubber-acrylic graft-type core-shell polymer having a refractive index of 1.480 to 1.550. For example, particles having a size of 50 to 400 nm made of rubber based on butadiene, butyl acrylate or butyl acrylate-styrene copolymer as a core and polymethyl methacrylate or polystyrene as a shell can be used.

On the other hand, the content of the (meth) acrylic monomer contained in the acrylic film is preferably 50 to 90 parts by weight based on 100 parts by weight of the total composition of the acrylic film. This is because when the above content range is satisfied, high durability and high transparency inherent in an acrylic resin can be sufficiently manifested.

The content of the styrene-based monomer in the acrylic film is preferably 5 to 40 parts by weight based on 100 parts by weight of the total composition of the acrylic film having the negative retardation. If the amount is less than 5 parts by weight, there is a problem that the desired retardation film is difficult to produce due to a poor retardation development. If the amount is more than 40 parts by weight, high durability and high transparency inherent to the acrylic polymer may not be sufficiently exhibited.

When the maleic anhydride monomer and / or the maleimide monomer is contained in the acrylic film, the content of the maleic anhydride monomer and / or the maleimide monomer is preferably 1 to 20 parts by weight based on 100 parts by weight of the total composition of the acrylic film having the negative retardation . When the content of the maleic anhydride monomer and / or the maleimide monomer is less than 1 part by weight, the effect of improving the heat resistance is insignificant. When the content of the maleic anhydride monomer and / or the maleimide monomer is more than 20 parts by weight, the brittleness of the film increases, This is because the phenomenon may occur.

When the acryl-based film contains the acrylonitrile-based monomer, the content of the acrylonitrile-based monomer is preferably 1 to 10 parts by weight per 100 parts by weight of the total composition of the acrylic film having the negative retardation. If the content of the acrylonitrile-based monomer is less than 1 part by weight, miscibility with the acrylic resin may decrease, and haze may be generated in the film, and haze may also occur when the amount exceeds 10 parts by weight.

When the rubber component is contained in the acrylic film, the content of the rubber component is preferably 1 to 20 parts by weight based on 100 parts by weight of the total composition of the acrylic film having the negative retardation. If the content of the rubber component is less than 1 part by weight, it may be impossible to exhibit excellent mechanical strength of the film, and the film tends to be broken, resulting in a problem in the processing step, and a problem that the optical performance is not sufficiently manifested It is because. When the content is more than 20 parts by weight, a problem that high heat resistance and high transparency inherent in an acrylic resin can not be sufficiently expressed may occur, and a problem of processing such as haze may occur in the drawing step .

On the other hand, the acrylic film can be produced by preparing a resin composition containing the acrylic resin or the like in a film form according to a method well known in the art, such as a solution casting method or an extrusion method. It is more preferable to use the extrusion method in view of the economical aspect. Optionally, an additive such as an improving agent may be added in the film production process within a range that does not deteriorate the physical properties of the film, and a uniaxial or biaxial stretching step may be further performed.

The stretching process may perform longitudinal (MD) stretching, widthwise (TD) stretching, or both. In the case of performing both the longitudinal direction stretching and the widthwise stretching, either one may be stretched in the other direction, or both directions may be stretched at the same time. In addition, the stretching may be performed in one step or may be performed in multiple steps. In the case of longitudinal stretching, stretching can be performed by a speed difference between rolls, and in the case of stretching in the width direction, tenter can be used. The time of railing of the tenter is usually within 10 degrees, suppressing the bowing phenomenon occurring in the widthwise stretching, and controlling the angle of the optical axis regularly. Even when the stretching in the width direction is performed in multiple steps, the effect of suppressing the bowing can be obtained.

On the other hand, the stretching can be performed in a temperature range of (Tg-20) ° C to (Tg + 30) ° C, where Tg is the glass transition temperature of the resin composition. The temperature range refers to a range from a temperature at which the storage elastic modulus of the resin composition begins to decrease and a loss elastic modulus becomes larger than a storage elastic modulus to a temperature at which the orientation of the polymer chain is relaxed and disappears. Alternatively, the temperature during the stretching step may be the glass transition temperature of the resin composition. The glass transition temperature of the resin composition 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.

The stretching speed is preferably in the range of 1 to 100 mm / min in the case of a universal testing machine (Zwick Z010) and in the range of 0.1 to 2 m / min in the case of a pile stretching machine And the stretching magnification is preferably about 5 to 300%.

On the other hand, in order to stabilize the optical isotropy and mechanical properties of the acrylic film of the present invention, heat treatment (annealing) may be performed after stretching treatment. The heat treatment conditions are not particularly limited, and any suitable conditions known to those skilled in the art can be employed.

The thickness of the acrylic film having the negative retardation characteristics of the present invention manufactured by the above method may be in the range of 20 to 100 탆, more preferably 30 to 80 탆 or 30 to 60 탆. When the thickness is less than 20 탆, the polarizing element can not be supported properly, resulting in device shrinkage, device cracking, and curl. When the thickness exceeds 100 탆, a large amount of heat is required for uniform stretching There are problems that not only high-speed stretching is difficult but also economical.

Next, in the present invention, the amide-based film having the negative C type or negative B type retardation preferably contains a polyamide-based resin as a main component, and the polyamide-based resin is not particularly limited as long as it has an amide group in the main chain Can be used without limit. For example, although not limited thereto, the amide-based film may include a polyamide-based resin containing a unit represented by the following general formula (1) or (2).

[Chemical Formula 1]

In the above Formula 1, 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.

In the formula (1), the C _{2 -16} aliphatic hydrocarbon chain means a hydrocarbon moiety having 2 to 16, 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 1, 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.

In the formula (A), the C _{6 -14} aromatic hydrocarbon ring means a monocyclic, bicyclic or tricyclic aromatic hydrocarbon moiety having 6 to 14 or 6 to 12 ring atoms, But are not limited to, benzene rings, naphthalene rings, anthracene rings, biphenyl rings, and the like.

On the other hand, in the above formula (1), 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 symmetric 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 Formula _1, 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.

(2)

In Formula 2, 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.

Herein, in B and C of the above formula (2), the C _{2 -16} aliphatic hydrocarbon chain means a hydrocarbon part 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 B and C in the 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 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.

In the above formulas (B) and (C), the C _{6 -14} aromatic hydrocarbon ring means a monocyclic, bicyclic or tricyclic aromatic hydrocarbon moiety having 6 to 14, or 6 to 12, ring atoms But are not limited to, benzene rings, naphthalene rings, anthracene rings, biphenyl rings, and the like.

On the other hand, in the formula (2), the bonding position of the polyamide resin of B and C to the main chain is not particularly limited and may be an asymmetric position or a symmetric 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 2, 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, although not limited thereto, it is more preferable that the polyamide resin includes a repeating unit represented by the following formula (3). In this case, the positive phase difference characteristic can be realized more effectively.

(3)

In the general formula 3, 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 a hydrocarbon moiety 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 3 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 3, 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 .

On the other hand, the amide-based film having the negative C type or negative B type retardation can be obtained by preparing a resin composition containing the polyamide type resin in a film form according to a method well known in the art such as a solution casting method or an extrusion method . It is more preferable to use the extrusion method in view of the economical aspect. Optionally, an additive such as an improving agent may be added in the film production process within a range that does not deteriorate the physical properties of the film, and a uniaxial or biaxial stretching step may be further performed.

The stretching process may perform longitudinal (MD) stretching, widthwise (TD) stretching, or both. In the case of performing both the longitudinal direction stretching and the widthwise stretching, either one may be stretched in the other direction, or both directions may be stretched at the same time. In addition, the stretching may be performed in one step or may be performed in multiple steps. In the case of longitudinal stretching, stretching can be performed by a speed difference between rolls, and in the case of stretching in the width direction, tenter can be used. The time of railing of the tenter is usually within 10 degrees, suppressing the bowing phenomenon occurring in the widthwise stretching, and controlling the angle of the optical axis regularly. Even when the stretching in the width direction is performed in multiple steps, the effect of suppressing the bowing can be obtained.

On the other hand, the stretching can be performed in a temperature range of (Tg-20) ° C to (Tg + 30) ° C, where Tg is the glass transition temperature of the resin composition. The temperature range refers to a range from a temperature at which the storage elastic modulus of the resin composition begins to decrease and a loss elastic modulus becomes larger than a storage elastic modulus to a temperature at which the orientation of the polymer chain is relaxed and disappears. Alternatively, the temperature during the stretching step may be the glass transition temperature of the resin composition. The glass transition temperature of the resin composition 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.

The stretching speed is preferably in the range of 1 to 100 mm / min in the case of a universal testing machine (Zwick Z010) and in the range of 0.1 to 2 m / min in the case of a pile stretching machine And the stretching magnification is preferably about 5 to 300%.

On the other hand, in order to stabilize the optical isotropy and the mechanical properties of the amide-based film of the present invention, heat treatment (annealing) and the like can be performed after the stretching treatment. The heat treatment conditions are not particularly limited, and any suitable conditions known to those skilled in the art can be employed.

The amide-based film having the negative C type or negative B type retardation film of the present invention produced by the above-described method can exhibit a desired phase difference with a thin thickness due to the high retardation property of the amide type film, , And a thickness of 5 to 40 占 퐉, preferably 10 to 35 占 퐉 or 10 to 30 占 퐉. When the thickness of the amide-based film having the negative C type or negative B type phase difference satisfies the above-mentioned range, the phase difference film can be made thinner, and the liquid crystal display including the same can be downsized and lightweight.

Meanwhile, the retardation film of the present invention can be produced by attaching the acrylic film having the negative retardation characteristic and the amide film having the negative C type or negative B type retardation using an adhesive or an adhesive. As described above, the retardation film of the present invention can produce a film having excellent thickness and phase difference uniformity due to the structure of the film laminate having the two layers adhered by the adhesive or the pressure-sensitive adhesive as described above.

On the other hand, the adhesive or pressure-sensitive adhesive which can be used in the present invention is not particularly limited, and may be an adhesive or a pressure-sensitive adhesive widely used in the related art, such as a polyvinyl alcohol-based adhesive or pressure-sensitive adhesive, a polyurethane-based adhesive or pressure- Based adhesive or a pressure-sensitive adhesive, or a radical UV adhesive or a pressure-sensitive adhesive.

Also, it is not particularly limited that the acrylic film having the negative retardation characteristics and the amide film having the retardation of the negative C type or negative B type are adhered using an adhesive or a pressure sensitive adhesive, and a method well known in the art &Lt; / RTI &gt; For example, when an acrylic pressure-sensitive adhesive is used, the pressure-sensitive adhesive composition may be applied on the acryl-based film or the amide-based film by a known method well-known in the art, followed by laminating the two films and drying. Or an UV-curable adhesive, the adhesive composition is applied onto the amide-based film having the negative C type or negative B type phase difference, and the acrylic film having the negative retardation characteristics is lapped and then UV-cured &Lt; / RTI &gt;

The thickness of the retardation film of the present invention manufactured by the above method may be in the range of 30 to 140 탆, more preferably 40 to 115 탆 or 40 to 90 탆. Therefore, when the retardation film is applied to a liquid crystal display device, it is possible to reduce the size and weight of the liquid crystal display device.

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 conventional polarizer 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 a planar switching (IPS) mode liquid crystal display 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.

Manufacturing example  1-1: wealth Phase difference Characteristic  Acrylic film (a)

Acrylonitrile copolymer (LG Chem, LGC 82TR, acrylonitrile content 20% by weight) and poly (cyclohexylmaleimide-co-methyl methacrylate) (LGMMA, 830HR) At a weight ratio of 80:20, respectively, using a twin extruder at 250 DEG C and 200 rpm to prepare a resin composition. An undrawn film having a width of 800 mm and a thickness of 185 탆 was produced using the resin composition at 250 캜 by using a T-die kneader. The unstretched film was stretched 1.4 times in a roll-to-roll manner at a temperature of 125 DEG C in the MD direction, and then stretched 2.9 times in the TD direction using a tenter stretcher at the same temperature to obtain a film having a negative retardation To prepare an acrylic film (a). The thickness of the final stretched film was 50 탆, and the retardation values (Rin) and retardation values (Rth) in the plane direction were 100 nm and 150 nm, respectively, measured by Axoscan's Axoscan equipment.

Manufacturing example  1-2: wealth Phase difference Characteristic  Acrylic film (b)

An unstretched film of 800 mm in width and 185 탆 in thickness prepared in the same manner as in Production Example 1-1 was stretched 1.3 times in roll-to-roll manner at a temperature of 125 캜 in the MD direction, And stretched 3.1 times in the TD direction using a tenter stretcher to produce an acrylic film (b) having negative retardation characteristics. The thickness of the final stretched film was 48 탆, and the retardation value (Rin) and retardation value (Rth) in the thickness direction were 124 nm and 172 nm, respectively, measured by Axoscan's Axoscan equipment.

Manufacturing example  2-1: Negative  C type The phase difference  Branch Amide series  Film (A)

An unoriented film having a width of 800 mm and a thickness of 60 탆 was prepared using a polyamide resin having an amide bond in the main chain (Evonik CX9704) under a condition of 245 캜 by using a T-die kneader. The unstretched film was stretched twice in a roll-to-roll manner at a temperature of 145 캜 in the MD direction, and then stretched twice in the TD direction using a tenter stretcher at the same temperature to obtain a negative C type retardation (A) having a weight average molecular weight of 1,000,000 was produced. The thickness of the finally stretched film was 20 탆, and the plane direction retardation value (Rin) and thickness direction retardation value (Rth) measured by Axoscan's Axoscan equipment were 1 nm and -100 nm, respectively.

Manufacturing example  2-2: Negative  B type The phase difference  Branch Amide series  Film (B)

An unoriented film having a width of 800 mm and a thickness of 60 탆 was prepared using a polyamide resin having an amide bond in the main chain (Evonik CX9704) under a condition of 245 캜 by using a T-die kneader. The unstretched film was stretched twice in a roll-to-roll manner at a temperature of 145 캜 in the MD direction, and then stretched 2.5 times in the TD direction using a tenter stretcher at the same temperature to obtain a negative B type retardation (B) having an amide-based film. The thickness of the final stretched film was 17 탆, and the retardation value (Rin) and the retardation value (Rth) in the thickness direction were 20 nm and -90 nm, respectively, measured by Axoscan's Axoscan equipment at a wavelength of 550 nm.

Manufacturing example  2-3: Negative  C type The phase difference  Branch Amide series  Film (C)

An unoriented film having a width of 800 mm and a thickness of 60 탆 was produced using a polyamide resin having an amide bond in the main chain (Arkema G350) under a condition of 245 캜 by using a T-die film. The unstretched film was stretched twice in the MD direction at a temperature of 152 캜 in a roll-to-roll manner, and then stretched twice in the TD direction using a tenter stretcher at the same temperature to obtain a negative C type retardation (C) having an amide group-containing polymer (A). The thickness of the finally stretched film was 19 μm. The retardation value (Rin) and the retardation value in thickness (Rth) of the film were 2 nm and -97 nm, respectively, measured by Axoscan's Axoscan equipment at a wavelength of 550 nm.

Manufacturing example  2-4: Negative  B type The phase difference  Branch Amide series  Film (D)

An unoriented film having a width of 800 mm and a thickness of 60 탆 was produced using a polyamide resin having an amide bond in the main chain (Arkema G350) under a condition of 245 캜 by using a T-die film. The unstretched film was stretched twice in the MD direction at a temperature of 152 캜 in a roll-to-roll manner, and then stretched 2.5 times in the TD direction at the same temperature using a tenter stretcher to obtain a negative B type retardation (D) having an amide-based film. The thickness of the final stretched film was 16 탆, and the retardation value (Rin) in the plane direction and the retardation value (Rth) in the thickness direction were 18 nm and -88 nm at a wavelength of 550 nm measured by an Axoscan equipment of Axometrics.

Example  One

The amide-based film (A) prepared in Preparation Example 2-1 was applied to the acrylic film (a) prepared in Preparation Example 1-1 and an acrylic adhesive to prepare a composite retardation film. The thickness of the final composite retardation film was 72 탆.

Example  2

The amide-based film (A) prepared in Preparation Example 2-1 was bonded to the acrylic film (b) prepared in Preparation Example 1-2 and an acrylic adhesive to prepare a composite retardation film. The thickness of the final composite retardation film thus produced was 70 탆.

Example  3

The amide-based film (B) prepared in Preparation Example 2-2 was bonded to the acrylic film (b) prepared in Preparation Example 1-2 and an acrylic adhesive to prepare a composite retardation film. The thickness of the final composite retardation film was 67 탆.

Example  4

The amide-based film (C) prepared in Preparation Example 2-3 was laminated using the acrylic film (a) prepared in Preparation Example 1-1 and an acrylic pressure-sensitive adhesive to prepare a composite retardation film. The thickness of the final composite retardation film was 71 탆.

Example  5

The amide-based film (C) prepared in Preparation Example 2-3 was bonded to the acrylic film (b) prepared in Production Example 1-2 using an acrylic adhesive, thereby preparing a composite retardation film. The thickness of the final composite retardation film was 69 탆.

Example  6

The amide-based film (D) prepared in Preparation Example 2-4 was bonded to the acrylic film (b) prepared in Preparation Example 1-2 and an acrylic adhesive to prepare a composite retardation film. The thickness of the final composite retardation film thus produced was 66 탆.

Comparative Example  One

Only the acrylic film (a) having negative retardation characteristics in Production Example 1-1 was used as a retardation film. The thickness of the produced retardation film was 50 탆.

Comparative Example  2

The negative C coating liquid was directly coated on the acrylic film (a) having negative retardation characteristics of Production Example 1-1 to prepare a composite retardation film. The negative C coating solution used herein was prepared by dissolving ethylcellulose (Dow EC100, Mw 180,000, Ethoxyl content: 49%) in a mixed solvent of toluene / ethanol (3/7) at a room temperature with gentle stirring at a solid content of 10% . The completely dissolved coating liquid was coated on an acrylic film having negative retardation characteristics to a final coating thickness of 10 mu m and dried at 80 DEG C for 5 minutes. The thickness of the produced retardation film was 60 탆.

Comparative Example  3

An acrylic negative C film was laminated on the acrylic film (a) having negative retardation characteristics in Production Example 1-1 to prepare a composite retardation film. The acrylic negative C film used here was prepared by the following method. First, an acrylic resin and a polycarbonate resin (LGPC trade name DVD1080) each containing 77% by weight of methyl methacrylate, 15% by weight of cyclohexyl methacrylate, 2% by weight of alphamethylstyrene and 6% by weight of cyclohexylmaleimide, At a weight ratio of 250 and 200 rpm using a twin extruder to prepare a resin composition. The obtained raw material pellets were dried in vacuo, melted in an extruder at 250 占 폚, passed through a coat hanger type T-die, and a film having a thickness of 185 占 퐉 was produced through a chrome casting roll and a drying roll. The prepared film was biaxially stretched 2.3 times in the MD direction and 2.5 times in the TD direction in this order to obtain a retardation film having a thickness of 42 占 퐉. At this time, the temperature in the MD direction stretching is 128 占 폚 and the stretching temperature in the TD direction is 138 占 폚. The thickness of the produced composite phase difference film was 94 탆.

Experimental Example  One

The retardation films prepared in Examples 1 to 6 and Comparative Example 1 were measured with respect to a retardation value (R _in ) in the plane direction at 550 nm, a retardation value _in thickness direction (R _th ) and Nz (R _th / R _in ) was measured and shown in Table 1 below.

division Negative retardation characteristics
Layer having - C or - B type
Layer having a phase difference complex
Phase difference film R _in (nm) R _th (nm) R _in (nm) R _th (nm) R _in (nm) R _th (nm) Nz (R _th / R _in ) Example 1 100 150 One -100 99 50 0.51 Example 2 124 172 One -100 123 72 0.59 Example 3 124 172 20 -90 104 82 0.79 Example 4 100 150 2 -97 98 53 0.54 Example 5 124 172 2 -97 122 75 0.61 Example 6 124 172 18 -88 106 84 0.79 Comparative Example 1 100 150 - - 100 150 1.50 Comparative Example 2 100 150 25 -103 75 47 0.60 Comparative Example 3 100 150 2 -90 98 60 0.61

As can be seen from the above Table 1, the composite retardation films of Examples 1 to 6 had a retardation value (R _in ) _{in the} range of 50 to 300 nm and a thickness retardation value (R _th ) in the range of 10 to 300 nm range and, Nz (R _th / R _in) to less than 1, it can be seen that it is suitable for application to the phase difference film of the IPS mode liquid crystal display device. However, in Comparative Example 1 For it can be seen that unsuitable to the value Nz (R _th / R _in) applied to the phase difference film or the like IPS-mode liquid crystal display device 1 or more.

Experimental Example  2

In order to compare the brittleness of the retardation films prepared in Examples 1 to 6 and Comparative Examples 1 to 3, the impact energy was measured and shown in Table 2 below. Here, the impact energy refers to the degree to which the film can withstand an external impact. In the present invention, the impact energy is measured to such an extent that a constant weight of the apparatus is able to withstand a drop of the film at a predetermined height. More specifically, in the present invention, the impact energy IE is a value defined according to the following equation (11).

Eq. (11): IE = (gravitational acceleration * weight of gravity * height) / (film thickness * film area)

Thickness (㎛) Impact energy (kN * m / m ³⁾ Example 1 72 8650 Example 2 70 8570 Example 3 67 9110 Example 4 71 6810 Example 5 69 6760 Example 6 66 7420 Comparative Example 1 50 380 Comparative Example 2 60 240 Comparative Example 3 94 500

As can be seen from the above [Table 2], it can be confirmed that the compound phase difference film using an amide-based film is excellent in brittleness. However, as in Comparative Examples 1 to 3, in the case of a compound phase difference film including only an acrylic film, it is confirmed that the embrittlement is very weak.

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 (15)

An acrylic film having negative retardation characteristics; And
An amide-based film having a negative C type or negative B type phase difference,
Wherein the amide-based film having the negative C type or negative B type phase difference comprises a polyamide type resin containing a unit represented by the following formula (3).
(3)

In Formula 3,
D is a C 2 _-16 aliphatic hydrocarbon chain,
E ₁ and E ₂ are benzene rings,
X ₄ , X ₅ and X ₆ are each independently a halogen atom or a C _1-6 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 to 2,
and k is an integer of 5 to 10,000.
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 an Nz value represented by the following formula (3): 0.1 or more and less than 1.
(3): Nz = _{Rth, total} / _{Rin, 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 acrylic film having the negative retardation characteristics satisfies the following formulas (4) and (5).
(4): 50 nm < R _{in , a} < 250 nm
(5): 80 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 acrylic film having the negative retardation characteristic measured in the visible light wavelength band,
R _{th , a} is the retardation value in the thickness direction of the acrylic film having negative retardation characteristics measured in the visible light wavelength band.
The method according to claim 1,
Wherein the amide-based film having the negative C type retardation satisfies the following formulas (6) and (7).
(6): -50 nm <R _{in , b 1} <50 nm
(7): -200 nm < R _{th , b 1} < 0 nm
In the above formulas (6) and (7)
R _{in and b 1} are retardation values in the plane direction of an amide-based film having a negative C-type retardation measured in a visible light wavelength band,
_{Rth and b1} are retardation values in the thickness direction of the amide type film having the negative C type retardation measured in the visible light wavelength band.
The method according to claim 1,
Wherein the amide-based film having the negative B type phase difference satisfies the following formulas (8) and (9).
Equation _{(8): 0nm <R in} , b2 <100nm
Equation _{(9): -200nm <R th} , b2 <0nm
In the above formulas (8) and (9)
R _{in, b2} is the plane retardation value of the amide-based film having a retardation of the negative type B measured in the visible light wavelength band,
_{Rth and b2} are retardation values in the thickness direction of an amide type film having a negative B type retardation measured in a visible light wavelength band.
The method according to claim 1,
Wherein the retardation film satisfies the following formula (10).
(10): n _{x , total} > n _{z , total} > n _{y , total}
In the above formula (10)
n _{x , total} is a refractive index in a 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)
n _{y , total} is the refractive index in the direction perpendicular to the slow axis of the entire retardation film (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.
delete delete The method according to claim 1,
Wherein the thickness of the amide-based film having the negative C type or negative B type phase difference is 5 to 40 mu m.
The method according to claim 1,
Wherein the acrylic film having negative phase difference characteristics comprises a blending resin containing an acrylic resin and a styrene resin or an acrylic resin containing a styrene monomer.
12. The method of claim 11,
Wherein the acrylic film having negative phase difference characteristics further comprises a rubber component.
The method according to claim 1,
Wherein the acrylic film having the negative phase difference characteristic and the amide film having the negative C type or negative B type phase difference are attached by an adhesive or a pressure sensitive adhesive.
The method according to claim 1,
Wherein the retardation film is for a planar switching (IPS) mode liquid crystal display device.
A liquid crystal display device comprising the retardation film of any one of claims 1 to 7 and 10 to 14.