KR20080045407A - Retardation films, method for preparing the same, liquid crystal display comprising the film - Google Patents

Abstract

A retardation film, a method of producing the retardation film and an LCD(Liquid Crystal Display) having the retardation film are provided to produce the retardation film of an in-plane switching mode LCD using a cyclic olefin co-polymer at a low cost. A retardation film is manufactured by stretching a cyclic olefin co-polymer un-stretched film in a vertical axis and has a retardation of 100 through 150 nanometer in a plane direction and 0 through minus 30 nanometer in a thickness direction at 550 nanometer.

Description

Retardation film, manufacturing method thereof, and liquid crystal display including the same {RETARDATION FILMS, METHOD FOR PREPARING THE SAME, LIQUID CRYSTAL DISPLAY COMPRISING THE FILM}

The present invention relates to a retardation film, a manufacturing method thereof, and a liquid crystal display device including the retardation film.

Recently, liquid crystal display devices are widely used as display devices for computers, word processors, small televisions, and the like. In particular, STN liquid crystal display systems have been put into practical use, and white STN display devices and color STN display devices have attracted attention.

However, the liquid crystal display device as described above is colored blue or yellow in relation to the birefringence of the liquid crystal cell and the visible light. In the liquid crystal display device of the white STN display device and the color STN display device, the coloring by the phase difference of the liquid crystal cell can be compensated by attaching a retardation film having a specific retardation value to the substrate surface of the liquid crystal cell.

Stretched TAC (triacetyl cellulose), cycloolefin polymer (COP) (for example, ZEONOR from ZEON Corp. and ARTON from JSR Corp.) and the like are used for such a retardation film. For example, Japanese Patent Laid-Open No. 2-191904 or Japanese Patent Laid-Open No. 2-42406 discloses an example in which a thermoplastic resin film is produced by longitudinal uniaxial stretching or transverse uniaxial stretching.

On the other hand, among the liquid crystal displays of various modes recently introduced to improve the wide viewing angle, the in-plane switching liquid crystal display (IPS-LCD) is a liquid crystal molecules on the substrate surface in the non-driven state Since it has an almost horizontal and uniform arrangement, light can hardly change by the polarizing plate and pass through the liquid crystal layer as it is, resulting in an undriven state by the arrangement of the polarizing plates on the top and bottom surfaces of the substrate. It can indicate an almost complete dark state. In such a liquid crystal display device in a planar switching mode, an optical compensation film is used to improve viewing angle characteristics.

The present inventors have found that the surface direction retardation and thickness direction retardation at 550 nm are 100 to 150 nm and 0, respectively, so that the longitudinal monoaxially oriented film made of a cyclic olefin copolymer is suitable for use as a retardation film of a planar switching mode liquid crystal display device. It has been found that it has a value in the range of ˜−30 nm. The cyclic olefin-based copolymer has a phase difference value suitable for use as a retardation film of a planar switching liquid crystal display device as described above when manufactured into a longitudinal uniaxial stretched film, and is easily available and inexpensive. Advantageous over the retardation film of the planar switching mode liquid crystal display device.

Accordingly, the present invention provides a retardation film prepared by vertically uniaxially stretching a cyclic olefin copolymer-free stretched film having a value of a phase difference of 100 to 150 nm in the plane direction and a 0 to -30 nm in the thickness direction at 550 nm, It is an object of the present invention to provide a liquid crystal display device comprising the manufacturing method and the retardation film.

The present invention provides a retardation film prepared by longitudinally uniaxially stretching a cyclic olefin copolymer-free stretched film having a value of a phase difference of 100 to 150 nm in the plane direction at 550 nm and 0 to -30 nm in the thickness direction. .

In addition, the present invention is a retardation film having a phase difference including the step of longitudinally uniaxially stretching the cyclic olefin copolymer-free stretched film in the plane direction at 550nm and 0 ~ -30nm in the thickness direction It provides a method of manufacturing.

In addition, the present invention is prepared by a longitudinal uniaxial stretching of a) a + C-plate and b) a cyclic olefin copolymer-free stretched film disposed on the + C-plate, the phase difference is 100 in the plane direction at 550nm It provides a laminated retardation film comprising a retardation film having a value of ˜150 nm and a value of 0 to −30 nm in the thickness direction.

In addition, the present invention a) phase difference produced by vertical uniaxial stretching of the cyclic olefin-based copolymer unstretched film having a value of 100 ~ 150nm in the plane direction and 0 ~ -30nm in the thickness direction at 550nm It provides a polarizing plate comprising a film, b) a first protective film disposed on the retardation film, c) a polarizer disposed on the first protective film, and d) a second protective film disposed on the polarizer. In this polarizing plate, + a C plate may be further provided below the a) retardation film.

In addition, the present invention a) the phase difference produced by longitudinal uniaxial stretching of the cyclic olefin copolymer-free stretched film having a value of 100 ~ 150nm in the plane direction and 0 ~ -30nm in the thickness direction at 550nm It provides a polarizing plate comprising a retardation film, b) a polarizer disposed on the retardation film, and c) a protective film disposed on the polarizer. In this polarizing plate, + a C plate may be further provided below the a) retardation film.

In addition, the present invention provides a retardation film having a phase difference of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm, produced by longitudinal uniaxial stretching of the cyclic olefin copolymer-free stretched film. It provides a liquid crystal display device comprising. It is preferable that this liquid crystal display device is a planar switching (IPS) mode.

Hereinafter, the present invention will be described in detail.

The retardation film according to the present invention is a film having a retardation value in the range of 550 nm in the range of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction, consisting of a cyclic olefin copolymer and having a cyclic olefin copolymer. It is characterized in that the non-oriented film produced by longitudinal uniaxial stretching.

In this invention, the surface direction retardation value can be defined like following formula 1, and the thickness direction retardation value can be defined like following formula 2.

[Equation 1]

R _in = d × (Nx-Ny)

[Equation 2]

R _th = d × {(Nz-Ny)}

In Formulas 1 and 2, Nx is a planar refractive index in the stretching direction, Ny is a planar refractive index in the vertical direction in the stretching direction, Nz is a refractive index in the thickness direction, and d is the thickness of the film.

The cyclic olefin copolymer used in the retardation film according to the present invention is not only easy to obtain and inexpensive, but also suitable for use as a retardation film of a planar switching mode liquid crystal display device when it is made of a longitudinal uniaxial stretched film. And a thickness direction retardation value, and the retardation value is uniform. Therefore, in the present invention, by using a cyclic olefin copolymer, a retardation film having the same or superior effect as that of the retardation film of the conventional planar switching mode liquid crystal display device can be produced at low cost.

The cyclic olefin copolymer which can be used to prepare the retardation film in the present invention is a cyclic structure-containing polymer, including a ring-opening polymer of a monomer having a norbornene ring structure and a hydrogenated product thereof; Addition polymers of monomers having a norbornene ring structure and hydrogenated products thereof; It may be selected and used in addition copolymers of monomers having norbornene-based ring structures with vinyl compounds and hydrogenated products thereof. In this invention, it is especially preferable to use the copolymer of a norbornene-type monomer and an ethylene monomer as said cyclic olefin type copolymer. It is preferable that the ratio of a norbornene-type monomer and an ethylene monomer in the said copolymer is 65-83: 17-35 weight%.

The cyclic olefin copolymer which can be used in the present invention may include a repeating unit represented by the following formula (1).

As the cyclic olefin copolymer, a copolymer of a commercially available norbornene-based monomer and an ethylene monomer can be used.

The retardation film according to the present invention is produced by forming a film of the above-mentioned cyclic olefin copolymer into a film and then applying a uniform longitudinal uniaxial stretching treatment. The retardation film has characteristics such as heat resistance, low specific gravity, low birefringence, low light modulus, low wavelength dispersion, and the like, which are inherently possessed by norbornene-based resins, and high retardation expression.

The method for producing the unstretched film of the cyclic olefin copolymer is not particularly limited, and for example, a melt extrusion method, a calender film forming method, a solution cast film forming method, or the like can be used. Among these, the melt extrusion method which is excellent in productivity is preferable. The melt extrusion method is a method in which a cyclic olefin copolymer is heated and melted in a cylinder, pressurized with a screw, and then discharged out from a die such as a T die.

In order to improve the heat resistance, UV resistance, smoothness, formability, etc. of the retardation film according to the present invention, an anti-aging agent such as a phenol-based or phosphorus-based, an anti-aging agent, such as a phenol-based copolymer, and an amine Antistatic agents such as those, esters of aliphatic alcohols, polyhydric alcohols, lubricants such as higher fatty acids, amides, ultraviolet absorbers such as benzophenones, and benzotriazoles can be added within a range not impaired for the purposes of the present invention. .

The cyclic olefin-based copolymer unstretched film prepared as described above may be prepared as a retardation film according to the present invention by longitudinal uniaxial stretching according to the following method.

The longitudinal uniaxial stretching method according to the present invention can be carried out by performing a preheating step, a stretching step and a heat treatment step, respectively, which can be carried out continuously. The longitudinal uniaxial stretching method may be performed using a manufacturing apparatus provided in the order of a preheating zone, a stretching zone, and a heat treatment zone.

The preheating step refers to a step of preheating and softening in advance so that the cyclic olefin-based copolymer unstretched film can be well stretched in the subsequent stretching step.

In the preheating step, it is preferable to heat the cyclic olefin copolymer-free stretched film so as to have a constant temperature in the range of Tg-30 ° C to Tg when the glass transition temperature of the cyclic olefin copolymer is Tg. It is preferable to make preheating time 1 to 10 minutes normally in order to suppress deformation more than necessary. In particular, in the present invention, when the preheating time is 5 minutes or more and 10 minutes or less, it is advantageous to make the retardation value of the stretched film after the stretching step included in the above-described value. Specifically, when the film is sufficiently preheated in the preheating step, the film is softened sufficiently so that there is little variation in the retardation value at the time of stretching. However, preheating for too long time requires high magnification of the film due to the softening degree of the film, or it is difficult to develop sufficient birefringence.

In the stretching step proceeding after the preheating step, when the glass transition temperature of the cyclic olefin copolymer-free film is Tg, the glass transition temperature of the film is in the temperature range of Tg-20 ° C to Tg + 20 ° C. It is preferable to uniaxially stretch longitudinally, ie, longitudinally. Here, the stretching temperature, the stretching speed, and the draw ratio may be determined by the kind, thickness, in-plane retardation value of the retardation film required, and the like of the cyclic olefin copolymer-free stretched film. In such a longitudinal uniaxial stretching method, the stretching temperature is more preferably set to Tg to Tg + 20 ° C of the cyclic olefin copolymer. When extending | stretching temperature is lower than Tg-20 degreeC of cyclic olefin type copolymer, there exists a tendency for phase difference deviation of the stretched film obtained by concentrating stress when extending | stretching, and temperature is higher than Tg + 20 degreeC of cyclic olefin copolymer. In this case, the degree of molecular orientation is low, and birefringence is hard to be expressed.

Although the draw ratio in the stretching step is set by the expression of the thickness of the unstretched film and the appropriate retardation value, 1.1 to 3 times is usually preferable. When the draw ratio is lower than 1.1 times, it is difficult to obtain a film having sufficient retardation due to the low birefringence, and when the draw ratio is higher than 3 times, the deviation of the retardation value of the stretched film becomes large and the neck in increases. There is this.

It is preferable that the extending | stretching speed at the time of extending | stretching the cyclic olefin type copolymer of this invention is 10-500% / min.

In the stretching step, when the ratio of the length and width of the stretched region of the film, that is, the portion of the film exposed during stretching is 1: 0.5 to 1: 1.5, it is advantageous to include the retardation value of the stretched film in the aforementioned value. Here, the length means the direction in which the stretching is performed, that is, the longitudinal direction, and the width means the vertical direction in the stretching direction, that is, the transverse direction. In general, the R _in value can be adjusted by adjusting the size of the draw ratio, but it is difficult to adjust the R _th value to a value of 0 to -15 nm. However, in the present invention, by adjusting the ratio of the length and width of the stretched region of the film, the R _th value of the stretched film can be adjusted in the range of 0 to-30nm, preferably 0 ~-15nm, the phase difference of the front surface of the film Deviation can also be reduced.

As the ratio of the length and width of the stretched region of the film is closer to 1: 0.5 to 1: 1.5, the shrinkage in the width direction during stretching is free and the R _th value tends to be close to zero. Since the value of R _th is expressed as the difference between the refractive index Ny in the direction perpendicular to the stretching direction and the refractive index Nz in the thickness direction, the R _th value becomes closer to zero as the two refractive indices are similar. When the shrinkage in the width direction is free, it is difficult to orient the polymer chain in the Ny direction, which results in a smaller Ny value and a smaller difference from the Nz value. In addition, since the shrinkage in the width direction is free, the entire surface of the film is evenly stretched during stretching, so that the phase difference deviation and the thickness variation are significantly reduced.

In the heat treatment step performed after the preheating step and the stretching step, when the glass transition temperature of the cyclic olefin copolymer is Tg for the purpose of fixing the orientation of the cyclic olefin copolymer longitudinal monoaxially oriented film, Heat treatment is performed to cool the temperature in the range of Tg-50 ° C to Tg-20 ° C.

In the case where the retardation film according to the present invention is prepared using a manufacturing apparatus having a preheating zone, a drawing zone, and a heat treatment zone, the cyclic olefin copolymer lead-free is transferred into the preheating zone, the stretching zone, and the heat treatment zone. The new film is continuously heated, stretched and heat treated to cool, but some intermediate temperature zones may inevitably occur at the boundaries of these zones. As a means for reducing this intermediate temperature range as much as possible, although not particularly limited, a narrow slit-shaped passage can be provided where the film moves between the zones. In addition, the other section can maintain the temperature of each zone by a method of shielding with a heat insulating partition wall, a shielding with an air curtain, or a combination thereof.

The retardation film according to the present invention prepared as described above has a value of retardation of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm, and a small difference in retardation. In the retardation film which concerns on this invention, it is preferable that surface direction retardation deviation is 30 nm or less, and it is more preferable that it is 15 nm or less. Under such conditions, the retardation film may not generate retardation stains. In addition, the thickness direction retardation deviation is preferably 10 nm or less, and more preferably 5 nm or less.

In addition, the present invention is prepared by a longitudinal uniaxial stretching of a) a + C-plate and b) a cyclic olefin copolymer-free stretched film disposed on the + C-plate, the phase difference is 100 in the plane direction at 550nm It provides a laminated retardation film comprising a retardation film having a value of ˜150 nm and a value of 0 to −30 nm in the thickness direction.

The + C-plate is a film having a planar retardation value of almost zero and a retardation value in the thickness direction having a positive value. The wavelength dispersion characteristics of the + C-plate may have normal wavelength dispersion characteristics, flat wavelength dispersion characteristics, and reverse wavelength dispersion characteristics.

The + C-plate may be made of a polymer material or a UV cured liquid crystal film. Specifically, it may be made of a homeotropic aligned liquid crystal film, a biaxially stretched polycarbonate (PC), a biaxially stretched COP, or the like.

The present invention also provides a phase retardation film prepared by a) longitudinal uniaxial stretching of a cyclic olefin copolymer-free stretched film with a phase difference of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm. and b) a first protective film disposed on the retardation film, c) a polarizer disposed on the first protective film, and d) a second protective film disposed on the polarizer. In this polarizing plate, + a C plate may be further provided below the a) retardation film.

As the polarizer, materials known in the art may be used, and specifically, stretched polyvinyle alchol (PVA) may be used.

As the first protective film and the second protective film, a protective film of a polarizing plate known in the art may be used, and the scope of the present invention is not limited by these types. Specifically, polyester polymers such as polyethylene terephthalate and polyethylene phthalade, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene and acrylonitrile-styrene copolymers (AS Styrene polymer such as resin), or a film made of a polycarbonate polymer or the like can be used. In addition, polyolefin polymers including polynorbornene, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamides, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene It is also possible to use a film made of a polymer, an epoxy polymer, or a blend polymer of the above polymers. In addition, a film including a thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylic urethane, epoxy and silicone may be used.

The present invention also provides a phase retardation film prepared by a) longitudinal uniaxial stretching of a cyclic olefin copolymer-free stretched film with a phase difference of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm. and b) a polarizer on the retardation film, and c) a polarizer comprising a protective film disposed on the polarizer. In this polarizing plate, + a C plate may be further provided below the a) retardation film.

In addition, the present invention provides a retardation film having a phase difference of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm, produced by longitudinal uniaxial stretching of the cyclic olefin copolymer-free stretched film. It provides a liquid crystal display device comprising. It is preferable that this liquid crystal display device is a planar switching (IPS) mode. The liquid crystal display according to the present invention may have a configuration known in the art except for including the retardation film according to the present invention described above.

One embodiment of the present invention is a liquid crystal display device comprising a liquid crystal cell and a first polarizing plate and a second polarizing plate provided on both sides of the liquid crystal cell, wherein at least one of the first polarizing plate and the second polarizing plate and the liquid crystal One retardation film having a phase difference of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction, produced by uniaxially stretching a cyclic olefin copolymer-free stretched film between cells It provides a liquid crystal display device comprising the above. A + C-plate film may be further provided between the first polarizing plate or the second polarizing plate and the retardation film or between the liquid crystal cell and the retardation film.

Another embodiment of the present invention is a liquid crystal display device comprising a liquid crystal cell and a first polarizing plate and a second polarizing plate provided on both sides of the liquid crystal cell, wherein at least one of the first polarizing plate and the second polarizing plate is one surface Or a protective film for a retardation film having a phase difference of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction, prepared by uniaxially stretching the cyclic olefin copolymer-free stretched film on both sides. It provides as a liquid crystal display device, characterized in that provided. In this case, a + C-plate film may be further provided between the first polarizing plate or the second polarizing plate and the liquid crystal cell. In addition, a phase difference produced by vertically uniaxially stretching the cyclic olefin copolymer-free stretched film between the first polarizing plate or the second polarizing plate and the liquid crystal cell is 100 to 150 nm in the plane direction and 0 in the thickness direction at 550 nm. You may further include the retardation film which has a value of --30 nm.

In the present invention, the retardation film, the + C-plate, the polarizer, the protective film, and the liquid crystal cell can be adhered to each other using an adhesive, and the scope of the present invention is not limited by a particular kind of adhesive.

The present invention is explained in more detail using the following examples and comparative examples. The invention is not limited to the following examples.

<Material>

In this embodiment, Ticona's Topas 6013 (Tg 138 ° C) resin, which is a copolymer of a norbornene-based monomer and an ethylene monomer, has a screw L / D of 29, a T-Die width of 1200 mm, and a lip of 1.0 mm. Melt extrusion was carried out with a phosphorus extruder to prepare a non-stretched film having a thickness of 100 μm.

The cyclic olefin copolymer-free stretched film having a width of 650 mm was introduced into a stretching machine having a preheating zone, a stretching zone, and a heat treatment zone, and uniaxially stretched in the longitudinal direction. The length of each zone was 1 m and the transfer speed of the film was 0.4 m / min.

<Example 1>

The cyclic olefin copolymer-free stretched film having a width of 650 mm was preheated in a preheating zone having a warm air temperature of 125 ° C. The pre-heated non-stretched film was stretched uniaxially in the longitudinal direction with a draw ratio of 1.7% with a stretching speed of 40% / min in a stretching zone having a warm air temperature of 140 ° C. The retardation film coming out of the stretching zone was cooled to 110 ° C. in the heat treatment zone. As for the obtained stretched film, the average thickness 80 micrometers, the width direction retardation deviation were 5 nm, the surface direction retardation value was 120 nm, and the thickness direction retardation value was -15 nm.

<Example 2>

The cyclic olefin copolymer-free stretched film having a width of 650 mm was preheated in a preheating zone having a warm air temperature of 120 ° C. The pre-heated unstretched film was stretched at a stretch rate of 40% / min in a stretching zone having a warm air temperature of 145 ° C, and the draw ratio was doubled and uniaxially stretched in the longitudinal direction. The stretched film coming out of the stretching zone was cooled to 100 ° C. in the heat treatment zone. The obtained retardation film was 75 micrometers in average thickness, the width direction retardation deviation was 7 nm, the surface direction retardation value was 100 nm, and the thickness direction retardation value was -15 nm.

<Phase Difference Measurement>

Refractive index (n) was measured for each of the prepared retardation films using an Abbe refractometer. In addition, the in-plane retardation value Re was measured using an axoscan manufactured by axo-matrix, and the angle between the incident light and the film plane was measured at 10 ° intervals to measure the retardation value Re up to 50 °.

When the refractive index in the stretching direction is Nx, the refractive index in the vertical direction in the stretching direction is Ny, and the refractive index in the thickness direction is Nz, the phase difference Re = (Nx-Ny) × d in the plane direction, the phase difference in the thickness direction Rth = (Nz-Ny) x d. At this time, d means the thickness of a stretched film.

The retardation deviation of the film front surface computed the average value of the value measured by 100 mm space | interval in the width direction after producing the stretched film of width 550-600 mm.

Comparative Example

A retardation film was prepared in the same manner as in Example 1 except for the step of longitudinal uniaxial stretching. Therefore, the plane direction retardation value of the unstretched film manufactured as mentioned above was 3 nm, and the thickness direction retardation value was -4 nm.

According to the present invention, a phase difference film of a planar switching mode liquid crystal display device can be manufactured at low cost by using an easily available and low cost cyclic olefin copolymer.

Claims (23)

A retardation film produced by vertical uniaxial stretching of a cyclic olefin copolymer-free stretched film having a value of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm. The retardation film of claim 1, wherein the retardation film is for retardation compensation of an in-plane switching (IPS) mode liquid crystal display device. The retardation film of claim 1, wherein the cyclic olefin copolymer is a copolymer of a norbornene monomer and an ethylene monomer. The retardation film of claim 3, wherein the norbornene-based monomer and the ethylene monomer are included in a ratio of 65 to 83:17 to 35% by weight. The retardation film according to claim 3, wherein the cyclic olefin copolymer comprises a repeating unit represented by the following formula (1). <Formula 1>

The retardation film of Claim 1 whose surface direction retardation deviation is 30 nm or less, and thickness direction retardation deviation is 10 nm or less. The retardation film of claim 1, wherein the retardation film is produced by uniaxially stretching the cyclic olefin copolymer-free film by a method including a preheating step, a stretching step, and a heat treatment step. The retardation film of claim 7, wherein the preheating step is performed for 5 to 10 minutes in the range of Tg-30 ° C to Tg when the glass transition temperature of the cyclic olefin copolymer is Tg. The method according to claim 7, wherein in the stretching step is stretched 1.1 to 3 times at Tg-20 ℃ to Tg + 20 ℃, the ratio of the length and width of the stretched region of the film is adjusted to 1: 0.5 to 1: 1.5 Retardation film. A retardation film comprising a step of longitudinally uniaxially stretching a cyclic olefin copolymer-free stretched film has a value of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm. The method of claim 10, comprising a preheating step, a stretching step, and a heat treatment step. The method of claim 10, wherein the preheating step is performed for 1 to 10 minutes at a temperature of Tg-30 ° C. to Tg when the glass transition temperature of the cyclic olefin copolymer is Tg. The method of claim 12, wherein the preheating step is performed for 5 to 10 minutes. The method of claim 10, wherein the stretching step, when the glass transition temperature of the cyclic olefin copolymer is Tg, the stretching ratio of 1.1 to 3 times and the stretching of 10 to 500% / min at Tg-20 ℃ ~ Tg + 20 ℃ Method for producing a retardation film to be carried out at a speed. The method according to claim 10, wherein in the stretching step, the ratio of the length and width of the stretched region of the film is controlled to be 1: 0.5 to 1: 1.5. The method of claim 10, wherein the heat treatment is performed to maintain a temperature of Tg-50 ° C. to Tg-20 ° C. when the glass transition temperature of the cyclic olefin copolymer is Tg. a) a + C-plate and b) a cyclic olefin copolymer-free stretched film disposed on the + C-plate, longitudinally uniaxially stretched, having a phase difference of 100 to 150 nm and thickness in the plane direction at 550 nm. The laminated retardation film containing the retardation film which has a value of 0--30 nm in a direction. a) a retardation film prepared by longitudinally uniaxially stretching a cyclic olefin copolymer-free stretched film having a value of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm, b) the A first protective film disposed on the retardation film, c) a polarizer disposed on the first protective film, and d) a second protective film disposed on the polarizer. The polarizing plate according to claim 18, further comprising: a) a + C-plate below the retardation film. a) a retardation film produced by vertical uniaxial stretching of a cyclic olefin copolymer-free stretched film having a value of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm, b) the And a polarizer disposed on the retardation film, and c) a protective film disposed on the polarizer. The polarizing plate according to claim 20, further comprising + C-plate below the a) retardation film. A liquid crystal display device comprising a retardation film produced by vertically uniaxially stretching a cyclic olefin copolymer-free stretched film, the phase difference film having a value of 100 to 150 nm in the plane direction and 0 to -30 nm in the thickness direction at 550 nm. . The liquid crystal display device of claim 22, wherein the liquid crystal display device is in an in-plane switching (IPS) mode.