KR101408387B1 - Optical compensation film and method of producing the same, polarization plate, and liquid crystal display apparatus - Google Patents

Abstract

An optical compensation film for precisely optically compensating a liquid crystal cell and improving color deviation depending on a high contrast and a visual direction in black display, a method for producing the same, a polarizing plate, and a liquid crystal display Lt; / RTI > Therefore, it is an optical compensation film or the like which is characterized by satisfying the following expressions (1) to (4).

50? Re (550)? 200 ... ... ... ... ... ... ... Equation (1)

0.4? Rth (550) / Re (550)? 0.6 ... Equation (2)

0.1 < Re (450) / Re (550) < 0.95 ... Equation (3)

1.03 < Re (650) / Re (550) < 1.93 ... Equation (4)

Optical compensation film, polarizing plate, retardation, liquid crystal display

Description

Technical Field [0001] The present invention relates to an optical compensation film, a polarizing plate, and a liquid crystal display device,

The present invention relates to an optical compensation film, a manufacturing method thereof, a polarizing plate, and a liquid crystal display device.

A liquid crystal display device has a liquid crystal cell and a polarizing plate. The polarizing plate generally has a protective film made of cellulose acetate and a polarizing film. For example, a polarizing film made of a polyvinyl alcohol film is dyed with iodine, stretched, and laminated on both sides thereof with a protective film.

In a transmissive liquid crystal display device, a polarizing plate may be attached to both sides of a liquid crystal cell, and one or more optical compensation films may be further disposed.

In a reflective liquid crystal display device, a reflective plate, a liquid crystal cell, at least one optical compensation film, and a polarizing plate are arranged in this order. A liquid crystal cell is composed of a liquid crystal molecule, two substrates for sealing it, and an electrode layer for applying a voltage to liquid crystal molecules.

The liquid crystal cell can be classified into TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically), or the like, which can be applied to both transmissive and reflective types, Compensatory Bend), VA (Vertically Aligned), ECB (Electrically Controlled Birefringence).

Of these LCDs, nematic liquid crystal molecules having positive dielectric anisotropy are used for applications requiring high display quality, and a 90-degree twisted nematic liquid crystal display (hereinafter referred to as TN mode) driven by a thin film transistor It is mainly used.

However, the TN mode has excellent viewing characteristics when seen from the front, but has a viewing angle characteristic that contrast is lowered when viewed in an oblique direction and gradation reversal occurs in which the brightness is reversed in the gray-scale display, , And this improvement is strongly desired.

On the other hand, liquid crystal systems of wide view angle, such as IPS system, OCB system and VA system, are expanding their share with the recent increase in demand for liquid crystal televisions. In each of these methods, the quality of the display is improved year after year, but the problem of color deviation that occurs when viewed obliquely has not been solved.

(450) /? N? D (550) <0.97, 1.01 <? Nd (650) /? N? D (550) as a retardation plate of a conventional polymer orientation film, ) &Lt; 1.35 (? N d (?) Is a retardation of a polymer oriented film at a wavelength? Nm) (see Japanese Patent Laid-Open Publication No. 2000-137116).

However, with the method described in Patent Document 1, the effect of improving the color deviation is not obtained in a television application requiring a very high display quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems and to achieve the following objects. In other words, it is an object of the present invention to provide an optical compensation film and a polarizing plate which are precisely optically compensated for the liquid crystal cell, and which improve color deviation depending on the visual direction in high contrast and black display.

Another object of the present invention is to provide a VA, IPS and OCB mode liquid crystal display device in which the contrast is improved and the color deviation depending on the viewing direction in black display is improved.

In order to solve the above problems, the inventors of the present invention have made extensive studies and obtained the following findings. That is, it is known that the color deviation can be highly compensated by bringing the Rth / Re of the optical compensation film close to 0.5 by a predetermined stretching condition.

The present invention is based on the above knowledge by the present inventors, and means for solving the above problems are as follows. In other words,

The optical compensation film of the present invention is characterized by satisfying the following expressions (1) to (4).

50? Re (550)? 200 ... ... ... ... ... ... ... Equation (1)

0.4? Rth (550) / Re (550)? 0.6 ... Equation (2)

0.1 &lt; Re (450) / Re (550) &lt; 0.95 ... Equation (3)

1.03 &lt; Re (650) / Re (550) &lt; 1.93 ... Equation (4)

Re (450), Re (550) and Re (650) in equations (1) to (4) are in-plane retardation values (unit: nm) measured at 450 nm, 550 nm and 650 nm wavelengths, respectively , And Rth (550) is a retardation value (unit: nm) in the thickness direction measured with light having a wavelength of 550 nm.

The method for producing an optical compensation film of the present invention is characterized by including a stretching step of stretching the film in either the longitudinal direction or the transverse direction and a shrinking step of shrinking the other direction.

The method for producing a polarizing plate of the present invention is manufactured by a method of producing an optical compensation film comprising a stretching step of stretching a film in either the longitudinal direction or the transverse direction and a shrinking step of shrinking the other direction, (1) to (4) of the optical compensation film according to the present invention by a roll-to-roll method.

The polarizing plate of the present invention is produced by a method of producing an optical compensation film comprising a stretching step of stretching a film in either the longitudinal direction or the transverse direction and a shrinking step of shrinking the other direction, Characterized in that the polarizing plate is manufactured by a method for producing a polarizing plate, which comprises a step of bonding an optical compensation film having a long shape satisfying the following conditions (1) to (4) with a polarizer and a roll-to-roll film.

The liquid crystal display of the present invention is manufactured by a method of producing an optical compensation film comprising a stretching step of stretching a film in either the longitudinal direction or the transverse direction and a shrinking step of shrinking the other direction, (7-1) a polarizing plate produced by a method for producing a polarizing plate including a step of bonding a long optical compensation film satisfying the following conditions (1) to (4) with a polarizer and a roll- And an optically anisotropic layer satisfying the expression (7-2).

-10 &lt; Re (550) &lt; 10 ... ... ... Equation (7-1)

100 &lt; Rth (550) &lt; 300 ... ... Equation (7-2)

According to the present invention, it is possible to provide an optical compensation film and a polarizing plate which are precisely optically compensated for the liquid crystal cell and improve color deviation depending on the visual direction in high contrast and black display, and also provide a polarizing plate in which the contrast is improved, It is possible to provide a liquid crystal display device of the VA, IPS and OCB modes, in which the color deviation depending on the color difference is improved.

Hereinafter, the present invention will be described in detail. In the present specification, the numerical range indicated by using &quot; ~ &quot; means a range including numerical values before and after "to" as a lower limit value and an upper limit value.

In the present specification, &quot; 45 DEG &quot;, &quot; parallel &quot;, or &quot; orthogonal &quot; means that the angle is within a range of an exact angle of less than +/- 5 DEG. The error with respect to the strict angle is preferably less than 4 DEG, more preferably less than 3 DEG. In addition, regarding the angle, &quot; + &quot; means clockwise and &quot; - &quot; means counterclockwise. The &quot; slow axis &quot; means the direction in which the refractive index becomes maximum. The term &quot; visible light region &quot; refers to a region of 380 to 780 nm. The wavelength at which the refractive index is measured is a value at? = 550 nm in the visible region, unless otherwise specified.

In the present specification, the term &quot; polarizing plate &quot; refers to a polarizing plate that has been cut to a size that is mounted on a long polarizing plate and a liquid crystal device (in this specification, &quot; punching &quot; ) And a polarizing plate. The term &quot; polarizing plate &quot; means a laminate having a transparent protective film for protecting the polarizing film on at least one side of the &quot; polarizing film &quot;.

In the present specification, Re (?) And Rth (?) Indicate retardation in the plane and retardation in the thickness direction at the wavelength?, Respectively. Re (?) Is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) with light having a wavelength of? Nm incident in the film normal direction.

When the film to be measured is represented by a monoaxial or biaxial refractive index ellipsoid, Rth (?) Is calculated by the following method.

Rth (λ) is a value obtained by dividing Re (λ) by the inclination axis (rotation axis) of the in-plane slow axis (determined by KOBRA 21ADH or WR) (if there is no slow axis, A total of six points are measured by incidence of light of a wavelength of? Nm from the oblique direction in a step of 10 degrees from the normal direction to the normal direction with respect to the film normal direction, and the measured retardation value and the assumption of the average refractive index KOBRA 21ADH or WR is calculated based on the value and the inputted film thickness value.

In the above case, in the case of a film having a direction in which the retardation value becomes zero at a certain tilt angle with the slow axis in the plane as the rotation axis in the plane from the normal direction, the retardation value at an inclination angle larger than the tilt angle has a sign After changing to negative, KOBRA 21ADH or WR is calculated.

When the slow axis is a tilting axis (rotation axis) (in the case where there is no slow axis, an arbitrary direction in the film plane is taken as a rotation axis), the retardation value is measured from any two oblique directions, Rth may be calculated from the following equations (I) and (II) based on the assumed value and the input film thickness value.

However, the above-mentioned Re ([theta]) represents the retardation value in the inclined direction from the normal direction.

In the formula (I), nx represents the index of refraction in the surface axial direction in the surface, ny represents the index of refraction in the direction orthogonal to nx in the surface, and nz represents the index of refraction in the direction orthogonal to nx and ny .

Rth = ((nx + ny) / 2 - nz) xd ... ... ... The formula (II)

Rth (?) Is calculated by the following method in the case where a film to be measured can not be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without an optical axis.

Rth (?) Is obtained by changing the Re (λ) from -50 ° to + 50 ° with respect to the normal direction of the film by a tilt axis (rotation axis) in the in-plane slow axis (determined by KOBRA 21ADH or WR) Light having a wavelength of? Nm is incident from the oblique direction, and 11 points are measured. KOBRA 21ADH or WR is calculated on the basis of the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.

In the above measurement, the values of the catalogs of the polymer handbook (JOHN WILEY & SONS, INC) and various optical compensation films can be used as the assumptions of the average refractive index.

The value of the average refractive index that is not already known can be measured with an Abbe refractometer. The values of average refractive index of the main optical compensation film are as follows: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethylmethacrylate (1.49) and polystyrene (1.59). By inputting the assumptions of these average refractive indices and the film thickness, KOBRA 21ADH or WR yields nx, ny, and nz. Nz = (nx - nz) / (nx - ny) is also calculated from the calculated nx, ny, and nz.

(Optical compensation film)

The optical compensation film of the present invention has an optical characteristic in which the cellulose acylate film has different wavelength dispersion of retardation in the normal direction of the incident light and in the oblique direction inclined with respect to the normal direction such as the polar angle of 60 degrees, And the like.

&Lt; Optical properties of optical compensation film &

The optical compensation film of the present invention has optical characteristics satisfying the following expressions (1) to (4) in order to improve the visual color deviation of the liquid crystal display device.

50? Re (550)? 200 ... ... ... ... ... ... ... Equation (1)

0.4? Rth (550) / Re (550)? 0.6 ... Equation (2)

0.1 &lt; Re (450) / Re (550) &lt; 0.95 ... Equation (3)

1.03 &lt; Re (650) / Re (550) &lt; 1.93 ... Equation (4)

Re (450), Re (550) and Re (650) in the above formulas (1) to (4) are in-plane retardation values measured in the wavelengths of 450 nm, 550 nm and 650 nm ), And Rth (450), Rth (550) and Rth (650) are retardation values (unit: nm) in the thickness direction measured with light having wavelengths of 450 nm, 550 nm and 650 nm, respectively.

Re (550) of the above formula (1) more preferably satisfies 80? Re (550)? 180 and further preferably satisfies 100? Re (550)? 150.

Rth (550) / Re (550) of the formula (2) is more preferably 0.43? Rth (550) / Re (550)? 0.57 and more preferably 0.45? Rth &Lt; / = 0.55.

Re (450) / Re (550) of the formula (3) is more preferably satisfies 0.3 <Re (450) / Re (550) &Lt; 0.85.

Re (650) / Re (550) of the above formula (4) is more preferably 1.08 <Re (650) / Re (550) &Lt; 1.70.

In addition, when applied to a liquid crystal display device, it is preferable that the optical compensation film is arranged so that its slow axis is parallel to the transmission axis of the polarizer.

Further, it is preferable to use an optically anisotropic layer satisfying the following formulas (7-1) and (7-2) in combination.

-10 &lt; Re (550) &lt; 10 ... ... ... Equation (7-1)

100 <| Rth (550) | <300 ... ... Equation (7-2)

In the case where the liquid crystal cell is the VA mode (VA mode liquid crystal display device), it is more preferable to satisfy the following expressions (7-3) and (7-4) And Formula (7-6) are satisfied.

-8 &lt; Re (550) &lt; 8 ... ... ... ... Equation (7-3)

140 <| Rth (550) | <240 ... ... Equation (7-4)

-5 &lt; Re (550) &lt; 5 ... ... ... ... Equation (7-5)

160 <| Rth (550) | <200 ... ... Equation (7-6)

&Lt; Polymer having a water content of 1.0% or less &

It is preferable to use a polymer having a water content of 1.0% or less in the optical compensation film of the present invention. Since the liquid crystal display device is used in various kinds of environments, it is intended to reduce the influence of temperature and humidity (especially humidity).

Examples of the polymer preferably used for the optical compensation film of the present invention include a polycarbonate copolymer and a polymer resin having a cyclic olefin structure.

Examples of the polycarbonate copolymer include a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), wherein the repeating unit represented by the general formula (1) To 30 mol% of a polycarbonate copolymer.

In the general formula (1), R ₁ to R ₈ are each independently selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group having 1 to 6 carbon atoms include an alkyl group such as a methyl group, an ethyl group, an isopropyl group and a cyclohexyl group, and an aryl group such as a phenyl group. Of these, a hydrogen atom and a methyl group are preferable.

In the general formula (1), X is represented by the following general formula (3), and R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the halogen atom and the alkyl group having 1 to 3 carbon atoms include the same ones as described above.

In the general formula (2), R ₁₁ to R ₁₈ are each independently selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms. Examples of the hydrocarbon group having 1 to 22 carbon atoms include an alkyl group having 1 to 9 carbon atoms such as a methyl group, an ethyl group, an isopropyl group and a cyclohexyl group, and an aryl group such as a phenyl group, a biphenyl group and a terphenyl group. Of these, a hydrogen atom and a methyl group are preferable.

In the general formula (2), Y is a group of the following formulas: R ₁₉ to R ₂₁ , R ₂₃ And R ₂₄ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms. These hydrocarbon groups are the same as those described above. R ₂₂ and R ₂₅ are each independently selected from hydrocarbon groups having 1 to 20 carbon atoms. Examples of such hydrocarbon groups include methylene, ethylene, propylene, butylene, cyclohexylene, phenylene, naphthyl A phenylene group, a phenylene group, Examples of Ar ₁ to Ar ₃ include an aryl group having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group.

[Polycarbonate Copolymer]

The polycarbonate copolymer is preferably a polycarbonate copolymer comprising 30 to 60 mol% of a repeating unit represented by the following formula (4) and 70 to 40 mol% of a repeating unit represented by the following formula (5) , More preferably 45 to 55 mol% of the repeating unit represented by the following general formula (4) and 45 to 55 mol% of the repeating unit represented by the following general formula (5).

In the general formula (4), R ₂₆ to R ₂₇ are each independently a hydrogen atom or a methyl group, and a methyl group is preferable from the viewpoint of handling.

In the above general formula (5), R ₂₈ to R ₂₉ are each independently a hydrogen atom or a methyl group, and hydrogen atoms are preferable from the viewpoints of economical efficiency, film properties and the like.

The optical compensation film in the present invention is preferably a polycarbonate copolymer having a fluorene skeleton as described above. As the polycarbonate copolymer having the fluorene skeleton, for example, a blend of polycarbonate copolymers having different composition ratios consisting of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) (1) is preferably 30 to 80 mol%, more preferably 35 to 75 mol%, and still more preferably 40 to 70 mol% of the entire polycarbonate copolymer.

The copolymer may be a combination of two or more kinds of repeating units represented by the general formulas (1) and (2).

Here, the above-mentioned molar ratio can be obtained by, for example, a nuclear magnetic resonance (NMR) apparatus in the entire polycarbonate bulk constituting the optical compensation film.

The above-mentioned polycarbonate copolymer can be produced by a known method. The polycarbonate is preferably a polycondensation method of a dihydroxy compound and phosgene, a melt polycondensation method and the like.

The polycarbonate copolymer preferably has an intrinsic viscosity of 0.3 to 2.0 dL / g. If it is less than 0.3, there is a problem that mechanical strength can not be maintained. On the other hand, if it exceeds 2.0, solution viscosity becomes excessively high, and problems such as generation of die lines in solution film formation and purification at the time of completion of polymerization become difficult.

The optical compensation film of the present invention may be a composition (blend) of the polycarbonate copolymer and other polymer compounds. In this case, since the polymer compound needs to be optically transparent, it is preferable that it is compatible with the polycarbonate copolymer, or that the refractive index of each polymer is substantially equal.

Specific examples of the other polymer include poly (styrene-co-maleic anhydride), and the composition ratio of the polycarbonate copolymer and the polymer compound is 30 to 80 mass% of the polycarbonate copolymer, 20 to 70 mass of the polymer compound %, More preferably 40 to 80% by mass of the polycarbonate copolymer and 20 to 60% by mass of the polymer compound.

In the case of a blend body, the polycarbonate copolymer may be combined with two or more kinds of repeating units.

In the case of a blend, a compatible blend is preferable. If the refractive indexes of the components are adjusted to each other, the light scattering between the components can be suppressed and the transparency can be improved. The blend body may be composed of three or more kinds of materials, or a plurality of kinds of polycarbonate copolymers and other polymeric compounds may be combined.

The weight average molecular weight of the polycarbonate copolymer is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000. The mass average molecular weight of the other polymer compound is preferably 500 to 100,000, more preferably 1,000 to 50,000.

[Polymer having a cyclic olefin structure]

Examples of the polymer resin having a cyclic olefin structure (hereinafter also referred to as "cyclic polyolefin resin" or "cyclic polyolefin") include (1) a norbornene polymer, (2) a monocyclic cycloolefin polymer, (3) a polymer of a cyclic conjugated diene, (4) a vinyl alicyclic hydrocarbon polymer, and a hydride of the above (1) to (4).

A preferred polymer for use in the present invention is an addition (co) polymeric ring-shaped polyolefin containing at least one repeating unit represented by the following formula (II) and at least one repeating unit represented by the formula (I) (Co) polymeric ring-like polyolefin.

An additional (co) polymer (including a ring-opening (co) polymer) containing at least one cyclic repeating unit represented by the general formula (III) is also preferably used.

Further, an additional (co) polymeric ring-shaped polymer having at least one repeating unit represented by the general formula (I), if necessary, in at least one of the repeating units represented by the general formula (III) Polyolefins can also be preferably used.

In the general formulas (II) to (III), m represents an integer of 0 to 4. R ¹ to R ^{6 each} represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms; X ¹ to X ³ and Y ¹ to Y ^{3 each} represent a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, hydrocarbon group of _{1 ~ 10, - (CH 2} ) n COOR 11, - (CH 2) n OCOR 12, - (CH 2) n NCO, - (CH 2) n NO 2, - (CH 2) n CN _{, - (CH 2) n CONR} 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ, - (CH 2) n W, or X ¹ and Y ^1, X ² and Y ² , or (-CO) ₂ O, (-CO) ₂ NR ¹⁵ composed of X ³ and Y ³ .

Also, ^{R 11, R 12, R 13} , R 14, R 15 is a group hydrocarbon of a hydrogen atom, 1 ~ 20, Z is a group of hydrocarbon substituted with a hydrocarbon group, or a halogen, W is SiR ¹⁶ _P D _{3 -P} (wherein R ¹⁶ represents a hydrocarbon group of 1 to 10 carbon atoms, D represents a halogen atom, -OCOR ¹⁶ or -OR ¹⁶ , p represents an integer of 0 to 3), and n represents an integer of 0 to 10.

(Rth) in the thickness direction of the optical compensation film is increased by introducing a functional group with high polarizability into the substituents of X ¹ to X ³ and Y ¹ to Y ³ to increase the in-plane retardation (Re) . The optical compensation film having a high Re-expressing property can be stretched in the film-forming process to increase the Re value.

The norbornene-based additional (co) polymer is disclosed in Japanese Laid-Open Patent Publication No. 10-7732, Japanese Patent Publication No. 2002-504184, US2004229157A1, and WO2004 / 070463A1. Is obtained by addition polymerization of norbornene polycyclic unsaturated compounds.

If necessary, norbornene based polycyclic unsaturated compounds and conjugated dienes such as ethylene, propylene, butene, butadiene and isoprene; Nonconjugated dienes such as ethylidene norbornene; Acrylic acid, maleic anhydride, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate, and vinyl chloride may be addition-polymerized.

This norbornene addition polymer (co) polymer is commercially available under the trade name Aper from Mitsui Chemicals, Inc., and has a glass transition temperature (Tg) different from that of APL8008T (Tg 70 DEG C), APL6013T (Tg 125 DEG C) Or APL6015T (Tg 145 DEG C). In addition, pellets such as TOPAS8007, 6013 and 6015 are available from Polyplastics Co., Ltd. Appear3000 is also being released at Ferrania.

The norbornene-based polymer hydride is disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19801, As disclosed in Japanese Unexamined Patent Application Publication No. 2003-159767 or Japanese Unexamined Patent Application Publication No. 2004-309979, by carrying out addition polymerization or metathesis ring-opening polymerization of a polycyclic unsaturated compound, followed by hydrogenation.

In the norbornene polymer used in the present invention, R ⁵ to R ⁶ are preferably a hydrogen atom or -CH ₃ , and X ³ and Y ³ are preferably a hydrogen atom, Cl, -COOCH ₃ , The group is appropriately selected.

This norbornene resin is sold under the trade name Arton G or Aton F by JSR Corporation and Zeonor ZF14, ZF16, Zeonex 250, Or Zeonex 280, and they can be used.

[Resin Having Positive Intrinsic Birefringence and Resin Having Negative Intrinsic Birefringence]

On the other hand, it is preferable to mix or laminate a polymer having a positive intrinsic birefringence and a polymer having a negative intrinsic birefringence in view of optical characteristics (satisfying the above expressions (3) to (4)). Examples thereof include those disclosed in Japanese Laid-Open Patent Publication Nos. 2004-309979, 2005-126576, 2003-292639, 2006-058540, 2004 -325971, but is not limited thereto.

<Production method of optical compensation film>

As a result of intensive studies, the present inventors have found that a cellulose acylate film having the desired optical properties can be obtained by a production method comprising a stretching process for stretching a film and a shrinking process for shrinking.

Here, the initiation of the shrinking process refers to a time at which the dimension of the film begins to substantially decrease, and the decrease of the film dimension may be caused by, for example, application of a physical external force to the film, And the case of not being subjected to physical external force application. The termination of the shrinking process refers to when the reduction of the dimensions of the film substantially ends.

Likewise, at the start of the stretching process, the dimension of the film substantially begins to increase, and the increase in the dimension of the film is due to, for example, physical stretching by applying a force to the film. The termination of the stretching process refers to a time at which the stretching process is terminated physically by stopping the application of the force to the film.

In the present invention, in particular, it is preferable to use a stretching process for stretching the film in the transport direction, a stretching process for stretching the film in the transverse direction, a stretching process for stretching the film in the transverse direction, And a shrinking step of shrinking in the carrying direction is preferably used.

First, a description will be given of a stretching step of stretching in the transport direction of the film, and a shrinking step of shrinking the film while grasping the film in the width direction of the film.

In this case, the film is stretched in the transport direction of the film. As a method of stretching in the transport direction of the film, a plurality of rolls are provided with a main speed difference (peripheral speed difference) Direction is preferably used. In the film formation by the solution softening method, when the film which has become semi-dry by being softened on a band or drum of stainless steel is peeled off, the speed of the conveying roller of the film is adjusted so that the film take- Is also preferably used.

In the width direction of the film, the both ends of the film are held while being gripped by a device called a tenter which fixes the film with a clip or a pin, and the width of the tenter is gradually narrowed so that the film can be shrunk substantially perpendicular to the stretching direction.

The stretching process and the shrinking process can be carried out in a sequence of one of stretching, shrinking, shrinking and stretching in a sequential manner.

It is also possible to grasp the film by a tenter which operates in two axial directions of the transport direction and the width direction of the film, such as sieve recognition, screw type, pantograph type, linear motor type and the like, The width of the tenter may be gradually narrowed to shrink in the orthogonal direction.

On the other hand, in a manufacturing method including a stretching step in which the film is stretched in the width direction and a shrinking step in which the film is shrunk in the carrying direction, the film is conveyed in the direction of conveyance, such as the body recognition, the screw type, the pantograph type, The film can be shrunk by gripping by a tenter operating in two axial directions in the width direction and gradually narrowing the interval of the clips in the transport direction while stretching in the width direction of the film.

As described above, at least a part of the stretching process and the shrinking process can be said to be performed at the same time by the method using the tenter which operates in the biaxial direction of the transport direction and the width direction of the film. As a result of research conducted by the present inventors, it has been found that this simultaneous treatment has an advantage that it is easy to reduce unevenness of stretching and shrinkage in a film surface called a bowing, by adjusting the timing, magnification and speed of stretching and shrinking.

Further, as a stretching apparatus specifically embodying a stretching process of stretching either one of the longitudinal direction or the transverse direction of the film and simultaneously shrinking the other one and increasing the film thickness of the film, FITZ manufactured by Ichiken Kogyo Co., And the like can be preferably used. This device is described in Japanese Patent Application Laid-Open No. 2001-38802.

Here, as a result of intensive studies, the inventors of the present invention have conducted studies on the elongation in the stretching process and the shrinkage ratio in the shrinking process, and have found that the relationship (2) is satisfied while limiting Re to a desired range (for example, 50 to 200 nm) , It was found that it is effective that the relationship between the elongation percentage X% in the stretching step and the shrinkage percentage Y% in the shrinking step satisfies the following formula (Z).

&Quot; (3) &quot;

When the relationship between the elongation and the shrinkage ratio is less than the lower limit of the formula (Z), technical solutions such as the combination of special additives and blending of different polymers are required in order to satisfy the desired Re and the relationship of the formula (2) And other problems such as an increase in manufacturing cost are caused. On the other hand, when the relationship between the elongation and the shrinkage ratio exceeds the upper limit of the formula (Z), the elongation and wrinkling of the film after the shrinking process occur, making it impossible to use the film as an optical compensation film.

In the present invention, the term "elongation" as used herein means a rate at which the length of the film after stretching is increased relative to the length of the film before stretching in the stretching direction, and the term "shrinkage" means the ratio of the length of the film after shrinkage Means the ratio of the length of the shrinkage.

In the range satisfying the above formula (Z), the elongation is preferably 5 to 45%, more preferably 10 to 30%. The shrinkage percentage is preferably 3 to 25%, more preferably 5 to 15%.

In order to achieve the desired optical properties, the stretching and shrinking process is preferably carried out at a glass transition temperature of the film at the time of processing plus (5 to 50) ° C.

The optical compensation film produced by the production method of the present invention preferably satisfies the following formula (A).

In the following formula (A), Rth (550) 10% RH and Rth (550) 60% RH are Rth (550) at 25 ° C and 60% RH, respectively.

10 ≥│Rth (550) 10% RH - Rth (550) 60% RH│ Formula (A)

(A) indicates that the absolute value of the difference between the value measured at 25 占 폚 and 60% RH and the value measured at 25 占 폚 and 10% RH in the thickness direction retardation Rth (?) Is preferably 10 nm or less .

The absolute value of the difference between the value measured at 25 캜 and 60% RH in the thickness direction retardation Rth and the value measured at 25 캜 and 10% RH is more preferably 5 nm or less.

In the present invention, the glass transition temperature was measured by measuring a film sample (unstretched) of 5 mm x 30 mm using a dynamic viscoelasticity measuring device (Vibron: DVA-225, manufactured by Haitian Instrumentation Control Co., Ltd.) The storage elastic modulus at the major axis in the longitudinal axis and the temperature (占 폚) in the linear axis at the major axis, the storage elastic modulus at 20 占 폚, the temperature rise rate at 2 占 폚 / min, the measurement temperature range from 30 to 200 占 폚, The glass transition temperature (Tg), which is a temperature at which the storage elastic modulus is abruptly reduced, which is observed when the transition from the solid region to the glass transition region is made.

Concretely, on the obtained chart, the intersection of the straight line 1 and the straight line 2 when the straight line 1 is drawn in the solid region and the straight line 2 is drawn in the glass transition region shows that the storage elastic modulus at the time of temperature increase sharply decreases and the film softens The glass transition temperature (Tg) (dynamic viscoelasticity) was defined as the temperature at which the glass transition temperature starts to shift to the glass transition region.

The temperature of the horizontal axis is the temperature of the film surface measured by a non-contact infrared thermometer.

The present invention can be carried out by wet stretching in which the film formed by the solution casting method is stretched during drying.

Further, the film formed by the melt extrusion method, or the solution film-forming film may be subjected to a continuous drawing process after drying, or may be subjected to separate drawing process once it has been wound.

It may also be applied to stretching a film formed by a melting method substantially free of a solvent.

The film may be stretched or shrunk in one stage or in multiple stages. In the case of multi-stage execution, the product of the respective draw magnifications may be within the preferable range described above.

The stretching speed is preferably 5 to 1,000% / minute, more preferably 10 to 500% / minute. The stretching is preferably performed by a heat roll and / or a radiant heat source (such as an IR heater) or warm air.

On the other hand, in order to satisfy the relationships of the above formulas (1) to (2), it is preferable that the optical compensation film before stretching satisfies the following formulas (5) to (6).

-20? Reb (550)? 20 ... ... ... Equation (5)

-20? Rthb (550)? 20 ... ... Equation (6)

Reb (550) is the in-plane retardation value (unit: nm) of the optical compensation film before stretching measured at 550 nm wavelength, and Rthb (550) is the retardation value (Unit: nm) of the optical compensation film before stretching measured by light.)

In order to realize the optical properties of the above formulas (5) to (6), it is preferable to form a preheating step for preheating the film before the stretching step. The use temperature in this preheating step is preferably the glass transition temperature + (25 to 100) ° C. The heat treatment time is preferably from 1 second to 3 minutes.

Further, heat treatment may be performed after the stretching process. The heat treatment temperature is preferably 20 ° C to 10 ° C higher than the glass transition temperature of the cellulose acetate film, and the heat treatment time is preferably 1 second to 3 minutes.

The heating method may be zone heating or partial heating using an infrared heater. Both ends of the film may be slitted during or at the end of the process. These slit debris is preferably recovered and reused as a raw material.

Japanese Patent Application Laid-Open No. 11-077718 discloses a tenter. In drying a web while maintaining the width of the tenter, a dry gas blowing method, a take-out angle, a wind speed distribution, a wind speed, A technique for securing prevention of quality deterioration such as planarity at the time of increasing the speed by the solution casting method or widening the web width by appropriately controlling the use of the air flow rate difference, the vertical blowing air flow rate, and the high- have.

Japanese Unexamined Patent Application Publication No. 11-077822 discloses an invention in which a stretched thermoplastic resin film is subjected to a heat treatment in a thermal relaxation process after forming a temperature gradient in the width direction of the film in order to prevent occurrence of unevenness have.

Further, in order to prevent the occurrence of unevenness, JP-A-4-204503 discloses an invention in which the solvent content of the film is 2 to 10% based on the solid content.

Further, in order to suppress the curl by the definition of the clip engagement width, Japanese Laid-Open Patent Publication No. 2002-248680 discloses that curling is suppressed by stretching the tenter clip engagement width D? (33 / (log elongation x log volatile content) There is disclosed an invention for facilitating film transportation after the stretching process.

Further, in order to make both high-speed film conveying and stretching compatible, JP-A-2002-337224 discloses an invention in which a tenter conveyance is switched to a half pin and a half clip.

Japanese Patent Application Laid-Open No. 2002-187960 discloses a method for easily improving the viewing angle characteristics and also for improving the viewing angle, in which a cellulose ester dope liquid is softened to a softening supporter and then a web (Film) is stretched by 1.0 to 4.0 times in at least one direction while the amount of residual solvent in the web is in the range of 100 mass% or less, particularly 10 to 100 mass%. As a further preferred embodiment, it is described that the film is stretched by 1.0 to 4.0 times in at least one direction while the amount of the residual solvent in the web is in the range of 100 mass% or less, particularly 10 to 100 mass%.

Further, in order to produce a retardation film having little bleed-out of the additive, no delamination between the layers, further excellent slidability, and excellent transparency, the composition disclosed in JP-A-2003-014933 Dope A containing a resin, an additive and an organic solvent, and a dope B containing no additive or containing a resin having an additive content smaller than Dope A, an additive and an organic solvent were prepared, , The dope B is covalently fired on the support so as to be a surface layer, the organic solvent is evaporated until it becomes detachable, the web is peeled from the support, and the residual solvent in the resin film at the time of stretching is 3 to 50 mass% In a range of from 1.1 to 1.3 times in at least one axial direction.

In a preferred embodiment, the web is peeled from the support and stretched at least in the uniaxial direction by 1.1 to 3.0 times at a stretching temperature in the range of 140 to 200 占 폚, dope A containing the resin and the organic solvent, A dope B containing fine particles and an organic solvent is prepared, the dope A is covalently fired on the support so that the core layer and the dope B become the surface layer, the organic solvent is evaporated until the separation becomes possible, the web is peeled from the support , And the stretching temperature is in the range of from 1.1 to 3.0 times at least in the uniaxial direction within the range of from 3 to 50 mass% of the residual solvent amount in the resin film at the time of stretching, Doping A containing a resin, an organic solvent and an additive, a resin containing no additive, a resin having an additive content smaller than Dophen A, an additive and an organic solvent Dope B containing a resin and fine particles and an organic solvent is prepared so that the core layer, the dope B, the surface layer, and the dope C are surface layers on the side opposite to the dope B, The web is peeled off from the support after the organic solvent is evaporated until the film becomes peelable and the stretched film is stretched at least 1.1 to 3.0 times in the uniaxial direction within the range of the residual solvent amount in the resin film in the range of 3 to 50 mass% The amount of the additive in the dope A is 1 to 30 mass% with respect to the resin, the amount of the additive in the dope B is 0 to 5 mass% with respect to the resin, and the elongation at the stretching temperature is in the range of 140 to 200 deg. The additives are plasticizers, ultraviolet absorbers or retardation adjusting agents, and the organic solvents in the dope A and the dope B are methylene chloride or methyl acetate, It has been described to use to contain 50 mass% or more with respect to the sheet.

Japanese Laid-Open Patent Publication No. 2003-004374 discloses a drying apparatus in which the hot wind of the dryer does not touch the marginal portion of the web, in order to prevent foaming of the web of tenter drying, The width of which is shorter than the width of the web.

Japanese Laid-Open Patent Publication No. 2003-019757 discloses a method of forming a car windshield on the inside of both ends of a web so as to prevent the tenter from drying air on the holding portion of the tenter in order to prevent foaming of the web of the tenter drier, The invention is described.

In order to stably carry out transportation and drying, Japanese Unexamined Patent Publication No. 2003-053749 discloses that the thickness after drying of both ends of a film carried by a pin tenter is X m, the average thickness after drying of the product portion of the film is T m 40 + (T - 60) x 0.2? X? 300 when the relationship between X and T is 40? X? 200 and 60 <T? (T-120) x 0.2 &lt; = X &lt; = 400 when the formula (3) is 120 &lt; T.

In order to prevent wrinkles from occurring in the multistage tenter, Japanese Unexamined Patent Publication (Kokai) No. 2-182654 discloses a tenter apparatus in which a heating chamber and a cooling chamber are formed in a dryer of a multistage tenter, and left and right clip- The invention is described.

Japanese Laid-Open Patent Publication No. 9-077315 discloses an invention in which the pin density of the pin tenter is made large and the pin density of the outside is made small in the pin of the pin tenter in order to prevent the web from being broken, wrinkled and conveyed .

In order to prevent the foaming of the web and the web from adhering to the holding means in the tenter, Japanese Unexamined Patent Publication (Kokai) No. 9-085846 discloses a tenter drying apparatus in which both side edge holding fins of a web Cooling the web to less than the foaming temperature of the web and cooling the fin just before tightening the web to a gelling temperature of the dope-type cooler of +15 DEG C or less.

Japanese Unexamined Patent Application Publication No. 2003-103542 discloses a pin tenter in which a boron structure is cooled and a surface temperature of a web in contact with the boron structure is set to be higher than that of a web The gelation temperature of the solution is not exceeded.

In addition, in order to prevent the deterioration of the quality such as the flatness at the time of increasing the speed by the solution softening method or widening the width of the web in the tenter, Japanese Unexamined Patent Publication No. 11-077718 discloses a method of drying a web in a tenter , A wind speed of 0.5 to 20 (40) m / s, a lateral temperature distribution of 10% or less, a web vertical air volume ratio of 0.2 to 1, and a dry gas ratio of 30 to 250 J / Kmol.

Also, in drying in a tenter, preferable drying conditions are disclosed depending on the amount of the residual solvent.

Specifically, it is preferable that the take-out angle from the blow-out port is in the range of 30 to 150 ° with respect to the plane of the film until the amount of the residual solvent in the web after peeling from the support is 4 mass% The web is dried by extracting the drying gas with the difference between the upper limit value and the lower limit value within 20% of the upper limit value based on the upper limit value of the air velocity on the basis of the upper limit of the air velocity on the film surface located in the direction of extension of the film, When the amount of the residual solvent is less than 70% by mass and equal to or more than 4% by mass, it is preferable that the air velocity on the web surface of the dry gas taken out from the take-out drier is not less than 0.5 m / sec and not more than 20 m / , And the drying gas is blown off at a blowing rate of the drying gas of not less than 0.5 m / sec and not more than 40 m / sec. The temperature distribution of the drying gas in the width direction When the amount of the residual solvent in the web is 4 mass% or more and 200 mass% or less, the difference between the upper limit value and the lower limit value is set to 10% or less of the upper limit value. The air-to-air ratio q of the dry gas taken out from the combustion chamber is 0.2? Q? 1.

In addition, as a preferable embodiment, at least one kind of gas is used as the dry gas and the average specific heat thereof is not less than 31.0 J / K · mol and not more than 250 J / K · mol, And drying with a dry gas having a saturated vapor pressure of 50% or less.

In order to prevent the deterioration of the flatness and the application due to the generation of contaminants, Japanese Patent Application Laid-Open No. 11-077719 discloses an apparatus for producing triacetylcellulose (TAC) The invention is described.

As a more preferable embodiment, it is possible to form a device for removing foreign matter generated at the contact portion between the clip and the web, until the clip of the tenter releases the web and then carries the web again, The residual amount of the clip or pin when contacting the web is 12 mass% or more and 50 mass% or less; the surface temperature of the contact portion of the clip or pin with the web is 60 ° C or more and 200 ° C or less ( More preferably 80 ° C or more and 120 ° C or less), and the like.

In order to improve the flatness and improve the quality deterioration due to the tearing in the tenter and to improve the productivity, Japanese Unexamined Patent Application Publication No. 11-090943 discloses a tenter clip in which an arbitrary transporting length Lt (m) And the ratio Lr = Ltt / Lt of the total length Ltt (m) of the lengths of the portions of the tenters having the same length as the length Lt in which the web is held in the transport direction is 1.0? Lr? 1.99. As a more preferable aspect, it is disclosed that the portion for holding the web is arranged without a gap when viewed from the web width direction.

Japanese Unexamined Patent Application Publication No. 11-090944 discloses an apparatus for producing a plastic film in which a web width direction in front of an entrance of a tenter is provided in order to quantify the deterioration of planarity and introduction instability caused by looseness of a web when introducing a web into a tenter, Of the present invention is described.

Further, as a more preferable embodiment, it is preferable that the loosening suppression device is a rotary roller which rotates in an angle range of 2 to 60 degrees in the width direction, with an intake device on the upper part of the web, And an air blower having an air blower.

Japanese Unexamined Patent Application Publication No. 11-090945 discloses a method of producing a TAC in which a web peeled from a support is introduced into a tenter at an angle with respect to a horizontal direction with the aim of preventing deterioration in quality and deterioration in productivity, Is disclosed.

Further, in order to make a film having a stable physical property, Japanese Unexamined Patent Publication (Kokai) No. 2000-289903 discloses a conveying apparatus which transports the web with tension in the width direction of the web at a time point of peeling and a solvent content of 50 to 12 mass% A holding means of the web and holding means of the web and a web width is calculated from the signal of the detection by the width detection of the web having two or more variable bending points and the position of the bending point is changed.

Japanese Patent Laid-Open Publication No. 2003-033933 discloses a method for forming a film on the left and right sides of the vicinity of the entrance of the tenter, A guide plate for preventing the web edge from being curled is disposed at least downward of the guide plate and the web facing surface of the guide plate is constituted by a web contacting resin portion and a web contacting metal portion which are arranged in the web conveying direction .

In a further preferred embodiment, the web-contacting resin portion of the guide plate on the upstream side in the web conveying direction, the web-contacting metal portion on the downstream side thereof, the web- (Including inclination) between the metal portions is within 500 占 퐉, the distance in the width direction in contact with the web of the web-contacting resin portion and the web-contacting metal portion of the guide plate is 2 to 150 mm, And the distance in the web conveying direction in contact with the web of the web contact metal part of the guide plate is 5 to 120 mm, And the web-contacting resin portion of the guide plate is made of a single resin. The distance between the web facing surfaces of the guide plates disposed above and below the left and right side edges of the web is 3 to 30 mm The distance between the web facing surfaces of the upper and lower guide plates at the left and right side edge portions of the web is enlarged at a ratio of 2 mm or more per 100 mm of width toward the inside of the web in the width direction, The upper and lower guide plates are each arranged to have a length of 10 to 300 mm on both side edges and the upper and lower guide plates are arranged so as to be shifted forward and backward along the conveying direction of the web and the distance between the upper and lower guide plates -200 to +200 mm, the web facing surface of the upper guide plate is made of only resin or metal, the resin part for web contact of the guide plate is made of Teflon (registered trademark) and the metal part for web contact is made of stainless steel The surface roughness of the web facing surface of the guide plate or the web contacting resin portion and / or the web contacting metal portion formed thereon is 3 μm or less, etc. It can control.

It is also described that the installation position of the upper and lower guide plates for preventing the occurrence of curls on the side of the web is preferably between the peeling-side end of the support and the tenter-inlet portion, more preferably at a portion near the inlet of the tenter.

Further, in order to prevent cutting and unevenness of the web during drying in the tenter, Japanese Patent Application Laid-Open No. 11-048271 discloses a method of stretching and drying with a width stretching device at a time point of 50 to 12 wt% , And a pressure of 0.2 to 10 KPa is applied from both sides of the web by a pressurizing device when the solvent content of the web is 10 wt% or less.

In a more preferred embodiment, when the pressure is applied using a nip roll as a method of ending the tension application at a solvent content of 4 mass% or more or applying pressure from both sides of the web (film), the nip roll pair is 1 to 8 It is also disclosed that the set temperature is preferably 100 to 200 DEG C in the case of pressurization.

Japanese Laid-Open Patent Publication No. 2002-036266, which is an invention for obtaining a high-quality thin TAC having a thickness of 20 to 85 탆, is characterized in that the difference in the tension acting on the web in the conveying direction before and after the tenter is 8N / Mm &lt; 2 &gt;, a preheating step of preheating the web after the peeling step, a stretching step of stretching the web using the post-tenter in the preheating step, and a step of stretching the web after the stretching step, And a mitigating step of mitigating only a smaller amount of damage.

Pre-heating step and the drawing step the temperature (T ₁₎ to (glass transition temperature (Tg) of the film - 60) in the temperature (T ₂₎ in the above ℃, and also mitigation process (T ₁ - 10) The elongation ratio of the web in the stretching step is set to 0 to 30% as a ratio to the web width just before entering the stretching step, and the elongation of the web in the relaxation step is set to -10 to 10% .

Further, Japanese Patent Application Laid-Open No. 2002-225054 discloses a method for producing a thin film having a dry film thickness of 10 to 60 占 퐉 and a light weight moisture permeable breathable article, S = {(Nx + Ny) / 2} - Nz, where the length of the web is held by a clip, (Where Nx is the refractive index in the direction with the greatest refractive index in the plane of the film, Ny is the refractive index in the direction perpendicular to the plane with respect to Nx, and Nz is the refractive index in the direction perpendicular to the plane of the film) And the time from softening to peeling is set to 30 to 90 seconds, and the web after peeling is stretched in the width direction and / or the longitudinal direction.

Japanese Unexamined Patent Publication No. 2002-341144 discloses a solution casting method having a stretching process and having a higher optical distribution as the mass concentration of the retardation control (rising) agent approaches the center in the film width direction for suppressing optical unevenness .

In addition, Japanese Laid-Open Patent Publication No. 2003-071863, which is an invention for obtaining a haze-free film, preferably has a stretching magnification in the width direction of 0 to 100%, and when used as a polarizing plate protective film, it is preferably 5 to 20% , More preferably from 8 to 15%.

In addition, when used as a retardation film, the stretch ratio in the transverse direction is more preferably from 10 to 40%, and even more preferably from 20 to 30%, and Ro can be controlled by the stretch ratio, And the planarity of the finished film is excellent.

The amount of the residual solvent in the film when the tenter is applied is preferably 20 to 100% by mass at the start of the tenter, and the tenter is dried until the residual solvent amount of the film becomes 10% by mass or less By mass, and more preferably 5% by mass or less.

The drying temperature in the case of performing the tenter is preferably 30 to 150 ° C, more preferably 50 to 120 ° C, further preferably 70 to 100 ° C, and the lower drying temperature is preferably the ultraviolet absorber or plasticizer And the process contamination can be reduced. On the other hand, it is also disclosed that when the drying temperature is high, the film has excellent planarity.

Japanese Unexamined Patent Application Publication No. 2002-248639, which is an invention for reducing dimensional variation in length and width when stored under high temperature and high humidity conditions, discloses a method for producing a film in which a cellulose ester solution is plied on a support, , And the drying shrinkage is dried so as to satisfy the following formula: 0? Dry shrinkage (%)? 0.1 × residual solvent amount in peeling.

In a preferred embodiment, when the residual solvent amount of the cellulose ester film after peeling is in the range of 40 to 100 mass%, at least the residual solvent amount is reduced by 30 mass% or more while holding both ends of the cellulose ester film by tenter transportation, The amount of residual solvent at the outlet of the tenter carrier of the cellulose ester film after peeling is 40 to 100 mass% and the amount of the residual solvent at the outlet is 4 to 20 mass%; the tension for conveying the cellulose ester film by the tenter carrier And that the tension for transporting the cellulose ester film by the tenter transport and the tensile force in the transverse direction of the cellulose ester film are substantially equal to each other.

Further, in order to obtain a film having a thin film thickness and excellent optical isotropy and planarity, Japanese Unexamined Patent Publication (Kokai) No. 2000-239403 discloses that the relationship between the residual solvent ratio X at the time of peeling and the residual solvent ratio Y at the time of introduction into the tenter is 0.3X Y &lt; / = 0.9X.

Japanese Unexamined Patent Application Publication No. 2002-286933 discloses a method for stretching a film to be formed by coextrusion, which includes a method of stretching under heating conditions and a method of stretching under solvent-containing conditions. In the case of stretching under heating conditions, It is preferable that the film is stretched at a temperature not higher than the vicinity thereof. On the other hand, in the case of stretching a film that has been formed into a film under solvent impregnation conditions, it is disclosed that the film once dried can be stretched again by contacting with a solvent and impregnating with a solvent .

[Melting film formation]

The production method of the optical compensation film of the present invention may be a melt film formation. Raw materials such as polymers and additives to be raw materials may be heated and melted, extruded and extruded and molded into a film by injection molding, or the raw material may be sandwiched between two heated plates and pressed to form a film.

The temperature of the heating and melting is not particularly limited as long as all of the raw polymer is uniformly melted and can be appropriately selected in accordance with the purpose. For example, it is heated to a temperature higher than the melting point or the softening point. In order to obtain a uniform film, a temperature higher than the melting point of the raw polymer is preferable, and a temperature higher by 5 to 40 캜 than the melting point is more preferable, and it is more preferable to heat and melt at a temperature 8 to 30 캜 higher than the melting point.

<Optically Anisotropic Layer>

As a method of controlling the Rth to be as small as possible, a method of applying and forming an optically anisotropic layer by a liquid crystal layer or the like is preferably used.

Specific examples of the liquid crystal layer include a method in which the discotic liquid crystal is oriented so that the angle between the circle and the optical compensation film surface is within 5 degrees (JP-A-10-312166) (Japanese Unexamined Patent Publication (Kokai) No. 2000-304932) in which the angle between the major axis and the above-mentioned optical compensation film plane is within 5 degrees.

This optically anisotropic layer contributes to the widening of the viewing angle contrast of a liquid crystal display device, in particular, a liquid crystal display device of OCB mode and VA mode, and a reduction in color deviation depending on the viewing angle.

The optical compensation film may be disposed between the polarizing plate on the observer side and the liquid crystal cell, between the polarizing plate on the back side and the liquid crystal cell, or may be disposed in both directions.

For example, it may be mounted as an independent member inside the liquid crystal display device, or may be mounted inside the liquid crystal display device as one member of the polarizing plate by imparting optical characteristics to the protective film for protecting the polarizing film and functioning as a transparent film.

[UV absorber]

It is preferable to use an ultraviolet absorber for the optical compensation film of the present invention.

The ultraviolet absorber is not particularly limited and may be appropriately selected according to the purpose. For example, an ultraviolet absorber such as a salicylate ester, benzophenone, benzotriazole, benzoate, cyanoacrylate, And benzophenone-based, benzotriazole-based, and salicylic ester-based ones are preferable.

Examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy 4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyl Oxybenzophenone, 2-hydroxy-4- (2-hydroxy-3-methacryloxy) propoxybenzophenone, and the like.

Examples of the benzotriazole-based ultraviolet absorber include 2 (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2 ) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-t-octylphenyl) benzotriazole and the like.

Examples of the salicylic ester series include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate.

Of these ultraviolet absorbers, particularly preferred are 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-methoxybenzophenone, 2- (2'- butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5' -trifluoromethylphenyl) (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole is preferable.

The ultraviolet absorber is preferably used in combination with a plurality of absorbents having different absorption wavelengths because a high shielding effect can be obtained over a wide wavelength range.

From the viewpoint of preventing deterioration of the liquid crystal, the ultraviolet absorber for liquid crystal is preferably excellent in absorbing ultraviolet rays having a wavelength of 370 nm or less and less absorbing visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Particularly, the benzotriazole-based compounds, benzophenone-based compounds and salicylic ester-based compounds exemplified above are preferable as ultraviolet absorbers, and among them, benzotriazole-based compounds are more preferable from the viewpoint of unnecessary coloring.

Examples of the ultraviolet absorber are described in Japanese Patent Application Laid-open No. 60-235852, Japanese Patent Application Laid-Open Nos. 3-199201, 5-1907073, 5-194789, 5-271471, 6-107854, 6-118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and 2000-204173 The compounds described in each publication can also be used.

The amount of the ultraviolet absorber to be added is preferably 0.001 to 5 mass%, more preferably 0.01 to 1 mass%, based on the polymer. When the addition amount is 0.001 mass% or more, the addition effect can be sufficiently exhibited, and when the addition amount is 5 mass% or less, bleeding-out of the ultraviolet absorbent onto the film surface can be suppressed.

The ultraviolet absorber may be added at the time of dissolving the polymer, or may be added to the dope after dissolution (in the case of solution film formation). Particularly, a form in which a ultraviolet absorber solution is added to the dope immediately before baking using a static mixer or the like is preferable because the spectral absorption characteristics can be easily adjusted.

[Deterioration inhibitor]

Also, for the purpose of preventing the optical compensation film from being deteriorated and decomposed, it is also preferable to appropriately use a deterioration inhibitor.

Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A No. 8-325537), guanidine compounds (JP-A No. 5-271471), benzotriazole UV absorbers (JP- 235819), and benzophenone-based UV absorbers (JP-A-6-118233).

[dyes]

In the present invention, a dye for color adjustment may be added. The content of the dye is preferably 10 to 1,000 ppm, more preferably 50 to 500 ppm, in terms of the mass ratio to the polymer. By including the dye in this way, it is possible to reduce the light piping of the optical compensation film and improve the yellowishness. These compounds are preferably added to the polymer solution or kneaded at the time of polymer melting.

[Matte Particles]

In the optical compensation film preferably used in the present invention, fine particles are preferably added as a matting agent. Examples of the fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate . The fine particles preferably contain silicon in that turbidity is lowered, and silicon dioxide is particularly preferable.

The fine particles of silicon dioxide preferably have a primary mean particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. It is more preferable that the average primary particle diameter is as small as 5 to 16 nm because the haze of the film can be lowered. The apparent specific gravity is preferably 90 to 200 g / L or more, more preferably 100 to 200 g / L or more. The larger the apparent specific gravity is, the more preferable is a high-concentration dispersion, and the haze and agglomerates are quantified.

When silicon dioxide fine particles are used as the matting agent, the amount of the silicon dioxide fine particles to be used is preferably 0.01 to 0.3 parts by mass based on 100 parts by mass of the polymeric component containing cellulose acylate.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 mu m, and exist as agglomerates of primary particles in the film, and form irregularities of 0.1 to 3.0 mu m on the surface of the film.

The average particle diameter of the secondary particles is preferably 0.2 탆 or more and 1.5 탆 or less, more preferably 0.4 탆 or more and 1.2 탆 or less, and still more preferably 0.6 탆 or more and 1.1 탆 or less. When the average particle diameter is 1.5 mu m or less, the haze is not excessively strengthened, and when the average particle diameter is 0.2 mu m or more, the effect of preventing squeaking is sufficiently exhibited.

The primary and secondary particle diameters of the fine particles are obtained by observing the particles in the film with a scanning electron microscope and setting the diameter of the circle circumscribing the particles to the particle diameter. Further, 200 particles are observed by changing the location, and the average value is regarded as the average particle diameter.

Examples of the fine particles of silicon dioxide include commercially available products such as "Aerosil" R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Aero Chemical Co., Can be used. The fine particles of zirconium oxide are commercially available, for example, under the trade names "Aerosil" R976 and R811 (manufactured by Aero Chemical Co., Ltd., Japan).

Of these, "Aerosil 200V" and "Aerosil R972V" are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more, and the turbidity of the optical compensation film is low So that the effect of lowering the coefficient of friction is great.

In the present invention, in order to obtain an optical compensation film containing particles having a small secondary average particle diameter, several methods can be considered when preparing a dispersion of fine particles.

For example, there is a method in which a fine particle dispersion in which a solvent and fine particles are mixed and stirred is prepared in advance, the fine particle dispersion is added to a small amount of a polymer solution prepared separately, stirred and dissolved, and mixed with the main polymer dope.

This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are also difficult to re-agglomerate.

In addition, there is also a method in which a small amount of polymer is added to a solvent, stirred and dissolved, and then the fine particles are added thereto and dispersed in a disperser, and this fine particle addition liquid is sufficiently mixed with the dope with an inline mixer.

In the present invention, although not limited to these methods, the concentration of silicon dioxide when dispersing the silicon dioxide fine particles in a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, And more preferably 15 to 20% by mass.

The higher the dispersion concentration, the lower the liquid turbidity with respect to the addition amount, and the haze and the agglomerate become positive. The amount of the matting agent to be added to the final polymer in the dope solution is preferably from 0.01 to 1.0 g, more preferably from 0.03 to 0.3 g, and still more preferably from 0.08 to 0.16 g per 1 m ² .

Examples of the lower alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. The solvent other than the lower alcohol is not particularly limited, but it is preferable to use a solvent used for forming the cellulose ester.

<Water content>

Also, the optical compensation film preferably used in the present invention has an equilibrium moisture content of 1.0% or less at 25 DEG C and 80% RH in order to reduce the color change of the liquid crystal display device over time.

The moisture content was measured by a Karl Fischer method using an optical compensation film sample 7 mm x 35 mm using a moisture analyzer (CA-03, manufactured by Mitsubishi Chemical Corporation) and a sample drying apparatus (VA-05, manufactured by Mitsubishi Chemical Corporation) . The water mass (g) is calculated by removing the sample mass (g).

&Lt; Modulus of elasticity &

The elastic modulus was measured by adjusting the humidity of the optical compensation film sample 10 mm x 150 mm at 25 ° C and 60% RH for 2 hours or more and then measuring the distance between the chucks using a tensile tester (Stroog-R2, manufactured by Toyo Seiki Seisaku- 100 mm, a temperature of 25 캜, and a drawing rate of 10 mm / min.

The measurement of the coefficient of hygroscopic expansion was carried out by measuring the value of the film L _{80 %} measured by a pin gauge at 25 ° C and 80% RH for 2 hours or more and the film left at 25 ° C and 10% RH for 2 hours or more, Was obtained from the value L _{10 %} measured by a gauge by the following equation (B).

(L _{80 %} - L _{10 %} ) / (80% RH - 10% RH) 10 ⁶ ... Formula (B)

<Hayes>

The haze of the optical compensation film preferably used in the present invention is preferably in the range of 0.01 to 2%.

In the present invention, the haze is measured in accordance with JIS K-6714 with a haze meter (HGM-2DP, manufactured by Suga Tester Co., Ltd.) at 25 占 폚 and 60% RH with an optical compensation film sample of 40 mm 占 80 mm.

<Change of dimension>

When the optical compensation film preferably used in the present invention is allowed to stand for 24 hours under conditions of 90 deg. C and 5% RH, dimensional changes when the film is allowed to stand still under the conditions of 60 DEG C and 95% RH for 24 hours It is preferable that the dimensional change of the resin composition is in the range of 0 to 5%.

<Photoelastic Coefficient>

In addition, the photoelastic coefficient of the optical compensation film of the present invention is preferably 50 x 10 &lt; ^-13 &gt; / dyne or less in order to improve uniformity when adhered to a liquid crystal display device.

As a specific measuring method, a tensile stress was applied to the optical compensation film sample in the major axis direction of 10 mm x 100 mm, and the retardation at that time was measured with an ellipsometer (M150, manufactured by Nippon Bunko K.K.) The photoelastic coefficient was calculated from the variation of the retardation.

(Polarizer)

According to the present invention, there is provided a polarizing plate comprising a polarizing film and a pair of protective films sandwiching the polarizing film, wherein at least one of the protective films (on the viewer side in the present invention) comprises a cellulose acylate film.

For example, a polarizing plate obtained by dying and stretching a polarizing film made of a polyvinyl alcohol film or the like with iodine, and laminating both sides thereof with a protective film can be used.

This polarizing plate is disposed outside the liquid crystal cell. It is preferable that a pair of polarizing plates composed of a polarizing film and a pair of protective films sandwiching the polarizing film are arranged so as to sandwich the liquid crystal cell.

It is preferable that the protective film disposed on the liquid crystal cell side is the optical compensation film of the present invention.

<Adhesive>

The adhesive for the polarizing film and the protective film is not particularly limited, but PVA resin (containing a modified PVA such as an acetacetyl group, a sulfonic acid group, a carboxyl group and an oxyalkylene group) and a boron compound aqueous solution and the like can be mentioned. Resins are preferred. The thickness of the adhesive layer is preferably 0.01 to 10 microns after drying, more preferably 0.05 to 5 microns.

<Consistent Manufacturing Process of Polarizing Film and Protective Film>

The polarizing plate usable in the present invention can be produced by a drying process in which a film for a polarizing film is stretched, followed by shrinking and decreasing the volatile content, wherein after the protective film is bonded to at least one side of the film after drying or drying, desirable.

As a concrete attaching method, a protective film is attached to a polarizing film by using an adhesive while both ends are kept in a drying process of the film, and then both ends are cut off, or after the film for polarizing film is released from both end holding portions after drying, After cutting, a protective film is attached. As the cutting method, a general technique such as a method of cutting with a cutter such as a blade or a method using a laser can be used.

After bonding, it is preferable to heat to dry the adhesive and to quantify the polarization performance. The heating conditions vary depending on the adhesive, but in the case of an aqueous system, the temperature is preferably 30 占 폚 or higher, more preferably 40 to 100 占 폚, and still more preferably 50 to 90 占 폚. These processes are more desirable in terms of performance and production efficiency to be manufactured in a consistent line.

<Performance of Polarizer>

It is preferable that the optical properties and durability (short-term and long-term storage stability) of the polarizing plate of the present invention are equivalent to or superior to those of a commercially available super high-contrast product (for example, HLC2-5618 manufactured by Sanritz Corporation).

Specifically, the visible light transmittance is 42.5% or more and the degree of polarization {(Tp-Tc) / (Tp + Tc)} ^1/2 ? 0.9995 (where Tp is the parallel transmittance and Tc is the orthogonal transmittance) The rate of change of light transmittance before and after 500 hours in an atmosphere of 90% RH and 500 hours in a dry atmosphere at 80 DEG C is preferably 3% or less, more preferably 1% or less, based on the absolute value. The change rate of the polarization degree is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

<Surface Treatment>

The surface of the optical compensation film of the present invention can be optionally treated to improve the adhesion to the cellulose acylate film or the polarizer layer of the polarizing plate.

As the surface treatment, for example, a glow discharge treatment, an ultraviolet ray irradiation treatment, a corona treatment, a flame treatment, an acid or an alkali treatment may be used.

The above-mentioned glow discharge process may be a low-temperature plasma occurring under a low-pressure gas of 10 ^-3 to 20 Torr, and further, a plasma treatment under atmospheric pressure is also preferable.

Plasma-excited gas means a plasma-excited gas under the above-mentioned conditions, and includes freon such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof.

These are described in detail on p. 30-32 of the Inventors Association Public Release No. 2001-1745 (published on March 15, 2001, Inventions Society).

In addition, the irradiation energy of 20 to 500 kGy is used at 10 to 1,000 keV, and more preferably, 20 to 300 kGy is used at 30 to 500 keV.

In the polarizing plate of the present invention, it is preferable that at least one layer of the hard coat layer, the antiglare layer, or the antireflection layer is formed on the surface (the visual side surface in the case of the present invention) of the protective film on at least one side of the polarizing plate.

That is, when a polarizing plate is used for a liquid crystal display device, it is preferable to form a functional film such as an antireflection layer on a protective film disposed on the opposite side of the liquid crystal cell. Examples of such functional films include a hard coat layer, Layer or more.

Further, it is not necessary to form each layer as a separate layer. For example, by providing the antireflection layer or the hard coat layer with a bridging function, instead of forming two layers of the antireflection layer and the antiglare layer, Or may function as an antistatic layer.

<Antireflection layer>

In the present invention, an antireflection layer in which at least a light scattering layer and a low refractive index layer are laminated in this order on a protective film of a polarizing plate, or an antireflection layer in which a medium refractive index layer, a high refractive index layer and a low refractive index layer are laminated in this order on a protective film . Hereinafter, preferred examples thereof will be described. Also, in the former configuration, the mirror reflectance generally becomes 1% or more, and is called a Low Reflection (LR) film. In the latter configuration, it is possible to realize a specular reflectance of 0.5% or less and is called an anti reflection (AR) film.

[LR film]

A preferred example of the antireflection layer (LR film) formed with the light-scattering layer and the low refractive index layer on the protective film of the polarizing plate will be described.

It is preferable that the light scattering layer is dispersed with the matte particles and that the refractive index of the material of the part other than the matte particle of the light scattering layer is in the range of 1.50 to 2.00 and the refractive index of the low refractive index layer is in the range of 1.20 to 1.49 .

In the present invention, the light-scattering layer combines the light-scattering property and the hard coat property, and may be a single layer or a plurality of layers, for example, two to four layers.

The antireflection layer has a surface irregularity shape with a center line average roughness (Ra) of 0.08 to 0.40 탆, a 10-point average roughness (Rz) of 10 times or less of Ra and an average irregularity distance (Sm) of 1 to 100 탆, The standard deviation of the height of the convex portion from the center line is not more than 0.5 占 퐉 and the standard deviation of the average irregularity distance Sm based on the center line is 20 占 퐉 or less and the inclination angle is 0 to 5 占 퐉 is 10% It is preferable since the antiglare property and the uniform mat feeling in the naked eye are achieved.

Also, since the colorimetry of the reflected light under the C light source is 0.5 to 0.99 in the range of the minimum value and the maximum value of the reflectance within the range of a * value of -2 to 2, b * value of -3 to 3 and 380 to 780 nm, It is preferable since it becomes micro-neutral.

Further, the b * value of the transmitted light under the C light source is 0 to 3, which is preferable because the yellow color of the white display when applied to a display device is reduced.

Furthermore, when a grid of 120 μm × 40 μm is inserted between the surface light source and the antireflection layer and the standard deviation of the luminance distribution when the luminance distribution is measured on the film is 20 or less, It is preferable because the glare when the polarizing plate of the present invention is applied is reduced.

The antireflection layer that can be used in the present invention is preferable because it can suppress the reflection of external light and improve the visibility by setting the optical characteristics to a mirror reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° gloss of 70% or less. In particular, the specular reflectance is more preferably 1% or less, and still more preferably 0.5% or less.

In addition, it is preferable that the haze is 20 to 50%, the ratio of the inner haze / total haze is 0.3 to 1, the haze value after forming the low refractive index layer from the haze value to the light scattering layer is within 15% 20 to 50%, and a transmittance ratio of 1.5 to 5.0 in the vertical transmission light / vertical direction from the vertical direction, is preferable because it prevents flickering on the fixed three LCD panels and dimming of letters and the like.

<Low Refractive Index Layer>

The refractive index of the low refractive index layer that can be used in the present invention is preferably 1.20 to 1.49, more preferably 1.30 to 1.44. It is preferable that the low refractive index layer satisfies the following formula (C) in terms of low reflectance.

(m / 4) λ × 0.7 <n L d L <(m / 4) λ × 1.3 ... ... Formula (C)

In the formula (C), m is a positive odd number, n _L is the refractive index of the low refractive index layer, and d _L is the film thickness (nm) of the low refractive index layer. In addition,? Is a wavelength and has a value in the range of 500 to 550 nm.

(Liquid crystal display device)

The polarizing plate obtained by bonding the above optical compensation film or polarizing film (including polarizing plate) is advantageously used in a liquid crystal display device, particularly a transmissive liquid crystal display device.

The transmissive liquid crystal display device comprises a liquid crystal cell and two polarizing plates disposed on both sides thereof. The polarizing plate is composed of a polarizing film and two transparent protective films disposed on both sides of the polarizing film. The liquid crystal cell carries liquid crystal between two electrode substrates.

One polarizing plate of the present invention is disposed on one side of the liquid crystal cell, or two polarizing plates are disposed on both sides of the liquid crystal cell.

It is preferable that the liquid crystal cell is a VA mode, an OCB mode, an IPS mode, or a TN mode.

<VA mode>

In the VA mode liquid crystal cell, the rod-shaped liquid crystal molecules are oriented substantially vertically when the voltage is not observed.

The liquid crystal cell of the VA mode includes (1) a VA mode liquid crystal cell of the VA mode in which the rod-like liquid crystalline molecules are oriented substantially vertically when the voltage is not applied and are oriented substantially horizontally when a voltage is applied (MVA mode) liquid crystal cell (SID97, Digest of tech. Papers 28 (1997) 845) in which a VA mode is multidomain for the purpose of enlarging the viewing angle, (3) a liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are vertically aligned substantially vertically when voltage is not applied and torsion multidomain is oriented when voltage is applied (Nippon Liquid Crystal Display, 1998), and (4) liquid crystal cells of SURVAIVAL mode (disclosed in LCD International 98).

In the VA mode liquid crystal display, it is preferable that the optical compensation film of the present invention is used in the viewer-side polarizing plate.

<OCB mode>

The liquid crystal cell of the OCB mode is a bend alignment mode liquid crystal cell in which the rod-shaped liquid crystalline molecules are oriented in substantially opposite directions (symmetrically) at the top and bottom of the liquid crystal cell. A liquid crystal display device using a liquid crystal cell of a bend alignment mode is disclosed in U.S. Patent Nos. 4583825 and 5410422, respectively. Since the rod-shaped liquid crystalline molecules are symmetrically oriented in the upper and lower portions of the liquid crystal cell, the liquid crystal cell in the bend alignment mode has a magneto-optical compensation function.

Therefore, this liquid crystal mode is also called OCB (Optically Compensatory Bend) liquid crystal mode. The liquid crystal display of the bend alignment mode has an advantage that the response speed is high.

<TN mode>

In the TN mode liquid crystal cell, the rod-shaped liquid crystalline molecules are substantially horizontally oriented and torsionally oriented at 60 to 120 degrees when the voltage is zero.

The TN mode liquid crystal cell is most often used as a color TFT liquid crystal display device, and is described in many documents.

According to the present invention, it is possible to provide an optical compensation film that corrects a liquid crystal cell accurately and optically compensates for color discrepancy depending on the viewing direction in high contrast and black display, a method of manufacturing the same, and a polarizing plate.

Further, according to the present invention, it is possible to provide a liquid crystal display device which prevents light leakage and obtains a good contrast.

Example

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

(Example 1)

Sodium hydroxide aqueous solution and ion-exchanged water were injected into a reaction tank equipped with a stirrer, a thermometer and a reflux condenser, and the monomer [A] shown by the following formula (6) and the monomer [B] shown by the following formula 50: 50 (mol%), and a small amount of hydrosulfite was added.

Next, methylene chloride was added thereto, and phosgene was blown at 20 DEG C for about 60 minutes.

Further, after p-tert-butylphenol was added to emulsify, triethylamine was added, and the reaction was terminated by stirring at 30 DEG C for about 3 hours.

After completion of the reaction, the organic phase was separated and methylene chloride was evaporated to obtain a polycarbonate copolymer. The composition ratio of the obtained copolymer was almost the same as the monomer injection ratio.

The water content of the obtained polycarbonate copolymer was 0.3%.

This copolymer and a cyanobiphenyl-based mixed liquid crystal product "BL007" manufactured by Merck are each dissolved in methylene chloride at a ratio of 96: 4 (parts by mass) to prepare a dope solution. A film 101 was prepared from this dope solution by a casting method.

A stretching device having a process of stretching the film 101 obtained in the above-mentioned direction in the width direction by using a tenter having a structure in which the continuous long film is narrowed while the lengthwise spacing of the tenter clips grips and transports the stretched film (Ichkane Industries Co., FITZ &quot; manufactured by Fuji Photo Film Co., Ltd.). After setting the film temperature at 170 占 폚 and passing through the heating zone after 30 seconds, stretching was started. The longitudinal direction of the film was relaxed to 0.77 times, And stretched to obtain an optical compensation film 111 having a film thickness of 60 m after stretching.

&Lt; Optical properties of film &

Re and Rth at the wavelengths of 450, 550 and 650 nm of the optical compensation film 111 were measured by KOBRA 21ADH (manufactured by Oji Instruments Co., Ltd.) according to the method described previously. The results are shown in Table 1.

As shown in Table 1, the values of Re and Rth at the wavelengths of 450, 550, and 650 nm of the optical compensation film (111) produced by the manufacturing method of the present Example 1 are as shown in the equations (1) to It was confirmed that all the relations were satisfied.

Reb and Rthb of the film 101 immediately before stretching were measured. As a result, Reb was 4 nm and Rthb was 10 nm.

&Lt; Production of polarizing plate &

<< Production of visual side polarizer >>

Iodine was adsorbed on the stretched polyvinyl alcohol film to prepare a polarizing film, and an optical compensation film 111 was attached to one surface of the polarizing film using an adhesive.

A saponification treatment was applied to a commercially available cellulose triacylate film (Fujisak TD80UF, manufactured by Fuji Photo Film Co., Ltd.), and the film was attached to the other surface of the polarizing film using a polyvinyl alcohol adhesive, And dried for 10 minutes or longer to prepare a polarizing plate 201.

At this time, the transmission axis of the polarizing film and the slow axis of the optical compensation film 111 were arranged in parallel. Further, the transmission axis of the polarizing film and the slow axis of the commercially available cellulose triacylate film were arranged so as to be perpendicular to each other.

&Lt; Preparation of Backlight-side Polarizer &

<< Preparation of Optical Compensation Film >>

[Formation of optically anisotropic layer]

After a commercially available cellulose acylate film (Z-TAC manufactured by Fuji Photo Film Co., Ltd.) was saponified, an alignment film coating liquid of the following composition was applied on this commercially available cellulose acylate film by a wire bar coater at 20 mL / m ² . Thereafter, the film was formed by drying for 60 seconds with hot air at 60 DEG C and for 120 seconds with hot air at 100 DEG C, respectively.

Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to form an orientation film.

[Composition of alignment film coating liquid]

10 parts by mass of modified polyvinyl alcohol shown by the following general formula (8)

Water 371 parts by mass

Methanol 119 parts by mass

Glutaraldehyde 0.5 part by mass

0.2 parts by mass of the compound represented by the following general formula (9)

Next, the optically anisotropic layer coating liquid of the following composition was applied on the alignment film so that Rth in the thickness direction after the wire roughening was 200 nm.

[Composition of optically anisotropic layer coating liquid]

1.8 g of a discotic liquid crystalline compound represented by the following general formula (10)

· Ethylene oxide-modified trimethylolpropane triacrylate

(V # 360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 0.2 g

Photopolymerization initiator (Irgacure 907, manufactured by Chiba Chemical Co., Ltd.) 0.06 g

0.02 g of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.)

Fluorine-containing polymer (Compound A shown by the following general formula (11)) 0.01 g

Methyl ethyl ketone 3.9 g

This was attached to the rim of the metal and heated for 3 minutes in a constant temperature bath at 125 캜 to orient the discotic liquid crystalline compound.

Next, the discotic liquid crystalline compound was crosslinked by UV irradiation for 30 seconds using a 120 W / cm high pressure mercury lamp. The temperature at the time of UV curing was set at 80 캜 to obtain an optically anisotropic layer.

The thickness of the optically anisotropic layer was 2.8 mu m. Thereafter, it was allowed to cool to room temperature. Thus, the optical compensation film 120 was produced. The optical characteristics of this optical compensation film 120 were measured and found to be Re (550) = 1 (nm), Rth (550) = 200 (nm) and Rth (450) / Rth (550) = 1.09.

Iodine was adsorbed on the stretched polyvinyl alcohol film to prepare a polarizing film, and an optical compensation film 120 was attached to one surface of the polarizing film using an adhesive.

A saponification treatment was applied to a commercially available cellulose triacylate film (Fujisak TD80UF, manufactured by Fuji Photo Film Co., Ltd.), and the film was attached to the other surface of the polarizing film using a polyvinyl alcohol adhesive, And dried for 10 minutes or longer to prepare a polarizing plate 300.

&Lt; Production of liquid crystal cell &

The liquid crystal cell was prepared by injecting a liquid crystal material ("MLC6608", manufactured by Merck Co.) having a cell gap of 3.6 mu m between substrates and having a negative dielectric constant anisotropy by injecting droplets between the substrates and forming a liquid crystal layer between the substrates. The retardation of the liquid crystal layer (that is, the product of the thickness d (占 퐉) of the liquid crystal layer and the refractive index anisotropy? N) was set to 300 nm. Further, the liquid crystal material was oriented so as to be vertically aligned.

<Mounting on VA panel>

The polarizing plate 201 having the optical compensation film 111 is disposed on the upper polarizer (viewing side) of the liquid crystal display device using the vertical alignment type liquid crystal cell so that the optical compensation film 111 is located on the liquid crystal cell side, In the lower polarizer plate (backlight side), a polarizing plate 300 provided with an optical compensation film 120 was provided such that the optical compensation film 120 was on the liquid crystal cell side.

The upper polarizer (polarizer 201) and the lower polarizer (polarizer 300) were attached to the liquid crystal cell via a pressure-sensitive adhesive. Nicols were arranged such that the transmission axis of the upper polarizer (polarizer 201) was in the vertical direction and the transmission axis of the lower polarizer (polarizer 300) was in the horizontal direction.

&Lt; Evaluation of color deviation &

A rectangle wave voltage of 55 Hz was applied to the liquid crystal cell. A white display of 5V, and a black display of 0V. The black display transmittance (%) at an azimuth angle of 45 degrees and a polar angle of 60 degrees in black display and the color deviation? X in azimuth angle of 45 degrees polar angle 60 and azimuth angle 180 degree polar angle 60 degree were evaluated based on the following evaluation criteria . The results are shown in Table 1.

[Evaluation Criteria of Color Deviation]

?:? X is less than 0.02

?:? X is 0.02 to 0.04

?:? X is 0.04 to 0.06

X:? X is 0.06 or more

&Lt; Evaluation of viewing angle &

The contrast ratio (white display / black display) was used as the contrast ratio, and the viewing angle (contrast ratio) was measured in eight steps from black display L1 to white display L8 using a measuring device (EZ- And a polar angle range in which the gray scale inversion of the black side was not observed at a ratio of 10 or more) were measured and evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation Criteria of Viewing Angle (a polar angle range in which the contrast ratio is 10 or more and there is no gray level inversion on the black side)

○: 80 ° or more in polar angle

○ △: Vertical angle of 80 ° or more in three directions

?: At least 80 degrees polar angle in two directions, up and down, right and left

X: Vertical angle of more than 80 degrees in 0 to 1 direction

&Lt; Evaluation of tolerance &

The viewing angle in a state in which the liquid crystal display device was left in an environment of 30 占 폚 and 90% RH for 250 hours was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation standard]

∘: ΔCu 'v' is less than 0.02

X:? Cu 'v' is 0.02 or more

(Example 2)

&Lt; Resin showing positive intrinsic birefringence value &gt;

Tricyclo [4,3,0,1 ^2,5 ] deca-3,7-diene (abbreviated as dicyclopentadiene, hereinafter abbreviated as "DCP"), tetracyclo [4,4,0,1 ^{2 , 5,17,10} ] dodeca-3-en (Tetracyclododecene, hereinafter abbreviated as "TCD") and 8-ethylidene-tetracyclo [4,4,0,1 ^2,5 , ^17,10 ] dodeca-3-ene (abbreviated as "ethylidene tetracyclododecene, hereinafter abbreviated as" ETD ") at a ratio of 47/28/35 (mass ratio) Followed by hydrogenation to obtain a ring-opening polymerization hydrogenation product (hereinafter abbreviated as norbornene-based polymer).

The ring-opening polymerized hydrogenated product had a glass transition point (Tg) of 130 占 폚 as measured by a differential scanning calorimeter (DSC), and a melt viscosity at a temperature of 250 占 폚 and a shear rate of 180 sec- ¹ of 980 Pa 占 퐏.

This norbornene polymer was used as the resin (A) having positive positive birefringence.

&Lt; Resin having negative birefringence value &gt;

As a resin (B) having negative intrinsic birefringence, a styrene-maleic anhydride copolymer (Daylaek D332, trade name: Nova Chemical Co., Ltd., melt viscosity 440 Pa · s, Tg = 130 ° C) was used. Hereinafter, this styrene-maleic anhydride copolymer is abbreviated as &quot; D332 &quot;.

<Retardation Control Agent>

Methylene bis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) as a retardation- Were used. This retardation regulator is commercially available from Asahi Kenshin Kogyo Co., Ltd. under the trade name ADEKASTAB LA-31. Hereinafter, the retardation adjusting agent is referred to as &quot; UVA &quot;.

A commercially available infrared absorbing agent (KAYASORB CY-17, manufactured by Nippon Kayaku Co., Ltd., maximum absorption wavelength: 782 nm) was used as a retardation adjusting agent showing dichroism. Hereinafter, this retardation adjusting agent is referred to as &quot; IR &quot;.

A first layer comprising the norbornene polymer, 100 parts by mass of the &quot; D332 &quot;, 4 parts by mass of the UVA, and 4 parts by mass of the IR, and a second layer comprising a mixture of ethylene (75 占 퐉) -third layer (7 占 퐉) -second layer (100 占 퐉) made of a vinyl acetate copolymer (trade name: MODEC AP543, manufactured by Mitsubishi Chemical Corporation) Layer laminate 102 having three layers and five layers laminated in this order from the side of the first layer (7 mu m) - the third layer (7 mu m) - the first layer (75 mu m) were coextruded using an extruder (trade name: LABOPLASTOMILI, Lt; / RTI &gt;

A stretching device having a step of stretching in the transverse direction by using a tenter having a structure in which the film (the layered product 102) obtained in the above manner is tapered while a continuous long film is grasped and conveyed in the longitudinal direction intervals of the tenter clips (Manufactured by Ichikane Kogyo K.K. under the trade name of &quot; FITZ &quot;), the film temperature was set to 130 DEG C, and after 30 seconds passed the heating zone, the stretching was started and the film length direction was relaxed to 0.70 times. And stretched 2.00 times in the width direction to obtain an optical compensation film 112 having a thickness of 60 mu m after stretching.

&Lt; Optical properties of film &

Re and Rth of the optical compensation film 112 at wavelengths of 450, 550 and 650 nm were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) according to the previously described method. The results are shown in Table 1.

As shown in Table 1, the values of Re and Rth at the wavelengths of 450, 550, and 650 nm of the optical compensation film 112 produced by the manufacturing method of Example 2 are the same as those of the formulas (1) to (4) Of the present invention.

Reb and Rthb of the film 102 immediately before stretching were measured. As a result, Reb was 3 nm and Rthb was 8 nm.

&Lt; Production of polarizing plate &

<< Production of visual side polarizer >>

(Polarizing plate 202) was produced in the same manner as in Example 1 except that the optical compensation film 112 was used in place of the optical compensation film 111 in the production of the visual side polarizing plate of Example 1 described above Respectively.

&Lt; Preparation of Backlight-side Polarizer &

<< Preparation of Optical Compensation Film >>

(Polarizing plate 300) was produced in the same manner as in the production of the backlight side polarizing plate of Example 1 described above.

&Lt; Production of liquid crystal cell &

A liquid crystal cell was produced in the same manner as in Example 1 described above.

<Mounting on VA panel>

The polarizing plate 202 and the polarizing plate 300 were mounted on the VA panel in the same manner as in Example 1 except that the polarizing plate 202 was used in place of the polarizing plate 201 in the mounting of the VA panel of Example 1 described above .

The viewing angle, color variation and resistance were evaluated in the same manner as in Example 1 described above. The results are shown in Table 1.

(Comparative Example 1)

A continuous elongate film of the film 101 prepared in Example 1 was fed to a conventional stretching device having a step of stretching the tenter clips in the width direction by using a tenter having a constant interval in the longitudinal direction, To obtain an optical compensation film 113 having a thickness of 60 m after stretching.

&Lt; Optical properties of film &

Re and Rth of the optical compensation film 113 at wavelengths of 450, 550 and 650 nm were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) according to the previously described method. The results are shown in Table 1.

As shown in Table 1, the values of Re and Rth at the wavelengths of 450, 550 and 650 nm of the optical compensation film (113) produced by the manufacturing method of this Comparative Example 1 satisfy the values of It was confirmed that the relationship was not satisfied at all.

&Lt; Production of polarizing plate &

<< Production of visual side polarizer >>

(Polarizing plate 203) was produced in the same manner as in Example 1 except that the optical compensation film 113 was used in place of the optical compensation film 111 in the production of the viewer side polarizing plate of Example 1 described above Respectively.

&Lt; Preparation of Backlight-side Polarizer &

<< Preparation of Optical Compensation Film >>

(Polarizing plate 300) was produced in the same manner as in the production of the backlight side polarizing plate of Example 1 described above.

&Lt; Production of liquid crystal cell &

A liquid crystal cell was produced in the same manner as in Example 1 described above.

<Mounting on VA panel>

The polarizing plate 203 and the polarizing plate 300 were mounted on the VA panel in the same manner as in Example 1 except that the polarizing plate 203 was used in place of the polarizing plate 201 in the mounting of the VA panel of Example 1 described above .

The viewing angle, color variation and resistance were evaluated in the same manner as in Example 1 described above. The results are shown in Table 1.

(Comparative Example 2)

&Lt; Preparation of cellulose acylate solution (CA-1) &gt;

The following composition was put into a mixing tank and stirred, and each component was dissolved to prepare a solution (CA-1) of cellulose acylate. Ac = acetyl group.

[Cellulose acylate solution (CA-1) composition]

100.0 parts by mass of cellulose acetate having an Ac substitution degree of 2.81

TPP (triphenylphosphate) 7.8 parts by mass

BDP (biphenyl diphenylphosphate) 3.9 parts by mass

Methylene chloride (first solvent) 402.0 parts by mass

Methanol (second solvent) 60.0 parts by mass

&Lt; Preparation of matting agent solution (MT-1) &gt;

20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were thoroughly stirred and mixed for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a dispersing machine together with the following composition, stirred for 30 minutes or more, and each component was dissolved to prepare a matting agent solution (MT-1).

[Matting agent solution (MT-1) composition]

10.0 parts by mass of a silica particle dispersion having an average particle diameter of 16 nm

Methylene chloride (first solvent) 76.3 parts by mass

Methanol (second solvent) 3.4 parts by mass

Cellulose acylate solution (CA-1) 10.3 parts by mass

&Lt; Preparation of additive solution &gt;

The following composition was put into a mixing tank, stirred while heating, and each component was dissolved to prepare an additive solution (AD-1). A retardation-generating agent represented by the following general formula (12) was used.

[Additive solution (AD-1) composition]

7.6 parts by mass of the retardation-imparting agent represented by the following general formula (12)

Methylene chloride (first solvent) 58.4 parts by mass

Methanol (second solvent) 8.7 parts by mass

Cellulose acylate solution (CA-1) 12.8 parts by mass

&Lt; Preparation of cellulose acylate film (103)

, 94.6 parts by mass of the cellulose acylate solution (CA-1), 1.3 parts by mass of the mat agent solution (MT-1) and 2.3 parts by mass of the additive solution (AD-1) Respectively.

In the above composition, the mass ratio of the retardation agent to the cellulose acylate was 1.0%.

Thereafter, the film was peeled from the band at a residual solvent amount of 30%, and dried at 140 DEG C for 40 minutes to prepare a cellulose acylate film (103).

The amount of the residual solvent of the obtained cellulose acylate film 103 was 0.2%, and the film thickness thereof was 100 占 퐉.

&Lt; Production of optical compensation film (114)

The cellulose acylate film 103 obtained above was continuously fed to a stretching apparatus having a step of stretching a continuous long film in the width direction using a tenter having a constant tenter spacing in the longitudinal direction, After passing through the heating zone for 30 seconds, stretching was started. The longitudinal direction of the film was relaxed by 0.85 times, stretched in the width direction by 1.25 times by a tenter clip, and the optical compensation film (114) &Lt; / RTI &gt;

<Optical characteristics of optical compensation film 114>

Re and Rth of the optical compensation film 114 at wavelengths of 450, 550 and 650 nm were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) according to the previously described method. The results are shown in Table 1.

As shown in Table 1, the values of Re and Rth at the wavelengths of 450, 550 and 650 nm of the optical compensation film 114 produced by the manufacturing method of this Comparative Example 2 are the same as those of the above- It was confirmed that the relationship was not satisfied at all.

Reb and Rthb of the film 103 immediately before stretching were measured. As a result, Reb was 7 nm and Rthb was 55 nm.

&Lt; Production of polarizing plate &

<< Production of visual side polarizer >>

(Polarizing plate 204) was produced in the same manner as in Example 1 except that the optical compensation film 114 was used in place of the optical compensation film 111 in the production of the visual side polarizing plate of Example 1 described above Respectively.

&Lt; Preparation of Backlight-side Polarizer &

<< Preparation of Optical Compensation Film >>

(Polarizing plate 300) was produced in the same manner as in the production of the backlight side polarizing plate of Example 1 described above.

&Lt; Production of liquid crystal cell &

A liquid crystal cell was produced in the same manner as in Example 1 described above.

<Mounting on VA panel>

The polarizing plate 204 and the polarizing plate 300 were mounted on the VA panel in the same manner as in Example 1 except that the polarizing plate 204 was used in place of the polarizing plate 201 in the mounting of the VA panel of Example 1 described above .

The viewing angle, color deviation and resistance were evaluated in the same manner as in Example 1 described above. The results are shown in Table 1.

(Comparative Example 3)

&Lt; Production of Optical Compensation Film 115 &gt;

A commercially available polycarbonate resin (Panlite, Teijin) was dissolved in methylene chloride to prepare a dope solution. A film 105 was produced from this dope solution by a casting method.

A stretching device having a step of stretching the film 105 obtained in the above-mentioned direction in the width direction by using a tenter having a structure in which a continuous long film is narrowed while the lengthwise spacing of the tenter clips grips and transports the stretched film (Ichkane Industries Co., FITZ &quot;), and stretched 1.5 times at a temperature of 160 DEG C to obtain an optical compensation film 115 having a thickness of 60 mu m after stretching.

<Optical characteristics of optical compensation film 115>

Re and Rth of the optical compensation film 115 at wavelengths of 450, 550 and 650 nm were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) according to the previously described method. The results are shown in Table 1.

&Lt; Production of polarizing plate &

<< Production of visual side polarizer >>

(Polarizing plate 205) was produced in the same manner as in Example 1 except that the optical compensation film 115 was used in place of the optical compensation film 111 in the production of the viewer side polarizing plate of Example 1 described above Respectively.

&Lt; Preparation of Backlight-side Polarizer &

<< Preparation of Optical Compensation Film >>

(Polarizing plate 300) was produced in the same manner as in the production of the backlight side polarizing plate of Example 1 described above.

&Lt; Production of liquid crystal cell &

A liquid crystal cell was produced in the same manner as in Example 1 described above.

<Mounting on VA panel>

The polarizing plate 205 and the polarizing plate 300 were mounted on the VA panel in the same manner as in Example 1 except that the polarizing plate 205 was used in place of the polarizing plate 201 in the mounting of the VA panel of Example 1 described above. Respectively.

The viewing angle, color variation, and resistance were evaluated in the same manner as in Example 1 described above. The results are shown in Table 1.

As shown in Table 1, the optical compensation films of Examples 1 and 2 satisfy the formulas (1) to (4), and thus the liquid crystal display provided with the polarizing plate having the optical compensation film of the present invention, Neutral black display can be realized in either one of them.

On the other hand, since the optical compensation films of Comparative Examples 1 to 3 did not satisfy the expressions (1) to (4), light leakage occurred in either the front direction or the viewing angle direction and the contrast was also poor.

Particularly, when the liquid crystal display device was observed under a condition of 30 ° C and 90% RH for 250 hours, it was confirmed that the viewing angle of Comparative Example 2 was remarkably deteriorated.

Therefore, the optical compensation film and the polarizing plate of the present invention enable the visual compensation of the VA state, the IPS state, and the OCB state, in almost all wavelengths. As a result, in the liquid crystal display device of the present invention, light leakage in the oblique direction in black display is reduced, and the viewing angle contrast is remarkably improved.

Further, since the present invention can realize a roll-to-roll production process in bonding with a polarizing plate, it is possible to provide an optical compensation film having excellent productivity

Further, since the liquid crystal display device of the present invention can suppress light leakage in oblique direction in black display in almost all visible light wavelength regions, color deviation in black display depending on viewing angle, which is a conventional problem, is greatly improved.

The liquid crystal display device of the present invention is not limited by the display mode of the liquid crystal cell and can provide a good contrast even in a liquid crystal display device having a liquid crystal layer of any of display modes such as VA mode, IPS mode, ECB mode, TN mode and OCB mode And can be suitably used for a mobile phone, a monitor for a PC, a television, a liquid crystal projector, and the like.

Claims (12)

delete delete delete A stretching step of stretching the film in either the longitudinal direction or the transverse direction and a shrinking step of shrinking the other direction, Satisfies the following expression (Z) when the elongation in the stretching step is X% and the shrinkage ratio in the shrinking step is Y%. [Equation 1]

5. The method of claim 4, The shrinking step is a step of shrinking the film by grasping and transporting the film by a tenter clip and by narrowing the distance in the transport direction of the tenter clip, Wherein the stretching step is a step of stretching the film in a direction orthogonal to the carrying direction. (Here, &quot; orthogonal &quot; means within a range of an exact angle of less than +/- 5 degrees.) delete 5. The method of claim 4, The optical compensation film before stretching satisfies the following expressions (5) to (6)  -20? Reb (550)? 20 ... ... Equation (5)  -20? Rthb (550)? 20 ... ... Equation (6) Reb (550) is an in-plane retardation value (unit: nm) of the optical compensation film before stretching measured with light having a wavelength of 550 nm, and Rthb (550) Is a retardation value in the thickness direction (unit: nm) of the optical compensation film before stretching measured by the following method. An optical compensation film produced by the method for producing an optical compensation film according to claim 4. A process for producing a polarizing plate, which comprises a step of bonding a long optical compensation film according to claim 8 with a polarizer and a roll-to-roll film. A polarizing plate produced by the method for producing a polarizing plate according to claim 9. (1) to (4), which is produced by a manufacturing method comprising a stretching step of stretching a film in either the longitudinal direction or the transverse direction and a shrinking step of shrinking the other direction, (7-1) and an optically anisotropic layer satisfying the following formula (7-2): &quot; (7-1) &quot; (Z) satisfies the following formula (Z) when the retardation in the stretching step is X% and the shrinkage ratio in the shrinking step is Y%. [Equation 1]

50? Re (550)? 200 ... ... ... ... ... ... ... Equation (1) 0.4? Rth (550) / Re (550)? 0.6 ... Equation (2) 0.1 &lt; Re (450) / Re (550) &lt; 0.95 ... Equation (3) 1.03 &lt; Re (650) / Re (550) &lt; 1.93 ... Equation (4) -10 &lt; Re (550) &lt; 10 ... ... ... Equation (7-1) 100 &lt; Rth (550) &lt; 300 ... Equation (7-2) Plane retardation value (unit: nm) measured with light having wavelengths of 450 nm, 550 nm and 650 nm, and Rth (550) and Re (650) (Unit: nm) in the thickness direction measured with light of 550 nm.) 12. The method of claim 11, Wherein the liquid crystal cell is in a VA mode.