TWI429993B - Optical compensating film, producing method thereof, polarizing plate, producing method thereof, and liquid crystal display device - Google Patents

Description

Optical compensation film and preparation method thereof, polarizing plate and preparation method thereof, and liquid crystal display device

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

The liquid crystal display device has a liquid crystal cell and a polarizing plate. In general, the polarizing plate 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 and stretched to form a protective film on both sides. Income.

In the transmissive crystal display device, one or more optical compensation films are disposed on the two sides of the liquid crystal cell.

In the reactive liquid crystal display device, a reflector, a liquid crystal cell, one or more optical compensation films, and a polarizing plate are usually disposed in this order. The liquid crystal cell system is composed of a liquid crystal molecule, two substrates for sealing, and an electrode layer for applying a voltage to liquid crystal molecules.

The liquid crystal cell has ON/OFF display due to the alignment state of the liquid crystal molecules, and either a transmissive type or a reflective type can be used. TN (Twisted Nematic), IPS (In-Plane Switching), and OCB (Optically Compensatory Bend) are proposed. ), VA (Vertically Aligned), ECB (Electrically Controlled Birefringence) display type.

In the LCD, a 90-degree twisted nematic liquid crystal display device which is driven by a thin film transistor is mainly used for a display having high display quality, mainly using nematic liquid crystal molecules having positive dielectric anisotropy (hereinafter Called TN type).

However, the TN type has excellent display characteristics when viewed from the front, but has reduced contrast when viewed from an oblique side, and has a viewing angle characteristic in which display characteristics such as reversal of inversion due to brightness are deteriorated in a gradation display. Therefore, it is strongly seeking this improvement.

In addition, the liquid crystal method of the wide viewing angle, which is called the IPS method, the OCB method, and the VA method, has increased the demand for liquid crystal televisions in recent years and has increased the compatibility. Each method also improves the display quality year after year, but the problem of color shift when viewing from the oblique side remains unresolved.

Moreover, the phase difference plate of the polymer alignment film, in particular, the quarter-wavelength plate, satisfies 0.6 < Δn. d(450)/△n. d(550)<0.97, 1.01<△n. d(650)/△n. D (550) < 1.35 (Δn.d (λ) is a phase difference of a polymer alignment film having a wavelength of λ nm) is known (refer to Japanese Laid-Open Patent Publication No. 2000-137116).

However, the method described in Patent Document 1 requires a television application having a very high display quality, and a sufficient color tone improving effect cannot be obtained.

The present invention has been made to solve the above problems and achieve the above object. In other words, the present invention has an object of providing an optical compensation film and a polarizing plate which are optically compensated correctly, and which have high contrast and improved color shift in relation to the viewing direction of the black display.

Further, the subject of the present invention is to improve the contrast and to improve the color shift property in relation to the viewing angle of the black display, in particular, the VA, IPS, and OCB type liquid crystal display devices.

In order to solve the above problems, the inventors of the present invention have conducted intensive studies and found the following findings. In other words, by setting the Rth/Re of the optical compensation film to approximately 0.5 by the predetermined extension condition, the knowledge of the color shift can be highly compensated.

The present invention is based on the above findings of the present inventors, and the method for solving the above problems is as follows. In other words, the optical compensation film of the present invention is characterized by satisfying the following formulas (1) to (4).

50≦Re(550)≦200.........Formula (1) 0.4≦Rth(550)/Re(550)≦0.6.........Formula (2) 0.1<Re(450)/Re(550)<0.95 .........the formula (3) 1.03<Re(650)/Re(550)<1.93.........the formula (4)

In the above formulas (1) to (4), Re (450), Re (550), and Re (650) are in-plane retardation values measured by light having wavelengths of 450 nm, 550 nm, and 650 nm (unit: nm) Rth (550) is a retardation value (unit: nm) in the thickness direction measured by light having a wavelength of 550 nm.

The method for producing an optical compensation film according to the present invention is characterized in that it includes an extension process for extending one of the longitudinal direction and the width direction of the film, and a shrinkage process for shrinking the other direction.

The method for producing a polarizing plate according to the present invention is characterized in that it comprises an extension process for extending one of a longitudinal direction and a width direction of the film, and an optical compensation film for shrinking the other direction. A long-length optical compensation film satisfying the above formulas (1) to (4), which is a combination of a polarizer and a roll-to-roller.

The polarizing plate of the present invention is characterized in that it is produced by an optical compensation film containing an extension process for extending one of the longitudinal direction and the width direction of the film and a shrinking process for shrinking the other direction. The long-length optical film satisfying the above formulas (1) to (4) is produced by a method of manufacturing a polarizing plate in which a polarizing mirror and a roll-to-roller are bonded together.

The liquid crystal display device of the present invention is characterized in that it has an optical compensation film having a shrinking process including a process of extending one of a longitudinal direction and a width direction of a film and shrinking a direction of the other direction. The polarizing plate and the liquid crystal cell manufactured by the method for manufacturing a polarizing plate of a long-length optical compensation film of the formula (1) to (4) which are bonded together by a polarizing mirror and a roll-to-roller are satisfied. A polarizing plate of an optically anisotropic layer of the formula (7-1) and the formula (7-2).

-10<Re(550)<10.........Formula (7-1) 100<|Rth(550)|<300.........Formula (7-2)

[Best form for implementing the invention]

In the following, the present invention will be described in detail. Further, in the present specification, the numerical range indicated by "~" is used, and the numerical values described before and after "~" refer to the range including the lower limit value and the upper limit value.

Moreover, in the present specification, "45°", "parallel" or "vertical" means within a range of ±5° from a strict angle. The error with the tight angle is preferably less than 4°, preferably less than 3°. In addition, the angle "+" refers to the clockwise direction and the "-" refers to the counterclockwise direction. In addition, the "late phase axis" means the direction in which the refractive index is the largest. Moreover, the "visible range" means 380 to 780 nm. Further, when the measurement wavelength of the refractive index is not particularly limited, the value of λ = 550 nm in the visible light range.

In addition, in the present specification, the "polarizing plate" is not particularly limited, and includes a long polarizing plate and a size that is cut into a liquid crystal device. (In the present specification, "cutting" includes "perforation" and "cutting". There are two types of polarizers such as polarizers. Further, in the present specification, the term "polarizing film" and "polarizing plate" are used, and "polarizing plate" means a laminated body having a transparent protective film for protecting the polarizing film on at least one side of the "polarizing film".

In the present specification, Re(λ) and Rth(λ) each represent a retardation value in the in-plane of the wavelength λ and a retardation value in the thickness direction. Re(λ) is measured by KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.), and light having a wavelength of λ nm is incident on the normal direction of the film.

When the measured film is represented by a refractive index ellipsoid of one axis or two axes, Rth(λ) is obtained by the following method.

Rth(λ) is the in-plane slow phase axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis) (when there is no slow phase axis, any direction in the film plane is used as the rotary axis) In the line direction, light having a wavelength of λ nm is incident from each oblique direction at a 10 degree stage from the normal direction of 50 degrees on one side, and all points are measured at 6 points, and the measured retardation value and the average refractive index are assumed. The value and the input film thickness value are used as a reference, and the above Re (λ) is calculated by KOBRA 21ADH or WR.

In the above, the retardation value of the tilt angle larger than the tilt angle when the film has a retardation axis in the in-plane direction as the rotation axis from the normal direction, and has a retardation value of zero at a certain tilt angle. After changing its sign to a negative value, it is determined by KOBRA 21ADH.

Further, the retardation axis is used as the tilt axis (rotary axis) (when there is no slow phase axis, the arbitrary direction in the film plane is used as the rotary axis), and the retardation value is measured from the two directions of arbitrary inclination, and the measured retardation is measured. The value, the assumed value of the average refractive index, and the input film thickness value are used as a reference, and Rth can be obtained by the following formulas (I) and (II).

However, the above Re(θ) represents a retardation value in a direction in which the angle θ is inclined from the normal direction.

Further, nx of the formula (I) indicates the refractive index in the direction of the slow axis in the plane, ny indicates the refractive index in the in-plane and nx perpendicular directions, and nz indicates the refractive index in the vertical direction from nx and ny.

Rth=((nx+ny)/2-nz)×d.........Formula (II)

The film to be measured is one which cannot be represented by a refractive index ellipsoid of one axis or two axes, that is, a film having no optical axis (Optic axis), and Rth(λ) is obtained by the following method.

Rth(λ) is the in-plane retardation axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis), from -50 degrees to +50 degrees for the film normal direction, at 10 degrees At the stage, the light of the wavelength λ nm is incident from the oblique direction, and all the points are measured at 11 points. The measured retardation value, the assumed value of the average refractive index, and the input film thickness value are used as the reference, and the above is determined by KOBRA 21ADH or WR. Re(λ).

In the above measurement, the assumed value of the average refractive index can be used in the catalogue of the polymer handbook (JOHN WILEY & SONS, INC) and various optical compensation films.

Further, the value of the average refractive index is not known, and can be measured by an Abbe refractometer. The values of the average refractive index of the main optical compensation film are as follows: cellulose phthalate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), poly Styrene (1.59). By inputting the assumed value of the average refractive index and the film thickness, KOBRA 21ADH or WR is obtained by taking nx, ny, and nz. From the obtained nx, ny, and nz, Nz = (nx - nz) / (nx - ny) can be obtained.

(optical compensation film)

The optical compensation film of the present invention is characterized in that the incident light is in a normal direction, a direction oblique thereto, for example, a polar angle of 60 degrees, and a wavelength having a retardation value on a cellulose phthalate film is dispersed differently. Optical properties, actively using this material for optical compensation.

(Optical properties of optical compensation film)

The optical compensation film of the present invention has an optical characteristic satisfying the following formulas (1) to (4) when the color shift is improved by the viewing angle of the liquid crystal display device.

50≦Re(550)≦200‧‧‧‧‧‧‧‧(1)

0.4≦Rth(550)/Re(550)≦0.6‧‧‧‧数(2)

0.1<Re(450)/Re(550)<0.95‧‧‧‧3 (3)

1.03<Re(650)/Re(550)<1.93‧‧‧‧数(4)

Further, in the above formulas (1) to (4), Re (450), Re (550), and Re (650) are in-plane resistances measured by light having wavelengths of 450 nm, 550 nm, and 650 nm. The hysteresis value (unit: nm), Rth (450), Rth (550), and Rth (650) are retardation values (unit: nm) in the thickness direction measured by light having wavelengths of 450 nm, 550 nm, and 650 nm.

Further, Re (550) of the above formula (1) is preferable to satisfy 80 ≦ Re (550) ≦ 180, and it is more preferable to satisfy 100 ≦ Re (550) ≦ 150.

Further, Rth(550)/Re(550) of the above formula (2) satisfies 0.43≦Rth(550)/Re(550)≦0.57, preferably to satisfy 0.45≦Rth(550)/Re(550)≦ 0.55 is better.

Moreover, Re(450)/Re(550) of the above formula (3) is preferably satisfying 0.3<Re(450)/Re(550)<0.9 to satisfy 0.5<Re(450)/Re(550). <0.85 is better.

Further, Re(650)/Re(550) of the above formula (4) is preferably satisfying 1.08<Re(650)/Re(550)<1.80 to satisfy 1.11<Re(650)/Re(550). <1.70 is better.

Further, when used in a liquid crystal display device, it is preferable to arrange the optical compensation film for the transmission axis of the polarizer in parallel with the slow phase axis.

Further, it is preferred to use an optically anisotropic layer which satisfies the following formula (7-1) and formula (7-2) in combination.

-10<Re(550)<10. . . . . . . . . Equation (7-1)

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

Here, when the liquid crystal cell is of the VA type (for a VA liquid crystal display device), it is preferable to satisfy the following formula (7-3) and formula (7-4) to satisfy the following formula ( 7-5) and the formula (7-6) are better.

-8<Re(550)<8. . . . . . . . . Equation (7-3)

140<|Rth(550)|<240.........the formula (7-4) -5<Re(550)<5.........the equation (7-5) 160<|Rth(550)|<200... ...the number (7-6)

<Polymer having a water content of 1.0% or less> In the optical compensation film of the present invention, a polymer having a water content of 1.0% or less is preferably used. When the liquid crystal display device is used in a wide variety of environments, it is necessary to reduce the influence of temperature and humidity (especially humidity).

A polymer suitable for use in the optical compensation film of the present invention, such as a polycarbonate copolymer or a polymer resin having a cyclic olefin structure.

Examples of the polycarbonate copolymer are a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), and the repeating unit represented by the above formula (1) occupies the entire 80 to 30 mole % of the polycarbonate copolymer.

In the above formula (1), each of R ₁ to R ₈ is independently a hydrocarbon group selected from a hydrogen atom, a halogen atom, and a carbon number of 1 to 6. The hydrocarbon group having 1 to 6 carbon atoms, for example, an alkyl group such as a methyl group, an ethyl group, an isopropyl group or a cyclohexyl group, or an aryl group such as a phenyl group. Among them, a hydrogen atom or a methyl group is preferred.

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

In the above formula (2), each of R ₁₁ to R ₁₈ is independently selected from a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 22 carbon atoms. The hydrocarbon group having 1 to 22 carbon atoms, for example, an alkyl group having 1 to 9 carbon atoms such as a methyl group, an ethyl group, an isopropyl group or a cyclohexyl group, or an aryl group such as a phenyl group, a biphenyl group or a terphenyl group. Among them, a hydrogen atom or a methyl group is preferred.

In the above formula (2), Y is a group of the following formula: R ₁₉ to R ₂₁ , R ₂₃ and R ₂₄ are each independently a hydrogen atom, a halogen atom or at least one hydrocarbon group selected from carbon atoms 1 to 22. Base. The hydrocarbon group is the same as the above. Further, each of R ₂₂ and R ₂₅ is independently a hydrocarbon group selected from carbon atoms 1 to 20, and the hydrocarbon group is, for example, a methylene group, an ethyl group, a propyl group, a butyl group, a cyclohexylene group, a phenylene group, or a sub Naphthyl, triphenylene. Ar ₁ to Ar _{3 are,} for example, an aryl group having 6 to 10 carbon atoms such as a phenyl group or a naphthyl group.

[Polycarbonate Copolymer] The above-mentioned polycarbonate copolymer has a repeating unit of 30 to 60 mol% as shown by the following formula (4) and a repeating unit of 70 to 40 as shown by the following formula (5). The polycarbonate copolymer formed by the ear % is preferably 45 to 55 mol% in the repeating unit represented by the following formula (4) and 55 to 45 mol% in the repeating unit represented by the following formula (5). The resulting polycarbonate copolymer is more preferred.

In the above formula (4), each of R ₂₆ to R ₂₇ is an independently hydrogen atom or a methyl group, and a methyl group is preferable in terms of handleability.

In the above formula (5), each of R ₂₈ to R ₂₉ is an independent hydrogen atom or a methyl group, and a hydrogen atom is preferred in terms of economy and film properties.

The optical compensation film of the present invention is preferably a polycarbonate copolymer having the above-described fluorene structure. A polycarbonate copolymer having the oxime structure, for example, a mixture of polycarbonate copolymers having a different composition ratio of a repeating unit represented by the above formula (1) and a repeating unit represented by the above formula (2) The content of the above formula (1) is preferably from 30 to 80 mol% of the total of the polycarbonate copolymer, more preferably from 35 to 75 mol%, and most preferably from 40 to 70 mol%.

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

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

The above polycarbonate copolymer can be obtained by a conventional method. As the polycarbonate, a method of polycondensing a dihydroxy compound with a phosphine, a melt polycondensation method, or the like can be used.

The intrinsic viscosity of the above polycarbonate copolymer is preferably from 0.3 to 2.0 dL/g. When it is less than 0.3, there is a problem that it becomes brittle and cannot maintain mechanical strength. When it is more than 2.0, since the melt viscosity becomes too high, problems such as connection with a mold may occur in the solution film formation, or it may be difficult to be obtained when the polymerization is completed. Refined problem.

Further, the optical compensation film of the present invention may be a composition (mixture) of the above polycarbonate copolymer and other polymer compound. In this case, since the polymer compound must have optical transparency, it is preferable to be compatible with the polycarbonate copolymer or the refractive index of each polymer.

Specific examples of the other polymer, such as poly(styrene-co-maleic anhydride), the composition ratio of the polycarbonate copolymer to the polymer compound, and the polycarbonate copolymer 30 to 80% by mass, the polymer compound body 20 The content of ~70% by mass is 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 mixture, a repeating unit of two or more kinds of the above copolymers may be combined.

Further, in the case of a mixture, a compatible mixture is preferred, but even if it is not completely compatible, as long as the refractive indices between the components coincide, the light scattering between the components can be suppressed, and the transparency can be improved. Further, the mixture may be combined with three or more kinds of materials, or may be combined with several kinds of polycarbonate copolymers and other polymer compounds.

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

[Polymer having a cyclic olefin structure] An example of a polymer resin having a cyclic olefin structure (hereinafter also referred to as "cyclic polyolefin resin" or "cyclic polyolefin"), and (1) raw spinylene a polymer, (2) a monocyclic cyclic olefin polymer, (3) a cyclic conjugated diene polymer, (4) a vinyl alicyclic hydrocarbon polymer, and the above (1) to (4) a hydride or the like.

The preferred polymer of the present invention is an addition (co)polymer cyclic polyolefin containing at least one or more repeating units represented by the following formula (II), and further contains at least 1 as needed. An addition (co)polymer cyclic polyolefin formed by the above repeating unit represented by the formula (I).

Further, an addition (co)polymer (including a ring-opening (co)polymer) containing at least one cyclic repeating unit represented by the formula (III) can also be used.

Further, in at least one repeating unit represented by the formula (III), an addition (co)polymer ring formed by at least one or more repeating units represented by the formula (I) may be further contained as required. Polyolefin is preferred.

In the above formulae (II) to (III), m represents an integer of 0 to 4. R ¹ to R ⁶ 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 represent a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, and a halogen atom. a hydrocarbon group having 1 to 10 carbon atoms, -(CH ₂ )nCOOR ¹¹ , (CH ₂ )nOCOR ¹² , -(CH ₂ )nNCO, -(CH ₂ )nNO ₂ , -(CH ₂ )nCN, -(CH ₂ nCONR ¹³ R ¹⁴ , -(CH ₂ )nNR ¹³ R ¹⁴ , -(CH ₂ )nOZ, -(CH ₂ )nW, or X ¹ and Y ¹ , X ² and Y ² , or X ³ and Y ³ The composition is -(CO) ₂ O, (CO) ₂ NR ¹⁵ .

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

By introducing a functional group having a large polarity in the substituents of X ¹ to X ³ and Y ¹ to Y ³ , the thickness-direction retardation value (Rth) of the optical compensation film can be increased, and the in-plane retardation can be obtained. The performance is getting bigger. The Re-expressing optical compensation film can be made larger by extending in the film forming process.

The original spinel-based addition (co)polymer is disclosed, for example, in Japanese Laid-Open Patent Publication No. Hei 10-7732, No. 2002-504184, No. 2004229157A1, or WO2004/070463A1. It is obtained by subjecting a raw spinylene-based polycyclic unsaturated compound to addition polymerization.

In addition, depending on the desired, the original spinel-based polycyclic unsaturated compound, and the conjugated diene of ethylene, propylene, butylene, butadiene, and isopentene; A conjugated diene; an addition polymerization of a linear diene compound of acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride, acrylate, methacrylate, maleimide, vinyl acetate, vinyl chloride, or the like .

The raw spinel-based addition (co)polymer has the trade name of Aberu (trans) which is sold by Mitsui Chemicals Co., Ltd., and has different glass transition temperatures (Tg), such as APL8008T (Tg 70 ° C), APL6013T. (Tg 125 ° C), or APL6015T (Tg 145 ° C) and other grades. In addition, there are pellets of TOPAS8007, 6013, and 6015, which are sold by polyplastics. In addition, Appear3000 is available from Ferrania.

The ruthenium-based polymer hydride, such as JP-A No. 1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19801, JP-A-2003-159767, or JP-A-2004-309979 discloses a process in which a polycyclic unsaturated compound is subjected to addition polymerization or substitution of ring-opening polymerization to carry out hydrogenation.

In the raw spinel-based 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 or -COOCH ₃ , and other groups. Can be chosen as appropriate.

The raw spinnene resin is sold by JSR (share) under the trade name of Arton G or Yatton F, or by Zeonor ZF14 and ZF16 from Japan. This product can be used in the sale of the Zeonex 250 or the AUNIgus 280.

[Resin having a positive characteristic birefringence and a resin having a negative birefringence] In addition, in terms of optical characteristics (satisfying the above formulas (3) to (4)), it has a positive characteristic double It is preferred that the refractive polymer is mixed with a polymer having a negative characteristic birefringence or laminated. For example, JP-A-2004-309979, JP-A-2005-126576, JP-A-2003-292639, JP-A-2006-058540, and JP-A-2004-325971 are not limited thereto.

<Method for Producing Optically Compensating Film> As a result of further intensive studies by the inventors of the present invention, it has been found that a cellulose having the above-mentioned preferred optical properties is obtained by a method comprising a stretching process for stretching a film and a shrinking process for shrinking. Phthalate film.

Here, the contraction process at the beginning means that when the size of the film begins to decrease substantially, the film size is reduced by, for example, applying a physical external force to the film, or applying a physical force to the film, such as during heat shrinkage. By. When the shrinkage process is completed, it means that the size of the film is substantially reduced.

Similarly, at the beginning of the extension process, when the size of the film begins to increase substantially, the increase in size of the film is performed by, for example, applying a physical extension treatment by applying a force to the film. When the extension project is completed, it means stopping the application of force to the film so that the extension process is physically completed.

In the present invention, in particular, it includes a stretching process for extending in the conveying direction of the film, a shrinking process for fixing and shrinking the film in the width direction of the film, or an extension process for extending in the width direction of the film. It is preferred to produce a shrinkage process that shrinks toward the direction in which the film is conveyed.

First, a method of performing a shrinkage process in which a film is extended in a conveyance direction of a film and a film is fixed and contracted in the width direction of the film is described.

In this case, when the film is extended in the direction in which the film is conveyed, the method of extending in the direction in which the film is conveyed is a method in which a plurality of rolls are provided with a circumferential speed difference, and a circumferential speed difference is used therebetween to extend in the longitudinal direction. Preferably. In addition, when the film is formed by the solution casting method, it is cast on a stainless steel belt or a barrel, and when the semi-dry state film is peeled off, the speed of the film conveying roller is adjusted, so that the film winding speed is higher. A faster film stripping process is preferred.

The width direction of the film is fixed and conveyed by a device called a tenter which fixes both ends of the film by clips or clips. By gradually narrowing the width of the tenter, the film can be made thin. Shrinks approximately perpendicular to the direction of extension.

Extension engineering and shrinkage engineering can be extended one by one. Shrink, or shrink. Any sequence of extensions is performed sequentially.

In addition, the tenter that operates in the two-axis direction of the transport direction and the width direction of the film can be fixed by a chain type, a screw type, a rack type, a linear motor type or the like, and the intervals of the clips are gradually moved toward the conveyance direction. The width is widened so that the film is stretched, and the width of the tenter is gradually narrowed to contract in the vertical direction.

In addition, in the method of forming an extension process extending in the width direction of the film and shrinking the film in the direction in which the film is conveyed, the film is conveyed toward the film by a chain type, a spiral type, a frame type, a linear motor type or the like. The tenter that operates in the two-axis direction of the direction and the width direction is fixed, and extends in the width direction of the film and gradually narrows the interval of the clip toward the conveying direction to contract the film.

As described above, at least part of the extension work can be performed simultaneously with the shrinking process by using a tenter that operates in the two-axis direction of the conveying direction and the width direction of the film. As a result of the research by the inventors, it can be seen that the simultaneous processing is performed by adjusting the extension. Shrinkage time, magnification, speed, can easily reduce the extension of the film surface called the bow. The advantage of shrinkage unevenness.

In addition, a stretching device which is formed by extending the film in the longitudinal direction or the width direction of the film and shrinking the other film while increasing the film thickness of the film, and using a FITZ machine manufactured by Shikasei Co., Ltd., etc. Preferably. This device is described in Japanese Laid-Open Patent Publication No. 2001-38802.

Here, as a result of the intensive study of the elongation rate of the elongation engineering and the shrinkage rate of the shrinkage engineering, the inventors have found that Re is in the desired range (for example, 50 to 200 nm) and satisfies the relationship of the above formula (2). It is extremely effective when the relationship between the elongation ratio X% of the elongation project and the shrinkage ratio Y% of the shrinkage engineering satisfies the following formula (Z).

In the relationship between the elongation and the shrinkage ratio, when the lower limit of the formula (Z) is lowered, in order to satisfy the relationship between the desired Re and the formula (2), it is necessary to use a special additive or a mixture of different kinds of polymers. Corresponding to the technology, these may cause other problems such as bleed out of the additive or increased manufacturing cost. Further, in the relationship between the elongation and the shrinkage ratio, when the upper limit of the formula (Z) is increased, the elongation and wrinkles are formed on the film after the shrinkage process, and it is not possible to use it as an optical compensation film.

Further, the elongation of the present invention means the elongation ratio of the length of the film after stretching in the direction of the film before stretching, and the shrinkage ratio refers to the shrinkage of the film after shrinkage in the shrinkage direction before the film length before shrinking. The ratio of length.

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

Further, in order to achieve the desired optical properties, it is preferred to carry out the stretching and shrinking process at a glass transition temperature of the film at the time of processing (5 to 50) °C.

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

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

10≧|Rth(550)10%RH-Rth(550)60%RH|. . . Equation (A)

Here, the above formula (A) indicates the difference between the value measured by the thickness direction retardation value Rth(λ) at 25 ° C and 60% RH and the value measured at 25 ° C and 10% RH, and the absolute value is 10 nm. The following is preferred.

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

Further, the glass transfer temperature of the present invention is measured by using a 5 mm × 30 mm film sample (not stretched) using a dynamic viscoelasticity measuring device (Bei Bulong: DVA-225, Eddie) The control (strand) system is measured by grasping a distance of 20 mm, a temperature increase rate of 2 ° C / min, a measurement temperature range of 30 to 200 ° C, and a number of cycles of 1 Hz. For the vertical axis, the logarithmic axis is the storage elastic modulus and the horizontal axis. When the linear axis is temperature (° C.), when the storage modulus is shifted from the solid range to the glass transition temperature, the observed storage elastic modulus rapidly decreases as the glass transition temperature Tg.

Specifically, on the obtained graph, the straight line 1 is drawn in the solid range, and when the straight line 2 is drawn in the glass rotating range, the intersection of the straight line 1 and the straight line 2 is such that the storage elastic modulus is rapidly reduced at the time of temperature rise, and the film starts to soften. The temperature, the temperature at which the glass transition range starts to travel, is taken as the glass transition temperature Tg (dynamic viscoelasticity).

Further, the temperature of the horizontal axis described above is the temperature of the surface of the film measured by a non-contact infrared thermometer.

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

Further, the film formed by the melt extrusion method or the film formed film may be continuously subjected to elongation treatment after drying, and once stretched, an extension treatment may be additionally performed.

Further, it is also possible to use an extension of a film which is substantially formed by a solvent-free melting method.

The extension or contraction of the film can be carried out in one piece or in multiple stages. When it is carried out in a multi-stage manner, the product of each stretching ratio may be within the above preferred range.

The stretching speed is preferably 5 to 1,000%/min, more preferably 10 to 500%/min. The stretching is preferably carried out by a heating roller or/and a radiant heat source (IR heater or the like) and warm air.

Further, in order to satisfy the relationship 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.........Formula (5) -20≦Rthb(550)≦20.........Formula (6) (in the above equations (5)~(6), Reb( 550) The in-plane retardation value (unit: nm) of the optical compensation film before stretching measured by light having a wavelength of 550 nm, and Rthb (550) is the thickness direction retardation of the optical compensation film before extension measured by light of 550 nm. Value (unit: nm)).

In order to realize the optical characteristics of the above formulas (5) to (6), a preheating process for preheating the film before the extension process is preferred. The use temperature in the preheating process is preferably a glass transition temperature + (25 to 100) °C. The heat treatment temperature is preferably from 1 second to 3 minutes.

Moreover, heat treatment can also be performed after the extension process. The heat treatment temperature is preferably carried out at a temperature lower by 20 ° C to 10 ° C higher than the glass transition temperature of the cellulose acetate film, and the heat treatment time is preferably from 1 second to 3 minutes.

Alternatively, the heating method may be district heating or partial heating using an infrared heater. It is also possible to nick the ends of the film during or at the end of the project. It is preferred to recycle such cutting chips as a raw material.

In the case of the tenter, the method of appropriately controlling the drying gas blowing, the angle of blowing, the wind speed distribution, the wind speed, and the like, when the width of the tenter is maintained and the web is dried is disclosed in Japanese Laid-Open Patent Publication No. Hei 11-077718, The air volume, the temperature difference, the air volume difference, the air volume ratio of the upper and lower air blows, and the use of a high specific heat drying gas can ensure the speed of the solution casting method and prevent the flatness and the like from deteriorating when the width of the fiber web is widened. technology.

In order to prevent the occurrence of speckle, the heat-treated resin film which has been stretched is subjected to heat treatment in which the temperature is distributed in the width direction of the film after the elongation process and the heat relaxation process.

In addition, in order to prevent the occurrence of a speckle, the invention discloses a method in which the solvent content of the film is extended by 2 to 10% based on the solid content, as described in JP-A-4-204503.

Further, when the nip length of the clip is specified to control the curling state, it is described in Japanese Laid-Open Patent Publication No. 2002-248680, by the width of the tenter holder D ≦ (33 / (log elongation × log volatile component)) The invention is carried out to extend the film to suppress the curling condition and to easily convey the film after the elongation process.

In the case of the high-speed film transfer and the extension, the invention is described in Japanese Laid-Open Patent Publication No. 2002-337224.

Further, JP-A-2002-187960 discloses that a cellulose ester slurry liquid is cast on a casting carrier for the purpose of simply improving the viewing angle characteristics and improving the viewing angle, and then, by self-casting The optical fiber (film) exfoliated by the carrier has an amount of residual solvent in the fiber web of 100% by mass or less, particularly in the range of 10 to 100% by mass, extending at least 1.0 to 4.0 times in one direction, and having an optical two-axis. The invention of sex. In the preferred embodiment, the amount of the residual solvent in the fiber web is 100% by mass or less, and particularly preferably in the range of 10 to 100% by mass, the stretching is performed at least 1.0 to 4.0 times in one direction.

In addition, in order to produce a retardation film in which the amount of diffusion of the additive is small, the peeling phenomenon between the layers is small, and the smoothness is good and the transparency is excellent, the resin containing the resin and the additive and the organic solvent is prepared as described in JP-A-2003-014933. Material A, and a slurry B containing an additive or an additive having a lower content than the slurry A and an additive and an organic solvent, the slurry A is a core layer, and the slurry B is a surface layer and is carried out on a carrier. Co-casting treatment, after evaporating the organic solvent until peeling off, the fiber web is peeled off from the carrier, and the residual solvent in the resin film at the time of stretching is in the range of 3 to 50% by mass, and extends at least in the 1-axis direction. ~1.3 times the invention.

Further, a preferred embodiment is described in which the fiber web is peeled off from the carrier, and then the stretching temperature is in the range of 140 to 200 ° C and extends at least 1.1 to 3.0 times in the axial direction to prepare a slurry A containing a resin and an organic solvent. And the slurry B containing the resin, the fine particles and the organic solvent, the slurry A as the core layer, the slurry B as the surface layer, and the co-casting treatment on the carrier until the organic solvent is evaporated until the peelable The net is peeled off from the carrier, and in the range of 3 to 50% by mass of the residual solvent in the resin film at the time of stretching, the invention is extended at least 1.1 to 3.0 times in the direction of the first axis, and then the extension temperature is 140 to 200 ° C. Extending from 1.1 to 3.0 times in at least one axial direction in the range, preparing a slurry A containing a resin and an organic solvent and an additive, and a resin containing a resin or an additive containing no additive or additive and having a lower content than the slurry A, and an organic solvent slurry The material B and the slurry C containing the resin and the fine particles and the organic solvent are prepared on the carrier with the slurry A as the core layer, the slurry B as the surface layer, and the slurry C and the slurry B on the opposite side. Co-casting until peelable After evaporating the organic solvent, the fiber web is peeled off from the carrier, and the residual solvent in the resin film at the time of stretching is in the range of 3 to 50% by mass, and the invention is extended at least 1.1 to 3.0 times in the 1-axis direction, and then, The extension temperature is extended from 1.1 to 3.0 times in at least one axial direction in the range of 140 to 200 ° C, and the amount of the additive in the slurry A is 1 to 30% by mass to the resin, and the amount of the additive in the slurry B is to the resin. It is 0 to 5 mass%, and the additive is a plasticizer, or an ultraviolet absorber, or a retardation value adjuster. The organic solvent in the slurry A and the slurry B can be used in an amount of 50% by mass or more based on the total organic solvent. Methylene chloride, or methyl acetate.

In addition, in order to prevent foaming of the web which is dried by the tenter, and to improve the dissociation property and prevent dust generation, it is described in Japanese Laid-Open Patent Publication No. 2003-004374 that the hot air of the dryer is not attached in the drying apparatus. An invention in which the width of the dryer is formed shorter than the width of the fiber web at both edge portions of the fiber web.

Further, in order to prevent foaming of the web which is dried by the tenter, to improve the disengageability and to prevent dusting, it is described in Japanese Laid-Open Patent Publication No. 2003-019757 that the holder of the tenter is not attached. Under the dry wind, the invention is provided with a windshield on the inner side of both ends of the fiber web.

In addition, in order to carry out the conveyance and drying in a stable manner, it is described in Japanese Laid-Open Patent Publication No. 2003-053749, that the thickness of the both ends of the film carried by the retort tenter after drying is X μm, and the film product When the average thickness after drying is T μm, the relationship between X and T satisfies the formula (1) T ≦ 60, 40 ≦ X ≦ 200, and the formula (2) 60 < T ≦ 120, 40 + (T-60) ×0.2≦X≦300, or the relationship of the formula (3) 120<T, 52+(T-120)×0.2≦X≦400.

Further, in order to prevent wrinkles from occurring in the multi-stage tenter, it is described in Japanese Laid-Open Patent Publication No. Hei No. 2-182654, in which a heating chamber and a cooling chamber are provided in a dryer of a multi-stage tenter. The invention of cooling the left and right clip chains, respectively.

In addition, in order to prevent the fiber web from being broken, wrinkled, or conveyed, it is described in Japanese Laid-Open Patent Publication No. Hei 9-077315, the density of the inner back stitch is increased in the clicker of the tenter. The invention has the effect that the density of the back stitch becomes small.

In addition, in order to prevent the foaming of the fiber web itself in the tenter or the adhesion of the fiber web to the holding device, it is described in Japanese Laid-Open Patent Publication No. Hei 9-085846, in which the two of the fiber webs are made in the tenter drying device. The side edge portion keeps the crepe needle cooled in the blow-out type cooler, not at the foaming temperature of the fiber web, and the squeezing needle before the fiber web is clamped in the ventilating tube type cooler at a temperature of +15 ° C or less The invention of cooling is carried out.

In addition, in order to prevent detachment of the embossing needle tenter and to facilitate the foreign matter, it is described in Japanese Laid-Open Patent Publication No. 2003-103542 that the insertion structure is cooled and the insertion structure is placed in the crepe tenter. The invention relates to a method of forming a film by a solution at a surface temperature which is not higher than the gelation temperature of the fiber web.

In addition, the solution casting method is used to increase the speed and prevent the flatness of the fiber web from being widened by the tenter, and is described in Japanese Laid-Open Patent Publication No. Hei 11-077718. When the fiber web is dried, the wind speed is 0.5 to 20 (40) m/s, the lateral temperature distribution is 10% or less, the downwind ratio of the fiber web is 0.2 to 1, and the dry gas ratio is 30 to 250 J/Kmol. .

Further, it is disclosed that when drying in a tenter, preferred drying conditions are determined depending on the amount of residual solvent.

Specifically, it is described that after the fiber web is peeled off from the carrier, the amount of residual solvent in the fiber web is up to 4% by mass, and the angle blown from the air outlet is in the range of 30 to 150° on the film plane, and is located in the range of 30 to 150°. The wind speed distribution on the surface of the film in the direction in which the drying gas is blown out is based on the upper limit of the wind speed, and the difference between the upper limit value and the lower limit value is within 20% of the upper limit value, the dry gas is blown out, and the fiber is made When the amount of the residual solvent in the fiber web is 130% by mass or less and 70% by mass or more, the air velocity of the dry gas blown from the blow dryer on the surface of the fiber web is 0.5 m/sec or more and 20 m/sec. When the amount of the residual solvent is less than 70% by mass and 4% by mass or less, the drying gas is blown by the wind of the drying gas at a wind speed of 0.5 m/sec or more and 40 m/sec or less, and the width of the fiber web is in the width direction. When the temperature distribution of the dry gas is based on the upper limit of the gas temperature, the difference between the upper limit value and the lower limit value is within 10% of the upper limit value, and the residual solvent amount in the fiber web is 4% by mass or more and 200. When the mass is less than %, the fiber that is transported The air volume ratio q of the dry gas blown out from the air outlet of the blow-drying dryer on the mesh is 0.2 ≦q ≦1.

Moreover, with regard to the preferred embodiment, it is disclosed that at least one gas is used as the drying gas, and the average specific heat is 31.0 J/K ‧ mol or more and 250 J/K. When it is less than mol, the dry gas which is contained in the dry gas during drying and which has a saturated vapor pressure of 50% or less of the concentration of the organic compound which is liquid at normal temperature is dried.

In addition, in order to prevent deterioration of flatness or coating due to the generation of a contaminant, it is described in Japanese Laid-Open Patent Publication No. Hei 11-077719, a clip of a tenter in a manufacturing apparatus of TAC (triethylenesulfonyl cellulose). The invention of the built-in heating section.

In a better form, it is disclosed that the clip of the tenter is used to liberate the web, and then, before the web is loaded, a device for removing foreign matter generated by the contact portion between the clip and the web is provided, and the injected gas is used. Or the liquid and the brush to remove the foreign matter, and the residual amount when the clip or the reticle is in contact with the fiber web is 12% by mass or more and 50% by mass or less, and the surface temperature at the contact portion of the clip or the reticle and the fiber web is 60 ° C. The above is 200 ° C or lower (preferably 80 ° C or higher, 120 ° C or lower) or the like.

In order to improve the planarity, and to improve the quality of the tenter due to the cracking, and to improve the productivity, it is described in Japanese Laid-Open Patent Publication No. Hei 11-090943, in the tenter clip, the tenter is arbitrary. The transport length Lt (m) and the clip of the tenter of the same length as Lt are such that the ratio of the total length Ltt of the portion in the transport direction of the web Ltt (m) is Lr = Ltt / Lt, which is 1.0 ≦ Lr ≦ 1.99. A more preferred form reveals that the portion of the web is retained, with no gap configuration when viewed from the width of the web.

In the case of introducing a fiber web into a tenter, it is described in Japanese Laid-Open Patent Publication No. Hei 11-090944, which is incorporated herein by reference. The invention has a device for suppressing slack in the width direction of the web before the tenter inlet.

Further, a more preferable form discloses a slack suppressing device which has a suction device above the fiber web by a rotary drum which is rotated in a direction in which the width is widened by 2 to 60°. A blower that blows air under the fiber web.

In the method of the TAC, the fiber web peeled from the carrier has an angle with respect to the level, and the introduction is pulled, as described in Japanese Laid-Open Patent Publication No. H11-090945. The invention in the frame.

In addition, in order to produce a film of a stable physical property, it is described in JP-A-2000-289903, that when the solvent content of the peeled solvent is 50 to 12% by mass, stress is applied in the width direction of the fiber web, and the conveyance is carried out. In the apparatus, the width detecting means of the fiber web and the holding means of the fiber web, and the invention for calculating the width of the fiber web from the detection signal having two or more variable bending points and detecting the width of the fiber web to change the position of the bending point.

In addition, in order to improve the holding property and prevent the fiber web from being broken for a long period of time, and to obtain a film having excellent quality, it is described in JP-A-2003-033933, on the left and right sides of the inlet portion of the tenter, in the fiber web. At least a lower portion of the upper and lower edges of the left and right side edge portions is provided with a wire web for preventing the side edge portion of the fiber web from being curled, and the web facing surface of the wire guide is placed in contact with the web in the direction in which the web is conveyed. The resin portion is formed by a metal portion for contact with the fiber web.

Further, it is preferable that the resin portion for contacting the web facing the web of the lead plate is on the upstream side in the direction in which the web is conveyed, the metal portion for contacting the web is disposed on the downstream side, and the resin for contacting the web of the lead sheet The step (including the inclined portion) between the metal portions for contacting the fiber web and the fiber web is 500 μm or less, and the distance between the fiber web contacting resin portion and the fiber web contacting metal portion connecting the lead plates in the width direction is 2 ~150mm, the distance between the fiber web contacting resin portion of the connecting lead plate and the fiber web contacting the metal portion in the fiber web transport direction is 5 to 120 mm, and the resin portion of the fiber web contact of the lead plate is attached to the metal wire The substrate is provided by surface resin processing or resin coating, and the resin portion for contacting the web of the lead plate is made of a resin monomer, and the fibers of the lead plate disposed above and below the left and right edge portions of the fiber web are provided. The distance between the opposite faces of the net is 3~30mm, and the distance between the opposite faces of the upper and lower wire plates at the left and right edge portions of the fiber web is toward the width of the fiber web and toward the inner side. The width of 100mm is enlarged by a ratio of 2mm or more, and the upper and lower wire plates at the left and right edge portions of the fiber mesh are each 10 to 300 mm in length, and the upper and lower wire guide plates are disposed apart from each other along the conveying direction of the fiber web. The separation distance between the upper and lower wires is -200 to +200 mm, and the web facing surface of the upper wire plate is made only of resin or metal, and the resin portion for fiber mesh contact of the wire plate is made of Teflon (registered trademark). The metal portion for contact with the fiber web is made of stainless steel, and the surface of the fiber web facing the conductor of the lead plate or the resin portion for contacting the fiber web and/or the metal portion for contacting the fiber mesh are 3 μm or less. .

Further, it is preferable to provide a position for preventing the occurrence of curling on the side edge portion of the fiber web from the peeling side end portion of the carrier to the tenter introduction portion, and particularly preferably at the entrance portion of the tenter. .

Further, in order to prevent breakage or spots of the fiber web during drying in the tenter, Japanese Laid-Open Patent Publication No. Hei 11-048271 discloses that the solvent content of the fiber web after peeling is 50 to 12% by weight in width. In the extension device, the invention is carried out by stretching, drying, and applying a pressure of 0.2 to 10 KPa from both sides of the fiber web by a pressurizing device when the solvent content of the fiber web is 10% by weight or less.

A more preferable form is a method of applying tension or applying pressure from both sides of a fiber web (film) when the solvent content is 4% by mass or more. When a pressure is applied using a nip roll, the number of rolls is about The 1~8 group is preferred, and the temperature at the time of pressurization is preferably 100 to 200 °C.

Further, in order to obtain a high-quality thin TAC having a thickness of 20 to 85 μm, it is disclosed in Japanese Laid-Open Patent Publication No. 2002-036266, a preferred form is a fiber web on the front and rear of the tenter along its conveying direction. a preheating project in which the tension difference is 8 N/mm ² or less, which is used for preheating the fiber web after the stripping process, and after the preheating process, the tenter is used to extend the fiber web, and the fiber is stretched after the extension project. The mitigation of the net is carried out in a smaller amount than the extension of the extension project.

The temperature T ₁ of the preheating process and the extension process is (the glass transition temperature of the film Tg-60) ° C or more, and the temperature T ₂ of the relaxation process is (T ₁ -10) ° C or less, so that the fiber web of the extension engineering The ratio of the elongation to the width of the web before the extension is 0 to 30%, and the elongation of the fiber web of the mitigation project is -10 to 10%.

In addition, in order to reduce the thickness of the dried film to a thickness of 10 to 60 μm, and to reduce the light-weight and moisture permeability, and to have excellent durability, it is disclosed in JP-A-2002-225054, after the peeling and the residue in the fiber web. When the amount of the solvent is up to 10% by mass, both ends of the fiber web are fixed by a clip, the drying shrinkage is suppressed by the width retention, and/or the width direction is extended to form the following formula S={(Nx+Ny)/2}- The surface alignment degree (S) shown by Nz is a film of 0.0008 to 0.0020 (wherein, Nx is a refractive index in the direction of maximum refractive index in the plane of the film, and Ny is a refractive index in a direction perpendicular to the surface of Nx. The Nz is a refractive index in the thickness direction of the film, and the time from the casting to the peeling is 30 to 90 seconds, and the web after the peeling is extended in the width direction and/or the length direction.

In the case of suppressing optical spots, the mass concentration of the retardation control (rise) agent has a high optical distribution when it is near the center in the film width direction, and has a solution film for extension engineering. method.

Further, in order to obtain a film which does not cause turbidity, Japanese Laid-Open Patent Publication No. 2003-071863 discloses that the stretching ratio in the width direction is preferably from 0 to 100%, and when used as a protective film for a polarizing plate, 5 to 20 is used. % is better, with 8~15% best.

Moreover, when it is disclosed that the phase difference film is used, the stretching ratio in the width direction is preferably 10 to 40%, more preferably 20 to 30%, and the stretching ratio is controlled by the stretching ratio. The higher the stretching ratio, the film can be made. The planarity is more excellent, so it is preferable.

Further, it is disclosed that the amount of residual solvent of the film when the tenter is carried out is preferably 20 to 100% by mass at the start of the tenter, and the tenter is provided until the residual solvent amount of the film is 10% by mass or less. Drying is preferred, and it is more preferably 5% by mass or less.

In addition, it is disclosed that the drying temperature at the time of the tenter is preferably 30 to 150 ° C, more preferably 50 to 120 ° C, 70 to 100 ° C is optimal, and the drying temperature is lower, such as ultraviolet absorber or plasticizer. The less the evaporation situation, the less the engineering pollution, but the higher the drying temperature, the more excellent the planarity of the film.

Further, in the case of storing under high temperature and high humidity conditions, it is described in JP-A-2002-248639 that the cellulose ester solution is cast on a carrier and continuous. In the method for producing a film which is peeled off and dried, the invention is characterized in that the drying shrinkage ratio satisfies the amount of residual solvent (%) at the time of drying shrinkage (%) ≦ 0.1 × peeling of the following formula.

Further, a preferred embodiment is disclosed in which the residual solvent amount of the cellulose ester film after peeling is in the range of 40 to 100% by mass, and the both ends of the cellulose ester film are fixed by a tenter transfer and at least a residual solvent is obtained. When the amount is reduced by 30% by mass or more, the amount of residual solvent in the tenter transfer inlet of the cellulose ester film after peeling is 40 to 100% by mass, and the residual solvent amount at the outlet is 4 to 20% by mass, so that the fiber is conveyed by the tenter. The tension of the polyester film is increased from the tenter transfer inlet toward the outlet, and the tension of the cellulose ester film conveyed by the tenter is approximately the same as the tension in the width direction of the cellulose ester film.

Further, in order to obtain a film having a thin film thickness, an optical isotropic property, and a flatness, the residual solvent ratio X at the time of peeling and the amount of residual solvent when introduced into a tenter are disclosed in JP-A-2000-239403. Film formation was carried out in the range of 0.3X ≦ Y ≦ 0.9X.

JP-A-2002-286933 discloses a method of stretching a film formed by casting, for example, a method of stretching under heating conditions and a method of stretching under conditions containing a solvent; under heating conditions When stretching, it is preferred to extend at a temperature lower than or lower than the glass transition temperature of the resin, and the film which is subjected to the casting film can be stretched to a solvent, and the once dried film is brought into contact with the solvent again. The impregnation solvent is extended.

[Fused Film Formation] The method for producing the optical compensation film of the present invention may be a melt film formation. The raw materials such as the polymer, the additive, and the like may be heated and melted, and the material may be thinned by extrusion and injection molding, or the raw material may be sandwiched between two heated flat plates to be pressed and thinned.

The temperature at which the raw material polymer is melted uniformly at the same time is not particularly limited, and may be appropriately selected depending on the purpose, for example, heating at a temperature equal to or higher than the melting point or the softening point. In order to obtain a uniform film, the temperature is higher than the melting point of the raw material polymer, preferably 5 to 40 ° C higher than the melting point, and heated at a temperature higher than the melting point of 8 to 30 ° C. The melter is best.

<Optical Anisotropic Layer> A method in which Re is a minimum value and Rth is controlled, and a method of coating an optically anisotropic layer by a liquid crystal layer or the like is preferably used.

A specific example of the liquid crystal layer is a method in which the disk liquid crystal is aligned within an angle of 5 degrees between the disk surface and the surface of the optical compensation film (Japanese Laid-Open Patent Publication No. Hei 10-312166). A method in which the angle between the shaft and the optical compensation film surface is aligned within 5 degrees (JP-A-2000-304932).

The optically anisotropic layer can expand the viewing angle contrast between the liquid crystal display device and the liquid crystal display device of the OCB type or the VA type, and can reduce the color shift 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, or may be disposed between the polarizing plate on the back side and the liquid crystal cell, or may be disposed on both sides.

For example, it can be incorporated as an independent member in the liquid crystal display device, or can impart optical characteristics to the protective film that protects the polarizing film, and can function as a transparent film to be incorporated in the liquid crystal display device as a member of the polarizing plate.

[Ultraviolet absorber] The optical compensation film of the present invention is preferably a UV absorber.

The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the purpose. For example, a salicylate type, a benzophenone type, a benzotriazole type, a benzoate type, a cyanoacrylate type, or a nickel may be used. An absorbent such as a salt system is preferably a benzophenone type, a benzotriazole type or a salicylate.

a benzophenone-based ultraviolet absorber such as 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-octyloxy Benzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-(2-hydroxy-3-methylpropoxy)propoxybenzophenone, and the like.

a benzotriazole-based ultraviolet absorber such as 2(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2 (2'-hydroxyl group) -5'-tert-butylphenyl)benzotriazole, 2(2'-hydroxy-3',5'-di-3-pentylphenyl)benzotriazole, 2(2'- Hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2(2'-hydroxy-5'-3-octylphenyl)benzotriazole Wait.

The salicylate is, for example, phenyl salicylate, p-octylphenyl salicylate or p-tert-butylphenylsalicylate.

Among the ultraviolet absorbers exemplified herein, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-methoxybenzophenone, 2 ( 2'-Hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2(2'-hydroxy-5'--3-butylphenyl) Benzotriazole, 2(2'-hydroxy-3',5'-di-3-pentylphenyl)benzotriazole, 2(2'-hydroxy-3',5'-di-third More preferably, -butylphenyl)-5-chlorobenzotriazole.

The ultraviolet absorber can be used by combining a plurality of absorbents having different absorption wavelengths, and a high blocking effect can be obtained in a wide wavelength range, which is preferable.

The ultraviolet ray absorbing agent for liquid crystals is excellent in ultraviolet absorbing ability at a wavelength of 370 nm or less in order to prevent deterioration of liquid crystal, and it is preferable that absorption of visible light having a wavelength of 400 nm or more is small in liquid crystal display properties. In particular, the benzotriazole-based compound, the benzophenone-based compound, and the salicylate-based compound are preferably used as the ultraviolet absorber, and the benzotriazole-based compound is less likely to be colored. good.

In addition, the ultraviolet absorber can also be used in JP-A-60-235852, JP-A-3-199201, same as 5-1907073, same as 5-149789, the same as 5-271471, and the same as 6-107054. Same as No. 6-118233, No. 6-148430, No. 7-11056, No. 7-1105, No. 7-11056, No. 8-29619, No. 8-239509, and No. 2000-204173 The compound described in the publication.

The amount of the ultraviolet absorber to be added is preferably 0.001 to 5% by mass, more preferably 0.01 to 1% by mass, based on the polymer. When the amount is 0.001% by mass or more, a sufficient effect of addition can be exhibited. Therefore, when the amount is 5% by mass or less, the ultraviolet absorber can be prevented from diffusing on the surface of the film, which is preferable.

Further, the ultraviolet absorber may be added at the same time as the polymer is dissolved, or may be added to the dissolved slurry (when the solution is formed into a film). In particular, it is preferable to use a static mixer or the like to add a UV absorber solution to the slurry before casting, and to easily adjust the spectral absorption characteristics.

[Preventing the deterioration agent] In addition, in order to prevent deterioration or decomposition of the optical compensation film, it is preferable to use a deterioration preventing agent as appropriate.

A deterioration inhibitor such as a butylamine, a hindered amine compound, a ruthenium compound (Japanese Unexamined Patent Publication No. Hei No. Hei No. Hei No. Hei. A compound such as a benzophenone-based UV absorber (JP-A-6-118233).

[Dye] Further, in the present invention, a dye when the hue is adjusted may be added. The content of the dye is preferably from 10 to 1,000 ppm by mass in terms of the polymer, more preferably from 50 to 500 ppm. At this time, by containing the dye, the light piping of the optical compensation film can be reduced, and the yellowish condition can be improved. It is preferred that such compounds be added to the polymer solution or kneaded while the polymer is molten.

[Matting Agent Fine Particles] Among the preferred optical compensation films used in the present invention, it is preferred to use fine particles as a matting agent. The microparticles used in the present invention are, for example, ceria, titania, alumina, zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, water and calcium citrate, aluminum citrate, magnesium citrate and phosphoric acid. calcium. It is preferred that the microparticles have a reduced turbidity, especially those containing cerium oxide.

The cerium oxide microparticles are preferably one having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g/L or more. The smaller average diameter of the primary particles is 5 to 16 nm, which is preferable because the size of the film can be reduced. 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, the better the size and the agglomerates can be obtained because a high concentration dispersion can be produced.

When cerium oxide is used as the matting agent, the amount thereof is preferably 0.01 to 0.3 parts by mass per 100 parts by mass of the polymer component containing cellulose phthalate.

When such fine particles are usually formed into secondary particles having an average particle diameter of 0.1 to 3.0 μm, they are present as aggregates of primary particles in the film, and irregularities of 0.1 to 3.0 μm are formed on the surface of the film.

The average particle diameter of the secondary particles is preferably 0.2 μm or more and 1.5 μm or less, more preferably 0.4 μm or more and 1.2 μm or less, and most preferably 0.6 μm or more and 1.1 μm or less. When the average particle diameter is 1.5 μm or less, the haze does not become too strong, and when it is 0.2 μm or more, the effect of preventing turbidity can be sufficiently exhibited.

The primary and secondary particle diameters of the microparticles were observed by a scanning electron microscope to have a circle diameter circumscribing the particles as a particle diameter. Further, 200 particles were observed at the changing place, and the average value was used as the average particle diameter.

For the particles of cerium oxide, for example, "Yayarojiru" R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above is Yajeroji, Japan) Commercial products such as the system). The zirconia fine particles are commercially available, for example, "Yayarojiru" R976 and R811 (above, manufactured by Yayarojiru, Japan).

Among them, "Yerojiro 200V" and "Yerojilu R972V" are fine particles of cerium oxide having an average particle diameter of 20 nm or less and an apparent specific gravity of 70 g/L or more. It is more preferable because the turbidity of the optical compensation film can be kept low and the effect of lowering the friction coefficient is large.

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

For example, a fine particle dispersion in which a solvent and fine particles are stirred and mixed is prepared in advance, and the fine particle dispersion is added to a small amount of a polymer solution to be used, stirred and dissolved, and then mixed with a main polymer slurry.

This method is a preferred preparation method in view of the excellent dispersibility of the cerium oxide microparticles and the difficulty in re-coagulation of the cerium oxide microparticles.

In addition, a small amount of a polymer is added to the solvent, and after stirring and dissolving, fine particles are added thereto, and dispersed by a disperser, and the liquid is used as a fine particle addition liquid, and the fine particle addition liquid is used as an on-line mixer and slurry. A method of thorough mixing.

In the present invention, when the cerium oxide fine particles are mixed and dispersed with a solvent or the like, the concentration of cerium oxide is preferably 5 to 30% by mass, more preferably 10 to 25% by mass. The best is 15 to 20% by mass.

The higher the dispersion concentration, the better the liquid turbidity is added to the added amount, and the aggregate can be improved. The amount of the matting agent added to the final polymer slurry solution is preferably 0.01 to 1.0 g for 1 m ² , more preferably 0.03 to 0.3 g, and most preferably 0.08 to 0.16 g.

Among the solvents to be used, the lower alcohol is preferably, for example, methanol, ethanol, propanol, isopropanol or butanol. The solvent other than the lower alcohol is not particularly limited, and a solvent used for film formation of the cellulose ester is preferred.

<Water content> In addition, the preferred optical compensation film used in the present invention has an equilibrium water content of 1.0% or less at 25 ° C and 80% RH, and is preferable because the liquid crystal display device has little variation in color odor over time. .

For the measurement of the moisture content, the optical compensation film sample 7 mm × 35 mm is a moisture analyzer (CA-03, manufactured by Mitsubishi Chemical Corporation), a sample drying device (VA-05, manufactured by Mitsubishi Chemical Corporation), and Karl. - Fisher method measurement. The amount of moisture (g) is determined by dividing the mass of the sample (g).

<Elasticity> Elasticity After adjusting the optical compensation film sample 10 mm × 150 mm at 25 ° C and 60% RH for 2 hours or more, the tensile tester (Ston Rogoff (trans) R2, (share) Toyo Seiki) The production system was carried out at a distance of 100 mm between the grids, a temperature of 25 ° C, and an elongation speed of 10 mm/min.

The coefficient of hygroscopic expansion is determined by placing the film at a temperature of 25 ° C and 80% RH for 2 hours or more for a value of L _80% measured by a pin gauge, and placing it at 25 ° C, 10% RH. The film size of the film or more per hour is determined by the following formula (B) by the value L _10% measured by the needle gauge.

(L _{80% -} L _10% ) / (80% RH - 10% RH) × 10 ⁶ ......... Equation (B)

<Haze> Further, a preferred optical compensation film used in the present invention has a haze of preferably 0.01 to 2%.

In the present invention, the measurement value of the haze is such that the optical compensation film sample is 40 mm × 80 mm, and a haze meter (HGM-2DP, Shika (test) test machine) is used at 25 ° C and 60% RH. It is measured based on JIS K-6714.

<Dimensional change> Moreover, the preferred optical compensation film used in the present invention has a dimensional change of 24 hours at 60 ° C and 95% RH, and a dimensional change of 24 hours at 90 ° C and 5% RH. It is preferably in the range of 0 to 5%.

<Photoelastic coefficient> Further, the optical compensation film of the present invention has a photoelastic coefficient of 50 × 10 ^-13 cm ² /dyne or less, which is preferable in terms of uniformity when attached to a liquid crystal display device.

The specific measurement method is such that the optical compensation film sample 10 mm × 100 mm is subjected to tensile stress in the direction of the long axis, so that the retardation value at this time is made by the Jericho (transfer) tester (M150, Japan Spectrophotometer) The measurement determines the photoelastic coefficient from the amount of change in the retardation value for stress.

<Polarizing Plate> The present invention provides a polarizing plate comprising a polarizing film and a protective film which is one of the polarizing films, and at least one protective film (the visually recognizable side in the present invention) is cellulose. Polarized plate of phthalate.

For example, a polarizing film obtained by dyeing a polarizing film made of a polyvinyl alcohol film or the like with iodine and extending it so as to have a two-layer layer on a protective film can be used.

The polarizing plate is disposed on the outer side of the liquid crystal cell. It is preferable to dispose the liquid crystal cell by a polarizing film and a pair of polarizing plates formed by sandwiching one of the polarizing films on the protective film.

Further, the protective film disposed on the liquid crystal cell side is preferably the optical compensation film of the present invention.

<Binder> The adhesive of the polarizing film and the protective film is not particularly limited, and examples thereof include a PVA resin (including a modified PVA such as an acetamidine group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group), or boron. An aqueous solution of the compound or the like is preferred, and a PVA-based resin is preferred. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and more preferably 0.05 to 5 μm.

<Consistent Manufacturing Process of Polarizing Film and Protective Film> The polarizing plate which can be used in the present invention is obtained by drying a film having a film for polarizing film and reducing the rate of shrinkage of the volatile component, and drying or drying. After the protective film is attached to at least one side, the post-heating process is preferred.

The specific attachment method is to use a binder to adhere the protective film to the polarizing film while keeping the both ends in a drying process of the film, and then to align the both ends, or to dry the polarizing film from the both ends of the holding portion. After the film is used and the both ends of the film are cut, a protective film or the like is attached. The method of cutting can be a general technique such as a method of cutting with a blade or the like, or a method of using an electron.

After the bonding, in order to dry the adhesive and to improve the polarizing performance, it is preferred to perform heating. The heating conditions vary depending on the binder. When the water system is used, it is preferably 30 ° C or higher, more preferably 40 to 100 ° C, and most preferably 50 to 90 ° C. These projects are better in terms of performance and productivity when manufactured in a consistent online operation.

<Performance of Polarizing Plate> The optical performance and durability (short-term, long-term storage) of the polarizing plate of the present invention are obtained by a highly contrasting product (for example, HLC2- manufactured by Shanliz Co., Ltd.). 5618, etc.) The performance above the equivalent is better.

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 parallel transmittance, Tc is vertical transmittance), at 60 ° C In the environment where the humidity is 90% RH for 500 hours and at 80 ° C for 500 hours in a dry environment, the rate of change of the light transmittance before and after the absolute value is preferably 3% or less, and more preferably 1% or less. good. Further, the rate of change in the degree of polarization is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

<Surface Treatment> The optical compensation film of the present invention can be cured by a surface treatment to improve adhesion to a cellulose phthalate film or a polarizing layer which is protected by a polarizing plate.

For the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used.

The glow discharge treatment referred to herein can be subjected to low-temperature plasma treatment under a low-pressure gas of 10 ^-3 to 20 Torr, or plasma treatment at atmospheric pressure.

A plasma-exciting gas, in the above-mentioned conditions, refers to a gas excited by a plasma, such as argon, helium, neon, xenon, xenon, nitrogen, carbon dioxide, fluoride of tetrafluoromethane, and the like, and the like. .

These details are described in the Invention Association Public Technical Bulletin No. 2001-1745 (issued March 15, 2001, Association of Inventions) p.30-32.

Further, in recent years, attention has been paid to plasma treatment at atmospheric pressure, for example, irradiation energy of 20 to 500 kGy is used at 10 to 1,000 keV, and irradiation energy of 20 to 300 kGy is preferably used at 30 to 500 keV.

In addition, in the polarizing plate according to the present invention, at least one hard coating layer, anti-glare layer or anti-reflection layer is provided on the surface of the protective film on at least one side of the polarizing plate (the visually recognizable side surface in the present invention). good.

In other words, when the polarizing plate is used in a liquid crystal display device, it is preferable to provide a functional film such as an antireflection layer on the protective film disposed on the liquid crystal cell and the opposite side to provide at least one hard coating layer and an antiglare layer. Or the antireflection layer is preferred as the functional film.

Further, each layer does not need to be provided with an individual layer, for example, by having a function of anti-glare property on the anti-reflection layer or the hard coating layer, and functions as an anti-glare anti-reflection layer instead of providing the anti-reflection layer and the anti-glare layer. Second floor.

<Anti-Reflective Layer> The present invention is an antireflection layer formed by at least sequentially laminating a light-scattering layer and a low-refractive-index layer on a protective film of a polarizing plate, or a refractive index layer, a high refractive index layer, or a layer of a high-refractive-index layer sequentially laminated on a protective film. The antireflection layer of the low refractive index layer. Preferred examples of these are described below. Further, in general, the former has a specular reflectance of 1% or more and is called a Low Reflection (LR) film. The latter composition can achieve a specular reflectance of 0.5% or less, which is called an Anti Reflection (AR) film.

[LR film]

A preferred example of the antireflection layer (LR film) in which the light scattering layer and the low refractive index layer are provided on the protective film of the polarizing plate will be described.

In the light scattering layer, it is preferable to disperse the matting particles. Except for the matting particles of the light scattering layer, the refractive index of some raw materials is preferably 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. good.

In the present invention, the light-scattering layer has both anti-glare property and hard coating property, and may be one layer or several layers (for example, two to four layers).

The anti-reflection layer may have a surface irregular shape, the center line average thickness Ra is 0.08 to 0.40 μm, the average thickness Rz of 10 points is 10 times or less of Ra, and the average unevenness distance Sm is 1 to 100 μm, and the convex portion is convex from the deepest portion. The standard deviation of the height of the part is 0.5 μm or less, and the standard deviation of the average unevenness distance Sm based on the center line is 20 μm or less, and the surface having an inclination angle of 0 to 5° is designed to be 10% or more, and sufficient anti-glare property can be achieved. It is preferable to have a uniform matte feeling by visual observation.

In addition, the color of the reflected light under the C light source is a* value -2~2, b* value is -3~3, in the range of 380-780 nm, by making the minimum and maximum reflectance The ratio is 0.5 to 0.99, and since the color of the reflected light is neutral, it is preferable.

The b* value of the transmitted light under the C light source is preferably 0 to 3, which is preferable when the display device is applied to lower the yellow taste from the display.

In addition, 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, the polarizing plate of the present invention is used on the high-definition panel. It is better when the glare is reduced.

The antireflection layer which can be used in the present invention has a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60° gloss of 70% or less by optical characteristics, thereby suppressing reflection of external light and improving visibility. good. In particular, the specular reflectance is preferably 1% or less, and more preferably 0.5% or less.

Moreover, by a haze of 20 to 50%, an internal haze/total haze value ratio of 0.3 to 1, from a haze of the light scattering layer to a haze value of less than 15% after forming the low refractive index layer, The comb-shaped width is 0.5mm, the transparency of the transparent image is 20~50%, and the transmittance ratio of the vertical transmitted light/vertical 2° oblique direction is 1.5~5.0, which can prevent glare on the high-definition LCD panel and reduce the text. It is better to blur the phenomenon.

<Low Refractive Index Layer> The refractive index of the low refractive index layer which can be used in the present invention is preferably from 1.20 to 1.49, more preferably from 1.30 to 1.44. Further, the low refractive index layer satisfies the following formula (C), and is preferable in terms of low reflectance.

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

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

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

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

The polarizing plate of the present invention is disposed one on one side of the liquid crystal cell or two on both sides of the liquid crystal cell.

The liquid crystal cell is preferably a VA type, an OCB type, an IPS type, or a TN type.

<VA type> VA type liquid crystal cell system When the voltage is not applied, the rod-like liquid crystalline molecules are substantially vertically aligned.

In the VA type liquid crystal cell, (1) a VA type liquid crystal cell which is substantially perpendicular to the rod-like liquid crystal molecules without applying a voltage and which is substantially horizontally aligned when a voltage is applied (Special Kaiping 2-176625) (2) In order to expand the viewing angle, a liquid crystal cell of a VA type multi-domain phase (MVA type) is described (SID97, Digest of tech. Papers (1997) 845), (3) A liquid crystal cell of a type (n-ASM type) in which a rod-like liquid crystal molecule is substantially vertically aligned without applying a voltage and is twisted in a multi-domain phase when a voltage is applied (Notes 58-59 of the Japan Liquid Crystal Symposium) (1998) ()) and (4) SURVAIVAL type liquid crystal cell (published by LCD International 98).

In the case of a VA type liquid crystal display device, the optical compensation film of the present invention is preferably used for a visually identifiable side polarizing plate.

The <OCB type> OCB type liquid crystal cell is a curved alignment type liquid crystal cell in which the rod-like liquid crystal molecules are aligned substantially oppositely (symmetric) above and below the liquid crystal cell. A liquid crystal display device using a curved alignment type liquid crystal cell is disclosed in the specification of U.S. Patent No. 4,583,825 and U.S. Patent No. 5,410,422. In order to align the rod-like liquid crystalline molecules symmetrically above and below the liquid crystal cell, the curved alignment type liquid crystal cell has its own optical compensation function.

Therefore, this liquid crystal type is also called an OCB (Optically Compensatory Bend) liquid crystal type. The curved alignment type liquid crystal display device has the advantage of fast response speed.

<TN type> TN type liquid crystal cell, when the voltage is not applied, the rod-like liquid crystalline molecules are substantially horizontally aligned, and then twisted and aligned at 60 to 120°.

The TN type liquid crystal cell is widely used as a color TFT liquid crystal display device in most documents.

According to the present invention, it is possible to provide an optical compensation film which can accurately optically compensate a liquid crystal cell, and which has high contrast and improved color shift in relation to a viewing angle of a black display, a method for producing the same, and a polarizing plate.

Further, according to the present invention, it is possible to provide a liquid crystal display device which can prevent light leakage and which is excellent in contrast.

In the following, embodiments of the invention are described, but the invention is not limited by the following examples.

(Example 1)

A sodium hydroxide aqueous solution and ion-exchanged water are added to a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, and the monomer [A] represented by the following formula (6) and the following formula (7) are added thereto. The monomer [B] shown is dissolved in a ratio of 50:50 (mole %), and a small amount of bisulfite is added.

Next, dichloromethane was added thereto, and phosgene was blown at 20 ° C for about 60 minutes. Further, after p-tert-butylphenol was added and emulsified, triethylamine was added thereto, and the mixture was stirred at 30 ° C for 3 hours to complete the reaction.

After completion of the reaction, the organic phase was separated and the dichloromethane was evaporated to give a polycarbonate copolymer. The composition ratio of the obtained copolymer is about the same as the monomer addition amount ratio.

Further, the obtained polycarbonate copolymer had a water content of 0.3%.

Each of the copolymers and the cyanobiphenyl mixed liquid crystal produced by Meru Valley Co., Ltd. was dissolved in methylene chloride at a ratio of 96:4 (mass by mass) to prepare a slurry solution. . The film 101 was produced from the slurry solution by a casting method.

The film 101 obtained as described above is fed to a tenter having a structure in which a continuous long-length film is fixed by using a tenter holder in the longitudinal direction and narrowed in transport, and is fed to have a width direction. The extension device of the project (trade name "FITZ" manufactured by Shimizu Kogyo Co., Ltd.) set the film temperature to 170 ° C, and after 30 seconds passed through the heating zone, the elongation was started, and the film length was relaxed and contracted by 0.77 times. The web holder was extended by 1.70 times in the width direction to obtain an optical compensation film 111 having an extended film thickness of 60 μm.

<Optical Characteristics of Film> The wavelengths of 450, 550, and 650 nm of Re and Rth of the optical compensation film 111 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). The results are shown in Table 1.

As shown in Table 1, the values of Re and Rth at wavelengths of 450, 550, and 650 nm of the optical compensation film 111 produced by the method of the first embodiment were confirmed, and the relationship of any of the above formulas (1) to (4) was satisfied. .

Further, as a result of measuring Reb and Rthb of the film 101 before stretching, Reb was 4 nm and Rthb was 10 nm.

<Production of Polarizing Plate> <<Production of Vision-Recognizable Side Polarizing Plate>> Adsorption of iodine on an extended polyvinyl alcohol film to prepare a polarizing film, and adhesion of an optical compensation film on one side of the polarizing film 111.

In addition, a commercially available cellulose tridecanoate film (Fugitagi TD80UF, Fuji Photo Film Co., Ltd.) is saponified, and a polyvinyl alcohol-based adhesive is attached to the polarizing film. On one side, it was dried at 70 ° C for 10 minutes or more 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 are arranged in parallel. Further, the transmission axis of the polarizing film and the late phase axis of the commercially available cellulose triphthalate film are vertically disposed.

<Production of Backlight Side Polarizing Plate><<Production of Optical Compensation Film>> [Formation of Optical Anisotropic Layer] Commercially available cellulose triphthalate film (Z-TAC manufactured by Fuji Photo Photograph) was saponified On the commercially available cellulose triphthalate film, an alignment film coating liquid having the following composition was applied at 20 mL/m ² with a coil bar coater. Then, it was dried by a warm air of 60 ° C for 60 seconds, and then dried in a warm air of 100 ° C for 120 seconds to form a film.

Next, rubbing treatment is performed on the formed film in a direction parallel to the retardation axis direction of the film to form an alignment film.

Next, the optically anisotropic layer coating liquid having the following composition was applied to the above alignment film by a coil bar and Rth of 200 nm in the thickness direction after curing.

The object was attached to a metal frame and heated in a thermostat at 125 ° C for 3 minutes to align the discotic liquid crystalline compound.

Next, a disc-shaped liquid crystalline compound was crosslinked by using a 120 W/cm high pressure mercury lamp and UV irradiation for 30 seconds. An optically anisotropic layer was obtained by setting the temperature at the time of UV hardening to 80 °C.

The thickness of the optically anisotropic layer was 2.8 μm. Then, let cool to room temperature. The optical compensation film 120 is fabricated in this manner. When the optical characteristics of the optical compensation film 120 were measured, Re (550) = 1 (nm), Rth (550) = 200 (nm), and Rth (450) / Rth (550) = 1.09.

The iodine is adsorbed on the stretched polyvinyl alcohol film to prepare a polarizing film, and the optical compensation film 120 is attached to one surface of the polarizing film by using a binder.

Furthermore, a commercially available cellulose triphthalate film (Fugitagi TD80UF, manufactured by Fuji Photograph) was subjected to saponification treatment, and then attached to the other surface of the polarizing film by using a polyvinyl alcohol-based adhesive. The polarizing plate 300 was produced by drying at ° C for 10 minutes or more.

<Production of Liquid Crystal Cell> The liquid crystal cell system has a cell gap of 3.6 μm between the substrates, and a liquid crystal material having a negative dielectric anisotropy ("MLC6608", manufactured by Merugu Co., Ltd.) is dropped and injected. It is sealed between the substrates, and a liquid crystal layer is formed between the substrates to be fabricated. The retardation value of the liquid crystal layer (i.e., the product of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn Δn.d) was 300 nm. Moreover, the liquid crystal material is aligned in a vertical alignment.

<Installation of VA panel> The upper polarizing plate (visually identifiable side) of the liquid crystal display device using the above-described vertical alignment type liquid crystal cell is such that the polarizing plate 201 provided with the optical compensation film 111 is in the optical compensation film 111 The liquid crystal cell is disposed under the side of the liquid crystal cell, and the polarizing plate 300 having the optical compensation film 120 is disposed under the liquid crystal cell side of the optical compensation film 120.

The upper polarizing plate (polarizing plate 201) and the lower polarizing plate (polarizing plate 300) are attached to the liquid crystal cell via an adhesive. The transmission axis of the upper polarizing plate (polarizing plate 201) is directed upward and downward, and secondly, the transmission axis of the lower polarizing plate (polarizing plate 300) is crossed in the left-right direction to cross the Nichol prism.

<Color shift evaluation> A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. White shows 5V, black shows 0V normal black type. The black display has an azimuth angle of 45 degrees, a black angle of 60 degrees in the polar angle, and a transmission angle (%), and an azimuth angle of 45 degrees, a polar angle of 60 degrees and an azimuth angle of 180 degrees, and a polar angle of 60 degrees. The Δx was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria for color shift] ○: △x is less than 0.02○ △: Δx is 0.02 to 0.04 △: Δx is 0.04 to 0.06 ×: Δx is 0.06 or more

<Evaluation of the viewing angle> In addition, the ratio of the transmittance (white display/black display) was used as the contrast, and the measurement machine (EZ-Contrast 160D, ELDIM company) was used, and the black display (L1) to the white display (L8) was used. The angle of view was measured at the stage (the polar angle range in which the contrast of the black side was not reversed when the contrast was 10 or more) was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria for the angle of view (the range of polar angles without the inversion of the black side when the contrast is 10 or more)] ○: 80° or more in the polar angles of the upper, lower, left and right ○ △: the polar angle in the upper, lower, left and right, and the third direction 80° or more △: 80° or more in the upper and lower left and right, and the polar angle in the 2 directions ×: in the upper and lower left and right, the polar angle of 0 to 1 is 80° or more

<Evaluation of Resistance> The viewing angle in a state where the liquid crystal display device was left in an environment of 30° C. and 90% RH for 250 hours was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation Criteria] ○: ΔCu'v' is less than 0.02 ×: ΔCu'v' is 0.02 or more

(Example 2)

<Resin having positive characteristic birefringence> Tricyclo[4,3,0,1 ^2,5 ]indole-3,7-diene (common name: dicyclopentadiene, hereinafter abbreviated as "DCP" ), tetracyclo[4,4,0,1 ^2,5 ,1 ^7,10 ]dodec-3-ene (common name: tetracyclododecene, hereinafter referred to as "TCD"), and 8-timeth ethylene yl - tetracyclo [4,4,0,1 ^2,5, 1 ^7,10] dodeca-3-ene (common name: tetracyclododecene vinylidene, hereinafter referred to as "ETD") to 47 / The mixture obtained by mixing the ratio of 28/35 (mass ratio) is subjected to ring-opening polymerization, and then subjected to hydrotreatment to obtain a ring-opening polymerization hydrogenated product (hereinafter simply referred to as a raw spintenyl polymer).

The ring-opening polymerization hydrogenated product has a glass transition point (Tg) of 130 ° C as measured by a differential scanning calorimeter (DSC), and a melt viscosity of 980 Pa at a shear rate of 180 sec ^-1 at a temperature of 250 ° C. s.

This raw spinylene-based polymer was used as the resin (A) having a positive characteristic birefringence.

<Resin having a negative characteristic birefringence> As a styrene-maleic anhydride copolymer (manufactured by Rome (trade), trade name: Daylaek D332, melt viscosity 440 Pa.S, Tg = 130 ° C) as having a negative A resin having a birefringence characteristic (B). Hereinafter, the styrene-maleic anhydride copolymer is abbreviated as "D332".

<blocking regulator> using 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol) As a retardation modifier with dichroism. The retardation modifier is commercially available from Asahi Denki Kogyo Co., Ltd. under the trade name Yadika Statab (transliteration) LA-31. In the following, the retardation modifier is "UVA".

A commercially available infrared ray absorbing agent (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYASORB CY-17, maximum absorption wavelength: 782 nm) was used as a retardation adjuster having dichroism. In the following, the retardation modifier is "IR".

a first layer formed of the raw layer of the raw spinel-based polymer, a second layer formed by mixing 100 parts by mass of the above-mentioned "D332" and 4 parts by mass of the above-mentioned UVA and 4 parts by mass of the IR, and The third layer of the ethylene-vinyl acetate copolymer (Mitsubishi Chemical Co., Ltd., trade name: Magic Digu (AP) 543) made of the adhesive layer, [Layer 1 (75 μm) - 3rd Layer (7 μm) - 2nd layer (100 μm) - 3rd layer (7 μm) - 1st layer (75 μm)] Three layers of five-layered laminate 102, using an extrusion molding machine (trade name) LABOPLASTOMILI, Toyo Seiki Co., Ltd., manufactured by co-extrusion molding.

The film (layered product 102) obtained as described above is sent to a tenter having a structure in which a continuous long-length film is fixed at an interval in the longitudinal direction of the tenter holder, and the conveyance is narrowed, and the width direction is An extension device for extending the extension (manufactured by Shimadzu Corporation, trade name "FITZ"), the film temperature was set at 130 ° C, and after 30 seconds, the film was stretched after passing through the heating zone, and the film length direction was 0.70 times. The stretcher holder was extended 2.00 times in the width direction, and an optical compensation film 112 having a film thickness of 60 μm after stretching was obtained.

<Optical Characteristics of Film> The wavelengths of 450, 550, and 650 nm of Re and Rth of the optical compensation film 112 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). The results are shown in Table 1.

As shown in Table 1, it was confirmed that the values of Re and Rth at wavelengths of 450, 550, and 650 nm of the optical compensation film 112 produced by the method of the second embodiment satisfy the relationship of any of the above formulas (1) to (4). .

Further, as a result of measuring Reb and Rthb of the film 102 before stretching, Reb was 3 nm and Rthb was 8 nm.

<Preparation of Polarizing Plate> <<Production of Vision-Recognizable Side Polarizing Plate>> In the fabrication of the visually recognizable side polarizing plate of the above-described Embodiment 1, except that the optical compensation film 112 is used instead of the optical compensation film 111, and the embodiment 1 A visually identifiable polarizing plate (polarizing plate 202) was produced in the same manner.

<Production of Backlight Side Polarizing Plate> <<Production of Optical Compensation Film>> A background lamp side polarizing plate (polarizing plate 300) was produced in the same manner as in the production of the background side polarizing plate of the above-described first embodiment.

<Production of Liquid Crystal Cell> A liquid crystal cell was produced in the same manner as in the above Example 1.

<Installation of VA Panel> In the mounting of the VA panel of the above-described first embodiment, the polarizing plate 202 and the polarizing plate 300 were made in the same manner as in the first embodiment except that the polarizing plate 202 was used instead of the polarizing plate 201. Installed on the VA panel.

Further, as in the above-described first embodiment, the viewing angle, the color shift property, and the resistance were evaluated. The results are shown in Table 1.

(Comparative Example 1)

The film 101 produced in the first embodiment is sent to a general extension device using an extension device having a constant width in the longitudinal direction of the tenter holder and extending in the width direction. The optical compensation film 113 was stretched 1.9 times at a temperature of 218 ° C and the film thickness after stretching was 60 μm.

<Optical characteristics of the film> Re and Rth of the wavelengths 450, 550 and 650 nm of the optical compensation film 113 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). The results are shown in Table 1.

As shown in Table 1, it was confirmed that the values of Re and Rth at wavelengths of 450, 550, and 650 nm of the optical compensation film 113 produced by the method of Comparative Example 1 did not satisfy any of the above formulas (1) to (4). relationship.

<Production of Polarizing Plate> <<Production of Vision-Recognizable Side Polarizing Plate>> In the production of the visually identifiable side polarizing plate of the above-described Embodiment 1, except that the optical compensation film 113 is used instead of the optical compensation film 111, and the embodiment 1 A polarizing plate (polarizing plate 203) was produced in the same manner.

<Production of Backlight Side Polarizing Plate> <<Production of Optical Compensation Film>> A background lamp side polarizing plate (polarizing plate 300) was produced in the same manner as in the production of the background side polarizing plate of the above-described first embodiment.

<Production of Liquid Crystal Cell> A liquid crystal cell was produced in the same manner as in the above Example 1.

In the mounting of the VA panel of the first embodiment, the polarizing plate 203 and the polarizing plate 300 are made in the same manner as in the first embodiment except that the polarizing plate 203 is used instead of the polarizing plate 201. Installed on the VA panel.

Further, as in the above-described first embodiment, the viewing angle, the color shift property, and the resistance were evaluated. The results are shown in Table 1.

(Comparative Example 2)

<Preparation of Cellulose Phthalate Solution CA-1> The following composition was placed in a mixing tank, stirred, and each component was dissolved to prepare a cellulose phthalate solution CA-1. Moreover, Ac = ethyl thiol.

<Preparation of Buffer Solution MT-1> 20 parts by mass of cerium oxide having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Yaya Rogiru, Japan) and 80 parts by mass of methanol were thoroughly stirred and mixed for 30 minutes. As a dispersion of cerium oxide particles. The dispersion and the following composition were placed in a disperser, stirred for further 30 minutes or more, and the components were dissolved to prepare a matting agent solution MT-1.

<Preparation of Additive Solution> The following composition was placed in a mixing tank, heated and stirred, and the components were dissolved to prepare an additive solution AD-1. Further, a retardation discovery agent represented by the following formula (12) is used.

<Preparation of Cellulose Phthalate Film 103> Each of 94.6 parts by mass of the above cellulose phthalate solution CA-1, 1.3 parts by mass of the matting agent solution MT-1, and 2.3 parts by mass of the additive solution AD-1 were filtered and mixed. Casting was carried out using a belt casting machine.

The mass ratio of the retardation discovery agent having the above composition to the cellulose phthalate was 1.0%.

Then, the film was peeled off from the tape at a residual solvent amount of 30%, and dried at 140 ° C for 40 minutes to produce a cellulose phthalate film 103.

The obtained cellulose phthalate film 103 had a residual solvent amount of 0.2% and a film thickness of 100 μm.

<Preparation of Optical Compensation Film 114> The cellulose phthalate film 103 obtained as described above is sent to a width direction by using a tenter having a constant length in the longitudinal direction of the tenter holder in a continuous long-length film. Extending the extended extension device, the film temperature was set at 180 ° C, and after 30 seconds passed through the heating zone, the film was stretched by 0.85 times in the longitudinal direction, and extended by the tenter holder in the width direction by 1.25. The optical compensation film 114 having a film thickness of 125 μm after stretching was obtained.

<Optical Characteristics of Optical Compensation Film 114> Re and Rth of the wavelengths 450, 550 and 650 nm of the optical compensation film 114 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). The results are shown in Table 1.

As shown in Table 1, the values of Re and Rth at wavelengths of 450, 550, and 650 nm of the optical compensation film 114 produced by the method of Comparative Example 2 were confirmed, and the relationship of any of the above formulas (1) to (4) was satisfied. .

Further, as a result of measuring Reb and Rthb of the film 103 before stretching, Reb was 7 nm and Rthb was 55 nm.

<Production of Polarizing Plate> <<Production of Vision-Recognizable Side Polarizing Plate>> In the production of the visually identifiable side polarizing plate of the above-described Embodiment 1, except that the optical compensation film 114 is used instead of the optical compensation film 111, and the embodiment 1 A polarizing plate (polarizing plate 204) was produced in the same manner.

<Production of Backlight Side Polarizing Plate> <<Production of Optical Compensation Film>> A background lamp side polarizing plate (polarizing plate 300) was produced in the same manner as in the production of the background side polarizing plate of the above-described first embodiment.

<Production of Liquid Crystal Cell> A liquid crystal cell was produced in the same manner as in the above Example 1.

<Installation of the VA panel> In the mounting of the VA panel of the first embodiment, the polarizing plate 204 and the polarizing plate 300 are made in the same manner as in the first embodiment except that the polarizing plate 204 is used instead of the polarizing plate 201. Installed on the VA panel.

Further, as in the above-described first embodiment, the viewing angle, the color shift property, and the resistance were evaluated. The results are shown in Table 1.

(Comparative Example 3)

<Preparation of Optical Compensation Film 115> A commercially available polycarbonate resin (manufactured by Bondington, manufactured by Teijin Co., Ltd.) was dissolved in dichloromethane to prepare a slurry solution. The film 105 is produced from the slurry solution by a casting method.

The film sheet 105 obtained as described above is sent to a tenter having a structure in which a continuous long-length film is fixed at an interval in the longitudinal direction of the tenter holder and narrowed between the conveyance, and the extension is extended in the width direction. The extension device of the project (manufactured by Shimadzu Corporation, trade name "FITZ") was stretched 1.5 times at a temperature of 160 ° C, and an optical compensation film 115 having a film thickness of 60 μm after stretching was obtained.

<Optical Characteristics of Optical Compensation Film 115> Re and Rth of the wavelengths 450, 550 and 650 nm of the optical compensation film 115 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). The results are shown in Table 1.

<Production of Polarizing Plate> <<Production of Vision-Recognizable Side Polarizing Plate>> In the production of the visually identifiable side polarizing plate of the above-described Embodiment 1, except that the optical compensation film 115 is used instead of the optical compensation film 111, and the embodiment 1 A visually identifiable polarizing plate (polarizing plate 205) was produced in the same manner.

<Production of Backlight Side Polarizing Plate> <<Production of Optical Compensation Film>> A background lamp side polarizing plate (polarizing plate 300) was produced in the same manner as in the production of the background side polarizing plate of the above-described first embodiment.

<Production of Liquid Crystal Cell> A liquid crystal cell was produced in the same manner as in the above Example 1.

In the mounting of the VA panel of the first embodiment, the polarizing plate 205 and the polarizing plate 300 are made in the same manner as in the first embodiment except that the polarizing plate 205 is used instead of the polarizing plate 201. Installed on the VA panel.

Further, as in the above-described first embodiment, the viewing angle, the color shift property, and the resistance were evaluated. The results are shown in Table 1.

As shown in Table 1, since the optical compensation films of Examples 1 and 2 can satisfy the numerical formulas (1) to (4), a liquid crystal display device provided with a polarizing plate of the optical compensation film is provided in the front direction and the viewing angle direction. A neutral black display can be achieved in either direction.

In addition, since the optical compensation films of Comparative Examples 1 to 3 cannot satisfy the numerical formulas (1) to (4), light leakage occurs in any of the front direction and the viewing angle direction, and the contrast is also poor.

In particular, when the liquid crystal display device was observed to stand in an environment 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, in particular, the viewing angle compensation of the black state in the VA mode, the IPS mode, and the OCB mode are all used in all wavelengths. As a result, the liquid crystal display device of the present invention can alleviate the oblique light leakage phenomenon in black display, and can significantly improve the viewing angle contrast.

Further, in the present invention, when the polarizing plate is bonded, since the manufacturing process of the roll-to-roll method can be realized, an optical compensation film excellent in productivity can be improved.

Further, in the liquid crystal display device of the present invention, since the oblique light detachment at the time of black display in the entire visible light wavelength range can be suppressed, the color shift at the time of black display relating to the viewing angle can be greatly improved.

[Utilization value of industry]

The liquid crystal display device of the present invention is not limited by the display type of the liquid crystal cell, and can be used in a liquid crystal display device having a liquid crystal layer of any display type such as a VA type, an IPS type, an ECB type, a TN type, and an OCB type. Good contrast, suitable for mobile phones, computer screens, TVs, LCD projectors, etc.

Claims (11)

An optical compensation film characterized by satisfying the following formulas (1) to (4), 50 ≦ Re (550) ≦ 200.............. Formula (1) 0.4 ≦ Rth (550) / Re (550) ≦ 0.6 ... Equation (2) 0.1 < Re (450) / Re (550) < 0.95 ... 3) 1.11<Re(650)/Re(550)<1.93...The equation (4) is in the equations (1)~(4), Re(450), Re(550), Re( 650) is an in-plane retardation value (unit: nm) measured by light having wavelengths of 450 nm, 550 nm, and 650 nm, and Rth (550) is a retardation value in the thickness direction measured by light having a wavelength of 550 nm (unit) :nm). The optical compensation film of claim 1 is a polymer having a water content of 1.0% or less. An optical compensation film according to claim 1 is a resin obtained by mixing a resin having a positive characteristic birefringence with a resin having a negative birefringence or a laminate of the same. A method for producing an optical compensation film, comprising: an extension process for extending one of a longitudinal direction and a width direction of the film, and a shrinking process for shrinking the other direction, wherein the shrinking process causes the film to be used The tenter holder is fixed and conveyed, and the extension engineering is performed to extend the film in a direction perpendicular thereto in a direction in which the interval between the direction of conveyance of the tenter holder is narrowed and contracted. A method for producing an optical compensation film, comprising: an extension process for extending one of a longitudinal direction and a width direction of the film, and a shrinkage process for shrinking the other direction, wherein an elongation of the extension process is X%, and when the shrinkage ratio of the shrinkage engineering is Y%, the following formula (Z) is satisfied, For example, the method for preparing an optical compensation film according to claim 5, wherein the optical compensation film before extension meets the following formulas (5) to (6), -20 ≦ Reb (550) ≦ 20. . . . . . . Equation (5) -20≦Rthb(550)≦20. . . . . . In the above formula (5) to (6), Reb (550) is an in-plane retardation value (unit: nm) of the optical compensation film before stretching measured by light having a wavelength of 550 nm, Rthb The thickness direction retardation value (unit: nm) of the optical compensation film before stretching measured by light of 550 nm. An optical compensation film according to claim 1 of the patent application, which is produced by the method for producing an optical compensation film of claim 4 or 5. A method for producing a polarizing plate, which comprises the step of bonding a long-length optical compensation film according to item 7 of the patent application with a polarizing plate and a roll-to-roller. A polarizing plate characterized by being produced by a method of producing a polarizing plate according to claim 8 of the patent application. A liquid crystal display device comprising a method of manufacturing a shrinking process including a process of extending one of a longitudinal direction and a width direction of a film and shrinking a direction of the other direction. The polarizing plate, the liquid crystal cell, and the following formula (7-) can be used for the long-length optical compensation film of the formula (1) to (4) which is bonded by a polarizer and a roll-to-roller. 1) and the polarizing plate of the optical anisotropic layer of the formula (7-2), -10<Re(550)<10. . . . . . . . . Equation (7-1) 100<| Rth(550)|<300. . . . . . Equation (7-2). The liquid crystal display device of claim 10, wherein the liquid crystal cell is of a VA type.