JP2008052262A - Optical film, production method of optical film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film ensuring correct optical compensation of a liquid crystal cell irrespective of the ambient humidity to achieve high contrast and improve the color shift dependent on the viewing angle direction at the black display time, a production method of the optical film, and a polarizing plate and a liquid crystal display device each using the optical film. <P>SOLUTION: The optical film includes at least one kind of humidity dependency improver that improves ΔRe, wherein the optical film has a ratio of Re/Rth which is larger as a wavelength is longer in the visible wavelength region; and Re which is larger as a wavelength is longer in the visible wavelength region; wherein Re represents an in-plane retardation (unit: nm) of the optical film; Rth represents a retardation (unit: nm) in a thickness direction of the optical film; and ΔRe represents a humidity dependency of Re defined by the formula (1): ΔRe(nm)=¾Re(550)10%RH-Re(%%)80%RH¾ wherein Re(550)10%RH represents Re at a wavelength of 550 nm, at a temperature of 25°C and a relative humidity of 10%; and Re(550)80%RH represents Re at a wavelength of 550 nm, at a temperature of 25°C and a relative humidity of 80%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical film in which a liquid crystal cell accurately optically compensates regardless of environmental humidity and improves color shift depending on a high contrast and a viewing angle direction during black display, and a method for producing the optical film, The present invention relates to a polarizing plate and a liquid crystal display device using an optical film.

  The liquid crystal display device has a liquid crystal cell and a polarizing plate. The polarizing plate generally has a protective film and a polarizing film made of cellulose acetate. For example, a polarizing film made of a polyvinyl alcohol film is dyed with iodine, stretched, and both surfaces thereof are laminated with a protective film. Obtained. In the transmissive liquid crystal display device, polarizing plates are attached to both sides of the liquid crystal cell, and one or more optical compensation films may be disposed. In a reflective liquid crystal display device, the reflector, liquid crystal cell, one or more optical compensation films, and a polarizing plate are usually arranged in this order. The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule. The liquid crystal cell performs ON / OFF display depending on the alignment state of liquid crystal molecules, and can be applied to both transmission and reflection types. TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory Bend). ), VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence) have been proposed.

  Among such LCDs, for applications that require high display quality, a 90 degree twisted nematic liquid crystal display device (hereinafter referred to as a TN mode) that uses nematic liquid crystal molecules having positive dielectric anisotropy and is driven by a thin film transistor. Is mainly used. However, although the TN mode has excellent display characteristics when viewed from the front, the contrast decreases when viewed from an oblique direction, and display is caused by gradation inversion that reverses the brightness in gradation display. There is a viewing angle characteristic that the characteristic is deteriorated, and this improvement is strongly demanded.

  On the other hand, the share of liquid crystal systems with a wide viewing angle such as the IPS system, OCB system, and VA system is expanding with the recent increase in demand for liquid crystal televisions. Each system has improved display quality year by year, but the problem of color misregistration that occurs when viewed obliquely has not been solved.

  Conventionally, 0.6 <Δn · d (450) / Δn · d (550) <0.97, 1.01 <Δn · d is used as a retardation plate of a polymer oriented film, particularly as a quarter-wave plate. It has been known that (650) / Δn · d (550) <1.35 (Δn · d (λ) is a retardation of a polymer alignment film at a wavelength λnm) (Patent Document 1).

JP 2000-137116 A

  An object of the present invention is to provide an optical film in which a liquid crystal cell accurately optically compensates regardless of environmental humidity and improves color shift depending on the viewing angle direction during high contrast and black display, and a method for producing the optical film An object of the present invention is to provide a polarizing plate and a liquid crystal display device using the optical film.

〔７〕
〔６〕に記載の光学フィルムの製造方法によって製造された、〔１〕〜〔５〕のいずれかに記載の光学フィルム。
〔８〕
Ｒｅ（５５０）が２０〜１００ｎｍの範囲であり、かつＲｔｈ（５５０）が１００〜３００ｎｍの範囲であることを特徴とする〔１〕〜〔５、７のいずれか〕に記載の光学フィルム。
（Ｒｅ(５５０)は波長５５０ｎｍの光における面内レターデーションＲｅ（単位：ｎｍ）、Ｒｔｈ(５５０)は波長５５０ｎｍの光における膜厚方向のレターデーションＲｔｈ（単位：ｎｍ）である。）
〔９〕
光学フィルムがセルロースアシレートを含むことを特徴とする〔１〕〜〔５〕、〔７〕〜〔８〕のいずれかに記載の光学フィルム。
〔１０〕
セルロースアシレートのグルコース単位の２位の水酸基のアシル基による置換度をＤＳ２、３位の水酸基のアシル基による置換度をＤＳ３、６位の水酸基のアシル基による置換度をＤＳ６としたときに、下記式（ＩＶ）および（Ｖ）を満たすことを特徴とする〔９〕に記載の光学フィルム。
式（ＩＶ）：２．０≦（ＤＳ２＋ＤＳ３＋ＤＳ６）≦３．０
式（Ｖ）：ＤＳ６／（ＤＳ２＋ＤＳ３＋ＤＳ６）≧０．３１５
〔１１〕
下記式（ＶＩ）および（ＶＩＩ）を満たすセルロースアシレートを含むことを特徴とする、〔９〕または〔１０〕に記載の光学フィルム。
式（ＶＩ）： ２．０ ≦ Ａ＋Ｂ ≦ ３．０
式（ＶＩＩ）： ０ ＜ Ｂ
（式（ＶＩ）および（ＶＩＩ）において、Ａは前記セルロースアシレートのグルコース単位の水酸基のアセチル基による置換度であり、Ｂは、前記セルロースアシレートのグルコース単位のプロピオニル基またはブチリル基またはベンゾイル基による置換度である。）
〔１２〕
レターデーション発現剤を含有することを特徴とする〔１〕〜〔５〕、〔７〕〜〔１１〕のいずれかに記載の光学フィルム。
〔１３〕
偏光膜と、該偏光膜を挟持する一対の保護膜とを有する偏光板であって、前記保護膜の少なくとも一枚が〔１〕〜〔５〕、〔７〕〜〔１２〕のいずれかに記載の光学フィルムであることを特徴とする偏光板。
〔１４〕
〔１〕〜〔５〕、〔７〕〜〔１２〕のいずれかに記載の光学フィルムまたは〔１３〕に記載の偏光板を有することを特徴とする液晶表示装置。
〔１５〕
液晶セルと該液晶セルの両側に配置された一対の偏光板を有する液晶表示装置であって、前記偏光板が〔１３〕に記載の偏光板であることを特徴とするＩＰＳ、ＯＣＢ、またはＶＡモード液晶表示装置。
〔１６〕
〔１３〕に記載の偏光板をバックライト側に用いたことを特徴とするＶＡモード液晶表示装置。 Means for achieving the object of the present invention are as follows.
[1]
The ratio Re / Rth of the retardation value Re in the film plane and the retardation value Rth in the film thickness direction increases as the wavelength increases in the visible wavelength range, and Re increases as the wavelength increases in the visible wavelength range. An optical film comprising at least one humidity dependency improving agent for improving the humidity dependency ΔRe of Re of the optical film represented by the following formula (1):
Formula (1): Hu dependency of optical film on humidity ΔRe (nm)
= | Re (550) 10% RH-Re (550) 80% RH |
(In the above formula, Re (550) 10% RH and Re (550) 80% RH are Re at a wavelength of 550 nm at 25 ° C. and a relative humidity of 10%, respectively, and Re at a relative humidity of 80% RH.)
[2]
The optical film according to [1], wherein the optical film further contains at least one kind of polymer.
[3]
When the mass of the polymer in the optical film is 100 parts by mass, the content of the humidity-dependent improving agent is the humidity dependence ΔRe (A) of Re of the optical film of A part by mass, and the content is The optical film according to [2], wherein the humidity dependency ΔRe (0) of Re of the optical film of 0 part by mass satisfies the following formula (2).
Formula (2): | ΔRe (A) −ΔRe (0) | / A ≧ 1 (nm / part by mass)
[4]
The optical film according to any one of [1] to [3], wherein the retardation value satisfies the following formulas (Ia), (Ib), (II), (III), and (A).
Formula (Ia): 0.4 <{(Re (450) / Rth (450)) / (Re (550) / Rth (550))} <0.95, and Formula (Ib): 1.05 <{ (Re (650) / Rth (650)) / (Re (550) / Rth (550))} <1.9
Formula (II): 0.1 <(Re (450) / Re (550)) <0.95
Formula (III): 1.03 <(Re (650) / Re (550)) <1.93
(In the formulas (Ia), (Ib), (II) and (III), Re (λ) is the in-plane retardation Re (unit: nm) in the light of wavelength λnm, and Rth (λ) is Retardation Rth in the film thickness direction (unit: nm).)
Formula (A): 10 ≧ | Re (550) 10% RH-Re (550) 80% RH |
(In the formula (A), Re (550) 10% RH and Re (550) 80% RH are Re (550) at 25 ° C., 10% and 80% RH, respectively.)
[5]
The optical film according to any one of [1] to [4], wherein the humidity dependency improving agent is a compound containing at least two hydrogen bonding groups.
[6]
A method for producing an optical film comprising a step of stretching a film at a stretch ratio of X% and a step of shrinking the film at a shrinkage ratio of Y%, wherein the relationship between the stretch ratio of X% and Y% is represented by the following formula (Z) And the film further contains a humidity dependency improving agent which is a compound containing at least two hydrogen bonding groups.
Formula (Z)

[7]
The optical film according to any one of [1] to [5], which is produced by the method for producing an optical film according to [6].
[8]
Re (550) is in the range of 20 to 100 nm, and Rth (550) is in the range of 100 to 300 nm. The optical film as described in any one of [1] to [5, 7].
(Re (550) is the in-plane retardation Re (unit: nm) for light having a wavelength of 550 nm, and Rth (550) is the retardation Rth (unit: nm) in the film thickness direction for light having a wavelength of 550 nm.)
[9]
The optical film according to any one of [1] to [5] and [7] to [8], wherein the optical film contains cellulose acylate.
[10]
When the substitution degree of the 2-position hydroxyl group of the cellulose acylate with the acyl group is DS2, the substitution degree of the 3-position hydroxyl group with the acyl group is DS3, and the substitution degree of the 6-position hydroxyl group with the acyl group is DS6, The optical film according to [9], wherein the following formulas (IV) and (V) are satisfied.
Formula (IV): 2.0 ≦ (DS2 + DS3 + DS6) ≦ 3.0
Formula (V): DS6 / (DS2 + DS3 + DS6) ≧ 0.315
[11]
The optical film according to [9] or [10], comprising cellulose acylate satisfying the following formulas (VI) and (VII):
Formula (VI): 2.0 ≦ A + B ≦ 3.0
Formula (VII): 0 <B
(In the formulas (VI) and (VII), A represents the degree of substitution of the hydroxyl group of the glucose unit of the cellulose acylate with an acetyl group, and B represents the propionyl group, butyryl group or benzoyl group of the glucose unit of the cellulose acylate. The degree of substitution by.)
[12]
The optical film according to any one of [1] to [5] and [7] to [11], which contains a retardation developer.
[13]
A polarizing plate having a polarizing film and a pair of protective films sandwiching the polarizing film, wherein at least one of the protective films is any one of [1] to [5] and [7] to [12] A polarizing plate, which is the optical film described above.
[14]
A liquid crystal display device comprising the optical film according to any one of [1] to [5] and [7] to [12] or the polarizing plate according to [13].
[15]
An IPS, OCB, or VA, comprising a liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell, wherein the polarizing plate is the polarizing plate described in [13]. Mode liquid crystal display.
[16]
A VA mode liquid crystal display device comprising the polarizing plate according to [13] on a backlight side.

  In the present specification, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 nm to 780 nm. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

  In this specification, “polarizing plate” is cut into a size to be incorporated into a long polarizing plate and a liquid crystal device unless otherwise specified (in this specification, “cutting” includes “punching” and “cutting out”. It is used in the meaning including both of the polarizing plates. In this specification, “polarizing film” and “polarizing plate” are distinguished from each other, and “polarizing plate” is a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. Means.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light with a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane The light is incident at a wavelength of λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction of KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed average refractive index, and the input film thickness value.

In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle The value is calculated by KOBRA 21ADH or WR after changing the sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the case where there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (3) and (4).

Formula (3):

The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In formula (3), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. .

Formula (4):

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optic axis, Rth (λ) is calculated by the following method.
Rth (λ) is from -50 ° to + 50 ° with respect to the normal direction of the film, with Re (λ) as the slow axis (indicated by KOBRA 21ADH or WR) in the plane and the tilt axis (rotation axis). Measured at 11 points by making light of wavelength λ nm incident from each inclined direction in 10 degree steps, and based on the measured retardation value, assumed average refractive index value and input film thickness value, KOBRA 21ADH or Calculated by WR.
In the above measurement, the assumed value of the average refractive index may be the value in the polymer handbook (JOHN WILEY & SONS, INC) and various optical film catalogs. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  The present invention has been completed based on the knowledge obtained as a result of intensive studies by the present inventors. By using the above-described optical film, the VA method, the IPS method, and the like are used regardless of the environmental humidity. , OCB type black state viewing angle compensation is possible at almost all wavelengths. As a result, in the liquid crystal display device of the present invention, light leakage in an oblique direction during black display is reduced, and the viewing angle contrast is remarkably improved. In addition, the liquid crystal display device of the present invention can suppress light leakage in an oblique direction during black display in almost all visible light wavelength regions. Has been greatly improved.

  In the present invention, an optical film has optical characteristics having different wavelength dispersion of retardation in a normal direction and an oblique direction inclined with respect to the normal direction, for example, a polar angle direction of 60 degrees, and this is actively applied to optical compensation. Use it. The scope of the present invention is not limited by the display mode of the liquid crystal layer, and can be used for a liquid crystal display device having a liquid crystal layer of any display mode such as VA mode, IPS mode, ECB mode, TN mode, and OCB mode. .

  Details of the present invention will be described below.

(Optical film)
In the optical film of the present invention, (i) the ratio Re / Rth of the retardation value Re in the film plane and the retardation value Rth in the film thickness direction increases as the wavelength increases in the visible wavelength range, and (ii) Re However, the larger the wavelength in the visible wavelength region, the larger.

  The wavelength dispersion of Re and Rth in the visible wavelength region (dependence of Re on the visible wavelength) (i) and (ii) of the optical film of the present invention will be described.

  As (ii), the greater the wavelength, the greater Re, which is advantageous for optical compensation (viewing angle compensation) by an optical film in a liquid crystal display device. Since the amount of optical compensation by the optical film is determined by (film retardation) / (wavelength λ), the smaller the wavelength, the larger the amount of optical compensation, and the larger the wavelength, the smaller the amount of optical compensation. Therefore, the same optical compensation amount can be obtained at any wavelength by reducing the retardation of the film (Re in this case) when the wavelength is small and increasing it when the wavelength is large.

  Next, in (i), the ratio Re / Rth of Re and Rth increases as the wavelength increases in the visible wavelength range, so that Rth is larger than the amount of chromatic dispersion of Re (the amount of Re increases as the wavelength increases). The amount of chromatic dispersion is reduced. This is also advantageous for optical compensation by an optical film in a liquid crystal display device. The chromatic dispersion of the retardation Rth in the film thickness direction is relatively smaller than the chromatic dispersion of the retardation Re in the in-plane direction, and almost all of the optical compensation in the black state of the VA method, the IPS method, and the OCB method. At a wavelength of

  The optical film of the present invention preferably has a retardation value satisfying the following formulas (Ia), (Ib), (II), (III) and (A).

Formula (Ia): 0.4 <{(Re (450) / Rth (450)) / (Re (550) / Rth (550))} <0.95, and Formula (Ib): 1.05 <{ (Re (650) / Rth (650)) / (Re (550) / Rth (550))} <1.9
Formula (II): 0.1 <(Re (450) / Re (550)) <0.95
Formula (III): 1.03 <(Re (650) / Re (550)) <1.93
(In the formulas (Ia), (Ib), (II) and (III), Re (λ) is the in-plane retardation Re (unit: nm) in the light of wavelength λnm, and Rth (λ) is Retardation Rth in the film thickness direction (unit: nm).)
Formula (A): 10 ≧ | Re (550) 10% RH-Re (550) 80% RH |
(In the formula (A), Re (550) 10% RH and Re (550) 80% RH are Re (550) at 25 ° C., 10% and 80% RH, respectively.)

The formulas (Ia), (Ib), (II) and (III) more preferably satisfy the following formulas (Ia-1), (Ib-1), (II-1) and (III-1). .
Formula (Ia-1): 0.5 <{(Re (450) / Rth (450)) / (Re (550) / Rth (550))} <0.9
Formula (Ib-1): 1.1 <{(Re (650) / Rth (650)) / (Re (550) / Rth (550))} <1.7
Formula (II-1): 0.2 <(Re (450) / Re (550)) <0.9
Formula (III-1): 1.1 <(Re (650) / Re (550)) <1.7
Also, | Re (550) 10% RH−Re (550) 80% RH |, that is, the difference ΔRe (= Re _10% − Re _80% ) is more preferably −10 to 10 nm, and further preferably −6 to 6 nm.

(Humidity dependency improver)
The optical film of the present invention is also characterized in that it contains at least one humidity dependency improving agent that improves the humidity dependency ΔRe of Re of the optical film represented by the following formula (1).
Formula (1): Hu dependency of optical film on humidity ΔRe (nm)
= | Re (550) 10% RH-Re (550) 80% RH |
(In the above formula, Re (550) 10% RH and Re (550) 80% RH are Re at a wavelength of 550 nm at 25 ° C. and a relative humidity of 10%, respectively, and Re at a relative humidity of 80% RH.)

  The optical film of the present invention is characterized by containing at least one kind of polymer and at least one kind of humidity dependency improving agent.

The humidity dependence improving agent has an effect that the humidity dependence ΔRe of Re of the optical film of the present invention satisfies the following formula (2).
Formula (2): | ΔRe (A) −ΔRe (0) | / A ≧ 1 (nm / part by mass)
Here, ΔRe (A) is the humidity dependency of Re of the optical film having a humidity dependency improver content of A part by mass when the mass of the polymer is 100 parts by mass, and ΔRe (0) is the humidity. This is the humidity dependency of Re in an optical film having a dependency improver content of 0 part by mass.

The humidity dependency improver is preferably a compound containing at least two hydrogen bonding groups.
Hereinafter, a case where cellulose acylate, which is preferable as a material for forming the optical film of the present invention, is used will be described as an example.

The humidity dependence of the in-plane retardation can be improved by adding a humidity dependence improving agent to the optical film of the present invention. This is because the humidity-dependent improving agent has two or more hydrogen bonding groups and interacts with the hydroxyl group of cellulose acylate to form a pseudo-crosslinking point between cellulose acylate chains. This is considered to inhibit the interaction with external water molecules.
Therefore, a hydrogen bondable group for interacting with cellulose acylate is essential for the humidity dependence improver. However, when there are many hydrogen bonding groups in the humidity dependency improver and the film becomes too hydrophilic, the moisture content and water permeability of the film increase and the quality and heat durability of the polarizing plate deteriorates.
Therefore, the humidity dependency improver preferably has one or more aromatic rings in order to increase hydrophobicity.
Furthermore, it is most preferable that the humidity dependency improver has 2 to 4 hydrogen bonding groups and 1 to 3 aromatic rings.
In the present invention, a hydrogen bonding group is a functional group having a hydrogen atom and capable of forming a hydrogen bond between the hydrogen atom and another functional group having a high degree of electrical negativeity. The binding group is preferably an amino group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a hydroxy group, a mercapto group, or a carboxyl group, and a functional group such as a hydroxy group, an acylamino group, or a sulfonylamino group. Is particularly preferred.
In the present invention, the humidity dependency improver is desirably contained in the cellulose acylate film in an amount of 1 to 30%, more preferably 5 to 20%, and particularly preferably 7 to 16%.

The molecular weight of the humidity dependence improving agent according to the present invention is preferably 250 or more and 2000 or less. Moreover, it is preferable that the boiling point is 260 degreeC or more. The boiling point can be measured using a commercially available measuring device (for example, TG / DTA100, manufactured by Seiko Electronics Industry Co., Ltd.).
Although various compounds can be used as the humidity dependence improving agent of the present invention, compounds represented by the following general formula (a) can be preferably used.

General formula (a)

In the general formula (a), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , or R ₆ represents a hydrogen atom or a substituent, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , or At least two of R ₆ are hydrogen bonding groups. The following substituent T can be applied as the substituent.

Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2-8, for example, propargyl, 3-pentynyl, etc.), aryl groups (preferably having 6-30 carbon atoms) More preferably, it has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like, and a substituted or unsubstituted amino group (preferably having 0 to 0 carbon atoms). 20, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc.), an alkoxy group (preferably having a carbon number) 1 to 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more Preferably it has 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 2-naphthyloxy and the like. An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl). An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group ( Preferably it has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, and examples thereof include phenyloxycarbonyl, etc.), an acyloxy group (preferably 2 to 20 carbon atoms, More preferably, it has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms. Nzoyloxy and the like. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino group (preferably having carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and sulfonylamino groups (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, and particularly preferably 0 to 12 carbon atoms, such as sulfamoyl and methylsulfamoyl). , Dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl). , Methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio etc.), arylthio group (preferably Has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms) More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl , Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms). For example, trimethylsilyl, triphenylsilyl, etc.) . Among these, an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, and an aryloxy group are more preferable, and an alkyl group, an aryl group, and an alkoxy group are more preferable.
These substituents may be further substituted with a substituent T. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

Further, at least two of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , or R ₆ are substituted or unsubstituted amino group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino. Group, a hydroxy group, a mercapto group, and a carboxyl group, more preferably an amino group and a hydroxy group, and particularly preferably a hydroxy group. In this case, the substituents may be the same or different.

  Although the especially preferable example of the compound represented with general formula (a) preferably used for this invention below is shown below, this invention is not limited to these specific examples.

(Optical film manufacturing method)
The method for producing an optical film of the present invention includes a step (stretching step) of stretching the optical film at a stretching ratio X% and a step (shrinking step) of contracting the film at a shrinkage rate Y%. And Y% satisfy the following formula (Z), and the film further contains a humidity dependency improving agent which is a compound containing at least two hydrogen bonding groups.

  Formula (Z)

  As a result of intensive studies, the inventors of the present invention include a humidity dependency improving agent which is a compound including a stretching step and a shrinking step and is a compound including at least two hydrogen bonding groups. , (Ib), (II), and (III), and it was found that an optical film having low humidity dependency of the front retardation Re can be obtained.

  The method for producing an optical film of the present invention preferably includes a stretching process for stretching in the film transport direction and a shrinking process for contracting while gripping the film in the film width direction, or stretching in the film width direction. It is preferable to include the extending process to perform and the shrinking process to shrink in the conveyance direction of a film.

First, a method for producing a film including a stretching process of stretching in the film transport direction and a contracting process of contracting while gripping the film in the width direction of the film will be described.
In this case, the film will be stretched in the film transport direction. As a method of stretching in the film transport direction, a circumferential speed difference is applied to a plurality of rolls, and the roll circumferential speed difference is utilized between the longitudinal directions. A method of stretching is preferably used. Also, in film formation by the solution casting method, when peeling a semi-dried film cast on a stainless steel band or drum, the speed of film peeling is adjusted by adjusting the speed of the film transport roller. A method of increasing the film winding speed is also preferably used.
In the width direction of the film, it is conveyed while being gripped by a device called a tenter that fixes both ends of the film with clips and pins, and the film is contracted substantially perpendicular to the stretching direction by gradually narrowing the width of the tenter. I can do it.
The stretching step and the shrinking step can be sequentially performed in the order of stretching / shrinking or shrinking / stretching.

  In addition, the film is gripped by a tenter that operates in two axes, the film transport direction and the width direction, such as a chain type, screw type, pantograph type, linear motor type, etc. While stretching, the width of the tenter can be gradually reduced to shrink in the width direction.

  On the other hand, in the cellulose acylate manufacturing method including a stretching process for stretching in the width direction of the film and a shrinking process for contracting in the film transport direction, the film transport such as chain type, screw type, pantograph type, linear motor type, etc. The film can be contracted by gripping it with a tenter that operates in two directions of the direction and the width direction and gradually narrowing the gap between the clips in the transport direction while stretching in the width direction of the film.

  In the method using the tenter operating in the biaxial direction of the film conveyance direction and the width direction described above, it can be said that at least a part of the stretching step and the shrinking step are performed simultaneously. As a result of the present inventors' study, such simultaneous processing is easy to reduce non-uniform stretching / shrinkage in the film plane called bowing by adjusting the timing, magnification, and speed of stretching / shrinking. It turns out that it has an advantage.

  In addition, Ichikin Kogyo Co., Ltd. is a stretching apparatus that specifically performs a stretching process that stretches either the longitudinal direction or the width direction of the film as described above, simultaneously shrinks the other, and simultaneously increases the film thickness of the film. A company-made FITZ machine or the like can be desirably used. This apparatus is described in (Japanese Patent Laid-Open No. 2001-38802).

  As a result of intensive studies, the inventors of the present invention have studied the above-mentioned formulas (Ia), (Ib), (II) while keeping Re within a desired range (20 to 100 nm). In order to satisfy the relationship of (III) and (III), it has been found that it is effective that the relationship between the stretching rate X% in the stretching step and the shrinkage rate Y% in the shrinking step satisfies the following formula (Z).

  Formula (Z)

When the relationship between the stretch rate and the shrinkage rate is below the lower limit of the formula (Z), a special addition is required to satisfy the desired Re and the relationships of the formulas (Ia), (Ib), (II), (III) Technical measures such as combined use of additives and blending of different polymers are required, which cause other problems such as crying out of additives and increased manufacturing costs. On the other hand, when the relationship between the stretching rate and the shrinkage rate exceeds the upper limit of the formula (Z), wrinkles are generated in the film after the stretching rate and the shrinking step, and it becomes impossible to use as an optical film.
In addition, the stretch rate as used in the field of this invention means the ratio of the length of the film after extending | stretching with respect to the length of the film before extending | stretching in a extending direction, and a shrinkage rate is the film before shrinking | contracting in a shrinking direction. It means the ratio of the contracted length of the film after contraction to the length.

  In the range satisfying the above formula (Z), the stretching ratio is preferably 20 to 50%, particularly preferably 25 to 45%. The shrinkage is preferably 15 to 45%, particularly preferably 20 to 40%.

  Further, as a result of the study by the present inventors, it is preferable to carry out the stretching step and the shrinking step at a temperature not lower than the glass transition temperature of the film and not higher than the crystallization temperature in order to achieve a desired stretching ratio and shrinkage ratio and optical properties. I understood it. If the temperature is lower than the glass transition temperature, it is difficult to carry out the shrinking process because the heat shrinkage of the film cannot be used. Further, when heated to a temperature equal to or higher than the crystallization temperature, Re decreases, so that desired optical properties cannot be achieved.

  In addition, the measurement of the glass transition temperature in the present invention was performed by adjusting a film sample (unstretched) 5 mm × 30 mm at 25 ° C. and 60% RH for 2 hours or more, and then measuring a dynamic viscoelasticity measuring device “Vibron: DVA-225”. Measured at a distance between grips of 20 mm, a heating rate of 2 ° C./min, a measurement temperature range of 30 ° C. to 200 ° C., and a frequency of 1 Hz, and stored in a logarithmic axis on the vertical axis. The temperature at which the storage elastic modulus transitions from the solid region to the glass transition region when the temperature is taken in terms of the elastic modulus and the linear axis on the horizontal axis. Tg. Specifically, on the obtained chart, when the straight line 1 is drawn in the solid region and the straight line 2 is drawn in the glass transition region, the intersection of the straight line 1 and the straight line 2 decreases rapidly when the temperature rises. The glass transition temperature Tg (dynamic viscoelasticity) was determined because the film started to soften and the temperature started to shift to the glass transition region.

  The treatment temperature is the film surface temperature measured with a non-contact infrared thermometer.

The present invention can be carried out by wet stretching in which a film formed by a solution casting method is stretched during drying. In addition, after the film is dried, the film can be continuously stretched, or after being wound up, a separate stretching process can be performed. Moreover, it can also be applied to stretching of a film formed by a melting method substantially containing no solvent. The stretching or shrinking of the film may be performed in one stage or in multiple stages. When it is performed in multiple stages, the product of the respective draw ratios may be set in the above-described preferable range.
The stretching speed is preferably 5% / min to 1000% / min, and more preferably 10% / min to 500% / min. The stretching is preferably performed by a heat roll or / and a radiant heat source (such as an IR heater) or warm air.

  It is preferable to provide a preheating step before stretching. You may heat-process after extending | stretching. The heat treatment temperature is preferably 20 ° C. to 10 ° C. higher than the glass transition temperature of the film, and the heat treatment time is preferably 1 second to 3 minutes. The heating method may be zone heating or partial heating using an infrared heater. You may slit the both ends of a film in the middle or the end of a process. These slit scraps are preferably recovered and reused as raw materials. The following techniques can be used as appropriate without departing from the spirit of the present invention. Further, the tenter is disclosed in Japanese Patent Application Laid-Open No. 11-077718. When the web is dried while the width is maintained by the tenter, the dry gas blowing method, the blowing angle, the wind speed distribution, the wind speed, the air volume, the temperature difference, and the air volume difference. Technology that ensures the prevention of quality degradation such as flatness when increasing the speed by the solution casting method or widening the web width by appropriately controlling the ratio of up and down blowing air volume, the use of high specific heat drying gas, etc. Is disclosed.

  Japanese Patent Application Laid-Open No. 11-077782 discloses a temperature gradient in the width direction of the film in the step of shrinking the stretched thermoplastic resin film by an amount less than the stretch amount by thermal relaxation after the stretch step in order to prevent unevenness. An invention is described in which a heat treatment is provided.

  Further, in order to suppress curling due to the regulation of the clip biting width, Japanese Patent Application Laid-Open No. 2002-248680 discloses stretching with a tenter clip biting width D ≦ (33 / (log stretch rate × log volatile content)). Describes an invention that suppresses curling and facilitates film conveyance after the stretching step.

  Furthermore, in order to achieve both high-speed soft film conveyance and stretching, Japanese Patent Application Laid-Open No. 2002-337224 describes an invention that switches tenter conveyance to a first half pin and a second half clip.

  Further, in order to prevent foaming of the tenter-dried web, improve detachability, and prevent dust generation, Japanese Patent Application Laid-Open No. 2003-004374 discloses that in the drying apparatus, hot air from the dryer is applied to both edges of the web. The invention is described in which the width of the dryer is formed shorter than the width of the web so as not to hit.

  Further, in order to prevent foaming of the tenter-dried web, improve releasability, and prevent dust generation, Japanese Patent Application Laid-Open No. 2003-019775 discloses that both ends of the web are prevented from hitting the holding portion of the tenter. An invention is described in which a wind shield is provided on the inside of the part.

  Furthermore, in order to stably carry and dry, Japanese Patent Application Laid-Open No. 2003-053749 discloses that the thickness after drying of both ends of the film carried by the pin tenter is X μm, the average after drying of the product part of the film When the thickness is T μm, the relationship between X and T is 40 ≦ X ≦ 200 when Equation (1) T ≦ 60, and 40+ (T−60) × 0 when Equation (2) 60 <T ≦ 120. The invention that satisfies the relationship of 52+ (T−120) × 0.2 ≦ X ≦ 400 when .2 ≦ X ≦ 300 or Formula (3) 120 <T is described.

  Further, in order to prevent wrinkles from occurring in the multistage tenter, JP-A-2-182654 discloses a tenter device in which a heating chamber and a cooling chamber are provided in a dryer of the multistage tenter, and left and right clip chains are provided. A separate cooling invention is described.

  Furthermore, in order to prevent web breakage, wrinkles, and conveyance failure, Japanese Patent Application Laid-Open No. 9-077315 describes an invention in which the inner pin density is increased and the outer pin density is decreased in the pin tenter pins. Yes.

  In addition, in order to prevent foaming of the web itself and adhesion of the web to the holding means in the tenter, Japanese Patent Application Laid-Open No. 9-085846 discloses that both side edge holding pins of the web are blown-type cooled in the tenter drying apparatus. An invention is described in which a pin is cooled to below the foaming temperature of the web and the pin immediately before the web is entrapped is cooled to a gelling temperature of the dope + 15 ° C. or lower in the duct type cooler.

  Further, in order to prevent pin tenter losing and improve foreign matter, Japanese Patent Application Laid-Open No. 2003-103542 discloses a web surface that cools the insertion structure and contacts the insertion structure in the pin tenter. An invention relating to a solution casting method in which the temperature does not exceed the gelling temperature of the web is described.

  In order to prevent deterioration in quality such as flatness when the speed is increased by the solution casting method or the width of the web is widened by a tenter, JP-A-11-0777718 discloses a web in the tenter. Is dried at a wind speed of 0.5 to 20 (40) m / s, a transverse temperature distribution of 10% or less, a web up / down air volume ratio of 0.2-1, and a dry gas ratio of 30-250 J /. The invention of Kmol is described. Furthermore, preferable drying conditions are disclosed depending on the amount of residual solvent in drying in the tenter. Specifically, after the web is peeled off from the support, the angle at which the air blows from the blowout port is 30 ° to 150 ° with respect to the film plane until the amount of residual solvent in the web reaches 4% by mass. And the difference between the upper limit value and the lower limit value is within 20% of the upper limit value when the wind speed distribution on the film surface located in the direction in which the drying gas blows out is based on the upper limit value of the wind speed, the drying gas When the amount of residual solvent in the web is 130% by mass or less and 70% by mass or more, the wind speed of the dry gas blown from the blow type dryer on the web surface is 0.5 m / sec. When the residual solvent amount is less than 70% by mass and less than 4% by mass and the residual solvent amount is less than 70% by mass and less than 4% by mass, the dry gas wind blown out at a wind speed of 0.5 to 40m / sec. When the temperature distribution of the drying gas in the width direction of the web is based on the upper limit value of the gas temperature, the difference between the upper limit value and the lower limit value should be within 10% of the upper limit value, the residual solvent in the web It is described that when the amount is 4% by mass or more and 200% by mass or less, the air flow ratio q of the dry gas blown out from the blow-out port of the blow-type dryer located above and below the conveyed web is 0.2 ≦ q ≦ 1. Has been. Furthermore, as a preferred embodiment, at least one kind of gas is used for the drying gas, the average specific heat is 31.0 J / K · mol or more and 250 J / K · mol or less, and the room temperature contained in the drying gas during drying. And the concentration of the liquid organic compound is dried with a drying gas having a saturated vapor pressure of 50% or less.

  In order to prevent the flatness and coating from deteriorating due to the generation of contaminants, Japanese Patent Application Laid-Open No. 11-0777719 discloses that in a TAC (triacetyl cellulose) manufacturing apparatus, a clip of a tenter has a built-in heating part. The invention is described. As a further preferable aspect, a device for removing foreign matter generated at the contact portion between the clip and the web between the time when the tenter clip releases the web and the time when the web is carried again, a jetting gas or liquid, and Remove foreign matter using a brush, the residual amount when the clip or pin contacts the web is 12% by mass or more and 50% by mass or less, and the surface temperature of the contact part between the clip or pin and the web is 60 ° or more. It is disclosed that it is 200 ° or less (more preferably 80 ° or more and 120 ° or less).

  In order to improve flatness, improve quality deterioration due to tearing in the tenter, and increase productivity, Japanese Patent Application Laid-Open No. 11-090943 discloses an arbitrary transport length Lt (m) of the tenter. The ratio Lr = Ltt / Lt of the total length Ltt (m) in the conveying direction of the portion where the clip of the tenter having the same length as Lt holds the web is 1.0 ≦ Lr ≦ 1.99 The invention is described. Furthermore, as a preferable aspect, it is disclosed that the portion holding the web is arranged without a gap when viewed from the web width direction.

  Further, when introducing a web into a tenter, in order to improve flatness deterioration and instability due to web sagging, Japanese Patent Application Laid-Open No. 11-090944 discloses a plastic film manufacturing apparatus in front of a tenter entrance. Describes an invention having a sag suppressing device in the web width direction. Further, as a more preferable aspect, the sagging suppression device is a rotating roller that rotates in the direction range of 2 to 60 ° in the width direction, has an air intake device on the upper part of the web, and can blow air from under the web. Having a blower is also disclosed.

  In order to prevent deterioration of quality and sagging that hinders productivity, Japanese Patent Application Laid-Open No. 11-090945 discloses that a web peeled from a support has an angle with respect to the horizontal in the TAC manufacturing method. The invention to be introduced into the tenter is described.

  Moreover, in order to make a film having stable physical properties, JP 2000-289903 A discloses a transport apparatus that transports while applying tension in the width direction of the web when the peeled and solvent content is 50 to 12 wt%. A web width detecting means, a web holding means, and an invention that has two or more variable bending points, calculates the web width from the detection signal in the web width detection, and changes the position of the bending point are described. ing.

  Furthermore, in order to improve the clipping property, prevent web breakage for a long period of time, and obtain a film with excellent quality, Japanese Patent Application Laid-Open No. 2003-033933 discloses the right and left sides of the web on both the left and right sides near the entrance of the tenter. A web side edge curl prevention guide plate is disposed at least below the upper and lower side edges, and the web facing surface of the guide plate is arranged in the web conveying direction and the web. It is described that it comprises a contact metal part. As a further preferred embodiment, the web contact resin portion of the web facing surface of the guide plate is disposed on the upstream side in the web conveyance direction, the web contact metal portion is disposed on the downstream side, the web contact resin portion of the guide plate, and The level difference (including the inclination) between the web contact metal parts is within 500 μm, and the width of the guide plate web contact resin part and the web contact metal part contacting the web is 2 to 2, respectively. It is 150 mm, the distance of the web contact direction of the web contact resin part of the guide plate and the web contact metal part in the web conveyance direction is 5 to 120 mm, respectively, and the web contact resin part of the guide plate is made of metal. Provided by surface resin processing or resin coating on the guide substrate, the web contact resin part of the guide plate is made of a single resin, the left and right side edges of the web The distance between the web facing surfaces of the guide plates arranged above and below is 3 to 30 mm, and the distance between the web facing surfaces of the upper and lower guide plates at the left and right side edges of the web. In the width direction of the web and inward, it is enlarged at a rate of 2 mm or more per 100 mm width, and the upper and lower guide plates have a length of 10 to 300 mm at the left and right side edges of the web, respectively. And the upper and lower guide plates are arranged so as to be displaced back and forth along the web conveying direction, and the distance of the deviation between the upper and lower guide plates is −200 to +200 mm, the upper guide The web facing surface of the plate is made of only resin or metal, the web contact resin portion of the guide plate is made of Teflon (registered trademark), and the web contact metal portion is It is disclosed that the surface roughness of the web facing surface of the guide plate or the web contact resin portion and / or the web contact metal portion provided on the guide plate is 3 μm or less. Yes. Further, it is also described that the installation position of the upper and lower guide plates for preventing web side edge curl generation is preferably between the peeling side end portion of the support and the tenter introduction portion, and more preferably installed near the tenter entrance. Has been.

Japanese Patent Laid-Open No. 2002-036266, which is an invention for obtaining a high-quality thin TAC having a thickness of 20 to 85 μm, has, as a preferable aspect, tension acting on the web along the conveying direction before and after the tenter. The difference of 8 N / mm ² or less, after the peeling process, a preheating process for preheating the web, a stretching process for stretching the web using a tenter after the preheating process, and after the stretching process, And a relaxation step of relaxing (i.e., shrinking) the web by an amount smaller than the stretch amount in the stretching step.

  Furthermore, Japanese Patent Application Laid-Open No. 2002-225054, which aims to have a dry film thickness of 10 to 60 μm and excellent durability, describes a period until the residual solvent amount of the web reaches 10% by mass after peeling. In addition, gripping both ends of the web with clips, suppressing drying shrinkage by holding the width, and / or stretching in the width direction, the plane orientation represented by the formula S = {(Nx + Ny) / 2} -Nz Forming a film having a degree (S) of 0.0008 to 0.0020 (where Nx is the refractive index in the direction of highest refractive index in the plane of the film, and Ny is perpendicular to Nx in the plane) The refractive index in the direction, Nz is the refractive index in the film thickness direction of the film), the time from casting to peeling is set to 30 to 90 seconds, and the web after peeling is stretched in the width direction and / or the longitudinal direction. , Etc. are disclosed.

  Japanese Patent Application Laid-Open No. 2002-341144 discloses a solution casting method having a stretching process in which the mass concentration of the retardation increasing agent has a higher concentration distribution as it approaches the center in the film width direction in order to suppress optical unevenness. Are listed.

  Japanese Patent Laid-Open No. 2002-248639, which is an invention that reduces vertical and horizontal dimensional fluctuations during storage under high temperature and high humidity conditions, continuously casts a cellulose ester solution on a support. In the method for producing a film that is peeled and dried, the invention is such that the drying shrinkage satisfies the formula: 0 ≦ dry shrinkage (%) ≦ 0.1 × residual solvent amount (%) when peeling Are listed. Furthermore, as a preferred embodiment, when the residual solvent amount of the cellulose ester film after peeling is in the range of 40 to 100% by mass, at least the residual solvent amount is 30% by mass while holding both ends of the cellulose ester film by tenter conveyance. The amount of residual solvent at the tenter transport entrance of the cellulose ester film after peeling is 40 to 100% by mass, the amount of residual solvent at the exit is 4 to 20% by mass, and the cellulose ester film is transported by tenter transport. It is disclosed that the tension to be conveyed increases from the entrance to the exit of the tenter conveyance, the tension to convey the cellulose ester film by the tenter conveyance and the tension in the width direction of the cellulose ester film are substantially equal. Yes.

  In order to obtain a film having a thin film thickness and excellent optical isotropy and flatness, Japanese Patent Application Laid-Open No. 2000-239403 discloses a residual solvent ratio X at the time of peeling and a residual solvent at the time of introduction into a tenter. It is disclosed that film formation is performed with the relationship of the rate Y being in the range of 0.3X ≦ Y ≦ 0.9X.

  The optical film of the present invention may be manufactured by any manufacturing method, but is preferably manufactured by the above-described optical film manufacturing method.

The optical film of the present invention preferably has Re (550) in the range of 20 to 100 nm and Rth (550) in the range of 100 to 300 nm.
In particular, when used in a VA liquid crystal display device, when compensation is performed on one side of a liquid crystal cell, Re (550) is in the range of 40 to 100 nm, and Rth (550) is in the range of 160 to 300 nm. Preferably, Re (550) is 45 to 80 nm, and Rth (550) is more preferably 170 to 250 nm.

  On the other hand, when it is used on both sides of the liquid crystal cell of the liquid crystal display device for VA and compensated with two sheets, Re (550) is in the range of 20 to 100 nm and Rth (550) is in the range of 100 to 200 nm. Preferably, Re (550) is 25 to 80 nm, and Rth (550) is more preferably 100 to 150 nm.

  The polymer material mainly constituting the optical film of the present invention that satisfies the above characteristics will be specifically described below.

[Material of optical film]
As a material for forming the optical film of the present invention, a cellulose polymer represented by triacetyl cellulose (hereinafter referred to as cellulose acylate), which has been conventionally used as a transparent protective film for polarizing plates, can be preferably used. . Details of the cellulose acylate will be described below.

(Cellulose acylate)
As the raw material cotton of cellulose acylate, a known raw material can be used (for example, refer to the Japanese Society for Invention and Innovation 2001-1745). Cellulose acylate can also be synthesized by a known method (see, for example, Mita et al., Wood Chemistry pages 180-190 (Kyoritsu Shuppan, 1968)). The viscosity average polymerization degree of cellulose acylate is preferably 200 to 700, more preferably 250 to 500, and most preferably 250 to 350. The number average molecular weight (Mn) of the cellulose ester used in the present invention is preferably 10,000 to 150,000, the weight average molecular weight (Mw) is 20,000 to 500,000, and the Z average molecular weight (Mz) is preferably 5,000 to 550000. Moreover, it is preferable that molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight and Mn is a number average molecular weight) by gel permeation chromatography is narrow. The specific value of Mw / Mn is preferably 1.5 to 5.0, more preferably 2.0 to 4.5, and most preferably 3.0 to 4.0. preferable.

The acyl group of the cellulose acylate is not particularly limited, but an acetyl group, propionyl group, butyryl group or benzoyl group is preferably used. The substitution degree of all acyl groups is preferably 2.0 to 3.0, more preferably 2.2 to 2.95. In this specification, the substitution degree of an acyl group is a value calculated according to ASTM D817. When cellulose acetate whose acyl group is an acetyl group is used, the degree of acetylation is preferably 57.0 to 62.5%, and more preferably 58.0 to 62.0%. When the acetylation degree is within this range, Re does not become larger than a desired value due to the conveying tension during casting, there is little in-plane variation, and there is little change in retardation value due to temperature and humidity.
In particular, it is obtained by substituting the hydroxyl group of the glucose unit constituting the cellulose of the cellulose acylate film with an acyl group having 2 or more carbon atoms, and the substitution degree of the hydroxyl group at the 2-position of the glucose unit with the acyl group is DS2, 3-position. When the substitution degree of the hydroxyl group of the hydroxyl group with DS3 is DS3 and the substitution degree of the hydroxyl group of the 6-position with DS6 is DS6, if the following formulas (IV) and (V) are satisfied, desired Re and Rth can be obtained. This is preferable because the change in the Re value due to temperature and humidity becomes smaller.

Formula (IV): 2.0 ≦ (DS2 + DS3 + DS6) ≦ 3.0
Formula (V): DS6 / (DS2 + DS3 + DS6) ≧ 0.315

A more preferred range is
Formula (IV-1): 2.2 ≦ (DS2 + DS3 + DS6) ≦ 2.9
Formula (V-1): DS6 / (DS2 + DS3 + DS6) ≧ 0.322
It is.

  Or, in particular, when the degree of substitution of the hydroxyl group of the glucose unit of cellulose acylate with an acetyl group is A, and the degree of substitution with a propionyl group, butyryl group or benzoyl group is B, A and B are represented by the formulas (VI) and (VII): When it is satisfied, it becomes easy to obtain desired Re and Rth, and it is easy to realize a high draw ratio without breaking, which is preferable.

Formula (VI): 2.0 ≦ A + B ≦ 3.0
Formula (VII): 0 <B

A more preferred range is
Formula (VI-1): 2.6 <= A + B <= 3.0
Formula (VII-1): 0.5 ≦ B ≦ 1.5
It is.

(Polymers other than cellulose acylate)
According to the present invention, the method for obtaining a film having preferable optical properties by a production method including a stretching step for stretching a film and a shrinking step for shrinking is not limited to cellulose acylate, and polymers that can be used as an optical film in general. The same effect as cellulose acylate can be expected.
Examples of polymers that can be used as these optical films include polycarbonate copolymers and polymer resins having a cyclic olefin structure.

  Examples of the polycarbonate copolymer include a repeating unit represented by the following general formula (A) and a repeating unit represented by the following general formula (B), and the repeating unit represented by the following general formula (A) is the whole. Polycarbonate copolymer occupying 80-30 mol% is mentioned.

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

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

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

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

  The polycarbonate copolymer is preferably a polycarbonate copolymer comprising 30 to 60 mol% of repeating units represented by the following general formula (C) and 70 to 40 mol% of repeating units represented by the following general formula (D). .

  More preferably, it is a polycarbonate copolymer composed of 45 to 55 mol% of the repeating unit represented by the general formula (C) and 55 to 45 mol% of the repeating unit represented by the general formula (D).

In the general formula (C), R _{26 to} R ₂₇ are each independently a hydrogen atom or a methyl group, and preferably a methyl group from the viewpoint of handleability.

In the general formula (D), R _{28 to} R ₂₉ are each independently a hydrogen atom or a methyl group, and a hydrogen atom is preferable from the viewpoints of economy and film characteristics.

  The optical film in the present invention is preferably one using the above-described polycarbonate copolymer having a fluorene skeleton. Examples of the polycarbonate copolymer having a fluorene skeleton include blends of polycarbonate copolymers having different composition ratios composed of the repeating unit represented by the general formula (A) and the repeating unit represented by the general formula (B). The content of the general formula (A) is preferably 80 to 30 mol%, more preferably 75 to 35 mol%, still more preferably 70 to 40 mol% of the entire polycarbonate copolymer.

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

  Here, the molar ratio can be determined by, for example, a nuclear magnetic resonance (NMR) apparatus over the entire polycarbonate bulk constituting the optical film.

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

  The intrinsic viscosity of the polycarbonate copolymer is preferably 0.3 to 2.0 dl / g. If it is less than 0.3, there is a problem that it becomes brittle and the mechanical strength cannot be maintained. There is a problem of becoming.

The optical film of the present invention may be a composition (blend) of the polycarbonate copolymer and other polymer compounds. In this case, since the polymer compound needs to be optically transparent, it is preferable that the polymer compound is compatible with the polycarbonate copolymer, or the refractive index of each polymer is substantially equal. Specific examples of the other polymer include poly (styrene-co-maleic anhydride), and the composition ratio of the polycarbonate copolymer to the polymer compound is 80 to 30% by mass of the polycarbonate copolymer. The polymer compound body is 20 to 70 mass%, preferably the polycarbonate copolymer is 80 to 40 mass%, and the polymer compound body is 20 to 60 mass%. Also in the case of a blend, two or more kinds of repeating units of the polycarbonate copolymer may be combined. In the case of a blend, a compatible blend is preferable, but even if the blend is not completely compatible, the light scattering between the components can be suppressed and the transparency can be improved by adjusting the refractive index between the components. In addition, a blend body may combine 3 or more types of materials, and can combine multiple types of polycarbonate copolymer and another high molecular compound.
The weight average molecular weight of the polycarbonate copolymer is 1,000 to 1,000,000, preferably 5,000 to 500,000. The mass average molecular weight of the other polymer compound is 500 to 100,000, preferably 1,000 to 50,000.

  Examples of a polymer resin having a cyclic olefin structure (hereinafter also referred to as “cyclic polyolefin resin” or “cyclic polyolefin”) include (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) Polymers of cyclic conjugated dienes, (4) vinyl alicyclic hydrocarbon polymers, and hydrides of (1) to (4). Preferred polymers for the present invention are addition (co) polymer cyclic polyolefins containing at least one repeating unit represented by the following general formula (II), and if necessary, a repeating unit represented by the general formula (I) An addition (co) polymer cyclic polyolefin further comprising at least one of the above. Further, addition (co) polymers (including ring-opening (co) polymers) containing at least one cyclic repeating unit represented by the general formula (III) can also be suitably used. The addition (co) polymer cyclic further comprising at least one repeating unit represented by the general formula (III) and, if necessary, at least one repeating unit represented by the general formula (I). Polyolefins can also be preferably used.

In formula, m represents the integer of 0-4. R ^{1 to} R ⁶ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, X ^{1 to} X ³ and Y ^{1 to} Y ³ are hydrogen atoms, hydrocarbon groups having 1 to 10 carbon atoms, halogen atoms, halogen atoms in substituted hydrocarbon group having 1 to 10 carbon _{atoms, - (CH 2) n COOR} 11, - (CH 2) n OCOR 12, - (CH 2) n NCO, - (CH 2) n NO 2, - _{(CH 2) n CN, -} (CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ, - (CH 2) n W or X ¹ and Y, ¹ , (—CO) ₂ O, (—CO) ₂ NR ¹⁵ composed of X ² and Y ² or X ³ and Y ³ is shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ are hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with halogen, and W is 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 polarizable large functional group in a substituent ^{X 1 ~X 3, Y 1 ~Y} 3, by increasing the thickness-direction retardation of the optical film (Rth), in-plane retardation (Re) The expression can be increased. A film having a high Re developability can increase the Re value by stretching in the film forming process.
Norbornene-based addition (co) polymers are disclosed in JP-A No. 10-7732, JP-T 2002-504184, US2004229157A1, or WO2004 / 070463A1. It can be obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and conjugated dienes such as ethylene, propylene, butene, butadiene and isoprene; non-conjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. This norbornene-based addition (co) polymer is sold under the name of Apel by Mitsui Chemicals, Inc., and has different glass transition temperatures (Tg) such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C) or APL6015T ( Grades such as Tg145 ° C). Pellets such as TOPAS 8007, 6013 and 6015 are sold by Polyplastics Co., Ltd. Further, Appear 3000 is sold by Ferrania.

Norbornene-based polymer hydrides are disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-159767, or JP-A-2004-309799. As disclosed in No. 1, etc., the polycyclic unsaturated compound is made by addition polymerization or metathesis ring-opening polymerization and then hydrogenation. In the norbornene-based polymer used in the present invention, R ^{5 to} R ⁶ are preferably a hydrogen atom or —CH ₃ , X ³ and Y ³ are preferably a hydrogen atom, Cl, —COOCH ₃ , and other groups are appropriately selected. The This norbornene-based resin is sold under the trade name Arton G or Arton F by JSR Corporation, and from Zeon Corporation Zeonor ZF14, ZF16, Zeonex 250 or Zeonex. They are commercially available under the trade name 280 and can be used.

(Retardation expression agent)
The optical film of the present invention preferably contains a retardation developer.

(A) Re control method;
In order to control the absolute value of Re of the optical film of the present invention, a compound having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution is preferably used as the retardation enhancer. By using such a compound, the absolute value can be controlled without substantially changing the wavelength dependency of Re in the visible region.
The above-mentioned “retardation agent” is an optical film having a wavelength of 550 nm, which is produced in the same manner except that Re measured by light having a wavelength of 550 nm of an optical film containing an additive does not contain the additive. Means an “additive” that is 20 nm or more higher than Re measured in (when converted to a film thickness of 80 μm). The increase in Re is preferably 30 nm or more, more preferably 40 nm or more, and most preferably 60 nm or more.
From the viewpoint of the function of the retardation enhancer, a rod-like compound is preferable, preferably has at least one aromatic ring, and more preferably has at least two aromatic rings.

  The rod-like compound preferably has a linear molecular structure. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that the angle of the molecular structure is 140 degrees or more in the thermodynamically most stable structure obtained by calculation as described above.

The rod-shaped compound preferably exhibits liquid crystallinity. More preferably, the rod-like compound exhibits liquid crystallinity upon heating (has thermotropic liquid crystallinity). The liquid crystal phase is preferably a nematic phase or a smectic phase.
Preferred compounds are described in JP-A-2004-4550, but are not limited thereto. Maximum absorption wavelength (λmax) in the ultraviolet absorption spectrum of the solution
Two or more rod-shaped compounds having a wavelength shorter than 250 nm may be used in combination.

  The rod-like compound can be synthesized with reference to methods described in literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 (1975), Tetrahedron, 48, 16, 1637 (1992).

  When the cellulose acylate is used as a raw material, the retardation developer is preferably added in an amount of 0.1 to 30% by mass, and preferably 0.5 to 20% by mass of the cellulose acylate. Is more preferable.

(B) Rth control method;
In order to express desired Rth, it is preferable to use a retardation developer.
The term “retardation enhancer” as used herein means that Rth measured at a wavelength of 550 nm of an optical film containing an additive is Rth measured at a wavelength of 550 nm of an optical film produced in exactly the same manner except that the additive is not included. Means an “additive” that is 20 nm or more higher (when converted to a film thickness of 80 μm). The increase in Rth is preferably 30 nm or more, more preferably 40 nm or more, and most preferably 60 nm or more.

The retardation developer is preferably a compound having at least two aromatic rings. Two or more types of retardation developing agents may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.
The retardation enhancer that controls Rth preferably does not affect Re expressed by stretching, and a discotic compound is preferably used.
The discotic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring, and the aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.
The aromatic compound is used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of cellulose acylate when cellulose acylate is used as a raw material. The aromatic compound is preferably used in the range of 0.05 to 15 parts by mass, more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the cellulose acylate. Two or more compounds may be used in combination.

(C) Method for controlling Rth; method using optically anisotropic layer As a method for controlling Rth without affecting Re expressed by stretching, a method of coating an optically anisotropic layer such as a liquid crystal layer is preferably used. It is done.
As a specific example of the liquid crystal layer, a method of aligning the discotic liquid crystal so that the angle between the disc surface and the optical film surface is within 5 degrees (Japanese Patent Laid-Open No. 10-312166), A method of aligning the major axis and the above-mentioned optical film surface to be within 5 degrees (Japanese Patent Laid-Open No. 2000-304932) can be mentioned.

  An optical film having an optically anisotropic layer (also referred to as an optical compensation film) is used to increase the viewing angle contrast of a liquid crystal display device, particularly an OCB mode or VA mode liquid crystal display device, and to reduce color shift depending on the viewing angle. Contribute. The optical compensation film may be disposed between the observer-side polarizing plate and the liquid crystal cell, may be disposed between the back-side polarizing plate and the liquid crystal cell, or may be disposed on both. For example, it can be incorporated into the liquid crystal display device as an independent member, or a protective film that protects the polarizing film can be provided with optical characteristics and function as a transparent film. It can also be incorporated inside the display device. An alignment film for controlling the alignment of the liquid crystalline compound in the optical anisotropic layer may be provided between the optical film and the optical anisotropic layer. Moreover, as long as the optical characteristic mentioned later is satisfy | filled, this optical film and an optically anisotropic layer may each consist of two or more layers. Hereinafter, the case where a cellulose acylate film is used as the optical film will be described in more detail with respect to the optical anisotropic layer.

[Optically anisotropic layer]
The optically anisotropic layer may be directly formed on the surface of the cellulose acylate film, or may be formed on the alignment film by forming an alignment film on the cellulose acylate film. It is also possible to transfer a liquid crystalline compound layer formed on another substrate onto a cellulose acylate film using an adhesive, an adhesive, or the like.
Examples of the liquid crystalline compound used for forming the optically anisotropic layer include a rod-like liquid crystalline compound and a discotic liquid crystalline compound (hereinafter, the discotic liquid crystalline compound may be referred to as a “discotic liquid crystalline compound”). The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal. Further, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity. For example, when a low-molecular liquid crystalline compound is used for the production of the optically anisotropic layer, the optically anisotropic layer In the process of forming, the compound may be cross-linked and no longer exhibits liquid crystallinity.

(Bar-shaped liquid crystalline compound)
Examples of the rod-like liquid crystalline compound that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyano-substituted phenylpyrimidines. Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. The rod-like liquid crystalline compound includes a metal complex. A liquid crystal polymer containing a rod-like liquid crystal compound in a repeating unit can also be used. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline compounds, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemical Review Vol. 22 Liquid Crystal Chemistry (1994) edited by the Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.

The birefringence of the rod-like liquid crystalline compound used in the present invention is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  The discotic liquid crystalline compound exhibits liquid crystallinity with a structure in which a linear alkyl group, an alkoxy group or a substituted benzoyloxy group is radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. Also included are compounds. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.

  As described above, when an optically anisotropic layer is formed from a liquid crystalline compound, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity. For example, a low-molecular discotic liquid crystalline compound has a group that reacts with heat or light, and the group reacts with heat or light to polymerize or crosslink to increase the molecular weight. When a layer is formed, the compound contained in the optically anisotropic layer may no longer have liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, it is preferable to introduce a linking group between the discotic core and the polymerizable group.

  In the present invention, in the optically anisotropic layer, the molecules of the rod-like compound or the discotic compound are fixed in an oriented state. The orientation average direction of the molecular symmetry axis of the liquid crystal compound at the interface on the optical film side has an intersection angle with the slow axis in the plane of the optical film of about 45 degrees. In this specification, “approximately 45 °” refers to an angle in the range of 45 ° ± 5 °, preferably 42 to 48 °, and more preferably 43 to 47 °.

The orientation average direction of the molecular symmetry axis of the liquid crystal compound can be generally adjusted by selecting a material of the liquid crystal compound or the alignment film or by selecting a rubbing treatment method.
In the present invention, for example, in the case of producing an optical compensation film for the OCB method, an alignment film for forming an optically anisotropic layer is produced by rubbing treatment, and in the direction of 45 ° with respect to the slow axis of the cellulose acylate film. By rubbing, an optically anisotropic layer in which the orientation average direction of the molecular symmetry axis of the liquid crystalline compound at least at the cellulose acylate film interface is 45 ° with respect to the slow axis of the cellulose acylate film is formed. be able to.
For example, the optical compensation film can be continuously produced by using a long cellulose acylate film whose slow axis is perpendicular to the longitudinal direction. Specifically, a coating solution for forming an alignment film is continuously applied to the surface of the long cellulose acylate film to prepare a film, and then the surface of the film is continuously 45 ° in the longitudinal direction. Then, an alignment film is produced by rubbing in the direction of, and an optically anisotropic layer-forming coating solution containing a liquid crystalline compound is continuously applied on the prepared alignment film, and the molecules of the liquid crystalline compound are dispersed. By aligning and fixing in that state, an optically anisotropic layer can be produced, and a long optical compensation film can be produced continuously. The optical compensation film produced in a long shape is cut into a desired shape before being incorporated into the liquid crystal display device.

  In addition, with respect to the orientation average direction of the molecular symmetry axis on the surface side (air side) of the liquid crystalline compound, the orientation average direction of the molecular symmetry axis of the liquid crystalline compound on the air interface side is relative to the slow axis of the cellulose acylate film. It is preferably about 45 °, more preferably 42 to 48 °, and even more preferably 43 to 47 °. In general, the orientation average direction of the molecular symmetry axis of the liquid crystal compound on the air interface side can be adjusted by selecting the type of the liquid crystal compound or the additive used together with the liquid crystal compound. Examples of the additive used together with the liquid crystal compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. Similarly to the above, the degree of change in the orientation direction of the molecular symmetry axis can be adjusted by selecting the liquid crystal compound and the additive. In particular, regarding the surfactant, it is preferable that the surface tension control of the coating solution is compatible.

  The plasticizer, surfactant and polymerizable monomer used together with the liquid crystal compound are compatible with the discotic liquid crystal compound and may change the tilt angle of the liquid crystal compound or do not inhibit the alignment. preferable. A polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) is preferred. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the liquid crystal compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, the adhesion between the alignment film and the optically anisotropic layer can be improved.

When a discotic liquid crystalline compound is used as the liquid crystalline compound, it is preferable to use a polymer that has a certain degree of compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound.
A cellulose ester can be mentioned as an example of a polymer. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate. In order not to inhibit the orientation of the discotic liquid crystalline compound, the amount of the polymer added is preferably in the range of 0.1 to 10% by mass, preferably 0.1 to 8% by mass with respect to the discotic liquid crystalline compound. More preferably, it is in the range of 0.1 to 5% by mass.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

  In the present invention, Re (550) of the optically anisotropic layer is preferably 0 to 300 nm, more preferably 0 to 200 nm, and further preferably 0 to 100 nm. Rth (550) in the film thickness direction of the optically anisotropic layer is preferably 20 to 400 nm, and more preferably 50 to 200 nm. The thickness of the optically anisotropic layer is preferably 0.1 to 20 microns, more preferably 0.5 to 15 microns, and most preferably 1 to 10 microns.

  The cellulose acylate film preferably used in the present invention can be obtained by forming a film using a solution obtained by dissolving the cellulose acylate and, if necessary, an additive in an organic solvent.

〔Additive〕
Examples of the additive that can be used in the cellulose acylate solution in the present invention include a plasticizer, an ultraviolet absorber, a deterioration preventing agent, a retardation (optical anisotropy) developing agent, and a retardation (optical anisotropy). Examples thereof include a reducing agent, a wavelength dispersion adjusting agent, a dye, fine particles, a peeling accelerator, and an infrared absorber.
In the present invention, it is preferable to use a retardation developer. Moreover, it is preferable to use at least one of a plasticizer, an ultraviolet absorber and a peeling accelerator.

  They may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, a UV absorber having a melting point of 20 ° C. or lower and a melting point of 20 ° C. or higher can be used in combination, or a plasticizer can be used in the same manner, as described in, for example, JP-A-2001-151901. ing.

[Ultraviolet absorber]
As the ultraviolet absorber, any type can be selected according to the purpose, and a salicylic acid ester-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex-based absorber or the like is used. Preferred are benzophenone series, benzotriazole series, and salicylic acid ester series.

  Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone.

  As a benzotriazole ultraviolet absorber, 2 (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2 (2′-hydroxy-5′-t-butylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5 Examples include chlorobenzotriazole, 2 (2′-hydroxy-5′-t-octylphenyl) benzotriazole, and the like.

  Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate.

  Among these exemplified ultraviolet absorbers, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2 (2′-hydroxy-3′-t-butyl- 5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-t-amylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole is particularly preferred.

  As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. The ultraviolet absorbent for liquid crystal is preferably one that is excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal and that has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Particularly preferred ultraviolet absorbers are the benzotriazole compounds, benzophenone compounds, and salicylic acid ester compounds mentioned above. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.

  As for the UV absorber, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-2000-204173 These compounds can also be used.

  0.001-5 mass% is preferable with respect to a cellulose acylate, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass% is more preferable. If the addition amount is 0.001% by mass or more, the effect of addition can be sufficiently exerted, and if the addition amount is 5% by mass or less, it is preferable because bleeding out of the ultraviolet absorber to the film surface can be suppressed.

  Further, the ultraviolet absorber may be added simultaneously with dissolution of cellulose acylate, or may be added to the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable because spectral absorption characteristics can be easily adjusted.

[Deterioration inhibitor]
The deterioration inhibitor can prevent cellulose triacetate and the like from deteriorating and decomposing. Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenone-based compounds. There are compounds such as UV absorbers (JP-A-6-118233).

[Plasticizer]
The plasticizer is preferably a phosphate ester or a carboxylic acid ester. Examples of the phosphate ester plasticizer include triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate and the like; Examples of the acid ester plasticizer include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), diethyl hexyl phthalate (DEHP), O-acetyl citrate. Acid triethyl (OACTE), O-acetyl tributyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate, oleic acid , Methyl ricinoleate, dibutyl sebacate, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc. The plasticizer used in the invention is more preferably selected from these exemplified plasticizers. Furthermore, the plasticizer is preferably (di) pentaerythritol esters, glycerol esters, diglycerol esters.

[Peeling accelerator]
Examples of the peeling accelerator include citric acid ethyl esters.

[Infrared absorber]
Furthermore, as an infrared absorber, it describes in Unexamined-Japanese-Patent No. 2001-194522, for example.

[Time of addition, etc.]
These additives may be added at any time in the dope preparation step, but may be added to the final preparation step of the dope preparation step by adding an additive preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is exhibited.

  Moreover, when a cellulose acylate film is a multilayer, the kind and addition amount of the additive of each layer may differ. For example, although described in Japanese Patent Application Laid-Open No. 2001-151902, these are conventionally known techniques.

  The glass transition point Tg measured by a dynamic viscoelasticity measuring device “Vibron: DVA-225” {manufactured by IT Measurement Control Co., Ltd.}} of a cellulose acylate film is selected by selecting the type and amount of these additives. It is preferable to set the elastic modulus measured at ˜150 ° C. with a tensile tester “Strograph-R2” {manufactured by Toyo Seiki Seisakusho} to 1500 to 4000 MPa. More preferably, the glass transition point Tg is 80 to 135 ° C. and the elastic modulus is 1500 to 3000 MPa. That is, the cellulose acylate film preferably used in the present invention preferably has a glass transition point Tg and an elastic modulus within the above ranges from the viewpoint of process suitability for polarizing plate processing and liquid crystal display device assembly.

  Furthermore, regarding the additive, the Japan Society of Invention and Innovation Technical Bulletin No. 2001-1745 (issued March 15, 2001, Japan Society of Invention) p. Those described in detail after 16 can be used as appropriate.

[Retardation reducing agent]
The retardation reducing agent used for reducing the optical anisotropy of the cellulose acylate film will be described.
Using a compound that suppresses the cellulose acylate in the film from being oriented in the plane and in the film thickness direction, the optical anisotropy is sufficiently reduced, and Re and Rth can be made zero or close to zero. it can. For this purpose, it is advantageous that the compound that lowers the optical anisotropy is sufficiently compatible with cellulose acylate, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

  The addition amount of the compound that decreases the optical anisotropy is preferably 0.01 to 30% by mass of the cellulose acylate, more preferably 1 to 25% by mass, and 5 to 20% by mass. Is particularly preferred.

  The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.

[dye]
In the present invention, a dye for adjusting the hue may be added. The content of the dye is preferably 10 to 1000 ppm, more preferably 50 to 500 ppm in terms of a mass ratio with respect to cellulose acylate. By containing the dye in this way, light piping of the cellulose acylate film can be reduced, and yellowness can be improved. These compounds may be added together with cellulose acylate and a solvent during the preparation of the cellulose acylate solution, or may be added during or after the solution preparation. Moreover, you may add to the ultraviolet absorber liquid added in-line. The dyes described in JP-A-5-34858 can be used.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose acylate film preferably used in the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Mention may be made of calcium phosphate. As the fine particles, those containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / L or more, and more preferably 100 to 200 g / L or more. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

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

  These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, but are present as aggregates of primary particles in the film, and 0.1 to 3.0 μm on the film surface. Form irregularities. The average particle diameter of the secondary particles is preferably from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. If the average particle diameter is 1.5 μm or less, the haze will not be too strong, and if it is 0.2 μm or more, the effect of preventing squeezing will be sufficiently exhibited, which is preferable.

  The primary and secondary particle diameters of the fine particles are determined by observing the particles in the film with a scanning electron microscope and using the diameter of a circle circumscribing the particles as the particle diameter. Also, 200 particles are observed at different locations, and the average value is taken as the average particle diameter.

  As the fine particles of silicon dioxide, for example, commercially available products such as “Aerosil” R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 {above, manufactured by Nippon Aerosil Co., Ltd.} can be used. . Zirconium oxide fine particles are commercially available under the trade names of “Aerosil” R976 and R811 {above, Nippon Aerosil Co., Ltd.}, and can be used.

  Among these, “Aerosil 200V” and “Aerosil R972V” are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more, and the turbidity of the optical film is low. This is particularly preferable because the effect of reducing the coefficient of friction is large while maintaining it.

In the present invention, in order to obtain a cellulose acylate film containing particles having a small secondary average particle size, several methods are conceivable when preparing a dispersion of fine particles. For example, a fine particle dispersion in which a solvent and fine particles are stirred and mixed is prepared in advance, and this fine particle dispersion is added to a small amount of separately prepared cellulose acylate solution and dissolved by stirring, and further mixed with the main cellulose acylate dope solution. There is a way. This method is a preferred preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, a small amount of cellulose ester is added to the solvent and dissolved by stirring. Then, the fine particles are added to the solvent and dispersed with a disperser to make the fine particle additive solution. There is also a way to do it. In the present invention, although not limited to these methods, the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, and 10 to 25% by mass. Is more preferable, and 15 to 20% by mass is most preferable.
A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film formation of a cellulose ester.

  Next, the organic solvent in which cellulose acylate preferably used in the present invention is dissolved will be described.

  In the present invention, as the organic solvent, any of a chlorinated solvent containing a chlorinated organic solvent as a main solvent and a non-chlorinated solvent not containing a chlorinated organic solvent can be used.

[Chlorine solvent]
In preparing the cellulose acylate solution preferably used in the present invention, a chlorinated organic solvent is preferably used as the main solvent. In the present invention, the type of the chlorinated organic solvent is not particularly limited as long as the object can be achieved as long as the cellulose acylate is dissolved and can be cast and formed into a film. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is preferable to use at least 50% by mass of dichloromethane in the total amount of the organic solvent.

Other organic solvents used in combination with the chlorinated organic solvent in the present invention are described below.
That is, as another preferable organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. The ester, ketone, ether and alcohol may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. You may have a functional group simultaneously. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The alcohol used in combination with the chlorinated organic solvent may preferably be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.

Examples of combinations of chlorinated organic solvents and other organic solvents include the following compositions, but are not limited thereto.
Dichloromethane / methanol / ethanol / butanol = 80/10/5/5 (parts by mass)
Dichloromethane / acetone / methanol / propanol = 80/10/5/5 (parts by mass)
Dichloromethane / methanol / butanol / cyclohexane = 80/10/5/5 (parts by mass)
Dichloromethane / methyl ethyl ketone / methanol / butanol = 80/10/5/5 (parts by mass)
Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol = 75/8/5/5/7 (parts by mass)
Dichloromethane / cyclopentanone / methanol / isopropanol = 80/7/5/8 (parts by mass)
Dichloromethane / methyl acetate / butanol = 80/10/10 (parts by mass)
Dichloromethane / cyclohexanone / methanol / hexane = 70/20/5/5 (parts by mass),
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol = 50/20/20/5/5 (parts by mass),
Dichloromethane / 1, 3 dioxolane / methanol / ethanol = 70/20/5/5 (parts by mass),
Dichloromethane / dioxane / acetone / methanol / ethanol = 60/20/10/5/5 (parts by mass),
Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane = 65/10/10/5/5/5 (parts by mass)
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol = 70/10/10/5/5 (parts by mass),
Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane = 65/10/10/5/5/5 (parts by mass)
Dichloromethane / methyl acetoacetate / methanol / ethanol = 65/20/10/5 (parts by mass),
Dichloromethane / cyclopentanone / ethanol / butanol = 65/20/10/5 (parts by mass).

[Non-chlorine solvents]
Next, a non-chlorine organic solvent that is preferably used in preparing a cellulose acylate solution that is preferably used in the present invention will be described. In the present invention, the non-chlorine organic solvent is not particularly limited as long as the object can be achieved as long as the cellulose acylate is dissolved and can be cast and formed into a film. The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone and methyl acetyl acetate. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

The above-mentioned non-chlorine organic solvent used for cellulose acylate is selected from the various viewpoints described above, and is preferably as follows.
That is, the non-chlorine solvent is preferably a mixed solvent containing the non-chlorine organic solvent as a main solvent, and is a mixed solvent of three or more different solvents, wherein the first solvent is methyl acetate, ethyl acetate, At least one selected from methyl formate, ethyl formate, acetone, dioxolane, and dioxane, or a mixture thereof, wherein the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate, The solvent is a mixed solvent selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, more preferably alcohols having 1 to 8 carbon atoms. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may not be provided. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, or methyl acetyl acetate. It may be a solvent.

  The alcohol as the third solvent may have a hydrocarbon chain that is linear, branched, or cyclic, and among them, a saturated aliphatic hydrocarbon chain is preferable. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. In addition, as the alcohol, a fluorine-based alcohol in which part or all of the hydrogen in the hydrocarbon chain is substituted with fluorine is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like.

  Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.

  These alcohols and hydrocarbons as the third solvent may be used alone or in a mixture of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, and hydrocarbons such as cyclohexane and hexane. Particularly preferred are methanol, ethanol, 1-propanol, 2-propanol and 1-butanol.

  The mixing ratio of the above three types of mixed solvents is that the first solvent is 20 to 95% by mass, the second solvent is 2 to 60% by mass, and the third solvent is 2 to 30% by mass in the total amount of the mixed solvent. %, Preferably the first solvent is 30 to 90% by mass, the second solvent is 3 to 50% by mass, and the third alcohol is 3 to 25% by mass. preferable. In particular, the first solvent is preferably 30 to 90% by mass, the second solvent is preferably 3 to 30% by mass, and the third solvent is an alcohol, and preferably 3 to 15% by mass.

  The non-chlorine-based organic solvent used in the present invention described above is more specifically described in JIII Journal of Technical Disclosure No. 2001-1745 (issued March 15, 2001, Invention Association) p. 12-16.

Preferred combinations of non-chlorine organic solvents of the present invention can include the following, but are not limited thereto.
Methyl acetate / acetone / methanol / ethanol / butanol = 75/10/5/5/5 (parts by mass),
Methyl acetate / acetone / methanol / ethanol / propanol = 75/10/5/5/5 (parts by mass),
Methyl acetate / acetone / methanol / butanol / cyclohexane = 75/10/5/5/5 (parts by mass),
Methyl acetate / acetone / ethanol / butanol = 81/8/7/4 (parts by mass)
Methyl acetate / acetone / ethanol / butanol = 82/10/4/4 (parts by mass),
Methyl acetate / acetone / ethanol / butanol = 80/10/4/6 (parts by mass)
Methyl acetate / methyl ethyl ketone / methanol / butanol = 80/10/5/5 (parts by mass),
Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol = 75/8/5/5/7 (parts by mass),
Methyl acetate / cyclopentanone / methanol / isopropanol = 80/7/5/8 (parts by mass),
Methyl acetate / acetone / butanol = 85/10/5 (parts by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol = 60/15/14/5/6 (parts by mass),
Methyl acetate / cyclohexanone / methanol / hexane = 70/20/5/5 (parts by mass),
Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol = 50/20/20/5/5 (parts by mass),
Methyl acetate / 1,3-dioxolane / methanol / ethanol = 70/20/5/5 (parts by mass),
Methyl acetate / dioxane / acetone / methanol / ethanol = 60/20/10/5/5 (parts by mass),
Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane = 65/10/10/5/5/5 (parts by mass),

Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol = 50/20/20/5/5 (parts by mass),
Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane = 65/10/10/5/5/5 (parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol = 65/20/10/5 (parts by mass),
Acetone / cyclopentanone / ethanol / butanol = 65/20/10/5 (parts by mass),
Acetone / 1,3-dioxolane / ethanol / butanol = 65/20/10/5 (parts by mass),
1,3-dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol = 55/20/10/5/5/5 (parts by mass)
And so on.

Furthermore, a cellulose acylate solution prepared by the following method can also be used.
A method of preparing a cellulose acylate solution with methyl acetate / acetone / ethanol / butanol = 81/8/7/4 (parts by mass), adding 2 parts by mass of butanol after filtration and concentration,
A method of preparing a cellulose acylate solution with methyl acetate / acetone / ethanol / butanol = 84/10/4/2 (parts by mass), adding 4 parts by mass of butanol after filtration and concentration,
A method of preparing a cellulose acylate solution with methyl acetate / acetone / ethanol = 84/10/6 (parts by mass), and adding 5 parts by mass of butanol after filtration and concentration.

  In addition to the non-chlorine organic solvent of the present invention, the dope used in the present invention may contain dichloromethane in an amount of 10% by mass or less based on the total amount of the organic solvent of the present invention.

[Characteristics of cellulose acylate solution]
The cellulose acylate solution is a solution in which cellulose acylate is dissolved in the organic solvent, and the concentration thereof is preferably in the range of 10 to 30% by mass from the viewpoint of film-forming casting suitability, more preferably. It is 13-27 mass%, Most preferably, it is 15-25 mass%.
A method for bringing the cellulose acylate solution into such a concentration range may be a predetermined concentration at the stage of dissolution, and will be described later after it is prepared in advance as a low concentration solution (for example, 9 to 14% by mass). You may adjust to a predetermined high concentration solution by a concentration process. Furthermore, after preparing a high concentration cellulose acylate solution in advance, various additives may be added to obtain a predetermined low concentration cellulose acylate solution, and any method is preferably used in the present invention. There is no particular problem if the concentration is carried out.

Next, in the present invention, the aggregate molecular weight of the cellulose acylate in the diluted solution when the cellulose acylate solution is 0.1 to 5% by mass with an organic solvent having the same composition is 150,000 to 15 million. Is preferable from the viewpoint of solubility in a solvent. The associated molecular weight is more preferably 180,000 to 9 million. This associated molecular weight can be determined by a static light scattering method. In that case, it is preferable to melt | dissolve so that the inertial radius calculated | required simultaneously may be 10-200 nm. A more preferable radius of inertia is 20 to 200 nm. Furthermore, it is preferable to dissolve so that the second virial coefficient is −2 × 10 ⁻⁴ to + 4 × 10 ^−4, and more preferably, the second virial coefficient is −2 × 10 ⁻⁴ to + 2 × 10 ^−4. It is.

  Here, the definition of the associated molecular weight, the radius of inertia, and the second virial coefficient in the present invention will be described. These are measured using the static light scattering method according to the following method. Although the measurement is performed in a dilute region for the convenience of the apparatus, these measured values reflect the behavior of the dope in the high concentration region of the present invention.

  First, cellulose acylate is dissolved in a solvent used for the dope to prepare solutions of 0.1 mass%, 0.2 mass%, 0.3 mass%, and 0.4 mass%. In order to prevent moisture absorption, the cellulose acylate is dried at 120 ° C. for 2 hours, and is measured at 25 ° C. and 10% RH. The dissolution method is carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method). Subsequently, these solutions and the solvent are filtered through a 0.2 μm Teflon filter. Then, static light scattering of the filtered solution is measured at 10 ° intervals from 30 ° to 140 ° at 25 ° C. using a light scattering measuring device “DLS-700” (manufactured by Otsuka Electronics Co., Ltd.). The obtained data is analyzed by the BERRY plot method. The refractive index necessary for this analysis is the value of the solvent determined by the Abbe refractive system, and the refractive index concentration gradient (dn / dc) is a differential refractometer “DRM-1021” {manufactured by Otsuka Electronics Co., Ltd. }, And using the solvent and solution used for the light scattering measurement.

[Preparation of dope]
Next, preparation of a solution (dope) for casting / film-forming cellulose acylate will be described.
The method for dissolving cellulose acylate is not particularly limited, and may be a room temperature dissolution method, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special JP-A-2000-273184, JP-A-11-323017, JP-A-11-302388, and the like describe the methods for preparing a cellulose acylate solution.

  The above-described method for dissolving cellulose acylate in an organic solvent can be applied to the present invention even within the scope of the present invention. For details on these, especially non-chlorine solvent systems, the Japan Society for Invention and Innovation, Publication No. 2001-1745 (issued March 15, 2001, Japan Society for Invention) p. 22-25, which can be carried out according to that method. Further, the cellulose acylate dope solution preferably used in the present invention is usually subjected to solution concentration and filtration, and these are similarly applied to the Japan Institute of Invention and Technology Publication No. 2001-1745 (March 2001). Issued on the 15th, Invention Association) p. 25 in detail. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it carries out in a pressurized state.

  It is preferable that the cellulose acylate solution has a viscosity and a dynamic storage elastic modulus within the ranges described below because it is easy to cast. These values are measured using 1 mL of the sample solution in a rheometer “CLS 500” and “Steel Cone” (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °. Measurement conditions were measured by varying the range from 40 ° C to -10 ° C at 2 ° C / min using Oscillation Step / Temperature Ramp, and storage at 40 ° C for static non-Newtonian viscosity n * (Pa · s) and -5 ° C. The elastic modulus G ′ (Pa) is obtained. The sample solution is kept warm until the liquid temperature becomes constant at the measurement start temperature, and then the measurement is started.

  In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, and more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s. Therefore, the dynamic storage elastic modulus at 15 ° C. should be 100 to 1,000,000. Furthermore, the dynamic storage elastic modulus at low temperature is preferably as large as possible. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When the support is at −50 ° C., the dynamic storage elastic modulus at −50 ° C. is preferably 10,000 to 5 million Pa.

  When the above-mentioned suitable cellulose acylate is used, a high concentration dope can be obtained, and a cellulose acylate solution having a high concentration and excellent stability can be obtained without depending on the means of concentration. Further, in order to facilitate dissolution, it may be concentrated using a concentration means after being dissolved at a low concentration. The concentration method is not particularly limited. For example, the low-concentration solution is guided between the cylindrical body and the rotation trajectory of the outer periphery of the rotating blade rotating in the circumferential direction, and the temperature between the solution and the solution. A method of giving a difference and obtaining a high-concentration solution while evaporating the solvent (for example, JP-A-4-259511), until a heated low-concentration solution is blown into the container from the nozzle until the solution hits the inner wall of the container from the nozzle The solvent is flash evaporated between the container and the solvent vapor is withdrawn from the container and the concentrated solution is withdrawn from the container bottom (eg, US Pat. No. 2,541,012, US Pat. No. 2,858,229, US The method described in Japanese Patent No. 4,414,341, US Pat. No. 4,504,355, etc.) and the like.

  Prior to casting, the dope solution is preferably filtered off foreign matters such as undissolved matter, dust, and impurities using an appropriate filter medium such as a wire mesh or flannel. For filtration of the cellulose acylate solution, it is preferable to use a filter having an absolute filtration accuracy of 0.1 to 100 μm, and it is more preferable to use a filter having an absolute filtration accuracy of 0.5 to 25 μm. The thickness of the filter is preferably 0.1 to 10 mm, and more preferably 0.2 to 2 mm. In that case, the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, further 1.0 MPa or less, and particularly preferably 0.2 MPa or less. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, fluororesins such as tetrafluoroethylene resin can be preferably used, and ceramics, metals and the like are particularly preferably used. The viscosity of the cellulose acylate solution immediately before film formation may be in a range that can be cast during film formation, and is usually prepared in a range of 10 Pa · s to 2000 Pa · s, preferably 30 Pa · s to 1000 Pa. · S is more preferable, and 40 Pa · s to 500 Pa · s is more preferable. The temperature at this time is not particularly limited as long as it is a temperature at the time of casting, but is preferably −5 to + 70 ° C., more preferably −5 to + 55 ° C.

[Film formation]
The cellulose acylate film preferably used in the present invention can be obtained by forming a film using the cellulose acylate solution (dope). As the film forming method and equipment, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the rotational speed, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as a web) is peeled off from the metal support at the peeling point where the metal support is cast almost uniformly around the metal support. The both ends of the obtained web are sandwiched between clips, transported by a tenter while maintaining the width, dried, and then transported by a roll group of a drying device to finish drying, and wound to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film for electronic displays, in addition to the solution casting film forming apparatus, surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. Therefore, a coating device is often added. Although each manufacturing process is described briefly below, it is not limited to these.

  In producing a cellulose acylate film by the solvent cast method, first, the prepared cellulose acylate solution (dope) is cast on a drum or a band, and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 5 to 40% by mass. The surface of the drum or band is preferably finished in a mirror state. For the dope, a method of casting on a drum or band having a surface temperature of 30 ° C. or less is preferably employed, and the metal support temperature is particularly preferably in the range of −10 to 20 ° C. Further, in the present invention, JP-A Nos. 2000-301555, 2000-301558, 07-032391, JP-A-03-193316, JP-A-05-086212, JP-A-62-037113, The methods described in JP-A No. 02-276607, JP-A No. 55-014201, JP-A No. 02-111511, and JP-A No. 02-208650 can be used.

[Multilayer casting]
The cellulose acylate solution may be cast as a single layer liquid on a smooth band or a drum as a metal support, or a plurality of cellulose acylate liquids of two or more layers may be cast. When casting a plurality of cellulose acylate solutions, a solution containing cellulose acylate is cast from a plurality of casting openings provided at intervals in the traveling direction of the metal support, and the films are laminated while being laminated. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. A film can also be formed by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, the cellulose described in JP-A-56-162617, a flow of a high-viscosity cellulose acylate solution is wrapped with a low-viscosity cellulose acylate solution, and the high-viscosity and low-viscosity cellulose acylate solutions are simultaneously extruded. An acylate film casting method may be used. Furthermore, as described in JP-A-61-94724 and JP-A-61-94725, it is also preferable that the outer solution contains a larger amount of an alcohol component that is a poor solvent than the inner solution. . Alternatively, two casting ports are used, and after the film formed on the metal support is peeled off by the first casting port, the second casting is performed on the side of the film that is in contact with the metal support surface. Thus, a film having a plurality of layers can also be produced, and examples thereof include a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Further, the cellulose acylate solution may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorption layer, and a polarizing layer).

  In the conventional single-layer solution, in order to obtain the required film thickness, it is necessary to extrude a high-concentration and high-viscosity cellulose acylate solution, in which case the stability of the cellulose acylate solution tends to deteriorate. In many cases, a solid matter is generated, resulting in a failure or flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a plurality of casting ports relatively little by little, it becomes possible to extrude a highly viscous solution onto a metal support at the same time. In addition to producing an excellent planar film with improved properties, the use of a concentrated cellulose acylate solution can achieve a reduction in drying load and increase the production speed of the film.

  In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting of three or more layers, the total film thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness. In the case of co-casting, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as the plasticizer, ultraviolet absorber, and matting agent. For example, a cellulose acylate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. It is also possible to change the type of plasticizer and ultraviolet absorber between the core layer and the skin layer. For example, the skin layer contains at least one of a low-volatile plasticizer and an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Furthermore, it is also a preferred embodiment that a peeling accelerator is contained only in the skin layer on the metal support side. Furthermore, it is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing cellulose acylate during casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity of the layer.

[Casting method]
As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the film thickness of the dope once cast on the metal support is adjusted with a blade. There is a method using a reverse roll coater for adjusting with a reverse rotating roll, and a method using a pressure die is preferable. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods mentioned here, it can be carried out by various known methods for casting a cellulose triacetate solution, and each condition is set in consideration of differences in the boiling point of the solvent used. Thus, the same effects as those described in the respective publications can be obtained.

  The endlessly running metal support used for producing the cellulose acylate film preferably used in the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt whose surface is mirror-finished by surface polishing ( May be referred to as a band). One or more pressure dies may be installed above the metal support. Preferably 1 or 2 groups. When two or more are installed, the amount of dope to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps. The temperature of the cellulose acylate solution used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all solution temperatures in the process may be the same or different at different points in the process. If they are different, the temperature may be a desired temperature just before casting.

[Dry]
In the manufacture of a cellulose acylate film, the dope is generally dried on the metal support by applying hot air from the surface side of the metal support (drum or belt), that is, from the surface of the web on the metal support. Method, method of applying hot air from the back of the drum or belt, contact the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heat the drum or belt by heat transfer to control the surface temperature There is a back surface liquid heat transfer method, and the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent. Is preferred. This is not the case when the cast dope is cooled and peeled off without drying.

  In order to suppress light leakage when the polarizing plate is viewed obliquely, it is necessary to arrange the transmission axis of the polarizer and the in-plane slow axis of the cellulose acylate film in parallel. Since the transmission axis of the roll film-like polarizer produced continuously is generally parallel to the width direction of the roll film, it is composed of the roll film-like polarizer and the roll film-like cellulose acylate film. In order to continuously bond the protective film, the in-plane slow axis of the roll film-shaped protective film needs to be parallel to the width direction of the film. Therefore, it is preferable to stretch more in the width direction. The stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched. In the former case, stretching may be performed in a state containing a residual solvent, and the stretching can be preferably performed at a residual solvent amount of 2 to 30% by mass.

  The film thickness of the cellulose acylate film preferably used in the present invention obtained after drying varies depending on the purpose of use, and is usually preferably in the range of 5 to 500 μm, more preferably in the range of 20 to 300 μm, particularly 30 to 30 μm. A range of 150 μm is preferred. Moreover, it is preferable that it is 40-110 micrometers for optical use, especially for VA liquid crystal display devices. The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness.

  The width of the cellulose acylate film obtained as described above is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, and still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10,000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, it is preferable to give knurling to at least one end, the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

  The variation in the Re (590) value in the width direction of the film is preferably ± 5 nm, and more preferably ± 3 nm. Further, the variation in the Rth (590) value in the width direction is preferably ± 10 nm, and more preferably ± 5 nm. Moreover, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

  The variation of the slow axis angle in the film plane of the cellulose acylate film preferably used in the present invention is preferably in the range of −2 ° to + 2 ° with respect to the reference direction of the roll film, from −1 ° to The range of + 1 ° is more preferable, and the range of −0.5 ° to + 0.5 ° is most preferable. Here, the reference direction is the longitudinal direction of the roll film when the cellulose acylate film is longitudinally stretched, and the width direction of the roll film when laterally stretched.

  In addition, the cellulose acylate film preferably used in the present invention has a difference between an Rth value at 25 ° C. and 10% RH and an Rth value at 25 ° C. and 80% RH ΔRth = | Rth (550) 10% RH−Rth ( 550) It is preferable that 80% RH | is 0 to 10 nm in order to reduce a color change with time of the liquid crystal display device.

Furthermore, the cellulose acylate film preferably used in the present invention has an equilibrium water content of 5.5% or less at 25 ° C. and 80% RH, from the viewpoint of reducing the color change with time of the liquid crystal display device.
The moisture content is measured by using a cellulose acylate film sample of 7 mm × 35 mm, a Karl Fischer method using a moisture measuring device and a sample drying apparatus {“CA-03”, “VA-05”, both Mitsubishi Chemical Corporation}}. Measure with It is calculated by dividing the amount of water (g) by the sample mass (g).

Furthermore, the cellulose acylate film preferably used in the present invention has a moisture permeability of 60 ° C., 95% RH, and 24 hours (in terms of a film thickness of 80 μm) of 400 g / m ² · 24 hr or more and 1800 g / m ² · 24 hr or less. It is preferable in order to reduce the color change with time of the liquid crystal display device.

The moisture permeability decreases as the thickness of the cellulose acylate film increases, and increases as the thickness decreases. Therefore, it is necessary to provide and convert a reference film thickness for any film thickness sample. In the present invention, the film thickness was converted according to the following formula (13) with the standard film thickness set at 80 μm.
Formula (13): 80 μm converted moisture permeability = measured moisture permeability × measured film thickness μm / 80 μm.

  The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The method described in can be applied.

  The glass transition temperature was measured by adjusting a cellulose acylate film sample (unstretched) 5 mm × 30 mm at 25 ° C. and 60% RH for 2 hours or more, and then measuring a dynamic viscoelasticity measuring device “Vibron: DVA-225” { Measured by a distance between grips of 20 mm, a heating rate of 2 ° C./min, a measurement temperature range of 30 ° C. to 200 ° C., a frequency of 1 Hz, and a logarithmic axis as a logarithmic axis. The temperature at which the storage elastic modulus shifts from the solid region to the glass transition region when the temperature (° C.) is taken on the linear axis on the horizontal axis is the glass transition temperature Tg. It was. Specifically, on the obtained chart, when the straight line 1 is drawn in the solid region and the straight line 2 is drawn in the glass transition region, the intersection of the straight line 1 and the straight line 2 decreases rapidly when the temperature rises. The glass transition temperature Tg (dynamic viscoelasticity) was determined because the film started to soften and the temperature started to shift to the glass transition region.

  The elastic modulus was measured by adjusting a cellulose acylate film sample 10 mm × 150 mm at 25 ° C. and 60% RH for 2 hours or more, and then a tensile tester “Strograph-R2” {manufactured by Toyo Seiki Seisakusho}} The chucking distance was 100 mm, the temperature was 25 ° C., and the stretching speed was 10 mm / min.

The measurement of the hygroscopic expansion coefficient is the value L _{80% obtained} by measuring the dimension of the film left at 25 ° C. and 80% RH for 2 hours or more with the pin gauge, and the dimension of the film left at 25 ° C. and 10% RH for 2 hours or more. Was obtained by the following formula (14) from the value L _10% measured with a pin gauge.
Formula (14): (L _80% -L _10% ) / (80% RH-10% RH) × 10 ⁶

The cellulose acylate film preferably used in the present invention preferably has a haze in the range of 0.01 to 2%. Here, the haze can be measured as follows.
The haze is measured by measuring a cellulose acylate film sample 40 mm × 80 mm at 25 ° C. and 60% RH with a haze meter “HGM-2DP” (manufactured by Suga Test Instruments Co., Ltd.) according to JIS K-6714.

  Furthermore, the cellulose acylate film preferably used in the present invention preferably has a mass change in the range of 0 to 5% by mass when left for 48 hours under conditions of 80 ° C. and 90% RH.

  Furthermore, the cellulose acylate film preferably used in the present invention has a dimensional change when left standing for 24 hours under conditions of 60 ° C. and 95% RH, and is allowed to stand for 24 hours under conditions of 90 ° C. and 5% RH. It is preferable that the dimensional change when placed is in the range of 0 to 5%.

The photoelastic coefficient is preferably 50 × 10 ⁻¹³ cm ² / dyne or less in order to reduce the color change with time of the liquid crystal display device.
As a specific measuring method, a tensile stress was applied to the major axis direction of a cellulose acylate film sample 10 mm × 100 mm, and the retardation at that time was measured with an ellipsometer “M150” {JASCO Corporation}. The photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

[Melting film formation]
The method for producing the optical film of the present invention may be melt film formation. A raw material such as a polymer or an additive as a raw material may be heated and melted, and then extruded to form a film by injection molding. Alternatively, the raw material may be sandwiched between two heated plates and pressed to form a film.

  The temperature for heating and melting is not particularly limited as long as the raw polymer is melted uniformly. Specifically, it is heated to a temperature equal to or higher than the melting point or softening point. In order to obtain a uniform film, the material is melted by heating to a temperature higher than the melting point of the starting polymer, preferably 5 to 40 ° C. higher than the melting point, particularly preferably 8 to 30 ° C. higher than the melting point. preferable.

[Alignment film]
The optical compensation film may have an alignment film between the cellulose acylate film and the optically anisotropic layer. In addition, an alignment film is used only when an optically anisotropic layer is produced, and after an optically anisotropic layer is produced on the oriented film, only the optically anisotropic layer is transferred onto a cellulose acylate film. Also good.
In the present invention, the alignment film is preferably a layer made of a crosslinked polymer. The polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent. The alignment film is formed by reacting a polymer having a functional group or a polymer having a functional group introduced therein with light, heat, pH change, or the like; or a cross-linking agent that is a highly reactive compound Can be formed by introducing a linking group derived from a cross-linking agent between polymers to cross-link between the polymers.

  The alignment film made of a crosslinked polymer can be usually formed by applying a coating solution containing the polymer or a mixture of the polymer and a crosslinking agent on a support, followed by heating. In the rubbing process described later, it is preferable to increase the degree of crosslinking in order to suppress the dust generation of the alignment film. A value (1- (Ma / Mb)) obtained by subtracting 1 from the ratio (Ma / Mb) of the amount (Ma) of the crosslinking agent remaining after crosslinking to the amount (Mb) of the crosslinking agent added to the coating solution. When Mb)) is defined as the degree of crosslinking, the degree of crosslinking is preferably 50% to 100%, more preferably 65% to 100%, and most preferably 75% to 100%.

In the present invention, the polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent. Of course, a polymer having both functions can also be used. Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide), styrene / vinyl toluene copolymer. , Chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethyl cellulose, gelatin, polyethylene, polypropylene, polycarbonate, etc. Examples thereof include compounds such as polymers and silane coupling agents. Examples of preferred polymers are water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyville alcohol, and modified polyvinyl alcohol, and gelatin, polyville alcohol, and modified polyvinyl alcohol are preferred. Mention may be made of bil alcohol and modified polyvinyl alcohol.
In the case of directly coating polyvinyl alcohol and modified polyvinyl alcohol on the cellulose acylate film used in the present invention, a method of providing a hydrophilic undercoat layer or applying a saponification treatment is preferably used.

Among the above polymers, polyvinyl alcohol or modified polyvinyl alcohol is preferable.
Examples of the polyvinyl alcohol include those having a saponification degree of 70 to 100%, generally those having a saponification degree of 80 to 100%, and more preferably those having a saponification degree of 82 to 98%. The degree of polymerization is preferably in the range of 100 to 3000.
Examples of the modified polyvinyl alcohol include those modified by copolymerization (modified groups such as COONa, Si (OX) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ Na, C ₁₂ H _25, etc. Modified by chain transfer (for example, COONa, SH, SC ₁₂ H ₂₅ etc. are introduced as modifying groups), modified by block polymerization (modified groups such as COOH, for example) , CONH ₂ , COOR, C ₆ H _5, etc. are introduced). As a polymerization degree, the range of 100-3000 is preferable. Among these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferable, and unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% is more preferable.
In order to impart adhesion between the cellulose acylate film and the optically anisotropic layer, it is preferable to introduce a crosslinking / polymerization active group into the polyvinyl alcohol, and preferable examples thereof include JP-A-8-338913. It is described in detail in the publication.
When using a hydrophilic polymer such as polyvinyl alcohol for the alignment film, it is preferable to control the moisture content from the viewpoint of the degree of hardening, preferably 0.4% to 2.5%, 0.6% More preferably, it is -1.6%. The water content can be measured with a commercially available Karl Fischer moisture content measuring device.
The alignment film preferably has a thickness of 10 microns or less.

It is preferable that Re (550) of the cellulose acylate film used in the present invention is in the range of 20 to 100 nm, and Rth (550) is in the range of 100 to 300 nm.
In particular, when used as an optical compensation film in a VA liquid crystal display device, when compensation is performed on one side of the liquid crystal cell, Re (550) is in the range of 40 to 100 nm, and Rth (550) is in the range of 160 to The range of 300 nm is preferable, Re (550) is 45 to 80 nm, and Rth (550) is more preferably 170 to 250 nm. Further, this optical compensation film may be used on both sides of a liquid crystal cell for VA liquid crystal display.

[Polarizer]
The present invention provides a polarizing plate comprising a polarizing film and a pair of protective films sandwiching the polarizing film, wherein at least one of the protective films includes the optical film. For example, a polarizing film obtained by dyeing a polarizing film made of a polyvinyl alcohol film or the like with iodine, stretching, and laminating both surfaces with a protective film can be used. The polarizing plate is disposed outside the liquid crystal cell. It is preferable that a pair of polarizing plates each including a polarizing film and a pair of protective films sandwiching the polarizing film are disposed with the liquid crystal cell interposed therebetween. In addition, it is preferable that the protective film arrange | positioned at the liquid crystal cell side is the optical film or optical compensation film of this invention.

"adhesive"
The adhesive between the polarizing film and the protective film is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. PVA resin is preferable. The thickness of the adhesive layer is preferably 0.01 to 10 microns after drying, and particularly preferably 0.05 to 5 microns.

《Integrated manufacturing process of polarizing film and protective film》
A polarizing plate that can be used in the present invention can be produced by having a drying process in which a polarizing film is stretched and then contracted to reduce the volatile content, and a protective film is applied to at least one surface after drying or during drying. After combining, it is preferable to have a post-heating step. As a specific attaching method, a protective film is attached to the polarizing film with an adhesive while holding both ends during the drying process of the film, and then both ends are cut off, or after drying, polarized from the holding parts on both ends. There is a method in which the film for film is released, both ends of the film are cut off, and then a protective film is applied. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After bonding, it is preferable to heat in order to dry the adhesive and improve the polarization performance. The heating condition varies depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C. or higher, more preferably 40 ° C. to 100 ° C., and further preferably 50 ° C. to 90 ° C. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.

<Performance of polarizing plate>
The optical properties and durability (short-term and long-term storage stability) of the polarizing plate of the present invention may be equivalent to or better than commercially available super high contrast products (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.). preferable. 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, and Tc is orthogonal transmission) The change rate of the light transmittance before and after being left in an atmosphere of 60 ° C. and a humidity of 90% RH for 500 hours and 80 ° C. in a dry atmosphere for 500 hours is 3% or less based on the absolute value, Further, it is preferably 1% or less, and the rate of change of the polarization degree is preferably 1% or less, more preferably 0.1% or less based on the absolute value.

[Surface treatment of cellulose acylate film]
The cellulose acylate film preferably used in the present invention can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. . As 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 here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Regarding these, the details are disclosed in the Invention Association Public Technical Bulletin No. 2001-1745 (issued March 15, 2001, Invention Association) p. 30-32. In the plasma treatment at atmospheric pressure, which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kGy is used under 10 to 1000 keV, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 keV. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

[Alkaline saponification]
The alkali saponification treatment is preferably carried out by a method in which the cellulose acylate film is directly immersed in a saponification solution tank or a method in which the saponification solution is applied to the cellulose acylate film. Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkali saponification coating solution has good wettability in order to apply the saponification solution to the cellulose acylate film, and the surface of the cellulose acylate film surface is not formed by the saponification solution solvent. It is preferred to select a solvent that remains good. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during the alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water.

Moreover, it is preferable that the polarizing plate regarding this invention provides an optically anisotropic layer on a protective film.
The material of the optically anisotropic layer is not limited, such as a liquid crystal compound, a non-liquid crystal compound, an inorganic compound, and an organic / inorganic composite compound. Liquid crystalline compounds include those in which a low molecular weight compound having a polymerizable group is aligned and then fixed by polymerization with light or heat, or liquid crystalline polymers are heated and aligned, then cooled and aligned in a glassy state. You can use what you want to fix. As the liquid crystalline compound, those having a disk-like structure, those having a rod-like structure, and those having a structure showing optical biaxiality can be used. As the non-liquid crystalline compound, a polymer having an aromatic ring such as polyimide or polyester can be used.
Various methods, such as application | coating, vapor deposition, sputtering, can be used for the formation method of an optically anisotropic layer.
When an optically anisotropic layer is provided on the protective film of the polarizing plate, the adhesive layer is further provided outside the optically anisotropic layer from the polarizer side.

  Furthermore, the polarizing plate according to the present invention is preferably one in which at least one layer of a hard coat layer, an antiglare layer or an antireflection layer is provided on the surface of the protective film on at least one side of the polarizing plate. That is, when the polarizing plate is used for 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 side opposite to the liquid crystal cell. It is preferable to provide at least one layer of a coat layer, an antiglare layer or an antireflection layer. In addition, it is not necessary to provide each layer as a separate layer, for example, by providing an antireflection layer and a hard coat layer with an antiglare function, instead of providing two layers of an antireflection layer and an antiglare layer, You may make it function as an anti-glare antireflection layer.

(Antireflection layer)
In the present invention, at least a light scattering layer and a low refractive index layer are laminated in this order on the protective film of the polarizing plate, or a medium refractive index layer, a high refractive index layer, and a low refractive index on the protective film. An antireflection layer in which rate layers are laminated in this order is suitably provided. Preferred examples thereof are described below. In the former configuration, the specular reflectance is generally 1% or more, which is referred to as a low reflection (LR) film. In the latter configuration, it is possible to realize a mirror reflectivity of 0.5% or less, and this is called an Anti Reflection (AR) film.

[LR film]
A preferred example of an antireflection layer (LR film) in which a light scattering layer and a low refractive index layer are provided on a protective film of a polarizing plate will be described.
In the light scattering layer, mat particles are preferably dispersed, and the refractive index of the material other than the mat particles in the light scattering layer is preferably in the range of 1.50 to 2.00, and the low refractive index The refractive index of the layer is preferably in the range of 1.20 to 1.49. In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be a single layer or a plurality of layers, for example, two to four layers.

  The antireflection layer has an uneven surface shape, centerline average roughness Ra is 0.08 to 0.40 μm, 10-point average roughness Rz is 10 times or less Ra, average unevenness distance Sm is 1 to 100 μm, unevenness The standard deviation of the height of the convex part from the deepest part is 0.5 μm or less, the standard deviation of the average unevenness distance Sm with respect to the center line is 20 μm or less, and the surface with the inclination angle of 0 to 5 ° is 10% or more. It is preferable that it is designed so that sufficient anti-glare property and visual uniform matte feeling can be achieved.

Further, the ratio between the minimum value and the maximum value of the reflectance when the color of the reflected light under the C light source is in the range of a ^* value −2 to 2, b ^* value −3 to 3 and 380 nm to 780 nm. It is preferable that it is 5-0.99 because the color of the reflected light becomes neutral. Furthermore, it is preferable that the b ^* value of the transmitted light under the C light source is 0 to 3 because the yellow color of white display when applied to a display device is reduced. Furthermore, when a 120 μm × 40 μm grid is inserted between the surface light source and the antireflection layer and the luminance distribution is measured on the film, the standard deviation of the luminance distribution is 20 or less. Since glare when the polarizing plate of the invention is applied is reduced, it is preferable.

  The antireflection layer that can be used in the present invention suppresses reflection of external light by setting its optical properties to a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° glossiness of 70% or less. This is preferable because visibility is improved. In particular, the specular reflectance is more preferably 1% or less, and most preferably 0.5% or less. Haze 20% to 50%, ratio of internal haze / total haze value 0.3 to 1, haze value after formation of low refractive index layer from haze value up to light scattering layer within 15%, comb width 0 .Transparent image clarity at 5 mm, 20% to 50%, vertical transmission light / transmittance ratio in the direction inclined by 2 ° from vertical is 1.5 to 5.0, thereby preventing glare on a high-definition LCD panel. This is preferable because blurring of characters and the like is reduced.

(Low refractive index layer)
The refractive index of the low refractive index layer that can be used in the present invention is preferably 1.20 to 1.49, more preferably 1.30 to 1.44. Furthermore, the low refractive index layer preferably satisfies the following formula (19) from the viewpoint of reducing the reflectance.
Formula (19): (m / 4) λ × 0.7 <n _L d _L <(m / 4) λ × 1.3
In the formula, m is a positive odd number, n _L is the refractive index of the low refractive index layer, and d _L is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 500 to 550 nm.

The material for forming the low refractive index layer will be described below.
The low refractive index layer preferably contains a fluorine-containing polymer as a low refractive index binder.
As the fluorine polymer, a fluorine-containing polymer which is crosslinked by heat or ionizing radiation and having a dynamic friction coefficient of 0.03 to 0.20, a contact angle with water of 90 to 120 ° and a sliding angle of pure water of 70 ° or less is preferable. When the polarizing plate according to the present invention is mounted on an image display device, the lower the peel strength from a commercially available adhesive tape, the easier it is to peel off after sticking a seal or memo. It is preferably 500 gf or less, more preferably 300 gf or less, and most preferably 100 gf or less. Further, the higher the surface hardness measured with a microhardness meter, the harder it is to scratch, and the surface hardness is preferably 0.3 GPa or more, more preferably 0.5 GPa or more.

  Examples of the fluorine-containing polymer used in the low refractive index layer include perfluoroalkyl group-containing silane compounds {for example, hydrolysates and dehydrated condensates of (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane}. In addition, a fluorine-containing copolymer having a fluorine-containing monomer unit and a structural unit for imparting crosslinking reactivity as constituent components can be mentioned.

  Specific examples of the fluorine-containing monomer include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.), (Meth) acrylic acid partial or fully fluorinated alkyl ester derivatives [e.g. "Biscoat 6FM" {manufactured by Osaka Organic Chemical Industry Co., Ltd.} or "M-2020" {manufactured by Daikin Industries Ltd.}], complete or Partially fluorinated vinyl ethers and the like can be mentioned, and perfluoroolefins are preferable, and hexafluoropropylene is particularly preferable from the viewpoint of refractive index, solubility, transparency, availability, and the like.

  As a structural unit for imparting crosslinking reactivity, a structural unit obtained by polymerization of a monomer having a self-crosslinkable functional group in the molecule in advance, such as glycidyl (meth) acrylate or glycidyl vinyl ether, a carboxyl group or a hydroxy group, Polymerization of monomers having amino groups, sulfo groups, etc. {eg (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.} Or a structural unit obtained by introducing a crosslinking reactive group such as a (meth) acryloyl group into the structural unit by a polymer reaction (for example, a method in which acrylic acid chloride is allowed to act on a hydroxy group). ) It is.

  In addition to the fluorine-containing monomer unit and the structural unit for imparting crosslinking reactivity, a monomer that does not contain a fluorine atom can be copolymerized as appropriate from the viewpoint of solubility in a solvent, film transparency, and the like. There are no particular limitations on the monomer units that can be used in combination. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2) -Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyltoluene, α-methylstyrene, etc.), vinyl ethers (methyl) Vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (Nt-butylacrylamide, N-cyclo) Hexyl acrylamide), methacrylamides, and acrylonitrile derivatives.

  As described in JP-A-10-25388 and JP-A-10-147739, the above polymer may be used in combination with a curing agent as appropriate.

(Light scattering layer)
The light scattering layer is formed for the purpose of imparting to the film a light diffusibility due to at least one of surface scattering and internal scattering and a hard coat property for improving the scratch resistance of the film. Therefore, it is formed including a binder for imparting hard coat properties, matte particles for imparting light diffusibility, and inorganic fillers for increasing the refractive index, preventing crosslinking shrinkage, and increasing the strength as necessary. The Further, by providing such a light scattering layer, the light scattering layer also functions as an antiglare layer, and the polarizing plate has an antiglare layer.

  The thickness of the light scattering layer is preferably 1 to 10 μm and more preferably 1.2 to 6 μm for the purpose of imparting hard coat properties. If the film thickness of the light scattering layer is not less than the lower limit, problems such as insufficient hardware properties are unlikely to occur, and if the thickness is not more than the upper limit, inconveniences such as curling and brittleness are deteriorated and workability is insufficient. Is preferable because it is difficult to cause.

  The binder of the light scattering layer is preferably a polymer having a saturated hydrocarbon chain or a polyether chain as the main chain, and more preferably a polymer having a saturated hydrocarbon chain as the main chain. The binder polymer preferably has a crosslinked structure. As the binder polymer having a saturated hydrocarbon chain as a main chain, a polymer of an ethylenically unsaturated monomer is preferable. As the binder polymer having a saturated hydrocarbon chain as the main chain and having a crosslinked structure, a (co) polymer of monomers having two or more ethylenically unsaturated groups is preferable. In order to make the binder polymer have a high refractive index, the monomer structure contains an aromatic ring, at least one atom selected from halogen atoms other than fluorine, sulfur atoms, phosphorus atoms, and nitrogen atoms. You can also choose.

  Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid {for example, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di ( (Meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3- Chlorohexane tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate}, modified ethylene oxide, vinylbenzene and derivatives thereof (for example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4 -Divinylcyclohexanone), vinyl sulfone (e.g. divinyl sulfone), acrylamide (e.g. methylene bisacrylamide) and methacrylamide. Two or more of these monomers may be used in combination.

  Specific examples of the high refractive index monomer include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like. Two or more of these monomers may be used in combination.

  Polymerization of these monomers having an ethylenically unsaturated group can be performed by irradiation with ionizing radiation or heating in the presence of a photo radical initiator or a thermal radical initiator. Accordingly, a coating liquid containing a monomer having an ethylenically unsaturated group, a photo radical initiator or a thermal radical initiator, mat particles and an inorganic filler is prepared, and the coating liquid is applied onto a protective film, and then ionizing radiation or heat is applied. It can harden | cure by the polymerization reaction by and can form an antireflection layer. As these photo radical initiators, known ones can be used.

  The polymer having a polyether as the main chain is preferably a ring-opening polymer of a polyfunctional epoxy compound. The ring-opening polymerization of the polyfunctional epoxy compound can be performed by irradiation with ionizing radiation or heating in the presence of a photoacid generator or a thermal acid generator. Therefore, a coating solution containing a polyfunctional epoxy compound, a photoacid generator or a thermal acid generator, matte particles and an inorganic filler is prepared, and the coating solution is applied on a protective film and then cured by ionizing radiation or heat polymerization reaction. Thus, an antireflection layer can be formed.

  Instead of or in addition to a monomer having two or more ethylenically unsaturated groups, a monomer having a crosslinkable functional group is used to introduce a crosslinkable functional group into the polymer, and this crosslinkable functional group reacts. A crosslinked structure may be introduced into the binder polymer.

Examples of the crosslinkable functional group include isocyanate group, epoxy group, aziridine group, oxazoline group, aldehyde group, carbonyl group, hydrazine group, carboxyl group, methylol group and active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not react immediately but may exhibit reactivity as a result of decomposition.
These binder polymers having a crosslinkable functional group can form a crosslinked structure by heating after coating.

For the purpose of imparting antiglare properties, the light scattering layer contains matte particles having an average particle diameter of 1 to 10 μm, preferably 1.5 to 7.0 μm, such as inorganic compound particles or resin particles, for the purpose of imparting antiglare properties. Is done. Specific examples of the matte particles include preferably particles of inorganic compounds such as silica particles and TiO ₂ particles; and resin particles such as acrylic particles, crosslinked acrylic particles, polystyrene particles, crosslinked styrene particles, melamine resin particles, and benzoguanamine resin particles. It is done. Of these, crosslinked styrene particles, crosslinked acrylic particles, crosslinked acrylic styrene particles, and silica particles are preferable. The shape of the mat particles can be either spherical or irregular.

  Two or more kinds of mat particles having different particle diameters may be used in combination. It is possible to impart anti-glare properties with mat particles having a larger particle size and to impart other optical characteristics with mat particles having a smaller particle size.

  Further, the particle size distribution of the mat particles is most preferably monodisperse, and the particle sizes of the particles are preferably closer to each other. For example, when particles having a particle size of 20% or more than the average particle size are defined as coarse particles, the proportion of coarse particles is preferably 1% or less, more preferably 0.1% of the total number of particles. % Or less, more preferably 0.01% or less. Matt particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and a matting agent having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree of classification.

The mat particles are contained in the light scattering layer so that the amount of mat particles in the formed light scattering layer is preferably 10 to 1000 mg / m ² , more preferably 100 to 700 mg / m ² .
The particle size distribution of the mat particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution.

The light scattering layer is made of an oxide of at least one metal selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony, in addition to the matte particles, in order to increase the refractive index of the layer. Thus, it is preferable that an inorganic filler having an average particle diameter of 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.06 μm or less is contained.
Conversely, in order to increase the difference in refractive index from the mat particles, it is also preferable to use a silicon oxide in order to keep the refractive index of the light scattering layer using the high refractive index mat particles low. The preferred particle size is the same as that of the aforementioned inorganic filler.

Specific examples of the inorganic filler used in the light scattering layer include TiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO and SiO ₂ . TiO ₂ and ZrO ₂ are particularly preferable in terms of increasing the refractive index. The surface of the inorganic filler is preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.

  The amount of these inorganic fillers added is preferably 10 to 90% of the total mass of the light scattering layer, more preferably 20 to 80%, and particularly preferably 30 to 75%.

  Such a filler does not scatter because the particle size is sufficiently smaller than the wavelength of light, and a dispersion in which the filler is dispersed in a binder polymer behaves as an optically uniform substance.

  The bulk refractive index of the mixture of binder and inorganic filler in the light scattering layer is preferably 1.50 to 2.00, more preferably 1.51 to 1.80. In order to make the refractive index within the above range, the kind and amount ratio of the binder and the inorganic filler may be appropriately selected. How to select can be easily known experimentally in advance.

  In order to ensure surface uniformity such as uneven coating, uneven drying, point defects, etc., the light scattering layer should be coated with either a fluorine-based or silicone-based surfactant, or both for forming the light scattering layer. Contained in the composition. In particular, a fluorine-based surfactant is preferably used because an effect of improving surface defects such as coating unevenness, drying unevenness, and point defects of the antireflection layer preferably used in the present invention appears in a smaller addition amount. The purpose is to increase productivity by giving high-speed coating suitability while improving surface uniformity.

[AR film]
Next, an antireflection layer (AR film) in which a middle refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in this order on the protective film will be described.

An antireflection layer comprising at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) in order on the protective film is designed to have a refractive index satisfying the following relationship. .
Refractive index of high refractive index layer> Refractive index of medium refractive index layer> Refractive index of protective film> Refractive index of low refractive index layer

Further, a hard coat layer may be provided between the protective film and the medium refractive index layer. Further, it may comprise a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. For example, JP-A-8-122504, 8-110401, 10-300902, Examples thereof include an antireflection layer described in JP-A No. 2002-243906, JP-A No. 2000-11706, and the like.
Further, other functions may be imparted to each layer. For example, an antifouling low refractive index layer and an antistatic high refractive index layer (for example, JP-A Nos. 10-206603 and 2002-2002). No. 243906 gazette) and the like.

  The haze of the antireflection layer is preferably 5% or less, more preferably 3% or less. Further, the surface strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K-5400.

(High refractive index layer and medium refractive index layer)
The layer having a high refractive index of the antireflection layer is composed of a cured film containing at least an inorganic compound fine particle having a high refractive index having an average particle diameter of 100 nm or less and a matrix binder.

  Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to obtain such fine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agent, etc .: JP-A Nos. 1-295503, 11-153703, 2000-9908, Anionic compounds or organometallic coupling agents: Japanese Patent Application Laid-Open No. 2001-310432, etc., a core-shell structure with high refractive index particles as a core (Japanese Patent Application Laid-Open No. 2001-166104, etc.), specific dispersant combination (For example, JP-A-11-153703, US Pat. No. 6,210,858, JP-A-2002-277609, etc.) and the like.

Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
More preferable materials include a polyfunctional compound-containing composition having at least two polymerizable groups of at least one of radically polymerizable and cationically polymerizable, a composition containing an organometallic compound containing a hydrolyzable group, And at least one composition selected from compositions containing the partial condensates thereof, for example, JP-A 2000-47004, 2001-315242, 2001-31871, 2001- And compounds described in Japanese Patent No. 296401.

  A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

  The refractive index of the high refractive index layer is preferably 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

  The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70. The thickness is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

(Low refractive index layer)
The low refractive index layer is sequentially laminated on the high refractive index layer. The refractive index of the low refractive index layer is preferably 1.20 to 1.55. More preferably, it is 1.30-1.50.

  The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known means for thin film layers including introduction of silicone, introduction of fluorine, and the like can be applied.

The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing a fluorine atom in a range of 35 to 80% by mass, for example, paragraph numbers [0018] to [0026] of JP-A-9-222503. Examples thereof include the compounds described in paragraph Nos. [0019] to [0030] of JP-A-11-38202, paragraph numbers [0027] to [0028] of JP-A-2001-40284, JP-A 2000-284102, and the like.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47.

  The silicone compound is preferably a compound having a polysiloxane structure, containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone [for example, “Silaplane” {manufactured by Chisso Corporation etc.]], polysiloxane containing silanol groups at both ends (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

  The crosslinking or polymerization reaction of at least one of the fluorine-containing polymer and the siloxane polymer having a crosslinking or polymerizable group is performed simultaneously with the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. Alternatively, it is preferable to form the low refractive index layer by light irradiation or heating after coating.

A sol / gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst is also preferable.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly (perfluoroalkyl ether) group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002-53804). Etc.) and the like.

  The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler {eg, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride) as additives other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820}, silane coupling agents, slip agents, surfactants, and the like. .

  When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer is provided on the surface of the protective film in order to impart physical strength to the protective film provided with the antireflection layer. In particular, it is preferably provided between the protective film and the high refractive index layer. The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group in the curable compound is preferably a photopolymerizable functional group. Also preferred are hydrolyzable functional group-containing organometallic compounds and organoalkoxysilyl compounds.

Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

  The hard coat layer can also serve as an antiglare layer containing particles having an average particle size of 0.2 to 10 μm and imparted with an antiglare function (antiglare function).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  The surface strength of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K-5400. Further, in the Taber test according to JIS K-5400, the smaller the wear amount of the test piece before and after the test, the better.

(Other layers of antireflection layer)
Further, a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Antistatic layer)
When an antistatic layer is provided, it is preferable to impart conductivity with a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less. The use of hygroscopic substances, water-soluble inorganic salts, certain surfactants, cationic polymers, anionic polymers, colloidal silica, etc. can give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ). There is a problem that dependency is large, and sufficient conductivity cannot be secured at low humidity. Therefore, a metal oxide is preferable as the conductive layer material. Some metal oxides are colored, but using these metal oxides as the conductive layer material is not preferable because the entire film is colored. Zn, Ti, Sn, Al, In, Si, Mg, Ba, Mo, W, or V can be used as the metal that forms the metal oxide without coloring, and a metal oxide containing these as main components is used. It is preferable.

Specific examples of the metal oxide include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , WO ₃ , V ₂ O _5, etc. These composite oxides are good, and ZnO, TiO ₂ and SnO ₂ are particularly preferable. Examples of containing different atoms include, for example, additives such as Al and In for ZnO, addition of Sb, Nb and halogen elements for SnO ₂ , and Nb and Ta for TiO ₂ . Addition is effective.

Furthermore, as described in Japanese Patent Publication No. 59-6235, a material obtained by adhering the above metal oxide to other crystalline metal particles or fibrous materials (for example, titanium oxide) may be used. Note that the volume resistance value and the surface resistance value are different physical property values and cannot be simply compared. However, in order to secure conductivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less in volume resistance value, The prevention layer should just have the surface resistance value of ¹⁰ < ^-10 > (ohm / square) or less, More preferably, it is 10 < ^-8 > (ohm / square). The surface resistance value of the antistatic layer needs to be measured as a value when the antistatic layer is the outermost layer, and can be measured in the middle of forming the laminated film.

[Liquid Crystal Display]
The polarizing plate obtained by laminating the optical film of the present invention or the optical film and a polarizing film is advantageously used for a liquid crystal display device, particularly a transmissive liquid crystal display device.
The transmissive liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. A polarizing plate consists of a polarizing film and two transparent protective films arrange | positioned at the both sides. The liquid crystal cell carries a liquid crystal between two electrode substrates.
One polarizing plate of the present invention is disposed on one side of the liquid crystal cell, or two are disposed on both sides of the liquid crystal cell.
The liquid crystal cell is preferably in VA mode, OCB mode, IPS mode, or TN mode, and more preferably in OCB mode, IPS mode, or VA mode.
In a VA mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle. ), (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).
In the case of a VA mode liquid crystal display device, when only one polarizing plate of the present invention is used, it is preferably used on the backlight side.
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function.
For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.
An IPS mode liquid crystal display device includes a pair of substrates sandwiching a liquid crystal layer, an electrode group formed on one of the pair of substrates, and a liquid crystal composition material layer having dielectric anisotropy sandwiched between the substrates A liquid crystal comprising: an alignment control layer formed opposite to the pair of substrates for aligning the molecular alignment of the liquid crystal composition material in a predetermined direction; and a driving means for applying a driving voltage to the electrode group Has a cell. The electrode group has an arrangement structure that is arranged so as to apply mainly a parallel electric field to the interface between the alignment control layer and the liquid crystal composition material layer.
In a TN mode liquid crystal cell, rod-like liquid crystalline molecules are substantially horizontally aligned when no voltage is applied, and are twisted and aligned at 60 to 120 °.
The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

[Examples 1 to 10, Comparative Examples 1 to 6, Reference Example]
<Film formation of optical film>
(1) Cellulose acylate By adding sulfuric acid as a catalyst to cellulose as a raw material, and further adding carboxylic anhydride as a raw material for acyl substituents to carry out an acylation reaction, and then neutralizing and saponifying and aging Prepared. At this time, by adjusting the amount of catalyst, the type and amount of carboxylic anhydride, the amount of neutralizing agent added, the amount of water added, the reaction temperature, and the aging temperature, the type of acyl group, the degree of substitution, the bulk density, and the degree of polymerization Different cellulose acylates were prepared. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.
Among the cellulose acylates prepared as described above, the following dope preparation was performed using cellulose acylate having an acetyl group substitution degree of DS2 + DS3 + DS6 = 2.79 and DS6 / (DS2 + DS3 + DS6) = 0.322. .

(2) Dope Preparation <1-1> Cellulose Acylate Solution The following composition is put into a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, and then a filter paper having an average pore size of 34 μm and It filtered with the sintered metal filter with an average hole diameter of 10 micrometers. Here, the additives were selected from the additives 1 to 3 according to Table 1.

―――――――――――――――――――――――――――――――――
Cellulose acylate solution ――――――――――――――――――――――――――――――――――
Cellulose acylate 100.0 parts by mass Additive 12.0 parts by mass Methylene chloride 403.0 parts by mass Methanol 60.2 parts by mass ――――――――――――――――――――― ―――――――――――

Additive 1; Humidity dependency improver

Additive 2; Humidity dependency improver

Additive 3: Mixture of plasticizer triphenyl phosphate / biphenyl diphenyl phosphate = 2/1 (weight ratio)

<1-2> Matting Agent Dispersion Solution Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a dispersing machine to prepare a matting agent dispersion.

――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 2.0 parts by mass Methylene chloride 72.4 parts by mass Methanol 10.8 parts by mass Cellulose acylate solution 10.3 parts by mass ――――――――――――――――――――――――――――

<1-3> Retardation developer solution Next, the following composition containing the cellulose acylate solution prepared by the above method was put into a mixing tank and dissolved by stirring while heating to prepare a retardation developer solution. .

―――――――――――――――――――――――――――――――――
Retardation developer solution ―――――――――――――――――――――――――――――――――
Rth enhancer A 20.0 parts by mass Methylene chloride 58.3 parts by mass Methanol 8.7 parts by mass Cellulose acylate solution 12.8 parts by mass ――――――――――――――――――― ――――――――――――――

  100 parts by mass of the cellulose acylate solution, 1.35 parts by mass of the matting agent dispersion, and a retardation developer solution in an amount such that the Rth developer A in the optical film is 5.1 parts by mass are mixed. A membrane dope was prepared.

(Rth expression agent A)

(Casting)
The above dope was cast using a glass plate casting apparatus. The film was dried for 6 minutes with warm air at a supply air temperature of 70 ° C., and the film peeled off from the glass plate was fixed to the frame, warm air with a supply air temperature of 100 ° C. for 10 minutes, and warm air with a supply air temperature of 140 ° C. for 20 minutes. It dried and manufactured the optical film with a film thickness of 108 micrometers. The glass transition temperature of the optical film was 140 ° C.
This film was gripped on four sides with a biaxial stretching test apparatus (manufactured by Toyo Seiki Seisakusho Co., Ltd.) and subjected to stretching and shrinking processes under the conditions shown in Table 1. As a common condition, preheating was performed for 3 minutes at the specified supply air temperature in each example before stretching, and it was confirmed that the film surface temperature measured with a non-contact infrared thermometer was within ± 1 ° C of the intake air temperature. . After stretching, air cooling was performed for 5 minutes while holding the clip. MD in the table indicates the casting direction at the time of casting the glass plate, and TD indicates the width direction perpendicular to the casting direction.

<Wrinkles of film>
The film was visually evaluated for wrinkles.
×: Level at which wrinkles are clearly observed visually
△: Level at which wrinkles are observed when watched carefully
○: Wrinkle-free level

<Re, Rth in light of wavelength 450, 550, 650 nm of film>
Re and Rth in light having wavelengths of 450, 550 and 650 nm of this film were measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above.
The results are shown in Table 1. From Table 1, the values of Re and Rth in light having wavelengths of 450, 550, and 650 nm of the optical film produced by the production method of the present invention are the same as those in the above formulas (Ia), (Ib), (II), and (III). It can be seen that

<Re humidity dependence>
The obtained optical film was conditioned at 25 ° C. and 10% RH and 25 ° C. and 80% RH for 2 hours or more, and then the retardation Re was measured in the environment. At this time, ΔRe (550) = Re (550) 10% RH−Re (550) 80% RH was calculated as the amount of change in retardation Re at a wavelength of 550 nm from 10% RH to 80% RH.

  From Table 1, it can be seen that the optical film of the present invention has a smaller ΔRe (550) than the optical film according to the comparative example, and the humidity dependency of Re is reduced.

<Preparation of polarizing plate>
A polarizing film was prepared by adsorbing iodine to a stretched polyvinyl alcohol film.
The optical film produced in Examples 1-10, Comparative Examples 1-6, and a reference example was affixed on the one side of the polarizing film using the polyvinyl alcohol-type adhesive agent. The saponification treatment was performed under the following conditions.
A 1.5 mol / liter aqueous sodium hydroxide solution was prepared and kept at 55 ° C. A 0.01 mol / liter dilute sulfuric acid aqueous solution was prepared and kept at 35 ° C. The produced optical film was immersed in the aqueous sodium hydroxide solution for 2 minutes, and then immersed in water to sufficiently wash away the aqueous sodium hydroxide solution. Subsequently, after being immersed in the above-mentioned dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water to sufficiently wash away the dilute sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
A commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is saponified, and is attached to the opposite side of the polarizer using a polyvinyl alcohol adhesive, and at 70 ° C. for 10 minutes or more. Dried.
The transmission axis of the polarizing film and the slow axis of the optical film produced as described above were arranged in parallel. The transmission axis of the polarizing film and the slow axis of a commercially available cellulose triacylate film were arranged so as to be orthogonal.

<Production of liquid crystal cell>
The liquid crystal cell has a cell gap between substrates of 3.6 μm, and a liquid crystal material having negative dielectric anisotropy (“MLC6608”, manufactured by Merck & Co., Inc.) is dropped and sealed between the substrates. Prepared by forming a layer. The retardation of the liquid crystal layer (that is, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn) was set to 300 nm. The liquid crystal material was aligned so as to be vertically aligned.

<Mounting on VA panel>
A commercially available super high contrast product (HLC2-5618 manufactured by Sanlitz Co., Ltd.) was used for the upper polarizing plate (observer side) of the liquid crystal display device using the vertical alignment type liquid crystal cell. In the lower polarizing plate (backlight side), the polarizing plate provided with the cellulose acylate films prepared in Examples 1, 2, 9, 10 and Comparative Examples 1 to 6 and Reference Example, the cellulose acylate film is a liquid crystal. It installed so that it might become the cell side. The upper polarizing plate and the lower polarizing plate were attached to the liquid crystal cell via an adhesive. The crossed nicols were arranged so that the transmission axis of the upper polarizing plate was in the vertical direction and the transmission axis of the lower polarizing plate was in the horizontal direction.
A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. A normally black mode with 5 V white display and 0 V black display was set. The black display transmittance (%) at the azimuth angle of 45 degrees and the polar angle of 60 degrees and the color shift Δx between the azimuth angle of 45 degrees polar angle of 60 degrees and the azimuth angle of 180 degrees and polar angle of 60 degrees were obtained. . The results are shown in Table 1. Further, using the measuring device (EZ-Contrast 160D, manufactured by ELDIM) as the contrast ratio, the transmittance ratio (white display / black display), the visual field is displayed in eight stages from black display (L1) to white display (L8). The angle (a polar angle range with a contrast ratio of 10 or more and no black-side gradation inversion) was measured. The results are shown in Table 2. As a result of observing the manufactured liquid crystal display device, in Examples 1, 2, 9, and 10, neutral black display was realized in both the front direction and the viewing angle direction.

Viewing angle (polar angle range with contrast ratio of 10 or more and no black-side gradation inversion)
○ Polar angle 80 ° or more in top / bottom / left / right ○ △ Polar angle 80 ° or more in three directions, top / bottom / left / right △ Polar angle 80 ° or more in two directions, top / bottom / left / right × Within top / bottom / left / right, pole in 0-1 direction Angle 80 ° or more Color shift (Δx)
○ Less than 0.02 ○ △ 0.02-0.04
△ 0.04-0.06
× 0.06 or more

[Examples 11 to 14]
Next, the relationship of the substitution degree DS2 with the acyl group of the hydroxyl group at the 2-position of the glucose unit of the cellulose acylate used, the substitution degree DS3 with the acyl group of the hydroxyl group at the 3-position, and the substitution degree DS6 with the acyl group of the hydroxyl group at the 6-position. Except for the points adjusted as shown in Table 3, optical films were produced in the same manner as in Example 2, processed into polarizing plates, mounted on VA panels, and evaluated. The evaluation results are shown in Table 3. In Example 11, neutral black display could be realized in both the front direction and the viewing angle direction. Also in Example 12, the color shift was small and a neutral black display could be realized. This result shows that the substitution degree of the hydroxyl group of the glucose unit of the optical film with an acyl group, (DS2 + DS3 + DS6) and DS6 / (DS2 + DS3 + DS6) can improve these performances.

[Examples 15 and 16, Comparative Example 7, Examples 17 to 22]
<Mounting on VA panel>
Examples 3 and 4, Comparative Example 5, and Examples 7 and 8 are provided on both the upper polarizing plate (observer side) and the lower polarizing plate (backlight side) of the liquid crystal display device using the vertical alignment type liquid crystal cell. And the polarizing plate provided with the optical film produced in Examples 11-14 was installed so that this optical film might become the liquid crystal cell side. The upper polarizing plate and the lower polarizing plate were attached to the liquid crystal cell via an adhesive. The liquid crystal displays of Examples 15 and 16, Comparative Example 7, and Examples 17 to 22 are arranged in a crossed Nicol arrangement so that the transmission axis of the upper polarizing plate is in the vertical direction and the transmission axis of the lower polarizing plate is in the horizontal direction. A device was made.
A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. A normally black mode with 5 V white display and 0 V black display was set. The black display transmittance (%) at the azimuth angle of 45 degrees and the polar angle of 60 degrees and the color shift Δx between the azimuth angle of 45 degrees polar angle of 60 degrees and the azimuth angle of 180 degrees and polar angle of 60 degrees were obtained. . The results are shown in Table 4. Further, using the measuring device (EZ-Contrast 160D, manufactured by ELDIM) as the contrast ratio, the transmittance ratio (white display / black display), the visual field is displayed in eight stages from black display (L1) to white display (L8). The angle (a polar angle range with a contrast ratio of 10 or more and no black-side gradation inversion) was measured. The results are shown in Table 4. As a result of observing the produced liquid crystal display device, in Examples 15 to 18, 21, and 22, neutral black display was realized in both the front direction and the viewing angle direction.

Viewing angle (polar angle range with contrast ratio of 10 or more and no black-side gradation inversion)
○ Polar angle 80 ° or more in top / bottom / left / right ○ △ Polar angle 80 ° or more in three directions, top / bottom / left / right △ Polar angle 80 ° or more in two directions, top / bottom / left / right × Within top / bottom / left / right, pole in 0-1 direction Angle 80 ° or more Color shift (Δx)
○ Less than 0.02 ○ △ 0.02-0.04
△ 0.04-0.06
× 0.06 or more

[Example 23]
<Evaluation of mounting on OCB panel>
(Alkali treatment)
To the optical film produced in Example 1, a 1.0 mol / L potassium hydroxide solution (solvent: water / isopropyl alcohol / propylene glycol = 69.2 parts by mass / 15 parts by mass / 15.8 parts by mass) was added at 10 cc / After applying m ² and holding at about 40 ° C. for 30 seconds, the alkaline solution was scraped off, washed with pure water, and water droplets were removed with an air knife. Then, it dried at 100 degreeC for 15 second.
The contact angle of the alkali-treated surface with pure water was measured and found to be 42 °.

(Formation of alignment film)
An alignment film coating solution having the following composition was applied to the alkali-treated surface by a # 16 wire bar coater at 28 ml / m ² . The alignment film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds.

──────────────────────────────────────
Alignment film coating solution composition ──────────────────────────────────────
Denatured polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde (crosslinking agent) 0.5 parts by weight Citrate ester (AS3, Sankyo Chemical Co., Ltd.) 0.35 parts by weight ──────────────────────────────────

(Rubbing process)
The transparent support on which the alignment film is formed is transported at a speed of 20 m / min, a rubbing roll (300 mm diameter) is set so as to be rubbed at 45 ° with respect to the longitudinal direction, and rotated at 650 rpm. A rubbing treatment was performed on the alignment film installation surface. The contact length between the rubbing roll and the transparent support was set to 18 mm.

(Formation of another optically anisotropic layer)
To 102 kg of methyl ethyl ketone, 41.01 kg of the discotic liquid crystalline compound used in Example 1, ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4.06 kg, cellulose acetate butyrate ( CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.35 Kg, photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy Co.) 1.35 Kg, sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 Kg Dissolved. To the solution, 0.1 kg of a fluoroaliphatic group-containing copolymer (Megafac F780 manufactured by Dainippon Ink Co., Ltd.) was added to prepare a coating solution. The coating solution was continuously applied to the alignment film surface of the transparent support being conveyed at 20 m / min by rotating a # 3.2 wire bar at 391 rotations in the same direction as the film conveyance direction.

  The temperature was continuously heated from room temperature to 100 ° C., the solvent was dried, and then the film surface wind speed of the disc-like optically anisotropic layer was 2.5 m / sec in a drying zone at 130 ° C. The disc-shaped liquid crystalline compound was aligned by heating for 2 seconds. Next, the film is transported to a drying zone at 80 ° C., and an ultraviolet ray with an illuminance of 600 mW is applied by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) with the surface temperature of the film being about 100 ° C. Irradiation was performed for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystalline compound was fixed to the orientation. Then, it was allowed to cool to room temperature and wound into a cylindrical shape to form a roll. In this way, a roll-shaped optical compensation film (KH-3) was produced.

When the viscosity of the optically anisotropic layer was measured at a film surface temperature of 127 ° C., it was 695 cp. The viscosity is a result of measuring a liquid crystal layer (excluding the solvent) having the same composition as the optically anisotropic layer with a heating E-type viscosity system.
A part of the produced roll-shaped optical compensation film KH-3 was cut out and used as a sample to measure optical characteristics. The Re retardation value of the optically anisotropic layer measured at a wavelength of 546 nm was 38 nm. Further, the angle (tilt angle) between the disc surface of the discotic liquid crystalline compound in the optically anisotropic layer and the support surface varied continuously in the depth direction of the layer, and averaged 28 °. Furthermore, when only the optically anisotropic layer was peeled from the sample and the average direction of the molecular symmetry axis of the optically anisotropic layer was measured, it was 45 ° with respect to the longitudinal direction of the optical compensation film.

(Preparation of polarizing plate)
A polarizing film was prepared by adsorbing iodine to the stretched polyvinyl alcohol film, and the prepared film (KH-3) was attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. The transmission axis of the polarizing film and the slow axis of the retardation plate (KH-3) were arranged in parallel.
A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to saponification treatment and attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate was produced.

(Preparation of bend alignment liquid crystal cell)
A polyimide film was provided as an alignment film on a glass substrate with an ITO electrode, and the alignment film was rubbed. The obtained two glass substrates were faced to each other so that the rubbing directions were parallel to each other, and the cell gap was set to 4.7 μm. A bend-aligned liquid crystal cell was prepared by injecting a liquid crystal compound (ZLI1132, manufactured by Merck & Co., Inc.) having a Δn of 0.1396 into the cell gap.
Two polarizing plates produced by the above-described method were attached so as to sandwich the produced bend alignment cell. The optically anisotropic layer of the polarizing plate faced the cell substrate, and the rubbing direction of the liquid crystal cell and the rubbing direction of the “another” optically anisotropic layer facing the liquid crystal cell were arranged to be antiparallel.
A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. A normally white mode of 2V white display and 5V black display was set. As a result of observing the manufactured liquid crystal display device by applying a voltage with the lowest transmittance at the front, that is, a black voltage, neutral black display was realized in both the front direction and the viewing angle direction.

[Examples 24 to 25 and Comparative Examples 8 to 9]
Among the prepared cellulose acylates, cellulose acylate having a substitution degree of acetyl group of 2.00, a substitution degree of propionyl group of 0.60, and a viscosity average polymerization degree of 350, 100 parts by mass of cellulose acylate, the additive 1 described above (Humidity dependency improver) 12 parts by weight, 290 parts by weight of methylene chloride, and 60 parts by weight of ethanol were placed in a sealed container, and the temperature of the mixture was gradually raised while stirring, and the temperature was raised to 80 ° C. over 60 minutes and dissolved. The inside of the container was 1.5 atm. This dope was added to Azumi Filter Paper No. After filtering using 244, it left still for 24 hours and the bubble in dope was removed.

  Separately, 5 parts by mass of the above cellulose acylate, 5 parts by mass of TINUVIN 109 (manufactured by Ciba Specialty Chemicals), 15 parts by mass of TINUVIN 326 (manufactured by Ciba Specialty Chemicals), AEROSIL A UV absorber solution was prepared by mixing 0.5 parts by mass of R972V (manufactured by Nippon Aerosil Co., Ltd.) with 94 parts by mass of methylene chloride and 8 parts by mass of ethanol, stirring and dissolving. R972V was previously dispersed in ethanol and added.

The ultraviolet absorbent solution was added at a ratio of 6 parts by mass with respect to 100 parts by mass of the dope and sufficiently mixed by a static mixer.
(Casting)
The dope thus prepared was cast in the same manner as described above in Example 1 (casting) to produce an optical film having a thickness of 108 μm. The glass transition temperature of the optical film was 140 ° C. This film was gripped on four sides by the same method as described above (casting) with a biaxial stretching test apparatus, and stretched and contracted under the conditions shown in Table 5.
Using the film thus subjected to the stretching / shrinking process, measurement was performed in the same manner as described in Example 1 <Re, Rth at film wavelengths 450, 550, and 650 nm> and <Preparation of polarizing plate>, and preparation of the polarizing plate Went. Further, mounting evaluation was performed in the same procedure as <Preparation of liquid crystal cell> described in Example 1 and <Mounting on VA panel> described in Example 9. The results are shown in Table 5.

[Examples 26 to 28]
Next, in the same manner as in Example 24 except that the substitution degree of the acetyl group (abbreviation Ac), propionyl group (abbreviation Pr), butyryl group (abbreviation Bt), and benzoyl group (abbreviation Bz) was changed to the values shown in Table 6. A cellulose acylate film was prepared. The method of measurement and mounting evaluation is the same as that of the example 24.

  In the cellulose acylate film having a substitution degree B of 0 or more by propionyl group, butyryl group, or benzoyl group as described above, Examples 9 and 10 using cellulose acylate films in which all substituents are acetyl groups It can be seen that the viewing angle and color misregistration performance equivalent to those of No. 13 and No. 13 can be realized without adding a retardation developer.

  According to the present invention, a cellulose acylate film, particularly for VA, IPS and OCB modes, which has a liquid crystal cell accurately optically compensated and improves color shift depending on the viewing angle direction during high contrast and black display, A production method and a polarizing plate using the cellulose acylate film are provided. In addition, according to the present invention, there is provided a liquid crystal display device particularly in VA, IPS and OCB modes in which the contrast is improved and the color shift depending on the viewing angle direction during black display is improved.

Claims (16)

The ratio Re / Rth of the retardation value Re in the film plane and the retardation value Rth in the film thickness direction increases as the wavelength increases in the visible wavelength range, and Re increases as the wavelength increases in the visible wavelength range. An optical film comprising at least one humidity dependency improving agent for improving the humidity dependency ΔRe of Re of the optical film represented by the following formula (1):
Formula (1): Hu dependency of optical film on humidity ΔRe (nm)
= | Re (550) 10% RH-Re (550) 80% RH |
(In the above formula, Re (550) 10% RH and Re (550) 80% RH are Re at a wavelength of 550 nm at 25 ° C. and a relative humidity of 10%, respectively, and Re at a relative humidity of 80% RH.)   The optical film according to claim 1, further comprising at least one polymer. When the mass of the polymer in the optical film is 100 parts by mass, the content of the humidity-dependent improving agent is the humidity dependence ΔRe (A) of Re of the optical film of A part by mass, and the content is The optical film according to claim 2, wherein the humidity dependency ΔRe (0) of Re of the optical film of 0 part by mass satisfies the following formula (2).
Formula (2): | ΔRe (A) −ΔRe (0) | / A ≧ 1 (nm / part by mass) 4. The optical film according to claim 1, wherein the retardation value satisfies the following formulas (Ia), (Ib), (II), (III) and (A).
Formula (Ia): 0.4 <{(Re (450) / Rth (450)) / (Re (550) / Rth (550))} <0.95, and Formula (Ib): 1.05 <{ (Re (650) / Rth (650)) / (Re (550) / Rth (550))} <1.9
Formula (II): 0.1 <(Re (450) / Re (550)) <0.95
Formula (III): 1.03 <(Re (650) / Re (550)) <1.93
(In the formulas (Ia), (Ib), (II) and (III), Re (λ) is the in-plane retardation Re (unit: nm) in the light of wavelength λnm, and Rth (λ) is Retardation Rth in the film thickness direction (unit: nm).)
Formula (A): 10 ≧ | Re (550) 10% RH-Re (550) 80% RH |
(In the formula (A), Re (550) 10% RH and Re (550) 80% RH are Re (550) at 25 ° C., 10% and 80% RH, respectively.) The optical film according to claim 1, wherein the humidity dependency improving agent is a compound containing at least two hydrogen bonding groups. A method for producing an optical film comprising a step of stretching a film at a stretch ratio of X% and a step of shrinking the film at a shrinkage ratio of Y%, wherein the relationship between the stretch ratio of X% and Y% is represented by the following formula (Z) And the film further contains a humidity dependency improving agent which is a compound containing at least two hydrogen bonding groups.
Formula (Z)

  The optical film in any one of Claims 1-5 manufactured by the manufacturing method of the optical film of Claim 6. The optical film according to claim 1, wherein Re (550) is in the range of 20 to 100 nm and Rth (550) is in the range of 100 to 300 nm.
(Re (550) is the in-plane retardation Re (unit: nm) for light having a wavelength of 550 nm, and Rth (550) is the retardation Rth (unit: nm) in the film thickness direction for light having a wavelength of 550 nm.)   The optical film according to claim 1, wherein the optical film contains cellulose acylate. When the substitution degree of the 2-position hydroxyl group of the cellulose acylate with an acyl group is DS2, the substitution degree of the 3-position hydroxyl group with an acyl group is DS3, and the substitution degree of the 6-position hydroxyl group with an acyl group is DS6, The optical film according to claim 9, wherein the following formulas (IV) and (V) are satisfied.
Formula (IV): 2.0 ≦ (DS2 + DS3 + DS6) ≦ 3.0
Formula (V): DS6 / (DS2 + DS3 + DS6) ≧ 0.315 The optical film according to claim 9 or 10, comprising cellulose acylate satisfying the following formulas (VI) and (VII).
Formula (VI): 2.0 ≦ A + B ≦ 3.0
Formula (VII): 0 <B
(In the formulas (VI) and (VII), A represents the degree of substitution of the hydroxyl group of the glucose unit of the cellulose acylate with an acetyl group, and B represents the propionyl group, butyryl group or benzoyl group of the glucose unit of the cellulose acylate. The degree of substitution by.)   The optical film according to any one of claims 1 to 5 and 7 to 11, further comprising a retardation developer.   It is a polarizing plate which has a polarizing film and a pair of protective film which pinches | interposes this polarizing film, Comprising: At least 1 sheet of the said protective film is an optical film in any one of Claims 1-5, 7-12. A polarizing plate characterized by that.   A liquid crystal display device comprising the optical film according to claim 1 or the polarizing plate according to claim 13.   A liquid crystal display device having a liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell, wherein the polarizing plate is the polarizing plate according to claim 13. Mode liquid crystal display.   A VA mode liquid crystal display device comprising the polarizing plate according to claim 13 on a backlight side.