JP2007304256A - Optical compensation film, polarizing plate and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensation film which allows an optical characteristic after saponification that exhibit no fluctuations or less amount of variation, in response to saponification condition and has high versatility as a member of elliptically polarizing plate or a liquid crystal display. <P>SOLUTION: The optical compensation film comprises an optical anisotropic layer, made of a composition containing at least a liquid crystalline compound on a plastic film, wherein both the change amounts of in-plane retardation Re and retardation Rth in the thickness direction of the optical anisotropic layer, after dipping the optical compensation film in an aqueous solution of sodium hydroxide 1.5 mol/L at 55°C for two min are smaller than 5 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical compensation film and a polarizing plate that contribute to improving the visibility and viewing angle of a liquid crystal display device, and the present invention also relates to a liquid crystal display device having improved visibility and viewing angle.

  As a liquid crystal display device, a so-called TN mode, in which a liquid crystal layer in which nematic liquid crystal is twisted and arranged between two orthogonal polarizing plates, and an electric field is applied in a direction perpendicular to the substrate is widely used. In this method, since the liquid crystal rises with respect to the substrate during black display, birefringence due to the liquid crystalline compound occurs when viewed from an oblique direction, and light leakage occurs. In order to solve this problem, a system in which a liquid crystal cell is optically compensated and a light leakage is prevented by using a film in which liquid crystal compounds are hybrid-aligned has been put into practical use. However, even if a liquid crystal compound is used, it is very difficult to completely optically compensate the liquid crystal cell without any problem, and there is a problem that gradation inversion in the lower direction of the screen cannot be suppressed.

  In order to solve such a problem, a liquid crystal display device using a so-called IPS mode or FFS mode in which a lateral electric field is applied to the liquid crystal, a protrusion formed in the panel by vertically aligning a liquid crystal having a negative dielectric anisotropy, A vertical alignment (VA) mode in which alignment is divided by a slit electrode has been proposed and put into practical use. In recent years, these panels have been developed not only for monitor applications but also for TV applications, and screen brightness has been greatly improved accordingly. For this reason, slight light leakage in the diagonally oblique incidence direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of deterioration in display quality.

  As one means for improving the color tone and the viewing angle of black display, disposing an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS and FFS modes. For example, by arranging a birefringent medium having an optical axis orthogonal to each other to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting, a white display or a halftone display is diagonally arranged between the substrate and the polarizing plate. It is disclosed that coloring can be improved when viewing directly from (see Patent Document 1). In addition, as a method using an optical compensation film made of a styrene polymer having a negative intrinsic birefringence or a discotic liquid crystalline compound (see Patent Documents 2, 3, and 4), the optical compensation film has a positive birefringence and an optical axis. A method of combining a film in the plane of a film with a film having positive birefringence and an optical axis in the normal direction of the film (see Patent Document 5), biaxial optical compensation film having a retardation of half wavelength Using a film having a negative retardation as a protective film of a polarizing plate and providing an optical compensation layer having a positive retardation on this surface (see Patent Document 7) Has been.

  Patent Document 8 proposes an IPS liquid crystal device in which a compensation film in which a rod-like liquid crystal is applied and oriented on a biaxial cellulose acylate film produced by stretching is mounted. In this method, the display quality and viewing angle are remarkably improved with a simple configuration.

In particular, the method described in Document 8 uses a cellulose acylate film as a base material in an optical compensation film, and can be used as a protective film for a polarizing plate when mounted on a liquid crystal display device. This is very preferable because the optical loss can be reduced as compared with a configuration in which the apparatus is thinned and a polarizing plate protective film is required.
By the way, when an optical compensation film comprising a cellulose acylate film as a base material and an optically anisotropic layer laminated is used as a protective film for a polarizing plate, the cellulose acylate film surface needs to be hydrophilized and saponified by immersion in an alkaline aqueous solution. In general, processing is performed. However, the present inventors have clarified that the optical characteristics of the optically anisotropic layer vary depending on the saponification conditions, and that the variation range is large in the optically anisotropic layer formed of the rod-like liquid crystal.
The saponification treatment is currently performed by several polarizing plate manufacturers under unique conditions. Under these circumstances, this problem can be solved by designing an optical compensation film that takes into account changes in optical properties due to saponification. It is difficult to do.

In Patent Document 9, in an optical compensation film having an optically anisotropic layer in which the alignment state of liquid crystalline molecules is fixed on a transparent support, the film thickness of the optically anisotropic layer before and after the hydrophilic treatment is specified. Discloses a method for accurately realizing optical characteristics as designed.
Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 JP 11-133408 A JP-A-11-305217 JP-A-10-307291 JP 2005-265889 A JP 2005-275394 A

In view of the above, an object of the present invention is to provide an optical compensation film having high versatility as a member of an elliptically polarizing plate or a liquid crystal display device, in which the optical properties after saponification do not vary or change little according to saponification conditions. provide. Moreover, this invention makes it a subject to provide the polarizing plate which can be produced stably by using this optical compensation film.
Another object of the present invention is to provide a liquid crystal display device having a simple configuration and excellent viewing angle characteristics.

Means for solving the above-mentioned problems are as follows.
[1] An optical compensation film having an optically anisotropic layer made of a composition containing at least a liquid crystal compound on a plastic film, wherein the optical compensation film is placed in a 1.5 mol / L sodium hydroxide aqueous solution. The optical compensation film is characterized in that after immersion for 2 minutes at 55 ° C., the amount of change in both the in-plane retardation Re and the thickness direction retardation Rth of the optically anisotropic layer is 5 nm or less.
[2] The optical compensation film according to [1], wherein the absolute value of at least one of Re and Rth of the optically anisotropic layer is 20 nm or more.
[3] The liquid crystal compound has a polymerizable group, and the optically anisotropic layer is a layer formed by aligning molecules of the liquid crystal compound having the polymerizable group and then fixing by polymerization. The optical compensation film according to [1] or [2], wherein
[4] The optical compensation film according to any one of [1] to [3], wherein the liquid crystal compound is a polymerizable liquid crystal compound having 1 to 3 functional polymerizable groups per molecule.
[5] The optical compensation film according to any one of [1] to [4], wherein the liquid crystal compound is a rod-like liquid crystal compound.
[6] The optical compensation film according to [5], wherein in the optically anisotropic layer, the molecules of the rod-like liquid crystalline compound are fixed in a vertical alignment or horizontal alignment state.
[7] The optical system according to any one of [1] to [6], wherein the liquid crystal compound is a compound that does not contain a divalent group that can be cleaved by hydrolysis or contains only one of the liquid crystal parts. Compensation film.
[8] A condensed ring structure in which the liquid crystalline compound includes a divalent group that can be cleaved by hydrolysis at a liquid crystalline site, and at least one group connected through the divalent group is composed of two or more rings. The optical compensation film according to any one of [1] to [7], which is a compound comprising:
[9] The optical compensation film of [7] or [8], wherein the linking group cleavable by hydrolysis is an ester group (—C (═ (O) O—).
[10] The film according to [1] to [9], wherein the polymer film is a film formed by a transverse uniaxial stretching method, a longitudinal uniaxial stretching method, a simultaneous biaxial stretching method, or a sequential biaxial stretching method. Any optical compensation film.
[11] The optical compensation film according to any one of [1] to [10], wherein the polymer film is a cellulose acylate film.
[12] A polarizing plate comprising the optical compensation film according to any one of [1] to [11].
[13] A liquid crystal display device comprising the optical compensation film of any one of [1] to [11] or the polarizing plate of [12].

  According to the present invention, an optical compensation film having high versatility can be provided as a member of an elliptically polarizing plate or a liquid crystal display device, in which the optical properties after saponification do not vary depending on the saponification conditions, or the amount of change is small. Moreover, this invention can provide the polarizing plate which can be produced stably by using this optical compensation film. Furthermore, according to the present invention, it is possible to provide a liquid crystal display device having a simple configuration and excellent viewing angle characteristics.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, an embodiment of the liquid crystal display device of the present invention and its constituent members will be described in order. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the present specification, “parallel” and “orthogonal” mean that the angle is within a range of strictly less than ± 10 °. In this range, an error from a strict angle is preferably less than ± 5 °, and more preferably less than ± 2 °. “Substantially parallel”, “substantially orthogonal”, and “substantially vertical” have the same meaning. Further, the “slow axis” means a direction in which the refractive index is maximized. Further, the measurement wavelength of the refractive index and the phase difference is a value at λ = 590 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. “Polarizing plate” means a laminate having a transparent protective film for protecting the polarizing film on at least one surface of the “polarizing film”. It shall be.
In the present specification, the description “(meth) acrylate” means “at least one of acrylate and methacrylate”. The same applies to “(meth) acrylic acid” and the like.

In this specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re (λ) is measured by making light having 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) (in the absence of the slow axis, any in-plane value) The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the 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 its 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), Rth can also be calculated from the following formula (1) and formula (2) based on the value, the assumed value of the average refractive index, and the input film thickness value.

式（２）
Ｒｔｈ＝（（ｎｘ＋ｎｙ）／２−ｎｚ）×ｄ
注記：上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値を表す。
式中、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘ及びｎｙに直交する方向の屈折率を表す。

Formula (2)
Rth = ((nx + ny) / 2−nz) × d
Note: The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In the formula, 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.

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 optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is the above-mentioned Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) from −50 degrees to +50 degrees with respect to the film normal direction. The light of wavelength λ nm is incident from each inclined direction in 10 degree steps and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the input film thickness value, KOBRA 21ADH or WR is calculated.
In the above measurement, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz.
In this specification, unless otherwise specified, the measurement wavelength is 590 nm, and the measurement value is 25 ° C. and 60% RH.

[Optical compensation film]
The present invention relates to an optical compensation film having an optically anisotropic layer made of a composition containing at least a liquid crystal compound on a plastic film, the optical compensation film comprising a 1.5 mol / L sodium hydroxide aqueous solution. The present invention relates to an optical compensation film in which the amount of change in both in-plane retardation and thickness direction retardation Rth of the optically anisotropic layer is 5 nm or less after being immersed for 2 minutes at 55 ° C.
First, the outline of the present invention will be described below.
[Summary of Invention]
As a result of intensive studies, the present inventor has found that an optical compensation film having a small retardation fluctuation value when subjected to saponification treatment under a predetermined condition is subjected to lettering even when saponification treatment is performed more slowly or more severely. The knowledge that the fluctuation value of the foundation is small was obtained, and the present invention was completed. As described above, when a polarizing plate manufacturer attaches a predetermined optical compensation film to a polarizing film to produce an elliptical polarizing plate or the like, there are various conditions for the saponification treatment applied to the optical compensation film. The optical compensation film of the present invention is highly versatile as a member of an elliptically polarizing plate or a liquid crystal display device because the change in optical properties due to fluctuations in saponification conditions is small.

  The optical compensation film of the present invention was immersed in an aqueous 1.5 mol / L sodium hydroxide solution at 55 ° C. for 2 minutes, and then either of in-plane retardation of the optical anisotropic layer and retardation Rth in the thickness direction. The amount of change is also 3 nm or less. The amount of change in retardation after saponification treatment under such conditions is preferably 2 nm or less, more preferably 1 nm or less, and most preferably no change at all.

  Furthermore, as a result of extensive studies by the inventor, the optically anisotropic layer formed by curing a composition containing a polymerizable liquid crystal compound, particularly a polymerizable rod-like liquid crystal compound, is subjected to a saponification process. As a result of further investigation, the liquid crystal compound is hydrolyzed and a part of the liquid crystal part (mesogen group) is eluted in the saponification solution, and the optical characteristics fluctuate. The knowledge that this elution can be remarkably reduced by using a liquid crystalline compound having structural characteristics has been obtained, and the present invention has been completed.

Hereinafter, each component of the optical compensation film of the present invention will be described in detail.
[Optically anisotropic layer]
In the optical compensation film of the present invention, the optically anisotropic layer is formed from a composition containing a liquid crystalline compound. The optically anisotropic layer is preferably formed on an alignment film formed on a polymer film.
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. The liquid crystal compound may be a polymer liquid crystal. Furthermore, when an optically anisotropic layer is formed using a low molecular liquid crystal, it is of course possible that the low molecular liquid crystal is crosslinked in the layer and does not exhibit liquid crystallinity. An optically anisotropic layer formed using a rod-like liquid crystal compound generally tends to have a larger retardation change due to saponification than an optically anisotropic layer formed using a polymerizable discotic liquid crystal compound. By using a rod-like liquid crystalline compound having a predetermined structural feature described later, fluctuations in optical characteristics due to saponification treatment of the optically anisotropic layer can be reduced.

As described above, when the optically anisotropic layer formed by curing a composition containing a liquid crystalline compound is saponified by the study of the present inventors, the liquid crystalline compound is hydrolyzed and partly eluted. It has been found that this is one of the causes of fluctuations in optical characteristics. Therefore, the liquid crystal compound is preferable so as not to include a divalent group (for example, an ester group (—C (═ (O) O—)) that is cleaved by hydrolysis at the liquid crystalline portion, or does not include at all, or In the case where it contains a divalent group that is cleaved by hydrolysis, at least one of the groups linked via the divalent group has a condensed structure of two or more rings. It is preferable that two or more condensed rings are directly bonded to the divalent group by forming an optically anisotropic layer using a liquid crystalline compound having such a structure. There are no particular restrictions on the condensed ring of two or more rings, and non-aromatic heterocycles such as cyclohexane rings and piperidine rings. Aromatic carbon rings such as rings and benzene rings, and Any of condensed rings composed of a combination of two or more of the same or different kinds of rings selected from aromatic hetero rings such as a pyridine ring may be used, for example, naphthalene ring, tetrahydronaphthalene ring, fluorene ring, bicyclohexane ring However, it is not limited to these.
In the present specification, the “liquid crystalline part” refers to a residue of the liquid crystalline compound excluding the polymerizable group at the terminal.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Among them, compounds containing cyanophenyl esters and benzoic acid esters are preferable because they are easily hydrolyzed and eluted in an alkaline solution.
Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. It is more preferable to fix the alignment of the rod-like liquid crystal compound by polymerization. As the liquid crystalline compound, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are suitably used. The number of the partial structures is preferably 1 to 6, more preferably 1 to 3. As the polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081, JP 2001-328773, JP 2004-240188, JP 2005-99236, JP 2005-99237, JP 2005-121827, JP It is possible to use the compounds described in 2002-30042 That.

  In order to fix the rod-like liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group to the liquid crystalline portion of the rod-like liquid crystalline compound. The number of polymerizable groups per molecule is preferably 1 to 6, more preferably 1 to 3, and particularly preferably 1 to 2.

  The liquid crystal compound may be selected from a polymerizable rod-like liquid crystal compound represented by the following formula (1).

In formula (1), Z ^{1 to} Z ⁴ are divalent linking groups, and A ^{1 to} A ⁴ are groups containing a substituted or unsubstituted aromatic ring or a saturated or unsaturated cycloolefin ring. P ¹ is a group having polymerization ability, R ¹ is a terminal group, and when the rod-like liquid crystal compound represented by the formula (1) is a bifunctional compound, R ¹ is a group having polymerization ability.
In the present invention, among Z ^{1 to} Z ⁴ which are divalent linking groups, the number of groups cleavable by hydrolysis such as ester groups is preferably 2 or less, more preferably 1 or less, Most preferably, it is zero.

The linking group represented by Z ⁴ is an alkylene group having 1 to 20 carbon atoms, or any —CH ₂ — in the alkylene group having 1 to 20 carbon atoms is —O—, —S—, —CO—, -COO-, -OCO-, -OCOO-, -CO-NR-, -NR-CO-, -NR-, -CH = N-, -N = CH-, -O-CO-NR-, -NR A divalent group substituted by —CO—NR—, —CH═CH—, or —C≡C— is preferred (where R represents H or an alkyl group having 1 to 4 carbon atoms). The alkylene group or the substituted alkylene group preferably has 1 to 10 carbon atoms, and more preferably has 3 to 10 carbon atoms. Linking group represented by Z ⁴ is preferably a group represented by any one of the following formulas ^{(Z 4 -1) (Z 4} -6).

In the formulas (Z ⁴ -1) to (Z ⁴ -6), r represents an integer of 1 to 10, and s and t represent an integer of 2 to 5. In the formulas (Z ⁴ -1) to (Z ⁴ -6), the formula (Z ⁴ -2), (Z ⁴ -3), (Z ⁴ -4) or (Z ⁴ -5) is preferable. (Z ⁴ -2) and (Z ⁴ -5) are particularly preferable because the bonds are hardly broken by hydrolysis.

In the formula (1), P ¹ is preferably any of groups having polymerization ability represented by the following formulas (P ¹ -1) to (P ¹ -6), and (P ¹ -1), (P ¹ -5) and more preferably or (P ¹ -6).

X is a hydrogen atom, a halogen atom, —CF ₃ , or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom, a fluorine atom, —CF ₃ , or an alkyl group having 1 to 2 carbon atoms.

In Formula (1), R ¹ is an alkyl group having 1 to 20 carbon atoms or an arbitrary —CH ₂ — of an alkyl group having 1 to 20 carbon atoms, —O—, —S—, —CO—, —COO—, -OCO-, -CH = CH-, -CF = CF-, or a group replaced by -C≡C-, a hydrogen atom, a halogen atom, -CN, -N = C = O, -N = C = S Or -Z ⁴ -P ¹ is preferred. Any hydrogen atom in the alkyl group or the substituted alkyl group may be replaced with a halogen atom, —CF ₃ or —CN.

More preferable examples of R ¹ include a hydrogen atom, a halogen atom, —CN, —CF ₃ , —CF ₂ H, —CFH ₂ , —OCF ₃ , —OCF ₂ H, a linear alkyl group having 1 to 10 carbon atoms. , A linear alkoxy group having 1 to 10 carbon atoms, a linear alkoxyalkyl group having 2 to 10 carbon atoms, a linear alkenyl group having 2 to 10 carbon atoms, or —Z ⁴ —P ¹ , and Z ⁴ And P ^{1 has} the same meaning as described above.

More preferable examples of R ¹ include a hydrogen atom, —F, —Cl, —CN, —CF ₃ , —CF ₂ H, —CFH ₂ , —OCF ₃ , —OCF ₂ H, —CH ₃ , —C ₂ H. _{5, -C 3 H 7, -C} 4 H 9, -C 5 H 11, -C 6 H 13, -C 7 H 15, -C 8 H 17, -OCH 3, -OC 2 H 5, -OC _{3 H 7, -OC 4 H 9} , -OC 5 H 11, -OC 6 H 13, -OC 7 H 15, -OC 8 H 17, -CH 2 OCH 3, -CH 2 OC 2 H 5, -CH _{2 OC 3 H 7, -CH 2} OC 4 H 9, -C 2 H 5 OCH 3, -C 2 H 5 OC 2 H 5, -C 2 H 5 OC 3 H 7, -C 3 H 6 OCH 3, _{-C 3 H 6 OC 2 H 5} , -C 3 H 6 OC 3 H 7, -CH 2 CH 2 F, -C 2 H 4 CH 2 F, -CH = CH 2, -CH = CHCH 3, -CH ₂ CH═CH ₂ , allyl, —C ₂ H ₄ CH═CH ₂ , —C ₂ H ₄ CH═CHCH ₃ , —Z ⁴ —P ¹ or the like, and Z ⁴ and P ¹ are as defined above.

R ¹ may be an alkyl group having an asymmetric carbon atom. In that case, the liquid crystal compound represented by the formula (1) has optical activity. Examples of alkyls having asymmetric carbon atoms are 2-methylbutyl, 2-methylpentyl, 2-methylhexyl, 2-methylheptyl, 2-methyloctyl, 2-methyl-1-butenyl, 2-methyl-1-pentenyl 2-methyl-1-hexenyl, 2-methyl-1-heptenyl, 2-methyl-1-octenyl, 2-methylbutoxy, 2-methylpentyloxy, 2-methylhexyloxy, 2-methylheptyloxy, 2- Examples include methyloctyloxy, 2-methylbutoxycarbonyl, 2-methylpentyloxycarbonyl, 2-methylhexyloxycarbonyl, 2-methylheptyloxycarbonyl, 2-methyloctyloxycarbonyl and the like.

A ¹ , A ² , A ³ , and A ⁴ in formula (1) are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-2,6- Diyl, tetrahydronaphthalene-2,6-diyl, fluorene-2,7-diyl, bicyclo [2.2.2] octane-1,4-diyl, or bicyclo [3.1.0] hexane-3,6- Diyl and bicyclo [4.4.0] decane are preferred. In these rings, arbitrary —CH ₂ — may be replaced by —O—, and arbitrary —CH═ may be replaced by —N═. However, it is preferable that two adjacent —CH ₂ — are not replaced like —O—O—. Examples in which —CH ₂ — is replaced by —O— in 1,4-cyclohexylene are 1,3-dioxane-2,5-diyl and 1,4-dioxane-2,5-diyl. Examples where -CH = is replaced by -N = in 1,4-phenylene are pyridine-2,5-diyl, pyrimidine-2,5-diyl and pyridazine-3,6-diyl. And any hydrogen atom in all cyclic groups including these rings is a halogen atom, alkyl having 1 to 5 carbon atoms, fluoroalkyl having 1 to 5 carbon atoms, alkoxy having 1 to 5 carbon atoms, or carbon. It may be replaced by alkenyl having 2 to 5 atoms. A preferred halogen atom is a fluorine atom. By containing a fluorine atom, it becomes hydrophobic and it is difficult for a hydroxide ion to enter during saponification, and it becomes difficult to be hydrolyzed after curing.

It is preferable that A ¹ , A ² , A ³ , or A ⁴ is a group having a condensed ring structure of two or more rings among the above-mentioned groups, which is less susceptible to hydrolysis after curing. In particular, when Z ¹ or the like bonded to each is a group that is cleaved by hydrolysis such as an ester group, it is particularly preferable that either one is a group having a condensed ring structure of two or more rings. . Preferred examples of the condensed ring include, but are not limited to, a naphthalene ring, a tetrahydronaphthalene ring, a fluorene ring, and a bicyclohexane ring.

In formula (1), Z ¹ , Z ² and Z ³ are each independently a single bond, or an arbitrary —CH ₂ — of an alkylene group having 1 to 20 carbon atoms or an alkylene group having 1 to 20 carbon atoms is —O—. , -S-, -COO-, -OCO-, -CH = CH- or -C≡C-, preferably represents a divalent group. In the alkylene group or substituted alkylene group, any hydrogen atom may be replaced with a halogen atom. The alkylene group or the substituted alkylene group preferably has 1 to 10 carbon atoms. Preferred examples of Z ¹ , Z ² or Z ³ are a single bond, —CH═CH—, —C≡C—, —COO—, —OCO—, — (CF ₂ ) ₂ —, —C≡C—COO. -, - OCO-C≡C -, - CH = CH- (CH 2) 2 -, - (CH 2) 2 -CH = CH -, - CF = CF -, - C≡C-HC = CH-, —CH═CH—C≡C—, —OCF ₂ —, —CF ₂ O—, or an alkylene group having 1 to 20 carbon atoms. More preferred alkylene groups have 1 to 10 carbon atoms.

More preferred examples of Z ¹ , Z ² or Z ³ are a single bond, — (CH ₂ ) ₂ —, —OCH ₂ —, —CH ₂ O—, — (CH ₂ ) _a —, —O (CH ₂ ). _{a -, - (CH 2)} a O -, - O (CH 2) a O -, - CH = CH -, - (CH 2) 4 -, - CF = CF -, - OCF 2 -, or -CF ₂ O-. Furthermore, Z ¹ , Z ² or Z ³ is preferably a single bond, — (CH ₂ ) ₂ —, —CH═CH—, —CF═CF—, —OCF ₂ —, or —CF ₂ O—. . In these linking groups, the double bond is preferably trans rather than cis.

  In the formula (1), m, n and q are each independently 0, 1 or 2. When the sum of m, n, and q is 0, the compound represented by the formula (1) is a compound having one ring structure. From the viewpoint of the liquid crystal phase temperature range, the ring structure has two or more ring structures. A condensed ring composed of a ring is desirable. When the sum of m, n and q is 1, the compound represented by the formula (1) is a compound having two ring structures. When the sum is 2 and 3, the compound represented by the formula (1) is a compound having three ring structures and a compound having four ring structures, respectively. In order to set the liquid crystal phase temperature range to the low temperature side, a compound having two ring structures may be selected. When it is desired to set the liquid crystal phase temperature range to a relatively high temperature side, a compound having three ring structures or a compound having four ring structures may be selected. When it is desired to set the liquid crystal phase temperature range to a higher temperature side, a compound in which the sum of m, n and q is 4, 5 or 6 may be selected.

  The compound represented by the formula (1) has a ring structure of 1 to 7, and preferably has a ring structure of 2 to 5. That is, compounds represented by the following formulas (1-A) to (1-D) are preferable.

When R ¹ is not —Z ⁴ —P ¹ , it is a monofunctional compound. When R ¹ is —Z ⁴ —P ¹ , it is a bifunctional compound having a polymerizable group at both ends of the molecule. The bifunctional compound exhibits higher polymerizability than the monofunctional compound. That is, the bifunctional compound has a higher polymerization rate, completes the polymerization in a shorter time, and a polymer having a higher degree of polymerization can be obtained. The obtained polymer has higher heat resistance, lower water absorption, water permeability and gas permeability, and higher mechanical strength (particularly hardness), which is preferable.
Among the bifunctional compounds, liquid crystalline di (meth) acrylate compounds are particularly preferable.

Furthermore, the formulas (1-A) to (1-D) can be embodied into preferable formulas such as the following examples. In the following formulas, R ¹ , Z ¹ , Z ² , Z ³ and Z ⁴ have the same meaning as these symbols in formula (1), and 1,4-cyclohexylene, 1,4-phenylene, 1, Groups representing 4-cyclohexenylene, pyridine-2,5-diyl, naphthalene-2,6-diyl, tetrahydronaphthalene-2,6-diyl, and fluorene-2,7-diyl are each represented by the following formula: Represents the group

  Of the above, Formula (1-1) to Formula (1-8), Formula (1-11) to Formula (1-18), or Formula (1-20) to Formula (1-60) are more preferable. (1-1) to Formula (1-2), Formula (1-4) to Formula (1-5), Formula (1-11) to Formula (1-16), Formula (1-30) to Formula ( 1-36), Formula (1-49) to Formula (1-50), Formula (1-56) to Formula (1-58), or Formula (1-60) is more preferable.

[Disc liquid crystalline compound]
In the present invention, the optically anisotropic layer can also be formed using a discotic liquid crystal compound.
Examples of the discotic liquid crystalline compound 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, page 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), and azacrown and phenylacetylene macrocycles.

The discotic liquid crystalline compound is a compound having a general molecular structure in which a linear alkyl group, an alkoxy group, or a substituted benzoyloxy group is substituted radially with respect to the mother nucleus at the molecular center. , Showing liquid crystallinity. Further, in the optically anisotropic layer formed from the discotic liquid crystalline compound, the substance contained in the final layer does not need to be the compound. For example, a low-molecular discotic liquid crystalline compound has a group that reacts with heat or light, and as a result, it may be polymerized or cross-linked by reaction with heat or light to increase the molecular weight and lose liquid crystallinity.
Examples of the discotic liquid crystalline compound are described in JP-A-8-50206. The polymerization of the discotic liquid crystalline compound is described in JP-A-8-27284.

  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, a linking group is introduced between the discotic core and the polymerizable group. Accordingly, the discotic liquid crystalline compound having a polymerizable group is preferably represented by the following formula (I).

(I) D (-LQ) _n
Where D is a discotic core; L is a divalent linking group, Q is a polymerizable group, and n is an integer from 4-12.
An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

  In the formula (I), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. A divalent linking group is preferred. The divalent linking group (L) is a divalent group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, —CO—, —NH—, —O—, and —S— are combined. More preferably, it is a linking group. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. . The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6-10.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group).
L1: -AL-CO-O-AL-
L2: -AL-CO-O-AL-O-
L3: -AL-CO-O-AL-O-AL-
L4: -AL-CO-O-AL-O-CO-
L5: -CO-AR-O-AL-
L6: -CO-AR-O-AL-O-
L7: -CO-AR-O-AL-O-CO-
L8: -CO-NH-AL-
L9: -NH-AL-O-
L10: -NH-AL-O-CO-

L11: -O-AL-
L12: -O-AL-O-
L13: -O-AL-O-CO-
L14: -O-AL-O-CO-NH-AL-
L15: -O-AL-S-AL-
L16: -O-CO-AR-O-AL-CO-
L17: -O-CO-AR-O-AL-O-CO-
L18: -O-CO-AR-O-AL-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L20: -S-AL-
L21: -S-AL-O-
L22: -S-AL-O-CO-
L23: -S-AL-S-AL-
L24: -S-AR-AL-

  Of the divalent linking groups, linking groups that are difficult to be cleaved by hydrolysis are preferred, and among these, L5 to L6, L9, L12, L15, and L20 to L21 are preferred.

Examples of the polymerizable group (Q) of the formula (I) are shown below.

The polymerizable group is preferably an unsaturated group (Q1 to Q7) or an epoxy group (Q8), more preferably an unsaturated group, and most preferably an ethylenically unsaturated group (Q1 to Q6). preferable.
In the formula (I), n is an integer of 4 to 12. A specific number is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  When the discotic liquid crystalline compound is used, the optically anisotropic layer can be formed by fixing the molecules of the discotic liquid crystalline compound vertically or horizontally and then fixing the molecules. By fixing after vertical alignment, the optically anisotropic layer can be a negative A plate. Moreover, the optically anisotropic layer can be made into a negative C plate by fixing after horizontal alignment. By applying the alkali solution treatment of the present invention to the optically anisotropic layer, only the retardation value can be adjusted without changing the optical axis.

  When a discotic liquid crystal compound is used, the plane of the discotic structural unit is inclined with respect to the polymer film surface, and the angle between the discotic structural unit surface and the polymer film surface is the depth of the optically anisotropic layer. It is also a preferred embodiment of the present invention to use an optically anisotropic layer having a structure that changes in the direction.

[Additive]
In the optically anisotropic layer, the liquid crystalline compound is preferably fixed. It may be fixed in any liquid crystal state, for example, any of a vertical alignment state and a horizontal alignment state. In order to bring the molecules of the liquid crystal compound into a desired alignment state, an alignment accelerator may be added to the composition. Moreover, when fixing by superposition | polymerization, you may add polymeric monomers, such as a polymerization initiator and a crosslinking agent, in a composition. Hereinafter, additives that can be used in the present invention will be described.
(Vertical alignment accelerator)
In order to uniformly align the liquid crystalline compound vertically, it is necessary to vertically control the alignment of the liquid crystalline compound on the alignment film interface side and the air interface side. For this purpose, a composition obtained by adding a compound having an effect of vertically aligning the liquid crystalline compound by an excluded volume effect, an electrostatic effect, or a surface energy effect to the alignment film may be employed. In addition, with regard to alignment control on the air interface side, a compound that is unevenly distributed at the air interface during alignment of the liquid crystalline compound and acts to align the liquid crystalline compound vertically by its excluded volume effect, electrostatic effect, or surface energy effect is blended The liquid crystal composition may be used. As such a compound (alignment film interface side vertical alignment agent) that promotes the vertical alignment of the molecules of the liquid crystal compound on the alignment film interface side, a pyridinium derivative is preferably used. As a compound (air interface side vertical alignment agent) that promotes the vertical alignment of the molecules of the liquid crystal compound on the air interface side, a fluoro aliphatic group that promotes the uneven distribution of the compound on the air interface side, One or more hydrophilic groups selected from the group consisting of a carboxyl group (—COOH), a sulfo group (—SO ₃ H), a phosphonoxy group {—OP (═O) (OH) ₂ }, and salts thereof. A compound is preferably used. Further, by blending these compounds, for example, when a liquid crystalline composition is prepared as a coating solution, the coating property of the coating solution is improved, and the occurrence of unevenness and repellency is suppressed.

(Polymerization initiator)
The aligned liquid crystalline compound can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

(Other additives for optically anisotropic layers)
Along with the liquid crystal compound, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal compound, and the like. These materials are preferably compatible with the liquid crystal compound and do not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. 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 discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in paragraphs [0028] to [0056] in JP-A No. 2001-330725, and compounds described in paragraphs [0069] to [0126] in Japanese Patent Application No. 2003-295212. Is mentioned.

  The polymer used together with the liquid crystal compound is preferably capable of thickening the coating solution. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecules so as not to inhibit the alignment of the liquid crystal compound. It is more preferable.

[Formation of optically anisotropic layer]
The optically anisotropic layer is formed using, for example, a composition containing a liquid crystal compound and additives such as a polymerization initiator and an alignment accelerator that are optionally added. The composition may be prepared as a coating solution in which the above materials are dissolved and / or dispersed in a solvent. The coating solution can be formed by coating on the surface of the support. It is preferable to form an alignment film on a support and apply the coating solution on the surface of the alignment film. As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

(Application method)
The coating liquid can be applied by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method). Especially, when forming the said optically anisotropic layer, it is preferable to apply | coat using a wire bar coating method, and it is preferable that the rotation speed of a wire bar satisfy | fills a following formula.
0.6 <(W × (R + 2r) × π) / V <1.4
[W: Number of revolutions of wire bar (rpm), R: Diameter of bar core (m), r: Diameter of wire (m), V: Conveying speed of support (m / min)]
The range of (W × (R + 2r) × π) / V is more preferably 0.7 to 1.3, and still more preferably 0.8 to 1.2.

  For forming the optically anisotropic layer, a die coating method is preferably used, and a coating method using a slide coater or a slot die coater is particularly preferable. For example, the coating methods described in JP-A No. 2004-290775, JP-A No. 2004-290776, JP-A No. 2004-358296, JP-A No. 2005-13989, and the like can be used.

Next, as described above, after coating the composition on the surface of the support such as a polymer film or the alignment film, the molecules of the liquid crystalline compound are aligned (preferably vertical alignment or horizontal alignment for rod-shaped liquid crystalline molecules). Thus, the optically anisotropic layer may be formed by fixing the molecules in the orientation state. The alignment temperature can be determined in consideration of the transition temperature of the liquid crystal compound to be used, the desired alignment state, and the like. The immobilization is preferably carried out by a polymerization reaction or a crosslinking reaction of liquid crystalline molecules or a polymerizable monomer that is optionally added to the composition. It is preferable to use ultraviolet rays for light irradiation for polymerization. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

In the present invention, it is preferable to increase the degree of curing of the outermost layer portion of the optically anisotropic layer. When the optically anisotropic layer is formed by a crosslinking or polymerization reaction of an ionizing radiation curable compound, the oxygen concentration is 4% by volume or less. It is preferable to carry out in an atmosphere. Furthermore, the oxygen concentration is more preferably 1% by volume or less, still more preferably 0.5% by volume or less, and particularly preferably 0.1% by volume or less.
The thickness of the formed optically anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and still more preferably 1 to 5 μm.

[Alignment film]
In order to align the liquid crystalline compound, it is preferable to use an alignment film.
If the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film is not necessary, and thus is not necessarily essential as a constituent member of the optical compensation film. That is, only the optically anisotropic layer on the alignment film in which the alignment state is fixed can be transferred onto the polymer film to produce the optical compensation film of the present invention.

  The alignment film has a function of defining the alignment direction of the liquid crystalline compound. The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Project method (LB film) Dioctadecylmethylammonium chloride, methyl stearylate) can be provided by means such as accumulation. Furthermore, an alignment film that generates an alignment function by applying an electric field, applying a magnetic field, or irradiating light is also known. The alignment film is preferably formed by polymer rubbing treatment.

Two or more kinds of polymers may be used in combination.
In order to ensure the durability with the optical compensation film, it is preferable to carry out a treatment for crosslinking the polymer of the alignment film at any stage after the alignment film is applied to the polymer film until the optical compensation film is obtained.
More preferably, the alignment film is formed by crosslinking two or more kinds of polymers and performing a rubbing treatment. As at least one kind of polymer, it is preferable to use a polymer which can be crosslinked by itself or a polymer which is crosslinked by a crosslinking agent.
The crosslinked structure can also be formed by reacting a polymer having a functional group between polymers by light, heat, or pH change. It is also possible to crosslink the polymer by using a compound having high reaction activity as a crosslinking agent and introducing a linking group derived from the crosslinking agent between the polymers.

Crosslinking of the polymer is carried out by applying an alignment film coating solution containing a polymer or a mixture of a polymer and a crosslinking agent on the polymer film and then performing a crosslinking reaction (for example, heating).
The polymer of the alignment film can be crosslinked by applying an alignment film coating solution on the polymer film and drying by heating. It is common to be done. It is preferable that the heating temperature of the coating solution is set low so that the alignment film is sufficiently cross-linked at the stage of the heat treatment when forming the optically anisotropic layer described later.
Considering the orientation of the optically anisotropic layer formed from the liquid crystalline compound on the alignment film, it is also preferable to carry out a treatment for sufficiently crosslinking the polymer of the alignment film after aligning the liquid crystalline compound.

Examples of the polymer used for the alignment film include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, polymaleimide, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylolacrylamide), gelatin, polyvinyl toluene, and chlorosulfonated. Examples include polyethylene, cellulose nitrate, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, polyvinyl acetate, polyvinyl chloride, carboxymethyl cellulose, polyethylene, polypropylene, and polycarbonate. Moreover, the polymer of an alignment film can also be formed from a coupling agent (eg, silane coupling agent).
A copolymer composed of two or more types of repeating units may be used. Examples of copolymers include acrylic acid / methacrylic acid copolymers, styrene / maleimide copolymers, styrene / vinyl toluene copolymers, vinyl acetate / vinyl chloride copolymers and ethylene / vinyl acetate copolymers. .
The polymer used for the alignment film is preferably a water-soluble polymer. The water-soluble polymer is preferably poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol, more preferably gelatin, polyvinyl alcohol and modified polyvinyl alcohol, and most preferably polyvinyl alcohol and modified polyvinyl alcohol. Particularly preferred is a modified polyvinyl alcohol to which a hydrophobic group is bonded.
It is also preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization.

The saponification degree of polyvinyl alcohol or modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and most preferably 85 to 95%. The degree of polymerization of polyvinyl alcohol or modified polyvinyl alcohol is preferably 100 to 3000.
The modified polyvinyl alcohol can be formed by copolymerization modification, chain transfer modification, or block polymerization modification.
Examples of the modifying group in the copolymerization modification include —COONa, —Si (OR) ₃ , —N (CH ₃ ) ₃ Cl, —C ₉ H ₁₉ , —COOR, —SO ₃ Na, and —C ₁₂ H _25. included. R is a hydrogen atom or an alkyl group.
Examples of the modifying group in the chain transfer modification, -COONa, include -SH and -C ₁₂ H _25.
Examples of the modifying group in the block polymerization modification include —COOH, —CONH ₂ , —COOR, and —C ₆ H ₅ . R is a hydrogen atom or an alkyl group.

  It is particularly preferable to use a compound represented by the following formula (II) as a modifying agent for polyvinyl alcohol.

In the formula (II), R ¹ is an alkyl group, an acryloylalkyl group, a methacryloylacrylic group, an acryloyloxyalkyl group, a methacryloyloxyacrylic group or an epoxyalkyl group; W is a halogen atom, an alkyl group or an alkoxy group X is an atomic group necessary for the compound represented by the formula (II) to form an active ester, an acid anhydride or an acid halide; l is 0 or 1, and n is It is an integer of 0-4.
More preferably, the polyvinyl alcohol modifier is represented by the following formula (III).

In the formula (III), X ¹ is an atomic group necessary for the compound represented by the formula (III) to form an active ester, an acid anhydride, or an acid halide; It is an integer of 24.
The modifier represented by the formula (II) can act on not only unmodified polyvinyl alcohol but also modified polyvinyl alcohol (copolymerization modification, chain transfer modification, block polymerization modification). Examples of the modified polyvinyl alcohol are described in JP-A-9-152509.
A method for synthesizing a modified polyvinyl alcohol, a method for measuring a visible absorption spectrum, and a method for determining the rate of introduction of a modifying group are described in JP-A-8-338913.

As the crosslinking agent, aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazoles, or dialdehyde starch can be used. Examples of aldehydes include formaldehyde, glyoxal and glutaraldehyde. Examples of N-methylol compounds include dimethylol urea and methylol dimethylhydantoin. Examples of the dioxane derivative include 2,3-dihydroxydioxane. Examples of compounds that act by activating the carboxyl group include carbenium, 2-naphthalenesulfonate, 1,1-bispyrrolidino-1-chloropyridinium and 1-morpholinocarbonyl-3- (sulfonatoaminomethyl). It is. Examples of active vinyl compounds include 1,3,5-triacroyl-hexahydro-s-triazine, bis (vinylsulfone) methane and N, N′-methylenebis- [β- (vinylsulfonyl) propionamide]. Examples of the active halogen compound include 2,4-dichloro-6-hydroxy-s-triazine. Two or more kinds of crosslinking agents may be used in combination.
The cross-linking agent is particularly effective for water-soluble polymers, particularly polyvinyl alcohol or modified polyvinyl alcohol. In view of productivity, aldehydes having high reaction activity, particularly glutaraldehyde is preferable.

When a large amount of the crosslinking agent is added, the moisture resistance of the alignment film is improved. When there is too much usage-amount of a crosslinking agent, the orientation function of an orientation film will fall. The amount of the crosslinking agent added to the polymer is preferably in the range of 0.1 to 20% by mass, and more preferably in the range of 0.5 to 15% by mass.
The alignment film contains a certain amount of a crosslinking agent that has not reacted even after the crosslinking reaction has been completed. The amount of the remaining crosslinking agent is preferably 1.0% by mass or less and more preferably 0.5% by mass or less in the alignment film. When the unreacted crosslinking agent is contained in the alignment film in an amount exceeding 1.0% by mass, the durability of the alignment film is lowered. That is, when an alignment film in which a large amount of the crosslinking agent remains is used in a liquid crystal display device, reticulation may occur when the device is used for a long time or left in a high temperature and high humidity atmosphere for a long time.

The alignment film can be formed by applying a solution containing a polymer or a solution containing a polymer and a crosslinking agent on a polymer film, followed by drying by heating (crosslinking) and rubbing treatment. The cross-linking reaction may be performed at any time after the coating solution is coated on the cellulose acetate film.
When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the solvent for preparing the coating liquid is an organic solvent having an antifoaming effect (eg, methanol), or an organic solvent and water. It is preferable to use a mixed solvent. When a mixed solvent of methanol and water is used, methanol in the mixed solvent is preferably 1% by mass or more, and more preferably 9% by mass or more. When methanol is used, generation of bubbles is suppressed, and defects on the surface of the alignment film and further on the optically anisotropic layer are remarkably reduced.
Examples of the coating method include a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, and a rod coating method. An extrusion coating method or a rod coating method is preferred, and an extrusion coating method is particularly preferred.

  The thickness of the alignment film is preferably in the range of 0.1 to 10 μm. The heat drying is preferably performed at a heating temperature in the range of 20 to 110 ° C, more preferably 60 to 100 ° C, and most preferably 80 to 100 ° C. The drying time is preferably 1 minute to 36 hours, more preferably 5 to 30 minutes. The pH of the coating solution is preferably set to an optimum value for the crosslinking agent to be used. When the crosslinking agent is glutaraldehyde, the pH is preferably in the range of 4.5 to 5.5, and particularly preferably pH 5.

  The rubbing process is the same as a method widely used in the manufacture of liquid crystal display devices. That is, the alignment function is obtained by rubbing the surface of the alignment film in a certain direction using paper, gauze, felt, rubber, nylon fiber or polyester fiber. Generally, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

[Retardation of optically anisotropic layer]
At least one of the absolute values of the in-plane retardation and the thickness direction retardation of the optically anisotropic layer is preferably 20 nm or more. Such a range is preferable because the influence of retardation fluctuation is easily detected.

[Polymer film]
The optical compensation film of the present invention has a polymer film that supports the optically anisotropic layer.
The transmittance of the polymer film included in the optical compensation film of the present invention is preferably 80% or more. Examples of the polymer constituting the film include cellulose ester (eg, cellulose acylate), norbornene polymer, polyacrylic acid ester, polymethacrylic acid ester (eg, polymethyl methacrylate), polycarbonate and polysulfone. Commercially available polymers (for Norbornene polymers, Arton and Zeonex) may be used.

A cellulose ester is preferred, and a lower fatty acid ester of cellulose is more preferred.
Lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used. Cellulose acetate is particularly preferred.
The acetylation degree of cellulose acetate is preferably 55.0 to 62.5%, and more preferably 57.0 to 62.0%.
The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation follows the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like).

  The viscosity average polymerization degree (DP) of the cellulose ester is preferably 250 or more, and more preferably 290 or more. The cellulose ester preferably has a narrow 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. The specific value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and most preferably 1.4 to 1.6. preferable.

In the cellulose ester, the hydroxyl groups at the 2nd, 3rd and 6th positions of cellulose are not evenly substituted, but the substitution degree of the 6th hydroxyl group tends to be small. In the present invention, it is preferable that the substitution degree of the 6-position hydroxyl group of cellulose is the same or greater than the 2-position and 3-position.
The ratio of the 6-position substitution degree to the total substitution degree at the 2nd, 3rd and 6th positions is preferably 30 to 40%, more preferably 31% or more, and most preferably 32% or more. . The 6-position substitution degree is preferably 0.88 or more.
The 6-position hydroxyl group may be substituted with an acyl group having 3 or more carbon atoms (eg, propionyl, butyryl, valeroyl, benzoyl, acryloyl) in addition to the acetyl group. The degree of substitution at each position can be determined by NMR.
Cellulose esters having a high degree of substitution at the 6-position are described in Synthesis Example 1 described in Paragraph Nos. 0043 and 0044, Synthesis Example 2 described in Paragraph Nos. 0048 and 0049, and Paragraph Nos. 0051 to 0052. It can be synthesized with reference to the method of Synthesis Example 3.

The Re retardation value and the Rth retardation value of the polymer film that is the support of the optically anisotropic layer are appropriately optimized depending on the method of the liquid crystal cell for optical compensation.
For example, in the case of the TN system, the Re value is adjusted to 0 to 20 nm, and the Rth value is adjusted to 70 to 400 nm.
When two optically anisotropic cellulose acetate films are used in the liquid crystal display device, the Rth retardation value of each film is preferably 70 to 250 nm.
In the OCB system, the Re value is adjusted to 20 to 70 nm, and the Rth value is adjusted to 150 to 600 nm.
When two optically anisotropic cellulose acetate films are used in a liquid crystal display device, the Rth retardation value of each film is preferably 150 to 300 nm.
In the case of a cellulose acetate film, the birefringence (Δn: nx−ny) is preferably (0.00) to (0.002). The birefringence Rth in the thickness direction of the cellulose acetate film is preferably (0.001) to (0.04).
Further, in the case of the ECB method, the Re value is adjusted to 0 to 20 nm, and the Rth value is adjusted to 0 to 70 nm.
When two optically anisotropic cellulose acetate films are used in a liquid crystal display device, the Rth retardation value of each film is preferably 0 to 40 nm.

  Substantially isotropic polymer films can also be used as the support. The retardation value can be adjusted by providing an optically anisotropic layer formed by fixing a rod-like liquid crystalline compound after horizontal or vertical alignment as described above on a substantially isotropic support. A positive A plate and a positive C plate can be produced, which is one of the preferred embodiments of the present invention. Similarly, as described above, by providing an optically anisotropic layer formed by fixing a discotic liquid crystalline compound after horizontal alignment or vertical alignment, a negative C plate having an adjustable retardation value, a negative An A plate can be produced, which is one of the preferred embodiments of the present invention.

  The substantially isotropic support preferably has an in-plane retardation (Re) of 0 to 20 nm, more preferably 0 to 10 nm, and most preferably 0 to 5 nm. The retardation in the thickness direction (Rth) is preferably -60 to 60 nm, preferably -40 to 40 nm, and most preferably -20 to 20 nm. The chromatic dispersion is preferably such that the ratio of Re (400) / Re (700) is less than 1.2.

[Manufacture of polymer film]
It is preferable to produce a polymer film by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which a polymer is dissolved in an organic solvent.
The organic solvent is a solvent selected from ethers having 2 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 2 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain.
The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic 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 the ether having 2 to 12 carbon atoms include dimethyl ether, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of the ketone having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the ester having 2 to 12 carbon atoms include methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  A typical example of the halogenated hydrocarbon having 1 to 6 carbon atoms is methylene chloride. Technically, halogenated hydrocarbons such as methylene chloride can be used without problems, but from the viewpoint of the global environment and working environment, the organic solvent preferably does not substantially contain halogenated hydrocarbons. “Substantially free” means that the proportion of halogenated hydrocarbon in the organic solvent is less than 5% by mass (preferably less than 2% by mass). Further, it is preferable that no halogenated hydrocarbon such as methylene chloride is detected from the produced cellulose acetate film.

Two or more organic solvents may be mixed and used. When a plurality of organic solvents are used in combination, an alcohol or hydrocarbon can be used in addition to the ether, ketone, ester or halogenated hydrocarbon.
The boiling point of the alcohol is preferably 30 to 170 ° C. The alcohol is preferably monovalent. The hydrocarbon portion of the alcohol may be branched or cyclic. The hydrocarbon moiety is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary.

  Examples of alcohols include methanol (boiling point: 64.65 ° C.), ethanol (78.325 ° C.), 1-propanol (97.15 ° C.), 2-propanol (82.4 ° C.), 1-butanol (117. 9 ° C), 2-butanol (99.5 ° C), t-butanol (82.45 ° C), 1-pentanol (137.5 ° C), 2-methyl-2-butanol (101.9 ° C), cyclo Hexanol (161 ° C.), 2-fluoroethanol (103 ° C.), 2,2,2-trifluoroethanol (80 ° C.), 2,2,3,3-tetrafluoro-1-propanol (109 ° C.), 1, 3-difluoro-2-propanol (55 ° C.), 1,1,1,3,3,3-hexa-2-methyl-2-propanol (62 ° C.), 1,1,1,3,3,3- Hexafluoro-2-pro Diol (59 ° C.), 2,2,3,3,3-pentafluoro-1-propanol (80 ° C.), 2,2,3,4,4,4-hexafluoro-1-butanol (114 ° C.), 2,2,3,3,4,4,4-heptafluoro-1-butanol (97 ° C.), perfluoro-tert-butanol (45 ° C.), 2,2,3,3,4,4,5, 5-octafluoro-1-pentanol (142 ° C.), 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (111.5 ° C.), 3,3,4,4, 5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol (95 ° C.), 2,2,3,3,4,4,5,5,6,6 7,7,8,8,8-pentadecafluoro-1-octanol (165 ° C.), 1- (pentafluorophenyl) Ethanol (82 ° C.) and 2,3,4,5,6-pentafluoro-benzyl alcohol (115 ° C.) are included.

  The boiling point of the hydrocarbon is preferably 30 to 170 ° C. The hydrocarbon may be branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be unsaturated. Examples of hydrocarbons include cyclohexane (boiling point: 80.7 ° C.), hexane (69 ° C.), benzene (80.1 ° C.), toluene (110.6 ° C.) and xylene (138.4-144.4 ° C.). Is included.

  When preparing the polymer solution, the container may be filled with an inert gas (eg, nitrogen gas). The viscosity of the polymer solution immediately before film formation may be in a range that allows casting during film formation. The viscosity is preferably in the range of 10 Pa · s to 2000 Pa · s, more preferably in the range of 30 Pa · s to 400 Pa · s.

A polymer solution can be prepared by a general method. A general method means processing at a temperature of 0 ° C. or higher (ordinary temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent.
The amount of the polymer is adjusted so that it is contained in an amount of 10 to 40% by mass in the obtained solution. The amount of the polymer is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring the polymer and the organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, the polymer and the organic solvent are put in a pressure vessel and sealed, and stirred while heating to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially.
The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in the container. The prepared dope is taken out of the container after cooling, or is taken out and then cooled using a means such as a heat exchanger.

A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, the polymer can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a polymer with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.
In the cooling dissolution method, first, a polymer is gradually added to an organic solvent with stirring at room temperature.
The amount of the polymer is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of the polymer is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice-methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). Upon cooling in this way, the mixture of polymer and organic solvent solidifies.
The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling until the final cooling temperature is reached.

Furthermore, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), the polymer dissolves in the organic solvent. The temperature can be raised by simply leaving it at room temperature or in a warm bath.
The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. .
A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.

In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.
In addition, according to differential scanning calorimetry (DSC), a 20 mass% solution obtained by dissolving cellulose acetate (acetylation degree: 60.9%, viscosity average polymerization degree: 299) in methyl acetate by a cooling dissolution method was 33. There exists a quasi-phase transition point between a sol state and a gel state in the vicinity of ° C., and a uniform gel state is obtained below this temperature. Therefore, it is necessary to keep this solution at a temperature equal to or higher than the pseudo phase transition temperature, preferably about 10 ° C. plus the gel phase transition temperature. However, this pseudo phase transition temperature varies depending on the degree of acetylation of cellulose acetate, the degree of viscosity average polymerization, the concentration of the solution, and the organic solvent used.

A polymer film is produced from the prepared polymer solution (dope) by a solvent cast method.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. The surface of the drum or band is preferably finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-115035.
The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less.
After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

Moreover, a polymer film may be produced by preparing a plurality of polymer solutions (dope) and casting two or more layers by a solvent cast method.
The dope is cast on a drum or 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 10 to 40% by mass. The surface of the drum or band is preferably finished in a mirror state.

  When casting a plurality of polymer solutions, a method of producing a film while casting and laminating a solution containing a polymer from a plurality of casting openings provided at intervals in the direction of travel of the support (JP-A-2009-101) 61-158414, JP-A-1-122419, and JP-A-11-198285). Also, a method for producing a film by casting a polymer solution from two casting ports (Japanese Patent Publication Nos. 60-27562, 61-94724, 61-947245, 61-104413, 61-158413 and JP-A-6-134933). Further, a polymer film casting method (described in JP-A-56-162617) in which a flow of a high-viscosity polymer solution is wrapped with a low-viscosity polymer solution and the high- and low-viscosity polymer solutions are simultaneously extruded can be employed.

Alternatively, two casting ports are used, the film cast on the support is peeled off by the first casting port, and the second casting is performed on the side in contact with the support surface to produce a film. Alternatively, a method (described in Japanese Patent Publication No. 44-20235) may be employed.
The plurality of polymer solutions to be cast may be the same solution. In order to give a function to a plurality of polymer layers, a polymer solution corresponding to the function may be extruded from each casting port.
The polymer solution for producing a film can be cast simultaneously with a coating solution for other functional layers (eg, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, and a polarizing film).

  In single layer casting, it is necessary to extrude a polymer solution with a high concentration and a high viscosity in order to obtain the required film thickness. In that case, the stability of the polymer solution may be poor, solid matter may be generated, causing a flaw or flatness. When a plurality of polymer solutions are cast from the casting port, a highly viscous solution can be simultaneously extruded onto the support, and the planarity is improved and an excellent planar film can be produced. Further, by using a concentrated polymer solution, a reduction in drying load can be achieved, and the production speed of the film can be increased.

A plasticizer can be added to the polymer film in order to improve the mechanical properties or to increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.
The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the polymer amount, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  A degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the polymer film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The addition amount of the deterioration preventing agent is preferably 0.01 to 1% by mass of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by mass. When the addition amount is less than 0.01% by mass, the effect of the deterioration preventing agent is hardly recognized. When the addition amount exceeds 1% by mass, bleed-out (bleeding) of the deterioration preventing agent to the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

  The polymer film may be provided with a mat layer containing a matting agent and a polymer on one side or both sides in order to improve handling during production. As the matting agent and polymer, materials described in JP-A-10-44327 can be preferably used.

The thickness of the polymer film is preferably 10 to 200 μm, more preferably 20 to 150 μm, and most preferably 30 to 140 μm.
The birefringence of the polymer film is preferably 0.00196 to 0.01375, more preferably 0.00168 to 0.006875, and most preferably 0.00275 to 0.00458 at 550 nm light.

[Stretching treatment]
The retardation of the polymer film can be adjusted by a stretching process.
The draw ratio (ratio of increase due to drawing relative to the original length) is preferably 3 to 100%, more preferably 5 to 80%, and most preferably 10 to 60%.

  The stretching treatment is preferably uniaxial stretching or biaxial stretching. Biaxial stretching includes simultaneous biaxial stretching and sequential biaxial stretching. That is, the stretching treatment is preferably performed by a lateral uniaxial stretching method, a longitudinal uniaxial stretching method, a simultaneous biaxial stretching method, or a sequential biaxial stretching method. For continuous production, a sequential biaxial stretching method is suitable. In the sequential biaxial stretching method, after the dope is cast on a band or a drum, the film is peeled off, stretched in the width direction (or the longitudinal method), and then stretched in the longitudinal direction (or the width direction).

Methods for stretching in the width direction are described in JP-A-62-115035, JP-A-4-152125, JP-A-4284221, JP-A-4-298310, and JP-A-11-48271. The film is stretched at room temperature or under heating conditions. The heating temperature is preferably not higher than the glass transition temperature of the film. You may implement the extending | stretching process of a film during a drying process. A special effect may be obtained by stretching the film with the solvent remaining.
In the case of stretching in the longitudinal direction, the film can be easily stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film stripping speed.
In the case of stretching in the width direction, the film can also be stretched by conveying while holding the width of the film with a tenter and gradually widening the width of the tenter. After drying the film, stretching using a stretching machine (preferably uniaxial stretching using a long stretching machine) can also be performed.

  The steps from casting to post-drying can be performed not in an air atmosphere but in an atmosphere of an inert gas (eg, nitrogen gas). A typical winder can be used for the production of the polymer film. As a winding method, a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress can be adopted.

[Polarizer]
The polarizing plate of the present invention has a polarizing film and the optical compensation film of the present invention. The polarizing plate generally has a polarizing film and two transparent protective films disposed on both sides thereof. As one protective film, the optical compensation film of the present invention may be used, or the optical compensation film of the present invention may be disposed on the surface of the transparent protective film. The other protective film may be a normal cellulose acetate film.
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.

  Further, the moisture permeability of the protective film is important for the productivity of the polarizing plate. The polarizing film and the protective film are bonded together with an aqueous adhesive, and the adhesive solvent is dried by diffusing in the protective film. The higher the moisture permeability of the protective film, the faster the drying and the higher the productivity. However, if the protective film is too high, moisture will enter the polarizing film depending on the usage environment (high humidity) of the liquid crystal display device. Polarization ability decreases.

[Liquid Crystal Display]
The liquid crystal display device of the present invention includes at least the optical compensation film of the present invention or the polarizing plate of the present invention. The liquid crystal display device of the present invention may be any of a reflection type, a semi-transmission type, a transmission type liquid crystal display device and the like. A liquid crystal display device generally includes a polarizing plate, a liquid crystal cell, and a retardation plate, a reflection layer, a light diffusion layer, a backlight, a front light, a light control film, a light guide plate, a prism sheet, a color filter, and the like as necessary. Although comprised from a member, in this invention, there is no restriction | limiting in particular except the point which makes it essential to use the polarizing plate of this invention. The liquid crystal cell is not particularly limited, and a general liquid crystal cell such as a liquid crystal layer sandwiched between a pair of transparent substrates provided with electrodes can be used. The transparent substrate constituting the liquid crystal cell is not particularly limited as long as the liquid crystal material constituting the liquid crystal layer is aligned in a specific alignment direction. Specifically, a transparent substrate in which the substrate itself has a property of orienting liquid crystals, a transparent substrate in which an alignment film having the property of orienting liquid crystals is provided, but the substrate itself lacks the alignment ability. Either can be used. Moreover, a well-known thing can be used for the electrode of a liquid crystal cell. Usually, it can be provided on the surface of the transparent substrate in contact with the liquid crystal layer, and when a substrate having an alignment film is used, it can be provided between the substrate and the alignment film. The material exhibiting liquid crystallinity for forming the liquid crystal layer is not particularly limited, and examples thereof include various ordinary low-molecular liquid crystalline compounds, high-molecular liquid crystalline compounds, and mixtures thereof that can constitute various liquid crystal cells. Moreover, a pigment | dye, a chiral agent, a non-liquid crystalline compound, etc. can also be added to these in the range which does not impair liquid crystallinity.

  In addition to the electrode substrate and the liquid crystal layer, the liquid crystal cell may include various components necessary for forming various types of liquid crystal cells described later. As the liquid crystal cell system, a TN (Twisted Nematic) system, a STN (Super Twisted Nematic) system, an ECB (Electrically Controlled Birefringence) system, an IPS (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, Alignment), PVA (Patterned Vertical Alignment), OCB (Optically Compensated Birefringence), HAN (Hybrid Aligned Nematic), ASM crocell) method, halftone gray scale method, domain division method, or display method using ferroelectric liquid crystal or antiferroelectric liquid crystal. The driving method of the liquid crystal cell is not particularly limited, and a passive matrix method used for STN-LCD and the like, and an active matrix method using an active electrode such as a TFT (Thin Film Transistor) electrode and a TFD (Thin Film Diode) electrode, Any driving method such as a plasma addressing method may be used. A field sequential method that does not use a color filter may be used.

The polarizing plate of the present invention is preferably used for reflective, transflective, and transmissive liquid crystal display devices. A reflective liquid crystal display device usually has a configuration in which a reflector, a liquid crystal cell, and a polarizing plate are laminated in this order. The retardation plate is disposed between the reflecting plate and the polarizing film (between the reflecting plate and the liquid crystal cell or between the liquid crystal cell and the polarizing film). The reflector may share the liquid crystal cell and the substrate. As the polarizing plate, the polarizing plate of the present invention can be used. In such a case, the retardation plate may not be separately provided.
The transflective liquid crystal display device includes a liquid crystal cell, a polarizing plate disposed on the viewer side of the liquid crystal cell, and at least one retardation plate disposed between the polarizing plate and the liquid crystal cell. And at least one transflective layer disposed behind the liquid crystal layer as viewed from the viewer, and at least one retardation plate and polarizing plate behind the transflective layer as viewed from the viewer And have. In this type of liquid crystal display device, it is possible to use both a reflection mode and a transmission mode by installing a backlight. Both polarizing plates may be the polarizing plate of the present invention, or only one of them may be the polarizing plate of the present invention. When the polarizing plate of the present invention is arranged, a retardation plate may not be separately arranged between the liquid crystal cell and the polarizing plate of the present invention.

The mode of the liquid crystal cell is not particularly limited, but is preferably an IPS mode or an FFS mode.
In an IPS mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially parallel to the substrate, and the liquid crystal molecules respond in a planar manner when an electric field parallel to the substrate surface is applied. In the IPS mode, black is displayed when no electric field is applied, and the transmission axes of the pair of upper and lower polarizing plates are orthogonal. A method of reducing leakage light at the time of black display in an oblique direction and improving a viewing angle using an optical compensation film is disclosed in JP-A-10-54982, JP-A-11-202323, and JP-A-9-292522. No. 11-133408, No. 11-305217, No. 10-307291, and the like.

  For example, the polarizing plate of the present invention has a pair of substrates and a liquid crystal cell (for example, a liquid crystal layer in which liquid crystal molecules sandwiched between the pair of substrates are aligned substantially parallel to the substrate during black display (for example, When using for a liquid crystal display device having an IPS mode liquid crystal cell), an optically anisotropic layer, a biaxial polymer film as a support, from the substrate side to the outside of one of the pair of substrates, and The polarizing plate is arranged in this order, and the polarizing plate is arranged so that the slow axis of the polymer film and the major axis direction of the liquid crystal molecules at the time of black display are substantially parallel, and outside the other substrate. Further, a second polarizing layer can be disposed. In this case, the absorption axes of both polarizing layers are arranged orthogonal to each other.

  Further, the polarizing plate of the present invention includes a liquid crystal cell having a pair of substrates and a liquid crystal layer in which liquid crystal molecules sandwiched between the pair of substrates are aligned substantially parallel to the substrate during black display (for example, When used in a liquid crystal display device having an IPS mode liquid crystal cell), a biaxial polymer film as a support, an optically anisotropic layer, and an outer side of one of the pair of substrates from the substrate side, and The polarizing plate is arranged in this order, and the polarizing plate is disposed so that the slow axis of the polymer film and the major axis direction of the liquid crystal molecules at the time of black display are substantially orthogonal, and further on the outside of the other substrate. A second polarizing layer can be disposed. In this case, the absorption axes of both polarizing layers are arranged orthogonal to each other. Also in this case, the absorption axes of both polarizing layers are arranged to be orthogonal to each other.

  In any of the above embodiments, only a substantially isotropic adhesive layer and / or a substantially isotropic transparent protective film is included between the second polarizing layer and the substrate. It is preferable. Specifically, the substantially isotropic transparent protective film has an in-plane retardation of 0 to 10 nm and a retardation in the thickness direction of -20 to 20 nm. For example, cellulose having such optical properties Films containing acylates or cyclic polyolefins are preferred.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
First, a cellulose acylate film having optical biaxiality is used as a base material, and a rod-like liquid crystal compound molecule having a polymerizable group is vertically aligned thereon, and then has an optically anisotropic layer formed by fixing by polymerization. The present invention will be described using an optical compensation film as an example.

(Preparation of cellulose acylate film T1)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

──────────────────────────────────
Cellulose acetate solution composition ──────────────────────────────────
Cellulose acetate having an acetylation degree of 60.9% (degree of polymerization: 300, Mn / Mw = 1.5) 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (second solvent) 54 parts by weight 1-butanol (third solvent) 11 parts by weight ──────────────────── ──────────────

  In another mixing tank, 16 parts by mass of the above-mentioned retardation increasing agent A, 8 parts by mass of the following retardation increasing agent B, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), methylene chloride 80 parts by mass and 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution (and a fine particle dispersion). The dope was prepared by mixing 45 parts by mass of the retardation increasing agent solution with 474 parts by mass of the cellulose acetate solution and stirring sufficiently.

Retardation increasing agent (A)

Retardation raising agent B

  The obtained dope was cast using a casting machine having a band having a width of 2 m and a length of 65 m. A film having a residual solvent amount of 15% by mass was stretched transversely at a stretch ratio of 20% using a tenter under the conditions of 130 ° C., held at 50 ° C. for 30 seconds with the stretched width, and then clipped to remove cellulose. An acetate film was prepared. The residual solvent amount at the end of stretching was 5% by mass, and further dried to prepare a cellulose acetate film (T1) with the residual solvent amount being less than 0.1% by mass. In addition, Tg of the used cellulose acylate is 140 degreeC.

  The resulting cellulose acetate film (T1) had a width of 1340 mm and a thickness of 88 μm. When the in-plane retardation (Re) at a wavelength of 590 nm was measured, it was 60 nm. The retardation (Rth) in the thickness direction was 190 nm.

The produced film was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C., and then an alkaline solution A having the following composition was applied by a bar coater to 14 ml / m ² and heated to 110 ° C. After retaining for 10 seconds under a heated steam far infrared heater (manufactured by Noritake Co., Ltd.), 3 ml / m ^{2 of} pure water was applied using a bar coater. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was retained in a drying zone at 70 ° C. for 2 seconds and dried.

――――――――――――――――――――――――――――――――――
<Alkaline solution A composition>
――――――――――――――――――――――――――――――――――
Potassium hydroxide 4.7 parts by weight Water 15.7 parts by weight Isopropanol 64.8 parts by weight Propylene glycol 14.9 parts by weight C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H (surfactant) 1.0 mass Department ――――――――――――――――――――――――――――――――――

(Preparation of optically anisotropic layer)
On the surface of the long cellulose acylate film (T1) produced as described above, an alignment film coating solution having the following composition was continuously applied with a # 14 wire bar. The alignment film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds.
――――――――――――――――――――――――――
Composition of alignment film coating solution ――――――――――――――――――――――――――
The following modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight ――――――――――――――――――――――――――――

  A coating solution containing a rod-like liquid crystal compound having the following composition was continuously applied onto the prepared alignment film with a # 5.0 wire bar. The conveyance speed of the film was 20 m / min. The solvent was dried in a step of continuously heating from room temperature to 80 ° C., and then heated in a drying zone at 80 ° C. for 90 seconds to align the rod-like liquid crystal compound. Subsequently, the orientation of the liquid crystal compound is fixed by UV irradiation while maintaining the temperature of the film at 60 ° C. and the oxygen concentration is controlled to 0.1% by volume or less under a nitrogen purge, and the optically anisotropic layer B1 And an optical compensation film F10 was produced.

  Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F10, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 0 nm, and Rth was −260 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface was formed.

――――――――――――――――――――――――――――――――――――
Composition of coating liquid (S1) containing rod-like liquid crystal compound ――――――――――――――――――――――――――――――――――――
The following rod-like liquid crystalline compound A 100 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 3 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass The following fluoropolymer 0 4 parts by weight The following pyridinium salt 1 part by weight Methyl ethyl ketone 172 parts by weight ――――――――――――――――――――――――――――――――――――― -

Rod-shaped liquid crystal compound A

<Preparation of optical compensation film F11>
The surface of the optical compensation film F10 produced above, on which the optically anisotropic layer is not laminated, is passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature is raised to 40 ° C. Solution A was applied with a bar coater at 14 ml / m ² and allowed to stay for 10 seconds under a steam far-infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., and then purified water using the same bar coater. 3 ml / m ^{2 was} applied. The film temperature at this time was 40 degreeC. Next, water washing with a fountain coater and water draining with an air knife were repeated three times, and after drying for 2 seconds in a drying zone at 70 ° C., the surface of the optical compensation film F10 on which the optically anisotropic layer was not laminated was saponified. A saponified optical compensation film F11 was prepared.

<Preparation of optical compensation film F12>
The optical compensation film F10 produced above was immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 2 minutes, and then immersed in water to sufficiently wash away sodium hydroxide. Then, after being immersed for 1 minute in 5 mmol / L sulfuric acid aqueous solution of 35 degreeC, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C. In this way, a saponified optical compensation film F12 was produced.

<Preparation of optical compensation film F13>
The optical compensation film F10 produced above was immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 4 minutes, and then immersed in water to sufficiently wash out sodium hydroxide. Then, after being immersed for 1 minute in 5 mmol / L sulfuric acid aqueous solution of 35 degreeC, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C. In this way, a saponified optical compensation film F13 was produced.

<Preparation of optical compensation film F20>
The rod-like liquid crystal compound A in the coating liquid (S1) containing the rod-shaped liquid crystal compound with respect to the optical compensation film F10 produced above is replaced with the following rod-shaped liquid crystal compound B (coating solution (S2) containing the rod-shaped liquid crystal compound), An optical compensation film F20 was produced.

Rod-shaped liquid crystal compound B

<Production of optical compensation films F21 to F23>
Saponified optical compensation films F21 to F23 were produced by replacing the optical compensation film F10 before saponification treatment with the optical compensation film F20 with respect to the saponified optical compensation films F11 to F13 produced above.

<Preparation of optical compensation film F30>
The rod-shaped liquid crystal compound A in the coating liquid (S1) containing the rod-shaped liquid crystal compound with respect to the optical compensation film F10 produced above is replaced with the following rod-shaped liquid crystal compound C (coating liquid containing the rod-shaped liquid crystal compound (S3)), An optical compensation film F30 was produced.

Rod-shaped liquid crystal compound C

<Preparation of optical compensation films F31 to F33>
Saponified optical compensation films F31 to F33 were produced by replacing the optical compensation film F10 before the saponification treatment with the optical compensation film F30 for the saponified optical compensation films F11 to F13 produced above.

Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled off from the produced optical compensation films F10 to F13, F20 to F23, and F30 to F33, and an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments) The optical properties were measured using The results are shown in Table 1. Re was all 0 nm, and it was confirmed from this that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface was confirmed.
Moreover, the surface free energy of the surface (back surface) on which the optically anisotropic layer was not laminated was calculated based on the measurement of the contact angle. The results are shown in Table 1.

From the results shown in Table 1, the following is clear. An optically anisotropic layer in which an optically anisotropic layer is formed using a rod-shaped liquid crystal compound C in which a liquid crystalline part is a benzoic acid ester having an ester bond as a rod-shaped liquid crystal compound and a linking group to a polymerizable group is an ester bond The retardation value (in-plane retardation Rth) of the conductive film F30 varies greatly due to the saponification treatment.
In contrast, an optically anisotropic film F20 in which an optically anisotropic layer is formed using a rod-like liquid crystal compound B containing no ester bond as a rod-like liquid crystal compound has a retardation value of in-plane retardation Re and thickness by saponification treatment. The retardation value Rth in the vertical direction did not vary.
In addition, the optically anisotropic film F10 in which an optically anisotropic layer is formed using the rod-like liquid crystalline compound A containing an ester bond as the rod-like liquid crystalline compound and simultaneously containing a naphthalene ring is not changed in retardation value by saponification treatment. There wasn't.

[Example 2]
<Preparation of polarizing plates (P11 to P13, P21 to P23, P31 to P33)>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a long polarizing film. The surface of the polarizing film on which the optically anisotropic layer of the optical compensation film F11 is not formed is formed on one side of the polarizing film, and the cellulose triacetate film (Fujitack TD80UL, Fuji Photo Film) whose surface is saponified on the other side. (Made by Co., Ltd.) was continuously pasted using a polyvinyl alcohol-based adhesive to produce a long polarizing plate P11. At this time, the absorption axis of the polarizing film was parallel to the longitudinal direction, and the angle formed by the absorption axis of the polarizing film and the slow axis of the cellulose acylate film was 90 °.
Similarly, the optical compensation film F11 was changed to the optical compensation films F12 to F13, F21 to F23, and F31 to F33, and long polarizing plates P12 to P13, P21 to P23, and P31 to P33 were produced.

[Example 3]
<Production of cellulose acetate film (T0)>
(Preparation of cellulose acetate solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution A.
―――――――――――――――――――――――――――――――――――
Composition of cellulose acetate solution A ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.94 100.0 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass ――――――――――――― ――――――――――――――――――――――

(Preparation of matting agent solution)
20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were mixed well for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution.
―――――――――――――――――――――――――――――――――
Matting agent solution composition ――――――――――――――――――――――――――――――――――
Silica particle dispersion with an average particle size of 16 nm 10.0 parts by weight Methylene chloride (first solvent) 76.3 parts by weight Methanol (second solvent) 3.4 parts by weight Cellulose acetate solution A 10.3 parts by weight ―――――――――――――――――――――――――――――

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
――――――――――――――――――――――――――――――
Additive solution composition ――――――――――――――――――――――――――――――
The following optical anisotropy reducing agent 49.3 parts by mass The following wavelength dispersion adjusting agent 4.9 parts by mass Methylene chloride (first solvent) 58.4 parts by mass Methanol (second solvent) 8.7 parts by mass Cellulose acetate Solution A 12.8 parts by mass ――――――――――――――――――――――――――――――

(Production of cellulose acetate film)
94.6 parts by mass of the cellulose acetate solution A, 1.3 parts by mass of the matting agent solution, and 4.1 parts by mass of the additive solution were mixed after filtration, and cast using a band casting machine. The mass ratio of the compound that reduces optical anisotropy and the wavelength dispersion adjusting agent to cellulose acetate in the above composition was 12% and 1.2%, respectively. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a long cellulose acetate film T0 having a thickness of 80 μm. The in-plane retardation (Re) of the obtained film was 1 nm (the slow axis was a direction perpendicular to the film longitudinal direction), and the thickness direction retardation (Rth) was −1 nm.

<Production of Polarizing Plate (P0)>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a long polarizing film. A polyvinyl alcohol-based adhesive was prepared by using the cellulose acetate film T0 saponified on one side of the polarizing film and a commercially available cellulose acetate film (Fujitac TD80UL, manufactured by Fuji Photo Film Co., Ltd.) on the other side. Was continuously bonded together to produce a polarizing plate P0.

[Example 4]
<Production of liquid crystal display devices (L11 to L13, L21 to L23, L31 to L33)>
The liquid crystal cell was taken out from the liquid crystal television TH-32LX500 (manufactured by Matsushita Electric Industrial Co., Ltd.), and the polarizing plate and the optical film which were pasted on the viewer side and the backlight side were peeled off. In this liquid crystal cell, when no voltage was applied and during black display, the liquid crystal molecules were aligned substantially in parallel between the glass substrates, and the slow axis direction was horizontal to the screen.

  The produced polarizing plates (P11 and P0) were bonded to the glass substrates above and below the parallel alignment cell using an adhesive. At this time, P11 is disposed on the polarizing plate on the backlight side, P0 is disposed on the viewing side, and the optically anisotropic layer included in the polarizing plate P11 is in contact with the glass substrate on the backlight side. The cellulose acetate film T0 contained in P0 was bonded so as to be in contact with the glass substrate on the viewing side. Further, the polarizing plate P11 and the polarizing plate P0 were arranged so that the absorption axis of the polarizing plate P11 and the slow axis of the liquid crystal cell were orthogonal to each other, and the absorption axes of the polarizing plate P11 and the polarizing plate P0 were orthogonal. In this way, a liquid crystal display device L11 was produced.

The polarizing plate P11 was changed to polarizing plates P12 to P13, P21 to P23, and P31 to P33, respectively, to prepare liquid crystal display devices L12 to L13, P21 to P23, and P31 to P33.
In the liquid crystal display devices L12 to L13, L21 to L23, and L31 to L33, the liquid crystal cell, the optically anisotropic layer, the cellulose acylate film, and the polarizing layer are in this order, and the optical anisotropy of the cellulose acylate film. The slow axis of the layer and the major axis direction of the liquid crystal molecules during black display were substantially parallel.

  The liquid crystal display devices L11 to L13, L21 to L23 and the liquid crystal display devices L31 to L33 were evaluated for oblique leakage light and dark room contrast by the following methods, and are summarized in Table 3.

(1) Diagonal leakage light Place the liquid crystal cell 1 on the Schacus Ten set in the dark room without attaching the polarizing plate so that the substrate on which the electrode is disposed is on the Schaukasten side, and use the rubbing direction of the liquid crystal cell as a reference Luminance meter (spectral radiance meter CS-1000: manufactured by Minolta Co., Ltd.) installed at an angle of 45 degrees to the left and 1 m away from the normal direction of the liquid crystal cell at 60 degrees. 1 was measured.
Then, each liquid crystal display device having a polarizing plate bonded on the same Schaukasten as described above was placed, and the luminance 2 was measured in the same manner as described above.

(2) Dark room contrast Each liquid crystal display device in which a polarizing plate is bonded to a Schaukasten set in a dark room is placed so that the substrate on which the electrode is placed is on the Schaukasten side, and the normal direction of the liquid crystal cell The contrast ratio, which is the luminance ratio (white display / black display), was measured with a luminance meter (spectral radiance meter CS-1000: manufactured by Minolta Co., Ltd.) installed at a distance of 1 m.

From the results in Table 3, the following is clear.
In the liquid crystal display device mounted with the saponification product of the optical compensation film F30 in which the retardation value of the optically anisotropic layer is changed by the saponification treatment, as the optical anisotropic layer is saponified for a longer time, the contrast decreases and the leakage light There is an increase.
On the other hand, in the liquid crystal display device equipped with the saponification products of the optical compensation films F10 and F20 in which the retardation value of the optically anisotropic layer was not changed by the saponification treatment, the optical anisotropic layer was saponified longer. In contrast, the optically anisotropic layer is good in terms of contrast and leakage light as compared with the case where the optically anisotropic layer is not saponified.

[Example 5]
Next, an optical compensation film having optical anisotropy formed by vertically aligning a rod-like liquid crystalline compound on a cellulose acylate film substantially free of retardation and then fixing by polymerization (the retardation value does not change due to saponification treatment) Positive C plate).

Cellulose acylate film (T0) produced in Example 3 The produced film was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C. After coating with a coater at 14 ml / m ² and heating for 10 seconds under a steam far infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., 3 ml / m of pure water was also used using a bar coater. ² applied. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was retained in a drying zone at 70 ° C. for 2 seconds and dried. This is designated as a cellulose acylate film (T10).

  The alignment film coating solution used in Example 1 was continuously applied with a # 14 wire bar to the surface of the long cellulose acylate film (T10) produced above and subjected to a saponification treatment. The alignment film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds.

  The coating liquid (S2) containing the rod-like liquid crystal compound used in the production of the optical compensation film F20 of Example 1 was continuously applied on the alignment film prepared above with a wire bar of # 4.5. The conveyance speed of the film was 20 m / min. The solvent was dried in a step of continuously humidifying from room temperature to 80 ° C., and then heated in a drying zone at 80 ° C. for 90 seconds to align the rod-like liquid crystal compound. Subsequently, the humidity of the film was maintained at 60 ° C., the orientation of the liquid crystalline compound was fixed by UV irradiation, the optical anisotropic layer B2 was formed, and an optical film F40 was produced.

  Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F40, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 0 nm, and Rth was −230 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface was formed.

<Preparation of optical compensation film F41>
The surface on which the optically anisotropic layer of the optical compensation film F40 prepared above is laminated is passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature is raised to 40 ° C. Was applied with a bar coater at a rate of 14 ml / m ² and kept for 10 seconds under a steam far infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., and then 3 ml of pure water using the same bar coater. / M ^{2 was} applied. The film temperature at this time was 40 degreeC. Next, water washing with a fountain coater and water draining with an air knife were repeated three times, and then the film was retained in a drying zone at 70 ° C. for 2 seconds and dried, and the surface on which the optically anisotropic layer of the optical compensation film F40 was laminated was treated with an alkali solution. An optical compensation film F41 was produced.

  Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F41, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 0 nm, and Rth was −230 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface was formed.

<Preparation of optical compensation film F42>
The optical compensation film F40 produced above was immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 4 minutes, and then immersed in water to sufficiently wash out sodium hydroxide. Then, after being immersed for 1 minute in 5 mmol / L sulfuric acid aqueous solution of 35 degreeC, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C. In this way, an optical compensation film F42 was produced.

Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F42, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 0 nm, and Rth was −230 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface was formed.
Further, when the surface free energy of the surface of the optical compensation film F42 on which the optically anisotropic layer was not laminated was measured, it was 65 mN / m.

From the above results, the following is clear.
By providing an optically anisotropic layer prepared by vertically aligning and fixing a polymerizable rod-like liquid crystalline compound on a substantially isotropic support, a positive change without retardation change by saponification treatment. C plate can be produced.

[Example 6]
Next, an optical compensation film having optical anisotropy formed by horizontal alignment of a rod-like liquid crystalline compound on a cellulose acylate film substantially free of retardation and then fixed by polymerization (a positive value with adjustable retardation value) (Example of A plate) is shown.

(Formation of alignment film)
On one surface of the cellulose acylate film (T10) produced in Example 5, 26.3 ml / m ² of a coating solution having the following composition was applied with a # 15 wire bar coater.

───────────────────────────────────
Alignment film coating solution composition ───────────────────────────────────
Polymer compound P described below 4 parts by mass Triethylamine 2 parts by mass 5% aqueous solution of DECONAL EX-521 8.1 parts by mass (epoxy compound of Nagase Kasei Kogyo Co., Ltd.)
Water 57 parts by mass Methanol 29 parts by mass───────────────────────────────────

Polymer compound P

  Drying was performed at 25 ° C. for 30 seconds and 120 ° C. warm air for 120 seconds. The thickness of the alignment film after drying was 1.0 μm. Further, the surface roughness of the alignment film was measured with an atomic force microscope (AFM: Atomic Force Microscope, SPI3800N, manufactured by Seiko Instruments Inc.) and found to be 1.135 nm. Next, the formed film was rubbed in the longitudinal direction of the cellulose acylate film (T0).

(Formation of optically anisotropic layer)
An optically anisotropic layer was formed on this alignment film. Specifically, a coating solution having the following composition is coated on the alignment film with a bar coater, dried at 40 ° C. for 30 seconds, then heated at 85 ° C. (alignment aging), and further irradiated with ultraviolet rays. A horizontally oriented optically anisotropic layer having a thickness of 0.7 μm was formed. This was designated as an optical compensation film F50.

───────────────────────────────────
Coating composition for optically anisotropic layer ────────────────────────────────────
Rod-like liquid crystalline compound B 26.2 parts by mass The following sensitizer A 0.32 parts by mass The following photopolymerization initiator B 0.96 parts by mass Orientation controller C 0.19 parts by mass Glutaraldehyde 0.04 parts by mass Cyclohexanone 72.29 parts by mass ───────────────────────────────────

Sensitizer A

Photoinitiator B

Orientation control agent C

  Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F50, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 60 nm, and Rth was 30 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially horizontally with respect to the film surface was confirmed.

<Preparation of optical compensation film F51>
The surface on which the optically anisotropic layer of the optical compensation film F50 prepared above is laminated is passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature is raised to 40 ° C., and then the alkali solution A having the above composition is used. Was applied with a bar coater at a rate of 14 ml / m ² and kept for 10 seconds under a steam far infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., and then 3 ml of pure water using the same bar coater. / M ^{2 was} applied. The film temperature at this time was 40 degreeC. Next, water washing with a fountain coater and water draining with an air knife are repeated three times, followed by dwelling in a drying zone at 70 ° C. for 2 seconds to dry, and the surface on which the optically anisotropic layer of the optical compensation film F50 is laminated is treated with an alkali solution, An optical compensation film F51 was produced.

  Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F51, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 60 nm, and Rth was 35 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially perpendicular to the film surface was formed.

<Preparation of optical compensation film F52>
The optical compensation film F50 prepared above was immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 4 minutes, and then immersed in water to sufficiently wash out sodium hydroxide. Then, after being immersed for 1 minute in 5 mmol / L sulfuric acid aqueous solution of 35 degreeC, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C. In this way, an optical compensation film F52 was produced.

Only the optically anisotropic layer containing the rod-like liquid crystalline compound was peeled from the produced optical compensation film F52, and the optical characteristics were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). . Re of only the optically anisotropic layer measured at a wavelength of 590 nm was 60 nm, and Rth was 30 nm. It was also confirmed that an optically anisotropic layer in which rod-like liquid crystal molecules were aligned substantially horizontally with respect to the film surface was confirmed.
Further, when the surface free energy of the surface on which the optically anisotropic layer on the back surface of the optical compensation film F52 was not laminated was measured, it was 66 mN / m.

From the above results, the following is clear.
By providing an optically anisotropic layer prepared by vertically aligning and fixing the polymerizable rod-like liquid crystalline compound of the present invention on a substantially isotropic support, the retardation value fluctuates during saponification treatment. Positive A plates can be made.

Claims (13)

  An optical compensation film having an optically anisotropic layer made of a composition containing at least a liquid crystal compound on a plastic film, the optical compensation film being placed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. The optical compensation film is characterized in that the amount of change in both in-plane retardation Re and thickness direction retardation Rth of the optically anisotropic layer is 3 nm or less after 2 minutes of immersion.   2. The optical compensation film according to claim 1, wherein an absolute value of at least one of Re and Rth of the optically anisotropic layer is 20 nm or more.   The liquid crystalline compound has a polymerizable group, and the optically anisotropic layer is a layer formed by aligning molecules of the liquid crystalline compound having the polymerizable group and then fixing by polymerization. The optical compensation film according to claim 1, wherein the optical compensation film is a film.   The optical compensation film according to any one of claims 1 to 3, wherein the liquid crystal compound is a polymerizable liquid crystal compound having 1 to 3 functional polymerizable groups per molecule.   The optical compensation film according to claim 1, wherein the liquid crystal compound is a rod-like liquid crystal compound.   6. The optical compensation film according to claim 5, wherein in the optically anisotropic layer, the molecules of the rod-like liquid crystalline compound are fixed in a vertical alignment state or a horizontal alignment state.   The optical compensation according to any one of claims 1 to 6, wherein the liquid crystal compound is a compound that does not contain a divalent group that can be cleaved by hydrolysis at the liquid crystal site or contains only one of them. the film.   The liquid crystal compound is a compound that includes a divalent group that can be cleaved by hydrolysis at a liquid crystal site, and a condensed ring structure in which at least one group linked through the divalent group is composed of two or more rings. The optical compensation film according to claim 1, wherein the optical compensation film is provided.   The optical compensation film according to claim 7 or 8, wherein the linking group cleavable by hydrolysis is an ester group (-C (= (O) O-).   10. The film according to claim 1, wherein the polymer film is a film formed by stretching by a lateral uniaxial stretching method, a longitudinal uniaxial stretching method, a simultaneous biaxial stretching method, or a sequential biaxial stretching method. The optical compensation film described.   The optical compensation film according to claim 1, wherein the polymer film is a cellulose acylate film.   A polarizing plate comprising the optical compensation film according to claim 1.   A liquid crystal display device comprising the optical compensation film according to claim 1 or the polarizing plate according to claim 12.